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Sample records for o-nitrosyl carboxylate compounds

  1. Boron-containing amino carboxylic acid compounds and uses thereof

    DOEpatents

    Kabalka, George W.; Srivastava, Rajiv R.

    2000-03-14

    Novel compounds which are useful for boron neutron capture therapy (BNCT) are disclosed. The compounds comprise a stable boron-containing group and an aminocycloalkane carboxylic acid group or a boronated acyclic hydrocarbon-linked amino carboxylic acid. Methods for synthesis of the compounds and for use of the compounds in BNCT are disclosed.

  2. Amino Acids, Aromatic Compounds, and Carboxylic Acids: How Did They Get Their Common Names?

    ERIC Educational Resources Information Center

    Leung, Sam H.

    2000-01-01

    Surveys the roots of the common names of organic compounds most likely to be encountered by undergraduate organic chemistry students. Includes information for 19 amino acids, 17 aromatic compounds, and 21 carboxylic acids. (WRM)

  3. Copper-catalyzed formal C - H carboxylation of aromatic compounds with carbon dioxide through arylaluminum intermediates.

    PubMed

    Ueno, Atsushi; Takimoto, Masanori; O, Wylie W N; Nishiura, Masayoshi; Ikariya, Takao; Hou, Zhaomin

    2015-04-01

    The C - H bond carboxylation of various aromatic compounds with CO2 was achieved by the deprotonative alumination with a mixed alkyl amido lithium aluminate compound iBu3 Al(TMP)Li followed by the NHC-copper-catalyzed carboxylation of the resulting arylaluminum species, which afforded the corresponding carboxylation products in high yield and high selectivity. In addition to benzene derivatives, heteroarenes such as benzofuran, benzothiophene, and indole derivatives are also suitable substrates. Functional groups such as Cl, Br, I, vinyl, amide, and CN could survive the reaction conditions. Some key reaction intermediates such as the copper aryl and isobutyl complexes and their carboxylation products were isolated and structurally characterized by X-ray crystallographic analyses, thus offering important information on the reaction mechanism. PMID:25491488

  4. Aggregation of asphaltene model compounds using a porphyrin tethered to a carboxylic acid.

    PubMed

    Schulze, Matthias; Lechner, Marc P; Stryker, Jeffrey M; Tykwinski, Rik R

    2015-07-01

    A Ni(II) porphyrin functionalized with an alkyl carboxylic acid (3) has been synthesized to model the chemical behavior of the heaviest portion of petroleum, the asphaltenes. Specifically, porphyrin 3 is used in spectroscopic studies to probe aggregation with a second asphaltene model compound containing basic nitrogen (4), designed to mimic asphaltene behavior. NMR spectroscopy documents self-association of the porphyrin and aggregation with the second model compound in solution, and a Job's plot suggests a 1 : 2 stoichiometry for compounds 3 and 4. PMID:26024486

  5. IDENTIFICATION AND QUANTIFICATION OF AEROSOL POLAR OXYGENATED COMPOUNDS BEARING CARBOXYLIC AND/OR HYDROXYL GROUPS. 1. METHOD DEVELOPMENT

    EPA Science Inventory

    In this study, a new analytical technique was developed for the identification and quantification of multi-functional compounds containing simultaneously at least one hydroxyl or one carboxylic group, or both. This technique is based on derivatizing first the carboxylic group(s) ...

  6. ESTIMATION OF HYDROLYSIS RATE CONSTANTS OF CARBOXYLIC ACID ESTER AND PHOSPHATE ESTER COMPOUNDS IN AQUEOUS SYSTEMS FROM MOLECULAR STRUCTURE BY SPARC

    EPA Science Inventory

    SPARC (SPARC Performs Automated Reasoning in Chemistry) chemical reactivity models were extended to calculate hydrolysis rate constants for carboxylic acid ester and phosphate ester compounds in aqueous non- aqueous and systems strictly from molecular structure. The energy diffe...

  7. Selective deuteration of (hetero)aromatic compounds via deutero-decarboxylation of carboxylic acids.

    PubMed

    Grainger, Rachel; Nikmal, Arif; Cornella, Josep; Larrosa, Igor

    2012-04-28

    A practical, mild and highly selective protocol for the monodeuteration of a variety of arenes and heteroarenes is presented. Catalytic amounts of Ag(I) salts in DMSO/D(2)O are shown to facilitate the deutero-decarboxylation of ortho-substituted benzoic and heteroaromatic α-carboxylic acids in high yields with excellent levels of deuterium incorporation. PMID:22418863

  8. High stability and high efficiency chemiluminescent acridinium compounds obtained from 9-acridine carboxylic esters of hydroxamic and sulphohydroxamic acids.

    PubMed

    Renotte, R; Sarlet, G; Thunus, L; Lejeune, R

    2000-01-01

    A series of hydroxamic acids and sulphohydroxamic acids were prepared and linked to 9-acridinecarboxylic acid through a pseudo-ester function. After N-methylation of the heterocyclic ring, the different compounds were tested for their chemiluminescent properties. Substituents on the hydroxamic functions have shown various effects (steric or electronic) on the luminescence yield or stability of the molecule. The most interesting derivatives were selected in terms of chemical stability and chemiluminescence efficiency. 9-[(N-hydroxysuccinimidyl-4-oxo-4-N-phenylaminobutanoate)N-carb oxylat e]-10-methyl-acridinium (FA6), 9-(N-phenylpivalamide-N-carboxylate)-10-methylacridinium (FA17) and 9-(N-phenylpivalamide N-carboxylate)-10-carboxymethyl-acridinium (FA18) iodomercurates are very promising as chemiluminescent labels. These compounds can be detected at very low levels (10(-16)-10(-17) mol/L) and in our stability evaluation, FA6, FA17 and FA18 showed similar results to the acridinium ester DMAE. Their half-lives at 20 degrees C are greater than 2 weeks. PMID:11038489

  9. Novel Antiphytopathogenic Compound 2-Heptyl-5-Hexylfuran-3-Carboxylic Acid, Produced by Newly Isolated Pseudomonas sp. Strain SJT25 ▿†

    PubMed Central

    Wang, Xiao-Ying; Xu, Yu-Quan; Lin, Shuang-Jun; Liu, Zhen-Zhen; Zhong, Jian-Jiang

    2011-01-01

    Pseudomonas sp. strain SJT25, which strongly antagonizes plant pathogens, was isolated from rice rhizosphere soil by a bioactivity-guided approach. A novel antiphytopathogenic compound was isolated from the fermentation broth of Pseudomonas sp. SJT25 and identified as 2-heptyl-5-hexylfuran-3-carboxylic acid. This compound showed antimicrobial activities both in vitro and in vivo. PMID:21742907

  10. Water-induced coacervation of alkyl carboxylic acid reverse micelles: phenomenon description and potential for the extraction of organic compounds.

    PubMed

    Ruiz, Francisco-Javier; Rubio, Soledad; Pérez-Bendito, Dolores

    2007-10-01

    Coacervates made up of alkanoic (C8-C16) and alkenoic (C18) acid reverse micelles were described for the first time, and their potential for the extraction of organic compounds prior to liquid chromatography was examined. The coacervation process occurred in miscible binary mixtures of water and a variety of protic and aprotic solvents. The phase behavior of alkyl carboxylic acids was found to be a function of both the Hildebrand solubility parameter, delta, and the hydrogen-bonding capability of the solvent. The best solvents for analytical extractions were those featuring the lowest delta values. The phase behavior of alkyl carboxylic acid/water/tetrahydrofuran (THF) ternary systems as a function of component concentration, pH, ionic strength, and temperature was investigated. The efficiency and the time required for phase separation depended on the experimental procedure used (i.e., standing, centrifugation, stirring, and sonication). The formation of alkyl carboxylic acid reverse micelles in THF was proven using both hydrophilic fluorescent probes and scattered light measurements. The structure of the coacervates consisted of spherical droplets dispersed in a continuous phase. Phase volume ratios were a function of both alkyl carboxylic acid and THF concentration. The low volume obtained (e.g., 1.5 microL per mg of decanoic) compared to that obtained by other coacervates (e.g., 5.1 microL per mg of dodecane sulfonic acid and 11.3 microL per mg of Triton X-114) greatly improved the concentration factors reached by coacervation-based extractions. Parameters affecting the extraction efficiency were assessed. Analytes in a wide range of polarity were efficiently extracted on the basis of the hydrophobic (e.g., PAHs) and hydrogen bond (e.g., chlorophenols, bisphenols, pesticides, phthalates, nonionic surfactants, dyes, and photographic developers) interactions that reverse micelles can establish. The coacervates were compatible with the chromatographic determination

  11. IDENTIFICATION AND QUANTIFICATION OF AEROSOL POLAR OXYGENATED COMPOUNDS BEARING CARBOXYLIC OR HYDROXYL GROUPS. 2. ORGANIC TRACER COMPOUNDS FROM MONOTERPENES

    EPA Science Inventory

    A comparison was made of polar organic compounds found in the field with those produced in secondary organic aerosol from laboratory irradiations of natural hydrocarbons and oxides of nitrogen. The field samples comprised atmospheric particulate matter (PM2.5) collect...

  12. Solid compounds of europium and terbium with some aromatic carboxylic acids

    SciTech Connect

    Chupakhina, R.A.; Biryulina, V.N.; Kasimova, L.V.; Balakhonov, V.G.

    1986-10-20

    By the reactions of europium and terbium hydroxides with aqueous solutions of benzoic, salicylic, phthalic, and phthalaldehydic acids, compounds were obtained with the compositions: for phthalic acid M/sub 2/L/sub 3/ x 3H/sub 2/O, and for the other acids ML/sub 3/ x 3H/sub 2/O, in which M = Eu/sup 3 +/, Tb/sup 3 +/; L is the anion of the corresponding acid. The compounds of europium and terbium with phthalaldehydric acid were prepared for the first time.

  13. New approach to immobilization of coal-model compounds on silica using a calcium carboxylate linkage

    SciTech Connect

    Ramakrishnan, S.; Guthrie, R.D.; Britt, P.F.; Buchanan, A.C. III; Davis, B.H.

    1995-12-31

    In an earlier report, we described our efforts to study the hydrothermolysis of surface-immobilized coal model compounds by attaching 1-(4{prime}-hydroxyphenyl)-2-phenylethane to the surface of fumed silica via a Si-OAr linkage using procedures developed by Buchanan, Poutsma and coworkers and heating the resultant material (SiO-DPE) under D{sub 2} pressure. These studies were complicated by the fact that phenolic compounds present in equilibrium with ether-linked materials react with thermolytically-produced radicals to form phenoxyl radicals which then react with D{sub 2} to give DOAr compounds. These provide D for ring-deuteration via a silica-catalyzed process which is restricted to hydroxyl-substituted aromatic rings. It is believed that the free phenol present in SIO-DPE experiments is due to small amounts of water which is known to be generated continually through the formation of siloxane bonds as silica is heated. In simple thermolysis experiments carried out in vacuum any water produced is driven out of the reaction zone. In our experiments, however, the reaction proceeds under D{sub 2} pressure (14 MPa) and reaction products are necessarily available for secondary processes. This report describes the preparation of coal model compounds and the analysis of volatile products from thermolysis.

  14. Pyrolysis of simple coal model compounds containing aromatic carboxylic acids: Does decarboxylation lead to cross-linking?

    SciTech Connect

    Eskay, T.P.; Britt, P.F.; Buchanan, A.C. III

    1996-12-31

    In recent years, it has been proposed that oxygen functional groups, prevalent in low rank coals, are major actors in retrograde reactions which inhibit their efficient thermochemical processing. In the pyrolysis and liquefaction of low-rank coals, low temperature cross-linking reactions have been correlated with the loss of carboxyl groups and the evolution of CO{sub 2} and H{sub 2}O. Pretreatments such as methylation, demineralization, or ion-exchange of the inorganic cations reduce cross-linking and CO{sub 2} evolution in pyrolysis, while the exchange of Na{sup +}, K{sup +}, Ca{sup ++}, and Ba{sup ++} into demineralized coal increases cross-linking and CO{sub 2} evolution in pyrolysis and liquefaction. These results suggest, in part, that decarboxylation pathways in coal may play an important role in the cross-linking of the coal polymer. However, the reaction pathways associated with the decarboxylation and cross-linking events in low rank coal are currently unknown. Furthermore, it is not known whether the reaction pathway that leads to decarboxylation also leads to cross-linking. Radical recombination or addition reactions have been suggested as being involved in retrograde reactions. However, the involvement of radical pathways in thermal decarboxylation reactions has recently been brought into question by the observation that decarboxylation of benzoic acid derivatives under coal liquefaction conditions yielded only small amounts of aryl-aryl coupling products. Therefore, to gain a better understanding of the role decarboxylation plays in cross-linking reactions in low rank coals, we have studied the pyrolysis of several bibenzyls containing aromatic carboxylic acids. The structures currently under investigation are 1,2-(3,3`-dicarboxyphenyl)ethane (1) and 1,2-(4,4`-dicarboxyphenyl)ethane(2). These compounds are capable of forming reactive free-radical intermediates at ca. 400{degrees}C through homolysis of the weak bibenzylic bonds.

  15. Transesterification of PHA to Oligomers Covalently Bonded with (Bio)Active Compounds Containing Either Carboxyl or Hydroxyl Functionalities

    PubMed Central

    Kwiecień, Iwona; Radecka, Iza; Kowalczuk, Marek; Adamus, Grażyna

    2015-01-01

    This manuscript presents the synthesis and structural characterisation of novel biodegradable polymeric controlled-release systems of pesticides with potentially higher resistance to weather conditions in comparison to conventional forms of pesticides. Two methods for the preparation of pesticide-oligomer conjugates using the transesterification reaction were developed. The first method of obtaining conjugates, which consist of bioactive compounds with the carboxyl group and polyhydroxyalkanoates (PHAs) oligomers, is "one-pot" transesterification. In the second method, conjugates of bioactive compounds with hydroxyl group and polyhydroxyalkanoates oligomers were obtained in two-step method, through cyclic poly(3-hydroxybutyrate) oligomers. The obtained pesticide-PHA conjugates were comprehensively characterised using GPC, 1H NMR and mass spectrometry techniques. The structural characterisation of the obtained products at the molecular level with the aid of mass spectrometry confirmed that both of the synthetic strategies employed led to the formation of conjugates in which selected pesticides were covalently bonded to PHA oligomers via a hydrolysable ester bond. PMID:25781908

  16. A magnesium-carboxylate framework showing luminescent sensing for CS{sub 2} and nitroaromatic compounds

    SciTech Connect

    Wu, Zhao-Feng; Tan, Bin; Feng, Mei-Ling; Du, Cheng-Feng; Huang, Xiao-Ying

    2015-03-15

    A magnesium metal-organic framework compound, namely [NH{sub 2}(CH{sub 3}){sub 2}][Mg{sub 3}(NDC){sub 2.5}(HCO{sub 2}){sub 2}(DMF){sub 0.75}(H{sub 2}O){sub 0.25}]·1.25DMF·0.75H{sub 2}O (1) (H{sub 2}NDC=1,4-naphthalene dicarboxylic acid, DMF=N,N′-dimethylformamide), has been synthesized in solvothermal conditions and structurally characterized. It features a three-dimensionally anionic framework with aligned channels parallel to the b-axis. Luminescent studies indicated that it showed significant luminescence quenching for carbon disulfide (CS{sub 2}) and nitrobenzene after being activated, at a content of only 3.0 and 0.1 vol% in DMF, respectively. In addition, the activated sample showed sensitive luminescence quenching for 1,3,5-trinitrophenol with a low concentration of 5×10{sup −5} mol/L. - Graphical abstract: Presented is a microporous 3D Mg-MOF, namely, [NH{sub 2}(CH{sub 3}){sub 2}][Mg{sub 3}(NDC){sub 2.5}(HCO{sub 2}){sub 2}(DMF){sub 0.75}(H{sub 2}O){sub 0.25}]·1.25DMF·0.75H{sub 2}O (1) (H{sub 2}NDC=1,4-naphthalene dicarboxylic acid) showing significant luminescence quenching for carbon disulfide and nitrobenzene. - Highlights: • A microporous 3D metal-organic framework based on Mg. • The compound shows significant luminescence quenching for CS{sub 2} and nitrobenzene after activated. • The compound shows sensitive luminescence quenching for 1,3,5-trinitrophenol with a low concentration of 5×10{sup −5} mol/L.

  17. Electrodepositing behaviors and properties of nano Fe-Ni-Cr/SiC composite coatings from trivalent chromium baths containing compound carboxylate-urea system.

    PubMed

    He, Xinkuai; Hou, Bailong; Cai, Youxing; Li, Chen; Jiang, Yumei; Wu, Luye

    2013-06-01

    The nano Fe-Ni-Cr/SiC composite coatings were prepared using pulse electrodeposition method from trivalent chromium baths containing compound carboxylate-urea system and nano SiC in ultrasonic field. The effects of the carboxylate-urea system on the nano Fe-Ni-Cr/SiC composite coatings have been investigated. These results indicated that the SiC and Cr contents and the thickness of the Fe-Ni-Cr/SiC composite coatings could be obviously improved by the compound carboxylate-urea system. The steady-state polarization curves showed that the hydrogen evolution reaction (HER) could be significantly inhibited by the compound carboxylate-urea system, which was benefit to increase the SiC and Cr contents and the thickness of the composite coatings. The cyclic voltammetry (CV) curves showed that the cathodic polarization of the matrix metal ions could be increased in the bath containing the compound carboxylate-urea system. Thus, a compact Fe-Ni-Cr/SiC composite coating could be obtained using this technique. The surface morphology of the Fe-Ni-Cr/SiC composite coatings checked with the scanning electron micrographs (SEM) showed that the surface smoothness could be also improved and the microcracks and pinholes could be decreased due to the presence of the compound carboxylate-urea system. The phase composition of the as-posited coating was measured by the X-ray diffraction (XRD). XRD data showed that the as-posited coating was Fe-Ni-Cr/SiC composite coating. The chemical composition of the coating was investigated by energy dispersive spectrum (EDS) analysis. The result showed the functional Fe-Ni-Cr/SiC composite coatings with 4.1 wt.% SiC and 25.1 wt.% Cr, and 23.9 microm thickness were obtained in this study, which had best corrosion resistance according to the results of the typical potentiodynamic polarization curves of the Fe-Ni-Cr/SiC composite coatings. PMID:23862444

  18. Pyrolysis of simple coal model compounds containing aromatic carboxylic acids: Does decarboxylation lead to cross-linking?

    SciTech Connect

    Eskay, T.P.; Britt, P.F.; Buchanan, A.C.

    1996-10-01

    Recently, a number of studies have shown that the evolution of CO{sub 2} from carboxylate groups is a key indicator of cross-linking reactions in pyrolysis and liquefaction of low rank coals. This result suggests that the thermal decarboxylation may occur by a pathway which initiates retrogressive reactions in the coal polymer. However, the chemistry of the thermal decomposition of aromatic carboxylic acids is not thoroughly understood. To provide insight into the thermal decarboxylation of aromatic carboxylic acids, and the role decarboxylation may play in coal pyrolysis, we have conducted a study of the pyrolysis of several bibenzyls containing aromatic carboxylic acids. The results of our pyrolysis study and the relevance of thermal decarboxylation on coal cross-linking reactions will be discussed.

  19. Effects of the density of carboxyl groups in organic compounds on the photocatalytic reduction of Cr(VI) in a TiO2 suspension.

    PubMed

    Lee, Seung-Mok; Cho, Il-Hyoung; Chang, Yoon-Young; Yang, Jae-Kyu

    2007-03-01

    Photocatalytic reduction (PCR) of Cr(VI) in a TiO2 suspension was studied at pH 4 in the presence of organic compounds containing different numbers of carboxyl groups. The compounds studied were glycine (Gly), iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA). In all the cases, near complete Cr(VI) removal was observed after 60 minutes. During PCR process, the aqueous Cr(VI) concentration measured with both Ion Chromatography and Atomic Absorption Spectrophotometery was different in the presence of IDA and EDTA as reaction proceeded while little difference was observed in a control test. This result suggests that a greater portion of reduced Cr(III) species was possibly dissolved through complex formation with IDA (Cr(III)-IDA) and EDTA (Cr(III)-EDTA) or with reaction intermediates (Cr(III)-organic complexes) during PCR compared to the control test. As the number of carboxyl group increased Cr(VI) reduction increased and showed a good linear relationship between initial rates of Cr(VI) reduction and adsorption density of carboxyl group of the surface of TiO2. The initial rate of Cr(VI) reduction in the presence of EDTA was 5 times greater than that in control. When the PCR process was applied in the treatment of real wastewater, an effective Cr(VI) reduction was observed with addition of EDTA. PMID:17365325

  20. Pyrolysis of simple coal model compounds containing aromatic carboxylic acids: Does decarboxylation lead to cross-linking?

    SciTech Connect

    Eskay, T.P.; Britt, P.F.; Buchanan, A.C. III

    1996-02-01

    The thermolysis of two aromatic carboxylic acids 1,2-(3,3`-dicarboxyphenyl)ethane (2) have been investigated at 400{degree} C as models of carboxylic acids in low rank coals. The major decomposition pathway observed is decarboxylation, which mainly occurs by an ionic pathway. This decarboxylation route does not lead to any significant amount of coupling or high molecular weight products that would be indicative of cross-linking products in coal. The pyrolysis of 1 and 2 will be investigated under a variety of conditions that better mimic the enviromment found in coal to further delineate the role that decarboxylation plays in coal cross-linking chemistry.

  1. Simultaneous determination of phenolic compounds in sesame oil using LC-MS/MS combined with magnetic carboxylated multi-walled carbon nanotubes.

    PubMed

    Wu, Rao; Ma, Fei; Zhang, Liangxiao; Li, Peiwu; Li, Guangming; Zhang, Qi; Zhang, Wen; Wang, Xiuping

    2016-08-01

    A novel magnetic carboxylated multi-walled carbon nanotubes (c-MWCNT-MNPs) was proposed for magnetic solid-phase extraction coupled with liquid chromatography-tandem mass spectrometry to determine phenolic compounds in sesame oil. In this study, c-MWCNT-MNPs were acquired by simply dispersing Fe3O4 magnetic nanoparticles into carboxylated multi-walled carbon nanotubes. The major parameters affecting extraction efficiency were optimized, including the type and volume of desorption solvents, extraction and desorption time, washing solution, and sorbent amount. The limit of quantifications and limit of detections were from 0.03μg/kg to 43.00μg/kg and from 0.01μg/kg to 13.60μg/kg, respectively. The recoveries of phenolic compounds in vegetable oils were in the range of 83.8-125.9% with inter-day and intra-day precisions of less than 13.2%. It was confirmed that this method was simple, rapid and reliable with an excellent potential for routine analysis of phenolic compounds in oil samples. PMID:26988510

  2. A new approach to immobilization of coal-model compounds on silica using a calcium carboxylate linkage

    SciTech Connect

    Ramakrishnan, S.; Guthrie, R.D.; Davis, B.H.

    1995-12-31

    Fumed silica treated with aqueous Ca(OH){sub 2} and dried, removes aromatic carboxylic acids from organic solvents. The resultant materials prepared with benzoic and toluic acids are stable at 400{degrees}C. A sample of 4-(2`-phenylethyl)benzoic acid immobilized in this way undergoes vacuum thermolysis to give volatile products typical of substituted diphenylethane thermolysis: benzene, toluene, ethylbenzene, diphenylethane and stilbene leaving the corresponding acids (benzoic, toluic, etc.) attached to the surface. As in previous experiments with surface-attached diphenylethane, rearrangement to 4-(1`-phenylethyl)benzoic acid is a major process. On heating under D{sub 2} pressure at 400{degrees}C, H-D exchange occurs at all aromatic and aliphatic positions in a manner similar to that of Si-O-Ar linked materials. Deuterium incorporation in carboxylate-substituted rings is much greater than in unsubstituted rings. The mechanism is under study.

  3. Polar organic marker compounds in atmospheric aerosol in the Po Valley during the Supersito campaigns - Part 1: Low molecular weight carboxylic acids in cold seasons

    NASA Astrophysics Data System (ADS)

    Pietrogrande, Maria Chiara; Bacco, Dimitri; Visentin, Marco; Ferrari, Silvia; Poluzzi, Vanes

    2014-04-01

    In the framework of the “Supersito” project, three intensive experimental campaigns were conducted in the Po Valley (Northern Italy) in cold seasons, such as late autumn, pre-winter and deep-winter, over three years from 2011 to 2013. As a part of a study on polar marker compounds, including carboxylic acids, sugar derivatives and lignin phenols, the present study reports a detailed discussion on the atmospheric concentrations of 14 low molecular weight carboxylic acids, mainly dicarboxylic and oxo-hydroxy carboxylic acids, as relevant markers of primary and secondary organic aerosols. PM2.5 samples were collected in two monitoring sites, representing urban and rural background stations. The total quantities of carboxylic acids were 262, 167 and 249 ng m-3 at the urban site and 308, 115, 248 ng m-3 at the rural site in pre-winter, fall and deep-winter, respectively. These high concentrations can be explained by the large human emission sources in the urbanized region, combined with the stagnant atmospheric conditions during the cold seasons that accumulate the organic precursors and accelerate the secondary atmospheric reactions. The distribution profiles of the investigated markers suggest the dominant contributions of primary anthropogenic sources, such as traffic, domestic heating and biomass burning. These results are confirmed by comparison with additional emission tracers, such as anhydro-saccharides for biomass burning and fatty acids originated from different anthropogenic sources. In addition, some secondary constituents were detected in both sites, as produced by in situ photo-chemical reactions from both biogenic (e.g. pinonic acid) and anthropogenic precursors (e.g. phthalic and adipic acids). The impact of different sources from human activities was elucidated by investigating the week pattern of carboxylic and fatty acid concentrations. The weekly trends of analytes during the warmer campaign (fall 2012; mean temperature: 12 °C) may be related to

  4. Carboxylate-modulated two novel Ag(I) coordination compounds with benzoguanamine ligand: Syntheses, structures, thermal stability and photoluminescent properties

    NASA Astrophysics Data System (ADS)

    Hao, Hong-Jun; Sun, Di; Liu, Fu-Jing; Huang, Rong-Bin; Zheng, Lan-Sun

    2012-03-01

    Two mixed-ligand coordination complexes (CCs) of the formula [Ag2(bga)2(pnba)2(H2O)]·(bga)2 (1) and {[Ag3(bga)3(dnb)3(H2O)]·(CH3OH)·(C2H5OH)}n (2) (bga = benzoguanamine, Hpnba = 4-nitrobenzoic acid, Hdnb = 3,5-dinitrobenzoic acid) were synthesized by reactions of AgNO3 and bga in the presence of different carboxylates under the ammoniacal condition. Both CCs have been characterized by element analysis, powder X-ray diffraction (PXRD), IR and X-ray single-crystal diffraction. Complex 1 is 0D discrete molecule which is extended to 1D supramolecular chains through intermolecular N-H···N complementary hydrogen bonds. Complex 2 is a 1D infinite chain containing monodentate and bidentate bga ligands. Analogously, the presence of complementary N-H···N hydrogen bonds drives the 1D chains to form 2D supramolecular sheet. In addition, the thermal stabilities and the photoluminescence properties of them were also investigated.

  5. Perfluorinated carboxylates and sulfonates and precursor compounds in herring gull eggs from colonies spanning the Laurentian Great Lakes of North America.

    PubMed

    Gebbink, Wouter A; Hebert, Craig E; Letcher, Robert J

    2009-10-01

    Environmentally important perfluorinated carboxylates and sulfonates, as well as per- and polyfluorinated precursor compounds including several sulfonamides, telomer acids, and alcohols were determined in individual herring gull (Larus argentatus) eggs collected (in 2007) from 15 colonies located at Canadian and some American sites across the Laurentian Great Lakes of North America. The pattern of perfluorosulfonates (PFSAs; C6, C8, C10 chain lengths) was dominated by PFOS (> 90% of sigmaPFSA concentration) regardless of collection location. Concentrations of sigmaPFSA were significantly (p < 0.03) higher in eggs from Middle Island (western Lake Erie; 507 +/- 47 ng/g ww), Toronto Harbour (484 +/- 49 ng/g ww), and Strachan Island (486 +/- 59 ng/g ww) (Lake Ontario) compared to eggs from colonies on Lakes Superior, Michigan, and Huron. Perfluorocarboxylic acids (PFCAs) ranging in chain length from C8 to C15 were detected in the eggs, with PFUnA and PFTrA being the dominant compounds. PFOA and PFNA were more abundant in the sigmaPFCA in eggs from Lake Superior and Michigan colonies, and PFUnA and longer chain PFCAs were more abundant in the sigmaPFCA in eggs from Lake Erie and Ontario colonies. In contrast to sigmaPFSA, the highest concentrations of sigmaPFCA were found in eggs from Double Island, Lake Huron (113 +/- 12 ng/g ww) followed by eggs from colonies on Lakes Erie and Ontario. Among the PFOS or PFCA precursor compounds assessed (6:2, 8:2, and 10:2 fluorotelomer alcohols and acids and PFOSA), none were detectable in eggs from any sampling location. The exception was PFOSA (average concentration < 1 ng/g ww), which suggests that PFOS in the gulls and subsequently in their eggs may be due, in part, to biotransformation of PFOSA to PFOS in the gull and/or in their diet and food web. The accumulation of PFSA and PFCA from mainly aquatic dietary sources was suggested, and were highly lake- and/ or colony-dependent especially showing a northwest and southeast

  6. Identification of 1-({[1-(4-Fluorophenyl)-5-(2-methoxyphenyl)-1H-pyrazol-3-yl]carbonyl}amino)cyclohexane Carboxylic Acid as a Selective Nonpeptide Neurotensin Receptor Type 2 Compound

    PubMed Central

    2015-01-01

    Compounds active at neurotensin receptors (NTS1 and NTS2) exert analgesic effects on different types of nociceptive modalities, including thermal, mechanical, and chemical stimuli. The NTS2 preferring peptide JMV-431 (2) and the NTS2 selective nonpeptide compound levocabastine (6) have been shown to be effective in relieving the pain associated with peripheral neuropathies. With the aim of identifying novel nonpeptide compounds selective for NTS2, we examined analogues of SR48692 (5a) using a FLIPR calcium assay in CHO cells stably expressing rat NTS2. This led to the discovery of the NTS2 selective nonpeptide compound 1-({[1-(4-fluorophenyl)-5-(2-methoxyphenyl)-1H-pyrazol-3-yl]carbonyl}amino)cyclohexane carboxylic acid (NTRC-739, 7b) starting from the nonselective compound 5a. PMID:24856674

  7. 1-Azaniumylcyclobutane-1-carboxylate monohydrate

    NASA Technical Reports Server (NTRS)

    Butcher, Ray J.; Brewer, Greg; Burton, Aaron S.; Dworkin, Jason

    2014-01-01

    In the title compound, C5H9NO2H2O, the amino acid is in the usual zwitterionic form involving the carboxylate group. The cyclobutane backbone of the amino acid is disordered over two conformations, with occupancies of 0.882 (7) and0.118 (7). In the crystal, NH O and OH O hydrogen bonds link the zwitterions [with the water molecule involved as both acceptor (with the NH3+) and donor (through a single carboxylate O from two different aminocyclobutane carboxylatemoities)], resulting in a two-dimensional layered structure lying parallel to (100).

  8. A bis(amine-carboxylate) copper(II) coordination compound forms a two-dimensional metal-organic framework when crystallized from water and methanol.

    PubMed

    Munro, Orde Q; Akerman, Matthew P; Gillham, Kate

    2009-09-01

    When {2,2'-[(2-methyl-2-nitropropane-1,3-diyl)diimino]diacetato}copper(II), [Cu(C(8)H(13)N(3)O(6))], (I), was crystallized from a binary mixture of methanol and water, a monoclinic two-dimensional water- and methanol-solvated metal-organic framework (MOF) structure, distinctly different from the known orthorhombic one-dimensional coordination polymer of (I), was isolated, namely catena-poly[[copper(II)-mu(3)-2,2'-[(2-methyl-2-nitropropane-1,3-diyl)diimino]diacetato] methanol 0.45-solvate 0.55-hydrate], {[Cu(C(8)H(13)N(3)O(6))].0.45CH(3)OH.0.55H(2)O}(n), (II). The monoclinic structure of (II) comprises centrosymmetric dimers stabilized by a dative covalent Cu(2)O(2) core and intramolecular N-H...O hydrogen bonds. Each dimer is linked to four neighbouring dimers via symmetry-related (opposing) pairs of bridging carboxylate O atoms to generate a ;diamondoid' net or two-dimensional coordination network. Tight voids of 166 A(3) are located between these two-dimensional MOF sheets and contain a mixture of water and methanol with fractional occupancies of 0.55 and 0.45, respectively. The two-dimensional MOF sheets have nanometre-scale spacings (11.2 A) in the crystal structure. Hydrogen-bonding between the methanol/water hydroxy groups and a Cu-bound bridging carboxylate O atom apparently negates thermal desolvation of the structure below 358 K in an uncrushed crystal of (II). PMID:19726848

  9. Simultaneous determination of endocrine disrupting compounds bisphenol F and bisphenol AF using carboxyl functionalized multi-walled carbon nanotubes modified electrode.

    PubMed

    Yang, Jichun; Wang, Xin; Zhang, Danfeng; Wang, Lingling; Li, Qi; Zhang, Lei

    2014-12-01

    A novel, simple and selective electrochemical method was developed for simultaneous determination of bisphenol F (BPF) and bisphenol AF (BPAF) in aqueous media (phosphate buffer solution, pH 6.0) on carboxyl functionalized multi-walled carbon nanotubes modified glassy carbon electrode (MWCNT-COOH/GCE) using differential pulse voltammetry (DPV). In DPV, MWCNT-COOH/GCE could separate the oxidation peak potentials of BPF and BPAF present in the same solution though, at the bare GCE, the peak potentials were indistinguishable. The results showed that the electrochemical sensor exhibited excellent electrocatalytic activity towards the oxidation of the two analytes. The peak current in DPV of BPF and BPAF increased linearly with their concentration in the ranges of 0.6-1.6 mmol/L BPF and 0.6-1.6 mmol/L BPAF. The detection limits were 0.1243 mmol/L and 0.1742 mmol/L (S/N=3) correspondingly. The modified electrode was successfully used to simultaneously determine BPF and BPAF in real samples. PMID:25159400

  10. Perfluorinated sulfonate and carboxylate compounds and precursors in herring gull eggs from across the Laurentian Great Lakes of North America: Temporal and recent spatial comparisons and exposure implications.

    PubMed

    Letcher, Robert J; Su, Guanyong; Moore, Jeremy N; Williams, Lisa L; Martin, Pamela A; de Solla, Shane R; Bowerman, William W

    2015-12-15

    Chemicals of emerging concern (CECs) in the basin of the Laurentian Great Lakes of North America include per- and poly-fluoroalkyl substances (PFASs) classified as perfluoroalkyl acids. We investigated several PFASs, and specifically 13 C4-C16 perfluorinated carboxylic acids (PFCAs), 4 (C4, C6, C8 and C10) perfluorinated sulfonates (PFSAs), perfluoro-4-ethylcyclohexane sulfonate (PFEtCHxS) and selected precursors (e.g. perfluorobutane sulfonamide and perfluorooctane sulfonamide) in herring gull (Larus argentatus) eggs collected in 2012-2013 from 19 Canadian and U.S. colony sites across the Great Lakes. C6, C8 and C10 PFSAs, PFEtCHxS, and C7-14 and C16 PFCAs were quantifiable at >97% of the 114 egg samples. PFEtCHxS concentrations ranged from n.d. to 3.1ng/g ww (highest in Lake Michigan eggs). Mean Σ4PFSA (92 to 97% perfluorooctane sulfonate (PFOS)) and Σ9PFCA concentration ranges were 44 to 740 and 4.8 to 118ng/g ww, respectively. Σ4PFSA showed a clear increasing concentration trend from the northwest to the southeast colonies. Also, Σ4PFCA to Σ9PFSA concentration ratios in gull eggs were greater in eggs from Lake Superior relative to colonies in the other lakes. PFOS concentrations in some egg samples were greater than some of the known lowest observed effect concentrations (LOECs) measured and reported in captive bird model studies. This study showed the increasing complexity of PFAS-CECs, and emphasized the importance of continuing monitoring of bioaccumulative PFAS in Great Lakes herring gulls. PMID:26318684

  11. Replacement of the carboxylic acid group of prostaglandin F2α with a hydroxyl or methoxy substituent provides biologically unique compounds

    PubMed Central

    Woodward, D F; Krauss, A H-P; Chen, J; Gil, D W; Kedzie, K M; Protzman, C E; Shi, L; Chen, R; Krauss, H A; Bogardus, A; Dinh, H T T; Wheeler, L A; Andrews, S W; Burk, R M; Gac, T; Roof, M B; Garst, M E; Kaplan, L J; Sachs, G; Pierce, K L; Regan, J W; Ross, R A; Chan, M F

    2000-01-01

    Replacement of the carboxylic acid group of PGF2α with the non-acidic substituents hydroxyl (-OH) or methoxy (-OCH3) resulted in an unexpected activity profile.Although PGF2α 1-OH and PGF2α 1-OCH3 exhibited potent contractile effects similar to 17-phenyl PGF2α in the cat lung parenchymal preparation, they were approximately 1000 times less potent than 17-phenyl PGF2α in stimulating recombinant feline and human FP receptors.In human dermal fibroblasts and Swiss 3T3 cells PGF2α 1-OH and PGF2α 1-OCH3 produced no Ca2+ signal until a 1 μM concentration was exceeded. Pretreatment of Swiss 3T3 cells with either 1 μM PGF2α 1-OH or PGF2α 1-OCH3 did not attenuate Ca2+ signal responses produced by PGF2α or fluprostenol. In the rat uterus, PGF2α 1-OH was about two orders of magnitude less potent than 17-phenyl PGF2α whereas PGF2α 1-OCH3 produced only a minimal effect.Radioligand binding studies on cat lung parenchymal plasma membrane preparations suggested that the cat lung parenchyma does not contain a homogeneous population of receptors that equally respond to PGF2α1-OH, PGF2α1-OCH3, and classical FP receptor agonists.Studies on smooth muscle preparations and cells containing DP, EP1, EP2, EP3, EP4, IP, and TP receptors indicated that the activity of PGF2α 1-OH and PGF2α 1-OCH3 could not be ascribed to interaction with these receptors.The potent effects of PGF2α 1-OH and PGF2α 1-OCH3 on the cat lung parenchyma are difficult to describe in terms of interaction with the FP or any other known prostanoid receptor. PMID:10952685

  12. Multiresidue analysis of endocrine-disrupting compounds and perfluorinated sulfates and carboxylic acids in sediments by ultra-high-performance liquid chromatography-tandem mass spectrometry.

    PubMed

    Cavaliere, Chiara; Capriotti, Anna Laura; Ferraris, Francesca; Foglia, Patrizia; Samperi, Roberto; Ventura, Salvatore; Laganà, Aldo

    2016-03-18

    A multiresidue analytical method for the determination of 11 perfluorinated compounds and 22 endocrine-disrupting compounds (ECDs) including 13 natural and synthetic estrogens (free and conjugated forms), 2 alkylphenols, 1 plasticiser, 2 UV-filters, 1 antimicrobial, and 2 organophosphorus compounds in sediments has been developed. Ultrasound-assisted extraction followed by solid phase extraction (SPE) with graphitized carbon black (GCB) cartridge as clean-up step were used. The extraction process yield was optimized in terms of solvent composition. Then, a 3(2) experimental design was used to optimize solvent volume and sonication time by response surface methodology, which simplifies the optimization procedure. The final extract was analyzed by ultra-high performance liquid chromatography coupled with tandem mass spectrometry. The optimized sample preparation method is simple and robust, and allows recovery of ECDs belonging to different classes in a complex matrix such as sediment. The use of GCB for SPE allowed to obtain with a single clean-up procedure excellent recoveries ranging between 75 and 110% (relative standard deviation <16%). The developed methodology has been successfully applied to the analysis of ECDs in sediments from different rivers and lakes of the Lazio Region (Italy). These analyses have shown the ubiquitous presence of chloro-substituted organophosphorus flame retardants and bisphenol A, while other analyzed compounds were occasionally found at concentration between the limit of detection and quantification. PMID:26884138

  13. Copper(II)-Catalyzed Silylation of Activated Alkynes in Water: Diastereodivergent Access to (E)- or (Z)-β-Silyl-α,β-Unsaturated Carbonyl and Carboxyl Compounds**

    PubMed Central

    Calderone, Joseph A.; Santos, Webster L.

    2014-01-01

    Copper(II)-catalyzed silylation of substituted alkynylcarbonyl compounds was investigated. Via activation of Me2PhSiBpin in water at room temperature and open atmosphere, vinylsilanes conjugated to carbonyl groups are synthesized in high yield. A surprising diastereodivergent access to olefin geometry was discovered using a silyl conjugate addition strategy: aldehydes and ketones were Z selective while esters and amides were exclusively transformed to E products. PMID:24532188

  14. MICROBIAL TRANSFORMATION OF ESTERS OF CHLORINATED CARBOXYLIC ACIDS

    EPA Science Inventory

    Two groups of compounds were selected for microbial transformation studies. In the first group were carboxylic acid esters having a fixed aromatic moiety and an increasing length of the alkyl component. Ethyl esters of chlorine-substituted carboxylic acids were in the second grou...

  15. Production of mono- and di-carboxylated polyethylene glycols as a factor obstacle to the successful ozonation-assisted biodegradation of ethoxylated compounds.

    PubMed

    Nakai, Satoshi; Okuda, Tetsuji; Nishijima, Wataru; Okada, Mitsumasa

    2015-10-01

    Ozonation is believed to improve the biodegradability of organic compounds. In the present study, degradation of nonylphenol ethoxylates (NPEOs) was monitored in hybrid treatment systems consisting of ozonation and microbial degradation processes. We found that ozonation of NPEOs decreased, rather than increased, the biodegradability under certain conditions. The timing of ozonation was a definitive factor in determining whether ozonation increased or decreased the biodegradation rates of NPEOs. Initial ozonation of NPEOs prior to biodegradation reduced the rate of dissolved organic carbon (DOC) removal during the subsequent 14 d of biodegradation, whereas intermediate ozonation at the 9th day of biodegradation improved subsequent DOC removal during 14 d of NPEO biodegradation. Furthermore, reduction of DOC removal was also observed, when initial ozonation prior to biodegradation was subjected to cetyl alcohol ethoxylates. The production of less biodegradable intermediates, such as mono- and dicarboxylated polyethylene glycols (MCPEGs and DCPEGs), was responsible for the negative effect of ozonation on biodegradability of NPEOs. DCPEGs and MCPEGs were produced by biodegradation of polyethylene glycols (PEGs) that were ozonolysis products of the NPEOs, and the biodegradability of DCPEGs and MCPEGs was less than that of the precursor PEGs. The results indicate that, if the target chemicals contain ethoxy chains, production of PEGs may be one of the important factors when ozonation is considered. PMID:25985303

  16. Pyrrolidinium-2-carboxyl-ate-4-nitro-phenol (1/2).

    PubMed

    Sowmya, Narayanan Swarna; Vidyalakshmi, Yechuri; Sampathkrishnan, Sadasivam; Srinivasan, Thothadri; Velmurugan, Devadasan

    2013-10-31

    In the title compound, C5H9NO2·2C6H5NO3, the pyrrolidine ring of the pyrrolidinium-2-carboxyl-ate zwitterion adopts a twisted conformation on the -CH2-CH2- bond adjacent to the N atom. The mean plane of this pyrrolidine ring forms dihedral angles of 25.3 (3) and 32.1 (3)° with the two nitro-phenol rings. An intra-molecular N-H⋯O hydrogen bond occurs in the pyrrolidinium-2-carboxyl-ate mol-ecule. In the crystal, mol-ecules are linked via O-H⋯O and N-H⋯O hydrogen bonds, enclosing R (3) 2(8) ring motifs, forming chains running parallel to the a axis. These chains are further cross-linked by O-H⋯O and C-H⋯O hydrogen bonds, forming undulating two-dimensional networks lying parallel to (001). PMID:24454145

  17. Boron Carboxylate Catalysis of Homoallylboration

    PubMed Central

    2015-01-01

    Boron tris(trifluoroacetate) is identified as the first effective catalyst for the homoallyl- and homocrotylboration of aldehydes by cyclopropylcarbinylboronates. NMR spectroscopic studies and theoretical calculations of key intermediates and transition states both suggest that a ligand-exchange mechanism, akin to our previously reported PhBCl2-promoted homoallylations, is operative. Our experimental and theoretical results also suggest that the catalytic activity of boron tris(trifluoroacetate) might originate from more facile catalytic turnover of the trifluoroacetate ligands (in agreement with DFT calculations) or from a lower propensity for formation of off-pathway reservoir intermediates (as observed by 1H NMR). This work shows that carboxylates are viable catalytic ligands for homoallyl- and homocrotylations of carbonyl compounds and opens the door to the development of catalytic asymmetric versions of this transformation. PMID:24754566

  18. Effect of choline carboxylate ionic liquids on biological membranes

    PubMed Central

    Rengstl, Doris; Kraus, Birgit; Van Vorst, Matthew; Elliott, Gloria D.; Kunz, Werner

    2015-01-01

    Choline carboxylates, ChCm, with m = 2–10 and choline oleate are known as biocompatible substances, yet their influence on biological membranes is not well-known, and the effect on human skin has not previously been investigated. The short chain choline carboxylates ChCm with m = 2, 4, 6 act as hydrotropes, solubilizing hydrophobic compounds in aqueous solution, while the longer chain choline carboxylates ChCm with m = 8,10 and oleate are able to form micelles. In the present study, the cytotoxicity of choline carboxylates was tested using HeLa and SK-MEL-28 cells. The influence of these substances on liposomes prepared from dipalmitoylphosphatidylcholine (DPPC) was also evaluated to provide insights on membrane interactions. It was observed that the choline carboxylates with a chain length of m > 8 distinctly influence the bilayer, while the shorter ones had minimal interaction with the liposomes. PMID:25444662

  19. Carboxylic acid sorption regeneration process

    DOEpatents

    King, C. Judson; Poole, Loree J.

    1995-01-01

    Carboxylic acids are sorbed from aqueous feedstocks into an organic liquid phase or onto a solid adsorbent. The acids are freed from the sorbent phase by treating it with aqueous alkylamine thus forming an alkylammonium carboxylate which is dewatered and decomposed to the desired carboxylic acid and the alkylamine.

  20. Carboxylic acid sorption regeneration process

    DOEpatents

    King, C.J.; Poole, L.J.

    1995-05-02

    Carboxylic acids are sorbed from aqueous feedstocks into an organic liquid phase or onto a solid adsorbent. The acids are freed from the sorbent phase by treating it with aqueous alkylamine thus forming an alkylammonium carboxylate which is dewatered and decomposed to the desired carboxylic acid and the alkylamine. 10 figs.

  1. High Lipophilicty of Perfluoroalkyl Carboxylate and Sulfonate

    PubMed Central

    Jing, Ping; Rodgers, Patrick J.; Amemiya, Shigeru

    2009-01-01

    Here we report on remarkably high lipophilicity of perfluoroalkyl carboxylate and sulfonate. A lipophilic nature of this emerging class of organic pollutants has been hypothesized as an origin of their bioaccumulation and toxicity. Both carboxylate and sulfonate, however, are considered hydrophilic while perfluroalkyl groups are not only hydrophobic but also oleophobic. Partition coefficients of homologous series of perfluoroalkyl and alkyl carboxylates between water and n-octanol were determined as a measure of their lipophilicity by ion-transfer cyclic voltammetry. Very similar lipophilicity of perfluoroalkyl and alkyl chains with the same length is demonstrated experimentally for the first time by fragment analysis of the partition coefficients. This finding is important for pharmaceutical and biomedical applications of perfluoroalkyl compounds. Interestingly, ∼2 orders of magnitude higher lipophilicity of a perfluoroalkyl carboxylate or sulfonate in comparison to its alkyl counterpart is ascribed nearly exclusively to their oxoanion groups. The higher lipophilicity originates from a strong electron-withdrawing effect of the perfluoroalkyl group on the adjacent oxoanion group, which is weakly hydrated to decrease its hydrophilicity. In fact, the inductive effect is dramatically reduced for a fluorotelomer with an ethylene spacer between perfluorohexyl and carboxylate groups, which is only as lipophilic as its alkyl counterpart, nonanoate, and is 400 times less lipophilic than perfluorononanoate. The high lipophilicity of perfluoroalkyl carboxylate and sulfonate implies that their permeation across such a thin lipophilic membrane as a bilayer lipid membrane is limited by their transfer at a membrane/water interface. The limiting permeability is lower and less dependent on their lipophilicity than the permeability controlled by their diffusion in the membrane interior as assumed in the classical solubility-diffusion model. PMID:19170492

  2. Crystal structure of ethyl 2,4-di-chloro-quinoline-3-carboxyl-ate.

    PubMed

    Cabrera, Alberto; Miranda, Luis D; Reyes, Héctor; Aguirre, Gerardo; Chávez, Daniel

    2015-12-01

    In the crystal structure of the title compound, C12H9Cl2NO2, the mean planes through the quinoline and carboxyl-ate groups have r.m.s. deviations of 0.006 and 0.021 Å, respectively, and form a dihedral angle of 87.06 (19)°. In the crystal, mol-ecules are linked via very weak C-H⋯O hydrogen bonds, forming chains, which propagate along the c-axis direction. PMID:26870538

  3. Investigations on the synthesis and properties of new derivatives of ethyl 3H-2-imino-7-methyl-4-oxopyrido [3,2-e]-1,3-thiazine-6-carboxylate and isomeric compounds.

    PubMed

    Sladowska, H; Zawisza, T

    1982-04-01

    Condensation of diethyl 2-chloro-6-methylpyridine-3,5-dicarboxylate (IV) with thiourea and alkyl or alkenyl N-mono- and N,N'-disubstituted thioureas gives mainly the corresponding derivatives of ethyl 3H-2-imino-7-methyl-4-oxopyrido [3,2-e]-1,3-thiazine-6-carboxylate (VI-XII). As by-products isomeric derivatives of ethyl 7-methyl-4-oxo-2-thioxo-1,2,3,4-tetrahydropyrido [2,3-d) pyrimidine-6-carboxylate (XIII-XVIII) are formed. PMID:7084447

  4. 1-Aza-niumyl-cyclo-butane-1-carboxyl-ate monohydrate.

    PubMed

    Butcher, Ray J; Brewer, Greg; Burton, Aaron S; Dworkin, Jason P

    2014-02-01

    In the title compound, C5H9NO2·H2O, the amino acid is in the usual zwitterionic form involving the α-carboxyl-ate group. The cyclo-butane backbone of the amino acid is disordered over two conformations, with occupancies of 0.882 (7) and 0.118 (7). In the crystal, N-H⋯O and O-H⋯O hydrogen bonds link the zwitterions [with the water molecule involved as both acceptor (with the NH3 (+)) and donor (through a single carboxylate O from two different aminocyclobutane carb-oxylate moities)], resulting in a two-dimensional layered structure lying parallel to (100). PMID:24764920

  5. The essential activated carboxyl group of inorganic pyrophosphatase.

    PubMed

    Avaeva, S M; Bakuleva, N P; Baratova, L A; Nazarova, T I; Fink, N Y

    1977-05-12

    1. A carboxyl group of high reactivity has been found in inorganic pyrophosphatase (pyrophosphate phosphohydrolase, EC 3.6.1.1) from yeast. This group interacts with agents which react neither with carboxyl groups of low molecular weight compounds nor with other carboxyl groups of the protein. 2. The reaction of this activated carboxyl group with inorganic phosphate, hydroxylamine, N-methyl- and O-methylhydroxylamines, and glycine methyl ester has been studied. 3. Homoserine and homoserine lactone were found in the hydrolyzate of phosphorylated and NaBH4-reduced pyrophosphatase, indicating that an aspartyl residue is phosphorylated. 4. Hydroxylamine and other nucleophilic agents cause inactivation of pyrophosphatase as a result of interaction with a carboxyl group. Both diaminobutyric and diaminopropionic acids were seen in the acid hydrolyzate of the protein treated with hydroxylamine and subjected to rearrangement in the presence of carbodiimide. 5. The ways in which the activation of a carboxyl group in the enzyme is achieved and the presumed mechanism of action of inorganic pyrophosphatase are discussed. PMID:16652

  6. Decarboxylative homocoupling of (hetero)aromatic carboxylic acids.

    PubMed

    Cornella, Josep; Lahlali, Hicham; Larrosa, Igor

    2010-11-21

    A variety of hetero(aromatic) carboxylic acids are shown to undergo decarboxylative homocoupling, mediated by a Pd/Ag system. This novel methodology for the synthesis of symmetrical biaryls avoids the use of haloarenes and organometallic compounds as starting materials. PMID:20882244

  7. Mechanistic Investigation into the Decarboxylation of Aromatic Carboxylic Acids

    SciTech Connect

    Britt, P F; Buchanan, III, A C; Eskay, T P; Mungall, W S

    1999-08-22

    It has been proposed that carboxylic acids and carboxylates are major contributors to cross-linking reactions in low-rank coals and inhibit its thermochemical processing. Therefore, the thermolysis of aromatic carboxylic acids was investigated to determine the mechanisms of decarboxylation at temperatures relevant to coal processing, and to determine if decarboxylation leads to cross-linking (i.e., formation of more refractory products). From the thcrmolysis of simple and polymeric coal model compounds containing aromatic carboxylic acids at 250-425 °C, decarboxylation was found to occur primarily by an acid promoted ionic pathway. Carboxylate salts were found to enhance the decarboxylation rate, which is consistent with the proposed cationic mechanism. Thermolysis of the acid in an aromatic solvent, such as naphthalene, produced a small amount of arylated products (~5 mol%)), which constitute a low-temperature cross-link. These arylated products were formed by the rapid decomposition of aromatic anhydrides, which are in equilibrium with the acid. These anhydrides decompose by a free radical induced decomposition pathway to form atyl radicals that can add to aromatic rings to form cross-links or abstract hydrogen. Large amounts of CO were formed in the thennolysis of the anhydrides which is consistent with the induced decomposition pathway. CO was also formed in the thermolysis of the carboxylic acids in aromatic solvents which is consistent with the formation and decomposition of the anhydride. The formation of anhydride linkages and cross-links was found to be very sensitive to the reactions conditions. Hydrogen donor solvents, such as tetralin, and water were found to decrease the formation of arylated products. Silar reaction pathways were also found in the thermolysis of a polymeric model that contained aromatic carboxylic acids. In this case, anhydride formation and decomposition produced an insoluble polymer, while the O-methylated polymer and the non-carboxylated

  8. [Synthesis and bronchodilator action of 4-(methoxycarbonylalkylsulfinyl)-4-pyrrol carboxylic esters].

    PubMed

    Eiden, F; Grusdt, U

    1989-11-01

    The dihydro-dimethoxyfuran carboxylic ester 3 reacts with different mercaptoalkyl carboxylates to give the carbomethoxyalkylthio-tetrahydrofuran carboxylic esters 4. Methanol elimination of 4 yields the dihydrofuran derivatives 5. 4 and 5 can be oxidized to afford the sulfoxides 6 and the sulfones 7, respectively. 4 reacts with primary amines to give the title compounds 8. Derivatives of 8 can be cyclized to afford the thienopyrroles 11 and 12 as well as the thienopyranopyrrole 14. The mercaptopyrrole carboxylic ester 10 is obtained from 8f by elimination of propenic acid. 8e shows bronchodilatoric activity in low concentration. PMID:2624526

  9. Breaking the Carboxyl Rule

    PubMed Central

    Balashov, Sergei P.; Petrovskaya, Lada E.; Imasheva, Eleonora S.; Lukashev, Evgeniy P.; Dioumaev, Andrei K.; Wang, Jennifer M.; Sychev, Sergey V.; Dolgikh, Dmitriy A.; Rubin, Andrei B.; Kirpichnikov, Mikhail P.; Lanyi, Janos K.

    2013-01-01

    A lysine instead of the usual carboxyl group is in place of the internal proton donor to the retinal Schiff base in the light-driven proton pump of Exiguobacterium sibiricum (ESR). The involvement of this lysine in proton transfer is indicated by the finding that its substitution with alanine or other residues slows reprotonation of the Schiff base (decay of the M intermediate) by more than 2 orders of magnitude. In these mutants, the rate constant of the M decay linearly decreases with a decrease in proton concentration, as expected if reprotonation is limited by the uptake of a proton from the bulk. In wild type ESR, M decay is biphasic, and the rate constants are nearly pH-independent between pH 6 and 9. Proton uptake occurs after M formation but before M decay, which is especially evident in D2O and at high pH. Proton uptake is biphasic; the amplitude of the fast phase decreases with a pKa of 8.5 ± 0.3, which reflects the pKa of the donor during proton uptake. Similarly, the fraction of the faster component of M decay decreases and the slower one increases, with a pKa of 8.1 ± 0.2. The data therefore suggest that the reprotonation of the Schiff base in ESR is preceded by transient protonation of an initially unprotonated donor, which is probably the ϵ-amino group of Lys-96 or a water molecule in its vicinity, and it facilitates proton delivery from the bulk to the reaction center of the protein. PMID:23696649

  10. Plastic scintillators with high loading of one or more metal carboxylates

    DOEpatents

    Cherepy, Nerine; Sanner, Robert Dean

    2016-01-12

    In one embodiment, a material includes at least one metal compound incorporated into a polymeric matrix, where the metal compound includes a metal and one or more carboxylate ligands, where at least one of the one or more carboxylate ligands includes a tertiary butyl group, and where the material is optically transparent. In another embodiment, a method includes: processing pulse traces corresponding to light pulses from a scintillator material; and outputting a result of the processing, where the scintillator material comprises at least one metal compound incorporated into a polymeric matrix, the at least one metal compound including a metal and one or more carboxylate ligands, where at least one of the one or more carboxylate ligands has a tertiary butyl group, and where the scintillator material is optically transparent and has an energy resolution at 662 keV of less than about 20%.

  11. EFFECT OF CARBOXYLIC IONOPHOROUS ANTIBACTERIALS ON THE GROWTH OF SELECTED MICROALGAE

    EPA Science Inventory

    Carboxylic ionophorous antibiotics are routinely used in cattle, chicken and turkey concentrated feedlot operations as anticoccidial and growth promotant feed additives and may, through runoff and effluents, enter adjacent waterways. The effects of these compounds on the growth o...

  12. Hydrothermal Mineral-Assisted Organic Transformations of Carboxylic Acids

    NASA Astrophysics Data System (ADS)

    Johnson, K. N.; Gould, I.; Williams, L. B.; Hartnett, H. E.; Shock, E.

    2014-12-01

    The purpose of our research is to probe the varieties of reactions possible in a hydrothermal system in which both organic compounds and minerals interact. We performed experiments at physical conditions representative of deep-sea and subsurface systems (300°C and 1000 bar) and analyzed the effect of the mineral magnetite (Fe3O4) in systems with carboxylic acids, either phenylacetic acid or hydrocinnamic acid (a.k.a., phenylpropanoic acid). Control experiments were also conducted with the same organic compounds in the absence of magnetite. Whereas previous studies of carboxylic acid reactivity with minerals have focused exclusively on simple molecules such as acetic acid and valeric acid (Bell et al. 1994; McCollom et al. 2003), the carboxylic acids used in our study differ from previous experimental compounds by the addition of a phenyl ring, which allows for the investigation of the specific mechanistic pathways of product formation. Decarboxylation (i.e., RCO2H → RH + CO2) is one of the major reaction pathways for carboxylic acids in hydrothermal conditions without minerals. Under our experimental conditions, decarboxylation leads to the ~80% conversion of phenylacetic acid into toluene within ~50 hours and the ~8% conversion of hydrocinnamic acid to ethyl benzene within ~190 hours. We found that magnetite had a different effect on the two organic compounds studied. In experiments with phenylacetic acid, the presence of magnetite did not enhance the rate of toluene production from decarboxylation but did activate additional product pathways that include diphenyl alkanes, alkenes, and ketones, as well as benzoic acid, a carboxylic acid one carbon length shorter than the parent compound. Magnetite had even more noticeable effects on the hydrocinnamic acid system leading to an increase of its consumption at 190 hours from ~9% in magnetite's absence to ~35% in the mineral's presence. Products of the experiments with magnetite included an enhanced rate of

  13. Atmospheric chemistry of carboxylic acids: microbial implication versus photochemistry

    NASA Astrophysics Data System (ADS)

    Vaïtilingom, M.; Charbouillot, T.; Deguillaume, L.; Maisonobe, R.; Parazols, M.; Amato, P.; Sancelme, M.; Delort, A.-M.

    2011-02-01

    Clouds are multiphasic atmospheric systems in which the dissolved organic compounds, dominated by carboxylic acids, are subject to multiple chemical transformations in the aqueous phase. Among them, solar radiation, by generating hydroxyl radicals (•OH), is considered as the main catalyzer of the reactivity of organic species in clouds. We investigated to which extent the active biomass existing in cloud water represents an alternative route to the chemical reactivity of carboxylic acids. Pure cultures of seventeen bacterial strains (Arthrobacter, Bacillus, Clavibacter, Frigoribacterium, Pseudomonas, Sphingomonas and Rhodococcus), previously isolated from cloud water and representative of the viable community of clouds were first individually incubated in two artificial bulk cloud water solutions at 17 °C and 5 °C. These solutions mimicked the chemical composition of cloud water from "marine" and "continental" air masses, and contained the major carboxylic acids existing in the cloud water (i.e. acetate, formate, succinate and oxalate). The concentrations of these carboxylic compounds were monitored over time and biodegradation rates were determined. In average, they ranged from 2 ×10-19 for succinate to 1 × 10-18 mol cell-1 s-1 for formate at 17 °C and from 4 × 10-20 for succinate to 6 × 10-19 mol cell-1 s-1 for formate at 5 °C, with no significant difference between "marine" and "continental" media. In parallel, irradiation experiments were also conducted in these two artificial media to compare biodegradation and photodegradation of carboxylic compounds. To complete this comparison, the photodegradation rates of carboxylic acids by •OH radicals were calculated from literature data. Inferred estimations suggested a significant participation of microbes to the transformation of carboxylic acids in cloud water, particularly for acetate and succinate (up to 90%). Furthermore, a natural cloud water sample was incubated (including its indigenous microflora

  14. Oxidation reaction of high molecular weight carboxylic acids in supercritical water.

    PubMed

    Jin, Fangming; Moriya, Takehiko; Enomoto, Heiji

    2003-07-15

    Stearic acid, being a model compound of high molecular weight carboxylic acids, was oxidized in a batch reactor by changing the oxygen supply with an insufficient oxygen supply at a constant reaction time at 420 degrees C. On the basis of the intermediate products identified by GC/MS, NMR, and HPLC analyses and the free-radical reaction mechanism, the oxidation pathways of high molecular weight carboxylic acids in supercritical water are discussed. The reaction of carboxylic acids in supercritical water proceeds with the consecutive oxidation of higher molecular weight carboxylic acids to lower molecular weight carboxylic acids through several major pathways. The attack of the hydroxyl radical occurs not only at the carbons in alpha-, beta-, gamma-positions to a --COOH group but also at the carbons ((omega-1)-carbon and/or omega-carbon) far in the alkyl chain from a --COOH group, which may lead to the formation of dicarboxylic acids. PMID:12901673

  15. Carboxylic Acids as Indicators of Parent Body Conditions

    NASA Technical Reports Server (NTRS)

    Lerner N. R.; Chang, Sherwood (Technical Monitor)

    1995-01-01

    Alpha-hydroxy and alpha-amino carboxylic acids found on the Murchison meteorite are deuterium enriched. It is postulated that they arose from a common interstellar scurce: the reaction of carbonyl compounds in an aqueous mixture containing HCN and NH3. Carbonyl compounds react with HCN to form alpha-hydroxy nitriles, RR'CO + HCN right and left arrow RR'C(OH)CN. If ammonia is also present, the alpha-hydroxy nitriles will exist in equilibrium with the alpha-amino nitriles, RR'C(OH)CN + NH3 right and left arrow - RRCNH2CN + H2O. Both nitrites are hydrolyzed by water to form carboxylic acids: RR'C(OH)CN + H2O yields RR'C(OH)CO2H and RR'C(NH2)CN + H2O yields RR'C(NH2)CO2H.

  16. (2SR,4aSR,8aSR)-6-Oxoperhydro­naphthalene-2-carboxylic acid

    PubMed Central

    Efthimiopoulos, Georgia; Davison, Mark; Lalancette, Roger A.; Thompson, Hugh W.

    2009-01-01

    In the title racemic compound, C11H16O3, the mol­ecule adopts a conformation that places its carboxyl group in an equatorial position. Mol­ecules aggregate by hydrogen-bond pairing of carboxyl groups, yielding centrosymmetric dimers that are arranged into layers in the (020) planes. PMID:21581624

  17. 2-(2-Chloro-phen-yl)-5-methyl-1,3-dioxane-5-carboxylic acid.

    PubMed

    Jia, Guo-Kai; Yuan, Lin; Zhang, Min; Yuan, Xian-You

    2012-07-01

    In the title compound, C(12)H(13)ClO(4), the 1,3-dioxane ring adopts a chair conformation and the 2-chloro-benzene and methyl substituents occupy equatorial sites. The carboxyl group is in an axial inclination. In the crystal, carb-oxy-lic acid inversion dimers linked by pairs of O-H⋯O hydrogen bonds generate R(2) (2)(8) loops. PMID:22807863

  18. Organometallic carboxylate resists for extreme ultraviolet with high sensitivity

    NASA Astrophysics Data System (ADS)

    Passarelli, James; Murphy, Michael; Re, Ryan Del; Sortland, Miriam; Hotalen, Jodi; Dousharm, Levi; Fallica, Roberto; Ekinci, Yasin; Neisser, Mark; Freedman, Daniel A.; Brainard, Robert L.

    2015-10-01

    We have developed organometallic carboxylate compounds [RnM)] capable of acting as negative-tone extreme ultraviolet (EUV) resists. The most sensitive of these resists contain antimony, three R-groups and two carboxylate groups, and carboxylate groups with polymerizable olefins (e.g., acrylate, methacrylate, or styrenecarboxylate). Evidence suggests that high sensitivity is achieved through the polymerization of olefins in the exposed region. We have performed a systematic sensitivity study of the molecules of the type RnM) where we have studied seven R groups, four main group metals (M), and three polymerizable carboxylate groups (O2CR‧). The sensitivity of these resists was evaluated using Emax or dose to maximum resist thickness after exposure and development. We found that the greatest predictor of sensitivity of the RnSb) resists is their level of polymerizable olefins. We mathematically define the polymerizable olefin loading (POL) as the ratio of the number of olefins versus the number of nonhydrogen atoms. Linear and log plots of Emax versus POL for a variety of molecules of the type R3Sb) lend insight into the behavior of these resists.

  19. Asymmetric synthesis of crambescin A-C carboxylic acids and their inhibitory activity on voltage-gated sodium channels.

    PubMed

    Nakazaki, Atsuo; Nakane, Yoshiki; Ishikawa, Yuki; Yotsu-Yamashita, Mari; Nishikawa, Toshio

    2016-06-21

    Synthesis of both enantiomers of crambescin B carboxylic acid is described. A cis-enyne starting material was epoxidized under the conditions of Katsuki asymmetric epoxidation to give 95% ee of the epoxide, which was transformed to crambescin B carboxylic acid via bromocation-triggered cascade cyclization as the key step. Enantiomerically pure crambescin A and C carboxylic acids were also synthesized from the product of the cascade reaction. Structure-activity relationship (SAR) studies against voltage-gated sodium channel (VGSC) inhibition using those synthetic compounds revealed that the natural enantiomer of crambescin B carboxylic acid was most active and comparable to tetrodotoxin, and the unalkylated cyclic guanidinium structure is indispensible, while the carboxylate moiety is not important. The absolute stereochemistry of crambescin A was determined by a comparison of the methyl ester derived from natural crambescin A with that derived from the stereochemically defined crambescin A carboxylic acid synthesized in this study. PMID:27215973

  20. Biarylalkyl Carboxylic Acid Derivatives as Novel Antischistosomal Agents.

    PubMed

    Mäder, Patrick; Blohm, Ariane S; Quack, Thomas; Lange-Grünweller, Kerstin; Grünweller, Arnold; Hartmann, Roland K; Grevelding, Christoph G; Schlitzer, Martin

    2016-07-01

    Parasitic platyhelminths are responsible for serious infectious diseases, such as schistosomiasis, which affect humans as well as animals across vast regions of the world. The drug arsenal available for the treatment of these diseases is limited; for example, praziquantel is the only drug currently used to treat ≥240 million people each year infected with Schistosoma spp., and there is justified concern about the emergence of drug resistance. In this study, we screened biarylalkyl carboxylic acid derivatives for their antischistosomal activity against S. mansoni. These compounds showed significant influence on egg production, pairing stability, and vitality. Tegumental lesions or gut dilatation was also observed. Substitution of the terminal phenyl residue in the biaryl scaffold with a 3-hydroxy moiety and derivatization of the terminal carboxylic acid scaffold with carboxamides yielded compounds that displayed significant antischistosomal activity at concentrations as low as 10 μm with satisfying cytotoxicity values. The present study provides detailed insight into the structure-activity relationships of biarylalkyl carboxylic acid derivatives and thereby paves the way for a new drug-hit moiety for fighting schistosomiasis. PMID:27159334

  1. Structure Property Relationships of Carboxylic Acid Isosteres

    PubMed Central

    2016-01-01

    The replacement of a carboxylic acid with a surrogate structure, or (bio)-isostere, is a classical strategy in medicinal chemistry. The general underlying principle is that by maintaining the features of the carboxylic acid critical for biological activity, but appropriately modifying the physicochemical properties, improved analogs may result. In this context, a systematic assessment of the physicochemical properties of carboxylic acid isosteres would be desirable to enable more informed decisions of potential replacements to be used for analog design. Herein we report the structure–property relationships (SPR) of 35 phenylpropionic acid derivatives, in which the carboxylic acid moiety is replaced with a series of known isosteres. The data set generated provides an assessment of the relative impact on the physicochemical properties that these replacements may have compared to the carboxylic acid analog. As such, this study presents a framework for how to rationally apply isosteric replacements of the carboxylic acid functional group. PMID:26967507

  2. Crystal structure of ethyl 2-(3,5-di-fluoro-phen-yl)quinoline-4-carboxyl-ate.

    PubMed

    Sunitha, V M; Naveen, S; Manjunath, H R; Benaka Prasad, S B; Manivannan, V; Lokanath, N K

    2015-05-01

    In the title compound, C18H13F2NO2, the two rings of the quinoline system are fused almost coaxially, with a dihedral angle between their planes of 2.28 (8)°. The plane of the attached benzene ring is inclined to the plane of the quinoline system by 7.65 (7)°. The carboxyl-ate group attached to the quinoline system is in an anti-periplanar conformation. There is a short intra-molecular C-H⋯O contact involving the carbonyl group. In the crystal, mol-ecules are linked via C-H⋯O hydrogen bonds, forming chains lying in the (1-10) plane. PMID:25995938

  3. Recovery of carboxylic acids produced by fermentation.

    PubMed

    López-Garzón, Camilo S; Straathof, Adrie J J

    2014-01-01

    Carboxylic acids such as citric, lactic, succinic and itaconic acids are useful products and are obtained on large scale by fermentation. This review describes the options for recovering these and other fermentative carboxylic acids. After cell removal, often a primary recovery step is performed, using liquid-liquid extraction, adsorption, precipitation or conventional electrodialysis. If the carboxylate is formed rather than the carboxylic acid, the recovery process involves a step for removing the cation of the formed carboxylate. Then, bipolar electrodialysis and thermal methods for salt splitting can prevent that waste inorganic salts are co-produced. Final carboxylic acid purification requires either distillation or crystallization, usually involving evaporation of water. Process steps can often be combined synergistically. In-situ removal of carboxylic acid by extraction during fermentation is the most popular approach. Recovery of the extractant can easily lead to waste inorganic salt formation, which counteracts the advantage of the in-situ removal. For industrial production, various recovery principles and configurations are used, because the fermentation conditions and physical properties of specific carboxylic acids differ. PMID:24751382

  4. Analysis of Chiral Carboxylic Acids in Meteorites

    NASA Technical Reports Server (NTRS)

    Burton, A. S.; Elsila, J. E.; Hein, J. E.; Aponte, J. C.; Parker, E. T.; Glavin, D. P.; Dworkin, J. P.

    2015-01-01

    Homochirality of amino acids in proteins and sugars in DNA and RNA is a critical feature of life on Earth. In the absence of a chiral driving force, however, reactions leading to the synthesis of amino acids and sugars result in racemic mixtures. It is currently unknown whether homochirality was necessary for the origins of life or if it was a product of early life. The observation of enantiomeric excesses of certain amino acids of extraterrestrial origins in meteorites provides evidence to support the hypothesis that there was a mechanism for the preferential synthesis or destruction of a particular amino acid enantiomer [e.g., 1-3]. The cause of the observed chiral excesses is un-clear, although at least in the case of the amino acid isovaline, the degree of aqueous alteration that occurred on the meteorite parent body is correlated to the isovaline L-enantiomeric excess [3, 4]. This suggests that chiral symmetry is broken and/or amplified within the meteorite parent bodies. Besides amino acids, there have been only a few reports of other meteoritic compounds found in enantiomeric excess: sugars and sugar acids [5, 6] and the hydroxy acid lactic acid [7]. Determining whether or not additional types of molecules in meteorites are also present in enantiomeric excesses of extraterrestrial information will provide insights into mechanisms for breaking chiral symmetry. Though the previous measurements (e.g., enantiomeric composition of lactic acid [7], and chiral carboxylic acids [8]) were made by gas chromatography-mass spectrometry, the potential for increased sensitivity of liquid chromatography-mass spectrometry (LC-MS) analyses is important because for many meteorite samples, only small sample masses are available for study. Furthermore, at least in the case of amino acids, many of the largest amino acid enantiomeric excesses were observed in samples that contained lower abundances (tens of ppb) of a given amino acid enantiomer. In the present work, we describe

  5. Synthesis, structural investigations, and anti-cancer activity of new methyl indole-3-carboxylate derivatives

    NASA Astrophysics Data System (ADS)

    Niemyjska, Maria; Maciejewska, Dorota; Wolska, Irena; Truszkowski, Paweł

    2012-10-01

    Two new methyl indole-3-carboxylate derivatives: methyl 1-(3'-indolylmethane)-indole-3-carboxylate (1), and methyl 1-(1'-benzenosulfonyl-3'-indolylmethane)-indole-3-carboxylate (2) were synthesized. They are interesting as the analogs of 3,3'-diindolylmethane, which is intensively tested as a potent antitumor agent. Their solid-state structure was characterized using 13C CP/MAS NMR or X-ray diffraction measurements. Molecular modeling was used as a help in the structure elucidation. The solid-state NMR spectroscopy showed only one stable conformer of 1, but the X-ray diffraction results indicate that compound 2 crystallizes in the triclinic space group P-1 with two molecules, A and B, in the asymmetric unit. Both compounds inhibited the growth of melanoma, renal and breast cancers cell lines.

  6. Synthesis and Functionalization of Cyclic Sulfonimidamides: A Novel Chiral Heterocyclic Carboxylic Acid Bioisostere

    PubMed Central

    2012-01-01

    An efficient synthesis of aryl substituted cyclic sulfonimidamides designed as chiral nonplanar heterocyclic carboxylic acid bioisosteres is described. The cyclic sulfonimidamide ring system could be prepared in two steps from a trifluoroacetyl protected sulfinamide and methyl ester protected amino acids. By varying the amino acid, a range of different C-3 substituted sulfonimidamides could be prepared. The compounds could be further derivatized in the aryl ring using standard cross-coupling reactions to yield highly substituted cyclic sulfonimidamides in excellent yields. The physicochemical properties of the final compounds were examined and compared to those of the corresponding carboxylic acid and tetrazole derivatives. The unique nonplanar shape in combination with the relatively strong acidity (pKa 5–6) and the ease of modifying the chemical structure to fine-tune the physicochemical properties suggest that this heterocycle can be a valuable addition to the range of available carboxylic acid isosteres. PMID:24900513

  7. Carboxylation and anaplerosis in neurons and glia.

    PubMed

    Hassel, B

    2000-01-01

    Anaplerosis, or de novo formation of intermediates of the tricarboxylic acid (TCA) cycle, compensates for losses of TCA cycle intermediates, especially alpha-ketoglutarate, from brain cells. Loss of alpha-ketoglutarate occurs through release of glutamate and GABA from neurons and through export of glutamine from glia, because these amino acids are alpha-ketoglutarate derivatives. Anaplerosis in the brain may involve four different carboxylating enzymes: malic enzyme, phosphoenopyruvate carboxykinase (PEPCK), propionyl-CoA carboxylase, and pyruvate carboxylase. Anaplerotic carboxylation was for many years thought to occur only in glia through pyruvate carboxylase; therefore, loss of transmitter glutamate and GABA from neurons was thought to be compensated by uptake of glutamine from glia. Recently, however, anaplerotic pyruvate carboxylation was demonstrated in glutamatergic neurons, meaning that these neurons to some extent can maintain transmitter synthesis independently of glutamine. Malic enzyme, which may carboxylate pyruvate, was recently detected in neurons. The available data suggest that neuronal and glial pyruvate carboxylation could operate at as much as 30% and 40-60% of the TCA cycle rate, respectively. Cerebral carboxylation reactions are probably balanced by decarboxylation reactions,, because cerebral CO2 formation equals O2 consumption. The finding of pyruvate carboxylation in neurons entails a major revision of the concept of the glutamine cycle. PMID:11414279

  8. (S) 2-phenyl-2-(p-tolylsulfonylamino)acetic acid. Structure, acidity and its alkali carboxylates

    NASA Astrophysics Data System (ADS)

    Duarte-Hernández, Angélica M.; Contreras, Rosalinda; Suárez-Moreno, Galdina V.; Montes-Tolentino, Pedro; Ramos-García, Iris; González, Felipe J.; Flores-Parra, Angelina

    2015-03-01

    The structure and the preferred conformers of (S) 2-phenyl-2-(p-tolylsulfonylamino)acetic acid (1) are reported. Compound 1 is a derivative of the unnatural aminoacid the (S) phenyl glycine. The X-ray diffraction analyses of the complexes of 1 with water, methanol, pyridine and its own anion are discussed. In order to add information about the acidity of the COOH and NH protons in compound 1, its pKa in DMSO and those of N-benzyl-p-tolylsulfonamide and (S) N-methylbenzyl-p-tolylsulfonamide were determined by cyclic voltammetry. Data improved the scarce information about pKa in DMSO values of sulfonamides. The products of the reactions of compound 1 with one and two equivalents of LiOH, NaOH and KOH in methanol were analyzed. Crystals of the lithium (2) and sodium (3) carboxylates and the dipotassium sulfonylamide acetate (7) were obtained, they are coordination polymers. In compound 2, the lithium is bound to four oxygen atoms with short bond lengths. The coordination of the lithium atom to two carboxylates gives an infinite ribbon by formation of fused six membered rings. In the crystal of compound 3, two pentacoordinated sodium atoms are bridged by three oxygen atoms, one from a water molecule and two from DMSO. The short distance between the sodium atoms (3.123 Å), implies a metal-metal interaction. The sodium couples are linked by two carboxylate groups, forming a planar ribbon of fused twelve membered rings. A notable discovery was a water molecule quenched in the middle of the ring, with a tetra coordinated oxygen atom in a square planar geometry. In compound 7, the carboxylate and the amide are bound to heptacoordinated potassium atoms. The 2D polymer of 7 has a sandwich structure, with the carboxylate and potassium atoms in the inner layer covered by the aromatic rings.

  9. Synthesis of tryptoline-3-carboxylic Acid derivatives a novel antidiabetic agent.

    PubMed

    Choudhary, An; Kohli, Ms; Kumar, A; Joshi, A

    2011-04-01

    The compounds, 2-(methylsulfonyl)-1,2,3,4-tetrahydro-9H-pyrido[3,4-b]indole-3-carboxylic acid (DM3), 2-(phenylsulfonyl)-1,2,3,4-tetrahydro-9H-pyrido[3,4-b]indole-3-carboxylic acid (DM(4)), and 2-(p-toluenesulfonyl)-1,2,3,4-tetrahydro-9H-pyrido[3,4-b]indole-3-carboxylic acid (DM(5)) were synthesized by coupling of 1,2,3,4-tetrahydro-9H-pyrido[3,4-b]indole-3-carboxylic acid (DM(2)) with methanesulfonyl chloride, benzenesulfonyl chloride, and toluenesulfonyl chloride, which in turn, was synthesized by dissolving dilute aqueous ammonia with 2-(N-hydroxy methyl amino)-indol-3-yl-propanoic acid (DM(1)) which is the reaction product of l-tryptophan and formalin. All the intermediates and title compounds were characterized by physical, chemical, analytical, and spectral data. All the title compounds have been screened for in vivo antidiabetic activity in streptozotocin-induced diabetic rats, and serum glucose was estimated spectrophotometrically at 505 nm by glucose oxidase/peroxidase method. Compound DM(5) showed potent antidiabetic activity. PMID:21731359

  10. Montiporic acid D, a new polyacetylene carboxylic acid from scleractinian coral Montipora digitata.

    PubMed

    Kodani, Shinya; Sato, Kanna; Higuchi, Tomihiko; Casareto, Beatriz E; Suzuki, Yoshimi

    2013-10-01

    A new polyacetylene carboxylic acid named montiporic acid D (1) was isolated along with a known polyacetylene alcohol, (Z)-13,15-hexadecadien-2,4-diyn-1-ol (2) from scleractinian coral Montipora digitata. The structures of compounds were determined by analyses of NMR and MS spectra. PMID:23432335

  11. Carboxylic acid accelerated formation of diesters

    DOEpatents

    Tustin, G.C.; Dickson, T.J.

    1998-04-28

    This invention pertains to accelerating the rate of formation of 1,1-dicarboxylic esters from the reaction of an aldehyde with a carboxylic acid anhydride or a ketene in the presence of a non-iodide containing a strong Bronsted acid catalyst by the addition of a carboxylic acid at about one bar pressure and between about 0 and 80 C in the substantial absence of a hydrogenation or carbonylation catalyst.

  12. Carboxylic acid accelerated formation of diesters

    DOEpatents

    Tustin, Gerald Charles; Dickson, Todd Jay

    1998-01-01

    This invention pertains to accelerating the rate of formation of 1,1-dicarboxylic esters from the reaction of an aldehyde with a carboxylic acid anhydride or a ketene in the presence of a non-iodide containing a strong Bronsted acid catalyst by the addition of a carboxylic acid at about one bar pressure and between about 0.degree. and 80.degree. C. in the substantial absence of a hydrogenation or carbonylation catalyst.

  13. Reaction of organic compounds with the SF/sub 4/-HF system in the presence of halogenating agents. III. Reaction of furan-2-carboxylic and 5-chloro-furancarboxylic acids with sulfur tetrafluoride in hydrogen fluoride in the presence of chlorine or sulfur monochloride

    SciTech Connect

    Kunshenko, B.V.; Il'nitskii, S.O.; Motnyak, L.A.; Lyalin, V.V.; Yagupol'skii, L.M.

    1987-09-20

    In the reaction of furan-2-carboxylic and 5-chlorofuran-2-carboxylic acids with the SF/sub 4/-HF-S/sub 2/Cl/sub 2/ system stoichiometric equivalents of S/sub 2/ClF add at positions 2,5 of the furan ring followed by substitution of the thiosulfenyl chloride group by fluorine, in addition to the transformation of the carboxyl group into a trifluoromethyl group. Chlorofluorination of the furan ring takes place in the reactions of these acids with the SF/sub 4/-HF-Cl/sub 2/ system. The cis-and trans-dihydrofurans were isolated in the individual form by preparative GLC, and their structures were proved by /sup 19/F and /sup 1/H NMR spectroscopy.

  14. Understanding biocatalyst inhibition by carboxylic acids.

    PubMed

    Jarboe, Laura R; Royce, Liam A; Liu, Ping

    2013-01-01

    Carboxylic acids are an attractive biorenewable chemical in terms of their flexibility and usage as precursors for a variety of industrial chemicals. It has been demonstrated that such carboxylic acids can be fermentatively produced using engineered microbes, such as Escherichia coli and Saccharomyces cerevisiae. However, like many other attractive biorenewable fuels and chemicals, carboxylic acids become inhibitory to these microbes at concentrations below the desired yield and titer. In fact, their potency as microbial inhibitors is highlighted by the fact that many of these carboxylic acids are routinely used as food preservatives. This review highlights the current knowledge regarding the impact that saturated, straight-chain carboxylic acids, such as hexanoic, octanoic, decanoic, and lauric acids can have on E. coli and S. cerevisiae, with the goal of identifying metabolic engineering strategies to increase robustness. Key effects of these carboxylic acids include damage to the cell membrane and a decrease of the microbial internal pH. Certain changes in cell membrane properties, such as composition, fluidity, integrity, and hydrophobicity, and intracellular pH are often associated with increased tolerance. The availability of appropriate exporters, such as Pdr12, can also increase tolerance. The effect on metabolic processes, such as maintaining appropriate respiratory function, regulation of Lrp activity and inhibition of production of key metabolites such as methionine, are also considered. Understanding the mechanisms of biocatalyst inhibition by these desirable products can aid in the engineering of robust strains with improved industrial performance. PMID:24027566

  15. Poly[μ6-(naphthalene-2,6-di-carboxyl-ato)-bis-(aqua-lithium)].

    PubMed

    Fédèle, Lionel; Sauvage, Frédéric; Becuwe, Matthieu; Chotard, Jean-Noël

    2014-08-01

    The title compound, [Li2(C12H6O4)(H2O)2] n , crystallizes with one half of the molecular entities in the asymmetric unit. The second half is gererated by inversion symmetry. The crystal structure has a layered arrangement built from distorted edge-sharing LiO3(OH)2 tetra-hedra parallel to (100), with naphthalenedi-carboxyl-ate bridging the LiO3(OH)2 layers along the [100] direction. Hydrogen bonding between the water molecule and adjacent carboxylate groups consolidates the packing. PMID:25249875

  16. Syntheses, characterization and fluorescent properties of two triethylene-glycol dicoumarin-3-carboxylates.

    PubMed

    Zhang, Hui; Yu, Tianzhi; Zhao, Yuling; Fan, Duowang; Qian, Long; Yang, Changhui; Zhang, Kai

    2007-11-01

    Two novel triethylene-glycol dicoumarin-3-carboxylates were synthesized and characterized by element analysis, (1)H NMR, FT-IR and UV-vis absorption spectra. The photoluminescent behaviors of triethylene-glycol dibenzo[5,6]coumarin-3-carboxylate doped in PMMA were discussed. These compounds exhibit strong blue emission under ultraviolet light excitation. Compared to coumarin-3-triethylene glycol diester, the absorption and emission spectra of benzo[5,6]coumarin-3-triethylene glycol diester was bathochromically shifted due to the larger conjugation of benzene moiety. These derivatives have potential possible to explore organic electroluminescent materials. PMID:17418628

  17. Design, synthesis, and testing of an isoquinoline-3-carboxylic-based novel anti-tumor lead.

    PubMed

    Gao, Fei; Liu, Haiqing; Li, Li; Guo, Jianpeng; Wang, Yuji; Zhao, Ming; Peng, Shiqi

    2015-10-15

    Compound 6, a novel isoquinoline comprising two isoquinoline-3-carboxylic acids and a benzoic acid conjugated together using tris(2-aminoethyl)amine, was synthesized and tested for anti-tumor activity. In vivo evaluations found 6 to be well tolerated, of high therapeutic efficacy and of low systemic toxicity, at effective doses. The results suggest 6 to be a promising lead for future study, and the use of multiple isoquinoline-3-carboxylic acid moieties as pharmacophores in the same molecule to be a useful strategy for the design of anti-tumor drugs. PMID:26386603

  18. (±)-trans-3-Benzoyl-bicyclo-[2.2.2]octane-2-carboxylic acid.

    PubMed

    Lalancette, Roger A; Thompson, Hugh W; Brunskill, Andrew P J

    2008-01-01

    The title keto acid, C(16)H(18)O(3), displays significant twisting of all three ethyl-ene bridges in its bicyclo-[2.2.2]octane structure owing to steric inter-actions; the bridgehead-to-bridgehead torsion angles are 13.14 (12), 13.14 (13) and 9.37 (13)°. The compound crystallizes as centrosymmetric carboxyl dimers [O⋯O = 2.6513 (12) Å and O-H⋯O = 178°], which have two orientations within the cell and contain no significant carboxyl disorder. PMID:21201657

  19. Determination of carboxylic acids in oil samples by capillary gas chromatography/mass spectrometry

    SciTech Connect

    Shen, J.

    1981-03-01

    A combined gas chromatography/mass spectrometric (GC/MS) method for measuring carboxylic acids in oil samples without first going through solvent extraction and group separation is reported. The carboxylic acids in oils are directly derivatized to their corresponding methyl esters via anion formation in tetramethylammonium hydroxide/methanol/methyl iodide/n-butyl acetate solutions prior to GC/MS analysis using a glass wall coated capillary column. The reaction is mild, selective, and rapid. It can usually be carried out at room temperature and completed in 10 to 15 min. Multiple ion detection techniques (MID) can be readily used to further resolve methyl esters from other compounds if necessary.

  20. Ni- and Fe-catalyzed Carboxylation of Unsaturated Hydrocarbons with CO2.

    PubMed

    Juliá-Hernández, Francisco; Gaydou, Morgane; Serrano, Eloisa; van Gemmeren, Manuel; Martin, Ruben

    2016-08-01

    The sustainable utilization of available feedstock materials for preparing valuable compounds holds great promise to revolutionize approaches in organic synthesis. In this regard, the implementation of abundant and inexpensive carbon dioxide (CO2) as a C1 building block has recently attracted considerable attention. Among the different alternatives in CO2 fixation, the preparation of carboxylic acids, relevant motifs in pharmaceuticals and agrochemicals, is particularly appealing, thus providing a rapid and unconventional entry to building blocks that are typically prepared via waste-producing protocols. While significant advances have been realized, the utilization of simple unsaturated hydrocarbons as coupling partners in carboxylation events is undoubtedly of utmost academic and industrial relevance, as two available feedstock materials can be combined in a catalytic fashion. This review article aims to describe the main achievements on the direct carboxylation of unsaturated hydrocarbons with CO2 by using cheap and available Ni or Fe catalytic species. PMID:27573397

  1. Assays for the classification of two types of esterases: carboxylic ester hydrolases and phosphoric triester hydrolases.

    PubMed

    Anspaugh, Douglas D; Roe, R Michael

    2002-11-01

    Assays for the Classification of Two Types of Esterases: Carboxylic Ester Hydrolase and Phosphoric Triester Hydrolase (Douglas D. Anspaugh and Michael Roe, North Carolina State University, Raleigh, North Carolina). This unit describes assays that quantitate two types of esterase the carboxylic ester hydrolases and the phosphoric triester hydrolases. Carboxylic ester hydrolases include the B-esterases, which are inhibited by organophosphorus compounds. Among the phosphoric triester hydrolases is aryldialkylphosphatase, which has been called A-esterase or paraoxonase due to its ability to oxidize paraoxon and other organophosphates. These assays are colorimetric and miniaturized for rapid simultaneous testing of multiple, small-volume samples in a microtiter plate format. There is also a discussion of the history of esterase nomenclature and the reasons why this large group of enzymes is so difficult to classify. PMID:20945297

  2. Enantioselective kinetic resolution of phenylalkyl carboxylic acids using metagenome‐derived esterases

    PubMed Central

    Fernández‐Álvaro, Elena; Kourist, Robert; Winter, Julia; Böttcher, Dominique; Liebeton, Klaus; Naumer, Christian; Eck, Jürgen; Leggewie, Christian; Jaeger, Karl‐Erich; Streit, Wolfgang; Bornscheuer, Uwe T.

    2010-01-01

    Summary Enantiomerically pure β‐arylalkyl carboxylic acids are important synthetic intermediates for the preparation of a wide range of compounds with biological and pharmacological activities. A library of 83 enzymes isolated from the metagenome was searched for activity in the hydrolysis of ethyl esters of three racemic phenylalkyl carboxylic acids by a microtiter plate‐based screening using a pH‐indicator assay. Out of these, 20 enzymes were found to be active and were subjected to analytical scale biocatalysis in order to determine their enantioselectivity. The most enantioselective and also enantiocomplementary biocatalysts were then used for preparative scale reactions. Thus, both enantiomers of each of the three phenylalkyl carboxylic acids studied could be obtained in excellent optical purity and high yields. PMID:21255306

  3. A new carboxyl-copper-organic framework and its excellent selective absorbability for proteins

    NASA Astrophysics Data System (ADS)

    Yang, Linyan; Xin, Liangliang; Gu, Wen; Tian, Jinlei; Liao, Shengyun; Du, Peiyao; Tong, Yuzhang; Zhang, Yanping; Lv, Rui; Wang, Jingyao; Liu, Xin

    2014-10-01

    One-pot solvothermal treatments of CuCl2·2H2O, H2L (5-(3-methyl-5-(pyridin-4-yl)-4H-1,2,4-triazol-4-yl) isophthalic acid) and Sm(NO3)3·6H2O in water yielded a rare carboxyl-copper-organic framework, [Cu(HL)]n·nH2O (1). The existence of carboxyl groups in compound 1 may be due to the interference of Sm(NO3)3·6H2O at the relatively high temperature and autogenous pressure of the reaction. Compound 1 has been characterized by single-crystal X-ray diffraction, PXRD, IR, and elemental analysis. Compound 1 is a 3D coordination polymer, and an xfe-4-Fddd, (42.6.83) topology in 1 is created. In addition, the optical properties have been investigated. Rhodamine B dyeing experiments exhibited that there were residual carboxyl groups on the surface of compound 1. UV-vis results showed that more lysozyme was adsorbed onto the surface of compound 1 than BSA at pH 7.4. At the same time, XPS spectra were also investigated to verify the results.

  4. Atmospheric chemistry of carboxylic acids: microbial implication versus photochemistry

    NASA Astrophysics Data System (ADS)

    Vaïtilingom, M.; Charbouillot, T.; Deguillaume, L.; Maisonobe, R.; Parazols, M.; Amato, P.; Sancelme, M.; Delort, A.-M.

    2011-08-01

    The objective of this work was to compare experimentally the contribution of photochemistry vs. microbial activity to the degradation of carboxylic acids present in cloud water. For this, we selected 17 strains representative of the microflora existing in real clouds and worked on two distinct artificial cloud media that reproduce marine and continental cloud chemical composition. Photodegradation experiments with hydrogen peroxide (H2O2) as a source of hydroxyl radicals were performed under the same microcosm conditions using two irradiation systems. Biodegradation and photodegradation rates of acetate, formate, oxalate and succinate were measured on both media at 5 °C and 17 °C and were shown to be on the same order of magnitude (around 10-10-10-11 M s-1). The chemical composition (marine or continental origin) had little influence on photodegradation and biodegradation rates while the temperature shift from 17 °C to 5 °C decreased biodegradation rates of a factor 2 to 5. In order to test other photochemical scenarios, theoretical photodegradation rates were calculated considering hydroxyl (OH) radical concentration values in cloud water estimated by cloud chemistry modelling studies and available reaction rate constants of carboxylic compounds with both hydroxyl and nitrate radicals. Considering high OH concentration ([OH] = 1 × 10-12 M) led to no significant contribution of microbial activity in the destruction of carboxylic acids. On the contrary, for lower OH concentration (at noon, [OH] = 1 × 10-14 M), microorganisms could efficiently compete with photochemistry and in similar contributions than the ones estimated by our experimental approach. Combining these two approaches (experimental and theoretical), our results led to the following conclusions: oxalate was only photodegraded; the photodegradation of formate was usually more efficient than its biodegradation; the biodegradation of acetate and succinate seemed to exceed their photodegradation.

  5. Di-μ-aqua-bis-[aqua-(5-carboxyl-ato-1H-1,2,3-triazole-4-carb-oxy-lic acid-κ(2) N (3),O (4))lithium].

    PubMed

    Starosta, Wojciech; Leciejewicz, Janusz

    2013-01-01

    The crystal structure of the title compound, [Li2(C4H2N3O4)2(H2O)4], contains centrosymmetric dinuclear mol-ecules in which two Li(I) ions are bridged by two water O atoms. The metal ion is coordinated by one N,O-bidentate ligand and three water O atoms (one of them is symmetry generated), with one of the bridging water O atoms in the apical position of a distorted square pyramid. The carboxyl-ate group that participates in coordination to the metal ion remains protonated; the other is deprotonated and coordination inactive. An intra-molecular O-H⋯O hydrogen bond between carboxyl-ate groups is observed. In the crystal, dimers are linked by O-H⋯O, O-H⋯N and N-H⋯O hydrogen bonds, generating a three-dimensional network. PMID:24427005

  6. Hygroscopic Characteristics of Alkylaminium Carboxylate Aerosols.

    PubMed

    Gomez-Hernandez, Mario; McKeown, Megan; Secrest, Jeremiah; Marrero-Ortiz, Wilmarie; Lavi, Avi; Rudich, Yinon; Collins, Don R; Zhang, Renyi

    2016-03-01

    The hygroscopic growth factor (HGF) and cloud condensation nuclei (CCN) activity for a series of alkylaminium carboxylate aerosols have been measured using a hygroscopicity tandem differential mobility analyzer coupled to a condensation particle counter and a CCN counter. The particles, consisting of the mixtures of mono- (acetic, propanoic, p-toluic, and cis-pinonic acid) and dicarboxylic (oxalic, succinic, malic, adipic, and azelaic acid) acid with alkylamine (mono-, di-, and trimethylamines), represent those commonly found under diverse environmental conditions. The hygroscopicity parameter (κ) of the alkylaminium carboxylate aerosols was derived from the HGF and CCN results and theoretically calculated. The HGF at 90% RH is in the range of 1.3 to 1.8 for alkylaminium monocarboxylates and 1.1 to 2.2 for alkylaminium dicarboxylates, dependent on the molecular functionality (i.e., the carboxylic or OH functional group in organic acids and methyl substitution in alkylamines). The κ value for all alkylaminium carboxylates is in the range of 0.06-1.37 derived from the HGF measurements at 90% RH, 0.05-0.49 derived from the CCN measurements, and 0.22-0.66 theoretically calculated. The measured hygroscopicity of the alkylaminium carboxylates increases with decreasing acid to base ratio. The deliquescence point is apparent for several of the alkylaminium dicarboxylates but not for the alkylaminium monocarboxylates. Our results reveal that alkylaminium carboxylate aerosols exhibit distinct hygroscopic and deliquescent characteristics that are dependent on their molecular functionality, hence regulating their impacts on human health, air quality, and direct and indirect radiative forcing on climate. PMID:26794419

  7. Mass spectrometric behaviour of carboxylated polyethylene glycols and carboxylated octylphenol ethoxylates.

    PubMed

    Frańska, Magdalena; Zgoła, Agnieszka; Rychłowska, Joanna; Szymański, Andrzej; Łukaszewski, Zenon; Frański, Rafał

    2003-01-01

    Mass spectrometric behaviour of mono- and di-carboxylated polyethylene glycols (PEGCs and CPEGCs) and carboxylated octylphenol ethoxylates (OPECs) are discussed. The tendency for ionisation (deprotonation, protonation and cationisation by alkali metal cations) of carboxylated PEGs was compared with that of non-carboxylated correspondents by using both secondary ion mass spectrometry (SIMS) and electrospray ionisation (ESI). The fragmentation of the PEGCs and CPEGCs is discussed and also compared with their neutral correspondents, PEGs. The B/E mass spectra were recorded, using secondary ion mass spectrometry as a method for generation, for deprotonated and protonated molecules and molecules cationised by alkali metal cations. The fragmentation behaviour of PEGs is found to be different from that of CPEGCs, The presence of carboxylic groups may be confirmed not only by the determination of molecular weights of the ethoxylates studied, but also on the basis of the fragment ions formed. The metastable decomposition of the [OPEC-H](-) ions proceed through the cleavage of the bond between the octylphenol moiety and the ethoxylene chain leading to the octylphenoxy anions. It permits determination of the mass of the hydrophobic moiety of the studied carboxylated alkylphenol ethoxylate. ESI mass spectra recorded in the negative ion mode were found to be more suitable for the determination of the average molecular weight of carboxylated ethoxylates than SI mass spectra. PMID:12939494

  8. Crystal structure of dimethyl 4,4'-di-meth-oxy-biphenyl-3,3'-di-carboxyl-ate.

    PubMed

    Lundvall, Fredrik; Dietzel, Pascal D C; Fjellvåg, Helmer

    2016-03-01

    In the title compound, C18H18O6, the benzene rings are coplanar due to the centrosymmetric nature of the mol-ecule, with an inversion centre located at the midpoint of the C-C bond between the two rings. Consequently, the methyl carboxyl-ate substituents are oriented in a trans fashion with regards to the bond between the benzene rings. The methyl carboxyl-ate and meth-oxy substituents are rotated slightly out of plane relative to their parent benzene rings, with dihedral and torsion angles of 18.52 (8) and -5.22 (15)°, respectively. The shortest O⋯H contact between neighbouring mol-ecules is about 2.5 Å. Although some structure-directing contributions from C-H⋯O hydrogen-bonding inter-actions are possible, the crystal packing seems primarily directed by weak van der Waals forces. PMID:27006799

  9. Substituent effects on hydrogen bonding of aromatic amide-carboxylate.

    PubMed

    Sen, Ibrahim; Kara, Hulya; Azizoglu, Akın

    2016-10-01

    N-(p-benzoyl)-anthranilic acid (BAA) derivatives have been synthesized with different substituents (X: Br, Cl, OCH3, CH3), and their crystal structures have been analyzed in order to understand the variations in their molecular geometries with respect to the substituents by using (1)H NMR, (13)C NMR, IR and X-ray single-crystal diffraction. The carboxylic acid group forms classic OH⋯O hydrogen bonded dimers in a centrosymmetric R2(2)(8) ring motifs for BAA-Br and BAA-Cl. However, no carboxylic acid group forms classic OH⋯O hydrogen bonded dimers in BAA-OCH3 and BAA-CH3. The asymmetric unit consists of two crystallographically independent molecules in BAA-OCH3. DFT computations show that the interaction energies between monomer and dimer are in the range of 0.5-3.8kcal/mol with the B3LYP/6-31+G*, B3LYP/6-31++G*, B3LYP/6-31++G**, and B3LYP/AUG-cc-pVDZ levels of theory. The presence of different hydrogen bond patterns is also governed by the substrate. For monomeric compounds studied herein, theoretical calculations lead to two low-energy conformers; trans (a) and cis (b). Former one is more stable than latter by about 4kcal/mol. PMID:27239947

  10. A new carboxyl-copper-organic framework and its excellent selective absorbability for proteins

    SciTech Connect

    Yang, Linyan; Xin, Liangliang; Gu, Wen; Tian, Jinlei; Liao, Shengyun; Du, Peiyao; Tong, Yuzhang; Zhang, Yanping; Lv, Rui; Wang, Jingyao; Liu, Xin

    2014-10-15

    One-pot solvothermal treatments of CuCl{sub 2}·2H{sub 2}O, H{sub 2}L (5-(3-methyl-5-(pyridin-4-yl)-4H-1,2,4-triazol-4-yl) isophthalic acid) and Sm(NO{sub 3}){sub 3}·6H{sub 2}O in water yielded a rare carboxyl-copper-organic framework, [Cu(HL)]{sub n}·nH{sub 2}O (1). The existence of carboxyl groups in compound 1 may be due to the interference of Sm(NO{sub 3}){sub 3}·6H{sub 2}O at the relatively high temperature and autogenous pressure of the reaction. Compound 1 has been characterized by single-crystal X-ray diffraction, PXRD, IR, and elemental analysis. Compound 1 is a 3D coordination polymer, and an xfe-4-Fddd, (4{sup 2}.6.8{sup 3}) topology in 1 is created. In addition, the optical properties have been investigated. Rhodamine B dyeing experiments exhibited that there were residual carboxyl groups on the surface of compound 1. UV–vis results showed that more lysozyme was adsorbed onto the surface of compound 1 than BSA at pH 7.4. At the same time, XPS spectra were also investigated to verify the results. - Graphical abstract: One-pot solvothermal treatments of CuCl{sub 2}·2H{sub 2}O, H2L (5-(3-methyl-5-(pyridin-4-yl)-4H-1, 2, 4-triazol-4-yl) isophthalic acid) and Sm(NO{sub 3}){sub 3}·6H{sub 2}O in water yielded a rare carboxyl-copper-organic framework, [Cu(HL)]n·nH{sub 2}O (1). The existence of carboxyl groups in compound 1 may be due to the interference of Sm(NO{sub 3}){sub 3}·6H{sub 2}O at the relatively high temperature and autogenous pressure of the reaction. Compound 1 has been characterized by single-crystal X-ray diffraction, XRPD, IR, and elemental analysis. Compound 1 is a 3D coordination polymer, and an xfe-4-Fddd, (4{sup 2}.6.8{sup 3}) topology in 1 is created. In addition, the optical properties have been investigated. Rhodamine B dyeing experiments exhibited that there were residual carboxyl groups on the surface of compound 1. UV-vis results showed that more lysozyme was adsorbed onto the surface of compound 1 than that of BSA at pH 7

  11. Nitric Acid Dehydration Using Perfluoro Carboxylate and Mixed Sulfonate/Carboxylate Membranes

    SciTech Connect

    R.L. Ames

    2004-09-01

    Perfluoro ionomer membranes are tetrafluoro ethylene-based materials with microheterogeneous structures consisting of a hydrophobic polymer backbone and a hydrophilic side-chain cluster region. Due to the ionomer cluster morphology, these films exhibit unique transport properties. Recent investigations with perfluoro sulfonate and perfluoro sulfonate/carboxylate composite polymers have demonstrated their value in the dehydration of nitric acid and they show potential as an alternative to conventional, energy intensive unit operations in the concentration of acid feeds. As a result, investigations were conducted to determine the feasibility of using pure perfluoro carboxylate and mixed perfluoro sulfonate/carboxylate films for the dehydration of nitric acid because of the speculation of improved water selectivity of the carboxylate pendant chain. During the first phase of these investigations the effort was focused on generating a thin, solution cast perfluoro carboxylate ionomer film, to evaluate the general, chemical and physical characteristics of the polymer, and to assess the material's aqueous transport performance (flux and nitrate separation efficiencies) in pervaporation and high-pressure environments. Results demonstrated that generating robust solution-cast films was difficult yet a number of membranes survived high trans-membrane pressures up to 700 psig. General characterization of the solution cast product showed reduced ion exchange capacities when compared with thicker, ''as received'' perfluoro carboxylate and similar sulfonate films. Small angle x-ray scattering analysis results suggested that the solution cast carboxylate films contained a small fraction of sulfonate terminated side-chains. Aqueous transport experimentation showed that permeate fluxes for both pure water and nitric acid were approximately two orders of magnitude smaller for the carboxylate solution cast membranes when compared to their sulfonate counterparts of similar thickness

  12. Cloud Forming Potential of Aminium Carboxylate Aerosols

    NASA Astrophysics Data System (ADS)

    Gomez Hernandez, M. E.; McKeown, M.; Taylor, N.; Collins, D. R.; Lavi, A.; Rudich, Y.; Zhang, R.

    2014-12-01

    Atmospheric aerosols affect visibility, air quality, human health, climate, and in particular the aerosol direct and indirect forcings represent the largest uncertainty in climate projections. In this paper, we present laboratory measurements of the hygroscopic growth factors (HGf) and cloud condensation nuclei (CCN) activity of a series of aminium carboxylate salt aerosols, utilizing a Hygroscopicity Tandem Differential Mobility Analyzer (HTDMA) coupled to a Condensation Particle Counter (CPC) and a CCN counter. HGf measurements were conducted for size-selected aerosols with diameters ranging from 46 nm to 151 nm and at relative humidity (RH%) values ranging from 10 to 90%. In addition, we have calculated the CCN activation diameters for the aminium carboxylate aerosols and derived the hygroscopicity parameter (k or kappa) values for all species using three methods, i.e., the mixing rule approximation, HGf, and CCN results. Our results show that variations in the ratio of acid to base directly affect the activation diameter, HGf, and (k) values of the aminium carboxylate aerosols. Atmospheric implications of the variations in the chemical composition of aminium carboxylate aerosols on their cloud forming potential will be discussed.

  13. The Conversion of Carboxylic Acids to Ketones: A Repeated Discovery

    ERIC Educational Resources Information Center

    Nicholson, John W.; Wilson, Alan D.

    2004-01-01

    The conversion of carboxylic acids to ketones is a useful chemical transformation with a long history. Several chemists have claimed that they discovered the conversion of carboxylic acids to ketones yet in fact the reaction is actually known for centuries.

  14. Tetratopic phenyl compounds, related metal-organic framework materials and post-assembly elaboration

    DOEpatents

    Farha, Omar K; Hupp, Joseph T

    2013-06-25

    Disclosed are tetratopic carboxylic acid phenyl for use in metal-organic framework compounds. These compounds are useful in catalysis, gas storage, sensing, biological imaging, drug delivery and gas adsorption separation.

  15. Tetratopic phenyl compounds, related metal-organic framework materials and post-assembly elaboration

    DOEpatents

    Farha, Omar K.; Hupp, Joseph T.

    2012-09-11

    Disclosed are tetratopic carboxylic acid phenyl for use in metal-organic framework compounds. These compounds are useful in catalysis, gas storage, sensing, biological imaging, drug delivery and gas adsorption separation.

  16. SPECTROSCOPIC STUDY OF SORPTION OF NITROGEN HETEROCYCLIC COMPOUNDS ON PHYLLOSILICATES

    EPA Science Inventory

    The present study focused on understanding the sorption characteristics of acridine (AcN)and acridine-9-carboxylic acid (AcNCOOH), two typical nitrogen heterocyclic compounds (NHCs), on well-characterized phyllosilicates (hectorite, saponite, and muscovite). Results presented in...

  17. Cationic mononuclear ruthenium carboxylates as catalyst prototypes for self-induced hydrogenation of carboxylic acids

    PubMed Central

    Naruto, Masayuki; Saito, Susumu

    2015-01-01

    Carboxylic acids are ubiquitous in bio-renewable and petrochemical sources of carbon. Hydrogenation of carboxylic acids to yield alcohols produces water as the only byproduct, and thus represents a possible next generation, sustainable method for the production of these alternative energy carriers/platform chemicals on a large scale. Reported herein are molecular insights into cationic mononuclear ruthenium carboxylates ([Ru(OCOR)]+) as prototypical catalysts for the hydrogenation of carboxylic acids. The substrate-derived coordinated carboxylate was found to function initially as a proton acceptor for the heterolytic cleavage of dihydrogen, and subsequently also as an acceptor for the hydride from [Ru–H]+, which was generated in the first step (self-induced catalysis). The hydrogenation proceeded selectively and at high levels of functional group tolerance, a feature that is challenging to achieve with existing heterogeneous/homogeneous catalyst systems. These fundamental insights are expected to significantly benefit the future development of metal carboxylate-catalysed hydrogenation processes of bio-renewable resources. PMID:26314266

  18. Biocatalytic amidation of carboxylic acids and their antinemic activity.

    PubMed

    Bose, Abinesh; Shakil, Najam Akhtar; Pankaj; Kumar, Jitendra; Singh, Manish K

    2010-04-01

    A series of novel N-alkyl substituted amides, synthesized by enzyme catalysis, were evaluated against root-knot nematode, Meloidogyne incognita and found to have potential antinemic activity. The corresponding amides were prepared by the condensation of equimolar amounts of carboxylic acids with different alkyl amines in the presence of Candida antarctica lipase at 60-90 degrees C in 16-20 h. The reactions were carried out in a non - solvent system without the use of any activating agents. All the products were obtained in appreciable amounts and the yields for different compounds varied between 77.4-82.3%. The synthesized compounds were characterized using spectroscopy techniques namely Infra Red (IR) and Nuclear Magnetic Resonance (NMR) ((1)H and (13)C). Nematicidal activity of synthesized amides was evaluated against J(2)s of Meloidogyne incognita at 500, 250, 125 and 62.5 ppm concentrations after 24 h, 48 h and 72 h of exposure. Among all the tested compounds, N-propyl-butyramide, N-propyl-pentanamide and N-propyl-hexanamide were found to possess significant activity with LC(50) values of 67.46, 83.49 and 96.53 respectively. N-propyl-butyramide with LC(50) value of 67.46 ppm was found to be most active amide against J(2)s of Meloidogyne incognita. The bioactivity study showed that an increase in alkyl chain significantly decreased the activity of amides against root-knot nematode. PMID:20390959

  19. Production of carboxylic acid and salt co-products

    DOEpatents

    Hanchar, Robert J.; Kleff, Susanne; Guettler, Michael V.

    2014-09-09

    This invention provide processes for producing carboxylic acid product, along with useful salts. The carboxylic acid product that is produced according to this invention is preferably a C.sub.2-C.sub.12 carboxylic acid. Among the salts produced in the process of the invention are ammonium salts.

  20. 21 CFR 177.1600 - Polyethylene resins, carboxyl modified.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Polyethylene resins, carboxyl modified. 177.1600... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1600 Polyethylene resins, carboxyl modified. Carboxyl-modified polyethylene resins may be safely used as the food-contact surface...

  1. 21 CFR 177.1600 - Polyethylene resins, carboxyl modified.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Polyethylene resins, carboxyl modified. 177.1600... Use Food Contact Surfaces § 177.1600 Polyethylene resins, carboxyl modified. Carboxyl-modified polyethylene resins may be safely used as the food-contact surface of articles intended for use in contact...

  2. 21 CFR 177.1600 - Polyethylene resins, carboxyl modified.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Polyethylene resins, carboxyl modified. 177.1600... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1600 Polyethylene resins, carboxyl modified. Carboxyl-modified polyethylene resins may be safely used as the food-contact surface...

  3. 21 CFR 177.1600 - Polyethylene resins, carboxyl modified.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Polyethylene resins, carboxyl modified. 177.1600... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1600 Polyethylene resins, carboxyl modified. Carboxyl-modified polyethylene resins may be safely used as the food-contact surface...

  4. 21 CFR 177.1600 - Polyethylene resins, carboxyl modified.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Polyethylene resins, carboxyl modified. 177.1600... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1600 Polyethylene resins, carboxyl modified. Carboxyl-modified polyethylene resins may be safely used as the food-contact surface...

  5. 40 CFR 721.2950 - Carboxylic acid glycidyl esters.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Carboxylic acid glycidyl esters. 721... Substances § 721.2950 Carboxylic acid glycidyl esters. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified generically as carboxylic acid glycidyl...

  6. 40 CFR 721.2950 - Carboxylic acid glycidyl esters.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Carboxylic acid glycidyl esters. 721... Substances § 721.2950 Carboxylic acid glycidyl esters. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified generically as carboxylic acid glycidyl...

  7. 40 CFR 721.2950 - Carboxylic acid glycidyl esters.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Carboxylic acid glycidyl esters. 721... Substances § 721.2950 Carboxylic acid glycidyl esters. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified generically as carboxylic acid glycidyl...

  8. 40 CFR 721.2093 - Alkenyl carboxylate, metal salt (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Alkenyl carboxylate, metal salt... Specific Chemical Substances § 721.2093 Alkenyl carboxylate, metal salt (generic). (a) Chemical substance... alkenyl carboxylate, metal salt (PMN P-99-0848) is subject to reporting under this section for...

  9. 40 CFR 721.2093 - Alkenyl carboxylate, metal salt (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alkenyl carboxylate, metal salt... Specific Chemical Substances § 721.2093 Alkenyl carboxylate, metal salt (generic). (a) Chemical substance... alkenyl carboxylate, metal salt (PMN P-99-0848) is subject to reporting under this section for...

  10. 40 CFR 721.2093 - Alkenyl carboxylate, metal salt (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Alkenyl carboxylate, metal salt... Specific Chemical Substances § 721.2093 Alkenyl carboxylate, metal salt (generic). (a) Chemical substance... alkenyl carboxylate, metal salt (PMN P-99-0848) is subject to reporting under this section for...

  11. 40 CFR 721.2093 - Alkenyl carboxylate, metal salt (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alkenyl carboxylate, metal salt... Specific Chemical Substances § 721.2093 Alkenyl carboxylate, metal salt (generic). (a) Chemical substance... alkenyl carboxylate, metal salt (PMN P-99-0848) is subject to reporting under this section for...

  12. 40 CFR 721.2950 - Carboxylic acid glycidyl esters.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Carboxylic acid glycidyl esters. 721... Substances § 721.2950 Carboxylic acid glycidyl esters. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified generically as carboxylic acid glycidyl...

  13. Water chemical ionization mass spectrometry of aldehydes, ketones esters, and carboxylic acids

    SciTech Connect

    Hawthorne, S.B.; Miller, D.J.

    1986-11-01

    Chemical ionization mass spectrometry (CI) of aliphatic and aromatic carbonyl compounds using water as the reagent gas provides intense pseudomolecular ions and class-specific fragmentation patterns that can be used to identify aliphatic aldehydes, ketones, carboxylic acids, and esters. The length of ester acyl and alkyl groups can easily be determined on the basis of loss of alcohols from the protonated parent. Water CI provides for an approximately 200:1 selectivity of carbonyl species over alkanes. No reagent ions are detected above 55 amu, allowing species as small as acetone, propanal, acetic acid, and methyl formate to be identified. When deuterate water was used as the reagent, only the carboxylic acids and ..beta..-diketones showed significant H/D exchange. The use of water CI to identify carbonyl compounds in a wastewater from the supercritical water extraction of lignite coal, in lemon oil, and in whiskey volatiles is discussed.

  14. Vibrational spectroscopic and molecular docking study of 4-Methylphenylquinoline-2-carboxylate

    NASA Astrophysics Data System (ADS)

    Fazal, E.; Panicker, C. Yohannan; Varghese, Hema Tresa; Nagarajan, S.; Sudha, B. S.; War, Javeed Ahamad; Srivastava, S. K.; Harikumar, B.; Anto, P. L.

    2015-05-01

    FT-IR and FT-Raman spectra of 4-Methylphenylquinoline-2-carboxylate were recorded and analyzed. The structure of the molecule has been optimized and structural characteristics have been determined by density functional theory. The geometrical parameters (DFT) are in agreement with the XRD results. HOMO and LUMO and other chemical properties are reported. Nonlinear optical properties are also reported. A detailed molecular picture of the title compound and its interactions were obtained from NBO analysis. The negative (red and yellow) regions of the MEP are related to electrophilic reactivity and the positive (blue) regions to nucleophilic reactivity, as shown in the MEP plot and the carbonyl group and the phenyl rings are observed as electrophilic. PASS analysis predicts that the 4-Methylphenylquinoline-2-carboxylate might exhibit anti-diabetic activity. Molecular docking results suggest that the compound might exhibit inhibitory activity against GPb.

  15. High lipophilicity of perfluoroalkyl carboxylate and sulfonate: implications for their membrane permeability.

    PubMed

    Jing, Ping; Rodgers, Patrick J; Amemiya, Shigeru

    2009-02-18

    Here we report on remarkably high lipophilicity of perfluoroalkyl carboxylate and sulfonate. A lipophilic nature of this emerging class of organic pollutants has been hypothesized as an origin of their bioaccumulation and toxicity. Both carboxylate and sulfonate, however, are considered hydrophilic while perfluroalkyl groups are not only hydrophobic but also oleophobic. Partition coefficients of a homologous series of perfluoroalkyl and alkyl carboxylates between water and n-octanol were determined as a measure of their lipophilicity by ion-transfer cyclic voltammetry. Very similar lipophilicity of perfluoroalkyl and alkyl chains with the same length is demonstrated experimentally for the first time by fragment analysis of the partition coefficients. This finding is important for pharmaceutical and biomedical applications of perfluoroalkyl compounds. Interestingly, approximately 2 orders of magnitude higher lipophilicity of a perfluoroalkyl carboxylate or sulfonate in comparison to its alkyl counterpart is ascribed nearly exclusively to their oxoanion groups. The higher lipophilicity originates from a strong electron-withdrawing effect of the perfluoroalkyl group on the adjacent oxoanion group, which is weakly hydrated to decrease its hydrophilicity. In fact, the inductive effect is dramatically reduced for a fluorotelomer with an ethylene spacer between perfluorohexyl and carboxylate groups, which is only as lipophilic as its alkyl counterpart, nonanoate, and is 400 times less lipophilic than perfluorononanoate. The high lipophilicity of perfluoroalkyl carboxylate and sulfonate implies that their permeation across such a thin lipophilic membrane as a bilayer lipid membrane is limited by their transfer at a membrane/water interface. The limiting permeability is lower and less dependent on their lipophilicity than the permeability controlled by their diffusion in the membrane interior as assumed in the classical solubility-diffusion model. PMID:19170492

  16. Boron-Catalyzed N-Alkylation of Amines using Carboxylic Acids.

    PubMed

    Fu, Ming-Chen; Shang, Rui; Cheng, Wan-Min; Fu, Yao

    2015-07-27

    A boron-based catalyst was found to catalyze the straightforward alkylation of amines with readily available carboxylic acids in the presence of silane as the reducing agent. Various types of primary and secondary amines can be smoothly alkylated with good selectivity and good functional-group compatibility. This metal-free amine alkylation was successfully applied to the synthesis of three commercial medicinal compounds, Butenafine, Cinacalcet. and Piribedil, in a one-pot manner without using any metal catalysts. PMID:26150397

  17. 3-(4-Meth-oxy-phen-yl)-5-methylisoxazole-4-carb-oxy-lic acid.

    PubMed

    Chandra; Raghu, K; Srikantamurthy, N; Umesha, K B; Palani, K; Mahendra, M

    2013-03-01

    In the title compound, C12H11NO4, the dihedral angle between the benzene and isoxazole rings is 42.52 (8)°. The carb-oxy-lic acid group is close to being coplanar with the isoxazole ring [dihedral angle = 5.3 (2)°]. In the crystal, inversion dimers linked by pairs of O-H⋯O hydrogen bonds generate R2(2)(8) loops. PMID:23476573

  18. KI-catalyzed α-acyloxylation of acetone with carboxylic acids.

    PubMed

    Wu, Ya-Dong; Huang, Bei; Zhang, Yue-Xin; Wang, Xiao-Xu; Dai, Jian-Jun; Xu, Jun; Xu, Hua-Jian

    2016-07-01

    The KI-catalyzed reaction of acetone with aromatic carboxylic acids is achieved, leading to α-acyloxycarbonyl compounds in good to excellent yields under mild reaction conditions. The present method exhibits good functional-group compatibility. Notably, this reaction system is even suitable for cinnamic acid, 3-phenylpropiolic acid and 4-phenylbutanoic acid. A kinetic isotope effect (KIE) study indicates that C-H cleavage of the acetone is the rate-limiting step in the catalytic cycle. PMID:27251323

  19. Copper-Catalyzed Carboxylation of Alkenylzirconocenes with Carbon Dioxide Leading to α,β-Unsaturated Carboxylic Acids.

    PubMed

    Wang, Sheng; Shao, Peng; Chen, Chao; Xi, Chanjuan

    2015-10-16

    A variety of alkenylzirconocenes were efficiently carboxylated by CO2 utilizing the (IMes)CuCl catalyst yielding the corresponding α,β-unsaturated carboxylic acids in good yields. This reaction could be carried out in a one-pot operation via sequential carbozirconation of alkynes and carboxylation using CO2 as starting materials under room temperature. PMID:26406296

  20. Pyrolysis Mechanisms of Aromatic Carboxylic Acids

    SciTech Connect

    Britt, P.F.; Eskay, T.P.; Buchanan, A.C. III

    1997-12-31

    Although decarboxylation of carboxylic acids is widely used in organic synthesis, there is limited mechanistic information on the uncatalyzed reaction pathways of aromatic carboxylic acids at 300-400 {degrees} C. The pyrolysis mechanisms of 1,2-(3,3-dicarboxyphenyl)ethane, 1,2-(4,4-dicarboxylphenyl)ethane, 1-(3-carboxyphenyl)-2-(4- biphenyl)ethane, and substituted benzoic acids have been investigated at 325-425 {degrees} C neat and diluted in an inert solvent. Decarboxylation is the dominant pyrolysis path. Arrhenius parameters, substituent effects, and deuterium isotope effects are consistent with decarboxylation by an electrophilic aromatic substitution reaction. Pyrolysis of benzoic acid in naphthalene, as a solvent, produces significant amounts of 1- and 2-phenylnaphthalenes. The mechanistic pathways for decarboxylation and arylation with be presented.

  1. Design, synthesis and antiproliferative activity of a novel class of indole-2-carboxylate derivatives.

    PubMed

    Ji, Xing-yue; Xue, Si-tu; Zhan, Yue-chen; Shen, Jia-jia; Wu, Lin-tao; Jin, Jie; Wang, Zhen; Li, Zhuo-rong

    2014-08-18

    Based on the chemical structure of Pyrroloquinoline quinone (PQQ), a novel class of indole-2-carboxylate derivatives was designed, synthesized and assayed for antiproliferative activity in cancer cells in vitro. The biological results showed that some derivatives exhibited significant antiproliferative activity against HepG2, A549 and MCF7 cells. Notably, the novel compounds, methyl 6-amino-4-cyclohexylmethoxy-1H-indole-2-carboxylate (6e) and methyl 4-isopropoxy-6-methoxy-1H-indole-2-carboxylate (9l) exhibited more potent antiproliferative activity than the reference drugs PQQ and etoposide in vitro, with IC50 values ranging from 3.78 ± 0.58 to 24.08 ± 1.76 μM. Further biological assay showed that both compounds 6e and 9l increased ROS generation dose-dependently, and induced PARP cleavage in A549 cells. Consequently, 6e and 9l appeared as promising anticancer lead compounds for further optimization. PMID:24996136

  2. Novel amine-based presursor compounds and composite membranes thereof

    DOEpatents

    Lee, Eric K. L.; Tuttle, Mark E.

    1989-01-01

    Novel amine-based precursor compounds comprising the condensation products of dialkylenetriamine and alpha, beta-unsaturated acid halides are disclosed, as well as composite membranes containing such compounds, the membranes being useful in RO-type processes for desalination and the removal of low molecular weight organic compounds such as phenols and carboxylic acids.

  3. EFFECTS OF CARBOXYLIC ACIDS ON LIQUID-PHASE ADSORPTION OF ETHANOL AND WATER BY HIGH-SILICA ZSM-5

    EPA Science Inventory

    Adsorption isotherms were measured for each compound adsorbed on commercially available ZSM-5 (Si/Al = 140) powder from binary and ternary liquid mixtures of ethanol, carboxylic acids, and water at room temperature. The amounts adsorbed were measured using a recently developed t...

  4. Carboxyl terminal deletion analysis of tryptophan hydroxylase.

    PubMed

    Mockus, S M; Kumer, S C; Vrana, K E

    1997-10-17

    Tryptophan hydroxylase (TPH) catalyzes the rate-limiting step in the synthesis of serotonin and participates (in a non-rate-limiting fashion) in melatonin biosynthesis. In rabbit, TPH exists as a tetramer of four identical 51007 dalton (444 amino acids) protein subunits. An intersubunit binding domain responsible for tetramer formation of TPH was identified by assessing the role of a carboxyl terminal leucine heptad and 4-3 hydrophobic repeat. These repeats are conserved in all of the aromatic amino acid hydroxylases and have been shown to be required for the assembly of tyrosine hydroxylase tetramers. Polymerase chain reaction was utilized to create three TPH carboxyl terminal deletions (C delta8, C delta12 and C delta17) that sequentially remove members of the leucine heptad and 4-3 hydrophobic repeat. Each deletion and full-length recombinant TPH was expressed in bacteria to obtain soluble enzyme extracts for subsequent activity and structural analysis. It was found that removal of 8, 12 or 17 amino acids from the carboxyl terminus of TPH did not significantly alter enzymatic activity when compared to full-length recombinant TPH. However, the macromolecular structure of the deletions was dramatically affected as determined by dimeric and monomeric profiles on size exclusion chromatography. It can be concluded that amino acids 428-444 (the C-terminal 17 amino acids) comprise an intersubunit binding domain that is required for tetramer formation of TPH, but that tetramer assembly is not essential for full enzymatic activity. PMID:9392522

  5. Conjugation of Methotrexate-Amino Derivatives to Macromolecules through Carboxylate Moieties Is Superior Over Conventional Linkage to Amino Residues: Chemical, Cell-Free and In Vitro Characterizations

    PubMed Central

    Cooper, Itzik; Fridkin, Mati; Shechter, Yoram

    2016-01-01

    In this study, we examined the possibility of introducing methotrexate (MTX) to the carboxylate rather than to the ε-amino side chains of proteins. We found that MTX—amino compounds covalently linked to the carboxylate moieties of macromolecules, undergo unusual peptide-bond cleavage, with the release of the MTX amino derivatives from the conjugates. This event takes place at an accelerated rate under acidic conditions, and at a slower rate at physiological pH values. The glutamate portion of MTX is responsible for this behavior, with little or no contribution of the p-aminobenzoate-pteridine ring that is linked to the α-amino side chain of the glutamate. Carboxylate-linked Fmoc-Glu-γ-CONH-(CH2)6-NH2 undergoes hydrolysis in a nearly indistinguishable fashion. A free α carboxylate moiety is essential for this effect. Carboxylate linked Fmoc-glutamic-amide-γ-CONH-(CH2)6-NH2 undergoes no hydrolysis under acidic conditions. Based on these findings, we engineered a cysteine specific MTX containing reagent. Its linkage to bovine serum albumin (BSA) yielded a conjugate with profound antiproliferative efficacy in a MTX-sensitive glioma cell line. In conclusion, carboxylate linked MTX-amino derivatives in particular, and carboxylate linked R-α-GLU-γ amino compounds in general are equipped with‘built-in chemical machinery’ that releases them under mild acidic conditions. PMID:27403959

  6. Snythesis and characterization of the first main group oxo-centered trinuclear carboxylate

    NASA Technical Reports Server (NTRS)

    Duraj, Stan A.

    1994-01-01

    The synthesis and structural characterization of the first main group oxo-centered, trinuclear carboxylato-bridged species is reported, namely (Ga3(mu(sub 3)-O) (mu-O2CC6H5)6 (4-Mepy)3) GaCl4 center dot 4-Mepy (compound 1), where 4-Mepy is 4-methylpyridine. Compound 1 is a main group example of a well-established class of complexes, referred to as 'basic carboxylates' of the general formula (M3(mu(sub 3)-O)(mu-O2CR)6L3)(+), previously observed only for transition metals.

  7. Carboxylates and sulfated carboxylates as inhibitors of steel corrosion in neutral media

    SciTech Connect

    Podobaev, N.I.; Larionov, E.A.

    1995-03-01

    Effects of carboxylates and sulfocarboxylates as well as their mixtures with o-nitrobenzoate on the corrosion of St3 steel in freely aerated distilled water and 0.01 - 0.04 M NaCl solutions (pH 7) are studied electrochemically and by the gravimetric technique. A noticeable improvement of the protective properties of sulfated mustard soap and sulfated castor oil is observed after the addition of 20 mg/l o-nitrobenzoate. Armco iron spontaneously passivates in 0.25 M CH{sub 3}COONa solution at a certain content of inhibitors and under a hydrodynamical regime. Sulfated carboxylates suppress the anodic process more strongly than do nonsulfated carboxylates.

  8. Synthesis, structural characterization and antimicrobial activities of diorganotin(IV) complexes with azo-imino carboxylic acid ligand: Crystal structure and topological study of a doubly phenoxide-bridged dimeric dimethyltin(IV) complex appended with free carboxylic acid groups

    NASA Astrophysics Data System (ADS)

    Roy, Manojit; Roy, Subhadip; Devi, N. Manglembi; Singh, Ch. Brajakishor; Singh, Keisham Surjit

    2016-09-01

    Diorganotin(IV) complexes appended with free carboxylic acids were synthesized by reacting diorganotin(IV) dichlorides [R2SnCl2; R = Me (1), Bu (2) and Ph (3)] with an azo-imino carboxylic acid ligand i.e. 2-{4-hydroxy-3-[(2-hydroxyphenylimino)methyl]phenylazo}benzoic acid in presence of triethylamine. The complexes were characterized by elemental analysis, IR and multinuclear NMR (1H, 13C and 119Sn) spectroscopy. The structure of 1 in solid state has been determined by X-ray crystallography. Crystal structure of 1 reveals that the compound crystallizes in monoclinic space group P21/c and is a dimeric dimethyltin(IV) complex appended with free carboxylic acid groups. In the structure of 1, the Sn(IV) atoms are hexacoordinated and have a distorted octahedral coordination geometry in which two phenoxy oxygen atoms and the azomethine nitrogen atom of the ligand coordinate to each tin atom. One of the phenoxy oxygen atom bridges the two tin centers resulting in a planar Sn2O2 core. Topological analysis is used for the description of molecular packing in 1. Tin NMR spectroscopy study indicates that the complexes have five coordinate geometry around tin atom in solution state. Since the complexes have free carboxylic acids, these compounds could be further used as potential metallo-ligands for the synthesis of other complexes. The synthesized diorganotin(IV) complexes were also screened for their antimicrobial activities and compound 2 showed effective antimicrobial activities.

  9. Poly[μ6-(naphthalene-2,6-di­carboxyl­ato)-bis­(aqua­lithium)

    PubMed Central

    Fédèle, Lionel; Sauvage, Frédéric; Becuwe, Matthieu; Chotard, Jean-Noël

    2014-01-01

    The title compound, [Li2(C12H6O4)(H2O)2]n, crystallizes with one half of the molecular entities in the asymmetric unit. The second half is gererated by inversion symmetry. The crystal structure has a layered arrangement built from distorted edge-sharing LiO3(OH)2 tetra­hedra parallel to (100), with naphthalenedi­carboxyl­ate bridging the LiO3(OH)2 layers along the [100] direction. Hydrogen bonding between the water molecule and adjacent carboxylate groups consolidates the packing. PMID:25249875

  10. Gas-Phase Partial Oxidation of Lignin to Carboxylic Acids over Vanadium Pyrophosphate and Aluminum-Vanadium-Molybdenum.

    PubMed

    Lotfi, Samira; Boffito, Daria C; Patience, Gregory S

    2015-10-26

    Lignin is a complex polymer that is a potential feedstock for aromatic compounds and carboxylic acids by cleaving the β-O-4 and 5-5' linkages. In this work, a syringe pump atomizes an alkaline solution of lignin into a catalytic fluidized bed operating above 600 K. The vanadium heterogeneous catalysts convert all the lignin into carboxylic acids (up to 25 % selectivity), coke, carbon oxides, and hydrogen. Aluminum-vanadium-molybdenum mostly produced lactic acid (together with formic acid, acrylic acid, and maleic anhydride), whereas the vanadium pyrophosphate catalyst produced more maleic anhydride. PMID:26361086

  11. (±)-trans-3-Benzoyl­bicyclo­[2.2.2]octane-2-carboxylic acid

    PubMed Central

    Lalancette, Roger A.; Thompson, Hugh W.; Brunskill, Andrew P. J.

    2008-01-01

    The title keto acid, C16H18O3, displays significant twisting of all three ethyl­ene bridges in its bicyclo­[2.2.2]octane structure owing to steric inter­actions; the bridgehead-to-bridgehead torsion angles are 13.14 (12), 13.14 (13) and 9.37 (13)°. The compound crystallizes as centrosymmetric carboxyl dimers [O⋯O = 2.6513 (12) Å and O—H⋯O = 178°], which have two orientations within the cell and contain no significant carboxyl disorder. PMID:21201657

  12. Enzymes involved in a novel anaerobic cyclohexane carboxylic acid degradation pathway.

    PubMed

    Kung, Johannes W; Meier, Anne-Katrin; Mergelsberg, Mario; Boll, Matthias

    2014-10-01

    The anaerobic degradation of cyclohexane carboxylic acid (CHC) has so far been studied only in Rhodopseudomonas palustris, in which CHC is activated to cyclohexanoyl coenzyme A (cyclohexanoyl-CoA [CHCoA]) and then dehydrogenated to cyclohex-1-ene-1-carboxyl-CoA (CHeneCoA). This intermediate is further degraded by reactions of the R. palustris-specific benzoyl-CoA degradation pathway of aromatic compounds. However, CHeneCoA is not an intermediate in the degradation of aromatic compounds in all other known anaerobic bacteria; consequently, degradation of CHC was mostly unknown in anaerobic bacteria. We identified a previously unknown CHC degradation pathway in the Fe(III)-reducing Geobacter metallireducens by determining the following CHC-induced in vitro activities: (i) the activation of CHC to CHCoA by a succinyl-CoA:CHC CoA transferase, (ii) the 1,2-dehydrogenation of CHCoA to CHeneCoA by CHCoA dehydrogenase, and (iii) the unusual 1,4-dehydrogenation of CHeneCoA to cyclohex-1,5-diene-1-carboxyl-CoA. This last represents a previously unknown joint intermediate of the CHC and aromatic compound degradation pathway in bacteria other than R. palustris. The enzymes catalyzing the three reactions were purified and characterized as specific enzymes after heterologous expression of the encoding genes. Quantitative reverse transcription-PCR revealed that expression of these genes was highly induced during growth with CHC but not with benzoate. The newly identified CHC degradation pathway is suggested to be present in nearly all CHC-degrading anaerobic bacteria, including denitrifying, Fe(III)-reducing, sulfate-reducing, and fermenting bacteria. Remarkably, all three CHC degradation pathways always link CHC catabolism to the catabolic pathways of aromatic compounds. We propose that the capacity to use CHC as a carbon source evolved from already-existing aromatic compound degradation pathways. PMID:25112478

  13. Carboxylic Acid Esters as Substrates of Cholinesterases

    NASA Astrophysics Data System (ADS)

    Brestkin, A. P.; Rozengart, E. V.; Abduvakhabov, A. A.; Sadykov, A. A.

    1983-10-01

    Data on the kinetics of the hydrolysis of various carboxylic acid esters by two main types of cholinesterases — acetylcholinesterase from human erythrocytes and butyrylcholinesterase from horse blood serum — are surveyed. It is shown that the rate of enzyme hydrolysis depends significantly on the structure of the acyl part of the ester molecule, the nature of the ester heteroatom, the structure of the alcohol component, and particularly the structure of the onium group. Esters based on natural products are of special interest as specific substrates of these enzymes. The role of the productive and non-productive sorption of the substrates in enzyme catalysis is demonstrated. The bibliography includes 81 references.

  14. Conformation of carboxylated schizophyllan in aqueous solution.

    PubMed

    Yoshiba, Kazuto; Sato, Takahiro; Osumi, Takaaki; Ulset, Ann-Sissel T; Christensen, Bjørn E

    2015-12-10

    Carboxylated schizophyllan (sclerox) samples of different degrees of oxidation were molecularly characterized by size exclusion chromatography equipped with a multi-angle light scattering detector (SEC-MALS) in 0.10 M aqueous NaCl solution. The molar mass distribution obtained by SEC-MALS shows that sclerox of low degree of oxidation is dissolved mainly as the trimer, whereas the trimer and single chain coexist in solution of sclerox of high degree of oxidation. The trimer of sclerox is much more flexible than the fully ordered triple helix of the parent schizophyllan and easily dissociates into single chains upon heating. PMID:26428092

  15. Synthetic cannabinoids as designer drugs: new representatives of indol-3-carboxylates series and indazole-3-carboxylates as novel group of cannabinoids. Identification and analytical data.

    PubMed

    Shevyrin, Vadim; Melkozerov, Vladimir; Nevero, Alexander; Eltsov, Oleg; Baranovsky, Alexander; Shafran, Yuri

    2014-11-01

    By means of gas chromatography with mass spectrometry detection (GC-MS), including high resolution mass spectrometry (GC-HRMS) together with ultra-high performance liquid chromatography in combination with high resolution tandem mass spectrometry (UHPLC-HRMS), nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FT-IR), structure of new synthetic cannabinoids, representatives of indol- and indazole-3-carboxylates groups, used in smoke mixtures, was determined. Obtained analytical data make reliable identification of these compounds in a course of analysis of criminal seizures possible. PMID:25305529

  16. Spectroscopic study on uranyl carboxylate complexes formed at the surface layer of Sulfolobus acidocaldarius.

    PubMed

    Reitz, Thomas; Rossberg, Andre; Barkleit, Astrid; Steudtner, Robin; Selenska-Pobell, Sonja; Merroun, Mohamed L

    2015-02-14

    The complexation of U(vi) at the proteinaceous surface layer (S-layer) of the archaeal strain Sulfolobus acidocaldarius was investigated over a pH range from pH 1.5 to 6 at the molecular scale using time-resolved laser-induced fluorescence spectroscopy (TRLFS) and U L(III)-edge extended X-ray absorption fine structure (EXAFS). The S-layer, which represents the interface between the cell and its environment, is very stable against high temperatures, proteases, and detergents. This allowed the isolation and purification of S-layer ghosts (= empty cells) that maintain the size and shape of the cells. In contrast to many other microbial cell envelope compounds the studied S-layer is not phosphorylated, enabling the investigation of uranyl carboxylate complexes formed at microbial surfaces. The latter are usually masked by preferentially formed uranyl phosphate complexes. We demonstrated that at highly acidic conditions (pH 1.5 to 3) no uranium was bound by the S-layer. In contrast to that, at moderate acidic pH conditions (pH 4.5 and 6) a complexation of U(vi) at the S-layer via deprotonated carboxylic groups was stimulated. Titration studies revealed dissociation constants for the carboxylic groups of glutamic and aspartic acid residues of pK(a) = 4.78 and 6.31. The uranyl carboxylate complexes formed at the S-layer did not show luminescence properties at room temperature, but only under cryogenic conditions. The obtained luminescence maxima are similar to those of uranyl acetate. EXAFS spectroscopy demonstrated that U(vi) in these complexes is mainly coordinated to carboxylate groups in a bidentate binding mode. The elucidation of the molecular structure of these complexes was facilitated by the absence of phosphate groups in the studied S-layer protein. PMID:25387060

  17. Metabolism of Cyclohexane Carboxylic Acid by Alcaligenes Strain W1

    PubMed Central

    Taylor, David G.; Trudgill, Peter W.

    1978-01-01

    Thirty-three microorganisms capable of growth with cyclohexane carboxylate as the sole source of carbon were isolated from mud, water, and soil samples from the Aberystwyth area. Preliminary screening and whole-cell oxidation studies suggested that, with one exception, all of the strains metabolized the growth substrate by beta-oxidation of the coenzyme A ester. This single distinctive strain, able to oxidize rapidly trans-4-hydroxycyclohexane carboxylate, 4-ketocyclohexane carboxylate, p-hydroxybenzoate, and protocatechuate when grown with cyclohexane carboxylate, was classified as a strain of Alcaligenes and given the number W1. Enzymes capable of converting cyclohexane carboxylate to p-hydroxybenzoate were induced by growth with the alicyclic acid and included the first unambiguous specimen of a cyclohexane carboxylate hydroxylase. Because it is a very fragile protein, attempts to stabilize the cyclohexane carboxylate hydroxylase so that a purification procedure could be developed have consistently failed. In limited studies with crude cell extracts, we found that hydroxylation occurred at the 4 position, probably yielding the trans isomer of 4-hydroxycyclohexane carboxylate. Simultaneous measurement of oxygen consumption and reduced nicotinamide adenine dinucleotide oxidation, coupled with an assessment of reactant stoichiometry, showed the enzyme to be a mixed-function oxygenase. Mass spectral analysis enabled the conversion of cyclohexane carboxylate to p-hydroxybenzoate by cell extracts to be established unequivocally, and all of our data were consistent with the pathway: cyclohexane carboxylate → trans-4-hydroxycyclohexane carboxylate → 4-ketocyclohexane carboxylate → p-hydroxybenzoate. The further metabolism of p-hydroxybenzoate proceeded by meta fission and by the oxidative branch of the 2-hydroxy-4-carboxymuconic semialde-hyde-cleaving pathway. PMID:207665

  18. Extraction, purification, methylation and GC-MS analysis of short-chain carboxylic acids for metabolic flux analysis.

    PubMed

    Tivendale, Nathan D; Jewett, Erin M; Hegeman, Adrian D; Cohen, Jerry D

    2016-08-15

    Dynamic metabolic flux analysis requires efficient and effective methods for extraction, purification and analysis of a plethora of naturally-occurring compounds. One area of metabolism that would be highly informative to study using metabolic flux analysis is the tricarboxylic acid (TCA) cycle, which consists of short-chain carboxylic acids. Here, we describe a newly-developed method for extraction, purification, derivatization and analysis of short-chain carboxylic acids involved in the TCA cycle. The method consists of snap-freezing the plant material, followed by maceration and a 12-15h extraction at -80 °C. The extracts are then subject to reduction (to stabilize β-keto acids), purified by strong anion exchange solid phase extraction and methylated with methanolic HCl. This method could also be readily adapted to quantify many other short-chain carboxylic acids. PMID:27348709

  19. Strong-acid, carboxyl-group structures in fulvic acid from the Suwannee River, Georgia. 1. Minor structures

    USGS Publications Warehouse

    Leenheer, J.A.; Wershaw, R. L.; Reddy, M.M.

    1995-01-01

    An investigation of the strong-acid characteristics (pKa 3.0 or less) of fulvic acid from the Suwannee River, Georgia, was conducted. Quantitative determinations were made for amino acid and sulfur-containing acid structures, oxalate half-ester structures, malonic acid structures, keto acid structures, and aromatic carboxyl-group structures. These determinations were made by using a variety of spectrometric (13C-nuclear magnetic resonance, infrared, and ultraviolet spectrometry) and titrimetric characterizations on fulvic acid or fulvic acid samples that were chemically derivatized to indicate certain functional groups. Only keto acid and aromatic carboxyl-group structures contributed significantly to the strong-acid characteristics of the fulvic acid; these structures accounted for 43% of the strong-acid acidity. The remaining 57% of the strong acids are aliphatic carboxyl groups in unusual and/or complex configurations for which limited model compound data are available.

  20. (19)F NMR study of ligand dynamics in carboxylate-bridged diiron(II) complexes supported by a macrocyclic ligand.

    PubMed

    Minier, Mikael A; Lippard, Stephen J

    2015-11-01

    A series of asymmetrically carboxylate-bridged diiron(ii) complexes featuring fluorine atoms as NMR spectroscopic probes, [Fe2(PIM)(Ar(4F-Ph)CO2)2] (10), [Fe2(F2PIM)(Ar(Tol)CO2)2] (11), and [Fe2(F2PIM)(Ar(4F-Ph)CO2)2] (12), were prepared and characterized by X-ray crystallography, Mössbauer spectroscopy, and VT (19)F NMR spectroscopy. These complexes are part of a rare family of syn N-donor diiron(ii) compounds, [Fe2(X2PIM)(RCO2)2], that are structurally very similar to the active site of the hydroxylase enzyme component of reduced methane monooxygenase (MMOHred). Solution characterization of these complexes demonstrates that they undergo intramolecular carboxylate rearrangements, or carboxylate shifts, a dynamic feature relevant to the reactivity of the diiron centers in bacterial multicomponent monooxygenases. PMID:26418547

  1. Decarboxylative Fluorination of Aliphatic Carboxylic Acids via Photoredox Catalysis

    PubMed Central

    Ventre, Sandrine; Petronijevic, Filip R.; MacMillan, David W. C.

    2016-01-01

    The direct conversion of aliphatic carboxylic acids to the corresponding alkyl fluorides has been achieved via visible light-promoted photoredox catalysis. This operationally simple, redox-neutral fluorination method is amenable to a wide variety of carboxylic acids. Photon-induced oxidation of carboxylates leads to the formation of carboxyl radicals, which upon rapid CO2-extrusion and F• transfer from a fluorinating reagent yield the desired fluoroalkanes with high efficiency. Experimental evidence indicates that an oxidative quenching pathway is operable in this broadly applicable fluorination protocol. PMID:25881929

  2. Metabolomic Analysis of Key Central Carbon Metabolism Carboxylic Acids as Their 3-Nitrophenylhydrazones by UPLC/ESI-MS

    PubMed Central

    Han, Jun; Gagnon, Susannah; Eckle, Tobias; Borchers, Christoph H.

    2014-01-01

    Multiple hydroxy-, keto-, di-, and tri-carboxylic acids are among the cellular metabolites of central carbon metabolism (CCM). Sensitive and reliable analysis of these carboxylates is important for many biological and cell engineering studies. In this work, we examined 3-nitrophenylhydrazine as a derivatizing reagent and optimized the reaction conditions for the measurement of ten CCM related carboxylic compounds, including glycolate, lactate, malate, fumarate, succinate, citrate, isocitrate, pyruvate, oxaloacetate, and α-ketoglutarate as their 3-nitrophenylhydrazones using LC/MS with electrospray ionization. With the derivatization protocol which we have developed, and using negative-ion multiple reaction monitoring on a triple-quadrupole instrument, all of the carboxylates showed good linearity within a dynamic range of ca. 200 to more than 2000. The on-column limits of detection and quantitation were from high femtomoles to low picomoles. The analytical accuracies for eight of the ten analytes were determined to be between 89.5 to 114.8% (CV≤7.4%, n=6). Using a quadrupole time-of-flight instrument, the isotopic distribution patterns of these carboxylates, extracted from a 13C-labeled mouse heart, were successfully determined by UPLC/MS with full-mass detection, indicating the possible utility of this analytical method for metabolic flux analysis. In summary, this work demonstrates an efficient chemical derivatization LC/MS method for metabolomic analysis of these key CCM intermediates in a biological matrix. PMID:23580203

  3. Extraterrestrial Organic Compounds in Meteorites

    NASA Technical Reports Server (NTRS)

    Botta, Oliver; Bada, Jeffrey L.; Meyer, Michael (Technical Monitor)

    2003-01-01

    Many organic compounds or their precursors found in meteorites originated in the interstellar or circumstellar medium and were later incorporated into planetesimals during the formation of the solar system. There they either survived intact or underwent further processing to synthesize secondary products on the meteorite parent body. The most distinct feature of CI and CM carbonaceous chondrites, two types of stony meteorites, is their high carbon content (up to 3% of weight), either in the form of carbonates or of organic compounds. The bulk of the organic carbon consists of an insoluble macromolecular material with a complex structure. Also present is a soluble organic fraction, which has been analyzed by several separation and analytical procedures. Low detection limits can be achieved by derivatization of the organic molecules with reagents that allow for analysis by gas chromatography/mass spectroscopy and high performance liquid chromatography. The CM meteorite Murchison has been found to contain more than 70 extraterrestrial amino acids and several other classes of compounds including carboxylic acids, hydroxy carboxylic acids, sulphonic and phosphonic acids, aliphatic, aromatic and polar hydrocarbons, fullerenes, heterocycles as well as carbonyl compounds, alcohols, amines and amides. The organic matter was found to be enriched in deuterium, and distinct organic compounds show isotopic enrichments of carbon and nitrogen relative to terrestrial matter.

  4. Z-effect reversal in carboxylic acid associates.

    PubMed

    Medvedev, Michael G; Bushmarinov, Ivan S; Lyssenko, Konstantin A

    2016-05-01

    The carboxylic group is a common fragment in synthetic compounds and biomolecules. Its conformation is assumed to be dominantly cis due to so-called Z-effect. However, in this study, we show that the nature of the H-bond acceptor in RCOOHX directly affects the conformational preference of the resulting supermolecule. This result is evident from the statistical analysis of available crystallographic data and was quantified using accurate quantum chemical calculations. We propose the term "supramolecular stereoelectronic effect" for the observed conformational preference. The likely reason for this is the interaction of the O-HX hydrogen bond with the C[double bond, length as m-dash]O double bond in the trans conformation, which in case of anionic X is strong enough to reverse the Z-effect. Explicit consideration of trans COOHX stabilization can help crystal structure predictions and biomolecular simulations. In particular, this effect plays a key role in the transition between the T6 and R6 forms of human insulin. PMID:27109148

  5. Lysine carboxylation: unveiling a spontaneous post-translational modification

    SciTech Connect

    Jimenez-Morales, David; Adamian, Larisa; Shi, Dashuang; Liang, Jie

    2014-01-01

    A computational method for the prediction of lysine carboxylation (KCX) in protein structures is described. The method accurately identifies misreported KCXs and predicts previously unknown KCX sites. The carboxylation of lysine residues is a post-translational modification (PTM) that plays a critical role in the catalytic mechanisms of several important enzymes. It occurs spontaneously under certain physicochemical conditions, but is difficult to detect experimentally. Its full impact is unknown. In this work, the signature microenvironment of lysine-carboxylation sites has been characterized. In addition, a computational method called Predictor of Lysine Carboxylation (PreLysCar) for the detection of lysine carboxylation in proteins with available three-dimensional structures has been developed. The likely prevalence of lysine carboxylation in the proteome was assessed through large-scale computations. The results suggest that about 1.3% of large proteins may contain a carboxylated lysine residue. This unexpected prevalence of lysine carboxylation implies an enrichment of reactions in which it may play functional roles. The results also suggest that by switching enzymes on and off under appropriate physicochemical conditions spontaneous PTMs may serve as an important and widely used efficient biological machinery for regulation.

  6. 40 CFR 721.10255 - Vinyl carboxylic acid ester (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Vinyl carboxylic acid ester (generic... Specific Chemical Substances § 721.10255 Vinyl carboxylic acid ester (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as...

  7. 40 CFR 721.10255 - Vinyl carboxylic acid ester (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Vinyl carboxylic acid ester (generic... Specific Chemical Substances § 721.10255 Vinyl carboxylic acid ester (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as...

  8. 40 CFR 721.10255 - Vinyl carboxylic acid ester (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Vinyl carboxylic acid ester (generic... Specific Chemical Substances § 721.10255 Vinyl carboxylic acid ester (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as...

  9. 40 CFR 721.2093 - Alkenyl carboxylate, metal salt (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.2093 Alkenyl carboxylate, metal salt (generic). (a) Chemical substance... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkenyl carboxylate, metal...

  10. Preparation of {alpha}, {beta}-unsaturated carboxylic acids and anhydrides

    DOEpatents

    Spivey, J.J.; Gogate, M.R.; Zoeller, J.R.; Tustin, G.C.

    1998-01-20

    Disclosed is a process for the preparation of {alpha},{beta}-unsaturated carboxylic acids and anhydrides thereof which comprises contacting formaldehyde or a source of formaldehyde with a carboxylic anhydride in the presence of a catalyst comprising mixed oxides of vanadium, phosphorus and, optionally, a third component selected from titanium, aluminum or, preferably silicon.

  11. Preparation of .alpha., .beta.-unsaturated carboxylic acids and anhydrides

    DOEpatents

    Spivey, James Jerry; Gogate, Makarand Ratnakav; Zoeller, Joseph Robert; Tustin, Gerald Charles

    1998-01-01

    Disclosed is a process for the preparation of .alpha.,.beta.-unsaturated carboxylic acids and anhydrides thereof which comprises contacting formaldehyde or a source of formaldehyde with a carboxylic anhydride in the presence of a catalyst comprising mixed oxides of vanadium, phosphorus and, optionally, a third component selected from titanium, aluminum or, preferably silicon.

  12. Preparation of .alpha.,.beta.-unsaturated carboxylic acids and esters

    DOEpatents

    Gogate, Makarand Ratnakar; Spivey, James Jerry; Zoeller, Joseph Robert

    1998-01-01

    Disclosed is a process for the preparation of .alpha.,.beta.-unsaturated carboxylic acids and esters thereof which comprises contacting formaldehyde or a source of formaldehyde with a carboxylic acid, ester or anhydride in the presence of a catalyst comprising an oxide of niobium.

  13. Preparation of {alpha},{beta}-unsaturated carboxylic acids and esters

    DOEpatents

    Gogate, M.R.; Spivey, J.J.; Zoeller, J.R.

    1998-09-15

    Disclosed is a process for the preparation of {alpha},{beta}-unsaturated carboxylic acids and esters thereof which comprises contacting formaldehyde or a source of formaldehyde with a carboxylic acid, ester or anhydride in the presence of a catalyst comprising an oxide of niobium.

  14. Novel lead(II) carboxylate arsonate hybrids

    NASA Astrophysics Data System (ADS)

    Yi, Fei-Yan; Song, Jun-Ling; Zhao, Na; Mao, Jiang-Gao

    2008-06-01

    Hydrothermal reactions of lead(II) acetate with phenylarsonic acid (H 2L 1) (or 4-hydroxy-3-nitrophenylarsonic acid, H 3L 2) and 5-sulfoisophthalic acid monosodium salt (NaH 2SIP) (or 1,3,5-benzenetricarboxylic acid (H 3BTC)) as the second metal linkers afforded three novel mixed-ligand lead(II) carboxylate-arsonates, namely, Pb 5(SIP) 2(L 1) 2(H 2O) 1, Pb 3(SIP)(L 2)(H 2O) 2 and Pb(H 2L 2)(H 2BTC) 3. The structure of 1 features a complicated 3D network composed of 2D double layers of lead(II) sulfoisophthalate bridged by 1D chains of lead(II) arsonates along b-axis, forming large tunnels along b-axis which are occupied by phenyl rings of the arsonate ligands. In 2, the Pb(II) ions are bridged by {L 2} 3- anions into a 2D double layer whereas the interconnection of the Pb(II) ions via bridging and chelating SIP anions gave a 2D double layer. The cross-linkage of the above two building units leads to a complicated 3D network. In 3, the interconnection of the Pb(II) ions via bridging {H 2L 2} - and {H 2BTC} - anions leads to a 1D double chain down a-axis. These 1D chains are further interconnected via hydrogen bonds among non-coordination carboxylate groups and arsonate oxygens into a 3D supramolecular architecture.

  15. Aqueous infrared carboxylate absorbances: Aliphatic di-acids

    USGS Publications Warehouse

    Cabaniss, S.E.; Leenheer, J.A.; McVey, I.F.

    1998-01-01

    Aqueous attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra of 18 aliphatic di-carboxylic acids are reported as a function of pH. The spectra show isosbestic points and intensity changes which indicate that Beer's law is obeyed, and peak frequencies lie within previously reported ranges for aqueous carboxylates and pure carboxylic acids. Intensity sharing from the symmetric carboxylate stretch is evident in many cases, so that bands which are nominally due to alkyl groups show increased intensity at higher pH. The asymmetric stretch of the HA- species is linearly related to the microscopic acidity constant of the H2A species, with ??pK 2 intervening atoms). The results suggest that aqueous ATR-FTIR may be able to estimate 'intrinsic' pKa values of carboxylic acids, in addition to providing quantitative estimates of ionization. ?? 1998 Elsevier Science B.V. All rights reserved.

  16. Carboxylic Acid Fullerene (C60) Derivatives Attenuated Neuroinflammatory Responses by Modulating Mitochondrial Dynamics

    NASA Astrophysics Data System (ADS)

    Ye, Shefang; Zhou, Tong; Cheng, Keman; Chen, Mingliang; Wang, Yange; Jiang, Yuanqin; Yang, Peiyan

    2015-05-01

    Fullerene (C60) derivatives, a unique class of compounds with potent antioxidant properties, have been reported to exert a wide variety of biological activities including neuroprotective properties. Mitochondrial dynamics are an important constituent of cellular quality control and function, and an imbalance of the dynamics eventually leads to mitochondria disruption and cell dysfunctions. This study aimed to assess the effects of carboxylic acid C60 derivatives (C60-COOH) on mitochondrial dynamics and elucidate its associated mechanisms in lipopolysaccharide (LPS)-stimulated BV-2 microglial cell model. Using a cell-based functional screening system labeled with DsRed2-mito in BV-2 cells, we showed that LPS stimulation led to excessive mitochondrial fission, increased mitochondrial localization of dynamin-related protein 1 (Drp1), both of which were markedly suppressed by C60-COOH pretreatment. LPS-induced mitochondria reactive oxygen species (ROS) generation and collapse of mitochondrial membrane potential (Δ Ψm) were also significantly inhibited by C60-COOH. Moreover, we also found that C60-COOH pretreatment resulted in the attenuation of LPS-mediated activation of nuclear factor (NF)-κB and mitogen-activated protein kinase (MAPK) signaling, as well as the production of pro-inflammatory mediators. Taken together, these findings demonstrated that carboxylic acid C60 derivatives may exert neuroprotective effects through regulating mitochondrial dynamics and functions in microglial cells, thus providing novel insights into the mechanisms of the neuroprotective properties of carboxylic acid C60 derivatives.

  17. Partial Hydrothermal Oxidation of High Molecular Weight Unsaturated Carboxylic Acids for Upgrading of Biodiesel Fuel

    NASA Astrophysics Data System (ADS)

    Kawasaki, K.; Jin, F.; Kishita, A.; Tohji, K.; Enomoto, H.

    2007-03-01

    With increasing environmental awareness and crude oil price, biodiesel fuel (BDF) is gaining recognition as a renewable fuel which may be used as an alternative diesel fuel without any modification to the engine. The cold flow and viscosity of BDF, however, is a major drawback that limited its use in cold area. In this study, therefore, we investigated that partial oxidation of high molecular weight unsaturated carboxylic acids in subcritical water, which major compositions in BDF, to upgrade biodiesel fuel. Oleic acid, (HOOC(CH2)7CH=CH(CH2)7CH3), was selected as a model compound of high molecular weight unsaturated carboxylic acids. All experiments were performed with a batch reactor made of SUS 316 with an internal volume of 5.7 cm3. Oleic acid was oxidized at 300 °C with oxygen supply varying from 1-10 %. Results showed that a large amount of carboxylic acids and aldehydes having 8-9 carbon atoms were formed. These experimental results suggest that the hydrothermal oxidative cleavage may mainly occur at double bonds and the cleavage of double bonds could improve the cold flow and viscosity of BDF.

  18. Functionalised carboxylic acids in atmospheric particles: An annual cycle revealing seasonal trends and possible sources

    NASA Astrophysics Data System (ADS)

    Teich, Monique; van Pinxteren, Dominik; Herrmann, Hartmut

    2013-04-01

    Carboxylic acids represent a major fraction of the water soluble organic carbon (WSOC) in atmospheric particles. Among the particle phase carboxylic acids, straight-chain monocarboxylic acids (MCA) and dicarboxylic acids (DCA) with 2-10 carbon atoms have extensively been studied in the past. However, only a few studies exist dealing with functionalised carboxylic acids, i.e. having additional hydroxyl-, oxo- or nitro-groups. Regarding atmospheric chemistry, these functionalised carboxylic acids are of particular interest as they are supposed to be formed during atmospheric oxidation processes, e.g. through radical reactions. Therefore they can provide insights into the tropospheric multiphase chemistry. During this work 28 carboxylic acids (4 functionalised aliphatic MCAs, 5 aromatic MCAs, 3 nitroaromatic MCAs, 6 aliphatic DCAs, 6 functionalised aliphatic DCAs, 4 aromatic DCAs) were quantitatively determined in 256 filter samples taken at the rural research station Melpitz (Saxony, Germany) with a PM10 Digitel DHA-80 filter sampler. All samples were taken in 2010 covering a whole annual cycle. The resulting dataset was examined for a possible seasonal dependency of the acid concentrations. Furthermore the influence of the air mass origin on the acid concentrations was studied based on a simple two-sector classification (western or eastern sector) using a back trajectory analysis. Regarding the annual average, adipic acid was found to be the most abundant compound with a mean concentration of 7.8 ng m-3 followed by 4-oxopimelic acid with 6.1 ng m-3. The sum of all acid concentrations showed two maxima during the seasonal cycle; one in summer and one in winter, whereas the highest overall acid concentrations were found in summer. In general the target acids could be divided into two different groups, where one group has its maximum concentration in summer and the other group during winter. The first group contains all investigated aliphatic mono- and dicarboxylic

  19. Sm(II)-Mediated Electron Transfer to Carboxylic Acid Derivatives: Development of Complexity-Generating Cascades.

    PubMed

    Just-Baringo, Xavier; Procter, David J

    2015-05-19

    Reductive electron transfer (ET) to organic compounds is a powerful method for the activation of substrates via the formation of radicals, radical anions, anions, and dianions that can be exploited in bond-cleaving and bond-forming processes. Since its introduction to the synthetic community in 1977 by Kagan, SmI2 has become one of the most important reducing agents available in the laboratory. Despite its widespread application in aldehyde and ketone reduction, it was widely accepted that carboxylic acid derivatives could not be reduced by SmI2; only recently has our work led to this dogma being overturned, and the reduction of carboxylic acid derivatives using SmI2 can now take its place alongside aldehyde/ketone reduction as a powerful activation mode for synthesis. In this Account, we set out our studies of the reduction of carboxylic acid derivatives using SmI2, SmI2-H2O, and SmI2-H2O-NR3 and the exploitation of the unusual radical anions that are now accessible in unprecedented carbon-carbon bond-forming processes. The Account begins with our serendipitous discovery that SmI2 mixed with H2O is able to reduce six-membered lactones to diols, a transformation previously thought to be impossible. After the successful development of selective monoreductions of Meldrum's acid and barbituric acid heterocyclic feedstocks, we then identified the SmI2-H2O-NR3 reagent system for the efficient reduction of a range of acyclic carboxylic acid derivatives that typically present a significant challenge for ET reductants. Mechanistic studies have led us to propose a common mechanism for the reduction of carboxylic acid derivatives using Sm(II), with only subtle changes observed as the carboxylic acid derivative and Sm(II) reagent system are varied. At the center of our postulated mechanism is the proposed reversibility of the first ET to the carbonyl of carboxylic acid derivatives, and this led us to devise several strategies that allow the radical anion intermediates to be

  20. S-Farnesyl-Thiopropionic Acid Triazoles as Potent Inhibitors of Isoprenylcysteine Carboxyl Methyltransferase

    PubMed Central

    2011-01-01

    We report the design and synthesis of novel FTPA-triazole compounds as potent inhibitors of isoprenylcysteine carboxyl methyltransferase (Icmt), through a focus on thioether and isoprenoid mimetics. These mimetics were coupled utilizing a copper-assisted cycloaddition to assemble the potential inhibitors. Using the resulting triazole from the coupling as an isoprenyl mimetic resulted in the biphenyl-substituted FTPA triazole 10n. This lipid-modified analogue is a potent inhibitor of Icmt (IC50 = 0.8 ± 0.1 μM; calculated Ki = 0.4 μM). PMID:22754607

  1. Silver(I)-Promoted ipso-Nitration of Carboxylic Acids by Nitronium Tetrafluoroborate.

    PubMed

    Natarajan, Palani; Chaudhary, Renu; Venugopalan, Paloth

    2015-11-01

    A novel and efficient method for the regioselective nitration of a series of aliphatic and aromatic carboxylic acids to their corresponding nitro compounds using nitronium tetrafluoroborate and silver carbonate in dimethylacetamide has been described. This transformation is believed to proceed via the alkyl-silver or aryl-silver intermediate, which subsequently reacts with the nitronium ion to form nitro substances. Mild reaction conditions, tolerant of a broad range of functional groups, and formation of only the ipso-nitrated products are the key features of this methodology when compared to known methods for syntheses of nitroalkyls and nitroarenes. PMID:26457769

  2. 3,4-Di­methyl­phenyl quinoline-2-carboxyl­ate

    PubMed Central

    Fazal, E.; Kaur, Manpreet; Sudha, B. S.; Nagarajan, S.; Jasinski, Jerry P.

    2013-01-01

    In the title compound, C18H15NO2, the dihedral angle between the mean planes of the quinoline ring system and the phenyl ring is 48.1 (5)°. The mean plane of the carboxyl­ate group is twisted from the mean planes of the latter by 19.8 (8) and 64.9 (5)°, respectively. The crystal packing features weak C—H⋯O inter­actions, which form chains along [010]. PMID:24454268

  3. CBL-2201. Report on a new designer drug: Napht-1-yl 1-(5-fluoropentyl)-1H-indole-3-carboxylate.

    PubMed

    Kondrasenko, A A; Goncharov, E V; Dugaev, K P; Rubaylo, A I

    2015-12-01

    The (1)H, (13)C and (15)N nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR) and gas chromatography coupled to mass spectrometry (GC-MS) identification of a synthetic cannabinoid compound has been conducted. It was shown that this compound cannot be reliably distinguished from the closely related quinolin-8-yl indole-3-carboxylic acid derivative by an automatic search in MS library. Structural difference of the studied compound and known illicit compounds has been determined using 1D and 2D NMR spectroscopy. Analytical data for the identification of this compound were provided. PMID:26386336

  4. Organic Compounds in Carbonaceous Meteorites

    NASA Technical Reports Server (NTRS)

    Cooper, Grorge

    2001-01-01

    Carbonaceous meteorites are relatively enriched in soluble organic compounds. To date, these compounds provide the only record available to study a range of organic chemical processes in the early Solar System chemistry. The Murchison meteorite is the best-characterized carbonaceous meteorite with respect to organic chemistry. The study of its organic compounds has related principally to aqueous meteorite parent body chemistry and compounds of potential importance for the origin of life. Among the classes of organic compounds found in Murchison are amino acids, amides, carboxylic acids, hydroxy acids, sulfonic acids, phosphonic acids, purines and pyrimidines (Table 1). Compounds such as these were quite likely delivered to the early Earth in asteroids and comets. Until now, polyhydroxylated compounds (polyols), including sugars (polyhydroxy aldehydes or ketones), sugar alcohols, sugar acids, etc., had not been identified in Murchison. Ribose and deoxyribose, five-carbon sugars, are central to the role of contemporary nucleic acids, DNA and RNA. Glycerol, a three-carbon sugar alcohol, is a constituent of all known biological membranes. Due to the relative lability of sugars, some researchers have questioned the lifetime of sugars under the presumed conditions on the early Earth and postulated other (more stable) compounds as constituents of the first replicating molecules. The identification of potential sources and/or formation mechanisms of pre-biotic polyols would add to the understanding of what organic compounds were available, and for what length of time, on the ancient Earth.

  5. Transcriptomic Analysis of Carboxylic Acid Challenge in Escherichia coli: Beyond Membrane Damage

    PubMed Central

    Royce, Liam A.; Boggess, Erin; Fu, Yao; Liu, Ping; Shanks, Jacqueline V.; Dickerson, Julie; Jarboe, Laura R.

    2014-01-01

    Carboxylic acids are an attractive biorenewable chemical. Enormous progress has been made in engineering microbes for production of these compounds though titers remain lower than desired. Here we used transcriptome analysis of Escherichia coli during exogenous challenge with octanoic acid (C8) at pH 7.0 to probe mechanisms of toxicity. This analysis highlights the intracellular acidification and membrane damage caused by C8 challenge. Network component analysis identified transcription factors with altered activity including GadE, the activator of the glutamate-dependent acid resistance system (AR2) and Lrp, the amino acid biosynthesis regulator. The intracellular acidification was quantified during exogenous challenge, but was not observed in a carboxylic acid producing strain, though this may be due to lower titers than those used in our exogenous challenge studies. We developed a framework for predicting the proton motive force during adaptation to strong inorganic acids and carboxylic acids. This model predicts that inorganic acid challenge is mitigated by cation accumulation, but that carboxylic acid challenge inverts the proton motive force and requires anion accumulation. Utilization of native acid resistance systems was not useful in terms of supporting growth or alleviating intracellular acidification. AR2 was found to be non-functional, possibly due to membrane damage. We proposed that interaction of Lrp and C8 resulted in repression of amino acid biosynthesis. However, this hypothesis was not supported by perturbation of lrp expression or amino acid supplementation. E. coli strains were also engineered for altered cyclopropane fatty acid content in the membrane, which had a dramatic effect on membrane properties, though C8 tolerance was not increased. We conclude that achieving higher production titers requires circumventing the membrane damage. As higher titers are achieved, acidification may become problematic. PMID:24586888

  6. A NEW NON-AMBIGUOUS ANALYTICAL TECHNIQUE FOR THE IDENTIFICATION OF AEROSOL OXYGENATED COMPOUNDS

    EPA Science Inventory

    The most important organic products identified in the particle phase from field samples and from smog chamber experiments are polar oxygenated compounds containing one, two, three or more oxygenated functional groups (e.g. hydroxyl, carboxylic acid, ketone). Current procedures ...

  7. Lysine carboxylation: unveiling a spontaneous post-translational modification

    PubMed Central

    Jimenez-Morales, David; Adamian, Larisa; Shi, Dashuang; Liang, Jie

    2014-01-01

    The carboxylation of lysine residues is a post-translational modification (PTM) that plays a critical role in the catalytic mechanisms of several important enzymes. It occurs spontaneously under certain physicochemical conditions, but is difficult to detect experimentally. Its full impact is unknown. In this work, the signature microenvironment of lysine-carboxylation sites has been characterized. In addition, a computational method called Predictor of Lysine Carboxyl­ation (PreLysCar) for the detection of lysine carboxylation in proteins with available three-dimensional structures has been developed. The likely prevalence of lysine carboxylation in the proteome was assessed through large-scale computations. The results suggest that about 1.3% of large proteins may contain a carboxylated lysine residue. This unexpected prevalence of lysine carboxylation implies an enrichment of reactions in which it may play functional roles. The results also suggest that by switching enzymes on and off under appropriate physicochemical conditions spontaneous PTMs may serve as an important and widely used efficient biological machinery for regulation. PMID:24419378

  8. Design of co-crystals/salts of some Nitrogenous bases and some derivatives of thiophene carboxylic acids through a combination of hydrogen and halogen bonds

    PubMed Central

    2014-01-01

    Background The utility of N-heterocyclic bases to obtain molecular complexes with carboxylic acids is well studied. Depending on the solid state interaction between the N-heterocyclic base and a carboxylic acid a variety of neutral or ionic synthons are observed. Meanwhile, pyridines and pyrimidines have been frequently chosen in the area of crystal engineering for their multipurpose functionality. HT (hetero trimers) and LHT (linear heterotetramers) are the well known synthons that are formed in the presence of pyrimidines and carboxylic acids. Results Fourteen crystals involving various substituted thiophene carboxylic acid derivatives and nitrogenous bases were prepared and characterized by using single crystal X-ray diffraction. The 14 crystals can further be divided into two groups [1a-7a], [8b-14b] based on the nature of the nitrogenous base. Carboxylic acid to pyridine proton transfer has occurred in 3 compounds of each group. In addition to the commonly occurring hydrogen bond based pyridine/carboxylic acid and pyrimidine/carboxylic acid synthons which is the reason for assembly of primary motifs, various other interactions like Cl…Cl, Cl…O, C–H…Cl, C-H…S add additional support in organizing these supermolecules into extended architectures. It is also interesting to note that in all the compounds π-π stacking occurs between the pyrimidine-pyrimidine or pyridine-pyridine or acid-acid moieties rather than acid-pyrimidine/pyridine. Conclusions In all the compounds (1a-14b) either neutral O–H…Npyridyl/pyrimidine or charge-assisted Npyridinium-H…Ocarboxylate hydrogen bonds are present. The HT (hetero trimers) and LHT (linear heterotetramers) are dominant in the crystal structures of the adducts containing N-heterocyclic bases with two proton acceptors (1a-7a). Similar type supramolecular ladders are observed in 5TPC44BIPY (8b), TPC44BIPY (9b), TPC44TMBP (11b). Among the seven compounds [8b-14b] the extended ligands are linear in all except for

  9. Unusual metal-ligand charge transfer in ferrocene functionalized μ3-O iron carboxylates observed with Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Mereacre, Valeriu; Schlageter, Martin; Eichhöfer, Andreas; Bauer, Thomas; Wolny, Juliusz A.; Schünemann, Volker; Powell, Annie K.

    2016-06-01

    Temperature dependent Mössbauer studies of two ferrocenecarboxylate functionalized {Fe3O} complexes in solid state are reported. It was found that conjugation of ferrocene ring orbitals with the π orbitals of the adjacent carboxylic group promotes a shift of electron density from the ferrocene FeII ion to the cyclopentadienide rings with π-orbital character giving rise to a new type of mixed-valence compound.

  10. Discovery of novel dihydrobenzofuran cyclopropane carboxylic acid based calcium sensing receptor antagonists for the treatment of osteoporosis.

    PubMed

    Liang, Gui-Bai; Zhou, Changyou; Huo, Xianghong; Wang, Hank; Yang, Xuelin; Huang, Shaoqiang; Wang, Haisheng; Wilkinson, Hilary; Luo, Lusong; Tang, Wei; Sutton, David; Li, Hong; Zaller, Dennis; Meinke, Peter T

    2016-08-15

    In a search for novel small molecule calcium-sensing receptor (CaSR) antagonists as oral bone anabolic agents, we discovered dihydrobenzofuran cyclopropane carboxylic acid derivatives, such as 12f (IC50=27.6nM), are highly potent calcium-sensing receptor antagonists. Studies in rats established that compound 12f stimulates parathyroid hormone (PTH) release in a fast-acting, pulsatile manner. PMID:27397499

  11. Radiation-induced carboxylation of chloroacetate ion: An avenue for making value-added products from carbon dioxide

    SciTech Connect

    Getoff, N.

    1997-12-31

    The major theme of this paper is the radiation-induced carboxylation monochloroacetic acid. The formation of various products originating from chloroacetate ion, CO{sub 2}, CO or/and formate was studied as a function of substrate concentration, absorbed radiation dose etc. Malonic acid and oxalic acid were found to be the major products in addition to succinic, maleic and citric acids. Small yields of other organic compounds were also found. The results from these studies will be reported.

  12. Hydrogenation of carboxylic acids with a homogeneous cobalt catalyst.

    PubMed

    Korstanje, Ties J; van der Vlugt, Jarl Ivar; Elsevier, Cornelis J; de Bruin, Bas

    2015-10-16

    The reduction of esters and carboxylic acids to alcohols is a highly relevant conversion for the pharmaceutical and fine-chemical industries and for biomass conversion. It is commonly performed using stoichiometric reagents, and the catalytic hydrogenation of the acids previously required precious metals. Here we report the homogeneously catalyzed hydrogenation of carboxylic acids to alcohols using earth-abundant cobalt. This system, which pairs Co(BF4)2·6H2O with a tridentate phosphine ligand, can reduce a wide range of esters and carboxylic acids under relatively mild conditions (100°C, 80 bar H2) and reaches turnover numbers of up to 8000. PMID:26472903

  13. Role of Phosphoenolpyruvate Carboxylation in Acetobacter xylinum

    PubMed Central

    Benziman, Moshe

    1969-01-01

    Glucose-grown cells of Acetobacter xylinum oxidized acetate only when the reaction mixture was supplemented with catalytic quantities of glucose or intermediates of the citrate cycle. Extracts, prepared by sonic treatment, catalyzed the formation of oxalacetate when incubated with phosphoenolpyruvate (PEP) and bicarbonate. Oxalacetate was not formed in the presence of pyruvate plus adenosine triphosphate. The ability to promote carboxylation of PEP was lower in succinate-grown cells than in glucose-grown cells. PEP carboxylase, partially purified from extracts by ammonium sulfate fractionation, catalyzed the stoichiometric formation of oxalacetate and inorganic phosphate from PEP and bicarbonate. The enzyme was not affected by acetyl-coenzyme A or inorganic phosphate. It was inhibited by adenosine diphosphate in a manner competitive with PEP (K1 = 1.3 mm) and by dicarboxylic acids of the citrate cycle; of these, succinate was the most potent inhibitor. It is suggested that the physiological role of PEP carboxylase in A. xylinum is to affect the net formation of C4 acids from C3 precursors, which are essential for the maintainance of the citrate cycle during growth on glucose. The relationship of PEP carboxylase to other enzyme systems metabolizing PEP and oxalacetate in A. xylinum is discussed. PMID:5788692

  14. Extraction of carboxylic acids by amine extractants

    SciTech Connect

    Tamada, Janet Ayako; King, C.J.

    1989-01-01

    This work examines the chemistry of solvent extraction by long-chain amines for recovery of carboxylic acids from dilute aqueous solution. Long-chain amines act as complexing agents with the acid, which facilitates distribution of the acid into the organic phase. The complexation is reversible, allowing for recovery of the acid from the organic phase and regeneration of the extractant. Batch extraction experiments were performed to study the complexation of acetic, lactic, succinic, malonic, fumaric, and maleic acids with Alamine 336, an aliphatic, tertiary amine extractant, dissolved in various diluents. Results were interpreted by a ''chemical'' model, in which stoichiometric ratios of acid and amine molecules are assumed to form complexes in the solvent phase. From fitting of the extraction data, the stoichiometry of complexes formed and the corresponding equilibrium constants were obtained. The results of the model were combined with infrared spectroscopic experiments and results of past studies to analyze the chemical interactions that are responsible for extraction behavior. The information from the equilibrium studies was used to develop guidelines for large-scale staged extraction and regeneration schemes. A novel scheme, in which the diluent composition is shifted between extraction and regeneration, was developed which could achieve both high solute recovery and high product concentration. 169 refs., 57 figs., 15 tabs.

  15. Comparison of Three Solid Phase Materials for the Extraction of Carboxylic Acids from River Water Followed by 2D GC × GC-TOFMS Determination

    PubMed Central

    Bosire, G. O.; Ngila, J. C.; Parshotam, H.

    2016-01-01

    The extraction and determination of aliphatic and aromatic carboxylic acids as well as their influence on the aromaticity and molecularity relationship of natural organic matter (NOM) in water are reported in this study. Three solid phase extraction (SPE) sorbents were used and their extraction efficiencies evaluated after chromatographic determinations (using gas chromatography with a time of flight mass spectrometer (GC × GC-TOFMS) and liquid chromatography with organic carbon detector (LC-OCD)). More than 42 carboxylic acids were identified in raw water from the Vaal River, which feeds the Lethabo Power Generation Station, South Africa, with cooling water. The aromatic carboxylic acid efficiency (28%) was achieved by using Strata™ X SPE while the highest aliphatic carboxylic acid efficiency (92.08%) was achieved by silica SPE. The hydrophobic nature of NOM in water depends on the nature of organic compounds in water, whether aromatic or aliphatic. The LC-OCD was used to assess the hydrophobicity levels of NOM as a function of these carboxylic acids in cooling water. The LC-OCD results showed that the aromatic nature of NOM in SPE filtered water followed the order Silica>Strata X>C-18. From the results, the hydrophobicity degree of the samples depended on the type and number of carboxylic acids that were removed by the SPE cartridges. PMID:27274730

  16. Comparison of Three Solid Phase Materials for the Extraction of Carboxylic Acids from River Water Followed by 2D GC × GC-TOFMS Determination.

    PubMed

    Bosire, G O; Ngila, J C; Parshotam, H

    2016-01-01

    The extraction and determination of aliphatic and aromatic carboxylic acids as well as their influence on the aromaticity and molecularity relationship of natural organic matter (NOM) in water are reported in this study. Three solid phase extraction (SPE) sorbents were used and their extraction efficiencies evaluated after chromatographic determinations (using gas chromatography with a time of flight mass spectrometer (GC × GC-TOFMS) and liquid chromatography with organic carbon detector (LC-OCD)). More than 42 carboxylic acids were identified in raw water from the Vaal River, which feeds the Lethabo Power Generation Station, South Africa, with cooling water. The aromatic carboxylic acid efficiency (28%) was achieved by using Strata™ X SPE while the highest aliphatic carboxylic acid efficiency (92.08%) was achieved by silica SPE. The hydrophobic nature of NOM in water depends on the nature of organic compounds in water, whether aromatic or aliphatic. The LC-OCD was used to assess the hydrophobicity levels of NOM as a function of these carboxylic acids in cooling water. The LC-OCD results showed that the aromatic nature of NOM in SPE filtered water followed the order Silica>Strata X>C-18. From the results, the hydrophobicity degree of the samples depended on the type and number of carboxylic acids that were removed by the SPE cartridges. PMID:27274730

  17. Field and dilution effects on the magnetic relaxation behaviours of a 1D dysprosium(iii)-carboxylate chain built from chiral ligands.

    PubMed

    Han, Tian; Leng, Ji-Dong; Ding, You-Song; Wang, Yanyan; Zheng, Zhiping; Zheng, Yan-Zhen

    2015-08-14

    A one-dimensional dysprosium(iii)-carboxylate chain in which the Dy(III) ions sit in a pseudo D(2d)-symmetry environment is synthesized and shows different slow magnetic relaxation behaviours depending on the field and dilution effects. Besides, the chiral ligand introduces the additional functions of the Cotton effect and polarization for this compound. PMID:26159885

  18. ESTIMATION OF CARBOXYLIC ACID ESTER HYDROLYSIS RATE CONSTANTS

    EPA Science Inventory

    SPARC chemical reactivity models were extended to calculate hydrolysis rate constants for carboxylic acid esters from molecular structure. The energy differences between the initial state and the transition state for a molecule of interest are factored into internal and external...

  19. Photosensitive dissolution inhibitors and resists based on onium salt carboxylates

    DOEpatents

    Dentinger, Paul M.; Simison, Kelby L.

    2005-11-29

    A photoresist composition that employs onium salt carboxylates as thermally stable dissolution inhibitors. The photoresist composition can be either an onium carboxylate salt with a phenolic photoresist, such as novolac, or an onium cation protected carboxylate-containing resin such as an acrylic/acrylic acid copolymer. The onium carboxylate can be an onium cholate, wherein the onium cholate is an iodonium cholate. Particularly preferred iodonium cholates are alkyloxyphenylphenyl iodonium cholates and most particularly preferred is octyloxyphenyphenyl iodonium cholate. The photoresist composition will not create nitrogen or other gaseous byproducts upon exposure to radiation, does not require water for photoactivation, has acceptable UV radiation transmission characteristics, and is thermally stable at temperatures required for solvent removal.

  20. Direct esterification of ammonium salts of carboxylic acids

    DOEpatents

    Halpern, Yuval

    2003-06-24

    A non-catalytic process for producing esters, the process comprising reacting an ammonium salt of a carboxylic acid with an alcohol and removing ammonia from the reaction mixture. Selectivities for the desired ester product can exceed 95 percent.

  1. Syntheses, characterizations and crystal structures of two new lead(II) amino and carboxylate-sulfonates with a layered and a pillared layered structure

    NASA Astrophysics Data System (ADS)

    Yuan, Yan-Ping; Mao, Jiang-Gao; Song, Jun-Ling

    2004-03-01

    Reactions of lead(II) acetate with m-aminobenzenesulfonic acid (H L1) and 5-sulfoisophthalic acid (H 3L2) afforded two new lead(II) sulfonates, Pb( L1) 21 and Pb 2( L2)( μ3-OH)(H 2O) 2. In compound 1, the lead(II) ion is eight-coordinated by two sulfonate groups bidentately, two sulfonate groups unidentately and two amino groups from six ligands. Each L1 ligand is tetradentate and bridges with three Pb(II) ions. The interconnection of the Pb(II) ions via bridging sulfonate ligands resulted in <100> and <200> layers. In compound 2, one Pb(II) ion is six-coordinated by a carboxylate group bidentately, by two carboxylate groups unidentately, by a sulfonate oxygen atom and by an OH anion, whereas the other one is six-coordinated by a bidentate chelating carboxylate group, two μ3-OH anions, a sulfonate oxygen atom and an aqua ligand. The interconnection of irregular PbO 6 polyhedra via carboxylate-sulfonate ligands resulted in the formation of a pillared layered structure with the 2D layer being formed; the lead(II) ions, hydroxyl groups, carboxylate and sulfonate groups and the benzene ring as the pillar agent.

  2. Carbon dioxide utilization via carbonate-promoted C-H carboxylation

    NASA Astrophysics Data System (ADS)

    Banerjee, Aanindeeta; Dick, Graham R.; Yoshino, Tatsuhiko; Kanan, Matthew W.

    2016-03-01

    Using carbon dioxide (CO2) as a feedstock for commodity synthesis is an attractive means of reducing greenhouse gas emissions and a possible stepping-stone towards renewable synthetic fuels. A major impediment to synthesizing compounds from CO2 is the difficulty of forming carbon-carbon (C-C) bonds efficiently: although CO2 reacts readily with carbon-centred nucleophiles, generating these intermediates requires high-energy reagents (such as highly reducing metals or strong organic bases), carbon-heteroatom bonds or relatively acidic carbon-hydrogen (C-H) bonds. These requirements negate the environmental benefit of using CO2 as a substrate and limit the chemistry to low-volume targets. Here we show that intermediate-temperature (200 to 350 degrees Celsius) molten salts containing caesium or potassium cations enable carbonate ions (CO32-) to deprotonate very weakly acidic C-H bonds (pKa > 40), generating carbon-centred nucleophiles that react with CO2 to form carboxylates. To illustrate a potential application, we use C-H carboxylation followed by protonation to convert 2-furoic acid into furan-2,5-dicarboxylic acid (FDCA)—a highly desirable bio-based feedstock with numerous applications, including the synthesis of polyethylene furandicarboxylate (PEF), which is a potential large-scale substitute for petroleum-derived polyethylene terephthalate (PET). Since 2-furoic acid can readily be made from lignocellulose, CO32--promoted C-H carboxylation thus reveals a way to transform inedible biomass and CO2 into a valuable feedstock chemical. Our results provide a new strategy for using CO2 in the synthesis of multi-carbon compounds.

  3. Carbon dioxide utilization via carbonate-promoted C-H carboxylation.

    PubMed

    Banerjee, Aanindeeta; Dick, Graham R; Yoshino, Tatsuhiko; Kanan, Matthew W

    2016-03-10

    Using carbon dioxide (CO2) as a feedstock for commodity synthesis is an attractive means of reducing greenhouse gas emissions and a possible stepping-stone towards renewable synthetic fuels. A major impediment to synthesizing compounds from CO2 is the difficulty of forming carbon-carbon (C-C) bonds efficiently: although CO2 reacts readily with carbon-centred nucleophiles, generating these intermediates requires high-energy reagents (such as highly reducing metals or strong organic bases), carbon-heteroatom bonds or relatively acidic carbon-hydrogen (C-H) bonds. These requirements negate the environmental benefit of using CO2 as a substrate and limit the chemistry to low-volume targets. Here we show that intermediate-temperature (200 to 350 degrees Celsius) molten salts containing caesium or potassium cations enable carbonate ions (CO3(2-)) to deprotonate very weakly acidic C-H bonds (pKa > 40), generating carbon-centred nucleophiles that react with CO2 to form carboxylates. To illustrate a potential application, we use C-H carboxylation followed by protonation to convert 2-furoic acid into furan-2,5-dicarboxylic acid (FDCA)--a highly desirable bio-based feedstock with numerous applications, including the synthesis of polyethylene furandicarboxylate (PEF), which is a potential large-scale substitute for petroleum-derived polyethylene terephthalate (PET). Since 2-furoic acid can readily be made from lignocellulose, CO3(2-)-promoted C-H carboxylation thus reveals a way to transform inedible biomass and CO2 into a valuable feedstock chemical. Our results provide a new strategy for using CO2 in the synthesis of multi-carbon compounds. PMID:26961655

  4. Carboxylation of Phenols with CO2 at Atmospheric Pressure.

    PubMed

    Luo, Junfei; Preciado, Sara; Xie, Pan; Larrosa, Igor

    2016-05-10

    A convenient and efficient method for the ortho-carboxylation of phenols under atmospheric CO2 pressure has been developed. This method provides an alternative to the previously reported Kolbe-Schmitt method, which requires very high pressures of CO2 . The addition of a trisubstituted phenol has proved essential for the successful carboxylation of phenols with CO2 at standard atmospheric pressure, allowing the efficient preparation of a broad variety of salicylic acids. PMID:26989848

  5. Crystal structures of ethyl 6-(4-methyl-phen-yl)-4-oxo-4H-chromene-2-carboxyl-ate and ethyl 6-(4-fluoro-phen-yl)-4-oxo-4H-chromene-2-carboxyl-ate.

    PubMed

    Gomes, Ligia R; Low, John Nicolson; Fernandes, Carlos; Gaspar, Alexandra; Borges, Fernanda

    2016-01-01

    The crystal structures of two chromone derivatives, viz. ethyl 6-(4-methyl-phen-yl)-4-oxo-4H-chromene-2-carboxyl-ate, C19H16O4, (1), and ethyl 6-(4-fluoro-phen-yl)-4-oxo-4H-chromene-2-carboxyl-ate C18H13FO4, (2), have been determined: (1) crystallizes with two mol-ecules in the asymmetric unit. A comparison of the dihedral angles beween the mean planes of the central chromone core with those of the substituents, an ethyl ester moiety at the 2-position and a para-substituted phenyl ring at the 6-position shows that each mol-ecule differs significantly from the others, even the two independent mol-ecules (a and b) of (1). In all three mol-ecules, the carbonyl groups of the chromone and the carboxyl-ate are trans-related. The supra-molecular structure of (1) involves only weak C-H⋯π inter-actions between H atoms of the substituent phenyl group and the phenyl group, which link mol-ecules into a chain of alternating mol-ecules a and b, and weak π-π stacking inter-actions between the chromone units. The packing in (2) involves C-H⋯O inter-actions, which form a network of two inter-secting ladders involving the carbonyl atom of the carboxyl-ate group as the acceptor for H atoms at the 7-position of the chromone ring and from an ortho-H atom of the exocyclic benzene ring. The carbonyl atom of the chromone acts as an acceptor from a meta-H atom of the exocyclic benzene ring. π-π inter-actions stack the mol-ecules by unit translation along the a axis. PMID:26870574

  6. Copper-Catalyzed Carboxylation of Aryl Iodides with Carbon Dioxide.

    PubMed

    Tran-Vu, Hung; Daugulis, Olafs

    2013-10-01

    A method for carboxylation of aryl iodides with carbon dioxide has been developed. The reaction employs low loadings of copper iodide/TMEDA or DMEDA catalyst, 1 atm of CO2, DMSO or DMA solvent, and proceeds at 25-70 °C. Good functional group tolerance is observed, with ester, bromide, chloride, fluoride, ether, hydroxy, amino, and ketone functionalities tolerated. Additionally, hindered aryl iodides such as iodomesitylene can also be carboxylated. PMID:24288654

  7. Vitamin K-dependent carboxylation of the carboxylase

    PubMed Central

    Berkner, Kathleen L.; Pudota, B. Nirmala

    1998-01-01

    Vitamin K-dependent (VKD) proteins require modification by the VKD-γ-glutamyl carboxylase, an enzyme that converts clusters of glus to glas in a reaction that requires vitamin K hydroquinone, for their activity. We have discovered that the carboxylase also carboxylates itself in a reaction dependent on vitamin K. When pure human recombinant carboxylase was incubated in vitro with 14CO2 and then analyzed after SDS/PAGE, a radiolabeled band corresponding to the size of the carboxylase was observed. Subsequent gla analysis of in vitro-modified carboxylase by base hydrolysis and HPLC showed that all of the radioactivity could be attributed to gla residues. Quantitation of gla, asp, and glu residues indicated 3 mol gla/mol carboxylase. Radiolabeled gla was acid-labile, confirming its identity, and was not observed if vitamin K was not included in the in vitro reaction. Carboxylase carboxylation also was detected in baculovirus(carboxylase)-infected insect cells but not in mock-infected insect cells, which do not express endogenous VKD proteins or carboxylase. Finally, we showed that the carboxylase was carboxylated in vivo. Carboxylase was purified from recombinant carboxylase BHK cells cultured in the presence or absence of vitamin K and analyzed for gla residues. Carboxylation of the carboxylase only was observed with carboxylase isolated from BHK cells cultured in vitamin K, and 3 mol gla/mol carboxylase were detected. Analyses of carboxylase and factor IX carboxylation in vitro suggest a possible role for carboxylase carboxylation in factor IX turnover, and in vivo studies suggest a potential role in carboxylase stability. The discovery of carboxylase carboxylation has broad implications for the mechanism of VKD protein carboxylation and Warfarin-based anti-coagulant therapies that need to be considered both retrospectively and in the future. PMID:9435215

  8. The binding of 3'-N-piperidine-4-carboxyl-3'-deoxy-ara-uridine to ribonuclease A in the crystal.

    PubMed

    Leonidas, Demetres D; Maiti, Tushar Kanti; Samanta, Anirban; Dasgupta, Swagata; Pathak, Tanmaya; Zographos, Spyros E; Oikonomakos, Nikos G

    2006-09-01

    The binding of a moderate inhibitor, 3'-N-piperidine-4-carboxyl-3'-deoxy-ara-uridine, to ribonuclease A has been studied by X-ray crystallography at 1.7A resolution. Two inhibitor molecules are bound in the central RNA binding cavity of RNase A exploiting interactions with residues from peripheral binding sites rather than from the active site of the enzyme. The uracyl moiety of the first inhibitor molecule occupies the purine-preferring site of RNase A, while the rest of the molecule projects to the solvent. The second inhibitor molecule binds with the carboxyl group at the pyrimidine recognition site and the uridine moiety exploits interactions with RNase A residues Lys66, His119 and Asp121. Comparative structural analysis of the 3'-N-piperidine-4-carboxyl-3'-deoxy-ara-uridine complex with other RNase A-ligand complexes provides a structural explanation of its potency. The crystal structure of the RNase A-3'-N-piperidine-4-carboxyl-3'-deoxy-ara-uridine complex provides evidence of a novel ligand-binding pattern in RNase A for 3'-N-aminonucleosides that was not anticipated by modelling studies, while it also suggests ways to improve the efficiency and selectivity of such compounds to develop pharmaceuticals against pathologies associated with RNase A homologues. PMID:16730994

  9. The interaction of Mozobil™ with carboxylates.

    PubMed

    Amendola, Valeria; Bergamaschi, Greta; Fabbrizzi, Luigi; Licchelli, Maurizio; Mangano, Carlo

    2016-01-21

    Mozobil(™) (1,1'-[1,4-phenylenebis(methylene)]bis[1,4,8,11-tetraazacyclotetradecane], 1, also known as JM3100 and AMD 3100) is a specific antagonist of the chemokine coreceptor CXCR4 and favours the mobilisation from the bone marrow of stem cells, which can be used for autologous transplantation. It is believed that the interaction, of both hydrogen bonding and electrostatic nature, involves a partly protonated form of Mozobil(™), LHn(n+) and the COO(-) groups of Asp(171) and Asp(262) residues protruding from the walls of the pocket of the membrane protein CXCR4. We have investigated, through potentiometric titrations in 0.1 M NaNO3 at 25 °C, the interaction equilibria between 1 (L) and linear dicarboxylates A(2-). These studies have demonstrated that the main equilibrium takes place: LH5(5+) + A(2-)⇄ [LH5···A](3+), and that the most stable [LH5···A](3+) complex forms for A(2-) = diphenyl-4,4'-dicarboxylate, whose length matches that of LH5(5+). (1)H NMR titration experiments have shown that in the 7-10 pH interval, LH3(3+), LH2(2+) and LH(+) forms establish π-π interactions with diphenyl-4,4'-dicarboxylate, according to a topological arrangement which excludes the formation of H-bonds. It is finally suggested that, in the pocket of the CXCR4 membrane protein, Mozobil(™) operates as a pentammonium cation, which establishes with carboxylate groups of Asp(171) and Asp(262) strong interactions of hydrogen bonding and electrostatic nature. PMID:26600122

  10. Low-line edge roughness extreme ultraviolet photoresists of organotin carboxylates

    NASA Astrophysics Data System (ADS)

    Del Re, Ryan; Passarelli, James; Sortland, Miriam; Cardineau, Brian; Ekinci, Yasin; Buitrago, Elizabeth; Neisser, Mark; Freedman, Daniel A.; Brainard, Robert L.

    2015-10-01

    Pure thin films of organotin compounds have been lithographically evaluated using extreme ultraviolet lithography (EUVL, 13.5 nm). Twenty compounds of the type R2Sn) were spin-coated from solutions in toluene, exposed to EUV light, and developed in organic solvents. Exposures produced negative-tone contrast curves and dense-line patterns using interference lithography. Contrast-curve studies indicated that the photosensitivity is linearly related to the molecular weight of the carboxylate group bound to tin. Additionally, photosensitivity was found to be linearly related to free radical stability of the hydrocarbon group bound directly to tin (R=phenyl, butyl, and benzyl). Dense-line patterning capabilities varied, but two resists in particular show exceptionally good line edge roughness (LER). A resist composed of an amorphous film of )SnCC)2 (1) achieved 1.4 nm LER at 22-nm half-pitch patterning and a resist composed of )Sn) (2) achieved 1.1 nm LER at 35-nm half-pitch at high exposure doses (600 mJ/cm2). Two photoresists that use olefin-based carboxylates, )SnCCH (3) and )SnCC (4), demonstrated better photospeeds (5 mJ/cm2 and 27 mJ/cm2) but worse LER.

  11. Carboxylated magnetic nanoparticles as MRI contrast agents: Relaxation measurements at different field strengths

    NASA Astrophysics Data System (ADS)

    Jedlovszky-Hajdú, Angéla; Tombácz, Etelka; Bányai, István; Babos, Magor; Palkó, András

    2012-09-01

    At the moment the biomedical applications of magnetic fluids are the subject of intensive scientific interest. In the present work, magnetite nanoparticles (MNPs) were synthesized and stabilized in aqueous medium with different carboxylic compounds (citric acid (CA), polyacrylic acid (PAA), and sodium oleate (NaOA)), in order to prepare well stabilized magnetic fluids (MFs). The magnetic nanoparticles can be used in the magnetic resonance imaging (MRI) as contrast agents. Magnetic resonance relaxation measurements of the above MFs were performed at different field strengths (i.e., 0.47, 1.5 and 9.4 T) to reveal the field strength dependence of their magnetic responses, and to compare them with that of ferucarbotran, a well-known superparamagnetic contrast agent. The measurements showed characteristic differences between the tested magnetic fluids stabilized by carboxylic compounds and ferucarbotran. It is worthy of note that our magnetic fluids have the highest r2 relaxivities at the field strength of 1.5 T, where the most of the MRI works in worldwide.

  12. n-Octyl gallate as inhibitor of pyruvate carboxylation and lactate gluconeogenesis.

    PubMed

    Eler, Gabrielle Jacklin; Santos, Israel Souza; de Moraes, Amarilis Giaretta; Comar, Jurandir Fernando; Peralta, Rosane Marina; Bracht, Adelar

    2015-04-01

    The alkyl gallates are found in several natural and industrial products. In the latter products, these compounds are added mainly for preventing oxidation. In the present work, the potencies of methyl gallate, n-propyl gallate, n-pentyl gallate, and n-octyl gallate as inhibitors of pyruvate carboxylation and lactate gluconeogenesis were evaluated. Experiments were done with isolated mitochondria and the isolated perfused rat liver. The potency of the gallic acid esters as inhibitors of pyruvate carboxylation in isolated mitochondria obeyed the following decreasing sequence: n-octyl gallate > n-pentyl gallate > n-propyl gallate > methyl gallate. A similar sequence of decreasing potency for lactate gluconeogenesis inhibition in the perfused liver was found in terms of the portal venous concentration. Both actions correlate with the lipophilicity of the compounds. The effects are harmful at high concentrations. At appropriate concentrations, however, octyl gallate should act therapeutically because its inhibitory action on gluconeogenesis will contribute further to its proposed antihyperglycemic effects. PMID:25487712

  13. Penarines A-F, (nor-)sesquiterpene carboxylic acids from Hygrophorus penarius (Basidiomycetes).

    PubMed

    Otto, Alexander; Porzel, Andrea; Schmidt, Jürgen; Wessjohann, Ludger; Arnold, Norbert

    2014-12-01

    Five sesquiterpene carboxylic acids (1-5) and one nor-sesquiterpene carboxylic acid (6) of the very rare ventricosane type, named penarines A-F, were isolated from fruiting bodies of the basidiomycete Hygrophorus penarius (Hygrophoraceae). This is the first report of (nor)-sesquiterpenes isolated from basidiocarps of the family Hygrophoraceae. Their structures were elucidated on the basis of extensive 1D ((1)H, (13)C) and 2D (HSQC, HMBC, COSY, ROESY) NMR spectroscopic analyses as well as high-resolution mass spectrometry studies. Additionally, the only known member of this rare type of sesquiterpenes, ventricos-7(13)-ene (7), could be identified via headspace GC-MS analysis in a fruiting body of H. penarius. Compounds 1-6 were devoid of remarkable antifungal activity against Cladosporium cucumerinum. Additionally, the cytotoxic activities of compounds 1 and 2 were evaluated against the human prostate cancer cell line PC-3 and the colon cancer cell line HT-29 showing no significant cytotoxic activity. PMID:25269661

  14. Environmentally benign graphite intercalation compound composition for exfoliated graphite, flexible graphite, and nano-scaled graphene platelets

    DOEpatents

    Zhamu, Aruna; Jang, Bor Z.

    2014-06-17

    A carboxylic-intercalated graphite compound composition for the production of exfoliated graphite, flexible graphite, or nano-scaled graphene platelets. The composition comprises a layered graphite with interlayer spaces or interstices and a carboxylic acid residing in at least one of the interstices, wherein the composition is prepared by a chemical oxidation reaction which uses a combination of a carboxylic acid and hydrogen peroxide as an intercalate source. Alternatively, the composition may be prepared by an electrochemical reaction, which uses a carboxylic acid as both an electrolyte and an intercalate source. Exfoliation of the invented composition does not release undesirable chemical contaminants into air or drainage.

  15. Bis(9-allyl-6-carb­oxy-9H-carbazole-3-carboxyl­ato-κ2 O 3,O 3′)diaqua­zinc

    PubMed Central

    Li, Dailin

    2012-01-01

    In the title compound, [Zn(C17H12NO4)2(H2O)2], the ZnII atom is located on a twofold rotation axis and is six-coordinated by four carboxyl­ate O atoms from two chelating 9-allyl-6-carb­oxy-9H-carbazole-3-carboxyl­ate ligands and two O atoms from two water mol­ecules. In the crystal, O—H⋯O hydrogen bonds link the mol­ecules into a layer structure parallel to (-101). PMID:23468689

  16. Design, Synthesis and Antibacterial Evaluation of Some New 2-Phenyl-quinoline-4-carboxylic Acid Derivatives.

    PubMed

    Wang, Xiaoqin; Xie, Xiaoyang; Cai, Yuanhong; Yang, Xiaolan; Li, Jiayu; Li, Yinghan; Chen, Wenna; He, Minghua

    2016-01-01

    A series of new 2-phenyl-quinoline-4-carboxylic acid derivatives was synthesized starting from aniline, 2-nitrobenzaldehyde, pyruvic acid followed by Doebner reaction, amidation, reduction, acylation and amination. All of the newly-synthesized compounds were characterized by ¹H-NMR, (13)C-NMR and HRMS. The antibacterial activities of these compounds against Gram-negative (Escherichia coli, Pseudomonas aeruginosa) and Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis), as well as one strain of methicillin-resistant Staphylococcus aureus (MRSA) bacteria were evaluated by the agar diffusion method (zone of inhibition) and a broth dilution method (minimum inhibitory concentration (MIC)), and their structure-activity relationships were obtained and discussed. The results revealed that some compounds displayed good antibacterial activity against Staphylococcus aureus, and Compounds 5a₄ and 5a₇ showed the best inhibition with an MIC value of 64 μg/mL against Staphylococcus aureus and with an MIC value of 128 μg/mL against Escherichia coli, respectively. The results of the MTT assay illustrated the low cytotoxicity of Compound 5a₄. PMID:26978336

  17. Solid phase extraction of petroleum carboxylic acids using a functionalized alumina as stationary phase.

    PubMed

    de Conto, Juliana Faccin; Nascimento, Juciara dos Santos; de Souza, Driele Maiara Borges; da Costa, Luiz Pereira; Egues, Silvia Maria da Silva; Freitas, Lisiane Dos Santos; Benvenutti, Edilson Valmir

    2012-04-01

    Petroleum essentially consists of a mixture of organic compounds, mainly containing carbon and hydrogen, and, in minor quantities, compounds with nitrogen, sulphur, and oxygen. Some of these compounds, such as naphthenic acids, can cause corrosion in pipes and equipment used in processing plants. Considering that the methods of separation or clean up the target compounds in low concentrations and in complex matrix use large amounts of solvents or stationary phases, is necessary to study new methodologies that consume smaller amounts of solvent and stationary phases to identify the acid components present in complex matrix, such as crude oil samples. The proposed study aimed to recover acid compounds using the solid phase extraction method, employing different types of commercial stationary ion exchange phases (SAX and NH(2)) and new phase alumina functionalized with 1,4-bis(n-propyl)diazoniabicyclo[2.2.2]octane chloride silsesquioxane (Dab-Al(2)O(3)), synthesized in this work. Carboxylic acids were used as standard mixture in the solid phase extraction for further calculation of recovery yield. Then, the real sample (petroleum) was fractionated into saturates, aromatics, resins, and asphaltenes, and the resin fraction of petroleum (B1) was eluted through stationary ion exchange phases. The stationary phase synthesized in this work showed an efficiency of ion exchange comparable to that of the commercial stationary phases. PMID:22589166

  18. Poly[aqua­(μ-pyrazine-2-carboxyl­ato-κ3 N,O:O)(μ-pyrazine-2-carboxyl­ato-κ3 N,O:O′)lead(II)

    PubMed Central

    Starosta, Wojciech; Leciejewicz, Janusz

    2010-01-01

    The polymeric structure of the title compound, [Pb(C5H3N2O2)2(H2O)]n, is built up from centrosymmetric [Pb(C5H3N2O2)2(H2O)]2 dimers, which are bridged by ligand carboxyl­ate O atoms. The PbII ion adopts an irregular PbN2O5 coordination polyhedron; it is chelated by one N,O-bidentate ligand and also bonds to a water O atom. A second N,O-bidentate ligand forms the dimer bridge and another bridging O atom from a nearby dimer also bonds to the PbII ion, leading to layers propagating in (100). A network of O—H⋯O hydrogen bonds operates between water O atoms (donors) and carboxyl­ate O atoms (acceptors). PMID:21579020

  19. Crystal structure of ethyl 4-(2,4-di-chloro-phen-yl)-2-methyl-4H-benzo[4,5]thia-zolo[3,2-a]pyrimidine-3-carboxyl-ate.

    PubMed

    Sankar, T; Naveen, S; Lokanath, N K; Gunasekaran, K

    2015-05-01

    In the title compound, C20H16Cl2N2O2S, the pyrimidine ring has a screw-boat conformation. The attached di-chloro-phenyl ring is twisted at an angle of 89.29 (13)° with respect to the pyrimidine ring mean plane. The benzo-thia-zole group is approximately planar (r.m.s. deviation = 0.008 Å) and inclined to the pyrimidine ring mean plane by 3.04 (10)°. The carboxyl-ate group assumes an extended conformation with respect to the pyrimidine ring, which can be seen from the O=C-O-C torsion angle of 3.2 (4) °. In the crystal, mol-ecules are linked via C-H⋯O and C-H⋯N hydrogen bonds, forming slabs lying parallel to (100). PMID:25995918

  20. Hydrothermal synthesis of two copper helical coordination polymers with acentric three-dimensional framework constructing from mixed pyridine carboxylates

    SciTech Connect

    Zhang Shuai; Cao Yanning; Zhang Hanhui Chai Xiaochuan; Chen Yiping

    2008-03-15

    Two copper helical coordination polymers, [Cu(2-pc)(3-pc)]{sub n}1 and [Cu(2-pc)(4-pc)]{sub n}2 (2-pc=2-pyridine carboxylate, 3-pc=3-pyridine carboxylate, 4-pc=4-pyridine carboxylate) have been hydrothermally synthesized directly from pyridine carboxylic acids and copper nitrate. The crystal structure were determined by single-crystal X-ray diffraction with the following data: compound 1, orthorhombic, P2{sub 1}2{sub 1}2{sub 1}, a=6.591(3) A, b=8.692(5) A, c=20.548(9) A, V=1177.2(9) A{sup 3}, Z=4; compound 2, orthorhombic, Pna2{sub 1}, a=21.160(10) A, b=9.095(5) A, c=6.401(3) A, V=1231.9(11) A{sup 3}, Z=4. The acentric three-dimensional (3D) framework of 1 is constructed from right-handed helical Cu(2-pc) chains and left-handed Cu(3-pc) helices. As for 2, Cu(2-pc) helical chains, in which left- and right-handed helices are coexisting, and Cu(4-pc) zigzag chains combined together to form acentric 3D architecture of 2 as well. Additionally, besides general spectral characterization, we first introduce generalized 2D correlation spectroscopy to explore the coordination polymers and ascertain the stretching vibration location of carboxylate groups of compounds 1 and 2. -- Abstract: Two copper helical coordination polymers, [Cu(2-pc)(3-pc)]{sub n}1 and [Cu(2-pc)(4-pc)]{sub n}2 have been obtained by hydrothermal synthesis. Both two compounds crystallized in non-centrosymmetric space groups, P2{sub 1}2{sub 1}2{sub 1} and Pna2{sub 1}, respectively. The 3D framework of 1 is constructed from right-handed helical Cu(2-pc) chains and left-handed Cu(3-pc) helices. As for 2, Cu(2-pc) helical chains, in which left- and right-handed helices are coexisting, and Cu(4-pc) zigzag chains combined together to form 3D architecture of 2 as well.

  1. Carboxylated, heteroaryl-substituted chalcones as inhibitors of vascular cell adhesion molecule-1 expression for use in chronic inflammatory diseases.

    PubMed

    Meng, Charles Q; Ni, Liming; Worsencroft, Kimberly J; Ye, Zhihong; Weingarten, M David; Simpson, Jacob E; Skudlarek, Jason W; Marino, Elaine M; Suen, Ki-Ling; Kunsch, Charles; Souder, Amy; Howard, Randy B; Sundell, Cynthia L; Wasserman, Martin A; Sikorski, James A

    2007-03-22

    Starting from a simple chalcone template, structure-activity relationship (SAR) studies led to a series of carboxylated, heteroaryl-substituted chalcone derivatives as novel, potent inhibitors of vascular cell adhesion molecule-1 (VCAM-1) expression. Correlations between lipophilicity determined by calculated logP values and inhibitory efficacy were observed among structurally similar compounds of the series. Various substituents were found to be tolerated at several positions of the chalcone backbone as long as the compounds fell into the right range of lipophilicity. The chalcone alpha,beta-unsaturated ketone moiety seemed to be the pharmacophore required for inhibition of VCAM-1 expression. Compound 19 showed significant antiinflammatory effects in a mouse model of allergic inflammation, indicating that this series of compounds might have therapeutic value for human asthma and other inflammatory disorders. PMID:17323940

  2. Carboxyl group participation in sulfate and sulfamate group transfer reactions

    SciTech Connect

    Hopkins, A.; Williams, A.

    1982-04-23

    The pH dependence for the hydrolysis of N-(2-carboxyphenyl)sulfamic acid exhibits a plateau region corresponding to participation of the carboxyl function. A normal deuterium oxide solvent isotope effect indicates that proton transfer from the carboxylic acid is concerted with sulfamate group transfer to water. Hydrolysis of salicylic sulfate and N-(2-carboxyphenyl)sulfamate in /sup 18/O-enriched water yields salicylic acid and anthranilic acids with no enrichment, excluding catalysis by neighboring nucleophilic attack on sulfur by the carboxylate group. Intermolecular catalysis by carboxylic acids is demonstrated in the hydrolysis of N-(1-naphthyl)sulfamic acid; the mechanism is shown to involve preequilibrium protonation of the nitrogen followed by nucleophilic attack on sulfur by the carboxylate anion. Fast decomposition of the acyl sulfate completes the hydrolysis; this mechanism is considered to be the most efficient but is excluded in the intramolecular case which is constrained by the electronic requirements of displacement at the sulfur atom (6-ENDO-tet).

  3. Design, Synthesis, and Fungicidal Activities of Novel 5-Methyl-1H-1,2,3- trizole-4-carboxyl Amide Analogues.

    PubMed

    Wang, Zhen-Jun; Yang, Hui-Hui; Tian, Lei; Zhao, Wei-Guang

    2016-01-01

    Succinate dehydrogenase inhibitors (SDHIs) are fungicides with an amide bond widely used to control plant diseases caused by phytopathogenic fungi. Because of broad spectrum activity of new SDHIs, they have attracted wide attention from the research community. A series of structurally novel SDHIs with a bioactive 1,2,3-triazole moiety were designed and synthesized. Bioactivity screening showed that some of designed N-phenethyl-1,2,3-trizole-4-carboxyl amide analogues exhibited good fungicidal activities toward Sclerotinia sclerotiorum and Botrytis cinerea, while some of Nbenzyl- 1,2,3-trizole-4-carboxyl amide analogues exhibited good fungicidal activities toward Phytophthora capsici and Cercospora arachidicola. EC50 value of compound 5d against Cercospora arachidicola (6.6 µg/mL) was lower than that of chlorothalonil (12.3 µg/mL). PMID:26558376

  4. Formation of aldehydes and carboxylic acids in ozonated surface water and wastewater: a clear relationship with fluorescence changes.

    PubMed

    Liu, Chen; Tang, Xiangyu; Kim, Jaeshin; Korshin, Gregory V

    2015-04-01

    This study examined the formation of aldehydes and carboxylic acids in ozonated surface water and municipal wastewater secondary effluent and addressed correlations between the generation of these compounds and concurrent changes of the fluorescence of natural/effluent organic matter (NOM/EfOM) substrates. Ozonation was effective in removing fluorophores in all excitation/emission matrix (EEM) regions, with those operationally assigned to humic- and protein-like species showing relatively higher reactivity than fulvic-like species. Examination of HO exposures and attendant changes of fluorescence-based parameters allows establishing strong linear relationships between formation of the aldehydes and carboxylic acids and the relative changes of integrated fluorescence (ΔIF/IF0). This demonstrates the feasibility of surrogate monitoring of the formation of biodegradable ozonation by-products via online measurements of water/wastewater EEM fluorescence. PMID:25576127

  5. Strong-acid, carboxyl-group structures in fulvic acid from the Suwannee River, Georgia. 2. Major structures

    USGS Publications Warehouse

    Leenheer, J.A.; Wershaw, R. L.; Reddy, M.M.

    1995-01-01

    Polycarboxylic acid structures that account for the strong-acid characteristics (pKa1 near 2.0) were examined for fulvic acid from the Suwannee River. Studies of model compounds demonstrated that pKa values near 2.0 occur only if the ??-ether or ??-ester groups were in cyclic structures with two to three additional electronegative functional groups (carboxyl, ester, ketone, aromatic groups) at adjacent positions on the ring. Ester linkage removal by alkaline hydrolysis and destruction of ether linkages through cleavage and reduction with hydriodic acid confirmed that the strong carboxyl acidity in fulvic acid was associated with polycarboxylic ??-ether and ??-ester structures. Studies of hypothetical structural models of fulvic acid indicated possible relation of these polycarboxylic structures with the amphiphilic and metal-binding properties of fulvic acid.

  6. Silylesterification of oxidized multi-wall carbon nanotubes by catalyzed dehydrogenative cross-coupling between carboxylic and hydrosilane functions

    NASA Astrophysics Data System (ADS)

    Seffer, J.-F.; Detriche, S.; Nagy, J. B.; Delhalle, J.; Mekhalif, Z.

    2014-06-01

    Surface modification of oxidized carbon nanotubes (O-CNTs) with silicon based anchoring groups (R-SiR3) is a relatively uncommon approach of the CNTs functionalization. Hydrosilane derivatives constitute an attractive subclass of compounds for silanization reactions on the CNTs surface. In this work, we report on the ZnCl2 catalytically controlled reaction (hydrosilane dehydrogenative cross-coupling, DHCC) of fluorinated hydrosilane probes with the carboxylic functions present on the surface of oxidized multi-wall carbon nanotubes. Carbon nanotubes functionalized with essentially alcohol groups are also used to compare the selectivity of zinc chloride toward carboxylic groups. To assess the efficiency of functionalization, X-ray Photoelectron Spectroscopy is used to determine the qualitative and quantitative composition of the different samples. Solubility tests on the oxidized and silanized MWNTs are also carried out in the framework of the Hansen Solubility Parameters (HSP) theory to apprehend at another scale the effect of DHCC.

  7. Diaqua-bis-(1H-imidazole-4-carboxyl-ato-κ(2) N (3),O (4))manganese(II).

    PubMed

    Xiong, Zhi-Yong; Li, Lin; Zhao, Xiang-Jie; Chen, Hai-Ming

    2013-03-01

    In the title compound, [Mn(C4H3N2O2)2(H2O)2], the Mn(II) ion is located on a twofold rotation axis and displays a distorted octa-hedral coordination environment, defined by two N,O-bidentate 1H-imidazole-4-carboxyl-ate ligands in the equatorial plane and two water mol-ecules in axial positions. In the crystal, O-H⋯O and N-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional supra-molecular network. π-π stacking inter-actions between the imidazole rings [centroid-centroid distances = 3.5188 (15) and 3.6687 (15) Å] further stabilize the structure. PMID:23476512

  8. Lanthanum(III)-Catalyzed Three-Component Reaction of Coumarin-3-carboxylates for the Synthesis of Indolylmalonamides and Analysis of Their Photophysical Properties.

    PubMed

    Jennings, Julia J; Bhatt, Chinmay P; Franz, Annaliese K

    2016-08-01

    New methodology has been developed for the Lewis acid catalyzed synthesis of malonamides. First, the scandium(III)-catalyzed addition of diverse nucleophiles (e.g., indoles, N,N-dimethyl-m-anisidine, 2-ethylpyrrole, and 2-methylallylsilane) to coumarin-3-carboxylates has been developed to afford chromanone-3-carboxylates in high yields as a single diastereomer. Upon investigating a subsequent lanthanum(III)-catalyzed amidation reaction, a new multicomponent reaction was designed by bringing together coumarin-3-carboxylates with indoles and amines to afford indolylmalonamides, which were identified to exhibit fluorescent properties. The photophysical properties for selected compounds have been analyzed, including quantum yield, molar absorptivity, and Stokes shift. Synthetic studies of several reaction byproducts involved in the network of reaction equilibria for the three-component reaction provide mechanistic insight for the development of this methodology. PMID:27304909

  9. Carboxylic acids in secondary aerosols from oxidation of cyclic monoterpenes by ozone

    SciTech Connect

    Glasius, M.; Lahaniati, M.; Calogirou, A.; Di Bella, D.; Jensen, N.R.; Hjorth, J.; Kotzias, D.; Larsen, B.R.

    2000-03-15

    A series of smog chamber experiments have been conducted in which five cyclic monoterpenes were oxidized by ozone. The evolved secondary aerosol was analyzed by GC-MS and HPLC-MS for nonvolatile polar oxidation products with emphasis on the identification of carboxylic acids. Three classes of compounds were determined at concentration levels corresponding to low percentage molar yields: i.e., dicarboxylic acids, oxocarboxylic acids, and hydroxyketocarboxylic acids. Carboxylic acids are highly polar and have lower vapor pressures than their corresponding aldehydes and may thus play an important role in secondary organic aerosol formation processes. The most abundant carboxylic acids were the following: cis-pinic acid AB1(cis-3-carboxy-2,2-dimethylcyclobutylethanoic acid) from {alpha} and {beta}-pinene; cis-pinonic acid A3 (cis-3-acetyl-2,2-dimethylcyclobutylethanoic acid) and cis-10-hydroxypinonic acid Ab6 (cis-2,2-dimethyl-3-hydroxyacetylcyclobutyl-ethanoic acid) from {alpha}-pinene and {beta}-pinene; cis-3-caric acid C1 (cis-2,2-dimethyl-1,3-cyclopropyldiethanoic acid), cis-3-caronic acid C3 (2,2-dimethyl-3-(2-oxopropyl)cyclopropanylethanoic acid), and cis-10-hydroxy-3-caronic acid C6 (cis-2,2-dimethyl-3(hydroxy-2-oxopropyl)cyclopropanylethanoic acid) from 3-carene; cis-sabinic acid S1 (cis-2-carboxy-1-isopropylcyclopropylethanoic acid) from sabinene; limonic acid L1 (3-isopropenylhexanedioic acid), limononic acid L3 (3-isopropenyl-6-oxo-heptanoic acid), 7-hydroxy-limononic acid L6 (3-isopropenyl-7-hydroxy-6-oxoheptanoic acid), and 7-hydroxylimononic acid Lg{prime} (7-hydroxy-3-isopropenyl-6-oxoheptanoic acid) from limonene.

  10. Reversible phase transition of 2-carboxypyridinium perchlorate-pyridinium-2-carboxylate (1/1).

    PubMed

    Wang, Bi-Qin; Yan, Hai-Biao; Huang, Zheng-Qing; Zhang, Yun-Hua; Sun, Jing

    2015-04-01

    The title salt, C6H6NO2(+)·ClO4(-)·C6H5NO2, was crystallized from an aqueous solution of equimolar quantities of perchloric acid and pyridine-2-carboxylic acid. Differential scanning calorimetry (DSC) measurements show that the compound undergoes a reversible phase transition at about 261.7 K, with a wide heat hysteresis of 21.9 K. The lower-temperature polymorph (denoted LT; T = 223 K) crystallizes in the space group C2/c, while the higher-temperature polymorph (denoted RT; T = 296 K) crystallizes in the space group P2/c. The relationship between these two phases can be described as: 2a(RT) = a(LT); 2b(RT) = b(LT); c(RT) = c(LT). The crystal structure contains an infinite zigzag hydrogen-bonded chain network of 2-carboxypyridinium cations. The most distinct difference between the higher (RT) and lower (LT) temperature phases is the change in dihedral angle between the planes of the carboxylic acid group and the pyridinium ring, which leads to the formation of different ten-membered hydrogen-bonded rings. In the RT phase, both the perchlorate anions and the hydrogen-bonded H atom within the carboxylic acid group are disordered. The disordered H atom is located on a twofold rotation axis. In the LT phase, the asymmetric unit is composed of two 2-carboxypyridinium cations, half an ordered perchlorate anion with ideal tetrahedral geometry and a disordered perchlorate anion. The phase transition is attributable to the order-disorder transition of half of the perchlorate anions. PMID:25836279

  11. Benzothiophene carboxylate derivatives as novel allosteric inhibitors of branched-chain α-ketoacid dehydrogenase kinase.

    PubMed

    Tso, Shih-Chia; Gui, Wen-Jun; Wu, Cheng-Yang; Chuang, Jacinta L; Qi, Xiangbing; Skvora, Kristen J; Dork, Kenneth; Wallace, Amy L; Morlock, Lorraine K; Lee, Brendan H; Hutson, Susan M; Strom, Stephen C; Williams, Noelle S; Tambar, Uttam K; Wynn, R Max; Chuang, David T

    2014-07-25

    The mitochondrial branched-chain α-ketoacid dehydrogenase complex (BCKDC) is negatively regulated by reversible phosphorylation.BCKDC kinase (BDK) inhibitors that augment BCKDC flux have been shown to reduce branched-chain amino acid (BCAA) concentrations in vivo. In the present study, we employed high-throughput screens to identify compound 3,6- dichlorobenzo[b]thiophene-2-carboxylic acid (BT2) as a novel BDK inhibitor (IC(50) = 3.19 μM). BT2 binds to the same site in BDK as other known allosteric BDK inhibitors, including (S)-α-cholorophenylproprionate ((S)-CPP). BT2 binding to BDK triggers helix movements in the N-terminal domain, resulting in the dissociation of BDK from the BCKDC accompanied by accelerated degradation of the released kinase in vivo. BT2 shows excellent pharmacokinetics (terminal T(1⁄2) = 730 min) and metabolic stability (no degradation in 240 min), which are significantly better than those of (S)-CPP. BT2, its analog 3-chloro-6-fluorobenzo[ b]thiophene-2-carboxylic acid (BT2F), and a prodrug of BT2 (i.e. N-(4-acetamido-1,2,5-oxadiazol-3-yl)-3,6-dichlorobenzo[ b]thiophene-2-carboxamide (BT3)) significantly increase residual BCKDC activity in cultured cells and primary hepatocytes from patients and a mouse model of maple syrup urine disease. Administration of BT2 at 20 mg/kg/day to wild-type mice for 1 week leads to nearly complete dephosphorylation and maximal activation of BCKDC in heart, muscle, kidneys, and liver with reduction in plasma BCAA concentrations. The availability of benzothiophene carboxylate derivatives as stable BDK inhibitors may prove useful for the treatment of metabolic disease caused by elevated BCAA concentrations. PMID:24895126

  12. Binding properties of solubilized gonadotropin-releasing hormone receptor: role of carboxylic groups

    SciTech Connect

    Hazum, E.

    1987-11-03

    The interaction of /sup 125/I-buserelin, a superactive agonist of gonadotropin-releasing hormone (GnRH), with solubilized GnRH receptor was studied. The highest specific binding of /sup 125/I-buserelin to solubilized GnRH receptor is evident at 4/sup 0/C, and equilibrium is reached after 2 h of incubation. The soluble receptor retained 100% of the original binding activity when kept at 4 or 22/sup 0/C for 60 min. Mono- and divalent cations inhibited, in a concentration-dependent manner, the binding of /sup 125/I-buserelin to solubilized GnRH receptor. Monovalent cations require higher concentrations than divalent cations to inhibit the binding. Since the order of potency with the divalent cations was identical with that of their association constants to dicarboxylic compounds, it is suggested that there are at least two carboxylic groups of the receptor that participate in the binding of the hormone. The carboxyl groups of sialic acid residues are not absolutely required for GnRH binding since the binding of /sup 125/I-buserelin to solubilized GnRH receptor was only slightly affected by pretreatment with neuraminidase and wheat germ agglutinin. The finding that polylysines stimulate luteinizing hormone (LH) release from pituitary cell cultures with the same efficacy as GnRH suggest that simple charge interactions can induce LH release. According to these results, the authors propose that the driving force for the formation of the hormone-receptor complex is an ionic interaction between the positively charged amino acid arginine in position 8 and the carboxyl groups in the binding site.

  13. Carboxylate-intercalated layered double hydroxides aged under microwave-hydrothermal treatment

    SciTech Connect

    Benito, P.; Labajos, F.M.; Mafra, L.; Rocha, J.; Rives, V.

    2009-01-15

    Carboxylate-intercalated (terephthalate, TA and oxalate, ox) layered double hydroxides (LDHs) are aged under a microwave-hydrothermal treatment. The influence of the nature of the interlayer anion during the ageing process is studied. Characterization results show that the microwave-hydrothermal method can be extended to synthesize LDHs with anions different than carbonate, like TA. LDH-TA compounds are stable under microwave irradiation for increasing periods of time and the solids show an improved order both in the layers and in the interlayer region as evidenced by powder X-ray diffraction (PXRD), {sup 27}Al MAS NMR and FT-IR spectroscopy. Furthermore, cleaning of the surface through removal of some organic species adsorbed on the surface of the particles also occurs during the microwave-hydrothermal treatment. Conversely, although the expected increase in crystallinity is observed in LDH-ox samples, the side-reaction between Al{sup 3+} and ox is also enhanced under microwave irradiation, and a partial destruction of the structure takes place with an increase in the M{sup 2+}/M{sup 3+} ratio and consequent modification of the cell parameters. - Graphical Abstract: The influence of the nature of the interlayer anion during the ageing process of carboxylate-intercalated (TA and ox) hydrotalcite-like compounds (HTlcs) is studied. Well crystallized for TA-containing compounds were obtained. However, the non-desired side-reaction of ox with the aluminum of the layers is enhanced by the microwaves and a partial destruction of the structure takes place.

  14. Octyl and nonylphenol ethoxylates and carboxylates in wastewater and sediments by liquid chromatography/tandem mass spectrometry.

    PubMed

    Loyo-Rosales, Jorge E; Rice, Clifford P; Torrents, Alba

    2007-08-01

    This work presents an LC-MS-MS-based method for the quantitation of nonylphenol ethoxylates (NPEOs) and octylphenol ethoxylates (OPEOs) in water, sediment, and suspended particulate matter, and three of their carboxylated derivatives in water. The alkylphenol ethoxylates (APEOs) were analyzed using isotope dilution mass spectrometry with [(13)C(6)]-labeled analogues, whereas the carboxylated derivatives were determined by external standard quantitation followed by confirmation using standard additions. The method was used to study APEO's behavior in a wastewater treatment plant (WWTP), where total dissolved NP0-16EO concentration was reduced by approximately 99% from influent (390 microg l(-1)) to final effluent (4 microg l(-1)), and total OP0-5EO concentration decreased by 94% from 3.1 to 0.2 microg l(-1). In contrast, the carboxylated derivatives were formed during the process with NP0-1EC concentrations increasing from 1.4 to 24 microg l(-1). Short-chain APEOs were present in higher proportions in particulate matter, presumably due to greater affinity for solids compared to the long-chain homologues. NP (0.49 microg l(-1)) and NP0-1EC (4.8 microg l(-1)) were the only APEO-related compounds detected in a surface water sample from a WWTP-impacted estuary; implying that 90% of the mass was in the form of carboxylated derivatives. Sediment analysis showed nonylphenol to be the single most abundant compound in sediments from the Baltimore Harbor area, where differences in homologue distribution suggested the presence of treated effluent in some of the sites and non-treated sources in the rest. PMID:17395243

  15. Gas Phase Reactivity of Carboxylates with N-Hydroxysuccinimide Esters

    NASA Astrophysics Data System (ADS)

    Peng, Zhou; McGee, William M.; Bu, Jiexun; Barefoot, Nathan Z.; McLuckey, Scott A.

    2015-01-01

    N-hydroxysuccinimide (NHS) esters have been used for gas-phase conjugation reactions with peptides at nucleophilic sites, such as primary amines (N-terminus, ɛ-amine of lysine) or guanidines, by forming amide bonds through a nucleophilic attack on the carbonyl carbon. The carboxylate has recently been found to also be a reactive nucleophile capable of initiating a similar nucleophilic attack to form a labile anhydride bond. The fragile bond is easily cleaved, resulting in an oxygen transfer from the carboxylate-containing species to the reagent, nominally observed as a water transfer. This reactivity is shown for both peptides and non-peptidic species. Reagents isotopically labeled with O18 were used to confirm reactivity. This constitutes an example of distinct differences in reactivity of carboxylates between the gas phase, where they are shown to be reactive, and the solution phase, where they are not regarded as reactive with NHS esters.

  16. Separation of certain carboxylic acids utilizing cation exchange membranes

    DOEpatents

    Chum, Helena L.; Sopher, David W.

    1984-01-01

    A method of substantially separating monofunctional lower carboxylic acids from a liquid mixture containing the acids wherein the pH of the mixture is adjusted to a value in the range of from about 1 to about 5 to form protonated acids. The mixture is heated to an elevated temperature not greater than about 100.degree. C. and brought in contact with one side of a perfluorinated cation exchange membrane having sulfonate or carboxylate groups or mixtures thereof with the mixture containing the protonated acids. A pressure gradient can be established across the membrane with the mixture being under higher pressure, so that protonated monofunctional lower carboxylic acids pass through the membrane at a substantially faster rate than the remainder of the mixture thereby substantially separating the acids from the mixture.

  17. Separation of certain carboxylic acids utilizing cation exchange membranes

    DOEpatents

    Chum, H.L.; Sopher, D.W.

    1983-05-09

    A method of substantially separating monofunctional lower carboxylic acids from a liquid mixture containing the acids wherein the pH of the mixture is adjusted to a value in the range of from about 1 to about 5 to form protonated acids. The mixture is heated to an elevated temperature not greater than about 100/sup 0/C and brought in contact with one side of a perfluorinated cation exchange membrane having sulfonate or carboxylate groups or mixtures thereof with the mixture containing the protonated acids. A pressure gradient can be established across the membrane with the mixture being under higher pressure, so that protonated monofunctional lower carboxylic acids pass through the membrane at a substantially faster rate than the remainder of the mixture thereby substantially separating the acids from the mixture.

  18. Production of carboxylates from high rate activated sludge through fermentation.

    PubMed

    Cagnetta, C; Coma, M; Vlaeminck, S E; Rabaey, K

    2016-10-01

    The aim of this work was to study the key parameters affecting fermentation of high rate activated A-sludge to carboxylates, including pH, temperature, inoculum, sludge composition and iron content. The maximum volatile fatty acids production was 141mgCg(-1) VSSfed, at pH 7. Subsequently the potential for carboxylate and methane production for A-sludge from four different plants at pH 7 and 35°C were compared. Initial BOD of the sludge appeared to be key determining carboxylate yield from A-sludge. Whereas methanogenesis could be correlated linearly to the quantity of ferric used for coagulation, fermentation did not show a dependency on iron presence. This difference may enable a strategy whereby A-stage sludge is separated to achieve fermentation, and iron dosing for phosphate removal is only implemented at the B-stage. PMID:27020399

  19. Novel polycarbo-substituted alkyl (thieno[3,2-c]quinoline)-2-carboxylates: synthesis and cytotoxicity studies.

    PubMed

    Mphahlele, Malose Jack; Maluleka, Marole Maria; Makhafola, Tshepiso Jan; Mabeta, Peace

    2014-01-01

    Direct one-pot base-promoted conjugate addition-elimination of 6,8-dibromo-4-chloroquinoline-3-carbaldehyde with methyl mercaptoacetate and subsequent cyclization afforded methyl [(6,8-dibromothieno[3,2-c]quinoline)]-2-carboxylate. The latter undergoes Suzuki-Miyaura cross-coupling with arylboronic acids to yield exclusively the corresponding alkyl [(6,8-diarylthieno[3,2-c]quinoline)]-2-carboxylates,. The cytotoxicity of the prepared compounds was evaluated against the human breast cancer cell line MCF-7 using the MTT assay. The effects of compounds 2, 3c and 4d on cell kinetics were further determined using the xCELLigence Real Time Cell Analysis (RTCA) system. In both the MTT assay and Real Time Cell Analysis, the compounds inhibited cancer cell growth in a dose- and time-dependent manner. Furthermore, on the basis of the calculated LC50 values, the compounds compared favourably with nocodazole, a well-established anticancer drug. PMID:25401397

  20. The interaction of carboxylic acids with aluminium oxides: journeying from a basic understanding of alumina nanoparticles to water treatment for industrial and humanitarian applications.

    PubMed

    Barron, Andrew R

    2014-06-14

    Carboxylic acids are found to react with aluminium oxides via a topotactic reaction such that the carboxylate acts as a bridging ligand. This reaction allows for carboxylate-functionalized alumina nanoparticles to be prepared directly from boehmite (AlOOH). Understanding the structural relationship between molecular and surface species allows for the rationalization/prediction of suitable alternative ligands as well as alternative oxide surfaces. The identity of the carboxylate substituent controls the pH stability of a nanoparticle as well as the porosity and processability of ceramics prepared by thermolysis. Through the choice of functional groups on the carboxylic acid the properties of the alumina surface or alumina nanoparticle can be tailored. For example, the solubility/miscibility of nanoparticles can be tuned to the solvent/matrix, and the wettability to be varied from hydrophobic to super hydrophilic. The choice Zwitter ionic substituents on alumina micro-/ultra-filtration membranes are found to enhance the flux and limit fouling while allowing for the facile separation of organic compounds from water. Examples are presented of purification of frac and flow-back water from oil well production as well as providing drinking water from contaminated sources in underdeveloped regions. PMID:24728503

  1. Self-assembly of amphiphilic homopolymers bearing ferrocene and carboxyl functionalities: effect of polymer concentration, β-cyclodextrin, and length of alkyl linker.

    PubMed

    Feng, Chun; Lu, Guolin; Li, Yongjun; Huang, Xiaoyu

    2013-08-27

    Three new acrylamide monomers containing ferrocene and tert-butyl ester groups were first synthesized via multistep nucleophilic substitution reaction under mild conditions followed by reversible addition-fragmentation chain transfer (RAFT) homopolymerization to give well-defined homopolymers with narrow molecular weight distributions (M(w)/M(n) ≤ 1.36). The target amphiphilic homopolymers were obtained by the acidic hydrolysis of tert-butyoxycarbonyls to carboxyls in every repeating unit using CF3COOH. The self-assembly behaviors of these amphiphilic homopolymers bearing both ferrocene and carboxyl moieties in each repeating unit in aqueous media were investigated by transmission emission microscopy (TEM), dynamic light scattering (DLS), and atomic force microscopy (AFM). Large compound micelles with different morphologies were formed by these amphiphilic homopolymers, which consist of the corona formed by hydrophilic carboxyls and the core containing numerous reverse micelles with hydrophilic islands of carboxyls in continuous hydrophobic phase of ferrocene-based segments. The morphologies of the formed micelles could be tuned by the concentration of amphiphilic homopolymers, pH value of the solution, the length of -CH2 linker between ferrocene group and carboxyl, and the amount of β-cyclodextrin (β-CD). PMID:23977901

  2. Compound matrices

    NASA Astrophysics Data System (ADS)

    Kravvaritis, Christos; Mitrouli, Marilena

    2009-02-01

    This paper studies the possibility to calculate efficiently compounds of real matrices which have a special form or structure. The usefulness of such an effort lies in the fact that the computation of compound matrices, which is generally noneffective due to its high complexity, is encountered in several applications. A new approach for computing the Singular Value Decompositions (SVD's) of the compounds of a matrix is proposed by establishing the equality (up to a permutation) between the compounds of the SVD of a matrix and the SVD's of the compounds of the matrix. The superiority of the new idea over the standard method is demonstrated. Similar approaches with some limitations can be adopted for other matrix factorizations, too. Furthermore, formulas for the n - 1 compounds of Hadamard matrices are derived, which dodge the strenuous computations of the respective numerous large determinants. Finally, a combinatorial counting technique for finding the compounds of diagonal matrices is illustrated.

  3. Decarboxylation of pyrrole-2-carboxylic acid: A DFT investigation

    NASA Astrophysics Data System (ADS)

    Cheng, Xueli; Wang, Jinhu; Tang, Ke; Liu, Yongjun; Liu, Chengbu

    2010-08-01

    Decarboxylation is normally a dissociative process, commonly catalyzed by proton or enzymes. The decarboxylation mechanism of pyrrole-2-carboxylic acid involves the addition of water to the carboxyl group, and the C-C bond cleavage leading to the protonated carbonic acid. The direct decarboxylation and decarboxylation aided with water were also investigated to consider the functions of proton and water. Our calculations with G AUSSIAN 03 package show that, with the assistance of H 3O +, the potential energy of the C-C rupture decreases significantly to 9.77 kcal/mol, and the total energy barrier decreases to 33.99 kcal/mol.

  4. Separation of aromatic carboxylic acids using quaternary ammonium salts on reversed-phase HPLC. 1. Separation behavior of aromatic carboxylic acids

    SciTech Connect

    Kawamura, K.; Okuwaki, A.; Verheyen, T.; Perry, G.J.

    2006-02-15

    In order to develop separation processes and analytical methods for aromatic carboxylic acids for the coal oxidation products, the separation behavior of aromatic carboxylic acids on a reversed-phase HPLC using eluent containing quaternary ammonium salt has been investigated. The retention mechanism of aromatic carboxylic acids was discussed on the basis of both ion-pair partition model and ion-exchange model. The retention behavior of aromatic carboxylic acids possessing one (or two) carboxylic acid group(s) followed the ion-pair partition model, where linear free energy relationship was observed between the capacity factor and the extraction equilibrium constants of benzoic acid and naphthalene carboxylic acid. Besides, the retention behavior followed ion-exchange model with increasing the number of carboxylic acids, where the capacity factor of benzene polycarboxylic acids is proportional to the association constants between aromatic acids and quaternary ammonium ions calculated on the basis of an electrostatic interaction model.

  5. Corrosion inhibition of rapidly solidified Mg-3% Zn-15% Al magnesium alloy with sodium carboxylates

    SciTech Connect

    Daloz, D.; Michot, G.; Rapin, C.; Steinmetz, P.

    1998-06-01

    The ability of sodium linear-saturated carboxylates to protect magnesium alloys against aqueous corrosion was characterized. Electrochemical measurements of polarization resistance and corrosion current showed the inhibition efficiency of these compounds is a function of their concentration and of the length of the aliphatic chain. In every case studied, the efficiency increased with immersion time. At pH 8, the best inhibiting behavior was observed with 0.05 M sodium undecanoate. The potential-pH diagram of magnesium in an aqueous solution containing undecanoate anions was generated based upon the solubility determined for magnesium undecanoate (Mg[CH{sub 3}(CH{sub 2}){sub 9}COO]{sub 2}). According to this diagram, the very low corrosion rate was suspected to result from formation of Mg(CH{sub 3}[CH{sub 2}]{sub 9}COO){sub 2}. Infrared spectrometry carried out on both the synthesized magnesium carboxylate and the product from the magnesium alloy surface after inhibitive treatment confirmed this hypothesis.

  6. Investigation of Pyridine Carboxylic Acids in CM2 Carbonaceous Chondrites: Potential Precursor Molecules for Ancient Coenzymes

    NASA Technical Reports Server (NTRS)

    Smith, Karen E.; Callahan, Michael P.; Gerakines, Perry A.; Dworkin, Jason P.; House, Christopher H.

    2014-01-01

    The distribution and abundances of pyridine carboxylic acids (including nicotinic acid) in eight CM2 carbonaceous chondrites (ALH 85013, DOM 03183, DOM 08003, EET 96016, LAP 02333, LAP 02336, LEW 85311, and WIS 91600) were investigated by liquid chromatography coupled to UV detection and high resolution Orbitrap mass spectrometry. We find that pyridine monocarboxylic acids are prevalent in CM2-type chondrites and their abundance negatively correlates with the degree of pre-terrestrial aqueous alteration that the meteorite parent body experienced. We lso report the first detection of pyridine dicarboxylic acids in carbonaceous chondrites. Additionally, we carried out laboratory studies of proton-irradiated pyridine in carbon dioxide-rich ices (a 1:1 mixture) to serve as a model of the interstellar ice chemistry that may have led to the synthesis of pyridine carboxylic acids. Analysis of the irradiated ice residue shows that a comparable suite of pyridine mono- and dicarboxylic acids was produced, although aqueous alteration may still play a role in the synthesis (and ultimate yield) of these compounds in carbonaceous meteorites. Nicotinic acid is a precursor to nicotinamide adenine dinucleotide, a likely ancient molecule used in cellular metabolism in all of life, and its common occurrence in CM2 chondrites may indicate that meteorites may have been a source of molecules for the emergence of more complex coenzymes on the early Earth.

  7. Investigation of Pyridine Carboxylic Acids in CM2 Carbonaceous Chondrites: Potential Precursor Molecules for Ancient Coenzymes

    NASA Technical Reports Server (NTRS)

    Smith, Karen E.; Callahan, Michael P.; Gerakines, Perry A.; Dworkin, Jason P.; House, Christopher H.

    2014-01-01

    The distribution and abundances of pyridine carboxylic acids (including nicotinic acid) in eight CM2 carbonaceous chondrites (ALH 85013, DOM 03183, DOM 08003, EET 96016, LAP 02333, LAP 02336, LEW 85311, and WIS 91600) were investigated by liquid chromatography coupled to UV detection and high resolution Orbitrap mass spectrometry. We find that pyridine monocarboxylic acids are prevalent in CM2-type chondrites and their abundance negatively correlates with the degree of pre-terrestrial aqueous alteration that the meteorite parent body experienced. We also report the first detection of pyridine dicarboxylic acids in carbonaceous chondrites. Additionally, we carried out laboratory studies of proton-irradiated pyridine in carbon dioxide-rich ices (a 1:1 mixture) to serve as a model of the interstellar ice chemistry that may have led to the synthesis of pyridine carboxylic acids. Analysis of the irradiated ice residue shows that a comparable suite of pyridine mono- and dicarboxylic acids was produced, although aqueous alteration may still play a role in the synthesis (and ultimate yield) of these compounds in carbonaceous meteorites. Nicotinic acid is a precursor to nicotinamide adenine dinucleotide, a likely ancient molecule used in cellular metabolism in all of life, and its common occurrence in CM2 chondrites may indicate that meteorites may have been a source of molecules for the emergence of more complex coenzymes on the early Earth.

  8. Thermolysis of a polymer model of aromatic carboxylic acids in low-rank coal

    SciTech Connect

    Mungall, W.S.; Britt, P.F.; Buchanan, A.C. III

    1997-03-01

    To compliment our current investigation into the role that decarboxylation of aromatic carboxylic acids plays in the low-temperature cross-linking of low-rank coals, we are investigating the thermolysis of a polymeric coal model compound to determine if the polymeric network structure of coal can alter the decarboxylation pathways. In this investigation, a bibenzylic polymer, poly-(m-xylylene-co-5-carboxy-m-xylylene), 1, was synthesized containing 2.3 carboxylic acids per 100 carbons, which is similar to that found in Zapp lignite. The pyrolysis of 1 was compared to poly-m-xylylene, 2, and the methyl ester of 1, 3, to determine if the carboxy group enhances cross-linking reactions. The major product from the pyrolysis of 1 at 375{degrees} C or 400{degrees} C for 1 h was a THF insoluble residue (60-75 wt%), while pyrolysis of 2 or the methyl ester of 1 produced only a THF soluble product. The mechanistic pathways leading to cross-linking will be discussed.

  9. Investigation of pyridine carboxylic acids in CM2 carbonaceous chondrites: Potential precursor molecules for ancient coenzymes

    NASA Astrophysics Data System (ADS)

    Smith, Karen E.; Callahan, Michael P.; Gerakines, Perry A.; Dworkin, Jason P.; House, Christopher H.

    2014-07-01

    The distribution and abundances of pyridine carboxylic acids (including nicotinic acid) in eight CM2 carbonaceous chondrites (ALH 85013, DOM 03183, DOM 08003, EET 96016, LAP 02333, LAP 02336, LEW 85311, and WIS 91600) were investigated by liquid chromatography coupled to UV detection and high resolution Orbitrap mass spectrometry. We find that pyridine monocarboxylic acids are prevalent in CM2-type chondrites and their abundance negatively correlates with the degree of pre-terrestrial aqueous alteration that the meteorite parent body experienced. We also report the first detection of pyridine dicarboxylic acids in carbonaceous chondrites. Additionally, we carried out laboratory studies of proton-irradiated pyridine in carbon dioxide-rich ices (a 1:1 mixture) to serve as a model of the interstellar ice chemistry that may have led to the synthesis of pyridine carboxylic acids. Analysis of the irradiated ice residue shows that a comparable suite of pyridine mono- and dicarboxylic acids was produced, although aqueous alteration may still play a role in the synthesis (and ultimate yield) of these compounds in carbonaceous meteorites. Nicotinic acid is a precursor to nicotinamide adenine dinucleotide, a likely ancient molecule used in cellular metabolism in all of life, and its common occurrence in CM2 chondrites may indicate that meteorites may have been a source of molecules for the emergence of more complex coenzymes on the early Earth.

  10. Experimental and computational studies of 4-(Trifluoromethyl)pyridine-2-carboxylic acid

    NASA Astrophysics Data System (ADS)

    Vural, Hatice

    2016-05-01

    The vibrational spectrum of 4-(Trifluoromethyl)pyridine-2-carboxylic acid was recorded using Fourier transform infrared spectrometer in the range 4000-400 cm-1. The optimized geometric structure of 4-(Trifluoromethyl)pyridine-2-carboxylic acid was searched by B3LYP, CAMB3LYP, and PBEPBE levels of density functional theory (DFT). The vibrational wavenumbers of the title molecule in the ground state were computed by using B3LYP, CAMB3LYP, and PBEPBE methods with the 6-31G (d) basis set. NMR chemical shifts of the title compound were calculated using the gauge-independent atomic orbital (GIAO) method. The solvent effect on the UV-Vis absorption spectrum of the molecule was also examined using the B3LYP method by applying the integral equation formalism-polarized continuum model (IEF-PCM). The nonlinear optical (NLO) properties were measured by means of hyperpolarizability calculation. The electric dipole moment, the mean polarizability and the mean first hyperpolarizability were calculated by using the DFT method with B3LYP, CAMB3LYP, and PBEPBE levels.

  11. Carboxylation of alkylboranes by N-heterocyclic carbene copper catalysts: synthesis of carboxylic acids from terminal alkenes and carbon dioxide.

    PubMed

    Ohishi, Takeshi; Zhang, Liang; Nishiura, Masayoshi; Hou, Zhaomin

    2011-08-22

    Caught in the act: N-Heterocyclic carbene copper(I) complexes (1; IPr=1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) serve as an excellent catalyst for the carboxylation of alkylboranes (2; R=alkyl) with CO(2) to afford a variety of functionalized carboxylic acids (3) in high yields. A novel copper methoxide/alkylborane adduct (A) and its subsequent CO(2) insertion product (B) have been isolated and shown to be true active catalyst species. PMID:21739544

  12. Improved Preparation of Halopropyl Bridged Carboxylic Ortho Esters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Protection of a carboxylic acid function as a bridged ortho ester derivative enables the use of strongly basic conditions in the synthetic strategy because the protons, alpha to the previous carbonyl carbon, are less acidic. Protected 3-halopropionic acid can behave like an alkyl halide making them...

  13. Porous Metal Carboxylate Boron Imidazolate Frameworks (MC-BIFs)

    PubMed Central

    Zheng, Shoutian; Wu, Tao; Zhang, Jian; Chow, Mina; Nieto, Ruben A.

    2011-01-01

    Integrated Material for Efficient CO2 Storage A new family of porous materials with tunable gas sorption properties have been made by integrating metal carboxylates and boron imidazolates under hydro- or solvothermal conditions. One hydrothermally synthesized phase exhibits a very high volumetric CO2 storage capacity at 81 L/L (273K, 1atm). PMID:20583020

  14. Neuronal pyruvate carboxylation supports formation of transmitter glutamate.

    PubMed

    Hassel, B; Brâthe, A

    2000-02-15

    Release of transmitter glutamate implies a drain of alpha-ketoglutarate from neurons, because glutamate, which is formed from alpha-ketoglutarate, is taken up by astrocytes. It is generally believed that this drain is compensated by uptake of glutamine from astrocytes, because neurons are considered incapable of de novo synthesis of tricarboxylic acid cycle intermediates, which requires pyruvate carboxylation. Here we show that cultured cerebellar granule neurons form releasable [(14)C]glutamate from H(14)CO(3)(-) and [1-(14)C]pyruvate via pyruvate carboxylation, probably mediated by malic enzyme. The activity of pyruvate carboxylation was calculated to be approximately one-third of the pyruvate dehydrogenase activity in neurons. Furthermore, intrastriatal injection of NaH(14)CO(3) or [1-(14)C]pyruvate labeled glutamate better than glutamine, showing that pyruvate carboxylation occurs in neurons in vivo. This means that neurons themselves to a large extent may support their release of glutamate, and thus entails a revision of the current view of glial-neuronal interactions and the importance of the glutamine cycle. PMID:10662824

  15. Dissolving Carboxylic Acids and Primary Amines on the Overhead Projector

    ERIC Educational Resources Information Center

    Solomon, Sally D.; Rutkowsky, Susan A.

    2010-01-01

    Liquid carboxylic acids (or primary amines) with limited solubility in water are dissolved by addition of aqueous sodium hydroxide (or hydrochloric acid) on the stage of an overhead projector using simple glassware and very small quantities of chemicals. This effective and colorful demonstration can be used to accompany discussions of the…

  16. Novel Lactate Transporters from Carboxylic Acid-Producing Rhizopus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The fungus Rhizopus is frequently used for fermentative production of lactic acid, but little is known about the mechanisms or proteins for transporting this carboxylic acid. Since transport of the lactate anion across the plasma membrane is critical to prevent acidification of the cytoplasm, we ev...

  17. The role of carboxylic acids in TALSQueak separations

    SciTech Connect

    Braley, Jenifer C.; Carter, Jennifer C.; Sinkov, Sergey I.; Nash, Ken L.; Lumetta, Gregg J.

    2012-04-13

    Recent reports have indicated TALSPEAK-type separations chemistry can be improved through the replacement of bis-2-ethyl(hexyl) phosphoric acid (HDEHP) and diethylenetriamine-N,N,N,N,N-pentaacetic acid (DTPA) with the weaker reagents 2-ethyl(hexyl) phosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) and N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid (HEDTA), respectively. This modified TALSPEAK has been provided with an adjusted acronym of TALSQueak (Trivalent Actinide Lanthanide Separation using Quicker Extractants and Aqueous Komplexes). Among several benefits, TALSQueak chemistry provides more rapid phase transfer kinetics, is less reliant on carboxylic acids to mediate lanthanide extraction and allows a simplified thermodynamic description of the separations process that generally requires only parameters available in the literature to describe metal transfer. This manuscript focuses on the role of carboxylic acids in aqueous ternary (M-HEDTA-carboxylate) complexes, americium/lanthanide separations, and extraction kinetics. Spectrophotometry (UV-vis) of the Nd hypersensitive band indicates the presence of aqueous ternary species (K111 = 1.83 {+-} 0.01 at 1.0 M ionic strength, Nd(HEDTA) + Lac <-> Nd(HEDTA)Lac). Varying the carboxylic acid does not have a significant impact on Ln/Am separations or extraction kinetics. TALSqueak separations come to equilibrium in five minutes at the conventional operational pH of 3.6 using only 0.1 M total lactate or citrate.

  18. Silver-catalyzed protodecarboxylation of heteroaromatic carboxylic acids.

    PubMed

    Lu, Pengfei; Sanchez, Carolina; Cornella, Josep; Larrosa, Igor

    2009-12-17

    A simple and highly efficient protodecarboxylation procedure for a variety of heteroaromatic carboxylic acids catalyzed by Ag(2)CO(3) and AcOH in DMSO is described. This methodology can also perform the selective monoprotodecarboxylation of several aromatic dicarboxylic acids. PMID:19924891

  19. The Synthesis of Copper(II) Carboxylates Revisited

    ERIC Educational Resources Information Center

    Kushner, Kevin; Spangler, Robert E.; Salazar, Ralph A., Jr.; Lagowski, J. J.

    2006-01-01

    An electrochemical synthesis of copper(II) carboxylates has been developed and used in the general chemistry laboratory course for chemistry majors. This synthesis, using nonaqueous solutions, supplements the strategy of providing experiences in synthetic chemistry described by Yoder et al. ("J. Chem. Educ." 1995, 72, 267). (Contains 1 table.)

  20. Improvement of ruthenium based decarboxylation of carboxylic acids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The removal of oxygen atoms from biobased carboxylic acids is an attractive route to provide the drop in replacement feedstocks that industry needs to continue to provide high performance products. Through the use of ruthenium catalysis, an efficient method where this process can be accomplished on ...

  1. Carboxylic Acids Plasma Membrane Transporters in Saccharomyces cerevisiae.

    PubMed

    Casal, Margarida; Queirós, Odília; Talaia, Gabriel; Ribas, David; Paiva, Sandra

    2016-01-01

    This chapter covers the functionally characterized plasma membrane carboxylic acids transporters Jen1, Ady2, Fps1 and Pdr12 in the yeast Saccharomyces cerevisiae, addressing also their homologues in other microorganisms, as filamentous fungi and bacteria. Carboxylic acids can either be transported into the cells, to be used as nutrients, or extruded in response to acid stress conditions. The secondary active transporters Jen1 and Ady2 can mediate the uptake of the anionic form of these substrates by a H(+)-symport mechanism. The undissociated form of carboxylic acids is lipid-soluble, crossing the plasma membrane by simple diffusion. Furthermore, acetic acid can also be transported by facilitated diffusion via Fps1 channel. At the cytoplasmic physiological pH, the anionic form of the acid prevails and it can be exported by the Pdr12 pump. This review will highlight the mechanisms involving carboxylic acids transporters, and the way they operate according to the yeast cell response to environmental changes, as carbon source availability, extracellular pH and acid stress conditions. PMID:26721276

  2. Improved preparation of haloalkyl bridged carboxylic ortho esters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Protection of a carboxylic acid function as a bridged ortho ester derivative enables the use of strong basic conditions in the synthetic strategy. For example, a protected 3-halopropionic acid can behave like an alkyl halide because the protons, alpha to the halide function, are less acidic. Ester...

  3. Light dependence of carboxylation capacity for C3 photosynthesis models

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Photosynthesis at high light is often modelled by assuming limitation by the maximum capacity of Rubisco carboxylation at low carbon dioxide concentrations, by electron transport capacity at higher concentrations, and sometimes by triose-phosphate utilization rate at the highest concentrations. Pho...

  4. Chiral Recognition Studies of α-(Nonafluoro-tert-butoxy)carboxylic Acids by NMR Spectroscopy.

    PubMed

    Nemes, Anikó; Csóka, Tamás; Béni, Szabolcs; Farkas, Viktor; Rábai, József; Szabó, Dénes

    2015-06-19

    Three chiral α-(nonafluoro-tert-butoxy)carboxylic acids (R)-1, (RS)-2, (R)-3 were synthesized to examine their application as chiral solvating agents with amines. As a model compound, first (S)- and/or (RS)-α-phenylethylamine was used, and their diastereomeric salts were investigated by (1)H and (19)F NMR and ECD spectroscopy. The NMR spectroscopic studies were carried out at room temperature using the slightly polar CDCl3 and apolar C6D6 as solvents in 5 mM and 54 mM concentrations. The difference of the chemical shifts (Δδ) in the diastereomeric complexes is comparable with other, well-known chiral derivatizing and solvating agents (e.g., Mosher's acid, Pirkle's alcohol). Diastereomeric salts of racemic acids (RS)-1 and (RS)-2 with biologically active amines (1R,2S)-ephedrine and (S)-dapoxetine were also investigated by (19)F NMR spectroscopy. PMID:26024423

  5. Structure-activity relationship of an ozonide carboxylic acid (OZ78) against Fasciola hepatica.

    PubMed

    Zhao, Qingjie; Vargas, Mireille; Dong, Yuxiang; Zhou, Lin; Wang, Xiaofang; Sriraghavan, Kamaraj; Keiser, Jennifer; Vennerstrom, Jonathan L

    2010-05-27

    In this paper, we describe the SAR of ozonide carboxylic acid OZ78 (1) as the first part of our search for a trematocidal synthetic peroxide drug development candidate. We found that relatively small structural changes to 1 resulted most commonly in loss of activity against Fasciola hepatica in vivo. A spiroadamantane substructure and acidic functional group (or ester prodrug) were required for activity. Of 26 new compounds administered at single 100 mg/kg oral doses to F. hepatica infected rats, 8 had statistically significant worm burden reductions, 7 were partially curative, and 1 (acylsulfonamide 6) was completely curative and comparable to 1 in flukicidal efficacy. This study also showed that the activity of 1 is peroxide-bond-dependent, suggesting that its flukicidal efficacy depends upon hemoglobin digestion in F. hepatica. PMID:20423101

  6. Sugar-Based Arylsulfonamide Carboxylates as Selective and Water-Soluble Matrix Metalloproteinase-12 Inhibitors.

    PubMed

    Nuti, Elisa; Cuffaro, Doretta; D'Andrea, Felicia; Rosalia, Lea; Tepshi, Livia; Fabbi, Marina; Carbotti, Grazia; Ferrini, Silvano; Santamaria, Salvatore; Camodeca, Caterina; Ciccone, Lidia; Orlandini, Elisabetta; Nencetti, Susanna; Stura, Enrico A; Dive, Vincent; Rossello, Armando

    2016-08-01

    Matrix metalloproteinase-12 (MMP-12) can be considered an attractive target to study selective inhibitors useful in the development of new therapies for lung and cardiovascular diseases. In this study, a new series of arylsulfonamide carboxylates, with increased hydrophilicity resulting from conjugation with a β-N-acetyl-d-glucosamine moiety, were designed and synthesized as MMP-12 selective inhibitors. Their inhibitory activity was evaluated on human MMPs by using the fluorimetric assay, and a crystallographic analysis was performed to characterize their binding mode. Among these glycoconjugates, a nanomolar MMP-12 inhibitor with improved water solubility, compound 3 [(R)-2-(N-(2-(3-(2-acetamido-2-deoxy-β-d-glucopyranosyl)thioureido)ethyl)biphenyl-4-ylsulfonamido)-3-methylbutanoic acid], was identified. PMID:27356908

  7. Lewis acid promoted ruthenium(II)-catalyzed etherifications by selective hydrogenation of carboxylic acids/esters.

    PubMed

    Li, Yuehui; Topf, Christoph; Cui, Xinjiang; Junge, Kathrin; Beller, Matthias

    2015-04-20

    Ethers are of fundamental importance in organic chemistry and they are an integral part of valuable flavors, fragrances, and numerous bioactive compounds. In general, the reduction of esters constitutes the most straightforward preparation of ethers. Unfortunately, this transformation requires large amounts of metal hydrides. Presented herein is a bifunctional catalyst system, consisting of Ru/phosphine complex and aluminum triflate, which allows selective synthesis of ethers by hydrogenation of esters or carboxylic acids. Different lactones were reduced in good yields to the desired products. Even challenging aromatic and aliphatic esters were reduced to the desired products. Notably, the in situ formed catalyst can be reused several times without any significant loss of activity. PMID:25728921

  8. Surface-Supported Robust 2D Lanthanide-Carboxylate Coordination Networks.

    PubMed

    Urgel, José I; Cirera, Borja; Wang, Yang; Auwärter, Willi; Otero, Roberto; Gallego, José M; Alcamí, Manuel; Klyatskaya, Svetlana; Ruben, Mario; Martín, Fernando; Miranda, Rodolfo; Ecija, David; Barth, Johannes V

    2015-12-16

    Lanthanide-based metal-organic compounds and architectures are promising systems for sensing, heterogeneous catalysis, photoluminescence, and magnetism. Herein, the fabrication of interfacial 2D lanthanide-carboxylate networks is introduced. This study combines low- and variable-temperature scanning tunneling microscopy (STM) and X-ray photoemission spectroscopy (XPS) experiments, and density functional theory (DFT) calculations addressing their design and electronic properties. The bonding of ditopic linear linkers to Gd centers on a Cu(111) surface gives rise to extended nanoporous grids, comprising mononuclear nodes featuring eightfold lateral coordination. XPS and DFT elucidate the nature of the bond, indicating ionic characteristics, which is also manifest in appreciable thermal stability. This study introduces a new generation of robust low-dimensional metallosupramolecular systems incorporating the functionalities of the f-block elements. PMID:26524215

  9. Synthesis, Fluorescence Properties, and Antiproliferative Potential of Several 3-Oxo-3H-benzo[f]chromene-2-carboxylic Acid Derivatives.

    PubMed

    Fu, Xiao-Bo; Wang, Xian-Fu; Chen, Jia-Nian; Wu, De-Wen; Li, Ting; Shen, Xing-Can; Qin, Jiang-Ke

    2015-01-01

    In this study, two series of 3-oxo-3H-benzo[f]chromene-2-carboxylic acid derivatives (compounds 5a-i and 6a-g) were synthesized. Their in vitro proliferation inhibitory activities against the A549 and NCI-H460 human non-small cell lung cancer (NSCLC) cell lines were evaluated. Their photophysical properties were measured. Among these target compounds, 5e exhibited the strongest antiproliferative activity by inducing apoptosis, arresting cell cycle, and elevating intracellular reactive oxygen species (ROS) level, suggesting that it may be a potent antitumor agent. In addition, compound 6g with very low cytotoxicity, demonstrated excellent fluorescence properties, which could be used as an effective fluorescence probe for biological imaging. PMID:26473819

  10. Photochemical transformations of diazocarbonyl compounds: expected and novel reactions

    NASA Astrophysics Data System (ADS)

    Galkina, O. S.; Rodina, L. L.

    2016-05-01

    Photochemical reactions of diazocarbonyl compounds are well positioned in synthetic practice as an efficient method for ring contraction and homologation of carboxylic acids and as a carbene generation method. However, interpretation of the observed transformations of diazo compounds in electronically excited states is incomplete and requires a careful study of the fine mechanisms of these processes specific to different excited states of diazo compounds resorting to modern methods of investigation, including laser technology. The review is devoted to analysis of new data in the chemistry of excited states of diazocarbonyl compounds. The bibliography includes 155 references.

  11. Synthesis, spectroscopic characterization and in vitro antimicrobial, anticancer and antileishmanial activities as well interaction with Salmon sperm DNA of newly synthesized carboxylic acid derivative, 4-(4-methoxy-2-nitrophenylamino)-4-oxobutanoic acid

    NASA Astrophysics Data System (ADS)

    Sirajuddin, Muhammad; Ali, Saqib; McKee, Vickie; Ullah, Hameed

    2015-03-01

    This paper stresses on the synthesis, characterization of novel carboxylic acid derivative and its application in pharmaceutics. Carboxylic acid derivatives have a growing importance in medicine, particularly in oncology. A novel carboxylic acid, 4-(4-methoxy-2-nitrophenylamino)-4-oxobutanoic acid, was synthesized and characterized by elemental analysis, FT-IR, NMR (1H, and 13C), mass spectrometry and single crystal X-ray structural analysis. The structure of the title compound, C11H12N2O6, shows the molecules dimerised by short intramolecular Osbnd H⋯O hydrogen bonds. The compound was screened for in vitro antimicrobial, anticancer, and antileishmanial activities as well as interaction with SS-DNA. The compound was also checked for in vitro anticancer activity against BHK-21, H-157 and HCEC cell lines, and showed significant anticancer activity. The compound was almost non-toxic towards human corneal epithelial cells (HCEC) and did not show more than 7.4% antiproliferative activity when used at the 2.0 μg/mL end concentration. It was also tested for antileishmanial activity against the promastigote form of leishmania major and obtained attractive result. DNA interaction study exposes that the binding mode of the compound with SS-DNA is an intercalative as it results in hypochromism along with minor red shift. A new and efficient strategy to identify pharmacophores sites in carboxylic acid derivative for antibacterial/antifungal activity using Petra, Osiris and Molinspiration (POM) analyses was also carried out.

  12. Synthesis, spectroscopic characterization and in vitro antimicrobial, anticancer and antileishmanial activities as well interaction with Salmon sperm DNA of newly synthesized carboxylic acid derivative, 4-(4-methoxy-2-nitrophenylamino)-4-oxobutanoic acid.

    PubMed

    Sirajuddin, Muhammad; Ali, Saqib; McKee, Vickie; Ullah, Hameed

    2015-03-01

    This paper stresses on the synthesis, characterization of novel carboxylic acid derivative and its application in pharmaceutics. Carboxylic acid derivatives have a growing importance in medicine, particularly in oncology. A novel carboxylic acid, 4-(4-methoxy-2-nitrophenylamino)-4-oxobutanoic acid, was synthesized and characterized by elemental analysis, FT-IR, NMR ((1)H, and (13)C), mass spectrometry and single crystal X-ray structural analysis. The structure of the title compound, C11H12N2O6, shows the molecules dimerised by short intramolecular OH⋯O hydrogen bonds. The compound was screened for in vitro antimicrobial, anticancer, and antileishmanial activities as well as interaction with SS-DNA. The compound was also checked for in vitro anticancer activity against BHK-21, H-157 and HCEC cell lines, and showed significant anticancer activity. The compound was almost non-toxic towards human corneal epithelial cells (HCEC) and did not show more than 7.4% antiproliferative activity when used at the 2.0μg/mL end concentration. It was also tested for antileishmanial activity against the promastigote form of leishmania major and obtained attractive result. DNA interaction study exposes that the binding mode of the compound with SS-DNA is an intercalative as it results in hypochromism along with minor red shift. A new and efficient strategy to identify pharmacophores sites in carboxylic acid derivative for antibacterial/antifungal activity using Petra, Osiris and Molinspiration (POM) analyses was also carried out. PMID:25536453

  13. Bis(dimethylsulfoxide)carbonateplatinum(ii), a new synthon for a low-impact, versatile synthetic route to anticancer Pt carboxylates.

    PubMed

    Bergamini, Paola; Marvelli, Lorenza; Ferretti, Valeria; Gemmo, Chiara; Gambari, Roberto; Hushcha, Yekatsiaryna; Lampronti, Ilaria

    2016-06-28

    The work describes a new low-impact synthetic route to Pt(ii)-carboxylate complexes, a class of compounds provided with established anticancer activity. The process is based on the ligand substitution on [PtCO3(Me2SO-S)2] (), a new synthon that can be easily prepared in water with high yield, is stable as a solid, and is reactive in solution where all its ligands can be easily replaced. It reacts with acidic O-donors releasing CO2 as the only side-product, whose development also supplies a driving force toward the products. The substitution of carbonate led to new Pt-DMSO carboxylate complexes , while the total substitution of the ligands of complex gave new Pt-phosphino carboxylates in high yields. The X-ray crystal structures of complexes [Pt(d(-)-quinate-O,O')(Me2SO-S)2] (), [Pt(salicylate)(Me2SO-S)2] () and [Pt(salicylate)(PPh3)2] () were determined. The tests of the antiproliferative activity of complexes on two human tumoral cell lines, A2780 (cisplatin-sensitive) and SKOV-3 (cisplatin-resistant), showed that the PTA (PTA = 1,3,5-triaza-7-phosphaadamantane) complexes were the most active on both cell lines. PMID:27291141

  14. Anionic sulfonated and carboxylated PPI dendrimers with the EDA core: synthesis and characterization of selective metal complexing agents.

    PubMed

    García-Gallego, Sandra; Cangiotti, Michela; Fiorani, Luigi; Fattori, Alberto; Muñoz-Fernández, Ma Ángeles; Gomez, Rafael; Ottaviani, M Francesca; de la Mata, F Javier

    2013-04-28

    Herein we describe the synthesis and characterization of new sulfonated and carboxylated poly(propyleneimino) (PPI) dendrimers with the ethylenediamino (EDA) core, at generations 1, 2 and 3. By means of UV-Vis and EPR spectroscopy, using Cu(2+) as a probe, we concluded that these dendrimers show a specific pattern in the coordination of metal ions. In agreement with the UV-Vis studies, EPR spectra of carboxylated compounds are constituted by 3 different signals which appear and then disappear with increasing copper concentration, corresponding to the saturation of different copper complexation sites. At the lowest copper concentration up to a 1:1 molar ratio between Cu(II) and the dendrimer, the spectrum is characteristic of a CuN2O2 coordination at the core of the dendrimer. The spectrum appearing at higher Cu(II) concentrations indicates a peripheral location of the ions coordinating one nitrogen and 3 oxygen atoms in a square planar geometry in restricted mobility conditions. For the highest concentrations tested, copper ions are confined at the external dendrimer surface with CuO4 coordination. For sulfonate systems, the EPR results are in line with a weaker interaction of Cu(II) with the nitrogen sites and a stronger interaction with the oxygen (SO3(-)) groups with respect to the interactions measured by EPR for carboxylate systems. PMID:23462972

  15. Improving the antidepressant action and the bioavailability of sertraline by co-crystallization with coumarin 3-carboxylate. Structural determination.

    PubMed

    Escudero, Graciela E; Laino, Carlos H; Echeverría, Gustavo A; Piro, Oscar E; Martini, Nancy; Rodríguez, Ailén N; Martínez Medina, Juan J; López Tévez, Libertad L; Ferrer, Evelina G; Williams, Patricia A M

    2016-04-01

    To improve the antidepressant action of sertraline a new salt with coumarin-3-carboxylate anion (SerH-CCA) has been synthesized by two different methods and characterized by FTIR spectroscopy and structural determinations by X-ray diffraction methods. The new salt is stabilized by strong intermolecular H-bonds involving the protonated amine group of SerH and the deprotonated carboxylate group of CCA. These findings can be correlated with the interpretation of the infrared spectrum. The salt, sertraline (SerHCl) and the sodium salt of coumarin-3-carboxylate (NaCCA) were orally administered male Wistar rats (10 mg/kg, based on sertraline). Rats were evaluated in separate groups by means of the forced swimming (FST). SerH-CCA produced antidepressant effects in a magnitude that exceeded SerHCl individual effects. None of these treatments affected activity levels by the open field OFT tests. We have also determined that the ion pair also improve the binding to bovine serum albumin (BSA) of the drug but retain its antimicrobial activity. It is reasonable to conclude that the replacement of chloride anion by a large organic anion in sertraline strengthens the pharmacological action of the native drug, binding to BSA with higher activity and retaining the antimicrobial activity of the antidepressant compound. PMID:26952715

  16. Tripotassium (bis­{[bis­(carboxyl­atometh­yl)amino]­meth­yl}phosphinato)cuprate(II) dihydrate

    PubMed Central

    Liu, Liyan; Zhang, Rui; Fan, Ping; Yu, Zhan; Zhang, Xiangdong

    2012-01-01

    In the title compound, K3[Cu(C10H12N2O10P)]·2H2O, the CuII ion, one potassium cation and a P atom are situated on a twofold rotation axis. The CuII ion is coordinated by two N and four O atoms from one bis­{[bis­(carboxyl­atometh­yl)amino]­meth­yl}phosphinate ligand in a distorted octa­hedral coordination geometry. The two crystallographically independent potassium ions exhibit different coordination environments. The potassium ion in a general position is hepta­coordinated by five carboxyl­ate O atoms, one phosphinate O atom and one water mol­ecule [K—O = 2.718 (3)–3.040 (3) Å], and the potassium ion situated on the twofold rotation axis is hexa­coordinated by four carboxyl­ate O atoms and two water mol­ecules [K—O = 2.618 (3)–2.771 (3) Å]. The water mol­ecules are also involved in formation of inter­molecular O—H⋯O hydrogen bonds. PMID:22259368

  17. Synthesis and bioevaluation of 2-phenyl-4-methyl-1,3-selenazole-5-carboxylic acids as potent xanthine oxidase inhibitors.

    PubMed

    Guan, Qi; Cheng, Zengjin; Ma, Xiaoxue; Wang, Lijie; Feng, Dongjie; Cui, Yuanhang; Bao, Kai; Wu, Lan; Zhang, Weige

    2014-10-01

    A series of 2-phenyl-4-methyl-1,3-selenazole-5-carboxylic acid derivatives (8a-f, 9a-m) were synthesized and evaluated for inhibitory activity against xanthine oxidase in vitro. Structure-activity relationship analyses have also been presented. Most of the target compounds exhibited potency levels in the nanomolar range. Compound 9e emerged as the most potent xanthine oxidase inhibitor (IC50 = 5.5 nM) in comparison to febuxostat (IC50 = 18.6 nM). Steady-state kinetics measurements with the bovine milk enzyme indicated a mixed type inhibition with Ki and Ki' values of 0.9 and 2.3 nM, respectively. A molecular modeling study on compounds 9e was performed to gain an insight into its binding mode with xanthine oxidase, and to provide the basis for further structure-guided design of new non-purine xanthine oxidase inhibitors related with 2-phenyl-4-methyl-1,3-selenazole-5-carboxylic acid scaffold. PMID:25113879

  18. In vitro assessment of potential intestinal absorption of some phenolic families and carboxylic acids from commercial instant coffee samples.

    PubMed

    López-Froilán, R; Ramírez-Moreno, E; Podio, N S; Pérez-Rodríguez, M L; Cámara, M; Baroni, M V; Wunderlin, D A; Sánchez-Mata, M C

    2016-06-15

    Coffee is one of the most consumed beverages in the world, being a source of bioactive compounds as well as flavors. Hydroxycinnamic acids, flavonols, and carboxylic acids have been studied in the samples of instant coffee commercialized in Spain. The studies about contents of food components should be complemented with either in vitro or in vivo bioaccessibility studies to know the amount of food components effectively available for functions in the human body. In this sense, a widely used in vitro model has been applied to assess the potential intestinal absorption of phenolic compounds and organic acids. The contents of hydroxycinnamic acids and flavonols were higher in instant regular coffee samples than in the decaffeinated ones. Bioaccessible phenolic compounds in most analyzed samples account for 20-25% of hydroxycinnamic acids and 17-26% of flavonols. This could mean that a great part of them can remain in the gut, acting as potential in situ antioxidants. Quinic, acetic, pyroglutamic, citric and fumaric acids were identified in commercial instant coffee samples. Succinic acid was found in the coffee blend containing chicory. All carboxylic acids showed a very high bioaccessibility. Particularly, acetic acid and quinic acid were found in higher contents in the samples treated with the in vitro simulation of gastrointestinal processes, compared to the original ones, which can be explained by their cleavage from chlorogenic acid during digestion. This is considered as a positive effect, since quinic acid is considered as an antioxidant inducer. PMID:27191052

  19. Diaqua­bis(pyridine-2-carboxyl­ato-κ2 N,O)cobalt(II)

    PubMed Central

    Huang, G. S.

    2008-01-01

    In the mol­ecule of the title compound, [Co(C6H4NO2)2(H2O)2], the coordination environment around the CoII atom is distorted octahedral; two N and two O atoms of the pyridine-2-carboxylate ligands lie in the equatorial plane and the two water O atoms in the axial positions. In the crystal structure, inter­molecular O—H⋯O hydrogen bonds link the mol­ecules, forming a supra­moleular network structure. PMID:21202222

  20. 5-Hydroxyquinoline-2-Carboxylic Acid, a Dead-End Metabolite from the Bacterial Oxidation of 5-Aminonaphthalene-2-Sulfonic Acid

    PubMed Central

    Nörtemann, Bernd; Glässer, Andrea; Machinek, Reinhard; Remberg, Gerd; Knackmuss, Hans-Joachim

    1993-01-01

    5-Aminonaphthalene-2-sulfonate (5A2NS) is converted by strain BN6 into 5-hydroxyquinoline-2-carboxylate (5H2QC). The authenticity of this new compound is confirmed by nuclear magnetic resonance and mass spectrometry. Its formation is explained by a spontaneous cyclization of the hypothetical metabolite 6′-amino-2′-hydroxybenzalpyruvate. The formation of 5H2QC as a dead-end product of 5A2NS prevents NADH regeneration so that 5A2NS oxidation is limited by the internal NADH pool. PMID:16348967

  1. Cesium Carboxylate-Promoted Iridium Catalyzed C-H Amidation/Cyclization with 2,2,2-Trichloroethoxycarbonyl Azide.

    PubMed

    Zhang, Tao; Wang, Zhen; Hu, Xuejiao; Yu, Meng; Deng, Tianning; Li, Guigen; Lu, Hongjian

    2016-06-01

    An Ir(III)-catalyzed direct C-H amidation/cyclization of benzamides using 2,2,2-trichloroethoxycarbonyl azide (TrocN3) as the aminocarbonyl source is reported. With the aid of cesium carboxylate, the reactions proceed efficiently and with high regioselectivity, producing various functionalized quinazoline-2,4(1H,3H)-diones, which are important building blocks and key synthetic intermediates for biologically and medicinally important compounds. During the reactions, two new C-N bonds were formed by breaking C-H and N-H bonds sequence. PMID:27164005

  2. Crystal structure of ethyl 2,4-di­chloro­quinoline-3-carboxyl­ate

    PubMed Central

    Cabrera, Alberto; Miranda, Luis D.; Reyes, Héctor; Aguirre, Gerardo; Chávez, Daniel

    2015-01-01

    In the crystal structure of the title compound, C12H9Cl2NO2, the mean planes through the quinoline and carboxyl­ate groups have r.m.s. deviations of 0.006 and 0.021 Å, respectively, and form a dihedral angle of 87.06 (19)°. In the crystal, mol­ecules are linked via very weak C—H⋯O hydrogen bonds, forming chains, which propagate along the c-axis direction. PMID:26870538

  3. Stimulation of H+ Efflux and Inhibition of Photosynthesis by Esters of Carboxylic Acids 1

    PubMed Central

    Duhaime, Donna E.; Bown, Alan W.

    1983-01-01

    Suspensions of mechanically isolated Asparagus sprengeri Regel mesophyll cells were used to investigate the influence of various carboxyester compounds on rates of net H+ efflux in the dark or light and photosynthetic O2 production. Addition of 0.15 to 1.5 millimolar malathion, α-naphthyl acetate, phenyl acetate, or p-nitrophenyl acetate stimulated H+ efflux and inhibited photosynthesis within 1 minute. In contrast, the more polar esters methyl acetoacetate or ethyl p-aminobenzoate had little or no effect on either of these two processes. A 0.15 millimolar concentration of α-naphthylacetate stimulated the normal rate of H+ efflux, 0.77 nanomoles H+ per 106 cells per minute by 750% and inhibited photosynthesis by 100%. The four active carboxyester compounds also stimulated H+ efflux after the normal rate of H+ efflux was eliminated with 0.01 milligrams per milliliter oligomycin or 100% N2. Oligomycin reduced the ATP level by 70%. Incubation of cells with malathion, α-naphthyl acetate, or p-nitrophenyl acetate resulted in the generation of the respective hydrolysis products ethanol, α-naphthol, and p-nitrophenol. It is proposed that inhibition of photosynthesis and stimulation of H+ efflux result when nonpolar carboxyester compounds enter the cell and generate acidic carboxyl groups when hydrolyzed by esterase enzymes. PMID:16663308

  4. In vitro anti-leishmanial and anti-fungal effects of new SbIII carboxylates

    PubMed Central

    2011-01-01

    Ring opening of phthalic anhydride has been carried out in acetic acid with glycine, β-alanine, L-phenylalanine, and 4-aminobenzoic acid to yield, respectively, 2-{[(carboxymethyl)amino]carbonyl}benzoic acid (I), 2-{[(2-carboxyethyl)amino]carbonyl}benzoic acid (II), 2-{[(1-carboxy-2-phenylethyl)amino]carbonyl}benzoic acid (III), and 2-[(4-carboxyanilino)carbonyl]benzoic acid (IV). Compounds I-IV have been employed as ligands for Sb(III) center (complexes V-VIII) in aqueous medium. FTIR and 1H NMR spectra proved the deprotonation of carboxylic protons and coordination of imine group and thereby tridentate behaviour of the ligands as chelates. Elemental, MS, and TGA analytic data confirmed the structural hypothesis based on spectroscopic results. All the compounds have been assayed in vitro for anti-leishmanial and anti-fungal activities against five leishmanial strains L. major (JISH118), L. major (MHOM/PK/88/DESTO), L. tropica (K27), L. infantum (LEM3437), L. mex mex (LV4), and L. donovani (H43); and Aspergillus Flavus, Aspergillus Fumigants, Aspergillus Niger, and Fusarium Solani. Compound VII exhibited good anti-leishmanial as well as anti-fungal impacts comparable to reference drugs.

  5. 40 CFR 721.10550 - Rare earth salt of a carboxylic acid (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Rare earth salt of a carboxylic acid... Specific Chemical Substances § 721.10550 Rare earth salt of a carboxylic acid (generic). (a) Chemical... as rare earth salt of a carboxylic acid (PMN P-05-324) is subject to reporting under this section...

  6. 40 CFR 721.10550 - Rare earth salt of a carboxylic acid (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Rare earth salt of a carboxylic acid... Specific Chemical Substances § 721.10550 Rare earth salt of a carboxylic acid (generic). (a) Chemical... as rare earth salt of a carboxylic acid (PMN P-05-324) is subject to reporting under this section...

  7. Cell Penetrant Inhibitors of the KDM4 and KDM5 Families of Histone Lysine Demethylases. 1. 3-Amino-4-pyridine Carboxylate Derivatives.

    PubMed

    Westaway, Susan M; Preston, Alex G S; Barker, Michael D; Brown, Fiona; Brown, Jack A; Campbell, Matthew; Chung, Chun-Wa; Diallo, Hawa; Douault, Clement; Drewes, Gerard; Eagle, Robert; Gordon, Laurie; Haslam, Carl; Hayhow, Thomas G; Humphreys, Philip G; Joberty, Gerard; Katso, Roy; Kruidenier, Laurens; Leveridge, Melanie; Liddle, John; Mosley, Julie; Muelbaier, Marcel; Randle, Rebecca; Rioja, Inma; Rueger, Anne; Seal, Gail A; Sheppard, Robert J; Singh, Onkar; Taylor, Joanna; Thomas, Pamela; Thomson, Douglas; Wilson, David M; Lee, Kevin; Prinjha, Rab K

    2016-02-25

    Optimization of KDM6B (JMJD3) HTS hit 12 led to the identification of 3-((furan-2-ylmethyl)amino)pyridine-4-carboxylic acid 34 and 3-(((3-methylthiophen-2-yl)methyl)amino)pyridine-4-carboxylic acid 39 that are inhibitors of the KDM4 (JMJD2) family of histone lysine demethylases. Compounds 34 and 39 possess activity, IC50 ≤ 100 nM, in KDM4 family biochemical (RFMS) assays with ≥ 50-fold selectivity against KDM6B and activity in a mechanistic KDM4C cell imaging assay (IC50 = 6-8 μM). Compounds 34 and 39 are also potent inhibitors of KDM5C (JARID1C) (RFMS IC50 = 100-125 nM). PMID:26771107

  8. Examination of acylated 4-aminopiperidine-4-carboxylic acid residues in the phosphotyrosyl+1 position of Grb2 SH2 domain-binding tripeptides.

    PubMed

    Kang, Sang-Uk; Choi, Won Jun; Oishi, Shinya; Lee, Kyeong; Karki, Rajeshri G; Worthy, Karen M; Bindu, Lakshman K; Nicklaus, Marc C; Fisher, Robert J; Burke, Terrence R

    2007-04-19

    A 4-aminopiperidine-4-carboxylic acid residue was placed in the pTyr+1 position of a Grb2 SH2 domain-binding peptide to form a general platform, which was then acylated with a variety of groups to yield a library of compounds designed to explore potential binding interactions, with protein features lying below the betaD strand. The highest affinities were obtained using phenylethyl carbamate and phenylbutyrylamide functionalities. PMID:17371004

  9. A spin-crossover complex based on a 2,6-bis(pyrazol-1-yl)pyridine (1-bpp) ligand functionalized with a carboxylate group.

    PubMed

    Abhervé, Alexandre; Clemente-León, Miguel; Coronado, Eugenio; Gómez-García, Carlos J; López-Jordà, Maurici

    2014-07-01

    Combining Fe(ii) with the carboxylate-functionalized 2,6-bis(pyrazol-1-yl)pyridine (bppCOOH) ligand results in the spin-crossover compound [Fe(bppCOOH)2](ClO4)2 which shows an abrupt spin transition with a T1/2 of ca. 380 K and a TLIESST of 60 K due to the presence of a hydrogen-bonded linear network of complexes. PMID:24804875

  10. Polybenzimidazole compounds

    DOEpatents

    Klaehn, John R.; Peterson, Eric S.; Wertsching, Alan K.; Orme, Christopher J.; Luther, Thomas A.; Jones, Michael G.

    2010-08-10

    A PBI compound that includes imidazole nitrogens, at least a portion of which are substituted with an organic-inorganic hybrid moiety. At least 85% of the imidazole nitrogens may be substituted. The organic-inorganic hybrid moiety may be an organosilane moiety, for example, (R)Me.sub.2SiCH.sub.2--, where R is selected from among methyl, phenyl, vinyl, and allyl. The PBI compound may exhibit similar thermal properties in comparison to the unsubstituted PBI. The PBI compound may exhibit a solubility in an organic solvent greater than the solubility of the unsubstituted PBI. The PBI compound may be included in separatory media. A substituted PBI synthesis method may include providing a parent PBI in a less than 5 wt % solvent solution. Substituting may occur at about room temperature and/or at about atmospheric pressure. Substituting may use at least five equivalents in relation to the imidazole nitrogens to be substituted or, preferably, about fifteen equivalents.

  11. Enhancing magnetoresistance in tetrathiafulvalene carboxylate modified iron oxide nanoparticle assemblies

    NASA Astrophysics Data System (ADS)

    Lv, Zhong-Peng; Luan, Zhong-Zhi; Cai, Pei-Yu; Wang, Tao; Li, Cheng-Hui; Wu, Di; Zuo, Jing-Lin; Sun, Shouheng

    2016-06-01

    We report a facile approach to stabilize Fe3O4 nanoparticles (NPs) by using tetrathiafulvalene carboxylate (TTF-COO-) and to control electron transport with an enhanced magnetoresistance (MR) effect in TTF-COO-Fe3O4 NP assemblies. This TTF-COO-coating is advantageous over other conventional organic coatings, making it possible to develop stable Fe3O4 NP arrays for sensitive spintronics applications.We report a facile approach to stabilize Fe3O4 nanoparticles (NPs) by using tetrathiafulvalene carboxylate (TTF-COO-) and to control electron transport with an enhanced magnetoresistance (MR) effect in TTF-COO-Fe3O4 NP assemblies. This TTF-COO-coating is advantageous over other conventional organic coatings, making it possible to develop stable Fe3O4 NP arrays for sensitive spintronics applications. Electronic supplementary information (ESI) available: Experimental details; supplementary figures and tables. See DOI: 10.1039/c6nr03311c

  12. Sensing of antipyretic carboxylates by simple chromogenic calix[4]pyrroles.

    PubMed

    Nishiyabu, Ryuhei; Anzenbacher, Pavel

    2005-06-15

    We present a simple, two- or three-step method for the synthesis of chromogenic octamethylcalix[4]pyrrole-based (OMCP) sensors for anions. Electrophilic aromatic substitution allows for converting the pyrrole moieties of OMCP into a dye. The formation of a sensor-anion complex results in partial charge transfer and a dramatic change in color. The absorption (UV-vis) and NMR titration experiments show that the chromogenic OMCPs sense anions administered as aqueous solutions, even at high ionic strength ( approximately 0.1 M NaCl), while displaying selectivity for pyrophosphate and carboxylate anions. The experiments with polyurethane sensor films show a strong response for aqueous carboxylates, such as antipyretics naproxen approximately ibuprofen > salicylate, without being biased by bicarbonate or carboxy termini of blood plasma proteins. PMID:15941245

  13. Giant regular polyhedra from calixarene carboxylates and uranyl

    PubMed Central

    Pasquale, Sara; Sattin, Sara; Escudero-Adán, Eduardo C.; Martínez-Belmonte, Marta; de Mendoza, Javier

    2012-01-01

    Self-assembly of large multi-component systems is a common strategy for the bottom-up construction of discrete, well-defined, nanoscopic-sized cages. Icosahedral or pseudospherical viral capsids, built up from hundreds of identical proteins, constitute typical examples of the complexity attained by biological self-assembly. Chemical versions of the so-called 5 Platonic regular or 13 Archimedean semi-regular polyhedra are usually assembled combining molecular platforms with metals with commensurate coordination spheres. Here we report novel, self-assembled cages, using the conical-shaped carboxylic acid derivatives of calix[4]arene and calix[5]arene as ligands, and the uranyl cation UO22+ as a metallic counterpart, which coordinates with three carboxylates at the equatorial plane, giving rise to hexagonal bipyramidal architectures. As a result, octahedral and icosahedral anionic metallocages of nanoscopic dimensions are formed with an unusually small number of components. PMID:22510690

  14. Soluble, High Molecular Weight Polysilsesquioxanes with Carboxylate Functionalities

    SciTech Connect

    RAHIMIAN,KAMYAR; LOY,DOUGLAS A.; WHEELER,DAVID R.

    2000-07-14

    Trialkoxysilyl-containing monomers of the type (RO){sub 3}Si(CH{sub 2}){sub 3}C(O)OtBu (R = Me, Et) were prepared by hydrosilation of the corresponding vinylic tert-butyl esters CH{sub 3}CHCH{sub 2}C(O)OtBu. Acid- or base-catalyzed polymerization of the monomers leads to very high molecular weight polymers with relatively narrow polydispersities. The polymerization results in complete condensation of the alkoxy groups while the tert-butyl ester functionality remains fully intact. Partial or full deprotection of the tert-butyl group can easily be achieved to yield the corresponding carboxylic acid polymers. The ester and carboxylic acid functionalities of these new materials allow for their potential use in a variety of applications such as scavenging of heavy metals.

  15. Functionalization of carbon nanotube by carboxyl group under radial deformation

    NASA Astrophysics Data System (ADS)

    Lara, Ivi Valentini; Zanella, Ivana; Fagan, Solange Binotto

    2014-01-01

    The dependence of the structural and the electronic properties of functionalized (5, 5) single-walled carbon nanotubes (SWNT) were investigated through ab initio density functional simulations when the carboxyl group is bonded on the flatter or curved regions. Radial deformations result in diameter decrease of up to 20 per cent of the original size, which was the limit reduction that maintains the SWNT functionalized structure. Changes on the electronic structure were observed due to the symmetry break of the SWNT caused by both the carboxyl group and the C-C bond distortions resulted by the radial deformation. It is observed that the functionalization process is specially favored by the sp3 hybridization induced on the more curved region of the deformed SWNT.

  16. Aldehydes, carboxylic acids and inorganic nitrate during NSMCS

    NASA Astrophysics Data System (ADS)

    Grosjean, Daniel

    This article describes the methods and results of a study involving measurements of ambient levels of carboxylic acids (formic, acetic and oxalic), aldehydes (formaldehyde, acetaldehyde, propanal, n- butanal, n- pentanal and benzaldehyde) and total inorganic nitrate (nitric acid + particulate nitrate) during the Nitrogen Species Methods Comparison Study (NSMCS). Results for inorganic nitrate obtained using Teflon-nylon filter packs are compared to those obtained with nylon-nylon filter units and to those obtained by other methods during NSMCS. Calculations are presented of the distribution of gas phase nitrogen among NO, NO 2, HONO 2 and PAN, and of the positive bias due to PAN and HONO 2 in NOx measurements by chemiluminescence. Data for aldehydes and carboxylic acids are discussed in terms of sampling efficiency, gas-aerosol phase distribution, possible interferents (e.g. PAN as acetate on alkaline filters), diurnal variations, and relative importance of emissions vs in-situ daytime and night-time formation and removal processes.

  17. Propensity of salicylamide and ethenzamide cocrystallization with aromatic carboxylic acids.

    PubMed

    Przybyłek, Maciej; Ziółkowska, Dorota; Mroczyńska, Karina; Cysewski, Piotr

    2016-03-31

    The cocrystallization of salicylamide (2-hydroxybenzamide, SMD) and ethenzamide (2-ethoxybenzamide, EMD) with aromatic carboxylic acids was examined both experimentally and theoretically. The supramolecular synthesis taking advantage of the droplet evaporative crystallization (DEC) technique was combined with powder diffraction and vibrational spectroscopy as the analytical tools. This led to identification of eleven new cocrystals including pharmaceutically relevant coformers such as mono- and dihydroxybenzoic acids. The cocrystallization abilities of SMD and EMD with aromatic carboxylic acids were found to be unexpectedly divers despite high formal similarities of these two benzamides and ability of the R2,2(8) heterosynthon formation. The source of diversities of the cocrystallization landscapes is the difference in the stabilization of possible conformers by adopting alternative intramolecular hydrogen boding patterns. The stronger intramolecular hydrogen bonding the weaker affinity toward intermolecular complexation potential. The substituent effects on R2,2(8) heterosynthon properties are also discussed. PMID:26898408

  18. Substrate Specificity within a Family of Outer Membrane Carboxylate Channels

    SciTech Connect

    Eren, Elif; Vijayaraghavan, Jagamya; Liu, Jiaming; Cheneke, Belete R.; Touw, Debra S.; Lepore, Bryan W.; Indic, Mridhu; Movileanu, Liviu; van den Berg, Bert; Dutzler, Raimund

    2012-01-17

    Many Gram-negative bacteria, including human pathogens such as Pseudomonas aeruginosa, do not have large-channel porins. This results in an outer membrane (OM) that is highly impermeable to small polar molecules, making the bacteria intrinsically resistant towards many antibiotics. In such microorganisms, the majority of small molecules are taken up by members of the OprD outer membrane protein family. Here we show that OprD channels require a carboxyl group in the substrate for efficient transport, and based on this we have renamed the family Occ, for outer membrane carboxylate channels. We further show that Occ channels can be divided into two subfamilies, based on their very different substrate specificities. Our results rationalize how certain bacteria can efficiently take up a variety of substrates under nutrient-poor conditions without compromising membrane permeability. In addition, they explain how channel inactivation in response to antibiotics can cause resistance but does not lead to decreased fitness.

  19. Electrocarboxylation: towards sustainable and efficient synthesis of valuable carboxylic acids

    PubMed Central

    Matthessen, Roman; Fransaer, Jan; Binnemans, Koen

    2014-01-01

    Summary The near-unlimited availability of CO2 has stimulated a growing research effort in creating value-added products from this greenhouse gas. This paper presents the trends on the most important methods used in the electrochemical synthesis of carboxylic acids from carbon dioxide. An overview is given of different substrate groups which form carboxylic acids upon CO2 fixation, including mechanistic considerations. While most work focuses on the electrocarboxylation of substrates with sacrificial anodes, this review considers the possibilities and challenges of implementing other synthetic methodologies. In view of potential industrial application, the choice of reactor setup, electrode type and reaction pathway has a large influence on the sustainability and efficiency of the process. PMID:25383120

  20. Fluorescently tuned nitrogen-doped carbon dots from carbon source with different content of carboxyl groups

    SciTech Connect

    Wang, Hao; Wang, Yun; Dai, Xiao; Zou, Guifu E-mail: zouguifu@suda.edu.cn; Gao, Peng; Zhang, Ke-Qin E-mail: zouguifu@suda.edu.cn; Du, Dezhuang; Guo, Jun

    2015-08-01

    In this study, fluorescent nitrogen-doped carbon dots (NCDs) were tuned via varying the sources with different number of carboxyl groups. Owing to the interaction between amino and carboxyl, more amino groups conjugate the surface of the NCDs by the source with more carboxyl groups. Fluorescent NCDs were tuned via varying the sources with different content of carboxyl groups. Correspondingly, the nitrogen content, fluorescence quantum yields and lifetime of NCDs increases with the content of carboxyl groups from the source. Furthermore, cytotoxicity assay and cell imaging test indicate that the resultant NCDs possess low cytotoxicity and excellent biocompatibility.

  1. Enhancing magnetoresistance in tetrathiafulvalene carboxylate modified iron oxide nanoparticle assemblies.

    PubMed

    Lv, Zhong-Peng; Luan, Zhong-Zhi; Cai, Pei-Yu; Wang, Tao; Li, Cheng-Hui; Wu, Di; Zuo, Jing-Lin; Sun, Shouheng

    2016-06-16

    We report a facile approach to stabilize Fe3O4 nanoparticles (NPs) by using tetrathiafulvalene carboxylate (TTF-COO(-)) and to control electron transport with an enhanced magnetoresistance (MR) effect in TTF-COO-Fe3O4 NP assemblies. This TTF-COO-coating is advantageous over other conventional organic coatings, making it possible to develop stable Fe3O4 NP arrays for sensitive spintronics applications. PMID:27271347

  2. Palladium-Catalyzed Carboxylation of Activated Vinylcyclopropanes with CO2.

    PubMed

    Mita, Tsuyoshi; Tanaka, Hiroyuki; Higuchi, Yuki; Sato, Yoshihiro

    2016-06-01

    By using a palladium catalyst with ZnEt2, activated vinylcyclopropanes were successfully converted into the corresponding β,γ-unsaturated carboxylic acids in high yields under a CO2 atmosphere (1 atm). The intermediate in this reaction is thought to be a nucleophilic η(1)-allylethylpalladium species, which would be produced from π-allylpalladium and ZnEt2 (umpolung reactivity). PMID:27184762

  3. Synthesis and properties of 1-aryl(pyrimidinyl)-piperazinylalkyl derivatives of ethyl 3-phenyl-7-methyl-2,4-dioxo-1,2,3,4-tetrahydropyrido[2,3-d] pyrimidine-5-carboxylate.

    PubMed

    Sladowska, H; Sieklucka-Dziuba, M; Staniak, L; Kleinrok, Z

    1994-01-01

    Synthesis of N-aryl (pyrimidinyl)piperazinylalkyl derivatives of ethyl 2,4-dioxo-1,2,3-4-tetrahydropyrido[2,3-d]pyrimidine-5-carboxylate is reported. Some of the obtained compounds are pharmacologically active. PMID:7945716

  4. Metabolic engineering of biocatalysts for carboxylic acids production

    PubMed Central

    Liu, Ping; Jarboe, Laura R.

    2012-01-01

    Fermentation of renewable feedstocks by microbes to produce sustainable fuels and chemicals has the potential to replace petrochemical-based production. For example, carboxylic acids produced by microbial fermentation can be used to generate primary building blocks of industrial chemicals by either enzymatic or chemical catalysis. In order to achieve the titer, yield and productivity values required for economically viable processes, the carboxylic acid-producing microbes need to be robust and well-performing. Traditional strain development methods based on mutagenesis have proven useful in the selection of desirable microbial behavior, such as robustness and carboxylic acid production. On the other hand, rationally-based metabolic engineering, like genetic manipulation for pathway design, has becoming increasingly important to this field and has been used for the production of several organic acids, such as succinic acid, malic acid and lactic acid. This review investigates recent works on Saccharomyces cerevisiae and Escherichia coli, as well as the strategies to improve tolerance towards these chemicals. PMID:24688671

  5. Cellular uptake and anticancer activity of carboxylated gallium corroles.

    PubMed

    Pribisko, Melanie; Palmer, Joshua; Grubbs, Robert H; Gray, Harry B; Termini, John; Lim, Punnajit

    2016-04-19

    We report derivatives of gallium(III) tris(pentafluorophenyl)corrole, 1 [Ga(tpfc)], with either sulfonic (2) or carboxylic acids (3, 4) as macrocyclic ring substituents: the aminocaproate derivative, 3 [Ga(ACtpfc)], demonstrated high cytotoxic activity against all NCI60 cell lines derived from nine tumor types and confirmed very high toxicity against melanoma cells, specifically the LOX IMVI and SK-MEL-28 cell lines. The toxicities of 1, 2, 3, and 4 [Ga(3-ctpfc)] toward prostate (DU-145), melanoma (SK-MEL-28), breast (MDA-MB-231), and ovarian (OVCAR-3) cancer cells revealed a dependence on the ring substituent: IC50values ranged from 4.8 to >200 µM; and they correlated with the rates of uptake, extent of intracellular accumulation, and lipophilicity. Carboxylated corroles 3 and 4, which exhibited about 10-fold lower IC50values (<20 µM) relative to previous analogs against all four cancer cell lines, displayed high efficacy (Emax= 0). Confocal fluorescence imaging revealed facile uptake of functionalized gallium corroles by all human cancer cells that followed the order: 4 > 3 > 2 > 1 (intracellular accumulation of gallium corroles was fastest in melanoma cells). We conclude that carboxylated gallium corroles are promising chemotherapeutics with the advantage that they also can be used for tumor imaging. PMID:27044076

  6. Green process for chemical functionalization of nanocellulose with carboxylic acids.

    PubMed

    Espino-Pérez, Etzael; Domenek, Sandra; Belgacem, Naceur; Sillard, Cécile; Bras, Julien

    2014-12-01

    An environmentally friendly and simple method, named SolReact, has been developed for a solvent-free esterification of cellulose nanocrystals (CNC) surface by using two nontoxic carboxylic acids (CA), phenylacetic acid and hydrocinnamic acid. In this process, the carboxylic acids do not only act as grafting agent, but also as solvent media above their melting point. Key is the in situ solvent exchange by water evaporation driving the esterification reaction without drying the CNC. Atomic force microscopy and X-ray diffraction analyses showed no significant change in the CNC dimensions and crystallinity index after this green process. The presence of the grafted carboxylic was characterized by analysis of the "bulk" CNC with elemental analysis, infrared spectroscopy, and (13)C NMR. The ability to tune the surface properties of grafted nanocrystals (CNC-g-CA) was evaluated by X-ray photoelectron spectroscopy analysis. The hydrophobicity behavior of the functionalized CNC was studied through the water contact-angle measurements and vapor adsorption. The functionalization of these bionanoparticles may offer applications in composite manufacturing, where these nanoparticles have limited dispersibility in hydrophobic polymer matrices and as nanoadsorbers due to the presence of phenolic groups attached on the surface. PMID:25353612

  7. Analysis of liposoluble carboxylic acids metabolome in human serum by stable isotope labeling coupled with liquid chromatography-mass spectrometry.

    PubMed

    Zhu, Quan-Fei; Zhang, Zheng; Liu, Ping; Zheng, Shu-Jian; Peng, Ke; Deng, Qian-Yun; Zheng, Fang; Yuan, Bi-Feng; Feng, Yu-Qi

    2016-08-19

    Fatty acids (FAs) are groups of liposoluble carboxylic acids (LCAs) and play important roles in various physiological processes. Abnormal contents or changes of FAs are associated with a series of diseases. Here we developed a strategy with stable isotope labeling combined with liquid chromatography-tandem mass spectrometry (IL-LC-MS) analysis for comprehensive profiling and relative quantitation of LCAs in human serum. In this strategy, a pair of isotope labeling reagents (2-dimethylaminoethylamine (DMED)) and d4-2-dimethylaminoethylamine (d4-DMED) were employed to selectively label carboxyl groups of LCAs. The DMED and d4-DMED labeled products can lose four characteristic neutral fragments of 45 and 49Da or 63 and 67Da in collision-induced dissociation. Therefore, quadruple neutral loss scan (QNLS) mode was established and used for non-targeted profiling of LCAs. The peak pairs of DMED and d4-DMED labeling with the same retention time, intensity and characteristic mass differences were extracted from the two NLS spectra respectively, and assigned as potential LCA candidates. Using this strategy, 241 LCA candidates were discovered in the human serum; 156 carboxylic acid compounds could be determined by searching HMDB and METLIN databases (FAs are over 90%) and 21 of these LCAs were successfully identified by standards. Subsequently, a modified pseudo-targeted method with multiple reaction monitoring (MRM) detection mode was developed and used for relative quantification of LCAs in human serum from type 2 diabetes mellitus (T2DM) patients and healthy controls. As a result, 81 LCAs were found to have significant difference between T2DM patients and healthy controls. Taken together, the isotope labeling combined with tandem mass spectrometry analysis demonstrated to be a powerful strategy for identification and quantification of LCA compounds in serum samples. PMID:27432792

  8. A C2-symmetric, basic Fe(III) carboxylate complex derived from a novel triptycene-based chelating carboxylate ligand.

    PubMed

    Li, Yang; Wilson, Justin J; Do, Loi H; Apfel, Ulf-Peter; Lippard, Stephen J

    2012-08-21

    A triptycene-based bis(benzoxazole) diacid ligand H(2)L2(Ph4) bearing sterically encumbering groups was synthesized. Treatment of H(2)L2(Ph4) with Fe(OTf)(3) afforded a C(2)-symmetric trinuclear iron(III) complex, [NaFe(3)(L2(Ph4))(2)(μ(3)-O)(μ-O(2)CCPh(3))(2)(H(2)O)(3)](OTf)(2) (8). The triiron core of this complex adopts the well known "basic iron acetate" structure where the heteroleptic carboxylates, comprising two Ph(3)CCO(2)(-) and two (L2(Ph4))(2-) ligands, donate the six carboxylate bridges. The (L2(Ph4))(2-) ligand undergoes only minor conformational changes upon formation of the complex. PMID:22751622

  9. A C2-Symmetric, Basic Fe(III) Carboxylate Complex Derived from a Novel Triptycene-Based Chelating Carboxylate Ligand

    PubMed Central

    Li, Yang; Wilson, Justin J.; Do, Loi H.; Apfel, Ulf-Peter; Lippard, Stephen J.

    2012-01-01

    A triptycene-based bis(benzoxazole) diacid ligand H2L2Ph4 bearing sterically encumbering groups was synthesized. Treatment of H2L2Ph4 with Fe(OTf)3 afforded a C2-symmetric trinuclear iron(III) complex, [NaFe3(L2Ph4)2(μ3-O)(μ-O2CCPh3)2(H2O)3](OTf)2 (8). The triiron core of this complex adopts the well known “basic iron acetate” structure where the heteroleptic carboxylates, comprising two dianionic ligands (L2Ph4)2− and two Ph3CCO2−, donate the six carboxylate bridges. The (L2Ph4)2− ligand undergoes only minor conformational changes upon formation of the complex. PMID:22751622

  10. Synthesis of α,β-unsaturated esters via a chemo-enzymatic chain elongation approach by combining carboxylic acid reduction and Wittig reaction

    PubMed Central

    Duan, Yitao; Yao, Peiyuan; Du, Yuncheng; Feng, Jinhui

    2015-01-01

    Summary α,β-Unsaturated esters are versatile building blocks for organic synthesis and of significant importance for industrial applications. A great variety of synthetic methods have been developed, and quite a number of them use aldehydes as precursors. Herein we report a chemo-enzymatic chain elongation approach to access α,β-unsaturated esters by combining an enzymatic carboxylic acid reduction and Wittig reaction. Recently, we have found that Mycobacterium sp. was able to reduce phenylacetic acid (1a) to 2-phenyl-1-ethanol (1c) and two sequences in the Mycobacterium sp. genome had high identity with the carboxylic acid reductase (CAR) gene from Nocardia iowensis. These two putative CAR genes were cloned, overexpressed in E. coli and one of two proteins could reduce 1a. The recombinant CAR was purified and characterized. The enzyme exhibited high activity toward a variety of aromatic and aliphatic carboxylic acids, including ibuprofen. The Mycobacterium CAR catalyzed carboxylic acid reduction to give aldehydes, followed by a Wittig reaction to afford the products α,β-unsaturated esters with extension of two carbon atoms, demonstrating a new chemo-enzymatic method for the synthesis of these important compounds. PMID:26664647

  11. Synthesis, Aqueous Reactivity, and Biological Evaluation of Carboxylic Acid Ester-Functionalized Platinum–Acridine Hybrid Anticancer Agents

    PubMed Central

    Graham, Leigh A.; Suryadi, Jimmy; West, Tiffany K.; Kucera, Gregory L.; Bierbach, Ulrich

    2012-01-01

    The synthesis of platinum–acridine hybrid agents containing carboxylic acid ester groups is described. The most active derivatives and the unmodified parent compounds showed up to 6-fold higher activity in ovarian cancer (OVCAR-3) and breast cancer (MCF-7, MDA-MB-23) cell lines than cisplatin. Inhibition of cell proliferation at nanomolar concentrations was observed in pancreatic (PANC-1) and non-small cell lung cancer cells (NSCLC, NCI-H460) of 80- and 150-fold, respectively. Introduction of the ester groups did not affect the cytotoxic properties of the hybrids, which form the same monofunctional–intercalative DNA adducts as the parent compounds, as demonstrated in a plasmid unwinding assay. In-line high-performance liquid chromatography and electrospray mass spectrometry (LC-ESMS) shows that the ester moieties undergo platinum-mediated hydrolysis in a chloride concentration-dependent manner to form carboxylate chelates. Potential applications of the chloride-sensitive ester hydrolysis as a self-immolative release mechanism for tumor-selective delivery of platinum–acridines are discussed. PMID:22871158

  12. Phenazine-1-carboxylic acid mediated anti-oomycete activity of the endophytic Alcaligenes sp. EIL-2 against Phytophthora meadii.

    PubMed

    Abraham, Amith; Philip, Shaji; Jacob, Manoj Kurian; Narayanan, Sunilkumar Puthenpurackel; Jacob, C Kuruvilla; Kochupurackal, Jayachandran

    2015-01-01

    The oomycete pathogen, Phytophthora meadii, causes various diseases in Hevea brasiliensis at different stages of its life cycle. The study reports the structural characterization of the active principle from the culture filtrate of Alcaligenes sp. EIL-2 (GenBank ID: HQ641257) offering antagonistic activity against P. meadii. Gas Chromatography Mass Spectroscopy (GC-MS) analysis showed the similarity of the compound with phenazine derivatives. The specific representations of FT-IR spectrum such as 3200 cm(-1) (OH stretching, NH stretching and presence of aromatic ring), 1737 cm(-1) (carboxylic acid), 2200-2400 cm(-1) (conjugated dienes) and 1467 cm(-1), and 1422 cm(-1) (CN bonds) were an indicative of phenazine-1-carboxylic acid (PCA). The structure of the compound was further confirmed by (1)H NMR/(13)C NMR spectroscopy, DEPT experiments, and two-dimensional NMR spectral studies, including (1)H-(1)H COSY and (1)H-(13)C HSQC as PCA with the molecular formula of C₁₃H₈N₂O₂. P. meadii was sensitive to purified PCA extract from the endophyte and a concentration of 5 μg/ml completely inhibited the mycelia growth. PCA also showed zoosporicidal activity against P. meadii zoospores. This is the first study of this kind where PCA from an endophyte of H. brasiliensis is being confirmed to carry antagonistic activity against P. meadii. PMID:24985092

  13. Photocatalytic Decomposition of Carboxylated Molecules on Light-Exposed Martian Regolith and Its Relation to Methane Production on Mars

    NASA Astrophysics Data System (ADS)

    Shkrob, Ilya A.; Chemerisov, Sergey D.; Marin, Timothy W.

    2010-05-01

    We propose that the paucity of organic compounds in martian soil can be accounted for by efficient photocatalytic decomposition of carboxylated molecules due to the occurrence of the photo-Kolbe reaction at the surface of particulate iron(III) oxides that are abundant in the martian regolith. This photoreaction is initiated by the absorption of UVA light, and it readily occurs even at low temperature. The decarboxylation is observed for miscellaneous organic carboxylates, including the nonvolatile products of kerogen oxidation (that are currently thought to accumulate in the soil) as well as α-amino acids and peptides. Our study indicates that there may be no "safe haven" for these organic compounds on Mars; oxidation by reactive radicals, such as hydroxyl, is concerted with photocatalytic reactions on the oxide particles. Acting together, these two mechanisms result in mineralization of the organic component. The photooxidation of acetate (the terminal product of radical oxidation of the aliphatic component of kerogen) on the iron(III) oxides results in the formation of methane; this reaction may account for seasonably variable production of methane on Mars. The concomitant reduction of Fe(III) in the regolith leads to the formation of highly soluble ferrous ions that contribute to weathering of the soil particles.

  14. Synthesis and pharmacological characterization of novel xanthine carboxylate amides as A2A adenosine receptor ligands exhibiting bronchospasmolytic activity.

    PubMed

    Yadav, Rakesh; Bansal, Ranju; Rohilla, Suman; Kachler, Sonja; Klotz, Karl-Norbert

    2016-04-01

    The carboxylate amides of 8-phenyl-1,3-dimethylxanthine described herein represent a new series of selective ligands of the adenosine A2A receptors exhibiting bronchospasmolytic activity. The effects of location of 8-phenyl substitutions on the adenosine receptor (AR) binding affinities of the newly synthesized xanthines have also been studied. The compounds displayed moderate to potent binding affinities toward various adenosine receptor subtypes when evaluated through radioligand binding studies. However, most of the compounds showed the maximum affinity for the A2A subtype, some with high selectivity versus all other subtypes. Xanthine carboxylate amide 13b with a diethylaminoethylamino moiety at the para-position of the 8-phenylxanthine scaffold was identified as the most potent A2A adenosine receptor ligand with Ki=0.06μM. Similarly potent and highly A2A-selective are the isovanillin derivatives 16a and 16d. In addition, the newly synthesized xanthine derivatives showed good in vivo bronchospasmolytic activity when tested in guinea pigs. PMID:26851736

  15. /sup 14/CO/sub 2/ ratios method for detecting pyruvate carboxylation

    SciTech Connect

    Kelleher, J.K.; Bryan, B.M. III

    1985-11-15

    The pattern of oxidative metabolism of pyruvate may be assessed by comparing the steady-state /sup 14/CO/sub 2/ production from four isotopes in identical samples. The assay requires measuring the ratios of steady-state /sup 14/CO/sub 2/ production from two isotope pairs, (2-/sup 14/C)pyruvate:(3-/sup 14/C)pyruvate and (1-/sup 14/C)acetate:(2-/sup 14/C)acetate. These ratios are defined as the ''pyruvate /sup 14/CO/sub 2/ ratio'' and the ''acetate /sup 14/CO/sub 2/ ratio,'' respectively. If pyruvate is metabolized exclusively via pyruvate dehydrogenase (PDH), the two ratios will be identical. Alternatively, if any pyruvate enters the tricarboxylic acid (TCA) cycle via pyruvate carboxylation (PC), the pyruvate /sup 14/CO/sub 2/ ratio will be less than the acetate /sup 14/CO/sub 2/ ratio. If pyruvate enters the TCA cycle only through PC (with oxaloacetate and fumarate in equilibrium) the pyruvate /sup 14/CO/sub 2/ ratio will approach a value of 1.0. An equation is presented for the quantitative evaluation of pyruvate oxidation by these two pathways. We have used this method to detect relative changes in the pattern of pyruvate metabolism in rat liver mitochondria produced by exposure to 1 mM octanoyl carnitine, a compound known to alter the PC:PDH activity ratio. The major advantages of the method are (i) that it provides a sensitive method for detecting pyruvate carboxylation at physiological pyruvate concentrations and (ii) that it provides a method for distinguishing between effects on pyruvate transport and effects on pyruvate oxidation.

  16. Selective protection and relative importance of the carboxylic acid groups of zaragozic acid A for squalene synthase inhibition.

    PubMed

    Biftu, T; Acton, J J; Berger, G D; Bergstrom, J D; Dufresne, C; Kurtz, M M; Marquis, R W; Parsons, W H; Rew, D R; Wilson, K E

    1994-02-01

    Chemistry that allows selective modification of the carboxylic acid groups of the squalene synthase inhibitor zaragozic acid A (1) was developed and applied to the synthesis of compounds modified at the 3-,4-,5-,3,4-,3,5-, and 4,5-positions. A key step in this procedure is the selective debenzylation by transfer hydrogenolysis in the presence of other olefinic groups. These compounds were tested in the rat squalene synthase assay and in vivo mouse model. Modification at C3 retains significant enzyme potency and enhances oral activity, indicating that C3 is not essential for squalene synthase activity. Modification at C4 and C5 results in significant loss in enzyme activity. In contrast, substitution at C3 or C4 enhances in vivo activity. Furthermore, disubstitution at the C3 and C4 positions results in additive in vivo potency. PMID:8308869

  17. Multipurpose Compound

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Specially formulated derivatives of an unusual basic compound known as Alcide may be the answer to effective treatment and prevention of the disease bovine mastitis, a bacterial inflammation of a cow's mammary gland that results in loss of milk production and in extreme cases, death. Manufactured by Alcide Corporation the Alcide compound has killed all tested bacteria, virus and fungi, shortly after contact, with minimal toxic effects on humans or animals. Alcide Corporation credits the existence of the mastitis treatment/prevention products to assistance provided the company by NERAC, Inc.

  18. Hydrothermal synthesis and structural characterization of ammonium ion-templated lanthanide(III) carboxylate-phosphonates

    PubMed Central

    Ayi, Ayi A.; Kinnibrugh, Tiffany L.; Clearfield, Abraham

    2014-01-01

    Using N-(phosphonomethyl) iminodiacetic acid (H4PMIDA), as a complexing agent, two new complexes, (NH4)La(PMIDA)(H2O)•H2O, 1 and (NH4)Yb(PMIDA), 2 have been synthesized hydrothermally. In both compounds, the metal ions are trapped by a three five-membered chelate rings by the chelating PMIDA anions giving a tricapped trigonal prismatic LaO8N and monocapped trigonal prismatic YbO6N geometries for 1 and 2, respectively. The structure of 1 consists of La(PMIDA)(H2O) chelating units, linked together by the phosphonate oxygen atoms O1 and O3 to form a chain along the c-axis. The chains are then connected together by the bridging phosphonate oxygen O2 to form a 2D layered structure with alternating 4- and 8-membered apertures. The structure of 2 consists Yb(PMIDA) chelating units, which are connected by alternating bridging carboxylate and phosphonate groups along the [010] direction forming chains with a corrugated pattern. The third phosphonate oxygen bridges the chains together along the [001] direction to build the two-dimensional layer with 4- and 6-membered apertures in the bc-plane. Under excitation of 330 nm, compound 2 shows a broad emission band at λmax = 460 nm. This emission is essentially in the blue luminescent region, which corresponds to ligand centered fluorescence. PMID:25414845

  19. Structure of eight molecular salts assembled from noncovalent bonding between carboxylic acids, imidazole, and benzimidazole

    NASA Astrophysics Data System (ADS)

    Jin, Shouwen; Zhang, Huan; Liu, Hui; Wen, Xianhong; Li, Minghui; Wang, Daqi

    2015-09-01

    Eight organic salts of imidazole/benzimidazole have been prepared with carboxylic acids as 2-methyl-2-phenoxypropanoic acid, α-ketoglutaric acid, 5-nitrosalicylic acid, isophthalic acid, 4-nitro-phthalic acid, and 3,5-dinitrosalicylic acid. The eight crystalline forms reported are proton-transfer compounds of which the crystals and compounds were characterized by X-ray diffraction analysis, IR, mp, and elemental analysis. These structures adopted hetero supramolecular synthons, with the most common R22(7) motif observed at salts 2, 3, 5, 6 and 8. Analysis of the crystal packing of 1-8 suggests that there are extensive strong Nsbnd H⋯O, and Osbnd H⋯O hydrogen bonds (charge assisted or neutral) between acid and imidazolyl components in all of the salts. Except the classical hydrogen bonding interactions, the secondary propagating interactions also play important roles in structure extension. This variety, coupled with the varying geometries and number of acidic groups of the acids utilized, has led to the creation of eight supramolecular arrays with 1D-3D structure. The role of weak and strong noncovalent interactions in the crystal packing is analyzed. The results presented herein indicate that the strength and directionality of the Nsbnd H⋯O, and Osbnd H⋯O hydrogen bonds between acids and imidazole/benzimidazole are sufficient to bring about the formation of organic salts.

  20. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2001-01-01

    Seawater and natural brines accounted for about 63% of US magnesium compounds production during 2000. Premier Services in Florida, Dow Chemical in Michigan, Martin Marietta Magnesia Specialties, and Rohm & Haas recovered dead-burned and caustic-calcined magnesias from seawater. And Premier Services' recoveries, in Nevada, were from magnasite.

  1. Simultaneous determination of Δ9-tetrahydrocannabinol, cannabidiol, cannabinol and 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid in hair using liquid chromatography-tandem mass spectrometry.

    PubMed

    Dulaurent, S; Gaulier, J M; Imbert, L; Morla, A; Lachâtre, G

    2014-03-01

    For several years, hair analyses have become a powerful tool to investigate past exposure towards xenobiotics. In the case of illicit drugs and more precisely of cannabis exposure, four compounds are usually investigated: Δ(9)-tetrahydrocannabinol (THC), the main active compound of cannabis, one of its metabolites [11-nor-Δ(9)-tetrahydrocannabinol-9-carboxylic acid (THC-COOH)] and two cannabinoids (cannabinol and cannabidiol). Up until now, the hair determination of the carboxylic metabolite of THC, which has been described as the only marker allowing distinguishing consumption and passive exposure, has been performed using a gas chromatography-tandem mass spectrometry method. The aim of this study was to develop a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous quantitative determination of the four markers. The sample preparation was based on an alkaline hydrolysis of hair samples followed by a liquid-liquid extraction of compounds in acidic conditions using a hexane/ethyl acetate mixture. The method was validated and the results were satisfactory: intra- and inter-assay accuracies below 9% and relative standard deviation below 15% for the four compounds. Moreover, the limit of quantification for THC-COOH, the most challenging compound, was validated at 0.2 pg/mg. This concentration is in accordance with the recommendations made by a scientific society which specializes in hair testing. It makes it possible to distinguish the kind of exposure to cannabis. PMID:24529787

  2. (±)-trans-3-Oxo-1,2,3,4,4a,9,10,10a-octa­hydro­phenanthrene-10a-carboxylic acid: catemeric hydrogen bonding in a δ-keto acid

    PubMed Central

    Davison, Mark; Lalancette, Roger A.; Thompson, Hugh W.; Miller, Alan J.

    2008-01-01

    The title compound, C15H16O3, aggregates as hydrogen-bonded catemers progressing from each carboxyl to the ketone of a screw-related neighbor [O⋯O = 2.6675 (14) Å and O—H⋯O = 170°]. Two parallel centrosymmetrically related single-strand hydrogen-bonding helices proceed through the cell in the b-axis direction. The packing includes three inter­molecular C—H⋯O=C close contacts, involving both the ketone and the carboxyl group. The structure is isomorphous with that of the previously described Δ4 α,β-unsaturated ketone. PMID:21201790

  3. Synthesis and properties of the derivatives of 2-alkylthio-4-oxo-3,4- (and -1,4)-dihydropyrido-[2,3-d]pyrimidine-5- and -6-carboxylic acids.

    PubMed

    Sladowska, H; Bartoszko-Malik, A; Zawisza, T

    1990-01-01

    Condensation of diethyl 2-amino-6-methylpyridine-3,4-dicarboxylate (I) with the corresponding isothiocyanates afforded derivatives of ethyl 4-oxo-2-thioxo-1,2,3,4-tetrahydropyrido [2,3-d]pyrimidine-5-carboxylate (V-VII). Alkylation of (V), (VI) and (XI) gave the corresponding derivatives of ethyl 2-alkylthio-4-oxo-3,4-(and 1,4)-dihydropyrido[2,3-d]pyrimidine-5- and -6- carboxylate [(XII-XVI), (XX-XXII)]. Some of the obtained compounds were active pharmacologically. PMID:2337442

  4. Propeptide of human protein C is necessary for. gamma. -carboxylation

    SciTech Connect

    Foster, D.C.; Rudinski, M.S.; Schach, B.G.; Berkner, K.L.; Kumar, A.A.; Hagen, F.S.; Sprecher, C.A.; Insley, M.Y.; Davie, E.W.

    1987-11-03

    Protein C is one of a family of vitamin K dependent proteins, including blood coagulation factors and bone proteins, that contains ..gamma..-carboxyglutamic acid. Sequence analysis of the cDNAs for these proteins has revealed the presence of a prepro leader sequence that contains a pre sequence or hydrophobic signal sequence and a propeptide containing a number of highly conserved amino acids. The pre region is removed from the growing polypeptide chain by signal peptidase, while the pro region is subsequently removed from the protein prior to secretion. In the present study, deletion mutants have been constructed in the propeptide region of the cDNA for human protein C, and the cDNAs were then expressed in mammalian cell culture. These deletions included the removal of 4, 9, 12, 15, 16, or 17 amino acids comprising the carboxyl end of the leader sequence of 42 amino acids. The mutant proteins were then examined by Western blotting, barium citrate adsorption and precipitation, amino acid sequence analysis, and biological activity and compared with the native protein present in normal plasma. These experiments have shown that protein C is readily synthesized in mammalian cell cultures, processed, and secreted as a two-chain molecule with biological activity. Furthermore, the pre portion or signal sequence in human protein C is 18 amino acids in length, and the pro portion of the leader sequence is 24 amino acids in length. Also, during biosynthesis and secretion, the amino-terminal region of the propeptide (residues from about -12 through -17) is important for ..gamma..-carboxylation of protein C, while the present data and those of others indicate that the carboxyl-terminal portion of propeptide (residues -1 through -4) is important for the removal of the pro leader sequence by proteolytic processing.

  5. R22(8) motifs in Aminopyrimidine sulfonate/carboxylate interactions: Crystal structures of pyrimethaminium benzenesulfonate monohydrate (2:2:1) and 2-amino-4,6-dimethylpyrimidinium sulfosalicylate dihydrate (4:2:2)

    PubMed Central

    Balasubramani, Kasthuri; Muthiah, Packianathan Thomas; Lynch, Daniel E

    2007-01-01

    Background Pyrimethamine [2,4-diamino-5-(p-chlorophenyl)-6-ethylpyrimidine] is an antifolate drug used in anti-malarial chemotherapy. Pyrimidine and aminopyrimidine derivatives are biologically important compounds owing to their natural occurrence as components of nucleic acids. Results In the crystal structures of two organic salts, namely pyrimethaminium benzenesulfonate monohydrate 1 and 2-amino-4, 6-dimethylpyrimidinium 3-carboxy-4-hydroxy benzenesulfonate dihydrate 2, pyrimethamine (PMN) and 2-amino-4,6-dimethylpyrimidine (AMPY) are protonated at one of the nitrogens in the pyrimidine rings. In both the PMN and AMPY sulfonate complexes, the protonated pyrimidine rings are hydrogen bonded to the sulfonate groups, forming a hydrogen-bonded bimolecular ring motif with graph-set notation R22(8). The sulfonate group mimics the carboxylate anion's mode of association, which is more commonly seen when binding with 2-aminopyrimidines. In compound 1, the PMN moieties are centrosymmetrically paired through a complementary DADA array of hydrogen bonds. In compound 2, two types of bimolecular cyclic hydrogen bonded R22(8) motifs (one involving the carboxylate group and the other involving sulfonate group) coexist. Furthermore, this compound is stabilized by intra and intermolecular O-H...O hydrogen bonds. Conclusion The crystal structures of pyrimethaminium benzenesulfonate monohydrate and 2-amino-4,6-dimethylpyrimidinium sulfosalicylate dihydrate have been investigated in detail. In compound 1, the R22(8) motif involving the sulfonate group is present. The role the sulfonic acid group plays in mimicking the carboxylate anions is thus evident. In compound 2, two types of bimolecular cyclic hydrogen bonded R22(8) motifs (one involving the carboxylate group and the other involving sulfonate group) coexist. In both the compounds base pairing also occurs. Thus homo and hetero synthons are present. PMID:17999751

  6. Toxicity of perfluorinated carboxylic acids for aquatic organisms.

    PubMed

    Tichý, Miloň; Valigurová, Radka; Cabala, Radomír; Uzlová, Rut; Rucki, Marián

    2010-06-01

    Toxicity of perfluorinated carboxylic acids with carbon chain C(8) to C(12) were tested with oligochaeta Tubifex tubifex. Toxicity was evaluated as the exposure time ET(50) from onset of damage of the oligochaeta in saturated aqueous solutions. The ET(50) fluctuated between 25 and 257 minutes. No statistically significant difference was found among the C(8), C(9) and C(12) acids (ET(50) between 143 and 257 minutes with large standard deviation). The acids with carbon chain C(10) and C(11) induced the effect significantly quicker (25 to 47 minutes). No acute toxicity measured in the three-minute test was observed in any case. PMID:21217876

  7. Two Dimensional Polyamides Prepared From Unsaturated Carboxylic Acids And Amines.

    DOEpatents

    McDonald, William F.; Huang, Zhi Heng; Wright, Stacy C.; Danzig, Morris; Taylor, Andrew C.

    2002-07-17

    A polyamide and a process for preparing the polyamide are disclosed. The process comprises reacting in a reaction mixture a monomer selected from unsaturated carboxylic acids, esters of unsaturated carboxylic acids, anhydrides of unsaturated carboxylic acids, and mixtures thereof, and a first amine to form an intermediate reaction product in the reaction mixture, wherein the first amine is selected from RR.sub.1 NH, RNH.sub.2, RR.sub.1 NH.sub.2.sup.+, RNH.sub.3.sup.+ and mixtures thereof, wherein R and R.sub.1 can be the same or different and each contain between about 1 and 50 carbon atoms and are optionally substituted with heteroatoms oxygen, nitrogen, sulfur, and phosphorus and combinations thereof, and reacting the intermediate reaction product and a second amine to form a polyamide, wherein the second amine is selected from R.sub.2 R.sub.3 NH, R.sub.2 NH.sub.2, R.sub.2 R.sub.3 NH.sub.2.sup.+, R.sub.2 NH.sub.3.sup.+ and mixtures thereof wherein R.sub.2 and R.sub.3 can be the same or different and each contain between about 1 and 50 carbon atoms and are optionally substituted with heteroatoms oxygen, nitrogen, sulfur, and phosphorus and combinations thereof, wherein multiple of the R, R.sub.1, R.sub.2, and R.sub.3 are in vertically aligned spaced relationship along a backbone formed by the polyamide. In one version of the invention, the monomer is selected from maleic anhydride, maleic acid esters, and mixtures thereof. In another version of the invention, the first amine is an alkylamine, such as tetradecylamine, and the second amine is a polyalkylene polyamine, such as pentaethylenehexamine. In yet another version of the invention, the first amine and the second amine are olefinic or acetylenic amines, such as the reaction products of an alkyldiamine and an acetylenic carboxylic acid. The first amine and the second amine may be the same or different depending on the desired polyamide polymer structure.

  8. Approaches for regeneration of amine-carboxylic acid extracts

    SciTech Connect

    Dai, Y.; King, C.J.

    1995-07-01

    Extraction processes based on reversible chemical complexation can be useful for separation of polar organics from dilute solution. Tertiary amines are effective extractants for the recovery of carboxylic acids from aqueous solution. The regeneration of aminecarboxylic acid extracts is an important step which strongly influences the economic viability of the separation process. Several regeneration methods are critically reviewed, and the factors that affect swing regeneration processes, including temperature-swing, diluent composition-swing and pH-swing with a volatile base are discussed. Interest in this area comes from interest in treatment of waste streams, particularly in petrochemical and fermentation manufacture.

  9. Pharmacological investigations and Petra/Osiris/Molinspiration (POM) analyses of newly synthesized potentially bioactive organotin(IV) carboxylates.

    PubMed

    Tariq, Muhammad; Sirajuddin, Muhammad; Ali, Saqib; Khalid, Nasir; Tahir, Muhammad Nawaz; Khan, Hizbullah; Ansari, Tariq Mahmood

    2016-05-01

    A series of organotin(IV) carboxylate complexes: [Me2SnL2] (1), [n-Bu2SnL2] (2), [n-Oct2SnL2] (3), [Me3SnL] (4), [n-Bu3SnL] (5) and [Ph3SnL] (6), where L=3-(4-fluorophenyl)acrylic acid, have been successfully synthesized and characterized by FT-IR, NMR ((1)H, (13)C) and single crystal analysis. The ligand coordinates to tin atom via carboxylate group. Compound 4 was also analyzed by single crystal XRD analysis. Crystallographic data for trimethyltin(IV) complex showed that the tin has approximate trigonal bipyramidal geometry with the CH3 groups in the trigonal plane. The carboxylate groups bridge the adjacent tin atoms, resulting in polymeric chains. FT-IR and NMR data also support the 5-coordination geometry for the triorganotin(IV) derivatives. In the case of the diorganotin(IV) derivatives a six-coordinate geometry at the tin atom is proposed from spectroscopic data. The Me-Sn-Me bond angle in complexes 1 and 4 was determined from the (2)J[(119)Sn-(1)H] value as 138.4° and 111° that falls in the range of 5-coordinated trigonal bipyramidal and 6-coordinated octahedral geometries, respectively. The synthesized compounds were screened for their biological activities including antibacterial, antifungal and cytotoxicity. The compounds 4-6 exhibit excellent antibacterial, antifungal and cytotoxic activities. The cytotoxicity data reveals that the HL and 1-3 are almost non-toxic and exhibited LD50 values in the range 73.45-675.1μg/mL while 4-6 are found to be cytotoxic to mildly cytotoxic with LD50 values in the range 6.43-13.49μg/mL. The compound interacts with DNA via intercalation of aromatic ring into the base pairs of DNA resulting in hypochromism and minor red shift. PMID:26974578

  10. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2003-01-01

    Seawater and natural brines accounted for about 60 percent of U.S. magnesium compounds production during 2002. Dead-burned and caustic-calcined magnesias were recovered from seawater by Premier Chemicals in Florida. They were also recovered from well brines in Michigan by Dow Chemical, Martin Marietta Magnesia Specialties and Rohm & Haas. And they were recovered from magnesite in Nevada by Premier Chemicals.

  11. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2006-01-01

    In 2005, seawater and natural brines accounted for 51% of US magnesium compounds production. World magnesia production was estimated to be 14.5 Mt. Most of the production came from China, North Korea, Russia and Turkey. Although no specific production figures are available, Japan and the United States are estimated to account for almost one-half of the world's capacity from seawater and brines.

  12. Metal Azolate/Carboxylate Frameworks as Catalysts in Oxidative and C-C Coupling Reactions.

    PubMed

    Tăbăcaru, Aurel; Xhaferaj, Nertil; Martins, Luísa M D R S; Alegria, Elisabete C B A; Chay, Rogério S; Giacobbe, Carlotta; Domasevitch, Konstantin V; Pombeiro, Armando J L; Galli, Simona; Pettinari, Claudio

    2016-06-20

    The five metal azolate/carboxylate (MAC) compounds [Cd(dmpzc)(DMF)(H2O)] (Cd-dmpzc), [Pd(H2dmpzc)2Cl2] (Pd-dmpzc), [Cu(Hdmpzc)2] (Cu-dmpzc), [Zn4O(dmpzc)3]·Solv (Zn-dmpzc·S), and [Co4O(dmpzc)3]·Solv (Co-dmpzc·S) were isolated by coupling 3,5-dimethyl-1H-pyrazol-4-carboxylic acid (H2dmpzc) to cadmium(II), palladium(II), copper(II), zinc(II), and cobalt(II) salts. While Cd-dmpzc and Pd-dmpzc had never been prepared in the past, for Cu-dmpzc, Zn-dmpzc·S, and Co-dmpzc·S we optimized alternative synthetic paths that, in the case of the copper(II) and cobalt(II) derivatives, are faster and grant higher yields than the previously reported ones. The crystal structure details were determined ab initio (Cd-dmpzc and Pd-dmpzc) or refined (Cu-dmpzc, Zn-dmpzc·S, and Co-dmpzc·S) by means of powder X-ray diffraction (PXRD). While Cd-dmpzc is a nonporous 3D MAC framework, Pd-dmpzc shows a 3D hybrid coordination/hydrogen-bonded network, in which Pd(H2dmpzc)2Cl2 monomers are present. The thermal behavior of the five MAC compounds was investigated by coupling thermal analysis to variable-temperature PXRD. Their catalytic activity was assessed in oxidative and C-C coupling reactions, with the copper(II) and cadmium(II) derivatives being the first nonporous MAC frameworks to be tested as catalysts. Cu-dmpzc is the most active catalyst in the partial oxidation of cyclohexane by tert-butyl hydroperoxide in acetonitrile (yields up to 12% after 9 h) and is remarkably active in the solvent-free microwave-assisted oxidation of 1-phenylethanol to acetophenone (yields up to 99% at 120 °C in only 0.5 h). On the other hand, activated Zn-dmpzc·S (Zn-dmpzc) is the most active catalyst in the Henry C-C coupling reaction of aromatic aldehydes with nitroethane, showing appreciable diastereoselectivity toward the syn-nitroalkanol isomer (syn:anti selectivity up to 79:21). PMID:27266480

  13. Degradation of halogenated aliphatic compounds by Xanthobacter autotrophicus GJ10.

    PubMed Central

    Janssen, D B; Scheper, A; Dijkhuizen, L; Witholt, B

    1985-01-01

    A bacterium that is able to utilize a number of halogenated short-chain hydrocarbons and halogenated carboxylic acids as sole carbon source for growth was identified as a strain of Xanthobacter autotrophicus. The organism constitutively produces two different dehalogenases. One enzyme is specific for halogenated alkanes, whereas the other, which is more heat stable and has a higher pH optimum, is specific for halogenated carboxylic acids. Haloalkanes were hydrolyzed in cell extracts to produce alcohols and halide ions, and a route for the metabolism of 1,2-dichlorethane is proposed. Both dehalogenases show a broad substrate specificity, allowing the degradation of bromine- and chlorine-substituted organic compounds. The results show that X. autotrophicus may play a role in the degradation of organochlorine compounds and that hydrolytic dehalogenases may be involved in the microbial metabolism of short-chain halogenated hydrocarbons in microorganisms. Images PMID:3994371

  14. Complexes of carboxyl-containing polymer and monosubstituted bipyridinium salts

    NASA Astrophysics Data System (ADS)

    Merekalova, N. D.; Bondarenko, G. N.; Krylsky, D. W.; Zakirov, M. I.; Talroze, R. V.

    2013-09-01

    Semi-empirical PM3 method for the quantum calculations of molecular electronic structure based on NDDO integral approximation is used to investigate the complex formation of monosubstituted 4,4‧-bipyridinium salts BpyR (Hal) containing a halide anion interacting with the quaternary nitrogen atom and carboxylic group of the two-units construct. Significant effect of the BpyR (Hal) electronic structure is unveiled that contributes in two different structures of these salts, namely, partial charge transfer complex and ion pair structure, both having stable energy minima. We demonstrate that (i) the structure of the N-substituent modulates the energy and electronic characteristics of monosubstituted salts BpyR with chlorine and bromine anions and (ii) the coulomb interactions between quaternary N-atom, halogen anion, and the proton of carboxylic group stimulate the transformation of the charge transfer complex into the ion pair structure. Results of calculations are compared with the experimental FTIR spectra of blends of BpyR(Hal) with Eudragit copolymer.

  15. Thermal decomposition of carboxylate ionic liquids: trends and mechanisms.

    PubMed

    Clough, Matthew T; Geyer, Karolin; Hunt, Patricia A; Mertes, Jürgen; Welton, Tom

    2013-12-21

    The thermal stability of a series of dialkylimidazolium carboxylate ionic liquids has been investigated using a broad range of experimental and computational techniques. Ionic liquids incorporating fluoroalkyl carboxylate anions were found to have profoundly differing thermal stabilities and decomposition mechanisms compared with their non-fluorinated analogues. 1-Ethyl-3-methylimidazolium acetate was observed to largely decompose via an S(N)2 nucleophilic substitution reaction when under inert gas conditions, predominantly at the imidazolium methyl substituent. The Arrhenius equations for thermal decomposition of 1-ethyl-3-methylimidazolium acetate, and the C(2)-methylated analogue 1-ethyl-2,3-dimethylimidazolium acetate, were determined from isothermal Thermogravimetric Analysis experiments. The low thermal stability of 1-ethyl-3-methylimidazolium acetate has important implications for biomass experiments employing this ionic liquid. For these two ionic liquids, ion pair and transition state structures were optimised using Density Functional Theory. The activation barriers for the S(N)2 nucleophilic substitution mechanisms are in good agreement with the experimentally determined values. PMID:24173605

  16. Integrated process for preparing a carboxylic acid from an alkane

    DOEpatents

    Benderly, Abraham; Chadda, Nitin; Sevon, Douglass

    2011-12-20

    The present invention relates to an integrated process for producing unsaturated carboxylic acids from the corresponding C.sub.2-C.sub.4 alkane. The process begins with performance of thermally integrated dehydrogenation reactions which convert a C.sub.2-C.sub.4 alkane to its corresponding C.sub.2-C.sub.4 alkene, and which involve exothermically converting a portion of an alkane to its corresponding alkene by oxidative dehydrogenation in an exothermic reaction zone, in the presence of oxygen and a suitable catalyst, and then feeding the products of the exothermic reaction zone to an endothermic reaction zone wherein at least a portion of the remaining unconverted alkane is endothermically dehydrogenated to form an additional quantity of the same corresponding alkene, in the presence of carbon dioxide and an other suitable catalyst. The alkene products of the thermally integrated dehydrogenation reactions are then provided to a catalytic vapor phase partial oxidation process for conversion of the alkene to the corresponding unsaturated carboxylic acid or nitrile. Unreacted alkene and carbon dioxide are recovered from the oxidation product stream and recycled back to the thermally integrated dehydrogenation reactions.

  17. Reductive Carboxylation of Propionate to Butyrate in Methanogenic Ecosystems

    PubMed Central

    Tholozan, J. L.; Samain, E.; Grivet, J. P.; Moletta, R.; Dubourguier, H. C.; Albagnac, G.

    1988-01-01

    During the batch degradation of sodium propionate by the anaerobic sludge from an industrial digestor, we observed a significant amount of butyrate formation. Varying the initial propionate concentrations did not alter the ratio of maximal butyrate accumulation to initial propionate concentration within a large range. By measuring the decrease in the radioactivity of [1-14C]butyrate during propionate degradation, we estimated that about 20% of the propionate was converted to butyrate. Labeled butyrate was formed from [1-14C]propionate with the same specific radioactivity, suggesting a possible direct pathway from propionate to butyrate. We confirmed this hypothesis by nuclear magnetic resonance studies with [13C]propionate. The results showed that [1-13C]-, [2-13C]-, and [3-13C]propionate were converted to [2-13C]-, [3-13C]-, and [4-13C]butyrate, respectively, demonstrating the direct carboxylation on the carboxyl group of propionate without randomization of the other two carbons. In addition, we observed an exchange reaction between C-2 and C-3 of the propionate, indicating that acetogensis may proceed through a randomizing pathway. The physiological significance and importance of various metabolic pathways involved in propionate degradation are discussed, and an unusual pathway of butyrate synthesis is proposed. PMID:16347557

  18. Adsorption behavior of epirubicin hydrochloride on carboxylated carbon nanotubes.

    PubMed

    Chen, Zhe; Pierre, Dramou; He, Hua; Tan, Shuhua; Pham-Huy, Chuong; Hong, Hao; Huang, Jilong

    2011-02-28

    The aim of this study was to understand the interaction between carboxylated carbon nanotubes (c-CNTs) and anticancer agents and evaluate the drug-loading ability of c-CNTs. We prepared carboxylated multi-walled carbon nanotubes (c-MWNTs) with nitric acid treatment, then evaluated the adsorption ability of c-MWNTs as adsorbents for loading of the anticancer drug, epirubicin hydrochloride (EPI), and investigated the adsorption behavior of EPI on c-MWNTs. Unmodified multi-walled carbon nanotubes (MWNTs) and single-walled carbon nanotubes (SWNTs) were included as comparative adsorbents. The results showed that carbon nanotubes were able to form supramolecular complexes with EPI via π-π stacking and possessed favorable loading properties as drug carriers. The Freundilich adsorption model was successfully employed to describe the adsorption process. Because of the high surface area and hydrogen bonding, c-MWNTs' adsorption efficiency was the highest and the most stable and their drug-loading capacity was superior to that of MWNTs. With the increase of pH, the adsorption capacity of EPI on the c-MWNTs increased. Low-temperature facilitated the adsorption. More rapid EPI adsorption rate and higher drug-loading ability were observed from c-MWNTs with smaller diameter. Moreover, the adsorption kinetics of EPI on c-MWNTs could be well depicted by using the pseudo-second-order kinetic model. PMID:21145959

  19. An efficient chemical synthesis of carboxylate-isostere analogs of daptomycin

    PubMed Central

    Yoganathan, Sabesan; Yin, Ning; He, Yong; Mesleh, Michael; Gu, Yu Gui; Miller, Scott J.

    2014-01-01

    Herein we report a direct and efficient method for the synthesis of four new carboxylate-isostere analogs of daptomycin. The side chain carboxylic acid moieties of the aspartic acids (Asp-3, Asp-7 and Asp-9) and β-methyl glutamic acid (MeGlu-12) were all converted into the corresponding carboxylate isosteres using direct synthetic procedures. The present study also describes an esterification protocol to overcome the possible backbone cyclization of the activated side chain carboxylic acid group of either Asp or Glu, onto the backbone amide. PMID:23752953

  20. Trace Amounts of Furan-2-Carboxylic Acids Determine the Quality of Solid Agar Plates for Bacterial Culture

    PubMed Central

    Hara, Shintaro; Isoda, Reika; Tahvanainen, Teemu; Hashidoko, Yasuyuki

    2012-01-01

    Background Many investigators have recognised that a significant proportion of environmental bacteria exist in a viable but non-culturable state on agar plates, and some researchers have also noticed that some of such bacteria clearly recover their growth on matrices other than agar. However, the reason why agar is unsuitable for the growth of some bacteria has not been addressed. Methodology/Principal Findings According to the guide of a bioassay for swarming inhibition, we identified 5-hydroxymethylfuran-2-carboxylic acid (5-HMFA) and furan-2-carboxylic acid (FA) as factors that inhibit bacterial swarming and likely inhibit extracellular polysaccharide production on agar. The furan-2-carboxylic acids 5-HMFA and FA effectively inhibited the swarming and swimming of several environmental bacteria at concentrations of 1.8 and 2.3 µg L−1 (13 and 21 nmol L−1), respectively, which are equivalent to the concentrations of these compounds in 0.3% agar. On Luria-Bertani (LB) plates containing 1.0% agar that had been previously washed with MeOH, a mixture of 5-HMFA and FA in amounts equivalent to their original concentrations in the unwashed agar repressed the swarming of Escherichia coli K12 strain W3110, a representative swarming bacterium. Conclusions/Significance Agar that contains trace amounts of 5-HMFA and FA inhibits the proliferation of some slow-growing or difficult-to-culture bacteria on the plates, but it is useful for single colony isolation due to the ease of identification of swarmable bacteria as the non-swarmed colonies. PMID:22848437

  1. 5-Aryl-1H-pyrazole-3-carboxylic acids as selective inhibitors of human carbonic anhydrases IX and XII.

    PubMed

    Cvijetić, Ilija N; Tanç, Muhammet; Juranić, Ivan O; Verbić, Tatjana Ž; Supuran, Claudiu T; Drakulić, Branko J

    2015-08-01

    Inhibitory activity of a congeneric set of 23 phenyl-substituted 5-phenyl-pyrazole-3-carboxylic acids toward human carbonic anhydrase (hCA, EC 4.2.1.1) isoforms I, II, IX and XII was evaluated by a stopped-flow CO2 hydrase assay. These compounds exerted a clear, selective inhibition of hCA IX and XII over hCAI and II, with Ki in two to one digit micromolar concentrations (4-50 μM). Derivatives bearing bulkier substituents in para-position of the phenyl ring inhibited hCA XII at one-digit micromolar concentrations, while derivatives having alkyl substituents in both ortho- and meta-positions inhibited hCA IX with Kis ranging between 5 and 25 μM. Results of docking experiments offered a rational explanation on the selectivity of these compounds toward CA IX and XII, as well as on the substitution patterns leading to best CA IX or CA XII inhibitors. By examining the active sites of these four isoforms with GRID generated molecular-interaction fields, striking differences between hCA XII and the other three isoforms were observed. The field of hydrophobic probe (DRY) appeared significantly different in CA XII active site, comparing to other three isoforms studied. To the best of our knowledge such an observation was not reported in literature so far. Considering the selectivity of these carboxylates towards membrane-associated over cytosolic CA isoforms, the title compounds could be useful for the development of isoform-specific non-sulfonamide CA inhibitors. PMID:26088336

  2. Perfluorinated carboxylic and sulphonic acids in surface water media from the regions of Tibetan Plateau: Indirect evidence on photochemical degradation?

    PubMed

    Yamazaki, Eriko; Falandysz, Jerzy; Taniyasu, Sachi; Hui, Ge; Jurkiewicz, Gabriela; Yamashita, Nobuyoshi; Yang, Yong-Liang; Lam, Paul K S

    2016-01-01

    Perfluorinated surfactants and repellents are synthetic substances that have found numerous industrial and customer applications. Due to their persistence, at least two groups of these substances-perfluorinated carboxylic acids (PFCAs) and perfluorinated sulfonic acids (PFSAs)-are diffused widely in the environment. It is hypothesized that the Tibetan Plateau, is one of few unique places on the Earth, due to its topography, specifically the vast space and high elevation above sea level, geographic location, climate, high solar radiation, lack of industry, little urbanization and general lack of significant direct sources of pollution. There it is believed possible to gain an insight into atmospheric fate (possible photochemical degradation of higher molecular mass and formation of lower molecular mass PFCAs and PFSAs) of PFASs under un-disturbed environmental conditions. Ultratrace analytical method for PFCAs and PFSAs and use of transportation and field blanks, laboratory blanks and isotopically labelled surrogates for recovery control has allowed the determination of nine perfluorinated carboxylic acids and six perfluorinated sulfonic acids at ultra-trace levels in water based samples from the alpine dimension regions of the Tibetan Plateau, the eastern slope of Minya Konka peak at the eastern edge of the Tibetan Plateau, and also from the city of Chengdu from the lowland of the Sichuan Province in China. The specific compositional pattern of PFCAs and PFSAs and low levels of pollution with those compounds were observed in the central region of the Tibetan Plateau and in the region adjacent to the peaks of Minya Konka in the Eastern Tibetan Plateau. The fingerprint of the compositional pattern of PFCAs and PFSAs in water samples in the central region of the Tibetan Plateau and in the alpine region adjacent to the peaks of Minya Konka in the Eastern Tibetan Plateau may be explained by the result of photochemical degradation with dealkylation of longer chain

  3. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2010-01-01

    Seawater and natural brines accounted for about 40 percent of U.S. magnesium compounds production in 2009. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties from well brines in Michigan. Caustic-calcined magnesia was recovered from seawater by Premier Chemicals in Florida, from well brines in Michigan by Martin Marietta and from magnesite in Nevada by Premier Chemicals. Intrepid Potash-Wendover, and Great Salt Lake Minerals Corp. recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from seawater by SPI Pharma in Delaware and Premier Chemicals in Florida, and by Martin Marietta from its operation mentioned above.

  4. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2002-01-01

    Seawater and natural brines accounted for about 60% of US magnesium compounds production in 2001. Dead-burned and caustic-calcined magnesias were recovered from seawater in Florida by Premier Chemicals. They were also recovered from Michigan well brines by Dow Chemical, Martin Marietta Magnesia Specialties and Rohm & Haas. And Premier Chemicals recovered dead-burned and caustic-calcined magnesias from magnesite in Nevada. Reilly Industries and Great Salt Lake Minerals recovered magnesium chloride brines from the Great Salt Lake in Utah.

  5. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2011-01-01

    Seawater and natural brines accounted for about 54 percent of U.S. magnesium compounds production in 2010. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties from well brines in Michigan. Caustic-calcined magnesia was recovered from seawater by Premier Magnesia in Florida, from well brines in Michigan by Martin Marietta and from magnesite in Nevada by Premier Magnesia. Intrepid Potash-Wendover and Great Salt Lake Minerals Corp. recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from seawater by SPI Pharma in Delaware and Premier Magnesia in Florida, and by Martin Marietta from its operation mentioned above.

  6. A comprehensive classification and nomenclature of carboxyl–carboxyl(ate) supramolecular motifs and related catemers: implications for biomolecular systems

    PubMed Central

    D’Ascenzo, Luigi; Auffinger, Pascal

    2015-01-01

    Carboxyl and carboxylate groups form important supramolecular motifs (synthons). Besides carboxyl cyclic dimers, carboxyl and carboxylate groups can associate through a single hydrogen bond. Carboxylic groups can further form polymeric-like catemer chains within crystals. To date, no exhaustive classification of these motifs has been established. In this work, 17 association types were identified (13 carboxyl–carboxyl and 4 carboxyl–carboxylate motifs) by taking into account the syn and anti carboxyl conformers, as well as the syn and anti lone pairs of the O atoms. From these data, a simple rule was derived stating that only eight distinct catemer motifs involving repetitive combinations of syn and anti carboxyl groups can be formed. Examples extracted from the Cambridge Structural Database (CSD) for all identified dimers and catemers are presented, as well as statistical data related to their occurrence and conformational preferences. The inter-carboxyl(ate) and carboxyl(ate)–water hydrogen-bond properties are described, stressing the occurrence of very short (strong) hydrogen bonds. The precise characterization and classification of these supramolecular motifs should be of interest in crystal engineering, pharmaceutical and also biomolecular sciences, where similar motifs occur in the form of pairs of Asp/Glu amino acids or motifs involving ligands bearing carboxyl(ate) groups. Hence, we present data emphasizing how the analysis of hydrogen-containing small molecules of high resolution can help understand structural aspects of larger and more complex biomolecular systems of lower resolution. PMID:25827369

  7. INTRACELLULAR ANTIOXIDANT ACTIVITY OF A STREPTOMYCES SP. 8812 SECONDARY METABOLITE, 6,7-DIHYDROXY-3,4-DIHYDROISOQINO- LINE-3-CARBOXYLIC ACID, AND ITS SYNTHETIC DERIVATIVES.

    PubMed

    Guśpiel, Adam; Ziemska, Joanna; Cześcik, Agnieszka; Kawecki, Robert; Solecka, Jolanta

    2016-01-01

    The aim of this study was to determine the antioxidant properties of 6,7-dihydroxy-3,4-dihydroiso- quinoline-3-carboxylic acid (1) and its derivatives in living cells against reactive forms of oxygen and nitrogen, i.e., hydrogen peroxide and nitric oxide. Four of tested compounds scavenged the reactive form of nitrogen more efficiently or similarly to Trolox (EC50 = 55.80 µM). Two compounds exhibited antioxidant activity against reactive oxygen species better than Trolox (EC50 = 51.88 µM). The most active derivative of 1 was the compound containing an iodine atom at position 8 (6,7-dihydroxy-8-iodo-3,4-dihydroisoquinoline-3-carboxylic acid). Our studies showed that some of the derivatives had the ability to cross the cell membrane and scavenge free radicals inside living cells. Thus, they are able to protect DNA and other cellular structures from the dam- aging effects of reactive oxygen and nitrogen species. In addition, some molecular descriptors of the tested compounds were determined with the use of ICM Pro (Molsoft L.L.C.). PMID:27476282

  8. Gas-Phase Spectroscopic Signatures of Carboxylate-Li(+) Contact Ion Pairs: New Benchmarks For Characterizing Ion Pairing in Solution.

    PubMed

    Habka, Sana; Brenner, Valérie; Mons, Michel; Gloaguen, Eric

    2016-04-01

    The coexistence of several types of ion pairs in solution together with their elusive nature hampers their experimental characterization, which relies in practice on theoretical models resorting to numerous approximations. In this context, a series of isolated contact ion pairs between a lithium cation and phenyl-tagged carboxylate anions of various lengths (Ph-(CH2)n-COO(-), n = 1-3) has been investigated in a conformer-selective manner by IR and UV laser spectroscopy, in conjunction with quantum chemistry calculations. The typical gas-phase IR signature of the bidentate structure formed between the carboxylate moiety and Li(+) has thus been obtained in the CO2(-) stretch region. In addition to the cation-anion interaction, a cation-π interaction occurs simultaneously in the largest system investigated (n = 3). The resulting distorted ion pair structure has been evidenced from both the IR signature of the CO2(-) stretches and the unique vibrationally resolved UV spectroscopy of a phenyl ring interacting with a cation. Such specific spectroscopic signatures of contact ion pairs provide experimental benchmarks, alternative to theoretical predictions, that can assist the assignment of vibrational spectra in solution. PMID:26978595

  9. Isolation of a Single Carboxyl-Carboxylate Proton Binding Site in the Pore of a Cyclic Nucleotide–Gated Channel

    PubMed Central

    Morrill, James A.; MacKinnon, Roderick

    1999-01-01

    The pore of the catfish olfactory cyclic nucleotide–gated (CNG) channel contains four conserved glutamate residues, one from each subunit, that form a high-affinity binding site for extracellular divalent cations. Previous work showed that these residues form two independent and equivalent high-pKa (∼7.6) proton binding sites, giving rise to three pH-dependent conductance states, and it was suggested that the sites were formed by pairing of the glutamates into two independent carboxyl-carboxylates. To test further this physical picture, wild-type CNG subunits were coexpressed in Xenopus oocytes with subunits lacking the critical glutamate residue, and single channel currents through hybrid CNG channels containing one to three wild-type (WT) subunits were recorded. One of these hybrid channels had two pH-dependent conductance states whose occupancy was controlled by a single high-pKa protonation site. Expression of dimers of concatenated CNG channel subunits confirmed that this hybrid contained two WT and two mutant subunits, supporting the idea that a single protonation site is made from two glutamates (dimer expression also implied the subunit makeup of the other hybrid channels). Thus, the proton binding sites in the WT channel occur as a result of the pairing of two glutamate residues. This conclusion places these residues in close proximity to one another in the pore and implies that at any instant in time detailed fourfold symmetry is disrupted. PMID:10398693

  10. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2007-01-01

    Seawater and natural brines accounted for about 52 percent of U.S. magnesium compounds production in 2006. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties from well brines in Michigan. Caustic-calcined magnesia was recovered from sea-water by Premier Chemicals in Florida; from well brines in Michigan by Martin Marietta and Rohm and Haas; and from magnesite in Nevada by Premier Chemicals. Intrepid Potash-Wendover and Great Salt Lake Minerals recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from brucite by Applied Chemical Magnesias in Texas, from seawater by SPI Pharma in Delaware and Premier Chemicals in Florida, and by Martin Marietta and Rohm and Haas from their operations mentioned above. About 59 percent of the magnesium compounds consumed in the United States was used for refractories that are used mainly to line steelmaking furnaces. The remaining 41 percent was consumed in agricultural, chemical, construction, environmental and industrial applications.

  11. Intermetallic Compounds

    NASA Astrophysics Data System (ADS)

    Takagiwa, Y.; Matsuura, Y.; Kimura, K.

    2014-06-01

    We have focused on the binary narrow-bandgap intermetallic compounds FeGa3 and RuGa3 as thermoelectric materials. Their crystal structure is FeGa3-type (tetragonal, P42/ mnm) with 16 atoms per unit cell. Despite their simple crystal structure, their room temperature thermal conductivity is in the range 4-5-W-m-1-K-1. Both compounds have narrow-bandgaps of approximately 0.3-eV near the Fermi level. Because their Seebeck coefficients are quite large negative values in the range 350-<-| S 373K|-<-550- μV-K-1 for undoped samples, it should be possible to obtain highly efficient thermoelectric materials both by adjusting the carrier concentration and by reducing the thermal conductivity. Here, we report the effects of doping on the thermoelectric properties of FeGa3 and RuGa3 as n and p-type materials. The dimensionless figure of merit, ZT, was significantly improved by substitution of Sn for Ga in FeGa3 (electron-doping) and by substitution of Zn for Ga in RuGa3 (hole-doping), mainly as a result of optimization of the electronic part, S 2 σ.

  12. Characterizations of organic compounds in diesel exhaust particulates.

    PubMed

    Lim, Jaehyun; Lim, Cheolsoo; Kim, Sangkyun; Hong, Jihyung

    2015-08-01

    To characterize how the speed and load of a medium-duty diesel engine affected the organic compounds in diesel particle matter (PM) below 1 μm, four driving conditions were examined. At all four driving conditions, concentration of identifiable organic compounds in PM ultrafine (34-94 nm) and accumulation (94-1000 nm) modes ranged from 2.9 to 5.7 μg/m(3) and 9.5 to 16.4 μg/m(3), respectively. As a function of driving conditions, the non-oxygen-containing organics exhibited a reversed concentration trend to the oxygen-containing organics. The identified organic compounds were classified into eleven classes: alkanes, alkenes, alkynes, aromatic hydrocarbons, carboxylic acids, esters, ketones, alcohols, ethers, nitrogen-containing compounds, and sulfur-containing compounds. At all driving conditions, alkane class consistently showed the highest concentration (8.3 to 18.0 μg/m(3)) followed by carboxylic acid, esters, ketones and alcohols. Twelve polycyclic aromatic hydrocarbons (PAHs) were identified with a total concentration ranging from 37.9 to 174.8 ng/m(3). In addition, nine nitrogen-containing polycyclic aromatic compounds (NPACs) were identified with a total concentration ranging from 7.0 to 10.3 ng/m(3). The most abundant PAH (phenanthrene) and NPACs (7,8-benzoquinoline and 3-nitrophenanthrene) comprise a similar molecular (3 aromatic-ring) structure under the highest engine speed and engine load. PMID:26257360

  13. Determination of carboxylic acids in water by gas chromatography-mass spectrometry after continuous extraction and derivatisation.

    PubMed

    Jurado-Sánchez, Beatriz; Ballesteros, Evaristo; Gallego, Mercedes

    2012-05-15

    This paper describes a new approach for the determination of monocarboxylic, dicarboxylic and tricarboxylic acids (35 compounds) in water. The analytes, in acid medium (pH ≈ 1.3), were sorbed on an 80 mg LiChrolut EN-Supelclean ENVI-18 (1:1) column and subsequently eluted with methanol. After evaporation of the extract to ≈ 10 μL, the analytes were spiked with 60 μL of the derivatising reagent and derivatised in a household microwave oven for 3 min. Among the reagents tested (BF(3)/1-butanol; acetyl chloride/1-butanol; isobutyl chloroformate/1-butanol; trimethylphenylammonium hydroxide, N,O-bis-(trimethylsilyl)acetamide, N,O-bis-(trimethylsilyl)trifluoroacetamide and trimethylchlorosilane), the best results in terms of reaction yield and stability of the derivatives were obtained with the mixture of 1% trimethylchlorosilane in N,O-bis-(trimethylsilyl)trifluoroacetamide. Microwave assisted derivatisation was used as an alternative heating approach for the rapid silylation of carboxylic acids. The proposed method proved to be a suitable analytical procedure for several types of carboxylic acids in water, with limits of detection within the range 0.6-15 ng L(-1), precision values from 4.0 to 6.0% (as within-day relative standard deviation) and recoveries from 93 to 101% for all the target analytes. PMID:22483903

  14. Structure of six anhydrous molecular salts assembled from noncovalent associations between carboxylic acids and bis-N-imidazoles

    NASA Astrophysics Data System (ADS)

    Jin, Shouwen; Guo, Ming; Wang, Daqi

    2012-08-01

    Six crystalline organic acid-base adducts derived from bis(N-imidazolyl) and carboxylic acids (3,5-dinitrobenzoic acid, 5-nitrosalicylic acid, 3,5-dinitrosalicylic acid, and phthalic acid) were prepared and characterized by X-ray diffraction analysis, IR, mp, and elemental analysis. The six compounds are all organic salts. In salts 1, 2, 4, 5, and 6 the corresponding bis(imidazole) derivatives are diprotonated, while in 3, the corresponding bis(imidazole) derivative is only monoprotonated. All supramolecular architectures of the salts 1-6 involve extensive Nsbnd H⋯O, Osbnd H⋯O, CH⋯O, and CH2⋯O hydrogen bonds as well as other noncovalent interactions. The role of weak and strong noncovalent interactions in the crystal packing is ascertained. All the salts displayed 3D framework structures under the cooperation of these weak interactions. The results presented herein indicate that the strength and directionality of the N+sbnd H⋯O-, Osbnd H⋯O, and Nsbnd H⋯N hydrogen bonds between carboxylic acids and ditopic imidazoles are sufficient to bring about the formation of binary organic salts.

  15. Distinguishing two groups of flavin reductases by analyzing the protonation state of an active site carboxylic acid.

    PubMed

    Dumit, Verónica I; Cortez, Néstor; Matthias Ullmann, G

    2011-07-01

    Flavin-containing reductases are involved in a wide variety of physiological reactions such as photosynthesis, nitric oxide synthesis, and detoxification of foreign compounds, including therapeutic drugs. Ferredoxin-NADP(H)-reductase (FNR) is the prototypical enzyme of this family. The fold of this protein is highly conserved and occurs as one domain of several multidomain enzymes such as the members of the diflavin reductase family. The enzymes of this family have emerged as fusion of a FNR and a flavodoxin. Although the active sites of these enzymes are very similar, different enzymes function in opposite directions, that is, some reduce oxidized nicotinamide adenine dinucleotide phosphate (NADP(+)) and some oxidize reduced nicotinamide adenine dinucleotide phosphate (NADPH). In this work, we analyze the protonation behavior of titratable residues of these enzymes through electrostatic calculations. We find that a highly conserved carboxylic acid in the active site shows a different titration behavior in different flavin reductases. This residue is deprotonated in flavin reductases present in plastids, but protonated in bacterial counterparts and in diflavin reductases. The protonation state of the carboxylic acid may also influence substrate binding. The physiological substrate for plastidic enzymes is NADP(+), but it is NADPH for the other mentioned reductases. In this article, we discuss the relevance of the environment of this residue for its protonation and its importance in catalysis. Our results allow to reinterpret and explain experimental data. PMID:21538544

  16. Enantiomeric and Isotopic Analysis of Organic Compounds in Carbonaceous Meteorites

    NASA Technical Reports Server (NTRS)

    Cooper, George

    2004-01-01

    Carbonaceous meteorites are relatively enriched in soluble organic compounds. The Murchison and Murray meteorites contain numerous compounds of interest in the study of early solar system organic chemistry and organic compounds of potential importance for the origin of life. These include: amino acids, amides, carboxylic acids, and polyols. This talk will focus on the enantiomeric and isotopic analysis of individual meteoritic compounds - primarily polyol acids. The analyses will determine if, in addition to certain amino acids from Murchison, another potentially important class of prebiotic compounds also contains enantiomeric excesses, i.e., excesses that could have contributed to the current homochirality of life. Preliminary enantiomeric and isotopic (C- 13) measurements of Murchison glyceric acid show that it is indeed extraterrestrial. C-13 and D isotope analysis of meteoritic sugar alcohols (glycerol, threitol, ribitol, etc.) has shown that they are also indigenous to the meteorite.

  17. Removal of perfluorinated carboxylates from washing wastewater of perfluorooctanesulfonyl fluoride using activated carbons and resins.

    PubMed

    Du, Ziwen; Deng, Shubo; Chen, Youguang; Wang, Bin; Huang, Jun; Wang, Yujue; Yu, Gang

    2015-04-01

    Perfluorooctanesulfonyl fluoride (PFOSF) washing wastewater contains high concentrations of perfluorinated carboxylates (PFCAs) including perfluorohexanoate (PFHxA, 0.10 mmol/L), perfluoroheptanoate (PFHpA, 0.11 mmol/L), and perfluorooctanoate (PFOA, 0.29 mmol/L). For the first time, we investigated the removal of these PFCAs from actual wastewater using the bamboo-derived activated carbon (BAC) and resin IRA67. Adsorption kinetics, effects of adsorbent dose, solution pH, and inorganic ions, as well as regeneration and reuse experiments were studied. The removal percents of three PFCAs by BAC and IRA67 followed the increasing order of PFHxA < PFHpA < PFOA, but the adsorption equilibrium time conformed to the reverse trend. PFCAs removal on IRA67 decreased with increasing pH, but BAC almost kept stable PFCAs removal at pH above 5.0. Among competitive adsorption of three PFCAs, PFOA was preferentially adsorbed on both BAC and IRA67. PFCAs removal from actual wastewater by BAC was higher than that in simulated solution, due to the presence of high concentration of inorganic ions in the wastewater. However, the co-existing organic compounds in wastewater significantly suppressed the adsorption of PFCAs. Both spent BAC and IRA67 were successfully regenerated by ethanol solution or NaCl/methanol mixture, and IRA67 showed the stable removal of PFCAs in five adsorption cycles. PMID:25585266

  18. Anti-Inflammatory and Antinociceptive Activities of Anthraquinone-2-Carboxylic Acid

    PubMed Central

    Park, Jae Gwang; Kim, Seung Cheol; Kim, Yun Hwan; Yang, Woo Seok; Kim, Yong; Hong, Sungyoul; Kim, Kyung-Hee; Yoo, Byong Chul; Kim, Shi Hyung; Kim, Jong-Hoon; Cho, Jae Youl

    2016-01-01

    Anthraquinone compounds are one of the abundant polyphenols found in fruits, vegetables, and herbs. However, the in vivo anti-inflammatory activity and molecular mechanisms of anthraquinones have not been fully elucidated. We investigated the activity of anthraquinones using acute inflammatory and nociceptive experimental conditions. Anthraquinone-2-carboxylic acid (9,10-dihydro-9,10-dioxo-2-anthracenecarboxylic acid, AQCA), one of the major anthraquinones identified from Brazilian taheebo, ameliorated various inflammatory and algesic symptoms in EtOH/HCl- and acetylsalicylic acid- (ASA-) induced gastritis, arachidonic acid-induced edema, and acetic acid-induced abdominal writhing without displaying toxic profiles in body and organ weight, gastric irritation, or serum parameters. In addition, AQCA suppressed the expression of inflammatory genes such as cyclooxygenase- (COX-) 2 in stomach tissues and lipopolysaccharide- (LPS-) treated RAW264.7 cells. According to reporter gene assay and immunoblotting analyses, AQCA inhibited activation of the nuclear factor- (NF-) κB and activator protein- (AP-) 1 pathways by suppression of upstream signaling involving interleukin-1 receptor-associated kinase 4 (IRAK1), p38, Src, and spleen tyrosine kinase (Syk). Our data strongly suggest that anthraquinones such as AQCA act as potent anti-inflammatory and antinociceptive components in vivo, thus contributing to the immune regulatory role of fruits and herbs. PMID:27057092

  19. Perfluorinated carboxylic acids in human breast milk from Spain and estimation of infant's daily intake.

    PubMed

    Motas Guzmàn, Miguel; Clementini, Chiara; Pérez-Cárceles, Maria Dolores; Jiménez Rejón, Sandra; Cascone, Aurora; Martellini, Tania; Guerranti, Cristiana; Cincinelli, Alessandra

    2016-02-15

    Human milk samples were collected from 67 mothers in 2014 at a Primary Care Centre in Murcia (Spain) and analyzed for perfluorinated carboxylic acids (PFCAs). Concentrations measured for perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA) and perfluorododecanoic acid (PFDoDA) ranged from compounds was revealed in 50 samples out of 67 analyzed. Influence of number of pregnancies and food habits on PFCAs concentrations was also investigated. Statistically significant differences in PFCA levels were found when the women were divided into maternal age classes and into the categories primiparae and multiparae. A greater transfer of PFC during breastfeeding by primiparous was evidenced and thus a higher exposure to these contaminants for the first child. Moreover, it was possible to hypothesize that the content of PFCs is in general correlated to the eating habits of donors and, in particular, with the fish consumption. Finally, PFOA daily intakes and risk index (RI) were estimated for the first six months of life and we found that ingestion rates of PFOA did not exceed the tolerable daily intake (TDI) recommended by the European Food Safety Authority (EFSA). PMID:26674688

  20. The cysteine releasing pattern of some antioxidant thiazolidine-4-carboxylic acids.

    PubMed

    Önen Bayram, F Esra; Sipahi, Hande; Acar, Ebru Türköz; Kahveci Ulugöl, Reyhan; Buran, Kerem; Akgün, Hülya

    2016-05-23

    Oxidative stress that corresponds to a significant increase in free radical concentration in cells can cause considerable damage to crucial biological macromolecules if not prevented by cellular defense mechanisms. The low-molecular-weight thiol glutathione (GSH) constitutes one of the main intracellular antioxidants. It is synthesized via cysteine, an amino acid found only in limited amounts in cells because of its neurotoxicity. Thus, to ensure an efficient GSH synthesis in case of an oxidative stress, cysteine should be provided extracellularly. Yet, given its nucleophilic properties and its rapid conversion into cystine, its corresponding disulfide, cysteine presents some toxicity and therefore is usually supplemented in a prodrug approach. Here, some thiazolidine-4-carboxylic acids were synthesized and evaluated for their antioxidant properties via the DDPH and CUPRAC assays. Then, the cysteine releasing capacity of the obtained compounds was investigated in aqueous and organic medium in order to correlate the relevant antioxidant properties of the molecules with their cysteine releasing pattern. As a result, the structures' antioxidative properties were not only attributed to cysteine release but also to the thiazolidine cycle itself. PMID:27017266

  1. Carboxylate-intercalated layered double hydroxides aged under microwave-hydrothermal treatment

    NASA Astrophysics Data System (ADS)

    Benito, P.; Labajos, F. M.; Mafra, L.; Rocha, J.; Rives, V.

    2009-01-01

    Carboxylate-intercalated (terephthalate, TA and oxalate, ox) layered double hydroxides (LDHs) are aged under a microwave-hydrothermal treatment. The influence of the nature of the interlayer anion during the ageing process is studied. Characterization results show that the microwave-hydrothermal method can be extended to synthesize LDHs with anions different than carbonate, like TA. LDH-TA compounds are stable under microwave irradiation for increasing periods of time and the solids show an improved order both in the layers and in the interlayer region as evidenced by powder X-ray diffraction (PXRD), 27Al MAS NMR and FT-IR spectroscopy. Furthermore, cleaning of the surface through removal of some organic species adsorbed on the surface of the particles also occurs during the microwave-hydrothermal treatment. Conversely, although the expected increase in crystallinity is observed in LDH-ox samples, the side-reaction between Al 3+ and ox is also enhanced under microwave irradiation, and a partial destruction of the structure takes place with an increase in the M 2+/M 3+ ratio and consequent modification of the cell parameters.

  2. A New Structural Family of Gas-Sorbing Coordination Polymers Derived from Phenolic Carboxylic Acids.

    PubMed

    White, Keith F; Abrahams, Brendan F; Babarao, Ravichandar; Dharma, A David; Hudson, Timothy A; Maynard-Casely, Helen E; Robson, Richard

    2015-12-01

    The structure of Li(inox)⋅2/3 DMF (inox(-) =the N-oxide of the isonicotinate anion) consists of a 3D framework with solvent-filled, square cross-section channels of approximate dimensions 5.5×5.5 Å. Unfortunately, the Li(inox) framework is unstable upon removal of DMF from the channels. When the structurally related 4-hydroxybenzoic acid (H2 hba) was used in place of Hinox, and Zn(2+) in place of the Li(+) , a structurally similar but more robust network, Zn(hba), was obtained; the isostructural compound, Co(hba), may also be prepared. Longer ligands with phenolate and carboxylate functional groups at opposite ends, such as the dianions of 4-coumaric acid (H2 cma) and 4'-hydroxy-4-biphenylcarboxylic acid (H2 hbpc), in combination with Zn(2+) yield Zn(cma) and Zn(hbpc) frameworks, respectively, with the same PtS topology but with larger channels. The coordination polymers remain intact after desolvation and exhibit microporosity, showing the ability to sorb significant quantities of CO2 , CH4 , and H2 . PMID:26525776

  3. The physical and degradation properties of starch-graft-acrylonitrile/carboxylated nitrile butadiene rubber latex films.

    PubMed

    Misman, M A; Azura, A R; Hamid, Z A A

    2015-09-01

    Starch-graft-acrylonitrile (ANS) is compounded with carboxylated nitrile butadiene rubber (XNBR) latex. The control XNBR and the ANS/XNBR latex films were prepared through a coagulant dipping process. The films were subjected to ageing and soil burial procedures. For the biodegradation experiment, the surface of the film was assessed after the 2nd, 4th and 8th week of soil burial. The ANS, XNBR, and ANS/XNBR colloidal stability were determined with a Malvern Zetasizer. For the dipped latex films, the mechanical, morphological and thermal properties were analyzed. The addition of ANS into the XNBR latex increased the stability of the colloidal dispersions, decreased the latex film tensile strength, but increased the elongation at break due to the bipolar interaction of the ANS and XNBR particles. The ANS/XNBR latex films aged faster than the control films while the morphological analysis showed the existence of a starch crystal region and the formation of microbial colonies on the surfaces of the films. Based on the TGA-DTA curves, a higher ΔT was observed for the ANS/XNBR latex films signifying high thermal energy needed for the film to thermally degrade. PMID:26005134

  4. Tissue-specific concentrations and patterns of perfluoroalkyl carboxylates and sulfonates in East Greenland polar bears.

    PubMed

    Greaves, Alana K; Letcher, Robert J; Sonne, Christian; Dietz, Rune; Born, Erik W

    2012-11-01

    Several perfluoroalkyl carboxylates (PFCAs) and perfluoroalkyl sulfonates (PFSAs) of varying chain length are bioaccumulative in biota. However, wildlife reports have focused on liver and with very little examination of other tissues, and thus there is a limited understanding of their distribution and potential effects in the mammalian body. In the present study, the comparative accumulation of C(6) to C(15) PFCAs, C(4), C(6), C(8) and C(10) PFSAs, and select precursors were examined in the liver, blood, muscle, adipose, and brain of 20 polar bears (Ursus maritimus) from Scoresby Sound, Central East Greenland. Overall, PFSA and PFCA concentrations were highest in liver followed by blood > brain > muscle ≈ adipose. Liver and blood samples contained proportionally more of the shorter/medium chain length (C(6) to C(11)) PFCAs, whereas adipose and brain samples were dominated by longer chain (C(13) to C(15)) PFCAs. PFCAs with lower lipophilicities accumulated more in the liver, whereas the brain accumulated PFCAs with higher lipophilicities. The concentration ratios (±SE) between perfluorooctane sulfonate and its precursor perfluorooctane sulfonamide varied among tissues from 9 (±1):1 (muscle) to 36 (±7):1 (liver). PFCA and PFSA patterns in polar bears indicate that the pharmacokinetics of these compounds are to some extent tissue-specific, and are the result of several factors that may include differing protein interactions throughout the body. PMID:23057644

  5. Occurrence and fate of oseltamivir carboxylate (Tamiflu) and amantadine in sewage treatment plants.

    PubMed

    Ghosh, Gopal Chandra; Nakada, Norihide; Yamashita, Naoyuki; Tanaka, Hiroaki

    2010-09-01

    We investigated the occurrence and fate of the two antiviral drugs oseltamivir carboxylate (OC)-the active metabolite of Tamiflu-and amantadine (AMT) at three sewage treatment plants (STPs) during the 2008-2009 and 2009-2010 influenza seasons in Japan. Both compounds were detected in all samples analyzed. The concentrations in raw influents at the STPs ranged from 140 to 460 ng L(-1) OC and from 184 to 538 ng L(-1) AMT. Primary treatment gave no substantial removal of the drugs (OC, 2-9%; AMT, 7-17%). Biological nutrient-removal-based secondary treatment (anoxic-oxic-anoxic-oxic and anaerobic-anoxic-oxic) removed 20-37% of OC, whereas extended-aeration-based conventional activated sludge treatment removed <20%. STPs using primary plus biological secondary treatment removed <50% of the drugs. The incorporation of tertiary treatment by ozonation removed >90%. Ozonation after secondary treatment in STPs will be necessary during an influenza pandemic to reduce the risks associated with the widespread use of antiviral drugs. PMID:20692015

  6. Exploring the role of a unique carboxyl residue in EmrE by mass spectrometry.

    PubMed

    Weinglass, Adam B; Soskine, Misha; Vazquez-Ibar, Jose-Luis; Whitelegge, Julian P; Faull, Kym F; Kaback, H Ronald; Schuldiner, Shimon

    2005-03-01

    EmrE is a small multidrug transporter in Escherichia coli that extrudes various positively charged drugs across the plasma membrane in exchange with protons, thereby rendering cells resistant to these compounds. Biochemical experiments indicate that the basic functional unit of EmrE is a dimer where the common binding site for protons and substrate is formed by the interaction of an essential charged residue (Glu-14) from both EmrE monomers. Carbodiimide modification of EmrE has been studied using functional assays, and the evidence suggests that Glu-14 is the target of the reaction. Here we exploited electrospray ionization mass spectrometry to directly monitor the reaction with each monomer rather than following inactivation of the functional unit. A cyanogen bromide peptide containing Glu-14 allows the extent of modification by the carboxyl-specific modification reagent diisopropylcarbodiimide (DiPC) to be monitored and reveals that peptide 2NPYIYLGGAILAEVIGTTLM(21) is approximately 80% modified in a time-dependent fashion, indicating that each Glu-14 residue in the oligomer is accessible to DiPC. Furthermore, preincubation with tetraphenylphosphonium reduces the reaction of Glu-14 with DiPC by up to 80%. Taken together with other biochemical data, the findings support a "time sharing" mechanism in which both Glu-14 residues in a dimer are involved in tetraphenylphosphonium and H(+) binding. PMID:15623511

  7. Sterically hindered carboxylate ligands support water-bridged dimetallic centers that model features of metallohydrolase active sites.

    PubMed

    Lee, Dongwhan; Hung, Pei-Lin; Spingler, Bernhard; Lippard, Stephen J

    2002-02-11

    The synthesis and characterization of carboxylate-bridged dimetallic complexes are described. By using m-terphenyl-derived carboxylate ligands, a series of dicobalt(II), dicobalt(III), dinickel(II), and dizinc(II) complexes were synthesized. The compounds are [Co(2)(mu-O(2)CAr(Tol))(2)(O(2)CAr(Tol))(2)L(2)] (1), [Co(2)(mu-OH(2))(2)(mu-O(2)CAr(Tol))(2)(O(2)CAr(Tol))(2)L(2)] (2a-c), [Co(2)(mu-OH)(2)(mu-O(2)CAr(Tol))(2)(O(2)CAr(Tol))(2)L(2)] (3), [Ni(2)(mu-O(2)CAr(Tol))(4)L(2)] (4), [Ni(2)(mu-HO...H)(2)(mu-O(2)CAr(Tol))(2)(O(2)CAr(Tol))(2)L(2)] (5), and [Zn(2)(mu-O(2)CAr(Tol))(2)(O(2)CAr(Tol))(2)L(2)] (6), where Ar(Tol)CO(2)H = 2,6-di(p-tolyl)benzoic acid and L = pyridine, THF, or N,N-dibenzylethylenediamine. Structural analysis of these complexes revealed that additional bridging ligands can be readily accommodated within the [M(2)(mu-O(2)CAr(Tol))(2)](2+) core, allowing a wide distribution of M...M distances from 2.5745(6) to 4.0169(9) A. Unprecedented bridging units [M(2)(mu-OH(2))(2)(mu-O(2)CR)(2)](n+) and [M(2)(mu-HO...H)(2)(mu-O(2)CR)(2)](n+) were identified in 2a-c and 5, respectively, in which strong hydrogen bonding accommodates shifts of protons from bridging water molecules toward the dangling oxygen atoms of terminal monodentate carboxylate groups. Such a proton shift along the O...H...O coordinate attenuates the donor ability of the anionic carboxylate ligand, which can translate into increased Lewis acidity at the metal centers. Such double activation of bridging water molecules by a Lewis acidic metal center and a metal-bound general base may facilitate the reactivity of metallohydrolases such as methionine aminopeptidase (MAP). PMID:11825079

  8. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2012-01-01

    Seawater and natural brines accounted for about 57 percent of magnesium compounds produced in the United States in 2011. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties LLC from well brines in Michigan. Caustic-calcined magnesia was recovered from seawater by Premier Magnesia LLC in Florida, from well brines in Michigan by Martin Marietta and from magnesite in Nevada by Premier Magnesia. Intrepid Potash Wendover LLC and Great Salt Lake Minerals Corp. recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from seawater by SPI Pharma Inc. in Delaware and Premier Magnesia in Florida, and by Martin Marietta from its brine operation in Michigan.

  9. Bismaleimide compounds

    DOEpatents

    Adams, Johnnie E.; Jamieson, Donald R.

    1986-01-14

    Bismaleimides of the formula ##STR1## wherein R.sub.1 and R.sub.2 each independently is H, C.sub.1-4 -alkyl, C.sub.1-4 -alkoxy, C1 or Br, or R.sub.1 and R.sub.2 together form a fused 6-membered hydrocarbon aromatic ring, with the proviso that R.sub.1 and R.sub.2 are not t-butyl or t-butoxy; X is O, S or Se; n is 1-3; and the alkylene bridging group, optionally, is substituted by 1-3 methyl groups or by fluorine, form polybismaleimide resins which have valuable physical properties. Uniquely, these compounds permit extended cure times, i.e., they remain fluid for a time sufficient to permit the formation of a homogeneous melt prior to curing.

  10. Bismaleimide compounds

    DOEpatents

    Adams, J.E.; Jamieson, D.R.

    1986-01-14

    Bismaleimides of the formula shown in the diagram wherein R[sub 1] and R[sub 2] each independently is H, C[sub 1-4]-alkyl, C[sub 1-4]-alkoxy, Cl or Br, or R[sub 1] and R[sub 2] together form a fused 6-membered hydrocarbon aromatic ring, with the proviso that R[sub 1] and R[sub 2] are not t-butyl or t-butoxy; X is O, S or Se; n is 1--3; and the alkylene bridging group, optionally, is substituted by 1--3 methyl groups or by fluorine, form polybismaleimide resins which have valuable physical properties. Uniquely, these compounds permit extended cure times, i.e., they remain fluid for a time sufficient to permit the formation of a homogeneous melt prior to curing.

  11. Biohydrogen and carboxylic acids production from wheat straw hydrolysate.

    PubMed

    Chandolias, Konstantinos; Pardaev, Sindor; Taherzadeh, Mohammad J

    2016-09-01

    Hydrolyzed wheat straw was converted into carboxylic acids and biohydrogen using digesting bacteria. The fermentations were carried out using both free and membrane-encased thermophilic bacteria (55°C) at various OLRs (4.42-17.95g COD/L.d), in semi-continuous conditions using one or two bioreactors in a series. The highest production of biohydrogen and acetic acid was achieved at an OLR of 4.42g COD/L.d, whilst the highest lactic acid production occurred at an OLR of 9.33g COD/L.d. Furthermore, the bioreactor with both free and membrane-encased cells produced 60% more lactic acid compared to the conventional, free-cell bioreactor. In addition, an increase of 121% and 100% in the production of acetic and isobutyric acid, respectively, was achieved in the 2nd-stage bioreactor compared to the 1st-stage bioreactor. PMID:27268482

  12. Adhesion to and decalcification of hydroxyapatite by carboxylic acids.

    PubMed

    Yoshida, Y; Van Meerbeek, B; Nakayama, Y; Yoshioka, M; Snauwaert, J; Abe, Y; Lambrechts, P; Vanherle, G; Okazaki, M

    2001-06-01

    Fundamental to the processes of decalcification of or adhesion to mineralized tissues is the molecular interaction of acids with hydroxyapatite. This study was undertaken to chemically analyze the interaction of 1 mono-, 2 di-, 1 tri-, and 2 polycarboxylic acids with hydroxyapatite in an attempt to elucidate the underlying mechanism. Maleic, citric, and lactic acid decalcified hydroxyapatite, in contrast to oxalic acid and the two polycarboxylic acids that were chemically bonded to hydroxyapatite. Solubility tests showed that the calcium salts of the former were very soluble, whereas those of the latter could hardly be dissolved in the respective acid solutions. Based on these data, an adhesion/decalcification concept was advanced that predicts that carboxylic acids, regardless of concentration/pH, either adhere to or decalcify hydroxyapatite, depending on the dissolution rate of the respective calcium salts in the acid solution. This contrasting behavior of organic acids most likely results from their differential structural conformations. PMID:11499514

  13. 40 CFR 721.10529 - Cobalt iron manganese oxide, carboxylic acid-modified (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Cobalt iron manganese oxide... Significant New Uses for Specific Chemical Substances § 721.10529 Cobalt iron manganese oxide, carboxylic acid... substance identified generically as cobalt iron manganese oxide, carboxylic acid-modified (PMN P-12-35)...

  14. 40 CFR 721.10529 - Cobalt iron manganese oxide, carboxylic acid-modified (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Cobalt iron manganese oxide... Significant New Uses for Specific Chemical Substances § 721.10529 Cobalt iron manganese oxide, carboxylic acid... substance identified generically as cobalt iron manganese oxide, carboxylic acid-modified (PMN P-12-35)...

  15. Photocatalytic Decarboxylative Hydroxylation of Carboxylic Acids Driven by Visible Light and Using Molecular Oxygen.

    PubMed

    Song, Hai-Tao; Ding, Wei; Zhou, Quan-Quan; Liu, Jing; Lu, Liang-Qiu; Xiao, Wen-Jing

    2016-08-19

    This paper discloses the first example of photocatalytic direct decarboxylative hydroxylation of carboxylic acids. It enables the conversion of a variety of readily available carboxylic acids to alcohols in moderate to high yields. This unprecedented protocol is accomplished under extremely mild reaction conditions using molecular oxygen (O2) as a green oxidant and using visible light as a driving force. PMID:27385267

  16. 40 CFR 721.10536 - Long-chain perfluoroalkyl carboxylate chemical substances.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Long-chain perfluoroalkyl carboxylate... Specific Chemical Substances § 721.10536 Long-chain perfluoroalkyl carboxylate chemical substances. (a... paragraph (b)(3) of this section. (3) Manufacture (including import) or processing of the following two...

  17. 40 CFR 721.2088 - Carboxylic acids, (C6-C9) branched and linear.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... linear. 721.2088 Section 721.2088 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.2088 Carboxylic acids, (C6-C9) branched and linear. (a) Chemical... as carboxylic acids, (C6-C9) branched and linear (PMNs P-93-313, 314, 315, and 316) are subject...

  18. Carboxyl-modified single-walled carbon nanotubes negatively affect bacterial growth and denitrification activity

    NASA Astrophysics Data System (ADS)

    Zheng, Xiong; Su, Yinglong; Chen, Yinguang; Wan, Rui; Li, Mu; Wei, Yuanyuan; Huang, Haining

    2014-07-01

    Single-walled carbon nanotubes (SWNTs) have been used in a wide range of fields, and the surface modification via carboxyl functionalization can further improve their physicochemical properties. However, whether carboxyl-modified SWNT poses potential risks to microbial denitrification after its release into the environment remains unknown. Here we present the possible effects of carboxyl-modified SWNT on the growth and denitrification activity of Paracoccus denitrificans (a model denitrifying bacterium). It was found that carboxyl-modified SWNT were present both outside and inside the bacteria, and thus induced bacterial growth inhibition at the concentrations of 10 and 50 mg/L. After 24 h of exposure, the final nitrate concentration in the presence of 50 mg/L carboxyl-modified SWNT was 21-fold higher than that in its absence, indicating that nitrate reduction was substantially suppressed by carboxyl-modified SWNT. The transcriptional profiling revealed that carboxyl-modified SWNT led to the transcriptional activation of the genes encoding ribonucleotide reductase in response to DNA damage and also decreased the gene expressions involved in glucose metabolism and energy production, which was an important reason for bacterial growth inhibition. Moreover, carboxyl-modified SWNT caused the significant down-regulation and lower activity of nitrate reductase, which was consistent with the decreased efficiency of nitrate reduction.

  19. Carboxyl-modified single-walled carbon nanotubes negatively affect bacterial growth and denitrification activity

    PubMed Central

    Zheng, Xiong; Su, Yinglong; Chen, Yinguang; Wan, Rui; Li, Mu; Wei, Yuanyuan; Huang, Haining

    2014-01-01

    Single-walled carbon nanotubes (SWNTs) have been used in a wide range of fields, and the surface modification via carboxyl functionalization can further improve their physicochemical properties. However, whether carboxyl-modified SWNT poses potential risks to microbial denitrification after its release into the environment remains unknown. Here we present the possible effects of carboxyl-modified SWNT on the growth and denitrification activity of Paracoccus denitrificans (a model denitrifying bacterium). It was found that carboxyl-modified SWNT were present both outside and inside the bacteria, and thus induced bacterial growth inhibition at the concentrations of 10 and 50 mg/L. After 24 h of exposure, the final nitrate concentration in the presence of 50 mg/L carboxyl-modified SWNT was 21-fold higher than that in its absence, indicating that nitrate reduction was substantially suppressed by carboxyl-modified SWNT. The transcriptional profiling revealed that carboxyl-modified SWNT led to the transcriptional activation of the genes encoding ribonucleotide reductase in response to DNA damage and also decreased the gene expressions involved in glucose metabolism and energy production, which was an important reason for bacterial growth inhibition. Moreover, carboxyl-modified SWNT caused the significant down-regulation and lower activity of nitrate reductase, which was consistent with the decreased efficiency of nitrate reduction. PMID:25008009

  20. 40 CFR 721.4663 - Fluorinated carboxylic acid alkali metal salts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... metal salts. 721.4663 Section 721.4663 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.4663 Fluorinated carboxylic acid alkali metal salts. (a) Chemical... fluorinated carboxylic acid alkali metal salts (PMNs P-95-979/980/981) are subject to reporting under...

  1. 40 CFR 721.4663 - Fluorinated carboxylic acid alkali metal salts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... metal salts. 721.4663 Section 721.4663 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.4663 Fluorinated carboxylic acid alkali metal salts. (a) Chemical... fluorinated carboxylic acid alkali metal salts (PMNs P-95-979/980/981) are subject to reporting under...

  2. 40 CFR 721.4663 - Fluorinated carboxylic acid alkali metal salts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... metal salts. 721.4663 Section 721.4663 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.4663 Fluorinated carboxylic acid alkali metal salts. (a) Chemical... fluorinated carboxylic acid alkali metal salts (PMNs P-95-979/980/981) are subject to reporting under...

  3. 40 CFR 721.4663 - Fluorinated carboxylic acid alkali metal salts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... metal salts. 721.4663 Section 721.4663 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.4663 Fluorinated carboxylic acid alkali metal salts. (a) Chemical... fluorinated carboxylic acid alkali metal salts (PMNs P-95-979/980/981) are subject to reporting under...

  4. Characterizing monoclonal antibody structure by carboxyl group footprinting

    PubMed Central

    Kaur, Parminder; Tomechko, Sara E; Kiselar, Janna; Shi, Wuxian; Deperalta, Galahad; Wecksler, Aaron T; Gokulrangan, Giridharan; Ling, Victor; Chance, Mark R

    2015-01-01

    Structural characterization of proteins and their antigen complexes is essential to the development of new biologic-based medicines. Amino acid-specific covalent labeling (CL) is well suited to probe such structures, especially for cases that are difficult to examine by alternative means due to size, complexity, or instability. We present here a detailed account of carboxyl group labeling (with glycine ethyl ester (GEE) tagging) applied to a glycosylated monoclonal antibody therapeutic (mAb). The experiments were optimized to preserve the structural integrity of the mAb, and experimental conditions were varied and replicated to establish the reproducibility of the technique. Homology-based models were generated and used to compare the solvent accessibility of the labeled residues, which include aspartic acid (D), glutamic acid (E), and the C-terminus (i.e., the target probes), with the experimental data in order to understand the accuracy of the approach. Data from the mAb were compared to reactivity measures of several model peptides to explain observed variations in reactivity. Attenuation of reactivity in otherwise solvent accessible probes is documented as arising from the effects of positive charge or bond formation between adjacent amine and carboxyl groups, the latter accompanied by observed water loss. A comparison of results with previously published data by Deperalta et al using hydroxyl radical footprinting showed that 55% (32/58) of target residues were GEE labeled in this study whereas the previous study reported 21% of the targets were labeled. Although the number of target residues in GEE labeling is fewer, the two approaches provide complementary information. The results highlight advantages of this approach, such as the ease of use at the bench top, the linearity of the dose response plots at high levels of labeling, reproducibility of replicate experiments (<2% variation in modification extent), the similar reactivity of the three target probes

  5. Lubricant compositions containing antioxidant mixtures comprising substituted thiazoles and substituted thiadiazole compounds

    SciTech Connect

    Shim, J.

    1981-04-07

    Lubricants are described containing oleaginous materials and, in an amount sufficient to impart oxidation stability and corrosion resistance, an adduct of a benzotriazole compound and an alkyl vinyl ether or a vinyl ester of a carboxylic acid in combination with an alkyl dimercapto thiadiazole.

  6. Identification of a Chemoreceptor for C2 and C3 Carboxylic Acids

    PubMed Central

    García, Vanina; Reyes-Darias, Jose-Antonio; Martín-Mora, David; Morel, Bertrand; Matilla, Miguel A.

    2015-01-01

    Chemoreceptors are at the beginnings of chemosensory signaling cascades that mediate chemotaxis. Most bacterial chemoreceptors are functionally unannotated and are characterized by a diversity in the structure of their ligand binding domains (LBDs). The data available indicate that there are two major chemoreceptor families at the functional level, namely, those that respond to amino acids or to Krebs cycle intermediates. Since pseudomonads show chemotaxis to many different compounds and possess different types of chemoreceptors, they are model organisms to establish relationships between chemoreceptor structure and function. Here, we identify PP2861 (termed McpP) of Pseudomonas putida KT2440 as a chemoreceptor with a novel ligand profile. We show that the recombinant McpP LBD recognizes acetate, pyruvate, propionate, and l-lactate, with KD (equilibrium dissociation constant) values ranging from 34 to 107 μM. Deletion of the mcpP gene resulted in a dramatic reduction in chemotaxis toward these ligands, and complementation restored a native-like phenotype, indicating that McpP is the major chemoreceptor for these compounds. McpP has a CACHE-type LBD, and we present data indicating that CACHE-containing chemoreceptors of other species also mediate taxis to C2 and C3 carboxylic acids. In addition, the LBD of NbaY of Pseudomonas fluorescens, an McpP homologue mediating chemotaxis to 2-nitrobenzoate, bound neither nitrobenzoates nor the McpP ligands. This work provides further insight into receptor structure-function relationships and will be helpful to annotate chemoreceptors of other bacteria. PMID:26048936

  7. Transport and Metabolism of 1-Aminocyclopropane-1-carboxylic Acid in Sunflower (Helianthus annuus L.) Seedlings 1

    PubMed Central

    Finlayson, Scott A.; Foster, Kenneth R.; Reid, David M.

    1991-01-01

    Transport and metabolism of [2,3-14C] 1-aminocyclopropane-1-carboxylic acid (ACC) from roots to shoots in 4-day-old sunflower (Helianthus annuus L.) seedlings were studied. [14C]ACC was detected in, and 14C2H4 was evolved from, shoots 0.5 hours after [14C]ACC was supplied to roots. Ethylene emanation from the shoots returned to normal levels after 6 hours. The roots showed a similar pattern, although at 24 hours ethylene emanation was still slightly higher than in those plants that did not receive ACC. [14C]N-malonyl-ACC (MACC) was detected in both tissues at all times sampled. [14C]MACC levels surpassed [14C]ACC levels in the shoot at 2 hours, whereas [14C]MACC levels in the root remained below [14C]ACC levels until 6 hours, after which they were higher. Thin-layer chromatography analysis identified [14C] ACC in 1-hour shoot extracts, and [14C]MACC was identified in root tissues at 1 and 12 hours after treatment. [14C]ACC and [14C] MACC in the xylem sap of treated seedlings were identified by thin-layer chromatography. Xylem transport of [14C]ACC in treated seedlings, and transport of ACC in untreated seedlings, was confirmed by gas chromatography-mass spectrometry. Some evidence for the presence of [14C]MACC in xylem sap in [14C]ACC-treated seedlings is presented. A substantial amount of radioactivity in both ACC and MACC fractions was detected leaking from the roots over 24 hours. A second radiolabeled volatile compound was trapped in a CO2-trapping solution but not in mercuric perchlorate. Levels of this compound were highest after the peak of ACC levels and before peak MACC levels in both tissues, suggesting that an alternate pathway of ACC metabolism was operating in this system. PMID:16668342

  8. Carboxylate Surrogates Enhance the Antimycobacterial Activity of UDP-Galactopyranose Mutase Probes.

    PubMed

    Winton, Valerie J; Aldrich, Claudia; Kiessling, Laura L

    2016-08-12

    Uridine diphosphate galactopyranose mutase (UGM also known as Glf) is a biosynthetic enzyme required for construction of the galactan, an essential mycobacterial cell envelope polysaccharide. Our group previously identified two distinct classes of UGM inhibitors; each possesses a carboxylate moiety that is crucial for potency yet likely detrimental for cell permeability. To enhance the antimycobacterial potency, we sought to replace the carboxylate with a functional group mimic-an N-acylsulfonamide group. We therefore synthesized a series of N-acylsulfonamide analogs and tested their ability to inhibit UGM. For each inhibitor scaffold tested, the N-acylsulfonamide group functions as an effective carboxylate surrogate. Although the carboxylates and their surrogates show similar activity against UGM in a test tube, several N-acylsulfonamide derivatives more effectively block the growth of Mycobacterium smegmatis. These data suggest that the replacement of a carboxylate with an N-acylsulfonamide group could serve as a general strategy to augment antimycobacterial activity. PMID:27626294

  9. Mechanism of silver- and copper-catalyzed decarboxylation reactions of aryl carboxylic acids.

    PubMed

    Xue, Liqin; Su, Weiping; Lin, Zhenyang

    2011-11-28

    Silver- and copper-catalyzed decarboxylation reactions of aryl carboxylic acids were investigated with the aid of density functional theory calculations. The reaction mechanism starts with a carboxylate complex of silver or copper. Decarboxylation occurs via ejecting CO(2) from the carboxylate complex followed by protodemetallation with an aryl carboxylic acid molecule to regenerate the starting complex. Our results indicated that the primary factor to affect the overall reaction barriers is the ortho steric destabilization effect on the starting carboxylate complexes for most cases. Certain ortho substituents that are capable of coordinating with the catalyst metal center without causing significant ring strain stabilize the decarboxylation transition states and reduce the overall reaction barriers. However, the coordination effect is found to be the secondary factor when compared with the ortho effect. PMID:21979246

  10. Site identification of carboxyl groups on graphene edges with Pt derivatives.

    PubMed

    Yuge, Ryota; Zhang, Minfang; Tomonari, Mutsumi; Yoshitake, Tsutomu; Iijima, Sumio; Yudasaka, Masako

    2008-09-23

    Although chemical functionalization at carboxyl groups of nanocarbons has been vigorously investigated and the identities and quantities of the carboxyl groups have been well studied, the location of carboxyl groups had not previously been clarified. Here, we show that site identification of carboxyl groups is possible by using Pt-ammine complex as a stain. After Pt-ammine complexes were mixed with graphenes in ethanol, many Pt-ammine complex clusters with an average size of about 0.6 nm were found to exist at edges of graphene sheets, indicating that the carboxyl groups mainly existed at the graphene edges. These results will make it easier to add functionalities by chemical modifications for various applications of nanotubes and other nanocarbons. PMID:19206426

  11. Investigation of supramolecular synthons and structural characterisation of aminopyridine-carboxylic acid derivatives

    PubMed Central

    2014-01-01

    Background Co-crystal is a structurally homogeneous crystalline material that contains two or more neutral building blocks that are present in definite stoichiometric amounts. The main advantage of co-crystals is their ability to generate a variety of solid forms of a drug that have distinct physicochemical properties from the solid co-crystal components. In the present investigation, five co-crystals containing 2-amino-6-chloropyridine (AMPY) moiety were synthesized and characterized. Results The crystal structure of 2-amino-6-chloropyridine (AMPY) (I), and the robustness of pyridine-acid supramolecular synthon were discussed in four stoichiometry co-crystals of AMPY…BA (II), AMPY…2ABA (III), AMPY…3CLBA (IV) and AMPY…4NBA (V). The abbreviated designations used are benzoic acid (BA), 2-aminobenzoic acid (2ABA), 3-chlorobenzoic acid (3CLBA) and 4-nitrobenzoic acid (4NBA). All the crystalline materials have been characterized by 1HNMR, 13CNMR, IR, photoluminescence, TEM analysis and X-ray diffraction. The supramolecular assembly of each co-crystal is analyzed and discussed. Conclusions Extensive N---H · · · N/N---H · · · O/O---H · · · N hydrogen bonds are found in (I-V), featuring different supramolecular synthons. In the crystal structure, for compound (I), the 2-amino-6-chloropyridine molecules are linked together into centrosymmetric dimers by hydrogen bonds to form homosynthon, whereas for compounds (II-V), the carboxylic group of the respective acids (benzoic acid, 2-aminobenzoic acid, 3-chlorobenzoic acid and 4-nitrobenzoic acid) interacts with pyridine molecule in a linear fashion through a pair of N---H · · · O and O---H · · · N hydrogen bonds, generating cyclic hydrogen-bonded motifs with the graph-set notation R 2 2 8 , to form heterosynthon. In compound (II), another intermolecular N---H · · · O hydrogen bonds further link these heterosynthons into zig-zag chains. Whereas in

  12. Synthesis, spectroscopic characterization and molecular modeling of a tetranuclear platinum(II) complex with thiazolidine-4-carboxylic acid

    NASA Astrophysics Data System (ADS)

    Corbi, Pedro P.; Formiga, André L. B.; Bonk, Fábio A.; Quintão, Frederico A.; Ferraresi, Diego K. D.; Lustri, Wilton R.; Massabni, Antonio C.

    2012-07-01

    The synthesis, spectroscopic characterization and molecular modeling of a novel tetranuclear platinum(II) complex with thiazolidine-4-carboxylic acid (THC) are described. Elemental analysis is consistent with the composition PtCl2C4H7NO2S·H2O. Infrared (IR) spectroscopic results and solid-state 13C and 15N nuclear magnetic resonance (NMR) data indicate coordination of the ligand to Pt(II) through the nitrogen and sulfur atoms. The square planar geometry of the platinum(II) complex is completed by chlorine atoms. Density functional theory (DFT) suggests the formation of a tetrameric cluster as the most probable structure, where each THC molecule bridges between two metal centers. The compound is insoluble in water.

  13. Poly[[tris­(μ3-2-oxidopyridinium-3-carboxyl­ato)manganese(II)sodium(I)] monohydrate

    PubMed Central

    Zhang, Bing-Yu; Nie, Jing-Jing; Xu, Duan-Jun

    2010-01-01

    In the crystal structure of the title compound, {[MnNa(C6H4NO3)3]·H2O}n, the MnII cation is located on a threefold rotation axis and is chelated by three 2-oxidopyridinium-3-carboxyl­ate (opc) anions in an octa­hedal coordination. The NaI cation is located on a threefold rotation axis and is surrounded by six O atoms from three opc anions. The opc anions link the Mn and Na cations, forming a three-dimensional polymeric structure. The uncoordinated water mol­ecule, located on a threefold rotation axis, is equally disordered over two sites. The three-dimensional network is consolidated by N—H⋯O hydrogen bonds. PMID:21579675

  14. Structural environments of carboxyl groups in natural organic molecules from terrestrial systems. Part 1: Infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Hay, Michael B.; Myneni, Satish C. B.

    2007-07-01

    Carboxyls play an important role in the chemistry of natural organic molecules (NOM) in the environment, and their behavior is dependent on local structural environment within the macromolecule. We studied the structural environments of carboxyl groups in dissolved NOM from the Pine Barrens (New Jersey, USA), and IHSS NOM isolates from soils and river waters using attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy. It is well established that the energies of the asymmetric stretching vibrations of the carboxylate anion (COO -) are sensitive to the structural environment of the carboxyl group. These energies were compiled from previous infrared studies on small organic acids for a wide variety of carboxyl structural environments and compared with the carboxyl spectral features of the NOM samples. We found that the asymmetric stretching peaks for all NOM samples occur within a narrow range centered at 1578 cm -1, suggesting that all NOM samples examined primarily contain very similar carboxyl structures, independent of sample source and isolation techniques employed. The small aliphatic acids containing hydroxyl (e.g., D-lactate, gluconate), ether/ester (methoxyacetate, acetoxyacetate), and carboxylate (malonate) substitutions on the α-carbon, and the aromatic acids salicylate ( ortho-OH) and furancarboxylate ( O-heterocycle), exhibit strong overlap with the NOM range, indicating that similar structures may be common in NOM. The width of the asymmetric peak suggests that the structural heterogeneity among the predominant carboxyl configurations in NOM is small. Changes in peak area with pH at energies distant from the peak at 1578 cm -1, however, may be indicative of a small fraction of other aromatic carboxyls and aliphatic structures lacking α-substitution. This information is important in understanding NOM-metal and mineral-surface complexation, and in building appropriate structural and mechanistic models of humic materials.

  15. Photo- and thermochromic and adsorption properties of porous coordination polymers based on bipyridinium carboxylate ligands.

    PubMed

    Toma, Oksana; Mercier, Nicolas; Allain, Magali; Kassiba, Abdel Adi; Bellat, Jean-Pierre; Weber, Guy; Bezverkhyy, Igor

    2015-09-21

    The zwitterionic bipyridinium carboxylate ligand 1-(4-carboxyphenyl)-4,4'-bipyridinium (hpc1) in the presence of 1,4-benzenedicarboxylate anions (BDC(2-)) and Zn(2+) ions affords three porous coordination polymers (PCPs): [Zn5(hpc1)2(BDC)4(HCO2)2]·2DMF·EtOH·H2O (1), [Zn3(hpc1)(BDC)2(HCO2)(OH)(H2O)]·DMF·EtOH·H2O (2), and [Zn10(hpc1)4(BDC)7(HCO2)2(OH)4(EtOH)2]·3DMF·3H2O (3), with the formate anions resulting from the in situ decomposition of dimethylformamide (DMF) solvent molecules. 1 and 3 are photo- and thermochromic, turning dark green as a result of the formation of bipyridinium radicals, as shown by electron paramagnetic resonance measurements. Particularly, crystals of 3 are very photosensitive, giving an eye-detectable color change upon exposure to the light of the microscope in air within 1-2 min. A very nice and interesting feature is the regular discoloration of crystals from the "edge" to the "core" upon exposition to O2 (reoxidation of organic radicals) due to the diffusion of O2 inside the pores, with this discoloration being slower in an oxygen-poor atmosphere. The formation of organic radicals is explained by an electron transfer from the oxygen atoms of the carboxylate groups to pyridinium cycles. In the structure of 3', [Zn10(hpc1)4(BDC)7(OH)6(H2O)2], resulting from the heating of sample 3 (desolvation and loss of CO molecules due to the decomposition of formate anions), no suitable donor-acceptor interaction is present, and as a consequence, this compound does not exhibit any chromic properties. The presence of permanent porosity in desolvated 1, 2, and 3' is confirmed by methanol adsorption at 25 °C with the adsorbed amount reaching 5 wt % for 1, 10 wt % for 3', and 13 wt % for 2. The incomplete desorption of methanol at 25 °C under vacuum points to strong host-guest interactions. PMID:26370743

  16. Determination of carboxylic acids, carbohydrates, glycerol, ethanol, and 5-HMF in beer by high-performance liquid chromatography and UV-refractive index double detection.

    PubMed

    Castellari, M; Sartini, E; Spinabelli, U; Riponi, C; Galassi, S

    2001-06-01

    A high-performance liquid chromatographic method is proposed for the simultaneous separation of main carboxylic acids, carbohydrates, ethanol, glycerol, and 5-HMF in beer by direct injection. A column packed with a sulfonated divinyl benzene-styrene copolymer and an isocratic elution with 0.0045N sulfuric acid and acetonitrile (6%, v/v) are employed. UV and refractive index detectors connected in series are also used to reduce the matrix interference of phenolic compounds. In conditions described, nine compounds are quantitated in a single chromatographic run without any pretreatment except for sample dilution and filtration before injection. Precision, accuracy, linearity of response, limit of detection, and limit of quantitation are also evaluated for each compound. Satisfactory results are obtained to justify the application of this method to all phases of beer production for process and quality control. PMID:11396687

  17. Carboxylation mechanism and stereochemistry of crotonyl-CoA carboxylase/reductase, a carboxylating enoyl-thioester reductase

    PubMed Central

    Erb, Tobias J.; Brecht, Volker; Fuchs, Georg; Müller, Michael; Alber, Birgit E.

    2009-01-01

    Chemo- and stereoselective reductions are important reactions in chemistry and biology, and reductases from biological sources are increasingly applied in organic synthesis. In contrast, carboxylases are used only sporadically. We recently described crotonyl-CoA carboxylase/reductase, which catalyzes the reduction of (E)-crotonyl-CoA to butyryl-CoA but also the reductive carboxylation of (E)-crotonyl-CoA to ethylmalonyl-CoA. In this study, the complete stereochemical course of both reactions was investigated in detail. The pro-(4R) hydrogen of NADPH is transferred in both reactions to the re face of the C3 position of crotonyl-CoA. In the course of the carboxylation reaction, carbon dioxide is incorporated in anti fashion at the C2 atom of crotonyl-CoA. For the reduction reaction that yields butyryl-CoA, a solvent proton is added in anti fashion instead of the CO2. Amino acid sequence analysis showed that crotonyl-CoA carboxylase/reductase is a member of the medium-chain dehydrogenase/reductase superfamily and shares the same phylogenetic origin. The stereospecificity of the hydride transfer from NAD(P)H within this superfamily is highly conserved, although the substrates and reduction reactions catalyzed by its individual representatives differ quite considerably. Our findings led to a reassessment of the stereospecificity of enoyl(-thioester) reductases and related enzymes with respect to their amino acid sequence, revealing a general pattern of stereospecificity that allows the prediction of the stereochemistry of the hydride transfer for enoyl reductases of unknown specificity. Further considerations on the reaction mechanism indicated that crotonyl-CoA carboxylase/reductase may have evolved from enoyl-CoA reductases. This may be useful for protein engineering of enoyl reductases and their application in biocatalysis. PMID:19458256

  18. Modeling the impact of iron-carboxylate photochemistry on radical budget and carboxylate degradation in cloud droplets and particles.

    PubMed

    Weller, Christian; Tilgner, Andreas; Bräuer, Peter; Herrmann, Hartmut

    2014-05-20

    To quantify the effects of an advanced iron photochemistry scheme, the chemical aqueous-phase radical mechanism (CAPRAM 3.0i) has been updated with several new Fe(III)-carboxylate complex photolysis reactions. Newly introduced ligands are malonate, succinate, tartrate, tartronate, pyruvate, and glyoxalate. Model simulations show that more than 50% of the total Fe(III) is coordinated by oxalate and up to 20% of total Fe(III) is bound in the newly implemented 1:1 complexes with tartronate, malonate, and pyruvate. Up to 20% of the total Fe(III) is found in hydroxo and sulfato complexes. The fraction of [Fe(oxalate)2](-) and [Fe(pyruvate)](2+) is significantly higher during nighttime than during daytime, which points toward a strong influence of photochemistry on these species. Fe(III) complex photolysis is an important additional sink for tartronate, pyruvate, and oxalate, with a complex photolysis contribution to overall degradation of 46, 40, and 99%, respectively, compared to all possible sink reactions with atmospheric aqueous-phase radicals, such as (•)OH, NO3(•), and SO4(•) (-). Simulated aerosol particles have a much lower liquid water content than cloud droplets, thus leading to high concentrations of species and, consequently, an enhancement of the photolysis sink reactions in the aerosol particles. The simulations showed that Fe(III) photochemistry should not be neglected when considering the fate of carboxylic acids, which constitute a major part of aqueous secondary organic aerosol (aqSOA) in tropospheric cloud droplets and aqueous particles. Failure to consider this loss pathway has the potential to result in a significant overestimate of aqSOA production. PMID:24678692

  19. Mixture of a molybdenum carboxylate and a molybdenum dithiophosphate or a molybdenum dithiocarbamate for use in a hydrovisbreaking process

    SciTech Connect

    Howell, J.A.; Kukes, S.G.

    1987-11-10

    A molybdenum is described containing mixture selected from the group consisting of a mixture comprising a molybdenum dithiophosphate and a molybdenum carboxylate and a mixture comprising a molybdenum dithiocarbamate and a molybdenum carboxylate.

  20. Carrier-Mediated Uptake of 1-(Malonylamino)cyclopropane-1-Carboxylic Acid in Vacuoles Isolated from Catharanthus roseus Cells 1

    PubMed Central

    Bouzayen, Mondher; Latché, Alain; Pech, Jean-Claude; Marigo, Gérard

    1989-01-01

    The uptake of 1-(malonylamino)cyclopropane-1-carboxylic acid (MACC), the conjugated form of the ethylene precursor, into vacuoles isolated from Catharanthus roseus cells has been studied by silicone layer floatation filtering. The transport across the tonoplast of MACC is stimulated fourfold by 5 millimolar MgATP, has a Km of about 2 millimolar, an optimum pH around 7, and an optimum temperature at 30°C. Several effectors known to inhibit ATPase (N,N′-dicyclohexylcarbodiimide) and to collapse the transtonoplastic H+ electrochemical gradient (carbonylcyanide m-chlorophenylhydrazone, gramicidin, and benzylamine) all reduced MACC uptake. Abolishing the membrane potential with SCN− and valinomycin also greatly inhibited MACC transport. Our data demonstrate that MACC accumulates in the vacuole against a concentration gradient by means of a proton motive force generated by a tonoplastic ATPase. The involvement of a protein carrier is suggested by the strong inhibition of uptake by compounds known to block SH—, OH—, and NH2— groups. MACC uptake is antagonized competitively by malonyl-d-tryptophan, indicating that the carrier also accepts malonyl-d-amino acids. Neither the moities of these compounds taken separately [1-aminocyclopropane-1-carboxylic acid, malonate, d-tryptophan or d-phenylalanine] nor malate act as inhibitors of MACC transport. The absence of inhibition of malate uptake by MACC suggests that MACC and malate are taken up by two different carriers. We propose that the carrier identified here plays an important physiological role in withdrawing from the cytosol MACC and malonyl-d-amino acids generated under stress conditions. PMID:16667182

  1. New silver(I) coordination polymers constructed from pyrazine derivatives and aromatic carboxylic acids: Syntheses, structures and photoluminescence

    NASA Astrophysics Data System (ADS)

    Zhang, Ting; Huang, Hua-Qi; Mei, Hong-Xin; Wang, Dan-Feng; Wang, Xiao-Xiang; Huang, Rong-Bin; Zheng, Lan-Sun

    2015-11-01

    Five one-dimensional to three-dimensional coordination polymers have been synthesized by 2-chlorobenzoic acid (HL1), 2-nitrobenzoic acid (HL2), o-toluic acid (HL3), 2,3,5-trimethylpyrazine (tpyz) and 2,3,5,6-tetramethylpyrazine (mpyz) in the presence of NH3·H2O in mixed solvents systems, namely, {Ag4(tpyz)2(L1)4}n (1), {Ag2(tpyz) (L2)2}n (2), {Ag2(tpyz) (L3)2}n (3), {Ag2(mpyz) (L1)2}n (4), {Ag(mpyz) (L2) (H2O)}n (5). All the complexes have been characterized by elemental analyses, IR spectra and X-ray diffraction. Compound 1 shows a 3D framework. The tpyz ligand links 1D chain which was connected by silver atom and L1 anion into 3D framework. Compounds 2 and 4 possess a similar 2D network with (4, 4) topology. Complex 3 also exhibits a two-dimensional structure. There is a 1D silver chain in 3, which is the main difference from 2 and 4. So, 3 shows three-connected (4 8, 3) topology. For 5, only one oxygen of L2 coordinated to Ag(I) ions. The L2 anions were arranged in both sides of the chain, which was connected by silver atoms and mpyz ligands. Then, the uncoordinated carboxylate oxygen with coordinated water 1molecule oxygen through the hydrogen bond made the resultant structure to a 3D framework. Complexes 1-5 spanning from one-dimensional chains to three-dimensional framework suggest that carboxylates and the kinds of pyrazine derivatives play significant roles in the formation of such coordination architectures. The photoluminescence and thermogravimetric analysis (TGA) of the complexes were also investigated.

  2. High fluorescence emission of carboxylic acid functionalized polystyrene/BaTiO{sub 3} nanocomposites and rare earth metal complexes: Preparation and characterization

    SciTech Connect

    Cao, X. T.; Showkat, A. M.; Wang, Z.; Lim, K. T.

    2015-03-30

    Noble fluorescence nanocomposite compound based on barium titanate nanoparticles (BTO), polystyrene (PSt), and terbium ion (Tb{sup 3+}) was synthesized by a combination of surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization, Friedel-Crafts alkylation reaction and coordinate chemistry. Initially, a modification of surface of BTO was conducted by an exchange process with S-benzyl S’-trimethoxysilylpropyltrithiocarbonate to create macro-initiator for polymerization of styrene. Subsequently, aryl carboxylic acid functionalized polystyrene grafted barium titanate (BTO-g-PSt-COOH) was generated by substitution reaction between 4-(Chloromethyl) benzoic acid and PSt chains. The coordination of the nanohybrids with Tb{sup 3+} ions afforded fluorescent Tb{sup 3+} tagged aryl carboxylic acid functionalized polystyrene grafted barium titanate (BTO-g-PSt-Tb{sup 3+}) complexes. Structure, morphology, and fluorescence properties of nanohybrid complexes were investigated by respective physical and spectral studies. FT-IR and SEM analyses confirmed the formation of BTO-g-PSt-Tb{sup 3+}nanohybrids. Furthermore, TGA profiles demonstrated the grafting of aryl carboxylic acid functionalized polystyrene on BTO surface. Optical properties of BTO-g-PSt-Tb{sup 3+} complexes were investigated by fluorescence spectroscopy.

  3. High fluorescence emission of carboxylic acid functionalized polystyrene/BaTiO3 nanocomposites and rare earth metal complexes: Preparation and characterization

    NASA Astrophysics Data System (ADS)

    Cao, X. T.; Showkat, A. M.; Wang, Z.; Lim, K. T.

    2015-03-01

    Noble fluorescence nanocomposite compound based on barium titanate nanoparticles (BTO), polystyrene (PSt), and terbium ion (Tb3+) was synthesized by a combination of surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization, Friedel-Crafts alkylation reaction and coordinate chemistry. Initially, a modification of surface of BTO was conducted by an exchange process with S-benzyl S'-trimethoxysilylpropyltrithiocarbonate to create macro-initiator for polymerization of styrene. Subsequently, aryl carboxylic acid functionalized polystyrene grafted barium titanate (BTO-g-PSt-COOH) was generated by substitution reaction between 4-(Chloromethyl) benzoic acid and PSt chains. The coordination of the nanohybrids with Tb3+ ions afforded fluorescent Tb3+ tagged aryl carboxylic acid functionalized polystyrene grafted barium titanate (BTO-g-PSt-Tb3+) complexes. Structure, morphology, and fluorescence properties of nanohybrid complexes were investigated by respective physical and spectral studies. FT-IR and SEM analyses confirmed the formation of BTO-g-PSt-Tb3+nanohybrids. Furthermore, TGA profiles demonstrated the grafting of aryl carboxylic acid functionalized polystyrene on BTO surface. Optical properties of BTO-g-PSt-Tb3+ complexes were investigated by fluorescence spectroscopy.

  4. Crystal structure of trans-di­aqua­bis­(1H-pyrazole-3-carboxyl­ato-κ2 N,O)copper(II) dihydrate

    PubMed Central

    Reinoso, Santiago; Artetxe, Beñat; Castillo, Oscar; Luque, Antonio; Gutiérrez-Zorrilla, Juan M.

    2015-01-01

    In the title compound, [Cu(C4H3N2O2)2(H2O)2]·2H2O, the CuII ion is located on an inversion centre and exhibits an axially elongated octa­hedral coordination geometry. The equatorial plane is formed by two N,O-bidentate 1H-pyrazole-3-carboxyl­ate ligands in a trans configuration. The axial positions are occupied by two water mol­ecules. The mononuclear complex mol­ecules are arranged in layers parallel to the ab plane. Each complex mol­ecule is linked to four adjacent species through inter­molecular O—H⋯O and N—H⋯O hydrogen bonds that are established between the coordinating water mol­ecules and carboxyl­ate O atoms or protonated N atoms of the organic ligands. These layers are further connected into a three-dimensional network by additional hydrogen bonds involving solvent water mol­ecules and non-coordinating carboxyl­ate O atoms. PMID:26870440

  5. Determination of alkylphenols and alkylphenol carboxylates in wastewater and river samples by hemimicelle-based extraction and liquid chromatography-ion trap mass spectrometry.

    PubMed

    Cantero, Manuel; Rubio, Soledad; Pérez-Bendito, Dolores

    2006-07-01

    Sodium dodecyl sulfate (SDS)-coated alumina and cetylpyridinium chloride (CPC)-coated silica were investigated as new sorbents for the concentration of alkylphenol polyethoxylate (APE) biodegradation products from wastewater and river water samples. Octylphenol (OP), nonylphenol (NP), octylphenol carboxylic acid (OPC) and nonylphenol carboxylic acid (NPC) were quantitatively retained on both supramolecular sorbents on the basis of the formation of mixed hemimicelles and admicelles. SDS hemimicelles-based SPE was proposed for the extraction/concentration of the target compounds prior to their separation and quantitation by liquid chromatography/electrospray ionization in negative mode, ion trap mass spectrometry. No clean-up steps or evaporation of the eluent were required. The recovery of APE metabolites from sewage and river water ranged between 87 and 100%. Concentration factors of about 500, using sample volumes of 1 l, were achieved. Detection limits were between 75 and 193 ng/l. The approach developed was applied to the determination of alklylphenols and alkylphenol carboxylic acids in raw and treated sewage and river samples. The concentrations of APE metabolites found ranged between 0.8 and 78 microg/l. PMID:16412449

  6. Synthesis of novel ethyl 1-ethyl-6-fluoro-7-(fatty amido)-1,4-dihydro-4-oxoquinoline-3-carboxylate derivatives and their biological evaluation.

    PubMed

    Venepally, Vijayendar; Prasad, R B N; Poornachandra, Y; Kumar, C Ganesh; Jala, Ram Chandra Reddy

    2016-01-15

    A series of novel ethyl 1-ethyl-6-fluoro-7-(fatty amido)-1,4-dihydro-4-oxoquinoline-3-carboxylate derivatives were prepared through multistep synthesis. The key step in the synthesis was to obtain the C-7 fatty amide derivative. The azide was selectively formed at C-7 position using sodium azide at 60°C. Subsequently, the azide was reduced under mild conditions using zinc and ammonium chloride to form the corresponding amine. The synthesized derivatives were further subjected to biological evaluation studies like cytotoxicity against a panel of cancer cell lines such as DU145, A549, SKOV3, MCF7 and normal lung cells, IMR-90 as well as with antimicrobial and antioxidant activities. It was observed that the carboxylated quinolone derivatives with hexanoic (8a), octanoic (8b), lauric (8d) and myristic (8e) moieties exhibited promising cytotoxicity against all the tested cancer cell lines. The results also suggested that hexanoic acid-based fatty amide carboxylated quinolone derivative (8a) exhibited promising activity against both bacterial and fungal strains and significant antibacterial activity was observed against Staphylococcus aureus MTCC 96 (MIC value of 3.9μg/mL). The compound 8a also showed excellent anti-biofilm activity against Staphylococcus aureus MTCC 96 and Bacillus subtilis MTCC 121 with MIC values of 2.1 and 4.6μg/mL, respectively. PMID:26646219

  7. Regeneration of carboxylic acid-laden basic sorbents by leaching with a volatile base in an organic solvent

    DOEpatents

    King, C. Judson; Husson, Scott M.

    1999-01-01

    Carboxylic acids are sorbed from aqueous feedstocks onto a solid adsorbent. The acids are freed from the sorbent phase by treating it with an organic solution of alkylamine thus forming an alkylamine/carboxylic acid complex which is decomposed with improved efficiency to the desired carboxylic acid and the alkylamine. Carbon dioxide addition can be used to improve the adsorption or the carboxylic acids by the solid phase sorbent.

  8. Copper(II)-Promoted Cyclization/Difunctionalization of Allenols and Allenylsulfonamides: Synthesis of Heterocycle-Functionalized Vinyl Carboxylate Esters.

    PubMed

    Casavant, Barbara J; Khoder, Zainab M; Berhane, Ilyas A; Chemler, Sherry R

    2015-12-18

    A unique method to affect intramolecular aminooxygenation and dioxygenation of allenols and allenylsulfonamides is described. These operationally simple reactions occur under neutral or basic conditions where copper(II) carboxylates serve as reaction promoter, oxidant, and carboxylate source. Moderate to high yields of heterocycle-functionalized vinyl carboxylate esters are formed with moderate to high levels of diastereoselectivity. Such vinyl carboxylate esters could serve as precursors to α-amino and α-oxy ketones and derivatives thereof. PMID:26624861

  9. Reactions of trialkyl phosphites with cyclopentadienones in presence of proton-donor reagents. III. Reactions of trimethyl phosphite with phencyclone in presence of carboxylic acids

    SciTech Connect

    Arbuzov, B.A.; Fuzhenkova, A.V.; Kharitonova, L.V.

    1987-11-20

    In presence of carboxylic acids trimethyl phosphite and phencyclone react with the formation of products with a bond between the C/sup 2/ atom of the cyclopentadienone system and phosphorus and with a bond between oxygen of the cyclone and phosphorus; dihydrophencyclone is also formed. The proportions of the products are influenced by the proportions of the reactants and the reaction temperature. The IR spectra of the compounds were determined on UR-10 and Specord 75-IR spectrometers. The PMR spectra were recorded on Varian T-60 and Tesla BS-467A spectrometers. As solvents the authors used chloroform, chloroform-d, and carbon tetrachloride.

  10. Crystal structures of methyl 3-(4-iso-propyl-phen-yl)-1-methyl-1,2,3,3a,4,9b-hexa-hydro-thio-chromeno[4,3-b]pyrrole-3a-carboxyl-ate, methyl 1-methyl-3-(o-tol-yl)-1,2,3,3a,4,9b-hexa-hydro-thio-chromeno[4,3-b]pyrrole-3a-carboxyl-ate and methyl 1-methyl-3-(o-tol-yl)-3,3a,4,9b-tetra-hydro-1H-thio-chromeno[4,3-c]isoxazole-3a-carboxyl-ate.

    PubMed

    Raja, R; Suresh, M; Raghunathan, R; SubbiahPandi, A

    2015-06-01

    In the title compounds, C23H27NO2S, (I), and C21H23NO2S, (II), the pyrrole rings have envelope conformations with the C atom substituted by the benzene ring as the flap. In the third title compound, C20H21NO3S, (III), the isoxazole ring has a twisted conformation on the C-C bond substituted by the benzene ring and the carboxyl-ate group. In all three compounds, the thio-pyran ring has a half-chair conformation. The mean plane of the pyrrole ring is inclined to the mean plane of the thio-pyran ring by 57.07 (9), 58.98 (9) and 60.34 (12)° in (I), (II) and (III), respectively. The benzene rings are inclined to one another by 73.26 (10)° in (I), 65.781)° in (II) and 63.37 (13)° in (III). In the crystals of all three compounds, there are no classical hydrogen bonds present. Only in the crystal of compound (I) are mol-ecules linked by a pair of C-H⋯π inter-actions, forming inversion dimers. The isopropyl group in compound (I) is disordered over two sets of sites and has a refined occupancy ratio of 0.586 (13):0.414 (13). PMID:26090125

  11. Coumarin carboxylic acids as monocarboxylate transporter 1 inhibitors: In vitro and in vivo studies as potential anticancer agents.

    PubMed

    Gurrapu, Shirisha; Jonnalagadda, Sravan K; Alam, Mohammad A; Ronayne, Conor T; Nelson, Grady L; Solano, Lucas N; Lueth, Erica A; Drewes, Lester R; Mereddy, Venkatram R

    2016-07-15

    Novel N,N-dialkyl carboxy coumarins have been synthesized as potential anticancer agents via inhibition of monocarboxylate transporter 1 (MCT1). These coumarin carboxylic acids have been evaluated for their in vitro MCT1 inhibition, MTT cancer cell viability, bidirectional Caco-2 cell permeability, and stability in human and liver microsomes. These results indicate that one of the lead candidate compounds 4a has good absorption, metabolic stability, and a low drug efflux ratio. Systemic toxicity studies with lead compound 4a in healthy mice demonstrate that this inhibitor is well tolerated based on zero animal mortality and normal body weight gains compared to the control group. In vivo tumor growth inhibition studies in mice show that the candidate compound 4a exhibits significant single agent activity in MCT1 expressing GL261-luc2 syngraft model but doesn't show significant activity in MCT4 expressing MDA-MB-231 xenograft model, indicating the selectivity of 4a for MCT1 expressing tumors. PMID:27241692

  12. 40 CFR 721.984 - Amino-hydroxy sulfonaphthylazo-disubstituted phenyl azo benzene carboxylate salt (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...-disubstituted phenyl azo benzene carboxylate salt (generic). 721.984 Section 721.984 Protection of Environment...-disubstituted phenyl azo benzene carboxylate salt (generic). (a) Chemical substance and significant new uses...-disubstituted phenyl azo benzene carboxylate salt (PMN P-00-0351) is subject to reporting under this section...

  13. 40 CFR 721.984 - Amino-hydroxy sulfonaphthylazo-disubstituted phenyl azo benzene carboxylate salt (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...-disubstituted phenyl azo benzene carboxylate salt (generic). 721.984 Section 721.984 Protection of Environment...-disubstituted phenyl azo benzene carboxylate salt (generic). (a) Chemical substance and significant new uses...-disubstituted phenyl azo benzene carboxylate salt (PMN P-00-0351) is subject to reporting under this section...

  14. 40 CFR 721.984 - Amino-hydroxy sulfonaphthylazo-disubstituted phenyl azo benzene carboxylate salt (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-disubstituted phenyl azo benzene carboxylate salt (generic). 721.984 Section 721.984 Protection of Environment...-disubstituted phenyl azo benzene carboxylate salt (generic). (a) Chemical substance and significant new uses...-disubstituted phenyl azo benzene carboxylate salt (PMN P-00-0351) is subject to reporting under this section...

  15. 40 CFR 721.984 - Amino-hydroxy sulfonaphthylazo-disubstituted phenyl azo benzene carboxylate salt (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...-disubstituted phenyl azo benzene carboxylate salt (generic). 721.984 Section 721.984 Protection of Environment...-disubstituted phenyl azo benzene carboxylate salt (generic). (a) Chemical substance and significant new uses...-disubstituted phenyl azo benzene carboxylate salt (PMN P-00-0351) is subject to reporting under this section...

  16. 40 CFR 721.984 - Amino-hydroxy sulfonaphthylazo-disubstituted phenyl azo benzene carboxylate salt (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-disubstituted phenyl azo benzene carboxylate salt (generic). 721.984 Section 721.984 Protection of Environment...-disubstituted phenyl azo benzene carboxylate salt (generic). (a) Chemical substance and significant new uses...-disubstituted phenyl azo benzene carboxylate salt (PMN P-00-0351) is subject to reporting under this section...

  17. Speciation and source identification of organic compounds in PM₁₀ over Seoul, South Korea.

    PubMed

    Choi, Na Rae; Lee, Se Pyo; Lee, Ji Yi; Jung, Chang Hoon; Kim, Yong Pyo

    2016-02-01

    Seventy three individual organic compounds in the atmospheric particulate matter with an aerodynamic diameter of less than or equal to a nominal 10 μm (PM10) over Seoul were identified and quantified from April 2010 to April 2011 using gas chromatography/mass spectrometry (GC/MS). These organic compounds were classified into five groups, n-alkanes, polycyclic aromatic hydrocarbons (PAHs), mono-carboxylic acids, di-carboxylic acids (DCAs), and sugars based on their chemical structures and properties. The organic compounds showed higher seasonal average concentrations from fall to winter than from spring to summer due to source strength, except some organic compounds among mono-carboxylic acids, DCAs, sugars such as undecanoic acid, methylmalonic acid, and fructose. Through qualitative data analysis using seasonal concentration variations and relevant diagnostic parameters, it was found that (1) anthropogenic sources such as combustion of fossil fuel and biomass burning attributed more to the formation of the organic aerosols than biogenic sources, and (2) the ambient level of n-alkanes, PAHs, and some compounds of DCAs and sugars was elevated in winter due to the increased primary emissions and larger transport from outside of the organic compounds in winter. PMID:26517386

  18. Luminescent hybrid lanthanide sulfates and lanthanide sulfonate-carboxylates with 1,10-phenanthroline involving in-situ oxidation of 2-mercaptonbenzoic acid

    SciTech Connect

    Zhong, Jie-Cen; Wan, Fang; Sun, Yan-Qiong; Chen, Yi-Ping

    2015-01-15

    A series of lanthanide sulfates and lanthanide sulfonate-carboxylates, [Ln{sub 2}(phen){sub 2}(SO{sub 4}){sub 3}(H{sub 2}O){sub 2}]{sub n} (I:Ln=Nd(1a), Sm(1b), Eu(1c), phen=1,10-phenanthroline) and [Ln(phen)(2-SBA)(BZA)]{sub n} (II: Ln=Sm(2a), Eu(2b), Dy(2c), 2-SBA=2-sulfobenzoate, BZA=benzoate) have been hydrothermally synthesized from lanthanide oxide, 2-mercaptonbenzoic acid with phen as auxiliary ligand and characterized by single-crystal X-ray diffraction, elemental analyses, IR spectra, TG analyses and luminescence spectroscopy. Interestingly, SO{sub 4}{sup 2−} anions in I came from the in situ deep oxidation of thiol groups of 2-mercaptonbenzoic acid while 2-sulfobenzoate and benzoate ligands in II from the middle oxidation and desulfuration reactions of 2-mercaptonbenzoic acid. Compounds I are organic–inorganic hybrid lanthanide sulfates, which have rare one-dimensional column-like structures. Complexes II are binuclear lanthanide sulfonate-carboxylates with 2-sulfobenzoate and benzoate as bridges and 1,10-phenanthroline as terminal. Photoluminescence studies reveal that complexes I and II exhibit strong lanthanide characteristic emission bands in the solid state at room temperature. - Graphical abstract: Lanthanide sulfates and lanthanide sulfonate-carboxylates have been hydrothermally synthesized. Interestingly, sulfate anions, 2-sulfobenzoate and benzoate ligands came from the in situ oxidation and desulfuration reactions of 2-mercaptonbenzoic acid. - Highlights: • In situ oxidation and desulfuration reactions of 2-mercaptonbenzoic acid. • The organic–inorganic hybrid lanthanide sulfates with one-dimensional column-like structure. • The dinuclear lanthanide sulfonate-carboxylates. • The emission spectra exhibit the characteristic transition of {sup 5}D{sub 0}→{sup 7}F{sub J} (J=0–4) of the Eu(III)

  19. Carboxylate-phenolate tautomerism in 5-[(nitrophenyl)diazenyl]salicylate anions.

    PubMed

    Yatsenko, Alexandr V; Paseshnichenko, Ksenia A

    2016-04-01

    Aryldiazenyl derivatives of salicylic acid and their salts are used as dyes. In these structures, the carboxylate groups are engaged in short contacts with the cations and in hydrogen bonds with water molecules, if present. If both O atoms of the carboxylate group take part in such interactions, the negative charge is delocalized over the two atoms. In the absence of hydrogen bonds and contacts with cations, the negative charge is localized on one of the O atoms. In the crystal structures of tetramethylammonium 2-hydroxy-5-[(E)-(4-nitrophenyl)diazenyl]benzoate and tetramethylammonium 2-hydroxy-5-[(E)-(2-nitrophenyl)diazenyl]benzoate, both C4H12N(+)·C13H8N3O5(-), all the interactions between the cations and anions are weak, and their effect on the geometry of the anions is negligible. Under these conditions, the 2-nitro-substituted anion is an almost pure phenol-carboxylate tautomer, whereas in the 4-nitro-substituted anion, the phenolic H atom is shifted towards the carboxylate group, and thus the structure of this anion is intermediate between the phenol-carboxylate and phenolate-carboxylic acid tautomeric forms. The probable formation of such an intermediate form is supported by quantum chemical calculations. Being the characteristic feature of this form, a short distance between the phenolic and carboxylate O atoms is observed in the 4-nitro-substituted anion, as well as in the structures of some 3,5-dinitrosalicylates reported in the literature. PMID:27045176

  20. Characterization and diagenesis of strong-acid carboxyl groups in humic substances

    USGS Publications Warehouse

    Leenheer, J.A.; Wershaw, R. L.; Brown, G.K.; Reddy, M.M.

    2003-01-01

    A small fraction of carboxylic acid functional groups in humic substances are exceptionally acidic with pKa values as low as 0.5. A review of acid-group theory eliminated most models and explanations for these exceptionally acidic carboxyl groups. These acidic carboxyl groups in Suwannee River fulvic acid were enriched by a 2-stage fractionation process and the fractions were characterized by elemental, molecular-weight, and titrimetric analyses, and by infrared and 13C- and 1H-nuclear magnetic resonance spectrometry. An average structural model of the most acidic fraction derived from the characterization data indicated a high density of carboxyl groups clustered on oxygen-heterocycle alicyclic rings. Intramolecular H-bonding between adjacent carboxyl groups in these ring structures enhanced stabilization of the carboxylate anion which results in low pKa1 values. The standard, tetrahydrofuran tetracarboxylic acid, was shown to have similar acidity characteristics to the highly acidic fulvic acid fraction. The end products of 3 known diagenetic pathways for the formation of humic substances were shown to result in carboxyl groups clustered on oxygen-heterocycle alicyclic rings.

  1. [Determination of the carboxyl content of oxidized starch by fourier transform infrared (FTIR) spectroscopy].

    PubMed

    Ding, Long-Long; Zhang, Yan-Hua; Gu, Ji-You; Tan, Hai-Yan; Zhu, Li-Bin

    2014-02-01

    In the present study, the carboxyl content of oxidized starch was determined by FTIR spectroscopy. Standard curve was drawn in which the ordinate was carboxyl content determined by national standard method with the ratio of carbonyl absorbance to the key of C-H absorbance in FTIR spectroscopy as the abscissa. The ratio of absorbance of unknown oxidized starch tested by FTIR spectroscopy was obtained, The carboxyl content was calculated by standard curve, and then compared with the carboxyl content determined by national standard method, and the deviation is between 2% and 4%. In order to improve the accuracy of the experiment, standard sample was selected to draw standard curve to better ensure that the carboxyl content of the unknown oxidized starch is in the range of standard curve calculation limit, and deviates from the limit of standard curve. Compared with the carboxyl content determined by national standard method, testing with FTIR spectroscopy is simple, easy to operate, and of high efficiency and better accuracy. So, it is significant to forecast the carboxyl content of oxidized starch by FTIR spectroscopy. PMID:24822409

  2. High-temperature pyrolysis mechanisms of coal model compounds

    SciTech Connect

    Penn, J.H.; Owens, W.H.

    1991-01-01

    The degradation of the carboxylic acid group has been examined with respect to potential pretreatment strategies for fossil fuel conversion processes. In one potential pretreatment strategy involving cation exchange of the carboxylic acid group, a series of benzoic acid and stearic acid salts have been chosen to model the tight'' carboxylic acids of immature fossil fuel feedstocks and have been pyrolyzed with an entrained flow reactor. Our preliminary results indicate that Group I and II salts yield primarily the parent acid. Benzoate salts also yield small amounts of benzene while the stearic acid salts give no other detectable products. In two alternative treatment strategies, esterification and anhydride preparation have also been accomplished with these compounds being subjected to the entrained flow reactor conditions. The benzoate esters give a number of products, such as benzaldehyde, benzene, and low MW gases. The formation of these compounds is extremely dependent on pyrolysis conditions and alkoxy chain length. A xenon flashlamp and an entrained flow reactor have been used to heat organic substrates to varying temperatures using different heating rates. Ultrarapid flashlamp pyrolysis (heating rate>10{sup 50}C/s) has been performed. Since the ultrarapid pyrolysis products differ from those observed with traditional heating techniques and differ from the products formed photochemically, the flashlamp pyrolysis products are attributed to high temperature thermal activation.

  3. Modified carbohydrate-chitosan compounds, methods of making the same and methods of using the same

    DOEpatents

    Venditti, Richard A; Pawlak, Joel J; Salam, Abdus; El-Tahlawy, Khaled Fathy

    2015-03-10

    Compositions of matter are provided that include chitosan and a modified carbohydrate. The modified carbohydrate includes a carbohydrate component and a cross linking agent. The modified carbohydrate has increased carboxyl content as compared to an unmodified counterpart carbohydrate. A carboxyl group of the modified carbohydrate is covalently bonded with an amino group of chitosan. The compositions of matter provided herein may include cross linked starch citrate-chitosan and cross linked hemicellulose citrate-chitosan, including foams thereof. These compositions yield excellent absorbency and metal chelation properties. Methods of making cross linked modified carbohydrate-chitosan compounds are also provided.

  4. Transition from Bioinert to Bioactive Material by Tailoring the Biological Cell Response to Carboxylated Nanocellulose.

    PubMed

    Hua, Kai; Rocha, Igor; Zhang, Peng; Gustafsson, Simon; Ning, Yi; Strømme, Maria; Mihranyan, Albert; Ferraz, Natalia

    2016-03-14

    This work presents an insight into the relationship between cell response and physicochemical properties of Cladophora cellulose (CC) by investigating the effect of CC functional group density on the response of model cell lines. CC was carboxylated by electrochemical TEMPO-mediated oxidation. By varying the amount of charge passed through the electrolysis setup, CC materials with different degrees of oxidation were obtained. The effect of carboxyl group density on the material's physicochemical properties was investigated together with the response of human dermal fibroblasts (hDF) and human osteoblastic cells (Saos-2) to the carboxylated CC films. The introduction of carboxyl groups resulted in CC films with decreased specific surface area and smaller total pore volume compared with the unmodified CC (u-CC). While u-CC films presented a porous network of randomly oriented fibers, a compact and aligned fiber pattern was depicted for the carboxylated-CC films. The decrease in surface area and total pore volume, and the orientation and aggregation of the fibers tended to augment parallel to the increase in the carboxyl group density. hDF and Saos-2 cells presented poor cell adhesion and spreading on u-CC, which gradually increased for the carboxylated CC as the degree of oxidation increased. It was found that a threshold value in carboxyl group density needs be reached to obtain a carboxylated-CC film with cytocompatibility comparable to commercial tissue culture material. Hence, this study demonstrates that a normally bioinert nanomaterial can be rendered bioactive by carefully tuning the density of charged groups on the material surface, a finding that not only may contribute to the fundamental understanding of biointerface phenomena, but also to the development of bioinert/bioactive materials. PMID:26886265

  5. The synthesis, structure and properties of N-acetylated derivatives of ethyl 3-amino-1H-pyrazole-4-carboxylate.

    PubMed

    Kusakiewicz-Dawid, Anna; Masiukiewicz, Elzbieta; Rzeszotarska, Barbara; Dybała, Izabela; Kozioł, Anna Eugenia; Broda, Małgorzata Anna

    2007-05-01

    Ethyl 3-amino-1H-pyrazole-4-carboxylate (1) was yielded through total synthesis and reacted with acetic anhydride to give the acetylated products 2-6. Compounds 1-6 were studied with HPLC, X-ray, FT-IR, (1)H-NMR, (13)C-NMR and MS. Acetylation was carried out in solvents of various polarity, namely; chloroform; dioxane; DMF; acetic anhydride, at room temperature and at boiling points; and in the presence and absence of DMAP. The acetylated products are mainly nitrogen atoms in the ring. The position of the ring proton in the solution was based on NOESY; multinuclear HMBC, HSQC spectra and calculations. For equivalent amounts (1-1.5 mol) of acetic anhydride at room temperature two products of monoacetylation are produced in the ring: 2 and 3, ca. 2 : 1 and at the same time only small amount of the third product of monoacetylated, 5 in DMF, as well the product diacetylated, 4. The greatest amount of the product 4 is produced during the reaction with chloroform. However, in this solvent and in dioxane no product 5 is produced. Compound 2 is, largely, formed in dimethylformamide, in the presence DMAP, 0.2 eq. In the presence of this catalytic base, for the first hour, there is a mixture 2 and 3 to the ratio ca. 95 : 5. With 8 eq of Ac(2)O at reflux, after another hour, the compounds 3, 4 and 6 appear about equal amounts. After a longer time, the compound, which appears most in this mixture is triacetylated derivative 6. The structural and spectroscopic characteristics of compounds 1-6 have been given and the methods for their preparation have been provided. PMID:17473461

  6. Thermal pretreatment of olive mill wastewater for efficient methane production: control of aromatic substances degradation by monitoring cyclohexane carboxylic acid.

    PubMed

    Pontoni, Ludovico; d'Antonio, Giuseppe; Esposito, Giovanni; Fabbricino, Massimiliano; Frunzo, Luigi; Pirozzi, Francesco

    2015-01-01

    Anaerobic digestion is investigated as a sustainable depurative strategy of olive oil mill wastewater (OOMW). The effect of thermal pretreatment on the anaerobic biodegradation of aromatic compounds present in (OMWW) was investigated. The anaerobic degradation of phenolic compounds, well known to be the main concern related to this kind of effluents, was monitored in batch anaerobic tests at a laboratory scale on samples pretreated at mild (80±1 °C), intermediate (90±1 °C) and high temperature (120±1 °C). The obtained results showed an increase of 34% in specific methane production (SMP) for OMWW treated at the lowest temperature and a decrease of 18% for treatment at the highest temperature. These results were related to the different decomposition pathways of the lignocellulosic compounds obtained in the tested conditions. The decomposition pathway was determined by measuring the concentrations of volatile organic acids, phenols, and chemical oxygen demand (COD) versus time. Cyclohexane carboxylic acid (CHCA) production was identified in all the tests with a maximum concentration of around 200 µmol L(-1) in accordance with the phenols degradation, suggesting that anaerobic digestion of aromatic compounds follows the benzoyl-CoA pathway. Accurate monitoring of this compound was proposed as the key element to control the process evolution. The total phenols (TP) and total COD removals were, with SMP, the highest (TP 62.7%-COD 63.2%) at 80 °C and lowest (TP 44.9%-COD 32.2%) at 120 °C. In all cases, thermal pretreatment was able to enhance the TP removal ability (up to 42% increase). PMID:25624137

  7. Sorption of heavy metal ions onto carboxylate chitosan derivatives--a mini-review.

    PubMed

    Boamah, Peter Osei; Huang, Yan; Hua, Mingqing; Zhang, Qi; Wu, Jingbo; Onumah, Jacqueline; Sam-Amoah, Livingstone K; Boamah, Paul Osei

    2015-06-01

    Chitosan is of importance for the elimination of heavy metals due to their outstanding characteristics such as the presence of NH2 and -OH functional groups, non-toxicity, low cost and, large available quantities. Modifying a chitosan structure with -COOH group improves it in terms of solubility at pH ≤7 without affecting the aforementioned characteristics. Chitosan modified with a carboxylic group possess carboxyl, amino and hydroxyl multifunctional groups which are good for elimination of metal ions. The focal point of this mini-review will be on the preparation and characterization of some carboxylate chitosan derivatives as a sorbent for heavy metal sorption. PMID:25791666

  8. Effect of carboxylic acid adsorption on the hydrolysis and sintered properties of aluminum nitride powder

    SciTech Connect

    Egashira, Makoto; Shimizu, Yasuhiro; Takao, Yuji; Yamaguchi, Ryoji; Ishikawa, Yasuhiro . Dept. of Materials Science and Engineering)

    1994-07-01

    To suppress the reactivity of AlN powder with water, chemical surface modification with carboxylic acids has been investigated. It was found that the chemical stability of AlN powder increased as the number of carbon atoms in carboxylic acids used for the surface treatment increased. Among the carboxylic acids tested, stearic acid was the most promising from the viewpoint of the chemical stability of the treated powder and the thermal conductivity of the sintered ceramics prepared by cold isostatic pressing and pressureless sintering.

  9. Palladium(II)-Catalyzed Tandem Synthesis of Acenes Using Carboxylic Acids as Traceless Directing Groups.

    PubMed

    Kim, Kiho; Vasu, Dhananjayan; Im, Honggu; Hong, Sungwoo

    2016-07-18

    A straightforward synthetic strategy for generating useful anthracene derivatives was developed involving palladium(II)-catalyzed tandem transformation with carboxylic acids as traceless directing groups. Carboxyl-directed C-H alkenylation, carboxyl-directed secondary C-H activation and rollover, intramolecular C-C bond formation, and decarboxylative aromatization are proposed as the key steps in the tandem reaction pathway. This novel synthetic route utilizes a broad range of substrates and provides a convenient synthetic tool that allows access to acenes. PMID:27244536

  10. Photophysics of indole-2-carboxylic acid (I2C) and indole-5-carboxylic acid (I5C): heavy atom effect.

    PubMed

    Kowalska-Baron, Agnieszka; Gałęcki, Krystian; Wysocki, Stanisław

    2013-12-01

    In this study the effect of carboxylic group substitution in the 2 and 5 position of indole ring on the photophysics of the parent indole chromophore has been studied. The photophysical parameters crucial in triplet state decay mechanism of aqueous indole-2-carboxylic acid (I2C) and indole-5-carboxylic acid (I5C) have been determined applying our previously proposed methodology based on the heavy atom effect and fluorescence and phosphorescence decay kinetics [Kowalska-Baron et al., 2012]. The determined time-resolved phosphorescence spectra of I2C and I5C are red-shifted as compared to that of the parent indole. This red-shift was especially evident in the case of I2C and may indicate the possibility of hydrogen bonded complex formation incorporating carbonyl CO, the NH group of I2C and, possibly, surrounding water molecules. The possibility of the excited state charge transfer process and the subsequent electronic charge redistribution in such a hydrogen bonded complex may also be postulated. The resulting stabilization of the I2C triplet state is manifested by its relatively long phosphorescence lifetime in aqueous solution (912 μs). The relatively short phosphorescence lifetime of I5C (56 μs) may be the consequence of more effective ground-state quenching of I5 C triplet state. This hypothesis may be strengthened by the significantly larger value of the determined rate constant of I5C triplet state quenching by its ground-state (4.4 × 10(8)M(-1)s(-1)) as compared to that for indole (6.8 × 10(7)M(-1)s(-1)) and I2C (2.3 × 10(7)M(-1)s(-1)). The determined bimolecular rate constant for triplet state quenching by iodide [Formula: see text] is equal to 1 × 10(4)M(-1)s(-1); 6 × 10(3)M(-1)s(-1) and 2.7 × 10(4)M(-1)s(-1) for indole, I2 C and I5 C, respectively. In order to obtain a better insight into iodide quenching of I2C and I5C triplet states in aqueous solution, the temperature dependence of the bimolecular rate constants for iodide quenching of the

  11. Variable Denticity in Carboxylate Binding to the Uranyl Coordination Complexes

    SciTech Connect

    G. S. Groenewold; W. A. de Jong; J. Oomens; M. J. van Stipdonk

    2010-05-01

    Tris-carboxylate complexes of the uranyl [UO2]2+ cation with acetate and benzoate were generated using electrospray ionization mass spectrometry, and then isolated in a Fourier transform ion cyclotron resonance mass spectrometer. Wavelength-selective infrared multiple photon dissociation (IRMPD) of the tris-acetatouranyl anion resulted in a redox elimination of an acetate radical, which was used to generate an IR spectrum that consisted of six prominent absorption bands. These were interpreted with the aid of density functional theory calculations in terms of a symmetric and antisymmetric –CO2 stretches of both the monodentate and bidentate acetate, CH3 bending and umbrella vibrations, and a uranyl OUO asymmetric stretch. The comparison of the calculated and measured IR spectra indicated that the tris-acetate complex contained two acetate ligands bound in a bidentate fashion, while the third acetate was monodentate. In similar fashion, the tris-benzoate uranyl anion was formed and photodissociated by loss of a benzoate radical, enabling measurement of the infrared spectrum that was in close agreement with that calculated for a structure containing one monodentate, and two bidentate benzoate ligand.

  12. Protolytic equilibria on the surface of carboxyl-containing silica

    SciTech Connect

    Mil'chenko, D.V.; Kudryavtsev, G.V.; Lisichkin, G.V.

    1986-09-01

    Potentiometric titration has been used to study the protolytic equilibria on the surface of carboxyl-containing silica (CS) prepared by the reaction of silica (Silokhrom S-80, S /SUB sp/ = 80 m2/g) with C1/sub 3/SiCH/sub 2/CH/sub 2/COOCH/sub 3/, followed by hydrolysis with 30% sulfuric acid. The titration curve of the vacuum-dried sample is irreversible. The titration curve of its Na+ form with hydrochloric acid proceeds lower than the titration curve of its H+ form and coincides with the titration curve of the air-dried sample (the last curve is reversible). The titration curve of CS coincides with the titration curve of butyric acid at pH < 6. At pH > 6 the titration curve of CS passes below the titration curve of butyric acid; this is due to the participation of silanol groups on the silica surface in the protolytic equilibria. The pK /SUB a/ of the grafted CS groups is equal to 4.80 which is close to the pK /SUB a/ value of butyric acid (4.78). A method has been proposed for the determination of the amount of weak acid groups grafted to the silica. It has been shown that in the titration of CS the equilibrium is established much faster than in the case of the unmodified silica.

  13. Determination of perfluoroalkyl carboxylic, sulfonic, and phosphonic acids in food.

    PubMed

    Ullah, Shahid; Alsberg, Tomas; Vestergren, Robin; Berger, Urs

    2012-11-01

    A sensitive and accurate method was developed and validated for simultaneous analysis of perfluoroalkyl carboxylic acids, sulfonic acids, and phosphonic acids (PFPAs) at low picograms per gram concentrations in a variety of food matrices. The method employed extraction with acetonitrile/water and cleanup on a mixed-mode co-polymeric sorbent (C8 + quaternary amine) using solid-phase extraction. High-performance liquid chromatographic separation was achieved on a C18 column using a mobile phase gradient containing 5 mM 1-methyl piperidine for optimal chromatographic resolution of PFPAs. A quadrupole time-of-flight high-resolution mass spectrometer operating in negative ion mode was used as detector. Method detection limits were in the range of 0.002 to 0.02 ng g(-1) for all analytes. Sample preparation (extraction and cleanup) recoveries at a spiking level of 0.1 ng g(-1) to a baby food composite were in the range of 59 to 98 %. A strong matrix effect was observed in the analysis of PFPAs in food extracts, which was tentatively assigned to sorption of PFPAs to the injection vial in the solvent-based calibration standard. The method was successfully applied to a range of different food matrices including duplicate diet samples, vegetables, meat, and fish samples. PMID:22955674

  14. Keto-Enol Tautomerizations Catalyzed by Water and Carboxylic Acids

    NASA Astrophysics Data System (ADS)

    da Silva, G.

    2009-12-01

    The ability of weakly-bound complexes to influence the kinetics of gas phase reactions, particularly in atmospheric chemistry, has long been speculated. This study uses quantum chemistry and statistical reaction rate theory to identify that bound water molecules can significantly reduce barriers to intramolecular hydrogen shift reactions, via a double-hydrogen-shift mechanism. The bound water molecule directly participates in the hydrogen shift reaction, exchanging a H atom with its counterpart. For the vinyl alcohol to acetaldehyde keto-enol tautomerization this mechanism cuts the reaction barrier approximately in half, reducing it by over 30 kcal mol-1. In contrast, while a non-participatory ‘bystander’ water molecule also reduces the hydrogen shift barrier, it is only by around 3 kcal/mol. When a carboxylic acid replaces water in the double-hydrogen-shift mechanism the barrier to keto-enol tautomerization is decimated, reduced to less than 6 kcal/mol (around 15 kcal/mol in the reverse direction). This results from reduced strain in the hydrogen shift transition state, and achieves enol lifetimes in the troposphere that become short on relevant timescales. Rapid enol to ketone isomerizations are currently required to explain the oxidation products of isoprene. The wider significance of rapid hydrogen shift reactions in atmospherically relevant molecules and radicals is also explored.

  15. Carboxylated and intact osteocalcin predict adiponectin concentration in hemodialyzed patients.

    PubMed

    Kuźniewski, Marek; Fedak, Danuta; Dumnicka, Paulina; Kapusta, Maria; Stępień, Ewa; Chowaniec, Eve; Krzanowska, Katarzyna; Krzanowski, Marcin; Chmiel, Grzegorz; Solnica, Bogdan; Sułowicz, Władysław

    2016-01-01

    Purpose Disrupted bone metabolism in patients with chronic kidney disease (CKD) is associated with elevated concentrations of biochemical bone markers. Recently, animal studies show the role of osteocalcin in energy metabolism, which is partially confirmed in humans. The aim of our study was to evaluate the relationships between serum concentrations of bone markers and indices of energy metabolism in CKD patients on maintenance hemodialysis; in particular, the relationship between various forms of osteocalcin and adiponectin. Patients and methods The cross-sectional study included 155 hemodialyzed stage 5 CKD patients. Serum concentrations of glucose, insulin, adiponectin, bone alkaline phosphatase (bALP), tartrate resistant acid phosphatase (TRAP), carboxylated (cOC), undercarboxylated (ucOC), and intact osteocalcin (OC) were determined. Results In total cohort, bALP, TRAP, cOC, and ucOC negatively correlated with BMI. All analyzed bone markers positively correlated with adiponectin in total cohort and in men. In multiple linear regression analysis including all patients, log(cOC) and log(intact OC) were the only bone markers that predicted log(adiponectin) (beta = 0.22; p = 0.016 and beta = 0.26; p = 0.010) independently of sex, dialysis vintage, CRP, insulin, iPTH concentrations, BMI, and age. Conclusions Our data confirm the positive association between cOC, intact OC, and adiponectin concentrations in CKD patients on maintenance hemodialysis. PMID:26822199

  16. A sensitive GC-EIMS method for simultaneous detection and quantification of JWH-018 and JWH-073 carboxylic acid and hydroxy metabolites in urine.

    PubMed

    Paul, Buddha D; Bosy, Thomas

    2015-04-01

    Synthetic cannabinoids, including JWH-018 and JWH-073, belong to a class of aminoalkylindoles (AAIs) that are smoked to produce an effect similar to tetrahydrocannabinol. Compounds in this class are often collectively known as 'Spice'. After ingestion, these compounds are extensively metabolized to their hydroxy and carboxylic acid metabolites. During forensic analysis, detection of these metabolites in urine is an indication of past exposure to the parent compounds. The analytical process involved hydrolysis of conjugated metabolites by glucuronidase, solvent extraction, derivatization by trifluoroacetic anhydride and hexafluoroisopropanol and GC-EIMS detection. Identification of the unknown was based on the criteria of GC retention time within ±2% and mass spectral ion ratio within ±20% of that of a standard. Deuterated internal standards of the carboxylic acid metabolites were used for quantification. The acid (JWH-018-COOH, JWH-073-COOH) and hydroxy (JWH-018-OH, JWH-073-OH) metabolites were linear over the concentration range of 0.1-10 and 0.2-10 ng/mL, respectively, with a correlation coefficient-square, R(2) > 0.999 (N = 5). Extraction recoveries of the metabolites were within 79 and 87%. The method was applied to 17 urine specimens collected as part of a military law enforcement investigation. Nine of the specimens tested positive for one or more of the metabolites. When the procedure was extended to screen other AAI compounds, two of the specimens were found to contain JWH-210, JWH-250 (JWH-302 or JWH-201) and JWH-250 (C4 isomers). The GC-EIMS method presented here was found to be suitable for detecting JWH-018 and JWH-073 metabolites and other AAI compounds in urine. PMID:25691387

  17. Chemistry of anti-AIDS and anticancer compounds

    SciTech Connect

    Yan, S.

    1992-01-01

    Several types of prodrugs of 2[prime], 3[prime]-dideoxynucleosides were designed and synthesized for evaluation as anti-AIDS drugs. These prodrugs include 5[prime]-O-acyl-2[prime], 3[prime]-dideoxynucleosides, in which the acyl groups are derived from both aromatic and aliphatic acids, [alpha]-amino acids, diacylglycerol carbonic acids, and diacylglycerol carbamic acids. By applying the pyridium-dihydropyridine redox delivery system to deliver 2[prime], 3[prime]-dideoxynucleosides to the central nervous system, 1,4-dihydropyridine-2[prime], 3[prime]-dideoxy-inosine and -adenosine compounds were synthesized. 5[prime]-Esters of 2[prime], 3[prime]-dideoxyinosine and 2[prime], 3[prime]-dideoxyadenosine were evaluated for their activity against the HIV-1 virus and for delivery to the central nervous system (CNS). The isomerization, hydrolysis, and oxidation of alkyl 1,4-dihydro-N-methylpyridine-3-carboxylates were studied by [sup 1]H and [sup 13]C NMR spectroscopy. Three intermediates, 1,4-dihydro-N-methylpyridine-3-carboxylic acid, alkyl (methyl or isopropyl) 1,6-dihydro-N-methylpyridine-3-carboxylate, and 1,6-dihydro-N-methylpyridine-3-carboxylic acid, were observed by [sup 1]H and [sup 13]C NMR spectroscopy, and their percentages in solution were determined. The structures of the 1,6-dihydropyridine intermediates were confirmed by comparison of the NMR spectra with those of an authentic model compound, methyl N-(4-chlorobenzyl)-1,6-dihydropyridine-3-carboxylate. The rate of hydrolysis of alkyl 1,4-dihydro-N-methylpyridine-3-carboxylates depends on the steric bulk of the O-alkyl group. A new type of 1,4-dihydropyridine drug delivery system with a three-carbon spacer group, 9-[2,3-di-O-acetyl-5-O-[3-(1,4-dihydro-N-methylpyridine-3-carboxamido)propionyl]-[beta]-D-arabinofuranosyl]adenine was designed, synthesized, and evaluated to deliver ara-ADA to the CNS for treatment of herpes encephalitis.

  18. Development of 2-(Substituted Benzylamino)-4-Methyl-1, 3-Thiazole-5-Carboxylic Acid Derivatives as Xanthine Oxidase Inhibitors and Free Radical Scavengers.

    PubMed

    Ali, Md Rahmat; Kumar, Suresh; Afzal, Obaid; Shalmali, Nishtha; Sharma, Manju; Bawa, Sandhya

    2016-04-01

    A series of 2-(substituted benzylamino)-4-methylthiazole-5-carboxylic acid was designed and synthesized as structural analogue of febuxostat. A methylene amine spacer was incorporated between the phenyl ring and thiazole ring in contrast to febuxostat in which the phenyl ring was directly linked with the thiazole moiety. The purpose of incorporating methylene amine was to provide a heteroatom which is expected to favour hydrogen bonding within the active site residues of the enzyme xanthine oxidase. The structure of all the compounds was established by the combined use of FT-IR, NMR and MS spectral data. All the compounds were screened in vitro for their ability to inhibit the enzyme xanthine oxidase as per the reported procedure along with DPPH free radical scavenging assay. Compounds 5j, 5k and 5l demonstrated satisfactory potent xanthine oxidase inhibitory activities with IC50 values, 3.6, 8.1 and 9.9 μm, respectively, whereas compounds 5k, 5n and 5p demonstrated moderate antioxidant activities having IC50 15.3, 17.6 and 19.6 μm, respectively, along with xanthine oxidase inhibitory activity. Compound 5k showed moderate xanthine oxidase inhibitory activity as compared with febuxostat along with antioxidant activity. All the compounds were also studied for their binding affinity in active site of enzyme (PDB ID-1N5X). PMID:26575582

  19. Enhancement of carboxylic acid degradation with sulfate radical generated by persulfate activation.

    PubMed

    Criquet, J; Nebout, P; Karpel Vel Leitner, N

    2010-01-01

    The aim of this work was to investigate the generation of sulfate radical for the removal of two carboxylic acids in aqueous solution: acetic and citric acids. From photochemical and radiolytic processes, kinetics of the degradation of these two carboxylic acids was studied as a function of the pH of the solution. It was shown that the maximum of acetic acid degradation occurred at pH 5. Above this pH, competitive reactions with the carbon mineralized inhibit the reaction of with the solute. In the case of citric acid, pH has only a little effect on the kinetic of citric acid degradation. The determination of mineralization yields shows several differences depending on carboxylic acids and pH. The degradation of both carboxylic acids was also studied in the radiolysis process whether with or without persulfate addition. A comparison of the processes of sulfate radical production is presented. PMID:20220244

  20. Preferential Interaction of Na+ over K+ to Carboxylate-functionalized Silver Nanoparticles

    EPA Science Inventory

    Elucidating mechanistic interactions between specific ions (Na+/ K+) and nanoparticle surfaces to alter particle stability in polar media has received little attention. We investigated relative preferential binding of Na+ and K+ to carboxylate-functionalized silver nanoparticles ...

  1. A microcalorimetric study of the sorption of copper(II) on KB-4 carboxyl cationite

    NASA Astrophysics Data System (ADS)

    Zauer, E. A.

    2008-08-01

    The thermokinetics of sorption of copper(II) ions on KB-4 carboxyl cationite in the salt and hydrogen forms was studied microcalorimetrically. The total heat effect of sorption and its dependence on the degree of ionite filling were determined.

  2. Measuring the concentration of carboxylic acid groups in torrefied spruce wood.

    PubMed

    Khazraie Shoulaifar, Tooran; Demartini, Nikolai; Ivaska, Ari; Fardim, Pedro; Hupa, Mikko

    2012-11-01

    Torrefaction is moderate thermal treatment (∼200-300°C) to improve the energy density, handling and storage properties of biomass fuels. In biomass, carboxylic sites are partially responsible for its hygroscopic. These sites are degraded to varying extents during torrefaction. In this paper, we apply methylene blue sorption and potentiometric titration to measure the concentration of carboxylic acid groups in spruce wood torrefied for 30min at temperatures between 180 and 300°C. The results from both methods were applicable and the values agreed well. A decrease in the equilibrium moisture content at different humidity was also measured for the torrefied wood samples, which is in good agreement with the decrease in carboxylic acid sites. Thus both methods offer a means of directly measuring the decomposition of carboxylic groups in biomass during torrefaction as a valuable parameter in evaluating the extent of torrefaction which provides new information to the chemical changes occurring during torrefaction. PMID:22940339

  3. ANALYSIS OF PERFLUORINATED CARBOXYLIC ACIDS IN SOILS II: OPTIMIZATION OF CHROMATOGRAPHY AND EXTRACTION

    EPA Science Inventory

    With the objective of detecting and quantitating low concentrations of perfluorinated carboxylic acids (PFCAs), including perfluorinated octanoic acid (PFOA), in soils, we compared the analytical suitability of liquid chromatography columns containing three different stationary p...

  4. The effect of carboxylic acid anions on the stability of framework mineral grains in petroleum reservoirs

    SciTech Connect

    MacGowan, D.B.; Surdam, R.C.; Ewing, R.E. )

    1990-06-01

    This paper presents experimental and empirical evidence to show that carboxylic acid anions (CAA's) are a major diagenetic control on first-cycle basins in Jurassic-to-Pleistocene reservoirs in the 80-to-120{degrees}C thermal window.

  5. Nicotine carboxylate insecticide emulsions: effect of the fatty acid chain length.

    PubMed

    Casanova, Herley; Araque, Pedronel; Ortiz, Carlos

    2005-12-28

    The effect of fatty acid chain length on nicotine carboxylate insecticide emulsions has been studied in terms of particle size, interfacial tension, nicotine encapsulation on emulsion droplets, and bioactivity. The particle size of the nicotine emulsion and the interfacial tension at the nicotine carboxylate oil phase (0.03 M)--Tween 80 aqueous phase (0.001 M) were affected in a similar way by the change in the fatty acid chain length, which was correlated by the packing conformation of Tween 80 and nicotine carboxylate molecules as obtained by AM1 theoretical calculations. The amount of encapsulated nicotine inside the nicotine carboxylate emulsion droplets influenced the insecticide bioactivity of nicotine; this relationship was explained in terms of the acid value of the different fatty acids used to prepare the nicotine formulation. PMID:16366679

  6. THE ANTIMUTAGENICITY OF 2-SUBSTITUTED SELENAZOLIDINE-4-(R)-CARBOXYLIC ACIDS.

    PubMed Central

    El-Sayed, Wael M.; Hussin, Warda A; Franklin, Michael R.

    2007-01-01

    Selenium can have cancer chemopreventive activity, although the mechanism of action has not been well defined. Selenazolidine-4-(R)-carboxylic acids (SCAs) were devised as prodrugs of L-selenocysteine, to provide selenium in a form and at a concentration commensurate with cancer chemopreventive activity. In the present study, a series of selenazolidines has been evaluated in the Salmonella typhimurium TA98 tester strain and all were found to possess antimutagenic activity. There was little difference between the seven selenazolidines in their effectiveness against either benzo[a]pyrene (B[a]P) or 3,6-bis(dimethylamino)acridine (acridine orange), agents which differ in their requirement for mammalian enzyme bioactivation for mutagenicity. Antimutagenic activity against acridine orange was dependent on selenazolidine concentration, and EC50 values were in the 5 –10 μM range. At 25 μM, the concentration tested in common for the two mutagens, the selenazolidines were more effective antimutagens against acridine orange than against B[a]P, with reductions in mutant frequency ranging from 54–71% for B[a]P and 79–93% for acridine orange. Efficacy against B[a]P was not enhanced when the concentration was increased to 50 μM. The similarity in efficacy among the selenazolidines against B[a]P mutagenicity, contrasted with inter-compound differences in their ability to inhibit S9 CYP1A activity. The CYP1A Ki values ranged from a low of 63 μM (2-[2'-hydroxyphenyl]SCA) to a high of 1.1 mM (2-cyclohexylSCA), but all were above the concentration required to inhibit mutagenicity by 50%. Thus, all the SCAs possess antimutagenic activity against both B[a]P and acridine orange, the efficacy varies little between the individual selenazolidines, and for B[a]P, the efficacy is not proportional to the inhibitory effect on the mutagen bioactivating enzyme. PMID:17166761

  7. Pyrroline-5-Carboxylate Reductase in Chlorella autotrophica and Chlorella saccharophila in Relation to Osmoregulation 1

    PubMed Central

    Laliberté, Gilles; Hellebust, Johan A.

    1989-01-01

    Pyrroline-5-carboxylate (P5C) reductase (EC 1.5.1.2), which catalyzes the reduction of P5C to proline, was partially purified from two Chlorella species; Chlorella autotrophica, a euryhaline marine alga that responds to increases in salinity by accumulating proline and ions, and Chlorella saccharophila, which does not accumulate proline for osmoregulation. From the elution profile of this enzyme from an anion exchange column in Tris-HCl buffer (pH 7.6), containing sorbitol and glycine betaine, it was shown that P5C reductase from C. autotrophica was a neutral protein whereas the enzyme from C. saccharophila was negatively charged. The kinetic mechanisms of the reductase was characteristic of a ping-pong mechanism with double competitive substrate inhibition. Both enzymes showed high specificity for NADH as cofactor. The affinities of the reductases for their substrates did not change when the cells were grown at different salinities. In both algae, the apparent Km values of the reductase for P5C and NADH were 0.17 and 0.10 millimolar, respectively. A fourfold increase in maximal velocity of the reductase was observed when C. autotrophica was transferred from 50 to 150% artificial sea water. Even though the reductase was inhibited by NaCl, KCl, and proline, it still showed appreciable activity in the presence of these compounds at molar concentrations. A possible role for the regulation of proline synthesis at the step catalyzed by P5C reductase is discussed in relation to the specificity of P5C reductase for NADH and its responses to salt treatments. PMID:16667157

  8. Copper-catalyzed intermolecular oxyamination of olefins using carboxylic acids and O-benzoylhydroxylamines

    PubMed Central

    Hemric, Brett N

    2016-01-01

    Summary This paper reports a novel approach for the direct and facile synthesis of 1,2-oxyamino moieties via an intermolecular copper-catalyzed oxyamination of olefins. This strategy utilizes O-benzoylhydroxylamines as an electrophilic amine source and carboxylic acids as a nucleophilic oxygen source to achieve a modular difunctionalization of olefins. The reaction proceeded in a regioselective manner with moderate to good yields, exhibiting a broad scope of carboxylic acid, amine, and olefin substrates. PMID:26877805

  9. Population pharmacokinetics of oseltamivir and oseltamivir carboxylate in obese and non‐obese volunteers

    PubMed Central

    Chairat, Kalayanee; Jittamala, Podjanee; Hanpithakpong, Warunee; Day, Nicholas P. J.; White, Nicholas J.; Pukrittayakamee, Sasithon

    2016-01-01

    Aims The aims of the present study were to compare the pharmacokinetics of oseltamivir and its active antiviral metabolite oseltamivir carboxylate in obese and non‐obese individuals and to determine the effect of obesity on the pharmacokinetic properties of oseltamivir and oseltamivir carboxylate. Methods The population pharmacokinetic properties of oseltamivir and oseltamivir carboxylate were evaluated in 12 obese [body mass index (BMI) ≥30 kg m−2) and 12 non‐obese (BMI <30 kg m−2) Thai adult volunteers receiving a standard dose of 75 mg and a double dose of 150 mg in a randomized sequence. Concentration–time data were collected and analysed using nonlinear mixed‐effects modelling. Results The pharmacokinetics of oseltamivir and oseltamivir carboxylate were described simultaneously by first‐order absorption, with a one‐compartment disposition model for oseltamivir, followed by a metabolism compartment and a one‐compartment disposition model for oseltamivir carboxylate. Creatinine clearance was a significant predictor of oseltamivir carboxylate clearance {3.84% increase for each 10 ml min−1 increase in creatinine clearance [95% confidence interval (CI) 0.178%, 8.02%]}. Obese individuals had an approximately 25% (95% CI 24%, 28%) higher oseltamivir clearance, 20% higher oseltamivir volume of distribution (95% CI 19%, 23%) and 10% higher oseltamivir carboxylate clearance (95% CI 9%, 11%) compared with non‐obese individuals. However, these altered pharmacokinetic properties were small and did not change the overall exposure to oseltamivir carboxylate. Conclusions The results confirmed that a dose adjustment for oseltamivir in obese individuals is not necessary on the basis of its pharmacokinetics. PMID:26810861

  10. Direct enantioselective conjugate addition of carboxylic acids with chiral lithium amides as traceless auxiliaries.

    PubMed

    Lu, Ping; Jackson, Jeffrey J; Eickhoff, John A; Zakarian, Armen

    2015-01-21

    Michael addition is a premier synthetic method for carbon-carbon and carbon-heteroatom bond formation. Using chiral dilithium amides as traceless auxiliaries, we report the direct enantioselective Michael addition of carboxylic acids. A free carboxyl group in the product provides versatility for further functionalization, and the chiral reagent can be readily recovered by extraction with aqueous acid. The method has been applied in the enantioselective total synthesis of the purported structure of pulveraven B. PMID:25562717

  11. Silver-Catalyzed Decarboxylative Allylation of Aliphatic Carboxylic Acids in Aqueous Solution.

    PubMed

    Cui, Lei; Chen, He; Liu, Chao; Li, Chaozhong

    2016-05-01

    Direct decarboxylative radical allylation of aliphatic carboxylic acids is described. With K2S2O8 as the oxidant and AgNO3 as the catalyst, the reactions of aliphatic carboxylic acids with allyl sulfones in aqueous CH3CN solution gave the corresponding alkenes in satisfactory yields under mild conditions. This site-specific allylation method is applicable to all primary, secondary, and tertiary alkyl acids and exhibits wide functional group compatibility. PMID:27065060

  12. Polymerization process for carboxyl containing polymers utilizing oil soluble ionic surface active agents

    SciTech Connect

    Uebele, C.E.; Ball, L.E.; Jorkasky, R.J. II; Wardlow, E. Jr.

    1987-09-08

    This patent describes a method for polymerizing olefinically unsaturated carboxylic acid monomers containing at least one activated carbon to carbon olefinic double bond and at least one carboxyl group. The monomers are polymerized in an organic media consisting essentially of organic liquids, in the presence of free radical forming catalysts and at least one oil soluble ionic surface active agent selected from the group consisting of: (a) anionic surface active agents; (b) cationic surface active agents; and (c) amphoteric surface active agents.

  13. Method for continuous production of aromatic carboxylic acid

    SciTech Connect

    Abrams, K.J.

    1988-12-20

    This patent describes a method for the continuous production of an aromatic carboxylic acid product in a pressurized oxidation reactor by liquid-phase, exothermic oxidation of an aromatic alkyl feed with an oxygen-containing gas, in the presence of an aromatic alkyl feed with an oxygen-containing gas, in the presence of an oxidation catalyst and in an aqueous monocarboxylic C/sub 2/ to C/sub 6/ aliphatic acid solvent medium, wherein the heat generated during the course of the oxidation is removed from the reactor by vaporization of a portion of the reaction medium and water, wherein the resulting vapors are condensed in part in a reflux loop externally of the oxidation reactor to produce a condensate and a gaseous phase, and wherein at least a portion of the condensate is returned to the oxidation reactor, the improvement comprising a method for controlling within desired limits the concentration of water in the oxidation reactor, which comprises: partitioning the vapors into a parallel condensate having a relatively lesser water-to-solvent weight ratio and a vapor phase having a relatively greater water-to-solvent weight ratio; returning the partial condensate directly to the oxidation reactor as a direct reflux stream; withdrawing the vapor phase from the reflux loop as a vapor stream; subjecting the withdrawn vapor stream to heat exchange while decreasing the vapor stream pressure to less than the oxidation reactor pressure to thereby produce an aqueous aliphatic acid stream having a water-to-solvent weight ratio greater than that of the direct reflux stream.

  14. Reductive carboxylation supports redox homeostasis during anchorage-independent growth.

    PubMed

    Jiang, Lei; Shestov, Alexander A; Swain, Pamela; Yang, Chendong; Parker, Seth J; Wang, Qiong A; Terada, Lance S; Adams, Nicholas D; McCabe, Michael T; Pietrak, Beth; Schmidt, Stan; Metallo, Christian M; Dranka, Brian P; Schwartz, Benjamin; DeBerardinis, Ralph J

    2016-04-14

    Cells receive growth and survival stimuli through their attachment to an extracellular matrix (ECM). Overcoming the addiction to ECM-induced signals is required for anchorage-independent growth, a property of most malignant cells. Detachment from ECM is associated with enhanced production of reactive oxygen species (ROS) owing to altered glucose metabolism. Here we identify an unconventional pathway that supports redox homeostasis and growth during adaptation to anchorage independence. We observed that detachment from monolayer culture and growth as anchorage-independent tumour spheroids was accompanied by changes in both glucose and glutamine metabolism. Specifically, oxidation of both nutrients was suppressed in spheroids, whereas reductive formation of citrate from glutamine was enhanced. Reductive glutamine metabolism was highly dependent on cytosolic isocitrate dehydrogenase-1 (IDH1), because the activity was suppressed in cells homozygous null for IDH1 or treated with an IDH1 inhibitor. This activity occurred in absence of hypoxia, a well-known inducer of reductive metabolism. Rather, IDH1 mitigated mitochondrial ROS in spheroids, and suppressing IDH1 reduced spheroid growth through a mechanism requiring mitochondrial ROS. Isotope tracing revealed that in spheroids, isocitrate/citrate produced reductively in the cytosol could enter the mitochondria and participate in oxidative metabolism, including oxidation by IDH2. This generates NADPH in the mitochondria, enabling cells to mitigate mitochondrial ROS and maximize growth. Neither IDH1 nor IDH2 was necessary for monolayer growth, but deleting either one enhanced mitochondrial ROS and reduced spheroid size, as did deletion of the mitochondrial citrate transporter protein. Together, the data indicate that adaptation to anchorage independence requires a fundamental change in citrate metabolism, initiated by IDH1-dependent reductive carboxylation and culminating in suppression of mitochondrial ROS. PMID:27049945

  15. Reductive carboxylation supports redox homeostasis during anchorage-independent growth

    PubMed Central

    Jiang, Lei; Shestov, Alexander A.; Swain, Pamela; Yang, Chendong; Parker, Seth J.; Wang, Qiong A.; Terada, Lance S.; Adams, Nicholas D.; McCabe, Michael T.; Pietrak, Beth; Schmidt, Stan; Metallo, Christian M.; Dranka, Brian P.; Schwartz, Benjamin; DeBerardinis, Ralph J.

    2016-01-01

    Epithelial cells receive growth and survival stimuli through their attachment to an extracellular matrix (ECM)1. Overcoming the addiction to ECM-induced signals is required for anchorage-independent growth, a property of most malignant cells2. Detachment from ECM is associated with enhanced reactive oxygen species (ROS) due to altered glucose metabolism2. Here we identify an unconventional pathway that supports redox homeostasis and growth during adaptation to anchorage independence. We observed that detachment from monolayer culture and growth as anchorage-independent tumor spheroids was accompanied by changes in both glucose and glutamine metabolism. Specifically, oxidation of both nutrients was suppressed in spheroids, whereas reductive formation of citrate from glutamine was enhanced. Reductive glutamine metabolism was highly dependent on cytosolic isocitrate dehydrogenase-1 (IDH1), because the activity was suppressed in cells homozygous null for IDH1 or treated with an IDH1 inhibitor. This activity occurred in absence of hypoxia, a well-known inducer of reductive metabolism. Rather, IDH1 mitigated mitochondrial ROS in spheroids, and suppressing IDH1 reduced spheroid growth through a mechanism requiring mitochondrial ROS. Isotope tracing revealed that in spheroids, isocitrate/citrate produced reductively in the cytosol could enter the mitochondria and participate in oxidative metabolism, including oxidation by IDH2. This generates NADPH in the mitochondria, enabling cells to mitigate mitochondrial ROS and maximize growth. Neither IDH1 nor IDH2 was necessary for monolayer growth, but deleting either one enhanced mitochondrial ROS and reduced spheroid size, as did deletion of the mitochondrial citrate transporter protein. Together, the data indicate that adaptation to anchorage independence requires a fundamental change in citrate metabolism, initiated by IDH1-dependent reductive carboxylation and culminating in suppression of mitochondrial ROS. PMID:27049945

  16. Evaluation of Substrate and Inhibitor Binding to Yeast and Human Isoprenylcysteine Carboxyl Methyltransferases (Icmts) using Biotinylated Benzophenone-containing Photoaffinity Probes

    PubMed Central

    Hahne, Kalub; Vervacke, Jeffery; Shrestha, Liza; Donelson, James L.; Gibbs, Richard A.; Distefano, Mark D.; Hrycyna, Christine A.

    2013-01-01

    Isoprenylcysteine carboxyl methyltransferases (Icmts) are a class of integral membrane protein methyltransferases localized to the endoplasmic reticulum (ER) membrane in eukaryotes. The Icmts from human (hIcmt) and S. cerevisae (Ste14p) catalyze the α-carboxyl methyl esterification step in the post-translational processing of CaaX proteins, including the yeast a-factor mating pheromones and both human and yeast Ras proteins. Herein, we evaluated synthetic analogs of two well-characterized Icmt substrates, N-acetyl-S-farnesyl-L-cysteine (AFC) and the yeast a-factor peptide mating pheromone, that contain photoactive benzophenone moieties in either the lipid or peptide portion of the molecule. The AFC based-compounds were substrates for both hIcmt and Ste14p, whereas the a-factor analogs were only substrates for Ste14p. However, the a-factor analogs were found to be micromolar inhibitors of hIcmt. Together, these data suggest that the Icmt substrate binding site is dependent upon features in both the isoprenyl moiety and upstream amino acid composition and that hIcmt and Ste14p have overlapping, yet distinct, substrate specificities. Photocrosslinking and neutravidin-agarose capture experiments with these analogs revealed that both hIcmt and Ste14p were specifically photolabeled to varying degrees with all of the compounds tested. These data suggest that these analogs will be useful for the future identification of the Icmt substrate binding sites. PMID:22634004

  17. Crystal structure of poly[bis-(ammonium) [bis-(μ4-benzene-1,3,5-tri-carboxyl-ato)dizincate] 1-methyl-pyrrolidin-2-one disolvate].

    PubMed

    Ordonez, Carlos; Fonari, Marina S; Wei, Qiang; Timofeeva, Tatiana V

    2016-05-01

    The title three-dimensional metal-organic framework (MOF) compound, {(NH4)2[Zn2(C9H3O6)2]·2C5H9NO} n , features an anionic framework constructed from Zn(2+) cations and benzene-1,3,5-tri-carboxyl-ate (BTC) organic anions. Charge balance is achieved by outer sphere ammonium cations formed by degradation of di-n-butyl-amine in the solvothermal synthesis of the compound. Binuclear {Zn2(COO)2} entities act as the framework's secondary building units. Each Zn(II) atom has a tetrahedral coordination environment with an O4 set of donor atoms. The three-dimensional framework adopts a rutile-type topology and channels are filled in an alternating fashion with ordered and disordered 1-methyl-pyrrolidin-2-one solvent mol-ecules and ammonium cations. The latter are held in the channels via four N-H⋯O hydrogen bonds, including three with the benzene-1,3,5-tri-carboxyl-ate ligands of the anionic framework and one with a 1-methyl-pyrrolidin-2-one solvent mol-ecule. PMID:27308037

  18. Synthesis, spectroscopic characterization and crystal structure of 5-bromo-1-(2-cyano-pyridin-4-yl)-1 H-indazole-3-carboxylic acid diethylamide

    NASA Astrophysics Data System (ADS)

    Anuradha, G.; Vasuki, G.; Surendrareddy, G.; Veerareddy, A.; Dubey, P. K.

    2014-07-01

    The title compound 5-bromo-1-(2-cyano-pyridin-4-yl)-1 H-indazole-3-carboxylic acid diethylamide, C18H16BrN5O, is prepared from 5-bromoindazole-3-carboxylic acid methylester. N 1-arylation is carried out with 4-chloro-2-cyanopyridine and the resulting product is converted to diethylamide by reacting with thionyl chloride and diethylamine. The structure is identified from its FT-IR, 1H NMR, 13C NMR spectroscopy, elemental analysis data and unambiguously confirmed by single crystal X-ray diffraction studies. There are two symmetry independent molecules in the asymmetric unit with no significant differences in bond lengths and angles. The title compound crystallizes in the triclinic system, space group , with a = 11.2330(2); b = 11.6130(2); c = 15.4710(3) Å, α = 92.515(1)°; β = 109.956(1)°; γ = 107.199(1)°; V = 1788.45(6)Å3 and z = 4. An intramolecular C-H…N hydrogen bond forms an S(6) ring motif in one of the unique molecules. In the crystal, two molecules are linked about a center of inversion by C-H…O hydrogen bonded dimers generating an R {2/2}(16) ring motif. The crystal packing is stabilized by C-H…N, C-H…O hydrogen bonds and π…π stacking interactions.

  19. Further studies on ethyl 5-hydroxy-indole-3-carboxylate scaffold: design, synthesis and evaluation of 2-phenylthiomethyl-indole derivatives as efficient inhibitors of human 5-lipoxygenase.

    PubMed

    Peduto, Antonella; Bruno, Ferdinando; Dehm, Friedrike; Krauth, Verena; de Caprariis, Paolo; Weinigel, Christina; Barz, Dagmar; Massa, Antonio; De Rosa, Mario; Werz, Oliver; Filosa, Rosanna

    2014-06-23

    5-Lipoxygenase (5-LO), an enzyme that catalyzes the initial steps in the biosynthesis of pro-inflammatory leukotrienes, is an attractive drug target for the pharmacotherapy of inflammatory and allergic diseases. Here, we present the design, synthesis and biological evaluation of novel series of ethyl 5-hydroxyindole-3-carboxylate derivatives that efficiently inhibit human 5-LO. SAR analysis revealed that the potency of compounds is closely related to the positioning of the substituents at the phenylthiomethyl ring. The introduction of methyl or chlorine groups in ortho- and ortho/para-position of thiophenol represent the most favorable modifications. Among all tested compounds, ethyl 5-hydroxy-2-(mesitylthiomethyl)-1-methyl-1H-indole-3-carboxylate (19) is the most potent derivative which blocks 5-LO activity in cell-free assays with IC50 = 0.7 μM, and suppressed 5-LO product synthesis in polymorphonuclear leukocytes with IC50 = 0.23 μM. PMID:24871899

  20. Conformational Changes in Thiazole-2-carboxylic Acid Selectively Induced by Excitation with Narrowband Near-IR and UV Light.

    PubMed

    Halasa, Anna; Reva, Igor; Lapinski, Leszek; Nowak, Maciej J; Fausto, Rui

    2016-04-01

    Conformers and photoinduced conformational transformations were studied for monomers of thiazole-2-carboxylic acid (TCA). The matrix-isolation technique and excitations with narrowband near-IR and UV light, tuned in an optical parametric oscillator, were used for this purpose. Form I, with the carboxylic moiety in the trans orientation and with the hydrogen atom of the OH group directed toward the nitrogen atom of the ring, was the most abundant in low-temperature argon or nitrogen matrixes. Conformer II, differing from I by 180° rotation of the OH group around the C-O bond, was also trapped in the matrixes, but in much smaller amount. The abundance of form II was experimentally determined as ∼6% of the total amount of TCA molecules. Selective excitation of I with narrowband near-IR laser light resulted in I → II transformation. This near-IR-induced conformational change was photoreversible: form II converted back to I upon selective excitation of II with near-IR light of different wavelength. Conformational conversions of I into II, or vice versa, were also induced in TCA monomers by narrowband UV excitations at 300 nm (for I → II transformation) and at 305 nm (for II → I transformation). A spontaneous conversion of photogenerated II into the most stable form I was observed for the compound trapped in the matrix at 15 K and kept in the dark. This process was very slow; the estimated half-life time of conformer II was longer than 50 h. Finally, TCA was shown to thermally decompose at room temperature, yielding CO2 and thiazole. PMID:26986193

  1. Design, synthesis, in silico and in vitro studies of novel 4-methylthiazole-5-carboxylic acid derivatives as potent anti-cancer agents.

    PubMed

    Kilaru, Ravendra Babu; Valasani, Koteswara Rao; Yellapu, Nanda Kumar; Osuru, Hari Prasad; Kuruva, Chandra Sekhar; Matcha, Bhaskar; Chamarthi, Naga Raju

    2014-09-15

    Since inhibitors of mucin onco proteins are potential targets for breast cancer therapy, a series of novel 4-methylthiazole-5-carboxylic acid (1) derivatives 3a-k were synthesized by the reaction of 1 with SOCl2 followed by different bases/alcohols in the presence of triethylamine. Once synthesized and characterized, their binding modes with MUC1 were studied by molecular docking analysis using Aruglab 4.0.1 and QSAR properties were determined using HyperChem. All synthesized compounds were screened for in vitro anti-breast cancer activity against MDA-MB-231 breast adenocarcinoma cell lines by Trypan-blue cell viability assay and MTT methods. Compounds 1, 3b, 3d, 3e, 3i and 3f showed good anti-breast cancer activity. Since 1 and 3d exhibited high potent activity against MDA-MB-231 cell lines, they show could be effective mucin onco protein inhibitors. PMID:25131536

  2. Biological evaluation of halogenated thiazolo[3,2-a]pyrimidin-3-one carboxylic acid derivatives targeting the YycG histidine kinase.

    PubMed

    Zhao, Dan; Chen, Chen; Liu, Huayong; Zheng, Likang; Tong, Yao; Qu, Di; Han, Shiqing

    2014-11-24

    With an intention to potent inhibitors of YycG histidine kinase, a series of halogenated thiazolo[3,2-a]pyrimidin-3-one carboxylic acid derivatives were synthesized and evaluated for their antibacterial, antibiofilm and hemolytic activities. The majority of the compounds showed good activity against Staphylococcus epidermidis and Staphylococcus aureus, with MIC values of 1.56-6.25 μM, simultaneously presented promising antiobifilm activity against S. epidermidis ATCC35984 at 50 μM. The test of inhibitory activity on YycG kinase suggested the antibacterial activities of these derivatives are based on inhibiting the enzyme activity of the YycG HK domain. The hemolytic activity test suggested these compounds exhibited in vitro antibacterial activity at non-hemolytic concentrations. PMID:25282671

  3. Anaerobic biodegradation of aromatic compounds.

    PubMed

    Jothimani, P; Kalaichelvan, G; Bhaskaran, A; Selvaseelan, D Augustine; Ramasamy, K

    2003-09-01

    . For complete degradation the side chains must be removed first and then the benzene ring is activated by carboxylation or hydroxylation or co-A thioester formation. In the next step the activated ring is converted to a form that can be collected in the central pool of metabolism. The third step is the channeling reaction in which the products of the catalysis are directed into central metabolite pool. The enzymes involved in these mechanisms are mostly benzyl co-A ligase, benzyl alcohol dehydrogenase. Other enzymes involved in this path are yet to be purified though many of the reactions products that have been theoretically postulated have been identified. This is mainly due to the instability of intermediate compounds as well as the association of the enzyme substrate is femoral and experimental conditions need to be sophisticated further for isolation of these enzymes. The first structural genes of benzoate and hydroxy benzoate ligases were isolated from Rhodopseudomonas palustris. This gene cluster of 30 kb size found in Rhodopseudomonas palustris coded for the Bad A protein. Similarly, some of the bph A,B,C and D cluster of genes coding for the degradation of pentachlorobenzenes were located in Pseudomonas pseudoalgaligenesKF 707. PMID:15242297

  4. Synthesis, crystal structure, computational study of 1-(6-chloro-pyridin-2-yl)-5-hydroxy-1H-pyrazole-3-carboxylic acid methyl ester and its 5-acetoxy analogs

    NASA Astrophysics Data System (ADS)

    Shen, Li-Qun; Huang, Su-Yu; Diao, Kai-Sheng; Lei, Fu-Hou

    2012-08-01

    Two new pyrazole derivatives of 1-(6-chloro-pyridin-2-yl)-5-hydroxy-1H-pyrazole-3-carboxylic acid methyl ester 1a and 5-acetoxy-1-(6-chloro-pyridin-2-yl)-1H-pyrazole-3-carboxylic acid methyl ester 2 were synthesized and characterized by 1H, 13C NMR, IR spectroscopies and HRMS analyses. The molecular structure of 1a and 2 were studied by X-ray diffraction and compared to density-functional-theory (DFT) calculations. The gauge-including atomic orbital (GIAO) method for calculating 1H and 13C NMR nuclear magnetic shielding tensors at the DFT method with 6-31+G* basis set were applied to the compounds 1a and 2. Additionally, thermodynamic properties of the cyclization of the compound 3 to these compounds (1a, 1b, 1c, 4) were investigated by theoretical calculations. These theoretical calculations was shown that the compound 1a was readily formed and was the most stable one. Tautomeric forms of the compound 1a were optimized at the same methods and basis set. The calculated relative Gibbs free energies of the tautomeric forms of 1a were used to estimate the equilibrium constants. It was shown that the 1a was the most stable than tautomer of 1b and 1c in the gas phase.

  5. Metabolic fate of the carboxyl-carbon of valine

    SciTech Connect

    Lathrop, K.A.; Bartlett, R.D.; Faulhaber, P.F.; Harper, P.V.

    1984-01-01

    Although several C-11-carboxyl-labeled amino acids show promise for clinical use, few detailed biokinetic studies have been reported. Such information is necessary for the calculation of comprehensive radiation absorbed doses and may reveal additional clinical uses. The authors have collected data in mice at intervals between 1 and 90 m after i.v. injection of D,L-, L-, or D-valine for 22 whole organs or tissue samples and for CO/sub 2/ and urinary excretion. The enantiomers were cleanly separated by HPLC, but studies with the D,L- mixture were also done as additional assurance of purity for the separation (i.e., (D+L)/2=D,L). Elimination of C-11 from L-valine is restricted to the approx. =25% of injected activity (IA) observed as exhaled CO/sub 2/, the production of which appears completed in approx. =15 m, the exhalation in approx. =100m. The remaining 75% IA is available for incorporation directly into proteins or into coenzyme-A after deamination to 2-oxoisovalerate. The approx. =25% IA from D-valine that appears to be retained in the body probably is not converted to L-valine since virtually no CO/sub 2/ is recovered. The pancreatic content of approx. =8% of retained activity (RA) for both L- and D- valine at 90 m suggests similar localization mechanisms for the activity remaining in the body after excretion is ended. A similar correspondence of RA is seen in most other organs, the notable exceptions being the approx. =2 to 3 times higher %RA in blood and muscle for D-valine and in small intestine for L-valine. Studies such as this offer the possibility for quantitation of isolated metabolic processes, in this case production of CO/sub 2/ from 2-oxoisovalerate formed by deamination, and for separating metabolized from non-metabolized localization of C-11 when the D-amino acid can be shown to remain undegraded.

  6. Low molecular weight carboxylic acids in oxidizing porphyry copper tailings.

    PubMed

    Dold, Bernhard; Blowes, David W; Dickhout, Ralph; Spangenberg, Jorge E; Pfeifer, Hans-Rudolf

    2005-04-15

    The distribution of low molecular weight carboxylic acids (LMWCA) was investigated in pore water profiles from two porphyry copper tailings impoundments in Chile (Piuquenes at La Andina and Cauquenes at El Teniente mine). The objectives of this study were (1) to determine the distribution of LMWCA, which are interpreted to be the metabolic byproducts of the autotroph microbial community in this low organic carbon system, and (2) to infer the potential role of these acids in cycling of Fe and other elements in the tailings impoundments. The speciation and mobility of iron, and potential for the release of H+ via hydrolysis of the ferric iron, are key factors in the formation of acid mine drainage in sulfidic mine wastes. In the low-pH oxidation zone of the Piuquenes tailings, Fe(III) is the dominant iron species and shows high mobility. LMWCA, which occur mainly between the oxidation front down to 300 cm below the tailings surface at both locations (e.g., max concentrations of 0.12 mmol/L formate, 0.17 mmol/L acetate, and 0.01 mmol/L pyruvate at Piuquenes and 0.14 mmol/L formate, 0.14 mmol/L acetate, and 0.006 mmol/L pyruvate at Cauquenes), are observed at the same location as high Fe concentrations (up to 71.2 mmol/L Fe(II) and 16.1 mmol/L Fe(III), respectively). In this zone, secondary Fe(III) hydroxides are depleted. Our data suggest that LMWCA may influence the mobility of iron in two ways. First, complexation of Fe(III), through formation of bidentate Fe(III)-LMWCA complexes (e.g., pyruvate, oxalate), may enhance the dissolution of Fe(III) (oxy)hydroxides or may prevent precipitation of Fe(III) (oxy)hydroxides. Soluble Fe(III) chelate complexes which may be mobilized downward and convert to Fe(II) by Fe(III) reducing bacteria. Second, monodentate LMWCA (e.g., acetate and formate) can be used by iron-reducing bacteria as electron donors (e.g., Acidophilum spp.), with ferric iron as the electron acceptor. These processes may, in part, explain the low abundances

  7. Interconversion of biologically important carboxylic acids by radiation

    NASA Technical Reports Server (NTRS)

    Negron-Mendoza, A.; Ponnamperuma, C.

    1978-01-01

    The interconversion of a group of biologically important polycarboxylic acids (acetic, fumaric, malic, malonic, succinic, citric, isocitric, tricarballylic) under gamma-ray or ultraviolet radiation was investigated. The formation of high molecular weight compounds was observed in all cases. Succinic acid was formed in almost all radiolysis experiments. Citric, malonic, and succinic acids appeared to be relatively insensitive to radiation. Interconversion of the polycarboxylic acids studied may have occurred under the effect of radiation in the prebiotic earth.

  8. Quenching of fluorescence of phenolic compounds and modified humic acids by cadmium ions.

    PubMed

    Tchaikovskaya, O N; Nechaev, L V; Yudina, N V; Mal'tseva, E V

    2016-08-01

    The interaction of a number of phenolic compounds, being 'model fragments' of humic acids, with cadmium ions was investigated. The fluorescence quenching method was used to determine the complexation constants of these compounds with cadmium ions. It was established that bonding of phenolic compounds by cadmium ions at рН 7 is weak and reaches a maximum value of 15% for interaction with resorcinol. It was demonstrated that modification of humic acids by the mechanoactivation method increases by three times bonding of cadmium ions, which is caused by strengthening the acid properties of carboxyl and hydroxyl groups at the aromatic ring. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26729402

  9. A staining protocol for identifying secondary compounds in Myrtaceae1

    PubMed Central

    Retamales, Hernan A.; Scharaschkin, Tanya

    2014-01-01

    • Premise of the study: Here we propose a staining protocol using toluidine blue (TBO) and ruthenium red to reliably identify secondary compounds in the leaves of some species of Myrtaceae. • Methods and Results: Leaves of 10 species representing 10 different genera of Myrtaceae were processed and stained using five different combinations of ruthenium red and TBO. Optimal staining conditions were determined as 1 min of ruthenium red (0.05% aqueous) and 45 s of TBO (0.1% aqueous). Secondary compounds clearly identified under this treatment include mucilage in the mesophyll, polyphenols in the cuticle, lignin in fibers and xylem, tannins and carboxylated polysaccharides in the epidermis, and pectic substances in the primary cell walls. • Conclusions: Potential applications of this protocol include systematic, phytochemical, and ecological investigations in Myrtaceae. It might be applicable to other plant families rich in secondary compounds and could be used as a preliminary screening method for extraction of these elements. PMID:25309840

  10. Pharmacokinetics, tissue distribution, and the lactone/carboxylate equilibrium of hydroxycamptothecin delivered via aerosol in mice.

    PubMed

    Hu, Wei; Zhang, Chao; Hu, Wenjin; Fang, Yun; Hou, Wenjie

    2012-10-01

    Aerosol delivery is a route which is advantageous to the therapy of pulmonary diseases, such as lung cancer. The pharmacokinetics and tissue distribution after aerosol delivery of carboxylate form of hydroxycamptothecin (C-HCPT) were investigated. The concentrations of the three different types (lactone, carboxylate and the total of both forms) of HCPT were measured by HPLC analysis. The initial experiment showed no evident difference between lactone and carboxylate in the lungs during the aerosol treatment, compared with the HCPT content in plasma. The AUC(inf) value of lactone in the lungs was higher than that of carboxylate, which was 138,176.00 min ng g⁻¹ and 128,460.00 min ng g⁻¹, respectively. Meanwhile, AUC(inf) in the plasma during the entire treatment indicated that the lactone content was always at a lower level, and the carboxylate form tended to predominate, as shown by the lactone/carboxylate (L/C) equilibrium. The tissue distribution results showed that the lactone proportion in the liver increased up to the maximum value of 69.69% after aerosol administration, whereas the mean L/C equilibrium index for the liver was 2.07±1.06, and the C(max) and AUC(0-∞) values of the total HCPT were highest in the tissues. Based on these results we speculated that the initial wholly carboxylate form of the HCPT atomized liquid did not influence the transformation to lactone form. Moreover, the deposition of the total HCPT and lactone was higher in the lungs and other tissues than in the plasma after the aerosol treatment. This study will be beneficial to the therapy of pulmonary carcinoma. PMID:22858157

  11. Density Functional Theory Study on the Interactions of Metal Ions with Long Chain Deprotonated Carboxylic Acids.

    PubMed

    Mehandzhiyski, Aleksandar Y; Riccardi, Enrico; van Erp, Titus S; Koch, Henrik; Åstrand, Per-Olof; Trinh, Thuat T; Grimes, Brian A

    2015-10-01

    In this work, interactions between carboxylate ions and calcium or sodium ions are investigated via density functional theory (DFT). Despite the ubiquitous presence of these interactions in natural and industrial chemical processes, few DFT studies on these systems exist in the literature. Special focus has been placed on determining the influence of the multibody interactions (with up to 4 carboxylates and one metal ion) on an effective pair-interaction potential, such as those used in molecular mechanics (MM). Specifically, DFT calculations are employed to quantify an effective pair-potential that implicitly includes multibody interactions to construct potential energy curves for carboxylate-metal ion pairs. The DFT calculated potential curves are compared to a widely used molecular mechanics force field (OPLS-AA). The calculations indicate that multibody effects do influence the energetic behavior of these ionic pairs and the extent of this influence is determined by a balance between (a) charge transfer from the carboxylate to the metal ions which stabilizes the complex and (b) repulsion between carboxylates, which destabilizes the complex. Additionally, the potential curves of the complexes with 1 and 2 carboxylates and one counterion have been examined to higher separation distance (20 Å) by the use of relaxed scan optimization and constrained density functional theory (CDFT). The results from the relaxed scan optimization indicate that near the equilibrium distance, the charge transfer between the metal ion and the deprotonated carboxylic acid group is significant and leads to non-negligible differences between the DFT and MM potential curves, especially for calcium. However, at longer separation distances the MM calculated interaction potential functions converge to those calculated with CDFT, effectively indicating the approximate domain of the separation distance coordinate where charge transfer between the ions is occurring. PMID:26331433

  12. Modeling the antisymmetric and symmetric stretching vibrational modes of aqueous carboxylate anions.

    PubMed

    Sutton, Catherine C R; Franks, George V; da Silva, Gabriel

    2015-01-01

    The infrared spectra of six aqueous carboxylate anions have been calculated at the M05-2X/cc-pVTZ level of theory with the SMD solvent model, and validated against experimental data from the literature over the region of 1700 cm(-1) to 1250 cm(-1); this region corresponds to the stretching modes of the carboxylate group, and is often interrogated when probing bonding of carboxylates to other species and surfaces. The anions studied here were formate, acetate, oxalate, succinate, glutarate and citrate. For the lowest energy conformer of each anion, the carboxylate moiety antisymmetric stretching peak was predicted with a mean signed error of only 4 cm(-1) using the SMD solvent model, while the symmetric peak was slightly overestimated. Performing calculations in vacuum and scaling was found to generally over-predict the antisymmetric vibrational frequencies and under predict the symmetric peak. Different conformers of the same anion were found to have only slightly different spectra in the studied region and the inclusion of explicit water molecules was not found to significantly change the calculated spectra when the implicit solvent model is used. Overall, the use of density functional theory in conjunction with an implicit solvent model was found to result in infra-red spectra that are the best reproduction of the features found experimentally for the aqueous carboxylate ions in the important 1700 cm(-1) to 1250 cm(-1) region. The development of validated model chemistries for simulating the stretching modes of aqueous carboxylate ions will be valuable for future studies that investigate how carboxylate anions complex with multivalent metal cations and related species in solution. PMID:25048288

  13. Sorption of carboxylic acid from carboxylic salt solutions at pHs close to or above the pK[sub a] of the acid, with regeneration with an aqueous solution of ammonia or low-molecular-weight alkylamine

    DOEpatents

    King, C.J.; Tung, L.A.

    1992-07-21

    Carboxylic acids are sorbed from aqueous feedstocks at pHs close to or above the acids' pH[sub a] into a strongly basic organic liquid phase or onto a basic solid adsorbent or moderately basic ion exchange resin. The acids are freed from the sorbent phase by treating it with aqueous alkylamine or ammonia thus forming an alkylammonium or ammonium carboxylate which dewatered and decomposed to the desired carboxylic acid and the alkylamine or ammonia. 8 figs.

  14. Compounding in Ukraine.

    PubMed

    Zdoryk, Oleksandr A; Georgiyants, Victoriya A; Gryzodub, Oleksandr I; Schnatz, Rick

    2013-01-01

    Pharmaceutical compounding in modern Ukraine has a rich history and goes back to ancient times. Today in the Ukraine, there is a revival of compounding practice, the opening of private compounding pharmacies, updating of legislative framework and requirements of the State Pharmacopeia of Ukraine for compounding preparations, and the introduction of Good Pharmaceutical Practice. PMID:23696172

  15. Identification of Novel Perfluoroalkyl Ether Carboxylic Acids (PFECAs) and Sulfonic Acids (PFESAs) in Natural Waters Using Accurate Mass Time-of-Flight Mass Spectrometry (TOFMS).

    PubMed

    Strynar, Mark; Dagnino, Sonia; McMahen, Rebecca; Liang, Shuang; Lindstrom, Andrew; Andersen, Erik; McMillan, Larry; Thurman, Michael; Ferrer, Imma; Ball, Carol

    2015-10-01

    Recent scientific scrutiny and concerns over exposure, toxicity, and risk have led to international regulatory efforts resulting in the reduction or elimination of certain perfluorinated compounds from various products and waste streams. Some manufacturers have started producing shorter chain per- and polyfluorinated compounds to try to reduce the potential for bioaccumulation in humans and wildlife. Some of these new compounds contain central ether oxygens or other minor modifications of traditional perfluorinated structures. At present, there has been very limited information published on these "replacement chemistries" in the peer-reviewed literature. In this study we used a time-of-flight mass spectrometry detector (LC-ESI-TOFMS) to identify fluorinated compounds in natural waters collected from locations with historical perfluorinated compound contamination. Our workflow for discovery of chemicals included sequential sampling of surface water for identification of potential sources, nontargeted TOFMS analysis, molecular feature extraction (MFE) of samples, and evaluation of features unique to the sample with source inputs. Specifically, compounds were tentatively identified by (1) accurate mass determination of parent and/or related adducts and fragments from in-source collision-induced dissociation (CID), (2) in-depth evaluation of in-source adducts formed during analysis, and (3) confirmation with authentic standards when available. We observed groups of compounds in homologous series that differed by multiples of CF2 (m/z 49.9968) or CF2O (m/z 65.9917). Compounds in each series were chromatographically separated and had comparable fragments and adducts produced during analysis. We detected 12 novel perfluoroalkyl ether carboxylic and sulfonic acids in surface water in North Carolina, USA using this approach. A key piece of evidence was the discovery of accurate mass in-source n-mer formation (H(+) and Na(+)) differing by m/z 21.9819, corresponding to the

  16. Metal-containing ligands for mixed-metal polymers: novel Cu(II)-Ag(I) mixed-metal coordination polymers generated from [Cu(2-methylpyrazine-5-carboxylate)2(H2O)].3H2O and silver(I) salts.

    PubMed

    Dong, Y B; Smith, M D; zur Loye, H C

    2000-05-01

    One Cu(II)-containing ligand and two Cu(II)-Ag(I) mixed-metal coordination polymers have been synthesized. [Cu(2-methylpyrazine-5-carboxylate)2(H2O)].3H2O (1) was obtained as a molecular complex with two uncoordinated nitrogen donors by the reaction of 2-methylpyrazine-5-carboxylate sodium with CuCl(2).2H2O in water. Compound 1 crystallized in the triclinic space group P1, with a = 10.498(2) A, b = 11.000(2) A, c = 8.1424(16) A, alpha = 98.33(3) degrees, beta = 101.83(3) degrees, gamma = 66.68(3) degrees, and Z = 2. Reactions of 1 with silver(I) salts have been studied. Two Cu(II)-Ag(I) mixed-metal coordination polymers, namely, Ag[Cu(2-methylpyrazine-5-carboxylate)2.(H2O)2](BF4) (2) and Ag[Cu(2-methylpyrazine-5-carboxylate)2.(H2O)2](NO3) (3), have been generated by treating 1 with AgBF4 and AgNO3, respectively. Compound 2 crystallized in the monoclinic space group C2/c, with a = 25.827(5) A, b = 9.6430(19) A, c = 7.4525(15) A, beta = 94.74(3) degrees, and Z = 4. Compound 3 also crystallized in the monoclinic space group C2/c, with a = 25.855(5) A, b = 9.782(2) A, c = 7.1201(14) A, beta = 96.90(3) degrees, and Z = 4. The main structural feature in both 2 and 3 is a zigzag Cu(II)-Ag(I) mixed-metal chain, in which the alternating Cu(II) and Ag(I) centers are linked by 2-methylpyrazine-5-carboxylate spacers. The effect of the nitrate counterion was illustrated by compound 3, in which a novel [Ag+...NO3-] coordination chain has been found which acts as the connector to cross-link the one-dimensional zigzag chains into a three-dimensional network. In addition, an identical interchain O-H...O hydrogen bonding system has been found in both 2 and 3 and has been shown to play a significant role in directing the alignment of the one-dimensional mixed-metal polymer chains in the crystalline state. The magnetic susceptibilities of 2 and 3 were measured and found to follow the Curie law (mu eff = 1.85 for 2 and 1.83 for 3). PMID:11428114

  17. Identification of hexanuclear Actinide(IV) carboxylates with Thorium, Uranium and Neptunium by EXAFS spectroscopy

    NASA Astrophysics Data System (ADS)

    Hennig, Christoph; Takao, Shinobu; Takao, Koichiro; Weiss, Stephan; Kraus, Werner; Emmerling, Franziska; Meyer, Michel; Scheinost, Andreas C.

    2013-04-01

    Hydrated actinide(IV) ions undergo hydrolysis and further polymerization and precipitation with increasing pH. The resulting amorphous and partly crystalline oxydydroxides AnOn(OH)4-2n·xH2O can usually be observed as colloids above the An(IV) solubility limit. The aging process of such colloids results in crystalline AnO2. The presence of carboxylates in the solution prevents the occurrence of such colloids by formation of polynuclear complexes through a competing reaction between hydrolysis and ligation. The majority of recently described carboxylates reveals a hexanuclear core of [An6(μ3-O)4(μ3-OH)4]12+ terminated by 12 carboxylate ligands. We found that the An(IV) carboxylate solution species remain often preserved in crystalline state. The An(IV) carboxylates show An-An distances which are ~ 0.03 Å shorter than the An-An distances in AnO2 like colloids. The difference in the distances could be used to identify such species in solution.

  18. Synthesis, spectroscopic characterization, biological screenings, DNA binding study and POM analyses of transition metal carboxylates

    NASA Astrophysics Data System (ADS)

    Uddin, Noor; Sirajuddin, Muhammad; Uddin, Nizam; Tariq, Muhammad; Ullah, Hameed; Ali, Saqib; Tirmizi, Syed Ahmed; Khan, Abdur Rehman

    2015-04-01

    This article contains the synthesis of a novel carboxylic acid derivative, its transition metal complexes and evaluation of biological applications. Six carboxylate complexes of transition metals, Zn(II) and Hg(II), have been successfully synthesized and characterized by FT-IR and NMR (1H, 13C). The ligand, HL, (4-[(2,6-Diethylphenyl)amino]-4-oxobutanoic acid) was also characterized by single crystal X-ray analysis. The complexation occurs via oxygen atoms of the carboxylate moiety. FT-IR date show the bidentate nature of the carboxylate moiety of the ligand as the Δν value in all complexes is less than that of the free ligand. The ligand and its complexes were screened for antifungal and antileishmanial activities. The results showed that the ligand and its complexes are active with few exceptions. UV-visible spectroscopy and viscometry results reveal that the ligand and its complexes interact with the DNA via intercalative mode of interaction. A new and efficient strategy to identify the pharmacophores and anti-pharmacophores sites in carboxylate derivatives for the antibacterial/antifungal activity using Petra, Osiris and Molinspiration (POM) analyses was also carried out.

  19. Improved antifouling properties of polyamide nanofiltration membranes by reducing the density of surface carboxyl groups.

    PubMed

    Mo, Yinghui; Tiraferri, Alberto; Yip, Ngai Yin; Adout, Atar; Huang, Xia; Elimelech, Menachem

    2012-12-18

    Carboxyls are inherent functional groups of thin-film composite polyamide nanofiltration (NF) membranes, which may play a role in membrane performance and fouling. Their surface presence is attributed to incomplete reaction of acyl chloride monomers during the membrane active layer synthesis by interfacial polymerization. In order to unravel the effect of carboxyl group density on organic fouling, NF membranes were fabricated by reacting piperazine (PIP) with either isophthaloyl chloride (IPC) or the more commonly used trimesoyl chloride (TMC). Fouling experiments were conducted with alginate as a model hydrophilic organic foulant in a solution, simulating the composition of municipal secondary effluent. Improved antifouling properties were observed for the IPC membrane, which exhibited lower flux decline (40%) and significantly greater fouling reversibility or cleaning efficiency (74%) than the TMC membrane (51% flux decline and 40% cleaning efficiency). Surface characterization revealed that there was a substantial difference in the density of surface carboxyl groups between the IPC and TMC membranes, while other surface properties were comparable. The role of carboxyl groups was elucidated by measurements of foulant-surface intermolecular forces by atomic force microscopy, which showed lower adhesion forces and rupture distances for the IPC membrane compared to TMC membranes in the presence of calcium ions in solution. Our results demonstrated that a decrease in surface carboxyl group density of polyamide membranes fabricated with IPC monomers can prevent calcium bridging with alginate and, thus, improve membrane antifouling properties. PMID:23205860

  20. Synthesis, spectroscopic characterization, biological screenings, DNA binding study and POM analyses of transition metal carboxylates.

    PubMed

    Uddin, Noor; Sirajuddin, Muhammad; Uddin, Nizam; Tariq, Muhammad; Ullah, Hameed; Ali, Saqib; Tirmizi, Syed Ahmed; Khan, Abdur Rehman

    2015-04-01

    This article contains the synthesis of a novel carboxylic acid derivative, its transition metal complexes and evaluation of biological applications. Six carboxylate complexes of transition metals, Zn(II) and Hg(II), have been successfully synthesized and characterized by FT-IR and NMR (1H, 13C). The ligand, HL, (4-[(2,6-Diethylphenyl)amino]-4-oxobutanoic acid) was also characterized by single crystal X-ray analysis. The complexation occurs via oxygen atoms of the carboxylate moiety. FT-IR date show the bidentate nature of the carboxylate moiety of the ligand as the Δν value in all complexes is less than that of the free ligand. The ligand and its complexes were screened for antifungal and antileishmanial activities. The results showed that the ligand and its complexes are active with few exceptions. UV-visible spectroscopy and viscometry results reveal that the ligand and its complexes interact with the DNA via intercalative mode of interaction. A new and efficient strategy to identify the pharmacophores and anti-pharmacophores sites in carboxylate derivatives for the antibacterial/antifungal activity using Petra, Osiris and Molinspiration (POM) analyses was also carried out. PMID:25646895

  1. Molecular and Enantiomeric Analysis of Organic Compounds in Carbonaceous Meteorites

    NASA Technical Reports Server (NTRS)

    Cooper, George

    2003-01-01

    Carbonaceous meteorites are relatively enriched in carbon. Much of this carbon is in the form of soluble organic compounds. The Murchison and Murray meteorites are the best-characterized carbonaceous meteorites with respect to organic chemistry. Their content of organic compounds has led to an initial understanding of early solar system organic chemistry as well as what compounds may have played a role in the origin of life (Cronin and Chang, 1993). Reported compounds include: amino acids, amides, carboxylic acids, sulfonic acids, and polyols. This talk will focus on the molecular and enantiomeric analysis of individual meteoritic compounds: polyol acids; and a newly identified class of meteorite compounds, keto acids, i.e., acetoacetic acid, levulinic acid, etc. Keto acids (including pyruvic) are critically important in all contemporary organisms. They are key intermediates in metabolism and processes such as the citric acid cycle. Using gas chromatography-mass spectrometry we identified individual meteoritic keto acids after derivatization to one or more of the following forms: isopropyl ester (ISP), trimethyIsiIy1 (TMS), tert-butyldimethylsilyl (BDMS). Ongoing analyses will determine if, in addition to certain amino acids from Murchison (Cronin and Pizzarello, 1997), other potentially important prebiotic compounds also contain enantiomeric excesses, i.e., excesses that could have contributed to the current homochirality of life.

  2. Hydrolysis of acyloxy nitroso compounds yields nitroxyl (HNO).

    PubMed

    Sha, Xin; Isbell, T Scott; Patel, Rakesh P; Day, Cynthia S; King, S Bruce

    2006-08-01

    Nitroxyl (HNO/NO(-)), the reduced form of nitric oxide, has gained attention based on its separate chemistry and biology from nitric oxide. The inherent reactivity of HNO requires new and mechanistically unique donors for the detailed study of HNO chemistry and biology. Oxidation of cyclohexanone oxime with lead tetraacetate yields 1-nitrosocyclohexyl acetate, whereas oxidation of oximes in the presence of excess carboxylic acid gives various acyloxy nitroso compounds. These bright blue compounds exist as monomers as indicated by their infrared, proton, and carbon NMR spectra, and X-ray crystallographic analysis reveals the nitroso groups possess a "nitroxyl-like" bent configuration. Hydrolysis of these compounds produces nitrous oxide, the dimerization and dehydration product of HNO, and provides evidence for the intermediacy of HNO. Both thiols and oxidative metal complexes inhibit nitrous oxide formation. Hydrolysis of these compounds in the presence of ferric heme complexes forms ferrous nitrosyl complexes providing further evidence for the intermediacy of HNO. Kinetic analysis shows that the rate of hydrolysis depends on pH and the structure of the acyl group of the acyloxy nitroso compound. These compounds relax pre-constricted rat aortic rings similar to known HNO donors. Together, these results identify acyloxy nitroso compounds as a new class of HNO donors. PMID:16866522

  3. Toward Functional Carboxylate-Bridged Diiron Protein Mimics: Achieving Structural Stability and Conformational Flexibility Using a Macrocylic Ligand Framework

    PubMed Central

    Do, Loi H.; Lippard, Stephen J.

    2011-01-01

    A dinucleating macrocycle, H2PIM, containing phenoxylimine metal-binding units has been prepared. Reaction of H2PIM with [Fe2(Mes)4] (Mes = 2,4,6-trimethylphenyl) and sterically hindered carboxylic acids, Ph3CCO2H or ArTolCO2H (2,6-bis(p-tolyl)benzoic acid), afforded complexes [Fe2(PIM)(Ph3CCO2)2] (1) and [Fe2(PIM)(ArTolCO2)2] (2), respectively. X-ray diffraction studies revealed that these diiron(II) complexes closely mimic the active site structures of the hydroxylase components of bacterial multi-component monooxygenases (BMMs), particularly the syn disposition of the nitrogen donor atoms and the bridging μ-η1η2 and μ-η1η1 modes of the carboxylate ligands at the diiron(II) centers. Cyclic voltammograms of 1 and 2 displayed quasi-reversible redox couples at +16 and +108 mV vs. ferrocene/ferrocenium, respectively. Treatment of 2 with silver perchlorate afforded a silver(I)/iron(III) heterodimetallic complex, [Fe2(μ-OH)2(ClO4)2(PIM)(ArTolCO2)Ag] (3), which was structurally and spectroscopically characterized. Complexes 1 and 2 both react rapidly with dioxygen. Oxygenation of 1 afforded a (μ-hydroxo)diiron(III) complex [Fe2(μ-OH)(PIM)(Ph3CCO2)3] (4), a hexa(μ-hydroxo)tetrairon(III) complex [Fe4(μ-OH)6(PIM)2(Ph3CCO2)2] (5), and an unidentified iron(III) species. Oxygenation of 2 exclusively formed di(carboxylato)diiron(III) compounds, a testimony to the role of the macrocylic ligand in preserving the dinuclear iron center under oxidizing conditions. X-ray crystallographic and 57Fe Mössbauer spectroscopic investigations indicated that 2 reacts with dioxygen to give a mixture of (μ-oxo)diiron(III) [Fe2(μ-O)(PIM)(ArTolCO2)2] (6) and di(μ-hydroxo)diiron(III) [Fe2(μ-OH)2(PIM)(ArTolCO2)2] (7) units in the same crystal lattice. Compounds 6 and 7 spontaneously convert to a tetrairon(III) complex, [Fe4(μ-OH)6(PIM)2(ArTolCO2)2] (8), when treated with excess H2O. PMID:21682286

  4. Carboxylic acids, sulfates, and organosulfates in processed continental organic aerosol over the southeast Pacific Ocean during VOCALS-REx 2008

    NASA Astrophysics Data System (ADS)

    Hawkins, L. N.; Russell, L. M.; Covert, D. S.; Quinn, P. K.; Bates, T. S.

    2010-07-01

    Submicron particles were collected on board the NOAA R/V Ronald H. Brown during the VAMOS Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx) in the southeast Pacific marine boundary layer in October and November 2008. The aerosol in this region was characterized by low numbers of particles (150-700 cm-3) that were dominated by sulfate ions at concentrations of 0.9 ± 0.7 μg m-3 and organic mass at 0.6 ± 0.4 μg m-3, with no measurable nitrate and low ammonium ion concentrations. Measurements of submicron organic aerosol functional groups and trace elements show that continental outflow of anthropogenic emissions is the dominant source of organic mass (OM) to the southeast Pacific with an additional, smaller contribution of organic mass from primary marine sources. This continental source is supported by a correlation between OM and radon. Saturated aliphatic C-CH (alkane) composed 41 ± 27% of OM. Carboxylic acid COOH (32 ± 23% of OM) was observed in single particles internally mixed with ketonic carbonyl, carbonate, and potassium. Organosulfate COSO3 (4 ± 8% of OM) was observed only during the periods of highest organic and sulfate concentrations and lowest ammonium concentrations, consistent with a sulfuric acid epoxide hydrolysis for proposed surrogate compounds (e.g., isoprene oxidation products) or reactive glyoxal uptake mechanisms from laboratory studies. This correlation suggests that in high-sulfate, low-ammonium conditions, the formation of organosulfate compounds in the atmosphere contributes a significant fraction of aerosol OM (up to 13% in continental air masses). Organic hydroxyl C-OH composed 20 ± 12% of OM and up to 50% of remote marine OM and was inversely correlated with radon indicating a marine source. A two-factor solution of positive matrix factorization (PMF) analysis resulted in one factor dominated by organic hydroxyl (>70% by mass) and one factor dominated by saturated aliphatic C-CH (alkane) and carboxylic acid

  5. Absence of Vitamin K-Dependent γ-Carboxylation in Human Periostin Extracted from Fibrotic Lung or Secreted from a Cell Line Engineered to Optimize γ-Carboxylation

    PubMed Central

    Annis, Douglas S.; Ma, Hanqing; Balas, Danika M.; Kumfer, Kraig T.; Sandbo, Nathan; Potts, Gregory K.; Coon, Joshua J.; Mosher, Deane F.

    2015-01-01

    Periostin (PN, gene name POSTN) is an extracellular matrix protein that is up-regulated in bronchial epithelial cells and lung fibroblasts by TH-2 cytokines. Its paralog, TGF-β-induced protein (βig-h3, gene name TGFBI), is also expressed in the lung and up-regulated in bronchial myofibroblasts by TGF-β. PN and βig-h3 contain fasciclin 1 modules that harbor putative recognition sequences for γ-glutamyl carboxylase and are annotated in UniProt as undergoing vitamin K-dependent γ-carboxylation of multiple glutamic acid residues. γ-carboxylation profoundly alters activities of other proteins subject to the modification, e.g., blood coagulation factors, and would be expected to alter the structure and function of PN and βig-h3. To analyze for the presence of γ-carboxylation, proteins extracted from fibrotic lung were reacted with monoclonal antibodies specific for PN, βig-h3, or modification with γ-carboxyglutamic acid (Gla). In Western blots of 1-dimensional gels, bands stained with anti-PN or -βig-h3 did not match those stained with anti-Gla. In 2-dimensional gels, anti-PN-positive spots had pIs of 7.0 to >8, as expected for the unmodified protein, and there was no overlap between anti-PN-positive and anti-Gla-positive spots. Recombinant PN and blood coagulation factor VII were produced in HEK293 cells that had been transfected with vitamin K 2, 3-epoxide reductase C1 to optimize γ-carboxylation. Recombinant PN secreted from these cells did not react with anti-Gla antibody and had pIs similar to that found in extracts of fibrotic lung whereas secreted factor VII reacted strongly with anti-Gla antibody. Over 67% coverage of recombinant PN was achieved by mass spectrometry, including peptides with 19 of the 24 glutamates considered targets of γ-carboxylation, but analysis revealed no modification. Over 86% sequence coverage and three modified glutamic acid residues were identified in recombinant fVII. These data indicate that PN and βig-h3 are not subject

  6. Novel Regenerated Solvent Extraction Processes for the Recovery of Carboxylic Acids or Ammonia from Aqueous Solutions Part I. Regeneration of Amine-Carboxylic Acid Extracts

    SciTech Connect

    Poole, L.J.; King, C.J.

    1990-03-01

    Two novel regenerated solvent extraction processes are examined. The first process has the potential to reduce the energy costs inherent in the recovery of low-volatility carboxylic acids from dilute aqueous solutions. The second process has the potential for reducing the energy costs required for separate recovery of ammonia and acid gases (e.g. CO{sub 2} and H{sub 2}S) from industrial sour waters. The recovery of carboxylic acids from dilute aqueous solution can be achieved by extraction with tertiary amines. An approach for regeneration and product recovery from such extracts is to back-extract the carboxylic acid with a water-soluble, volatile tertiary amine, such as trimethylamine. The resulting trimethylammonium carboxylate solution can be concentrated and thermally decomposed, yielding the product acid and the volatile amine for recycle. Experimental work was performed with lactic acid, succinic acid, and fumaric acid. Equilibrium data show near-stoichiometric recovery of the carboxylic acids from an organic solution of Alamine 336 into aqueous solutions of trimethylamine. For fumaric and succinic acids, partial evaporation of the aqueous back extract decomposes the carboxylate and yields the acid product in crystalline form. The decomposition of aqueous solutions of trimethylammonium lactates was not carried out to completion, due to the high water solubility of lactic acid and the tendency of the acid to self-associate. The separate recovery of ammonia and acid gases from sour waters can be achieved by combining steam-stripping of the acid gases with simultaneous removal of ammonia by extraction with a liquid cation exchanger. The use of di-2,4,4-trimethylpentyl phosphinic acid as the liquid cation exchanger is explored in this work. Batch extraction experiments were carried out to measure the equilibrium distribution ratio of ammonia between an aqueous buffer solution and an organic solution of the phosphinic acid (0.2N) in Norpar 12. The concentration

  7. Methyl 9-diethyl­amino-2,2-bis­(4-meth­oxy­phen­yl)-2H-benzo[h]chromene-5-carboxyl­ate

    PubMed Central

    Kim, Moon-Hwan; Park, Hee-Moon; Kim, Chong-Hyeak

    2011-01-01

    In the title compound, C31H29NO5, the methyl carboxyl­ate and dimethyl­amino groups on the naphtho­pyran group are almost coplanar with the naphtho­pyran ring system [r.m.s. deviations = 0.08 (2) and 0.161 (2) Å, respectively]. The dihedral angle between the methyl carboxyl­ate and dimethyl­amino groups is 4.9 (1)°. The pyran ring has an envelope conformation with the quaternary C atom out of plane by 0.4739 (13) Å. The meth­oxy­phenyl substituent forms a dihedral angle of 16.6 (1)° with the plane of the benzene ring, while the other meth­oxy­phenyl group is almost coplanar, making a dihedral angle of 1.4 (1)°. PMID:21754239

  8. ATR-FTIR spectroscopy detects alterations induced by organotin(IV) carboxylates in MCF-7 cells at sub-cytotoxic/-genotoxic concentrations

    PubMed Central

    Ahmad, Muhammad S; Mirza, Bushra; Hussain, Mukhtiar; Hanif, Muhammad; Ali, Saqib; Walsh, Michael J; Martin, Francis L

    2008-01-01

    The environmental impact of metal complexes such as organotin(IV) compounds is of increasing concern. Genotoxic effects of organotin(IV) compounds (0.01 μg/ml, 0.1 μg/ml or 1.0 μg/ml) were measured using the alkaline single-cell gel electrophoresis (comet) assay to measure DNA single-strand breaks (SSBs) and the cytokinesis-block micronucleus (CBMN) assay to determine micronucleus formation. Biochemical-cell signatures were also ascertained using attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy. In the comet assay, organotin(IV) carboxylates induced significantly-elevated levels of DNA SSBs. Elevated micronucleus-forming activities were also observed. Following interrogation using ATR-FTIR spectroscopy, infrared spectra in the biomolecular range (900 cm-1 – 1800 cm-1) derived from organotin-treated MCF-7 cells exhibited clear alterations in their biochemical-cell fingerprint compared to control-cell populations following exposures as low as 0.0001 μg/ml. Mono-, di- or tri-organotin(IV) carboxylates (0.1 μg/ml, 1.0 μg/ml or 10.0 μg/ml) were markedly cytotoxic as determined by the clonogenic assay following treatment of MCF-7 cells with ≥ 1.0 μg/ml. Our results demonstrate that ATR-FTIR spectroscopy can be applied to detect molecular alterations induced by organotin(IV) compounds at sub-cytotoxic and sub-genotoxic concentrations. This biophysical approach points to a novel means of assessing risk associated with environmental contaminants. PACS codes: 87.15.-v, 87.17.-d, 87.18.-h PMID:19351425

  9. Water-enhanced solubility of carboxylic acids in organic solvents and its applications to extraction processes

    SciTech Connect

    Starr, J.N.; King, C.J.

    1991-11-01

    The solubilities of carboxylic acids in certain organic solvents increase remarkably with an increasing amount of water in the organic phase. This phenomenon leads to a novel extract regeneration process in which the co-extracted water is selectively removed from an extract, and the carboxylic acid precipitates. This approach is potentially advantageous compared to other regeneration processes because it removes a minor component of the extract in order to achieve a large recovery of acid from the extract. Carboxylic acids of interest include adipic acid, fumaric acid, and succinic acid because of their low to moderate solubilities in organic solvents. Solvents were screened for an increase in acid solubility with increased water concentration in the organic phase. Most Lewis-base solvents were found to exhibit this increased solubility phenomena. Solvents that have a carbonyl functional group showed a very large increase in acid solubility. 71 refs., 52 figs., 38 tabs.

  10. Isotope-Encoded Carboxyl Group Footprinting for Mass Spectrometry-Based Protein Conformational Studies

    NASA Astrophysics Data System (ADS)

    Zhang, Hao; Liu, Haijun; Blankenship, Robert E.; Gross, Michael L.

    2016-01-01

    We report an isotope-encoding method coupled with carboxyl-group footprinting to monitor protein conformational changes. The carboxyl groups of aspartic/glutamic acids and of the C-terminus of proteins can serve as reporters for protein conformational changes when labeled with glycine ethyl ester (GEE) mediated by carbodiimide. In the new development, isotope-encoded "heavy" and "light" GEE are used to label separately the two states of the orange carotenoid protein (OCP) from cyanobacteria. Two samples are mixed (1:1 ratio) and analyzed by a single LC-MS/MS experiment. The differences in labeling extent between the two states are represented by the ratio of the "heavy" and "light" peptides, providing information about protein conformational changes. Combining isotope-encoded MS quantitative analysis and carboxyl-group footprinting reduces the time of MS analysis and improves the sensitivity of GEE and other footprinting.

  11. Beyond ketonization: selective conversion of carboxylic acids to olefins over balanced Lewis acid–base pairs

    SciTech Connect

    Baylon, Rebecca A. L.; Sun, Junming; Martin, Kevin J.; Venkitasubramanian, Padmesh; Wang, Yong

    2016-01-01

    Dwindling petroleum reserves combined with increased energy demand and political factors encouraging an increase in energy independence have led to a large amount of research on sustainable alternatives. To this end, biomass conversion has been recognized as themost readily viable technology to produce biofuel concerning our reliance on liquid fuels for transportation and has the advantage of being easily integrated into our heavy use of combustion engines. The interest in biomass conversion has also resulted in reduced costs and a greater abundance of bio-oil, a mixture of hundreds of oxygenates including alcohols, aldehydes, carboxylic acids, and ketones. However, the presence of carboxylic acids in bio-oil derived from lignocellulose pyrolysis leads to low pH, instability, and corrosiveness. In addition, carboxylic acids (i.e. acetic acid) can also be produced via fermentation of sugars. This can be accomplished by a variety of homoacetogenic microorganisms that can produce acetic acid with 100% carbon yield.

  12. Environmental effects and desorption characteristics on heavy metal removal using carboxylated alginic acid.

    PubMed

    Jeon, Choong; Je Yoo, Young; Hoell, Wolfgang H

    2005-01-01

    Effects of ionic strength and organic materials on copper ion uptake capacity using carboxylated alginic acid which showed very high metal ion uptake capacity were investigated. The ionic strength only had a slight effect on the decrease of copper ion uptake capacity regardless of NaCl concentration. And, the effect of organic materials such as NTA (nitrilotriaceticacid) and sodium hypophosphite on the copper ion uptake capacity was negligible. When the lead ion adsorbed on carboxylated alginic acid was desorbed by NTA, which showed high desorption efficiency, the best optimum concentration of NTA was about 0.01 M. Also desorption efficiency decreased, however, concentration factor increased as S/L ratio which is defined as the ratio of adding amount of adsorbed and volume of desorbing agent increased. In sequential adsorption and desorption cycles, the lead uptake capacity on carboxylated alginic acid was relatively maintained through cycles 1-5. PMID:15364075

  13. Deep eutectic solvents formed between choline chloride and carboxylic acids: versatile alternatives to ionic liquids.

    PubMed

    Abbott, Andrew P; Boothby, David; Capper, Glen; Davies, David L; Rasheed, Raymond K

    2004-07-28

    Deep Eutectic Solvents (DES) can be formed between a variety of quaternary ammonium salts and carboxylic acids. The physical properties are significantly affected by the structure of the carboxylic acid but the phase behavior of the mixtures can be simply modeled by taking account of the mole fraction of carboxylic acid in the mixture. The physical properties such as viscosity, conductivity, and surface tension of these DES are similar to ambient temperature ionic liquids and insight into the cause of these properties is gained using hole-theory. It is shown that the conductivity and viscosity of these liquids is controlled by ion mobility and the availability of voids of suitable dimensions, and this is consistent with the fluidity of other ionic liquids and molten salts. The DES are also shown to be good solvents for metal oxides, which could have potential application for metal extraction. PMID:15264850

  14. Continuous separation of serum proteins using a stirred cell charged with carboxylated and sulfonated microspheres.

    PubMed

    Lee, J H; Yoon, J Y; Kim, W S

    1998-01-01

    We contrived a new separation system using a stirred cell charged with uncoupled microsphere similar to the chromatographic separation. Microspheres, carboxylated PS/PMAA and sulfonated PS/PNaSS, were prepared by emulsifier-free emulsion polymerization. To complement the submicron size weakness and the absence of ligands, we employed the latex form, the dispersion of microsphere, and took advantage of interaction relationships between proteins and microspheres. Adsorption isotherm is contemplated to investigate continuous separation behaviours of serum proteins. Selectivity of separation is in the following order: PS/PNaSS-2.0 (high sulfonated) < PS/PNaSS-0.3 (low sulfonated) < PS/PMAA-0.5 (low carboxylated). Unlike previous works on batch separation, not only the adsorbed amount in equilibrium (Cm), but also adsorption coefficient (K), played an important role in continuous separation. Functional groups (carboxyl and sulfonate), induced from the co-monomer, also affected the adsorption behaviours. PMID:9861492

  15. Iron Catalysis for Room-Temperature Aerobic Oxidation of Alcohols to Carboxylic Acids.

    PubMed

    Jiang, Xingguo; Zhang, Jiasheng; Ma, Shengming

    2016-07-13

    Oxidation from alcohols to carboxylic acids, a class of essential chemicals in daily life, academic laboratories, and industry, is a fundamental reaction, usually using at least a stoichiometric amount of an expensive and toxic oxidant. Here, an efficient and practical sustainable oxidation technology of alcohols to carboxylic acids using pure O2 or even O2 in air as the oxidant has been developed: utilizing a catalytic amount each of Fe(NO3)3·9H2O/TEMPO/MCl, a series of carboxylic acids were obtained from alcohols (also aldehydes) in high yields at room temperature. A 55 g-scale reaction was demonstrated using air. As a synthetic application, the first total synthesis of a naturally occurring allene, i.e., phlomic acid, was accomplished. PMID:27304226

  16. Carboxylic acid production from brewer's spent grain via mixed culture fermentation.

    PubMed

    Liang, Shaobo; Wan, Caixia

    2015-04-01

    This study aimed at investigating carboxylic acid production from brewer's spent grain (BSG) via mixed culture fermentation. The results showed that the distribution of fermentation products was significantly affected by pH conditions and the addition of electron donors. Lactic acid was the dominant component under acidic and alkaline conditions while volatile fatty acids (VFAs) became dominant under the neutral condition. Furthermore, the neutral condition favored the chain elongation of carboxylic acids, especially with ethanol as the electron donor. Ethanol addition enhanced valeric acid and caproic acid production by 44% and 167%, respectively. Lactic acid addition also had positive effects on VFAs production under the neutral condition but limited to C2-C4 products. As a result, propionic acid and butyric acid production was increased by 109% and 152%, respectively. These findings provide substantial evidence for regulating carboxylic acid production during mixed culture fermentation of BSG by controlling pH and adding electron donors. PMID:25698409

  17. Carboxylic-Acid-passivated metal oxide nanocrystals: ligand exchange characteristics of a new binding motif.

    PubMed

    De Roo, Jonathan; Justo, Yolanda; De Keukeleere, Katrien; Van den Broeck, Freya; Martins, José C; Van Driessche, Isabel; Hens, Zeger

    2015-05-26

    Ligand exchange is central in the processing of inorganic nanocrystals (NCs) and requires understanding of surface chemistry. Studying sterically stabilized HfO2 and ZrO2 NCs using (1) H solution NMR and IR spectroscopy as well as elemental analysis, this paper demonstrates the reversible exchange of initial oleic acid ligands for octylamine and self-adsorption of oleic acid at NC surfaces. Both processes are incompatible with an X-type binding motif of carboxylic acids as reported for sulfide and selenide NCs. We argue that this behavior stems from the dissociative adsorption of carboxylic acids at the oxide surface. Both proton and carboxylate moieties must be regarded as X-type ligands yielding a combined X2 binding motif that allows for self-adsorption and exchange for L-type ligands. PMID:25866095

  18. Isotope-Encoded Carboxyl Group Footprinting for Mass Spectrometry-Based Protein Conformational Studies.

    PubMed

    Zhang, Hao; Liu, Haijun; Blankenship, Robert E; Gross, Michael L

    2016-01-01

    We report an isotope-encoding method coupled with carboxyl-group footprinting to monitor protein conformational changes. The carboxyl groups of aspartic/glutamic acids and of the C-terminus of proteins can serve as reporters for protein conformational changes when labeled with glycine ethyl ester (GEE) mediated by carbodiimide. In the new development, isotope-encoded "heavy" and "light" GEE are used to label separately the two states of the orange carotenoid protein (OCP) from cyanobacteria. Two samples are mixed (1:1 ratio) and analyzed by a single LC-MS/MS experiment. The differences in labeling extent between the two states are represented by the ratio of the "heavy" and "light" peptides, providing information about protein conformational changes. Combining isotope-encoded MS quantitative analysis and carboxyl-group footprinting reduces the time of MS analysis and improves the sensitivity of GEE and other footprinting. PMID:26384685

  19. Communication: Physical origins of ionization potential shifts in mixed carboxylic acids and water complexes

    NASA Astrophysics Data System (ADS)

    Gu, Quanli; Tang, Zhen; Su, Peifeng; Wu, Wei; Yang, Zhijun; Trindle, Carl O.; Knee, Joseph L.

    2016-08-01

    The ionization potential (IP) of the aromatic alpha hydroxy carboxylic acid, 9-hydroxy-9-fluorene carboxylic acid (9HFCA), is shifted by complexation with hydrogen bonding ligands such as water and formic acid. Generalized Kohn-Sham energy decomposition analysis decomposes the intermolecular binding energies into a frozen energy term, polarization, correlation, and/or dispersion energy terms, as well as terms of geometric relaxation and zero point energy. We observe that in each dimer the attractive polarization always increases upon ionization, enhancing binding in the cation and shifting the IP toward the red. For 9HFCA—H2O, a substantial decrease of the repulsive frozen energy in cation further shifts the IP toward red. For 9HFCA—HCOOH, the increase of the frozen energy actually occurs in the cation and shifts the IP toward blue. Consistent with the experimental measurements, our analysis provides new, non-intuitive perspectives on multiple hydrogen bonds interactions in carboxylic acids and water complexes.

  20. Features of the pp60v-src carboxyl terminus that are required for transformation.

    PubMed Central

    Yaciuk, P; Shalloway, D

    1986-01-01

    Analysis of the biological and biochemical activities of pp60recombinant-src proteins encoded by 12 carboxyl-terminal mutants showed that a wide family of alternate src carboxyl termini permit complete transforming and kinase activities. src proteins having carboxyl termini which are up to 10 amino acids longer than that of pp60c-src (17 amino acids longer than that of pp60v-src) still permit transformation. Transformation-positive mutations preserve leucine-516, a residue which is highly conserved in protein-tyrosine kinase sequences; removal causes in vivo protein instability. Successive deletion mutants show that this residue is at the boundary of a region required for kinase activity. pp60src which is truncated just outside this point still transforms cells and binds both pp50 and pp90 cellular proteins. Images PMID:3097514

  1. One-step hydrothermal synthesis of carboxyl-functionalized upconversion phosphors for bioapplications.

    PubMed

    Yang, Jianping; Shen, Dengke; Li, Xiaomin; Li, Wei; Fang, Yin; Wei, Yong; Yao, Chi; Tu, Bo; Zhang, Fan; Zhao, Dongyuan

    2012-10-22

    In this paper, we report a facile one-step hydrothermal method to synthesize phase-, size-, and shape-controlled carboxyl-functionalized rare-earth fluorescence upconversion phosphors by using a small-molecule binary acid, such as malonic acid, oxalic acid, succinic acid, or tartaric acid as capping agent. The crystals, from nano- to microstructures with diverse shapes that include nanospheres, microrods, hexagonal prisms, microtubes, microdisks, polygonal columns, and hexagonal tablets, can be obtained with different reaction times, reaction temperatures, molar ratios of capping agent to sodium hydroxide, and by varying the binary acids. Fourier transform infrared, thermogravimetric analysis, and upconversion luminescence spectra measurements indicate that the synthesized NaYF(4):Yb/Er products with hydrophilic carboxyl-functionalized surface offer efficient upconversion luminescent performance. Furthermore, the antibody/secondary antibody conjugation can be realized by the carboxyl-functionalized surfaces of the upconversion phosphors, thus indicating the potential bioapplications of these kinds of materials. PMID:22996059

  2. High-performance liquid chromatographic determination of methyl anthranilate, hydroxymethylfurfural and related compounds in honey.

    PubMed

    Nozal, M J; Bernal, J L; Toribio, L; Jiménez, J J; Martín, M T

    2001-05-11

    A high-performance liquid chromatographic method for determining 5-hydroxymethyl-2-furaldehyde (hydroxymethylfurfural), 2-furaldehyde (furfural), furan-2-carboxylic acid (2-furoic acid), furan-3-carboxylic acid (3-furoic acid), furan-3-carboxaldehyde (3-furaldehyde) and 2-aminobenzoic acid methyl ester (methyl anthranilate) in honey and honeydew samples is described. To prevent matrix interference and to isolate the compounds, a clean-up step which implies a solid-phase extraction on polymeric cartridges and an elution with 0.5 ml methanol is recommended. The compounds are separated on a reversed-phase column with a gradient of (A) 1% aqueous acetic acid-acetonitrile (97:3, v/v) and (B) acetonitrile-water (50:50, v/v), with UV detection at 250 nm. The method is applied to the analysis of samples from different botanical origin. PMID:11403496

  3. Application of FIGAERO (Filter Inlet for Gases and AEROsol) coupled to a high resolution time of flight chemical ionization mass spectrometer to field and chamber organic aerosol: Implications for carboxylic acid formation and gas-particle partitioning from monoterpene oxidation

    NASA Astrophysics Data System (ADS)

    Lopez-Hilfiker, F.; Mohr, C.; Ehn, M.; Rubach, F.; Mentel, T. F.; Kleist, E.; Wildt, J.; Thornton, J. A.

    2013-12-01

    We present measurements of a large suite of gas and particle phase carboxylic acid containing compounds made with a Filter Inlet for Gas and AEROsol (FIGAERO) coupled to a high resolution time of flight chemical ionization mass spectrometer (HR-ToF-CIMS) developed at the University of Washington. A prototype operated with acetate negative ion proton transfer chemistry was deployed on the Julich Plant Atmosphere Chamber to study a-pinene oxidation, and a modified version was deployed at the SMEAR II forest station in Hyytiälä, Finland and SOAS, in Brent Alabama. We focus here on results from JPAC and Hyytiälä, where we utilized the same ionization method most selective towards carboxylic acids. In all locations, 100's of organic acid compounds were observed in the gas and particles and many of the same composition acids detected in the gas-phase were detected in the particles upon temperature programmed thermal desorption. Particulate organics detected by FIGAERO are highly correlated with organic aerosol mass measured by an AMS, providing additional volatility and molecular level information about collected aerosol. The fraction of a given compound measured in the particle phase follows expected trends with elemental composition, but many compounds would not be well described by an absorptive partitioning model assuming unity activity coefficients. Moreover the detailed structure in the thermal desorption signals reveals a contribution from thermal decomposition of large molecular weight organics and or oligomers with implications for partitioning measurements and model validation

  4. Design and synthesis of human ABCB1 (P-glycoprotein) inhibitors by peptide coupling of diverse chemical scaffolds on carboxyl and amino termini of (S)-valine-derived thiazole amino acid.

    PubMed

    Singh, Satyakam; Prasad, Nagarajan Rajendra; Chufan, Eduardo E; Patel, Bhargav A; Wang, Yi-Jun; Chen, Zhe-Sheng; Ambudkar, Suresh V; Talele, Tanaji T

    2014-05-22

    P-glycoprotein (P-gp) serves as a therapeutic target for the development of multidrug resistance reversal agents. In this study, we synthesized 21 novel compounds by peptide coupling at corresponding carboxyl and amino termini of (S)-valine-based bis-thiazole and monothiazole derivatives with diverse chemical scaffolds. Using calcein-AM efflux assay, we identified compound 28 (IC50 = 1.0 μM) carrying 3,4,5-trimethoxybenzoyl and 2-aminobenzophenone groups, respectively, at the amino and carboxyl termini of the monothiazole zwitter-ion. Compound 28 inhibited the photolabeling of P-gp with [(125)I]-iodoarylazidoprazosin with IC50 = 0.75 μM and stimulated the basal ATP hydrolysis of P-gp in a concentration-dependent manner (EC50 ATPase = 0.027 μM). Compound 28 at 3 μM reduced resistance in cytotoxicity assay to paclitaxel in P-gp-expressing SW620/Ad300 and HEK/ABCB1 cell lines. Biochemical and docking studies showed site-1 to be the preferable binding site for 28 within the drug-binding pocket of human P-gp. PMID:24773054

  5. Root carboxylate exudation capacity under phosphorus stress does not improve grain yield in green gram.

    PubMed

    Pandey, Renu; Meena, Surendra Kumar; Krishnapriya, Vengavasi; Ahmad, Altaf; Kishora, Naval

    2014-06-01

    Genetic variability in carboxylate exudation capacity along with improved root traits was a key mechanism for P-efficient green gram genotype to cope with P-stress but it did not increase grain yield. This study evaluates genotypic variability in green gram for total root carbon exudation under low phosphorus (P) using (14)C and its relationship with root exuded carboxylates, growth and yield potential in contrasting genotypes. Forty-four genotypes grown hydroponically with low (2 μM) and sufficient (100 μM) P concentrations were exposed to (14)CO2 to screen for total root carbon exudation. Contrasting genotypes were employed to study carboxylate exudation and their performance in soil at two P levels. Based on relative (14)C exudation and biomass, genotypes were categorized. Carboxylic acids were measured in exudates and root apices of contrasting genotypes belonging to efficient and inefficient categories. Oxalic and citric acids were released into the medium under low-P. PDM-139 (efficient) was highly efficient in carboxylate exudation as compared to ML-818 (inefficient). In low soil P, the reduction in biomass was higher in ML-818 as compared to PDM-139. Total leaf area and photosynthetic rate averaged for genotypes increased by 71 and 41 %, respectively, with P fertilization. Significantly, higher root surface area and volume were observed in PDM-139 under low soil P. Though the grain yield was higher in ML-818, the total plant biomass was significantly higher in PDM-139 indicating improved P uptake and its efficient translation into biomass. The higher carboxylate exudation capacity and improved root traits in the later genotype might be the possible adaptive mechanisms to cope with P-stress. However, it is not necessary that higher root exudation would result in higher grain yield. PMID:24493254

  6. Carboxylated N-glycans on RAGE promote S100A12 binding and signaling

    PubMed Central

    Srikrishna, Geetha; Nayak, Jonamani; Weigle, Bernd; Temme, Achim; Foell, Dirk; Hazelwood, Larnele; Olsson, Anna; Volkmann, Niels; Hanein, Dorit; Freeze, Hudson H.

    2010-01-01

    RAGE, the Receptor for Advanced Glycation End Products, is a signaling receptor protein of the immunoglobulin superfamily implicated in multiple pathologies. It binds a diverse repertoire of ligands, but the structural basis for the interaction of different ligands is not well understood. We earlier showed that carboxylated glycans on the V-domain of RAGE promote the binding of HMGB1 and S100A8/A9. Here we study the role of these glycans on the binding and intracellular signaling mediated by another RAGE ligand, S100A12. S100A12 binds carboxylated glycans, and a subpopulation of RAGE enriched for carboxylated glycans shows more than ten fold higher binding potential for S100A12 than total RAGE. When expressed in mammalian cells, RAGE is modified by complex glycans predominantly at the first glycosylation site (N25IT) that retains S100A12 binding. Glycosylation of RAGE and maximum binding sites for S100A12 on RAGE are also cell type dependent. Carboxylated glycan-enriched population of RAGE forms higher order multimeric complexes with S100A12, and this ability to multimerize is reduced upon deglycosylation or by using non-glycosylated sRAGE expressed in E.coli. mAbGB3.1, an antibody against carboxylated glycans, blocks S100A12 mediated NF-κB signaling in HeLa cells expressing full length RAGE. These results demonstrate that carboxylated N-glycans on RAGE enhance binding potential and promote receptor clustering and subsequent signaling events following oligomeric S100A12 binding. PMID:20512925

  7. Carboxylic and dicarboxylic acids extracted from crushed magnesium oxide single crystals

    NASA Technical Reports Server (NTRS)

    Freund, F.; Gupta, A. D.; Kumar, D.

    1999-01-01

    Carboxylic and dicarboxylic acids (glycolic, oxalic, malonic and succinic) have been extracted with tetrahydrofuran (THF) and H2O from large synthetic MgO crystals, crushed to a medium fine powder. The extracts were characterized by infrared spectroscopy and 1H-NMR. The THF extracts were derivatized with tert-butyldimethylsilyl (t-BDMS) for GC-MS analysis. A single crystal separated from the extract was used for an x-ray structure analysis, giving the monoclinic unit cell, space group P21/c with ao = 5.543 A, bo = 8.845 A, co = 5.086 A, and beta = 91.9 degrees, consistent with beta-succinic acid, HOOC(CH2)COOH. The amount of extracted acids is estimated to be of the order of 0.1 to 0.5 mg g-1 MgO. The MgO crystals from which these organic acids were extracted grew from the 2860 degrees C hot melt, saturated with CO/CO2 and H2O, thereby incorporating small amounts of the gaseous components to form a solid solution (ss) with MgO. Upon cooling, the ss becomes supersaturated, causing solute carbon and other solute species to segregate not only to the surface but also internally, to dislocations and subgrain boundaries. The organic acids extracted from the MgO crystals after crushing appear to derive from these segregated solutes that formed C-C, C-H and C-O bonds along dislocations and other defects in the MgO structure, leading to entities that can generically be described as (HxCyOz)n-. The processes underlying the formation of these precursors are fundamental in nature and expected to be operational in any minerals, preferentially those with dense structures, that crystallized in H2O-CO2-laden environments. This opens the possibility that common magmatic and metamorphic rocks when weathering at the surface of a tectonically active planet like Earth may be an important source of abiogenically formed complex organic compounds.

  8. Carboxylic and Dicarboxylic Acids Extracted from Crushed Magnesium Oxide Single Crystals

    NASA Technical Reports Server (NTRS)

    Freund, Friedemann; Gupta, Alka D.; Kumar, Devendra; DeVincenzi, Donald (Technical Monitor)

    1998-01-01

    Carboxylic and dicarboxylic acids (glycolic, oxalic, malonic and succinic) have been extracted with tetrahydrofuran (THE) and H2O from large synthetic MgO crystals, crushed to a medium fine powder. The extracts were characterized by infrared spectroscopy and (sup 1)H-NMR (Nuclear Magnetic Resonance). The THF extracts were derivatized with tert-butyldimethylsilyl (t-BDMS) for GC-MS (Gas Chromatography - Mass Spectroscopy) analysis. A single crystal separated from the extract was used for an x-ray structure analysis, giving the monoclinic unit cell, space group P2(sub 1)/c with a(sub o) = 5.543 A, b(sub o) = 8.845 A, c(sub o) = 5.086 A, and beta = 91.9 degrees, consistent with beta-succinic acid, HOOC(CH2)COOH. The amount of extracted acids is estimated to be of the order of 0.1 to 0.5 mg/g MgO. The MgO crystals from which these organic acids were extracted grew from the 2360 C hot melt, saturated with CO/CO2 and H2O, thereby incorporating small amounts of the gaseous components to form a solid solution (ss) with MgO. Upon cooling, the ss becomes supersaturated, causing solute carbon and other solute species to segregate not only to the surface but also internally, to dislocations and subgrain boundaries. The organic acids extracted from the MgO crystals after crushing appear to derive from these segregated solutes that formed C-C, C-H, and C-O bonds along dislocations and other defects in the MgO structure, leading to entities that can generically be described as (HxCyOz)(sup n-). The processes underlying the formation of these precursors are fundamental in nature and expected to be operational in any minerals, preferentially those with dense structures, that crystallized in H2O-CO2-laden environments. This opens the possibility that common magmatic and metamorphic rocks when weathering at the surface of a tectonically active planet like Earth may be an important source of abiogenically formed complex organic compounds.

  9. Fate of perfluorinated carboxylates and sulfonates during snowmelt within an urban watershed.

    PubMed

    Meyer, Torsten; De Silva, Amila O; Spencer, Christine; Wania, Frank

    2011-10-01

    The transport dynamics of perfluorinated carboxylic acids and sulfonates during snowmelt in the highly urbanized Highland Creek watershed in Toronto, Canada was investigated by analyzing river water, bulk snow, and groundwater, sampled in February and March 2010, by means of liquid chromatography-tandem mass spectrometry. Perfluorohexanoate, perfluorooctanoate, and perfluorooctane sulfonate were dominant in river water, with concentrations of 4.0-14 ng·L(-1), 2.2-7.9 ng·L(-1), and 2.1-6.5 ng·L(-1), respectively. Relatively high levels of perfluorohexanoate may be related to the recent partial replacement in various consumer products of perfluorooctyl substances with shorter-chained perfluorinated compounds (PFCs). Highest PFC concentrations were found within the more urbanized part of the drainage area, suggestive of residential, industrial, and/or traffic-related sources. The riverine flux of PFCs increased during the snowmelt period, but only approximately one-fifth of the increased flux can be attributed to PFCs present in the snowpack, mostly because concentration in snow are generally quite low compared to those in river water. The remainder of the increased flux must be due to the mobilization of PFCs by the high flow conditions prevalent during snowmelt. Run-off behavior was clearly dependent on perfluoroalkyl chain length: Dilution with relatively clean snowmelt water caused a drop in the river water concentrations of short-chain PFCs at high flow during early melting. This prevented an early concentration peak of those water-soluble PFCs within the stream, as could have been expected in response to their early release from a melting snowpack. Instead, concentrations of particle-associated long-chain PFCs in creek water peaked early in the melt, presumably because high flow mobilized contaminated particles from impervious surfaces in the more urbanized areas of the watershed. The ability to enter the subsurface and deeper groundwater aquifers increased

  10. Preparation of carboxylic acid-bearing polysaccharide nanofiber made from euglenoid β-1,3-glucans.

    PubMed

    Shibakami, Motonari; Tsubouchi, Gen; Nakamura, Makoto; Hayashi, Masahiro

    2013-10-15

    This paper introduces a new strategy for creating surface modified polysaccharide nanofibers. To demonstrate proof of principle, the synthesis, structure, and self-assembly behavior of a carboxylic acid-bearing polysaccharide made from paramylon (β-1,3-glucan) and succinic anhydride were investigated. Examination by a combination of NMR, FT-IR, and SEC-MALLS confirmed that successful preparation of the desired succinylated paramylon without significant depolymerization. NMR, SEC-MALLS, visible absorption and CD spectroscopic analyses indicated that the paramylon derivative forms the triplex structure in solutions. SEM observation revealed that succinylated paramylon forms a nanofiber that has carboxylic acid on the surface. PMID:23987321

  11. Toward interfacing organic semiconductors with ferromagnetic transition metal substrates: enhanced stability via carboxylate anchoring.

    PubMed

    Han, R; Blobner, F; Bauer, J; Duncan, D A; Barth, J V; Feulner, P; Allegretti, F

    2016-07-28

    We demonstrate that chemically well-defined aromatic self-assembled monolayers (SAMs) bonded via a carboxylate head group to surfaces of ferromagnetic (FM = Co, Ni, Fe) transition metals can be prepared at ambient temperature in ultra-high vacuum and are thermally stable up to 350-400 K (depending on the metal). The much superior stability over thiolate-bonded SAMs, which readily decompose above 200 K, and the excellent electronic communication guaranteed by the carboxylate bonding render benzoate/FM-metal interfaces promising candidates for application in spintronics. PMID:27417687

  12. Comparative structure analysis of non-polar organic ferrofluids stabilized by saturated mono-carboxylic acids.

    PubMed

    Avdeev, M V; Bica, D; Vékás, L; Aksenov, V L; Feoktystov, A V; Marinica, O; Rosta, L; Garamus, V M; Willumeit, R

    2009-06-01

    The structure of ferrofluids (magnetite in decahydronaphtalene) stabilized with saturated mono-carboxylic acids of different chain lengths (lauric, myristic, palmitic and stearic acids) is studied by means of magnetization analysis and small-angle neutron scattering. It is shown that in case of saturated acid surfactants, magnetite nanoparticles are dispersed in the carrier approximately with the same size distribution whose mean value and width are significantly less as compared to the classical stabilization with non-saturated oleic acid. The found thickness of the surfactant shell around magnetite is analyzed with respect to stabilizing properties of mono-carboxylic acids. PMID:19376524

  13. From Brittle to Pliant Viscoelastic Materials with Solid State Linear Polyphosphonium - Carboxylate Assemblies

    PubMed Central

    Godeau, Guilhem; Navailles, Laurence; Nallet, Frédéric; Lin, Xinrong; McIntosh, Thomas J.; Grinstaff, Mark W.

    2013-01-01

    A polystyrenylphosphonium polymer was synthesized and complexed with various carboxylic acid derivatives to form new solid-state polyelectrolyte-surfactant assemblies. The properties of these ionic materials were highly dependent on the nature of the anion and included a brittle material, a rubbery ball that bounces, or a sticky fiber. The values for the equilibrium modulus, storage modulus, and loss modulus were dependent on the composition of the carboxylic acid and the number of electrostatic interactions. Small-angle X-ray scattering studies on the supramolecular assemblies confirmed a bilayer structure for two of the assemblies. PMID:24511156

  14. Branched Arylalkenes from Cinnamates: Selectivity Inversion in Heck Reactions by Carboxylates as Deciduous Directing Groups.

    PubMed

    Tang, Jie; Hackenberger, Dagmar; Goossen, Lukas J

    2016-09-01

    A decarboxylative Mizoroki-Heck coupling of aryl halides with cinnamic acids has been developed in which the carboxylate group directs the arylation into its β-position before being tracelessly removed through protodecarboxylation. In the presence of a copper/palladium catalyst, both electron-rich and electron-deficient aryl bromides and chlorides bearing numerous functionalities were successfully coupled with broadly available cinnamates, with selective formation of 1,1-disubstituted alkenes. This reaction concept, in which the carboxylate acts as a deciduous directing group, ideally complements traditional 1,2-selective Heck reactions of styrenes. PMID:27485163

  15. Entanglement and Bell's inequality violation above room temperature in metal carboxylates.

    SciTech Connect

    Souza, A M; Soares-Pinto, D O; Sarthour, R S; Oliveira, I S; Reis, Mario S; Brandao, Paula; Moreira Dos Santos, Antonio F

    2009-01-01

    In the present work we show that a particular family of materials, the metal carboxylates, may have entangled states up to very high temperatures. From magnetic-susceptibility measurements, we have estimated the critical temperature below which entanglement exists in the copper carboxylate {Cu-2(O2CH)(4)}{Cu(O2CH)(2)(2-methylpyridine)(2)}, and we have found this to be above room temperature (T-e similar to 630 K). Furthermore, the results show that the system remains maximally entangled until close to similar to 100 K and the Bell's inequality is violated up to nearly room temperature (similar to 290 K).

  16. Nucleosides of 4-methylthio-1,2,3-triazol-5-yl-carboxylic acid derivatives

    SciTech Connect

    Shingarova, I.D.; Yartseva, I.V.; Preobrazhenskaya, M.N.

    1987-08-01

    2-..beta..-D-Ribofuranosyl-4-methylthio-5-methoxycarbonyl-1,2,3-triazole was obtained by fusing 4-methylthio-5-methoxycarbonyl-1,2,3-triazole together with tetraacyl-D-ribofuranose, followed by deacylation, and its amide and hydrazide were prepared. The structures of the new nucleosides were established by converting them into known 2-nucleosides of 1,2,3-triazol-4-yl-carboxylic acid derivatives. By comparing PMR spectra with previously reported PMR spectra for the isomeric 1- and 2-nucleosides of 1,2,3-triazol-4-yl-carboxylic acid derivatives, the synthesized nucleosides could be assigned to 2-substituted triazoles.

  17. Enantioselective TADMAP-Catalyzed Carboxyl Migration Reactions for the Synthesis of Stereogenic Quaternary Carbon

    PubMed Central

    Shaw, Scott A.; Aleman, Pedro; Christy, Justin; Kampf, Jeff W.; Va, Porino

    2008-01-01

    The chiral, nucleophilic catalyst TADMAP (1) has been prepared from 3-lithio-4-dimethylamino-pyridine (5) and triphenylacetaldehyde (3), followed by acylation and resolution. TADMAP catalyzes the carboxyl migration of oxazolyl, furanyl, and benzofuranyl enol carbonates with good to excellent levels of enantioselection. The oxazole reactions are especially efficient, and are used to prepare chiral lactams (23) and lactones (30) containing a quaternary asymmetric carbon. TADMAP-catalyzed carboxyl migrations in the indole series are relatively slow and proceed with inconsistent enantioselectivity. Modeling studies (B3LYP/6-31G*) have been used in qualitative correlations of catalyst conformation, reactivity, and enantioselectivity. PMID:16417383

  18. A new 3D Cd-triazolate framework obtained from in situ decarboxylication of 5-amino-3-carboxyl-1,2,4-triazole

    NASA Astrophysics Data System (ADS)

    Liu, Bing; Feng, Hui-Jun; Zhang, Zong-Hui; Xu, Ling; Jiao, Huan

    2015-10-01

    A new 3D Cd-triazolate MOF compound [Cd(Hatrz) (SO4)] (1) (Hatrz = 3-amino-1H-1,2,4-triazole) was obtained from in situ decarboxylication of 5-amino-3-carboxyl-1,2,4-triazole (H2atrc) under the hydrothermal reaction of CdSO4 with H2atrc. Compound 1 features itself a Hatrz-supporting 3D architecture based on the connection of inorganic [CdSO4] layers with Hatrz spacers. Cd(II) atom, SO4 2 - and Hatrz dummied as 6-, 4- and 2-connected nodes respectively, compound 1 can be simplified to a (2,4,6)-connected {44.62.88.12}{44.62}{8} topological network. The thermal stability of 1 is up to ca. 402 °C, and the fluorescence of 1 shows an emission at 366 nm, originating from SO4 2 - → Cd transfer. PXRD of compound 1 confirms the phase purity of the bulk sample. FT-IR spectrum of 1 is in accord with the structure analysis.

  19. Organosulfates and Carboxylic Acids in Secondary Organic Aerosols in Coniferous Forests in Rocky Mountains (USA), Sierra Nevada Mountains (USA) and Northern Europe (Finland and Denmark)

    NASA Astrophysics Data System (ADS)

    Glasius, M.; Hansen, A. M. K.; Kristensen, K.; Kristensen, T. B.; Mccubbin, I. B.; Hallar, A. G.; Petäjä, T.; Surratt, J. D.; Worton, D. R.; Bilde, M.; Kulmala, M. T.; Goldstein, A. H.

    2014-12-01

    Levels and chemical composition of secondary organic aerosols affect their climate effects and properties. Organosulfates (OS) are formed through heterogeneous reactions involving oxidized sulfur compounds, primarily originating from anthropogenic sources. Availability of authentic standards have until now been an obstacle to quantitative investigations of OS in atmospheric aerosols. We have developed a new, facile method for synthesis and purification of OS standards. Here we have used 7 standards to quantify OS and nitrooxy organosulfates (NOS) observed in aerosols collected at four sites in coniferous forests in USA and Europe during spring or summer. The two American sites were Storm Peak Laboratory, Colorado (Rocky Mountains, elevation 3220 m a.s.l) and Sierra Nevada Mountains, California (as part of BEARPEX 2007 and 2009). The European sites were Hyytiälä Forest Station, Finland (in the boreal zone) and Silkeborg, Denmark (temperate forest). Aerosol filter samples were extracted and analyzed using a high performance liquid chromatograph coupled through an electrospray inlet to a quadrupole time-of-flight mass spectrometer (HPLC-QTOF-MS). We identified 11 carboxylic acids using authentic standards, while 16 different OS and 8 NOS were identified based on their molecular mass and MS fragmentation patterns, as well as comparison with available standards. OS were ubiquitous in the atmospheric aerosol samples, even at the high elevation mountain station. Levels of carboxylic acids from oxidation of monoterpenes were 8-25 ng m-3 at Silkeborg and Storm Peak Laboratory, while concentrations at the sites with strong regional monoterpene emissions (Sierra Nevada Mountains and Hyytiälä) were much higher (10-200 ng m-3). At all sites, the dominant group of OS were derived from isoprene (IEPOX) and related compounds, while OS of monoterpenes showed lower concentrations, except at Hyytiälä during periods of north-westerly winds when monoterpene OS were at similar or

  20. Polar herbicides, pharmaceutical products, perfluorooctanesulfonate (PFOS), perfluorooctanoate (PFOA), and nonylphenol and its carboxylates and ethoxylates in surface and tap waters around Lake Maggiore in Northern Italy.

    PubMed

    Loos, Robert; Wollgast, Jan; Huber, Tania; Hanke, Georg

    2007-02-01

    A survey of contamination of surface and drinking waters around Lake Maggiore in Northern Italy with polar anthropogenic environmental pollutants has been conducted. The target analytes were polar herbicides, pharmaceuticals (including antibiotics), steroid estrogens, perfluorooctanesulfonate (PFOS), perfluoroalkyl carboxylates (including perfluorooctanoate PFOA), nonylphenol and its carboxylates and ethoxylates (NPEO surfactants), and triclosan, a bactericide used in personal-care products. Analysis of water samples was performed by solid-phase extraction (SPE) then liquid chromatography-triple-quadrupole (tandem) mass spectrometry (LC-MS-MS). By extraction of 1-L water samples and concentration of the extract to 100 microL, method detection limits (MDLs) as low as 0.05-0.1 ng L(-1) were achieved for most compounds. Lake-water samples from seven different locations in the Southern part of Lake Maggiore and eleven samples from different tributary rivers and creeks were investigated. Rain water was also analyzed to investigate atmospheric input of the contaminants. Compounds regularly detected at very low concentrations in the lake water included: caffeine (max. concentration 124 ng L(-1)), the herbicides terbutylazine (7 ng L(-1)), atrazine (5 ng L(-1)), simazine (16 ng L(-1)), diuron (11 ng L(-1)), and atrazine-desethyl (11 ng L(-1)), the pharmaceuticals carbamazepine (9 ng L(-1)), sulfamethoxazole (10 ng L(-1)), gemfibrozil (1.7 ng L(-1)), and benzafibrate (1.2 ng L(-1)), the surfactant metabolite nonylphenol (15 ng L(-1)), its carboxylates (NPE(1)C 120 ng L(-1), NPE(2)C 7 ng L(-1), NPE(3)C 15 ng L(-1)) and ethoxylates (NPE( n )Os, n = 3-17; 300 ng L(-1)), perfluorinated surfactants (PFOS 9 ng L(-1), PFOA 3 ng L(-1)), and estrone (0.4 ng L(-1)). Levels of these compounds in drinking water produced from Lake Maggiore were almost identical with those found in the lake itself, revealing the poor performance of sand filtration and chlorination applied by the local