Sample records for carboxylic acid function

  1. Carboxylic Acid Unknowns and Titration 90 CARBOXYLIC ACID UNKNOWN

    E-print Network

    Jasperse, Craig P.

    Carboxylic Acid Unknowns and Titration 90 CARBOXYLIC ACID UNKNOWN A. Solubility Tests: Water, Na the formula weight. #12;Carboxylic Acid Unknowns and Titration 91 Note: Do your titration once, and check

  2. Gas-Phase Reactivity of Carboxylic Acid Functional Groups with Carbodiimides

    PubMed Central

    Prentice, Boone M.; Gilbert, Joshua D.; Stutzman, John R.; Forrest, William P.; McLuckey, Scott A.

    2012-01-01

    Gas-phase modification of carboxylic acid functionalities is performed via ion/ion reactions with carbodiimide reagents [N-cyclohexyl-N?-(2-morpholinoethyl)carbodiimide (CMC) and [3-(3-Ethylcarbodiimide-1-yl)propyl]trimethylaminium (ECPT). Gas-phase ion/ion covalent chemistry requires the formation of a long-lived complex. In this instance, the complex is stabilized by an electrostatic interaction between the fixed charge quaternary ammonium group of the carbodiimide reagent cation and the analyte dianion. Subsequent activation results in characteristic loss of an isocyanate derivative from one side of the carbodiimide functionality, a signature for this covalent chemistry. The resulting amide bond is formed on the analyte at the site of the original carboxylic acid. Reactions involving analytes that do not contain available carboxylic acid groups (e.g., they have been converted to sodium salts) or reagents that do not have the carbodiimide functionality do not undergo a covalent reaction. This chemistry is demonstrated using PAMAM generation 0.5 dendrimer, ethylenediaminetetraacetic acid (EDTA), and the model peptide DGAILDGAILD. This work demonstrates the selective gas-phase covalent modification of carboxylic acid functionalities. PMID:23208744

  3. Carboxylic acid functional group analysis using constant neutral loss scanning-mass spectrometry.

    PubMed

    Dron, Julien; Eyglunent, Gregory; Temime-Roussel, Brice; Marchand, Nicolas; Wortham, Henri

    2007-12-12

    The present study describes the development of a new analytical technique for the functional group determination of the carboxylic moiety using atmospheric pressure chemical ionization-mass spectrometry (APCI-MS/MS) operated in the constant neutral loss scanning (CNLS) mode. Carboxylic groups were first derivatized into their corresponding methyl esters by reacting with BF3/methanol mix and the reaction mixture was then directly injected into the APCI chamber. The loss of methanol (m/z = 32 amu) resulting from the fragmentation of the protonated methyl esters was then monitored. Applying this method together with a statistical approach to reference mixtures containing 31 different carboxylic acids at randomly calculated concentrations demonstrated its suitability for quantitative functional group measurements with relative standard deviations below 15% and a detection limit of 0.005 mmol L(-1). Its applicability to environmental matrices was also shown through the determination of carboxylic acid concentrations inside atmospheric aerosol samples. To the best of our knowledge, it is the first time that the tandem mass spectrometry was successfully applied to functional group analysis, offering great perspectives in the characterization of complex mixtures which are prevailing in the field of environmental analysis as well as in the understanding of the chemical processes occurring in these matrices. PMID:18022412

  4. Electrical and physical characterization of bilayer carboxylic acid-functionalized molecular layers.

    PubMed

    Pookpanratana, Sujitra; Robertson, Joseph W F; Jaye, Cherno; Fischer, Daniel A; Richter, Curt A; Hacker, Christina A

    2013-02-12

    We have used flip chip lamination (FCL) to form monolayer and bilayer molecular junctions of carboxylic acid-containing molecules with Cu atom incorporation. Carboxylic acid-terminated monolayers are self-assembled onto ultrasmooth Au by using thiol chemistry and grafted onto n-type Si. Prior to junction formation, monolayers are physically characterized by using polarized infrared absorption spectroscopy, X-ray photoelectron spectroscopy, and near-edge X-ray absorption fine structure spectroscopy, confirming the molecular quality and functional group termination. FCL was used to form monolayer junctions onto H-terminated Si or bilayer junctions of carboxylic acid monolayers on Au and Si. From the electrical measurements, we find that the current through the junction is attenuated as the effective molecular length within the junction increases, indicating that molecules are electrically active within the junction. We find that the electronic transport through the bilayer junction saturates at very thick effective distances possibly because of another electron-transport mechanism that is not nonresonant tunneling as a result of trapped defects or sequential tunneling. In addition, bilayer junctions are fabricated with and without Cu atoms, and we find that the electron transport is not distinguishably different when Cu atoms are within the bilayer. PMID:23362920

  5. 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.

  6. Expression of a functional jasmonic acid carboxyl methyltransferase is negatively correlated with strawberry fruit development.

    PubMed

    Preuß, Anja; Augustin, Christiane; Figueroa, Carlos R; Hoffmann, Thomas; Valpuesta, Victoriano; Sevilla, José F; Schwab, Wilfried

    2014-09-15

    The volatile metabolite methyl jasmonate (MeJA) plays an important role in intra- and interplant communication and is involved in diverse biological processes. In this study, we report the cloning and functional characterization of a S-adenosyl-l-methionine:jasmonic acid carboxyl methyltransferase (JMT) from Fragaria vesca and Fragaria×ananassa. Biochemical assays and comprehensive transcript analyses showed that JMT has been erroneously annotated as gene fusion with a carboxyl methyltransferase (CMT) (gene15184) in the first published genome sequence of F. vesca. Recombinant FvJMT catalyzed the formation of MeJA with KM value of 22.3?M while FvCMT and the fusion protein were almost inactive. Activity of JMT with benzoic acid and salicylic acid as substrates was less than 1.5% of that with JA. Leucine at position 245, an amino acid missing in other JMT sequences is essential for activity of FvJMT. In accordance with MeJA levels, JMT transcript levels decreased steadily during strawberry fruit ripening, as did the expression levels of JA biosynthesis and regulatory genes. It appears that CMT has originated by a recent duplication of JMT and lost its enzymatic activity toward JA. In the newest version of the strawberry genome sequence (June 2014) CMT and JMT are annotated as separate genes in accordance with differential temporal and spatial expression patterns of both genes in Fragaria sp. In conclusion, MeJA, the inactive derivative of JA, is probably involved in early steps of fruit development by modulating the levels of the active plant hormone JA. PMID:25046752

  7. Thermolysis of carboxylic acid salts

    SciTech Connect

    Khlestkin, R.N.; Khlestkina, V.L.; Usanov, N.G.; Gareev, V.M.

    1982-07-01

    The dependence of the thermal stability of carboxylic acid salts on the nature of the anion and cation of the salt was studied. It was found that the capacity for thermal decomposition by salts of aliphatic, naphthenic, aromatic and heterocyclic carboxylic acids (with the exception of alkali salts) varies in inverse proportion to the values of the pK/sub a/ of the acids and to the values of the standard heats of formation of oxides (of the metal which forms the salt) relative to a monovalent bond with oxygen. An empirical equation which permits the thermal stability of many carboxylic acid salts to be predicted is given. Recommendations are developed for evaluating the relative activity of oxide and carbonate catalysts in reactions of vapor-phase conversion of aliphatic carboxylic acids to ketones and their operating temperatures.

  8. Understanding biocatalyst inhibition by carboxylic acids

    PubMed Central

    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

  9. Detection of a CO and NH3 gas mixture using carboxylic acid-functionalized single-walled carbon nanotubes

    PubMed Central

    2013-01-01

    Carbon nanotubes (CNT) are extremely sensitive to environmental gases. However, detection of mixture gas is still a challenge. Here, we report that 10 ppm of carbon monoxide (CO) and ammonia (NH3) can be electrically detected using a carboxylic acid-functionalized single-walled carbon nanotubes (C-SWCNT). CO and NH3 gases were mixed carefully with the same concentrations of 10 ppm. Our sensor showed faster response to the CO gas than the NH3 gas. The sensing properties and effect of carboxylic acid group were demonstrated, and C-SWCNT sensors with good repeatability and fast responses over a range of concentrations may be used as a simple and effective detection method of CO and NH3 mixture gas. PMID:23286690

  10. Chemoselective Functionalization of Carboxylic Acid and Phenol Containing Natural Products and the Development and Use of a Nucleophile Catalyzed Michael Aldol Lactonization Process

    E-print Network

    McFarlin, Rae

    2013-05-02

    probes for mechanism of action studies. Herein, we describe a strategy to functionalize carboxylic acid and phenol containing natural products. This methodology relies on the in situ generation of diazoalkanes to form the corresponding carbonyl esters...

  11. Cyclopentane-1,3-dione: A Novel Isostere for the Carboxylic Acid Functional Group. Application to the Design of Potent Thromboxane (A2)-Receptor Antagonists

    PubMed Central

    Ballatore, Carlo; Soper, James; Piscitelli, Francesco; James, Michael; Huang, Longchuan; Atasoylu, Onur; Huryn, Donna M.; Trojanowski, John Q.; Lee, Virginia M.-Y.; Brunden, Kurt R.; Smith, Amos B.

    2011-01-01

    Cyclopentane-1,3-diones are known to exhibit pKa values typically in the range of carboxylic acids. To explore the potential of the cyclopentane-1,3-dione unit as a carboxylic acid isostere, the physical-chemical properties of representative congeners were examined and compared with similar derivatives bearing carboxylic acid or tetrazole residues. These studies suggested that cyclopentane-1,3-diones may effectively substitute for the carboxylic acid functional group. To demonstrate the use of the cyclopentane-1,3-dione isostere in drug-design, derivatives of a known thromboxane-A2 prostanoid (TP) receptor antagonist, 3-(3-(2-(4-chlorophenylsulfonamido)ethyl)-phenyl)propanoic acid (12), were synthesized and evaluated in both functional and radioligand-binding assays. A series of mono- and di-substituted cyclopentane-1,3-dione derivatives (41–45) were identified that exhibit nM IC50 and Kd values similar to 12. Collectively, these studies demonstrate that the cyclopentane-1,3-dione moiety comprises a novel isostere of the carboxylic acid functional group. Given the combination of the relatively strong acidity, tunable lipophilicity, and versatility of the structure, the cyclopentane-1,3-dione moiety may constitute a valuable addition to the palette of carboxylic acid isosteres. PMID:21863799

  12. Piperazine and its carboxylic acid derivatives-functionalized mesoporous silica as nanocarriers for gemcitabine: adsorption and release study.

    PubMed

    Bahrami, Zohreh; Badiei, Alireza; Atyabi, Fatemeh; Darabi, Hossein Reza; Mehravi, Bita

    2015-04-01

    Piperazine-functionalized SBA-15 nanorods were synthesized by post grafting method with methyldimethoxysilylpropylpiperazine (MDSP). The carboxylic acid derivatives of piperazine-functionalized SBA-15 nanorods were obtained using two different kinds of precursors (bromoacetic acid and succinic anhydride). The prepared materials were used as nanocarriers for the anticancer drug (gemcitabine). The obtained samples were characterized by SAXS, N2 adsorption-desorption, SEM, TEM, DLS, thermogravimetric analysis, FTIR, Raman and UV spectroscopies. The adsorption and release properties of all samples were investigated. In vitro study included cell toxicity. It was found that the surface functionalization increases the interaction between the carrier and gemcitabine and results in the loading enhancement of the drug. In addition, the adsorption of gemcitabine on the modified mesoporous matrix depends on the type of the introduced functional groups. The carboxylic acid-modified samples have higher loading content, due to the strong interaction with gemcitabine. The maximum content of deposited drug in the modified SBA-15 nanorods is close to 36wt.% that it is related to PC2-SBA-15 sample which obtained using succinic anhydride. The obtained results reveal that the surface functionalization leads toward a significant decrease of the drug release rate without any appreciable cytotoxicity. No significant differences are observed among the drug release rate from the modified samples. PMID:25686928

  13. Molecular Structure of Cyclopropane carboxylic acid

    NSDL National Science Digital Library

    2003-04-11

    Cyclopropane carboxylic acid is a clear liquid used as an intermediate for agrochemicals, pharmaceuticals, and other organic synthesis such as for the applications of electronics, chemicals, polymer additives, coatings, adhesives, surfactants, and other applications. Also, derivatives of cyclopropane-carboxylic acid are used against parasites in plants and animals. For example, the alkynyl esters of cyclopropane-carboxylic acid are used as pesticides. Similarly, cyclopropane carboxylic acid esters containing a polyhalogenated substituent are used as fungicides.

  14. Synthesis, bifunctionalization, and remarkable adsorption performance of benzene-bridged periodic mesoporous organosilicas functionalized with high loadings of carboxylic acids.

    PubMed

    Wu, Hao-Yiang; Shieh, Fa-Kuen; Kao, Hsien-Ming; Chen, Yi-Wen; Deka, Juti Rani; Liao, Shih-Hsiang; Wu, Kevin C-W

    2013-05-10

    Highly ordered benzene-bridged periodic mesoporous organosilicas (PMOs) that were functionalized with exceptionally high loadings of carboxylic acid groups (COOH), up to 80?mol?% based on silica, have been synthesized and their use as adsorbents for the adsorption of methylene blue (MB), a basic dye pollutant, and for the loading and release of doxorubicin (DOX), an anticancer drug, is demonstrated. These COOH-functionalized benzene-silicas were synthesized by the co-condensation of 1,4-bis(triethoxysilyl) benzene (BTEB) and carboxyethylsilanetriol sodium salt (CES), an organosilane that contained a carboxylic acid group, in the presence of non-ionic oligomeric surfactant Brij?76 in acidic medium. The materials thus obtained were characterized by a variety of techniques, including powder X-ray diffraction (XRD), nitrogen-adsorption/desorption isotherms, TEM, and (13)C and (29)Si solid-state NMR spectroscopy. Owing to the exceptionally high loadings of COOH groups, their high surface areas, and possible ?-?-stacking interactions, these adsorbents have very high adsorption capacities and extremely rapid adsorption rates for MB removal and for the controlled loading/release of DOX, thus manifesting their great potential for environmental and biomedical applications. PMID:23512281

  15. Conversion of carboxylate salts to carboxylic acids via reactive distillation

    E-print Network

    Williamson, Shelly Ann

    2000-01-01

    on the conversion of the carboxylate salts produced via fermentation into their corresponding acids via reactive distillation. The primary objective is to determine the optimal operating conditions of the distillation. A secondary objective is to optimize...

  16. Synergistic effect of self-assembled carboxylic acid-functionalized carbon nanotubes and carbon fiber for improved electro-activated polymeric shape-memory nanocomposite

    NASA Astrophysics Data System (ADS)

    Lu, Haibao; Min Huang, Wei

    2013-06-01

    The present work studies the synergistic effect of self-assembled carboxylic acid-functionalized carbon nanotube (CNT) and carbon fiber on the electrical property and electro-activated recovery behavior of shape memory polymer (SMP) nanocomposites. The combination of CNT and carbon fiber results in improved electrical conductivity in the SMP nanocomposites. Carboxylic acid-functionalized CNTs are grafted onto the carbon fibers and then self-assembled by deposition to significantly enhance the reliability of the bonding between carbon fiber and SMP via van der Waals and covalent crosslink. Furthermore, the self-assembled carboxylic acid-functionalized CNTs and carbon fibers enable the SMP nanocomposites for Joule heating triggered shape recovery.

  17. Peptide coupling between amino acids and the carboxylic acid of a functionalized chlorido-gold(I)-phosphane.

    PubMed

    Kriechbaum, Margit; List, Manuela; Himmelsbach, Markus; Redhammer, Günther J; Monkowius, Uwe

    2014-10-01

    We have developed a protocol for the direct coupling between methyl ester protected amino acids and the chlorido-gold(I)-phosphane (p-HOOC(C6H4)PPh2)AuCl. By applying the EDC·HCl/NHS strategy (EDC·HCl = N-ethyl-N'-(3-(dimethylamino)propyl)carbodiimide hydrochloride, NHS = N-hydroxysuccinimide), the methyl esters of l-phenylalanine, glycine, l-leucine, l-alanine, and l-methionine are coupled with the carboxylic acid of the gold complex in moderate to good yields (62-88%). All amino acid tagged gold complexes were characterized by (1)H and (13)C NMR spectroscopy and high-resolution mass spectrometry. As corroborated by measurement of the angle of optical rotation, no racemization occurred during the reaction. The molecular structure of the leucine derivative was determined by single-crystal X-ray diffraction. In the course of developing an efficient coupling protocol, the acyl chlorides (p-Cl(O)C(C6H4)PPh2)AuX (X = Cl, Br) were also prepared and characterized. PMID:25203269

  18. Langmuir 1985,1,725-740 725 Acid-Base Behavior of Carboxylic Acid Groups Covalently

    E-print Network

    Deutch, John

    Langmuir 1985,1,725-740 725 Acid-Base Behavior of Carboxylic Acid Groups Covalently Attached: August 7, 1985 Oxidation of polyethylene with chromic acidfsulfuric acid generates a material (PE-C02H) having a high density of carboxylic acid and ketone functionalities in a thin surface layer

  19. 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

  20. Photocaging of carboxylic acids: a modular approach.

    PubMed

    Szyma?ski, Wiktor; Velema, Willem A; Feringa, Ben L

    2014-08-11

    Photocaged compounds are important tools for studying and regulating multiple processes, including biological functions. Reported herein is the use of the Passerini multicomponent reaction for modular preparation of photocaged carboxylic acids. The reaction is compatible with several functionalities and proceeds smoothly both in water and dichloromethane. The choice of aldehyde determines the wavelength used for deprotection and enables formation of orthogonally protected products. The isocyanide component can be used for introduction of reactive tags and photosensitizers, as well as for immobilization on a solid support. PMID:24801857

  1. A NCS mediated oxidative C-H bond functionalization: direct esterification between a C(sp(3))-H bond and carboxylic acids.

    PubMed

    Zheng, Yang; Mao, Jincheng; Rong, Guangwei; Xu, Xinfang

    2015-05-12

    A transition metal free oxidative C-H bond functionalization/esterification of ?-alkoxy alkanes with acids is described in this report. This method is effectively mediated by NCS instead of traditional oxidants, like TBHP or its derivatives, and directly generates the esterification products in moderate to high yield under mild conditions. This tranformation constitutes a practical and general approach toward various ?-acyloxy ethers with broad substrate generality; alkyl-, aryl-, alkenyl- and alkynyl-carboxylic acids are all well tolerated. PMID:25921733

  2. An experimental and density functional study on conformational and spectroscopic analysis of 5-methoxyindole-2-carboxylic acid.

    PubMed

    Cinar, Mehmet; Karabacak, Mehmet; Asiri, Abdullah M

    2015-02-25

    In this article, a brief conformational and spectroscopic characterization of 5-methoxyindole-2-carboxylic acid (5-MeOICA) via experimental techniques and applications of quantum chemical methods is presented. The conformational analysis of the studied molecule was determined theoretically using density functional computations for ground state, and compared with previously reported experimental findings. The vibrational transitions were examined by measured FT-IR and FT-Raman spectroscopic data, and also results obtained from B3LYP and CAM-B3LYP functionals in combination with 6-311++G(d,p) basis set. The recorded proton and carbon NMR spectra in DMSO solution were analyzed to obtain the exact conformation. Due to intermolecular hydrogen bondings, NMR calculations were performed for the dimeric form of 5-MeOICA and so chemical shifts of those protons were predicted more accurately. Finally, electronic properties of steady compound were identified by a comparative study of UV absorption spectra in ethanol and water solution and TD-DFT calculations. PMID:25255480

  3. Redox-neutral palladium-catalyzed C-h functionalization to form isoindolinones with carboxylic acids or anhydrides as readily available starting materials.

    PubMed

    Liang, Hong-Wen; Ding, Wei; Jiang, Kun; Shuai, Li; Yuan, Yi; Wei, Ye; Chen, Ying-Chun

    2015-06-01

    An operationally simple, Pd-catalyzed C-H functionalization is described for the synthesis of important and useful isoindolinones from readily available carboxamides and carboxylic acids or anhydrides. The reactions proceed efficiently with a broad range of substrates under redox-neutral reaction conditions and tolerate a diversity of functional groups. The mechanistic investigation suggests that the reactions involve C-H activation, nucleophilic addition, ?-O elimination, and dehydration steps. PMID:25978091

  4. 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.

  5. 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 (Nafion{trademark} 111). Additionally, nitric acid separation efficiencies ({alpha}) were approximately one order of magnitude higher for the carboxylate solution cast films when compared to Nafion{trademark} 111. The second phase of our work included the generation of thin carboxylate films made by the chemical synthesis perfluoro sulfonate and mixed sulfonate/carboxylate polymers from a perfluoro sulfonyl fluoride precursor, the characterization of the newly generated material, and a study of the transport characteristics of these membranes. Transport studies consisted of the dehydration of nitric acid feeds by pervaporation. In addition, the initial hypothesis was expanded to include demonstration that transmembrane flux and separation efficiencies are a function of the ratio between sulfonate and carboxylate terminated side chains of the perfluoro ionomer. Investigations demonstrated the ability to generate in- house films with varying sulfonate/carboxylate concentrations from commercially available perfluoro sulfonyl fluoride material, and showed that the converted films could be characterized using Fourier transform infrared (FTIR) and x-ray fluorescence (XRF) spectroscopy. Finally, the mixed films where subjected to nitric acid dehydration transport tests and a relationship was found to exist between sulfonate/carboxylate pendant chain ratio and both flux and water separation capability. In summary, experimental results confirmed that, when compared to Nafion 111{trademark}, the mixed film's bulk fluxes decrease by approximately three orders of magnitude and the water separation factor increases by as much as two orders of magnitude as the carboxylate side-chain content was increased from 0 (pure sulfonate film) to 53 mole%, supporting the hypothesis given for this effort. It was observed that the water selectivity improved for both the solution cast perfluoro carboxylate and mixed perfluoro sulfonate/carboxylate films when judged against similar perfluoro sulfonate materials. Of great benefit was that during the investigation a number of research tools w

  6. Adsorption of a carboxylic acid-functionalized aminoxyl radical onto SiO?.

    PubMed

    Murata, Hidenori; Baskett, Martha; Nishide, Hiroyuki; Lahti, Paul M

    2014-04-15

    Silicon wafers both without and with silicon(IV) oxide surface coverage were covered with benzene solutions of stable organic radical 3-(N-tert-butyl-N-aminoxyl)benzoic acid (mNBA). X-ray photoelectron spectroscopy supported the presence of the radical on both surface-cleaned (oxide-reduced) and oxide-covered surfaces. Optical waveguide spectroscopy showed that the radical retained its structure while adsorbed to the surface of the wafers, without noticeable decomposition. AFM and MFM imaging showed that the radical formed blocky particles with a change in rms roughness from 0.3 nm premodification to 1.7 nm postmodification on the surface-cleaned silicon. Similar experiments using oxide-coated silicon showed that the radical adsorbed to form much smoother layers, with a small change in rms roughness from 0.2 to 0.3 nm. Contact angle measurements of water on the premodified and postmodified samples showed a large, hydrophobic change in the silicon oxide surface but only a modest change in the surface-cleaned silicon surface. Samples of mNBA adsorbed onto silica gel showed strong electron-spin resonance signals from the aminoxyl spin, even years after production. The results demonstrate the prospects for treating and coating oxide-covered silicon wafers and silicon oxide-coated particles with a paramagnetically active organic substrate, without major chemical modification of the pretreatment surface; the resulting organic spin sites can be stable for years. PMID:24684264

  7. Molecular level computational studies of polyethylene and polyacrylonitrile composites containing single walled carbon nanotubes: effect of carboxylic acid functionalization on nanotube-polymer interfacial properties

    PubMed Central

    Haghighatpanah, Shayesteh; Bohlén, Martin; Bolton, Kim

    2014-01-01

    Molecular dynamics (MD) and molecular mechanics (MM) methods have been used to investigate additive-polymer interfacial properties in single walled carbon nanotube (SWNT)—polyethylene and SWNT—polyacrylonitrile composites. Properties such as the interfacial shear stress and bonding energy are similar for the two composites. In contrast, functionalizing the SWNT with carboxylic acid groups leads to an increase in these properties, with a larger increase for the polar polyacrylonitrile composite. Increasing the percentage of carbon atoms that were functionalized from 1 to 5% also leads to an increase in the interfacial properties. In addition, the interfacial properties depend on the location of the functional groups on the SWNT wall. PMID:25229056

  8. Ion chromatography of organic carboxylic acids. Determination of monobasic carboxylic and hydroxy acids

    SciTech Connect

    Ivanov, A.A.; Shpigun, O.A.; Zolotov, Yu.A.

    1986-07-10

    An ion chromatographic method has been developed for the determination of monobasic carboxylic and hydroxy acids, as well as some of their chloroderivatives. The optimum eluent for the joint determination of monobasic carboxylic and hydroxy acids, fluoride and chloride ions is a 1 x 10/sup -4/ M solution of NaOH. The limit of detection of acids with this eluent is equal to (1.5-3.1) x 10/sup -3/ ..mu..g/ml. Inorganic anions (F/sup -/, Cl/sup -/, NO/sub 3//sup -/, and SO/sub 4//sup 2 -/), as well as dibasic carboxylic and hydroxy acids, do not interfere with the determination of monobasic carboxylic and hydroxy acids. The method has been used for the determination of lactic acid in gastric juice and that of formic, acetic, propionic, and butyric acids in water and condensate of thermoelectric power plants.

  9. 40 CFR 721.10679 - Carboxylic acid, substituted alkylstannylene ester, reaction products with inorganic acid tetra...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 2014-07-01 false Carboxylic acid, substituted alkylstannylene ester, reaction products with inorganic acid tetra alkyl ester (generic). 721...Substances § 721.10679 Carboxylic acid, substituted alkylstannylene...

  10. Recovery of Carboxylic Acids from Fermentation Broth via Acid Springing

    E-print Network

    Dong, Jipeng

    2010-01-14

    RECOVERY OF CARBOXYLIC ACIDS FROM FERMENTATION BROTH VIA ACID SPRINGING A Thesis by JIPENG DONG Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE December 2008 Major Subject: Chemical Engineering RECOVERY OF CARBOXYLIC ACIDS FROM FERMENTATION BROTH VIA ACID SPRINGING A Thesis by JIPENG DONG Submitted to the Office of Graduate Studies of Texas A...

  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. 4-(Dimethylamino)pyridine-catalysed iodolactonisation of ?,?-unsaturated carboxylic acids.

    PubMed

    Meng, Chuisong; Liu, Zhihui; Liu, Yuxiu; Wang, Qingmin

    2015-06-10

    4-(Dimethylamino)pyridine functioned as an excellent catalyst for iodolactonisation reactions of ?,?-unsaturated carboxylic acids, affording ?-lactones, ?-lactones, or both under neutral conditions at room temperature. The effects of substrate structures on the iodolactonisation were investigated, and a catalytic mechanism is proposed. PMID:26009007

  13. 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.

  14. Ethane-bridged periodic mesoporous organosilicas functionalized with high loadings of carboxylic acid groups: synthesis, bifunctionalization, and fabrication of metal nanoparticles.

    PubMed

    Deka, Juti Rani; Kao, Hsien-Ming; Huang, Shu-Ying; Chang, Wei-Chieh; Ting, Chun-Chiang; Rath, Purna Chandra; Chen, Ching-Shiun

    2014-01-13

    Well-ordered periodic mesoporous organosilicas (PMOs) functionalized with high contents of carboxylic acid (?COOH) groups, up to 85?mol?% based on silica, were synthesized by co-condensation of 1,2-bis(triethoxysilyl)ethane (BTEE) and carboxyethylsilanetriol sodium salt (CES) under acidic conditions by using alkyl poly(oxyethylene) surfactant Brij?76 as a structure-directing agent. A variety of techniques including powder X-ray diffraction (XRD), nitrogen adsorption/desorption, Fourier-transformed infrared (FTIR), transmission electron microscopy (TEM), (13) C- and (29) Si solid-state nuclear magnetic resonance (NMR) were used to characterize the products. The materials thus obtained were used as an effective support to synthesize metal nanoparticles (Ag and Pt) within the channel of 2D hexagonal mesostructure of PMOs. The size and distribution of the nanoparticles were observed to be highly dependent on the interaction between the carboxylic acid functionalized group and the metal precursors. The size of Pt nanoparticles reduced from 3.6 to 2.5?nm and that of Ag nanoparticles reduced from 5.3 to 3.4?nm with the increase in the ?COOH loading from 10 to 50?%. PMID:24338957

  15. Comparison of silatrane, phosphonic acid, and carboxylic acid functional groups for attachment of porphyrin sensitizers to TiO2 in photoelectrochemical cells.

    PubMed

    Brennan, Bradley J; Llansola Portolés, Manuel J; Liddell, Paul A; Moore, Thomas A; Moore, Ana L; Gust, Devens

    2013-10-21

    A tetra-arylporphyrin dye was functionalized with three different anchoring groups used to attach molecules to metal oxide surfaces. The physical, photophysical and electrochemical properties of the derivatized porphyrins were studied, and the dyes were then linked to mesoporous TiO2. The anchoring groups were ?-vinyl groups bearing either a carboxylate, a phosphonate or a siloxy moiety. The siloxy linkages were made by treatment of the metal oxide with a silatrane derivative of the porphyrin. The surface binding and lability of the anchored molecules were studied, and dye performance was compared in a dye-sensitized solar cell (DSSC). Transient absorption spectroscopy was used to study charge recombination processes. At comparable surface concentration, the porphyrin showed comparable performance in the DSSC, regardless of the linker. However, the total surface coverage achievable with the carboxylate was about twice that obtainable with the other two linkers, and this led to higher current densities for the carboxylate DSSC. On the other hand, the carboxylate-linked dyes were readily leached from the metal oxide surface under alkaline conditions. The phosphonates were considerably less labile, and the siloxy-linked porphyrins were most resistant to leaching from the surface. The use of silatrane proved to be a practical and convenient way to introduce the siloxy linkages, which can confer greatly increased stability on dye-sensitized electrodes with photoelectrochemical performance comparable to that of the other linkers. PMID:23959453

  16. The synthesis of 13alpha-androsta-5,16-diene derivatives with carboxylic acid, ester and carboxamido functionalities at position-17 via palladium-catalyzed carbonylation.

    PubMed

    Acs, Péter; Takács, Attila; Szilágyi, Antal; Wölfling, János; Schneider, Gyula; Kollár, László

    2009-01-01

    17-Alkoxycarbonyl- and 17-carboxamido-3beta-hydroxy-13alpha-androsta-5,16-diene derivatives were synthetized in high yields in the palladium-catalyzed carbonylation reactions of the corresponding 3beta-hydroxy-17-iodo-13alpha-androsta-5,16-diene. This substrate with a 17-iodo-16-ene functionality was obtained from the 17-keto derivative via its 17-hydrazone, which was treated with iodine in the presence of a base (1,1,3,3-tetramethylguanidine). 17-Carboxamides were obtained by chemoselective aminocarbonylation through the use of amines, including amino acid esters, as N-nucleophiles. The 17-methoxycarbonyl-16-ene derivative was synthetized by using methanol as O-nucleophile. The parent compound of this series, the 17-carboxylic acid derivative, was formed in the presence of water via hydroxycarbonylation. PMID:19152802

  17. Alpha-hydroxyacids and carboxylic acids.

    PubMed

    Yu, Ruey J; Van Scott, Eugene J

    2004-04-01

    The carboxylic acids include alpha-hydroxyacids (AHAs), polyhydroxy acids (PHAs), aldobionic acids (ABAs), retinoic acid, vitamin C and azelaic acid. They all have therapeutic actions. AHAs, PHAs and ABAs are organic hydroxyacids, a group of natural and physiological substances which can modulate skin keratinization and increase biosynthesis of dermal components. Because of these effects, AHAs, PHAs and ABAs are therapeutically effective or beneficial for topical treatment of dry skin, rough skin, acne, rosacea, warts, eczema, psoriasis and skin changes associated with ageing, including wrinkles and photoageing. In addition, PHAs and ABAs, which are antioxidants, are topically beneficial for sensitive or diseased skin and for the prevention of oxidative damage caused by UV radiation. The vitamin A derivatives, known as retinoids, include three that are found physiologically. Retinoic acid is the most potent of these in promoting proliferation and differentiation of epithelial cells, and in stimulating biosynthesis of collagen I and III. Because of these actions, retinoic acid is therapeutically effective for topical treatment of acne, actinic keratoses and photoaged skin. Vitamin C, which is l-ascorbic acid and a lactone form of 3-keto-polyhydroxy acid, is a water-soluble antioxidant. Because of this property vitamin C has been promoted for topical prevention of skin damage caused by UV radiation. Azelaic acid has been shown to normalize keratinization in the follicular infundibulum, exert an antibacterial effect against Propionibacterium acnes and inhibit melanogenesis and so has been used for topical treatment of acne and melasma. The carboxylic acids display similarities and differences in their topical actions and therapeutic applications. PMID:17147560

  18. Conversion of carboxylate salts to carboxylic acids via reactive distillation 

    E-print Network

    Williamson, Shelly Ann

    2000-01-01

    , municipal solid wastes, sewage sludge, and industrial biosludge. Using a proprietary technology owned by Texas A&M University the wastes are first treated with lime to enhance reactivity. Then they are converted to calcium carboxylate salts using a mixed...

  19. Carboxylic Acid catalyzed hydration of acetaldehyde.

    PubMed

    Rypkema, Heather A; Sinha, Amitabha; Francisco, Joseph S

    2015-05-14

    Electronic structure calculations of the pertinent stationary points on the potential energy surface show that carboxylic acids can act effectively as catalysts in the hydration of acetaldehyde. Barriers to this catalyzed process correlate strongly with the pKa of the acid, providing the potential to provide the predictive capacity of the effectiveness of carboxylic acid catalysts. Transition states for the acid-catalyzed systems take the form of pseudo-six-membered rings through the linear nature of their hydrogen bonds, which accounts for their relative stability compared to the more strained direct and water-catalyzed systems. When considered as a stepwise reaction of a dimerization followed by reaction/complexation, it is likely that collisional stabilization of the prereactive complex is more likely than reaction in the free gas phase, although the catalyzed hydration does retain the potential to proceed on water surfaces or in droplets. Lastly, it is observed that postreactive diol-acid complexes are significantly stable (?12-17 kcal/mol) relative to isolated products, suggesting the possibility of long-lived hygroscopic species that could act as a seed molecule for condensation of secondary organic aerosols. PMID:25734508

  20. 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 our efforts to develop highly sensitive LC-MS methods for the analysis of chiral carboxylic acids including hydroxy acids.

  1. Structural and biochemical study on the inhibitory activity of derivatives of 5-nitro-furan-2-carboxylic acid for RNase H function of HIV-1 reverse transcriptase.

    PubMed

    Yanagita, Hiroshi; Urano, Emiko; Matsumoto, Kishow; Ichikawa, Reiko; Takaesu, Yoshihisa; Ogata, Masakazu; Murakami, Tsutomu; Wu, Hongui; Chiba, Joe; Komano, Jun; Hoshino, Tyuji

    2011-01-15

    Rapid emergence of drug-resistant variants is one of the most serious problems in chemotherapy for HIV-1 infectious diseases. Inhibitors acting on a target not addressed by approved drugs are of great importance to suppress drug-resistant viruses. HIV-1 reverse transcriptase has two enzymatic functions, DNA polymerase and RNase H activities. The RNase H activity is an attractive target for a new class of antiviral drugs. On the basis of the hit chemicals found in our previous screening with 20,000 small molecular-weight compounds, we synthesized derivatives of 5-nitro-furan-2-carboxylic acid. Inhibition of RNase H enzymatic activity was measured in a biochemical assay with real-time monitoring of florescence emission from the digested RNA substrate. Several derivatives showed higher inhibitory activities that those of the hit chemicals. Modulation of the 5-nitro-furan-2-carboxylic moiety resulted in a drastic decrease in inhibitory potency. In contrast, many derivatives with modulation of other parts retained inhibitory activities to varying degrees. These findings suggest the binding mode of active derivatives, in which three oxygen atoms aligned in a straight form at the nitro-furan moiety are coordinated to two divalent metal ions located at RNase H reaction site. Hence, the nitro-furan-carboxylic moiety is one of the critical scaffolds for RNase H inhibition. Of note, the RNase H inhibitory potency of a derivative was improved by 18-fold compared with that of the original hit compound, and no significant cytotoxicity was observed for most of the derivatives showing inhibitory activity. Since there is still much room for modification of the compounds at the part opposite the nitro-furan moiety, further chemical conversion will lead to improvement of compound potency and specificity. PMID:21193314

  2. MULTIVALENT CARBOXYLIC ACIDS TO MODIFY THE PROPERTIES OF ZEIN

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Carboxylic acids having more than one carboxylic acid moiety have been evaluated in zein melt formulations produced in a torque rheometer. These reagents are effective plasticizers for zein, lowering zein viscosity and delaying the onset of rapid viscosity increase. These reagents have been shown ...

  3. 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.

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

    DOEpatents

    Gogate, Makarand Ratnakar (Durham, NC); Spivey, James Jerry (Cary, NC); Zoeller, Joseph Robert (Kingsport, TN)

    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.

  5. 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...

  6. 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.

  7. Bis(?-2?-carboxyl­atobiphenyl-2-carboxylic acid-?2 O 2:O 2?)bis­[(2,2?-bipyridine-?2 N,N?)(2?-carboxyl­ato­biphenyl-2-carboxylic acid-?O 2?)zinc(II)

    PubMed Central

    An, Zhe

    2009-01-01

    In the dimeric title compound, [Zn2(C14H9O4)4(C10H8N2)2], the ZnII ions are penta­coordinated by one 2,2?-bipyridyl ligand and by three O atoms from three 2?-carboxyl­atobiphenyl-2-carboxylic acid ligands. Two of the 2?-carboxyl­atobiphenyl-2-carboxylic acid ligands act as bridging ligands and, together with two zinc(II) cations, produce an 18-membered ring system. The remaining 2?-carboxyl­atobiphenyl-2-carboxylic acid ligands work as monodentate ligands. The crystal packing diagram is consolidated by O—H?O hydrogen bonds. PMID:21578552

  8. Phytotoxicity of low-weight carboxylic acids.

    PubMed

    Himanen, Marina; Prochazka, Petr; Hänninen, Kari; Oikari, Aimo

    2012-07-01

    Presence of low-weight carboxylic acids (LWCAs) can be the reason for phytotoxicity of green manures, treated bio-waste or digestates from biogas production applied to soils. As the phytotoxic concentrations of LWCA are poorly known, this work presents data on six acids (C(1)C(6): formic, acetic, propionic, butyric, valeric, and caproic). Phytotoxicity was measured in acute (72 or 120 h) and subchronic (21 d) assays for seed germination, seedling elongation, and plant growth for garden cress Lepidium sativum and ryegrass Lolium multiflorum. The dose-response relationship was modeled using Weibull model. Results showed a trend that toxicity of LWCA increases with the length of the carbon chain, formic acid (C(1)) being the least and caproic acid (C(6)) the most toxic. EC50 values in the acute seed germination of cress ranged between 1.9 and 4.2mM and for ryegrass between 1.8 and 6.4mM. In subchronic assays EC50 values for germination were in a range from 11 to 46mMkg(-1)dm for cress, and from 18 to 127 mM kg(-1) dm for ryegrass. EC50 values for early seedling growth of cress based on acute assays ranged from 0.7 to 2.3mM and that of ryegrass from 1.2 to 1.8mM. Range of EC50 values for shoot biomass of cress was between 8 and 40 mM kg(-1) dm and of ryegrass between 12 and 93 mM kg(-1) dm. PMID:22440635

  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. 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 (Cary, NC); Gogate, Makarand Ratnakav (Durham, NC); Zoeller, Joseph Robert (Kingsport, TN); Tustin, Gerald Charles (Kingsport, TN)

    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. Microtribological properties of molecularly thin carboxylic acid functionalized imidazolium ionic liquid film on single-crystal silicon

    Microsoft Academic Search

    Yufei Mo; B. Yu; Wenjie Zhao; Mingwu Bai

    2008-01-01

    A series of 1-alkyl-3-ethylcarboxylic acid imidazolium chloride ([AEImi][Cl]) ionic liquids was synthesized and evaluated as a new kind of lubricant for microelectromechanical system (MEMS). In this research, novel molecular thin ionic liquid films (ILs) with various bonding percentages were prepared with different annealing temperatures and times. Film wettability was determined by measurement of contact angle and thickness with the ellipsometric

  13. Amine-based systems for carboxylic acid recovery

    SciTech Connect

    King, C.J.

    1992-05-01

    Several carboxylic acids are prominent commercial products, and their number and importance will probably grow. Getting these acids out of aqueous solution is necessary in petrochemical manufacture, fermentation, and the environmentally and economically important recovery from waste streams. In this paper, the authors discuss the methods possible to extract acids such as citric, lactic, and succinic from complex mixtures. Carboxylic acids are also readily made by fermentation and are among the most attractive substances that could be manufactured from biomass. Branches of this cycle lead to acetic, lactic, propionic, and formic acids, among others. Carboxylic acids are promising intermediates in a bioprocessing complex, because the oxygen of the biomass is placed in a form that is useful for further reaction with many other products. Citric acid is manufactured on a large scale by fermentation, and lactic and fumaric acids, among others, were manufactured that way in the past.

  14. 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...

  15. Conversion of sugarcane bagasse to carboxylic acids under thermophilic conditions

    E-print Network

    Fu, Zhihong

    2009-05-15

    3-6 The total carboxylic acid changed with time for paper fermentations under thermophilic conditions????????????????.. 61 3-7 pH profiles for paper fermentations under thermophilic conditions?? 61 3-8 Acetate content profile for carboxylic acids... changed with time for hot-lime- water-treated bagasse fermentations under thermophilic conditions?.???????????????????..???.. 66 3-11 pH profiles for hot-lime-water-treated bagasse fermentations under thermophilic conditions??.??????????..?????? 68 4...

  16. 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.

  17. Corrosion inhibition of steel in concrete by carboxylic acids

    Microsoft Academic Search

    K. K. Sagoe-Crentsil; F. P. Glasser; V. T. Yilmaz

    1993-01-01

    Water soluble carboxylic acids have been used as corrosion inhibitors. They remain largely soluble after curing in cement for up to 90d. Corrosion current measurements are presented showing malonic acid, a dicarboxylic acid, to be a very effective corrosion inhibitor even in the presence of 2.5 wt % chloride. Unfortunately, it has an initial retarding effect on the set of

  18. Solvent extraction of rare-earth metals by carboxylic acids

    SciTech Connect

    Preez, A.C. du; Preston, J.S. [Mintek, Randburg (South Africa)

    1992-04-01

    The solvent extraction of the trivalent lanthanides and yttrium from nitrate media by solutions of carboxylic acids in xylene has been studied. Commercially available carboxylic acids such as Versatic 10 and naphthenic acids were used, as well as model compounds of known structure, such as 2-ethylhexanoic and 3-cyclohexylpropanoic acids. In a few cases, extraction of the metals from sulphate and chloride solutions was also investigated. The dependence of the extraction properties of the carboxylic acids on the atomic number of the lanthanide shows a definite relationship to the steric bulk of the carboxylic acid molecule quantified by means of the steric parameter, E{sub s}{prime} of the substituent alkyl group. The stoichiometries of the extracted complexes for representative light (La), middle (Gd) and heavy (Lu) rare-earth metals were investigated by the slope-analysis technique for a sterically hindered acid (Versatic 10 acid; -E{prime}{sub s} = 3.83) and an acid with low steric hindrance (3-cyclohexylpropanoic acid; -E{prime}{sub s} = 0.28). 14 refs., 13 figs., 3 tabs.

  19. Carboxylic acid functionalization prevents the translocation of multi-walled carbon nanotubes at predicted environmentally relevant concentrations into targeted organs of nematode Caenorhabditis elegans

    NASA Astrophysics Data System (ADS)

    Nouara, Abdelli; Wu, Qiuli; Li, Yinxia; Tang, Meng; Wang, Haifang; Zhao, Yuliang; Wang, Dayong

    2013-06-01

    Carboxyl (-COOH) surface modified multi-walled carbon nanotubes (MWCNTs-COOH) can be used for targeted delivery of drugs and imaging. However, whether MWCNTs-COOH at environmentally relevant concentrations exert certain toxic effects on multicellular organisms and the underlying mechanisms are still largely unclear. In the present study, we applied the nematode Caenorhabditis elegans to evaluate the properties of MWCNTs-COOH at environmentally relevant concentrations by comparing the effects of MWCNTs and MWCNTs-COOH exposure on C. elegans from L1-larvae to adult at concentrations of 0.001-1000 ?g L-1. Exposure to MWCNTs could potentially damage the intestine (primary targeted organ) at concentrations greater than 0.1 ?g L-1 and functions of neurons and reproductive organ (secondary targeted organs) at concentrations greater than 0.001 ?g L-1. Carboxyl modification prevented the toxicity of MWCNTs on the primary and the secondary targeted organs at concentrations less than 100 ?g L-1, suggesting that carboxyl modification can effectively prevent the adverse effects of MWCNTs at environmentally relevant concentrations. After exposure, MWCNTs-COOH (1 mg L-1) were translocated into the spermatheca and embryos in the body through the primary targeted organs. However, MWCNTs-COOH (10 ?g L-1) were not observed in spermatheca and embryos in the body of nematodes. Moreover, relatively high concentrations of MWCNTs-COOH exposed nematodes might have a hyper-permeable intestinal barrier, whereas MWCNTs-COOH at environmentally relevant concentrations effectively sustained the normally permeable state for the intestinal barrier. Therefore, we elucidated the cellular basis of carboxyl modification to prevent toxicity of MWCNTs at environmentally relevant concentrations. Our data highlights the key role of biological barriers in the primary targeted organs to block toxicity formation from MWCNTs, which will be useful for the design of effective prevention strategies against MWCNTs toxicity.Carboxyl (-COOH) surface modified multi-walled carbon nanotubes (MWCNTs-COOH) can be used for targeted delivery of drugs and imaging. However, whether MWCNTs-COOH at environmentally relevant concentrations exert certain toxic effects on multicellular organisms and the underlying mechanisms are still largely unclear. In the present study, we applied the nematode Caenorhabditis elegans to evaluate the properties of MWCNTs-COOH at environmentally relevant concentrations by comparing the effects of MWCNTs and MWCNTs-COOH exposure on C. elegans from L1-larvae to adult at concentrations of 0.001-1000 ?g L-1. Exposure to MWCNTs could potentially damage the intestine (primary targeted organ) at concentrations greater than 0.1 ?g L-1 and functions of neurons and reproductive organ (secondary targeted organs) at concentrations greater than 0.001 ?g L-1. Carboxyl modification prevented the toxicity of MWCNTs on the primary and the secondary targeted organs at concentrations less than 100 ?g L-1, suggesting that carboxyl modification can effectively prevent the adverse effects of MWCNTs at environmentally relevant concentrations. After exposure, MWCNTs-COOH (1 mg L-1) were translocated into the spermatheca and embryos in the body through the primary targeted organs. However, MWCNTs-COOH (10 ?g L-1) were not observed in spermatheca and embryos in the body of nematodes. Moreover, relatively high concentrations of MWCNTs-COOH exposed nematodes might have a hyper-permeable intestinal barrier, whereas MWCNTs-COOH at environmentally relevant concentrations effectively sustained the normally permeable state for the intestinal barrier. Therefore, we elucidated the cellular basis of carboxyl modification to prevent toxicity of MWCNTs at environmentally relevant concentrations. Our data highlights the key role of biological barriers in the primary targeted organs to block toxicity formation from MWCNTs, which will be useful for the design of effective prevention strategies against MWCNTs toxicity. Electronic supplementary information (ESI) available. See DOI: 10

  20. On the chemical reaction between carboxylic acids and iron, including the special case of naphthenic acid

    Microsoft Academic Search

    Omar Yépez

    2007-01-01

    The reaction between different carboxylic acids and iron was performed by monitoring the amount of iron dissolved in oil through the formation of the iron carboxylate and by the product distribution in the gas phase. It was found that the solubility of the given iron carboxylate strongly influences the concentration of iron dissolved in oil. At temperatures higher than 300°C,

  1. 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...

  2. 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…

  3. Pretreatment and Fermentation of Sugarcane Trash to Carboxylic Acids

    E-print Network

    Nachiappan, Balasubraman

    2010-01-14

    produced 19.7 g/L of carboxylic acids. Sugarcane trash had the highest average yield (0.31 g total acid/g VS fed) and highest average conversion (0.70 g VS digested/g VS fed) among the three substrates compared. Countercurrent fermentations were performed...

  4. A Caffeoylcyclohexane-1Carboxylic Acid Derivative From Asimina Triloba

    Microsoft Academic Search

    Meena Haribal; Paul Feeny; Cathy C Lester

    1998-01-01

    Three caffeoyl derivatives of 1,3,4,5-tetrahydroxycyclohexane 1-carboxylic acid, one of them an oviposition stimulant for the zebra swallowtail butterfly, Eurytides marcellus, were isolated from Asimina triloba. The structure of the active isomer, 3-caffeoyl-muco-quinic acid, was determined by extensive NMR studies.

  5. Sensing of enantiomeric excess in chiral carboxylic acids.

    PubMed

    Akdeniz, Ali; Mosca, Lorenzo; Minami, Tsuyoshi; Anzenbacher, Pavel

    2015-04-01

    Cinchona alkaloids (quinine, quinidine, cinchonine, cinchonidine) alkylated at N(1) with chloromethyl anthracene can serve as fluorescent sensors for chiral carboxylic acids. These cinchona ammonium salts are shown to bind chiral carboxylic acids while displaying an increase in fluorescence intensity that can be utilized in determination of enantiomeric excess (ee). Sensor arrays composed of four cinchona ammonium salts are used for quantitative analysis of ee in several non-steroidal anti-inflammatory drugs (NSAIDs), such as enantiomers of ibuprofen, ketoprofen, and naproxen. PMID:25720499

  6. 1H-Azepine-2-oxo-5-amino-5-carboxylic Acid: A 310 Helix Inducer and an Effective Tool for Functionalized Gold Nanoparticles.

    PubMed

    Pellegrino, Sara; Bonetti, Andrea; Clerici, Francesca; Contini, Alessandro; Moretto, Alessandro; Soave, Raffaella; Gelmi, Maria Luisa

    2015-06-01

    A new ?,?-disubstituted constrained glutamine analogue has been designed to decorate gold nanoparticles and to induce a 310-helix when inserted in peptides. Using an efficient "one-pot" asymmetric Schmidt reaction between 4-disubstituted-cyclohexanone and hydroxyalkylazides, 1H-azepine-2-oxo-5-amino-5-carboxylic acid was prepared. The main (R) isomer was inserted at the N-terminus in a very short peptide sequence (i.e., PhCO-(R)-Oxo-Azn-l-Ala-Aib-l-AlaNHMe) and a stable 310-helix conformation was obtained, as verified by both NMR experiments and molecular dynamics (MD) simulations. Finally, the presence of the hydroxyl chain at the nitrogen atom of the ring allowed for the preparation of covered chiral gold nanoparticles. PMID:25938852

  7. Enantioselective synthesis of ?-hydroxy carboxylic acids: direct conversion of ?-oxocarboxylic acids to enantiomerically enriched ?-hydroxy carboxylic acids via neighboring group control

    Microsoft Academic Search

    Zhe Wang; Chunlin Zhao; Michael E. Pierce; Joseph M. Fortunak

    1999-01-01

    ?-Oxocarboxylic acids can be reduced to the corresponding ?-hydroxy carboxylic acids employing DIP-Cl™ as a reducing agent. The ?-carboxylic substituent exerts a remarkable neighboring group effect on the reduction. The reaction presumably proceeds in an intramolecular fashion through a `rigid' bicyclic transition state assembly, which produces enantioselectivities approaching 99%.

  8. Carboxylic Acids as Indicators of Parent Body Conditions

    NASA Astrophysics Data System (ADS)

    Lerner, N. R.

    1995-09-01

    Alpha-hydroxy and alpha-amino carboxylic acids found on the Murchison meteorite are deuterium enriched [1]. It is postulated that they arose from a common interstellar source: the reaction of carbonyl compounds in an aqueous mixture containing HCN and NH3. Carbonyl compounds react with HCN to form alph-hydroxy nitriles, RR'CO + HCN <--> RR'C(OH)CN. If ammonia is also present, the alpha-hydroxy nitriles will exist in equilibirum with the alpha-amino nitriles, RR'C(OH)CN +NH3 .<--> RRCNH2CN + H2O. Both nitriles are hydrolyzed by water to form carboxylic acids: RR'C(OH)CN + H2O --> RR'C(OH)CO2H and RR'C(NH2)CN + H2O --> RR'C(NH2)CO2H. Carbonyl compounds observed in the interstellar medium have been shown to be deuterium enriched [2]. The combined alpha-amino acids found on Murchison have deltaD = +1751 o/oo while the combined alpha-hydroxy acids have deltaD = +573. o/oo [1]. This large discrepancy in deltaD values does not preclude common precursors for the alpha-amino acids and the alpha-hydroxy acids. Different relative amounts of specific alpha-amino and alpha-hydroxy acids could lead to quite different combined D/H ratios. If the alpha-hydroxy acids lose significantly more deuterium during synthesis than the alpha-amino acids or if they have a higher rate of H/D exchange with liquid water than alpha-amino acids, the alpha-hydroxy acids would be isotopically lighter than the alpha-amino acids, because the water responsible for the aqueous alteration of the Murchison parent body was deuterium depleted with deltaD = -100. o/oo [3]. To determine between these alternative mechanisms we measured the rates of hydrogen-deuterium exchange of glycolic acid (the alpha-hydroxy analog of glycine), lactic acid (the alpha-hydroxy analog of alanine), and alpha-hydroxy isobutyric acid have been measured in D2O as a function of pH, temperature and the presence of Allende or Murchison minerals. No detectable H/D exchange was observed. Glycine subjected to similar conditons exchanged as much as 80% of its carbon-bonded deuterium, and alanine 43% [4]. Evidently, the relative deuterium content of the alpha-amino acids and alpha-hydroxy acids found on the Murchison meteorite was not determined by H/D exchange with water. In order to determine if deuterium retention is less for alpha-hydroxy acids than it is for alpha-amino carboxylic acids during synthesis a solution was prepared containing: KCN, 0.005M; NH4Cl, 0.002 M; CD2O, 0.0007M; CD3CDO, 0.0008 M; and (CD3)2CO 0.0006 M, and divided into aliquots which were maintained at 263 K and at 295 K. At the end of one month the carbonyls, alpha-amino acids and alpha-hydroxy acids were separated from the mixture and their deuterium content determined from their mass spectra (see Table 1). The retention of deuterium during synthesis varies significantly between the alpha-hydroxy acids and the alpha-amino acids with common precursors. Only comparisons of D/H ratios of specific acids with a postulated common precursor are meaningful. References: [1] Cronin J. R. et al. (1993) GCA, 57, 4745-4752. [2] Zinner E. (1988) in Meteorites and the Early Solar System (J. R. Kerridge and M. S. Matthews, eds.), 956-983, Univ. of Arizona. [3] Robert F. and Epstein S. (1982) GCA, 46, 81-95. [4] Lerner N. R. (1995) GCA, 59, 1623-1631. Table 1 shows D/(D+H) of carbon-bonded hydrogen in compounds separated after one month from a simulated meteorite solution.

  9. More on Effects Controlling Carboxylic Acidity.

    ERIC Educational Resources Information Center

    Schwartz, Lowell M.

    1981-01-01

    Gas phase acidity data shown are offered to writers of elementary organic chemistry texts for replacement of the aqueous phase data that are universally used. Relative acidities in the gas phase are controlled virtually exclusively by enthalpic factors. Structural-energetic explanations of acidic trends can therefore be used. (SK)

  10. 40 CFR 721.10381 - Cyclic carboxylic acid, polymer with dihydroxy dialkyl ether, hydroxy substituted alkane and...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 false Cyclic carboxylic acid, polymer with dihydroxy dialkyl ether, hydroxy substituted alkane and carboxylic acid anhydride, methacrylate terminated polyester...Substances § 721.10381 Cyclic carboxylic acid, polymer with dihydroxy dialkyl...

  11. 40 CFR 721.10381 - Cyclic carboxylic acid, polymer with dihydroxy dialkyl ether, hydroxy substituted alkane and...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 false Cyclic carboxylic acid, polymer with dihydroxy dialkyl ether, hydroxy substituted alkane and carboxylic acid anhydride, methacrylate terminated polyester...Substances § 721.10381 Cyclic carboxylic acid, polymer with dihydroxy dialkyl...

  12. 40 CFR 721.10381 - Cyclic carboxylic acid, polymer with dihydroxy dialkyl ether, hydroxy substituted alkane and...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 false Cyclic carboxylic acid, polymer with dihydroxy dialkyl ether, hydroxy substituted alkane and carboxylic acid anhydride, methacrylate terminated polyester...Substances § 721.10381 Cyclic carboxylic acid, polymer with dihydroxy dialkyl...

  13. Synthesis and hypoglycemic evaluation of substituted pyrazole-4-carboxylic acids

    Microsoft Academic Search

    Bertrand Cottineau; Patrick Toto; Christophe Marot; Aline Pipaud; Jacques Chenault

    2002-01-01

    The synthesis and in vivo activities of a series of substituted pyrazole-4-carboxylic acids as hypoglycemic agents are described. Modelization of some potent compounds, comparatively to the metformine, presents certain analogies permitting to predict the design of some novel antidiabetic drugs.

  14. Structural determination of the carboxylic acid metabolites of polychlorotrifluoroethylene.

    PubMed

    Brashear, W T; Greene, R J; Mahle, D A

    1992-05-01

    1. Polychlorotrifluoroethylene (PCTFE) is a perhalogenated hydrocarbon which consists mainly of C-6 and C-8 oligomers of chlorotrifluoroethylene (CTFE) end-capped with chlorine and referred to as trimer and tetramer, respectively. PCTFE is a hydraulic fluid considered for use in advanced weapon systems. 2. Inhalation studies have shown that PCTFE causes a dose-related hepatotoxicity in rats that is accompanied by proliferation of hepatic peroxisomes and increased liver weight. 3. Carboxylic acid metabolites of PCTFE have been isolated from rats exposed to PCTFE via inhalation. These metabolites, or their formation, may be involved in the toxicity of PCTFE. 4. Trimer carboxylic acids have been isolated from rat urine and identified, and tetramer carboxylic acids have been isolated from rat liver, and identified. 5. Our investigation of trimer and tetramer carboxylic acid metabolites of PCTFE has shown that the terminal carbon bearing two chlorine atoms is the exclusive site of oxidation. No evidence was found indicating oxidation of terminal carbon atoms having one chlorine. PMID:1413865

  15. Pilot-scale fermentation of office paper and chicken manure to carboxylic acids 

    E-print Network

    Moody, Andrew Garret

    2006-08-16

    ). Methane Inhibition Carboxylic acids are only one of the products of the anaerobic fermentation of biomass; methane is also produced by methanogenesis. To prevent carboxylic acid loss to methane, a methanogen inhibitor is required. Ross (1998) found...

  16. Phase behavior of methane with carboxylic acids

    SciTech Connect

    Der Shin Shy; Jun Shun Yau; Fuan Nan Tsai (National Cheng Kung Univ., Tainan (Taiwan, Province of China). Dept. of Chemical Engineering)

    1993-01-01

    Vapor-liquid equilibria for the binary mixtures methane + dodecanoic acid, methane + hexadecanoic acid, and methane + eicosanoic acid have been measured in a semiflow apparatus under the temperatures ranging from 373.2 to 473.2 K at pressures up to 5.07 MPa. A correlation is developed to describe the results and to calculate the gas solubilities of these systems. Henry's constants and the partial molar volumes at infinite dilution of methane are evaluated from gas solubilities.

  17. Palladium-catalyzed regioselective decarboxylative alkylation of arenes and heteroarenes with aliphatic carboxylic acids.

    PubMed

    Premi, Chanchal; Dixit, Ankit; Jain, Nidhi

    2015-06-01

    An unprecedented Pd(OAc)2-catalyzed decarboxylative alkylation of unactivated arenes, with aliphatic carboxylic acids as inexpensive alkyl sources, is reported. The alkylation, controlled by the directing group, is regioselective, shows high functional group tolerance, and provides mild access to alkylated indolines, 2-phenylpyridines, and azobenzenes under solvent-free conditions in moderate to high yields. PMID:25997514

  18. Study of quantitative structure–mobility relationship of carboxylic and sulphonic acids in capillary electrophoresis

    Microsoft Academic Search

    Chunxia Xue; Huanxiang Liu; Xiaojun Yao; Mancang Liu; Zhide Hu; Botao Fan

    2004-01-01

    A quantitative structure–mobility relationship (QSMR) was developed for the absolute mobilities of 115 carboxylic and sulphonic acids in capillary electrophoresis based on the descriptors calculated from the structure alone. The heuristic method (HM) and radial basis function neural networks (RBFNN) were utilized to construct the linear and nonlinear prediction models, respectively. The prediction results were in agreement with the experimental

  19. Bimolecular decomposition pathways for carboxylic acids of relevance to biofuels.

    PubMed

    Clark, Jared M; Nimlos, Mark R; Robichaud, David J

    2015-01-22

    The bimolecular thermal reactions of carboxylic acids were studied using quantum mechanical molecular modeling. Previous work1 investigated the unimolecular decomposition of a variety of organic acids, including saturated, ?,?-unsaturated, and ?,?-unsaturated acids, and showed that the type and position of the unsaturation resulted in unique branching ratios between dehydration and decarboxylation, [H2O]/[CO2]. In this work, the effect of bimolecular chemistry (water-acid and acid-acid) is considered with a representative of each acid class. In both cases, the strained 4-centered, unimolecular transition state, typical of most organic acids, is opened up to 6- or 8-centered bimolecular geometries. These larger structures lead to a reduction in the barrier heights (20-45%) of the thermal decomposition pathways for organic acids and an increase in the decomposition kinetics. In some cases, they even cause a shift in the branching ratio of the corresponding product slates. PMID:25513721

  20. 40 CFR 721.10550 - Rare earth salt of a carboxylic acid (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 2014-07-01 false Rare earth salt of a carboxylic acid (generic...Chemical Substances § 721.10550 Rare earth salt of a carboxylic acid (generic...substance identified generically as rare earth salt of a carboxylic acid (PMN...

  1. 40 CFR 721.10550 - Rare earth salt of a carboxylic acid (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 2013-07-01 false Rare earth salt of a carboxylic acid (generic...Chemical Substances § 721.10550 Rare earth salt of a carboxylic acid (generic...substance identified generically as rare earth salt of a carboxylic acid (PMN...

  2. Group composition of carboxylic acids from West Siberian crude oils

    SciTech Connect

    Zhic'tsov, N.I.; Ershov, V.A.; Samokhvalova, G.I.

    1982-11-01

    Performs mass spectrometric analyses of carboxylic acids from crudes of different geologic ages using an MAT 111 chromatograph/mass spectrometer equipped with systems for direct sample introduction and temperature programming. Explains that as an analytical characteristic for determination of the group composition and molecular weight distribution of the carboxylic, the relative intensities of peaks of the ions (M-15)/sup +/ were selected in the mass spectra of their trimethylsilyl esters (TMSES), obtained at different temperatures of the sample in the ion source. Concludes that the results from an analysis of the group composition of the carboxylic acids in crude oils from 10 deposits of various geological ages indicate that as the metamorphism factor increases, there is a decrease in the content of naphthenic acids in the acid concentrates from the crudes. Offers the possibility that for higher reservoir temperatures and greater depths of occurrence of the oil-enclosing rock, the reducing factor dominates over the oxidizing factor in making up the composition of the petroleum acids.

  3. 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

  4. Extraction chemistry of fermentation product carboxylic acids

    Microsoft Academic Search

    A. S. Kertes; C. J. King

    1986-01-01

    Within the framework of a program aiming to improve the existing extractive recovery technology of fermentation products, the state of the art is critically reviewed. The acids under consideration are propionic, lactic, pyruvic, succinic, fumaric, maleic, malic, itaconic, tartaric, citric, and isocitric, all obtained by the aerobic fermentation of glucose via the glycolytic pathways and glyoxylate bypass. With no exception,

  5. Pear ACO genes encoding putative 1-aminocyclopropane-1-carboxylate oxidase homologs are functionally expressed during fruit ripening and involved in response to salicylic acid.

    PubMed

    Shi, Hai-Yan; Zhang, Yu-Xing

    2012-10-01

    1-Aminocyclopropane-1-carboxylate (ACC) oxidase catalyzes the final reaction of the ethylene biosynthetic pathway, converting ACC into ethylene. Past studies have shown a possible link between ACC oxidase and salicylic acid during fruit ripening in pear, but the relationship has received no more than modest study at the gene expression level. In this study, two cDNA clones encoding putative ACC oxidase, PpACO1 and PpACO2, were isolated from a cDNA library constructed by our own laboratory and produced using mRNA from mesocarp of pear (Pyrus pyrifolia Nakai. cv.Whangkeumbae). One cDNA clone, designated PpACO1 (GenBank accession No. JN807390), comprised an open reading frame of 945 bp encoding a protein of 314 amino acids. The other cDNA, designated PpACO2 (GenBank accession No. JN807392), encodes a protein with 322 amino acids that shares high similarity with the known plant ACOs. Using PCR amplification techniques, two genomic clones corresponding to PpACO1 and PpACO2 were isolated and shown to contain independently three introns with typical GT/AG boundaries defining the splice junctions. The PpACO1 gene product shared 99 % identity with an ACC oxidase from pear (Pyrus × bretschneideri Rehd.cv.Yali), and phylogenetic analyses clearly placed the gene product in the ACC oxidase cluster of the pear 2-oxoglutarate-dependent dioxygenase superfamily tree. Quantitative RT-PCR analysis indicated that the two PpACO genes are differentially expressed in pear tissues. PpACO1 and PpACO2 were predominantly expressed in fruit. The transcripts of PpACO1 were accumulated at relatively low levels in early fruit, but strongly high levels in fruit ripening and senescence stages, while the transcripts of PpACO2 were accumulated at higher levels in early fruit and much lower levels with further fruit cell development than the transcripts of PpACO1. In addition, PpACO1 gene was down-regulated in fruit by salicylic acid (SA). Nevertheless, PpACO2 gene was dramatically up-regulated in fruit by SA. These results suggested that the PpACOs may participate in regulation of fruit ripening and in response to SA in pear. PMID:22711312

  6. 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.

  7. Polythermal solubility of fullerenes in higher isomeric carboxylic acids

    Microsoft Academic Search

    K. N. Semenov; O. V. Arapov; A. K. Pyartman; V. A. Keskinov; V. V. Lishchuk; N. A. Charykov; N. I. Alekseev

    2007-01-01

    The solubility of individual fullerenes C60 and C70 and a fullerene mixture enriched in higher fullerenes (C60 38.8, C70 33.0, C76–78 5.6, C84 8.6, C90 2.6, and C96 3.3%) in higher isomeric carboxylic acids was studied within the 20–80C temperature range; the corresponding solubility\\u000a polytherms are presented.

  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. Transcriptomic analysis of the role of carboxylic acids in metabolite signaling in Arabidopsis leaves.

    PubMed

    Finkemeier, Iris; König, Ann-Christine; Heard, William; Nunes-Nesi, Adriano; Pham, Phuong Anh; Leister, Dario; Fernie, Alisdair R; Sweetlove, Lee J

    2013-05-01

    The transcriptional response to metabolites is an important mechanism by which plants integrate information about cellular energy and nutrient status. Although some carboxylic acids have been implicated in the regulation of gene expression for select transcripts, it is unclear whether all carboxylic acids have the same effect, how many transcripts are affected, and how carboxylic acid signaling is integrated with other metabolite signals. In this study, we demonstrate that perturbations in cellular concentrations of citrate, and to a lesser extent malate, have a major impact on nucleus-encoded transcript abundance. Functional categories of transcripts that were targeted by both organic acids included photosynthesis, cell wall, biotic stress, and protein synthesis. Specific functional categories that were only regulated by citrate included tricarboxylic acid cycle, nitrogen metabolism, sulfur metabolism, and DNA synthesis. Further quantitative real-time polymerase chain reaction analysis of specific citrate-responsive transcripts demonstrated that the transcript response to citrate is time and concentration dependent and distinct from other organic acids and sugars. Feeding of isocitrate as well as the nonmetabolizable citrate analog tricarballylate revealed that the abundance of selected marker transcripts is responsive to citrate and not downstream metabolites. Interestingly, the transcriptome response to citrate feeding was most similar to those observed after biotic stress treatments and the gibberellin biosynthesis inhibitor paclobutrazol. Feeding of citrate to mutants with defects in plant hormone signaling pathways did not completely abolish the transcript response but hinted at a link with jasmonic acid and gibberellin signaling pathways. Our results suggest that changes in carboxylic acid abundances can be perceived and signaled in Arabidopsis (Arabidopsis thaliana) by as yet unknown signaling pathways. PMID:23487434

  10. THE SOLVENT EXTRACTION OF RARE-EARTH METALS BY CARBOXYLIC ACIDS

    Microsoft Academic Search

    A. C. du Preez; J. S. Preston

    1992-01-01

    The solvent extraction of the trivalent lanthanides and yttrium from nitrate media by solutions of carboxylic acids in xylene has been studied. Commercially available carboxylic acids such as Versatic 10 and naphthenic acids were used, as well as model compounds of known structure, such as 2-ethylhexanoic and 3-cyclohexylpropanoic acids. In a few cases, extraction of the metals from sulphate and

  11. Catalysis of the Carbonylation of Alcohols to Carboxylic Acids Including Acetic Acid Synthesis from Methanol.

    ERIC Educational Resources Information Center

    Forster, Denis; DeKleva, Thomas W.

    1986-01-01

    Monsanto's highly successful synthesis of acetic acid from methanol and carbon monoxide illustrates use of new starting materials to replace pretroleum-derived ethylene. Outlines the fundamental aspects of the acetic acid process and suggests ways of extending the synthesis to higher carboxylic acids. (JN)

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

    DOEpatents

    McDonald, William F. (Utica, OH); Huang, Zhi Heng (East Lansing, MI); Wright, Stacy C. (Lansing, MI); Danzig, Morris (Northbrook, IL); Taylor, Andrew C. (Ann Arbor, MI)

    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.

  13. Chemoselective Boron-Catalyzed Nucleophilic Activation of Carboxylic Acids for Mannich-Type Reactions.

    PubMed

    Morita, Yuya; Yamamoto, Tomohiro; Nagai, Hideoki; Shimizu, Yohei; Kanai, Motomu

    2015-06-10

    The carboxyl group (COOH) is an omnipresent functional group in organic molecules, and its direct catalytic activation represents an attractive synthetic method. Herein, we describe the first example of a direct catalytic nucleophilic activation of carboxylic acids with BH3·SMe2, after which the acids are able to act as carbon nucleophiles, i.e. enolates, in Mannich-type reactions. This reaction proceeds with a mild organic base (DBU) and exhibits high levels of functional group tolerance. The boron catalyst is highly chemoselective toward the COOH group, even in the presence of other carbonyl moieties, such as amides, esters, or ketones. Furthermore, this catalytic method can be extended to highly enantioselective Mannich-type reactions by using a (R)-3,3'-I2-BINOL-substituted boron catalyst. PMID:26011419

  14. Some biological properties of new quinoline-4-carboxylic acid and quinoline-4-carboxamide derivatives

    Microsoft Academic Search

    J. Strigá?ová; D. Hudecová; L'. Vare?ka; A. Lásiková; D. Végh

    2000-01-01

    The antimicrobial and morphogenetic effects of fourteen newly synthesized 2-substituted derivatives of quinoline-4-carboxylic\\u000a acid and quinoline-4-carboxamide were studied using G+ and G? bacteria, yeasts and filamentous fungi. The highest antimicrobial effects were found with substituted quinoline-4-carboxylic\\u000a acid derivatives. Quinoline-4-carboxamides only weakly influenced the growth of the tested microorganisms. Some derivatives\\u000a of quinoline-4-carboxylic acid elicited profound changes in the morphology of

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

    PubMed

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

    2015-12-01

    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 (??m) 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)-?B 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. PMID:26058514

  16. Study on Distribution and Composition of Carboxylic Acids of Bohai Crude Oil in China

    Microsoft Academic Search

    Bangfeng Qi; Xu Fei; Shaojun Wang; Liren Chen

    2004-01-01

    This study concerns the distribution, type, and structure of carboxylic acids in the 200–550°C distillates of Bohai crude oil. The acids, isolated by aqueous alcoholic sodium hydroxide, were converted into corresponding methyl esters with BF3 as a catalyst. The chemical structure of these carboxylic acids and distribution of their various components in different distillates were studied in detail by IR,

  17. Palladium-catalyzed decarboxylative coupling of quinolinone-3-carboxylic acids and related heterocyclic carboxylic acids with (hetero)aryl halides.

    PubMed

    Messaoudi, Samir; Brion, Jean-Daniel; Alami, Mouad

    2012-03-16

    An efficient and practical decarboxylative cross-coupling reaction of quinolin-4(1H)-one 3-carboxylic acids with (hetero)aryl halides has been established. Under a bimetallic system of PdBr(2) and silver carbonate, the protocol proved to be general, and a variety of 3-(hetero)aryl 4-quinolinones and related heterocycles, such as 3-aryl-1,8-naphthyridin-4(1H)-ones, 3-arylcoumarins, 3-arylquinolin-2(1H)-ones, and 2-arylchromones, can be prepared in good to excellent yields. PMID:22381127

  18. Titania-Promoted Carboxylic Acid Alkylations of Alkenes and Cascade Addition–Cyclizations

    PubMed Central

    2014-01-01

    Photochemical reactions employing TiO2 and carboxylic acids under dry anaerobic conditions led to several types of C–C bond-forming processes with electron-deficient alkenes. The efficiency of alkylation varied appreciably with substituents in the carboxylic acids. The reactions of aryloxyacetic acids with maleimides resulted in a cascade process in which a pyrrolochromene derivative accompanied the alkylated succinimide. The selectivity for one or other of these products could be tuned to some extent by employing the photoredox catalyst under different conditions. Aryloxyacetic acids adapted for intramolecular ring closures by inclusion of 2-alkenyl, 2-aryl, or 2-oximinyl functionality reacted rather poorly. Profiles of reactant consumption and product formation for these systems were obtained by an in situ NMR monitoring technique. An array of different catalyst forms were tested for efficiency and ease of use. The proposed mechanism, involving hole capture at the TiO2 surface by the carboxylates followed by CO2 loss, was supported by EPR spectroscopic evidence of the intermediates. Deuterium labeling indicated that the titania likely donates protons from surface hydroxyl groups as well as supplying electrons and holes, thus acting as both a catalyst and a reaction partner. PMID:24437519

  19. A role for coenzyme M (2-mercaptoethanesulfonic acid) in a bacterial pathway of aliphatic epoxide carboxylation

    PubMed Central

    Allen, Jeffrey R.; Clark, Daniel D.; Krum, Jonathan G.; Ensign, Scott A.

    1999-01-01

    The bacterial metabolism of short-chain aliphatic alkenes occurs via oxidation to epoxyalkanes followed by carboxylation to ?-ketoacids. Epoxyalkane carboxylation requires four enzymes (components I–IV), NADPH, NAD+, and a previously unidentified nucleophilic thiol. In the present work, coenzyme M (2-mercaptoethanesulfonic acid), a compound previously found only in the methanogenic Archaea where it serves as a methyl group carrier and activator, has been identified as the thiol and central cofactor of aliphatic epoxide carboxylation in the Gram-negative bacterium Xanthobacter strain Py2. Component I catalyzed the addition of coenzyme M to epoxypropane to form a ?-hydroxythioether, 2-(2-hydroxypropylthio)ethanesulfonate. Components III and IV catalyzed the NAD+-dependent stereoselective dehydrogenation of R- and S-enantiomers of 2-(2-hydroxypropylthio)ethanesulfonate to form 2-(2-ketopropylthio)ethanesulfonate. Component II catalyzed the NADPH-dependent cleavage and carboxylation of the ?-ketothioether to form acetoacetate and coenzyme M. These findings evince a newfound versatility for coenzyme M as a carrier and activator of alkyl groups longer in chain-length than methane, a function for coenzyme M in a catabolic pathway of hydrocarbon oxidation, and the presence of coenzyme M in the bacterial domain of the phylogenetic tree. These results serve to unify bacterial and Archaeal metabolism further and showcase diverse biological functions for an elegantly simple organic molecule. PMID:10411892

  20. Binding of carboxylic acids by fluorescent pyridyl ureas.

    PubMed

    Jordan, Lisa M; Boyle, Paul D; Sargent, Andrew L; Allen, William E

    2010-12-17

    Fluorescent pyrid-2-yl ureas were prepared by treating halogenated 2-aminopyridines with hexyl isocyanate, followed by Sonogashira coupling with arylacetylenes. The sensors emit light of ?360 nm with quantum yields of 0.05-0.1 in acetonitrile solution. Addition of strong organic acids (pK(a) < 13 in CH(3)CN) shifts the fluorescence band to lower energy, and clean isoemissive behavior is observed. Fluorescence response curves (i.e., F/F(0) vs [acid](total)) are hyperbolic in shape for CCl(3)COOH and CF(3)COOH, with association constants on the order of 10(3) M(-1) for both acids. (1)H NMR titrations and DFT analyses indicate that trihaloacetic acids bind in ionized form to the receptors. Pyridine protonation disrupts an intramolecular H-bond, thereby unfolding an array of ureido NH donors for recognition of the corresponding carboxylates. Methanesulfonic acid protonates the sensors, but no evidence for conjugate base binding at the urea moiety is found by NMR. An isosteric control compound that lacks an integrated pyridine does not undergo significant fluorescence changes upon acidification. PMID:21080667

  1. Influence of carboxylic-acid structure on the kinetics of electrode processes occurring during Kolbe electrosynthesis

    SciTech Connect

    Lotvin, B.M.; Vasil'ev, Yu.B.

    1987-02-01

    The influence of carboxylic-acid structure on the kinetics of electrode processes occurring during Kolbe electrosynthesis was studied, and shown to produce changes in the rates of destructive chemisorption and destructive oxidation of the carboxylic acid, in the competition for the platinum electrode surface between the solvent and the carboxylate anions at high anode potentials, and in the routes of radical reactions because of changes in the nature of the radical formed.

  2. Selenium Catalyzed Oxidation of Aldehydes: Green Synthesis of Carboxylic Acids and Esters.

    PubMed

    Sancineto, Luca; Tidei, Caterina; Bagnoli, Luana; Marini, Francesca; Lenardão, Eder J; Santi, Claudio

    2015-01-01

    The stoichiometric use of hydrogen peroxide in the presence of a selenium-containing catalyst in water is here reported as a new ecofriendly protocol for the synthesis of variously functionalized carboxylic acids and esters. The method affords the desired products in good to excellent yields under very mild conditions starting directly from commercially available aldehydes. Using benzaldehyde as a prototype the gram scale synthesis of benzoic acid is described, in which the aqueous medium and the catalyst could be recycled at last five times while achieving an 87% overall yield. PMID:26060915

  3. Regeneration of carboxylic acid-laden basic sorbents by leaching with a volatile base in an organic solvent

    DOEpatents

    King, C. Judson (Kensington, CA); Husson, Scott M. (Berkeley, CA)

    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.

  4. Photophysical properties of dysprosium complexes with aromatic carboxylic acids by molecular spectroscopy

    Microsoft Academic Search

    Bing Yan; Bing Zhou

    2005-01-01

    A series of luminescent dysprosium complexes with different aromatic carboxylic acids have been synthesized and characterized. The photophysical properties of these complexes have been studied with all kinds of molecular spectroscopy such as infrared spectra, ultraviolet spectra, phosphorescence spectra and fluorescence spectra. Especially the energy match and intramolecular energy transfer process between the triplet state energies of aromatic carboxylic acids

  5. Direct Condensation of Carboxylic Acids with Alcohols Catalyzed by Hafnium(IV) Salts

    Microsoft Academic Search

    Kazuaki Ishihara; Suguru Ohara; Hisashi Yamamoto

    2000-01-01

    In order to promote atom efficiency in synthesis and to avoid the generation of environmental waste, the use of stoichiometric amounts of condensing reagents or excess substrates should be avoided. In esterification, excesses of either carboxylic acids or alcohols are normally needed. We show that the direct condensation of equimolar amounts of carboxylic acids and alcohols can be achieved with

  6. Polyacetal Carboxylic Acids: a New Group of Antiviral Polyanions

    PubMed Central

    Claes, P.; Billiau, A.; De Clercq, E.; Desmyter, J.; Schonne, E.; Vanderhaeghe, H.; De Somer, P.

    1970-01-01

    Chlorite-oxidized oxypolysaccharides are polyacetal carboxylic acids. They inhibited the cytopathic effect of vesicular stomatitis virus in mouse embryo cell cultures challenged at low input multiplicity. After intraperitoneal injection of these compounds in mice, interferon appeared in the circulation. The compounds also protected mice against lethal mengovirus infection and against the development of experimental pox lesions on the tail. Chlorite-oxidized oxyamylose was antiviral only when at least 64% of the glucopyranose units were oxidized, an observation which suggested a correlation between charge density and antiviral effect. The antiviral activity was also influenced by the molecular weight, as demonstrated by the fact that chlorite-oxidized dextrans which had a high intrinsic viscosity were more active than those with low intrinsic viscosity. PMID:4314553

  7. 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...

  8. Density functional study of electronic, charge density, and chemical bonding properties of 9-methyl-3-Thiophen-2-YI-Thieno [3,2-e] [1, 2, 4] Thriazolo [4,3-c] pyrimidine-8-Carboxylic acid ethyl ester crystals

    NASA Astrophysics Data System (ADS)

    Reshak, A. H.; Kamarudin, H.; Alahmed, Z. A.; Auluck, S.; Chyský, Jan

    2014-06-01

    A comprehensive theoretical density functional investigation of the electronic crystal structure, chemical bonding, and the electron charge densities of 9-Methyl-3-Thiophen-2-YI-Thieno [3, 2-e] [1, 2, 4] Thriazolo [4,3-c] Pyrimidine-8-Carboxylic Acid Ethyl Ester (C15H12N4O2S2) is performed. The density of states at Fermi level equal to 5.50 (3.45) states/Ry cell, and the calculated bare electronic specific heat coefficient is found to be 0.95 (0.59) mJ/mole-K2 for the local density approximation (Engel-Vosko generalized gradient approximation). The electronic charge density space distribution contours in (1 0 0) and (1 1 0) planes were calculated. We find that there are two independent molecules (A and B) in the asymmetric unit exhibit intramolecular C-H…O, C-H…N interactions. This intramolecular interaction is different in molecules A and B, where A molecule show C-H…O interaction while B molecule exhibit C-H…N interaction. We should emphasis that there is ?-? interaction between the pyrimidine rings of the two neighbors B molecules gives extra strengths and stabilizations to the superamolecular structure. The calculated distance between the two neighbors pyrimidine rings found to be 3.345 Å, in good agreement with the measured one (3.424(1) Å).

  9. 4Hydroxy2-quinolones 142. 4Methyl2-oxo-1,2-dihydroquinoline-3-carboxylic acid anilides as potential diuretics

    Microsoft Academic Search

    I. V. Ukrainets; N. L. Bereznyakova; V. A. Parshikov; O. I. Naboka

    2008-01-01

    A large series of 4-methyl-2-oxo-1,2-dihydroquinoline-3-carboxylic acid anilides has been prepared as potential diuretic agents.\\u000a The effect of all of the synthesized compounds on the urinary function of the kidney has been investigated. The appearance\\u000a of a “structure — diuretic activity” relationship is discussed.

  10. Silver-mediated decarboxylative C-S cross-coupling of aliphatic carboxylic acids under mild conditions.

    PubMed

    Wang, Peng-Fei; Wang, Xiao-Qing; Dai, Jian-Jun; Feng, Yi-Si; Xu, Hua-Jian

    2014-09-01

    A silver-mediated decarboxylative C-S cross-coupling reaction of aliphatic carboxylic acid is described. This reaction occurs smoothly under mild conditions and shows good tolerance of functional groups. It provides an alternative approach for the synthesis of alkyl aryl sulfides. PMID:25153507

  11. Carboxylic Acids as A Traceless Activation Group for Conjugate Additions: A Three-Step Synthesis of ()-Pregabalin

    E-print Network

    MacMillan, David W. C.

    electrode (SCE) in CH3CN).9 We assumed that base-promoted deprotonation of a carboxylic acid substrateCarboxylic Acids as A Traceless Activation Group for Conjugate Additions: A Three-Step Synthesis: The direct application of carboxylic acids as a traceless activation group for radical Michael additions has

  12. Structure and function studies on enzymes with a catalytic carboxyl group(s): from ribonuclease T1 to carboxyl peptidases

    PubMed Central

    TAKAHASHI, Kenji

    2013-01-01

    A group of enzymes, mostly hydrolases or certain transferases, utilize one or a few side-chain carboxyl groups of Asp and/or Glu as part of the catalytic machinery at their active sites. This review follows mainly the trail of studies performed by the author and his colleagues on the structure and function of such enzymes, starting from ribonuclease T1, then extending to three major types of carboxyl peptidases including aspartic peptidases, glutamic peptidases and serine-carboxyl peptidases. PMID:23759941

  13. Human Delta1-pyrroline-5-carboxylate synthase: function and regulation.

    PubMed

    Hu, C-A A; Khalil, S; Zhaorigetu, S; Liu, Z; Tyler, M; Wan, G; Valle, D

    2008-11-01

    Mammalian Delta(1)-pyrroline-5-carboxylate synthase (P5CS) is a bifunctional ATP- and NAD(P)H-dependent mitochondrial enzyme that catalyzes the coupled phosphorylation and reduction-conversion of L: -glutamate to P5C, a pivotal step in the biosynthesis of L: -proline, L: -ornithine and L: -arginine. Previously, we reported cloning and characterization of two P5CS transcript variants generated by exon sliding that encode two protein isoforms differing only by a two amino acid-insert at the N-terminus of the gamma-glutamyl kinase active site. The short form (P5CS.short) is highly expressed in the gut and is inhibited by ornithine. In contrast, the long form (P5CS.long) is expressed ubiquitously and is insensitive to ornithine. Interestingly, we found that all the established human cell lines we have studied expressed P5CS.long but not P5CS.short. In addition, expression of P5CS.long can be modulated by hormones: downregulation by hydrocortisone and dexamethasone and upregulation by estradiol, for example. Using a quantitative proteomic approach, we showed that P5CS.long is upregulated by p53 in p53-induced apoptosis in DLD-1 colorectal cancer cells. Functional genomic analysis confirmed that there are two p53-binding consensus sequences in the promoter region and in the intron 1 of the human P5CS gene. Interestingly, overexpression of P5CS by adenoviruses harboring P5CS.long or P5CS.short in various cell types has no effect on cell growth or survival. It would be of importance to further investigate the role of P5CS as a p53 downstream effector and how P5CS.short expression is regulated by hormones and factors of alternative splicing in cells isolated from model animals. PMID:18401542

  14. Noncatalytic reaction of isonitriles and carboxylic acids en route to amide-type linkages

    Microsoft Academic Search

    Xuechen Li; Samuel J Danishefsky

    2008-01-01

    This protocol describes the preparation of an N-methyl-asparagine-linked glycosyl amino acid, on the basis of a reaction between carboxylic acids and isonitriles. Under microwave\\/thermolysis, carboxylic acids can couple with isonitriles without an external catalyst to form N-formyl-amides, which may be further advanced to the corresponding amides, N-methyl amide and N-methyloyl amide. The example reaction of ?-galactopyranosyl isonitrile (7) with a

  15. Utility of branched chain carboxylic acids in the manufacture of driers

    Microsoft Academic Search

    Alfred Fischer

    1966-01-01

    To be useful in the manufacture of driers, a carboxylic acid must yield lead, cobalt, manganese, calcium and zinc soaps which\\u000a are soluble in paint vehicles and petroleum hydrocarbon thinners. The drying metal soaps of a number of saturated branched\\u000a chain carboxylic acids were prepared to determine the relationship of acid structure to metal soap solubility. It was found\\u000a that

  16. 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

  17. Novel Regenerated Solvent Extraction Processes for the Recovery of Carboxylic Acids or Ammonia from Aqueous Solutions Part I. Regeneration of Amine-Carboxylic Acid Extracts

    Microsoft Academic Search

    L. J. Poole; C. J. King

    1990-01-01

    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 and HS) from industrial sour waters. The

  18. Some biological properties of new quinoline-4-carboxylic acid and quinoline-4-carboxamide derivatives.

    PubMed

    Strigácová, J; Hudecová, D; Varecka, L; Lásiková, A; Végh, D

    2000-01-01

    The antimicrobial and morphogenetic effects of fourteen newly synthesized 2-substituted derivatives of quinoline-4-carboxylic acid and quinoline-4-carboxamide were studied using G+ and G- bacteria, yeasts and filamentous fungi. The highest antimicrobial effects were found with substituted quinoline-4-carboxylic acid derivatives. Quinoline-4-carboxamides only weakly influenced the growth of the tested microorganisms. Some derivatives of quinoline-4-carboxylic acid elicited profound changes in the morphology of hyphal tips of Botrytis cinerea, mainly their branching and the release of the cytoplasmic content. Quinoline derivatives, which elicited morphological changes, increased also the permeability of the plasmalemma of plant cells. PMID:11347250

  19. Isolation of carboxylic acid-protected Au25 clusters using a borohydride purification strategy.

    PubMed

    Shivhare, Atal; Wang, Lisa; Scott, Robert W J

    2015-02-10

    We report the synthesis of 11-mercaptoundecanoic acid (11-MUA) and 16-mercaptohexadecanoic acid (16-MHA) protected Au25 clusters with moderate yields (?15%) using a NaBH4 purification strategy. UV-vis spectroscopy, transmission electron microscopy (TEM), and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry were employed to study the entire process of the isolation of 11-MUA-protected Au25 clusters from a polydisperse Au cluster solution. UV-vis and TEM data clearly show the formation of a polydisperse mixture, which upon the addition of NaBH4 leads to the growth and precipitation of non-Au25 clusters, leaving the Au25 clusters behind. MALDI MS shows the molecular ion peak for the 11-MUA-protected Au25 cluster. 11-MUA-protected Au25 clusters in THF were purified by slowly increasing the pH of the solution, which leads to the complete deprotonation of carboxyl groups on the surface and eventually precipitation of Au25 clusters. Further protonation of these clusters by acetic acid leads to their solubilization in THF. These results show that, owing to the inherent stability of Au25 clusters, a NaBH4 purification strategy can be used to isolate Au25 clusters with surface carboxylic acid functionalities from a polydisperse Au cluster solution. PMID:25590767

  20. Application of palladium-catalyzed carboxyl anhydride-boronic acid cross coupling in the synthesis of novel bile acids analogs with modified side chains.

    PubMed

    Mayorquín-Torres, Martha C; Flores-Álamo, Marcos; Iglesias-Arteaga, Martin A

    2015-09-01

    Palladium-catalyzed cross coupling of 4-methoxycarbonyl phenyboronic acid with acetylated bile acids in which the carboxyl functions was activated by formation of a mixed anhydride with pivalic anhydride afforded the cross coupled compounds, which were converted in novel side chain modified bile acids by one pot carbonyl reduction/removal of the protecting acetyl groups by Wolff-Kishner reduction. Unambiguous assignments of the NMR signals and crystal characterization of the heretofore unknown compounds are provided. PMID:26048448

  1. Effect of carboxylic acid content on the acute toxicity of oil sands naphthenic acids.

    PubMed

    Frank, Richard A; Fischer, Katharina; Kavanagh, Richard; Burnison, B Kent; Arsenault, Gilles; Headley, John V; Peru, Kerry M; Van Der Kraak, Glen; Solomon, Keith R

    2009-01-15

    Fractions of methylated naphthenic acids (NAs) isolated from oil sands process-affected waterwere collected utilizing Kugelrohr distillation and analyzed by proton nuclear magnetic resonance (1H NMR) spectroscopy. 1H NMR analysis revealed that the ratio of methyl ester hydrogen atoms to remaining aliphatic hydrogen atoms increased from 0.130 to 0.214, from the lowest to the greatest molecular weight (MW) fractions, respectively, indicating that the carboxylic acid content increased with greater MW. Acute toxicity assays with exposure to monocarboxyl NA-like surrogates demonstrated that toxicity increased with increasing MW (D. magna LC50 values of 10 +/- 1.3 mM and 0.59 +/- 0.20 mM for the respective lowest and highest MW NA-like surrogates); however, with the addition of a second carboxylic acid moiety, the toxicity was significantly reduced (D. magna LC50 values of 10 +/- 1.3 mM and 27 +/- 2.2 mM forthe respective monocarboxyl and dicarboxyl NA-like surrogates of similar MW). Increased carboxylic acid content within NA structures of higher MW decreases hydrophobicity and, consequently, offers a plausible explanation as to why lower MW NAs in oil sands process-affected water are more toxic than the greater MW NAs. PMID:19238950

  2. 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.

  3. An ab initio density functional study of the optical functions of 9-Methyl-3-Thiophen-2-YI-Thieno [3,2e] [1,2,4] Thriazolo [4,3c] Pyrimidine-8-Carboxylic Acid Ethyl Ester crystals

    NASA Astrophysics Data System (ADS)

    Reshak, Ali H.; Kityk, I. V.; Khenata, R.; Al-Douri, Y.; Auluck, S.

    An ab initio investigation of the optical constants of 9-Methyl-3-Thiophen-2-YI-Thieno [3,2e] [1,2,4] Thriazolo [4,3c] Pyrimidine-8-Carboxylic Acid Ethyl Ester crystal is performed within a framework of local density approximation (LDA), and the Engel-Vosko generalized gradient approximation (EV-GGA) exchange correlation potentials. It is established that there are two independent molecules (A and B) exhibiting different intra-molecular interactions: C-H⋯O (A) and C-H⋯N (B). These intra-molecular interactions favor stabilization of the crystal structure for molecules A and B. It should be emphasized that there exist remarkable ?-? interactions between the pyrimidine rings of the two neighbors B molecules giving extra strengths and stabilizations to the superamolecular structure. These different intra-molecular interactions C-H⋯O (A) and C-H⋯N (B) and the ?-? interaction between the pyrimidine rings of the two neighbors B molecules give principal contribution to dispersion of optical properties. With a view to seek deeper insight into the electronic structure, the optical properties were investigated. Our calculations show that the optical constants are very anisotropic. The EVGGA calculation shows a blue spectral shift of around 0.024 eV with significant changes in the spectra compared to the LDA calculation. The observed spectral shifts are in agreement with the calculated band structure and corresponding electron density of states.

  4. Effects of intermediate metabolite carboxylic acids of TCA cycle on Microcystis with overproduction of phycocyanin.

    PubMed

    Bai, Shijie; Dai, Jingcheng; Xia, Ming; Ruan, Jing; Wei, Hehong; Yu, Dianzhen; Li, Ronghui; Jing, Hongmei; Tian, Chunyuan; Song, Lirong; Qiu, Dongru

    2015-04-01

    Toxic Microcystis species are the main bloom-forming cyanobacteria in freshwaters. It is imperative to develop efficient techniques to control these notorious harmful algal blooms (HABs). Here, we present a simple, efficient, and environmentally safe algicidal way to control Microcystis blooms, by using intermediate carboxylic acids from the tricarboxylic acid (TCA) cycle. The citric acid, alpha-ketoglutaric acid, succinic acid, fumaric acid, and malic acid all exhibited strong algicidal effects, and particularly succinic acid could cause the rapid lysis of Microcystis in a few hours. It is revealed that the Microcystis-lysing activity of succinic acid and other carboxylic acids was due to their strong acidic activity. Interestingly, the acid-lysed Microcystis cells released large amounts of phycocyanin, about 27-fold higher than those of the control. On the other hand, the transcription of mcyA and mcyD of the microcystin biosynthesis operon was not upregulated by addition of alpha-ketoglutaric acid and other carboxylic acids. Consider the environmental safety of intermediate carboxylic acids. We propose that administration of TCA cycle organic acids may not only provide an algicidal method with high efficiency and environmental safety but also serve as an applicable way to produce and extract phycocyanin from cyanobacterial biomass. PMID:25342454

  5. Simple and convenient synthesis of esters from carboxylic acids and alkyl halides using tetrabutylammonium fluoride.

    PubMed

    Matsumoto, Kouichi; Shimazaki, Hayato; Miyamoto, Yu; Shimada, Kazuaki; Haga, Fumi; Yamada, Yuki; Miyazawa, Hirotsugu; Nishiwaki, Keiji; Kashimura, Shigenori

    2014-01-01

    A simple and convenient method has been developed for the synthesis of esters from the corresponding carboxylic acids and alkyl halides by using a stoichiometric amount of tetrabutylammonium fluoride (Bu?NF) as the base. The reaction of carboxylic acids and a Bu?NF/THF solution in DMF or THF as the solvent generates carboxylate ions in situ. The carboxylate ions thus generated and accumulated are highly reactive. They are then allowed to react with alkyl halides as the electrophiles, and afford the corresponding esters in moderate to good yields. The reaction without Bu?NF does not afford any product; therefore, Bu?NF seems to play an important role as the base in these reactions. A bulky countercation such as the tetrabutylammonium cation seems to increase the reactivity of the carboxylate ions in the solution phase. PMID:24770480

  6. Rh(III)-Catalyzed Decarboxylative Coupling of Acrylic Acids with Unsaturated Oxime Esters: Carboxylic Acids Serve as Traceless Activators

    PubMed Central

    2015-01-01

    ?,?-Unsaturated carboxylic acids undergo Rh(III)-catalyzed decarboxylative coupling with ?,?-unsaturated O-pivaloyl oximes to provide substituted pyridines in good yield. The carboxylic acid, which is removed by decarboxylation, serves as a traceless activating group, giving 5-substituted pyridines with very high levels of regioselectivity. Mechanistic studies rule out a picolinic acid intermediate, and an isolable rhodium complex sheds further light on the reaction mechanism. PMID:24512241

  7. 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 of secondary Fe(III) hydroxide precipitates below the oxidation front and the high concentrations of Fe(II) observed in the pore waters of some low-sulfide systems. The reduction of Fe(III) and the subsequent increase of iron mobility and potential acidity transfer (Fe(II) oxidation can result in the release of H+ in an oxic environment) should be taken in account in mine waste management strategies. PMID:15884343

  8. Photophysics of indole-2-carboxylic acid (I2C) and indole-5-carboxylic acid (I5C): Heavy atom effect

    NASA Astrophysics Data System (ADS)

    Kowalska-Baron, Agnieszka; Ga??cki, Krystian; Wysocki, Stanis?aw

    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 Cdbnd O, 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 ?s). The relatively short phosphorescence lifetime of I5C (56 ?s) may be the consequence of more effective ground-state quenching of I5C 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 × 108 M-1 s-1) as compared to that for indole (6.8 × 107 M-1 s-1) and I2C (2.3 × 107 M-1 s-1). The determined bimolecular rate constant for triplet state quenching by iodide kqT1 is equal to 1 × 104 M-1 s-1; 6 × 103 M-1 s-1 and 2.7 × 104 M-1 s-1 for indole, I2C and I5C, 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 triplet states has been expressed in Arrhenius form. The linearity of the obtained Arrhenius plots clearly indicated the existence of one temperature-dependent non-radiative process for the de-excitation of I2C and I5C triplet state in the presence of iodide. This process may be attributed to the solute-quenching by iodide and, most probably, proceeds via reversibly formed exciplex. The activation energies obtained from linear Arrhenius plots (1.89 kcal/mol for I5C; 2.55 kcal/mol for I2C) are smaller as compared to that for diffusion controlled reactions in aqueous solution (about 4 kcal/mol), which may indicate the great importance of the electrostatic interactions between solute and iodide ions in lowering the energy barrier needed for the formation of the triplet-quencher complex. Based on the theoretical predictions (at the DFT(CAM-B3LYP)/6-31 + G(d,p) level of theory) and careful analysis of the obtained FTIR spectra it may be concluded that in the solid state I2C and I5C molecules form associates by intermolecular NH⋯Odbnd C and OH⋯Odbnd C hydrogen bonding interactions, whereas the existence of intramolecular NH⋯Odbnd C interactions in the solid state of I2C and I5C is highly unlikely.

  9. Photophysics of indole-2-carboxylic acid (I2C) and indole-5-carboxylic acid (I5C): heavy atom effect.

    PubMed

    Kowalska-Baron, Agnieszka; Ga??cki, Krystian; Wysocki, Stanis?aw

    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 ?s). The relatively short phosphorescence lifetime of I5C (56 ?s) 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 triplet states has been expressed in Arrhenius form. The linearity of the obtained Arrhenius plots clearly indicated the existence of one temperature-dependent non-radiative process for the de-excitation of I2C and I5C triplet state in the presence of iodide. This process may be attributed to the solute-quenching by iodide and, most probably, proceeds via reversibly formed exciplex. The activation energies obtained from linear Arrhenius plots (1.89 kcal/mol for I5 C; 2.55 kcal/mol for I2 C) are smaller as compared to that for diffusion controlled reactions in aqueous solution (about 4 kcal/mol), which may indicate the great importance of the electrostatic interactions between solute and iodide ions in lowering the energy barrier needed for the formation of the triplet-quencher complex. Based on the theoretical predictions (at the DFT(CAM-B3LYP)/6-31+G(d,p) level of theory) and careful analysis of the obtained FTIR spectra it may be concluded that in the solid state I2 C and I5 C molecules form associates by intermolecular NH · · · OC and OH · · · OC hydrogen bonding interactions, whereas the existence of intramolecular NH · · · OC interactions in the solid state of I2C and I5C is highly unlikely. PMID:23933843

  10. 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. (Wyoming Univ., Laramie, WY (USA))

    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.

  11. Pilot-scale fermentation of office paper and chicken manure to carboxylic acids

    E-print Network

    Moody, Andrew Garret

    2006-08-16

    This project focused on scaling up the laboratory fermentation of biomass to carboxylic acids. Four 1050-gallon tanks were used to simulate four-stage countercurrent fermentation. Most laboratory fermentations have been performed with 1-L fermentors...

  12. Self-assembly of indole-2-carboxylic acid at graphite and gold surfaces.

    PubMed

    De Marchi, Fabrizio; Cui, Daling; Lipton-Duffin, Josh; Santato, Clara; MacLeod, Jennifer M; Rosei, Federico

    2015-03-14

    Model systems are critical to our understanding of self-assembly processes. As such, we have studied the surface self-assembly of a small and simple molecule, indole-2-carboxylic acid (I2CA). We combine density functional theory gas-phase (DFT) calculations with scanning tunneling microscopy to reveal details of I2CA assembly in two different solvents at the solution/solid interface, and on Au(111) in ultrahigh vacuum (UHV). In UHV and at the trichlorobenzene/highly oriented pyrolytic graphite (HOPG) interface, I2CA forms epitaxial lamellar structures based on cyclic OH?O carboxylic dimers. The structure formed at the heptanoic acid/HOPG interface is different and can be interpreted in a model where heptanoic acid molecules co-adsorb on the substrate with the I2CA, forming a bicomponent commensurate unit cell. DFT calculations of dimer energetics elucidate the basic building blocks of these structures, whereas calculations of periodic two-dimensional assemblies reveal the epitaxial effects introduced by the different substrates. PMID:25770512

  13. The conversion of corn stover and pig manure to carboxylic acids with the MixAlco process

    E-print Network

    Black, Amanda Spring

    2013-02-22

    The MixAlco process, developed by Dr. Mark T. Holtzapple, uses anaerobic fermentation to convert waste biomass into carboxylate salts which can then be manipulated into carboxylic acids, ketones and alcohols. This project focuses on the application...

  14. Standard molar enthalpies of formation of three branched alkyl carboxylic acids

    Microsoft Academic Search

    Manuel A. V. Ribeiro da Silva; M. L. C. C. H. Ferrão; Adelina M. R. O. Alves da Silva

    1999-01-01

    The standard (po= 0.1 MPa) molar enthalpies of combustion in oxygen at T= 298.15 K of three branched alkyl chain carboxylic acids, 2-methylpropanoic, 2,2-dimethylpropanoic, and 3-methylbutanoic, were measured by static bomb combustion calorimetry, from which their standard molar enthalpies of formation were derived.The standard molar enthalpies of formation at T= 298.15 K of the gaseous carboxylic acids were derived using

  15. Decomposition mechanism of the tert-butyl esters of carboxylic acids

    Microsoft Academic Search

    V. G. Avakyan; A. D. Litmanovich; V. O. Cherkezyan

    1984-01-01

    1.It has been shown by quantum-chemical calculations that the monomolecular decomposition of tert-butyl esters ot carboxylic acids, which involves the detachment of isobutylene, takes place as the result of the transfer of a proton from the closest CH3 group of the tert-butyl substituent to the carbonyl O atom.2.The catalytic action of carboxylic acids on this reaction is exhibited by the

  16. Direct Catalytic Anti-Markovnikov Addition of Carboxylic Acids to Alkenes

    PubMed Central

    Perkowski, Andrew J.

    2013-01-01

    A direct catalytic anti-Markovnikov addition of carboxylic acids to alkenes is reported. The catalyst system is comprised of the Fukuzumi acridinium photooxidant (1) and a substoichiometric quantity of a hydrogen atom donor. Oxidizable olefins such as styrenes, trisubstituted aliphatic alkenes, and enamides can be employed along with a variety of carboxylic acids to afford the anti-Markovnikov addition adducts exclusively. A deuterium-labeling experiment lends insight to the potential mechanism. PMID:23808532

  17. 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

  18. 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.

  19. A novel ceria–activated carbon composite for the catalytic ozonation of carboxylic acids

    Microsoft Academic Search

    P. C. C. Faria; J. J. M. Órfão; M. F. R. Pereira

    2008-01-01

    Ceria (Ce–O) and a novel ceria–activated carbon composite (AC0–Ce–O) were prepared and tested as catalysts in the ozonation of two selected carboxylic acids, oxalic acid and oxamic acid, at acid pH. Ce–O showed an interesting catalytic effect, especially in the ozonation of oxalic acid. A strong synergic effect was observed for the AC0–Ce–O composite in the case of oxalic acid,

  20. Extraction of ethanol with higher carboxylic acid solvents and their toxicity to yeast

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In a screening exercise for ethanol-selective extraction solvents, partitioning of ethanol and water from a 5 wt% aqueous solution into several C8 – C18 carboxylic acids was studied. Results for the acids are compared with those from alcohols of similar structure. In all cases studied, the acids exh...

  1. Theoretical modeling of the OH stretch infrared spectrum of carboxylic acid dimers based on first-principles anharmonic couplings

    E-print Network

    Zwier, Timothy S.

    Theoretical modeling of the OH stretch infrared spectrum of carboxylic acid dimers based on first, Wisconsin 53706-1396 Received 20 September 2002; accepted 28 October 2002 Carboxylic acid dimers serve, and OH bend internal coordinates for the formic acid and benzoic acid dimers. These are then projected

  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. Isolation and Molecular Characterization of 1-Aminocyclopropane-1-carboxylic Acid Synthase Genes in Hevea brasiliensis

    PubMed Central

    Zhu, Jia-Hong; Xu, Jing; Chang, Wen-Jun; Zhang, Zhi-Li

    2015-01-01

    Ethylene is an important factor that stimulates Hevea brasiliensis to produce natural rubber. 1-Aminocyclopropane-1-carboxylic acid synthase (ACS) is a rate-limiting enzyme in ethylene biosynthesis. However, knowledge of the ACS gene family of H. brasiliensis is limited. In this study, nine ACS-like genes were identified in H. brasiliensis. Sequence and phylogenetic analysis results confirmed that seven isozymes (HbACS1–7) of these nine ACS-like genes were similar to ACS isozymes with ACS activity in other plants. Expression analysis results showed that seven ACS genes were differentially expressed in roots, barks, flowers, and leaves of H. brasiliensis. However, no or low ACS gene expression was detected in the latex of H. brasiliensis. Moreover, seven genes were differentially up-regulated by ethylene treatment.These results provided relevant information to help determine the functions of the ACS gene in H. brasiliensis, particularly the functions in regulating ethylene stimulation of latex production. PMID:25690030

  4. Discovery of a Novel Series of CRTH2 (DP2) Receptor Antagonists Devoid of Carboxylic Acids

    PubMed Central

    2011-01-01

    Antagonism of the CRTH2 receptor represents a very attractive target for a variety of allergic diseases. Most CRTH2 antagonists known to date possess a carboxylic acid moiety, which is essential for binding. However, potential acid metabolites O-acyl glucuronides might be linked to idiosynchratic toxicity in humans. In this communication, we describe a new series of compounds that lack the carboxylic acid moiety. Compounds with high affinity (Ki < 10 nM) for the receptor have been identified. Subsequent optimization succeeded in reducing the high metabolic clearance of the first compounds in human and rat liver microsomes. At the same time, inhibition of the CYP isoforms was optimized, giving rise to stable compounds with an acceptable CYP inhibition profile (IC50 CYP2C9 and 2C19 > 1 ?M). Taken together, these data show that compounds devoid of carboxylic acid groups could represent an interesting alternative to current CRTH2 antagonists in development. PMID:24900284

  5. 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

  6. Visible Light Photorelease of Carboxylic Acids via Charge-Transfer Excitation of N-Methylpyridinium Iodide Esters.

    PubMed

    Kunsberg, David J; Kipping, Allison H; Falvey, Daniel E

    2015-07-17

    Iodide contrast sensitization to direct irradiation of charge transfer salts incurs carboxylic acid release via visible light absorption. The photochemical reduction of N-methyl-4-pyridinium iodide esters to release carboxylic acids is examined using (1)H NMR analysis. Photolysis reactions are carried out under mild, biphasic solvent conditions using a household LED lamp. Carboxylic acid release is reported in high yields, and the viability of this method for synthetic chemistry is demonstrated through a macroscale reaction. PMID:26120927

  7. Copper complexes of nicotinic-aromatic carboxylic acids as superoxide dismutase mimetics.

    PubMed

    Suksrichavalit, Thummaruk; Prachayasittikul, Supaluk; Piacham, Theeraphon; Isarankura-Na-Ayudhya, Chartchalerm; Nantasenamat, Chanin; Prachayasittikul, Virapong

    2008-01-01

    Nicotinic acid (also known as vitamin B3) is a dietary element essential for physiological and antihyperlipidemic functions. This study reports the synthesis of novel mixed ligand complexes of copper with nicotinic and other select carboxylic acids (phthalic, salicylic and anthranilic acids). The tested copper complexes exhibited superoxide dismutase (SOD) mimetic activity and antimicrobial activity against Bacillus subtilis ATCC 6633, with a minimum inhibition concentration of 256 microg/mL. Copper complex of nicotinic-phthalic acids (CuNA/Ph) was the most potent with a SOD mimetic activity of IC(50) 34.42 microM. The SOD activities were observed to correlate well with the theoretical parameters as calculated using density functional theory (DFT) at the B3LYP/LANL2DZ level of theory. Interestingly, the SOD activity of the copper complex CuNA/Ph was positively correlated with the electron affinity (EA) value. The two quantum chemical parameters, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), were shown to be appropriate for understanding the mechanism of the metal complexes as their calculated energies show good correlation with the SOD activity. Moreover, copper complex with the highest SOD activity were shown to possess the lowest HOMO energy. These findings demonstrate a great potential for the development of value-added metallovitamin-based therapeutics. PMID:19078847

  8. Photorelease of carboxylic acids, amino acids, and phosphates from N-alkylpicolinium esters using photosensitization by high wavelength laser dyes.

    PubMed

    Sundararajan, Chitra; Falvey, Daniel E

    2005-06-01

    Visible light (>450 nm) is used to efficiently cleave carboxylic acids, amino acids, and phosphates from their N-methyl picolinium esters. Photolysis using pyrromethene dyes PM 546 and PM 597 and also coumarin 6 as photosensitizers effects release of carboxylic acids, N-protected amino acids, and phosphates in quantitative yields. The effective rate of photorelease by the dyes, Phiepsilon, was found to be as high as 4500 M-1 cm-1. The photorelease proceeds through photoinduced electron transfer from the dye sensitizers to the N-methyl picolinium group. Fluorescence quenching and laser flash photolysis experiments support the photoinduced electron-transfer mechanism. PMID:15926809

  9. A Quick and Simple Conversion of Carboxylic Acids into Their Anilides of Heating with Phenyl Isothiocyanate.

    ERIC Educational Resources Information Center

    Ram, Ram N.; And Others

    1983-01-01

    Converting carboxylic acids into their anilides, which usually involves preparation of acid chloride or mixed anhydride followed by treatment with aniline, is tedious and/or time-consuming. A quick and easier procedure, using phenyl isothiocyanate, is provided. Reactions involved and a summary table of results are included. (JN)

  10. S-Adenosyl-L-Methionine:Salicylic Acid Carboxyl Methyltransferase, an Enzyme Involved in Floral Scent

    E-print Network

    Pichersky, Eran

    S-Adenosyl-L-Methionine:Salicylic Acid Carboxyl Methyltransferase, an Enzyme Involved in Floral Arbor, Michigan 48109 Received February 10, 1998, and in revised form April 14, 1999 S-Adenosyl-L-methionine:salicylic compound in C. breweri, from salicylic acid and S-adenosyl-L-methionine (SAM). The native en- zyme

  11. Communication: Spectroscopic measurement of the binding energy of a carboxylic acid-water dimer

    NASA Astrophysics Data System (ADS)

    Gu, Quanli; Knee, J. L.

    2012-05-01

    Infrared-ultraviolet two color pump-probe spectroscopy is used to measure the binding energy, D0, of a carboxylic acid-water dimer where the acid is 9-hydroxy-9-fluorenecarboxylic acid. The acid-water configuration presents a standard structure for the general acid-water interaction where the water bonds to the carboxylic acid group through two intermolecular hydrogen bonds. Photodissociation studies with product vibrational state resolution have enabled an accurate determination of the binding energy for this acid-water system to be D0 = 2975 ± 30 cm-1. Quantum chemical calculations are performed to compare with the experimental observations and a recent measurement on the water dimer (D0 = 1105 ± 10 cm-1).

  12. The Biosynthetic Pathway of Indole-3-Carbaldehyde and Indole-3-Carboxylic Acid Derivatives in Arabidopsis.

    PubMed

    Böttcher, Christoph; Chapman, Alexandra; Fellermeier, Franziska; Choudhary, Manisha; Scheel, Dierk; Glawischnig, Erich

    2014-04-11

    Indolic secondary metabolites play an important role in pathogen defense in cruciferous plants. In Arabidopsis (Arabidopsis thaliana), in addition to the characteristic phytoalexin camalexin, derivatives of indole-3-carbaldehyde (ICHO) and indole-3-carboxylic acid (ICOOH) are synthesized from tryptophan via the intermediates indole-3-acetaldoxime and indole-3-acetonitrile. Based on feeding experiments combined with nontargeted metabolite profiling, their composition in nontreated and silver nitrate (AgNO3)-treated leaf tissue was comprehensively analyzed. As major derivatives, glucose conjugates of 5-hydroxyindole-3-carbaldehyde, ICOOH, and 6-hydroxyindole-3-carboxylic acid were identified. Quantification of ICHO and ICOOH derivative pools after glucosidase treatment revealed that, in response to AgNO3 treatment, their total accumulation level was similar to that of camalexin. ARABIDOPSIS ALDEHYDE OXIDASE1 (AAO1), initially discussed to be involved in the biosynthesis of indole-3-acetic acid, and Cytochrome P450 (CYP) 71B6 were found to be transcriptionally coexpressed with camalexin biosynthetic genes. CYP71B6 was expressed in Saccharomyces cerevisiae and shown to efficiently convert indole-3-acetonitrile into ICHO and ICOOH, thereby releasing cyanide. To evaluate the role of both enzymes in the biosynthesis of ICHO and ICOOH derivatives, knockout and overexpression lines for CYP71B6 and AAO1 were established and analyzed for indolic metabolites. The observed metabolic phenotypes suggest that AAO1 functions in the oxidation of ICHO to ICOOH in both nontreated and AgNO3-treated leaves, whereas CYP71B6 is relevant for ICOOH derivative biosynthesis specifically after induction. In summary, a model for the biosynthesis of ICHO and ICOOH derivatives is presented. PMID:24728709

  13. Automatic analyzer for highly polar carboxylic acids based on fluorescence derivatization-liquid chromatography.

    PubMed

    Todoroki, Kenichiro; Nakano, Tatsuki; Ishii, Yasuhiro; Goto, Kanoko; Tomita, Ryoko; Fujioka, Toshihiro; Min, Jun Zhe; Inoue, Koichi; Toyo'oka, Toshimasa

    2015-03-01

    A sensitive, versatile, and reproducible automatic analyzer for highly polar carboxylic acids based on a fluorescence derivatization-liquid chromatography (LC) method was developed. In this method, carboxylic acids were automatically and fluorescently derivatized with 4-(N,N-dimethylaminosulfonyl)-7-piperazino-2,1,3-benzoxadiazole (DBD-PZ) in the presence of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride by adopting a pretreatment program installed in an LC autosampler. All of the DBD-PZ-carboxylic acid derivatives were separated on the ODS column within 30 min by gradient elution. The peak of DBD-PZ did not interfere with the separation and the quantification of all the acids with the exception of lactic acid. From the LC-MS/MS analysis, we confirmed that lactic acid was converted to an oxytriazinyl derivative, which was further modified with a dimethoxy triazine group of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM). We detected this oxytriazinyl derivative to quantify lactic acid. The detection limits (signal-to-noise ratio = 3) for the examined acids ranged from 0.19 to 1.1 µm, which correspond to 95-550 fmol per injection. The intra- and inter-day precisions of typical, highly polar carboxylic acids were all <9.0%. The developed method was successfully applied to the comprehensive analysis of carboxylic acids in various samples, which included fruit juices, red wine and media from cultured tumor cells. PMID:25082081

  14. Enhanced diastereoselectivity via confinement: photoisomerization of 2,3-diphenylcyclopropane-1-carboxylic acid derivatives within zeolites.

    PubMed

    Sivaguru, J; Sunoj, Raghavan B; Wada, Takehiko; Origane, Yumi; Inoue, Yoshihisa; Ramamurthy, Vaidhyanathan

    2004-10-01

    From the perspective of asymmetric induction, the photochemistry of 24 chiral esters and amides of cis-2,3-diphenylcyclopropane-1-carboxylic acid from excited singlet and triplet states has been investigated within zeolites. The chiral auxiliaries placed at a remote location from the isomerization site functioned far better within a zeolite than in solution. Generally, chiral auxiliaries with an aromatic or a carbonyl substituent performed better than the ones containing only alkyl substituents. A model based on cation-binding-dependent flexibility of the chiral auxiliary accounts for the observed variation in de between aryl (and carbonyl) and alkyl chiral auxiliaries within zeolites. Cation-dependent diastereomer switch was also observed in select examples. PMID:15387575

  15. 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

  16. Inhibition of a medium chain acyl-CoA synthetase involved in glycine conjugation by carboxylic acids.

    PubMed

    Kasuya, F; Igarashi, K; Fukui, M

    1996-11-22

    Molecular characteristics of carboxylic acids were investigated for the ability to inhibit a purified medium chain acyl-CoA synthetase, using hexanoic acid as a substrate. Salicylic acid, 4-methylsalicylic acid, 2-hydroxynaphtoic acid, and 2-hydroxyoctanoic acid, which do not act as substrates for the medium chain acyl-CoA synthetase, were potent as inhibitors. Valproic acid was not an inhibitor. Salicylic acid, 2-hydroxynaphthoic acid, and 2-hydroxyoctanoic acid inhibited the medium chain acyl-CoA synthetase with Ki values of 37, 5.2, and 500 microM, respectively. 4-Methylsalicylic acid was more potent than salicylic acid. The inhibitory carboxylic acids were competitive with respect to hexanoic acid. The distance of the hydroxyl group from the carboxylic acid group of the benzene ring influenced the inhibitory activity. The hydroxyl group on the carbon adjacent to the carboxylic acid group was required for inhibitory activity. In addition, there was a good correlation between the lipophilicity of the carboxylic acids and the Ki values, suggesting that the lipophilicity of the carboxylic acids is a major determinant for inhibition of the medium chain acyl-CoA synthetase. PMID:8937481

  17. 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.

  18. Biocatalytic reduction of short-chain carboxylic acids into their corresponding alcohols with syngas fermentation.

    PubMed

    Perez, Jose M; Richter, Hanno; Loftus, Sarah E; Angenent, Largus T

    2013-04-01

    Short-chain carboxylic acids generated by various mixed- or pure-culture fermentation processes have been considered valuable precursors for production of bioalcohols. While conversion of carboxylic acids into alcohols is routinely performed with catalytic hydrogenation or with strong chemical reducing agents, here, a biological conversion route was explored. The potential of carboxydotrophic bacteria, such as Clostridium ljungdahlii and Clostridium ragsdalei, as biocatalysts for conversion of short-chain carboxylic acids into alcohols, using syngas as a source of electrons and energy is demonstrated. Acetic acid, propionic acid, n-butyric acid, isobutyric acid, n-valeric acid, and n-caproic acid were converted into their corresponding alcohols. Furthermore, biomass yields and fermentation stoichiometry from the experimental data were modeled to determine how much metabolic energy C. ljungdahlii generated during syngas fermentation. An ATP yield of 0.4-0.5 mol of ATP per mol CO consumed was calculated in the presence of hydrogen. The ratio of protons pumped across the cell membrane versus electrons transferred from ferredoxin to NAD(+) via the Rnf complex is suggested to be 1.0. Based on these results, we provide suggestions how n-butyric acid to n-butanol conversion via syngas fermentation can be further improved. PMID:23172270

  19. Chiroptical spectroscopy of natural products: avoiding the aggregation effects of chiral carboxylic acids.

    PubMed

    Polavarapu, Prasad L; Donahue, Emily A; Hammer, Karissa C; Raghavan, Vijay; Shanmugam, Ganesh; Ibnusaud, Ibrahim; Nair, Divya S; Gopinath, Chithra; Habel, Deenamma

    2012-08-24

    Determination of the absolute configurations and predominant conformations of chiral natural products, occurring as carboxylic acids, using chiroptical spectroscopic methods becomes challenging due to the formation of solute aggregates (in the form of dimers, etc.) and/or solute-solvent complexes resulting from intermolecular hydrogen bonding with solvent. A hypothesis that such aggregation effects can be avoided by using corresponding sodium salts or acid anhydrides for chiroptical spectroscopic measurements has been tested. For this purpose, vibrational circular dichroism, electronic circular dichroism, and optical rotatory dispersion spectra for disodium salts of two natural products, hibiscus acid and garcinia acid, and the anhydride of acetylated garcinia acid have been measured. These experimental spectra are analyzed in combination with quantum chemical calculations of corresponding spectra. The spectral analysis for sodium salts and anhydride turned out to be simpler, suggesting that the conversion of carboxylic acids to corresponding salts or anhydride can be advantageous for the application of chiroptical spectroscopy. PMID:22877358

  20. The conversion of corn stover and pig manure to carboxylic acids with the MixAlco process 

    E-print Network

    Black, Amanda Spring

    2013-02-22

    of ruminant bacteria to digest the biomass into carboxylate salts (e. g. , calcium acetate, propionate, and butyrate). These carboxylate salts can be chemically manipulated to produce ketones or alcohols, both of which have a marketable value. Benefits... culture is beneficial because it adapts to a wide variety of input materials while regenerating its population to maintain an equilibrium. The microbial digestion ofbiomass results in carboxylic acids (e. g. , acetic, propionic, and butyric acids...

  1. Direct conversion of carboxylate salts to carboxylic acids via reactive extraction 

    E-print Network

    Xu, Xin

    2008-10-10

    The MixAlco process, a proprietary technology owned by Texas A&M University, converts biomass (e.g., municipal solid waste, sewage sludge, paper, agricultural residues, and energy crops) into usable chemicals (e.g., acetic acid) and fuels (e...

  2. Hydrogen bonds in 1:1 complex of piperidine-3-carboxylic acid with salicylic acid

    NASA Astrophysics Data System (ADS)

    Bartoszak-Adamska, El?bieta; Dega-Szafran, Zofia; Krociak, Magdalena; Jaskolski, Mariusz; Szafran, Miros?aw

    2009-02-01

    The 1:1 complex between the zwitterionic piperidinium-3-carboxylate (P3C) and salicylic acid (SAL), P3C·SAL, has been characterized by single crystal X-ray analysis, FTIR and NMR spectroscopy, and by DFT calculations. The crystals are orthorhombic, space group Pbca, with a = 11.6477(7), b = 9.1754(6), c = 23.5833(12) Å. An O sbnd H⋯O bridge (2.537(1) Å) links the SAL and P3C moieties. The proton in this H bond is located closer to the salicylic carboxylate group. In the P3C moiety, the piperidine ring adopts the chair conformation, and the carboxylate group is in the axial orientation and is stabilized by an intramolecular N +sbnd H⋯O hydrogen bond of 2.847(1) Å. In the crystal packing, two P3C·SAL units form a centrosymmetric dimer through a pair of intermolecular N +sbnd H⋯O bonds of 2.801(1) Å. The dimers form a zigzag chain linked via another N +sbnd H⋯O bond (2.799(1) Å). In the structures of the monomeric [P3C·SAL] and dimeric [(P3C·SAL) 2] species optimized by B3LYP/6-31G(d,p) calculations, both the inter- and intra-molecular hydrogen bonds are shorter than in the crystal. The FTIR spectrum shows a broad absorption in the 3100-2400 cm -1 region attributed to ?NH and ?OH vibrations. The broad absorption in the 1500-600 cm -1 region is attributed to the O sbnd H·O hydrogen bonds. The 1H and 13C NMR spectra have been analyzed to elucidate the structure of the P3C·SAL complex in solution. The GIAO magnetic isotropic shielding tensors have been used to predict the 1H and 13C chemical shifts in DMSO solution.

  3. A lead-207 nuclear magnetic resonance study of the complexation of lead by carboxylic acids and aminocarboxylic acids

    NASA Astrophysics Data System (ADS)

    Nakashima, Thomas T.; Rabenstein, Dallas L.

    The complexation of Pb(II) by carboxylic acids and aminocarboxylic acids was studied by 207Pb NMR. The results indicate that the 207Pb chemical shift provides a sensitive probe of the aqueous coordination chemistry of Pb(II). A single, exchange-averaged resonance is observed for lead in solutions containing Pb(NO 3) 2 and pivalic acid, acetic acid, formic acid, or chloroacetic acid, the chemical shift of which is sensitive to the Pb(NO 3) 2 to carboxylic acid ratio and to solution pH. Formation constants for the Pb(II)-carboxylate complexes were determined by fitting the chemical shift data to a model involving the complexes and ligand protonation. Chemical shift data for solutions containing Pb(NO 3) 2 and glycine, histidine, or glycylglycine indicate complexation of Pb(II) by the zwitterionic forms of these ligands. Formation constants for these complexes, which are difficult to study by other methods, were also determined from the chemical shift data. Complexation of Pb(II) by ethylenediaminetetraacetic acid, N-hydroxyethylethylenediaminetriacetic acid, nitrilotriacetic acid, and N-methyliminodiacetic acid causes a large deshielding of the 207Pb nucleus, e.g., the resonance for the ethylenediaminetetraacetic acid complex is deshielded by 2350 ppm. The chemical shift of the lead in these complexes is sensitive to protonation of the complex and to the formation of mixed complexes containing hydroxide ion.

  4. Corrosion of iron in anhydrous acetonitrile solutions of some carboxylic acids

    SciTech Connect

    Aramaki, Kunitsugu; Shimizu, Kiyoshi; Sakakibara, Makoto; Nishihara, Hiroshi (Keio Univ., Yokohama (Japan). Dept. of Chemistry)

    1993-06-01

    Corrosion of iron in anhydrous acetronitrile solutions of some carboxylic acids containing a small amount of water (100 [approximately] 350 ppm) was investigated by polarization measurements. Polarization curves of the iron electrode in aqueous and acetonitrile solutions of carboxylic acids (acetic, chloroacetic, dichloroacetic, and benzoic) are discussed based on the content of water and the concentration of H[sup +] and carboxylate ion. A linear relationship between logarithms of the corrosion current density and proton concentration was established for iron in acetonitrile solutions. The cathodic reaction was first order with respect to the H[sup +] concentration. The cathodic process of iron corrosion in the acetonitrile solutions with a small amount of water seemed to be similar to that in the aqueous solutions.

  5. The Enolase Superfamily: A General Strategy for Enzyme-Catalyzed Abstraction of the R-Protons of Carboxylic Acids

    E-print Network

    Rayment, Ivan

    -Protons of Carboxylic Acids Patricia C. Babbitt,*, Miriam S. Hasson,§,| Joseph E. Wedekind,,# David R. J. Palmer by their ability to catalyze the abstraction of the R-proton of a carboxylic acid to form an enolic intermediate specialized enzymes: mandelate racemase, galactonate dehydratase, glucarate dehydratase, muconate

  6. 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 acids. The high concentrations in summer could lead to the conclusion that these acids are mostly formed during photochemical processes in the atmosphere. However, the concentrations in autumn were often exceeded by the ones in winter. Therefore probably other sources beside photochemical processes have to be considered. The second group consists of aromatic compounds. Because of the high concentrations in winter it can be concluded that photochemical formation plays a minor role and primary emission sources e.g., wood combustion are likely. Further evidence in determining sources of the carboxylic acids could be obtained from the air mass origin. In general, air masses transported from East have a more anthropogenic influence than the air mass inflow from West. For all aromatic carboxylic acids higher concentrations were determined during eastern inflow, indicating anthropogenic sources. This presumption is supported by high correlations with the elemental carbon (EC). Regarding the aliphatic carboxylic there is one group with higher concentrations when the air mass is transported from West and one with higher concentrations when air mass is transported from East. In summary the findings of this study reveal a clear difference in the seasonal trends of the single target acids indicating a variety of different sources.

  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. Determination of polyfluoroalkyl phosphoric acid diesters, perfluoroalkyl phosphonic acids, perfluoroalkyl phosphinic acids, perfluoroalkyl carboxylic acids, and perfluoroalkane sulfonic acids in lake trout from the Great Lakes region.

    PubMed

    Guo, Rui; Reiner, Eric J; Bhavsar, Satyendra P; Helm, Paul A; Mabury, Scott A; Braekevelt, Eric; Tittlemier, Sheryl A

    2012-11-01

    A comprehensive method to extract perfluoroalkyl carboxylic acids, perfluoroalkane sulfonic acids, perfluoroalkyl phosphonic acids, perfluoroalkyl phosphinic acids, and polyfluoroalkyl phosphoric acid diesters simultaneously from fish samples has been developed. The recoveries of target compounds ranged from 78 % to 121 %. The new method was used to analyze lake trout (Salvelinus namaycush) from the Great Lakes region. The results showed that the total perfluoroalkane sulfonate concentrations ranged from 0.1 to 145 ng/g (wet weight) with perfluorooctane sulfonate (PFOS) as the dominant contaminant. Concentrations in fish between lakes were in the order of Lakes Ontario ? Erie > Huron > Superior ? Nipigon. The total perfluoroalkyl carboxylic acid concentrations ranged from 0.2 to 18.2 ng/g wet weight. The aggregate mean perfluorooctanoic acid (PFOA) concentration in fish across all lakes was 0.045 ± 0.023 ng/g. Mean concentrations of PFOA were not significantly different (p > 0.1) among the five lakes. Perfluoroalkyl phosphinic acids were detected in lake trout from Lake Ontario, Lake Erie, and Lake Huron with concentration ranging from non-detect (ND) to 0.032 ng/g. Polyfluoroalkyl phosphoric acid diesters were detected only in lake trout from Lake Huron, at levels similar to perfluorooctanoic acid. PMID:22722738

  9. Convenient one-pot synthesis of 2-oxazolines from carboxylic acids.

    PubMed

    Hioki, Kazuhito; Takechi, Yumiko; Kimura, Noriyo; Tanaka, Hiroyuki; Kunishima, Munetaka

    2008-12-01

    Simple one-pot methods for preparation of 2-oxazolines have been developed using 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM). Treatment of a mixture of carboxylic acids and 2-haloethylammonium salts with DMT-MM in methanol followed by refluxing in the presence of KOH gives oxazolines. PMID:19043250

  10. 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

  11. Regioselective Enzymatic ?-Carboxylation of para-Hydroxy- styrene Derivatives Catalyzed by Phenolic Acid Decarboxylases

    PubMed Central

    Wuensch, Christiane; Pavkov-Keller, Tea; Steinkellner, Georg; Gross, Johannes; Fuchs, Michael; Hromic, Altijana; Lyskowski, Andrzej; Fauland, Kerstin; Gruber, Karl; Glueck, Silvia M; Faber, Kurt

    2015-01-01

    We report on a ‘green’ method for the utilization of carbon dioxide as C1 unit for the regioselective synthesis of (E)-cinnamic acids via regioselective enzymatic carboxylation of para-hydroxystyrenes. Phenolic acid decarboxylases from bacterial sources catalyzed the ?-carboxylation of para-hydroxystyrene derivatives with excellent regio- and (E/Z)-stereoselectivity by exclusively acting at the ?-carbon atom of the C=C side chain to furnish the corresponding (E)-cinnamic acid derivatives in up to 40% conversion at the expense of bicarbonate as carbon dioxide source. Studies on the substrate scope of this strategy are presented and a catalytic mechanism is proposed based on molecular modelling studies supported by mutagenesis of amino acid residues in the active site. PMID:26190963

  12. Biodegradation kinetics of trans-4-methyl-1-cyclohexane carboxylic acid

    Microsoft Academic Search

    Janice C. Paslawski; John V. Headley; Gordon A. Hill; Mehdi Nemati

    2009-01-01

    Naphthenic acids are a complex mixture of organic compounds which naturally occur in crude oil. Low molecular weight components\\u000a of the naphthenic acids are known to be toxic in aquatic environments and there is a need to better understand the factors\\u000a controlling the kinetics of their biodegradation. In this study, a relatively low molecular weight naphthenic acid compound\\u000a (trans-isomer of

  13. Adsorption of Co(II) by a carboxylate-functionalized polyacrylamide grafted lignocellulosics.

    PubMed

    Shibi, I G; Anirudhan, T S

    2005-02-01

    A new adsorbent (PGBS-COOH) having carboxylate functional group at the chain end was synthesized by graft copolymerization of acrylamide onto banana stalk, BS (Musa Paradisiaca) using ferrous ammonium sulphate/H2O2 redox initiator system. The efficiency of the adsorbent in the removal of cobalt [Co(II)] from water was investigated using batch adsorption technique. The adsorbent exhibits very high adsorption potential for Co(II) and under optimum conditions more than 99% removal was achieved. The maximum adsorption capacity was observed at the pH range 6.5-9.0. The equilibrium isotherm data were analysed using three isotherm models, Langmuir, Freundlich and Scatchard, to determine the best fit equation for the sorption of Co(II) on the PGBS-COOH. A comparative study with a commercial cation exchanger, Ceralite IRC-50, having carboxylate functional group showed that PGBS-COOH is 2.8 times more effective compared to Ceralite IRC-50 at 30 degrees C. Synthetic nuclear power plant coolant water samples were also treated by the adsorbent to demonstrate its efficiency in removing Co(II) from water in the presence of other metal ions. Acid regeneration was tried for several cycles to recover the adsorbed metal ions and also to restore the sorbent to its original state. PMID:15664619

  14. Group composition of carboxylic acids from West Siberian crude oils

    Microsoft Academic Search

    N. I. Zhil'tsov; V. A. Ershov; G. I. Samokhvalova

    1982-01-01

    with alkali [i]~ The physical and chemical properties of the crude oils from which the petroleum acids were obtained are listed in Table i, along with the results from chromatographic separation of the extracts into fractions of neutral substances, phenol, and carboxyiic acids. The deviation between results of parallel analyses was no greater than 15% (relative), and the losses in

  15. Enhanced Production of Carboxylic Acids by Engineering of Rhizopus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The fungus Rhizopus is frequently used to convert, or ferment sugars obtained from agricultural crops to lactic acid. This natural product has long been utilized by the food industry as an additive for preservation, flavor, and acidity. Additionally, it is used for the manufacture of environmental...

  16. Role of biologically active inorganic anions Cl- and Br- in inclusion complex formation of ?-cyclodextrin with some aromatic carboxylic acids

    NASA Astrophysics Data System (ADS)

    Terekhova, Irina; Chibunova, Ekaterina; Kumeev, Roman; Alper, Gennady

    2013-02-01

    1H NMR spectroscopy was used to evaluate the effects of biologically active anions Cl- and Br- in inclusion complex formation of ?-cyclodextrin with some aromatic carboxylic acids. It was demonstrated that presence of Br- anions induces the decrease in ?-cyclodextrin binding affinity to carboxylic acids, while Cl- has no a noticeable effect. The observed difference was discussed in terms of selective interactions of ?-cyclodextrin with Br- and Cl-. Only Br- anions are able to penetrate into ?-cyclodextrin cavity and compete with carboxylic acid molecule for the macrocyclic cavity. This competition shifts the ?-cyclodextrin/acid equilibrium in the direction of complex dissociation.

  17. Simple thiol-ene click chemistry modification of SBA-15 silica pores with carboxylic acids.

    PubMed

    Bordoni, Andrea V; Lombardo, M Verónica; Regazzoni, Alberto E; Soler-Illia, Galo J A A; Wolosiuk, Alejandro

    2015-07-15

    A straightforward approach for anchoring tailored carboxylic groups in mesoporous SiO2 colloidal materials is presented. The thiol-ene photochemical reaction between vinyltrimethoxysilane precursors and various thiocarboxylic acids which has, click chemistry features (i.e. high conversion yields, insensitivity to oxygen, mild reaction conditions), results in carboxylated silane precursors that can be readily used as surface modifiers. The carboxylic groups of acetic, undecanoic and succinic acid were immobilized on the silica mesopore walls of SBA-15 powders employing the synthesized silane precursors. Post-grafting has been confirmed through infrared spectrometry (FTIR), energy dispersive X-ray spectroscopy (EDS), elemental analysis (EA) and zeta potential measurements. Detailed field-emission gun scanning electron microscopy (FESEM) images and small angle X-ray scattering (SAXS) data revealed parallel mesopores and ordered mesostructures. It is shown that the immobilized COOH groups are chemically accessible for acid-base reactions as well as copper adsorption. Immobilization of easily synthesized tailored carboxylic modified alkoxide precursors within mesoporous systems provides a unique chemical nanoenvironment within these ordered frameworks. PMID:25845883

  18. Tandem decarboxylative hydroformylation-hydrogenation reaction of ?,?-unsaturated carboxylic acids toward aliphatic alcohols under mild conditions employing a supramolecular catalyst system.

    PubMed

    Diab, Lisa; Gellrich, Urs; Breit, Bernhard

    2013-10-28

    A new atom economic catalytic method for a highly chemoselective reduction of ?,?-unsaturated carboxylic acids to the corresponding saturated alcohols under mild reaction conditions, compatible with a wide range reactive functional groups, is reported. The new methodology consists of a novel tandem decarboxylative hydroformylation/aldehyde reduction sequence employing a unique supramolecular catalyst system. PMID:24022335

  19. Inhibition of a medium chain acyl-CoA synthetase involved in glycine conjugation by carboxylic acids

    Microsoft Academic Search

    Fumiyo Kasuya; Kazuo Igarashi; Miyoshi Fukui

    1996-01-01

    Molecular characteristics of carboxylic acids were investigated for the ability to inhibit a purified medium chain acyl-CoA synthetase, using hexanoic acid as a substrate. Salicylic acid, 4-methylsalicylic acid, 2-hydroxynaphthoic acid, and 2-hydroxyoctanoic acid, which do not act as substrates for the medium chain acyl-CoA synthetase, were potent as inhibitors. Valproic acid was not an inhibitor. Salicylic acid, 2-hydroxynaphthoic acid, and

  20. 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 ?-? 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 the TMBP (10b, 11b, 12b). The structure of each compound depends on the dihedral angle between the carboxyl group and the nitrogenous base. All these compounds indicate three main synthons that regularly occur, namely linear heterodimer (HD), heterotrimer (HT) and heterotetramer (LHT). PMID:24655545

  1. 1-aminocyclopropane-1-carboxylic acid (ACC) in plants: more than just the precursor of ethylene!

    PubMed Central

    Van de Poel, Bram; Van Der Straeten, Dominique

    2014-01-01

    Ethylene is a simple two carbon atom molecule with profound effects on plants. There are quite a few review papers covering all aspects of ethylene biology in plants, including its biosynthesis, signaling and physiology. This is merely a logical consequence of the fascinating and pleiotropic nature of this gaseous plant hormone. Its biochemical precursor, 1-aminocyclopropane-1-carboxylic acid (ACC) is also a fairly simple molecule, but perhaps its role in plant biology is seriously underestimated. This triangularly shaped amino acid has many more features than just being the precursor of the lead-role player ethylene. For example, ACC can be conjugated to three different derivatives, but their biological role remains vague. ACC can also be metabolized by bacteria using ACC-deaminase, favoring plant growth and lowering stress susceptibility. ACC is also subjected to a sophisticated transport mechanism to ensure local and long-distance ethylene responses. Last but not least, there are now a few exciting studies where ACC has been reported to function as a signal itself, independently from ethylene. This review puts ACC in the spotlight, not to give it the lead-role, but to create a picture of the stunning co-production of the hormone and its precursor. PMID:25426135

  2. DETERMINATION OF CARBOXYLIC ACIDS BY ION-EXCLUSION CHROMATOGRAPHY WITH NON-SUPPRESSED CONDUCTIVITY AND OPTICAL DETECTORS

    EPA Science Inventory

    Determination of carboxylic acids using non-suppressed conductivity and UV detections is described. The background conductance of 1-octanesulfonic acid, hexane sulfonic acid and sulfuric acid at varying concentrations was determined. Using 0.2 mM 1-octanesulfonic acid as a mobile...

  3. DETERMINATION OF CARBOXYLIC ACIDS BY ION-EXCLUSION CHROMATOGRAPHY WITH NON-SUPPRESSED CONDUCTIVITY AND OPTICAL DETECTORS

    EPA Science Inventory

    Determination of carboxylic acids using non-suppressed conductivity and UV detections is described. he background conductance of I-octanesulfonic acid, hexane sulfonic acid and sulfuric acid at varying concentrations was determined. sing 0.2 MM I-octanesulfonic acid as a mobile p...

  4. 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.

  5. 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.

  6. Conversion of municipal solid waste to carboxylic acids using a mixed culture of mesophilic microorganisms.

    PubMed

    Aiello-Mazzarri, Cateryna; Agbogbo, Frank K; Holtzapple, Mark T

    2006-01-01

    Waste biomass was anaerobically converted to carboxylate salts by using a mixed culture of acid-forming microorganisms. Municipal solid waste (MSW) was the energy source (carbohydrates) and sewage sludge (SS) was the nutrient source (minerals, metals, and vitamins). Four fermentors were arranged in series and solids and liquids were transferred countercurrently in opposite directions, which allows both high conversions and high product concentrations. Fresh biomass was added to Fermentor 1 (highest carboxylic acid concentration) and fresh media was added to Fermentor 4 (most digested biomass). All fermentations were performed at 40 degrees C. Calcium carbonate was added to the fermentors to neutralize the acids to their corresponding carboxylate salts. Iodoform was used to inhibit methane production and urea was added as a nitrogen source. Product concentrations were up to 25 g/L, with productivities up to 1.4 g total acid/(L liquid d). Mass balances with closure between 93% and 105% were obtained for all systems. Continuum particle distribution modeling (CPDM) was applied to correlate batch fermentation data to countercurrent fermentation data and predict product concentration over a wide range of solids loading rates and residence times. CPDM for lime-treated MSW/SS fermentation system predicted the experimental total acid concentration and conversion within 4% and 16% respectively. PMID:16154502

  7. Effect of carboxylic acid of periodic mesoporous organosilicas on the fructose-to-5-hydroxymethylfurfural conversion in dimethylsulfoxide systems

    NASA Astrophysics Data System (ADS)

    Dutta, Saikat; Kao, Hsien-Ming; Wu, Kevin C.-W.

    2014-11-01

    This manuscript presents the preparation and catalytic application of highly ordered benzene bridged periodic mesoporous organosilicas (PMOs) functionalized with carboxylic acid (-COOH) group at varied density. The COOH-functionalized PMOs were synthesized by one-step condensation of 1,4-bis (triethoxysilyl) benzene and carboxylic group containing organosilane carboxyethylsilanetriol sodium salt using Brij-76 as the template. The obtained materials were characterized by a mean of methods including powder X-ray diffraction, nitrogen adsorption-desorption, scanning- and transmission electron microscopy, and 13C solid-state nuclear magnetic resonance measurements. The potentials of the obtained PMO materials with ordered mesopores were examined as solid catalysts for the chemical conversion of fructose to 5-hydroxymethylfurfural (HMF) in an organic solvent. The results showed that COOH-functionalized PMO with 10% COOH loading exhibited best results for the fructose to HMF conversion and selectivity. The high surface area, the adequate density acid functional group, and the strength of the PMO materials contributing to a promising catalytic ability were observed.

  8. Enols of Carboxylic Acid Amides with -Electron-Withdrawing Substituents

    E-print Network

    Sklenak, Stepan

    , Stepan Sklena´k, and Zvi Rappoport* Contribution from the Department of Organic Chemistry and the Miner were ascribed to stabilization of the acid form by resonative electron donation from the heteroatom X (X ) OH, OR, NRR, OCOR, halogen; cf. hybrid 2b, eq 1).2a A similar resonative electron donation from

  9. Controlled-potential coulometry for the analysis of carboxylic acids

    Microsoft Academic Search

    S. G. Abdullina; O. A. Lira; G. K. Ziyatdinova; G. K. Budnikov; N. P. Kodryanu

    2009-01-01

    Coulometric titration methods with potentiometric indication of the end-point have been developed for determining benzoic,\\u000a salicylic, nicotinic, and ascorbic acids in various pharmaceutical dosage forms, liniments, and aqueous alcohol solutions.\\u000a The relative standard deviation was within 0.01–0.02.

  10. (R)-(+)-N-methylbenzoguanidine ((R)-NMBG) catalyzed kinetic resolution of racemic secondary benzylic alcohols with free carboxylic acids by asymmetric esterification.

    PubMed

    Nakata, Kenya; Shiina, Isamu

    2011-10-21

    (R)-(+)-N-Methylbenzoguanidine ((R)-NMBG) was found to function as an efficient acyl-transfer catalyst for the kinetic resolution of racemic secondary benzylic alcohols in the presence of achiral carboxylic acids and pivalic anhydride. The use of a tertiary amine in this reaction is not necessary to attain good chemical yields of the products. It was determined that diphenylacetic acid could be employed as the most suitable acyl donor for achieving a high enantioselectivity for the kinetic resolution of the racemic secondary benzylic alcohols having normal aliphatic alkyl chains at the C-1 positions. On the other hand, a less-hindered carboxylic acid, such as 3-phenylpropanoic acid, functioned as a better acyl donor for the kinetic resolution of racemic secondary benzylic alcohols having branched aliphatic alkyl chains at the C-1 positions. PMID:21887445

  11. Salt and co-crystal formation from 6-bromobenzo[d]thiazol-2-amine and different carboxylic acid derivatives

    NASA Astrophysics Data System (ADS)

    Jin, Shouwen; Yan, Pinhui; Wang, Daqi; Xu, Yijie; Jiang, Yingyan; Hu, Liangliang

    2012-05-01

    Studies concentrating on non-covalent interactions between the organic base of 6-bromobenzo[d]thiazol-2-amine, and carboxylic acid derivatives have led to an increased understanding of the role 6-bromobenzo[d]thiazol-2-amine has in binding with carboxylic acid derivatives. Here anhydrous and hydrated multicomponent organic acid-base adducts of 6-bromobenzo[d]thiazol-2-amine have been prepared with the carboxylic acids as p-nitrobenzoic acid, fumaric acid, L-tartaric acid, and terephthalic acid. The four crystalline compounds were characterized by X-ray diffraction analysis, infrared (IR), melting point (mp), and elemental analysis. All structures adopted hetero R22(8) supramolecular synthons except the salt 3. Analysis of crystal packing of the compounds under study suggests that there are Nsbnd H⋯O, Osbnd H⋯N, and Osbnd H⋯O hydrogen bonds (charge assisted or neutral) between acid and base components in the supramolecular assemblies.

  12. 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

  13. Attenuated total reflectance Fourier-transform infrared spectroscopy of carboxylic acids adsorbed onto mineral surfaces

    NASA Astrophysics Data System (ADS)

    Kubicki, J. D.; Schroeter, L. M.; Itoh, M. J.; Nguyen, B. N.; Apitz, S. E.

    1999-09-01

    A suite of naturally-occurring carboxylic acids (acetic, oxalic, citric, benzoic, salicylic and phthalic) and their corresponding sodium salts were adsorbed onto a set of common mineral substrates (quartz, albite, illite, kaolinite and montmorillonite) in batch slurry experiments. Solution pH's of approximately 3 and 6 were used to examine the effects of pH on sorption mechanisms. Attenuated total reflectance Fourier-transform infrared (ATR FTIR) spectroscopy was employed to obtain vibrational frequencies of the organic ligands on the mineral surfaces and in solution. UV/visible spectroscopy on supernatant solutions was also employed to confirm that adsorption from solution had taken place for benzoic, salicylic and phthalic acids. Molecular orbital calculations were used to model possible surface complexes and interpret the experimental spectra. In general, the tectosilicates, quartz and albite feldspar, did not chemisorb (i.e., strong, inner-sphere adsorption) the carboxylate anions in sufficient amounts to produce infrared spectra of the organics after rinsing in distilled water. The clays (illite, kaolinite and montmorillonite) each exhibited similar ATR FTIR spectra. However, the illite sample used in this study reacted to form strong surface and aqueous complexes with salicylic acid before being treated to remove free Fe-hydroxides. Chemisorption of carboxylic acids onto clays is shown to be limited without the presence of Fe-hydroxides within the clay matrix.

  14. Comparison Of Asymmetric Hydrogenations Of Unsaturated- Carboxylic Acids And -Esters

    PubMed Central

    Khumsubdee, Sakunchai; Burgess, Kevin

    2013-01-01

    As methodology development matures it can be difficult to discern the most effective ways of performing certain transformations from the rest. This review summarizes the most important contributions leading to asymmetric hydrogenations of simple unsaturated-acid and ester substrates, with the objective of highlighting at least the best types of catalysts for each. Achievements in the area are described and these reveal situations where further efforts should be worthwhile, and ones where more research is only likely to give diminishing returns. In general, our conclusions are that the most useful types of catalysts for unsaturated-acids and -esters tend to be somewhat different, simple substrates have been studied extensively, and the field is poised to address more complex reactions. These could be ones involving alternative, particularly cyclic, structures, chemoselectivity issues, and more complex substrate stereochemistries. PMID:24729943

  15. Determination of some aliphatic carboxylic acids in anaerobic digestion process waters by ion-exclusion chromatography with conductimetric detection on a weakly acidic cation-exchange resin column

    Microsoft Academic Search

    Kazuaki Ito; Yohichi Takayama; Mikaru Ikedo; Masanobu Mori; Hiroshi Taoda; Qun Xu; Wenzhi Hu; Hiroshi Sunahara; Tsuneo Hayashi; Shinji Sato; Takeshi Hirokawa; Kazuhiko Tanaka

    2004-01-01

    The determination of seven aliphatic carboxylic acids, formic, acetic, propionic, isobutyric, n-butyric, isovaleric and n-valeric acids in anaerobic digestion process waters was examined using ion-exclusion chromatography with conductimetric detection. The analysis of these biologically important carboxylic acids is necessary as a measure for evaluating and controlling the process. The ion-exclusion chromatography system employed consisted of polymethacrylate-based weakly acidic cation-exchange resin

  16. Encapsulated hydrogen-bonded dimers of amide and carboxylic acid

    NASA Astrophysics Data System (ADS)

    Tzeli, Demeter; Petsalakis, Ioannis D.; Theodorakopoulos, Giannoula; Ajami, Dariush; Jiang, Wei; Rebek, Julius

    2012-10-01

    A theoretical DFT study on benzamide and benzoic acid dimers in the gas phase and encapsulated in two cages of different size has been carried out in order to explain experimental observations regarding the % distributions of the different dimers formed in these cages. The results show that the % distribution of encapsulated dimers in the larger cage is similar to the gas-phase distribution. In the smaller cage interaction of amide with the cage leads to lower dimerization energy and a reduced % fraction of the corresponding encapsulated dimers, compared to the large cage % distribution, in agreement with experiment.

  17. Iron-catalyzed decarboxylative alkenylation of cycloalkanes with arylvinyl carboxylic acids via a radical process

    PubMed Central

    Zhao, Jiancan; Fang, Hong

    2013-01-01

    Summary A Fe(acac)3-catalyzed decarboxylative coupling of 2-(aryl)vinyl carboxylic acids with cycloalkanes was developed by using DTBP as an oxidant through a radical process. This reaction tolerates a wide range of substrates, and products are obtained in good to excellent yields (71–95%). The reaction also shows excellent stereoselectivity, and only trans-isomers are obtained. PMID:24062833

  18. Extraction of rare earths and yttrium with high molecular weight carboxylic acids

    Microsoft Academic Search

    D. K. Singh; H. Singh; J. N. Mathur

    2006-01-01

    The extraction behaviour of trivalent rare earths namely La, Ce, Pr, Nd, Sm, Gd, Dy and Ho including Y (M(III), where M represents rare earths and yttrium ) from chloride medium has been studied with the solutions of high molecular weight carboxylic acids such as cekanoic, naphthenic, neo-heptanoic and Versatic 10 in dodecane. The effects of equilibrium pH, extractant concentration,

  19. 13C NMR shielding tensors of carboxyl carbon in amino acids calculated by ONIOM method

    Microsoft Academic Search

    Anmin Zheng; Minghui Yang; Yong Yue; Chaohui Ye; Feng Deng

    2004-01-01

    Our-own-N-layered integrated molecular orbital+molecular mechanics (ONIOM) method has been applied to calculate 13C chemical shift shielding tensor of the carboxyl carbon in three amino acid crystals. The calculated shielding tensors are in good agreement with the experimental values. The root mean square (RMS) has dramatically decreased to 5.9 ppm compared to that (35.5 ppm) previously reported in reference. The present

  20. Process for the generation of .alpha., .beta.-unsaturated carboxylic acids and esters using niobium catalyst

    DOEpatents

    Gogate, Makarand Ratnakav (Durham, NC); Spivey, James Jerome (Cary, NC); Zoeller, Joseph Robert (Kingsport, TN)

    1999-01-01

    A process using a niobium catalyst includes the step of reacting an ester or carboxylic acid with oxygen and an alcohol in the presence a niobium catalyst to respectively produce an .alpha.,.beta.-unsaturated ester or carboxylic acid. Methanol may be used as the alcohol, and the ester or carboxylic acid may be passed over the niobium catalyst in a vapor stream containing oxygen and methanol. Alternatively, the process using a niobium catalyst may involve the step of reacting an ester and oxygen in the presence the niobium catalyst to produce an .alpha.,.beta.-unsaturated carboxylic acid. In this case the ester may be a methyl ester. In either case, niobium oxide may be used as the niobium catalyst with the niobium oxide being present on a support. The support may be an oxide selected from the group consisting of silicon oxide, aluminum oxide, titanium oxide and mixtures thereof. The catalyst may be formed by reacting niobium fluoride with the oxide serving as the support. The niobium catalyst may contain elemental niobium within the range of 1 wt % to 70 wt %, and more preferably within the range of 10 wt % to 30 wt %. The process may be operated at a temperature from 150 to 450.degree. C. and preferably from 250 to 350.degree. C. The process may be operated at a pressure from 0.1 to 15 atm. absolute and preferably from 0.5-5 atm. absolute. The flow rate of reactants may be from 10 to 10,000 L/kg.sub.(cat) /h, and preferably from 100 to 1,000 L/kg.sub.(cat) /h.

  1. Removal of transition metals from dilute aqueous solution by carboxylic acid group containing absorbent polymers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A new carboxylic acid group containing resin with cation exchange capacity, 12.67 meq/g has been used to remove Cu2+, Co2+ and Ni2+ ions from dilute aqueous solution. The resin has Cu2+, Co2+ and Ni2+ removal capacity, 216 mg/g, 154 mg/g and 180 mg/g, respectively. The selectivity of the resin to ...

  2. Dual SOâ-NOâ concentration reduction by calcium salts of carboxylic acids

    Microsoft Academic Search

    Judith Steciak; Yiannis A. Levendis; Donald L. Wise; Gerard A. Simons

    1995-01-01

    This research continues the investigation of agents that are capable of simultaneously removing SOâ and Moâ from the effluent of coal-fired power plants. The simultaneous removal of SOâ and NOâ by calcium salts of carboxylic acids was evaluated in a laboratory-scale furnace in atmospheres containing 2,000 ppm SOâ, 1,000 ppm NO, 3% Oâ, and 12% COâ at gas temperatures between

  3. 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.

  4. 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.

  5. Evaluation of toxic effects of several carboxylic acids on bacterial growth by toxicodynamic modelling

    PubMed Central

    2011-01-01

    Background Effects of organic acids on microbial fermentation are commonly tested in investigations about metabolic behaviour of bacteria. However, they typically provide only descriptive information without modelling the influence of acid concentrations on bacterial kinetics. Results We developed and applied a mathematical model (secondary model) to capture the toxicological effects of those chemicals on kinetic parameters that define the growth of bacteria in batch cultures. Thus, dose-response kinetics were performed with different bacteria (Leuconostoc mesenteroides, Carnobacterium pisicola, Escherichia coli, Bacillus subtilis and Listonella anguillarum) exposed at increasing concentrations of individual carboxylic acids (formic, acetic, propionic, butyric and lactic). In all bioassays the acids affected the maximum bacterial load (Xm) and the maximum growth rate (vm) but only in specific cases the lag phase (?) was modified. Significance of the parameters was always high and in all fermentations the toxicodynamic equation was statistically consistent and had good predictability. The differences between D and L-lactic acid effects were significant for the growth of E. coli, L. mesenteroides and C. piscicola. In addition, a global parameter (EC50,?) was used to compare toxic effects and provided a realistic characterization of antimicrobial agents using a single value. Conclusions The effect of several organic acids on the growth of different bacteria was accurately studied and perfectly characterized by a bivariate equation which combines the basis of dose-response theory with microbial growth kinetics (secondary model). The toxicity of carboxylic acids was lower with the increase of the molecular weight of these chemicals. PMID:22118421

  6. 2-Alkyl-4-hydroxymethylfuran-3-carboxylic acids, antibiotic production inducers discovered by Streptomyces coelicolor genome mining

    PubMed Central

    Corre, Christophe; Song, Lijiang; O'Rourke, Sean; Chater, Keith F.; Challis, Gregory L.

    2008-01-01

    All of the genetic elements necessary for the production of the antibiotic methylenomycin (Mm) and its regulation are contained within the 22-kb mmy-mmf gene cluster, which is located on the 356-kb linear plasmid SCP1 of Streptomyces coelicolor A3(2). A putative operon of 3 genes within this gene cluster, mmfLHP, was proposed to direct the biosynthesis of an A-factor-like signaling molecule, which could play a role in the regulation of Mm biosynthesis. The mmfLHP operon was expressed under the control of its native promoter in S. coelicolor M512, a host lacking the SCP1 plasmid, and the ability to produce prodiginine and actinorhodin antibiotics. Comparative metabolic profiling led to the identification and structure elucidation of a family of 5 new 2-alkyl-4-hydroxymethylfuran-3-carboxylic acids (AHFCAs), collectively termed Mm furans (MMFs), as the products of the mmfLHP genes. MMFs specifically induce the production of the Mm antibiotics in S. coelicolor. Comparative genomics analyses and searches of the natural product chemistry literature indicated that other streptomycetes may produce AHFCAs, suggesting that they could form a general class of antibiotic biosynthesis inducers in Streptomyces species, with analogous functions to the better known ?-butyrolactone regulatory molecules. PMID:18988741

  7. One-Pot Synthesis of Esters of Cyclopropane Carboxylic Acids via Tandem Vicarious Nucleophilic Substitution-Michael Addition Process.

    PubMed

    M?kosza, Mieczys?aw; Bester, Karol; Cmoch, Piotr

    2015-06-01

    ?-Chlorocarbanions generated via base-induced vicarious nucleophilic substitution reaction of alkyl dichloroacetates with nitroarenes react with Michael acceptors to give esters of cyclopropane carboxylic acids substituted with p-nitroaromatic rings. PMID:25950949

  8. Structure and growth behavior of centimeter-sized helical oleate assemblies formed with assistance of medium-length carboxylic acids.

    PubMed

    Kageyama, Yoshiyuki; Ikegami, Tomonori; Hiramatsu, Natsuko; Takeda, Sadamu; Sugawara, Tadashi

    2015-04-29

    The nonequilibrium organization of self-assemblies from small building-block molecules offers an attractive and essential means to develop advanced functional materials and to understand the intrinsic nature of life systems. Fatty acids are well-known amphiphiles that form self-assemblies of several shapes. Here, we found that the lengths of helical structures of oleic acid formed in a buffered aqueous solution are dramatically different by the presence or absence of certain amphiphilic carboxylic acids. For example, under the coexistence of a small amount of N-decanoyl-l-alanine, we observed the formation of over 1 centimeter-long helical assemblies of oleate with a regular pitch and radius, whereas mainly less than 100 ?m-long helices formed without this additive. Such long helical assemblies are unique in terms of their highly dimensional helical structure and growth dynamics. Results from the real-time observation of self-assembly formation, site-selective small-angle X-ray scattering, high-performance liquid chromatography analysis, and pH titration experiments suggested that the coexisting carboxylates assist in elongation by supplying oleate molecules to a scaffold for oleate helical assembly. PMID:25781720

  9. Potential correlation between carboxylic acid metabolites in Biomphalaria alexandrina snails after exposure to Schistosoma mansoni infection.

    PubMed

    Abou Elseoud, Salwa M F; Abdel Fattah, Nashwa S; Ezz El Din, Hayam M; Abdel Al, Hala; Mossalem, Hanan; Elleboudy, Noha

    2012-06-01

    Carboxylic acids play an important role in both aerobic and anaerobic metabolic pathways of both the snail and the parasite. Monitoring the effects of infection by schistosome on Biomphalaria alexandrina carboxylic acids metabolic profiles represents a promising additional source of information about the state of metabolic system. We separated and quantified pyruvic, fumaric, malic, oxalic, and acetic acids using ion-suppression reversed-phase high performance liquid chromatography (HPLC) to detect correlations between these acids in both hemolymph and digestive gland gonad complex (DGG's) samples in a total of 300 B. alexandrina snails (150 infected and 150 controls) at different stages of infection. The results showed that the majority of metabolite pairs did not show significant correlations. However, some high correlations were found between the studied acids within the control group but not in other groups. More striking was the existence of reversed correlations between the same acids at different stages of infection. Some possible explanations of the underlying mechanisms were discussed. Ultimately, however, further data are required for resolving the responsible regulatory events. These findings highlight the potential of metabolomics as a novel approach for fundamental investigations of host-pathogen interactions as well as disease surveillance and control. PMID:22711922

  10. Synthesis and pharmacochemical study of new Cu(II) complexes with thiophen-2-yl saturated and ?,?-unsaturated substituted carboxylic acids

    Microsoft Academic Search

    D. Panagoulis; E. Pontiki; E. Skeva; C. Raptopoulou; S. Girousi; D. Hadjipavlou-Litina; C. Dendrinou-Samara

    2007-01-01

    Copper complexes with thiophen-2-yl saturated and ?,?-unsaturated carboxylic acids as ligands were prepared, characterized and pharmacochemically studied. The available evidence supports a dimeric structure for the complexes of the general formula [Cu2(L)4(MeOH)2] where L are the anions of thiophene 2-carboxylic acid (HL1), 2-(thiophen-2-yl)-acetic acid (HL2), 3-thiophen-2-yl-acrylic acid (HL3), 2-phenyl-3-thiophen-2-yl-acrylic acid (HL4) respectively. The crystal structure of [Cu2(L1)4(MeOH)2] (2) was determined

  11. Human ? 1 -pyrroline-5-carboxylate synthase: function and regulation

    Microsoft Academic Search

    C.-A. A. Hu; S. Khalil; S. Zhaorigetu; Z. Liu; M. Tyler; G. Wan; D. Valle

    2008-01-01

    Mammalian ?1-pyrroline-5-carboxylate synthase (P5CS) is a bifunctional ATP- and NAD(P)H-dependent mitochondrial enzyme that catalyzes\\u000a the coupled phosphorylation and reduction-conversion of l-glutamate to P5C, a pivotal step in the biosynthesis of l-proline, l-ornithine and l-arginine. Previously, we reported cloning and characterization of two P5CS transcript variants generated by exon sliding\\u000a that encode two protein isoforms differing only by a two amino

  12. A Novel Aromatic Carboxylic Acid Inactivates Luciferase by Acylation of an Enzymatically Active Regulatory Lysine Residue

    PubMed Central

    Nakagomi, Madoka; Fujimaki, Nobuko; Ito, Ai; Toda, Takahiro; Fukasawa, Hiroshi; Shudo, Koichi; Tomita, Ryoichi

    2013-01-01

    Firefly luciferase (Luc) is widely used as a reporter enzyme in cell-based assays for gene expression. A novel aromatic carboxylic acid, F-53, reported here for the first time, substantially inhibited the enzymatic activity of Luc in a Luc reporter screening. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and tandem mass spectrometry (MS/MS) analyses showed that F-53 modifies Luc at lysine-529 via amidation of the F-53 carboxyl group. The lysine-529 residue of Luc, which plays a regulatory catalytic role, can be acetylated. Luc also has a long-chain fatty acyl-CoA synthase activity. An in vitro assay that involved both recombinant Luc and mouse liver microsomes identified F-53-CoA as the reactive form produced from F-53. However, whereas the inhibitory effect of F-53 is observed in Hela cells that transiently expressed Luc, it is not observed in an in vitro assay that involves recombinant Luc alone. Therefore, insights into the activities of certain mammalian transferases can be translated to better understand the acylation by F-53. The insights from this study about the novel inhibitory modification mechanism might help not only to avoid misinterpretation of the results of Luc-based reporter screening assays but also to explain the pharmacological and toxicological effects of carboxylic acid-containing drugs. PMID:24066181

  13. Consideration of Thiol and Carboxylic Acid Chemisorption on Various Electrode Materials by Thermodynamic Calculation

    NASA Astrophysics Data System (ADS)

    Yagyu, Shinjiro; Yoshitake, Michiko; Chikyow, Toyohiro

    Thiols and carboxylic acids are important molecules for the anchor of Self-Assemble Monolayer (SAM) on metal surface in organic devices. In order to consider whether carboxylate or thiolate adsorbs on various metals, adsorption energies of methanthiolate and acetate on various metals were thermodynamically calculated using basic quantities of formation enthalpies of metal oxides (Hf(MxOy)) and metal sulfide (Hf(MxSy)). The calculations were carried out for the adsorption on clean, O adsorbed, and OH adsorbed surface. The results suggested that methanethiolate adsorbs on all clean metals, and on O and OH adsorbed metals except Ti and Al (the high Hf(MxOy) metals). On the other hand, acetate adsorbed on all O and OH covered metals, and the clean metals except Au, Ag and Pt (the low Hf(MxOy) metals). As the modification of electrodes using SAM is carried out under atmospheric and liquid conditions, it is considered that thiols prefer the adsorption on the low Hf(MxOy) metals to the high Hf(MxOy) metals, on the contrary, carboxylic acids prefer the adsorption on the high Hf(MxOy) metals to the low Hf(MxOy) metals.

  14. A sensitive and selective imprinted solid phase extraction coupled to HPLC for simultaneous detection of trace quinoxaline-2-carboxylic acid and methyl-3-quinoxaline-2-carboxylic acid in animal muscles.

    PubMed

    Duan, Zhenjuan; Yi, Jianghua; Fang, Guozhen; Fan, Lipeng; Wang, Shuo

    2013-08-15

    A new molecularly imprinted polymer (MIP), selective for major metabolites of quinoxaline-1,4-dioxides, was prepared through bulk polymerisation using quinoxaline-2-carboxylic acid (QCA) as template, diethylaminoethylmethacrylate as functional monomer and ethylene glycol dimethacrylate as cross-linker in tetrahydrofuran. The synthesised MIP was characterised by Fourier transform infrared and adsorption experiments. MIP exhibited high affinity, fast kinetics for QCA and good selectivity for QCA and methyl-3-quinoxaline-2-carboxylic acid (MQCA). MIP obtained was used as a selective sorbent for molecularly imprinted solid phase extraction (MISPE) coupled with HPLC to detect QCA and MQCA. Under the optimal conditions, the limits of detection (S/N=3) of porcine, chicken and fish muscles were 0.1, 0.3, 0.1 ?g/kg for QCA and 0.2, 0.3, 0.1 ?g/kg for MQCA, respectively and good recoveries were obtained in the range from 60.0 to 119.4%. These results indicated the MISPE-HPLC procedure could be successfully used for the determination QCA and MQCA in animal muscles. PMID:23561106

  15. Bio-inspired amino acid oxidation by a non-heme iron catalyst modeling the action of 1-aminocyclopropane-1-carboxylic acid oxidase.

    PubMed

    Baráth, Gábor; Kaizer, József; Pap, József Sándor; Speier, Gábor; El Bakkali-Taheri, Nadia; Simaan, A Jalila

    2010-10-21

    In this communication we describe the first example of a biomimetic mononuclear iron complex, [Fe(III)(Salen)Cl] (Salen = N,N'-bis(salicylidene)-ethylenediaminato), that highly selectively and efficiently catalyzes the oxidation of 1-aminocyclopropane-1-carboxylic acid (ACCH), ?-aminoisobutyric acid (AIBH), and alanine (ALAH) to ethylene or the corresponding carbonyl compounds, mimicking the action of the non-heme iron enzyme 1-aminocyclopropane-1-carboxylic acid oxidase (ACCO). PMID:20830340

  16. Ruthenium(II) multi carboxylic acid complexes: chemistry and application in dye sensitized solar cells.

    PubMed

    Shahroosvand, Hashem; Nasouti, Fahimeh; Sousaraei, Ahmad

    2014-04-01

    Novel ruthenium multi carboxylic complexes (RMCCs) have been synthesized by using ruthenium nitrosyl nitrate, 1,2,4,5-benzenetetracarboxylic acid (H4btec) and 4,7-diphenyl-1,10-phenanthroline (BPhen) as photosensitizers for titanium dioxide semiconductor solar cells. The complexes were characterized by (1)H-NMR, FT-IR, UV-Vis, ICP and CHN analyses. The reaction details and features were then described. SEM analysis revealed that the penetration of dyes into the pores of the nanocrystalline TiO2 surface was improved by increasing the number of btec units. The solar energy to electricity conversion efficiency of complexes shows that the number of attached carboxylates on a dye has an influence on the photoelectrochemical properties of the dye-sensitized electrode. An incident photon-to-current conversion efficiency (IPCE) of 13% at 510 nm was obtained for ruthenium complexes with three btec units. PMID:24500312

  17. Water-enhanced solubility of carboxylic acids in organic solvents and its application to extraction processes

    SciTech Connect

    Starr, J.N. (Abbott Labs., North Chicago, IL (United States)); King, C.J. (Lawrence Berkeley Lab., CA (United States))

    1992-11-01

    This paper reports on solubilities of carboxylic acids in certain organic solvents which increase sharply as the concentration of water in the solvent increases. This phenomenon leads to a method of regeneration for solvent-extraction processes whereby coextracted water is selectively removed from the extract, such as by stripping, thereby precipitating the acid. The removal of a minor constituent to cause precipitation reduces energy consumption, in contrast with bulk removal of solvent. Solubilities of fumaric acid were measured in a number of organic solvents, with varying amounts of water in the organic phase. Cyclohexanone and methylcyclohexanone were chosen as solvents for which detailed solid-liquid and liquid-liquid equilibria were measured for adipic, fumaric, and succinic acids in the presence of varying concentrations of water, at both 25 and 45[degrees]C. Batch precipitation experiments were performed to demonstrate the processing concept and determine the relative volatility of water to solvent in the presence of carbon.

  18. Simultaneous and sensitive analysis of aliphatic carboxylic acids by ion-chromatography using on-line complexation with copper(II) ion.

    PubMed

    Kemmei, Tomoko; Kodama, Shuji; Yamamoto, Atsushi; Inoue, Yoshinori; Hayakawa, Kazuichi

    2015-01-01

    A new approach to ion chromatography is proposed to improve the UV detection of aliphatic carboxylic acids separated by anion-exchange chromatography. When copper(II) ion added to the mobile phase, it forms complexes with carboxylic acids that can be detected at 240 nm. The absorbance was found to increase with increasing copper(II) ion concentration. The retention times of ?-hydroxy acids were also found to depend on the copper(II) ion concentration. Addition of acetonitrile to the mobile phase improved the separation of aliphatic carboxylic acids. The detection limits of the examined carboxylic acids (formate, glycolate, acetate, lactate, propionate, 3-hydroxypropionate, n-butyrate, isobutyrate, n-valerate, isovalerate, n-caproate) calculated at S/N=3 ranged from 0.06 to 3 ?M. The detector signal was linear over three orders of magnitude of carboxylic acid concentration. The proposed method was successfully applied to analyze aliphatic carboxylic acids in rainwater and bread. PMID:25523885

  19. Enantiopure synthesis of dihydrobenzo[1,4]-oxazine-3-carboxylic acids and a route to benzoxazinyl oxazolidinones.

    PubMed

    Malhotra, Rajesh; Dey, Tushar K; Basu, Sourav; Hajra, Saumen

    2015-03-21

    A two step protocol is developed for the efficient synthesis of enantiopure N-Boc-dihydrobenzo[b]-1,4-oxazine-3-carboxylic acids 4 from serine derived cyclic sulfamidate via intramolecular arylamination. The RuPhos Palladacycle along with additional RuPhos ligand is found to be an efficient catalyst for the arylamination of ?-(2-bromoaryloxy)amino acids 3 to provide easy and direct access to a variety of dihydrobenzo[b]-1,4-oxazine-3-carboxylic acids 4 with complete retention of enantiopurity in moderate to high yields. Dihydrobenzo[b]-1,4-oxazine-3-carboxylic acids are not only important unnatural amino acids, but are key precursors for the synthesis of important compounds such as benzoxazinyl oxazolidinones. A general approach for the synthesis of benzoxazinyl oxazolidinone is presented. PMID:25645529

  20. Surface functional groups on acid-activated nutshell carbons

    Microsoft Academic Search

    Christopher A. Toles; Wayne E. Marshall; Mitchell M. Johns

    1999-01-01

    Nutshells from agriculturally important nut crops (almond, black walnut, English walnut, macadamia nut and pecan) were converted to granular activated carbon using phosphoric acid activation in nitrogen or air. Surface functional groups (carbonyl, phenols, lactones, carboxyl) were quantified by titration with bases of different ionization potential. The degree of copper uptake was correlated with the presence of various functional groups

  1. Synthesis, Characterization, Semiempirical and Biological Activities of Organotin(IV) Carboxylates with 4-Piperidinecarboxylic Acid

    PubMed Central

    Sharma, Saroj K.; Qanungo, Kushal; Shahid, Muhammad

    2014-01-01

    Organotin (IV) carboxylates with the general formulae R2Sn(Cl)L [R?=?Me (1), n-Bu (2), Ph (3)] and R3SnL [R?=?Me (4), Ph (5)] have been synthesized by the reaction of 4-piperidinecarboxylic acid (HL) with KOH and R2SnCl2 (R?=?Me, n-Bu, Ph)/R3SnCl (R?=?Me, Ph) in methanol under stirring conditions. The metal ligand binding site, structure, and stability of complexes have been verified by FT-IR, (1H, 13C) NMR, EI-MS technique, and semiempirical study. The FT-IR data indicate the bidentate chelating mode of the carboxylate ligand which is also confirmed by semiempirical study. In solution state, five and four coordinated geometry around tin was confirmed by NMR spectroscopy. The EI-MS data agreed well with the molecular structure of the complexes. Thermodynamic parameters and molecular descriptors were calculated by using semiempirical PM3 method. HOMO-LUMO calculations show that chlorodiorganotin complexes are more susceptible to nucleophilic attack as compared to triorganotin complexes. Computed negative heat of formation indicates that complexes 1–4 are thermodynamically stable. The organotin(IV) carboxylates displayed powerful antimicrobial activities against various strains of bacteria and fungi and their minimal inhibitory concentration were also evaluated. The complexes exhibited comparatively higher hemolytic activity as compared to free ligand. PMID:25548551

  2. Effects of the proline analog L-thiazolidine-4-carboxylic acid on proline metabolism

    SciTech Connect

    Elthon, T.E.; Stewart, C.R.

    1984-02-01

    The effect of various proline analogs on proline oxidation in mitochondria isolated from etiolated barley (Hordeum vulgare) shoots was investigated. Of the analogs tested, only L-thiazolidine-4-carboxylic acid (T4C) was an effective inhibitor. T4C (1 millimolar) inhibited proline (10 millimolar) -dependent O/sub 2/ uptake an average of 67%. T4C was also oxidized to some degree (12.9 nanoatoms oxygen per minute per milligram protein for 10 millimolar). The effect of T4C on the oxidation of other mitochondrial substrates was also tested. T4C inhibited ..delta../sup 1/-pyrrolidine-5-carboxylic acid-dependent oxygen uptake slightly (13%), the oxidation of malate plus pyruvate even less (6%), and stimulated the oxidation of succinate (+11%), exogenous NADH (+19%), and citrate (+20%). Thus, inhibition by T4C in mitochondria is relatively specific to proline oxidation. T4C was found to inhibit proline dehydrogenase and not the transport of proline into the matrix. The effect of T4C on proline metabolism in detached green barley leaves was investigated. T4C inhibited proline oxidation in turgid leaves, increasing the proline content of these leaves slightly. In wilted leaves (that are synthesizing proline rapidly), T4C inhibited proline synthesis, which resulted in a decrease in the proline content of the leaves. ..delta../sup 1/-pyrrolidine-5-carboxylic acid reductase (the last enzyme in proline synthesis) was not inhibited by T4C, and thus T4C's influence is prior to that step of the synthetic pathway. T4C had no influence on the incorporation of proline into protein.

  3. The amino acid sequences of the carboxyl termini of human and mouse hepatic lipase influence cell surface association

    Microsoft Academic Search

    Robert J. Brown; Joshua R. Schultz; Kerry W. S. Ko; John S. Hill; Tanya A. Ramsamy; Ann L. White; Daniel L. Sparks; Zemin Yao

    2003-01-01

    Human hepatic lipase (hHL) mainly exists cell sur- face bound, whereas mouse HL (mHL) circulates in the blood stream. Studies have suggested that the carboxyl terminus of HL mediates cell surface binding. We prepared recombinant hHL, mHL, and chimeric proteins (hHLmt and mHLht) in which the carboxyl terminal 70 amino acids of hHL were ex- changed with the corresponding sequence

  4. Orthogonal protecting groups for N(alpha)-amino and C-terminal carboxyl functions in solid-phase peptide synthesis.

    PubMed

    Albericio, F

    2000-01-01

    For the controlled synthesis of even the simplest dipeptide, the N(alpha)-amino group of one of the amino acids and the C-terminal carboxyl group of the other should both be blocked with suitable protecting groups. Formation of the desired amide bond can now occur upon activation of the free carboxyl group. After coupling, peptide synthesis can be continued by removal of either of the two protecting groups and coupling with the free C-terminus or N(alpha)-amino group of another protected amino acid. When three functional amino acids are present in the sequence, the side chain of these residues also has to be protected. It is important that there is a high degree of compatibility between the different types of protecting groups such that one type may be removed selectively in the presence of the others. At the end of the synthesis, the protecting groups must be removed to give the desired peptide. Thus, it is clear that the protection scheme adopted is of the utmost importance and makes the difference between success and failure in a given synthesis. Since R. B. Merrifield introduced the solid-phase strategy for the synthesis of peptides, this prerequisite has been readily accepted. This strategy is usually carried out using two main protection schemes: the tert-butoxycarbonyl/benzyl and the 9-flourenylmethoxycarbonyl/tert-butyl methods. However, for the solid-phase preparation of complex or fragile peptides, as well as for the construction of libraries of peptides or small molecules using a combinatorial approach, a range of other protecting groups is also needed. This review summarizes other protecting groups for both the N(alpha)-amino and C-terminal carboxyl functions. PMID:11074410

  5. Synthesis of 5-arylpyrimidine-2-carboxylic acids and the liquid-crystal characteristics of their aryl esters

    SciTech Connect

    Mikhaleva, M.A.; Kolesnichenko, G.A.; Rubina, K.I.; Gol'dberg, Yu.Sh.; Savel'ev, V.A.; Leitis, L.Ya.; Shimanskaya, M.V.; Mamaev, V.P.

    1986-09-01

    5-Arylpyrimidine-2-carboxylic acids were synthesized by the hydrolysis of 5-aryl-2-cyanopyrimidines and the oxidation of 5-aryl-2-styrylpyrimidines under the conditions of phase-transfer catalysis. The aryl esters of the acids were obtained, and their liquid-crystal characteristics were studied. The p-substituted aryl esters of 5-phenylpyrimidine-2-carboxylic acid do not exhibit mesomorphism, but the introduction of a butyloxy group at the p position of the phenyl residue leads to the appearance of nematic characteristics. Aryl 5-phenylpyrimidinylcarbonyloxy-benzoates are nematic liquid crystals with a thermally stable meso phase and an existence range of 50-80/sup 0/C.

  6. Wind tunnel investigations on the retention of carboxylic acids during riming

    NASA Astrophysics Data System (ADS)

    Jost, Alexander; Szakáll, Miklós; Diehl, Karoline; Mitra, Subir K.; Borrmann, Stephan

    2015-04-01

    In mid-latitudes, precipitation is mainly initiated via the ice phase in mixed phase clouds. In such clouds the ice particles grow to precipitation sizes at the expense of liquid drops through riming which means that supercooled droplets collide with ice particles and subsequently freeze. Water-soluble trace substances present in the liquid phase might remain only fractionally in the ice phase after freezing. This fractionation is called retention and is an important ratio which quantifies the partitioning of atmospheric trace substances between the phases. Laboratory experiments were carried out at the Mainz vertical wind tunnel to determine the retention of lower mono- and di-carboxylic acids during riming. Due to their low molecular weight and their polarity these acids are water-soluble. In the atmosphere formic acid and acetic acid are the most abundant mono-carboxylic acids in the gas and aqueous phase, thus, they represent the major fraction of carboxylic acids in cloud water. Oxalic and malonic acid are common coatings on aerosol particles because of their relatively low saturation vapor pressure. These di-carboxylic acids might therefore promote the aerosol particles to act as cloud condensation nuclei and additionally contribute to the aqueous phase chemistry in cloud droplets. The conditions during the riming experiments in the wind tunnel were similar to those in atmospheric mixed phase clouds, i.e. temperatures from -18°C to -6 °C, liquid water contents between 0.5 and 1.5 g/m3, and liquid drop radii between 10 and 20 ?m. The liquid phase concentrations ranged from 3 to 5 mg/l (4.1 < pH < 4.5). As rime collectors captively floating ice particles and quasi-floating snowflakes with diameters between 0.6 and 1.5 cm were used. The wind speed in the vertical wind tunnel was very close to the terminal velocities of the rime collectors, thus, the ventilation during riming was in the same order of magnitude as under atmospheric riming conditions. After riming the collectors were removed from the wind tunnel, their melt water was analyzed by ion chromatography and the retention coefficients, i.e. the fractions of the species which remained in the ice phase were determined. Average retention coefficients of formic acid and acetic acid were 0.73 ± 0.07 and 0.62 ± 0.12, respectively; both oxalic and malonic acids had average retention coefficients of 0.98 ± 0.04. These variations can be explained by the fact that retention depends on the one hand on the dissociation state of the substance together with its solubility (described by the effective Henry's law constant) and on the other hand on the latent heat removal from the collector to the environment. This is affected by ventilation, shape of the rime collector, liquid water content, and droplet size.

  7. Incorporation of C14 From Carbon Dioxide into Sugar Phosphates, Carboxylic Acids, and Amino Acids by Clostridium thermoaceticum

    PubMed Central

    Ljungdahl, Lars; Wood, Harland G.

    1965-01-01

    Ljungdahl, Lars (Western Reserve University, Cleveland, Ohio), and Harland G. Wood. Incorporation of C14 from carbon dioxide into sugar phosphates, carboxylic acids, and amino acids by Clostridium thermoaceticum. J. Bacteriol. 89:1055–1064. 1965.—The mechanism of synthesis of acetate from carbon dioxide by Clostridium thermoaceticum was investigated by incubating cells with glucose or xylose in the presence of C14O2. Sugar phosphates, amino acids, and carboxylic acids were isolated and the specific radioactivities were determined; the distributions of C14 were also determined in some of the compounds. Only fructose-1,6-diphosphate, formate, and lactate had higher specific activities than the acetate. The specific activities and distribution of C14 in the fructose-6-phosphate and ribose-5-phosphate were such that we conclude that the synthesis of acetate does not occur via a pathway involving the sugar phosphates as direct intermediates. Likewise, it is shown that pathways including lactate, aspartate, serine, glycine, malate, and succinate are not of importance in the synthesis of acetate from CO2. The methyl group of free methionine was unlabeled and is not a precursor of the methyl group of acetate. PMID:14276095

  8. Preferential interaction of Na+ over K+ with carboxylate-functionalized silver nanoparticles.

    PubMed

    Pokhrel, Lok R; Andersen, Christian P; Rygiewicz, Paul T; Johnson, Mark G

    2014-08-15

    Elucidating mechanistic interactions between monovalent cations (Na(+)/K(+)) and engineered nanoparticle surfaces to alter particle stability in polar media have received little attention. We investigated relative preferential interaction of Na(+) and K(+) with carboxylate-functionalized silver nanoparticles (carboxylate-AgNPs) to determine if interaction preference followed the Hofmeister series (Na(+)>K(+)). We hypothesized that Na(+) will show greater affinity than K(+) to pair with carboxylates on AgNP surfaces, thereby destabilizing the colloidal system. Destabilization upon Na(+) or K(+) interacting with carboxylate-AgNPs was evaluated probing changes in multiple physicochemical characteristics: surface plasmon resonance/optical absorbance, electrical conductivity, pH, hydrodynamic diameter, electrophoretic mobility, surface charge, amount of Na(+)/K(+) directly associated with AgNPs, and Ag(+) dissociation kinetics. We show that Na(+) and K(+) react differently, indicating local Na(+) pairing with carboxylates on AgNP surfaces is kinetically faster and remarkably favored over K(+), thus supporting Hofmeister ordering. Our results suggest that AgNPs may transform into micron-size aggregates upon release into aqueous environments and that the fate of such aggregates may need consideration when assessing environmental risk. PMID:24840275

  9. Solubility of Small-Chain Carboxylic Acids in Supercritical Carbon Dioxide

    DOE PAGESBeta

    Sparks, Darrell L.; Estevez, L. Antonio; Hernandez, Rafael; McEwen, Jason; French, Todd

    2010-11-11

    The solubility of heptanoic acid and octanoic acid in supercritical carbon dioxide has been determined at temperatures of (313.15, 323.15, and 333.15) K over a pressure range of (8.5 to 30.0) MPa, depending upon the solute. The solubility of heptanoic acid ranged from a solute concentration of (0.08 ± 0.03) kg • m -3 (T = 323.15 K, p = 8.5 MPa) to (147 ± 0.2) kg • m -3 (T = 323.15 K, p = 20.0 MPa). The lowest octanoic acid solubility obtained was a solute concentration of (0.40 ± 0.1) kg • m -3 (T = 333.15 K, p = 10.0 MPa), while the highest solute concentration was (151 ± 2) kg • m -3 (T = 333.15 K, p = 26.7 MPa). Additionally, solubility experiments were performed for nonanoic acid in supercritical carbon dioxide at 323.15 K and pressures of (10.0 to 30.0) MPa to add to the solubility data previously published by the authors. In general, carboxylic acid solubility increased with increasing solvent density. The results also showed that the solubility of the solutes decreased with increasing molar mass at constant supercritical-fluid density. Additionally, the efficacy of Chrastil's equation and other density-based models was evaluated for each fatty acid.

  10. Solubility of Small-Chain Carboxylic Acids in Supercritical Carbon Dioxide

    DOE PAGESBeta

    Sparks, Darrell L.; Estevez, L. Antonio; Hernandez, Rafael; McEwen, Jason; French, Todd

    2010-11-11

    The solubility of heptanoic acid and octanoic acid in supercritical carbon dioxide has been determined at temperatures of (313.15, 323.15, and 333.15) K over a pressure range of (8.5 to 30.0) MPa, depending upon the solute. The solubility of heptanoic acid ranged from a solute concentration of (0.08 ± 0.03) kg • m -3 (T = 323.15 K, p = 8.5 MPa) to (147 ± 0.2) kg • m -3 (T = 323.15 K, p = 20.0 MPa). The lowest octanoic acid solubility obtained was a solute concentration of (0.40 ± 0.1) kg • m -3 (T = 333.15 K,more »p = 10.0 MPa), while the highest solute concentration was (151 ± 2) kg • m -3 (T = 333.15 K, p = 26.7 MPa). Additionally, solubility experiments were performed for nonanoic acid in supercritical carbon dioxide at 323.15 K and pressures of (10.0 to 30.0) MPa to add to the solubility data previously published by the authors. In general, carboxylic acid solubility increased with increasing solvent density. The results also showed that the solubility of the solutes decreased with increasing molar mass at constant supercritical-fluid density. Additionally, the efficacy of Chrastil's equation and other density-based models was evaluated for each fatty acid.« less

  11. Novel blue-emitting carboxyl-functionalized poly(arylene ether nitrile)s with excellent thermal

    E-print Network

    Lin, Zhiqun

    Novel blue-emitting carboxyl-functionalized poly(arylene ether nitrile)s with excellent thermal*b A series of novel carboxyl-functionalized poly(arylene ether nitrile)s (CPAENs) were synthesized via(arylene ether)s such as poly(arylene ether sulfone)s, poly(arylene ether ketone)s, poly(arylene ether nitrile

  12. Retention of heavy metals by carboxyl functional groups of biochars in small arms range soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Long-term effectiveness of biochar for heavy metal stabilization depends upon biochar’s sorptive property and recalcitrance in soil. To understand the role of carboxyl functional groups on heavy metal stabilization, cottonseed hull biochar and flax shive steam activated biochar having low O/C ratio...

  13. The Biosynthetic Pathway of Indole-3-Carbaldehyde and Indole-3-Carboxylic Acid Derivatives in Arabidopsis1[W

    PubMed Central

    Böttcher, Christoph; Chapman, Alexandra; Fellermeier, Franziska; Choudhary, Manisha; Scheel, Dierk; Glawischnig, Erich

    2014-01-01

    Indolic secondary metabolites play an important role in pathogen defense in cruciferous plants. In Arabidopsis (Arabidopsis thaliana), in addition to the characteristic phytoalexin camalexin, derivatives of indole-3-carbaldehyde (ICHO) and indole-3-carboxylic acid (ICOOH) are synthesized from tryptophan via the intermediates indole-3-acetaldoxime and indole-3-acetonitrile. Based on feeding experiments combined with nontargeted metabolite profiling, their composition in nontreated and silver nitrate (AgNO3)-treated leaf tissue was comprehensively analyzed. As major derivatives, glucose conjugates of 5-hydroxyindole-3-carbaldehyde, ICOOH, and 6-hydroxyindole-3-carboxylic acid were identified. Quantification of ICHO and ICOOH derivative pools after glucosidase treatment revealed that, in response to AgNO3 treatment, their total accumulation level was similar to that of camalexin. ARABIDOPSIS ALDEHYDE OXIDASE1 (AAO1), initially discussed to be involved in the biosynthesis of indole-3-acetic acid, and Cytochrome P450 (CYP) 71B6 were found to be transcriptionally coexpressed with camalexin biosynthetic genes. CYP71B6 was expressed in Saccharomyces cerevisiae and shown to efficiently convert indole-3-acetonitrile into ICHO and ICOOH, thereby releasing cyanide. To evaluate the role of both enzymes in the biosynthesis of ICHO and ICOOH derivatives, knockout and overexpression lines for CYP71B6 and AAO1 were established and analyzed for indolic metabolites. The observed metabolic phenotypes suggest that AAO1 functions in the oxidation of ICHO to ICOOH in both nontreated and AgNO3-treated leaves, whereas CYP71B6 is relevant for ICOOH derivative biosynthesis specifically after induction. In summary, a model for the biosynthesis of ICHO and ICOOH derivatives is presented. PMID:24728709

  14. 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.

  15. A supported polymeric liquid membrane process for removal of carboxylic acids from a waste stream

    SciTech Connect

    Ho, S.V.

    1999-12-31

    The removal or elimination of organic residues from aqueous waste streams represents a major need in the chemical industry. The authors have developed a new class of membrane called supported polymeric liquid membranes that are capable of removing and concentrating low molecular weight organic compounds from dilute aqueous solutions, especially those that also contain high concentrations of inorganic salts. Attractive features of this membrane process include the ability to recover the contaminants in concentrated form for either recycle or more economical disposal, low pressure (ambient) operation, simple scale-up using commercial hollow fiber modules, and ease of in-situ regeneration of the polymeric liquid. The process has shown treatment feasibility for several types of aqueous waste streams. This paper describes the laboratory development activities for treating a waste stream containing a dilute mixture of C2-C6 carboxylic acids and nitric acid.

  16. Electrochemical properties of polyolefin nonwoven fabric modified with carboxylic acid group for battery separator

    NASA Astrophysics Data System (ADS)

    Choi, Seong-Ho; Kang, Hae-Jeong; Ryu, Eun-Nyoung; Lee, Kwang-Pill

    2001-01-01

    Carboxylic acid group was introduced by radiation-induced grafting of acrylic acid (AAc) onto polyolefine nonwoven fabric (PNF), wherein the PNF comprises at least about 60% of a polyethylene having a melting temperature at ˜132°C and no more than about 40% of a second polypropylene having a lower melting temperature at ˜162°C, for a battery separator. The AAc-grafted PNF was characterized by XPS, SEM, DSC, TGA and porosimeter. The wetting speed, electrolyte retention, electrical resistance, and tensile strength were evaluated after grafting of AAc. It was found that the wetting speed, electrolyte retention, thickness, and ion-exchange capacity increased, whereas the electrical resistance decreased with increasing grafting yield. The tensile strength decreased with increasing grafting yield, whereas the elongation decreased with increasing grafting yield.

  17. Charge transport and structural dynamics in carboxylic-acid-based deep eutectic mixtures.

    PubMed

    Griffin, Philip J; Cosby, Tyler; Holt, Adam P; Benson, Roberto S; Sangoro, Joshua R

    2014-08-01

    Charge transport and structural dynamics in the 1:2 mol ratio mixture of lidocaine and decanoic acid (LID-DA), a model deep eutectic mixture (DEM), have been characterized over a wide temperature range using broad-band dielectric spectroscopy and depolarized dynamic light scattering. Additionally, Fourier transform infrared spectroscopy measurements were performed to assess the degree of proton transfer between the neutral parent molecules. From our detailed analysis of the dielectric spectra, we have determined that this carboxylic-acid-based DEM is approximately 25% ionic at room temperature. Furthermore, we have found that the characteristic diffusion rate of mobile charge carriers is practically identical to the rate of structural relaxation at all measured temperatures, indicating that fast proton transport does not occur in LID-DA. Our results demonstrate that while LID-DA exhibits the thermal characteristics of a DEM, its charge transport properties resemble those of a protic ionic liquid. PMID:25025600

  18. Synthesis and evaluation of novel dental monomer with branched carboxyl acid group

    PubMed Central

    Song, Linyong; Ye, Qiang; Ge, Xueping; Misra, Anil; Laurence, Jennifer S.; Berrie, Cynthia L.; Spencer, Paulette

    2014-01-01

    To enhance the water miscibility and increase the mechanical properties of dentin adhesives, a new glycerol-based monomer with vinyl and carboxylic acid, 4-((1,3-bis(-methacryloyloxy)propan-2-yl)oxy)-2-methylene-4-oxobutanoic acid (BMPMOB), was synthesized and characterized. Dentin adhesive formulations containing 2-hydroxyethyl methacrylate (HEMA), 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy) phenyl]propane (BisGMA), and BMPMOB were characterized with regard to real-time photopolymerization behavior, water sorption, dynamic mechanical analysis, and microscale three-dimensional internal morphologies and compared with HEMA/BisGMA controls. The experimental adhesive copolymers showed higher glass transition temperature and rubbery moduli, as well as improved water miscibility compared to the controls. The enhanced properties of the adhesive copolymers indicated that BMPMOB is a promising comonomer for dental restorative materials. PMID:24596134

  19. Influence of cyclic dimer formation on the phase behavior of carboxylic acids. II. Cross-associating systems.

    PubMed

    Jane?ek, Ji?í; Paricaud, Patrice

    2013-08-15

    The doubly bonded dimer association scheme (DBD) proposed by Sear and Jackson is extended to mixtures exhibiting both self- and cross-associations. The PC-SAFT equation of state is combined with the new DBD association contribution to describe the vapor-liquid equilibria of binary mixtures of carboxylic acids + associating compounds (water, alcohols, and carboxylic acids). The effect of doubly bonded dimers on the phase behavior in such systems is less important than in mixtures of carboxylic acids with nonassociating compounds, due to the cross-associations that compete with the formation of DBDs. Nevertheless, a clear improvement in the description of vapor-liquid coexistence curves is achieved over the classical 2B association model, particularly for the dew point curves. PMID:23806104

  20. Hydroxyindole Carboxylic Acid-Based Inhibitors for Receptor-Type Protein Tyrosine Protein Phosphatase Beta

    PubMed Central

    Zeng, Li-Fan; Zhang, Ruo-Yu; Bai, Yunpeng; Wu, Li; Gunawan, Andrea M.

    2014-01-01

    Abstract Aims: Protein tyrosine phosphatases (PTPs) play an important role in regulating a wide range of cellular processes. Understanding the role of PTPs within these processes has been hampered by a lack of potent and selective PTP inhibitors. Generating potent and selective probes for PTPs remains a significant challenge because of the highly conserved and positively charged PTP active site that also harbors a redox-sensitive Cys residue. Results: We describe a facile method that uses an appropriate hydroxyindole carboxylic acid to anchor the inhibitor to the PTP active site and relies on the secondary binding elements introduced through an amide-focused library to enhance binding affinity for the target PTP and to impart selectivity against off-target phosphatases. Here, we disclose a novel series of hydroxyindole carboxylic acid-based inhibitors for receptor-type tyrosine protein phosphatase beta (RPTP?), a potential target that is implicated in blood vessel development. The representative RPTP? inhibitor 8b-1 (L87B44) has an IC50 of 0.38??M and at least 14-fold selectivity for RPTP? over a large panel of PTPs. Moreover, 8b-1 also exhibits excellent cellular activity and augments growth factor signaling in HEK293, MDA-MB-468, and human umbilical vein endothelial cells. Innovation: The bicyclic salicylic acid pharmacophore-based focused library approach may provide a potential solution to overcome the bioavailability issue that has plagued the PTP drug discovery field for many years. Conclusion: A novel method is described for the development of bioavailable PTP inhibitors that utilizes bicyclic salicylic acid to anchor the inhibitors to the active site and peripheral site interactions to enhance binding affinity and selectivity. Antioxid. Redox Signal. 20, 2130–2140. PMID:24180557

  1. Ascorbic acid absorption in Crohn's disease. Studies using L-(carboxyl-/sup 14/C)ascorbic acid

    SciTech Connect

    Pettit, S.H.; Shaffer, J.L.; Johns, C.W.; Bennett, R.J.; Irving, M.H.

    1989-04-01

    Total body pool and intestinal absorption of ascorbic acid were studied in 12 patients undergoing operation for Crohn's disease (six with fistulae and six without) and in six control patients undergoing operation for reasons other than Crohn's disease. L-(carboxyl-/sup 14/C)Ascorbic acid, 0.19-0.40 megabecquerels (MBq), was given orally. After a period of equilibration, the labeled ascorbic acid was flushed out of the patient's body tissues using large doses of unlabeled ascorbic acid. Intestinal absorption of ascorbic acid, assessed from the total cumulative urinary /sup 14/C recovery, was found to be similar in patients with fistulizing Crohn's disease (73.9 +/- 8.45%), those without fistulas (72.8 +/- 11.53%), and in controls (80.3 +/- 8.11%). Total body pools of ascorbic acid, calculated using the plasma /sup 14/C decay curves, were similar in patients with Crohn's disease with fistulas (17.1 +/- 5.91 mg/kg), patients without fistulas (9.6 +/- 3.58 mg/kg), and in controls (13.3 +/- 4.28 mg/kg). The results indicate that ascorbic acid absorption is normal in patients with both fistulizing and nonfistulizing Crohn's disease. The results suggest that routine supplements of vitamin C are not necessary unless oral ascorbic acid intake is low.

  2. 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.

  3. Addition of carboxylic acids modifies phosphate sorption on soil and boehmite surfaces: a solution chemistry and XANES spectroscopy study.

    PubMed

    Schefe, C R; Kappen, P; Zuin, L; Pigram, P J; Christensen, C

    2009-02-01

    Soil acidification is a globally significant agricultural issue, as the plant availability of phosphorus (P) is decreased through increased P sorption onto aluminium (Al) hydroxides and other solid phase binding sites. X-ray absorption near edge structure (XANES) spectroscopy generated new information on the speciation of Al and P in the presence of carboxylic acids on soil and boehmite (gamma-AlOOH) surfaces. XANES spectra were acquired in the soft X-ray regime at the P and Al L(2,3)-edges, and the Al K-edge, respectively. Adding oxalic acid to soil enhanced Al dissolution and exposed previously occluded soil P, while hydroxybenzoic and coumaric acids did not compete with P for surface binding sites. Boehmite strongly adsorbed carboxylic acids in the absence of applied phosphorus. However, when P was applied with carboxylic acids, the carboxylics were unable to compete with P for binding, especially hydroxybenzoic and coumaric acids. Using XANES in both total electron yield and fluorescence yield modes provided valuable information on both surface and near-surface processes of P and Al due to different information depths. The Al K-edge XANES provided baseline information on the solid-phase matrix. XANES in total electron yield mode and at the P L-edge shows promise for speciation of elements on soil surfaces due to enhanced sensitivity for speciation of surface-adsorbed species compared to the commonly used P K-edge XANES. PMID:18990400

  4. Surface Patterning of Benzene Carboxylic Acids on Graphite: Influence of structure, solvent, and concentration on molecular self-assembly

    NASA Astrophysics Data System (ADS)

    Florio, Gina; Stiso, Kimberly; Campanelli, Joseph; Dessources, Kimberly; Folkes, Trudi

    2012-02-01

    Scanning tunneling microscopy (STM) was used to investigate the molecular self-assembly of four different benzene carboxylic acid derivatives at the liquid/graphite interface: pyromellitic acid (1,2,4,5-benzenetetracarboxylic acid), trimellitic acid (1,2,4-benzenetricarboxylic acid), trimesic acid (1,3,5-benzenetricarboxylic acid), and 1,3,5-benzenetriacetic acid. A range of two dimensional networks are observed that depend sensitively on the number of carboxylic acids present, the nature of the solvent, and the solution concentration. We will describe our recent efforts to determine (a) the preferential two-dimensional structure(s) for each benzene carboxylic acid at the liquid/graphite interface, (b) the thermodynamic and kinetic factors influencing self-assembly (or lack thereof), (c) the role solvent plays in the assembly, (e) the effect of in situ versus ex situ dilution on surface packing density, and (f) the temporal evolution of the self-assembled monolayer. Results of computational analysis of analog molecules and model monolayer films will also be presented to aid assignment of network structures and to provide a qualitative picture of surface adsorption and network formation.

  5. Comparison of unimolecular decomposition pathways for carboxylic acids of relevance to biofuels.

    PubMed

    Clark, Jared M; Nimlos, Mark R; Robichaud, David J

    2014-01-01

    Quantum mechanical molecular modeling is used [M06-2X/6-311++G(2df,p)] to compare activation energies and rate constants for unimolecular decomposition pathways of saturated and unsaturated carboxylic acids that are important in the production of biofuels and that are models for plant and algae-derived intermediates. Dehydration and decarboxylation reactions are considered. The barrier heights to decarboxylation and dehydration are similar in magnitude for saturated acids (?71 kcal mol(-1)), with an approximate 1:1 [H2O]/[CO2] branching ratio over the temperature range studied (500-2000 K). ?,?-Unsaturation lowers the barrier to decarboxylation between 2.2 and 12.2 kcal mol(-1) while increasing the barriers to dehydration by ?3 kcal mol(-1). The branching ratio, as a result, is an order of magnitude smaller, [H2O]/[CO2] = 0.07. For some ?,?-unsaturated acids, six-center transition states are available for dehydration, with barrier heights of ?35.0 kcal mol(-1). The branching ratio for these acids can be as high as 370:1. ?,?-Unsaturation results in a small lowering in the barrier height to decarboxylation (?70.0 kcal mol(-1)). ?,?-Unsaturation also leads to a lowering in the dehydration pathway from 1.7 to 5.1 kcal mol(-1). These results are discussed with respect to predicted kinetic values for acids of importance in biofuels production. PMID:24295398

  6. A fluorimetric study of terbium, europium and dysprosium in aqueous solution using pyridine carboxylic acids as ligands

    Microsoft Academic Search

    B. S Panigrahi

    2002-01-01

    Fluorescence enhancement of Tb3+, Eu3+ and Dy3+ was studied in aqueous solution using pyridine carboxylic acids (nicotinic, picolinic and dipicolinic acids) as ligands. The fluorescence intensity of Tb3+, Eu3+ and Dy3+ could be enhanced, contrary to an earlier report by more than two to three orders of magnitude using these acids as ligands. To further enhance the lanthanide fluorescence, a

  7. Abiotic Formation of Carboxylic Acids (RCOOH) in Interstellar and Solar System Model Ices

    NASA Astrophysics Data System (ADS)

    Kim, Y. S.; Kaiser, R. I.

    2010-12-01

    The present laboratory study simulated the abiotic formation of carboxylic acids (RCOOH) in interstellar and solar system model ices of carbon dioxide (CO2)-hydrocarbon mix C n H2n+2 (n = 1-6). The pristine model ices were irradiated at 10 K under contamination-free, ultrahigh vacuum conditions with energetic electrons generated in the track of galactic cosmic-ray particles. The chemical processing of the ices was monitored by a Fourier transform infrared spectrometer and a quadrupole mass spectrometer during the irradiation phase and subsequent warm-up phases on line and in situ in order to extract qualitative (carriers) and quantitative (rate constants and yields) information on the newly synthesized species. Carboxylic acids were identified to be the main carrier, together with carbon monoxide (CO) and a trace of formyl (HCO) and hydroxycarbonyl (HOCO) radicals at 10 K. The upper limit of acid column density at 10 K was estimated as much as (1.2 ± 0.1) × 1017 molecules cm-2 at doses of 17 ± 2 eV molecule-1, or the yield of 39% ± 4% from the initial column density of carbon dioxide. The temporal column density profiles of the products were then numerically fit using two independent kinetic schemes of reaction mechanisms. Finally, we transfer this laboratory simulation to star-forming regions of the interstellar medium, wherein cosmic-ray-induced processing of icy grains at temperatures as low as 10 K could contribute to the current level of chemical complexity as evidenced in astronomical observations and in extracts of carbonaceous meteorites.

  8. ABIOTIC FORMATION OF CARBOXYLIC ACIDS (RCOOH) IN INTERSTELLAR AND SOLAR SYSTEM MODEL ICES

    SciTech Connect

    Kim, Y. S.; Kaiser, R. I., E-mail: ralfk@hawaii.ed [Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822 (United States)

    2010-12-10

    The present laboratory study simulated the abiotic formation of carboxylic acids (RCOOH) in interstellar and solar system model ices of carbon dioxide (CO{sub 2})-hydrocarbon mix C{sub n} H{sub 2n+2} (n = 1-6). The pristine model ices were irradiated at 10 K under contamination-free, ultrahigh vacuum conditions with energetic electrons generated in the track of galactic cosmic-ray particles. The chemical processing of the ices was monitored by a Fourier transform infrared spectrometer and a quadrupole mass spectrometer during the irradiation phase and subsequent warm-up phases on line and in situ in order to extract qualitative (carriers) and quantitative (rate constants and yields) information on the newly synthesized species. Carboxylic acids were identified to be the main carrier, together with carbon monoxide (CO) and a trace of formyl (HCO) and hydroxycarbonyl (HOCO) radicals at 10 K. The upper limit of acid column density at 10 K was estimated as much as (1.2 {+-} 0.1) x 10{sup 17} molecules cm{sup -2} at doses of 17 {+-} 2 eV molecule{sup -1}, or the yield of 39% {+-} 4% from the initial column density of carbon dioxide. The temporal column density profiles of the products were then numerically fit using two independent kinetic schemes of reaction mechanisms. Finally, we transfer this laboratory simulation to star-forming regions of the interstellar medium, wherein cosmic-ray-induced processing of icy grains at temperatures as low as 10 K could contribute to the current level of chemical complexity as evidenced in astronomical observations and in extracts of carbonaceous meteorites.

  9. Inhibitive action of indole-5-carboxylic acid towards corrosion of mild steel in deaerated 0.5 M sulfuric acid solutions

    NASA Astrophysics Data System (ADS)

    Quartarone, G.; Bonaldo, L.; Tortato, C.

    2006-09-01

    Inhibition of mild steel corrosion in deaerated 0.5 M sulfuric acid solutions containing various concentrations of indole-5-carboxylic acid is studied in the temperature range from 25 to 55 °C using weight-loss, potentiodynamic and spectrophotometric tests. The adsorptive behaviour of inhibitor is also investigated using electrochemical impedance spectroscopy measurements. The indole-5-carboxylic acid is found to shift the corrosion potentials towards more noble values. This shift indicates that the addition of inhibitor mainly affects the anodic process, raising the anodic overpotential more than that of the cathodic, i.e. the indole-5-carboxylic acid behaves as mixed-type inhibitor. Because the cathodic Tafel slopes for hydrogen reduction ( bc) are affected, the inhibitor probably affects the hydrogen reduction mechanism. The activation energy values ( Ea) indicate that the indole-5-carboxylic acid increases the activation energy of the corrosion reaction. The adsorption behaviour of indole-5-carboxylic acid follows Langmuir's isotherm. Both the low values of -?G° and its decrease with temperature suggest physical adsorption. Double layer capacitance-potential curves indicate considerable adsorption of the inhibitor in the potential range (-400 to -800 mV/ SCE).

  10. Fourier Tranform Microwave Studies of Bi-Molecules of Carboxylic Acids

    NASA Astrophysics Data System (ADS)

    Evangelisti, Luca; Feng, Gang; Qian, Gou; Maris, Assimo; Caminati, W.; Favero, Laura B.; Cocinero, Emilio; Ejica, Patricia; Fernandez, Jose'A.; Castano, Fernando; Lesarri, Alberto; Meyer, Rolf

    2012-06-01

    We recorded the molecular beam Fourier transform microwave spectra of several isotopic species of several homo and hetero dimers of carboxylic acids (R-COOH). Several tunnelling splittings have been measured with the accuracy underlying microwave spectroscopy. These splittings have been originated by the concerted double proton transfer of the two protons, but in some cases also by internal motions within the R chain in R-COOH. When the splittings were due to the double proton transfer, they were considerably decreasing upon mono- or bi-deuteration of the two carboxylic protons. The splittings due to the proton transfer have been used to determine the barrier to the proton transfer by applying a flexible model suited to take into account the coupling of the proton motions with the skeletal motions. The potential energy surfaces of the lateral chain motions have also been estimated. A full frame structure has been determined for some bimolecules, obtaining details of the Ubbelohde effect associated to the double hydrogen bond.

  11. Transition-metal-free visible-light photoredox catalysis at room-temperature for decarboxylative fluorination of aliphatic carboxylic acids by organic dyes.

    PubMed

    Wu, Xinxin; Meng, Chunna; Yuan, Xiaoqian; Jia, Xiaotong; Qian, Xuhong; Ye, Jinxing

    2015-07-01

    We report herein an efficient, general and green method for decarboxylative fluorination of aliphatic carboxylic acids. By using a transition-metal-free, organocatalytic photoredox system, the reaction of various aliphatic carboxylic acids with the Selectfluor reagent afforded the corresponding alkyl fluorides in satisfactory yields under visible light irradiation at room temperature. PMID:26111079

  12. Direct ester condensation from a 1:1 mixture of carboxylic acids and alcohols catalyzed by hafnium(IV) or zirconium(IV) salts

    Microsoft Academic Search

    Kazuaki Ishihara; Masaya Nakayama; Suguru Ohara; Hisashi Yamamoto

    2002-01-01

    To promote atom efficiency in synthesis and to avoid the generation of environmental waste, the use of stoichiometric amounts of condensing reagents or excess substrates should be avoided. In esterification, excess amounts of either carboxylic acids or alcohols are normally needed. We found that the direct condensation of equimolar amounts of carboxylic acids and alcohols could be achieved using hafnium(IV)

  13. Understanding Potential Exposure Sources of Perfluorinated Carboxylic Acids in the Workplace

    PubMed Central

    Kaiser, Mary A.; Dawson, Barbara J.; Barton, Catherine A.; Botelho, Miguel A.

    2010-01-01

    This paper integrates perspectives from analytical chemistry, environmental engineering, and industrial hygiene to better understand how workers may be exposed to perfluorinated carboxylic acids when handling them in the workplace in order to identify appropriate exposure controls. Due to the dramatic difference in physical properties of the protonated acid form and the anionic form, this family of chemicals provides unique industrial hygiene challenges. Workplace monitoring, experimental data, and modeling results were used to ascertain the most probable workplace exposure sources and transport mechanisms for perfluorooctanoic acid (PFOA) and its ammonium salt (APFO). PFOA is biopersistent and its measurement in the blood has been used to assess human exposure since it integrates exposure from all routes of entry. Monitoring suggests that inhalation of airborne material may be an important exposure route. Transport studies indicated that, under low pH conditions, PFOA, the undissociated (acid) species, actively partitions from water into air. In addition, solid-phase PFOA and APFO may also sublime into the air. Modeling studies determined that contributions from surface sublimation and loss from low pH aqueous solutions can be significant potential sources of workplace exposure. These findings suggest that keeping surfaces clean, preventing accumulation of material in unventilated areas, removing solids from waste trenches and sumps, and maintaining neutral pH in sumps can lower workplace exposures. PMID:20974675

  14. Transition metal ion-assisted photochemical generation of alkyl halides and hydrocarbons from carboxylic acids

    SciTech Connect

    Carraher, Jack; Pestovsky, Oleg; Bakac, Andreja

    2012-03-14

    Near-UV photolysis of aqueous solutions of propionic acid and aqueous Fe3+ in the absence of oxygen generates a mixture of hydrocarbons (ethane, ethylene and butane), carbon dioxide, and Fe2+. The reaction becomes mildly catalytic (about five turnovers) in the presence of oxygen which converts a portion of alkyl radicals to oxidizing intermediates that reoxidize Fe2+. The photochemistry in the presence of halide ions (X? = Cl?, Br?) generates ethyl halides via halogen atom abstraction from FeXn3?n by ethyl radicals. Near-quantitative yields of C2H5X are obtained at ?0.05 M X?. Competition experiments with Co(NH3)5Br2+ provided kinetic data for the reaction of ethyl radicals with FeCl2+ (k = (4.0 ± 0.5) × 106 M?1 s?1) and with FeBr2+ (k = (3.0 ± 0.5) × 107 M?1 s?1). Photochemical decarboxylation of propionic acid in the presence of Cu2+ generates ethylene and Cu+. Longer-chain acids also yield alpha olefins as exclusive products. These reactions become catalytic under constant purge with oxygen which plays a dual role. It reoxidizes Cu+ to Cu2+, and removes gaseous olefins to prevent accumulation of Cu+(olefin) complexes and depletion of Cu2+. The results underscore the profound effect that the choice of metal ions, the medium, and reaction conditions exert on the photochemistry of carboxylic acids.

  15. Omega-3 carboxylic acids (Epanova): a review of its use in patients with severe hypertriglyceridemia.

    PubMed

    Blair, Hannah A; Dhillon, Sohita

    2014-10-01

    Omega-3 carboxylic acids (Epanova) [OM3-CA] is the first free fatty acid form of long-chain marine omega-3 fatty acids (eicosapentaenoic acid and docosahexaenoic acid being the most abundant) to be approved by the US FDA as an adjunct to diet to lower triglyceride levels in patients with severe hypertriglyceridemia (? 500 mg/dL). Oral OM3-CA has greater bioavailability than ethyl ester forms of omega-3 and, unlike omega-3 acid ethyl esters, does not require co-ingestion of a high-fat meal, as it does not need pancreatic enzyme activity for absorption. In the 12-week EpanoVa fOr Lowering Very high triglyceridEs (EVOLVE) trial, OM3-CA 2 or 4 g/day significantly reduced serum triglyceride levels relative to placebo. Other lipid parameters, including non-high-density lipoprotein cholesterol (non-HDL-C), total cholesterol, and very low-density lipoprotein cholesterol (VLDL-C) levels, were also reduced significantly with OM3-CA relative to placebo. Low-density lipoprotein cholesterol levels were increased significantly with OM3-CA relative to placebo; however, these increases were not accompanied by increases in the circulating concentrations of non-HDL-C, VLDL-C, or apolipoprotein B. OM3-CA was generally well tolerated in this study, with most adverse events being of mild or moderate severity. Although additional comparative data are needed to position OM3-CA with respect to other formulations of omega-3 fatty acids, current evidence suggests that OM3-CA is a useful addition to the treatment options available for patients with severe hypertriglyceridemia. PMID:25234378

  16. Polymorphism in Self-Assembled Structures of 9-Anthracene Carboxylic Acid on Ag(111)

    PubMed Central

    Lu, Chao; Wei, Yinying; Zhu, Erkuang; Reutt-Robey, Janice E.; Xu, Bo

    2012-01-01

    Surface self-assembly process of 9-anthracene carboxylic acid (AnCA) on Ag(111) was investigated using STM. Depending on the molecular surface density, four spontaneously formed and one annealed AnCA ordered phases were observed, namely a straight belt phase, a zigzag double-belt phase, two simpler dimer phases, and a kagome phase. The two high-density belt phases possess large unit cells on the scale length of 10 nm, which are seldom observed in molecular self-assembled structures. This structural diversity stems from a complicated competition of different interactions of AnCA molecules on metal surface, including intermolecular and molecular-substrate interactions, as well as the steric demand from high molecular surface density. PMID:22837666

  17. A chiral benzoquinolizine-2-carboxylic acid arginine salt active against vancomycin-resistant Staphylococcus aureus.

    PubMed

    de Souza, Noel J; Gupte, Shrikant V; Deshpande, Prasad K; Desai, Vijaya N; Bhawsar, Satish B; Yeole, Ravindra D; Shukla, Milind C; Strahilevitz, Jacob; Hooper, David C; Bozdogan, Bülent; Appelbaum, Peter C; Jacobs, Michael R; Shetty, Nitin; Patel, Mahesh V; Jha, Rasendrakumar; Khorakiwala, Habil F

    2005-08-11

    There is an urgent medical need for novel antibacterial agents to treat hospital infections, specially those caused by multidrug-resistant Gram-positive pathogens. The need may also be fulfilled by either exploring antibacterial agents having new mechanism of action or expanding known classes of antibacterial drugs. The paper describes a new chemical entity, compound 21, derived from hitherto little known "floxacin". The choice of the entity was made from a series of synthesized prodrugs and salts of the active chiral benzoquinolizine carboxylic acid, S-(-)-nadifloxacin. The chemistry, physicochemical characteristics, and essential bioprofile of 21 qualifies it for serious consideration as a novel drug entity against hospital infections of multi-drug-resistant Staphylococcus aureus, and its progress up to clinical phase I trials in humans is described. PMID:16078842

  18. Synergism between ammonia, lactic acid and carboxylic acids as kairomones in the host-seeking behaviour of the malaria mosquito Anopheles gambiae sensu stricto (Diptera: Culicidae)

    Microsoft Academic Search

    Renate C. Smallegange; Yu Tong Qiu; Loon van J. J. A; Willem Takken

    2005-01-01

    Host odours play a major role in the orientation and host location of blood-feeding mosquitoes. Anopheles gambiae Giles sensu stricto, which is the most important malaria vector in Africa, is a highly anthropophilic mosquito species, and the host-seeking behaviour of the females of this mosquito is guided by volatiles of human origin. Ammonia, lactic acid and several carboxylic acids are

  19. Alkaline battery containing a separator of a cross-linked copolymer of vinyl alcohol and unsaturated carboxylic acid

    NASA Technical Reports Server (NTRS)

    Hsu, L. C.; Philipp, W. H.; Sheibley, D. W.; Gonzalez-Sanabria, O. D. (inventors)

    1985-01-01

    A battery separator for an alkaline battery is described. The separator comprises a cross linked copolymer of vinyl alcohol units and unsaturated carboxylic acid units. The cross linked copolymer is insoluble in water, has excellent zincate diffusion and oxygen gas barrier properties and a low electrical resistivity. Cross linking with a polyaldehyde cross linking agent is preferred.

  20. [3 + 2] Cycloaddition reactions of thioisatin with thiazolidine-2-carboxylic acid: a versatile route to new heterocyclic scaffolds

    PubMed Central

    2011-01-01

    A facile synthesis of azabicycloadducts is described by 1,3-dipolar cycloaddition reactions of thioisatin with thiazolidine-2-carboxylic acid in the presence of various electron rich and electron deficient dipolarophiles. Theoritical calculations have been performed to study the regioselectivity of products. The geometrical and energetic properties have been analyzed for the different reactants, transition states and cycloadducts formed. PMID:22373364

  1. 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...

  2. Selective Nickel- and Manganese-Catalyzed Decarboxylative Cross Coupling of Some ?,?-Unsaturated Carboxylic Acids with Cyclic Ethers

    PubMed Central

    Zhang, Jia-Xiang; Wang, Yan-Jing; Zhang, Wei; Wang, Nai-Xing; Bai, Cui-Bing; Xing, Ya-Lan; Li, Yi-He; Wen, Jia-Long

    2014-01-01

    A nickel- and manganese-catalyzed decarboxylative cross coupling of ?, ?-unsaturated carboxylic acids with cyclic ethers such as tetrahydrofuran and 1, 4-dioxane was developed. Oxyalkylation was achieved when nickel acetate was used as catalyst, while manganese acetate promoted the reaction of alkenylation. PMID:25502282

  3. Highly stereoselective biosynthesis of (R)-?-hydroxy carboxylic acids through rationally re-designed mutation of d-lactate dehydrogenase

    PubMed Central

    Zheng, Zhaojuan; Sheng, Binbin; Gao, Chao; Zhang, Haiwei; Qin, Tong; Ma, Cuiqing; Xu, Ping

    2013-01-01

    An NAD-dependent d-lactate dehydrogenase (d-nLDH) of Lactobacillus bulgaricus ATCC 11842 was rationally re-designed for asymmetric reduction of a homologous series of ?-keto carboxylic acids such as phenylpyruvic acid (PPA), ?-ketobutyric acid, ?-ketovaleric acid, ?-hydroxypyruvate. Compared with wild-type d-nLDH, the Y52L mutant d-nLDH showed elevated activities toward unnatural substrates especially with large substitutes at C-3. By the biocatalysis combined with a formate dehydrogenase for in situ generation of NADH, the corresponding (R)-?-hydroxy carboxylic acids could be produced at high yields and highly optical purities. Taking the production of chiral (R)-phenyllactic acid (PLA) from PPA for example, 50?mM PPA was completely reduced to (R)-PLA in 90?min with a high yield of 99.0% and a highly optical purity (>99.9% e.e.) by the coupling system. The results presented in this work suggest a promising alternative for the production of chiral ?-hydroxy carboxylic acids. PMID:24292439

  4. Clozapine-carboxylic acid plasticized co-amorphous dispersions: Preparation, characterization and solution stability evaluation.

    PubMed

    Ali, Ahmed Mahmoud Abdelhaleem; Ali, Adel Ahmed; Maghrabi, Ibrahim Abdullah

    2015-06-01

    This study addressed the possibility of forming of co-amorphous systems between clozapine (CZ) and various carboxylic acid plasticizers (CAPs). The aim was to improve the solubility and oral bioavailability of clozapine. Co-amorphous dispersions were prepared using modified solvent evaporation methodology at drug/plasticizer stoichiometric ratios of 1:1, 1:1.5 and 1:2. Solid state characterization was performed using differential scanning calorimetry, X-ray diffraction and infra red spectroscopy. Highly soluble homogeneous co-amorphous dispersions were formed between clozapine and CAPs via hydrogen bonding. The co-amorphous dispersions formed with tartaric acid (1:2) showed the highest dissolution percentage (> 95 % in 20 minutes) compared to pure crystalline CZ (56 %). Highly stable solutions were obtained from co-amorphous CZ-citric and CZ-tartaric acid at 1:1.5 molar ratio. The prepared dispersions suggest the possibility of peroral or sublingual administration of highly soluble clozapine at a reduced dose with the great chance to bypass the first pass metabolism. PMID:26011930

  5. Atmospheric chemistry and fate of highly-fluorinated carboxylic acids and alcohols

    NASA Astrophysics Data System (ADS)

    Rontu Carlon, Nabilah Arshad

    It is well known that organic molecules constitute a significant fraction of atmospheric aerosol particle composition. Organic compounds which reside on the surface of aerosol particles dictate its morphological, chemical, and optical properties and can influence its reactivity in the atmosphere. Organic rich atmospheric aerosol particles may be a vehicle of transport for organics found in the atmosphere. In the context of this work, the atmospheric chemistry and fate of highly fluorinated and fully fluorinated organic compounds, known as perfluorinated compounds (PFCs), are examined. They have recently been under the scrutiny of the Environmental Protection Agency due to their widespread distribution, persistence, bioaccumulation, and possible toxicity. The focus of the studies outlined in this thesis is motivated by determining if atmospheric aerosol particles may be a plausible candidate for transporting highly-fluorinated and perfluorinated compounds in the troposphere, and also understanding the heterogeneous chemistry that this class of compounds can undergo in the atmosphere. Gas-phase vibrational spectra of several perfluorocarboxylic acids were studied from the infrared to the visible regions. The objective of these experiments served as a preliminary step in determining if PFCs have the potential to undergo sunlight-initiated photochemistry through vibrational overtone pumping of the O-H bond. Results would discern if there is a competition between evaporation and actual chemical reactions occurring at the air-water interface. The surface properties of several highly-fluorinated carboxylic acids and partially fluorinated alcohols at the air-water interface were investigated. These results helped characterize film properties and understand how these compounds behave at the air-water interface in the presence of other organics. Consequences of these studies helped answer if atmospheric aerosol particles may be a possible vehicle of transport for fluorinated compounds in the atmosphere. Processing films of an unsaturated, partially fluorinated carboxylic acid at the air-water interface with ozone and visible light was examined. The resultant film was collected and analyzed as well as the subphase to determine degradation products. Results from these studies gave valuable insight as to the changing structure of the film due to photoprocessing and showed differences in activity of fluorinated compounds as compared to hydrocarbon analog acids.

  6. Tunneling isomerization of small carboxylic acids and their complexes in solid matrixes: a computational insight.

    PubMed

    Tsuge, Masashi; Khriachtchev, Leonid

    2015-03-19

    We have studied hydrogen-atom tunneling in the cis-to-trans conformational change of some carboxylic acid monomers and formic acid (FA) complexes and dimers at the MP2(full) and CCSD(T) levels of theory within the Wentzel-Kramers-Brillouin approximation. The barrier for the minimum energy path, where the OH bond length and the COH bending angle are optimized, is found to be a good approximation for providing the highest barrier transparency. The matrix effect on the transmission coefficients of cis-FA monomer, trans-cis FA dimer (tc1), and cis-acetic acid monomer are modeled by the polarizable continuum model (PCM) at the MP2(full) level of theory in different environments. For the cis-FA monomer and trans-cis FA dimer (tc1), the calculated transmission coefficients agree with the experimental lifetimes observed in noble-gas solids. However, this method cannot reproduce the experimental results obtained for cis-acetic acid. Moreover, the long lifetime of cis-FA and cis-acetic acid in the N2 environment cannot be reproduced either, which is most probably due to specific interactions that are not included in the PCM. The calculation for cis-HCOOD shows a strong decrease of the barrier transparency compared to that for cis-HCOOH, which is consistent with the experiments. In general, good agreement is observed between the calculated barrier transparency (including PCM) and experimental tunneling rate. However, some exceptions are found, which shows that additional factors influence the tunneling rate. PMID:25393052

  7. Unusual stable isotope ratios in amino acid and carboxylic acid extracts from the Murchison meteorite

    NASA Technical Reports Server (NTRS)

    Epstein, S.; Krishnamurthy, R. V.; Cronin, J. R.; Pizzarello, S.; Yuen, G. U.

    1987-01-01

    The isotopic composition of hydrogen, nitrogen, and carbon in amino acid and monocarboxylic acid extracts from the Murchison meteorite has been determined. The unusually high D/H and N-15/N-14 ratios in the amino acid fraction are uniquely characteristic of known interstellar organic materials. The delta D value of the monocarboxylic acid fraction is lower but still consistent with an interstellar origin. These results confirm the extraterrestrial origin of both classes of compound and provide the first evidence suggesting a direct relationship between the massive organosynthesis occurring in interstellar clouds and the presence of prebiotic compounds in primitive planetary bodies.

  8. Fluorocinnoline derivatives. II. Synthesis and antibacterial activity of fluorinated 1-alkyl-1,4-dihydro-4-oxocinnoline-3-carboxylic acids.

    PubMed

    Miyamoto, T; Matsumoto, J

    1989-01-01

    Chemical modification of cinoxacin was studied with the aim of improving its antibacterial activity and spectrum. Alkylation of ethyl 6,7,8-trifluoro- and 6,7-difluoro-4-hydroxycinnoline-3-carboxylates (1 and 7) with alkyl iodide or dialkyl sulfate gave ethyl 1-alkyl-6,7,8-trifluoro- and 6,7-difluoro-1,4-dihydro-4-oxocinnoline-3-carboxylates (2 and 8), together with the isomeric anhydro-bases 3 and 9 of 2-alkyl-3-ethoxycarbonyl-6,7,8-trifluoro- and 6,7-difluoro-4-hydroxycinnolinium hydroxides, respectively. Acid-catalyzed hydrolysis of the 1-alkyl derivatives 2 and 8 gave the corresponding carboxylic acids 4 and 10. The same treatment of 3 and 9, accompanied with decarboxylation of the inner salts 5 and 11, afforded the anhydro-bases 6 and 12 of 2-alkyl-4-hydroxycinnolinium hydroxides, respectively. Displacement reactions of 4 and 10 with nucleophiles such as amine, alkoxide and thiolate gave 7-substituted 1-alkyl-6,8-difluoro- and 6-fluoro-1,4-dihydro-4-oxocinnoline-3-carboxylic acids (13 and 17-35). Antibacterial activities of these compounds were evaluated and compared with those of cinoxacin and norfloxacin. Some compounds showed a broader spectrum and more potent activity than cinoxacin, but were considerably inferior in activity to norfloxacin. PMID:2720857

  9. Self-oriented glucose-modified infrared sensor for the detection of compounds bearing carboxylic acid groups.

    PubMed

    Cheng, Ming-Liang; Yang, Jyisy

    2008-01-01

    To explore the interactions of self-oriented glucose toward organic species, we prepared a glucose-modified infrared (IR) chemical sensor and examined its performance in the detection of compounds bearing carboxylic acid functional groups. Using a two-layer modification method, we chemically bonded glucose to the surface of an IR sensing element. The immobilized glucose moieties exhibited the ability to assemble into a chemical form similar to that of the cyclodextrins (CDs) such that they could trap targeted molecules. This modified sensing phase displayed an analysis capability similar to that of CDs, but without the problems encountered attempting to maintain the activity of the latter. From a systematic examination of three classes of structural analogs of acids, we found that the behavior of the glucose-modified sensing phase was similar to that of a CD-modified sensing phase. In terms of quantitative detection, we obtained an average regression coefficient of approximately 0.996 for the analytical signals of the examined compounds at concentrations less than 20 mg/L. The linearity of the standard curves was related to the detection time: the shorter the detection time, the greater the linearity. Defined as three times the noise level, we obtained detection limits of a few hundred parts per billion (microg/L) for the determination of high-polarity compounds using our glucose-modified sensing phase. PMID:18230206

  10. Carboxyl group (-CO2 H) functionalized coordination polymer nanoparticles as efficient platforms for drug delivery.

    PubMed

    Novio, Fernando; Lorenzo, Julia; Nador, Fabiana; Wnuk, Karolina; Ruiz-Molina, Daniel

    2014-11-17

    Functionalization of nanoparticles can significantly influence their properties and potential applications. Although researchers can now functionalize metal, metal oxide, and organic polymer nanoparticles with a high degree of precision, controlled surface functionalization of nanoscale coordination polymer particles (CPPs) has remained a significant challenge. The lack of methodology is perhaps one of the greatest roadblocks to the advancement of CPPs into high added-value drug delivery applications. Here, we report having achieved this goal through a stepwise formation and functionalization protocol. We fabricated robust nanoparticles with enhanced thermal and colloidal stabilities by incorporation of carboxyl groups and these surface carboxyl groups could be subsequently functionalized through well-known peptide coupling reactions. The set of chemistries that we employed as proof-of-concept enabled a plethora of new functional improvements for the application of CPPs as drug delivery carriers, including enhanced colloidal stabilities and the incorporation of additional functional groups such as polyethylene glycol (PEG) or fluorescent dyes that enabled tracking of their cellular uptake. Finally, we ascertained the cytotoxicity of the new CPP nanoparticles loaded with camptothecin to human breast adenocarcinoma (MCF-7). Efflux measurements show that the encapsulation of camptothecin enhances the potency of the drug 6.5-fold and increases the drug retention within the cell. PMID:25284328

  11. 2-substituted thiazolidine-4(R)-carboxylic acids as prodrugs of L-cysteine. Protection of mice against acetaminophen hepatotoxicity

    SciTech Connect

    Nagasawa, H.T.; Goon, D.J.; Muldoon, W.P.; Zera, R.T.

    1984-05-01

    A number of 2-alkyl- and 2-aryl-substituted thiazolidine-4(R)-carboxylic acids were evaluated for their protective effect against hepatotoxic deaths produced in mice by LD/sub 90/ doses of acetaminophen. 2(RS)-Methyl-, 2(RS)-n-propyl-, and 2(RS)-n- pentylthiazolidine -4(R)-carboxylic acids (compounds 1b,d,e, respectively) were nearly equipotent in their protective effect based on the number of surviving animals at 48 h as well as by histological criteria. 2(RS)-Ethyl-, 2(RS)-phenyl-, and 2(RS)-(4-pyridyl)thiazolidine-4(R)-carboxylic acids (compounds 1c,f,g) were less protective. The enantiomer of 1b, viz., 2(RS)- methylthiazolidine -4(S)-carboxylic acid (2b), was totally ineffective in this regard. Thiazolidine-4(R)-carboxylic acid (1a), but not its enantiomer, 2a, was a good substrate for a solubilized preparation of rat liver mitochondrial proline oxidase (K/sub m/ 1.1 x 10(-4) M; V/sub max/ . 5.4 mumol min-1 (mg of protein)-1). Compound 1b was not a substrate for proline oxidase but dissociated to L-cysteine in this system. At physiological pH and temperature, the hydrogens on the methyl group of 1b underwent deuterium exchange with solvent D/sub 2/O (k1 . 2.5 X 10(-5) s), suggesting that opening of the thiazolidine ring must have taken place. Indeed, 1b labeled with /sup 14/C in the 2 and methyl positions was rapidly metabolized by the rat to produce /sup 14/CO/sub 2/, 80% of the dose being excreted in this form in the expired air after 24 h. It is suggested that these 2-substituted thiazolidine-4(R)-carboxylic acids are prodrugs of L-cysteine that liberate this sulfhydryl amino acid in vivo by nonenzymatic ring opening, followed by solvolysis.

  12. Confirmation of a carboxylic acid metabolite of polychlorotrifluoroethylene and a method for its GC-ECD analysis in biological matrices.

    PubMed

    Greene, R J; Brashear, W T; Auten, K L; Mahle, D A

    1992-01-01

    3.1 Oil, referred to as polychlorotrifluoroethylene (pCTFE), is a polymeric mixture consisting primarily of trimers and tetramers of chlorotrifluoroethylene (CTFE) end-capped with chlorine. Inhalation studies have associated dose-related body weight loss, increased organ weights, and abnormal hepatic enzyme activities with exposure to pCTFE. The carboxylic acid metabolites of pCTFE have been shown to cause hepatotoxicity in rats, which is manifested by increased liver weights and the proliferation of hepatic peroxisomes. A method was developed to derivatize these carboxylic acid metabolites. Tissue homogenates and feces were extracted with methanol, and urinary metabolites were extracted on octadecylsilane (ODS) solid-phase extraction columns. Aliquots of the extracts and whole blood were methylated with 3N methanolic HCl to transesterify the carboxylic acid metabolites to volatile methyl esters. The pCTFE methyl esters were analyzed by gas chromatography (GC) with electron capture detection (ECD). The on-column limit of detection was 5 pg for each methyl ester. Solid-phase extraction of spiked urine gave extraction efficiencies of 90.4% for the trimer acid and 84.7% for the tetramer acid. This method was successfully applied to toxicity studies in rats and nonhuman primates. The identities of the derivatized metabolites were confirmed by GC/MS. PMID:1640695

  13. Equivalent Circuit Analysis of Dye-Sensitized Solar Cell by Using One-Diode Model: Effect of Carboxylic Acid Treatment of TiO2 Electrode

    Microsoft Academic Search

    Masaki Murayama; Tatsuo Mori

    2006-01-01

    For the improvement of dye-sensitized solar cell performance, it is important to analyze the electric mechanism of cells and to employ an effective treatment. Equivalent circuit analysis using a one-diode model was carried out for a dye-sensitized solar cell consisting of a TiO2 electrode treated with carboxylic acid. Carboxylic acid treatment, especially using acetic acid, was effective in increasing the

  14. meso-Ester and carboxylic acid substituted BODIPYs with far-red and near-infrared emission for bioimaging applications.

    PubMed

    Ni, Yong; Zeng, Lintao; Kang, Nam-Young; Huang, Kuo-Wei; Wang, Liang; Zeng, Zebing; Chang, Young-Tae; Wu, Jishan

    2014-02-17

    A series of meso-ester-substituted BODIPY derivatives 1-6 are synthesized and characterized. In particular, dyes functionalized with oligo(ethylene glycol) ether styryl or naphthalene vinylene groups at the ? positions of the BODIPY core (3-6) become partially soluble in water, and their absorptions and emissions are located in the far-red or near-infrared region. Three synthetic approaches are attempted to access the meso-carboxylic acid (COOH)-substituted BODIPYs 7 and 8 from the meso-ester-substituted BODIPYs. Two feasible synthetic routes are developed successfully, including one short route with only three steps. The meso-COOH-substituted BODIPY 7 is completely soluble in pure water, and its fluorescence maximum reaches around 650?nm with a fluorescence quantum yield of up to 15?%. Time-dependent density functional theory calculations are conducted to understand the structure-optical properties relationship, and it is revealed that the Stokes shift is dependent mainly on the geometric change from the ground state to the first excited singlet state. Furthermore, cell staining tests demonstrate that the meso-ester-substituted BODIPYs (1 and 3-6) and one of the meso-COOH-substituted BODIPYs (8) are very membrane-permeable. These features make these meso-ester- and meso-COOH-substituted BODIPY dyes attractive for bioimaging and biolabeling applications in living cells. PMID:24515608

  15. FT-IR, Laser-Raman spectra and computational analysis of 5-Methyl-3-phenylisoxazole-4-carboxylic acid

    NASA Astrophysics Data System (ADS)

    Sert, Yusuf; Mahendra, M.; Keskino?lu, S.; Chandra; Srikantamurthy, N.; Umesha, K. B.; Ç?rak, Ç.

    2015-03-01

    In this study the experimental and theoretical vibrational frequencies of a newly synthesized anti-tumor, antiviral, hypoglycemic, antifungal and anti-HIV agent namely, 5-Methyl-3-phenylisoxazole-4-carboxylic acid has been investigated. The experimental FT-IR (4000-400 cm-1) and Laser-Raman spectra (4000-100 cm-1) of the molecule in solid phase have been recorded. The theoretical vibrational frequencies and optimized geometric parameters (bond lengths, bond angles and torsion angles) have been calculated by using density functional theory (DFT/B3LYP: Becke, 3-parameter, Lee-Yang-Parr and DFT/M06-2X: highly parametrized, empirical exchange correlation function) with 6-311++G(d,p) basis set by Gaussian 09W software, for the first time. The assignments of the vibrational frequencies have been done by potential energy distribution (PED) analysis by using VEDA 4 software. The theoretical optimized geometric parameters and vibrational frequencies have been found to be in good agreement with the corresponding experimental data and results in the literature. In addition, the highest occupied molecular orbital (HOMO) energy, the lowest unoccupied molecular orbital (LUMO) energy and the other related molecular energy values of the compound have been investigated by using the same theoretical calculations.

  16. Reaction Kinetics for the Biocatalytic Conversion of Phenazine-1-Carboxylic Acid to 2-Hydroxyphenazine

    PubMed Central

    Chen, Mingmin; Cao, Hongxia; Peng, Huasong; Hu, Hongbo; Wang, Wei; Zhang, Xuehong

    2014-01-01

    The phenazine derivative 2-hydroxyphenazine (2-OH-PHZ) plays an important role in the biocontrol of plant diseases, and exhibits stronger bacteriostatic and fungistatic activity than phenazine-1-carboxylic acid (PCA) toward some pathogens. PhzO has been shown to be responsible for the conversion of PCA to 2-OH-PHZ, however the kinetics of the reaction have not been systematically studied. Further, the yield of 2-OH-PHZ in fermentation culture is quite low and enhancement in our understanding of the reaction kinetics may contribute to improvements in large-scale, high-yield production of 2-OH-PHZ for biological control and other applications. In this study we confirmed previous reports that free PCA is converted to 2-hydroxy-phenazine-1-carboxylic acid (2-OH-PCA) by the action of a single enzyme PhzO, and particularly demonstrate that this reaction is dependent on NADP(H) and Fe3+. Fe3+ enhanced the conversion from PCA to 2-OH-PHZ and 28°C was a optimum temperature for the conversion. However, PCA added in excess to the culture inhibited the production of 2-OH-PHZ. 2-OH-PCA was extracted and purified from the broth, and it was confirmed that the decarboxylation of 2-OH-PCA could occur without the involvement of any enzyme. A kinetic analysis of the conversion of 2-OH-PCA to 2-OH-PHZ in the absence of enzyme and under different temperatures and pHs in vitro, revealed that the conversion followed first-order reaction kinetics. In the fermentation, the concentration of 2-OH-PCA increased to about 90 mg/L within a red precipitate fraction, as compared to 37 mg/L within the supernatant. The results of this study elucidate the reaction kinetics involved in the biosynthesis of 2-OH-PHZ and provide insights into in vitro methods to enhance yields of 2-OH-PHZ. PMID:24905009

  17. Synthesis and cytotoxic properties of derivatives of the tert -butyl ester of 7-alkylidene-3-methyl-3-cepheme-4-carboxylic acid

    Microsoft Academic Search

    M. Vorona; I. Potorocina; G. Veinberg; I. Shestakova; I. Kanepe; E. Lukevics

    2008-01-01

    Sulfones of the tert-butyl esters of 7-arylmethylene-and 7-(2-furyl)methylene-3-methyl-3-cepheme-4-carboxylic acid were obtained\\u000a by the condensation of the tert-butyl ester of 3-methyl-7-oxo-3-cepheme-4-carboxylic acid with arylmethylene-and 2-furylidenetriphenylphosphoranes\\u000a and subsequent oxidation of the intermediate products by meta-chloroperbenzoic acid. The combination of the tert-butyl esters\\u000a of 7E-bromomethylene-and 7,7-dibromomethylene-3-methyl-1,1-dioxo-3-cepheme-4-carboxylic acids with trimethylsilylacetylene\\u000a under conditions of the Sonogashira reaction gave the tert-butyl esters of 3-methyl-1,1-dioxo-7E-(3-trimethylsilyl-2-propynylidene)-3-cepheme-4-carboxylic\\u000a acid and

  18. Growth inhibition of Clostridium thermocellum by carboxylic acids: A mechanism based on uncoupling by weak acids

    Microsoft Academic Search

    Alejandro A. Herrero; Reinaldo F. Gomez; Brad Snedecor; Cynthia J. Tolman; Mary F. Roberts

    1985-01-01

    The inhibition of Clostridium thermocellum strains by acetate and other organic acids (propionate, butyrate) can be explained by a model based on the chemiosmotic theory and uncoupler action. It is proposed that the charged permeant species in the process of anion exclusion is the dimer HA-2. Evidence for this mechanisms is provided by 31P-NMR studies of whole cells and cell

  19. Synthesis, antifungal activity and QSAR of some novel carboxylic acid amides.

    PubMed

    Du, Shijie; Lu, Huizhe; Yang, Dongyan; Li, Hong; Gu, Xilin; Wan, Chuan; Jia, Changqing; Wang, Mian; Li, Xiuyun; Qin, Zhaohai

    2015-01-01

    A series of novel aromatic carboxylic acid amides were synthesized and tested for their activities against six phytopathogenic fungi by an in vitro mycelia growth inhibition assay. Most of them displayed moderate to good activity. Among them N-(2-(1H-indazol-1-yl)phenyl)-2-(trifluoromethyl)benzamide (3c) exhibited the highest antifungal activity against Pythium aphanidermatum (EC50 = 16.75 µg/mL) and Rhizoctonia solani (EC50 = 19.19 µg/mL), compared to the reference compound boscalid with EC50 values of 10.68 and 14.47 µg/mL, respectively. Comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were employed to develop a three-dimensional quantitative structure-activity relationship model for the activity of the compounds. In the molecular docking, a fluorine atom and the carbonyl oxygen atom of 3c formed hydrogen bonds toward the hydroxyl hydrogens of TYR58 and TRP173. PMID:25749678

  20. Some Characteristics of the System Converting 1-Aminocyclopropane-1-carboxylic Acid to Ethylene 1

    PubMed Central

    Apelbaum, Akiva; Burgoon, Alan C.; Anderson, James D.; Solomos, Theo; Lieberman, Morris

    1981-01-01

    The rate of C2H4 production in plant tissue appears to be limited by the level of endogenous 1-aminocyclopropane-1-carboxylic acid (ACC). Exogenous ACC stimulated C2H4 production considerably in plant tissues, but this required 10 to 100 times the endogenous concentrations of ACC before significant increases in C2H4 production were observed. This was partially due to poor penetration of ACC into the tissues. Conversion of ACC to C2H4 was inhibited by free radical scavengers, reducing agents, and copper chelators, but not by inhibitors of pyridoxal phosphate-mediated reactions. The system for converting ACC to C2H4 may be membrane-associated, for it did not survive treatment with surface-active agents and cold or osmotic shock reduced the capacity of the system to convert ACC to C2H4. The reaction rate was sensitive to temperatures above 29 and below 12 C, which suggests that the system may be associated with membrane-bound lipoproteins. The data presented support the possibility that the conversion of exogenous ACC to C2H4 proceeds via the natural physiological pathway. PMID:16661638

  1. Oxidation of benzene with hydrogen peroxide catalyzed with ferrocene in the presence of pyrazine carboxylic acid

    NASA Astrophysics Data System (ADS)

    Shul'pina, L. S.; Durova, E. L.; Kozlov, Yu. N.; Kudinov, A. R.; Strelkova, T. V.; Shul'pin, G. B.

    2013-12-01

    It is found that ferrocene in the presence of small amounts of pyrazine carboxylic acid (PCA) effectively catalyzes the oxidation of benzene to phenol with hydrogen peroxide. Two main differences upon the oxidation of two different substrates, i.e., cyclohexane and benzene, with the same H2O2-ferrocene-PCA catalytic system are revealed: the rates of benzene oxidation and hydrogen peroxide decomposition are several times lower than the rate of cyclohexane oxidation at close concentrations of both substrates, and the rate constant ratios for the reactions of oxidizing particles with benzene and acetonitrile are significantly lower than would be expected for reactions involving free hydroxyl radicals. The overall rate of hydrogen peroxide decomposition, including both the catalase and oxidase routes, is lower in the presence of benzene than in the presence of cyclohexane. It is suggested on the grounds of these data that a catalytically active particle different from the one generated in the absence of benzene is formed in the presence of benzene. This particle catalyzes hydrogen peroxide decomposition less efficiently than the initial complex and generates a dissimilar oxidizing particle that exhibits higher selectivity. It is shown that reactivity of the system at higher concentrations of benzene differs from that of an initial system not containing an aromatic component with the capability of ?-coordination with metal ions.

  2. Autoinhibition of Ethylene Production in Citrus Peel Discs : SUPPRESSION OF 1-AMINOCYCLOPROPANE-1-CARBOXYLIC ACID SYNTHESIS.

    PubMed

    Riov, J; Yang, S F

    1982-03-01

    Wound ethylene formation induced in flavede tissue of citrus fruit (Citrus paradisi MacFad. cv. Ruby Red) by slicing was almost completely inhibited by exogenous ethylene. The inhibition lasted for at least 6 hours after removal of exogenous ethylene and was then gradually relieved. The extent of inhibition was dependent upon the concentration of ethylene (1 to 10 microliters/liter) and the duration of treatment. The increase in wound ethylene production in control discs was paralleled by an increase in 1-aminocyclopropane-1-carboxylic acid (AAC) content, whereas in ethylene-treated discs there was little increase in ACC content. Application of ACC completely restored ethylene production in ethylene-pretreated discs, indicating that the conversion of ACC to ethylene is not impaired by the presence of ethylene. Thus, autoinhibition of ethylene synthesis was exerted by reducing the availability of ACC. Ethylene treatment resulted in a decrease in extractable ACC synthase activity, but this decrease was too small to account for the marked inhibition of ACC formation. The data indicate that autoinhibition of ethylene production in citrus flavede discs results from suppression of ACC formation through repression of the synthesis of ACC synthase and inhibition of its activity. PMID:16662276

  3. 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.

  4. 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.

  5. Spectrofluorimetric determination of 3-methylflavone-8-carboxylic acid, the main active metabolite of flavoxate hydrochloride in human urine.

    PubMed

    Zaazaa, Hala E; Mohamed, Afaf O; Hawwam, Maha A; Abdelkawy, Mohamed

    2015-01-01

    A simple, sensitive and selective spectrofluorimetric method has been developed for the determination of 3-methylflavone-8-carboxylic acid as the main active metabolite of flavoxate hydrochloride in human urine. The proposed method was based on the measurement of the native fluorescence of the metabolite in methanol at an emission wavelength 390 nm, upon excitation at 338 nm. Moreover, the urinary excretion pattern has been calculated using the proposed method. Taking the advantage that 3-methylflavone-8-carboxylic acid is also the alkaline degradate, the proposed method was applied to in vitro determination of flavoxate hydrochloride in tablets dosage form via the measurement of its corresponding degradate. The method was validated in accordance with the ICH requirements and statistically compared to the official method with no significant difference in performance. PMID:25004902

  6. Spectrofluorimetric determination of 3-methylflavone-8-carboxylic acid, the main active metabolite of flavoxate hydrochloride in human urine

    NASA Astrophysics Data System (ADS)

    Zaazaa, Hala E.; Mohamed, Afaf O.; Hawwam, Maha A.; Abdelkawy, Mohamed

    2015-01-01

    A simple, sensitive and selective spectrofluorimetric method has been developed for the determination of 3-methylflavone-8-carboxylic acid as the main active metabolite of flavoxate hydrochloride in human urine. The proposed method was based on the measurement of the native fluorescence of the metabolite in methanol at an emission wavelength 390 nm, upon excitation at 338 nm. Moreover, the urinary excretion pattern has been calculated using the proposed method. Taking the advantage that 3-methylflavone-8-carboxylic acid is also the alkaline degradate, the proposed method was applied to in vitro determination of flavoxate hydrochloride in tablets dosage form via the measurement of its corresponding degradate. The method was validated in accordance with the ICH requirements and statistically compared to the official method with no significant difference in performance.

  7. Exploring the other side of biologically relevant chemical space: insights into carboxylic, sulfonic and phosphonic acid bioisosteric relationships.

    PubMed

    Macchiarulo, Antonio; Pellicciari, Roberto

    2007-11-01

    Bioisosteric replacements have been widely and successfully applied to develop bioisosteric series of biologically active compounds in medicinal chemistry. In this work, the concept of bioisosterism is revisited using a novel approach based on charting the "other side" of biologically relevant chemical space. This space is composed by the ensemble of binding sites of protein structures. Explorations into the "other side" of biologically relevant chemical space are exploited to gain insight into the principles that rules molecular recognition and bioisosteric relationships of molecular fragments. We focused, in particular, on the construction of the "other side" of chemical space covered by binding sites of small molecules containing carboxylic, sulfonic, and phosphonic acidic groups. The analysis of differences in the occupation of that space by distinct types of binding sites unveils how evolution has worked in assessing principles that rule the selectivity of molecular recognition, and improves our knowledge on the molecular basis of bioisosteric relationships among carboxylic, sulfonic, and phosphonic acidic groups. PMID:17544772

  8. Efficient amide bond formation through a rapid and strong activation of carboxylic acids in a microflow reactor.

    PubMed

    Fuse, Shinichiro; Mifune, Yuto; Takahashi, Takashi

    2014-01-13

    The development of highly efficient amide bond forming methods which are devoid of side reactions, including epimerization, is important, and such a method is described herein and is based on the concept of rapid and strong activation of carboxylic acids. Various carboxylic acids are rapidly (0.5 s) converted into highly active species, derived from the inexpensive and less-toxic solid triphosgene, and then rapidly (4.3 s) reacted with various amines to afford the desired peptides in high yields (74%-quant.) without significant epimerization (?3%). Our process can be carried out at ambient temperature, and only CO2 and HCl salts of diisopropylethyl amine are generated. In the long history of peptide synthesis, a significant number of active coupling reagents have been abandoned because the highly active electrophilic species generated are usually susceptible to side reactions such as epimerization. The concept presented herein should renew interest in the use of these reagents. PMID:24402801

  9. Successful computer guided planned synthesis of (4R)-thiazolidine carboxylic acid and its 2-substituted analogues as urease inhibitors.

    PubMed

    Khan, Khalid Mohammed; Ullah, Zia; Lodhi, Muhammad Arif; Ali, Muhammad; Choudhary, Muhammad Iqbal; Rahman, Atta Ur; Haq, Zaheer Ul

    2006-05-01

    By using internal combinatorial library we were able to identify (4R)-thiazolidines carboxylic acid and its 2-substituted analogs as active inhibitors of urease. Molecular modeling and virtual screening were utilized to find out potential compounds. Computational techniques were employed at database of 90,000 ligands and selected the structure representing the low energy conformations, Grid and FlexX docking algorithms were used and the top binding ligands were synthesized and screened in wet-lab. PMID:16710811

  10. Successful computer guided planned synthesis of (4 R )-thiazolidine carboxylic acid and its 2-substituted analogues as urease inhibitors

    Microsoft Academic Search

    Khalid Mohammed Khan; Zia Ullah; Muhammad Arif Lodhi; Muhammad Ali; Muhammad Iqbal Choudhary; Atta ur Rahman; Zaheer ul Haq

    2006-01-01

    By using internal combinatorial library we were able to identify (4R)-thiazolidines carboxylic acid and its 2-substituted analogs as active inhibitors of urease. Molecular modeling and virtual\\u000a screening were utilized to find out potential compounds. Computational techniques were employed at database of 90,000 ligands\\u000a and selected the structure representing the low energy conformations, Grid and FlexX docking algorithms were used and

  11. High Sensitive Sensor Based on Carbon Nanotube Electrode for Determination of Lanthanum in the Presence of Calcon Carboxylic Acid

    Microsoft Academic Search

    Sayed Mehdi Ghoreishi; Mohsen Behpour; Samaneh Mazaheri; Mohammadhassan Motaghedifard

    2012-01-01

    In this paper we have investigated the electrochemical activity of lanthanum chloride (La (III)) in the presence of calcon carboxylic acid (CCA) using a multi-walled carbon nano tube\\/carbon paste electrode (CNT\\/CPE). The peak current increases linearly with increasing of the La (III) concentration. For this purpose, a few electrochemical methods such as cyclic, differential pulse voltammetry, linear sweep and hydrodynamic

  12. Inhibitory effect of 6-hydroxy-7-methoxychroman-2-carboxylic acid phenylamide on nitric oxide and interleukin-6 production in macrophages

    Microsoft Academic Search

    Kyung Rak Min; Heesoon Lee; Byung Hak Kim; EunYong Chung; Sung Min Cho; Youngsoo Kim

    2005-01-01

    6-Hydroxy-7-methoxychroman-2-carboxylic acid phenylamide (CP compound) is a novel chemically synthetic compound with vitamin E-like chemical structure. In the present study, the CP compound was discovered to inhibit nitric oxide (NO) and interleukin (IL)-6 productions in lipopolysaccharide (LPS)-stimulated macrophages. Further, CP compound attenuated LPS-induced synthesis of mRNA and protein levels of inducible NO synthase (iNOS), in parallel, and inhibited iNOS promoter

  13. Effect of l-aminocyclopropane-l-carboxylic acid, silver nitrate, and norbornadiene on plant regeneration from maize callus cultures

    Microsoft Academic Search

    David D. Songstad; David R. Duncan; Jack M. Widholm

    1988-01-01

    The effect of the ethylene antagonists norbornadiene and silver nitrate and the ethylene precursor l-aminocyclopropane-l-carboxylic acid (ACC) on Zea mays plant regeneration was studied. A 12-fold increase in plant regeneration, as measured by number of plants obtained per gram fresh weight from callus cultures of maize inbreds Pa91 and H99, was obtained by 250 µM norbornadiene and 100 µM silver

  14. Low-molecular-weight aliphatic carboxylic acids in soil solutions under different vegetations determined by capillary zone electrophoresis

    Microsoft Academic Search

    Bjarne Westergaard Strobel; Irene Bernhoft; Ole K. Borggaard

    1999-01-01

    Concentrations of low-molecular-weight aliphatic carboxylic acids in soil solution were determined by a newly developed capillary\\u000a zone electrophoresis method. Soil solution samples were collected by centrifugation of soil from the A horizon of a Danish,\\u000a homogeneous, nutrient-rich Hapludalf in adjacent forested and arable plots. The forested plots of 0.5 ha were 33-year old\\u000a stands of beech (Fagus sylvatica L.), oak

  15. Tissue Localization of a Submergence-Induced 1-Aminocyclopropane-1-Carboxylic Acid Synthase in Rice1

    PubMed Central

    Zhou, Zhongyi; de Almeida Engler, Janice; Rouan, Dominique; Michiels, Frank; Van Montagu, Marc; Van Der Straeten, Dominique

    2002-01-01

    At least two 1-aminocyclopropane-1-carboxylic acid synthase genes (ACS) are implicated in the submergence response of rice (Oryza sativa). Previously, the OS-ACS5 gene has been shown to be induced during short- as well as long-term complete submergence of seedlings and to be controlled by a balance of gibberellin and abscisic acid in both lowland and deepwater rice. This study demonstrates that OS-ACS5 mRNA is localized in specific tissues and cells both during normal development and in response to complete submergence. The temporal and spatial regulation of OS-ACS5 expression is presented by in situ hybridization and histochemical analysis of ?-glucuronidase (GUS) activity in transgenic rice carrying an OS-ACS5-gus fusion. Whole-mount in situ hybridization revealed that in air-grown rice seedlings, OS-ACS5 was expressed at a low level in the shoot apex, meristems, leaf, and adventitious root primordia, and in vascular tissues of nonelongated stems and leaf sheaths. In response to complete submergence, the expression in vascular bundles of young stems and leaf sheaths was strongly induced. The results of histochemical GUS assays were consistent with those found by whole-mount in situ hybridization. Our findings suggest that OS-ACS5 plays a role in vegetative growth of rice under normal conditions and is also recruited for enhanced growth upon complete submergence. The possible implication of OS-ACS5 in root-shoot communication during submergence stress and its putative role in aerenchyma formation upon low-oxygen stress are discussed. PMID:12011339

  16. Chamazulene carboxylic acid and matricin: a natural profen and its natural prodrug, identified through similarity to synthetic drug substances.

    PubMed

    Ramadan, Mai; Goeters, Susanne; Watzer, Bernhard; Krause, Eva; Lohmann, Klaus; Bauer, Rudolf; Hempel, Bernd; Imming, Peter

    2006-07-01

    Chamazulene carboxylic acid (1) is a natural profen with anti-inflammatory activity and a degradation product of proazulenic sesquiterpene lactones, e.g., matricin. Both 1 and proazulenes occur in chamomile (Matricaria recutita), yarrow (Achillea millefolium), and a few other Asteraceae species. It was isolated in improved yields, characterized physicochemically, and found to be an inhibitor of cyclooxygenase-2, but not of cyclooxygenase-1. It had anti-inflammatory activity in several animal models with local and systemic application. When human volunteers were given matricin orally, plasma levels of 1 were found to be in the micromolar range. Matricin was converted to 1 in artificial gastric fluid, but not in artificial intestinal fluid. Matricin and the yarrow proazulenes are proposed to be anti-inflammatory through conversion to 1. Intriguingly, the biological activity of the natural compound 1 was found because of its similarity to fully synthetic drug substances. This is the reverse process of the common lead function of natural compounds in drug discovery. PMID:16872141

  17. Rapid adsorption of 2,4-dichlorophenoxyacetic acid by iron oxide nanoparticles-doped carboxylic ordered mesoporous carbon.

    PubMed

    Tang, Lin; Zhang, Sheng; Zeng, Guang-Ming; Zhang, Yi; Yang, Gui-De; Chen, Jun; Wang, Jing-Jing; Wang, Jia-Jia; Zhou, Yao-Yu; Deng, Yao-Cheng

    2015-05-01

    The ordered mesoporous carbon composite functionalized with carboxylate groups and iron oxide nanoparticles (Fe/OMC) was successfully prepared and used to adsorb 2,4-dichlorophenoxyacetic acid (2,4-D) from wastewater. The resultant adsorbent possessed high degree of order, large specific surface area and pore volume, and good magnetic properties. The increase in initial pollutant concentration and contact time would make the adsorption capacity increase, but the pH and temperature are inversely proportional to 2,4-D uptake. The equilibrium of adsorption was reached within 120 min, and the equilibrated adsorption capacity increased from 99.38 to 310.78 mg/g with the increase of initial concentration of 2,4-D from 100 to 500 mg/L. Notablely, the adsorption capacity reached 97% of the maximum within the first 5 min. The kinetics and isotherm study showed that the pseudo-second-order kinetic and Langmuir isotherm models could well fit the adsorption data. These results indicate that Fe/OMC has a good potential for the rapid adsorption of 2,4-D and prevention of its further diffusion. PMID:25594883

  18. Neurochemical analysis of amino acids, polyamines and carboxylic acids: GC–MS quantitation of tBDMS derivatives using ammonia positive chemical ionization

    Microsoft Academic Search

    Paul L. Wood; M. Amin Khan; Joseph R. Moskal

    2006-01-01

    The GC–MS quantitation of a large number of neurochemicals utilizing a single derivatization step is not common but is provided by the reagent N-(tert-butyldimethylsilyl)-N-methyltrifluro-acetamide (MTBSTFA). Previous workers have utilized this derivative for GC–MS analyses of amino acids, carboxylic acids and urea with electron impact (EI) and with positive chemical ionization (PCI; methane as reagent gas). However, these conditions yield significant

  19. 40 CFR 180.426 - 2-[4,5-Dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinoline carboxylic acid...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...imidazol-2-yl]-3-quinoline carboxylic acid; tolerance for residues. A tolerance is established for residues of the herbicide 2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H -imidazol-2-yl]-3-quinoline...

  20. 40 CFR 180.426 - 2-[4,5-Dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinoline carboxylic acid...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...imidazol-2-yl]-3-quinoline carboxylic acid; tolerance for residues. A tolerance is established for residues of the herbicide 2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H -imidazol-2-yl]-3-quinoline...

  1. 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...

  2. Separation of the isomers of benzene poly(carboxylic acid)s by quaternary ammonium salt via formation of deep eutectic solvents.

    PubMed

    Hou, Yucui; Li, Jian; Ren, Shuhang; Niu, Muge; Wu, Weize

    2014-11-26

    Because of similar properties and very low volatility, isomers of benzene poly(carboxylic acid)s (BPCAs) are very difficult to separate. In this work, we found that isomers of BPCAs could be separated efficiently by quaternary ammonium salts (QASs) via formation of deep eutectic solvents (DESs). Three kinds of QASs were used to separate the isomers of BPCAs, including the isomers of benzene tricarboxylic acids (trimellitic acid, trimesic acid, and hemimellitic acid) and the isomers of benzene dicarboxylic acids (phthalic acid and isophthalic acid). Among the QASs, tetraethylammonium chloride was found to have the best performance, which could completely separate BPCA isomers in methyl ethyl ketone solutions. It was found that the hydrogen bond forming between QAS and BPCA results in the selective separation of BPCA isomers. QAS in DES was regenerated effectively by the antisolvent method, and the regenerated QAS was reused four times with the same high efficiency. PMID:25351281

  3. Laccase-mediator system for alcohol oxidation to carbonyls or carboxylic acids: toward a sustainable synthesis of profens.

    PubMed

    Galletti, Paola; Pori, Matteo; Funiciello, Federica; Soldati, Roberto; Ballardini, Alberto; Giacomini, Daria

    2014-09-01

    By combining two green and efficient catalysts, such as the commercially available enzyme laccase from Trametes versicolor and the stable free radical 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO), the oxidation in water of some primary alcohols to the corresponding carboxylic acids or aldehydes and of selected secondary alcohols to ketones can be accomplished. The range of applicability of bio-oxidation is widened by applying the optimized protocol to the oxidation of enantiomerically pure 2-arylpropanols (profenols) into the corresponding 2-arylpropionic acids (profens), in high yields and with complete retention of configuration. PMID:25044433

  4. Electronically Rich N-Substituted Tetrahydroisoquinoline 3-Carboxylic Acid Esters: Concise Synthesis and Conformational Studies

    PubMed Central

    Al-Horani, Rami A.; Desai, Umesh R.

    2012-01-01

    Recent work in our laboratory has shown that the highly substituted, electronically rich 1,2,3,4–tetrahydroisoquinoline–3–carboxylic acid (THIQ3CA) scaffold is a key building block for a novel class of promising anticoagulants (Al-Horani et al. J. Med. Chem. 2011, 54, 6125–6138). The synthesis of THIQ3CA analogs, especially containing specific, electronically rich substituents, has been a challenge and essentially no efficient methods have been reported in the literature. We describe three complementary, glycine donor-based strategies for high yielding synthesis of highly substituted, electronically rich THIQ3CA esters. Three glycine donors studied herein include hydantoin 1, (±)-Boc-?-phosphonoglycine trimethyl ester 2 and (±)-Z-?-phosphonoglycine trimethyl ester 3. Although the synthesis of THIQ3CA analogs could be achieved using either of the three, an optimal, high yielding approach for the desired THIQ3CA esters was best achieved using 3 in three mild, efficient steps. Using this approach, a focused library of advanced N-arylacyl, N-arylalkyl, and bis-THIQ3CA analogs was synthesized. Variable temperature and solvent-dependent NMR chemical shift studies indicated the presence of two major conformational rotamers in 3:1 proportion for N–arylacyl–THIQ3CA analogs, which were separated by a high kinetic barrier of ~17 kcal/mol. In contrast, N–arylalkyl and bis–THIQ3CA variants displayed no rotamerism, which implicates restricted rotation around the amide bond as the origin for high-barrier conformational interconversion. This phenomenon is of major significance because structure-based drug design typically utilizes only one conformation. Overall, the work presents fundamental studies on the synthesis and conformational properties of highly substituted, electronically rich THIQ3CA analogs. PMID:22665943

  5. Chemical Analysis and Transplacental Transfer of Oseltamivir and Oseltamivir Carboxylic Acid in Pregnant Rats

    PubMed Central

    Lin, Chia-Chun; Yen, Jiin-Cherng; Wu, Yu-Tse; Lin, Lie-Chwen; Tsai, Tung-Hu

    2012-01-01

    In view of the limited information on the pharmacokinetics of oseltamivir (OSE) during pregnancy, this study aims to evaluate the placental transportation of OSE and its active metabolite oseltamivir carboxylic acid (OCA) in rats. A validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) system coupled to an in vivo transplacental model has been developed to determine OSE and OCA in the placenta, amniotic fluids and fetus of 13-day pregnant Sprague-Dawley rats. Concentrations of OSE and OCA in plasma, amniotic fluids, placenta, and fetus were measured by the validated LC-MS/MS after OSE administration (10 mg/kg, iv). The pharmacokinetic data of both analytes were examined by non-compartmental modeling. The area under the concentration-time curve (AUC) of OCA in maternal plasma was found to be 3.6 times larger than that of OSE. The AUCs of OCA in both amniotic fluid and fetus were significantly decreased, in comparison with that in maternal plasma (reduced by 76.7 and 98.1%, respectively). We found that both OSE and OCA can penetrate the placenta, amniotic fluids and fetus in rats during pregnancy; however, the penetration of OCA was much lower than that of OSE. The mother-to-fetus transfer ratio was defined as AUCfetus/AUCmother. The data demonstrated that the mother-to-fetus transfer ratio of OSE and OCA were 1.64 and 0.019, respectively, suggesting that OSE, but not OCA, penetrated through the placenta. Moreover, OCA might not be easily metabolized in the fetus due to the lack of carboxylase in the fetus. PMID:23056234

  6. catena-Poly[[di­aqua­bis­(?3-5-carboxyl­ato-1H-pyrazole-3-carb­oxy­lic acid-?3 O 3:O 3;O 5)dilithium(I)] monohydrate

    PubMed Central

    Starosta, Wojciech; Leciejewicz, Janusz

    2013-01-01

    The basic structural unit of the title polymeric ribbon, {[Li2(C5H3N2O2)2(H2O)2]·H2O}n, is a centrosymmetric dinuclear complex in which the two LiI ions are bridged by two carboxyl­ato O atoms, to generate a centrosymmetric Li2O2 core. These are connected into a chain along [01-1] by carboxylic acid–carbonyl-O bonds. The tetra­hedral coordination of the LiI cation is completed by an aqua ligand. The carboxylic acid is involved in an intra-ribbon hydrogen bond. A solvate water molecule showing positional (50:50) disorder is observed. Polymeric ribbons along [01-1] are connected by O—H?O, N—H?O and O—H?N hydrogen bonds into a three-dimensional architecture. PMID:24454029

  7. Capillary zone electrophoresis for U(VI) and short chain carboxylic acid sorption studies on silica and rutile.

    PubMed

    Sladkov, Vladimir; Zhao, Yujia; Mercier-Bion, Florence

    2011-02-15

    Capillary zone electrophoresis was used to study the uranyl and short chain carboxylic acid sorption on silica and rutile. The separation and the simultaneous determination (in a single run) of a number of short chain carboxylic acids (oxalic, formic, acetic and propionic) and U(VI) with direct UV detection is developed for the analysis of solutions after the sorption experiments. The reverse polarity mode is used (the injection is performed at the negative end). The matrix effect of Si(IV) (possible silica dissolution product) and perchlorate (added for constant ionic strength in sorption experiments) on the separation of U(VI) and organic acids is investigated. The influence of methanol addition in carrier electrolyte on the separation selectivity of given analytes is also studied. Under the chosen conditions (carbonate buffer (ionic strength of 0.1M), pH 9.8, 0.15 mM of tetradecyltrimethylammonium bromide, 25% (v/v) of methanol) the calibration curves are plotted. They are linear in two ranges of concentration from ?1×10(-5) to ?1×10(-3) M for oxalate, acetate, propionate, U(VI) and ?1×10(-4) to ?1×10(-3) for formate. The accuracy of the procedure is checked by the "added-found" method in simulation solutions. The relative standard deviations of the concentrations found are within the range of 1-10% and the recovery is in the range of 90-115%. This method is applied for the analysis of aqueous samples issued from sorption experiments on silica and rutile. The obtained results indicate that the given organic acids decrease uranium sorption both on silica and rutile. These experiments demonstrate that short chain carboxylic acids can influence the mobility and the chemistry of U(VI) in the environment. PMID:21238757

  8. Biosynthesis of 1-aminocyclopropane-1-carboxylic acid and ethylene from delta-aminolevulinic acid in ripening tomato fruits

    SciTech Connect

    El-Rayes, D.E.D.A.

    1987-01-01

    A new pathway for ethylene (C/sub 2/H/sub 4/) biosynthesis, which utilizes delta-aminolevulinic acid (ALA) as a precursor of 1-aminocyclopropane-1-carboxylic acid (ACC), the immediate precursor of C/sub 2/H/sub 4/, is presented. ALA enhanced ACC accumulation to 410% and C/sub 2/H/sub 4/ production to 232% of the control. The C/sub 2/H/sub 4/ production rate varied with the ALA concentration and the stage of tomato fruit development. As the ALA concentration increased from zero to 40 mM, the C/sub 2/H/sub 4/ production rate increased. Both treated and untreated pericarp discs from fruits at the pink stage of development yielded the largest C/sub 2/H/sub 4/ production rate. Radioactivity from (2,3-/sup 3/H)ALA was detected in both ACC and C/sub 2/H/sub 4/, and radioactivity from (4-/sup 14/C)ALA was detected in ACC and CO/sub 2/ but not in C/sub 2/H/sub 4/. However, radioactivity from (5-/sup 14/C)ALA was detected in CO/sub 2/, and its amount was greater than that obtained from (4-/sup 14/C)ALA. Neither ACC nor C/sub 2/H/sub 4/ showed any radioactivity when (5-/sup 14/C)ALA was supplied to the fruit discs. In addition, when (2,3-/sup 3/H)ALA or (4-/sup 14/C)ALA was supplied to the fruit discs, radioactivity was detected in other metabolites such as fumarate, succinate, malate, glutamate, glutamine, ..cap alpha..-ketoglutarate, and methionine, but the amount of radioactivity was insignificant as compared with the amount of radioactivity found in C/sub 2/H/sub 4/ and ACC.

  9. Perfluoroalkyl sulfonic and carboxylic acids: A critical review of physicochemical properties, levels and patterns in waters and wastewaters, and treatment methods

    Microsoft Academic Search

    Sierra Rayne; Kaya Forest

    2009-01-01

    Perfluorinated acids (PFAs) are an emerging class of environmental contaminants present in various environmental and biological matrices. Two major PFA subclasses are the perfluorinated sulfonic acids (PFSAs) and carboxylic acids (PFCAs). The physicochemical properties and partitioning behavior for the linear PFA members are poorly understood and widely debated. Even less is known about the numerous branched congeners with varying perfluoroalkyl

  10. Effect of anions on the efficiency of aromatic carboxylic acid corrosion inhibitors in near neutral media: Experimental investigation and theoretical modeling

    Microsoft Academic Search

    P. Agarwal; D. Landolt

    1998-01-01

    The influence of the nature and concentration of electrolyte anions on the efficiency of carboxylic acid based inhibitors for steel in neutral solution was studied using anodic and cathodic polarization at a rotating disk electrode. The N-ethyl-morpholine salts of a ?-benzoyl alcanoic acid model compound and of benzoic acid were used as inhibitors. Both compounds were found to inhibit the

  11. Equilibrium 2H/ 1H fractionations in organic molecules. II: Linear alkanes, alkenes, ketones, carboxylic acids, esters, alcohols and ethers

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Sessions, Alex L.; Nielsen, Robert J.; Goddard, William A., III

    2009-12-01

    Equilibrium 2H/ 1H fractionation factors (? eq) for various H positions in alkanes, alkenes, ketones, carboxylic acids, esters, alcohols, and ethers were calculated between 0 and 100 °C using vibrational frequencies from ab initio QM calculations (B3LYP/6-311G**). Results were then corrected using a temperature-dependent linear calibration curve based on experimental data for H ? in ketones ( Wang et al., 2009). The total uncertainty in reported ? eq values is estimated at 10-20‰. The effects of functional groups were found to increase the value of ? eq for H next to electron-donating groups, e.g. sbnd OR, sbnd OH or sbnd O(C dbnd O)R, and to decrease the value of ? eq for H next to electron-withdrawing groups, e.g. sbnd (C dbnd O)R or sbnd (C dbnd O)OR. Smaller but significant functional group effects are also observed for H ? and sometimes H ?. By summing over individual H positions, we estimate the equilibrium fractionation relative to water to be -90‰ to -70‰ for n-alkanes and around -100‰ for pristane and phytane. The temperature dependence of these fractionations is very weak between 0 and 100 °C. Our estimates of ? eq agree well with field data for thermally mature hydrocarbons (? 2H values between -80‰ and -110‰ relative to water). Therefore the observed ? 2H increase of individual hydrocarbons and the disappearance of the biosynthetic ? 2H offset between n-alkyl and linear isoprenoid lipids during maturation of organic matter can be confidently attributed to H exchange towards an equilibrium state. Our results also indicate that many n-alkyl lipids are biosynthesized with ? 2H values that are close to equilibrium with water. In these cases, constant down-core ? 2H values for n-alkyl lipids cannot be reliably used to infer a lack of isotopic exchange.

  12. Metabolism of benzoic acid by bacteria: 3,5-cyclohexadiene-1,2-diol-1-carboxylic acid is an intermediate in the formation of catechol.

    PubMed

    Reiner, A M

    1971-10-01

    3,5-Cyclohexadiene-1,2-diol-1-carboxylic acid (1,2-dihydro-1,2-dihydroxy-benzoic acid) is converted enzymatically to catechol in cell extracts from Acinetobacter, Alcaligenes, Azotobacter, and three Pseudomonas species. This enzymatic activity is present only in cultures which have been grown in the presence of benzoic acid, and which convert benzoic acid to catechol rather than to protocatechuic acid. The reaction is assayed by the concomitant formation of reduced nicotinamide adenine dinucleotide from nicotinamide adenine dinucleotide. The conversion of [(14)C]benzoic acid to [(14)C]dihydrodihydroxybenzoic acid is demonstrated in cell extracts. A scheme for the conversion of benzoic acid to catechol in bacteria is presented, involving the formation of dihydrodihydroxybenzoic acid from benzoic acid by a dioxygenase which is unstable in cell extracts, followed by the dehydrogenation and decarboxylation of dihydrodihydroxybenzoic acid to catechol by a previously undescribed enzyme. Experiments with anthranilic acid and phthalic acid suggest that dihydrodihydroxybenzoic acid is a metabolite unique to benzoic acid metabolism. Two new methods for assaying benzoic acid dioxygenase are suggested. PMID:4399343

  13. 10-Iodo-11H-indolo[3,2-c]quinoline-6-carboxylic Acids Are Selective Inhibitors of DYRK1A

    PubMed Central

    2015-01-01

    The protein kinase DYRK1A has been suggested to act as one of the intracellular regulators contributing to neurological alterations found in individuals with Down syndrome. For an assessment of the role of DYRK1A, selective synthetic inhibitors are valuable pharmacological tools. However, the DYRK1A inhibitors described in the literature so far either are not sufficiently selective or have not been tested against closely related kinases from the DYRK and the CLK protein kinase families. The aim of this study was the identification of DYRK1A inhibitors exhibiting selectivity versus the structurally and functionally closely related DYRK and CLK isoforms. Structure modification of the screening hit 11H-indolo[3,2-c]quinoline-6-carboxylic acid revealed structure–activity relationships for kinase inhibition and enabled the design of 10-iodo-substituted derivatives as very potent DYRK1A inhibitors with considerable selectivity against CLKs. X-ray structure determination of three 11H-indolo[3,2-c]quinoline-6-carboxylic acids cocrystallized with DYRK1A confirmed the predicted binding mode within the ATP binding site. PMID:25730262

  14. Biosynthetic mechanism of 2-acetyl-1-pyrroline and its relationship with Delta1-pyrroline-5-carboxylic acid and methylglyoxal in aromatic rice (Oryza sativa L.) callus.

    PubMed

    Huang, Tzou-Chi; Teng, Chia-Shih; Chang, Jia-Lin; Chuang, Hui-Su; Ho, Chi-Tang; Wu, Mei-Li

    2008-08-27

    2-Acetyl-1-pyrroline (2-AP) was identified as the major flavor compound in aromatic rice varieties Tainung 71 and 72. In order to understand the mechanism of 2-AP biosynthesis in aromatic rice, we studied the formation of putative precursors, Delta(1)-pyrroline-5-carboxylic acid and methylglyoxal. The endogenous Delta(1)-pyrroline-5-carboxylic acid contents of Tainung 71 and 72 calli reached 191 to 276%, compared to nonaromatic rice Tainung 67. In addition, calli of Tainung 71 and 72 contained 1.30- and 1.36-fold, respectively, higher methylglyoxal levels than that of Tainung 67. Specific enzyme activities of Delta(1)-pyrroline-5-carboxylic acid-synthetic enzyme including Delta(1)-pyrolline-5-carboxylic acid synthetase (P5CS) and ornithine aminotransferase (OAT) increased significantly in aromatic rice varieties. The expression levels of P5CS1 and P5CS2 genes were found to be significantly higher in aromatic rice than nonaromatic rice. Results of a tracer experiment with (15)N-labeled glutamic acid revealed that the nitrogen atom of 2-acetyl-1-pyrroline was derived from glutamic acid. Upregulation of P5CS in aromatic rice Tainung 72 may contribute to the increase of Delta(1)-pyrroline-5-carboxylic acid level and thus leads to the accumulation of an extra amount of 2-acetyl-1-pyrroline. PMID:18680302

  15. Acid zeta function and ajoint acid zeta function

    E-print Network

    Jining Gao

    2010-03-16

    In this paper we set up the theory of acid zeta function and ajoint acid zeta function, based on the theory, we point out a reason to doubt the truth of the Riemann hypothesis and also as a consequence, we give out some new RH equivalences.

  16. Interorgan Translocation of 1-Aminocyclopropane-1-Carboxylic Acid and Ethylene Coordinates Senescence in Emasculated Cymbidium Flowers

    PubMed Central

    Woltering, Ernst J.

    1990-01-01

    In Cymbidium flowers, emasculation by removal of the pollinia and the anther cap leads within 24 hours to red coloration of the labellum (lip). Lip coloration, being the first sign of senescence in these flowers, has been ascribed to the action of ethylene in the lip. When a small incision in the base of the lip is made prior to emasculation, or when the lip is excised and placed in water within 10 to 15 hours after emasculation, coloration is considerably delayed. This indicates that a coloration-associated factor is moving in or out of the lip. Measurements of ethylene production of excised flower parts, isolated at different times after emasculation, showed an increase only in the central column; the other flower parts, including the lip, did not show a measurable change. In contrast, in situ measurements of the ethylene production of the central column and the remaining portion of the flower revealed a simultaneous increase in all the flower parts following emasculation. Similarly, application of radiolabeled 1-aminocyclopropane-1-carboxylic acid (ACC) to the top of the central column in situ leads to the production of radiolabeled ethylene by all the flower parts. In addition, the ethylene production of isolated lips, measured immediately after excision, was initially high but ceased within 10 to 15 minutes. Treatment of the central column in situ with ethylene or ethephon did not stimulate ACC production but did stimulate lip coloration and this was accompanied by an increased internal ethylene concentration in the lip. The data indicate that endogenously produced as well as applied ACC is rapidly translocated from the site of production or application to all the other flower parts where it is immediately converted into ethylene. By excision of a flower organ, the influx of ACC is prevented, causing a rapid decrease in ethylene production. In addition, it was found that ethylene may also be translocated in physiologically significant amounts within the flower. The roles of ACC and ethylene as mobile senescence or wilting factors in emasculation- and pollination-induced senescence is discussed. PMID:16667357

  17. Coumarin-3-carboxylic acid derivatives as potentiators and inhibitors of recombinant and native N-Methyl-D-Aspartate receptors

    PubMed Central

    Irvine, Mark W.; Costa, Blaise M.; Volianskis, Arturas; Fang, Guangyu; Ceolin, Laura; Collingridge, Graham L.; Monaghan, Daniel T.; Jane, David E.

    2012-01-01

    N-Methyl-D-aspartate receptors (NMDARs) are known to be involved in a range of neurological and neurodegenerative disorders and consequently the development of compounds that modulate the function of these receptors has been the subject of intense interest. We have recently reported that 6-bromocoumarin-3-carboxylic acid (UBP608) is a negative allosteric modulator with weak selectivity for GluN2A-containing NMDARs. In the present study, a series of commercially available and newly synthesized coumarin derivatives have been evaluated in a structure-activity relationship (SAR) study as modulators of recombinant NMDAR activity. The main conclusions from this SAR study were that substituents as large as iodo were accommodated at the 6-position and that 6,8-dibromo or 6,8-diiodo substitution of the coumarin ring enhanced the inhibitory activity at NMDARs. These coumarin derivatives are therefore excellent starting points for the development of more potent and GluN2 subunit selective inhibitors, which may have application in the treatment of a range of neurological disorders such as neuropathic pain, epilepsy and depression. Surprisingly, 4-methyl substitution of UBP608 to give UBP714, led to conversion of the inhibitory activity of UBP608 into potentiating activity at recombinant GluN1/GluN2 receptors. UBP714 also enhanced NMDAR mediated field EPSPs in the CA1 region of the hippocampus. UBP714 is therefore a novel template for the development of potent and subunit selective NMDAR potentiators that may have therapeutic applicability in the treatment of patients with cognitive deficits or schizophrenia. PMID:22265875

  18. Diastereomeric complex of ( R/ S)-piperidine-3-carboxylic acid with (2 R,3 R)-tartaric acid: Structural, spectroscopic and computational studies

    NASA Astrophysics Data System (ADS)

    Bartoszak-Adamska, E.; Dega-Szafran, Z.; Jaskólski, M.; Szafran, M.

    2011-07-01

    2:2 Complex of ( R) and ( S)-piperidine-3-carboxylic acids (P3C) with (2 R,3 R) -tartaric acid (TA), 1, has been characterized by single-crystal X-ray analysis, FTIR and NMR spectroscopies, and by DFT calculations. The crystals of 1 are monoclinic, space group P2 1. The crystal structure is formed by two distinct P3CH +·TA - components, A and B, linked by an O-H⋯O hydrogen bond of 2.603(2) Å. The A and B components differ in the absolute configuration of the C(3) atom of P3CH +; ( S) in A and ( R) in B. The piperidinium-3-carboxylic acid and (2 R,3 R)-semi-tartrate anion moieties of the components A and B are linked by O-H⋯O hydrogen bonds of 2.517(1) and 2.535(1) Å, respectively. In A and B the piperidinium rings adopt the chair conformation with the carboxyl group in the equatorial position. The structures of the monomers of P3CH +·TA -, 3A and 3B, as well as of a dimer 2, have been optimized by the B3LYP/6-31G(d,p) approach. The chemical shift assignments were based on two-dimensional 1H- 1H and 1H- 13C experiments.

  19. Oxygenase-Catalyzed Desymmetrization of N,N-Dialkyl-piperidine-4-carboxylic Acids**

    PubMed Central

    Rydzik, Anna M; Leung, Ivanhoe K H; Kochan, Grazyna T; McDonough, Michael A; Claridge, Timothy D W; Schofield, Christopher J

    2014-01-01

    ?-Butyrobetaine hydroxylase (BBOX) is a 2-oxoglutarate dependent oxygenase that catalyzes the final hydroxylation step in the biosynthesis of carnitine. BBOX was shown to catalyze the oxidative desymmetrization of achiral N,N-dialkyl piperidine-4-carboxylates to give products with two or three stereogenic centers. PMID:25164544

  20. Heparinic Acids: Determination of Equivalent Weights and Sulfate to Carboxyl Ratios

    Microsoft Academic Search

    Klaus E. Kuettner; Arthur Lindenbaum

    1964-01-01

    By means of an automatic titration apparatus, a polyelectrolyte of biological origin, heparin, from two animal sources, was found to have an average equivalent weight of 170.0, a sulfate content of 34.44 percent, and a sulfate to carboxyl ratio of 2.59.

  1. Di-?-aqua-bis­[aqua­(5-carboxyl­ato-1H-1,2,3-triazole-4-carb­oxy­lic acid-?2 N 3,O 4)lithium

    PubMed Central

    Starosta, Wojciech; Leciejewicz, Janusz

    2013-01-01

    The crystal structure of the title compound, [Li2(C4H2N3O4)2(H2O)4], contains centrosymmetric dinuclear mol­ecules in which two LiI 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 carboxyl­ate group that participates in coordination to the metal ion remains protonated; the other is deprotonated and coordination inactive. An intra­molecular O—H?O hydrogen bond between carboxyl­ate 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

  2. Evidence for carbocation intermediates in the TiO[sub 2]-catalyzed photochemical fluorination of carboxylic acids

    SciTech Connect

    Cuiwei Lai; Yeong Il Kim; Chong Mou Wang; Mallouk, T.E. (Univ. of Texas, Austin (United States))

    1993-03-12

    In the past few years, laser flash photolysis studies of colloidal TiO[sub 2] suspensions have been used to determine the mechanism of photochemical reactions relevant both to solar energy conversion and to environmental remediation. Laser flash photolysis/transient absorbance spectroscopy was used to determine the mechanism of photo-Kolbe fluorination of carboxylic acids, RCOOH [yields] RF, at colloidal TiO[sub 2] suspensions in acetonitrile. Transient absorption spectra of Ph[sub 3]C[sup +], Ph[sub 3]C[sup [sm bullet

  3. Fluorescein analogue xanthene-9-carboxylic acid: a transition-metal-free CO releasing molecule activated by green light.

    PubMed

    Antony, Lovely Angel Panamparambil; Slanina, Tomáš; Šebej, Peter; Šolomek, Tomáš; Klán, Petr

    2013-09-01

    6-Hydroxy-3-oxo-3H-xanthene-9-carboxylic acid is introduced as the first transition-metal-free carbon monoxide releasing molecule activated by visible light (photoCORM). This water-soluble fluorescein analogue releases carbon monoxide in both water and methanol upon irradiation at 500 nm. When selectively irradiated in the presence of hemoglobin (Hb) under physiological conditions, released CO is quantitatively trapped to form carboxyhemoglobin (COHb). The reaction progress can be accurately monitored by characteristic absorption and emission properties of the reactants and products. PMID:23957602

  4. Surface properties of calcium and magnesium oxide nanopowders grafted with unsaturated carboxylic acids studied with inverse gas chromatography.

    PubMed

    Maciejewska, Magdalena; Krzywania-Kaliszewska, Alicja; Zaborski, Marian

    2012-09-28

    Inverse gas chromatography (IGC) was applied at infinite dilution to evaluate the surface properties of calcium and magnesium oxide nanoparticles and the effect of surface grafted unsaturated carboxylic acid on the nanopowder donor-acceptor characteristics. The dispersive components (?(s)(D)) of the free energy of the nanopowders were determined by Gray's method, whereas their tendency to undergo specific interactions was estimated based on the electron donor-acceptor approach presented by Papirer. The calcium and magnesium oxide nanoparticles exhibited high surface energies (79 mJ/m² and 74 mJ/m², respectively). Modification of nanopowders with unsaturated carboxylic acids decreased their specific adsorption energy. The lowest value of ?(s)(D) was determined for nanopowders grafted with undecylenic acid, approximately 55 mJ/m². The specific interactions were characterised by the molar free energy (?G(A)(SP)) and molar enthalpy (?H(A)(SP)) of adsorption as well as the donor and acceptor interaction parameters (K(A), K(D)). PMID:22907042

  5. 4Hydroxy2-quinolones 138. Synthesis and study of structure-biological activity relationships in a series of 1-hydroxy-3-oxo-5,6-dihydro-3H-pyrrolo[3,2,1- ij ]quinoline-2-carboxylic acid anilides

    Microsoft Academic Search

    I. V. Ukrainets; E. V. Mospanova; N. L. Bereznyakova; O. I. Naboka

    2007-01-01

    Two methods are discussed and the synthesis of a series of 1-hydroxy-3-oxo-5,6-dihydro-3H-pyrrolo[3,2,1-ij]quinoline-2-carboxylic\\u000a acid anilides has been carried out. The antitubercular activity and the effect on the urinary function of the kidney have\\u000a been studied for the compounds prepared. A structure-biological activity relationship is discussed.

  6. Solution Phase Parallel Synthesis of 4-Aminophenyl Ethers Using a Carboxyl-Functionalized Ionic Liquid as Support

    Microsoft Academic Search

    Yanqing Peng; Fengping Yi; Gonghua Song; Ying Zhang

    2005-01-01

    Summary. A small sortiment of 4-aminophenyl ether derivatives was constructed with good yields and purities via Williamson reaction using the carboxyl-functionalized ionic liquid [cmmim][BF4] as soluble support. The recovered ionic liquid could be reused for several times with similar capacity.

  7. (S)-1-(4-Dimethylaminophenylcarbonyl)-3-aminopyrrolidine: a derivatization reagent for enantiomeric separation and sensitive detection of chiral carboxylic acids by LC/ESI-MS/MS.

    PubMed

    Ogawa, Shoujiro; Tadokoro, Hiroaki; Sato, Maho; Hanawa, Takehisa; Higashi, Tatsuya

    2013-12-01

    A novel derivatization reagent, (S)-1-(4-dimethylaminophenylcarbonyl)-3-aminopyrrolidine (1-DAPAP), was developed for increasing the detection sensitivity and enantiomeric separation of chiral carboxylic acids by liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS). 1-DAPAP reacted with carboxylic acids at room temperature within 5min in the presence of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride. The epimerization (racemization) during the derivatization reaction was negligible. The resulting derivatives were highly responsive during the ESI-MS operating in the positive-ion mode and gave a characteristic product ion during the MS/MS, which enabled the sensitive detection using selected reaction monitoring; the detection responses of the 1-DAPAP-derivatives were increased by 10-1100-fold over the intact carboxylic acids and the limits of detection ranged from 0.97 and 5.2fmol on the column. The 1-DAPAP-derivatization was also effective for the enantiomeric separation of chiral carboxylic acids; the resolution values were 1.2-4.3 for the evaluated carboxylic acids. The derivatization procedure was successfully applied to biological sample analyses; the derivatization followed by LC/ESI-MS/MS enabled the separation and detection of trace amounts of ibuprofen and naproxen in human saliva with a simple pretreatment and small sample volume. PMID:24131653

  8. Novel Regenerated Solvent Extraction Processes for the Recovery of Carboxylic Acids or Ammonia from Aqueous Solutions Part II. Recovery of Ammonia from Sour Waters

    Microsoft Academic Search

    L. J. Poole; C. J. King

    1990-01-01

    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 and HS) from industrial sour waters. The

  9. Speciation of aqueous Ni(II)-carboxylate and Ni(II)-fulvic acid solutions: Combined ATR-FTIR and XAFS analysis

    NASA Astrophysics Data System (ADS)

    Strathmann, Timothy J.; Myneni, Satish C. B.

    2004-09-01

    Aqueous solutions containing Ni(II) and a series of structurally related carboxylic acids were analyzed using attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and Ni K-edge X-ray absorption fine structure spectroscopy (XAFS). XAFS spectra were also collected for solutions containing Ni 2+ and chelating ligands (ethylenediaminetetraacetic acid, nitrilotriacetic acid (NTA)) as well as soil fulvic acid. Limited spectral changes are observed for aqueous Ni(II) complexes with monocarboxylates (formate, acetate) and long-chain polycarboxylates (succinate, tricarballylate), where individual donor groups are separated by multiple bridging methylene groups. These spectral changes indicate weak interactions between Ni(II) and carboxylates, and the trends are similar to some earlier reports for crystalline Ni(II)-acetate solids, for which X-ray crystallography studies have indicated monodentate Ni(II)-carboxylate coordination. Nonetheless, electrostatic or outer-sphere coordination cannot be ruled out for these complexes. However, spectral changes observed for short-chain dicarboxylates (oxalate, malonate) and carboxylates that contain an alcohol donor group adjacent to one of the carboxylate groups (lactate, malate, citrate) demonstrate inner-sphere metal coordination by multiple donor groups. XAFS spectral fits of Ni(II) solutions containing soil fulvic acid are consistent with inner-sphere Ni(II) coordination by one or more carboxylate groups, but spectra are noisy and outer-sphere modes of coordination cannot be ruled out. These molecular studies refine our understanding of the interactions between carboxylates and weakly complexing divalent transition metals, such as Ni(II).

  10. Synthesis, characterization, theoretical study and biological activities of oxovanadium (IV) complexes with 2-thiophene carboxylic acid hydrazide.

    PubMed

    Jabeen, Mudassir; Ali, Saqib; Shahzadi, Saira; Sharma, Saroj K; Qanungo, Kushal

    2014-07-01

    Oxovanadium (IV) complexes (1)-(3) have been synthesized by treating 2-thiophene carboxylic acid hydrazide with VOSO4?xH2O and VCl3(THF)3 in different M/L ratios. These complexes have been characterized by elemental analysis, UV-vis, FT-IR and mass spectrometry. The FT-IR data predicts the bidentate nature of the ligand which is also confirmed by semi-empirical study. Mass spectrometric data shows that molecular ion peak is only observed for 2-thiophene carboxylic acid hydrazide. The ESP map and thermodynamic parameters shows the presence of partial charge on atoms and stability of synthesized oxovanadium complexes, respectively. DNA binding study of complexes (1)-(3) was carried out by UV-vis and cyclic voltammetric methods which suggests the intercalative binding mode of the complexes with DNA. Cytotoxicity was checked by brine shrimp lethality assay and complex (1) showed greater cytotoxicity towards Artemia salina as compared to free ligand. Immuno-modulatory activity data shows that hydrazide ligand was more active as compared to oxovanadium complexes and standard drug. Complex (2) shows significant urease inhibition activity. The ligand and synthesized complexes were found inactive against all tested bacterial and fungal strains. PMID:24844618

  11. Systematic evaluation and optimization of modification reactions of oligonucleotides with amines and carboxylic acids for the synthesis of DNA-encoded chemical libraries.

    PubMed

    Franzini, Raphael M; Samain, Florent; Abd Elrahman, Maaly; Mikutis, Gediminas; Nauer, Angela; Zimmermann, Mauro; Scheuermann, Jörg; Hall, Jonathan; Neri, Dario

    2014-08-20

    DNA-encoded chemical libraries are collections of small molecules, attached to DNA fragments serving as identification barcodes, which can be screened against multiple protein targets, thus facilitating the drug discovery process. The preparation of large DNA-encoded chemical libraries crucially depends on the availability of robust synthetic methods, which enable the efficient conjugation to oligonucleotides of structurally diverse building blocks, sharing a common reactive group. Reactions of DNA derivatives with amines and/or carboxylic acids are particularly attractive for the synthesis of encoded libraries, in view of the very large number of building blocks that are commercially available. However, systematic studies on these reactions in the presence of DNA have not been reported so far. We first investigated conditions for the coupling of primary amines to oligonucleotides, using either a nucleophilic attack on chloroacetamide derivatives or a reductive amination on aldehyde-modified DNA. While both methods could be used for the production of secondary amines, the reductive amination approach was generally associated with higher yields and better purity. In a second endeavor, we optimized conditions for the coupling of a diverse set of 501 carboxylic acids to DNA derivatives, carrying primary and secondary amine functions. The coupling efficiency was generally higher for primary amines, compared to secondary amine substituents, but varied considerably depending on the structure of the acids and on the synthetic methods used. Optimal reaction conditions could be found for certain sets of compounds (with conversions >80%), but multiple reaction schemes are needed when assembling large libraries with highly diverse building blocks. The reactions and experimental conditions presented in this article should facilitate the synthesis of future DNA-encoded chemical libraries, while outlining the synthetic challenges that remain to be overcome. PMID:25061844

  12. Exploring the chemical space of ureidothiophene-2-carboxylic acids as inhibitors of the quorum sensing enzyme PqsD from Pseudomonas aeruginosa.

    PubMed

    Sahner, J Henning; Empting, Martin; Kamal, Ahmed; Weidel, Elisabeth; Groh, Matthias; Börger, Carsten; Hartmann, Rolf W

    2015-05-26

    Pseudomonas aeruginosa employs a quorum sensing (QS) communication system that makes use of small diffusible molecules. Among other effects, the QS system coordinates the formation of biofilm which decisively contributes to difficulties in the therapy of Pseudomonas infections. The present work deals with the structure-activity exploration of ureidothiophene-2-carboxylic acids as inhibitors of PqsD, a key enzyme in the biosynthetic pathway of signal molecules in the Pseudomonas QS system. We describe an improvement of the inhibitory activity by successfully combining features from two different PqsD inhibitor classes. Furthermore the functional groups, which are responsible for the inhibitory potency, were identified. Moreover, the inability of the new inhibitors, to prevent signal molecule formation in whole cell assays, is discussed. PMID:25874327

  13. Rhodium(III)-Catalyzed ortho C?H Heteroarylation of (Hetero)aromatic Carboxylic Acids: A Rapid and Concise Access to ?-Conjugated Poly-heterocycles.

    PubMed

    Qin, Xurong; Li, Xiaoyu; Huang, Quan; Liu, Hu; Wu, Di; Guo, Qiang; Lan, Jingbo; Wang, Ruilin; You, Jingsong

    2015-06-01

    Rh(III) -catalyzed oxidative C?H/C?H cross-coupling between (hetero)aromatic carboxylic acids and various heteroarenes has been accomplished to construct highly functionalized ortho-carboxy-substituted bi(hetero)aryls. The use of a carboxy group as the directing group obviates tedious steps for installation and removal of extra directing groups, and enables a facile one-step synthesis of ortho-carboxy bi(hetero)aryls. The method provides opportunities for rapid assembly of a library of important fluorene and coumarin-type poly-heterocycles through intramolecular electrophilic substitution or oxidative lactonization. As illustrative examples, the strategy developed herein greatly streamlines accesses to a variety of appealing polyheterocycles such as DTPO (5H-dithieno[3,2-b:2',3'-d]pyran-5-one), CPDTO (cyclopentadithiophen-4-one), and indenothiophenes. PMID:25917223

  14. Conformational equilibria and large-amplitude motions in dimers of carboxylic acids: rotational spectrum of acetic acid-difluoroacetic acid.

    PubMed

    Gou, Qian; Feng, Gang; Evangelisti, Luca; Caminati, Walther

    2014-10-01

    We report the rotational spectra of two conformers of the acetic acid-difluoroacetic acid adduct (CH3COOH-CHF2COOH) and supply information on its internal dynamics. The two conformers differ from each other, depending on the trans or gauche orientation of the terminal -CHF2 group. Both conformers display splittings of the rotational transitions, due to the internal rotation of the methyl group of acetic acid. The corresponding barriers are determined to be V3(trans)=99.8(3) and V3(gauche)=90.5(9) cm(-1) (where V3 is the methyl rotation barrier height). The gauche form displays a further doubling of the rotational transitions, due to the tunneling motion of the -CHF2 group between its two equivalent conformations. The corresponding B2 barrier is estimated to be 108(2) cm(-1). The increase in the distance between the two monomers upon OH?OD deuteration (the Ubbelohde effect) is determined. PMID:25056445

  15. Direct Synthesis of Amides from Carboxylic Acids and Amines Using B(OCH2CF3)3

    PubMed Central

    2013-01-01

    B(OCH2CF3)3, prepared from readily available B2O3 and 2,2,2-trifluoroethanol, is as an effective reagent for the direct amidation of a variety of carboxylic acids with a broad range of amines. In most cases, the amide products can be purified by a simple filtration procedure using commercially available resins, with no need for aqueous workup or chromatography. The amidation of N-protected amino acids with both primary and secondary amines proceeds effectively, with very low levels of racemization. B(OCH2CF3)3 can also be used for the formylation of a range of amines in good to excellent yield, via transamidation of dimethylformamide. PMID:23586467

  16. Isolation and Identification of Two l-Azetidine-2-carboxylic Acid-Degrading Soil Microorganisms, Enterobacter agglomerans and Enterobacter amnigenus

    PubMed

    Yeung; Lee; Woodard

    1998-02-27

    Soil samples collected at several times during the growing season and at different locations within Convallaria majalis beds in Ann Arbor, MI, were screened for their ability to grow with the cyclic amino acid, l-azetidine-2-carboxylic acid (l-A-2-C), as their sole nitrogen source (i.e., metabolize l-A-2-C). Two different soil microorganisms were isolated, characterized, and identified using fundamental selection methods, the standard battery of biochemical characterization tests, and scanning electron microscopy. The assignment of the identity of these organisms as Enterobacter agglomerans and Enterobacter amnigenus was further verified by comparison with authentic microbial samples obtained from ATCC that were able to utilize l-A-2-C as their sole nitrogen source. PMID:9548848

  17. Synthesis and cytotoxic activity of derivatives of the tert -butyl ester of 7 Z -acetylmethylene-3-methyl-3-cephem-4-carboxylic acid

    Microsoft Academic Search

    I. Potorocina; M. Vorona; G. Veinberg; I. Shestakova; I. Kanepe; M. Petrova; E. Liepinsh; E. Lukevics

    2009-01-01

    The condensation of the acetylmethylene group in the tert-butyl esters of 7Z-acetylmethylene-3-methyl-3-cephem-4-carboxylic acid and 7Z-acetylmethylene-3-methyl-1,1-dioxo-3-cephem-4-carboxylic acid and in 7Z-acetylmethylene-3-methylene-1,1-dioxo-3-cephem with arylmethoxyamines and O-alkylation of the tert-butyl ester of 7Z-(2-hydroxyimino)propylidene-3-methyl-1,1-dioxo-3-cephem-4-carboxylic acid using substituted benzyl bromides as well as pyridylmethyl\\u000a chlorides gave arylmethoxyimino and pyridylmethoxyimino derivatives of these compounds in the syn and anti isomeric forms.\\u000a The Vilsmaier reagent was used to

  18. Origin of the 900 cm-1 broad double-hump OH vibrational feature of strongly hydrogen-bonded carboxylic acids

    NASA Astrophysics Data System (ADS)

    Van Hoozen, Brian L.; Petersen, Poul B.

    2015-03-01

    Medium and strong hydrogen bonds are common in biological systems. Here, they provide structural support and can act as proton transfer relays to drive electron and/or energy transfer. Infrared spectroscopy is a sensitive probe of molecular structure and hydrogen bond strength but strongly hydrogen-bonded structures often exhibit very broad and complex vibrational bands. As an example, strong hydrogen bonds between carboxylic acids and nitrogen-containing aromatic bases commonly display a 900 cm-1 broad feature with a remarkable double-hump structure. Although previous studies have assigned this feature to the OH, the exact origin of the shape and width of this unusual feature is not well understood. In this study, we present ab initio calculations of the contributions of the OH stretch and bend vibrational modes to the vibrational spectrum of strongly hydrogen-bonded heterodimers of carboxylic acids and nitrogen-containing aromatic bases, taking the 7-azaindole—acetic acid and pyridine—acetic acid dimers as examples. Our calculations take into account coupling between the OH stretch and bend modes as well as how both of these modes are affected by lower frequency dimer stretch modes, which modulate the distance between the monomers. Our calculations reproduce the broadness and the double-hump structure of the OH vibrational feature. Where the spectral broadness is primarily caused by the dimer stretch modes strongly modulating the frequency of the OH stretch mode, the double-hump structure results from a Fermi resonance between the out of the plane OH bend and the OH stretch modes.

  19. Origin of the 900 cm(-1) broad double-hump OH vibrational feature of strongly hydrogen-bonded carboxylic acids.

    PubMed

    Van Hoozen, Brian L; Petersen, Poul B

    2015-03-14

    Medium and strong hydrogen bonds are common in biological systems. Here, they provide structural support and can act as proton transfer relays to drive electron and/or energy transfer. Infrared spectroscopy is a sensitive probe of molecular structure and hydrogen bond strength but strongly hydrogen-bonded structures often exhibit very broad and complex vibrational bands. As an example, strong hydrogen bonds between carboxylic acids and nitrogen-containing aromatic bases commonly display a 900 cm(-1) broad feature with a remarkable double-hump structure. Although previous studies have assigned this feature to the OH, the exact origin of the shape and width of this unusual feature is not well understood. In this study, we present ab initio calculations of the contributions of the OH stretch and bend vibrational modes to the vibrational spectrum of strongly hydrogen-bonded heterodimers of carboxylic acids and nitrogen-containing aromatic bases, taking the 7-azaindole--acetic acid and pyridine--acetic acid dimers as examples. Our calculations take into account coupling between the OH stretch and bend modes as well as how both of these modes are affected by lower frequency dimer stretch modes, which modulate the distance between the monomers. Our calculations reproduce the broadness and the double-hump structure of the OH vibrational feature. Where the spectral broadness is primarily caused by the dimer stretch modes strongly modulating the frequency of the OH stretch mode, the double-hump structure results from a Fermi resonance between the out of the plane OH bend and the OH stretch modes. PMID:25770541

  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. Analysis of carboxyl tail function in the skeletal muscle Cl- channel hClC-1.

    PubMed

    Ma, Linlin; Rychkov, Grigori Y; Hughes, Bernard P; Bretag, Allan H

    2008-07-01

    Human ClC-1 (skeletal muscle Cl- channel) has a long cytoplasmic C-tail (carboxyl tail), containing two CBS (cystathionine beta-synthase) domains, which is very important for channel function. We have now investigated its significance further, using deletion and alanine-scanning mutagenesis, split channels, GST (glutathione transferase)-pull-down and whole-cell patch-clamping. In tagged split-channel experiments, we have demonstrated strong binding between an N-terminal membrane-resident fragment (terminating mid-C-tail at Ser(720) and containing CBS1) and its complement (containing CBS2). This interaction is not affected by deletion of some sequences, suggested previously to be important, particularly in channel gating. Contact between CBS1 and CBS2, however, may make a major contribution to assembly of functional channels from such co-expressed complements, although the possibility that C-tail fragments could, in addition, bind to other parts of the membrane-resident component has not been eliminated. We now show such an interaction between a membrane-resident component terminating at Ser(720) (but with CBS1 deleted) and a complete C-tail beginning at Leu(598). Channel function is rescued in patch-clamped HEK-293T (human embryonic kidney) cells co-expressing these same fragments. From our own results and those of others, we conclude that the CBS1-CBS2 interaction is not sufficient, in itself, for channel assembly, but rather that this might normally assist in bringing some part of the CBS2/C-tail region into appropriate proximity with the membrane-resident portion of the protein. Previously conflicting and anomalous results can now be explained by an hypothesis that, for split channels to be functional, at least one membrane-resident component must include a plasma membrane trafficking signal between Leu(665) and Lys(680). PMID:18321245

  2. Differences in the length of the carboxyl terminus mediate functional properties of neurokinin-1 receptor

    Microsoft Academic Search

    Jian-Ping Lai; Saien Lai; Florin Tuluc; Morris F. Tansky; Laurie E. Kilpatrick; Susan E. Leeman; Steven D. Douglas

    2008-01-01

    The neurokinin-1 receptor (NK1R) has two naturally occurring forms that differ in the length of the carboxyl terminus: a full-length receptor consisting of 407 aa and a truncated receptor consisting of 311 aa. We examined whether there are differential signaling properties attributable to the carboxyl terminus of this receptor by using stably transfected human embryonic kidney (HEK293) cell lines that

  3. Comparison of CO2 and oxygen DC submerged thermal plasmas for decomposition of carboxylic acid in aqueous solution

    NASA Astrophysics Data System (ADS)

    Safa, S.; Hekmat-Ardakan, A.; Soucy, G.

    2014-11-01

    The feasibility of the carboxylic acid decomposition with two different direct current (DC) thermal plasma torches was investigated. An oxygen DC submerged thermal plasma torch and a newly designed submerged DC plasma torch operating with a mixture of carbon dioxide and methane (CO2/CH4) were used. Sebacic acid was selected as a representative of pollutants in the most wastewater produced by chemical process industries. The effect of different operational conditions including treatment time, the reactor pressure as well as the role of oxidizing agents such as (H2O2) were investigated on the decomposition rate of sebacic acid. Concentration of sebacic acid was quantified by Ion Chromatography/Mass Spectrometry (IC/MS). The oxygen plasma showed higher decomposition rate in basic medium. Adding H2O2 into aqueous solution enhanced the sebacic acid decomposition rate with the CO2/CH4 plasma up to the same decomposition rate of the oxygen plasma. Increasing the pressure also increased the decomposition rate for both plasmas with an increase twice higher for the CO2/CH4 plasma than that of the oxygen plasma. This work therefore presents the conditions in which these plasmas can provide the same decomposition rate for contaminants in aqueous solution.

  4. DNA damage in human skin keratinocytes caused by multiwalled carbon nanotubes with carboxylate functionalization.

    PubMed

    McShan, Danielle; Yu, Hongtao

    2014-07-01

    Water-soluble carbon nanotubes have been found to be one of the most promising nanomaterials in biological- and biomedical-based applications. However, there have been major concerns on their ability to cause cellular and DNA damages upon exposure. In this work, we explore the toxic effects of three multiwalled carbon nanotubes (MWCNTs: nonpurified, purified and carboxylate-functionalized) on human skin keratinocytes (HaCaT). Cytotoxicity tests using the conventional thiazolyl blue tetrazolium bromide (MTT) and the water-soluble tetrazolium (WST-1) assays for 0.5 or 24 h exposure to 20 ?g/mL of MWCNTs show that all three caused minimum cytotoxicity that is generally not statistically significant. Assessment of direct and oxidative DNA damages using both alkaline Comet assay and formamidopyrimidine DNA glycosylase-modified Comet assay reveals that the treatment with 20 ?g/mL of MWCNTs does not cause significant direct DNA damages, but causes great amount of oxidative DNA damages in HaCaT cells. The oxidative DNA damage reaches the maximum amount at 4 h of incubation in Dulbecco's minimum essential medium, but decreases to the minimum at 8 and 24 h of incubation, indicating repair of the oxidative damages by the intrinsic DNA repair mechanism of the cells. PMID:23012341

  5. Functional nucleic acid probes and uses thereof

    DOEpatents

    Nilsen-Hamilton, Marit

    2006-10-03

    The present invention provides functional nucleic acid probes, and methods of using functional nucleic acid probes, for binding a target to carry out a desired function. The probes have at least one functional nucleic acid, at least one regulating nucleic acid, and at least one attenuator. The functional nucleic acid is maintained in an inactive state by the attenuator and activated by the regulating nucleic acid only in the presence of a regulating nucleic acid target. In its activated state the functional nucleic acid can bind to its target to carry out a desired function, such as generating a signal, cleaving a nucleic acid, or catalyzing a reaction.

  6. QSTR studies regarding the ECOSAR toxicity of benzene-carboxylic acid' esters to fathead minnow fish (Pimephales promelas).

    PubMed

    Tarko, Laszlo; Putz, Mihai V; Ionascu, Cosmin; Putz, Ana-Maria

    2014-01-01

    The present work employs 152 benzene-carboxylic acid' esters having computed the toxicity within the range [2.251, 10.222] for fathead minnow fish (Pimephales promelas). Calibration set includes many pairs having very similar chemical structure, size, shape and hydrophilicity, but very different value of ECOSAR toxicity or vice versa. The QSTR study, which uses all esters as calibration set, emphasized a large percent (16.2%) of outliers. In this QSTR study most of the estimated values of toxicity for outliers are much lower than ECOSAR toxicity. The LogP and some aromaticity descriptors are predictors. The best QSTR for esters having low value (< 5.5) of ECOSAR toxicity and the best QSTR for esters having high value (> 5.5) of ECOSAR toxicity are obtained when the number of outliers is very small. These QSTRs are different enough and highlight opposite influences of certain descriptors on toxicity. The results emphasize two possibilities: (a) the esters having low value of ECOSAR toxicity and the esters having high value of ECOSAR toxicity are included in two different classes from the point of view of structure-toxicity relationship and/or (b) many high values of ECOSAR toxicity are wrong. By comparison, a QSTR using experimental values of toxicity against rats for 37 benzene-carboxylic esters included in the same database gives good correlation experimental/computed values of toxicity, the number of outliers is null and the result of validation test is good. PMID:24724900

  7. Biosynthesis of 8-hydroxyquinoline-2-carboxylic acid, an iron chelator from the gut of the lepidopteran Spodoptera littoralis.

    PubMed

    Pesek, Jelena; Svoboda, Ji?í; Sattler, Martina; Bartram, Stefan; Boland, Wilhelm

    2015-01-01

    In the regurgitate (foregut content) of Spodoptera larvae we found high concentrations (0.5-5 mM) of 8-hydroxyquinoline-2-carboxylic acid (8-HQA). In a survey of different lepidopteran species, this compound was only detected in species belonging to the family of Noctuidae. 8-HQA was shown to derive from tryptophan metabolism. The amount of 8-HQA in the regurgitate was strongly dependent on the tryptophan content of the diet. In the insect 8-HQA is generated from tryptophan via kynurenine and 3-hydroxykynurenine. 8-HQA is produced by the larvae and not by their commensal gut bacteria. Analysis of different life stages of Spodoptera larvae revealed that 8-HQA is formed during the larval stage, probably acting as an iron chelator to control the gut microbiome. PMID:25356857

  8. Structural and Binding Analysis of Pyrimidinol Carboxylic Acid and N-Hydroxy Quinazolinedione HIV-1 RNase H Inhibitors?

    PubMed Central

    Lansdon, Eric B.; Liu, Qi; Leavitt, Stephanie A.; Balakrishnan, Mini; Perry, Jason K.; Lancaster-Moyer, Candra; Kutty, Nilima; Liu, Xiaohong; Squires, Neil H.; Watkins, William J.; Kirschberg, Thorsten A.

    2011-01-01

    HIV-1 RNase H breaks down the intermediate RNA-DNA hybrids during reverse transcription, requiring two divalent metal ions for activity. Pyrimidinol carboxylic acid and N-hydroxy quinazolinedione inhibitors were designed to coordinate the two metal ions in the active site of RNase H. High-resolution (1.4 Å to 2.1 Å) crystal structures were determined with the isolated RNase H domain and reverse transcriptase (RT), which permit accurate assessment of the metal and water environment at the active site. The geometry of the metal coordination suggests that the inhibitors mimic a substrate state prior to phosphodiester catalysis. Surface plasmon resonance studies confirm metal-dependent binding to RNase H and demonstrate that the inhibitors do not bind at the polymerase active site of RT. Additional evaluation of the RNase H site reveals an open protein surface with few additional interactions to optimize active-site inhibitors. PMID:21464257

  9. Effects of Age, Water Stress, and 1-Aminocyclopropane-1-carboxylic Acid on Leaflet Movement in Albizzia julibrissin1

    PubMed Central

    Lee, Youngsook; Satter, Ruth L.

    1983-01-01

    The movement patterns of Albizzia julibrissin leaflets transferred from light to darkness differ for leaflets of different age: the older the leaflet, the slower and less completely it closes. Water stress, which enhances ethylene synthesis in other plants, and 1-aminocyclopropane-1-carboxylic acid (ACC), precursor of ethylene, both mimic the effect of aging by reducing the rate and extent of dark-induced closure. Brief far-red compared to red irradiation before darkness does not appear to alter the closure of young leaflets, but far-red preirradiation retards the closure of middle-aged and old leaflets floating on water, and middle-aged leaflets treated with ACC. A change in some membrane property and/or cell wall lignification are suggested as possible explanations for the alteration of leaflet movement. PMID:16662885

  10. Ethylene-promoted malonylation of 1-aminocyclopropane-1-carboxylic acid participates in autoinhibition of ethylene synthesis in grapefruit flavedo discs.

    PubMed

    Liu, Y; Hoffman, N E; Yang, S F

    1985-07-01

    The increase in ethylene formation and in 1-aminocyclopropane-1-carboxylic acid (ACC) content in flavedo tissue of grapefruit (Citrus paradisi Macfad. cv. Ruby Red) in response to excision was markedly inhibited by exogenous ethylene. Ethylene treatment inhibited the synthesis of ACC, but increased the tissue's capability to malonylate ACC to N-malonyl-ACC, resulting in further reduction in the endogenous ACC content. The development of extractable ACC-malonyl-transferase activity in the tissue was markedly promoted by treatment with exogenous ethylene. These results indicate that the autoinhibition of ethylene production in this tissue results not only from suppression of ACC synthesis, but also from promotion of ACC malonylation; both processes reduce the availability of ACC for ethylene synthesis. PMID:24248233

  11. Effect of 1-Aminocyclopropane-1-carboxylic acid and aminoethoxyvinylglycine on ethylene emanation and somatic embryogenesis from orchardgrass leaf cultures.

    PubMed

    Songstad, D D; Petracek, P D; Sams, C E; Conger, B V

    1989-03-01

    Ethylene emanation rates were assessed from leaf tissues of an embryogenic seed plant (Cycle 0) and regeneration cycle plants selected for enhanced embryogenesis (Cycles I, II and IV). In all experiments, ethylene was assessed from the basal 1 cm portion of the innermost leaf. Ethylene emanation was five-fold higher in Cycle II and Cycle IV plants than in Cycle 0 and nonembryogenic (NE) seed plants. After two days culture on Schenk and Hildebrandt medium containing 30 ?M dicamba (SH-30), ethylene emanation from Cycle 0 and Cycle II leaf sections increased by 55-fold. Culture of leaf explants for 30 days on SH-30 containing 1 mM 1-aminocyclopropane-1-carboxylic acid (ACC) reduced the embryogenic response by 99%. Treatment of leaf explants with 1 mM aminoethoxyvinylglycine (AVG) reduced ethylene emanation but did not affect embryogenesis. The data indicate that ethylene mediated by ACC may hinder the embryogenic response from orchardgrass leaf cultures. PMID:24240460

  12. ANALYSIS OF PERFLUORINATED CARBOXYLIC ACIDS IN SOILS: DETECTION AND QUANTITATION ISSUES AT LOW CONCENTRATIONS

    EPA Science Inventory

    Methods were developed for the extraction from soil, identification, confirmation and quantitation by LC/MS/MS of trace levels of perfluorinated octanoic acid (PFOA), perfluorinated nonanoic acid (PFNA) and perfluorinated decanoic acid (PFDA). Whereas PFOA, PFNA and PFDA all can...

  13. Carboxylic acid sorption on synthetic clays in marine water: in vitro experiments and implications for organo-clay behaviour under marine conditions

    E-print Network

    1 Carboxylic acid sorption on synthetic clays in marine water: in vitro experiments and implications for organo-clay behaviour under marine conditions Sylvain Drouin a , Mohammed Boussafir a* , Jean to investigate the role of clay minerals in organic matter preservation, the fixation of pure organic compounds

  14. THERMAL DESORPTION MASS SPECTROMETRIC ANALYSIS OF ORGANIC AEROSOL FORMED FROM REACTIONS OF 1-TETRADECENE AND O3 IN THE PRESENCE OF ALCOHOLS AND CARBOXYLIC ACIDS. (R826235)

    EPA Science Inventory

    The chemistry of secondary organic aerosol formation from reactions of 1-tetradecene and O3 in dry air in the presence of excess alcohols and carboxylic acids was investigated in an environmental chamber using a thermal desorption particle beam mass spec...

  15. 6-Hydroxy-1,2,3,4-tetrahydro-isoquinoline-3-carboxylic acid mimics active conformation of tyrosine in opioid peptides.

    PubMed

    Sperlinga, Emanuela; Kosson, Piotr; Urbanczyk-Lipkowska, Zofia; Ronsisvalle, Giuseppe; Carr, Daniel B; Lipkowski, Andrzej W

    2005-05-16

    6-Hydroxy-1,2,3,4-tetrahydro-isoquinoline-3-carboxylic acid (6Htc) has been proposed as a rigid mimic of tyrosine conformation in opioid ligand-receptor complex. The significant receptor binding to mu and delta opioid receptors of respective analogues of deltorphin, dermorphin, and endomorphin with D,L-6Htc prove initial prediction. PMID:15863298

  16. Singlet oxygen reactions of 3-methoxy-2-pyrrole carboxylic acid tert-butyl esters. A route to 5-substituted pyrrole precursors of prodigiosin and analogs

    Microsoft Academic Search

    Harry H. Wasserman; Mingde Xia; Jianji Wang; Anders K. Petersen; Michael Jorgensen; Patricia Power; Jonathan Parr

    2004-01-01

    Reaction of the tert-butyl ester of 3-methoxy-2-pyrrole carboxylic acid with singlet oxygen yields a peroxidic intermediate which undergoes coupling with a range of nucleophiles to yield 5-substituted pyrroles. Among these products are ?,??-bipyrroles which serve as precursors of prodigiosin, including A-ring substituted analogues.

  17. Electronic and optical response of Ru(II) complexes functionalized by methyl, carboxylate groups: joint theoretical and experimental study

    SciTech Connect

    Tretiak, Sergei [Los Alamos National Laboratory

    2008-01-01

    New photovoltaic and photocatalysis applications have been recently proposed based on the hybrid Ru(II)-bipyridine-complex/semiconductor quantum dot systems. In order to attach the complex to the surface of a semiconductor, a linking bridge - a carboxyl group - is added to one or two of the 2,2{prime}-bipyridine ligands. Such changes in the ligand structure, indeed, affect electronic and optical properties and consequently, the charge transfer reactivity of Ru-systems. In this study, we apply both theoretical and experimental approaches to analyze the effects brought by functionalization of bipyridine ligands with the methyl, carboxyl, and carboxilate groups on the electronic structure and optical response of the Ru(II) bipyridine complex. First principle calculations based on density functional theory (DFT) and linear response time dependent density functional theory (TDDFT) are used to simulate the ground and excited-state structures of functionalized Ru-complexes in the gas phase, as well as in acetonitrile solution. In addition, an inelaborate Frenkel exciton model is used to explain the optical activity and splitting patterns of the low-energy excited states. All theoretical results nicely complement experimental absorption spectra of Ru-complexes and contribute to their interpretation. We found that the carboxyl group breaks the degeneracy of two low-energy optically bright excited states and red-shifts the absorption spectrum, while leaves ionization and affinity energies of complexes almost unchanged. Experimental studies show a high probability of deprotonation of the carbboxyl group in the Ru-complexes resulted in a slight blue shift and decrease of intensities of the low energy absorption peaks. Comparison of experimental and theoretical linear response spectra of deprotanated complexes demonstrate strong agreement when acetonitrile solvent is used in simulations. A polar solvent is found to play an important role in calculations of optical spectra: it stabilizes the energy of states localized on the carboxyl or carboxylate groups eliminating artificial charge transport states, which typically appear in TDDFT calculations. Thus, it is validated that the excited-state structure of the functionalized Ru-complexes, specifically in the case of the deprotonated functions, can be accurately modeled by TDDFT with the addition of a dielectric continuum in simulations.

  18. Determination of short chain carboxylic acids in vegetable oils and fats using ion exclusion chromatography electrospray ionization mass spectrometry.

    PubMed

    Viidanoja, Jyrki

    2015-02-27

    A new method for quantification of short chain C1-C6 carboxylic acids in vegetable oils and fats by employing Liquid Chromatography Mass Spectrometry (LC-MS) has been developed. The method requires minor sample preparation and applies non-conventional Electrospray Ionization (ESI) liquid phase chemistry. Samples are first dissolved in chloroform and then extracted using water that has been spiked with stable isotope labeled internal standards that are used for signal normalization and absolute quantification of selected acids. The analytes are separated using Ion Exclusion Chromatography (IEC) and detected with Electrospray Ionization Mass Spectrometry (ESI-MS) as deprotonated molecules. Prior to ionization the eluent that contains hydrochloric acid is modified post-column to ensure good ionization efficiency of the analytes. The averaged within run precision and between run precision were generally lower than 8%. The accuracy was between 85 and 115% for most of the analytes. The Lower Limit of Quantification (LLOQ) ranged from 0.006 to 7mg/kg. It is shown that this method offers good selectivity in cases where UV detection fails to produce reliable results. PMID:25627971

  19. Topologically unique heterometallic Cu(II)/Li coordination polymers self-assembled from N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid biobuffer: versatile catalyst precursors for mild hydrocarboxylation of alkanes to carboxylic acids.

    PubMed

    Kirillova, Marina V; Kirillov, Alexander M; Martins, André N C; Graiff, Claudia; Tiripicchio, Antonio; Pombeiro, Armando J L

    2012-05-01

    The facile aqueous medium reactions of copper(II) nitrate with BES biobuffer [(HOCH(2)CH(2))(2)N(CH(2)CH(2)SO(3)H), hereinafter referred as H(3)bes] in the presence of various benzenecarboxylic acids [benzoic (Hba), 3-hydroxybenzoic (Hhba), and 3,5-dihydroxybenzoic (Hdhba) acid] and lithium hydroxide gave rise to the self-assembly generation of three new heterometallic Cu(II)/Li materials, [Li(H(2)O)(4)][Cu(4)(?(2)-Hbes)(4)(?(2)-ba)]·H(2)O (1) and [Cu(4)(?(3)-Hbes)(4)(L){Li(H(2)O)(2)}](n)·3nH(2)O {L = ?(2)-hba (2) and ?(2)-dhba (3)}. They were isolated as air-stable crystalline solids and fully characterized by infrared (IR) and UV-vis spectroscopy and electrospray ionization (ESI)-MS(±), elemental, thermal, and single-crystal X-ray diffraction analyses. The latter revealed that 1-3 have comparable packing patterns and unit cell parameters, being composed of similar [Cu(4)(?-Hbes)(4)(?-carboxylate)](-) cores and [Li(H(2)O)(4)](+) cations (in 1) or [?-Li(H(2)O)(2)](+) groups (in 2 and 3), which are arranged into discrete 0D aggregates in 1 or infinite 3D noninterpenetrating metal-organic networks in 2 and 3. The topological analysis of the coordination polymers 2 and 3 disclosed the trinodal 3,3,4-connected underlying nets with an unprecedented topology defined by the point symbol of (4.6.8)(4)(4(2).6)(2)(6(2).16(2).18(2)), further simplification of which resulted in the binodal 4,4-connected nets with the pts (PtS) topology. Apart from representing very rare examples of coordination compounds derived from H(3)bes, 1-3 feature solubility in water and were applied as efficient and versatile catalyst precursors for the mild (60 °C) single-pot hydrocarboxylation, by CO and H(2)O, of various gaseous, linear, and cyclic C(n) (n = 2-9) alkanes into the corresponding C(n+1) carboxylic acids, in H(2)O/MeCN medium under homogeneous conditions and in the presence of potassium peroxodisulfate. Total yields (based on alkane) of carboxylic acids up to 78% were achieved, which are remarkable in the field of alkane functionalization under mild conditions, especially for a C-C bond formation reaction in aqueous acid-solvent-free medium. PMID:22482365

  20. Mixed culture syngas fermentation and conversion of carboxylic acids into alcohols.

    PubMed

    Liu, Kan; Atiyeh, Hasan K; Stevenson, Bradley S; Tanner, Ralph S; Wilkins, Mark R; Huhnke, Raymond L

    2014-01-01

    Higher alcohols such as n-butanol and n-hexanol have higher energy density than ethanol, are more compatible with current fuel infrastructure, and can be upgraded to jet and diesel fuels. Several organisms are known to convert syngas to ethanol, but very few can produce higher alcohols alone. As a potential solution, mixed culture fermentation between the syngas fermenting Alkalibaculum bacchi strain CP15 and propionic acid producer Clostridium propionicum was studied. The monoculture of CP15 produced only ethanol from syngas without initial addition of organic acids to the fermentation medium. However, the mixed culture produced ethanol, n-propanol and n-butanol from syngas. The addition of propionic acid, butyric acid and hexanoic acid to the mixed culture resulted in a 50% higher conversion efficiency of these acids to their respective alcohols compared to CP15 monoculture. These findings illustrate the great potential of mixed culture syngas fermentation in production of higher alcohols. PMID:24315938

  1. Assembly of Acid-Functionalized Single-Walled Carbon Nanotubes at Oil/Water Interfaces

    NASA Astrophysics Data System (ADS)

    Feng, Tao; Hoagland, David; Russell, Thomas

    2014-03-01

    The segregation of water-soluble acid-functionalized single-walled carbon nanotubes (SWCNTs) at the oil/water interface was induced by dissolving low-molecular-weight amine-terminated polystyrene (PS-NH2) in the oil phase. Salt-bridge interactions between carboxylic acid groups of SWCNTs and amine groups of PS drove assembly of a mixed interfacial film, monitored by pendant drop tensiometry and laser scanning confocal microscopy. The influence of PS end-group functionality, PS and SWCNT concentrations, and degree of SWCNT acid modification on interfacial activity were assessed, and a sharp drop in interfacial tension was observed above a critical SWCNT concentration. Interfacial tensions were low enough to support stable oil/water emulsions. Further experiments, including potentiometric titrations and replacement of SWCNTs by other carboxyl-containing species, demonstrated that the interfacial tension drop reflects the loss of SWCNT charge as pH falls near/below the intrinsic carboxyl dissociation constant; species lacking multivalent carboxylic acid groups are inactive. The interfacial assemblies of SWCNTs appear neither ordered nor oriented. Research Advisor.

  2. Assembly of acid-functionalized single-walled carbon nanotubes at oil/water interfaces.

    PubMed

    Feng, Tao; Hoagland, David A; Russell, Thomas P

    2014-02-01

    The efficient segregation of water-soluble, acid-functionalized, single-walled carbon nanotubes (SWCNTs) at the oil/water interface was induced by dissolving low-molecular-weight amine-terminated polystyrene (PS-NH2) in the oil phase. Salt-bridge interactions between carboxylic acid groups of SWCNTs and amine groups of PS drove the assembly of SWCNTs at the interface, monitored by pendant drop tensiometry and laser scanning confocal microscopy. The impact of PS end-group functionality, PS and SWCNT concentrations, and the degree of SWCNT acid modification on the interfacial activity was assessed, and a sharp drop in interfacial tension was observed above a critical SWCNT concentration. Interfacial tensions were low enough to support stable oil/water emulsions. Further experiments, including potentiometric titrations and the replacement of SWCNTs by other carboxyl-containing species, demonstrated that the interfacial tension drop reflects the loss of SWCNT charge as the pH falls near/below the intrinsic carboxyl dissociation constant; species lacking multivalent carboxylic acid groups are inactive. The trapped SWCNTs appear to be neither ordered nor oriented. PMID:24443769

  3. In-situ spectroscopic investigations of the redox behavior of poly(indole-5-carboxylic-acid) modified electrodes in acidic aqueous solutions.

    PubMed

    Talbi, H; Billaud, D; Louarn, G; Pron, A

    2001-03-01

    The oxidation of electrochemically grown poly(indole-5-carboxylic-acid) (P5CO2H) and its spectroscopic properties have been studied by in-situ spectroelectrochemical techniques. The purpose of this paper is to characterize the different modifications on the P5CO2H backbone, induced by the electrochemical oxidation in aqueous acidic solution. We have identified, on the basis of Raman spectra, the vibrational modes associated with neutral and oxidized segments of polymer. It was shown that at least three chemically and optically different species (perhaps other products too) are produced in different potential regimes upon oxidation of this polymer. The results obtained also indicate that the molecular properties of this conducting polymer are better revealed by in-situ resonant spectra than by ex-situ infrared and Raman studies. PMID:11300553

  4. Formation of carboxamides by direct condensation of carboxylic acids and amines in alcohols using a new alcohol- and water-soluble condensing agent: DMT-MM

    Microsoft Academic Search

    Munetaka Kunishima; Chiho Kawachi; Kazuhito Hioki; Keiji Terao; Shohei Tani

    2001-01-01

    Selective formation of carboxamides in an alcohol or water by an exceptionally convenient one-step procedure in which a condensing agent is simply added to a mixture of acids and amines has been achieved successfully by using a new condensing agent, 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM). Activation of carboxylic acids by DMT-MM in the presence of amines and subsequent aminolysis of the resulting

  5. pH responsive properties of non-fouling mixed-charge polymer brushes based on quaternary amine and carboxylic acid monomers

    Microsoft Academic Search

    Luo Mi; Matthew T. Bernards; Gang Cheng; Qiuming Yu; Shaoyi Jiang

    2010-01-01

    In this work, we report a tunable mixed-charge copolymer surface containing positively charged quaternary amine monomers ([2-(Acryloyloxy)ethyl] trimethyl ammonium chloride, TMA) and negatively-charged carboxylic acid monomers (2-carboxy ethyl acrylate, CAA). The non-fouling properties of this copolymer coating depend on environmental pH. The surface has charge neutrality under neutral and basic conditions, and is positively charged under acidic conditions due to

  6. Long-chain carboxylic acids in pyrolysates of Green River kerogen

    NASA Technical Reports Server (NTRS)

    Kawamura, K.; Tannenbaum, E.; Huizinga, B. J.; Kaplan, I. R.

    1986-01-01

    Long-chain fatty acids (C10-C32), as well as C14-C21 isoprenoid acids (except for C18), have been identified in anhydrous and hydrous pyrolyses products of Green River kerogen (200-400 degrees C, 2-1000 hr). These kerogen-released fatty acids are characterized by a strong even/odd predominance (CPI: 4.8-10.2) with a maximum at C16 followed by lesser amounts of C18 and C22 acids. This distribution is different from that of unbound and bound geolipids extracted from Green River shale. The unbound fatty acids show a weak even/odd predominance (CPI: 1.64) with a maximum at C14, and bound fatty acids display an even/odd predominance (CPI: 2.8) with maxima at C18 and C30. These results suggest that fatty acids were incorporated into kerogen during sedimentation and early diagenesis and were protected from microbial and chemical changes over geological periods of time. Total quantities of fatty acids produced during heating of the kerogen ranged from 0.71 to 3.2 mg/g kerogen. Highest concentrations were obtained when kerogen was heated with water for 100 hr at 300 degrees C. Generally, their amounts did not decrease under hydrous conditions with increase in temperature or heating time, suggesting that significant decarboxylation did not occur under the pyrolysis conditions used, although hydrocarbons were extensively generated.

  7. Solvent extraction of nickel and cobalt with synergistic systems consisting of carboxylic acid and aliphatic hydroxyoxime

    Microsoft Academic Search

    Chu Yong Cheng

    2006-01-01

    Metal extraction pH isotherms and extraction and stripping kinetics have been determined with Versatic 10 acid and LIX® 63 and modifier TBP in an attempt to develop synergistic SX systems for the separation, purification and recovery of nickel and cobalt from leach solutions.The combination of LIX® 63 with Versatic 10 acid resulted in significant synergistic shifts for nickel, cobalt, copper,

  8. Harvest maturity related changes in the cold-induced activation of 1-aminocyclopropane-1-carboxylic acid metabolism in Granny Smith apples \\/ Efecto del estado de madurez sobre la activación por frío del metabolismo del ácido 1-aminociclopropano-1-carboxílico en manzanas Granny Smith

    Microsoft Academic Search

    C. Larrigaudiere; I. Recasens; J. Graell; M. Vendrell

    1999-01-01

    Changes in 1-aminocyclopropane-1-carboxylic acid metabolism in apples (Malus domestica Borkh cv Granny Smith) were studied in relation to cold storage. Emphasis was given to the differential re sponsiveness of fruits to cold treatment as a function of stage of maturity at harvest. Fruits were held at 1 or 20 °C for 30 days, respectively, or exposed to 1 °C for

  9. Rapid degradation of Pseudomonas fluorescens 1-aminocyclopropane-1-carboxylic acid deaminase proteins expressed in transgenic Arabidopsis.

    PubMed

    Kim, Kangmin; Park, Sung-Hee; Chae, Jong-Chan; Soh, Byoung Yul; Lee, Kui-Jae

    2014-06-01

    1-Aminocyclopropane-1-carboxylate (ACC) deaminase is commonly produced by plant growth-promoting rhizobacteria (PGPR) and has been suggested to facilitate the growth and stress tolerance of hosts via a reduction in levels of ethylene. However, the regulatory mechanism of ACC deaminase (AcdS) protein within host plant cells is largely unknown. Here, we demonstrated beneficial effects and post-translational modification of PGPR-originated AcdS proteins in plants. Compared with the wild-type, transgenic Arabidopsis expressing the Pseudomonas fluorescens acdS (PfacdS) gene displayed increased root elongation and reduced sensitivity to 10 ?M exogenous ACC, an ethylene precursor. Arabidopsis expressing PfacdS also showed increased tolerance to high salinity (150 mM NaCl). PfAcdS proteins accumulated in transgenic Arabidopsis were rapidly degraded, which was potentially mediated by the 26S proteasome pathway. The degradation of PfAcdS was alleviated in the presence of exogenous ACC. In conclusion, our data suggest that the plant growth-promoting effects of bacterial AcdS proteins are potentially modulated via protein turnover inside the host plant cells. Such post-translational modification plays a physiological role in the mutualistic interactions between microorganisms and plants in the rhizospheric and/or endospheric niche. PMID:24801274

  10. Ethylene Promotes the Capability To Malonylate 1-Aminocyclopropane-1-carboxylic Acid and d-Amino Acids in Preclimacteric Tomato Fruits 1

    PubMed Central

    Liu, Yu; Su, Ling-Yuan; Yang, Shang Fa

    1985-01-01

    When whole unripe green tomato fruits (Lycopersicon esculentum Mill, cv T3) were treated with ethylene (10 microliters per liter) for 18 hours, the fruit's ability to convert 1-aminocyclopropane-1-carboxylic acid (ACC) to N-malonyl-ACC (MACC) increased markedly and such an effect was also observed in fruits of mutant nor, which cannot ripen normally. The promotion of the capability to malonylate ACC by ethylene increased with the increasing ethylene concentration from 0.1 to 100 microliters per liter and with increasing duration of ethylene treatment up to 8 hours; a longer duration of ethylene treatment did not further increase the malonylation capability. When ethylene was withdrawn, the promotion disappeared within 72 hours. Norbornadiene, a competitive inhibitor of ethylene action, effectively eliminated the promotive effect of ethylene. Ethylene treatment also promoted the fruits' capability to conjugate d-amino acids and ?-amino-isobutyric acid. Since the increase in the tissue's capability to malonylate ACC was accompanied by an increase in the extractable activity of ACC and d-amino acid malonyltransferase, ethylene is thought to promote the development of ACC/d-amino acid malonyltransferase in unripe tomato fruits. PMID:16664157

  11. Scalable and chromatography-free synthesis of 2-(2-formylalkyl)arenecarboxylic acid derivatives through the supramolecularly controlled hydroformylation of vinylarene-2-carboxylic acids.

    PubMed

    Dydio, Pawe?; Reek, Joost N H

    2014-05-01

    This protocol describes how to prepare 2-(2-formylalkyl)-arenecarboxylic acid derivatives, common building blocks for the synthesis of various valuable chemicals (e.g., anti-obesity and Alzheimer's disease treatment pharmaceuticals), by using the fully regioselective hydroformylation of vinyl arene derivatives. This catalytic reaction proceeds cleanly with 100% regioselectivity and chemoselectivity. The procedure is reliably scalable and can be efficiently conducted on a multigram scale. The analytically pure product is easily isolated with a nearly quantitative yield by using a simple acid-base extraction workup and avoids any tedious chromatography. This protocol details the synthesis of a bisphosphite ligand (L1) that is a pivotal element of the catalytic system used, Rh(acac)(CO)2 with ligand L1, starting from commercial building blocks. The protocol also describes a general procedure for the preparative hydroformylation of vinylarene-2-carboxylic acid derivatives to 2-formylalkylarene products, providing a representative example for the hydroformylation of 2-vinylbenzoic acid (1a) to 2-(3-oxopropane)-benzoic acid (2a). The synthesis of L1 (six chemical reactions) uses 2-nitrophenylhydrazine, 4-benzyloxybenzoylchloride and (S)-binol, and takes 5-7 working days. The actual hydroformylation reaction of each vinyl arene derivative takes ?4 h of active effort over a period of 1-3 d. PMID:24762785

  12. Molecular cloning of cDNA encoding a drosophila ryanodine receptor and functional studies of the carboxyl-terminal calcium release channel.

    PubMed Central

    Xu, X; Bhat, M B; Nishi, M; Takeshima, H; Ma, J

    2000-01-01

    Ryanodine is a plant alkaloid that was originally used as an insecticide. To study the function and regulation of the ryanodine receptor (RyR) from insect cells, we have cloned the entire cDNA sequence of RyR from the fruit fly Drosophila melanogaster. The primary sequence of the Drosophila RyR contains 5134 amino acids, which shares approximately 45% identity with RyRs from mammalian cells, with a large cytoplasmic domain at the amino-terminal end and a small transmembrane domain at the carboxyl-terminal end. To characterize the Ca(2+) release channel activity of the cloned Drosophila RyR, we expressed both full-length and a deletion mutant of Drosophila RyR lacking amino acids 277-3650 (Drosophila RyR-C) in Chinese hamster ovary cells. For subcellular localization of the expressed Drosophila RyR and Drosophila RyR-C proteins, green fluorescent protein (GFP)-Drosophila RyR and GFP-Drosophila RyR-C fusion constructs were generated. Confocal microscopic imaging identified GFP-Drosophila RyR and GFP-Drosophila RyR-C on the endoplasmic reticulum membranes of transfected cells. Upon reconstitution into the lipid bilayer membrane, Drosophila RyR-C formed a large conductance cation-selective channel, which was sensitive to modulation by ryanodine. Opening of the Drosophila RyR-C channel required the presence of microM concentration of Ca(2+) in the cytosolic solution, but the channel was insensitive to inhibition by Ca(2+) at concentrations as high as 20 mM. Our data are consistent with our previous observation with the mammalian RyR that the conduction pore of the calcium release channel resides within the carboxyl-terminal end of the protein and further demonstrate that structural and functional features are essentially shared by mammalian and insect RyRs. PMID:10692315

  13. Lysine Carboxylation in Proteins: OXA-10 -Lactamase Jason B. Cross,1

    E-print Network

    Schlegel, H. Bernhard

    -base chemistry, in expan- sion of function beyond those of the 20 standard amino acids. In this study, the ONIOM; ONIOM QM/MM method; density func- tional calculations INTRODUCTION Carboxylated lysine residues have

  14. Calculated Third Order Rate Constants for Interpreting the Mechanisms of Hydrolyses of Chloroformates, Carboxylic Acid Halides, Sulfonyl Chlorides and Phosphorochloridates

    PubMed Central

    Bentley, T. William

    2015-01-01

    Hydrolyses of acid derivatives (e.g., carboxylic acid chlorides and fluorides, fluoro- and chloroformates, sulfonyl chlorides, phosphorochloridates, anhydrides) exhibit pseudo-first order kinetics. Reaction mechanisms vary from those involving a cationic intermediate (SN1) to concerted SN2 processes, and further to third order reactions, in which one solvent molecule acts as the attacking nucleophile and a second molecule acts as a general base catalyst. A unified framework is discussed, in which there are two reaction channels—an SN1-SN2 spectrum and an SN2-SN3 spectrum. Third order rate constants (k3) are calculated for solvolytic reactions in a wide range of compositions of acetone-water mixtures, and are shown to be either approximately constant or correlated with the Grunwald-Winstein Y parameter. These data and kinetic solvent isotope effects, provide the experimental evidence for the SN2-SN3 spectrum (e.g., for chloro- and fluoroformates, chloroacetyl chloride, p-nitrobenzoyl p-toluenesulfonate, sulfonyl chlorides). Deviations from linearity lead to U- or V-shaped plots, which assist in the identification of the point at which the reaction channel changes from SN2-SN3 to SN1-SN2 (e.g., for benzoyl chloride). PMID:26006228

  15. A kinetic study of the reactions of diphenyldiazomethane with some aliphatic carboxylic acids

    E-print Network

    Hoefelmeyer, Albert Bernard

    1954-01-01

    an esterification pro? cedure. The methyl ester of each acid was formed and fractionated in the Todd column to obtain pure ester. The purified ester was then saponified and the pure acid obtained by hydrolysis and subsequent distillation from the saponification...mentioned Todd column. The methyl valerate was saponified, using a 10$ excess of 10$ sodium hydroxide solution. The mixture was refluxed for two hours after the ester layer disappeared. The product was then distilled until 100? C. was reached and held...

  16. Enantioselective Recognition of Chiral Carboxylic Acids by a ?-Amino Acid and 1,10-Phenanthroline Based Chiral Fluorescent Sensor

    PubMed Central

    Zhang, Yonghong; Hu, Fangzhi; Wang, Bin; Zhang, Xiaomei; Liu, Chenjiang

    2015-01-01

    A novel chiral 1,10-phenanthroline-based fluorescent sensor was designed and synthesized from optical active ?-amino acids. It used 1,10-phenanthroline moiety as a fluorescent signaling site and binding site, with optically active ?-amino acids as a chiral barrier site. Notably, the optically active ?-amino acids were obtained by a Lewis base catalyzed hydrosilylation of ?-enamino esters according to our former work. The chiral sensor has been used to conduct the enantioselective recognition of chiral mono and dicarboxylic acids derivatives. Using this fluorescent sensor, a moderate “turn-off” fluorescence-diminishment response towards enantiomer of tartaric acids, and proline was observed. It found that l-enantiomers quench the chiral fluorescence sensor more efficiently than d-enantiomers due to the absolute configuration of the ?-amino acid. PMID:25954953

  17. Molecular structure, vibrational spectra, natural bond orbital and thermodynamic analysis of 3,6-dichloro-4-methylpyridazine and 3,6-dichloropyridazine-4-carboxylic acid by dft approach

    NASA Astrophysics Data System (ADS)

    Prabavathi, N.; Senthil Nayaki, N.; Venkatram Reddy, B.

    2015-02-01

    Vibrational spectral analysis of the molecules 3,6-dichloro-4-methylpyridazine (DMP) and 3,6-dichloropyridazine-4-carboxylic acid (DPC) was carried out using FT-IR and FT-Raman spectroscopic techniques. The molecular structure and vibrational spectra of DMP and DPC were obtained by the density functional theory (DFT) method, using B3LYP functional, with 6-311++G(d,p) basis set. A detailed interpretation of the Infrared and Raman spectra of the two molecules were reported based on potential energy distribution (PED). The theoretically predicted FTIR and FT-Raman spectra of the titled molecules have been simulated and were compared with the experimental spectra. Determination of electric dipole moment (?) and hyperpolarizability ?0 helps to study the non-linear optical (NLO) behavior of DMP and DPC. Stability of the molecules arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. 13C and 1H NMR spectra were recorded and 13C and 1H NMR chemical shifts of the molecules were calculated using the gauge independent atomic orbital (GIAO) method. UV-visible spectrum of the compounds was also recorded in the region 200-1100 nm and electronic properties, HOMO (Highest Occupied Molecular Orbitals) and LUMO (Lowest Unoccupied Molecular Orbitals) energies were measured by time-dependent TD-DFT approach. Charge density distribution and site of chemical reactivity of the molecule have been studied by mapping electron density isosurface with molecular electrostatic potential (MESP).

  18. Dual SO{sub 2}-NO{sub x} concentration reduction by calcium salts of carboxylic acids

    SciTech Connect

    Steciak, J.; Levendis, Y.A.; Wise, D.L. [Northeastern Univ., Boston, MA (United States); Simons, G.A. [Simons Research Association, Lynnfield, MA (United States)

    1995-08-01

    This research continues the investigation of agents that are capable of simultaneously removing SO{sub 2} and Mo{sub x} from the effluent of coal-fired power plants. The simultaneous removal of SO{sub 2} and NO{sub x} by calcium salts of carboxylic acids was evaluated in a laboratory-scale furnace in atmospheres containing 2,000 ppm SO{sub 2}, 1,000 ppm NO, 3% O{sub 2}, and 12% CO{sub 2} at gas temperatures between 550 and 1,250 C (825 and 1,425 K) with a residence times of 4 s in an isothermal zone. The salts studied included calcium formate (CF, Ca(COOH){sub 2}), calcium acetate (CA, Ca(CH{sub 2}COOH){sub 2}), calcium propionate CP, (Ca(CH{sub 2}CH{sub 2}COOH){sub 2}) and calcium benzoate (CB, Ca(C{sub 6}H{sub 4}COOH){sub 2}). Maximum reductions in SO{sub 2} concentration due to the formation of CaSO{sub 4} were recorded as follows: 60% for CP, 55% for CR, 35% for CA, and 18% for CB at gas temperatures in the neighborhood of 950 C and at a Ca/s molar ratio near 2.8. With the organic portion of the injected salts acting as secondary fuel for NO{sub x} control, maximum NO{sub x} concentration reductions were 88% for CP, 65% for CB, 22% for CA and less than 10% for CF at gas temperatures near 950 C at bulk equivalence ratios that varied between 0.5 for CF and 2.1 for CB. A recently constructed, narrower furnace increased the gas flow velocities and the particle dispersion in the gas. Therein, at residence times as low as 1 s, CP achieved simultaneous SO{sub 2} and NO{sub x} removal of over 80% at gas temperatures {ge}950 C. the addition of an oxidizing zone following the carboxylic acid sorbent injection zone affected the overall SO{sub 2}-NO{sub x} removal according to the stoichiometry of the sorbent injection zone. When this zone was: (1) fuel-lean, the overall SO{sub 2} removal improved; (2) stoichiometric, the overall SO{sub 2} removal was not affected; and (3) significantly fuel-rich , the overall SO{sub 2} removal worsened.

  19. Interaction between carboxyl-functionalized carbon black nanoparticles and porous media

    NASA Astrophysics Data System (ADS)

    Kim, Song-Bae; Kang, Jin-Kyu; Yi, In-Geol

    2015-04-01

    Carbon nanomaterials, such as carbon nanotubes, fullerene, and graphene, have received considerable attention due to their unique physical and chemical characteristics, leading to mass production and widespread application in industrial, commercial, and environmental fields. During their life cycle from production to disposal, however, carbon nanomaterials are inevitably released into water and soil environments, which have resulted in concern about their health and environmental impacts. Carbon black is a nano-sized amorphous carbon powder that typically contains 90-99% elemental carbon. It can be produced from incomplete combustion of hydrocarbons in petroleum and coal. Carbon black is widely used in chemical and industrial products or applications such as ink pigments, coating plastics, the rubber industry, and composite reinforcements. Even though carbon black is strongly hydrophobic and tends to aggregate in water, it can be dispersed in aqueous media through surface functionalization or surfactant use. The aim of this study was therefore to investigate the transport behavior of carboxyl-functionalized carbon black nanoparticles (CBNPs) in porous media. Column experiments were performed for potassium chloride (KCl), a conservative tracer, and CBNPs under saturated flow conditions. Column experiments was conducted in duplicate using quartz sand, iron oxide-coated sand (IOCS), and aluminum oxide-coated sand (AOCS) to examine the effect of metal (Fe, Al) oxide presence on the transport of CBNPs. Breakthrough curves (BTCs) of CBNPs and chloride were obtained by monitoring effluent, and then mass recovery was quantified from these curves. Additionally, interaction energy profiles for CBNP-porous media were calculated using DLVO theory for sphere-plate geometry. The BTCs of chloride had relative peak concentrations ranging from 0.895 to 0.990. Transport parameters (pore-water velocity v, hydrodynamic dispersion coefficient D) obtained by the model fit from the tracer BTCs were 0.274±0.007 cm min-1 and 0.102±0.025 cm2 min-1, respectively. Mass recoveries of chloride were in the range of 94.7 to 101.9%, indicating that chloride behaved as a conservative tracer and that the column experiments were successful. The BTCs of CBNPs had different relative peak concentrations depending on the porous media used in the experiments. In quartz sand, the relative peak concentration was 0.768±0.005. The mass recovery of CBNPs in quartz sand was 83.1±2.7%, whereas no breakthrough of CBNPs (mass recovery = 0 %) was observed in IOCS or AOCS at the same flow rate, indicating that all CBNPs were retained in the IOCS and AOCS columns under the experimental conditions. These results indicate that metal (Fe, Al) oxides can play a significant role in the attachment of CBNPs to porous media. For the given solution conditions, both CBNPs and quartz sand were negatively charged with zeta potentials of -31.8±0.1 and -39.0±0.6 mV, respectively. Therefore, the electrostatic interactions between CBNPs and quartz sand were repulsive. Meanwhile, both IOCS and ACOS were positively charged with zeta potentials of 10.1±1.3 and 39.9±1.9 mV, respectively, such that the interaction between CBNPs and metal oxide-coated sands was electrostatically attractive, resulting in enhancement of CBNP attachment to the coated sands. Interaction energy profiles for CBNP-porous media were calculated using DLVO theory for sphere-plate geometry. Interaction energy profiles demonstrated that the interaction energy for CBNP-quartz sand was repulsive with a primary maximum (energy barrier) of 63.2 KBT, whereas the interaction energies for CBNP-IOCS and CBNP-AOCS were attractive with no energy barriers. Acknowledgement This research was supported by the National Institute of Environmental Research, Korea Ministry of Environment, in 2014.

  20. (CF3CO)2O/CF3SO3H-mediated synthesis of 1,3-diketones from carboxylic acids and aromatic ketones

    PubMed Central

    Kim, JungKeun; Shokova, Elvira; Tafeenko, Victor

    2014-01-01

    Summary A very simple and convenient reaction for 1,3-diketone preparation from carboxylic acids and aromatic ketones in TFAA/TfOH system is described. When the ?-phenylpropionic acids were used as starting materials, they initially gave 1-indanones and then underwent further acylation with the formation of 2-(?-phenylpropionyl)-1-indanones as the main reaction products. In addition, the application of the proposed protocol allowed for the synthesis of selected polysubstituted pyrazoles in a one-pot procedure directly from acids and ketones. PMID:25298794

  1. Five 3D supramolecular frameworks assembled from classical directional hydrogen-bonds and Csbnd H⋯O associations between carboxylic acids and bis-imidazoles

    NASA Astrophysics Data System (ADS)

    Jin, Shouwen; Guo, Ming; Wang, Daqi; Wei, Shuaishuai; Zhou, Yong; Zhou, Yingping; Cao, Xinchao; Yu, Zeyun

    2012-08-01

    Five crystalline organic acid-base adducts derived from bis(N-imidazolyl) and carboxylic acid (p-nitrobenzoic acid, m-nitrobenzoic acid, 3,5-dihydroxybenzoic acid, sebacic acid, and fumaric acid) were prepared and characterized by X-ray diffraction analysis, IR, mp, and elemental analysis. Of the five compounds three are organic salts (1, 3, and 5) and the other two (2, and 4) are cocrystals. In salts 1, and 5, the L1 are diprotonated, while in 3 the L1 is only monoprotonated. All supramolecular architectures of the adducts 1-5 involve extensive intermolecular Nsbnd H⋯O, Osbnd H⋯O, and Csbnd H⋯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 complexes displayed 3D framework structure for the synergistic effect of the various noncovalent interactions. The results presented herein indicate that the strength and directionality of the N+sbnd H⋯O-, Osbnd H⋯O, and Osbnd H⋯N hydrogen bonds between carboxylic acids and ditopic imidazoles are sufficient to bring about the formation of binary cocrystals or organic salts.

  2. The carboxyl-terminal domain of the p53 protein regulates sequence-specific DNA binding through its nonspecific nucleic acid-binding activity.

    PubMed Central

    Bayle, J H; Elenbaas, B; Levine, A J

    1995-01-01

    The murine p53 protein contains two nucleic acid-binding sites, a sequence-specific DNA-binding region localized between amino acid residues 102-290 and a nucleic acid-binding site without sequence specificity that has been localized to residues 364-390. Alternative splicing of mRNA generates two forms of this p53 protein. The normal, or majority, splice form (NSp53) retains its carboxyl-terminal sequence-nonspecific nucleic acid-binding site, which can negatively regulate the sequence-specific DNA-binding site. The alternative splice form of p53 (ASp53) replaces amino acid residues 364-390 with 17 different amino acids. This protein fails to bind nucleic acids nonspecifically and is constitutive for sequence-specific DNA binding. Thus, the binding of nucleic acids at the carboxyl terminus regulates sequence-specific DNA binding by p53. The implications of these findings for the activation of p53 transcriptional activity following DNA damage are discussed. Images Fig. 2 Fig. 3 Fig. 4 PMID:7777576

  3. Anaerobic fermentation of rice straw and chicken manure to carboxylic acids 

    E-print Network

    Agbogbo, Frank Kwesi

    2007-04-25

    by methanogens to produce methane. Because osmotic stress is the ultimate barrier to achieving high acid concentrations, inocula from marine environments have salt- resistant microorganisms that strengthen the tolerance to high salt concentrations (Li, 2002...). The sediment was collected from 0.5-m-deep holes and placed into bottles filled with deoxygenated media. 2.4 Inhibitor Iodoform (CHI3) solution containing 20 g CHI3/L ethanol was used as a methanogen inhibitor in this experiment. Iodoform was added...

  4. Different geometrical arrangements in carboxylate coordination polymers of flexible dicarboxylic acid

    SciTech Connect

    Deka, Himangshu; Sarma, Rupam [Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781 039, Assam (India); Kumari, Satchi; Khare, Alika [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781 039, Assam (India); Baruah, Jubaraj B., E-mail: juba@iitg.ernet.in [Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781 039, Assam (India)

    2011-07-15

    Dicarboxylate coordination polymers (1-5) of Mn(II), Ni(II), Cu(II), Zn(II) and Cd(II), respectively, derived from (7-carboxymethoxy-naphthalen-2-yloxy)-acetic acid (L{sub 1}H{sub 2}) are synthesized and characterized. Depending on the coordination sites around the metal centers and coordination mode of the ligand, dimensionality of these polymers varies. The dicarboxylates adopt three spatial orientations: in-plane linear coordination, out-of-plane cis coordination and out-of-plane trans coordination mode. Both the cis and trans out-of-plane coordination modes are found to exist only if the ancillary ligand pyridine is coordinated to the metal ion. When the aquoligand coordinates the in-plane linear coordination mode of L{sub 1} predominates. The coordination polymers 4 and 5 show photoluminescence in solution. The dicarboxylate of (5-carboxymethoxy-naphthalen-1-yloxy)-acetic acid (L{sub 2}H{sub 2}) does not form coordination polymer under ambient conditions, but prefers to remain as uncoordinated anion providing hydrophobic confinement to hexa-aquometal(II) cation. Compound 3 crystallizes in P2{sub 1} space group and it shows broadband ultra-violet fluorescence centered at 352.9 nm on focusing 632.8 nm He:Ne laser. - Graphical abstract: Different geometrical arrangements in coordination polymers derived from (7-carboxymethoxy-naphthalen-2-yloxy)-acetic acid of metal ions Mn(II), Ni(II), Cu(II), Zn(II) and Cd(II) are presented. The (5-carboxymethoxy-naphthalen-1-yloxy)-acetic acid led to hexa-aquo cadmium(II) dicarboxylate. Highlights: > Structural and spectroscopic characterizations of five dicarboxylate coordination polymers of (7-carboxymethoxy-naphthalen-2-yloxy)-acetic acid with different metal ions are presented. > Different geometrical arrangements of coordination polymers stabilized in solid state are described. > Photoluminescence properties of the polymers are shown. > NLO property of a copper coordination polymer is described.

  5. Microsomal aldehyde dehydrogenase is localized to the endoplasmic reticulum via its carboxyl-terminal 35 amino acids

    PubMed Central

    1994-01-01

    Rat microsomal aldehyde dehydrogenase (msALDH) has no amino-terminal signal sequence, but instead it has a characteristic hydrophobic domain at the carboxyl terminus (Miyauchi, K., R. Masaki, S. Taketani, A. Yamamoto, A. Akayama, and Y. Tashiro. 1991. J. Biol. Chem. 266:19536- 19542). This membrane-bound enzyme is a useful model protein for studying posttranslational localization to its final destination. When expressed from cDNA in COS-1 cells, wild-type msALDH is localized exclusively in the well-developed ER. The removal of the hydrophobic domain results in the cytosolic localization of truncated proteins, thus suggesting that the portion is responsible for membrane anchoring. The last 35 amino acids of msALDH, including the hydrophobic domain, are sufficient for targeting of E. coli beta-galactosidase to the ER membrane. Further studies using chloramphenicol acetyltransferase fusion proteins suggest that two hydrophilic sequences on either side of the hydrophobic domain play an important role in ER targeting. PMID:8089174

  6. Inhibitory and bactericidal activities of amifloxacin, a new quinolone carboxylic acid, compared with those of seven other antimicrobial agents.

    PubMed

    Baltch, A L; Sutphen, N T; Smith, R P; Conley, P E

    1984-01-01

    The activity of amifloxacin, a new quinolone carboxylic acid compound, against 147 strains of microorganisms was studied and was compared with the activities of cinoxacin, trimethoprim, amikacin, and four beta-lactam antimicrobials. The minimal concentration at which 90% of strains were inhibited by amifloxacin was lowest for Escherichia coli and Klebsiella sp (less than or equal to 0.125 microgram/ml), followed by Proteus sp (less than or equal to 0.25 microgram/ml), Enterobacter sp and Citrobacter sp (less than or equal to 0.5 microgram/ml), Providencia sp (less than or equal to 2 micrograms/ml), and Pseudomonas aeruginosa, Serratia sp, and Acinetobacter calcoaceticus var anitratus (less than or equal to 8 micrograms/ml). When compared with the ranges of activity of seven reference antimicrobials, the range of amifloxacin activity was lowest for P aeruginosa, Citrobacter sp, Proteus sp, and A calcoaceticus var anitratus and similar to aztreonam's activity against Enterobacter sp. For amikacin-resistant P aeruginosa, the minimal inhibitory concentrations (MICs) of amifloxacin ranged from 1 to 16 micrograms/ml. The MICs and minimal bactericidal concentrations (MBCs) of amifloxacin were similar. For all strains tested, microbial susceptibilities to amifloxacin were greater than those to currently available oral antimicrobial drugs, such as cinoxacin and trimethoprim. PMID:6440708

  7. Molecular structures and ab initio molecular orbital calculations of the optically active derivatives of 1-aminocyclopropane-1-carboxylic acid

    NASA Astrophysics Data System (ADS)

    Džoli?, Zoran; Cetina, Mario; Kova?ek, Damir; Hergold-Brundi?, Antonija; Mrvoš-Sermek, Draginja; Nagl, Ante; Slade, Neda; Paveli?, Krešimir; Balzarini, Jan; De Clercq, Erik; Zerbe, Oliver; Folkers, Gerd; Scapozza, Leonardo; Mintas, Mladen

    2003-07-01

    The novel optically active derivatives of 2,2'-disubstituted-1-aminocyclopropane-1-carboxylic acid (-)- 2 and (+)- 3 were synthesised from the spiro-azlactone (+)- 1. Oxidation of the diol moiety of (+)- 3 gave by ring enlargement the racemic mixture of 2,3-dihydrofuran derivative (±)- 6. This conversion is explained by stepwise rearrangement of the initially formed tetrasubstituted cyclopropanecarbaldehyde 4 through zwitterionic's reactive intermediate 5. The formation of (±)- 6 is preferred energetically as established by ab initio calculations of the ground states and possible intermediates for that rearrangement. The crystal structure and absolute configuration of the compounds (+)- 1, (-)- 2, (+)- 3 and (-)- 7 were determined by single-crystal X-ray diffraction method. All four compounds possess Z-configuration of the cyclopropane ring. The dioxolane ring in the structures (+)- 1 and (-)- 2 adopts half-chair conformation, while the cyclopropane ring and geminally substituted groups in the structures (-)- 2, (+)- 3 and (-)- 7 possess the anticlinal conformation. The molecules of the compound (+)- 1 are connected by very weak intermolecular hydrogen bond of C-H⋯O type. In the compounds (-)- 2, (+)- 3 and (-)- 7inter- and intramolecular hydrogen bonds of N-H⋯O type were observed. The spiro-compound (+)- 1 exhibited a more pronounced inhibitory activity against the proliferation of murine leukemia and human T-lymphocytes cells than other type of tumor cell lines and normal human fibroblast cells.

  8. Structure of the PLP Degradative Enzyme 2-Methyl-3-hydroxypyridine-5-carboxylic Acid Oxygenase from Mesorhizobium loti MAFF303099 and Its Mechanistic Implications

    SciTech Connect

    McCulloch, Kathryn M.; Mukherjee, Tathagata; Begley, Tadhg P.; Ealick, Steven E.; Cornell

    2009-06-12

    A vitamin B{sub 6} degradative pathway has recently been identified and characterized in Mesorhizobium loti MAFF303099. One of the enzymes on this pathway, 2-methyl-3-hydroxypyridine-5-carboxylic acid oxygenase (MHPCO), is a flavin-dependent enzyme and catalyzes the oxidative ring-opening of 2-methyl-3-hydroxypyridine-5-carboxylic acid to form E-2-(acetamino-methylene)succinate. The gene for this enzyme has been cloned, and the corresponding protein has been overexpressed in Escherichia coli and purified. The crystal structure of MHPCO has been solved to 2.1 {angstrom} using SAD phasing with and without the substrate MHPC bound. These crystal structures provide insight into the reaction mechanism and suggest roles for active site residues in the catalysis of a novel oxidative ring-opening reaction.

  9. Light- and temperature-entrained circadian regulation of activity and mRNA accumulation of 1-aminocyclopropane-1-carboxylic acid oxidase in Stellaria longipes.

    PubMed

    Kathiresan, A; Reid, D M; Chinnappa, C C

    1996-01-01

    Stem and leaf tissues of Stellaria longipes Goldie (prairie ecotype) exhibit circadian rhythmicity in the activity and mRNA abundance for 1-aminocyclopropane-1-carboxylic acid oxidase (EC 1.4.3). The steady-state mRNA levels and enzymatic activity levels fluctuated with a period of approximately 24 h and reached their maxima by the middle of the light phase and minima by the middle of the dark phase. The oscillations showed damping under constant light, constant dark and constant temperature conditions, indicating that the rhythm is entrained by an external signal. The results indicate that light/dark cycles have greater entraining effects than temperature cycles. A 15-min red light pulse, but not a blue light pulse, could reset rhythm in continuous darkness, suggesting the possible role of a red-light signal transduction pathway in the circadian regulation of 1-aminocyclopropane-1-carboxylic acid oxidase. PMID:8771799

  10. Calix[n]arene carboxylic acid derivatives as regulators of enzymatic reactions: enhanced enantioselectivity in lipase-catalyzed hydrolysis of (R/S)-naproxen methyl ester.

    PubMed

    Akoz, Enise; Akbulut, Osman Y; Yilmaz, Mustafa

    2014-01-01

    Candida rugosa lipase was immobilized with a sol-gel encapsulation procedure in the presence and absence of a calix[n]arene carboxylic acid derivative grafted onto magnetic nanoparticles or in the presence of the calix[n]arene carboxylic acid derivative with Fe3O4 magnetic nanoparticles as an additive. Through the enantioselective hydrolysis of racemic naproxen methyl ester and the hydrolysis of p-nitrophenylpalmitate, the relative enzyme activity was evaluated and tested. These results show that the encapsulated lipase without supports has lower conversion and enantioselectivity compared to the Calix[n]COOH-based encapsulated lipase. It has also been observed that the Calix[4]COOH-based encapsulated lipase has excellent enantioselectivity (enantiomeric ratio (E)?> 400) as compared to encapsulated-free lipase enantioselectivity (E = 137), and it also has an enantiomeric excess value of ~98 % for S-naproxen. PMID:24092454

  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 ?g/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. Influence of Surface Modification with Carboxylic Acids on Performance of Polymer\\/Titania Photovoltaic Devices

    Microsoft Academic Search

    Hongwei Geng; Qiyun Qu; Chong Chen; Huan Wu; Mingtai Wang

    2010-01-01

    Polymer\\/titania nanoparticle hybrid bulk heterojunction photovoltaic devices were fabricated, and the influences of nanoparticle\\u000a content and surface modifiers on the photophysical and photovoltaic properties were investigated by photoluminescence measurements,\\u000a current–voltage characterization, and intensity-modulated photovoltage spectroscopy. The results revealed that dodecanoic-acid-modified\\u000a titania yields the best dispersibility in organic solvent and the highest device performance, and that the open-circuit voltage\\u000a and electron

  13. Different geometrical arrangements in carboxylate coordination polymers of flexible dicarboxylic acid

    Microsoft Academic Search

    Himangshu Deka; Rupam Sarma; Satchi Kumari; Alika Khare; Jubaraj B. Baruah

    2011-01-01

    Dicarboxylate coordination polymers (1–5) of Mn(II), Ni(II), Cu(II), Zn(II) and Cd(II), respectively, derived from (7-carboxymethoxy-naphthalen-2-yloxy)-acetic acid (L1H2) are synthesized and characterized. Depending on the coordination sites around the metal centers and coordination mode of the ligand, dimensionality of these polymers varies. The dicarboxylates adopt three spatial orientations: in-plane linear coordination, out-of-plane cis coordination and out-of-plane trans coordination mode. Both the

  14. Accumulation of the Antibiotic Phenazine-1-Carboxylic Acid in the Rhizosphere of Dryland Cereals

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural antibiotics are thought to function in the defense, fitness, competitiveness, biocontrol activity, communication and gene regulation of microorganisms. However, the scale and quantitative aspects of antibiotic production in natural settings are poorly understood. We addressed these fundament...

  15. Accumulation of the antibiotic phenazine-1-carboxylic acid in the rhizosphere of dryland cereals

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural antibiotics are thought to function in microbial defense, fitness, competitiveness, biocontrol, communication and gene regulation. However, the frequency and amount of antibiotics produced in nature are poorly understood. In this study, we assessed the geographic distribution of indigenous p...

  16. ACCUMULATION OF THE ANTIBIOTIC PHENAZINE-1-CARBOXYLIC ACID IN THE RHIZOSPHERE OF DRYLAND WHEAT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural antibiotics are thought to function in microbial defense, fitness, competitiveness, biocontrol, communication and gene regulation activity, and antibiotic-producing species are commonly found in microbial communities throughout nature. However, the frequency and amount of antibiotic producti...

  17. Synergistic extraction of rare earths using acid–base coupling extractants of calix[4]arene carboxyl derivative and primary amine N1923

    Microsoft Academic Search

    Wenwei He; Wuping Liao; Chunji Niu; Deqian Li

    2008-01-01

    Synergistic effect in the extraction of rare earth (RE) metals by the acid–base coupling (ABC) extractants of calix[4]arene carboxyl derivative tBu[4]CH2COOH (H4A) and primary amine N1923 (RNH2) has been investigated. The extraction of RE was enhanced by the addition of sodium cations into the aqueous phase not only in the extraction system of tBu[4]CH2COOH alone but also in the mixture

  18. Light and temperature-entrained circadian regulation of activity and mRNA accumulation of 1-aminocyclopropane-1-carboxylic acid oxidase in Stellaria longipes

    Microsoft Academic Search

    Arumugam Kathiresan; D. M. Reid; C. C. Chinnappa

    1996-01-01

    Stem and leaf tissues of Stellaria longipes Goldie (prairie ecotype) exhibit circadian rhythmicity in the activity and mRNA abundance for 1-aminocyclopropane-1-carboxylic acid oxidase (EC 1.4.3). The steady-state mRNA levels and enzymatic activity levels fluctuated with a period of approximately 24 h and reached their maxima by the middle of the light phase and minima by the middle of the dark

  19. Activation of carboxylic acids as their active esters by means of tert-butyl 3-(3,4-dihydrobenzotriazine-4-on)yl carbonate

    Microsoft Academic Search

    Yochai Basel; Alfred Hassner

    2002-01-01

    Carboxylic acids were activated in the presence of DMAP with tert-butyl carbonates (BOC-OX) 1, which were prepared in situ by reaction of X-OH and di-tert-butyl dicarbonate (BOC2O). The most efficient active carbonate proved to be tert-butyl 3-(3,4-dihydrobenzotriazine-4-on)yl carbonate 1a, leading to efficient formation of benzotriazinonyl esters 3 and 6, which are intermediates in reactions with primary and secondary amines to

  20. Screening of optimum condition for combined modification of ultra-stable Y zeolites using multi-hydroxyl carboxylic acid and phosphate

    Microsoft Academic Search

    Xing-wen Chang; Li-feng He; Hai-ning Liang; Xin-mei Liu; Zi-feng Yan

    2010-01-01

    According to the performance requirements of hydrocracking catalyst with high selectivity to middle distillate, multi-hydroxyl carboxylic acid (MHCA) and phosphate (AP) were used to achieve combined dealuminum modification of ultra-stable Y zeolites. The modification effect was influenced by the concentration of MHCA and AP, liquid–liquid ratio, reaction temperature and reaction time. In order to find the optimum modification condition, orthogonal

  1. Selective synthesis of ?,?-dideuterio alcohols by the reduction of carboxylic acids using SmI2 and D2O as deuterium source under SET conditions.

    PubMed

    Szostak, Michal; Spain, Malcolm; Procter, David J

    2014-10-01

    The first general method for the chemoselective synthesis of ?,?-dideuterio alcohols directly from feedstock carboxylic acids under single electron transfer conditions using SmI2 is reported. This reaction proceeds after the activation of Sm(II) with a Lewis base, results in excellent levels of deuterium incorporation across a wide range of substrates, and represents an attractive alternative to processes mediated by pyrophoric alkali metal deuterides. PMID:25247236

  2. Polymethyl methacrylate-co-methacrylic acid coatings with controllable concentration of surface carboxyl groups: A novel approach in fabrication of polymeric platforms for potential bio-diagnostic devices

    NASA Astrophysics Data System (ADS)

    Hosseini, Samira; Ibrahim, Fatimah; Djordjevic, Ivan; Koole, Leo H.

    2014-05-01

    The generally accepted strategy in development of bio-diagnostic devices is to immobilize proteins on polymeric surfaces as a part of detection process for diseases and viruses through antibody/antigen coupling. In that perspective, polymer surface properties such as concentration of functional groups must be closely controlled in order to preserve the protein activity. In order to improve the surface characteristics of transparent polymethacrylate plastics that are used for diagnostic devices, we have developed an effective fabrication procedure of polymethylmetacrylate-co-metacrylic acid (PMMA-co-MAA) coatings with controlled number of surface carboxyl groups. The polymers were processed effectively with the spin-coating technique and the detailed control over surface properties is here by demonstrated through the variation of a single synthesis reaction parameter. The chemical structure of synthesized and processed co-polymers has been investigated with nuclear magnetic resonance spectroscopy (NMR) and matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-ToF-MS). The surface morphology of polymer coatings have been analyzed with atomic force microscopy (AFM) and scanning electron microscopy (SEM). We demonstrate that the surface morphology and the concentration of surface -COOH groups (determined with UV-vis surface titration) on the processed PMMA-co-MAA coatings can be precisely controlled by variation of initial molar ratio of reactants in the free-radical polymerization reaction. The wettability of developed polymer surfaces also varies with macromolecular structure.

  3. In vivo oxidation of carboxyl-labelled cyclic fatty acids formed from linoleic and linolenic acids in the rat.

    PubMed

    Joffre, Florent; Roy, Alexandre; Bretillon, Lionel; Pasquis, Bruno; Sergiel, Jean-Pierre; Loreau, Olivier; Chardigny, Jean-Michel; Sébédio, Jean-Louis

    2004-01-01

    Cyclic fatty acid monomers (CFAM), which occur from the intramolecular cyclisation of linoleic and linolenic acids, are subsequently present in some edible oils and are suspected to induce metabolic disorders. One may suggest that the presence of a ring would alter the ability of the organism to oxidise these molecules. In order to test this hypothesis, we assessed the oxidative metabolism of CFAM in rats. For this purpose, rats were force-fed from 1.5 to 2.6 MBq of [1-(14)C]-linoleic acid, [1-(14)C]-linolenic acid, [1-(14)C]-CFAM-18:2 or [1-(14)C]-CFAM-18:3, and 14CO2 production was monitored for 24 h. The animals were then sacrificed and the radioactivity was determined in different tissues. No significant differences in 14CO2 production were found 24 h after the administration of CFAM and their respective precursors. Our data clearly demonstrate that, at least for the first beta-oxidation cycle, CFAM are oxidised in a similar way as both essential fatty acids. PMID:15270550

  4. Retention indices, relative response factors, and mass spectra of trifluoroethyl and heptafluorobutyl esters of carboxylic acids determined by capillary GC/MS

    SciTech Connect

    Yu, S.K.-T.; Vrana, R.P.; Green, J.B.

    1990-11-01

    The GC/MS characteristics of carboxylic acid esters prepared from fluorine-containing alcohols were compared to those of methyl esters. The GC retention of 2,2,2-trifluoroethyl (TFE) esters was less than, and 2,2,3,3,4,4,4-heptafluoro-1-butyl (HFB) esters approximately equivalent to that of methyl esters. The peak shape of both TFE and HFB esters was slightly superior to that of methyl esters. Mass spectra of TFE and HFB aliphatic esters show significantly more intense molecular and key fragment ions than those of methyl esters. Also, owing to their significantly higher molecular weights, TFE or HFB ester molecular ions and most fragment ions of interest occur at significantly higher m/z values than most potential interfering ions. The GC retention indices, relative GC/MS total ion current response factors, and 70 eV electron impact mass spectra of about 70 TFE and 70 HFB carboxylic acid esters are reported. Results from analysis of a TFE/HFB esterified petroleum carboxylic acid concentrate are discussed in detail. 26 refs., 17 figs., 3 tabs.

  5. Crystal structure of 9-(4-bromo­but­yl)-9H-fluorene-9-carb­oxy­lic acid

    PubMed Central

    Zhang, Xu-Yang; Liu, Bing-Ni; Wang, Ping-Bao; Liu, Deng-Ke

    2014-01-01

    The title compound, C18H17BrO2, is a key inter­mediate in the synthesis of lomitapide mesylate, a microsomal triglyceride transfer protein inhibitor. Its asymmetric unit contains two independent mol­ecules with slightly different conformations; the mean planes of the 4-bromo­butyl and carboxyl­ate groups in the two mol­ecules form dihedral angles of 24.54?(12) and 17.10?(18)°. In the crystal, carboxyl­ate groups are involved in O—H?O hydrogen bonding, which leads to the formation of two crystallographically independent centrosymmetric dimers. Weak inter­molecular C—H?O inter­actions further link these dimers into layers parallel to the bc plane. PMID:25484705

  6. Toward the Complete Characterization of Atmospheric Organic Particulate Matter: Derivatization and Two-Dimensional Comprehensive Gas Chromatography/Time of Flight Mass Spectrometry as a Method for the Determination of Carboxylic Acids

    NASA Astrophysics Data System (ADS)

    Boris, Alexandra Jeanne

    Understanding the composition of atmospheric organic particulate matter (OPM) is essential for predicting its effects on climate, air quality, and health. However, the polar oxygenated fraction (PO-OPM), which includes a significant mass contribution from carboxylic acids, is difficult to speciate and quantitatively determine by current analytical methods such as gas chromatography-mass spectrometry (GC-MS). The method of chemical derivatization and two-dimensional GC with time of flight MS (GCxGC/TOF-MS) was examined in this study for its efficacy in: 1) quantifying a high percentage of the total organic carbon (TOC) mass of a sample containing PO-OPM; 2) quantitatively determining PO-OPM components including carboxylic acids at atmospherically relevant concentrations; and 3) tentatively identifying PO-OPM components. Two derivatization reagent systems were used in this study: BF3/butanol for the butylation of carboxylic acids, aldehydes, and acidic ketones, and BSTFA for the trimethylsilylation (TMS) of carboxylic acids and alcohols. Three alpha-pinene ozonolysis OPM filter samples and a set of background filter samples were collected by collaborators in a University of California, Riverside environmental chamber. Derivatization/GCxGC TOF-MS was used to tentatively identify some previously unidentified ?-pinene ozonolysis products, and also to show the characteristics of all oxidation products determined. Derivatization efficiencies as measured were 40-70% for most butyl derivatives, and 50-58% for most trimethylsilyl derivatives. A thermal optical method was used to measure the TOC on each filter, and a value of the quantifiable TOC mass using a gas chromatograph was calculated for each sample using GCxGC separation and the mass-sensitive response of a flame ionization detector (FID). The TOC quantified using TMS and GCxGC-FID (TMS/TOCGCxGC FID) accounted for 15-23% of the TOC measured by the thermal-optical method. Using TMS and GCxGC/TOF-MS, 8.85% of the thermal optical TOC was measured and 48.2% of the TMS/TOCGCxGC-FID was semi-quantified using a surrogate standard. The carboxylic acids tentatively identified using TMS and GCxGC/TOF-MS accounted for 8.28% of the TOC measured by thermal optical means. GCxGC TOF-MS chromatograms of derivatized analytes showed reduced peak tailing due in part to the lesser interactions of the derivatized analytes with the stationary phase of the chromatography column as compared to the chromatograms of underivatized samples. The improved peak shape made possible the greater separation, quantification, and identification of high polarity analytes. Limits of detection using derivatization and GCxGC/TOF-MS were <1 ng per ?L injected for a series of C2-C6 di-acids, cis-pinonic acid, and dodecanoic acid using both butylation and TMS. Derivatization with GCxGC/TOF-MS was therefore effective for determining polar oxygenated compounds at low concentrations, for determining specific oxidation products not previously identified in OPM, and also for characterizing the probable functional groups and structures of ?-pinene ozonolysis products.

  7. The carboxyl-terminal region of Crtac1B/LOTUS acts as a functional domain in endogenous antagonism to Nogo receptor-1.

    PubMed

    Kurihara, Yuji; Arie, Yuko; Iketani, Masumi; Ito, Hiromu; Nishiyama, Kuniyuki; Sato, Yasufumi; Nakamura, Fumio; Mizuki, Nobuhisa; Goshima, Yoshio; Takei, Kohtaro

    2012-02-10

    Myelin-derived axon growth inhibitors, such as Nogo, bind to Nogo receptor-1 (NgR1) and thereby limit the action of axonal regeneration after injury in the adult central nervous system. Recently, we have found that cartilage acidic protein-1B (Crtac1B)/lateral olfactory tract usher substance (LOTUS) binds to NgR1 and functions as an endogenous NgR1 antagonist. To examine the functional domain of LOTUS in the antagonism to NgR1, analysis using the deletion mutants of LOTUS was performed and revealed that the carboxyl-terminal region (UA/EC domain) of LOTUS bound to NgR1. The UA/EC fragment of LOTUS overexpressed together with NgR1 in COS7 cells abolished the binding of Nogo66 to NgR1. Overexpression of the UA/EC fragment in cultured chick dorsal root ganglion neurons suppressed Nogo66-induced growth cone collapse. These findings suggest that the UA/EC region is a functional domain of LOTUS serving for an antagonistic action to NgR1. PMID:22281491

  8. Bile Acids Regulate Cardiovascular Function

    PubMed Central

    Khurana, Sandeep; Raufman, Jean-Pierre; Pallone, Thomas L.

    2011-01-01

    Research over the last decade has uncovered roles for bile acids (BAs) that extend beyond their traditional functions in regulating lipid digestion and cholesterol metabolism. BAs are now recognized as signaling molecules that interact with both plasma membrane and nuclear receptors. Emerging evidence indicates that by interacting with these receptors BAs regulate their own synthesis, glucose and energy homeostasis, and other important physiological events. Herein, we provide a comprehensive review of the actions of BAs on cardiovascular function. In the heart and the systemic circulation, BAs interact with plasma membrane G-protein coupled receptors, e.g. TGR5 and muscarinic receptors, and nuclear receptors, e.g. the farnesoid (FXR) and pregnane (PXR) xenobiotic receptors. BA receptors are expressed in cardiovascular tissue, however, the mechanisms underlying BA-mediated regulation of cardiovascular function remain poorly understood. BAs reduce heart rate by regulating channel conductance and calcium dynamics in sino-atrial and ventricular cardiomyocytes, and regulate vascular tone via both endothelium-dependent and -independent mechanisms. End-stage-liver disease, obstructive jaundice and intrahepatic cholestasis of pregnancy are prominent conditions in which elevated serum BAs alter vascular dynamics. This review focuses on BAs as newly-recognized signaling molecules that modulate cardiovascular function. PMID:21707953

  9. Cyanide Toxicokinetics: The Behavior of Cyanide, Thiocyanate and 2-Amino-2-Thiazoline-4-Carboxylic Acid in Multiple Animal Models

    PubMed Central

    Bhandari, Raj K.; Oda, Robert P.; Petrikovics, Ilona; Thompson, David E.; Brenner, Matthew; Mahon, Sari B.; Bebarta, Vikhyat S.; Rockwood, Gary A.; Logue, Brian A.

    2014-01-01

    Cyanide causes toxic effects by inhibiting cytochrome c oxidase, resulting in cellular hypoxia and cytotoxic anoxia, and can eventually lead to death. Cyanide exposure can be verified by direct analysis of cyanide concentrations or analyzing its metabolites, including thiocyanate (SCN?) and 2-amino-2-thiazoline-4-carboxylic acid (ATCA) in blood. To determine the behavior of these markers following cyanide exposure, a toxicokinetics study was performed in three animal models: (i) rats (250–300 g), (ii) rabbits (3.5–4.2 kg) and (iii) swine (47–54 kg). Cyanide reached a maximum in blood and declined rapidly in each animal model as it was absorbed, distributed, metabolized and eliminated. Thiocyanate concentrations rose more slowly as cyanide was enzymatically converted to SCN?. Concentrations of ATCA did not rise significantly above the baseline in the rat model, but rose quickly in rabbits (up to a 40-fold increase) and swine (up to a 3-fold increase) and then fell rapidly, generally following the relative behavior of cyanide. Rats were administered cyanide subcutaneously and the apparent half-life (t1/2) was determined to be 1,510 min. Rabbits were administered cyanide intravenously and the t1/2 was determined to be 177 min. Swine were administered cyanide intravenously and the t1/2 was determined to be 26.9 min. The SCN? t1/2 in rats was 3,010 min, but was not calculated in rabbits and swine because SCN? concentrations did not reach a maximum. The t1/2 of ATCA was 40.7 and 13.9 min in rabbits and swine, respectively, while it could not be determined in rats with confidence. The current study suggests that cyanide exposure may be verified shortly after exposure by determining significantly elevated cyanide and SCN? in each animal model and ATCA may be used when the ATCA detoxification pathway is significant. PMID:24711295

  10. Analysis of 2-oxothiazolidine-4-carboxylic acid by hydrophilic interaction liquid chromatography: application for ocular delivery using chitosan nanoparticles.

    PubMed

    Al-Kinani, Ali Athab; Naughton, Declan P; Calabrese, Gianpiero; Vangala, Anil; Smith, James R; Pierscionek, Barbara K; Alany, Raid G

    2015-03-01

    Oxidative damage due to low levels of glutathione (GSH) is one of the main causes of cataract formation. It has been reported that 2-oxothiazolidine-4-carboxylic acid (OTZ), a cysteine prodrug, can increase the cellular level of GSH. Currently, there is no analytical method to separate and quantify OTZ from aqueous humour samples for cataract research. The present study aims to develop and validate a hydrophilic interaction liquid chromatography (HILIC) method for the quantification of OTZ in simulated aqueous humour (SAH). The developed method was validated according to FDA guidelines. Accuracy, precision, selectivity, sensitivity, linearity, lower limit of quantification (LLOQ), lower limit of detection (LLOD) and stability were the parameters assessed in the method validation. The developed method was found to be accurate and precise with LLOQ and LLOD of 200 and 100 ng/mL, respectively; method selectivity was confirmed by the absence of any matrix interference with the analyte peak. The constructed calibration curve was linear in the range of 0.2-10 ?g/mL, with a regression coefficient of 0.999. In addition, the OTZ was found to be stable in SAH after three freeze/thaw cycles. Chitosan nanoparticles loaded with OTZ were formulated by the ionic gelation method. The nanoparticles were found to be uniform in shape and well dispersed with average size of 153 nm. The in vitro release of OTZ from the nanoparticles was quantified using the developed analytical method over 96 h. Permeation of OTZ through excised bovine cornea was measured using HILIC. The lag time and the flux were 0.2 h and 3.05 ?g/cm(2) h, respectively. PMID:25662935

  11. 1-Aminocyclopropane-1-carboxylic acid (ACC) concentration and ACC synthase expression in soybean roots, root tips, and soybean cyst nematode (Heterodera glycines)-infected roots

    PubMed Central

    Tucker, Mark L.; Xue, Ping; Yang, Ronghui

    2010-01-01

    Colonization of plant roots by root knot and cyst nematodes requires a functional ethylene response pathway. However, ethylene plays many roles in root development and whether its role in nematode colonization is direct or indirect, for example lateral root initiation or root hair growth, is not known. The temporal requirement for ethylene and localized synthesis of ethylene during the life span of soybean cyst nematode (SCN) on soybean roots was further investigated. Although a significant increase in ethylene evolution was not detected from SCN-colonized roots, the concentration of the immediate precursor to ethylene, 1-aminocyclopropane-1-carboxylic acid (ACC), was higher in SCN-colonized root pieces and root tips than in other parts of the root. Moreover, expression analysis of 17 ACC synthase (ACS) genes indicated that a select set of ACS genes is expressed in SCN-colonized root pieces that is clearly different from the set of genes expressed in non-colonized roots or root tips. Semi-quantitative real-time PCR indicated that ACS transcript accumulation correlates with the high concentration of ACC in root tips. In addition, an ACS-like sequence was found in the public SCN nucleotide database. Acquisition of a full-length sequence for this mRNA (accession GQ389647) and alignment with transcripts for other well-characterized ACS proteins indicated that the nematode sequence is missing a key element required for ACS activity and therefore probably is not a functional ACS. Moreover, no significant amount of ACC was found in any growth stage of SCN that was tested. PMID:19861652

  12. Complex metabolism of aromatic glucosinolates in Pieris rapae caterpillars involving nitrile formation, hydroxylation, demethylation, sulfation, and host plant dependent carboxylic acid formation.

    PubMed

    Agerbirk, Niels; Olsen, Carl Erik; Poulsen, Eva; Jacobsen, Niels; Hansen, Paul Robert

    2010-02-01

    We investigated the metabolism of two chain elongated phenolic glucosinolates and the corresponding O-methyl derivatives upon ingestion by caterpillars of the butterfly Pieris rapae (L.). The glucosinolates (GSLs) were 4-hydroxyphenethylGSL, (R)-2-hydroxy-2-(4-hydroxyphenyl)ethylGSL, 4-methoxyphenethylGSL, and (R)-2-hydroxy-2-(4-methoxyphenyl)ethylGSL, variously occurring in foliage of two Arabis species: Arabis hirsuta (L.) Scop. and Arabis soyeri Reut. & Huet subsp. subcoriacea (Gren. ex Nyman) Breitstr. (Brassicaceae). Frass from caterpillars reared on each Arabis species contained two sulfated nitriles (4-sulfates of 3-(4-hydroxyphenyl)propanenitrile and 3-hydroxy-3-(4-hydroxyphenyl)propanenitrile) as apparent GSL metabolites. Comparison of glucosinolate levels in foliage and levels of sulfated nitriles in frass, and experiments with isolated GSLs spiked to crucifer foliage and ingested by P. rapae, demonstrated that phenolic GSLs and the corresponding O-methyl derivatives were metabolised to sulfated nitriles, and that metabolites lacking a beta-hydroxy group were partially hydroxylated in this position during metabolism in P. rapae. In contrast, an induction experiment did not show increased levels of beta-hydroxylated GSLs in A. soyeri plants upon caterpillar feeding. Frass contents of other putative GSL metabolites from the interaction with the two Arabis species differed significantly; caterpillars reared on A. hirsuta excreted significant amounts of four carboxylic acids (3-(4-hydroxyphenyl)propanoic acid, 3-hydroxy-3-(4-hydroxyphenyl)propanoic acid, and the corresponding 4-sulfates), which were low or absent when the caterpillars were reared on A. soyeri. The excreted carboxylic acids could be formed by hydrolysis of nitriles to carboxylic acids in caterpillar guts by an ingested nitrilase enzyme from A. hirsuta foliage; this hypothesis was supported by demonstration of 3-(4-hydroxyphenyl)propanenitrile hydrolysing nitrilase activity (E.C. 3.5.5.x) in a crude A. hirsuta extract. Some hypothetic metabolites, glycine conjugates of phenolic carboxylic acids, were not detected. Conditions for group separation and HPLC isolation of intact GSLs and sulfated metabolites were optimised, NMR spectroscopic data of the compounds are reported, and evolutionary and ecological implications are discussed. PMID:20079434

  13. 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.

  14. Rapid determination of memantine in human plasma by using nanoring carboxyl-functionalized paramagnetic molecularly imprinted polymer d-?-SPE and UFLC-MS/MS.

    PubMed

    Qiu, Hai-Wen; Xia, Lei; Gong, Li-Min; Ruan, Lie-Min; Zhao, Yong-Gang

    2015-06-01

    A novel, simple, and sensitive method based on the use of dispersive micro-solid-phase extraction (d-?-SPE) procedure combined with ultra-fast liquid chromatography-tandem quadrupole mass spectrometry (UFLC-MS/MS) for the determination of memantine (ME) was developed and validated over the linearity range 0.05-10.0?µg/L with 100??L of human plasma using memantine-D6 (ME-D6) as the internal standard. The novel nanoring carboxyl-functionalized paramagnetic molecularly imprinted polymer (NR-CF-Mag-MIP) was synthesized by ultrasound-assisted suspension polymerization, using ME as a template molecule, methacrylic acid as a functional monomer, and divinylbenzene as a cross-linking agent. The NR-CF-Mag-MIP was used as the d-?-SPE sorbent to extract ME from human plasma samples. The obtained results demonstrated the higher extraction capacity of NR-CF-Mag-MIP with recoveries between 97.6 and 101%. The limits of quantification (LOQs) for ME was 0.015?µg/L. Validation results on linearity, specificity, accuracy, precision, and stability, as well as on application to the analysis of samples taken up to 480?h after oral administration of 20?mg (two 10?mg capsules) of ME in healthy volunteers demonstrated the applicability to bioequivalence studies. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25209851

  15. Molecular modeling of the dimeric structure of human lipoprotein lipase and functional studies of the carboxyl-terminal domain.

    PubMed

    Kobayashi, Yoko; Nakajima, Toshiaki; Inoue, Ituro

    2002-09-01

    Lipoprotein lipase (LPL) plays a key role in lipid metabolism. Molecular modeling of dimeric LPL was carried out using insight ii based upon the crystal structures of human, porcine, and horse pancreatic lipase. The dimeric model reveals a saddle-shaped structure and the key heparin-binding residues in the amino-terminal domain located on the top of this saddle. The models of two dimeric conformations - a closed, inactive form and an open, active form - differ with respect to how surface-loop positions affect substrate access to the catalytic site. In the closed form, the surface loop covers the catalytic site, which becomes inaccessible to solvent. Large conformational changes in the open form, especially in the loop and carboxyl-terminal domain, allow substrate access to the active site. To dissect the structure-function relationships of the LPL carboxyl-terminal domain, several residues predicted by the model structure to be essential for the functions of heparin binding and substrate recognition were mutagenized. Arg405 plays an important role in heparin binding in the active dimer. Lys413/Lys414 or Lys414 regulates heparin affinity in both monomeric and dimeric forms. To evaluate the prediction that LPL forms a homodimer in a 'head-to-tail' orientation, two inactive LPL mutants - a catalytic site mutant (S132T) and a substrate-recognition mutant (W390A/W393A/W394A) - were cotransfected into COS7 cells. Lipase activity could be recovered only when heterodimerization occurred in a head-to-tail orientation. After cotransfection, 50% of the wild-type lipase activity was recovered, indicating that lipase activity is determined by the interaction between the catalytic site on one subunit and the substrate-recognition site on the other. PMID:12230584

  16. pH responsive properties of non-fouling mixed-charge polymer brushes based on quaternary amine and carboxylic acid monomers.

    PubMed

    Mi, Luo; Bernards, Matthew T; Cheng, Gang; Yu, Qiuming; Jiang, Shaoyi

    2010-04-01

    In this work, we report a tunable mixed-charge copolymer surface containing positively charged quaternary amine monomers ([2-(acryloyloxy)ethyl] trimethyl ammonium chloride, TMA) and negatively-charged carboxylic acid monomers (2-carboxy ethyl acrylate, CAA). The non-fouling properties of this copolymer coating depend on environmental pH. The surface has charge neutrality under neutral and basic conditions, and is positively charged under acidic conditions due to the protonation of the carboxylic acid group. This transition in surface charge with respect to pH allows the surface to be switched from bacteria-adhesive to bacteria-resistant. We demonstrate that the bacteria adhered to the surface under acidic conditions can be easily released as bulk pH increases. This tunable surface can be used to collect a contaminant and then be externally stimulated to release the contaminant, to allow for analysis of its composition. Its bacteria attraction and release property makes it very promising for decontamination and biomedical applications. PMID:20045182

  17. Catalytic Thiol and Carboxylate: Role of Cysteine and Glutamic Acid in the Xylosidic Activity of Endoxylanase from Chainiasp. (NCL 82-5-1)

    Microsoft Academic Search

    S. Hegde Subray; R. Kumar Ameeta; N. Ganesh Krishna; Islam M. Khan

    1998-01-01

    Chemical modification of the endoxylanase fromChainiasp. with group-specific chemical modifiers in the absence and presence of substrate and kinetics of modification revealed the involvement of a thiol and a carboxylate in the catalytic function of the enzyme. The active-site peptides were chemically labeled and sequenced. The sequence alignment of the chemically labeled peptide with other family G\\/11 xylanases showed that

  18. Grafting of end-functionalized poly( tert-butyl acrylate) to poly(ethylene- co-acrylic acid) film

    Microsoft Academic Search

    Keisha B. Walters; Douglas E. Hirt

    2006-01-01

    Poly(tert-butyl acrylate) (PtBA) was grafted to the surface of poly(ethylene-co-acrylic acid) (EAA) film and the pendant groups of the tethered PtBA were modified to create chemically tailored surface modifying layers. The carboxylic acid groups in the copolymer film served as the grafting sites for the covalent tethering of end-functionalized PtBA. The progression of these reactions was monitored using attenuated total

  19. 1-Aminocyclopropane-1-carboxylic acid and abscisic acid during the germination of sugar beet (Beta vulgaris L.): a comparative study of fruits and seeds.

    PubMed

    Hermann, Katrin; Meinhard, Juliane; Dobrev, Peter; Linkies, Ada; Pesek, Bedrich; Hess, Barbara; Machácková, Ivana; Fischer, Uwe; Leubner-Metzger, Gerhard

    2007-01-01

    The control of sugar beet (Beta vulgaris L.) germination by plant hormones was studied by comparing fruits and seeds. Treatment of sugar beet fruits and seeds with gibberellins, brassinosteroids, auxins, cytokinins, and jasmonates or corresponding hormone biosynthesis inhibitors did not appreciably affect radicle emergence of fruits or seeds. By contrast, treatment with ethylene or the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) promoted radicle emergence of fruits and seeds. Abscisic acid (ABA) acted as an antagonist of ethylene and inhibited radicle emergence of seeds, but not appreciably of fruits. High endogenous contents of ACC and of ABA were evident in seeds and pericarps of dry mature fruits, but declined early during imbibition. ABA-treatment of seeds and fruits induced seed ACC accumulation while ACC-treatment did not affect the seed ABA content. Transcripts of ACC oxidase (ACO, ethylene-forming enzyme) and ABA 8'-hydroxylase (CYP707A, ABA-degrading enzyme) accumulate in fruits and seeds upon imbibition. ABA and ACC and the pericarp did not affect the seed CYP707A transcript levels. By contrast, seed ACO transcript accumulation was promoted by ABA and by pericarp removal, but not by ACC. Quantification of the endogenous ABA and ACC contents, ABA and ACC leaching, and ethylene evolution, demonstrate that an embryo-mediated active ABA extrusion system is involved in keeping the endogenous seed ABA content low by 'active ABA leaching', while the pericarp restricts ACC leaching during imbibition. Sugar beet radicle emergence appears to be controlled by the pericarp, by ABA and ACC leaching, and by an ABA-ethylene antagonism that affects ACC biosynthesis and ACO gene expression. PMID:17761730

  20. 3922 J. Org. Chem. 1990,55, 3922-3926 Diiodosilane. 3.' Direct Synthesis of Acyl Iodides from Carboxylic Acids,

    E-print Network

    Keinan, Ehud

    reagents. The first synthesis dates back to 1832 when Liebig and Wohler reported that treatment of benzoyl reagent^.^ The only reported exception to the above statements is Jung's observation that treatment the initially formed trimethylsilyl carboxylate into palmityl iodide.l0 We report here that the inorganic

  1. Heterocyclic-2-carboxylic acid (3-cyano-1,4-di-N-oxidequinoxalin-2-yl)amide derivatives as hits for the development of neglected disease drugs.

    PubMed

    Ancizu, Saioa; Moreno, Elsa; Torres, Enrique; Burguete, Asunción; Pérez-Silanes, Silvia; Benítez, Diego; Villar, Raquel; Solano, Beatriz; Marín, Adoración; Aldana, Ignacio; Cerecetto, Hugo; González, Mercedes; Monge, Antonio

    2009-01-01

    Neglected diseases represent a major health problem. It is estimated that one third of the world population is infected with tuberculosis (TB). Besides TB, Chagas disease, affects approximately 20 million people. Quinoxalines display great activities against TB and Chagas. Forty new quinoxaline 1,4-di-N-oxide derivatives have been prepared and tested against M. tuberculosis and T. cruzi. Carboxylic acid quinoxaline 1,4-di-N-oxides (CAQDOs) 5 and 17 showed MIC values on the same order as the reference antituberculosis drug, rifampicin. Meanwhile, CAQDOs 12 and 22 presented IC(50) values in the same order as the anti-chagasic drug, nifurtimox. PMID:19553897

  2. Synthesis of 3,8,9-trisubstituted-1,7,9-triaza-fluorene-6-carboxylic acid derivatives as a new class of insulin secretagogues

    Microsoft Academic Search

    Rajesh H. Bahekar; Mukul R. Jain; Pradip A. Jadav; Ashish Goel; Dipam N. Patel; Vijay M. Prajapati; Arun A. Gupta; Honey Modi; Pankaj R. Patel

    2007-01-01

    ?-Carbolines stimulate insulin secretion in a glucose-dependent manner, probably by acting on I3-binding site. Knowing the in vitro glucose-dependent insulinotropic potential of ?-carbolines, in this project, three series of substituted-triaza-fluorene-6-carboxylic acids (5a–v, 6a–t, and 7a–t) were designed (analogs of ?-carboline) as a new class of insulinotropic agents. The in vitro glucose-dependent insulinotropic activities of test compounds were evaluated using RIN5F

  3. A facile hydroxyindole carboxylic acid-based focused library approach for potent and selective inhibitors of Mycobacterium protein tyrosine phosphatase B**

    PubMed Central

    Zeng, Li-Fan; Xu, Jie; He, Yantao; He, Rongjun; Wu, Li; Gunawan, Andrea M.

    2013-01-01

    A facile hydroxyindole carboxylic acid-based focused amide library approach was designed to target both the PTP active site and a unique nearby pocket for enhanced affinity and selectivity. High throughput screening of the focused library let to the identification of a highly potent (Ki=50 nM) and selective (>100-fold against a large panel of PTPs) inhibitor 11a for mPTPB, an essential virulence factor for Mycobacterium tuberculosis. Importantly, 11a displayed highly efficacious cellular activity and was capable of reversing the altered immune responses induced by mPTPB in macrophages. PMID:23568546

  4. Design, synthesis and anti-tubercular evaluation of new 2-acylated and 2-alkylated amino-5-(4-(benzyloxy)phenyl)thiophene-3-carboxylic acid derivatives. Part 1

    Microsoft Academic Search

    Xiaoyun Lu; Baojie Wan; Scott G. Franzblau; Qidong You

    2011-01-01

    A series of 2-acylated and 2-alkylated amino-5-(4-(benzyloxy)phenyl)thiophene-3-carboxylic acid derivatives were synthesized and evaluated for anti-tubercular activity. Among these compounds, 10d, 15, 12h and 12k inhibited Mycobacterium tuberculosis (Mtb) growth with MIC values between 1.9 and 7.7 ?M and low toxicity against VERO cells. The four compounds were also tested against multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) clinical strains, which

  5. Determination of 11-nor-? 9-tetrahydrocannabinol-9-carboxylic acid in urine using high-performance liquid chromatography and electrospray ionization mass spectrometry

    Microsoft Academic Search

    T Breindahl; K Andreasen

    1999-01-01

    High-performance liquid chromatography with electrospray ionization mass spectrometry was used to determine 11-nor-?9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) in urine. After basic hydrolysis of conjugates, the compound was extracted using SPEC-PLUS-3ML-C18 solid-phase extraction columns. A deuterium labelled internal standard (d3-THC-COOH) was added prior to hydrolysis. Separation was performed on a reversed-phase Zorbax Eclipse XDB-C8 analytical column (150×3.0 mm I.D.) using a gradient program

  6. Butyric acid in functional constipation

    PubMed Central

    Pituch, Aleksandra; Walkowiak, Jaros?aw

    2013-01-01

    Butyric acid, a short-chain fatty acid, is a major energy source for colonocytes. It occurs in small quantities in some foods, and in the human body, it is produced in the large intestine by intestinalkacteria. This production can be reduced in some cases, for which butyric acid supplementation may be useful. So far, the use of butyric acid in the treatment of gastrointestinal disorders has been limited because of its specific characteristics such as its rancid smell and rapid absorption in the upper gastrointestinal tract. In the Polish market, sodium butyrate has been recently made available, produced by the modern technology of microencapsulation, which allows the active substance to reach the small and large intestines, where butyrate easily dissociates into butyric acid. This article presents the potential beneficial mechanisms of action of butyric acid in defecation disorders, which are primarily associated with reductions in pain during defecation and inflammation in the gut, among others. PMID:24868272

  7. Solvent-induced synthesis of cobalt(II) coordination polymers based on a rigid ligand and flexible carboxylic acid ligands: syntheses, structures and magnetic properties.

    PubMed

    Wang, Ting; Zhang, Chuanlei; Ju, Zemin; Zheng, Hegen

    2015-04-21

    Five new cobalt(ii) coordination architectures, {[Co(L)2(H2O)2]·2H2O·2NO3}n (), {[Co(L)(ppda)]·2H2O}n (), {[Co2(L)(ppda)2]2·H2O}n (), {[Co(L)(nba)]·5H2O}n (), and {[Co(L)(oba)]2·3H2O}n (), have been constructed from the rigid ligand L [L = 2,8-di(1H-imidazol-1-yl)dibenzofuran] and different flexible carboxylic acid ligands [H2ppda = 4,4'-(perfluoropropane-2,2-diyl)dibenzoic acid, H2nba = 4,4'-azanediyldibenzoic acid, and H2oba = 4,4'-oxydibenzoic acid]. Depending on the nature of the solvent systems, these five different coordination polymers were synthesized and characterized by single-crystal X-ray diffraction, IR, PXRD and elemental analysis. Compounds , and were obtained by a one-pot method, and then we utilized the solvent-induced effect to obtain almost pure crystals of , respectively. Compound is an infinite 1D chain which is formed by L ligands and Co atoms. Compound contains a [Co2(CO2)4] secondary building unit (SBU), and can be topologically represented as a 6-connected 2-fold interpenetrating pcu net with the point symbol of {4(12)·6(3)}. Compound can be characterized as a 4-connected sql tetragonal planar network with the point symbol of {4(4)·6(2)}. In compounds and , there is a 1D chain which is formed by flexible carboxylic acid ligands and Co atoms; then the 1D chain is linked by L ligands in the tilting direction, leading to the formation of a 2D layer. Furthermore, UV-vis, TGA and magnetic properties have been investigated in detail. PMID:25778448

  8. Selective Catalysis of Lactic Acid to Produce Commodity Chemicals

    Microsoft Academic Search

    Yongxian Fan; Chunhui Zhou; Xiaohong Zhu

    2009-01-01

    Owning to its biobased organic acid, low cost and multiple reactive functionalities as it contains both one carboxylic acid group and hydroxyl group, lactic acid has been described as a commodity chemical sleeping giant. In this review, the conversion of lactic acid to other important commodity chemicals, such as, poly L?lactic acid, acrylic acid, 2, 3?pentanedione, pyruvic acid, propanoic acid,

  9. Regulating bioactivity of Cu2+ bis-1,10-phenanthroline artificial metallonucleases with sterically functionalized pendant carboxylates.

    PubMed

    Prisecaru, Andreea; McKee, Vickie; Howe, Orla; Rochford, Garret; McCann, Malachy; Colleran, John; Pour, Milan; Barron, Niall; Gathergood, Nicholas; Kellett, Andrew

    2013-11-14

    The synthetic chemical nuclease, [Cu(1,10-phenanthroline)2](2+), has stimulated research within metallonuclease development and in the area of cytotoxic metallodrug design. Our analysis reveals, however, that this agent is "promiscuous" as it binds both dsDNA and protein biomolecules, without specificity, and induces general toxicity to a diversity of cell lineages. Here, we describe the synthesis and characterization of small-molecule metallonucleases containing the redox-active cation, [Cu(RCOO)(1,10-phen)2](+), where 1,10-phen = 1,10-phenanthroline and R = -H, -CH3, -C2H5, -CH(CH3)2, and -C(CH3)3. The presence of coordinated carboxylate groups in the complex cation functions to enhance dsDNA recognition, reduce serum albumin binding, and offer control of toxicity toward human cancer cells, Gram positive and negative bacteria, and fungal pathogens. The induction of genomic dsDNA breaks (DSBs) were identified in ovarian adenocarcinoma cells using immunodetection of ?-H2AX. Formate, acetate, and pivalate functionalized complexes induced DSBs in a higher percentage of cells compared with [Cu(1,10-phen)2](2+), which supports the importance of inner-sphere modification toward enhancing targeted biological application. PMID:24131470

  10. RNA interference of 1-aminocyclopropane-1-carboxylic acid oxidase (ACO1 and ACO2) genes expression prolongs the shelf life of Eksotika (Carica papaya L.) papaya fruit.

    PubMed

    Sekeli, Rogayah; Abdullah, Janna Ong; Namasivayam, Parameswari; Muda, Pauziah; Abu Bakar, Umi Kalsom; Yeong, Wee Chien; Pillai, Vilasini

    2014-01-01

    The purpose of this study was to evaluate the effectiveness of using RNA interference in down regulating the expression of 1-aminocyclopropane-1-carboxylic acid oxidase gene in Eksotika papaya. One-month old embryogenic calli were separately transformed with Agrobacterium strain LBA 4404 harbouring the three different RNAi pOpOff2 constructs bearing the 1-aminocyclopropane-1-carboxylic acid oxidase gene. A total of 176 putative transformed lines were produced from 15,000 calli transformed, selected, then regenerated on medium supplemented with kanamycin. Integration and expression of the targeted gene in putatively transformed lines were verified by PCR and real-time RT-PCR. Confined field evaluation of a total of 31 putative transgenic lines planted showed a knockdown expression of the targeted ACO1 and ACO2 genes in 13 lines, which required more than 8 days to achieve the full yellow colour (Index 6). Fruits harvested from lines pRNAiACO2 L2-9 and pRNAiACO1 L2 exhibited about 20 and 14 days extended post-harvest shelf life to reach Index 6, respectively. The total soluble solids contents of the fruits ranged from 11 to 14° Brix, a range similar to fruits from non-transformed, wild type seed-derived plants. PMID:24950439

  11. Double D-?-A dye linked by 2,2'-bipyridine dicarboxylic acid: influence of para- and meta-substituted carboxyl anchoring group.

    PubMed

    Ganesan, Paramaguru; Chandiran, Aravind Kumar; Gao, Peng; Rajalingam, Renganathan; Grätzel, Michael; Nazeeruddin, Mohammad Khaja

    2015-04-01

    Starting from 2,2'-bipyridine dicarboxylic acid, two new (D-?-A)2 sensitizers, including m-DA with the carboxyl anchoring group substituted meta to the donor-bridge moiety and p-DA with a para-substituted anchoring group, were synthesized in order to evaluate the impact of the position of the anchoring group on the optical, electrochemical, and photovoltaic properties of dye-sensitized solar cells. p-DA exhibits red-shifted absorption behavior compared to m-DA, owing to the more efficiently extended ?-conjugation with para substitution. Both m-DA and p-DA are adsorbed on the mesoporous TiO2 surface by using both of their carboxylic acid groups in a bianchoring mode, which is confirmed through attenuated total reflectance FTIR analysis. Red-shifted absorption of p-DA assists the achievement of a red-shifted incident photon-to-electron conversion efficiency and a higher short-circuit current density than m-DA. The photogenerated electron lifetime in TiO2 is also found to be higher for para substituted p-DA than the meta-substituted m-DA, which results in a higher open-circuit voltage. All of the results suggest that dicarboxyl-2,2'-bipyridine can be used as an acceptor for metal-free organic sensitizers. However, the anchoring segments should be adjusted to the favorable position of the corresponding donor-bridge moieties for better conjugation. PMID:25656067

  12. The Carboxyl Tail of Alpha-Actinin-4 Regulates Its Susceptibility to m-Calpain and thus Functions in Cell Migration and Spreading

    PubMed Central

    Shao, Hanshuang; Travers, Tim; Camacho, Carlos; Wells, Alan

    2013-01-01

    Alpha-actinin-4 links the cytoskeleton to sites of adhesion and has been shown to be modulated to enable cell migration. Such focal adhesions must be labile to accomplish migration, with this detachment occurring at least in part via m-calpain activation (Glading et al., 2002, Glading et al., 2001, Xie et al., 1998). In this study, we report that alpha-actinin-4 is initially cleaved by m-calpain between tyrosine 13 and glycine. Removal of the first 13 amino acids does not affect alpha-actinin-4 binding to actin filaments and its localization within fibroblasts but drives cell migration with less persistence. Binding of phosphoinositides PI(4,5)P2, PI(3,4,5)P3 and PI(3,4)P2 to alpha-actinin-4, as well as binding of alpha-actinin-4 to actin filaments all inhibit m-calpain cleavage of ACTN4 between tyrosine 13 and glycine 14. Interestingly, the carboxyl terminus of alpha-actinin-4 including its calcium binding motifs, is inhibitory for a secondary cleavage of alpha-actinin-4 between lysine 283 and valine 284.The minimal length of inhibitory domain is mapped to the last 11 amino acids of alpha-actinin-4. The C-terminal tail of alpha-actinin-4 is essential for maintaining its normal actin binding activity and localization within cytoplasm and also its colocalization with actin in the lamellipodia of locomoting fibroblasts. Live cell imaging reveals that the 1–890 fragment fails to rescue neither the basal or growth factor-stimulated migration nor the revert the spread area of fibroblasts to the level of NR6WT. These findings suggest that the C-terminal tail of alpha-actinin-4 is essential for its function in cell migration and adhesion to substratum. PMID:23466492

  13. Simultaneous analysis of apolar phytohormones and 1-aminocyclopropan-1-carboxylic acid by high performance liquid chromatography/electrospray negative ion tandem mass spectrometry via 9-fluorenylmethoxycarbonyl chloride derivatization.

    PubMed

    Ziegler, Jörg; Qwegwer, Jakob; Schubert, Melvin; Erickson, Jessica L; Schattat, Martin; Bürstenbinder, Katharina; Grubb, C Douglas; Abel, Steffen

    2014-10-01

    A strategy to detect and quantify the polar ethylene precursor 1-aminocyclopropan-1-carboxylic acid (ACC) along with the more apolar phytohormones abscisic acid (ABA), indole-3-acetic acid (IAA), jasmonic acid (JA), jasmonic acid-isoleucine conjugate (JA-Ile), 12-oxo-phytodienoic acid (OPDA), trans-zeatin, and trans-zeatin 9-riboside using a single extraction is presented. Solid phase resins commonly employed for extraction of phytohormones do not allow the recovery of ACC. We circumvent this problem by attaching an apolar group to ACC via derivatization with the amino group specific reagent 9-fluorenylmethoxycarbonyl chloride (Fmoc-Cl). Derivatization in the methanolic crude extract does not modify other phytohormones. The derivatized ACC could be purified and detected together with the more apolar phytohormones using common solid phase extraction resins and reverse phase HPLC/electrospray negative ion tandem mass spectrometry. The limit of detection was in the low nanomolar range for all phytohormones, a sensitivity sufficient to accurately determine the phytohormone levels from less than 50mg (fresh weight) of Arabidopsis thaliana and Nicotiana benthamiana tissues. Comparison with previously published phytohormone levels and the reported changes in phytohormone levels after stress treatments confirmed the accuracy of the method. PMID:25160953

  14. Studies on the effect of CL 306,293, a substituted quinoline carboxylic acid, on the clinical disease induced in mice with LP-BM5 virus.

    PubMed

    Scott, J W; DeJoy, S Q; Jeyaseelan, R; Powell, D W; Raventos-Suarez, C; O'Hara, B; Wick, M M; Oronsky, A L; Kerwar, S S

    1993-01-01

    CL 306,293, a substituted quinoline carboxylic acid, is a potent inhibitor of dihydroorotic acid dehydrogenase, an enzyme essential for the biosynthesis of pyrimidines. In mammalian cell culture, the agent exhibits antiproliferative properties that can be reversed by the addition of uridine. CL 306,293 inhibits the development of the clinical disease in a murine model of immunodeficiency induced by a mixture of LP-BM5 retroviruses. In infected mice, the agent prevents the development of hypergammaglobulinemia, lymphadenopathy, splenomegaly and induction of an IL-2 deficiency. The CD4/CD8 ratio and the number of B cells in the lymph nodes are decreased if the infected animals are treated with CL 306,293. CL 306,293 was more efficacious and potent than 3'-azido-3'-deoxythymidine. The beneficial effects of CL 306,293 observed in this model are most probably related to its antiproliferative properties. PMID:8384434

  15. 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

  16. Stereoselective synthesis of unsaturated and functionalized L-NHBoc amino acids, using Wittig reaction under mild phase-transfer conditions.

    PubMed

    Rémond, Emmanuelle; Bayardon, Jérôme; Ondel-Eymin, Marie-Joëlle; Jugé, Sylvain

    2012-09-01

    The stereoselective synthesis of a new amino acid phosphonium salt was described by quaternization of melting triphenylphosphine with the ?-iodo NHBoc-amino ester, derived from L-aspartic acid. The deprotection of the carboxylic acid function to afford the phosphonium salt with a free carboxylic acid group was achieved by a palladium-catalyzed desallylation reaction. This phosphonium salt was used in the Wittig reaction with aromatic or aliphatic aldehydes and trifluoroacetophenone, under solid-liquid phase-transfer conditions in chlorobenzene and in the presence of K(3)PO(4) as weak base, to afford the corresponding unsaturated amino acids without racemization. Thus, the reaction with substituted aldehydes allows to graft various functionalized groups on the lateral chain of the amino acid, such as trifluoromethyl, cyano, nitro, ferrocenyl, boronato, or azido. In addition, the reaction of the amino acid Wittig reagent with ?,?-unsaturated aldehydes leads to amino acids bearing a diene on the lateral chain. Finally, this amino acid phosphonium salt appears to be a new powerful tool for the preparation of unsaturated and non-proteinogenic ?-amino acids, directly usable for the synthesis of customized peptides. PMID:22870957

  17. Expression and regulation of pear 1-aminocyclopropane-1-carboxylic acid synthase gene (PpACS1a) during fruit ripening, under salicylic acid and indole-3-acetic acid treatment, and in diseased fruit.

    PubMed

    Shi, Hai-Yan; Zhang, Yu-Xing

    2014-06-01

    In plants, the level of ethylene is determined by the activity of the key enzyme 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS). A gene encoding an ACC synthase protein was isolated from pear (Pyrus pyrifolia). This gene designated PpACS1a (GenBank accession no. KC632526) was 1488 bp in length with an open reading frame (ORF) encoding a protein of 495 amino acids that shared high similarity with other pear ACC synthase proteins. The PpACS1a was grouped into type-1 subfamily of plant ACS based on its conserved domain and phylogenetic status. Real-time quantitative PCR indicated that PpACS1a was differentially expressed in pear tissues and predominantly expressed in anthers. The expression signal of PpACS1a was also detected in fruit and leaves, but no signal was detected in shoots and petals. Furthermore, the PpACS1a expression was regulated during fruit ripening. In addition, the PpACS1a gene expression was regulated by salicylic acid (SA) and indole-3-acetic acid (IAA) in fruit. Moreover, the expression of the PpACS1a was up-regulated in diseased pear fruit. These results indicated that PpACS1a might be involved in fruit ripening and response to SA, IAA and disease. PMID:24562629

  18. Synthesis and characterization of a heteroleptic Ru(II) complex of phenanthroline containing oligo-anthracenyl carboxylic acid moieties.

    PubMed

    Adeloye, Adewale O; Ajibade, Peter A

    2010-01-01

    In an effort to develop new ruthenium(II) complexes, this work describes the design, synthesis and characterization of a ruthenium(II) functionalized phenanthroline complex with extended ?-conjugation. The ligand were L(1) (4,7-bis(2,3-dimethylacrylic acid)-1,10-phenanthroline), synthesized by a direct aromatic substitution reaction, and L(2) (4,7-bis(trianthracenyl-2,3-dimethylacrylic acid)-1,10-phenanthroline), which was synthesized by the dehalogenation of halogenated aromatic compounds using a zero-valent palladium cross-catalyzed reaction in the absence of magnesium-diene complexes and/or cyclooctadienyl nickel (0) catalysts to generate a new carbon-carbon bond (C-C bond) polymerized hydrocarbon units. The ruthenium complex [RuL(1)L(2)(NCS)(2)] showed improved photophysical properties (red-shifted metal-to-ligand charge-transfer transition absorptions and enhanced molar extinction coefficients), luminescence and interesting electrochemical properties. Cyclic and square wave voltammetry revealed five major redox processes. The number of electron(s) transferred by the ruthenium complex was determined by chronocoulometry in each case. The results show that processes I, II and III are multi-electron transfer reactions while processes IV and V involved one-electron transfer reaction. The photophysical property of the complex makes it a promising candidate in the design of chemosensors and photosensitizers, while its redox-active nature makes the complex a potential mediator of electron transfer in photochemical processes. PMID:20957086

  19. Synthesis and Characterization of a Heteroleptic Ru(II) Complex of Phenanthroline Containing Oligo-Anthracenyl Carboxylic Acid Moieties

    PubMed Central

    Adeloye, Adewale O.; Ajibade, Peter A.

    2010-01-01

    In an effort to develop new ruthenium(II) complexes, this work describes the design, synthesis and characterization of a ruthenium(II) functionalized phenanthroline complex with extended ?-conjugation. The ligand were L1 (4,7-bis(2,3-dimethylacrylic acid)-1,10-phenanthroline), synthesized by a direct aromatic substitution reaction, and L2 (4,7-bis(trianthracenyl-2,3-dimethylacrylic acid)-1,10-phenanthroline), which was synthesized by the dehalogenation of halogenated aromatic compounds using a zero-valent palladium cross-catalyzed reaction in the absence of magnesium-diene complexes and/or cyclooctadienyl nickel (0) catalysts to generate a new carbon-carbon bond (C-C bond) polymerized hydrocarbon units. The ruthenium complex [RuL1L2(NCS)2] showed improved photophysical properties (red-shifted metal-to-ligand charge-transfer transition absorptions and enhanced molar extinction coefficients), luminescence and interesting electrochemical properties. Cyclic and square wave voltammetry revealed five major redox processes. The number of electron(s) transferred by the ruthenium complex was determined by chronocoulometry in each case. The results show that processes I, II and III are multi-electron transfer reactions while processes IV and V involved one-electron transfer reaction. The photophysical property of the complex makes it a promising candidate in the design of chemosensors and photosensitizers, while its redox-active nature makes the complex a potential mediator of electron transfer in photochemical processes. PMID:20957086

  20. 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

  1. G?q Protein Carboxyl Terminus Imitation Polypeptide GCIP-27 Improves Cardiac Function in Chronic Heart Failure Rats

    PubMed Central

    Lu, Xiao Lan; Tong, Yang Fei; Liu, Ya; Xu, Ya Li; Yang, Hua; Zhang, Guo Yuan; Li, Xiao-Hui; Zhang, Hai-Gang

    2015-01-01

    Background G?q protein carboxyl terminus imitation polypeptide (GCIP)-27 has been shown to alleviate pathological cardiomyocyte hypertrophy induced by various factors. Pathological cardiac hypertrophy increases the morbidity and mortality of cardiovascular diseases while it compensates for poor heart function. This study was designed to investigate the effects of GCIP-27 on heart function in rats with heart failure induced by doxorubicin. Methods and Results Forty-eight rats were randomly divided into the following six groups receiving vehicle (control), doxorubicin (Dox), losartan (6 mg/kg, i.g.) and three doses of GCIP-27 (10, 30, 90 ?g/kg; i.p., bid), respectively. Heart failure was induced by Dox, which was administered at a 20 mg/kg cumulative dose. After 10 weeks of treatment, we observed that GCIP-27 (30, 90 ?g/kg) significantly increased ejection fraction, fraction shortening, stroke volume and sarcoplasmic reticulum Ca2+ ATPase activity of Dox-treated hearts. Additionally, GCIP-27 decreased myocardial injury, heart weight index and left ventricular weight index, fibrosis and serum cardiac troponin-I concentration in Dox-treated mice. Immunohistochemistry, western blotting and real-time PCR experiments indicated that GCIP-27 (10–90 ?g/kg) could markedly upregulate the protein expression of myocardial ?-myosin heavy chain (MHC), Bcl-2, protein kinase C (PKC) ? and phosphorylated extracellular signal-regulated kinase (p-ERK) 1/2 as well as the mRNA expression of ?-MHC, but downregulated the expression of ?-MHC, Bax and PKC ?II, and the mRNA expression levels of ?-MHC in Dox-treated mice. It was also found that GCIP-27 (30, 90 ?g/L) decreased cell size and protein content of cardiomyocytes significantly in vitro by comparison of Dox group. Conclusions GCIP-27 could effectively ameliorate heart failure development induced by Dox. PKC–ERK1/2 signaling might represent the underlying mechanism of the beneficial effects of GCIP-27. PMID:25822412

  2. Amino acids and gut function

    Microsoft Academic Search

    W. W. Wang; S. Y. Qiao; D. F. Li

    2009-01-01

    The intestine is not only critical for the absorption of nutrients, but also interacts with a complex external milieu. Most\\u000a foreign antigens enter the body through the digestive tract. Dietary amino acids are major fuels for the small intestinal\\u000a mucosa, as well as important substrates for syntheses of intestinal proteins, nitric oxide, polyamines, and other products\\u000a with enormous biological importance.

  3. 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 higher levels than isoprene-derived OS. This indicates that isoprene OS were long-range transported to Hyytiälä from southerly regions with high emissions of isoprene and related compounds. Influence of formation mechanisms and long-range transport on concentrations of OS, NOS and carboxylic acids will be discussed in the presentation.

  4. Synthesis and structural, conformational and pharmacological study of some esters derived from 3-?-hydroxytropan-3-?-carboxylic acid

    NASA Astrophysics Data System (ADS)

    Burgos, C.; Izquierdo, M. L.; Arias, M. S.; Gálvez, E.; Matesanz, E.; Martinez-Ripoll, M.; Sanz-Aparicio, J.; Fonseca, I.; Bellanato, J.; López-Ruiz, P.

    1993-12-01

    A series of 3-?-hydroxy-3-?-alkoxycarbonyl tropanes has been synthesized and studied by IR, 1H and 13C NMR spectroscopy, and the crystal structure of ethyl-3-?-hydroxytropan-3-?-carboxylate ( VIb) and phenethyl-3-?-hydroxytropan-3-?-carboxylate ( VIc) have been determined by X-ray diffraction. The compounds studied display in chloroform- d the same preferred conformation. The pyrrolidine and piperidine rings adopt a flattened N8 envelope and a distorted chair conformation puckered at N8 and strongly flattened at C3, respectively, with the N-methyl and hydroxy groups in equatorial and pseudo-equatorial positions and the ester group in a pseudo-axial arrangement with respect to the piperidine ring. An intramolecular interaction between the hydroxy group and the nitrogen atom is proposed. However in CD 3OD solution the intramolecular hydrogen bond is broken and the hydroxy and ester groups adopt a different relative disposition, more sterically favourable, decreasing the flattening of the piperidine ring. With regard to the tropane skeleton, these results are in close agreement with those found for compounds VIb and VIc in the crystalline state. The inhibitory effect of the title compounds on 3H-GABA binding to a synaptosomal brain membranes is also reported.

  5. In situ Analysis of Carboxylic and Amino Acids on Mars by Solvent-extraction and Chemical Derivatization Coupled to Gas Chromatography

    NASA Astrophysics Data System (ADS)

    Buch, A.; Sternberg, R.; Meunier, D.; Szopa, C.; Cabane, M.; Raulin, F.; Mahaffy, P.

    2003-05-01

    In situ analysis of carboxylic and amino acids on Mars by solvent-extraction and chemical derivatization coupled to gas chromatography In the frame of the SAM (Sample Analysis at Mars) project (for Mars Science Laboratory, MSL 2009) , we have developed a space instrument sub-system, based on gas chromatography, for the in situ analysis of some of the "key prebiotic" organic molecules expected to be contained in the Martian soil. This analysis is carried out following three steps : extraction of the organic matter from the soil, derivatization of the organic extracted compounds, and GC-MS analysis. To develop this system, samples from the driest and wettest parts of the Atacama desert in Chile (R. Navarro-Gonzalez [1]), currently considered by now as the best analogues of the Martian soil for the exobiological point of view, were used in this study as a reference material. We have first selected and optimized the best solvent for the extraction step of the targeted molecules. Although water is the best solvent for amino acids, it cannot be used since it is an important molecule targeted by several in situ experiments. Moreover water is not appropriate for all the carboxylic acids, especially for derivative benzoic carboxylic acids expected to be present at the Martian surface [2]. For this reason, an alternative solvent was searched by the comparison of the performances of a wide range of solvents. We have thus shown that 2-propanol was the best solvent for the extraction of both family of the targeted compounds. In order to lower the energy consumption and especially the time needed for each analysis, ultrasonic assisted extraction was carried out. Three major parameters of extraction were studied : time of extraction, temperature and volume of solvent contacted with the soil. The results showed that the use of ultrasonication allowed to decrease the extraction time from 24 h (heating in oven at 100 deg C) to 30 min. at room temperature with a significant increase of the extraction yield. Finally the derivatization step procedure, based on silylation reaction [3, 4], was also optimized. The effect of the sonication and the quantity of the derivative reactant on the derivatisation reaction time and yield were also determined. This system was shown to be the most efficient for the detection of the low concentration levels (ppm) amino and carboxylic acids of the Atacama desert samples . It is thus expected to be the most efficient for the in situ analysis of organics in the Martian soil. [1] Navarro-Gonzalez R. et al. Mars like soils in the Atacama desert. Submitted [2] S. A. Benner, K. G. Devine, L.N. Matveeva, D.H. Powel PNAS 97(6) (1998) 2425- 2430 [3] C . Rodier, R. Sternberg, F. Raulin, C. Vidal-Madjar, J. Chromatogr. A 915 (2001) 199. [4] Buch, R. Sternberg, D. Meunier, C. Rodier, C. Laurent, F. Raulin and C. Vidal-Madjar, J. of Chromatogr. A, 999, (1-2), (2003) 165-174

  6. In vitro mutagenesis of Caenorhabditis elegans cuticle collagens identifies a potential subtilisin-like protease cleavage site and demonstrates that carboxyl domain disulfide bonding is required for normal function but not assembly.

    PubMed Central

    Yang, J; Kramer, J M

    1994-01-01

    The importance of conserved amino acids in the amino and carboxyl non-Gly-X-Y domains of Caenorhabditis elegans cuticle collagens was examined by analyzing site-directed mutations of the sqt-1 and rol-6 collagen genes in transgenic animals. Altered collagen genes on transgenic arrays were shown to produce appropriate phenotypes by injecting in vivo cloned mutant alleles. Equivalent alterations in sqt-1 and rol-6 generally produced the same phenotypes, indicating that conserved amino acids in these two collagens have similar functions. Serine substitutions for either of two conserved carboxyl domain cysteines produced LRol phenotypes. Substitution for both cysteines in sqt-1 also resulted in an LRol phenotype, demonstrating that disulfide bonding is important for normal function but not required for assembly. Arg-1 or Arg-4 to Cys mutations in homology block A (HBA; consensus, 1-RXRRQ-5; in the amino non-Gly-X-Y domain) caused RRol phenotypes, while the same alteration at Arg-3 had no effect, indicating that Arg-3 is functionally different from Arg-1 and Arg-4. Substitutions of Arg-4 with Ser, Leu, or Glu also produced the RRol phenotype, while Lys substitutions for Arg-1 or Arg-4 did not generate any abnormal phenotypes. His substitutions for Arg-1 or Arg-4 caused somewhat less severe RRol phenotypes. Therefore, strong positively charged residues, Arg or Lys, are required at positions 1 and 4 for normal function. The conserved pattern of arginines in HBA matches the cleavage sites of the subtilisin-like endoproteinases. HBA may be a cleavage site for a subtilisin-like protease, and cleavage may be important for cuticle collagen processing. PMID:8139571

  7. Functional complementation of truncated human skeletal-muscle chloride channel (hClC-1) using carboxyl tail fragments

    PubMed Central

    Wu, Weiping; Rychkov, Grigori Y.; Hughes, Bernard P.; Bretag, Allan H.

    2005-01-01

    Crystal structures of bacterial CLC (voltage-gated chloride channel family) proteins suggest the arrangement of permeation pores and possible gates in the transmembrane region of eukaryotic CLC channels. For the extensive cytoplasmic tails of eukaryotic CLC family members, however, there are no equivalent structural predictions. Truncations of cytoplasmic tails in different places or point mutations result in loss of function or altered gating of several members of the CLC family, suggesting functional importance. In the present study, we show that deletion of the terminal 100 amino acids (N889X) in human ClC-1 (skeletal-muscle chloride channel) has minor consequences, whereas truncation by 110 or more amino acids (from Q879X) destroys channel function. Use of the split channel strategy, co-injecting mRNAs and expressing various complementary constructs in Xenopus oocytes, confirms the importance of the Gln879–Arg888 sequence. A split between the two CBS (cystathionine ?-synthase) domains (CBS1 and CBS2) gives normal function (e.g. G721X plus its complement), whereas a partial complementation, eliminating the CBS1 domain, eliminates function. Surprisingly, function is retained even when the region Gly721–Ala862 (between CBS1 and CBS2, and including most of the CBS2 domain) is omitted from the complementation. Furthermore, even shorter peptides from the CBS2-immediate post-CBS2 region are sufficient for functional complementation. We have found that just 26 amino acids from Leu863 to Arg888 are necessary since channel function is restored by co-expressing this peptide with the otherwise inactive truncation, G721X. PMID:16321142

  8. Ethyl 7-oxo-7H-benzo[de]imidazo[5,1-a]iso­quinoline-11-carboxyl­ate–tri­fluoro­acetic acid (1/1)

    PubMed Central

    Stibrany, Robert T.; Potenza, Joseph A.

    2013-01-01

    The structure of the title tri­fluoro­acetic acid adduct, C17H12N2O3·C2HF3O2, contains a tri­fluoro­acetic acid mol­ecule hydrogen bonded to the imine N atom of the imidazole ring of a nearly planar four-fused-ring system (r.m.s. deviatiation = 0.013?Å). The carb­oxy­lic acid group of the triflouro­acetic acid mol­ecule is twisted with respect to the mean plane of the four-fused-ring sytem by 75.9?(2)°. A short intra­molecular C—H?O hydrogen bond occurs. In the crystal, the adduct mol­ecules are arranged into stacks along the b axis via ?–? inter­actions between imidazole rings and between imidazole and one of the benzene rings [centroid–centroid distances 3.352?(2) and 3.485?(2)?Å, respectively]. Molecules are linked via C—H?O hydrogen bonds, forming an alternating polymeric head-to-head/tail-to-tail stepped chain approximately along the a-axis direction and tilted on an axis bisecting the b and c axes. PMID:23795131

  9. Application of chemical cytochrome P-450 model systems to studies on drug metabolism--VIII. Novel metabolism of carboxylic acids via oxidative decarboxylation.

    PubMed

    Komuro, M; Higuchi, T; Hirobe, M

    1995-01-01

    The oxidative decarboxylation of carboxylic acids by the chemical cytochrome P-450 model and rat liver microsomal systems was investigated. In the chemical system using meso-tetrakis(pentafluorophenyl)porphyrin iron chloride [Fe(TPFPP)Cl] with iodosylbenzene (PhIO), alpha-arylcarboxylic acids and alpha,alpha,alpha-trisubstituted acetic acids are converted to the corresponding one-carbon-reduced alcohol (I) and carbonyl derivatives (II) via oxidative decarboxylation. These products were then used as standards to identify the metabolites in vivo and in vitro. Biliary excretion of Ia and IIa in bile duct-cannulated rats after oral administration of ketoprofen amounted to 0.22 and 0.03% of the dose, respectively. In the case of indomethacin, Ib and IIb were detected as metabolites in the rat liver microsomal system, in yields of 2.8 and 0.29%, respectively. Further, the yields of Ib and IIb were decreased in the presence of SKF-525A. Thus, these metabolites were formed by cytochrome P-450-dependent reactions. Metabolites Ia, Ib, IIa and IIb had moderate to strong inhibitory activities on arachidonic acid-induced platelet aggregation and cyclooxygenase activity in vitro, comparable to those of the parent compounds. PMID:8612047

  10. Di-heterometalation of thiol-functionalized peptide nucleic acids

    PubMed Central

    Joshi, Tanmaya; Patra, Malay; Spiccia, Leone; Gasser, Gilles

    2013-01-01

    As a proof-of-principle, two hetero-bimetallic PNA oligomers containing a ruthenium(II) polypyridyl and a cyclopentadienyl manganese tricarbonyl complex have been prepared by serial combination of solid-phase peptide coupling and in-solution thiol chemistry. Solid-phase N-terminus attachment of Ru(II)-polypyridyl carboxylic acid derivative, C1, onto the thiol-functionalized PNA backbone (H-a-a-g-t-c-t-g-c-linker-cys-NH2) has been performed by standard peptide coupling method. As two parallel approaches, the strong affinity of thiols for maleimide and haloacetyl group has been exploited for subsequent post-SPPS addition of cymantrene-based organometallic cores, C2 and C3. Michael-like addition and thioether ligation of thiol functionalized PNA1 (H-gly-a-a-g-t-c-t-g-c-linker-cys-NH2) and PNA2 (C1-a-a-g-t-c-t-g-c-linker-cys-NH2) to cymantrene maleimide and chloroacetyl derivatives, C2 and C3, respectively, has been performed. The synthesized ruthenium(II)-cymantrenyl PNA oligomers have been characterized by mass spectrometry (ESI-MS) and IR spectroscopy. The distinct Mn-CO vibrational IR stretches, between 1,924–2,074 cm?1, have been used as markers to confirm the presence of cymantrenyl units in the PNA sequences and the purity of the HPLC-purified PNA thioethers assessed using LC-MS. PMID:23422249

  11. Biosynthesis of Germacrene A Carboxylic Acid in Chicory Roots. Demonstration of a Cytochrome P450 (+)-Germacrene A Hydroxylase and NADP+-Dependent Sesquiterpenoid Dehydrogenase(s) Involved in Sesquiterpene Lactone Biosynthesis

    PubMed Central

    de Kraker, Jan-Willem; Franssen, Maurice C. R.; Dalm, Marcella C. F.; de Groot, Aede; Bouwmeester, Harro J.

    2001-01-01

    Sprouts of chicory (Cichorium intybus), a vegetable grown in the dark, have a slightly bitter taste associated with the presence of guaianolides, eudesmanolides, and germacranolides. The committed step in the biosynthesis of these compounds is catalyzed by a (+)-germacrene A synthase. Formation of the lactone ring is the postulated next step in biosynthesis of the germacrene-derived sesquiterpene lactones. The present study confirms this hypothesis by isolation of enzyme activities from chicory roots that introduce a carboxylic acid function in the germacrene A isopropenyl side chain, which is necessary for lactone ring formation. (+)-Germacrene A is hydroxylated to germacra-1(10),4,11(13)-trien-12-ol by a cytochrome P450 enzyme, and is subsequently oxidized to germacra-1(10),4,11(13)-trien-12-oic acid by NADP+-dependent dehydrogenase(s). Both oxidized germacrenes were detected as their Cope-rearrangement products elema-1,3,11(13)-trien-12-ol and elema-1,3,11(13)-trien-12-oic acid, respectively. The cyclization products of germacra-1(10),4,11(13)-trien-12-ol, i.e. costol, were also observed. The (+)-germacrene A hydroxylase is inhibited by carbon monoxide (blue-light reversible), has an optimum pH at 8.0, and hydroxylates ?-elemene with a modest degree of enantioselectivity. PMID:11299372

  12. 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

  13. Synthesis, Antifungal Activity and Structure-Activity Relationships of Novel 3-(Difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic Acid Amides.

    PubMed

    Du, Shijie; Tian, Zaimin; Yang, Dongyan; Li, Xiuyun; Li, Hong; Jia, Changqing; Che, Chuanliang; Wang, Mian; Qin, Zhaohai

    2015-01-01

    A series of novel 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid amides were synthesized and their activities were tested against seven phytopathogenic fungi by an in vitro mycelia growth inhibition assay. Most of them displayed moderate to excellent activities. Among them N-(2-(5-bromo-1H-indazol-1-yl)phenyl)-3-(difluoro-methyl)-1-methyl-1H-pyrazole-4-carboxamide (9m) exhibited higher antifungal activity against the seven phytopathogenic fungi than boscalid. Topomer CoMFA was employed to develop a three-dimensional quantitative structure-activity relationship model for the compounds. In molecular docking, the carbonyl oxygen atom of 9m could form hydrogen bonds towards the hydroxyl of TYR58 and TRP173 on SDH. PMID:26007171

  14. Synthesis of 3,8,9-trisubstituted-1,7,9-triaza-fluorene-6-carboxylic acid derivatives as a new class of insulin secretagogues.

    PubMed

    Bahekar, Rajesh H; Jain, Mukul R; Jadav, Pradip A; Goel, Ashish; Patel, Dipam N; Prajapati, Vijay M; Gupta, Arun A; Modi, Honey; Patel, Pankaj R

    2007-09-01

    beta-Carbolines stimulate insulin secretion in a glucose-dependent manner, probably by acting on I(3)-binding site. Knowing the in vitro glucose-dependent insulinotropic potential of beta-carbolines, in this project, three series of substituted-triaza-fluorene-6-carboxylic acids (5a-v, 6a-t, and 7a-t) were designed (analogs of beta-carboline) as a new class of insulinotropic agents. The in vitro glucose-dependent insulinotropic activities of test compounds were evaluated using RIN5F assay. Interestingly, with respect to the control, test compounds showed concentration-dependent insulin release, only in presence of glucose load (16.7 mmol). Some of the test compounds from each series were found to be equipotent to standard compound (Harmane), indicating that the pyridine ring systems of substituted-triaza-fluorenes act as bioisosteres of benzene ring in beta-carbolines. PMID:17583514

  15. Comparative bioavailability of two oral formulations of clopidogrel: determination of clopidogrel and its carboxylic acid metabolite (SR26334) under fasting and fed conditions in healthy subjects.

    PubMed

    Brvar, Nina; Lachance, Sylvain; Lévesque, Ann; Breznik, Marjanca; Cvitkovi? Mar?i?, Lea; Merslavi?, Mateja; Grabnar, Iztok; Mateovi?-Rojnik, Tatjana

    2014-03-01

    Two randomized, single dose, 2-period, 2-sequence crossover studies were conducted to evaluate the comparative bioavailability of two clopidogrel formulations under fasting and fed conditions. Assessment of bioequivalence was based upon measurement of plasma concentrations of the parent drug, clopidogrel, and its major (inactive) metabolite, clopidogrel carboxylic acid, using improved methanol-free extraction. Bioequivalence of Krka's formulation to the innovator's formulation was demonstrated under both fasting and fed conditions on 205 volunteers. Confidence intervals for AUC0-t, AUC0-inf and Cmax of clopidogrel and its main metabolite were well within the acceptance range of 80.00 to 125.00 %. Food substantially increased the bioavailability of clopidogrel from both formulations, while no effect of food on the extent and rate of exposure to the metabolite was observed. The effect of food was comparable between the two formulations, as indicated by the same direction and rank of food impact on the bioavailability of both formulations. PMID:24670351

  16. Identification of 11-Nor-delta9-tetrahydrocannabinol-9-carboxylic acid in urine by ion trap GC-MS-MS in the context of doping analysis.

    PubMed

    Caballero, Gerardo M; D'Angelo, Carlos; Fraguío, Mariá Sol; Centurión, Osvaldo Teme

    2004-01-01

    The purpose of this study is to develop a sensitive and specific alternative to current gas chromatography (GC)-mass spectrometry (MS) selected ion monitoring confirmation methods of 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid (cTHC) in human urine samples, in the context of doping analysis. An identification procedure based on the comparison, among suspicious and control samples, of the relative abundances of cTHC selected product ions obtained by GC-tandem MS in an ion trap is presented. The method complies with the identification criteria for qualitative assays established by sports authorities; the comparison procedure is precise, reproducible, specific, and sensitive, thus indicating that it is fit for the purpose of identification accordingly to World Antidoping Agency requirements. PMID:15768841

  17. 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

  18. The Influence of Carboxyl Groups on the Photoluminescence of Mercaptocarboxylic Acid-Stabilized CdTe Nanoparticles

    Microsoft Academic Search

    Hao Zhang; Zhen Zhou; Bai Yang; Mingyuan Gao

    2003-01-01

    The CdTe nanoparticles were prepared in aqueous solution using different mercaptocarboxylic acids such as 3-mercaptopropionic acid (MPA) and thioglycolic acid (TGA) as stabilizing agents following the synthetic route described in ref 9. The pH-dependent photoluminescence (PL) of MPA- and TGA-stabilized CdTe nanoparticles was systematically investigated before and after addition of poly(acrylic acid) (PAA) into the CdTe solutions. Experimental results reveal

  19. Identification of a novel protonation pattern for carboxylic acids upon Q(B) photoreduction in Rhodobacter sphaeroides reaction center mutants at Asp-L213 and Glu-L212 sites.

    PubMed

    Nabedryk, Eliane; Breton, Jacques; Okamura, Melvin Y; Paddock, Mark L

    2004-06-15

    In the reaction center from the photosynthetic purple bacterium Rhodobacter sphaeroides, light energy is rapidly converted to chemical energy through coupled electron-proton transfer to a buried quinone molecule Q(B). Involved in the proton uptake steps are carboxylic acids, which have characteristic infrared vibrations that are observable using light-induced Fourier transform infrared (FTIR) difference spectroscopy. Upon formation, Q(B)(-) induces protonation of Glu-L212, located within 5 A of Q(B), resulting in a IR signal at 1728 cm(-1). However, no other IR signal is observed within the classic absorption range of protonated carboxylic acids (1770-1700 cm(-1)). In particular, no signal for Asp-L213 is found despite its juxtaposition to Q(B) and importance for proton uptake on the second electron-transfer step. In an attempt to uncover the reason behind this lack of signal, the microscopic electrostatic environment in the vicinity of Q(B) was modified by interchanging Asp and Glu at the L213 and L212 positions. The Q(B)(-)/Q(B) FTIR spectrum of the Asp-L212/Glu-L213 swap mutant in the 1770-1700 cm(-1) range shows several distinct new signals, which are sensitive to (1)H/(2)H isotopic exchange, indicating that the reduction of Q(B) results in the change of the protonation state of several carboxylic acids. The new bands at 1752 and 1747 cm(-1) were assigned to an increase of protonation in response to Q(B) reduction of Glu-L213 and Asp-L212, respectively, based on the effect of replacing them with their amine analogues. Since other carboxylic acid signals were observed, it is concluded that the swap mutations at L212 and L213 affect a cluster of carboxylic acids larger than the L212/L213 acid pair. Implications for the native reaction center are discussed. PMID:15182169

  20. Novel 2-oxoimidazolidine-4-carboxylic acid derivatives as Hepatitis C virus NS3-4A serine protease inhibitors: synthesis, activity, and X-ray crystal structure of an enzyme inhibitor complex

    SciTech Connect

    Arasappan, Ashok; Njoroge, F. George; Parekh, Tejal N.; Yang, Xiaozheng; Pichardo, John; Butkiewicz, Nancy; Prongay, Andrew; Yao, Nanhua; Girijavallabhan, Viyyoor (SPRI)

    2008-06-30

    Synthesis and HCV NS3 serine protease inhibitory activity of some novel 2-oxoimidazolidine-4-carboxylic acid derivatives are reported. Inhibitors derived from this new P2 core exhibited activity in the low {micro}M range. X-ray structure of an inhibitor, 15c bound to the protease is presented.

  1. Molecular composition and size distribution of sugars, sugar-alcohols and carboxylic acids in airborne particles during a severe urban haze event caused by wheat straw burning

    NASA Astrophysics Data System (ADS)

    Wang, Gehui; Chen, Chunlei; Li, Jianjun; Zhou, Bianhong; Xie, Mingjie; Hu, Shuyuan; Kawamura, Kimitaka; Chen, Yan

    2011-05-01

    Molecular compositions and size distributions of water-soluble organic compounds (WSOC, i.e., sugars, sugar-alcohols and carboxylic acids) in particles from urban air of Nanjing, China during a severe haze event caused by field burning of wheat straw were characterized and compared with those in the summer and autumn non-haze periods. During the haze event levoglucosan (4030 ng m -3) was the most abundant compound among the measured WSOC, followed by succinic acid, malic acid, glycerol, arabitol and glucose, being different from those in the non-haze samples, in which sucrose or azelaic acid showed a second highest concentration, although levoglucosan was the highest. The measured WSOC in the haze event were 2-20 times more than those in the non-hazy days. Size distribution results showed that there was no significant change in the compound peaks in coarse mode (>2.1 ?m) with respect to the haze and non-haze samples, but a large difference in the fine fraction (<2.1 ?m) was found with a sharp increase during the hazy days mostly due to the increased emissions of wheat straw burning. Molecular compositions of organic compounds in the fresh smoke particles from wheat straw burning demonstrate that sharply increased concentrations of glycerol and succinic and malic acids in the fine particles during the haze event were mainly derived from the field burning of wheat straw, although the sources of glucose and related sugar-alcohols whose concentrations significantly increased in the fine haze samples are unclear. Compared to that in the fresh smoke particles of wheat straw burning an increase in relative abundance of succinic acid to levoglucosan during the haze event suggests a significant production of secondary organic aerosols during transport of the smoke plumes.

  2. Global emission inventories for C4-C14 perfluoroalkyl carboxylic acid (PFCA) homologues from 1951 to 2030, part II: the remaining pieces of the puzzle.

    PubMed

    Wang, Zhanyun; Cousins, Ian T; Scheringer, Martin; Buck, Robert C; Hungerbühler, Konrad

    2014-08-01

    We identify eleven emission sources of perfluoroalkyl carboxylic acids (PFCAs) that have not been discussed in the past. These sources can be divided into three groups: [i] PFCAs released as ingredients or impurities, e.g., historical and current use of perfluorobutanoic acid (PFBA), perfluorohexanoic acid (PFHxA) and their derivatives; [ii] PFCAs formed as degradation products, e.g., atmospheric degradation of some hydrofluorocarbons (HFCs) and hydrofluoroethers (HFEs); and [iii] sources from which PFCAs are released as both impurities and degradation products, e.g., historical and current use of perfluorobutane sulfonyl fluoride (PBSF)- and perfluorohexane sulfonyl fluoride (PHxSF)-based products. Available information confirms that these sources were active in the past or are still active today, but due to a lack of information, it is not yet possible to quantify emissions from these sources. However, our review of the available information on these sources shows that some of the sources may have been significant in the past (e.g., the historical use of PFBA-, PFHxA-, PBSF- and PHxSF-based products), whereas others can be significant in the long-term (e.g., (bio)degradation of various side-chain fluorinated polymers where PFCA precursors are chemically bound to the backbone). In addition, we summarize critical knowledge and data gaps regarding these sources as a basis for future research. PMID:24861268

  3. Construction of an amperometric D-amino acid biosensor based on D-amino acid oxidase/carboxylated mutliwalled carbon nanotube/copper nanoparticles/polyalinine modified gold electrode.

    PubMed

    Lata, Suman; Batra, Bhawna; Kumar, Pankaj; Pundir, C S

    2013-06-01

    An improved D-amino acid biosensor was constructed based on covalent immobilization of D-amino acid oxidase onto carboxylated mutliwalled carbon nanotube/copper nanoparticles/polyalinine hybrid film electrodeposited on gold electrode. The biosensor exhibited an optimal response within 2s at pH 8.0 and 30°C when polarized at 0.09 V. There was a linear relationship between biosensor response (?A) and D-alanine concentration ranging from 0.001 to 0.7 mM. The sensitivity of the biosensor was 54.85 ?A cm(-2) mM(-1) with a lower limit of detection of 0.2 ?M (signal/noise=3). The enzyme electrode was used 150 times over a period of 4 months. The biosensor measured the d-amino acid level in fruit juices. PMID:23399389

  4. Stereoselective Synthesis of cis-2 and trans-2-(Indol-3-yl) Cyclopropyl Amines, Carboxylic Acids, and Esters

    Microsoft Academic Search

    Tilak T. Raj; Maurice R. Eftink

    1998-01-01

    We report a general route for the synthesis of E and Z isomers of indol-3-yl cyclopropyl amines, carboylic acids, and esters. These cyclopropane containing molecules are of interest as conformationally constrained analogues of tryptamine and indole propionic acid, biologically active indoles. The route involves reaction of vinyl indole with ethyl diazoacetate, chromatographic separation of the E and Z stereoisomers of

  5. Supramolecular architectures in the co-crystals involving carboxylic acids and 1,2-bis(4-pyridyl)ethane, an extended bipyridyl type ligand

    NASA Astrophysics Data System (ADS)

    Ebenezer, Samuel; Muthiah, Packianathan Thomas

    2011-03-01

    In the present study 1,2-bis(4-pyridyl)ethane (BPA) crystallizes with 2-chlorobenzoic acid (2CBA), 4-methylbenzoic acid (4MBA), phthalic acid (PA), succinic acid (SA) and adipic acid (AA) to yield co-crystals BPA.2CBA ( 1), BPA.4MBA ( 2), BPA.PA ( 3), BPA.SA ( 4) and BPA.AA ( 5) respectively. All the five co-crystals are constituted by the utilization of the R22(7) synthon, created by the combination of hard N-H⋯O and complementary soft C-H⋯O hydrogen bonds. 1 and 2 illustrate the formation of three component aggregate as in both cases BPA interacts with carboxylic acids to form supramolecular ladder-type assembies. Molecular recognition in co-crystals 3-5 results in the formation of extended infinite tapes and differ further as a consequence of the soft C-H⋯O bonds and stacking interactions. Structure 3 shows the formation of zig-zag tapes while 4 and 5 form linear infinite tapes. Structure 4 shows isostructural behaviour with an analogous structure previously reported (Bowes et al. (2003) [77]).The isostructurality is because of the structural resemblance between both the entities in the co-crystals - fumaric acid/succinic acid and 1,2-bis(4-pyridyl)ethane/1,2-bis(4-pyridyl)ethene. Compound 5 shows good degree of resemblance with another reported analogous structure-1,2-bis(4-pyridyl)ethene adipic acid. (Zhang et al. (2003) [72]). Structure 5 and the reported structure form similar supramolecular sheets through intertape interactions differing from each other only in the alignment of neighboring tapes. The linear tapes in both the cases are linked laterally through different C-H⋯O interactions and ventrally through different stacking interactions. This work illustrates the construction of different supramolecular architectures and the role of weak C-H⋯O hydrogen bonds and stacking interactions in the higher level of supramolecular organization.

  6. An Allele of the Ripening-Specific 1-Aminocyclopropane-1-Carboxylic Acid Synthase Gene (ACS1) in Apple Fruit with a Long Storage Life1

    PubMed Central

    Sunako, Tomomi; Sakuraba, Wakako; Senda, Mineo; Akada, Shinji; Ishikawa, Ryuji; Niizeki, Minoru; Harada, Takeo

    1999-01-01

    An allele of the 1-aminocyclopropane-1-carboxylic acid (ACC) synthase gene (Md-ACS1), the transcript and translated product of which have been identified in ripening apples (Malus domestica), was isolated from a genomic library of the apple cultivar, Golden Delicious. The predicted coding region of this allele (ACS1-2) showed that seven nucleotide substitutions in the corresponding region of ACS1-1 resulted in just one amino acid transition. A 162-bp sequence characterized as a short interspersed repetitive element retrotransposon was inserted in the 5?-flanking region of ACS1-2 corresponding to position ?781 in ACS1-1. The XhoI site located near the 3? end of the predicted coding region of ACS1-2 was absent from the reverse transcriptase-polymerase chain reaction product, revealing that exclusive transcription from ACS1-1 occurs during ripening of cv Golden Delicious fruit. DNA gel-blot and polymerase chain reaction analyses of genomic DNAs showed clearly that apple cultivars were either heterozygous for ACS1-1 and ACS1-2 or homozygous for each type. RNA gel-blot analysis of the ACS1-2 homozygous Fuji apple, which produces little ethylene and has a long storage life, demonstrated that the level of transcription from ACS1-2 during the ripening stage was very low. PMID:10198088

  7. Identification of a Naturally Occurring Inhibitor of the Conversion of 1-Aminocyclopropane-1-Carboxylic Acid to Ethylene by Carnation Microsomes 1

    PubMed Central

    Shih, Ching Yu; Dumbroff, Erwin B.; Thompson, John E.

    1989-01-01

    During cell-free experiments with membranes isolated from carnation petals (Dianthus caryophillus L. cv White Sim), the conversion of 1-aminocyclopropane-1-carboxylic acid into ethylene was blocked by a factor derived from the cytosol. Subsequent characterization of the inhibitor revealed that its effect was concentration dependent, that it was water soluble, and that it could be removed from solution by dialysis and addition of polyvinyl-polypyrrolidone. Activity profiles obtained after solvent partitioning over a range of pH values and after chromatography on silica gel, size exclusion gel, and ion exchange resins revealed that the inhibitor was a highly polar, low molecular weight species that was nonionic at low pH and anionic at pH values above 8. Use of selected solvent systems during paper and thin layer chromatography combined with specific spray reagents tentatively identified the compound as a hydroxycinnamic acid derivative. Base hydrolysis and subsequent comparison with known standards by high performance liquid chromatography, gas-liquid chromatography, and ultraviolet light spectroscopy established that the inhibitor was a conjugate with a ferulic acid moiety. Release of ferulic acid following treatment with ?-glucosidase also indicated the presence of a glucose moiety, and unequivocal identification of the inhibitor as 1-O-feruloyl-?-d-glucose was confirmed by gas chromatography-mass spectroscopy and by ultraviolet light, 1H-, and 13C- nuclear magnetic resonance spectroscopy. Feruloylglucose constituted about 0.1% of the dry weight of stage III (preclimacteric) carnation petals, but concentrations fell sharply during stage IV (climacteric), when ethylene production peaks and the flowers senesce. In a reaction mixture containing microsome-bound ethylene forming enzyme system, 98% of all ethylene production was abolished in the presence of 50 ?m concentrations of the inhibitor. PMID:16666663

  8. Integrating Retinoic Acid Signaling with Brain Function

    ERIC Educational Resources Information Center

    Luo, Tuanlian; Wagner, Elisabeth; Drager, Ursula C.

    2009-01-01

    The vitamin A derivative retinoic acid (RA) regulates the transcription of about a 6th of the human genome. Compelling evidence indicates a role of RA in cognitive activities, but its integration with the molecular mechanisms of higher brain functions is not known. Here we describe the properties of RA signaling in the mouse, which point to…

  9. Free and esterified aliphatic carboxylic acids in humin and humic acids from a peat sample as revealed by pyrolysis with tetramethylammonium hydroxide or tetraethylammonium acetate

    Microsoft Academic Search

    Laurent Grasset; Cédric Guignard; André Amblès

    2002-01-01

    The combination of TMAH thermochemolysis and TEAAc treatment makes it possible to discriminate between the different forms of mono- and dicarboxylic acids present in the structure of humin and humic acids, that is, “free” uncombined acids, methyl or ethyl esters present as tightly trapped molecules within the matrix, or acids chemically linked to the matrix by ester groups. The results

  10. Preparation of L-tryptophan imprinted microspheres based on carboxylic acid functionalized polystyrene.

    PubMed

    Monier, M; Abdel-Latif, D A; Nassef, Hossam M

    2015-05-01

    In this work, polymerizable (4-vinylbenzoyl)-L-tryptophan (VBLT) was synthesized and characterized utilizing, elemental analysis, mass spectra, FTIR, (1)H and (13)CNMR. VBLT was then copolymerized with styrene and divinylbenzene cross-linker using potassium persulfate free radical initiator. The template L-Trp molecules were then leached out from the cross-linked network leaving selective recognition cavities, which are able to selectively rebind with L-Trp than D-Trp. The obtained molecularly imprinted LT-CPS resin was examined using various instrumental techniques such as SEM and FTIR to be then employed in a series of adsorption experiments to evaluate the essential parameters for efficient selective extraction of L-Trp. The kinetics of adsorption displayed the best fit with pseudo-second-order kinetic model, suggesting chemical sorption as the rate determining step. Additionally, the most effective interpretation of the adsorption isotherm data was acquired by Langmuir isotherm, and the maximum adsorption capacities were 155±2 and 82±1 mg/g for L- and D-Trp, respectively. Moreover, chiral resolution of L, D-Trp racemic mixture was performed using column of LT-CPS. PMID:25661777

  11. Studies on the mixed-ligand complexes of copper(II) with gallic acid and pyridine carboxylic acids and their benzologues

    Microsoft Academic Search

    M. S. Abu-Bakr; H. M. Rageh; E. Y. Hashem; M. H. Moustafa

    1994-01-01

    The ternary complex formation of copper(II) with gallic acid (gal) and 2-hydroxy nicotinic acid (hyna), 2-mercapto nicotinic acid (mena), salicylic acid (sa) or thiosalicylic acid (tsa) as a second ligand in a 1:1:1 molar ratio has been investigated in 40% (v\\/v) ethanol using spectrophotometric andpH titration methods. The solution equilibria of the ternary systems have been determined and the stability

  12. A Mononuclear Carboxylate-Rich Oxoiron(IV) Complex: a Structural and Functional Mimic of TauD Intermediate ‘J’

    PubMed Central

    McDonald, Aidan R.; Guo, Yisong; Vu, Van V.; Bominaar, Emile L.; Münck, Eckard; Que, Lawrence

    2012-01-01

    The pentadentate ligand nBu-P2DA (2(b), nBu-P2DA = N-(1?,1?-bis(2-pyridyl)pentyl)iminodiacetate) was designed to bind an iron center in a carboxylate-rich environment similar to that found in the active sites of TauD and other ?-ketoglutarate-dependent mononuclear non-heme iron enzymes. The iron(II) complex nBu4N[FeII(Cl)(nBu-P2DA)] (3(b)-Cl) was synthesized and crystallographically characterized to have a 2-pyridine-2-carboxylate donor set in the plane perpendicular to the Fe-Cl bond. Reaction of 3(b)-Cl with N-heterocyclic amines such as pyridine or imidazole yielded the N-heterocyclic amine adducts [FeII(N)(nBu-P2DA)]. These adducts in turn reacted with oxo-transfer reagents at ?95 °C to afford a short-lived oxoiron(IV) complex [FeIV(O)(nBu-P2DA)] (5(b)) in yields as high as 90% depending on the heterocycle used. Complex 5(b) exhibits near-IR absorption features (?max = 770 nm) and Mossbauer parameters (? = 0.04 mm/s; ?EQ = 1.13 mm/s; D = 27±2 cm?1) characteristic of an S = 1 oxoiron(IV) species. Direct evidence for an Fe=O bond of 1.66 Å was found from EXAFS analysis. DFT calculations on 5(b) in its S =1 spin state afforded a geometry-optimized structure consistent with the EXAFS data. They further demonstrated that the replacement of two pyridine donors in [FeIV(O)(N4Py)]2+ (N4Py = N,N-(bis(2-pyridyl)methyl)N-bis(2-pyridylmethyl)amine) with carboxylate donors in 5(b) decreased the energy gap between the ground S = 1 and the excited S = 2 states, reflecting the weaker equatorial ligand field of 5(b) and accounting for its larger D value. Complex 5(b) reacted readily with dihydrotoluene, methyldiphenylphosphine and ferrocene at ?60 °C, and in all cases was approximately a 5-fold more reactive oxidant than [FeIV(O)(N4Py)]2+. The reactivity differences between these two complexes may arise from a combination of electronic and steric factors. Carboxylate-rich 5(b) represents the closest structural mimic reported thus far of the oxoiron(IV) intermediate (‘J’) found in TauD and provides us with vital insights into the role carboxylate ligands play in modulating the spectroscopic and reactivity properties of the non-heme oxoiron(IV) moiety. PMID:23267430

  13. A water-soluble carboxylic-functionalized chemosensor for detecting Al(3+) in aqueous media and living cells: Experimental and theoretical studies.

    PubMed

    Jun Lee, Jae; Jin Park, Gyeong; Sung Kim, Yong; Young Lee, Sun; Ji Lee, Hyun; Noh, Insup; Kim, Cheal

    2015-07-15

    A new water-soluble carboxylic-functionalized chemosensor 1 was designed and synthesized. 1 exhibited the selective fluorescence enhancement toward aluminum ions with a 1:1 complexation stoichiometry in aqueous solution. The detection limit (24nM) of 1 for Al(3+) is about two order lower than the WHO guideline (7.41?M) for the drinking water. 1 was successfully applied to living cells and real samples for detecting Al(3+). Moreover, the sensing mechanism originated from the inhibited excited-state intramolecular proton transfer (ESIPT) process and the chelation-enhanced fluorescence (CHEF) effect, as supported by theoretical calculations. PMID:25747507

  14. Effects of 5,8-dimethylthieno[2,3-b]quinoline-2-carboxylic acid on the antioxidative defense and lipid membranes in Plasmodium berghei-infected erythrocytes.

    PubMed

    Gamboa de Domínguez, N D; Charris, J; Domínguez, J; Monasterios, M; Angel, J; Rodrigues, J

    2015-08-01

    Plasmodium parasites degrade hemoglobin producing reactive oxygen species as toxic byproducts which are detoxified by a series of antioxidant mechanisms. Quinoline compounds have demonstrated activity against hemoglobin degradation with 5,8-dimethylthieno[2,3-b]quinoline-2-carboxylic acid (TQCA) representing a recent compound inhibiting this process. Thus, this study was undertaken to determine the ability of TQCA to modify the oxidative status in Plasmodium berghei-infected erythrocytes. After hemolysis, activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and dehydrogenase enzymes as well as lipid peroxidation were investigated by spectrophotometry. Saturated and unsaturated fatty acids were determined by gas-liquid chromatography and the in vivo effects of TQCA were confirmed by a malaria murine model (Rane test). The activity of glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) in infected cells was diminished by this compound compared to control infection in 75.1?±?3.5% and 26.5?±?0.3%, respectively, while that of GPx and GR was also lowered (p?<0.05). As an adaptive response we appreciated a 2.3-fold increase of SOD activity compared to control infection. Lipid peroxidation and the saturated/unsaturated fatty acids ratio were also decreased by this quinoline derivate in 49.2?±?1.32% and 37?±?0.06%, respectively, protecting the cells from hemolysis caused by the infection. The in vitro results were in concordance with the potential in vivo activity of this compound in an established malaria murine model in which TQCA showed significant decrease in the parasitemia levels and increased the mean survival days of infected mice. In conclusion, the antioxidant defense represents a biochemical target for TQCA actions as a potent antimalarial whose effects were also confirmed in vivo. PMID:25956945

  15. A TECHNIQUE TO RECOVER TRACER AS CARBOXYL-CARBON AND ALPHA-NITROGEN FROM AMINO ACIDS IN SOIL HYDROLYSATES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Isotope analysis of biochemical compounds provides an unequivocal means for detecting assimilation of tracer C and N into microbial biomass. A diffusion method recently developed to determine amino acid-N by ninhydrin oxidation of soil hydrolysates was modified to permit simultaneous collection of ...

  16. Carboxyl-terminal domain of MUC16 imparts tumorigenic and metastatic functions through nuclear translocation of JAK2 to pancreatic cancer cells

    PubMed Central

    Das, Srustidhar; Lakshmanan, Imayavaramban; Majhi, Prabin D.; Smith, Lynette M.; Wagner, Kay-Uwe; Batra, Surinder K.

    2015-01-01

    MUC16 (CA125) is a type-I transmembrane glycoprotein that is up-regulated in multiple cancers including pancreatic cancer (PC). However, the existence and role of carboxyl-terminal MUC16 generated following its cleavage in PC is unknown. Our previous study using a systematic dual-epitope tagged domain deletion approach of carboxyl-terminal MUC16 has demonstrated the generation of a 17-kDa cleaved MUC16 (MUC16-Cter). Here, we demonstrate the functional significance of MUC16-Cter in PC using the dual-epitope tagged version (N-terminal FLAG- and C-terminal HA-tag) of 114 carboxyl-terminal residues of MUC16 (F114HA). In vitro analyses using F114HA transfected MiaPaCa-2 and T3M4 cells showed enhanced proliferation, motility and increased accumulation of cells in the G2/M phase with apoptosis resistance, a feature associated with cancer stem cells (CSCs). This was supported by enrichment of ALDH+ CSCs along with enhanced drug-resistance. Mechanistically, we demonstrate a novel function of MUC16-Cter that promotes nuclear translocation of JAK2 resulting in phosphorylation of Histone-3 up-regulating stemness-specific genes LMO2 and NANOG. Jak2 dependence was demonstrated using Jak2+/+ and Jak2?/? cells. Using eGFP-Luciferase labeled cells, we demonstrate enhanced tumorigenic and metastatic potential of MUC16-Cter in vivo. Taken together, we demonstrate that MUC16-Cter mediated enrichment of CSCs is partly responsible for tumorigenic, metastatic and drug-resistant properties of PC cells. PMID:25691062

  17. Interfacial activity of acid functionalized single-walled carbon nanotubes (SWCNTs) at the fluid-fluid interface

    NASA Astrophysics Data System (ADS)

    Feng, Tao; Russell, Thomas; Hoagland, David

    2013-03-01

    Interfacial assembly of acid-functionalized single-walled carbon nanotubes at the oil/water interface is achieved by the addition of low molecular weight (MW) amino-terminated polystyrene in the oil phase. The surface activity of carboxylated SWCNTs is strongly influenced by the end-group chemistry and molecular weight of the polystyrene component, the concentrations of this component and the SWCNTs, along with the degree of functionalization of the SWCNTs. The prerequisites for interfacial trapping are amino termini on chains with MW less than 5K and 6 hours or longer incubation of pristine SWCNTs to achieve their carboxylation. Plummets in interfacial tension resembling those for surfactants were observed at critical bulk concentrations of both SWCNTs and PS-NH2. In dried droplets, SWCNTs densely packed with associated PS-NH2 form a bird nest-like interfacial structure, with the SWCNTs preferentially oriented perpendicular to the original interface. Interfacial assembly of acid-functionalized single-walled carbon nanotubes at the oil/water interface is achieved by the addition of low molecular weight (MW) amino-terminated polystyrene in the oil phase. The surface activity of carboxylated SWCNTs is strongly influenced by the end-group chemistry and molecular weight of the polystyrene component, the concentrations of this component and the SWCNTs, along with the degree of functionalization of the SWCNTs. The prerequisites for interfacial trapping are amino termini on chains with MW less than 5K and 6 hours or longer incubation of pristine SWCNTs to achieve their carboxylation. Plummets in interfacial tension resembling those for surfactants were observed at critical bulk concentrations of both SWCNTs and PS-NH2. In dried droplets, SWCNTs densely packed with associated PS-NH2 form a bird nest-like interfacial structure, with the SWCNTs preferentially oriented perpendicular to the original interface. Advisor

  18. XPS analysis of oleylamine/oleic acid capped Fe3O4 nanoparticles as a function of temperature

    NASA Astrophysics Data System (ADS)

    Wilson, D.; Langell, M. A.

    2014-06-01

    Fe3O4 nanoparticles were synthesized solvothermally using oleylamine and oleic acid as surfactants, and the surface composition was determined by X-ray photoelectron spectroscopy (XPS) as a function of temperature, from the as-synthesized nanoparticles to those annealed under vacuum at 883K. XPS of the as-synthesized nanoparticles was consistent with a surface composition of stoichiometric Fe3O4 capped with a mixture of monodentate carboxylate and chemisorbed amine, although the surface was enriched in carboxylate over that present in the synthesis reaction concentration. The method of synthesis and capping surfactants effectively protect the nanoparticle surface from detectable hydroxylation. The capped nanoparticle is stable for 24 h at 373K, and the capping agents persist to 523K, at which point the oleylamine decomposes to desorb nitrogen and deposit aliphatic carbon from the capping tail. The carboxylate decomposes over a wider range and at 883K some carboxylate remains on the surface. The iron oxide nanoparticle undergoes substantial reduction as the aliphatic capping tail decomposes. While the as-introduced nanoparticle is essentially Fe3O4, reduction to FeO, Fe and Fe3C occurs sequentially as the nanoparticle is heated to higher temperatures.

  19. Transport of carboxyl-functionalized carbon black nanoparticles in saturated porous media: Column experiments and model analyses.

    PubMed

    Kang, Jin-Kyu; Yi, In-Geol; Park, Jeong-Ann; Kim, Song-Bae; Kim, Hyunjung; Han, Yosep; Kim, Pil-Je; Eom, Ig-Chun; Jo, Eunhye

    2015-01-01

    The aim of this study was to investigate the transport behavior of carboxyl-functionalized carbon black nanoparticles (CBNPs) in porous media including quartz sand, iron oxide-coated sand (IOCS), and aluminum oxide-coated sand (AOCS). Two sets of column experiments were performed under saturated flow conditions for potassium chloride (KCl), a conservative tracer, and CBNPs. Breakthrough curves were analyzed to obtain mass recovery and one-dimensional transport model parameters. The first set of experiments was conducted to examine the effects of metal (Fe, Al) oxides and flow rate (0.25 and 0.5mLmin(-1)) on the transport of CBNPs suspended in deionized water. The results showed that the mass recovery of CBNPs in quartz sand (flow rate=0.5mLmin(-1)) was 83.1%, whereas no breakthrough of CBNPs (mass recovery=0%) was observed in IOCS and AOCS at the same flow rate, indicating that metal (Fe, Al) oxides can play a significant role in the attachment of CBNPs to porous media. In addition, the mass recovery of CBNPs in quartz sand decreased to 76.1% as the flow rate decreased to 0.25mLmin(-1). Interaction energy profiles for CBNP-porous media were calculated using DLVO theory for sphere-plate geometry, demonstrating that the interaction energy for CBNP-quartz sand was repulsive, whereas the interaction energies for CBNP-IOCS and CBNP-AOCS were attractive with no energy barriers. The second set of experiments was conducted in quartz sand to observe the effect of ionic strength (NaCl=0.1 and 1.0mM; CaCl2=0.01 and 0.1mM) and pH (pH=4.5 and 5.4) on the transport of CBNPs suspended in electrolyte. The results showed that the mass recoveries of CBNPs in NaCl=0.1 and 1.0mM were 65.3 and 6.4%, respectively. The mass recoveries of CBNPs in CaCl2=0.01 and 0.1mM were 81.6 and 6.3%, respectively. These results demonstrated that CBNP attachment to quartz sand can be enhanced by increasing the electrolyte concentration. Interaction energy profiles demonstrated that the interaction energy profile for CBNP-quartz sand was compressed and that the energy barrier decreased as the electrolyte concentration increased. Furthermore, the mass recovery of CBNPs in the presence of divalent ions (CaCl2=0.1mM) was far lower than that in the presence of monovalent ions (NaCl=0.1mM), demonstrating a much stronger effect of Ca(2+) than Na(+) on CBNP transport. Mass recovery of CBNPs at pH4.5 was 55.6%, which was lower than that (83.1%) at pH5.4, indicating that CBNP attachment to quartz sand can be enhanced by decreasing the pH. The sticking efficiencies (?) calculated from the mass recovery by colloid filtration theory were in the range from 2.1×10(-2) to 4.5×10(-1), which were far greater than the values (2.56×10(-6)-3.33×10(-2)) of theoretical sticking efficiencies (?theory) calculated from the DLVO energy by the Maxwell model. PMID:25977994

  20. Significant conductivity enhancement of conductive poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) films through a treatment with organic carboxylic acids and inorganic acids.

    PubMed

    Xia, Yijie; Ouyang, Jianyong

    2010-02-01

    Significant conductivity enhancement was observed on transparent and conductive poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films after a treatment with organic and inorganic acids, including acetic acid, propionic acid, butyric acid, oxalic acid, sulfurous acid, and hydrochloric acid. The conductivity could be enhanced from 0.2 to over 200 S cm(-1), that is, by a factor of more than 1000. The conductivity enhancement was dependent on the structure of the acids and the experimental conditions during the treatment, such as the acid concentration and the temperature. The optimal temperature was in the range of 120 to 160 degrees C. The resistance dropped rapidly when a PEDOT:PSS film was treated with acid solution of high concentration, whereas it gradually increased and then decreased when it was treated with an acid solution of low concentration. The mechanism for this conductivity enhancement was studied by various chemical and physical characterizations. The temperature dependence of conductivity indicates that the energy barrier for charge hopping among the PEDOT chains become lower in the highly conductive PEDOT:PSS film after the acid treatment. The ultraviolet-visible-near-infrared (UV-vis-NIR) absorption spectroscopy, the X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) indicate the loss of polystyrene sulfonic acid (PSSH) chains from the PEDOT:PSS film after the acid treatment, and the atomic force microscopy (AFM) suggest conformational change of the polymer chains. Therefore, the conductivity enhancement is attributed to the loss of PSSH chains from the PEDOT:PSS film and the conformational change of the PEDOT chains, which are induced by the acids. PMID:20356194

  1. Retinoic Acid Signaling in the Functioning Brain

    NSDL National Science Digital Library

    Ursula C. Drager (University of Massachusetts Medical School; Eunice Kennedy Shriver Center REV)

    2006-02-28

    Retinoic acid, an active form of vitamin A, regulates gene expression throughout the body, and many components of the signaling system through which it acts are present in the brain. Very little is known, however, about how retinoic acid functions in neurobiological systems. Several studies have provided evidence that retinoic acid plays a role in sleep, learning, and memory, but the precise mechanisms through which it influences these processes remain unclear. All of these processes involve local or long-range inhibition and synchronized neuronal activity between separate locations in the brain. A critical component in the generation of the synchronized firing of cortical neurons (cortical synchrony) is a network of inhibitory interneurons containing parvalbumin, a cell population affected by retinoid perturbations, such as exposure to a vitamin A overdose. An understanding of the role of retinoids in normal brain function would provide clues to the long-standing question of whether abnormalities in retinoic acid signaling contribute to the pathogenesis of some brain diseases with uncertain etiologies that involve both genetic and environmental factors.

  2. The drastic effect of platinum on carbon-supported ruthenium-tin catalysts used for hydrogenation reactions of carboxylic acids

    Microsoft Academic Search

    Yoshinori Hara; Kouetsu Endou

    2003-01-01

    The incorporation of platinum on bimetallic ruthenium-tin catalysts supported on active carbon has profound effects on the catalytic behavior. The reaction rate was accelerated nearly three times compared with that of the bimetallic system for the hydrogenation of 1,4-cyclohexanedicarboxylic acid (CHDA). Moreover, it turned out that Pt can completely prevent Sn, one component of the catalyst, from dissolving into the

  3. Changes of 1-Aminocyclopropane-1-carboxylic Acid Content in Ripening Fruits in Relation to their Ethylene Production Rates 1

    Microsoft Academic Search

    Neil E. Hoffman; Shang Fa Yang

    1980-01-01

    Changes in the level of 1-amino cyclopropane- Icarboxylic acid (ACC) were compared to ethylene production during fruit ripening of avocado (Persea americana Mill.) banana (Musa sapientum L.) and tomato (Lycopersicon esculentum Mill.). Preclimacteric tissues contained less than 0.1 nmol\\/g of ACC in all tissues. In avocado, the level of ACC increased to 45 nmol\\/g in the later stage of the

  4. Salicylic Acid Influences Net Photosynthetic Rate, Carboxylation Efficiency, Nitrate Reductase Activity, and Seed Yield in Brassica juncea

    Microsoft Academic Search

    Q. Fariduddin; S. Hayat; A. Ahmad

    2003-01-01

    Aqueous solutions of salicylic acid (SA) were applied to the foliage of 30-d-old plants of mustard (Brassica juncea Czern & Coss cv. Varuna). The plants sprayed with the lowest used concentration (10?5 M) of SA were healthier than those sprayed with water only or with higher concentrations of SA (10?4 or 10?3 M). 60-d-old plants possessed 8.4, 9.8, 9.3, 13.0

  5. Advanced dress-up chiral columns: New removable chiral stationary phases for enantioseparation of chiral carboxylic acids.

    PubMed

    Todoroki, Kenichiro; Ishii, Yasuhiro; Ide, Takafumi; Min, Jun Zhe; Inoue, Koichi; Huang, Xin; Zhang, Wei; Hamashima, Yoshitaka; Toyo'oka, Toshimasa

    2015-07-01

    This paper describes the preparation of new dress-up columns featuring reproducibly removable and replaceable chiral stationary phases. After synthesizing perfluroalkylated quinine and quinidine derivatives as chiral stationary phase compounds (F-CSPs), we adsorbed them reversibly onto a fluorous LC column through pumping of their solutions. Using this dress-up chiral column and fluorophobic elution of aqueous ammonium formate/MeOH mixtures, we could enantioseparate four racemic N-acetyl amino acids, dichlorprop, and sixteen fluorescent 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC)-derivatized amino acids. Dressing and undressing of the coated F-CSPs could be controlled by varying the fluorophilicity and fluorophobicity of the eluent. The relative standard deviations of the retention times, the retention factors, the number of theoretical plates, the enantioseparation factors, and the resolutions of each of four preparations of such dress-up columns were all less than or equal to 5.26% (from 20 repeated analyses); the reproducibilities from four different preparations were all less than or equal to 10.6%. These columns also facilitated highly sensitive and selective analyses of AQC-amino acids when detected using LC-MS/MS. PMID:26043097

  6. Visible light-induced decomposition of a fluorotelomer unsaturated carboxylic acid in water with a combination of tungsten trioxide and persulfate.

    PubMed

    Hori, Hisao; Ishiguro, Atsushi; Nakajima, Kohei; Sano, Taizo; Kutsuna, Shuzo; Koike, Kazuhide

    2013-11-01

    Photochemical decomposition of a fluorotelomer unsaturated carboxylic acid, C3F7CFCHCOOH (1), in the presence of WO3 and an electron acceptor (S2O8(2-) or H2O2) in water under visible-light irradiation was investigated. Under an O2 atmosphere, 1 was not decomposed either by TiO2 (P25) or WO3 alone. A combination of WO3 and H2O2 also resulted in almost no decomposition of 1. In contrast, irradiation in the presence of a combination of WO3 and S2O8(2-) (potassium salt) efficiently decomposed 1 to F(-), CO2, C3F7COOH, and C2F5COOH. The decomposition of 1 was affected by the counter cation of S2O8(2-): the decomposition extent was higher with K2S2O8 than with (NH4)2S2O8. The decomposition of 1 was further enhanced when the reaction in the presence of WO3 and K2S2O8 was carried out under an argon atmosphere. Under O2, the amount of H2O2 formed in the reaction solution was an order of magnitude higher than the amount formed under argon. This fact suggests that the decrease in the decomposition of 1 under O2 can be ascribed to the formation of H2O2, which consumed S2O8(2-) and SO4(-). PMID:24112660

  7. Construction of an amperometric TG biosensor based on AuPPy nanocomposite and poly (indole-5-carboxylic acid) modified Au electrode.

    PubMed

    Narang, Jagriti; Chauhan, Nidhi; Rani, Poonam; Pundir, C S

    2013-04-01

    A method is described for construction of an amperometric triglyceride (TG) biosensor based on covalent co-immobilization of lipase, glycerol kinase and glycerol-3-phosphate oxidase onto gold polypyrrole nanocomposite decorated poly indole-5-carboxylic acid electrodeposited on the surface of a gold electrode. The enzyme electrode was characterized by transmission electron microscopy, scanning electron microscopy, electrochemical impedance studies, Fourier transform infrared spectroscopy and cyclic voltammetry. Biosensor showed optimum response within 4 s at pH 6.5 and 35 °C, when polarized at +0.1 V against Ag/AgCl. There was a linear relationship between sensor response and triolein concentration in the range 50-700 mg/dl. Biosensor was employed for determination of TG in serum. Detection limit of the biosensor was 20 mg/dl. Biosensor was evaluated with 91-95 % recovery of added triolein in sera and 4.14 and 5.85 % within and between batch coefficients of variation, respectively. There was a good correlation (r = 0.99) between sera TG values by standard method (Enzymic colorimetric) and the present method. The biosensor was unaffected by a number of serum substances at their physiological concentration. Biosensor lost 50 % of its initial activity after its 100 uses over 7 months, when stored at 4 °C. PMID:22903594

  8. Cr(VI) reduction by an Aspergillus tubingensis strain: role of carboxylic acids and implications for natural attenuation and biotreatment of Cr(VI) contamination.

    PubMed

    Coreño-Alonso, Alejandro; Acevedo-Aguilar, Francisco Javier; Reyna-López, Georgina E; Tomasini, Araceli; Fernández, Francisco J; Wrobel, Katarzyna; Wrobel, Kazimierz; Gutiérrez-Corona, J Félix

    2009-06-01

    Experiments conducted in shake flask cultures, in minimal medium of pH 5.3 containing 50 microg mL(-1)Cr(VI) with glucose as a carbon source, indicated that the biomass of Aspergillus sp. strain Ed8, a chromate-tolerant fungal strain previously isolated from a chromium-polluted soil, responds to the presence of citrate in the medium by increasing the rate of Cr(VI) reduction; this effect required the use of live biomass and was not observed in medium with lactate. Other natural carboxylic acids or non-natural metal chelating agents showed a stimulatory effect of Cr(VI) reduction by Ed8 biomass; salicylate, tartrate and citrate were the stronger stimulators of the specific rate of Cr(VI) reduction, with about 12, 8 and 7-fold stimulatory effects, respectively, as compared to control cultures without additions. A procedure for Cr(VI) removal from a diluted electroplating effluent was devised, based on the use of growth medium amended with citrate or a mixture of salycilate-tartrate and cycles of recharge of growth medium-diluted effluent. In addition, conditions were adjusted in a 2-L bioreactor to reach a 20-fold increase in the volume of the reduction system with no loss of efficiency. Strain Ed8 was identified as an Aspergillus tubingensis isolate (included in Aspergillus niger species complex) on the basis of the ITS1-5.8s rDNA-ITS2 sequence similarity. PMID:19286242

  9. Crystal structure and DFT calculations of 5-(4-Chlorophenyl)-1-(6-methoxypyridazin-3-yl)-1H-pyrazole-3-carboxylic acid

    NASA Astrophysics Data System (ADS)

    Ala?alvar, Can; Soylu, Mustafa Serkan; Ünver, Hüseyin; Ocak ?skeleli, Nazan; Yildiz, Mustafa; Çiftçi, Murat; Bano?lu, Erden

    2014-11-01

    The title compound, 5-(4-Chlorophenyl)-1-(6-methoxypyridazin-3-yl)-1H-pyrazole-3-carboxylic acid, has been characterized by using elemental analysis, MS, FT-IR, 1H NMR and 13C NMR spectroscopic, and crystallographic techniques. The title compound crystallizes in the triclinic space group P-1 with a = 9.612(1), b = 9.894(1), c = 17.380(1) Å, ? = 90.213(5)°, ? = 104.99(1)°, ? = 111.072(5)°, V = 1481.3(2) Å3 and Dx = 1.483 g cm-3 respectively. The structure of the compound has also been examined by using quantum chemical methods. The molecular geometry and vibrational frequencies of monomeric and dimeric form of the title compound in the ground state have been calculated by using the B3LYP/6-31G(d,p) level of the theory. The calculated results show that the optimized geometry and the theoretical vibration frequencies of the dimeric form are good agreement with experimental data. In addition, HOMO-LUMO energy gap, molecular electrostatic potential map, thermodynamic properties of the title compound were performed at B3LYP/6-31G(d,p) level of theory.

  10. A targeted/non-targeted screening method for perfluoroalkyl carboxylic acids and sulfonates in whole fish using quadrupole time-of-flight mass spectrometry and MS(e).

    PubMed

    Crimmins, Bernard S; Xia, Xiaoyan; Hopke, Philip K; Holsen, Thomas M

    2014-02-01

    A new method for measuring perfluoroalkyl contaminants (PFCs) in biological matrices has been developed. An ultra-high pressure liquid chromatograph equipped with a quadrupole time-of-flight mass spectrometer (UPLC-QToF) was optimized using a continuous precursor/product ion monitoring mode. Unlike traditional targeted studies that isolate precursor/product ion pairs, the current method alternates between two ionization energy channels to continuously capture standard electrospray ionization (low energy) and collision induced dissociation (high energy) spectra. The result is the indiscriminant acquisition of paired low and high energy spectra for all constituents eluting from the chromatographic system. This technique was evaluated for the routine analysis of perfluoroalkyl species. Using this technique, linear perfluoroalkyl carboxylic acids (C4 to C14) and perfluoroalkyl sulfonates (C4, C6, C8 and C10) exhibited a linear range spanning over three orders of magnitude and were detectable at levels less than 1 pg on column with a root mean squared signal to noise ratio of 5 to 20. Lake trout (Salvelinus namaycush) and National Institutes of Standards and Technology Standard Reference Material 1946 were used to evaluate matrix effects and the accuracy of this method when applied to a whole fish extract. The current method was also evaluated as a diagnostic tool to identify unknown PFCs using experimental fragmentation patterns, mass defect filtering and Kendrick plots. PMID:24352588

  11. Promotion by Ethylene of the Capability to Convert 1-Aminocyclopropane-1-carboxylic Acid to Ethylene in Preclimacteric Tomato and Cantaloupe Fruits 1

    PubMed Central

    Liu, Yu; Hoffman, Neil E.; Yang, Shang Fa

    1985-01-01

    The intact fruits of preclimacteric tomato (Lycopersicon esculentum Mill) or cantaloupe (Cucumis melo L.) produced very little ethylene and had low capability of converting 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene. When these unripe tomato or cantaloupe fruits were treated with ethylene for 16 hours there was no increase in ACC content or in ethylene production rate, but the tissue's capability to convert ACC to ethylene increased markedly. Such an effect was also observed in fruits of tomato mutants rin and nor, which do not undergo ripening and the climacteric increase in ethylene production during the senescence. The development of this ethylene-forming capability induced by ethylene increased with increasing ethylene concentration (from 0.1 to 100 microliters per liter) and duration (1 to 24 hours); when ethylene was removed this capability remained high for sometime (more than 24 hours). Norbornadiene, a competitive inhibitor of ethylene action, effectively eliminated the promotive effect of ethylene in tomato fruit. These data indicate that the development of the capability to convert ACC to ethylene in preclimacteric tomato and cantaloupe fruits are sensitive to ethylene treatment and that when these fruits are exposed to exogenous ethylene, the increase in ethylene-forming enzyme precedes the increase in ACC synthase. PMID:16664067

  12. Immunopurification and characterization of a 40-kD 1-aminocyclopropane-1-carboxylic acid N-malonyltransferase from mung bean seedling hypocotyls.

    PubMed Central

    Chick, W S; Leung, P C

    1997-01-01

    1-Aminocyclopropane-1-carboxylic acid (ACC) N-malonyltransferase catalyzes the transfer of the malonyl group from malonyl coenzyme A to ACC to form malonyl ACC. Using partially purified ACC N-malonyltransferase from the hypocotyls of mung bean (Vigna radiata) seedlings, we produced two mouse monoclonal antibodies (1H5 and 2G3) to this enzyme. These antibodies bind to sites other than the active site of the enzyme because monoclonal antibody-bound ACC N-malonyltransferase still exhibits full catalytic activity. A monoclonal antibody column was constructed using 1H5 and protein G Sepharose. The ACC N-malonyltransferase purified from this monoclonal antibody column has a molecular mass of 40 kD, which is different from that reported previously. The enzyme has a higher electrophoretic mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the absence of the reducing agent dithiothreitol. The optimum temperature of this 40-kD ACC N-malonyltransferase is 45 degrees C and the apparent Kms for ACC and malonyl coenzyme A are 66.7 and 40 microns, respectively. PMID:9008392

  13. Better rooting procedure to enhance survival rate of field grown malaysian eksotika papaya transformed with 1-aminocyclopropane-1-carboxylic Acid oxidase gene.

    PubMed

    Sekeli, Rogayah; Abdullah, Janna Ong; Namasivayam, Parameswari; Muda, Pauziah; Abu Bakar, Umi Kalsom

    2013-01-01

    A high survival rate for transformed papaya plants when transferred to the field is useful in the quest for improving the commercial quality traits. We report in this paper an improved rooting method for the production of transformed Malaysian Eksotika papaya with high survival rate when transferred to the field. Shoots were regenerated from embryogenic calli transformed with antisense and RNAi constructs of 1-aminocyclopropane-1-carboxylic acid oxidase (ACO) genes using the Agrobacterium tumefaciens-mediated transformation method. Regenerated transformed shoots, each measuring approximately 3-4?cm in height, were cultured in liquid half-strength Murashige and Skoog (MS) medium or sterile distilled water, and with either perlite or vermiculite supplementation. All the culturing processes were conducted either under sterile or nonsterile condition. The results showed that rooting under sterile condition was better. Shoots cultured in half-strength MS medium supplemented with vermiculite exhibited a 92.5% rooting efficiency while perlite showed 77.5%. The survival rate of the vermiculite-grown transformed papaya plantlets after transfer into soil, contained in polybags, was 94%, and the rate after transfer into the ground was 92%. Morpho-histological analyses revealed that the tap roots were more compact, which might have contributed to the high survival rates of the plantlets. PMID:25969786

  14. Pharmacophore Elucidation and Molecular Docking Studies on 5-Phenyl-1-(3-pyridyl)-1H-1,2,4-triazole-3-carboxylic Acid Derivatives as COX-2 Inhibitors

    PubMed Central

    Lindner, Marc; Sippl, Wolfgang; Radwan, Awwad A.

    2010-01-01

    A set of 5-phenyl-1-(3-pyridyl)-1H-1,2,4-triazole-3-carboxylic acid derivatives (16–32) showing anti-inflammatory activity was analyzed using a three-dimensional qualitative structure-selectivity relationship (3D QSSR) method. The CatalystHipHop approach was used to generate a pharmacophore model for cyclooxygenase-2 (COX-2) inhibitors based on a training set of 15 active inhibitors (1–15). The degree of fitting of the test set compounds (16–32) to the generated hypothetical model revealed a qualitative measure of the more or less selective COX-2 inhibition of these compounds. The results indicate that most derivatives (16, 18, 20–25, and 30–32) are able to effectively satisfy the proposed pharmacophore geometry using energy accessible conformers (Econf < 20 kcal/mol). In addition, the triazole derivatives (16–32) were docked into COX-1 and COX-2 X-ray structures, using the program GOLD. Based on the docking results it is suggested that several of these novel triazole derivatives are active COX inhibitors with a significant preference for COX-2. In principle, this work presents an interesting, comprehensive approach to theoretically predict the mode of action of compounds that showed anti-inflammatory activity in an in vivo model. PMID:21179343

  15. Understanding pyrroline-5-carboxylate synthetase deficiency: clinical, molecular, functional, and expression studies, structure-based analysis, and novel therapy with arginine.

    PubMed

    Martinelli, Diego; Häberle, Johannes; Rubio, Vicente; Giunta, Cecilia; Hausser, Ingrid; Carrozzo, Rosalba; Gougeard, Nadine; Marco-Marín, Clara; Goffredo, Bianca M; Meschini, Maria Chiara; Bevivino, Elsa; Boenzi, Sara; Colafati, Giovanna Stefania; Brancati, Francesco; Baumgartner, Matthias R; Dionisi-Vici, Carlo

    2012-09-01

    ?(1)-Pyrroline-5-carboxylate synthetase (P5CS) catalyzes the first two steps of ornithine/proline biosynthesis. P5CS deficiency has been reported in three families, with patients presenting with cutis/joint laxity, cataracts, and neurodevelopmental delay. Only one family exhibited metabolic changes consistent with P5CS deficiency (low proline/ornithine/citrulline/arginine; fasting hyperammonemia). Here we report a new P5CS-deficient patient presenting the complete clinical/metabolic phenotype and carrying p.G93R and p.T299I substitutions in the ?-glutamyl kinase (?GK) component of P5CS. The effects of these substitutions are (1) tested in mutagenesis/functional studies with E.coli ?GK, (2) rationalized by structural modelling, and (3) reflected in decreased P5CS protein in patient fibroblasts (shown by immunofluorescence). Using optical/electron microscopy on skin biopsy, we show collagen/elastin fiber alterations that may contribute to connective tissue laxity and are compatible with our angio-MRI finding of kinky brain vessels in the patient. MR spectroscopy revealed decreased brain creatine, which normalized after sustained arginine supplementation, with improvement of neurodevelopmental and metabolic parameters, suggesting a pathogenic role of brain creatine decrease and the value of arginine therapy. Morphological and functional studies of fibroblast mitochondria show that P5CS deficiency is not associated with the mitochondrial alterations observed in ?(1)-pyrroline-5-carboxylate reductase deficiency (another proline biosynthesis defect presenting cutis laxa and neurological alterations). PMID:22170564

  16. In vitro and in vivo profile of 5-[(4?-trifluoromethyl-biphenyl-2-carbonyl)-amino]-1 H-indole-2-carboxylic acid benzylmethyl carbamoylamide (dirlotapide), a novel potent MTP inhibitor for obesity

    Microsoft Academic Search

    Jin Li; Brian S. Bronk; John P. Dirlam; Alan E. Blize; Peter Bertinato; Burton H. Jaynes; Anne Hickman; Christine Miskell; Usha A. Pillai; Jay S. Tibbitts; Michelle L. Haven; Nicole L. Kolosko; Chris J. Barry; Tara B. Manion

    2007-01-01

    The synthesis of a novel gut selective MTP inhibitor, 5-[(4?-trifluoromethyl-biphenyl-2-carbonyl)-amino]-1H-indole-2-carboxylic acid benzylmethyl carbamoylamide (dirlotapide), and its in vitro and in vivo profile are described. Dirlotapide (3) demonstrated excellent potency against MTP enzyme in HepG2 cells and canine hepatocytes. This novel MTP inhibitor also showed excellent efficacy when tested in a canine food intake model.

  17. In vitro and in vivo profile of 5-[(4'-trifluoromethyl-biphenyl-2-carbonyl)-amino]-1H-indole-2-carboxylic acid benzylmethyl carbamoylamide (dirlotapide), a novel potent MTP inhibitor for obesity.

    PubMed

    Li, Jin; Bronk, Brian S; Dirlam, John P; Blize, Alan E; Bertinato, Peter; Jaynes, Burton H; Hickman, Anne; Miskell, Christine; Pillai, Usha A; Tibbitts, Jay S; Haven, Michelle L; Kolosko, Nicole L; Barry, Chris J; Manion, Tara B

    2007-04-01

    The synthesis of a novel gut selective MTP inhibitor, 5-[(4'-trifluoromethyl-biphenyl-2-carbonyl)-amino]-1H-indole-2-carboxylic acid benzylmethyl carbamoylamide (dirlotapide), and its in vitro and in vivo profile are described. Dirlotapide (3) demonstrated excellent potency against MTP enzyme in HepG2 cells and canine hepatocytes. This novel MTP inhibitor also showed excellent efficacy when tested in a canine food intake model. PMID:17276061

  18. Deduced Amino Acid Sequences Surrounding the Fusion Glycoprotein Cleavage Site and of the Carboxyl-terminus of Haemagglutinin–Neuraminidase Protein of the Avirulent Thermostable Vaccine Strain I-2 of Newcastle disease virus

    Microsoft Academic Search

    P. N. Wambura; J. Meers; J. A. Kattenbelt; A. R. Gould; P. B. Spradbrow

    2007-01-01

    A single-tube RT-PCR technique generated a 387 bp or 300 bp cDNA amplicon covering the F0 cleavage site or the carboxyl (C)-terminus of the HN gene, respectively, of Newcastle disease virus (NDV) strain I-2. Sequence analysis was used to deduce the amino acid sequences of the cleavage site of F protein and the\\u000a C-terminus of HN protein, which were then

  19. Inhibitory effects of tea extracts on the mutagenicity of 1-methyl-1,2,3,4-tetrahydro- ?-carboline-3-carboxylic acid on treatment with nitrite in the presence of ethanol

    Microsoft Academic Search

    M Higashimoto; Y Akada; M Sato; T Kinouchi; T Kuwahara; Y Ohnishi

    2000-01-01

    It has been shown that the mutagenicity of 1-methyl-1,2,3,4-tetrahydro-?-carboline-3-carboxylic acid (MTCCA), a major mutagen precursor in soy sauce on treatment with nitrite and ethanol, was strongly decreased by the addition of hot water extracts of green, black and oolong teas in the reaction mixture when it was treated with 50mm nitrite at pH3.0, 37°C for 60min in the presence of

  20. Solvent Extraction Behavior of Magnesium and Calcium in Versatic Acid-Amine Systems

    Microsoft Academic Search

    Anil K. De; Syamal Ray

    1974-01-01

    Quantitative extraction of calcium and magnesium in high molecular weight carboxylic acid, versatic-9, and amine systems is reported. Butanol was used as diluent. The study includes the extraction behavior as a function of pH by controlled addition of amines, such as monoethanol amine, diethanol amine, and triethanol amine, the effect of diluent, solvent concentration, and different high molecular carboxylic acids