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Sample records for protonated imine carbonyl

  1. Iron-Carbonyl-Catalyzed Redox-Neutral [4+2] Annulation of N-H Imines and Internal Alkynes by C-H Bond Activation.

    PubMed

    Jia, Teng; Zhao, Chongyang; He, Ruoyu; Chen, Hui; Wang, Congyang

    2016-04-18

    Stoichiometric C-H bond activation of arenes mediated by iron carbonyls was reported by Pauson as early as in 1965, yet the catalytic C-H transformations have not been developed. Herein, an iron-catalyzed annulation of N-H imines and internal alkynes to furnish cis-3,4-dihydroisoquinolines is described, and represents the first iron-carbonyl-catalyzed C-H activation reaction of arenes. Remarkablely, this is also the first redox-neutral [4+2] annulation of imines and alkynes proceeding by C-H activation. The reaction also features only cis stereoselectivity and excellent atom economy as neither base, nor external ligand, nor additive is required. Experimental and theoretical studies reveal an oxidative addition mechanism for C-H bond activation to afford a dinuclear ferracycle and a synergetic diiron-promoted H-transfer to the alkyne as the turnover-determining step. PMID:27002210

  2. Method of producing imines

    DOEpatents

    Sithambaram, Shanthakumar; Son, Young-Chan; Suib, Steven L.

    2008-04-08

    A method for forming an imine comprises reacting a first reactant comprising a hydroxyl functionality, a carbonyl functionality, or both a hydroxyl functionality and a carbonyl functionality with a second reactant having an amine functionality in the presence of ordered porous manganese-based octahedral molecular sieves and an oxygen containing gas at a temperature and for a time sufficient for the imine to be produced.

  3. Proton-Coupled Electron Transfer in the Reduction of Carbonyls by Samarium Diiodide-Water Complexes.

    PubMed

    Chciuk, Tesia V; Anderson, William R; Flowers, Robert A

    2016-07-20

    Reduction of carbonyls by SmI2 is significantly impacted by the presence of water, but the fundamental step(s) of initial transfer of a formal hydrogen atom from the SmI2-water reagent system to produce an intermediate radical is not fully understood. In this work, we provide evidence consistent with the reduction of carbonyls by SmI2-water proceeding through proton-coupled electron transfer (PCET). Combined rate and computational studies show that a model aldehyde and ketone are likely reduced through an asynchronous PCET, whereas reduction of a representative lactone occurs through a concerted PCET. In the latter case, concerted PCET is likely a consequence of significantly endergonic initial electron transfer. PMID:27367158

  4. Protonation Sites, Tandem Mass Spectrometry and Computational Calculations of o-Carbonyl Carbazolequinone Derivatives

    PubMed Central

    Martínez-Cifuentes, Maximiliano; Clavijo-Allancan, Graciela; Zuñiga-Hormazabal, Pamela; Aranda, Braulio; Barriga, Andrés; Weiss-López, Boris; Araya-Maturana, Ramiro

    2016-01-01

    A series of a new type of tetracyclic carbazolequinones incorporating a carbonyl group at the ortho position relative to the quinone moiety was synthesized and analyzed by tandem electrospray ionization mass spectrometry (ESI/MS-MS), using Collision-Induced Dissociation (CID) to dissociate the protonated species. Theoretical parameters such as molecular electrostatic potential (MEP), local Fukui functions and local Parr function for electrophilic attack as well as proton affinity (PA) and gas phase basicity (GB), were used to explain the preferred protonation sites. Transition states of some main fragmentation routes were obtained and the energies calculated at density functional theory (DFT) B3LYP level were compared with the obtained by ab initio quadratic configuration interaction with single and double excitation (QCISD). The results are in accordance with the observed distribution of ions. The nature of the substituents in the aromatic ring has a notable impact on the fragmentation routes of the molecules. PMID:27399676

  5. Protonation Sites, Tandem Mass Spectrometry and Computational Calculations of o-Carbonyl Carbazolequinone Derivatives.

    PubMed

    Martínez-Cifuentes, Maximiliano; Clavijo-Allancan, Graciela; Zuñiga-Hormazabal, Pamela; Aranda, Braulio; Barriga, Andrés; Weiss-López, Boris; Araya-Maturana, Ramiro

    2016-01-01

    A series of a new type of tetracyclic carbazolequinones incorporating a carbonyl group at the ortho position relative to the quinone moiety was synthesized and analyzed by tandem electrospray ionization mass spectrometry (ESI/MS-MS), using Collision-Induced Dissociation (CID) to dissociate the protonated species. Theoretical parameters such as molecular electrostatic potential (MEP), local Fukui functions and local Parr function for electrophilic attack as well as proton affinity (PA) and gas phase basicity (GB), were used to explain the preferred protonation sites. Transition states of some main fragmentation routes were obtained and the energies calculated at density functional theory (DFT) B3LYP level were compared with the obtained by ab initio quadratic configuration interaction with single and double excitation (QCISD). The results are in accordance with the observed distribution of ions. The nature of the substituents in the aromatic ring has a notable impact on the fragmentation routes of the molecules. PMID:27399676

  6. Light-Activated Reversible Imine Isomerization: Towards a Photochromic Protein Switch.

    PubMed

    Berbasova, Tetyana; Santos, Elizabeth M; Nosrati, Meisam; Vasileiou, Chrysoula; Geiger, James H; Borhan, Babak

    2016-03-01

    Mutants of cellular retinoic acid-binding protein II (CRABPII), engineered to bind all-trans-retinal as an iminium species, demonstrate photochromism upon irradiation with light at different wavelengths. UV light irradiation populates the cis-imine geometry, which has a high pKa , leading to protonation of the imine and subsequent "turn-on" of color. Yellow light irradiation yields the trans-imine isomer, which has a depressed pKa , leading to loss of color because the imine is not protonated. The protein-bound retinylidene chromophore undergoes photoinduced reversible interconversion between the colored and uncolored species, with excellent fatigue resistance. PMID:26684483

  7. Light-Activated Reversible Imine Isomerization: Towards a Photochromic Protein Switch

    PubMed Central

    Berbasova, Tetyana; Santos, Elizabeth M.; Nosrati, Meisam; Vasileiou, Chrysoula; Geiger, James H.; Borhan, Babak

    2016-01-01

    Mutants of cellular retinoic acid-binding protein II (CRABPII), engineered to bind all-trans-retinal as an iminium species, demonstrate photochromism upon irradiation with light at different wavelengths. UV light irradiation populates the cis-imine geometry, which has a high pKa, leading to protonation of the imine and subsequent “turn-on” of color. Yellow light irradiation yields the trans-imine isomer, which has a depressed pKa, leading to loss of color because the imine is not protonated. The protein-bound retinylidene chromophore undergoes photoinduced reversible interconversion between the colored and uncolored species, with excellent fatigue resistance. PMID:26684483

  8. The bimolecular gas-phase reaction of protonated alkyldipeptides with acetonylacetone

    NASA Astrophysics Data System (ADS)

    Gur, Erez H.; de Koning, L. J.; Nibbering, N. M. M.

    1997-11-01

    The gas-phase reaction of protonated alkyldipeptides with acetonylacetone has been studied in a Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometer. The reaction is identified as the gas-phase analogue of Paal-Knorr pyrrole synthesis. Under thermal conditions, the reaction complex loses a water molecule during a condensation reaction, which couples the dipeptide to the acetonylacetone molecule via an imine bond. Low energy collisional activation of the long-lived imine product ion induces additional loss of a water molecule to form the protonated 2,5-dimethylpyrrole derivative of the dipeptide. Detailed insight into the mechanism is obtained by a comparison of the reactivity of various alkyldipeptides with model compounds with amino functional groups. The reaction is catalysed by the peptide carbonyl groups, which assist in the protonation of the acetonylacetone carbonyl oxygen atoms, making the acetonylacetone carbonyl carbon atoms susceptible to nucleophilic attack by the peptide amino group. From both the previously studied bimolecular hydrogen-deuterium exchange behaviour and the presently studied reaction with acetonylacetone, it follows that the bimolecular reactivity of protonated alkyldipeptides is related to the extent of mobility of the proton within the reactive complex.

  9. Models for incomplete nucleophilic attack on a protonated carbonyl group and electron-deficient alkenes: salts and zwitterions from 1-dimethylamino-naphthalene-8-carbaldehyde.

    PubMed

    Lari, Alberth; Pitak, Matuesz B; Coles, Simon J; Rees, Gregory J; Day, Stephen P; Smith, Mark E; Hanna, John V; Wallis, John D

    2012-10-14

    The X-ray crystal structures of salts and zwitterionic Knoevenagel products from 1-dimethylamino-naphthalene-8-carbaldehyde show long N-C bonds between peri-groups which provide models for incomplete nucleophilic attack on a protonated carbonyl group and electron-deficient alkenes respectively. For the salts the N-C bonds lie in the range 1.625-1.638 Å with C-OH bonds intermediate in length between single and double bonds, while for the zwitterions the N-C bonds lie in the range 1.612-1.660 Å. The structural assignment of the former is supported by solid state (13)C and (15)N NMR studies on doubly isotopically-labelled material. Several zwitterions were converted to naphtha[1,8-bc]azepines by a mechanism involving the tertiary amino effect. PMID:22910881

  10. Fates of imine intermediates in radical cyclizations of N-sulfonylindoles and ene-sulfonamides

    PubMed Central

    Zhang, Hanmo; Hay, E Ben; Geib, Stephen J

    2015-01-01

    Summary Two new fates of imine intermediates formed on radical cyclizations of ene-sulfonamides have been identified, reduction and hydration/fragmentation. Tin hydride-mediated cyclizations of 2-halo-N-(3-methyl-N-sulfonylindole)anilines provide spiro[indoline-3,3'-indolones] or spiro-3,3'-biindolines (derived from imine reduction), depending on the indole C2 substituent. Cyclizations of 2-haloanilide derivatives of 3-carboxy-N-sulfonyl-2,3-dihydropyrroles also presumably form spiro-imines as primary products. However, the lactam carbonyl group facilitates the ring-opening of these cyclic imines by a new pathway of hydration and retro-Claisen-type reaction, providing rearranged 2-(2'-formamidoethyl)oxindoles. PMID:26664585

  11. Ketyl Radical Formation via Proton-Coupled Electron Transfer in an Aqueous Solution versus Hydrogen Atom Transfer in Isopropanol after Photoexcitation of Aromatic Carbonyl Compounds.

    PubMed

    Zhang, Xiting; Ma, Jiani; Li, Songbo; Li, Ming-De; Guan, Xiangguo; Lan, Xin; Zhu, Ruixue; Phillips, David Lee

    2016-07-01

    The excited nπ* and ππ* triplets of two benzophenone (BP) and two anthraquinone (AQ) derivatives have been observed in acetonitrile, isopropanol, and mixed aqueous solutions using time-resolved resonance Raman spectroscopic and nanosecond transient absorption experiments. These experimental results, combined with results from density functional theory calculations, reveal the effects of solvent and substituents on the properties, relative energies, and chemical reactivities of the nπ* and ππ* triplets. The triplet nπ* configuration was found to act as the reactive species for a subsequent hydrogen atom transfer reaction to produce a ketyl radical intermediate in the isopropanol solvent, while the triplet ππ* undergoes a proton-coupled electron transfer (PCET) in aqueous solutions to produce a ketyl radical intermediate. This PCET reaction, which occurs via a concerted proton transfer (to the excited carbonyl group) and electron transfer (to the excited phenyl ring), can account for the experimental observation by several different research groups over the past 40 years of the formation of ketyl radicals after photolysis of a number of BP and AQ derivatives in aqueous solutions, although water is considered to be a relatively "inert" hydrogen-donor solvent. PMID:27266916

  12. Osmotic adaptation of Escherichia coli with a negligible proton motive force in the presence of carbonyl cyanide m-chlorophenylhydrazone.

    PubMed Central

    Ohyama, T; Mugikura, S; Nishikawa, M; Igarashi, K; Kobayashi, H

    1992-01-01

    It has been reported that Escherichia coli is able to grow in the presence of carbonyl cyanide m-chlorophenylhydrazone (CCCP) when ATP is produced by glycolysis (N. Kinoshita et al., J. Bacteriol. 160:1074-1077, 1984). We investigated the effect of CCCP on the osmotic adaptation of E. coli growing with glucose. When E. coli growing in rich medium containing CCCP was transferred to medium containing sucrose, its growth stopped for a while and then started again. This lag time was negligible in the absence of CCCP. The same results were obtained when the osmolarity was increased by N-methylglucamine-maleic acid. In addition to adapting itself to the hyperosmotic rich medium, E. coli adapted itself to hyperosmolarity in a minimal medium containing CCCP, again with a lag time. Hyperosmotic shock decreased the internal level of potassium ion rather than causing the accumulation of external potassium ion in the presence of CCCP. The internal amount of glutamic acid increased in cells growing in hyperosmotic medium in the presence and absence of CCCP. Large elevations in levels of other amino acids were not observed in the cells adapted to hyperosmolarity. Trehalose was detected only in hyperosmosis-stressed cells in the presence and absence of CCCP. These results suggest that E. coli can adapt to changes in the environmental osmolarity with a negligible accumulation of osmolytes from the external milieu but that the accumulation may promote the adaptation. PMID:1314804

  13. Formation of Amides from Imines via Cyanide-Mediated Metal-Free Aerobic Oxidation.

    PubMed

    Seo, Hong-Ahn; Cho, Yeon-Ho; Lee, Ye-Sol; Cheon, Cheol-Hong

    2015-12-18

    A new protocol for the direct formation of amides from imines derived from aromatic aldehydes via metal-free aerobic oxidation in the presence of cyanide is described. This protocol was applicable to various aldimines, and the desired amides were obtained in moderate to good yields. Mechanistic studies suggested that this aerobic oxidative amidation might proceed via the addition of cyanide to imines followed by proton transfer from carbon to nitrogen in the original imines, leading to carbanions of α-amino nitriles, which undergo subsequent oxidation with molecular oxygen in air to provide the desired amide compounds. PMID:26580330

  14. Synthesis of Cyclic Azomethine Imines by Cycloaddition Reactions of N-Isocyanates and N-Isothiocyanates.

    PubMed

    Bongers, Amanda; Ranasinghe, Indee; Lemire, Philippe; Perozzo, Alyssa; Vincent-Rocan, Jean-François; Beauchemin, André M

    2016-08-01

    Various nitrogen-substituted iso(thio)cyanates engage in [3 + 2]-cycloaddition reactions to form azomethine imines containing triazolone, triazole-thione, and pyrazole-thione cores. First, iminoisothiocyanates are shown to undergo aminothiocarbonylation reactions with strained alkenes, and a comparison with recently reported reactions of iminoisocyanates highlights their reduced reactivity. In contrast, amino(thio)carbonylation reactions of imines with iminoisocyanates and iminoisothiocyanates proved more efficient, providing access to triazolone and triazole-thione cores. The dipole products can be converted to valuable heterocyclic cores through simple derivatization reactions. PMID:27458786

  15. Nickel carbonyl

    Integrated Risk Information System (IRIS)

    Nickel carbonyl ; CASRN 13463 - 39 - 3 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  16. Carbonyl sulfide

    Integrated Risk Information System (IRIS)

    Carbonyl sulfide ; CASRN 463 - 58 - 1 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  17. Imine Hydrogels with Tunable Degradability

    PubMed Central

    Boehnke, Natalie; Cam, Cynthia; Bat, Erhan; Segura, Tatiana; Maynard, Heather D.

    2015-01-01

    A shortage of available organ donors has created a need for engineered tissues. In this context, polymer-based hydrogels that break down inside the body are often used as constructs for growth factors and cells. Herein, we report imine cross-linked gels where degradation is controllable by the introduction of mixed imine cross-links. Specifically, hydrazide-functionalized poly(ethylene glycol) (PEG) reacts with aldehyde-functionalized PEG (PEG-CHO) to form hydrazone linked hydrogels that degrade quickly in media. The time to degradation can be controlled by changing the structure of the hydrazide group or by introducing hydroxylamines to form non-reversible oxime linkages. Hydrogels containing adipohydrazide-functionalized PEG (PEG-ADH) and PEG-CHO were found to degrade more rapidly than gels formed from carbodihydrazide-functionalized PEG (PEG-CDH). Incorporating oxime linkages via aminooxy-functionalized PEG (PEG-AO) into the hydrazone cross-linked gels further stabilized the hydrogels. This imine crosslinking approach should be useful for modulating the degradation characteristics of 3D cell culture supports for controlled cell release. PMID:26061010

  18. Antiplasmodial Drugs in the Gas Phase: A CID and DFT Study of Quinolon-4( 1H)-Imine Derivatives

    NASA Astrophysics Data System (ADS)

    Amorim Madeira, Paulo J.; Sitoe, Ana Raquel Fernandes; Gonçalves, Daniel; Rodrigues, Tiago; Guedes, Rita C.; Lopes, Francisca; Moreira, Rui; Bronze, M. Rosário

    2014-09-01

    The gas-phase behavior of 12 quinolon-4( 1H)-imine derivatives with antiplasmodial activity was investigated using electrospray ionization tandem mass spectrometry together with collision induced dissociation and density functional theory (DFT) calculations. The most probable protonation site was predicted by calculating the proton affinity (PA) values for each possible protonation site and it was found to be the imine nitrogen for all compounds under study. Fragmentation pathways of the protonated molecules were proposed and the assignment of product ion structures was performed taking into account theoretical calculations. The nature of the quinoline substituent was found to influence the gas-phase behavior of the compounds under study. The data acquired allowed to bracket the proton affinity of the quinolin-4-imine scaffold, which can be a useful starting point to choose appropriate references for determining PA values of this scaffold.

  19. Catalytic Asymmetric Umpolung Reactions of Imines

    PubMed Central

    Wu, Yongwei; Hu, Lin; Li, Zhe; Deng, Li

    2015-01-01

    Imines, carbon-nitrogen double bonds, are fundamentally important functional groups in organic chemistry. This is largely due to the fact that imines act as electrophiles in C–C bond forming reactions towards carbon nucleophiles, thereby serving one of the most widely used precursors for the formation of amines in both synthetic and biosynthetic settings.1–5 If the carbon atom of the imine could be rendered electron-rich, the imine could react as a nucleophile instead of as an electrophile. Such a reversal in the electronic characteristics of the imine functionality would facilitate the development of new chemical transformations that convert imines into amines via C–C bond forming reactions with carbon electrophiles, thereby creating new opportunities for the efficient synthesis of amines. The development of asymmetric ‘umpolung’ reactions of imines remains an uncharted ground, in spite of the far-reaching impact of such reactions in organic synthesis. Here we report the discovery and development of new chiral phase transfer catalysts that promote the highly efficient asymmetric umpolung reactions of imines and enals. These catalysts mediate the deprotonation of imines and direct the 2-azaallylanions thus formed to react in a highly chemoselective, regioselective, diastereoselective and enantioselective fashion with enals. The reaction tolerates a broad range of imines and enals, and can be carried out in high yield with as little as 0.01 mol % catalyst with a moisture and air-tolerant operational protocol. These umpolung reactions provide a conceptually new and practical approach towards chiral amino compounds. PMID:26201597

  20. Synthesis of an Epoxide Carbonylation Catalyst: Exploration of Contemporary Chemistry for Advanced Undergraduates

    ERIC Educational Resources Information Center

    Getzler, Yutan D. Y. L.; Schmidt, Joseph A. R.; Coates, Geoffrey W.

    2005-01-01

    A class of highly active, well-defined compounds for the catalytic carbonylation of epoxides and aziridines to beta-lactones and beta-lactams are introduced. The synthesis of one of the catalysts involves a simple imine condensation to form the ligand followed by air-sensitive metalation and salt metathesis steps.

  1. A General Method for Imine Formation Using B(OCH2CF3)3.

    PubMed

    Reeves, Jonathan T; Visco, Michael D; Marsini, Maurice A; Grinberg, Nelu; Busacca, Carl A; Mattson, Anita E; Senanayake, Chris H

    2015-05-15

    Tris(2,2,2-trifluoroethyl)borate [B(OCH2CF3)3] was found to be a mild and general reagent for the formation of a variety of imines by condensation of amides or amines with carbonyl compounds. N-Sulfinyl, N-toluenesulfonyl, N-(dimethylamino)sulfamoyl, N-diphenylphosphinoyl, N-(α-methylbenzyl), and N-(4-methoxyphenyl) aldimines are all accessible using this reagent at room temperature. The reactions are operationally simple, and the products are obtained without special workup or isolation procedures. PMID:25906082

  2. An (R)‐Imine Reductase Biocatalyst for the Asymmetric Reduction of Cyclic Imines

    PubMed Central

    Hussain, Shahed; Leipold, Friedemann; Man, Henry; Wells, Elizabeth; France, Scott P.; Mulholland, Keith R.; Grogan, Gideon

    2015-01-01

    Abstract Although the range of biocatalysts available for the synthesis of enantiomerically pure chiral amines continues to expand, few existing methods provide access to secondary amines. To address this shortcoming, we have over‐expressed the gene for an (R)‐imine reductase [(R)‐IRED] from Streptomyces sp. GF3587 in Escherichia coli to create a recombinant whole‐cell biocatalyst for the asymmetric reduction of prochiral imines. The (R)‐IRED was screened against a panel of cyclic imines and two iminium ions and was shown to possess high catalytic activity and enantioselectivity. Preparative‐scale synthesis of the alkaloid (R)‐coniine (90 % yield; 99 % ee) from the imine precursor was performed on a gram‐scale. A homology model of the enzyme active site, based on the structure of a closely related (R)‐IRED from Streptomyces kanamyceticus, was constructed and used to identify potential amino acids as targets for mutagenesis.

  3. Container molecules based on imine type ligands.

    PubMed

    Schulze, A Carina; Oppel, Iris M

    2012-01-01

    This chapter will give a short overview about container molecules, their synthesis and possible applications. The main focus is on those which are based on imine type ligands. These containers can be used for example for guest exchange, gas separation, as chemical sensors or for the stabilisation of white phosphorus under water. The described cages have wide openings or tightly closed ones. For one cage the reversible opening and closing is also described. PMID:22076078

  4. Prosthetic iodination methods for radiolabeling of carbonyl moieties

    SciTech Connect

    Barakat, B.M.A.

    1987-01-01

    The demonstrable need for an indirect, prosthetic-group, radioiodination of carbonyl-containing biomolecules such as ketosteroids, carbohydrates, gangliosides, glycoproteins and aldehydo- and keto-drugs. This need has been addressed by developing a route to iodinated (radioiodination) aryl hydrazides which are subsequently condensed with carbonyl-containing moieties. This dissertation is directed at improving the utility of this reaction and at comparing the hydrolytic stability of the resulting hydrazones to that of similar tyramine imines, a type presently employed in indirect radioiodinations. The aryl carboxylic acid hydrazones were virtually inert to hydrolysis under simulated physiological conditions which caused imine bond rupture. Further improvements to this new prosthetic labeling method were sought in simplifying its two-step, acid-catalyzed cleavage of triazenooxadiazoles (the protected, pre-labeling form of the aryl carboxylic acid hydrazides) to the iodinated hydrazide. Synthetic procedures were explored which might yield non-conjugated aryl oxadiazoles--bearing methylenes inserted between the phenyl and the heterocyclic ring--in the expectation that these substances would be less stable and would hydrolyze in a single-acid-catalyzed step. Four synthetic pathways to amino (or nitro) aryl-methyl oxadiazoles could not be advanced beyond the open-chain precursors of the heterocyclics. Pyrolysis, thermolysis, and catalyzed cyclization reagents could not effect ring closure. A method was developed, however, to an oxadiazolone which can serve as a protective functionality for the iodinated aryl acid hydrazides.

  5. Silyl Ketene Imines: Highly Versatile Nucleophiles for Catalytic, Asymmetric Synthesis

    PubMed Central

    Denmark, Scott E.; Wilson, Tyler W.

    2012-01-01

    This Minireview provides an overview on the development of silyl ketene imines and their recent applications in catalytic, enantioselective reactions. The unique structure of the ketene imine allows a diverse range of reactivity patterns and provides solutions to existing challenges in the enantioselective construction of quaternary stereogenic carbon centers and cross-benzoin adducts. A variety of reactions for which silyl ketene imines have been applied are presented with an overall goal of inspiring new uses for these underutilized nucleophiles. PMID:22968901

  6. Substituent Effects on Electrophilic Catalysis by the Carbonyl Group: Anatomy of the Rate Acceleration for PLP-Catalyzed Deprotonation of Glycine

    PubMed Central

    Crugeiras, Juan; Rios, Ana; Riveiros, Enrique; Richard, John P.

    2011-01-01

    First-order rate constants, determined by 1H NMR, are reported for deuterium exchange between solvent D2O and the α-amino carbon of glycine in the presence of increasing concentrations of carbonyl compounds (acetone, benzaldehyde and salicylaldehyde) and at different pD and buffer concentrations. These rate data were combined with 1H NMR data that define the position of the equilibrium for formation of imines/iminium ions from addition of glycine to the respective carbonyl compounds, to give second-order rate constants kDO for deprotonation of α-imino carbon by DO−. The assumption that these second-order rate constants lie on linear structure-reactivity correlations between log kOL and pKa was made in estimating the following pKas for deprotonation of α-imino carbon: pKa = 22, glycine–acetone iminium ion; pKa = 27, glycine–benzaldehyde imine; pKa ≈ 23, glycine–benzaldehyde iminium ion; and, pKa = 25, glycine–salicylaldehyde iminium ion. The much lower pKa of 17 [Toth, K.; Richard, J. P. J. Am. Chem. Soc. 2007, 129, 3013–3021] for carbon deprotonation of the adduct between 5′-deoxypyridoxal (DPL) and glycine shows that the strongly electron-withdrawing pyridinium ion is unique in driving the extended delocalization of negative charge from the α-iminium to the α-pyridinium carbon. This favors carbanion protonation at the α–pyridinium carbon, and catalysis of the 1,3-aza-allylic isomerization reaction that is a step in enzyme-catalyzed transamination reactions. An analysis of the effect of incremental changes in structure on the activity of benzaldehyde in catalysis of deprotonation of glycine shows the carbonyl group electrophile, the 2-O− ring substituent and the cation pyridinium nitrogen of DPL each make a significant contribution to the catalytic activity of this cofactor analog. The extraordinary activity of DPL in catalysis of deprotonation of α–amino carbon results from the summation of these three smaller effects. PMID:21323335

  7. COATING URANIUM FROM CARBONYLS

    DOEpatents

    Gurinsky, D.H.; Storrs, S.S.

    1959-07-14

    Methods are described for making adherent corrosion resistant coatings on uranium metal. According to the invention, the uranium metal is heated in the presence of an organometallic compound such as the carbonyls of nickel, molybdenum, chromium, niobium, and tungsten at a temperature sufficient to decompose the metal carbonyl and dry plate the resultant free metal on the surface of the uranium metal body. The metal coated body is then further heated at a higher temperature to thermally diffuse the coating metal within the uranium bcdy.

  8. Chemoselective hydrogenation of functionalized nitroarenes and imines by using carbon nanofiber-supported iridium nanoparticles.

    PubMed

    Motoyama, Yukihiro; Taguchi, Masahiro; Desmira, Nelfa; Yoon, Seong-Ho; Mochida, Isao; Nagashima, Hideo

    2014-01-01

    The reaction of three types of carbon nanofibers (CNFs; platelet: CNF-P, tubular: CNF-T, herringbone: CNF-H) with Ir4(CO)12 in mesitylene at 165 °C provided the corresponding CNF-supported iridium nanoparticles, Ir/CNFs (Ir content=2.3-2.6 wt.%). Transmission electron microscopy (TEM) studies of these Ir/CNF samples revealed that size-controlled Ir nanoparticles (average particle size of 1.1-1.5 nm) existed on the CNFs. Among the three Ir/CNF samples, Ir/CNF-T showed an excellent catalytic activity and chemoselectivity towards hydrogenation of functionalized nitroarenes and imines; the corresponding aniline derivatives were obtained with high turnover numbers at ambient temperature under 10 tm of H2 , and the catalyst is reusable. Ir/CNF-T was also effective for the reductive N-alkylation of anilines with carbonyl compounds. PMID:24347068

  9. Similarities and differences between azomethines and ketimines: synthesis, materials characterization and structure of novel imines compounds.

    PubMed

    Iwan, Agnieszka; Kaczmarczyk, Bozena; Janeczek, Henryk; Sek, Danuta; Ostrowski, Slawomir

    2007-04-01

    Imines (ketimines and azomethines) derived from p-dibenzoylbenzene (DB) and terephthalic aldehyde (TA) and two aromatic amines: aniline and 2,6-dimethylaniline have been investigated. Compounds were synthesized via condensation of amines with carbonyl monomers in DMA or amine solution. When using DMA as a solvent, azomethines with high yields were obtained. On the other hand, the amines used as a monomers served also as an effective solvent for the synthesis of the ketanils. This different reactivity of the aldehyde and ketone groups in DMA and in amine depends on the dehydration mechanism being dominated by a kinetic process or thermodynamic one. On the basis of FTIR, 13C and 1H NMR, UV-vis spectra, thermal characteristic and theoretical calculations conclusions are drawn regarding the similarities and differences between azomethines and ketimines. PMID:16872877

  10. Similarities and differences between azomethines and ketimines: Synthesis, materials characterization and structure of novel imines compounds

    NASA Astrophysics Data System (ADS)

    Iwan, Agnieszka; Kaczmarczyk, Bozena; Janeczek, Henryk; Sek, Danuta; Ostrowski, Slawomir

    2007-04-01

    Imines (ketimines and azomethines) derived from p-dibenzoylbenzene (DB) and terephthalic aldehyde (TA) and two aromatic amines: aniline and 2,6-dimethylaniline have been investigated. Compounds were synthesized via condensation of amines with carbonyl monomers in DMA or amine solution. When using DMA as a solvent, azomethines with high yields were obtained. On the other hand, the amines used as a monomers served also as an effective solvent for the synthesis of the ketanils. This different reactivity of the aldehyde and ketone groups in DMA and in amine depends on the dehydration mechanism being dominated by a kinetic process or thermodynamic one. On the basis of FTIR, 13C and 1H NMR, UV-vis spectra, thermal characteristic and theoretical calculations conclusions are drawn regarding the similarities and differences between azomethines and ketimines. ?

  11. Imine-Functionalized Triazatriangulenium Platforms: Towards an Artificial Ciliated Epithelium.

    PubMed

    Hammerich, Melanie; Rusch, Talina; Krekiehn, Nicolai R; Bloedorn, Andreas; Magnussen, Olaf M; Herges, Rainer

    2016-06-17

    Triazatriangulenium (TATA) platforms have been used to prepare highly ordered, self-assembled monolayers of free- and vertically standing imines on Au(111) surfaces. Upon irradiation, the imines undergo trans-cis isomerization and a fast thermal reaction (t1/2 =0.58 s at 20 °C) back to the more stable trans form. It is known that the photochemical reaction proceeds through rotation of the C=N bond and the thermochemical reaction through inversion at the N atom. The imine motors, therefore, should be able to induce a net displacement of particles above the surface similar to cilia epithelia in nature. PMID:27016909

  12. Asymmetric Allylboration of Acyl Imines Catalyzed by Chiral Diols

    PubMed Central

    Lou, Sha; Moquist, Philip N.; Schaus, Scott E.

    2008-01-01

    Chiral BINOL-derived diols catalyze the enantioselective asymmetric allylboration of acyl imines. The reaction requires 15 mol% of (S)-3,3′-Ph2-BINOL as the catalyst and allyldiisopropoxyborane as the nucleophile. The reaction products are obtained in good yields (75 – 94%) and high enantiomeric ratios (95:5 – 99.5:0.5) for aromatic and aliphatic imines. High diastereoselectivities (dr > 98:2) and enantioselectivities (er > 98:2) are obtained in the reactions of acyl imines with crotyldiisopropoxyboranes. This asymmetric transformation is directly applied to the synthesis of maraviroc, the selective CCR5 antagonist with potent activity against HIV-1 infection. Mechanistic investigations of the allylboration reaction including IR, NMR, and mass spectrometry study indicate that acyclic boronates are activated by chiral diols via exchange of one of the boronate alkoxy groups with activation of the acyl imine via hydrogen bonding. PMID:18020334

  13. Vibrational spectra, structure and antioxidant activity of gossypol imine derivatives

    NASA Astrophysics Data System (ADS)

    Ilkevych, N. S.; Schroeder, G.; Rybachenko, V. I.; Chotiy, K. Y.; Makarova, R. A.

    2012-02-01

    The structures and tautomeric equilibria of natural polyphenol gossypol and four its imine derivatives were studied by FT-IR-, NMR-spectroscopy and quantum chemistry methods. It was shown that gossypol Schiff bases exist in solution as enamine-enamine tautomer and hydrazones as imine-imine tautomer. Infrared absorption spectra of studied compounds were simulated using the PM3 method. The fundamental vibrational frequencies were evaluated using various scale factors which yield a good agreement between observed and calculated frequencies. Free radical scavenging activity of gossypol and its imine derivatives was evaluated using DPPH method. Antioxidant activity of studied compounds was characterized. Gossypol hydrazones were shown to be more efficient, while Schiff base to be less efficient as antioxidants in comparison with gossypol itself.

  14. Establishing the kinetic competency of the cationic imine intermediate in nitroalkane oxidase.

    PubMed

    Valley, Michael P; Tichy, Shane E; Fitzpatrick, Paul F

    2005-02-23

    The flavoprotein nitroalkane oxidase catalyzes the oxidation of neutral nitroalkanes to the corresponding aldehydes and ketones. Cyanide inactivates the enzyme during turnover in a concentration-dependent fashion. Mass spectrometry of the flavin from enzyme inactivated by cyanide in the presence of nitroethane or nitrohexane shows that a flavin cyanoethyl or cyanohexyl intermediate has formed. At high concentrations of cyanide, inactivation does not consume oxygen. Rapid reaction studies show that formation of the adduct with 2-(2H2)-nitroethane shows a kinetic isotope effect of 7.9. These results are consistent with cyanide reacting with a species formed after proton abstraction but before flavin oxidation. The proposed mechanism for nitroalkane oxidase involves removal of a proton from the nitroalkane, forming a carbanion which adds to the flavin N(5). Elimination of nitrite from the resulting adduct would form an electrophilic imine which can be attacked by hydroxide. The present results are consistent with cyanide trapping this electrophilic intermediate. PMID:15713081

  15. Naphthalene- and perylenediimides with hydroquinones, catechols, boronic esters and imines in the core.

    PubMed

    Fin, Andrea; Petkova, Irina; Doval, David Alonso; Sakai, Naomi; Vauthey, Eric; Matile, Stefan

    2011-12-21

    The green-fluorescent protein of the jellyfish operates with the most powerful phenolate donors in the push-pull fluorophore. To nevertheless achieve red fluorescence with the same architecture, sea anemone and corals apply oxidative imination, a process that accounts for the chemistry of vision as well. The objective of this study was to apply these lessons from nature to one of the most compact family of panchromatic fluorophores, i.e. core-substituted naphthalenediimides (cNDIs). We report straightforward synthetic access to hydroxylated cNDI and cPDI cores by palladium-catalyzed cleavage of allyloxy substituents. With hydroxylated cNDIs but not cPDIs in water-containing media, excited-state intramolecular proton transfer yields a second bathochromic emission. Deprotonation of hydroquinone, catechol and boronic ester cores provides access to an impressive panchromism up to the NIR frontier at 640 nm. With cNDIs, oxidative imination gives red shifts up to 638 nm, whereas the expanded cPDIs already absorb at 754 nm upon deprotonation of hydroquinone cores. The practical usefulness of hydroquinone cNDIs is exemplified by ratiometric sensing of the purity of DMF with the "naked eye" at a sensitivity far beyond the "naked nose". We conclude that the panchromatic hypersensitivity toward the environment of the new cNDIs is ideal for pattern generation in differential sensing arrays. PMID:21879124

  16. Chemoselective reduction of the carbonyl functionality through hydrosilylation: integrating click catalysis with hydrosilylation in one pot.

    PubMed

    Roy, Sudipta Raha; Sau, Samaresh Chandra; Mandal, Swadhin K

    2014-10-01

    Herein we report the chemoselective reduction of the carbonyl functionality via hydrosilylation using a copper(I) catalyst bearing the abnormal N-heterocyclic carbene 1 with low (0.25 mol %) catalyst loading at ambient temperature in excellent yield within a very short reaction time. The hydrosilylation reaction of α,β-unsaturated carbonyl compounds takes place selectively toward 1,2-addition (C═O) to yield the corresponding allyl alcohols in good yields. Moreover, when two reducible functional groups such as imine and ketone groups are present in the same molecule, this catalyst selectively reduces the ketone functionality. Further, 1 was used in a consecutive fashion by combining the Huisgen cycloaddition and hydrosilylation reactions in one pot, yielding a range of functionalized triazole substituted alcohols in excellent yields. PMID:25188382

  17. Theoretical investigations of the reaction between 1,4-dithiane-2,5-diol and azomethine imines: mechanisms and diastereoselectivity.

    PubMed

    Zheng, Linjie; Qiao, Yan; Lu, Mengxue; Chang, Junbiao

    2015-07-21

    In the present study, mechanistic insights into the domino reaction between 1,4-dithiane-2,5-diol and azomethine imines were derived from the computational study with B3LYP and M06-2X functionals. On the whole, the domino process comprises two consecutive reactions: cleavage of 1,4-dithiane-2,5-diol leading to mercaptoacetaldehyde and [3 + 3] cycloaddition of mercaptoacetaldehyde with azomethine imines. The cleavage of 1,4-dithiane-2,5-diol can take place via multiple possible pathways (1A-1E), and pathway 1E in which double-methanol molecules mediate the proton transfer process is the most energetically favorable, with an energy barrier of 19.9 kcal mol(-1). For the [3 + 3] cycloaddition, three possible pathways (2F-2H) were explored. The calculated energy profiles reveal that pathway 2H with activation energies ranging from 6.9 to 10.2 kcal mol(-1) is more energetically favorable than pathways 2F and 2G. Specifically, pathway 2H comprises three reaction steps: deprotonation of mercaptoacetaldehyde by DABCO allows for the formation of the thiol anion, which subsequently launches a nucleophilic attack on azomethine imines followed by intramolecular cyclization resulting in the final products. The calculated results are in agreement with the experimental observations that the reaction can proceed most efficiently in the presence of both DABCO and methanol. Furthermore, the hydrogen bonding interaction is identified to be the main factor determining the observed diastereoselectivity The current systematic theoretical study gives a full scenario of the reaction between 1,4-dithiane-2,5-diol and azomethine imines catalyzed by DABCO, and thus provides some valuable clues for further investigation and development of this kind of important reaction. PMID:26079432

  18. 49 CFR 173.198 - Nickel carbonyl.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Nickel carbonyl. 173.198 Section 173.198... Nickel carbonyl. (a) Nickel carbonyl must be packed in specification steel or nickel cylinders as prescribed for any compressed gas except acetylene. A cylinder used exclusively for nickel carbonyl may...

  19. 49 CFR 173.198 - Nickel carbonyl.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 2 2013-10-01 2013-10-01 false Nickel carbonyl. 173.198 Section 173.198... Nickel carbonyl. (a) Nickel carbonyl must be packed in specification steel or nickel cylinders as prescribed for any compressed gas except acetylene. A cylinder used exclusively for nickel carbonyl may...

  20. 49 CFR 173.198 - Nickel carbonyl.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Nickel carbonyl. 173.198 Section 173.198... Nickel carbonyl. (a) Nickel carbonyl must be packed in specification steel or nickel cylinders as prescribed for any compressed gas except acetylene. A cylinder used exclusively for nickel carbonyl may...

  1. 49 CFR 173.198 - Nickel carbonyl.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Nickel carbonyl. 173.198 Section 173.198... Nickel carbonyl. (a) Nickel carbonyl must be packed in specification steel or nickel cylinders as prescribed for any compressed gas except acetylene. A cylinder used exclusively for nickel carbonyl may...

  2. 49 CFR 173.198 - Nickel carbonyl.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Nickel carbonyl. 173.198 Section 173.198... Nickel carbonyl. (a) Nickel carbonyl must be packed in specification steel or nickel cylinders as prescribed for any compressed gas except acetylene. A cylinder used exclusively for nickel carbonyl may...

  3. Quantum Chemical Studies of the Substituent Effect on the Reaction of Carbonyl Oxime with Amine.

    PubMed

    Kaya, Yunus

    2016-07-21

    The reaction of the two different substitue carbonyl oximes (isonitrosoacetylnaphthaline, inanH and nitro-isonitrosoacetophenone, ninapH) with two different amines (1-phenylethanol amine, pea, and ethanol amine, ea) was carried out and characterized by elemental analyses, IR, and (1)H and (13)C NMR spectroscopic methods. As a result of these experimental studies, two different levels for all reactions were determined: (I) formation of imine oxime and (II) rearrangement of imine oxime or formation of amido alcohol. After a mechanism was suggested for all of these reactions, the reaction mechanism of carbonyl oxime with amine was first studied by means of the B3LYP/6-311G(d,p) method. Because of the deficiency of density functional theory (DFT) on dispersion effects, the wB97X-D/6-311G(d,p) method, which includes dispersion correction, was used to obtain the reaction heat and free energy barriers to explain why the formation (imine oxime) and unexpected rearrangement products (amido alcohol) occurred or did not occur. The statistical thermodynamic method was used to obtain the changes in thermodynamic properties of the studied molecules between 100 and 500 K. From a kinetic viewpoint, the slowest step of the reactions is the IN1-TS2-IN2 step, which determines the steps of the reaction kinetics. In addition, spectroscopic properties such as vibrational and NMR chemical shifts were studied for all of the molecules. The frontier molecular orbitals (FMOs), highest occupied molecular orbitals (HOMOs), and lowest unoccupied molecular orbitals (LUMOs) were monitored for all of the molecules. PMID:27362286

  4. Stéréochimie de la liaison hydrogène sur le groupe carbonyle

    NASA Astrophysics Data System (ADS)

    Laurence, Christian; Berthelot, Michel; Helbert, Maryvonne

    The asymmetric shape or splitting of the ν(XH) or ν(XD) bands of OH(OD), NH, SH and CH proton donors hydrogen bonded to the carbonyl group of ketones, aldehydes, esters, amides, ureas and carbamates have been explained by the existence of two stereoisomeric complexes: a linear complex (along the axis of the carbonyl bond) and an angular complex (in the direction of a lone pair). Bulky substituents on the carbonyl group or near the XH bond destabilize the angular arrangement. Inductive electron-withdrawing substituents on the carbonyl group favour the linear arrangement.

  5. Secondary brown carbon formation via the dicarbonyl imine pathway: nitrogen heterocycle formation and synergistic effects.

    PubMed

    Kampf, C J; Filippi, A; Zuth, C; Hoffmann, T; Opatz, T

    2016-07-21

    Dicarbonyls are known to be important precursors of so-called atmospheric brown carbon, significantly affecting aerosol optical properties and radiative forcing. In this systematic study we report the formation of light-absorbing nitrogen containing compounds from simple 1,2-, 1,3-, 1,4-, and 1,5-dicarbonyl + amine reactions. A combination of spectrophotometric and mass spectrometric techniques was used to characterize reaction products in solutions mimicking atmospheric particulates. Experiments with individual dicarbonyls and dicarbonyl mixtures in ammonium sulfate and glycine solutions demonstrate that nitrogen heterocycles are common structural motifs of brown carbon chromophores formed in such reaction systems. 1,4- and 1,5-dicarbonyl reaction systems, which were used as surrogates for terpene ozonolysis products, showed rapid formation of light-absorbing material and products with absorbance maxima at ∼450 nm. Synergistic effects on absorbance properties were observed in mixed (di-)carbonyl experiments, as indicated by the formation of a strong absorber in ammonium sulfate solutions containing acetaldehyde and acetylacetone. This cross-reaction oligomer shows an absorbance maximum at 385 nm, relevant for the actinic flux region of the atmosphere. This study demonstrates the complexity of secondary brown carbon formation via the imine pathway and highlights that cross-reactions with synergistic effects have to be considered an important pathway for atmospheric BrC formation. PMID:27334793

  6. Role of the carbonyl group of the (6–4) photoproduct in the (6–4) photolyase reaction†

    PubMed Central

    Yamamoto, Junpei; Hitomi, Kenichi; Hayashi, Ryosuke; Getzoff, Elizabeth D.; Iwai, Shigenori

    2009-01-01

    The (6–4) photoproduct, which is one of the major UV-induced DNA lesions, causes carcinogenesis with high frequency. The (6–4) photolyase is a flavoprotein that can restore this lesion to the original bases, but its repair mechanism has not been elucidated. In this study, we focused on the interaction between the enzyme and the 3’ pyrimidone component of the (6–4) photoproduct, and prepared a substrate analog in which the carbonyl group, a hydrogen-bond acceptor, was replaced with an imine, a hydrogen-bond donor, to investigate the involvement of this carbonyl group in the (6–4) photolyase reaction. UV irradiation of oligodeoxyribonucleotides containing a single thymine–5-methylisocytosine site yielded products with absorption bands at wavelengths longer than 300 nm, similar to those obtained from the conversion of the TT site to the (6–4) photoproduct. The nuclease digestion, MALDI-TOF mass spectrometry, and the instability of the products indicated the formation of the 2-iminopyrimidine-type photoproduct. Analyses of the reaction and the binding of the (6–4) photolyase using these oligonucleotides revealed that this imine analog of the (6–4) photoproduct was not repaired by the (6–4) photolyase, although the enzyme bound to the oligonucleotide with considerable affinity. These results indicate that the carbonyl group of the 3’ pyrimidone ring plays an important role in the (6–4) photolyase reaction. Based on these results, we discuss the repair mechanism. PMID:19715341

  7. Cobalt-Catalyzed Enantioselective Vinylation of Activated Ketones and Imines.

    PubMed

    Huang, Yuan; Huang, Rui-Zhi; Zhao, Yu

    2016-05-25

    We present here an unprecedented cobalt-catalyzed enantioselective vinylation of α-ketoesters, isatins, and imines to deliver a range of synthetically useful allylic alcohols and amines in high enantiopurity. This method employs commercially available and easy to handle catalysts and reagents and exhibits a high degree of practicality. The efficiency, selectivity, and operational simplicity of this catalytic system coupled with the substrate generality render this method a valuable tool in organic synthesis. PMID:27139596

  8. Anion and ion-pair binding by a G-2 poly(ethylene imine) dendrimer.

    PubMed

    Bazzicalupi, Carla; Bianchi, Antonio; Giorgi, Claudia; Gratteri, Paola; Mariani, Palma; Valtancoli, Barbara

    2013-09-14

    The second-generation poly(ethylene imine) dendrimer (L), based on ammonia as the initiating core molecule, forms anion and ion-pair complexes in aqueous solution. Speciation of the complex species formed and determination of the relevant stability constants were performed by means of potentiometric titration in a 0.10 M NMe4Cl solution at 298.1 K. Protonated forms of L interact with NO3(-), SO4(2-), SeO4(2-), HPO4(2-) and H2PO4(-) forming stable 1 : 1 anion complexes. The dendritic structure endows the molecule with a greater anion binding ability relative to analogous linear polyamines. It was previously reported that L forms stable metal complexes. We show here that protonated forms of the mononuclear complexes with Cu(2+), Zn(2+) and Cd(2+) bind these anions, and Pb(2+) complexes bind NO3(-). The resulting ion-pair complexes show considerable stability thanks to the cooperative effect of the oppositely charged partners. Molecular modelling calculations show that both anion-ligand and anion-metal ion interactions can participate in stabilizing such ion-pair complexes. PMID:23538528

  9. Dextran-graft-linear poly(ethylene imine)s for gene delivery: importance of the linking strategy.

    PubMed

    Ochrimenko, Sofia; Vollrath, Antje; Tauhardt, Lutz; Kempe, Kristian; Schubert, Stephanie; Schubert, Ulrich S; Fischer, Dagmar

    2014-11-26

    Low molar mass linear poly(ethylene imine)s (lPEI) were grafted onto dextran via different synthesis routes aiming at the elucidation of structure-property relationships of dextran-graft-linear poly(ethylene imine) (dex-g-lPEI) conjugates for gene delivery applications. Beside the molar mass of well-defined lPEIs and the linker unit, also the amount of lPEI in the polymeric vectors was varied. The synthesized dextran modifications were characterized regarding their chemical structure and showed enhanced complexation and stabilization of DNA against enzymatic degradation. The transfection efficiency of dex-g-lPEIs was increased compared to unmodified lPEI and revealed a dependency of the used linking strategy. All complexes of DNA and dex-g-lPEIs were found to be nontoxic, but the synthesis route showed a strong influence on the aggregation of red blood cells. In conclusion, the linking strategy of lPEI to dextran has a significant impact on the physicochemical characteristics of DNA/polymer complexes, the biocompatibility as well as the transfection efficiency. PMID:25256523

  10. Studies on the interaction of isocyanides with imines: reaction scope and mechanistic variations.

    PubMed

    Ghashghaei, Ouldouz; Manna, Consiglia Annamaria; Vicente-García, Esther; Revés, Marc; Lavilla, Rodolfo

    2014-01-01

    The interaction of imines with isocyanides has been studied. The main product results from a sequential process involving the attack of two units of isocyanide, under Lewis acid catalysis, upon the carbon-nitrogen double bond of the imine to form the 4-membered ring system. The scope of the reaction regarding the imine and isocyanide ranges has been determined, and also some mechanistic variations and structural features have been described. PMID:24454559

  11. Radical perfluoroalkylation - easy access to 2-perfluoroalkylindol-3-imines via electron catalysis.

    PubMed

    Leifert, Dirk; Artiukhin, Denis G; Neugebauer, Johannes; Galstyan, Anzhela; Strassert, Cristian Alejandro; Studer, Armido

    2016-05-21

    Arylisonitriles (2 equivalents) react with alkyl and perfluoroalkyl radicals to form 2-alkylated indole-3-imines via two sequential additions to the isonitrile moiety followed by homolytic aromatic substitution. The three component reaction comprises three C-C bond formations. The endocyclic imine functionality in the products is more reactive in follow up chemistry and hydrolysis of the exocyclic imine leads to 3-oxindoles that show fluorescence properties. PMID:27063553

  12. Studies on the interaction of isocyanides with imines: reaction scope and mechanistic variations

    PubMed Central

    Ghashghaei, Ouldouz; Manna, Consiglia Annamaria; Vicente-García, Esther; Revés, Marc

    2014-01-01

    Summary The interaction of imines with isocyanides has been studied. The main product results from a sequential process involving the attack of two units of isocyanide, under Lewis acid catalysis, upon the carbon–nitrogen double bond of the imine to form the 4-membered ring system. The scope of the reaction regarding the imine and isocyanide ranges has been determined, and also some mechanistic variations and structural features have been described. PMID:24454559

  13. Asymmetric Intramolecular Alkylation of Chiral Aromatic Imines via Catalytic C-H Bond Activation

    SciTech Connect

    Watzke, Anja; Wilson, Rebecca; O'Malley, Steven; Bergman, Robert; Ellman, Jonathan

    2007-04-16

    The asymmetric intramolecular alkylation of chiral aromatic aldimines, in which differentially substituted alkenes are tethered meta to the imine, was investigated. High enantioselectivities were obtained for imines prepared from aminoindane derivatives, which function as directing groups for the rhodium-catalyzed C-H bond activation. Initial demonstration of catalytic asymmetric intramolecular alkylation also was achieved by employing a sterically hindered achiral imine substrate and catalytic amounts of a chiral amine.

  14. Identification of imine reductase-specific sequence motifs.

    PubMed

    Fademrecht, Silvia; Scheller, Philipp N; Nestl, Bettina M; Hauer, Bernhard; Pleiss, Jürgen

    2016-05-01

    Chiral amines are valuable building blocks for the production of a variety of pharmaceuticals, agrochemicals and other specialty chemicals. Only recently, imine reductases (IREDs) were discovered which catalyze the stereoselective reduction of imines to chiral amines. Although several IREDs were biochemically characterized in the last few years, knowledge of the reaction mechanism and the molecular basis of substrate specificity and stereoselectivity is limited. To gain further insights into the sequence-function relationships, the Imine Reductase Engineering Database (www.IRED.BioCatNet.de) was established and a systematic analysis of 530 putative IREDs was performed. A standard numbering scheme based on R-IRED-Sk was introduced to facilitate the identification and communication of structurally equivalent positions in different proteins. A conservation analysis revealed a highly conserved cofactor binding region and a predominantly hydrophobic substrate binding cleft. Two IRED-specific motifs were identified, the cofactor binding motif GLGxMGx5 [ATS]x4 Gx4 [VIL]WNR[TS]x2 [KR] and the active site motif Gx[DE]x[GDA]x[APS]x3 {K}x[ASL]x[LMVIAG]. Our results indicate a preference toward NADPH for all IREDs and explain why, despite their sequence similarity to β-hydroxyacid dehydrogenases (β-HADs), no conversion of β-hydroxyacids has been observed. Superfamily-specific conservations were investigated to explore the molecular basis of their stereopreference. Based on our analysis and previous experimental results on IRED mutants, an exclusive role of standard position 187 for stereoselectivity is excluded. Alternatively, two standard positions 139 and 194 were identified which are superfamily-specifically conserved and differ in R- and S-selective enzymes. Proteins 2016; 84:600-610. © 2016 Wiley Periodicals, Inc. PMID:26857686

  15. Enantioselective Hydrosilylation of Imines Catalyzed by Chiral Zinc Acetate Complexes.

    PubMed

    Bezłada, Agata; Szewczyk, Marcin; Mlynarski, Jacek

    2016-01-01

    A series of zinc acetate complexes with optically pure diphenylethanediamine (DPEDA)-derived ligands have been employed as enantioselective catalyst for the hydrosilylation of various imines. High control of stereoselectivity (up to 97% ee) and excellent yields (up to 96%) were gained for a broad range of N-phosphinoylimines by using (R,R)-N,N'-dibenzyl-1,2-diphenylethane-1,2-diamine. This is the first successful application of an air-stable and environmentally friendly chiral Zn(OAc)2 complex instead of the previously used harmful diethylzinc in the asymmetric reduction of the C═N double bond. PMID:26667387

  16. PROGRESS IN PROCESS INTENSIFICATION: SYNTHESIS OF IMINES USING A SPINNING TUBE-IN-TUBE REACTOR

    EPA Science Inventory

    The high purity, high throughput synthesis of a number of imines (Schiff bases) using a spinning tube-in-tube reactor (STT, Kreido Laboratories, Camarillo, CA) has been carried out. The STT reactor allows the high throughput production of high purity imines from a wide variety of...

  17. Towards a zinc-catalyzed asymmetric hydrogenation/transfer hydrogenation of imines.

    PubMed

    Werkmeister, Svenja; Fleischer, Steffen; Junge, Kathrin; Beller, Matthias

    2012-11-01

    The first asymmetric hydrogenation/transfer hydrogenation of imines to amines using zinc(II) triflate in combination with chiral ligands is described. The monodentate binaphthophosphepine ligand (3 g) provided the highest enantioselectivities. Using different imines, the corresponding amines were obtained in moderate yields and enantioselectivities. PMID:22807402

  18. Vibrational scaling factors for transition metal carbonyls

    NASA Astrophysics Data System (ADS)

    Assefa, M. K.; Devera, J. L.; Brathwaite, A. D.; Mosley, J. D.; Duncan, M. A.

    2015-11-01

    Vibrational frequencies for a selected set of transition metal carbonyl complexes are computed with various forms of density functional theory (B3LYP, BP86, M06, and M06-L), employing several different basis sets. The computed frequencies for the carbonyl stretches are compared to the experimental values obtained from gas phase infrared spectra of isolated neutrals and ions. Recommended carbonyl-stretch scaling factors which are developed vary significantly for different functionals, but there is little variation with basis set. Scaled frequencies compared to experimental spectra for cobalt and tantalum carbonyl cations reveal additional variations in multiplet patterns and relative band intensities for different functionals.

  19. Interresidue carbonyl-carbonyl polarization transfer experiments in uniformly 13C, 15N-labeled peptides and proteins

    NASA Astrophysics Data System (ADS)

    Janik, Rafal; Ritz, Emily; Gravelle, Andrew; Shi, Lichi; Peng, Xiaohu; Ladizhansky, Vladimir

    2010-03-01

    In this work, we demonstrate that Homonuclear Rotary Resonance Recoupling (HORROR) can be used to reintroduce carbonyl-carbonyl interresidue dipolar interactions and to achieve efficient polarization transfer between carbonyl atoms in uniformly 13C, 15N-labeled peptides and proteins. We show that the HORROR condition is anisotropically broadened and overall shifted to higher radio frequency intensities because of the CSA effects. These effects are analyzed theoretically using Average Hamiltonian Theory. At spinning frequencies used in this study, 22 kHz, this broadening is experimentally found to be on the order of a kilohertz at a proton field of 600 MHz. To match HORROR condition over all powder orientations, variable amplitude radio frequency (RF) fields are required, and efficient direct transfers on the order of 20-30% can be straightforwardly established. Two- and three-dimensional chemical shift correlation experiments establishing long-range interresidue connectivities (e.g., (N[i]-CO[i - 2])) are demonstrated on the model peptide N-acetyl-valine-leucine, and on the third immunoglobulin binding domain of protein G. Possible future developments are discussed.

  20. Interresidue carbonyl-carbonyl polarization transfer experiments in uniformly 13C,15N-labeled peptides and proteins.

    PubMed

    Janik, Rafal; Ritz, Emily; Gravelle, Andrew; Shi, Lichi; Peng, Xiaohu; Ladizhansky, Vladimir

    2010-03-01

    In this work, we demonstrate that Homonuclear Rotary Resonance Recoupling (HORROR) can be used to reintroduce carbonyl-carbonyl interresidue dipolar interactions and to achieve efficient polarization transfer between carbonyl atoms in uniformly (13)C,(15)N-labeled peptides and proteins. We show that the HORROR condition is anisotropically broadened and overall shifted to higher radio frequency intensities because of the CSA effects. These effects are analyzed theoretically using Average Hamiltonian Theory. At spinning frequencies used in this study, 22kHz, this broadening is experimentally found to be on the order of a kilohertz at a proton field of 600MHz. To match HORROR condition over all powder orientations, variable amplitude radio frequency (RF) fields are required, and efficient direct transfers on the order of 20-30% can be straightforwardly established. Two- and three-dimensional chemical shift correlation experiments establishing long-range interresidue connectivities (e.g., (N[i]-CO[i-2])) are demonstrated on the model peptide N-acetyl-valine-leucine, and on the third immunoglobulin binding domain of protein G. Possible future developments are discussed. PMID:20060344

  1. Temperature enhancement of photoactivity of N-triphenylmethylsalicylidene imine in solid state

    NASA Astrophysics Data System (ADS)

    Lewanowicz, Aleksandra

    2003-10-01

    Spectral behavior of chromic N-triphenylmethylsalicylidene imine in solid state has been investigated as function of temperature in 300-77 K temperature range. The analysis of the absorption, fluorescence and fluorescence excitation spectra together with the results of microscopic observation has been taken into account in monitoring of changing features. Direct evidence of the keto tautomer (open form) and intermediate formation has been presented, and dynamics of the intramolecular processes have been shortly discussed. The experimental activation energies equal to 5.9 kcal/mol and 9.5 kcal/mol have been extracted from the kinetics of thermally driven changes of luminescence. Those values have been attributed to 540-nm and 510-nm as well as 490-nm emitting species. Besides radiative transition, two main nonradiative deactivation channels, nonradiative transition and photochemical reaction, have been considered in explanation of the thermally enhanced photoactivity of the crystal under study. Contrary to a model anil compound, the photoactivity of studied molecular system with bulky substituent could be realized as dual-type behavior, thermochromic as well as photochromic simultaneously. The changes of the crystal color have been discussed in the frame of the proposed scheme. The scheme represents junction of thermochromic and photochromic behaviors following the proton transfer photochemical reaction acting as the first step of molecular rearrangement.

  2. Increased Adipose Protein Carbonylation in Human Obesity

    PubMed Central

    Frohnert, Brigitte I.; Sinaiko, Alan R.; Serrot, Federico J.; Foncea, Rocio E.; Moran, Antoinette; Ikramuddin, Sayeed; Choudry, Umar; Bernlohr, David A.

    2015-01-01

    Insulin resistance is associated with obesity but mechanisms controlling this relationship in humans are not fully understood. Studies in animal models suggest a linkage between adipose reactive oxygen species (ROS) and insulin resistance. ROS oxidize cellular lipids to produce a variety of lipid hydroperoxides that in turn generate reactive lipid aldehydes that covalently modify cellular proteins in a process termed carbonylation. Mammalian cells defend against reactive lipid aldehydes and protein carbonylation by glutathionylation using glutathione-S-transferase A4 (GSTA4) or carbonyl reduction/oxidation via reductases and/or dehydrogenases. Insulin resistance in mice is linked to ROS production and increased level of protein carbonylation, mitochondrial dysfunction, decreased insulin-stimulated glucose transport, and altered adipokine secretion. To assess protein carbonylation and insulin resistance in humans, eight healthy participants underwent subcutaneous fat biopsy from the periumbilical region for protein analysis and frequently sampled intravenous glucose tolerance testing to measure insulin sensitivity. Soluble proteins from adipose tissue were analyzed using two-dimensional gel electrophoresis and the major carbonylated proteins identified as the adipocyte and epithelial fatty acid–binding proteins. The level of protein carbonylation was directly correlated with adiposity and serum free fatty acids (FFAs). These results suggest that in human obesity oxidative stress is linked to protein carbonylation and such events may contribute to the development of insulin resistance. PMID:21593812

  3. Efficient gene transfection using novel cationic polymers poly(hydroxyalkylene imines).

    PubMed

    Zaliauskiene, Lolita; Bernadisiute, Ula; Vareikis, Ausvydas; Makuska, Ricardas; Volungeviciene, Ieva; Petuskaite, Agne; Riauba, Laurynas; Lagunavicius, Arunas; Zigmantas, Sarunas

    2010-09-15

    A series of novel cationic polymers poly(hydroxyalkylene imines) were synthesized and tested for their ability to transfect cells in vitro and in vivo. Poly(hydroxyalkylene imines), in particular, poly(2-hydroxypropylene imine) (pHP), poly(2-hydroxypropylene imine ethylene imine) (pHPE), and poly(hydroxypropylene imine propylene imine) (pHPP) were synthesized by polycondensation reaction from 1,3-diamino-2-propanol and the appropriate dibromide. Electron microscopic examination demonstrated that the resulting polymers condensed DNA into toroid shape complexes of 100-150 nm in size. Transfection studies showed that all three polymers were able to deliver genetic material into the cell, with pHP being superior to pHPP and pHPE. pHP acted as an efficient gene delivery agent in a variety of different cell lines and outcompeted most of the widely used polymer or lipid based transfection reagents. Intravenous administration of pHP-DNA polyplexes in mice followed by the reporter gene analysis showed that the reagent was suitable for in vivo applications. In summary, the results indicate that pHP is a new efficient reagent for gene delivery in vitro and in vivo. PMID:20695432

  4. Developing a novel catalytic approach for imine formation by using self-replicating catalyst

    NASA Astrophysics Data System (ADS)

    Nasir, Fatin Ilyani; Philp, Douglas; Hasbullah, Siti Aishah; Hassan, Nurul Izzaty

    2015-09-01

    Synthesis of imine compounds usually results in moderate yield due its reversibility characteristic and prone to hydrolysis. Hence, to increase the formation of imine compound, self-replicating catalyst was introduced. The self-replicating catalyst is the imine product itself. The first imine compound, 4-{[4-(3,5-Dimethyl-phenylcarbamoyl)-benzylidene]-amino}-phenyl)-acetic acid has been synthesized from 4-Amino-N-(3,5-dimethyl-phenyl)-benzamide and (4-formyl-phenyl)-acetic acid. Simultaneously, 4-formylbenzoic acid was reacted with thionyl chloride to produce 4-formylbenzoyl chloride, which was then reacted with 2-amino-4,6-dimethylpyridine in the presence of triethylamine to afford N-(4,6-dimethyl-pyridin-2-yl)-4-formyl-benzamide. N-(4,6-dimethyl-pyridin-2-yl)-4-formyl-benzamide formed then reacted with 4-amino-2-methylbenzoic acid to form the second imine derivative, 4-{[4-(4,6-dimethyl-pyridin-2-ylcarbamoyl)-benzylidene]-amino}-2-methyl-benzoic acid. The concentration time profile for the synthesis of self-replicating imine 1 reveals the classic sigmoidal shape characteristics of an autocatalytic process and the rate of the reaction are higher than that observed in the absence of recognition. In order to demonstrate the nature of self-replicating catalyst, a preformed imine 1 was doped into the reaction mixture of amine 1 and the corresponding aldehyde, 4-formylbenzoic acid. The insertion of substoichiometric amounts (15 mol%) of imine 1 at the start of the reaction has accelerated the rate formation of imine 1.

  5. Highly enantioselective trapping of zwitterionic intermediates by imines

    NASA Astrophysics Data System (ADS)

    Qiu, Huang; Li, Ming; Jiang, Li-Qin; Lv, Feng-Ping; Zan, Li; Zhai, Chang-Wei; Doyle, Michael P.; Hu, Wen-Hao

    2012-09-01

    Reactions with the unstable and highly reactive zwitterionic intermediates generated in processes catalysed by transition metals are providing new opportunities for molecular constructions. Insertion reactions involve the collapse of zwitterionic intermediates, but trapping them would allow structural elaborations that are not currently available. To synthesize complex molecules in this manner, reactive electrophiles can be used to trap the zwitterionic intermediates. Here, we describe the use of imines, activated by chiral organocatalysts, and a highly efficient integrated rhodium and chiral Brønsted acid co-catalysed process to trap zwitterionic intermediates that have been proposed previously to undergo a formal C-H insertion reaction, allowing us to obtain polyfunctionalized indole and oxindole derivatives in a single step with excellent diastereoselectivity and enantioselectivity.

  6. Rhodium-Catalyzed Regiodivergent Hydrothiolation of Allyl Amines and Imines.

    PubMed

    Kennemur, Jennifer L; Kortman, Gregory D; Hull, Kami L

    2016-09-14

    The regiodivergent Rh-catalyzed hydrothiolation of allyl amines and imines is presented. Bidentate phosphine ligands with larger natural bite angles (βn ≥ 99°), for example, DPEphos, dpph, or L1, promote a Markovnikov-selective hydrothiolation in up to 88% yield and >20:1 regioselectivity. Conversely, when smaller bite angle ligands (βn ≤ 86°), for example, dppbz or dppp, are employed, the anti-Markovnikov product is formed in up to 74% yield and >20:1 regioselectivity. Initial mechanistic investigations are performed and are consistent with an oxidative addition/olefin insertion/reductive elimination mechanism for each regioisomeric pathway. We hypothesize that the change in regioselectivity is an effect of diverging coordination spheres to favor either Rh-S or Rh-H insertion to form the branched or linear isomer, respectively. PMID:27547858

  7. Surface decorated platinum carbonyl clusters

    NASA Astrophysics Data System (ADS)

    Ciabatti, Iacopo; Femoni, Cristina; Iapalucci, Maria Carmela; Longoni, Giuliano; Zacchini, Stefano; Zarra, Salvatore

    2012-06-01

    Four molecular Pt-carbonyl clusters decorated by Cd-Br fragments, i.e., [Pt13(CO)12{Cd5(μ-Br)5Br2(dmf)3}2]2- (1), [Pt19(CO)17{Cd5(μ-Br)5Br3(Me2CO)2}{Cd5(μ-Br)5Br(Me2CO)4}]2- (2), [H2Pt26(CO)20(CdBr)12]8- (3) and [H4Pt26(CO)20(CdBr)12(PtBr)x]6- (4) (x = 0-2), have been obtained from the reactions between [Pt3n(CO)6n]2- (n = 2-6) and CdBr2.H2O in dmf at 120 °C. The structures of these molecular clusters with diameters of 1.5-2 nm have been determined by X-ray crystallography. Both 1 and 2 are composed of icosahedral or bis-icosahedral Pt-CO cores decorated on the surface by Cd-Br motifs, whereas 3 and 4 display a cubic close packed Pt26Cd12 metal frame decorated by CO and Br ligands. An oversimplified and unifying approach to interpret the electron count of these surface decorated platinum carbonyl clusters is suggested, and extended to other low-valent organometallic clusters and Au-thiolate nanoclusters.Four molecular Pt-carbonyl clusters decorated by Cd-Br fragments, i.e., [Pt13(CO)12{Cd5(μ-Br)5Br2(dmf)3}2]2- (1), [Pt19(CO)17{Cd5(μ-Br)5Br3(Me2CO)2}{Cd5(μ-Br)5Br(Me2CO)4}]2- (2), [H2Pt26(CO)20(CdBr)12]8- (3) and [H4Pt26(CO)20(CdBr)12(PtBr)x]6- (4) (x = 0-2), have been obtained from the reactions between [Pt3n(CO)6n]2- (n = 2-6) and CdBr2.H2O in dmf at 120 °C. The structures of these molecular clusters with diameters of 1.5-2 nm have been determined by X-ray crystallography. Both 1 and 2 are composed of icosahedral or bis-icosahedral Pt-CO cores decorated on the surface by Cd-Br motifs, whereas 3 and 4 display a cubic close packed Pt26Cd12 metal frame decorated by CO and Br ligands. An oversimplified and unifying approach to interpret the electron count of these surface decorated platinum carbonyl clusters is suggested, and extended to other low-valent organometallic clusters and Au-thiolate nanoclusters. CCDC 867747 and 867748. For crystallographic data in CIF or other electronic format see DOI: 10.1039/c2nr30400g

  8. Stereoselective Reduction of Imines with Trichlorosilane Using Solid-Supported Chiral Picolinamides.

    PubMed

    Fernandes, Sílvia D; Porta, Riccardo; Barrulas, Pedro C; Puglisi, Alessandra; Burke, Anthony J; Benaglia, Maurizio

    2016-01-01

    The stereoselective reduction of imines with trichlorosilane catalyzed by chiral Lewis bases is a well-established procedure for the synthesis of enantio-enriched amines. Five supported cinchona-based picolinamides have been prepared and their activity tested in a model reaction. The comparison of different supporting materials revealed that polystyrene gave better results than silica in terms of stereoselectivity. The applicability of the solid-supported catalyst of choice to the reduction of different imines was also demonstrated. Additionally, for the first time, a catalytic reactor containing a polymer-immobilized chiral picolinamide has been employed for the stereoselective reduction of imines with trichlorosilane under continuous flow conditions. PMID:27608000

  9. Synthesis of a γ-lactam library via formal cycloaddition of imines and substituted succinic anhydrides.

    PubMed

    Tan, Darlene Q; Atherton, Amy L; Smith, Austin J; Soldi, Cristian; Hurley, Katherine A; Fettinger, James C; Shaw, Jared T

    2012-03-12

    Formal cycloaddition reactions between imines and cyclic anhydrides serve as starting point for the synthesis of diverse libraries of small molecules. The synthesis of succinic anhydrides substituted with electron-withdrawing groups is facilitated by new mild conditions for alkylation of aryl-substituted acetyl esters with ethyl bromoacetate. These anhydrides are then used in formal cycloaddition reactions with imines to produce γ-lactams. 2-Fluoro-5-nitrophenylsuccinic anhydride reacts efficiently with imines to provide lactams that are further diversified by conversion of the nitro group to either an aniline and an azide for subsequent reactions with acylating agents and alkynes, respectively. The synthesis of cyanosuccinic anhydride is reported for the first time, and the use of this compound in reactions with imines and subsequent functionalization of the resultant lactams is demonstrated. PMID:22225535

  10. Highly-efficient synthesis of covalent porphyrinic cages via DABCO-templated imine condensation reactions.

    PubMed

    Ding, Huimin; Meng, Xiangshi; Cui, Xu; Yang, Yihui; Zhou, Tailin; Wang, Caixing; Zeller, Matthias; Wang, Cheng

    2014-10-01

    We report a new approach to construct covalent porphyrinic cages with different spacer lengths, in which the cage compounds have been conveniently synthesized in quantitative yields, via DABCO-templated imine condensation reactions. PMID:25111246

  11. Asymmetric Transfer Hydrogenation of Imines using Alcohol: Efficiency and Selectivity are Influenced by the Hydrogen Donor.

    PubMed

    Pan, Hui-Jie; Zhang, Yao; Shan, Chunhui; Yu, Zhaoyuan; Lan, Yu; Zhao, Yu

    2016-08-01

    The influence of the alcohol, as the hydrogen donor, on the efficiency and selectivity of the asymmetric transfer hydrogenation (ATH) of imines is reported for the first time. This discovery not only leads to a highly enantioselective access to N-aryl and N-alkyl amines, but also provides new insight into the mechanism of the ATH of imines. Both experimental and computational studies provide support for the reaction pathway involving an iridium alkoxide as the reducing species. PMID:27374880

  12. Nitrile imines: matrix isolation, IR spectra, structures, and rearrangement to carbodiimides.

    PubMed

    Bégué, Didier; Qiao, Greg GuangHua; Wentrup, Curt

    2012-03-21

    The structures and reactivities of nitrile imines are subjects of continuing debate. Several nitrile imines were generated photochemically or thermally and investigated by IR spectroscopy in Ar matrices at cryogenic temperatures (Ph-CNN-H 6, Ph-CNN-CH(3)17, Ph-CNN-SiMe(3)23, Ph-CNN-Ph 29, Ph(3)C-CNN-CPh(3)34, and the boryl-CNN-boryl derivative 39). The effect of substituents on the structures and IR absorptions of nitrile imines was investigated computationally at the B3LYP/6-31G* level. IR spectra were analyzed in terms of calculated anharmonic vibrational spectra and were generally in very good agreement with the calculated spectra. Infrared spectra were found to reflect the structures of nitrile imines accurately. Nitrile imines with IR absorptions above 2200 cm(-1) have essentially propargylic structures, possessing a CN triple bond (typically PhCNNSiMe(3)23, PhCNNPh 29, and boryl-CNN-boryl 39). Nitrile imines with IR absorptions below ca. 2200 cm(-1) are more likely to be allenic (e.g., HCNNH 1, PhCNNH 6, HCNNPh 43, PhCNNCH(3)17, and Ph(3)C-CNN-CPh(3)34). All nitrile imines isomerize to the corresponding carbodiimides both thermally and photochemically. Monosubstituted carbodiimides isomerize thermally to the corresponding cyanamides (e.g., Ph-N═C═N-H 5 → Ph-NH-CN 8), which are therefore the thermal end products for nitrile imines of the types RCNNH and HCNNR. This tautomerization is reversible under flash vacuum thermolysis conditions. PMID:22364289

  13. Hydrogenation of imines catalyzed by trisphosphine-substituted molybdenum and tungsten nitrosyl hydrides and co-catalytic acid.

    PubMed

    Chakraborty, Subrata; Blacque, Olivier; Fox, Thomas; Berke, Heinz

    2014-10-01

    Hydride complexes Mo,W(CO)(NO)H(mer-etp(i)p) (iPr2PCH2CH2)2PPh=etp(i)p) (2 a,b(syn), syn and anti of NO and Ph(etp(i)p) orientions) were prepared and probed in imine hydrogenations together with co-catalytic [H(Et2O)2][B(C6F5)4] (140 °C, 60 bar H2). 2 a,b(syn) were obtained via reduction of syn/anti-Mo,W(NO)Cl3(mer-etp(i)p) and syn,anti-Mo,W(NO)(CO)Cl(mer-etp(i)p). [H(Et2O)2][B(C6F5)4] in THF converted the hydrides into THF complexes syn-[Mo,W(NO)(CO)(etp(i)p)(THF)][B(C6F5)4]. Combinations of the p-substituents of aryl imines p-R(1)C6H4CH=N-p-C6H4R(2) (R(1),R(2)=H,F,Cl,OMe,α-Np) were hydrogenated to amines (maximum initial TOFs of 1960 h(-1) (2 a(syn)) and 740 h(-1) (2 b(syn)) for N-(4-methoxybenzylidene)aniline). An 'ionic hydrogenation' mechanism based on linear Hammett plots (ρ=-10.5, p-substitution on the C-side and ρ=0.86, p-substitution on the N-side), iminium intermediates, linear P(H2) dependence, and DKIE=1.38 is proposed. Heterolytic splitting of H2 followed by 'proton before hydride' transfers are the steps in the ionic mechanism where H2 ligand addition is rate limiting. PMID:25048293

  14. Visible light induced green transformation of primary amines to imines using a silicate supported anatase photocatalyst.

    PubMed

    Zavahir, Sifani; Zhu, Huaiyong

    2015-01-01

    Catalytic oxidation of amine to imine is of intense present interest since imines are important intermediates for the synthesis of fine chemicals, pharmaceuticals, and agricultural chemicals. However, considerable efforts have been made to develop efficient methods for the oxidation of secondary amines to imines, while little attention has until recently been given to the oxidation of primary amines, presumably owing to the high reactivity of generated imines of primary amines that are easily dehydrogenated to nitriles. Herein, we report the oxidative coupling of a series of primary benzylic amines into corresponding imines with dioxygen as the benign oxidant over composite catalysts of TiO2 (anatase)-silicate under visible light irradiation of λ > 460 nm. Visible light response of this system is believed to be as a result of high population of defects and contacts between silicate and anatase crystals in the composite and the strong interaction between benzylic amine and the catalyst. It is found that tuning the intensity and wavelength of the light irradiation and the reaction temperature can remarkably enhance the reaction activity. Water can also act as a green medium for the reaction with an excellent selectivity. This report contributes to the use of readily synthesized, environmentally benign, TiO2 based composite photocatalyst and solar energy to realize the transformation of primary amines to imine compounds. PMID:25629455

  15. Protein Carbonylation and Adipocyte Mitochondrial Function*

    PubMed Central

    Curtis, Jessica M.; Hahn, Wendy S.; Stone, Matthew D.; Inda, Jacob J.; Droullard, David J.; Kuzmicic, Jovan P.; Donoghue, Margaret A.; Long, Eric K.; Armien, Anibal G.; Lavandero, Sergio; Arriaga, Edgar; Griffin, Timothy J.; Bernlohr, David A.

    2012-01-01

    Carbonylation is the covalent, non-reversible modification of the side chains of cysteine, histidine, and lysine residues by lipid peroxidation end products such as 4-hydroxy- and 4-oxononenal. In adipose tissue the effects of such modifications are associated with increased oxidative stress and metabolic dysregulation centered on mitochondrial energy metabolism. To address the role of protein carbonylation in the pathogenesis of mitochondrial dysfunction, quantitative proteomics was employed to identify specific targets of carbonylation in GSTA4-silenced or overexpressing 3T3-L1 adipocytes. GSTA4-silenced adipocytes displayed elevated carbonylation of several key mitochondrial proteins including the phosphate carrier protein, NADH dehydrogenase 1α subcomplexes 2 and 3, translocase of inner mitochondrial membrane 50, and valyl-tRNA synthetase. Elevated protein carbonylation is accompanied by diminished complex I activity, impaired respiration, increased superoxide production, and a reduction in membrane potential without changes in mitochondrial number, area, or density. Silencing of the phosphate carrier or NADH dehydrogenase 1α subcomplexes 2 or 3 in 3T3-L1 cells results in decreased basal and maximal respiration. These results suggest that protein carbonylation plays a major instigating role in cytokine-dependent mitochondrial dysfunction and may be linked to the development of insulin resistance in the adipocyte. PMID:22822087

  16. Palladium-catalyzed oxidative carbonylation reactions.

    PubMed

    Wu, Xiao-Feng; Neumann, Helfried; Beller, Matthias

    2013-02-01

    Palladium-catalyzed coupling reactions have become a powerful tool for advanced organic synthesis. This type of reaction is of significant value for the preparation of pharmaceuticals, agrochemicals, as well as advanced materials. Both, academic as well as industrial laboratories continuously investigate new applications of the different methodologies. Clearly, this area constitutes one of the major topics in homogeneous catalysis and organic synthesis. Among the different palladium-catalyzed coupling reactions, several carbonylations have been developed and widely used in organic syntheses and are even applied in the pharmaceutical industry on ton-scale. Furthermore, methodologies such as the carbonylative Suzuki and Sonogashira reactions allow for the preparation of interesting building blocks, which can be easily refined further on. Although carbonylative coupling reactions of aryl halides have been well established, palladium-catalyzed oxidative carbonylation reactions are also interesting. Compared with the reactions of aryl halides, oxidative carbonylation reactions offer an interesting pathway. The oxidative addition step could be potentially avoided in oxidative reactions, but only few reviews exist in this area. In this Minireview, we summarize the recent development in the oxidative carbonylation reactions. PMID:23307763

  17. Quantification of the electrophilic reactivities of aldehydes, imines, and enones.

    PubMed

    Appel, Roland; Mayr, Herbert

    2011-06-01

    The rates of the epoxidation reactions of aldehydes, of the aziridination reactions of aldimines, and of the cyclopropanation reactions of α,β-unsaturated ketones with aryl-stabilized dimethylsulfonium ylides have been determined photometrically in dimethyl sulfoxide (DMSO). All of these sulfur ylide-mediated cyclization reactions as well as the addition reactions of stabilized carbanions to N-tosyl-activated aldimines have been shown to follow a second-order rate law, where the rate constants reflect the (initial) CC bond formation between nucleophile and electrophile. The derived second-order rate constants (log k(2)) have been combined with the known nucleophilicity parameters (N, s(N)) of the aryl-stabilized sulfur ylides 4a,b and of the acceptor-substituted carbanions 4c-h to calculate the electrophilicity parameters E of aromatic and aliphatic aldehydes (1a-i), N-acceptor-substituted aromatic aldimines (2a-e), and α,β-unsaturated ketones (3a-f) according to the linear free-energy relationship log k(2) = s(N)(N + E) as defined in J. Am. Chem. Soc.2001, 123, 9500-9512. The data reported in this work provide the first quantitative comparison of the electrophilic reactivities of aldehydes, imines, and simple Michael acceptors in DMSO with carbocations and cationic metal-π complexes within our comprehensive electrophilicity scale. PMID:21553901

  18. Thermally Stable Heterocyclic Imines as New Potential Nonlinear Optical Materials

    NASA Technical Reports Server (NTRS)

    Nesterov, Volodymyr V.; Antipin, Mikhail Y.; Nesterov, Vladimir N.; Moore, Craig E.; Cardelino, Beatriz H.; Timofeeva, Tatiana V.

    2004-01-01

    In the course of a search for new thermostable acentric nonlinear optical crystalline materials, several heterocyclic imine derivatives were designed, with the general structure D-pi-A(D'). Introduction of a donor amino group (D') into the acceptor moiety was expected to bring H-bonds into their crystal structures, and so to elevate their melting points and assist in an acentric molecular packing. Six heterocycle-containing compounds of this type were prepared, single crystals were grown for five of them, and these crystals were characterized by X-ray analysis. A significant melting temperature elevation was found for all of the synthesized compounds. Three of the compounds were also found to crystallize in acentric space groups. One of the acentric compounds is built as a three-dimensional H-bonded molecular network. In the other two compounds, with very similar molecular structure, the molecules form one-dimensional H-bonded head-to-head associates (chains). These chains are parallel in two different crystallographic directions and form very unusual interpenetrating chain patterns in an acentric crystal. Two of the compounds crystallized with centrosymmetric molecular packing.

  19. Sphingosine induces the aggregation of imine-containing peroxidized vesicles.

    PubMed

    Jiménez-Rojo, Noemi; Viguera, Ana R; Collado, M Isabel; Sims, Kacee H; Constance, Chad; Hill, Kasey; Shaw, Walt A; Goñi, Félix M; Alonso, Alicia

    2014-08-01

    Lipid peroxidation plays a central role in the pathogenesis of many diseases like atherosclerosis and multiple sclerosis. We have analyzed the interaction of sphingosine with peroxidized bilayers in model membranes. Cu(2+) induced peroxidation was checked following UV absorbance at 245nm, and also using the novel Avanti snoopers®. Mass spectrometry confirms the oxidation of phospholipid unsaturated chains. Our results show that sphingosine causes aggregation of Cu(2+)-peroxidized vesicles. We observed that aggregation is facilitated by the presence of negatively-charged phospholipids in the membrane, and inhibited by anti-oxidants e.g. BHT. Interestingly, long-chain alkylamines (C18, C16) but not their short-chain analogues (C10, C6, C1) can substitute sphingosine as promoters of vesicle aggregation. Furthermore, sphinganine but not sphingosine-1-phosphate can mimic this effect. Formation of imines in the membrane upon peroxidation was detected by (1)H-NMR and it appeared to be necessary for the aggregation effect. (31)P-NMR spectroscopy reveals that sphingosine facilitates formation of non-lamellar phase in parallel with vesicle aggregation. The data might suggest a role for sphingosine in the pathogenesis of atherosclerosis. PMID:24802275

  20. Stratospheric carbonyl sulfide (OCS) burden

    NASA Astrophysics Data System (ADS)

    Kloss, Corinna; Walker, Kaley A.; Deshler, Terry; von Hobe, Marc

    2015-04-01

    An estimation of the global stratospheric burden of carbonyl sulfide (OCS) calculated using satellite based measurements from the Atmospheric Chemistry Experiment - Fourier Transform Spectrometer (ACE-FTS) will be presented. OCS is the most abundant sulfur containing gas in the atmosphere in the absence of volcanic eruptions. With a long lifetime of 2-6 years it reaches the stratosphere where it is photolyzed and the sulfur oxidized and condensed to aerosols, contributing to the stratospheric aerosol layer. The aerosol layer is the one factor of the middle-atmosphere with a direct impact on the Earth's climate by scattering incoming solar radiation back to space. Therefore it is crucial to understand and estimate the different processes and abundances of the species contributing to the aerosol layer. However, the exact amount of OCS in the stratosphere has not been quantified yet. A study on the OCS mixing ratio distribution based on ACE-FTS data has already been made by Barkley et al. (2008), also giving an estimation for the total atmospheric OCS mass. ACE-FTS is an infrared solar occultation spectrometer providing high- resolution profile observations since 2004. In the scope of this work the focus lies on the stratospheric OCS burden, calculated by integrating the ACE profiles. A global overview on the stratospheric OCS amount in the past and present based on the ACE data as well as a look at regional and seasonal variability will be given. Furthermore, the results of this work will be useful for further studies on OCS fluxes and lifetimes, and in quantifying the contribution of OCS to the global stratospheric sulfur burden. Barkley et al., 2008, Geophys. Res. Lett., 35, L14810.

  1. Characteristic infrared intensities of carbonyl stretching vibrations.

    PubMed

    Richter, Wagner E; Silva, Arnaldo F; Vidal, Luciano N; Bruns, Roy E

    2016-07-14

    The experimental infrared fundamental intensities of gas phase carbonyl compounds obtained by the integration of spectral bands in the Pacific Northwest National Laboratory (PNNL) spectral database are in good agreement with the intensities reported by other laboratories having a root mean square error of 27 km mol(-1) or about 13% of the average intensity value. The Quantum Theory of Atoms in Molecules/Charge-Charge Transfer-Counterpolarization (QTAIM/CCTCP) model indicates that the large intensity variation from 61.7 to 415.4 km mol(-1) is largely due to static atomic charge contributions, whereas charge transfer and counterpolarization effects essentially cancel one another leaving only a small net effect. The Characteristic Substituent Shift Model estimates the atomic charge contributions to the carbonyl stretching intensities within 30 km mol(-1) or 10% of the average contribution. However, owing to the size of the 2 × C × CTCP interaction contribution, the total intensities cannot be estimated with this degree of accuracy. The dynamic intensity contributions of the carbon and oxygen atoms account for almost all of the total stretching intensities. These contributions vary over large ranges with the dynamic contributions of carbon being about twice the size of the oxygen ones for a large majority of carbonyls. Although the carbon monoxide molecule has an almost null dipole moment contrary to the very polar bond of the characteristic carbonyl group, its QTAIM/CCTCP model is very similar to those found for the carbonyl compounds. PMID:27306140

  2. Fast photolysis of carbonyl nitrates from isoprene

    NASA Astrophysics Data System (ADS)

    Müller, Jean-Francois; Peeters, Jozef; Stavrakou, Trisevgeni

    2014-05-01

    We show that photolysis is, by far, the major atmospheric sink of isoprene-derived carbonyl nitrates. Empirical evidence from published laboratory studies on the absorption cross sections and photolysis rates of α-nitrooxy ketones suggests that the presence of the nitrate group (i) greatly enhances the absorption cross sections, and (ii) facilitates dissociation to a point that the photolysis quantum yield is close to unity, with O-NO2 dissociation as the likely major channel. On this basis, we provide new recommendations for estimating the cross sections and photolysis rates of carbonyl nitrates. The newly estimated photorates are validated using a chemical box model against measured temporal profiles of carbonyl nitrates in an isoprene oxidation experiment by Paulot et al. (2009). The comparisons for ethanal nitrate and for the sum of methacrolein- and methylvinylketone nitrates strongly supports our assumptions of large cross section enhancements and a near-unit quantum yield for these compounds. These findings have significant atmospheric implications, as carbonyl nitrates constitute an important component of the total organic nitrate pool over vegetated areas: the photorates of key carbonyl nitrates from isoprene are estimated to be typically between ~3 and 20 times higher than their sink due to reaction with OH in relevant atmospheric conditions. Moreover, since the reaction is expected to release NO2, photolysis is especially effective in depleting the total organic nitrate pool.

  3. Oxidative stress induced carbonylation in human plasma.

    PubMed

    Madian, Ashraf G; Diaz-Maldonado, Naomi; Gao, Qiang; Regnier, Fred E

    2011-10-19

    The focus of this study was on the assessment of technology that might be of clinical utility in identification, quantification, characterization of carbonylation in human plasma proteins. Carbonylation is widely associated with oxidative stress diseases. Breast cancer patient samples were chosen as a stress positive case based on the fact that oxidative stress has been reported to be elevated in this disease. Measurements of 8-isoprostane in plasma confirmed that breast cancer patients in this study were indeed experiencing significant oxidative stress. Carbonyl groups in proteins from freshly drawn blood were derivatized with biotin hydrazide after which the samples were dialyzed and the biotinylated proteins subsequently selected, digested and labeled with iTRAQ™ heavy isotope coding reagent(s). Four hundred sixty proteins were identified and quantified, 95 of which changed 1.5 fold or more in concentration. Beyond confirming the utility of the analytical method, association of protein carbonylation was examined as well. Nearly one fourth of the selected proteins were of cytoplasmic, nuclear, or membrane origin. Analysis of the data by unbiased knowledge assembly methods indicated the most likely disease associated with the proteins was breast neoplasm. Pathway analysis showed the proteins which changed in carbonylation were strongly associated with Brca1, the breast cancer type-1 susceptibility protein. Pathway analysis indicated the major molecular functions of these proteins are defense, immunity and nucleic acid binding. PMID:21856457

  4. Oxidative stress induced carbonylation in human plasma

    PubMed Central

    Madian, Ashraf G.; Diaz-Maldonado, Naomi; Gao, Qiang; Regnier, Fred E.

    2011-01-01

    The focus of this study was on the assessment of technology that might be of clinical utility in identification, quantification, characterization of carbonylation in human plasma proteins. Carbonylation is widely associated with oxidative stress diseases. Breast cancer patient samples were chosen as a stress positive case based on the fact that oxidative stress has been reported to be elevated in this disease. Measurements of 8-isoprostane in plasma confirmed that breast cancer patients in this study were indeed experiencing significant oxidative stress. Carbonyl groups in proteins from freshly drawn blood were derivatized with biotin hydrazide after which the samples were dialyzed and the biotinylated proteins subsequently selected, digested and labeled with iTRAQ™ heavy isotope coding reagent(s). Four hundred sixty proteins were identified and quantified, 95 of which changed 1.5 fold or more in concentration. Beyond confirming the utility of the analytical method, association of protein carbonylation was examined as well. Nearly one fourth of the selected proteins were of cytoplasmic, nuclear, or membrane origin. Analysis of the data by unbiased knowledge assembly methods indicated the most likely disease associated with the proteins was breast neoplasm. Pathway analysis showed the proteins which changed in carbonylation were strongly associated with Brca1, the breast cancer type-1 susceptibility protein. Pathway analysis indicated the major molecular functions of these proteins are defense, immunity and nucleic acid binding. PMID:21856457

  5. Process and catalyst for carbonylating olefins

    DOEpatents

    Zoeller, Joseph Robert

    1998-06-02

    Disclosed is an improved catalyst system and process for preparing aliphatic carbonyl compounds such as aliphatic carboxylic acids, alkyl esters of aliphatic carboxylic acids and anhydrides of aliphatic carboxylic acids by carbonylating olefins in the presence of a catalyst system comprising (1) a first component selected from at least one Group 6 metal, i.e., chromium, molybdenum, and/or tungsten and (2) a second component selected from at least one of certain halides and tertiary and quaternary compounds of a Group 15 element, i.e., nitrogen, phosphorus and/or arsenic, and (3) as a third component, a polar, aprotic solvent. The process employing the improved catalyst system is carried out under carbonylating conditions of pressure and temperature discussed herein. The process constitutes and improvement over known processes since it can be carried out at moderate carbonylation conditions without the necessity of using an expensive noble metal catalyst, volatile, toxic materials such as nickel tetracarbonyl, formic acid or a formate ester. Further, the addition of a polar, aprotic solvent to the catalyst system significantly increases, or accelerates, the rate at which the carbonylation takes place.

  6. Coupling the Torpedo Microplate-Receptor Binding Assay with Mass Spectrometry to Detect Cyclic Imine Neurotoxins

    PubMed Central

    Aráoz, Rómulo; Ramos, Suzanne; Pelissier, Franck; Guérineau, Vincent; Benoit, Evelyne; Vilariño, Natalia; Botana, Luis M.; Zakarian, Armen; Molgó, Jordi

    2014-01-01

    Cyclic imine neurotoxins constitute an emergent family of neurotoxins of dinoflagellate origin that are potent antagonists of nicotinic acetylcholine receptors. We developed a target-directed functional method based on the mechanism of action of competitive agonists/antagonists of nicotinic acetylcholine receptors for the detection of marine cyclic imine neurotoxins. The key step for method development was the immobilization of Torpedo electrocyte membranes rich in nicotinic acetylcholine receptors on the surface of microplate wells and the use of biotinylated-α-bungarotoxin as tracer. Cyclic imine neurotoxins competitively inhibit biotinylated-α-bungarotoxin binding to Torpedo-nicotinic acetylcholine receptors in a concentration-dependent manner. The microplate-receptor binding assay allowed rapid detection of nanomolar concentrations of cyclic imine neurotoxins directly in shellfish samples. Although highly sensitive and specific for the detection of neurotoxins targeting nicotinic acetylcholine receptors as a class, the receptor binding assay cannot identify a given analyte. To address the low selectivity of the microplate-receptor binding assay, the cyclic imine neurotoxins tightly bound to the coated Torpedo nicotinic receptor were eluted with methanol, and the chemical nature of the eluted ligands was identified by mass spectrometry. The immobilization of Torpedo electrocyte membranes on the surface of microplate wells proved to be a high-throughput format for the survey of neurotoxins targeting nicotinic acetylcholine receptors directly in shellfish matrixes with high sensitivity and reproducibility. PMID:23131021

  7. Coupling the Torpedo microplate-receptor binding assay with mass spectrometry to detect cyclic imine neurotoxins.

    PubMed

    Aráoz, Rómulo; Ramos, Suzanne; Pelissier, Franck; Guérineau, Vincent; Benoit, Evelyne; Vilariño, Natalia; Botana, Luis M; Zakarian, Armen; Molgó, Jordi

    2012-12-01

    Cyclic imine neurotoxins constitute an emergent family of neurotoxins of dinoflagellate origin that are potent antagonists of nicotinic acetylcholine receptors. We developed a target-directed functional method based on the mechanism of action of competitive agonists/antagonists of nicotinic acetylcholine receptors for the detection of marine cyclic imine neurotoxins. The key step for method development was the immobilization of Torpedo electrocyte membranes rich in nicotinic acetylcholine receptors on the surface of microplate wells and the use of biotinylated-α-bungarotoxin as tracer. Cyclic imine neurotoxins competitively inhibit biotinylated-α-bungarotoxin binding to Torpedo-nicotinic acetylcholine receptors in a concentration-dependent manner. The microplate-receptor binding assay allowed rapid detection of nanomolar concentrations of cyclic imine neurotoxins directly in shellfish samples. Although highly sensitive and specific for the detection of neurotoxins targeting nicotinic acetylcholine receptors as a class, the receptor binding assay cannot identify a given analyte. To address the low selectivity of the microplate-receptor binding assay, the cyclic imine neurotoxins tightly bound to the coated Torpedo nicotinic receptor were eluted with methanol, and the chemical nature of the eluted ligands was identified by mass spectrometry. The immobilization of Torpedo electrocyte membranes on the surface of microplate wells proved to be a high-throughput format for the survey of neurotoxins targeting nicotinic acetylcholine receptors directly in shellfish matrixes with high sensitivity and reproducibility. PMID:23131021

  8. Two Structures of a Thiazolinyl Imine Reductase from Yersinia enterocolitica (Irp3) Provide Insight for Catalysis and Binding to the Nonribosomal Peptide Synthetase Module of HMWP1

    PubMed Central

    Meneely, Kathleen M.; Lamb, Audrey L.

    2012-01-01

    The thiazolinyl imine reductase from Yersinia enterocolitica (Irp3) catalyzes the NADPH-dependent reduction of a thiazoline ring in an intermediate for the formation of the siderophore yersiniabactin. Two structures of Irp3 were determined in the apo- (1.85 Å) and NADP+-bound (2.31 Å) forms. Irp3 shows structural homology to sugar oxidoreductases such as glucose-fructose oxidoreductase and 1,5-anhydro-D-fructose reductase, as well as to biliverdin reductase. A homology model of the thiazolinyl imine reductase from Pseudomonas aeruginosa (PchG) was generated. Extensive loop insertions are observed in the C-terminal domain that are unique to Irp3 and PchG and not found in the structural homologs that recognize small molecular substrates. These loops are hypothesized to be important for binding of the nonribosomal peptide synthetase modules (found in HMWP1 and PchF, respectively) to which the substrate of the reductase is covalently attached. A catalytic mechanism of proton donation from a general acid (either histidine-101 or tyrosine-128) and hydride donation from C4 of nicotinamide of the NADPH cofactor is proposed for reduction of the carbon-nitrogen double bond of the thiazoline. PMID:23066849

  9. Carbonyl compounds indoors in a changing climate

    PubMed Central

    2012-01-01

    Background Formic acid, acetic acid and formaldehyde are important compounds in the indoor environment because of the potential for these acids to degrade calcareous materials (shells, eggs, tiles and geological specimens), paper and corrode or tarnish metals, especially copper and lead. Carbonyl sulfide tarnishes both silver and copper encouraging the formation of surface sulfides. Results Carbonyls are evolved more quickly at higher temperatures likely in the Cartoon Gallery at Knole, an important historic house near Sevenoaks in Kent, England where the study is focused. There is a potential for higher concentrations to accumulate. However, it may well be that in warmer climates they will be depleted more rapidly if ventilation increases. Conclusions Carbonyls are likely to have a greater impact in the future. PMID:22439648

  10. Carbonyl extraction of lunar and asteroidal metals

    NASA Astrophysics Data System (ADS)

    Lewis, John S.; Jones, Thomas D.; Farrand, William H.

    It is suggested that the Mond process for carbonyl extraction of metals from ore may be used as an efficient, low-energy scheme for producing high-purity Fe, Ni, Cr, Mn, and Co from lunar or asteroidal feedstocks. It is proposed that scenarios for obtaining oxygen from the lunar relogith can be enhanced by carbonyl processing of the metallic alloy byproducts of such operations. It is further suggested that the native metal content of asteroidal regoliths is even more suitable to carbonyl processing. High-purity, corrosion-resistant Fe and Ni can be extracted from asteroidal feedstocks along with a Co-rich residue containing 0.5 percent platinum-group metals. Recommendations for bringing the method to a practical level of development for space applications are presented.

  11. Copper-Catalyzed Carbonylative Coupling of Cycloalkanes and Amides.

    PubMed

    Li, Yahui; Dong, Kaiwu; Zhu, Fengxiang; Wang, Zechao; Wu, Xiao-Feng

    2016-06-13

    Carbonylation reactions are a most powerful method for the synthesis of carbonyl-containing compounds. However, most known carbonylation procedures still require noble-metal catalysts and the use of activated compounds and good nucleophiles as substrates. Herein, we developed a copper-catalyzed carbonylative transformation of cycloalkanes and amides. Imides were prepared in good yields by carbonylation of a C(sp(3) )-H bond of the cycloalkane with the amides acting as weak nucleophiles. Notably, this is the first report of copper-catalyzed carbonylative C-H activation. PMID:27167881

  12. Advances in Measurement of Carbonyls in Aerosols.

    NASA Astrophysics Data System (ADS)

    Charles, M.; Jakober, C.; Spaulding, R.; Green, P.; Destaillats, H.; Hughes, J. M.

    2002-12-01

    Chamber studies establish the formation of highly polar oxygenated species from the reaction of anthropogenic and biogenic hydrocarbons with hydroxyl radicals or ozone. A paucity of data exists however on the generation and fate of these organics in the ambient atmospheric environment. This is primarily due to the absence of suitable analytical methods. To address limitations of existing methods, we developed methods that rely on O-(2,3,4,5,6)-pentafluorobenzylhydroxylamine (PFBHA), and bis-(trimethylsilyl) trifluoroacetamide (BSTFA) in concert with GC/ion trap mass spectrometry (GC/ITMS) to identify and quantify carbonyl, dicarbonyl and hydroxy carbonyl photooxidation products in aerosols at part-per-trillion (pptv) levels. We also optimized and evaluated a mist chamber to sample carbonyls and multi-functional carbonyls with 10 minute sampling times. We applied the method to identify and quantify 2-hydroxy-2-methyl propanal (2-HMPR), a proposed photooxidation product of 2-methyl-3-buten-2-ol (MBO) in the Blodgett Forest, CA. The average 2-HMPR/MBO mixing ratio was 0.33ñ 0.25, which is reasonable since the expected yield of 2-HMPR from the hydroxyl radical oxidation of MBO is 0.19-0.35. Further method development in our laboratory is exploring the employment of HPLC/atmospheric pressure chemical ionization (APCI) mass spectra to identify model aliphatic and aromatic carbonyls (the major classes were aldehydes, ketones, dicarbonyls, and quinones) in aerosols. The data indicate the potential for pentafluorobenzyl derivatization in concert with GC/ITMS and HPLC/ITMS to measure a broad range of carbonyls.

  13. "Click" Chemistry: Application of Copper Metal in Cu-Catalyzed Azomethine Imine-Alkyne Cycloadditions.

    PubMed

    Pušavec Kirar, Eva; Grošelj, Uroš; Mirri, Giorgio; Požgan, Franc; Strle, Gregor; Štefane, Bogdan; Jovanovski, Vasko; Svete, Jurij

    2016-07-15

    A series of 16 copper-catalyzed azomethine imine-alkyne cycloaddition (CuAIAC) reactions between four pyrazolidinone-1-azomethine imines and four terminal ynones gave the corresponding fluorescent cycloadducts as bimane analogues in very high yields. The applicability of CuAIAC was demonstrated by the fluorescent labeling of functionalized polystyrene and by using Cu-C and Cu-Fe as catalysts. Experimental evidence, kinetic measurements, and correlation between a clean catalyst surface and the reaction rate are in agreement with a homotopic catalytic system with catalytic Cu(I)-acetylide formed from Cu(0) by "in situ" oxidation. The availability of azomethine imines, mild reaction conditions, simple workup, and scalability make CuAIAC a viable supplement to the Cu-catalyzed azide-alkyne cycloaddition reaction in "click" chemistry. PMID:27305104

  14. Structure-Reactivity Relationship in the Frustrated Lewis Pair (FLP)-Catalyzed Hydrogenation of Imines.

    PubMed

    Tussing, Sebastian; Kaupmees, Karl; Paradies, Jan

    2016-05-23

    The autoinduced, frustrated Lewis pair (FLP)-catalyzed hydrogenation of 16-benzene-ring substituted N-benzylidene-tert-butylamines with B(2,6-F2 C6 H3 )3 and molecular hydrogen was investigated by kinetic analysis. The pKa values for imines and for the corresponding amines were determined by quantum-mechanical methods and provided a direct proportional relationship. The correlation of the two rate constants k1 (simple catalytic cycle) and k2 (autoinduced catalytic cycle) with pKa difference between imine and amine pairs (ΔpKa ) or Hammett's σ parameter served as useful parameters to establish a structure-reactivity relationship for the FLP-catalyzed hydrogenation of imines. PMID:27060884

  15. Proton Therapy

    MedlinePlus

    ... nucleus is surrounded by electrons. In proton therapy, beams of fast-moving protons are used to destroy ... atoms to release proton, neutron, and helium ion beams. In this highly specialized form of radiosurgery , proton ...

  16. Palladium-catalyzed carbonylative synthesis of benzoxazinones from N-(o-bromoaryl)amides using paraformaldehyde as the carbonyl source.

    PubMed

    Li, Wanfang; Wu, Xiao-Feng

    2014-11-01

    Carbonylation reactions have been widely used in organic synthesis. However, the manipulation of toxic and pressurized carbon monoxide limited their applications in organic laboratories. The search for alternative carbonyl sources as an important method for carbonylative organic synthesis is spreading. Herein, a series of substituted benzoxazinones were synthesized from N-(o-bromoaryl)amides by palladium-catalyzed carbonylation with paraformaldehyde as the carbonyl source, which is inexpensive, stable, and easy to use. Notably, this is the first example of using paraformaldehyde as the CO source in palladium-catalyzed carbonylative synthesis of heterocycles. PMID:25280209

  17. Specificity of sites within eight-membered ring zeolite channels for carbonylation of methyls to acetyls.

    PubMed

    Bhan, Aditya; Allian, Ayman D; Sunley, Glenn J; Law, David J; Iglesia, Enrique

    2007-04-25

    The acid-catalyzed formation of carbon-carbon bonds from C1 precursors via CO insertion into chemisorbed methyl groups occurs selectively within eight-membered ring (8-MR) zeolite channels. This elementary step controls catalytic carbonylation rates of dimethyl ether (DME) to methyl acetate. The number of O-H groups within 8-MR channels was measured by rigorous deconvolution of the infrared bands for O-H groups in cation-exchanged and acid forms of mordenite (M,H-MOR) and ferrierite (H-FER) after adsorption of basic probe molecules of varying size. DME carbonylation rates are proportional to the number of O-H groups within 8-MR channels. Na+ cations selectively replaced protons within 8-MR channels and led to a disproportionate decrease in carbonylation turnover rates (per total H+). These conclusions are consistent with the low or undetectable rates of carbonylation on zeolites without 8-MR channels (H-BEA, H-FAU, H-MFI). Such specificity of methyl reactivity upon confinement within small channels appears to be unprecedented in catalysis by microporous solids, which typically select reactions by size exclusion of bulkier transition states. PMID:17397162

  18. Synthesis of Imine-Bearing ZnO Nanoparticle Thin Films and Characterization of Their Structural, Morphological and Optical Properties.

    PubMed

    Kaur, Narinder; Sharma, Sanjeev K; Kim, Deuk Young; Sharma, Hemant; Singh, Narinder

    2015-10-01

    We are presenting the first report on the fabrication of imine-bearing ZnO nanoparticle thin films grown on Corning glass by spin coating. The sol was prepared by dissolving imine-bearing ZnO nanoparticles in dimethylsulfoxide (DMSO). The thickness of the films was manipulated to be 125-200 nm. The X-ray diffraction (XRD) analysis showed hexagonal wurtzite structure of imine-bearing ZnO nanoparticles thin films with a (002) preferential orientation. The stretching of chemical bonds of the imine linkage and Zn-O in imine-bearing ZnO nanoparticle thin films was confirmed by Fourier transform infrared spectroscopy (FTIR). The grain size of the films increased with increasing the thickness of the films due to the number of coatings and subsequently dried at 200 °C. The transmittance of imine-bearing ZnO nanoparticle thin films was observed to be ≥94%, which was in close agreement to pure ZnO thin films in the visible region. The bandgap of imine-bearing ZnO nanoparticle thin films (3.04 eV), evaluated from Tauc's plot, was observed to be lower than that of pure ZnO (3.21 eV), which is attributed to the interaction of the ZnO nanoparticles with the imine receptor. PMID:26726472

  19. Four-Component Reaction for the Synthesis of Dithiocarbamates Starting from Cyclic Imines.

    PubMed

    Schlüter, Torben; Ziyaei Halimehjani, Azim; Wachtendorf, Daniel; Schmidtmann, Marc; Martens, Jürgen

    2016-08-01

    An efficient one-pot, four-component reaction for the synthesis of dithiocarbamates using carbon disulfide, cyclic imines, acid chlorides, and commercially available primary or secondary amines has been developed by performing an acid chloride addition to a heterocyclic imine followed by subsequent nucleophilic substitution of in situ generated dithiocarbamic acid. With the aid of the newly developed and powerful multicomponent reaction, a direct route for the synthesis of 24 unknown dithiocarbamates in moderate to good yield under mild conditions is enabled. PMID:27362425

  20. The synthesis, structure and reactivity of an imine-stabilized carboranylphosphorus(i) compound.

    PubMed

    Chan, Tek Long; Xie, Zuowei

    2016-06-01

    A new imine-stabilized carboranyl-phosphinidene has been synthesized and structurally characterized. DFT studies suggest that the imine moiety provides an electron pair to stabilize carboranyl-phosphinidene. On the other hand, the sterically demanding carboranyl ligand can prevent the dimerization, facilitating the formation of monomeric phosphinidene. These observations are supported by the reactivity studies. Such a monovalent phosphorous(i) compound can undergo reactions with Cu(OAc)2, S, Se, (TMS)CHN2 and HCl to give various phosphorus(iii) species. All compounds are fully characterized by NMR spectroscopy, elemental analyses as well as single-crystal X-ray analyses. PMID:27180610

  1. Ruthenium-catalyzed reductive methylation of imines using carbon dioxide and molecular hydrogen.

    PubMed

    Beydoun, Kassem; Ghattas, Ghazi; Thenert, Katharina; Klankermayer, Jürgen; Leitner, Walter

    2014-10-01

    The use of the well-defined [Ru(triphos)(tmm)] catalyst, CO2 as C1 source, and H2 as reducing agent enabled the reductive methylation of isolated imines, as well as the direct coupling of amines with aldehydes and the subsequent reductive methylation of the in situ formed imines. The method, which afforded the corresponding N-methyl amines in very good to excellent yields, was also used for the preparation of the antifungal agent butenafine in one step with no apparent waste, thus increasing the atom efficiency of its synthesis. PMID:25146346

  2. Fast photolysis of carbonyl nitrates from isoprene

    NASA Astrophysics Data System (ADS)

    Müller, J.-F.; Peeters, J.; Stavrakou, T.

    2014-03-01

    Photolysis is shown to be a major sink for isoprene-derived carbonyl nitrates, which constitute an important component of the total organic nitrate pool over vegetated areas. Empirical evidence from published laboratory studies on the absorption cross sections and photolysis rates of α-nitrooxy ketones suggests that the presence of the nitrate group (i) greatly enhances the absorption cross sections and (ii) facilitates dissociation to a point that the photolysis quantum yield is close to unity, with O-NO2 dissociation as a likely major channel. On this basis, we provide new recommendations for estimating the cross sections and photolysis rates of carbonyl nitrates. The newly estimated photo rates are validated using a chemical box model against measured temporal profiles of carbonyl nitrates in an isoprene oxidation experiment by Paulot et al. (2009). The comparisons for ethanal nitrate and for the sum of methacrolein- and methyl vinyl ketone nitrates strongly supports our assumptions of large cross-section enhancements and a near-unit quantum yield for these compounds. These findings have significant atmospheric implications: the photorates of key carbonyl nitrates from isoprene are estimated to be typically between ~ 3 and 20 times higher than their sink due to reaction with OH in relevant atmospheric conditions. Moreover, since the reaction is expected to release NO2, photolysis is especially effective in depleting the total organic nitrate pool.

  3. Fast photolysis of carbonyl nitrates from isoprene

    NASA Astrophysics Data System (ADS)

    Müller, J.-F.; Peeters, J.; Stavrakou, T.

    2013-11-01

    Photolysis is shown to be a major sink for isoprene-derived carbonyl nitrates, which constitute an important component of the total organic nitrate pool over vegetated areas. Empirical evidence from published laboratory studies on the absorption cross sections and photolysis rates of α-nitrooxy ketones suggests that the presence of the nitrate group (i) greatly enhances the absorption cross sections, and (ii) facilitates dissociation to a point that the photolysis quantum yield is close to unity, with O-NO2 dissociation as the likely major channel. On this basis, we provide new recommendations for estimating the cross sections and photolysis rates of carbonyl nitrates. The newly estimated photorates are validated using a chemical box model against measured temporal profiles of carbonyl nitrates in an isoprene oxidation experiment by Paulot et al. (2009). The comparisons for ethanal nitrate and for the sum of methacrolein- and methylvinylketone nitrates strongly supports our assumptions of large cross section enhancements and a near-unit quantum yield for these compounds. These findings have significant atmospheric implications: the photorates of key carbonyl nitrates from isoprene are estimated to be typically between ~3 and 20 times higher than their sink due to reaction with OH in relevant atmospheric conditions. Moreover, since the reaction is expected to release NO2, photolysis is especially effective in depleting the total organic nitrate pool.

  4. Organocatalyzed Intramolecular Carbonyl-Ene Reactions.

    PubMed

    Dahlmann, Heidi A; McKinney, Amanda J; Santos, Maria P; Davis, Lindsey O

    2016-01-01

    An organocatalyzed intramolecular carbonyl-ene reaction was developed to produce carbocyclic and heterocyclic 5- and 6-membered rings from a citronellal-derived trifluoroketone and a variety of aldehydes. A phosphoramide derivative was found to promote the cyclization of the trifluoroketone, whereas a less acidic phosphoric acid proved to be a superior catalyst for the aldehyde substrates. PMID:27258238

  5. High Pressure Synthesis of Transition Metal Carbonyls.

    ERIC Educational Resources Information Center

    Hagen, A. P.; And Others

    1979-01-01

    Presents an experiment which uses readily available starting materials and inexpensive equipment for synthesis of transition metal carbonyls at 1000 atm and which is intended to give students experience in techniques used in research and industry. Safety precautions are emphasized. (Author/SA)

  6. Polyimides Containing Carbonyl and Ether Connecting Groups

    NASA Technical Reports Server (NTRS)

    Hergenrother, Paul M.; Havens, Stephen J.

    1987-01-01

    Semicrystallinity gives rise to tough, solvent-resistant polymers. New polyimides prepared from reaction of aromatic dianhydrides with new diamines containing carbonyl and ether connecting groups between aromatic rings. Damines prepared from reaction of 4-aminophenol with activated aromatic difluoro compounds in presence of potassium carbonate. These types of polymers have potential applications in molded products, films, adhesives, and composites.

  7. Bifunctional influence of 3-chloro substitution on structural and energetic characteristics of N-methyl-salicylidene imines

    NASA Astrophysics Data System (ADS)

    Koll, A.; Janski, J.; Karpfen, A.; Wolschann, P.

    2010-07-01

    Energetic and structural effects of formation of intramolecular hydrogen bonds in the group of eight differently chloro-substituted ortho-hydroxy aromatic Schiff bases ( N-methyl-salicylidene imines) containing the 3-chloro substituent in all compounds were studied. The aim was to explain the specific function of this substituent, giving rise to an especially large increase of the strength of intramolecular hydrogen bonds. DFT B3LYP/6-31 + G(d,p) calculations of the structures of particular conformers as well as the potential energy surfaces were carried out. The method of thermodynamic cycle-like scheme was adapted, where the three open conformers are used to estimate the steric corrections connected with formation of chelate rings in the fourth conformer. Problems arising for the estimation of the energy of intramolecular hydrogen bonds connected with the selection of reference states and various structural aspects are discussed in detail. 3-Chloro-substituted Schiff bases can be accounted as sterically enhanced intramolecular hydrogen bonds. Participation of steric and electronic functions in increasing of the energy of intramolecular hydrogen bonds was analyzed. Low energetic proton transfer reaction was found in these molecules, which can be potentially interesting from the point of view of possible thermochromic applications.

  8. Transition-Metal-Catalyzed Carbonylation of Methyl Acetate.

    ERIC Educational Resources Information Center

    Polichnowski, S. W.

    1986-01-01

    Presents a study of the rhodium-catalyzed, ioding-promoted carbonylation of methyl acetate. This study provides an interesting contrast between the carbonylation of methyl acetate and the carbonylation of methanol when similar rhodium/iodine catalyst systems are used. (JN)

  9. Method for conversion of .beta.-hydroxy carbonyl compounds

    DOEpatents

    Lilga, Michael A.; White, James F.; Holladay, Johnathan E.; Zacher, Alan H.; Muzatko, Danielle S.; Orth, Rick J.

    2010-03-30

    A process is disclosed for conversion of salts of .beta.-hydroxy carbonyl compounds forming useful conversion products including, e.g., .alpha.,.beta.-unsaturated carbonyl compounds and/or salts of .alpha.,.beta.-unsaturated carbonyl compounds. Conversion products find use, e.g., as feedstock and/or end-use chemicals.

  10. Ferricytochrome c Directly Oxidizes Aminoacetone to Methylglyoxal, a Catabolite Accumulated in Carbonyl Stress

    PubMed Central

    Sartori, Adriano; Mano, Camila M.; Mantovani, Mariana C.; Dyszy, Fábio H.; Massari, Júlio; Tokikawa, Rita; Nascimento, Otaciro R.; Nantes, Iseli L.; Bechara, Etelvino J. H.

    2013-01-01

    Age-related diseases are associated with increased production of reactive oxygen and carbonyl species such as methylglyoxal. Aminoacetone, a putative threonine catabolite, is reportedly known to undergo metal-catalyzed oxidation to methylglyoxal, NH4+ ion, and H2O2 coupled with (i) permeabilization of rat liver mitochondria, and (ii) apoptosis of insulin-producing cells. Oxidation of aminoacetone to methylglyoxal is now shown to be accelerated by ferricytochrome c, a reaction initiated by one-electron reduction of ferricytochrome c by aminoacetone without amino acid modifications. The participation of O2•− and HO• radical intermediates is demonstrated by the inhibitory effect of added superoxide dismutase and Electron Paramagnetic Resonance spin-trapping experiments with 5,5′-dimethyl-1-pyrroline-N-oxide. We hypothesize that two consecutive one-electron transfers from aminoacetone (E0 values = −0.51 and −1.0 V) to ferricytochrome c (E0 = 0.26 V) may lead to aminoacetone enoyl radical and, subsequently, imine aminoacetone, whose hydrolysis yields methylglyoxal and NH4+ ion. In the presence of oxygen, aminoacetone enoyl and O2•− radicals propagate aminoacetone oxidation to methylglyoxal and H2O2. These data endorse the hypothesis that aminoacetone, putatively accumulated in diabetes, may directly reduce ferricyt c yielding methylglyoxal and free radicals, thereby triggering redox imbalance and adverse mitochondrial responses. PMID:23483930

  11. Asymmetric synthesis of trifluoromethylated amines via catalytic enantioselective isomerization of imines.

    PubMed

    Wu, Yongwei; Deng, Li

    2012-09-01

    A new approach toward the asymmetric synthesis of optically active trifluoromethylated amines was enabled by an unprecedented, highly enantioselective catalytic isomerization of trifluoromethyl imines with a new chiral organic catalyst. Not only aryl but also alkyl trifluoromethylated amines could be obtained in high enantioselectivities. PMID:22906148

  12. Temperature-dependent annuloselectivity and stereochemistry in the reactions of methanesulfonyl sulfene with imines.

    PubMed

    Wu, Qiuyue; Yang, Zhanhui; Xu, Jiaxi

    2016-07-26

    The annuloselectivity in the reactions of methanesulfonyl sulfene and imines varies with temperature. At a relatively higher temperature of 20 °C, the [2(s) + 2(i)] annulation of different N-alkyl imines occurs exclusively, giving four-membered trans-β-sultams in up to 69% yields. At a lower temperature of -78 °C, the [2(s) + 2(i) + 2(i)] annulation of N-methyl imines takes place specifically, delivering six-membered 1,2,4-thiadiazine 1,1-dioxides, 4-aza-δ-sultams, in up to 80% yields, with diverse configurations at the C3, C5, and C6 stereocenters. The trans-stereochemistry involved in the [2(s) + 2(i)] annulations is attributed to the conrotatory ring closure of the thermodynamically stable 2,3-thiazabutadiene-type zwitterionic intermediates, while the diverse stereochemical outcomes in the [2(s) + 2(i) + 2(i)] annulations are caused by the iminium isomerization in the stepwise nucleophilic [4 + 2] annulation between the same zwitterionic intermediates and a second molecule of N-methyl imines. PMID:27384153

  13. Enantioselective addition of boronates to acyl imines catalyzed by chiral biphenols.

    PubMed

    Bishop, Joshua A; Lou, Sha; Schaus, Scott E

    2009-01-01

    On the big screen: A chiral biphenol catalyst screening protocol was developed for the rapid identification of enantioselective nucleophilic boronate reactions with acyl imines (see scheme). The approach successfully identified a unique catalyst for the reaction of aryl, vinyl, and alkynyl boronates. Mechanistic studies demonstrate boronate ligand exchange with the catalyst is necessary for activation towards nucleophilic addition. PMID:19431168

  14. Copper-catalyzed borylative coupling of vinylazaarenes and N-Boc imines.

    PubMed

    Smith, Joshua J; Best, Daniel; Lam, Hon Wai

    2016-03-01

    Cu-catalyzed three-component couplings of vinylazaarenes, B2(pin)2, and N-Boc imines are described. Oxidation of the initially formed boronate gives azaarene-containing, Boc-protected amino alcohols with reasonable to good diastereoselectivities. PMID:26883896

  15. Cu(I)-catalyzed direct addition and asymmetric addition of terminal alkynes to imines

    PubMed Central

    Wei, Chunmei; Mague, Joel T.; Li, Chao-Jun

    2004-01-01

    A Cu(I)-catalyzed direct addition of alkynes to imines was developed. The process is simple and provides a diverse range of propargylamines in high enantiomeric excess and good yield both in water and in toluene. The absolute configuration of such addition products has been determined by x-ray crystallography. PMID:15067132

  16. Multi-responsive coordination polymers utilising metal-stabilised, dynamic covalent imine bonds.

    PubMed

    García, Fátima; Pelss, Janis; Zuilhof, Han; Smulders, Maarten M J

    2016-07-12

    We report how the combination of dynamic covalent imine bonds and coordination bonds in a single polymer material not only imparts enhanced stability to the final polymer, but also allows the material to be sensitive to a range of stimuli, offering more fine-grained control over its properties. PMID:26879208

  17. Oxidation of heterocyclic amines, sulfilimines, and phosphine imines with dimethyldioxirane. [Aminofurazans

    SciTech Connect

    Coburn, M.D.

    1987-01-01

    Dimethyldioxirane (DMD) reacted with 3-amino-4-(4-chlorophenyl)furazan (1) to yield 3-(4-chlorophenyl)-4-nitrofurazan (5). DMD reacted with the dimethylsulfilimine of 1 to give the sulfoximine with some 5. Treatment of the trioctylphosphine imine (3) with DMD gave only 5. Other reactions with DMD were studied, including the oxidation of aminofurazans. (DLC)

  18. Enantioselective Reduction of Ketones and Imines Catalyzed by (CN-Box)Re(V)-Oxo Complexes

    PubMed Central

    Nolin, Kristine A.; Ahn, Richard W.; Kobayashi, Yusuke; Kennedy-Smith, Joshua J.

    2012-01-01

    The development and application of chiral, non-racemic Re(V)-oxo complexes to the enantioselective reduction of prochiral ketones is described. In addition to the enantioselective reduction of prochiral ketones, we report the application of these complexes to (1) a tandem Meyer-Schuster rearrangement/reduction to access enantioenriched allylic alcohols and (2) the enantioselective reduction of imines. PMID:20623567

  19. Oxidative carbonylation of amines to carbamates

    SciTech Connect

    Waller, F.J.

    1987-04-01

    Within the last several years, new technologies have appeared to replace phosgene for isocyanate manufacture. These include carbamate chemistries based upon dialkyl carbonate, reductive carbonylation of nitroaromatics, and oxidative carbonylation of amines. The carbamate ester can be handled safely and is reversibly cleaved to the isocyanate. The technology described here involves the preparation of both aliphatic and aromatic carbamates from an amine, alcohol, CO, oxidant, and a non-corrosive catalyst. The catalyst precursor is Pd(OAc){sub 2} and the oxidants are copper carboxylates or copper carboxylates and molecular oxygen. The latter represents a one-step carbamate synthesis with high catalyst activity, nearly quantitative conversions and alcohol selectivities greater than 90%. Operating temperatures and pressures are 80-110{degree}C and less than 500 psi, respectively. Experiments designed to probe the mechanism will be presented along with a discussion of novel (Cu(O{sub 2}CR){sub 2}){sub 2}R'NH{sub 2} complexes.

  20. Portable chemiluminescence detector for nickel carbonyl

    SciTech Connect

    Hikade, D.A.; Stedman, D.H.; Walega, J.G.

    1984-08-01

    This article describes a portable chemiluminescent detector for Ni(CO)/sub 4/ containing two innovative components, a self-contained carbon monoxide source which provides a greater degree of portability and a thermal differentiator to improve selectivity. The instrument is capable of measuring parts-per-billion levels of Ni(CO)/sub 4/, Fe(CO)/sub 5/, and NO. The instrument was used to measure carbonyl concentrations in the field and in cigarette smoke.

  1. Carbonyl compounds generated from electronic cigarettes.

    PubMed

    Bekki, Kanae; Uchiyama, Shigehisa; Ohta, Kazushi; Inaba, Yohei; Nakagome, Hideki; Kunugita, Naoki

    2014-11-01

    Electronic cigarettes (e-cigarettes) are advertised as being safer than tobacco cigarettes products as the chemical compounds inhaled from e-cigarettes are believed to be fewer and less toxic than those from tobacco cigarettes. Therefore, continuous careful monitoring and risk management of e-cigarettes should be implemented, with the aim of protecting and promoting public health worldwide. Moreover, basic scientific data are required for the regulation of e-cigarette. To date, there have been reports of many hazardous chemical compounds generated from e-cigarettes, particularly carbonyl compounds such as formaldehyde, acetaldehyde, acrolein, and glyoxal, which are often found in e-cigarette aerosols. These carbonyl compounds are incidentally generated by the oxidation of e-liquid (liquid in e-cigarette; glycerol and glycols) when the liquid comes in contact with the heated nichrome wire. The compositions and concentrations of these compounds vary depending on the type of e-liquid and the battery voltage. In some cases, extremely high concentrations of these carbonyl compounds are generated, and may contribute to various health effects. Suppliers, risk management organizations, and users of e-cigarettes should be aware of this phenomenon. PMID:25353061

  2. Carbonyl Compounds Generated from Electronic Cigarettes

    PubMed Central

    Bekki, Kanae; Uchiyama, Shigehisa; Ohta, Kazushi; Inaba, Yohei; Nakagome, Hideki; Kunugita, Naoki

    2014-01-01

    Electronic cigarettes (e-cigarettes) are advertised as being safer than tobacco cigarettes products as the chemical compounds inhaled from e-cigarettes are believed to be fewer and less toxic than those from tobacco cigarettes. Therefore, continuous careful monitoring and risk management of e-cigarettes should be implemented, with the aim of protecting and promoting public health worldwide. Moreover, basic scientific data are required for the regulation of e-cigarette. To date, there have been reports of many hazardous chemical compounds generated from e-cigarettes, particularly carbonyl compounds such as formaldehyde, acetaldehyde, acrolein, and glyoxal, which are often found in e-cigarette aerosols. These carbonyl compounds are incidentally generated by the oxidation of e-liquid (liquid in e-cigarette; glycerol and glycols) when the liquid comes in contact with the heated nichrome wire. The compositions and concentrations of these compounds vary depending on the type of e-liquid and the battery voltage. In some cases, extremely high concentrations of these carbonyl compounds are generated, and may contribute to various health effects. Suppliers, risk management organizations, and users of e-cigarettes should be aware of this phenomenon. PMID:25353061

  3. Millimeter wave spectra of carbonyl cyanide

    NASA Astrophysics Data System (ADS)

    Bteich, S. B.; Tercero, B.; Cernicharo, J.; Motiyenko, R. A.; Margulès, L.; Guillemin, J.-C.

    2016-07-01

    Context. More than 30 cyanide derivatives of simple organic molecules have been detected in the interstellar medium, but only one dicarbonitrile has been found and that very recently. There is still a lack of high-resolution spectroscopic data particularly for dinitriles derivatives. The carbonyl cyanide molecule is a new and interesting candidate for astrophysical detection. It could be formed by the reaction of CO and CN radicals, or by substitution of the hydrogen atom by a cyano group in cyanoformaldehyde, HC(=O)CN, that has already been detected in the interstellar medium. Aims: The available data on the rotational spectrum of carbonyl cyanide is limited in terms of quantum number values and frequency range, and does not allow accurate extrapolation of the spectrum into the millimeter-wave range. To provide a firm basis for astrophysical detection of carbonyl cyanide we studied its millimeter-wave spectrum. Methods: The rotational spectrum of carbonyl cyanide was measured in the frequency range 152-308 GHz and analyzed using Watson's A- and S-reduction Hamiltonians. Results: The ground and first excited state of v5 vibrational mode were assigned and analyzed. More than 1100 distinct frequency lines of the ground state were fitted to produce an accurate set of rotational and centrifugal distortion constants up to the eighth order. The frequency predictions based on these constants should be accurate enough for astrophysical searches in the frequency range up to 500 GHz and for transition involving energy levels with J ≤ 100 and Ka ≤ 42. Based on the results we searched for interstellar carbonyl cyanide in available observational data without success. Thus, we derived upper limits to its column density in different sources. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2011.0.00009.SV. ALMA is a partnership of ESO (representing its member states), NSF (USA), and NINS (Japan) with NRC (Canada), NSC, and ASIAA (Taiwan), and KASI (Republic of

  4. Carbonyl Emissions from Gasoline and Diesel Motor Vehicles

    SciTech Connect

    Destaillats, Hugo; Jakober, Chris A.; Robert, Michael A.; Riddle, Sarah G.; Destaillats, Hugo; Charles, M. Judith; Green, Peter G.; Kleeman, Michael J.

    2007-12-01

    Carbonyls from gasoline powered light-duty vehicles (LDVs) and heavy-duty diesel powered vehicles (HDDVs) operated on chassis dynamometers were measured using an annular denuder-quartz filter-polyurethane foam sampler with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine derivatization and chromatography-mass spectrometry analyses. Two internal standards were utilized based on carbonyl recovery, 4-fluorobenzaldehyde forcarbonyls and 6-fluoro-4-chromanone for>_C8 compounds. Gas- and particle-phase emissions for 39 aliphatic and 20 aromatic carbonyls ranged from 0.1 ? 2000 ?g/L fuel for LDVs and 1.8 - 27000 mu g/L fuel for HDDVs. Gas-phase species accounted for 81-95percent of the total carbonyls from LDVs and 86-88percent from HDDVs. Particulate carbonyls emitted from a HDDV under realistic driving conditions were similar to concentrations measured in a diesel particulate matter (PM) standard reference material. Carbonyls accounted for 19percent of particulate organic carbon (POC) emissions from low-emission LDVs and 37percent of POC emissions from three-way catalyst equipped LDVs. This identifies carbonyls as one of the largest classes of compounds in LDV PM emissions. The carbonyl fraction of HDDV POC was lower, 3.3-3.9percent depending upon operational conditions. Partitioning analysis indicates the carbonyls had not achieved equilibrium between the gas- and particle-phase under the dilution factors of 126-584 used in the current study.

  5. N-cyanoimidazole and diimidazole imine: water-soluble condensing agents for the formation of the phosphodiester bond

    NASA Technical Reports Server (NTRS)

    Ferris, J. P.; Huang, C. H.; Hagan, W. J. Jr

    1989-01-01

    The reaction of BrCN with imidazole results in the formation of N-cyanoimidazole and diimidazole imine. These compounds were shown to be useful condensing agents for the formation of the phosphodiester bound in aqueous solution.

  6. The on-surface synthesis of imine-based covalent organic frameworks with non-aromatic linkage.

    PubMed

    Yue, Jie-Yu; Liu, Xuan-He; Sun, Bing; Wang, Dong

    2015-10-01

    A pair of isomeric imine-based covalent organic frameworks with non-aromatic linkage has been fabricated at the graphite surface, which extends the structural diversity of surface covalent organic frameworks. PMID:26271298

  7. Fluxional behavior of a cadmium zwitterion complex: proton transport and tautomerism in methylene chloride solution.

    PubMed

    Anderson, Oren P; la Cour, Agnete; Berg, Andrew; Garrett, Andrew D; Wicholas, Mark

    2003-07-28

    The synthesis and structure of the tautomeric Cd(II) isoindoline zwitterion coordination compound [Cd(4'-MeLH)(NO(3))(2)].CH(3)OH (4'-MeLH = 1,3-bis[2-(4-methylpyridyl)imino]isoindoline) are reported. In methylene chloride solution, tautomer interconversion occurs as the N-H proton moves between the identical imine nitrogen atoms. We report the kinetics of proton transfer as followed by variable temperature (1)H NMR spectroscopy and demonstrate that methanol of solvation and adventitious water facilitate rapid proton transfer. PMID:12870937

  8. Preparation of 3-azoindoles and 3-hydrazonoindolin-2-imines as well as their applications as NNO pincer ligands for boron.

    PubMed

    Ding, Hualong; Peng, Zhixing; Wang, Jinjin; Lu, Ping; Wang, Yanguang

    2016-08-01

    Potassium carbonate-promoted coupling reactions between 3-diazoindolin-2-imines and nucleophiles were tested. By respectively applying 2-naphthalenols and 2-arylacetates as nucleophiles, 3-azoindoles and 3-hydrazonoindolin-2-imines were obtained in excellent yields. Moreover, 3-azoindol-2-amines could be used as NNO pincer ligands for boron and resulted in the formation of hexacycleborofluorides with their absorption around 580 nm in dichloromethane. PMID:27381923

  9. Copper-Catalyzed Enantioselective Addition of Styrene-Derived Nucleophiles to Imines Enabled by Ligand-Controlled Chemoselective Hydrocupration.

    PubMed

    Yang, Yang; Perry, Ian B; Buchwald, Stephen L

    2016-08-10

    The copper-catalyzed intermolecular enantioselective addition of styrenes to imines has been achieved under mild conditions at ambient temperature. This process features the use of styrenes as latent carbanion equivalents via the intermediacy of catalytically generated benzylcopper derivatives, providing an effective means for accessing highly enantiomerically enriched amines bearing contiguous stereocenters. Mechanistic studies shed light on the origin of the preferential styrene hydrocupration in the presence of an imine with the Ph-BPE-derived copper catalyst. PMID:27454393

  10. Infrared spectroscopy of mass-selected metal carbonyl cations

    NASA Astrophysics Data System (ADS)

    Ricks, A. M.; Reed, Z. E.; Duncan, M. A.

    2011-04-01

    Metal carbonyl cations of the form M(CO)n+ are produced in a molecular beam by laser vaporization in a pulsed nozzle source. These ions, and their corresponding rare gas atom "tagged" analogs, M(CO)n(RG)m+, are studied with mass-selected infrared photodissociation spectroscopy in the carbonyl stretching region and with density functional theory computations. The number of infrared-active bands, their frequency positions, and their relative intensities provide distinctive patterns allowing determination of the geometries and electronic structures of these complexes. Cobalt penta carbonyl and manganese hexacarbonyl cations are compared to isoelectronic iron pentacarbonyl and chromium hexacarbonyl neutrals. Gold and copper provide examples of "non-classical" carbonyls. Seven-coordinate carbonyls are explored for the vanadium group metal cations (V +, Nb + and Ta +), while uranium cations provide an example of an eight-coordinate carbonyl.

  11. Detecting a quasi-stable imine species on the reaction pathway of SHV-1 β-lactamase and 6β-(hydroxymethyl)penicillanic acid sulfone.

    PubMed

    Che, Tao; Rodkey, Elizabeth A; Bethel, Christopher R; Shanmugam, Sivaprakash; Ding, Zhe; Pusztai-Carey, Marianne; Nottingham, Michael; Chai, Weirui; Buynak, John D; Bonomo, Robert A; van den Akker, Focco; Carey, Paul R

    2015-01-27

    For the class A β-lactamase SHV-1, the kinetic and mechanistic properties of the clinically used inhibitor sulbactam are compared with the sulbactam analog substituted in its 6β position by a CH2OH group (6β-(hydroxymethyl)penicillanic acid). The 6β substitution improves both in vitro and microbiological inhibitory properties of sulbactam. Base hydrolysis of both compounds was studied by Raman and NMR spectroscopies and showed that lactam ring opening is followed by fragmentation of the dioxothiazolidine ring leading to formation of the iminium ion within 3 min. The iminium ion slowly loses a proton and converts to cis-enamine (which is a β-aminoacrylate) in 1 h for sulbactam and in 4 h for 6β-(hydroxymethyl) sulbactam. Rapid mix-rapid freeze Raman spectroscopy was used to follow the reactions between the two sulfones and SHV-1. Within 23 ms, a 10-fold excess of sulbactam was entirely hydrolyzed to give a cis-enamine product. In contrast, the 6β-(hydroxymethyl) sulbactam formed longer-lived acyl-enzyme intermediates that are a mixture of imine and enamines. Single crystal Raman studies, soaking in and washing out unreacted substrates, revealed stable populations of imine and trans-enamine acyl enzymes. The corresponding X-ray crystallographic data are consonant with the Raman data and also reveal the role played by the 6β-hydroxymethyl group in retarding hydrolysis of the acyl enzymes. The 6β-hydroxymethyl group sterically hinders approach of the water molecule as well as restraining the side chain of E166 that facilitates hydrolysis. PMID:25536850

  12. Detecting a Quasi-stable Imine Species on the Reaction Pathway of SHV-1 β-Lactamase and 6β-(Hydroxymethyl)penicillanic Acid Sulfone

    PubMed Central

    2015-01-01

    For the class A β-lactamase SHV-1, the kinetic and mechanistic properties of the clinically used inhibitor sulbactam are compared with the sulbactam analog substituted in its 6β position by a CH2OH group (6β-(hydroxymethyl)penicillanic acid). The 6β substitution improves both in vitro and microbiological inhibitory properties of sulbactam. Base hydrolysis of both compounds was studied by Raman and NMR spectroscopies and showed that lactam ring opening is followed by fragmentation of the dioxothiazolidine ring leading to formation of the iminium ion within 3 min. The iminium ion slowly loses a proton and converts to cis-enamine (which is a β-aminoacrylate) in 1 h for sulbactam and in 4 h for 6β-(hydroxymethyl) sulbactam. Rapid mix–rapid freeze Raman spectroscopy was used to follow the reactions between the two sulfones and SHV-1. Within 23 ms, a 10-fold excess of sulbactam was entirely hydrolyzed to give a cis-enamine product. In contrast, the 6β-(hydroxymethyl) sulbactam formed longer-lived acyl–enzyme intermediates that are a mixture of imine and enamines. Single crystal Raman studies, soaking in and washing out unreacted substrates, revealed stable populations of imine and trans-enamine acyl enzymes. The corresponding X-ray crystallographic data are consonant with the Raman data and also reveal the role played by the 6β-hydroxymethyl group in retarding hydrolysis of the acyl enzymes. The 6β-hydroxymethyl group sterically hinders approach of the water molecule as well as restraining the side chain of E166 that facilitates hydrolysis. PMID:25536850

  13. Autoinduced catalysis and inverse equilibrium isotope effect in the frustrated Lewis pair catalyzed hydrogenation of imines.

    PubMed

    Tussing, Sebastian; Greb, Lutz; Tamke, Sergej; Schirmer, Birgitta; Muhle-Goll, Claudia; Luy, Burkhard; Paradies, Jan

    2015-05-26

    The frustrated Lewis pair (FLP)-catalyzed hydrogenation and deuteration of N-benzylidene-tert-butylamine (2) was kinetically investigated by using the three boranes B(C6F5)3 (1), B(2,4,6-F3-C6H2)3 (4), and B(2,6-F2-C6H3)3 (5) and the free activation energies for the H2 activation by FLP were determined. Reactions catalyzed by the weaker Lewis acids 4 and 5 displayed autoinductive catalysis arising from a higher free activation energy (2 kcal mol(-1)) for the H2 activation by the imine compared to the amine. Surprisingly, the imine reduction using D2 proceeded with higher rates. This phenomenon is unprecedented for FLP and resulted from a primary inverse equilibrium isotope effect. PMID:25877865

  14. C70 as a Photocatalyst for Oxidation of Secondary Benzylamines to Imines.

    PubMed

    Kumar, Rakesh; Gleissner, Eva H; Tiu, Elisha Gabrielle V; Yamakoshi, Yoko

    2016-01-15

    Photosensitive C70 was used for the catalytic oxidation of benzylamines to the corresponding imines. The advantages of using C70 compared to C60 or other commonly used photosensitizers such as tetraphenylporphyrin (TPP) are (1) faster reaction rates, especially under lower energy of light sources, (2) clean reactions with simple workup without chromatography, and (3) lower catalyst loadings. The reactions were suitable for various benzylamine derivatives. Subsequent nucleophilic additions to the imines were successfully carried out on substituted products. Quenching experiments in the presence of DABCO and benzoquinone implicate the involvement of the singlet oxygen ((1)O2) and the superoxide radical anion (O2(•-)) as important reactive species in the oxidation. PMID:26700114

  15. Generation and exploitation of acyclic azomethine imines in chiral Brønsted acid catalysis

    NASA Astrophysics Data System (ADS)

    Hashimoto, Takuya; Kimura, Hidenori; Kawamata, Yu; Maruoka, Keiji

    2011-08-01

    Successful implementation of a catalytic asymmetric synthesis strategy to produce enantiomerically enriched compounds requires the adoption of suitable prochiral substrates. The combination of an azomethine imine electrophile with various nucleophiles could give straightforward access to a number of synthetically useful chiral hydrazines, but is used rarely. Here we report the exploitation of acyclic azomethine imines as a new type of prochiral electrophile. They can be generated in situ by the condensation of N‧-benzylbenzoylhydrazide with a variety of aldehydes in the presence of a catalytic amount of an axially chiral dicarboxylic acid. By trapping these electrophiles with alkyl diazoacetate or (diazomethyl)phosphonate nucleophiles, we produced a diverse array of chiral α-diazo-β-hydrazino esters and phosphonates with excellent enantioselectivities.

  16. Chemoselective Intramolecular Carbonyl Ylide Formation through Electronically Differentiated Malonate Diesters.

    PubMed

    Nakhla, Mina C; Lee, Che-Wah; Wood, John L

    2015-12-01

    A method for chemoselective carbonyl ylide formation utilizing the Rh(II) catalyzed decomposition of electronically differentiated diazo malonates is disclosed. Treatment of ethyl, trifluoro ethyl diazo malonate with a Rh(II) catalyst selectively forms a carbonyl ylide from the relatively electron rich ethyl ester. This carbonyl ylide can be trapped by various alkynes giving highly functionalized oxabicyclic compounds in a chemo-, regio-, and diastereoselective fashion. PMID:26584509

  17. Acute inhalation toxicity of carbonyl sulfide

    SciTech Connect

    Benson, J.M.; Hahn, F.F.; Barr, E.B.

    1995-12-01

    Carbonyl sulfide (COS), a colorless gas, is a side product of industrial procedures sure as coal hydrogenation and gasification. It is structurally related to and is a metabolite of carbon disulfide. COS is metabolized in the body by carbonic anhydrase to hydrogen sulfide (H{sub 2}S), which is thought to be responsible for COS toxicity. No threshold limit value for COS has been established. Results of these studies indicate COS (with an LC{sub 50} of 590 ppm) is slightly less acutely toxic than H{sub 2}S (LC{sub 50} of 440 ppm).

  18. N-Aryl-oxazolidin-2-imine Muscle Selective Androgen Receptor Modulators Enhance Potency through Pharmacophore Reorientation

    SciTech Connect

    Nirschl, Alexandra A.; Zou, Yan; Krystek, Jr., Stanley R.; Sutton, James C.; Simpkins, Ligaya M.; Lupisella, John A.; Kuhns, Joyce E.; Seethala, Ramakrishna; Golla, Rajasree; Sleph, Paul G.; Beehler, Blake C.; Grover, Gary J.; Egan, Donald; Fura, Aberra; Vyas, Viral P.; Li, Yi-Xin; Sack, John S.; Kish, Kevin F.; An, Yongmi; Bryson, James A.; Gougoutas, Jack Z.; DiMarco, John; Zahler, Robert; Ostrowski, Jacek; Hamann, Lawrence G.

    2010-11-09

    A novel selective androgen receptor modulator (SARM) scaffold was discovered as a byproduct obtained during synthesis of our earlier series of imidazolidin-2-ones. The resulting oxazolidin-2-imines are among the most potent SARMs known, with many analogues exhibiting sub-nM in vitro potency in binding and functional assays. Despite the potential for hydrolytic instability at gut pH, compounds of the present class showed good oral bioavailability and were highly active in a standard rodent pharmacological model.

  19. Tissue-Integratable and Biocompatible Photogelation by the Imine Crosslinking Reaction.

    PubMed

    Yang, Yunlong; Zhang, Jieyuan; Liu, Zhenzhen; Lin, Qiuning; Liu, Xiaolin; Bao, Chunyan; Wang, Yang; Zhu, Linyong

    2016-04-01

    A novel photogelling mechanism by the phototriggered-imine-crosslinking (PIC) reaction is demonstrated. Hyaluronic acid grafted with o-nitrobenzene, a photogenerated aldehyde group, can quickly photo-crosslink with amino-bearing polymers or proteins. Once the in situ photogelling on a wound occurs, the PIC gelling process can well integrate a hydrogel with surrounding tissue by covalent bonding, thus making it a powerful tool for tissue engineering and regenerative medicine. PMID:26840751

  20. Chiral Phosphoric Acid-Catalyzed Enantioselective Formal [3+2] Cycloaddition of Azomethine Imines with Enecarbamates.

    PubMed

    Wang, Yang; Wang, Qian; Zhu, Jieping

    2016-06-01

    The first catalytic asymmetric inverse electron demand 1,3-dipolar cycloaddition of azomethine imines with enecarbamates has been developed. Isoquinoline-fused pyrazolidines containing two or three contiguous stereogenic centers were obtained in high yields with excellent regio-, diastereo-, and enantioselectivities. The pyrazolidine ring can be opened to install an aminal, α-amino nitrile, or homoallylamine function with an excellent control of the newly generated stereogenic center. Access to aminobenzo[a]quinolizidine is also documented. PMID:27135440

  1. Chain Walking of Allylrhodium Species Towards Esters During Rhodium‐Catalyzed Nucleophilic Allylations of Imines

    PubMed Central

    Martínez, Jose I.; Smith, Joshua J.; Hepburn, Hamish B.

    2015-01-01

    Abstract Allylrhodium species derived from δ‐trifluoroboryl β,γ‐unsaturated esters undergo chain walking towards the ester moiety. The resulting allylrhodium species react with imines to give products containing two new stereocenters and a Z‐alkene. By using a chiral diene ligand, products can be obtained with high enantioselectivities, where a pronounced matched/mismatched effect with the chirality of the allyltrifluoroborate is evident. PMID:26756445

  2. Chain Walking of Allylrhodium Species Towards Esters During Rhodium-Catalyzed Nucleophilic Allylations of Imines.

    PubMed

    Martínez, Jose I; Smith, Joshua J; Hepburn, Hamish B; Lam, Hon Wai

    2016-01-18

    Allylrhodium species derived from δ-trifluoroboryl β,γ-unsaturated esters undergo chain walking towards the ester moiety. The resulting allylrhodium species react with imines to give products containing two new stereocenters and a Z-alkene. By using a chiral diene ligand, products can be obtained with high enantioselectivities, where a pronounced matched/mismatched effect with the chirality of the allyltrifluoroborate is evident. PMID:26756445

  3. Development of new hydrogenations of imines and benign reductive hydroaminations: zinc triflate as a catalyst.

    PubMed

    Werkmeister, Svenja; Fleischer, Steffen; Zhou, Shaolin; Junge, Kathrin; Beller, Matthias

    2012-04-01

    The hydrogenation of imines to amines in the presence of catalytic amounts of zinc triflate has been demonstrated for the first time. In addition, an efficient procedure for the reductive hydroamination of alkynes to amines is presented using zinc triflate as a catalyst precursor. In both protocols a variety of different functional groups are tolerated, and the reactions proceed smoothly in high yields. PMID:22323333

  4. N-Methylimidazole Promotes the Reaction of Homophthalic Anhydride with Imines

    PubMed Central

    2015-01-01

    The addition of N-methylimidazole (NMI) to the reaction of homophthalic anhydride with imines such as pyridine-3-carboxaldehyde-N-trifluoroethylimine (9) reduces the amount of elimination byproduct and improves the yield of the formal cycloadduct, tetrahydroisoquinolonic carboxylate 10. Carboxanilides of such compounds are of interest as potential antimalarial agents. A mechanism that rationalizes the role of NMI is proposed, and a gram-scale procedure for the synthesis and resolution of 10 is also described. PMID:25036978

  5. A computational method to predict carbonylation sites in yeast proteins.

    PubMed

    Lv, H Q; Liu, J; Han, J Q; Zheng, J G; Liu, R L

    2016-01-01

    Several post-translational modifications (PTM) have been discussed in literature. Among a variety of oxidative stress-induced PTM, protein carbonylation is considered a biomarker of oxidative stress. Only certain proteins can be carbonylated because only four amino acid residues, namely lysine (K), arginine (R), threonine (T) and proline (P), are susceptible to carbonylation. The yeast proteome is an excellent model to explore oxidative stress, especially protein carbonylation. Current experimental approaches in identifying carbonylation sites are expensive, time-consuming and limited in their abilities to process proteins. Furthermore, there is no bioinformational method to predict carbonylation sites in yeast proteins. Therefore, we propose a computational method to predict yeast carbonylation sites. This method has total accuracies of 86.32, 85.89, 84.80, and 86.80% in predicting the carbonylation sites of K, R, T, and P, respectively. These results were confirmed by 10-fold cross-validation. The ability to identify carbonylation sites in different kinds of features was analyzed and the position-specific composition of the modification site-flanking residues was discussed. Additionally, a software tool has been developed to help with the calculations in this method. Datasets and the software are available at https://sourceforge.net/projects/hqlstudio/ files/CarSpred.Y/. PMID:27420944

  6. Facile Access to Stable Silylium Ions Stabilized by N-Heterocyclic Imines.

    PubMed

    Ochiai, Tatsumi; Szilvási, Tibor; Inoue, Shigeyoshi

    2016-01-01

    Novel silylium ions with N-heterocyclic imines were successfully synthesized. The reaction of trimethylsilyl imidazolin-2-imine Me₃SiNIPr (NIPr = bis(2,6-diisopropylphenyl)-imidazolin-2-imino) with B(C₆F₅)₃ leads to dimeric imino-substituted silylium ions through a methyl group abstraction on the silicon atom. Meanwhile, the intermolecular imino-coordinated silylium ion is formed by using the less sterically crowded imine Me₃SiNItBu (NItBu = bis(tert-butyl)-imidazolin-2-imino). Furthermore, the treatment of dimethylchlorosilane Me₂(Cl)SiNIPr with AgOTf affords the contact ion pair Me₂(OTf)SiNIPr by substitution of the chloride. A novel complex with the formula [Me₂(DMAP)SiNIPr][OTf] was prepared by coordination with 4-dimethylamino-pyridine (DMAP). In the solid state, the DMAP adduct [Me₂(DMAP)SiNIPr][OTf] contains a distinct [Me₂(DMAP)SiNIPr]⁺ moiety. PMID:27589708

  7. Kinetics and Mechanism of the Gas-Phase Reaction of Selected Carbonyls with Cl Atoms between 250 and 340 K

    NASA Astrophysics Data System (ADS)

    Hasson, A. S.; Algrim, L.; Abdelhamid, A.; Tyndall, G. S.; Orlando, J. J.

    2013-12-01

    Carbonyls are important products from the gas phase degradation of most volatile organic compounds. Their atmospheric reactions therefore have a significant impact on atmospheric composition, particularly in aged air masses. While the reactions of short-chain linear carbonyls are well understood, the chemistry of larger (> C6) and branched carbonyl is more uncertain. To provide insight into these reactions, the reactions of three carbonyls (methyl isopropyl ketone, MIK; di-isopropyl ketone, DIK; and diethyl ketone, DEK) with chlorine atoms were investigated between 250 and 340 K and 1 atm in the presence and absence of NOx and an HO2 source (methanol). Experiments were performed in a photochemical reactor using a combination of long-path Fourier transform infra-red spectroscopy, proton transfer reaction mass spectrometry and gas chromatography with flame ionization detection. The kinetics were studied using the relative rate technique with butanone and isopropanol as the reference compounds. The Arrhenius expression for the three rate coefficients was determined to be k(DEK+Cl) = 3.87 x 10-11e(2 × 7 kJ/mol)/RT cm3 molecules-1 s-1 , k(MIPK+Cl) = 7.20 x 10-11e(0.2× 8 kJ/mol)/RT cm3 molecules-1 s-1 , and k(DIPK+Cl) = 3.33 x 10-10e(-3× 8 kJ/mol)/RT cm3 molecules-1 s-1 . Measured reaction products accounted for 38-72 % of the reacted carbon and were consistent with strong deactivation of the carbon atom adjacent to the carbonyl group with respect to H-atom abstraction by Cl atoms. The product distributions also provide insight into radical recycling from the organic peroxy + HO2 reaction, and the relative rates of isomerization, fragmentation and reaction with O2 for carbonyl-containing alkoxy radicals. Implications of these results will be discussed.

  8. Formation of Small Gas Phase Carbonyls from Heterogeneous Oxidation of Polyunsaturated Fatty Acids (PUFA)

    NASA Astrophysics Data System (ADS)

    Zhou, S.; Zhao, R.; Lee, A.; Gao, S.; Abbatt, J.

    2011-12-01

    Fatty acids (FAs) are emitted into the atmosphere from gas and diesel powered vehicles, cooking, plants, and marine biota. Field measurements have suggested that FAs, including polyunsaturated fatty acids (PUFA), could make up an important contribution to the organic fraction of atmospheric aerosols. Due to the existence of carbon-carbon double bonds in their molecules, PUFA are believed to be highly reactive towards atmospheric oxidants such as OH and NO3 radicals and ozone, which will contribute to aerosol hygroscopicity and cloud condensation nuclei activity. Previous work from our group has shown that small carbonyls formed from the heterogeneous reaction of linoleic acid (LA) thin films with gas-phase O3. It is known that the formation of small carbonyls in the atmosphere is not only relevant to the atmospheric budget of volatile organic compounds but also to secondary organic aerosol formation. In the present study, using an online proton transfer reaction mass spectrometry (PTR-MS) and off-line gas chromatography-mass spectrometry (GC-MS) we again investigated carbonyl formation from the same reaction system, i.e. the heterogeneous ozonolysis of LA film. In addition to the previously reported carbonyls, malondialdehyde (MDA), a source of reactive oxygen species that is mutagenic, has been identified as a product for the first time. Small dicarbonyls, e.g. glyoxal, are expected to be formed from the further oxidation of MDA. In this presentation, the gas-phase chemistry of MDA with OH radicals using a newly built Teflon chamber in our group will also be presented.

  9. Stereochemistry and Mechanistic Insight in the [2(k)+2(i)+2(i)] Annulations of Ketenes and Imines.

    PubMed

    Yang, Zhanhui; He, Wei; Cheng, Baoxiang; Xu, Jiaxi

    2016-06-01

    The stereochemistry and mechanistic insight in the annulations of one ketene molecule with two imine molecules ([2(k)+2(i)+2(i)] annulation) are studied by using six-membered 3,4-dihydroisoquinoline as an imine probe. A concerted hetero-Diels-Alder cycloaddition mechanism is proposed to explain the stereochemical outcomes. In most cases, the zwitterionic 2-aza-1,3-butadiene-type intermediates, generated from ketenes and imines, undergo endo hetero-Diels-Alder cycloaddition with the second imine molecule. For ketenes with electron-donating substituents, (2,4)-cis-(4,5)-cis-[2(k)+2(i)+2(i)] annuladducts formed stereospecifically, while, for ketenes with electron-accepting substituents, (2,4)-cis-(4,5)-trans-[2(k)+2(i)+2(i)] annuladducts are generated stereospecifically. The [2(k)+2(i)+2(i)] annulations of aryloxyketenes and 3,4-dihydroisoquinoline give stereodivergent products due to the occurrence of the stepwise nucleophilic annulation. However, in the [2(k)+2(i)+2(i)] annulations of seven-membered cyclic imine dibenzo[b,f][1,4]oxazepine, the zwitterionic aza-butadiene-type intermediates exclusively undergo exo hetero-Diels-Alder cycloadditions with another molecule of imine to yield (2,4)-trans-(4,5)-trans-[2(k)+2(i)+2(i)] annuladducts stereospecifically, regardless of the ketene substituents. The mechanistic model not only discloses the nature of the [2(k)+2(i)+2(i)] annulations, but also can be used to explain and predict the stereochemistry of the [2(k)+2(i)+2(i)] annuladducts from different ketenes and imines. PMID:27166848

  10. Carbonyl emissions in diesel and biodiesel exhaust

    NASA Astrophysics Data System (ADS)

    Machado Corrêa, Sérgio; Arbilla, Graciela

    With the use of biodiesel in clear growth, it is important to quantify any potential emission benefits or liabilities of this fuel. Several researches are available concerning the regulated emissions of biodiesel/diesel blends, but there is a lack of information about non-regulated emissions. In a previous paper [Corrêa, S.M., Arbilla, G., 2006. Emissões de formaldeído e acetaldeído de misturas biodiesel/diesel. Periódico Tchê Química, 3, 54-68], the emissions of aromatic hydrocarbons were reported. In this work, seven carbonyl emissions (formaldehyde, acetaldehyde, acrolein, acetone, propionaldehyde, butyraldehyde, and benzaldehyde) were evaluated by a heavy-duty diesel engine fueled with pure diesel (D) and biodiesel blends (v/v) of 2% (B2), 5% (B5), 10% (B10), and 20% (B20). The tests were conducted using a six cylinder heavy-duty engine, typical of the Brazilian fleet of urban buses, in a steady-state condition under 1000, 1500, and 2000 rpm. The exhaust gases were diluted nearly 20 times and the carbonyls were sampled with SiO 2-C18 cartridges, impregnated with acid solution of 2,4-dinitrophenylhydrazine. The chemical analyses were performed by high performance liquid chromatography using UV detection. Using average values for the three modes of operation (1000, 1500, and 2000 rpm) benzaldehyde showed a reduction on the emission (-3.4% for B2, -5.3% for B5, -5.7% for B10, and -6.9% for B20) and all other carbonyls showed a significative increase: 2.6, 7.3, 17.6, and 35.5% for formaldehyde; 1.4, 2.5, 5.4, and 15.8% for acetaldehyde; 2.1, 5.4, 11.1, and 22.0% for acrolein+acetone; 0.8, 2.7, 4.6, and 10.0% for propionaldehyde; 3.3, 7.8, 16.0, and 26.0% for butyraldehyde.

  11. The Hydrolysis of Carbonyl Sulfide at Low Temperature: A Review

    PubMed Central

    Zhao, Shunzheng; Yi, Honghong; Tang, Xiaolong; Jiang, Shanxue; Gao, Fengyu; Zhang, Bowen; Zuo, Yanran; Wang, Zhixiang

    2013-01-01

    Catalytic hydrolysis technology of carbonyl sulfide (COS) at low temperature was reviewed, including the development of catalysts, reaction kinetics, and reaction mechanism of COS hydrolysis. It was indicated that the catalysts are mainly involved metal oxide and activated carbon. The active ingredients which can load on COS hydrolysis catalyst include alkali metal, alkaline earth metal, transition metal oxides, rare earth metal oxides, mixed metal oxides, and nanometal oxides. The catalytic hydrolysis of COS is a first-order reaction with respect to carbonyl sulfide, while the reaction order of water changes as the reaction conditions change. The controlling steps are also different because the reaction conditions such as concentration of carbonyl sulfide, reaction temperature, water-air ratio, and reaction atmosphere are different. The hydrolysis of carbonyl sulfide is base-catalyzed reaction, and the force of the base site has an important effect on the hydrolysis of carbonyl sulfide. PMID:23956697

  12. Enantioselective Protonation

    PubMed Central

    Mohr, Justin T.; Hong, Allen Y.; Stoltz, Brian M.

    2010-01-01

    Enantioselective protonation is a common process in biosynthetic sequences. The decarboxylase and esterase enzymes that effect this valuable transformation are able to control both the steric environment around the proton acceptor (typically an enolate) and the proton donor (typically a thiol). Recently, several chemical methods to achieve enantioselective protonation have been developed by exploiting various means of enantiocontrol in different mechanisms. These laboratory transformations have proven useful for the preparation of a number of valuable organic compounds. PMID:20428461

  13. Carbonyl Emissions From Oil and Gas Production Facilities

    NASA Astrophysics Data System (ADS)

    Lyman, S. N.; O'Neil, T.; Tran, T.

    2015-12-01

    A number of recent studies have targeted emissions of methane and other hydrocarbons from oil and gas exploration and production activity. These measurements are greatly increasing understanding of the atmospheric impacts of oil and gas development. Very few measurements exist, however, of emissions of formaldehyde and other carbonyls from oil and gas equipment. Carbonyls are toxic and serve as important ozone precursors, especially during winter ozone episodes in places like Utah's Uintah Basin. Current air quality models are only able to reproduce observed high wintertime ozone if they incorporate emissions inventories with very high carbonyl emissions. We measured carbonyl emissions from oil and gas equipment and facilities—including glycol dehydrators, liquid storage tanks, raw gas leaks, raw gas-burning engines, and produced water surface impoundments—in Rocky Mountain oil and gas fields. Carbonyl emissions from raw gas were below detection, but emissions of formaldehyde, acetaldehyde, and other carbonyls were detected from liquid storage tanks, glycol dehydrators, and other oil and gas equipment. In some cases, carbonyls may be formed from the degradation of methanol and other chemicals used in oil and gas production, but the collected data provide evidence for other non-combustion formation pathways. Raw gas-burning engines also emitted carbonyls. Emissions from all measured sources were a small fraction of total volatile organic compound emissions. We incorporated our measurements into an emissions inventory, used that inventory in an air quality model (WRF-SMOKE-CAMx), and were unable to reproduce observed high wintertime ozone. This could be because (1) emission sources we have not yet measured, including compressors, gas processing plants, and others, are large; (2) non-carbonyl emissions, especially those that quickly degrade into carbonyls during photochemical processing, are underestimated in the inventory; or (3) the air quality model is unable

  14. Detection of carbonyl fluoride in the stratosphere

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Park, J. H.; Russell, J. M., III; Zander, R.; Brown, L. R.; Farmer, C. B.; Norton, R. H.; Raper, O. F.

    1986-01-01

    Infrared solar absorption spectra of the stratosphere recorded at a resolution of 0.01/cm by the ATMOS (Atmospheric Trace Molecule Spectroscopy) instrument from onboard Spacelab 3 (04/30 to 05/6/85) have revealed the existence of many previously unobserved absorption features in the 1925 to 1960/cm and 1249 to 1255/cm regions and one at 774/cm. On the basis of comparisons with laboratory spectra, these features have been identified as belonging to the nu1, nu4, and nu6 bands of carbonyl fluoride, respectively. Volume mixing ratios of COF2 between 17 and 40 km have been deduced from analysis of the nu1 and nu6 bands.

  15. Absorption of carbonyl sulfide in aqueous methyldiethanolamine

    SciTech Connect

    Al-Ghawas, H.A.; Ruiz-Ibanez, G.; Sandall, O.C. )

    1988-01-01

    The absorption of carbonyl sulfide in aqueous methyldiethanolamine (MDEA) was studied over a range of temperatures and MDEA concentrations. MDEA is commonly used for selective absorption of hydrogen sulfide in the presence of carbon dioxide. However, sulfur in the form of COS may also be present and it is necessary that estimates of absorption rates of this compound be made. The objective of this study is to determine the physiochemical properties needed to predict COS absorption rates in aqueous MDEA. Free gas solubility and the diffusivity of COS in MDEA solutions were measured over the temperature range 15 to 40{sup 0}C for MDEA concentrations up to 30 weight per cent using the nitrous oxide analogy method. Solubilities were measured volumetrically in an equilibrium cell and diffusivities were measured using a laminar liquid jet absorber. The kinetics of the reaction between COS and MDEA were studied by measuring absorption rates in a single wetted-sphere absorber.

  16. Metal-free carbonylations by photoredox catalysis.

    PubMed

    Majek, Michal; Jacobi von Wangelin, Axel

    2015-02-01

    The synthesis of benzoates from aryl electrophiles and carbon monoxide is a prime example of a transition-metal-catalyzed carbonylation reaction which is widely applied in research and industrial processes. Such reactions proceed in the presence of Pd or Ni catalysts, suitable ligands, and stoichiometric bases. We have developed an alternative procedure that is free of any metal, ligand, and base. The method involves a redox reaction driven by visible light and catalyzed by eosin Y which affords alkyl benzoates from arene diazonium salts, carbon monoxide, and alcohols under mild conditions. Tertiary esters can also be prepared in high yields. DFT calculations and radical trapping experiments support a catalytic photoredox pathway without the requirement for sacrificial redox partners. PMID:25414135

  17. Atmospheric carbonyl sulfide exchange in bog microcosms

    SciTech Connect

    Fried, A.; Klinger, L.F.; Erickson, D.J. III )

    1993-01-22

    Measurements of Carbonyl sulfide (OCS) fluxes were carried out on bog microcosms using chamber sampling and tunable diode laser analysis. Intact bog microcosms (vascular plants, mosses, and peat) removed ambient levels of OCS in the light and dark with rates from [minus]2.4 to [minus]8.1 ng S min[sup [minus]1] m[sup [minus]2]. Peat and peat plus mosses emitted OCS in the light with rates of 17.4 and 10.9 ng S min[sup [minus]1] m[sup [minus]2], respectively. In the dark, the mosses apparently removed OCS at a rate equivalent to the peat emissions. A 3-D numerical tracer model using this data indicated that boreal bog ecosystems remove at most 1% of ambient OCS, not sufficient to account for an observed OCS depletion in boreal air masses. 13 refs., 1 fig., 1 tab.

  18. The crystal structure and physicochemical characteristics of 2-hydroxy-N-[3(5)-pyrazolyl]-1,4-naphthoquinone-4-imine, a new antitrypanosomal compound.

    PubMed

    Sperandeo, Norma R; Karlsson, Alicia; Cuffini, Silvia; Pagola, Silvina; Stephens, Peter W

    2005-01-01

    This study was designed to investigate the physical characteristics and crystalline structure of 2-hydroxy-N-[3(5)-pyrazolyl]-1,4-naphthoquinone-4-imine (PNQ), a new active compound against Trypanosoma cruzi, the causative agent of American trypanosomiasis. Methods used included differential scanning calorimetry, thermogravimetry, hot stage microscopy, polarized light microscopy (PLM), Fourier-transform infrared (FTIR) spectroscopy, and high-resolution X-ray powder diffraction (HR-XRPD). According to PLM and HR-XRPD data, PNQ crystallized as red oolitic crystals (absolute methanol) or prisms (dimethyl sulfoxide [DMSO]-water) with the same internal structure. The findings obtained with HR-XRPD data (applying molecular location methods) showed a monoclinic unit cell [a = 18.4437(1) A, b = 3.9968(2) A, c = 14.5304(1) A, alpha = 90 degrees , beta = 102.71(6) degrees , gamma = 90 degrees , V = 1044.9(1) A(3), Z = 4, space group P2(1)/c], and a crystal structure (excluding H-positions) described by parallel layers in the direction of the b-axis, with molecules held by homochemical (phenyl-phenyl and pyrazole-pyrazole) van der Waals interactions. In addition, FTIR spectra displayed the NH-pyrazole stretch overlapped with the OH absorption at 3222 cm(-1), typical of -NH and -OH groups associated through H-bondings; and a carbonyl stretching absorption at 1694 cm(-1), indicating a nonextensively H-bonded quinonic C=O, which was in accordance with the solved crystal structure of PNQ. The existence of such cohesive forces shed light on the thermoanalytical data, which revealed that PNQ is a stable solid, unaffected by oxygen that decomposed without melting above 260 degrees C. PMID:16408868

  19. Reductive carbonylation of aromatic nitro compounds

    SciTech Connect

    Wehman, P.; Kamer, P.C.J.; Leeuwen, P.W.N.M. van

    1995-12-31

    In the reductive carbonylation of aromatic nitro compounds carbamates and isocyanates are prepared through a direct reaction between the nitro group and CO under the influence of a catalyst. This route avoids the major disadvantages of the traditional process for the production of the industrially important isocyanates and carbamates. The authors have developed a stable, active, and rather selective homogeneous palladium catalyst for the reductive carbonylation of the nitro substrate. Best results were obtained with Pd-phenanthroline complexes in which the ligands bear moderately donating substituents. Noncoordinating anions in the catalyst complex are clearly preferable. The highest activity was reached with the Pd(4,7-Me{sub 2}-1,10-phen){sub 2}(OTf){sub 2} catalyst complex (t.o.f. = 311 mol/mol/h, selectivity toward the desired carbamate = 84%). With the Pd(1,10-phenanthroline){sub 2}(OTf){sub 2} catalyst complex, the authors studied the scope of the reaction in order to prepare a wide range of functionalized carbamates for the fine chemistry. During this study, it was found that a remarkable improvement of the catalytic activity and selectivity on addition of a benzoic acid (t.o.f. > 365 mol/mol/h, selectivity toward carbamate = 94%). In the presence of 4-chlorobenzoic acid even aromatic dinitro compounds could be converted easily, resulting in the best results reported ever for the conversion of 1,4-dinitrobenzene into the corresponding dicarbamate (t.o.f. = 73 mol/mol/h, selectivity toward the dicarbamate = 86%).

  20. [Assessment of the concentrations of carbonylated proteins and carbonyl reductase enzyme in mexican women with breast cancer: A pilot study].

    PubMed

    Gutiérrez-Salinas, José; García-Ortiz, Liliana; Mondragón-Terán, Paul; Hernández-Rodríguez, Sergio; Ramírez-García, Sotero; Núñez-Ramos, Norma Rebeca

    2016-01-01

    Oxidative stress could promote the development of cancer and implicate carbonylated proteins in the carcinogenic process. The goal of this study was to assess the concentrations of carbonylated proteins and carbonyl reductase enzyme in women with breast cancer and determine whether these markers were possible indicators of tissue damage caused by the disease. A total of 120 healthy women and 123 women with a diagnosis of breast cancer were included. The concentration of carbonylated proteins in plasma and the concentration of carbonyl reductase enzyme in leukocytes were determined using the ELISA assay. There was a 3.76-fold increase in the amount of carbonylated proteins in the plasma from the patient group compared with healthy control group (5±3.27 vs. 1.33±2.31 nmol carbonyls/mg protein; p<0.05). Additionally, a 60% increase in the carbonyl reductase enzyme was observed in the patient group compared with the healthy control group (3.27±0.124 vs. 2.04±0.11 ng/mg protein; p<0.05). A positive correlation (r=0.95; p<0.001) was found between both measurements. These results suggest the presence of tissue damage produced by cancer; therefore, these parameters could be used to indicate tissue damage in cancer patients. PMID:26927639

  1. Electronic structure and UV spectra of N-arylthio-1,4-benzoquinone imines

    SciTech Connect

    Pirozhenko, V.V.; Boldeskul, I.E.; Kolesnikov, V.T.; Vid, L.V.; Kuz'menko, L.O.

    1986-01-01

    The electronic structure of N-arylthio-1,4-benzoquinone imines (II) was studied by quantum-chemical methods (CNDO/2). It was shown that the special characteristics of the reactivity of the compounds in reaction with chlorine compared with sulfenylketimines R/sub 2/C=N-S-Ar not containing a quinonoid ring may be due to the different nature of the lowest unoccupied molecular orbitals (LUMO). The UV spectra of compounds (II) were investigated. In the visible region the spectra of all the compounds contain strong absorption (R/sub 1/ = R/sub 2/ = R/sub 3/ = R/sub 4/ = R/sub 5/ = H, lambda/sub m/ = 433 nm, epsilon/sub m/ = 2.12 x 10/sup 4/ liters/mole x cm), due to intramolecular charge transfer from the sulfur atom to the quinonoid fragment of the molecule. It was established that there is a linear relation between the energy of the transition and the sigma/sup +/ constants of the substituents in the aryl fragment. The assignment of the transitions was confirmed by calculations of the UV spectra of N-arylthio-1,4-benzoquinone imines by the PPP method. Comparison of the UV spectra of these compounds with the UV spectra of N-arylsulfonyl-1,4-benzoquinone imines makes it possible to conclude that the sulfur atom of the SO/sub 2/ group, unlike the divalent sulfur atom, is not capable of transmitting the electronic effects of the substituents from one part of the molecule to the other.

  2. Strain-Induced Reactivity in the Dynamic Covalent Chemistry of Macrocyclic Imines.

    PubMed

    Ratjen, Lars; Vantomme, Ghislaine; Lehn, Jean-Marie

    2015-07-01

    The displacement of molecular structures from their thermodynamically most stable state by imposition of various types of electronic and conformational constraints generates highly strained entities that tend to release the accumulated strain energy by undergoing either structural changes or chemical reactions. The latter case amounts to strain-induced reactivity (SIR) that may enforce specific chemical transformations. A particular case concerns dynamic covalent chemistry which may present SIR, whereby reversible reactions are activated by coupling to a high-energy state. We herewith describe such a dynamic covalent chemical (DCC) system involving the reversible imine formation reaction. It is based on the formation of strained macrocyclic bis-imine metal complexes in which the macrocyclic ligand is in a high energy form enforced by the coordination of the metal cation. Subsequent demetallation generates a highly strained free macrocycle that releases its accumulated strain energy by hydrolysis and reassembly into a resting state. Specifically, the metal-templated condensation of a dialdehyde with a linear diamine leads to a bis-imine [1+1]-macrocyclic complex in which the macrocyclic ligand is in a coordination-enforced strained conformation. Removal of the metal cation by a competing ligand yields a highly reactive [1+1]-macrocycle, which then undergoes hydrolysis to transient non-cyclic aminoaldehyde species, which then recondense to a strain-free [2+2]-macrocyclic resting state. The process can be monitored by (1) H NMR spectroscopy. Energy differences between different conformational states have been evaluated by Hartree-Fock (HF) computations. One may note that the stabilisation of high-energy molecular forms by metal ion coordination followed by removal of the latter, offers a general procedure for producing out-of-equilibrium molecular states, the fate of which may then be examined, in particular when coupled to dynamic covalent chemical processes. PMID

  3. Three-step metal-promoted allene-based preparation of bis(heterocyclic) cyclophanes from carbonyl compounds.

    PubMed

    Alcaide, Benito; Almendros, Pedro; Quirós, M Teresa; Lázaro, Carlos; Torres, M Rosario

    2014-07-01

    A straightforward metal-mediated method for the synthesis of bis(dihydrofuryl) cyclophane scaffolds from carbonyl compounds has been developed. The combination of the dihydrofuran moiety with different heterocycles such as β-lactams and sugars allows high levels of skeletal diversity. The process comprises indium-promoted one-pot carbonyl bis(allenylation) and gold- or palladium-catalyzed double cyclization in the resulting bis(allenols), followed by selective ruthenium-catalyzed macrocyclization. In some cases, the method has been successfully applied to the synthesis of the challenging Z-isomers. The E- versus Z-stereochemistry of the metathesis-formed double bonds could not be assigned taking into consideration the usual coupling constants criteria, but a diagnostic based on the chemical shifts of the two olefinic protons located at the macrocyclic double bond was established. PMID:24910897

  4. Annulation of Aromatic Imines via Directed C-H BondActivation

    SciTech Connect

    Thalji, Reema K.; Ahrendt, Kateri A.; Bergman, Robert G.; Ellman,Jonathan A.

    2005-04-14

    A directed C-H bond activation approach to the synthesis of indans, tetralins, dihydrofurans, dihydroindoles, and other polycyclic aromatic compounds is presented. Cyclization of aromatic ketimines and aldimines containing alkenyl groups tethered at the meta position relative to the imine directing group has been achieved using (PPh{sub 3}){sub 3}RhCl (Wilkinson's catalyst). The cyclization of a range of aromatic ketimines and aldimines provides bi- and tricyclic ring systems with good regioselectivity. Different ring sizes and substitution patterns can be accessed through the coupling of monosubstituted, 1,1- or 1,2-disubstituted, and trisubstituted alkenes bearing both electron-rich and electron-deficient functionality.

  5. Annulation of aromatic imines via directed C-H bond activation.

    PubMed

    Thalji, Reema K; Ahrendt, Kateri A; Bergman, Robert G; Ellman, Jonathan A

    2005-08-19

    A directed C-H bond activation approach to the synthesis of indans, tetralins, dihydrofurans, dihydroindoles, and other polycyclic aromatic compounds is presented. Cyclization of aromatic ketimines and aldimines containing alkenyl groups tethered at the meta position relative to the imine directing group has been achieved using (PPh3)3RhCl (Wilkinson's catalyst). The cyclization of a range of aromatic ketimines and aldimines provides bi- and tricyclic ring systems with good regioselectivity. Different ring sizes and substitution patterns can be accessed through the coupling of monosubstituted, 1,1- or 1,2-disubstituted, and trisubstituted alkenes bearing both electron-rich and electron-deficient functionality. PMID:16095296

  6. C-H Bond Oxidation Catalyzed by an Imine-Based Iron Complex: A Mechanistic Insight.

    PubMed

    Olivo, Giorgio; Nardi, Martina; Vìdal, Diego; Barbieri, Alessia; Lapi, Andrea; Gómez, Laura; Lanzalunga, Osvaldo; Costas, Miquel; Di Stefano, Stefano

    2015-11-01

    A family of imine-based nonheme iron(II) complexes (LX)2Fe(OTf)2 has been prepared, characterized, and employed as C-H oxidation catalysts. Ligands LX (X = 1, 2, 3, and 4) stand for tridentate imine ligands resulting from spontaneous condensation of 2-pycolyl-amine and 4-substituted-2-picolyl aldehydes. Fast and quantitative formation of the complex occurs just upon mixing aldehyde, amine, and Fe(OTf)2 in a 2:2:1 ratio in acetonitrile solution. The solid-state structures of (L1)2Fe(OTf)(ClO4) and (L3)2Fe(OTf)2 are reported, showing a low-spin octahedral iron center, with the ligands arranged in a meridional fashion. (1)H NMR analyses indicate that the solid-state structure and spin state is retained in solution. These analyses also show the presence of an amine-imine tautomeric equilibrium. (LX)2Fe(OTf)2 efficiently catalyze the oxidation of alkyl C-H bonds employing H2O2 as a terminal oxidant. Manipulation of the electronic properties of the imine ligand has only a minor impact on efficiency and selectivity of the oxidative process. A mechanistic study is presented, providing evidence that C-H oxidations are metal-based. Reactions occur with stereoretention at the hydroxylated carbon and selectively at tertiary over secondary C-H bonds. Isotopic labeling analyses show that H2O2 is the dominant origin of the oxygen atoms inserted in the oxygenated product. Experimental evidence is provided that reactions involve initial oxidation of the complexes to the ferric state, and it is proposed that a ligand arm dissociates to enable hydrogen peroxide binding and activation. Selectivity patterns and isotopic labeling studies strongly suggest that activation of hydrogen peroxide occurs by heterolytic O-O cleavage, without the assistance of a cis-binding water or alkyl carboxylic acid. The sum of these observations provides sound evidence that controlled activation of H2O2 at (LX)2Fe(OTf)2 differs from that occurring in biomimetic iron catalysts described to date. PMID

  7. Kinetic Resolution of 2H-Azirines by Asymmetric Imine Amidation.

    PubMed

    Hu, Haipeng; Liu, Yangbin; Lin, Lili; Zhang, Yuheng; Liu, Xiaohua; Feng, Xiaoming

    2016-08-16

    Highly efficient kinetic resolution of 2H-azirines by an asymmetric imine amidation was achieved in the presence of a chiral N,N'-dioxide/Sc(III) complex, thus providing a promising method to obtain the enantioenriched 2H-azirine derivatives and protecting-group free aziridines at the same time. It is rare to find an example of N1 of an oxindole participating in a reaction over C3. Moreover, chiral 2H-azirines were stereospecifically transformed into an unprotected aziridine and α-amino ketone. PMID:27384910

  8. Seasonal and diurnal characteristics of atmospheric carbonyls in Nanning, China

    NASA Astrophysics Data System (ADS)

    Guo, Songjun; Chen, Mei; Tan, Jihua

    2016-03-01

    For the first time, atmospheric carbonyls were measured to identify seasonal and diurnal variations in Nanning from October 2011 to July 2012. Formaldehyde (6.79 ± 3.39 μg/m3), acetaldehyde (15.81 ± 10.48 μg/m3) and acetone (5.43 ± 6.91 μg/m3) were the three most abundant carbonyls, accounting for ~ 85% of the total carbonyls. The average total concentrations of carbonyls and three abundant carbonyls showed significant high levels in summer compared to those in winter. Diurnal variations suggested that photochemical conditions, combustion of charcoal and straw, and solvent usage are important for the distributions of atmospheric carbonyls. The highest average C1/C2 ratio was observed in summer (0.75) compared to those (0.31-0.70) in other seasons, implying the positive effect of photochemical activities on raising C1/C2 ratio, and the significant low C2/C3 ratio (12.01-18.23) in winter and autumn than those (95.83-24.49) in both spring and summer suggested the important anthropogenic emissions such as charcoal and biomass combustion. O3 formation potentials in summer and spring were significantly higher by ~ 2 times than those in autumn and winter. Formaldehyde and acetaldehyde are the top two carbonyls which contribute 82-97% to total O3 formation potentials.

  9. High throughput assay for evaluation of reactive carbonyl scavenging capacity☆

    PubMed Central

    Vidal, N.; Cavaille, J.P.; Graziani, F.; Robin, M.; Ouari, O.; Pietri, S.; Stocker, P.

    2014-01-01

    Many carbonyl species from either lipid peroxidation or glycoxidation are extremely reactive and can disrupt the function of proteins and enzymes. 4-hydroxynonenal and methylglyoxal are the most abundant and toxic lipid-derived reactive carbonyl species. The presence of these toxics leads to carbonyl stress and cause a significant amount of macromolecular damages in several diseases. Much evidence indicates trapping of reactive carbonyl intermediates may be a useful strategy for inhibiting or decreasing carbonyl stress-associated pathologies. There is no rapid and convenient analytical method available for the assessment of direct carbonyl scavenging capacity, and a very limited number of carbonyl scavengers have been identified to date, their therapeutic potential being highlighted only recently. In this context, we have developed a new and rapid sensitive fluorimetric method for the assessment of reactive carbonyl scavengers without involvement glycoxidation systems. Efficacy of various thiol- and non-thiol-carbonyl scavenger pharmacophores was tested both using this screening assay adapted to 96-well microplates and in cultured cells. The scavenging effects on the formation of Advanced Glycation End-product of Bovine Serum Albumin formed with methylglyoxal, 4-hydroxynonenal and glucose-glycated as molecular models were also examined. Low molecular mass thiols with an α-amino-β-mercaptoethane structure showed the highest degree of inhibitory activity toward both α,β-unsaturated aldehydes and dicarbonyls. Cysteine and cysteamine have the best scavenging ability toward methylglyoxal. WR-1065 which is currently approved for clinical use as a protective agent against radiation and renal toxicity was identified as the best inhibitor of 4-hydroxynonenal. PMID:24688895

  10. Synthesis of a Two-Dimensional Covalent Organic Monolayer through Dynamic Imine Chemistry at the Air/Water Interface.

    PubMed

    Dai, Wenyang; Shao, Feng; Szczerbiński, Jacek; McCaffrey, Ryan; Zenobi, Renato; Jin, Yinghua; Schlüter, A Dieter; Zhang, Wei

    2016-01-01

    A two-dimensional covalent organic monolayer was synthesized from simple aromatic triamine and dialdehyde building blocks by dynamic imine chemistry at the air/water interface (Langmuir-Blodgett method). The obtained monolayer was characterized by optical microscopy, scanning electron microscopy, and atomic force microscopy, which unambiguously confirmed the formation of a large (millimeter range), unimolecularly thin aromatic polyimine sheet. The imine-linked chemical structure of the obtained monolayer was characterized by tip-enhanced Raman spectroscopy, and the peak assignment was supported by spectra simulated by density functional theory. Given the modular nature and broad substrate scope of imine formation, the work reported herein opens up many new possibilities for the synthesis of customizable 2D polymers and systematic studies of their structure-property relationships. PMID:26768822

  11. Synthesis, Spectral investigation (¹H, ¹³C) and Anti-microbial Screening of benzophenone imines.

    PubMed

    Khosa, Muhammad Kaleem; Jamal, Muhammad Asghar; Saif, Muhammad Jawad; Muneer, Majid; Rehman, Fazalur; Farman, Muhammad; Shoaib, Hafiz Muhammad; Shahid, Muhammad; Hameed, Shabnam

    2015-11-01

    New series of benzophenone imines with general formula Ph2-C=NR; R = Benzyl, 4-Fluorobenzyl, Naphthyl, Phenyl, 4-Nitrophenyl were synthesized by condensation of dichlorodiphenylmethane and different aromatic primary amines (1:1) Those imines were characterized by different physiochemical and spectroscopic techniques like melting point, elemental analysis, FT-IR, multinuclear NMR (¹H, ¹³C). After characterization, imines were subjected to anti-microbial activities. All compounds showed promising activity against different bacterial strains like Escherichia coli, Bacillussubtilis, Pasturellam ultocida and Staphylococcus aureus as well as fungal strains like Alternata alternaria, Ganoderma lucidium, Penicillium notatum and Trichoderma harzianum using Amoxicillin and Flucanazole as a standard drugs respectively. PMID:26639485

  12. Controlling stereoselectivity in the aminocatalytic enantioselective Mannich reaction of aldehydes with in situ generated N-carbamoyl imines.

    PubMed

    Galzerano, Patrizia; Agostino, Dario; Bencivenni, Giorgio; Sambri, Letizia; Bartoli, Giuseppe; Melchiorre, Paolo

    2010-05-25

    A simple and convenient method for the direct, aminocatalytic, and highly enantioselective Mannich reactions of aldehydes with in situ generated N-carbamoyl imines has been developed. Both alpha-imino esters and aromatic imines serve as suitable electrophilic components. Moreover, the judicious selection of commercially available secondary amine catalysts allows selective access to the desired stereoisomer of the N-tert-butoxycarbonyl (Boc) or N-carbobenzyloxy (Cbz) Mannich adducts, with high control over the syn or anti relative configuration and almost perfect enantioselectivity. Besides the possibility to fully control the stereochemistry of the Mannich reaction, the main advantage of this method lies in the operational simplicity; the highly reactive N-carbamate-protected imines are generated in situ from stable and easily handled alpha-amido sulfones. PMID:20397160

  13. Design, synthesis, and characterization of TPA-thiophene-based amide or imine functionalized molecule for potential optoelectronic devices

    NASA Astrophysics Data System (ADS)

    Sarswat, Prashant K.; Sathyapalan, Amarchand; Zhu, Yakun; Free, Michael L.

    2013-01-01

    New sets of molecules containing tri-phenyl-amine (TPA) core and thiophene unit with amide and imine functional groups are designed, synthesized, characterized, and compared. These are solution processable small molecules with high mobility. The newly designed molecules have better solubility due to the C=N (imine) and CONH2 (amide) moiety as compared to the established molecules with CH=CH (methine) for optoelectronic applications. They have an optimal energy band gap, which indicates their potential utility in a variety of optoelectronic applications. These molecules also show efficient intermolecular charge transfer mechanisms similar to conventional organic semiconducting molecules as evidenced by optical measurements. Density functional theory simulation results show that the localization of the frontier highest occupied molecular orbital is around the TPA core for molecules coupled with imine and amide, and is reasonably stable.

  14. Enantioselective Construction of Pyrrolidines by Palladium-Catalyzed Asymmetric [3+2] Cycloaddition of Trimethylenemethane with Imines

    PubMed Central

    Trost, Barry M.; Silverman, Steven M.

    2012-01-01

    A protocol for the enantioselective [3+2] cycloaddition of trimethylenemethane (TMM) with imines has been developed. Central to this effort were the novel phosphoramidite ligands developed in our laboratories. The conditions developed to effect an asymmetric TMM reaction using 2-trimethylsilylmethyl allyl acetate were shown to be tolerant of a wide variety of imine acceptors to provide the corresponding pyrrolidine cycloadducts with excellent yields and selectivities. Use of a bis-2-naphthyl phosphoramidite allowed the successful cycloaddition of the parent TMM with N-Boc imines, and has further permitted the reaction of substituted donors with N-tosyl aldimines and ketimines in high regio-, diastereo-, and enantioselectivity. Use of a diphenylazetidine ligand allows the complimentary synthesis of the exocyclic nitrile product shown, and we demonstrate control of the regioselectivity of the product based on manipulation of the reaction parameters. PMID:22309214

  15. Enantioselective construction of quaternary stereogenic carbons by the Lewis base catalyzed additions of silyl ketene imines to aldehydes.

    PubMed

    Denmark, Scott E; Wilson, Tyler W; Burk, Matthew T; Heemstra, John R

    2007-12-01

    Silyl ketene imines derived from a variety of alpha-branched nitriles have been developed as highly useful reagents for the construction of quaternary stereogenic centers via the aldol addition reaction. In the presence of SiCl4 and the catalytic action of chiral phosphoramide (R,R)-5, silyl ketene imines undergo extremely rapid and high yielding addition to a wide variety of aromatic aldehydes with excellent diastereo- and enantioselectivity. Of particular note is the high yields and selectivities obtained from electron-rich, electron-poor, and hindered aldehydes. The nitrile function serves as a useful precursor for further synthetic manipulation. PMID:17988135

  16. Insight into the crystallization of amorphous imine-linked polymer networks to 2D covalent organic frameworks.

    PubMed

    Smith, Brian J; Overholts, Anna C; Hwang, Nicky; Dichtel, William R

    2016-03-01

    We explore the crystallization of a high surface area imine-linked two-dimensional covalent organic framework (2D COF). The growth process reveals rapid initial formation of an amorphous network that subsequently crystallizes into the layered 2D network. The metastable amorphous polymer may be isolated and resubjected to growth conditions to form the COF. These experiments provide the first mechanistic insight into the mechanism of imine-linked 2D COF formation, which is distinct from that of boronate-ester linked COFs. PMID:26857035

  17. Proton transfer reactions between nitric acid and acetone, hydroxyacetone, acetaldehyde and benzaldehyde in the solid phase.

    PubMed

    Lasne, Jérôme; Laffon, Carine; Parent, Philippe

    2012-12-01

    The heterogeneous and homogeneous reactions of acetone, hydroxyacetone, acetaldehyde and benzaldehyde with solid nitric acid (HNO(3)) films have been studied with Reflection-Absorption Infrared Spectroscopy (RAIRS) under Ultra-High Vacuum (UHV) conditions in the 90-170 K temperature range. In the bulk or at the surface of the films, nitric acid transfers its proton to the carbonyl function of the organic molecules, producing protonated acetone-H(+), hydroxyacetone-H(+), acetaldehyde-H(+) and benzaldehyde-H(+), and nitrate anions NO(3)(-), a reaction not observed when nitric acid is previously hydrated [J. Lasne, C. Laffon and Ph. Parent, Phys. Chem. Chem. Phys., 2012, 14, 697]. This provides a molecular-scale description of the carbonyl protonation reaction in an acid medium, the first step of the acid-catalyzed condensation of carbonyl compounds, fuelling the growth of secondary organic aerosols (SOA) in the atmosphere. PMID:23090634

  18. Osmium(ii) complexes for light-driven aerobic oxidation of amines to imines.

    PubMed

    Li, Yong-Hui; Liu, Xiao-Le; Yu, Zhen-Tao; Li, Zhao-Sheng; Yan, Shi-Cheng; Chen, Guang-Hui; Zou, Zhi-Gang

    2016-08-01

    Herein, we describe the synthesis and characterization of three Os(ii) complexes (i.e., [Os(fptz)2(PPhMe2)2] (1, fptzH = 3-trifluoromethyl-5-pyridyl-1,2,4-triazole), [Os(fptz)2(CO)(L1)] (2, L1 = PPh3; 3, L1 = pyridine)) that have been successfully utilized as good photocatalysts to promote aerobic oxidative coupling of amines to imines with molecular oxygen in air as a green oxidant. Complex 1 is the most effective catalyst for the oxidative coupling of benzylamine with molecular O2 (air) as the oxidant because of the complex's strong absorption of visible light and long-lived triplet state. The application of a low catalyst loading (0.06 mol%) of complex 1 to the oxidative coupling of a wide range of amines affords the corresponding imines efficiently and selectively in most cases. The reaction mechanism was investigated via relevant control and quenching experiments. The results indicated that the reaction occurs via an active (1)O2-involved pathway. The (1)O2-generating ability of complex 1 as a photosensitizer was evaluated using 9,10-dimethylanthracene (DMA) as a chemical trap for (1)O2. PMID:27431765

  19. Targeting Reactive Carbonyl Species with Natural Sequestering Agents.

    PubMed

    Hwang, Sung Won; Lee, Yoon-Mi; Aldini, Giancarlo; Yeum, Kyung-Jin

    2016-01-01

    Reactive carbonyl species generated by the oxidation of polyunsaturated fatty acids and sugars are highly reactive due to their electrophilic nature, and are able to easily react with the nucleophilic sites of proteins as well as DNA causing cellular dysfunction. Levels of reactive carbonyl species and their reaction products have been reported to be elevated in various chronic diseases, including metabolic disorders and neurodegenerative diseases. In an effort to identify sequestering agents for reactive carbonyl species, various analytical techniques such as spectrophotometry, high performance liquid chromatography, western blot, and mass spectrometry have been utilized. In particular, recent advances using a novel high resolution mass spectrometry approach allows screening of complex mixtures such as natural products for their sequestering ability of reactive carbonyl species. To overcome the limited bioavailability and bioefficacy of natural products, new techniques using nanoparticles and nanocarriers may offer a new attractive strategy for increased in vivo utilization and targeted delivery of bioactives. PMID:26927058

  20. Infrared photodissociation spectroscopy of vanadium oxide-carbonyl cations.

    PubMed

    Brathwaite, A D; Ricks, A M; Duncan, M A

    2013-12-19

    Mass selected vanadium oxide-carbonyl cations of the form VO(m)(CO)(n)(+) (m = 0-3 and n = 3-6) are studied via infrared laser photodissociation spectroscopy in the 600-2300 cm(-1) region. Insight into the structure and bonding of these complexes is obtained from the number of infrared active bands, their relative intensities and their frequency positions. Density functional theory calculations are carried out in support of the experimental data. The effect of oxidation on the carbonyl stretching frequencies of VO(CO)(n)(+), VO2(CO)(n)(+), and VO3(CO)(n)(+) complexes is investigated. All of these oxide-carbonyl species have C-O stretch vibrations blue-shifted from those of the pure vanadium ion carbonyls. The V-O stretches of these complexes are also investigated, revealing the effects of CO coordination on these vibrations. The oxide-carbonyls all have a hexacoordinate core analogous to that of V(CO)6(+). The fully coordinated vanadium monoxide-carbonyl species is VO(CO)5(+), and those of the dioxide and trioxide are VO2(CO)4(+) and VO3(CO)3(+), respectively. PMID:23927497

  1. Carbonyl species characteristics during the evaporation of essential oils

    NASA Astrophysics Data System (ADS)

    Chiang, Hsiu-Mei; Chiu, Hua-Hsien; Lai, Yen-Ming; Chen, Ching-Yen; Chiang, Hung-Lung

    2010-06-01

    Carbonyls emitted from essential oils can affect the air quality when they are used in indoors, especially under poor ventilation conditions. Lavender, lemon, rose, rosemary, and tea tree oils were selected as typical and popular essential oils to investigate in terms of composition, thermal characteristics and fifteen carbonyl constituents. Based on thermogravimetric (TG) analysis, the activation energy was 7.6-8.3 kcal mol -1, the reaction order was in the range of 0.6-0.7 and the frequency factor was 360-2838 min -1. Formaldehyde, acetaldehyde, acetone, and propionaldehyde were the dominant carbonyl compounds, and their concentrations were 0.034-0.170 ppm. The emission factors of carbonyl compounds were 2.10-3.70 mg g -1, and acetone, propionaldehyde, acetaldehyde, and formaldehyde accounted for a high portion of the emission factor of carbonyl compounds in essential oil exhaust. Some unhealthy carbonyl species such as formaldehyde and valeraldehyde, were measured at low-temperature during the vaporization of essential oils, indicating a potential effect on indoor air quality and human health.

  2. Theoretical investigation of the halogen bonded complexes between carbonyl bases and molecular chlorine.

    PubMed

    Zierkiewicz, Wiktor; Bieńko, Dariusz C; Michalska, Danuta; Zeegers-Huyskens, Thérèse

    2015-04-30

    The halogen bonded complexes between six carbonyl bases and molecular chlorine are investigated theoretically. The interaction energies calculated at the CCSD(T)/aug-cc-pVTZ level range between -1.61 and -3.50 kcal mol(-1). These energies are related to the ionization potential, proton affinity, and also to the most negative values (V(s,min)) on the electrostatic potential surface of the carbonyl bases. A symmetry adapted perturbation theory decomposition of the energies has been performed. The interaction results in an elongation of the Cl-Cl bond and a contraction of the CF and CH bonds accompanied by a blue shift of the ν(CH) vibrations. The properties of the Cl2 molecules are discussed as a function of the σ*(Cl-Cl) occupation, the hybridization, and the occupation of the Rydberg orbitals of the two chlorine atoms. Our calculations predict a large enhancement of the infrared and Raman intensities of the ν(Cl-Cl) vibration on going from isolated to complexed Cl2. PMID:25727322

  3. Light-driven nitrile imine-mediated tetrazole-ene cycloaddition as a versatile platform for fullerene conjugation.

    PubMed

    Sugawara, Yuuki; Jasinski, Nils; Kaupp, Michael; Welle, Alexander; Zydziak, Nicolas; Blasco, Eva; Barner-Kowollik, Christopher

    2015-08-21

    An efficient methodology for modular fullerene functionalization via the photo-induced nitrile imine-mediated tetrazole-ene cycloaddition (NITEC) is introduced. The versatility and platform character of the method is illustrated by the light-driven reaction of fullerenes with small molecule, polymeric and surface-immobilized tetrazoles. The efficient fullerene conjugation is evidenced via mass spectrometric techniques. PMID:26179054

  4. Highly effective asymmetric hydrogenation of cyclic N-alkyl imines with chiral cationic Ru-MsDPEN catalysts.

    PubMed

    Chen, Fei; Ding, Ziyuan; Qin, Jie; Wang, Tianli; He, Yanmei; Fan, Qing-Hua

    2011-08-19

    A range of cyclic N-alkyl imines were efficiently hydrogenated by using a chiral cationic Ru(η(6)-cymene)(MsDPEN)(BArF) complex (MsDPEN = N-(methanesulfonyl)-1,2-diphenylethylenediamine) in high yields and up to 98% ee. A one-pot synthesis of chiral 2-phenylpyrrolidine via reductive amination was also developed. PMID:21766831

  5. Diastereoselective Allylation of "N"-"Tert"-Butanesulfinyl Imines: An Asymmetric Synthesis Experiment for the Undergraduate Organic Laboratory

    ERIC Educational Resources Information Center

    Chen, Xiao-Yang; Sun, Li-Sen; Gao, Xiang; Sun, Xing-Wen

    2015-01-01

    An asymmetric synthetic experiment that encompasses both diastereoselectivity and enantioselectivity is described. In this experiment, Zn-mediated allylation of an ("R")-"N"-"tert"-butanesulfinyl imine is first performed to obtain either diastereomer using two different solvent systems, followed by oxidation of the…

  6. A Practical Guide for Predicting the Stereochemistry of Bifunctional Phosphoric Acid Catalyzed Reactions of Imines.

    PubMed

    Reid, Jolene P; Simón, Luis; Goodman, Jonathan M

    2016-05-17

    Chiral phosphoric acids have become powerful catalysts for the stereocontrolled synthesis of a diverse array of organic compounds. Since the initial report, the development of phosphoric acids as catalysts has been rapid, demonstrating the tremendous generality of this catalyst system and advancing the use of phosphoric acids to catalyze a broad range of asymmetric transformations ranging from Mannich reactions to hydrogenations through complementary modes of activation. These powerful applications have been developed without a clear mechanistic understanding of the reasons for the high level of stereocontrol. This Account describes investigations into the mechanism of the phosphoric acid catalyzed addition of nucleophiles to imines, focusing on binaphthol-based systems. In many cases, the hydroxyl phosphoric acid can form a hydrogen bond to the imine while the P═O interacts with the nucleophile. The single catalyst, therefore, activates both the electrophile and the nucleophile, while holding both in the chiral pocket created by the binaphthol and constrained by substituents at the 3 and 3' positions. Detailed geometric and energetic information about the transition states can be gained from calculations using ONIOM methods that combine the advantages of DFT with some of the speed of force fields. These high-level calculations give a quantitative account of the selectivity in many cases, but require substantial computational resources. A simple qualitative model is a useful complement to this complex quantitative model. We summarize our calculations into a working model that can readily be sketched by hand and used to work out the likely sense of selectivity for each reaction. The steric demands of the different parts of the reactants determine how they fit into the chiral cavity and which of the competing pathways is favored. The preferred pathway can be found by considering the size of the substituents on the nitrogen and carbon atoms of the imine electrophile

  7. Proton Transport

    NASA Technical Reports Server (NTRS)

    Pohorille, Andrew; DeVincenzi, Donald L. (Technical Monitor)

    2001-01-01

    The transport of protons across membranes is an essential process for both bioenergetics of modern cells and the origins of cellular life. All living systems make use of proton gradients across cell walls to convert environmental energy into a high-energy chemical compound, adenosine triphosphate (ATP), synthesized from adenosine diphosphate. ATP, in turn, is used as a source of energy to drive many cellular reactions. The ubiquity of this process in biology suggests that even the earliest cellular systems were relying on proton gradient for harvesting environmental energy needed to support their survival and growth. In contemporary cells, proton transfer is assisted by large, complex proteins embedded in membranes. The issue addressed in this Study was: how the same process can be accomplished with the aid of similar but much simpler molecules that could have existed in the protobiological milieu? The model system used in the study contained a bilayer membrane made of phospholipid, dimyristoylphosphatidylcholine (DMPC) which is a good model of the biological membranes forming cellular boundaries. Both sides of the bilayer were surrounded by water which simulated the environment inside and outside the cell. Embedded in the membrane was a fragment of the Influenza-A M$_2$ protein and enough sodium counterions to maintain system neutrality. This protein has been shown to exhibit remarkably high rates of proton transport and, therefore, is an excellent model to study the formation of proton gradients across membranes. The Influenza M$_2$ protein is 97 amino acids in length, but a fragment 25 amino acids long. which contains a transmembrane domain of 19 amino acids flanked by three amino acids on each side. is sufficient to transport protons. Four identical protein fragments, each folded into a helix, aggregate to form small channels spanning the membrane. Protons are conducted through a narrow pore in the middle of the channel in response to applied voltage. This

  8. Carbonyl emissions from vehicular exhausts sources in Hong Kong.

    PubMed

    Ho, Steven Sai Hang; Ho, Kin Fai; Lee, Shun Cheng; Cheng, Yan; Yu, Jian Zhen; Lam, Ka Man; Feng, Natale Sin Yau; Huang, Yu

    2012-02-01

    Vehicular emission (VE) is one of the important anthropogenic sources for airborne carbonyls in urban area. Six types of VE-dominated samples were collected at representative locations in Hong Kong where polluted by a particular fueled type of vehicles, including (i) a gas refilling taxis station (liquefied petroleum gas [LPG] emission); (ii) a light-duty passenger car park (gasoline emission); (iii) a minibus station (diesel emission); (iv) a single-deck-bus depot (diesel emission); (v) a double-deck-bus depot (diesel emission); and (vi) a whole-food market entrance for light- and heavy-duty vehicles (diesel emission). A total of 15 carbonyls in the samples were quantified. Formaldehyde was the most abundant carbonyl among the VE-dominated samples, and its contribution to the total quantified amount on a molar basis ranged from 54.8% to 60.8%. Acetaldehyde and acetone were the next two abundant carbonyls. The carbonyls were quantified at three roadside locations in Hong Kong. The highest concentrations of formaldehyde and acetaldehyde, 22.7 +/- 8.4 and 6.0 +/- 2.8 microg/m3, respectively, were determined in the samples collected at a main transportation gate for goods between Hong Kong and Mainland China. The total quantified carbonyl concentration, 37.9 +/- 9.3 microg/m3, was the highest at an entrance of a cross-harbor tunnel in downtown area. The theoretical carbonyls compositions of the three roadside locations were estimated according to the VE-dominated sample profiles and the statistics on vehicle numbers and types during the sampling period. The measured compositions of formaldehyde were much higher than the theoretical compositions in summer, demonstrating that photochemical reactions significantly contributed to the formaldehyde production in the roadsides. PMID:22442938

  9. Synthesis and Biology of Cyclic Imine Toxins, An Emerging Class of Potent, Globally Distributed Marine Toxins

    PubMed Central

    Stivala, Craig E.; Benoit, Evelyne; Araoz, Romulo; Servent, Denis; Novikov, Alexei

    2014-01-01

    From a small group of exotic compounds isolated only two decades ago, Cyclic Imine (CI) toxins have become a major class of marine toxins with global distribution. Their distinct chemical structure, biological mechanism of action, and intricate chemistry ensures that CI toxins will continue to be the subject of fascinating fundamental studies in the broad fields of chemistry, chemical biology, and toxicology. The worldwide occurrence of potent CI toxins in marine environments, their accumulation in shellfish, and chemical stability are important considerations in assessing risk factors for human health. This review article aims to provide an account of chemistry, biology, and toxicology of CI toxins from their discovery to the present day. PMID:25338021

  10. Radical migration-addition of N-tert-butanesulfinyl imines with organozinc reagents.

    PubMed

    Huang, Wei; Ye, Jian-Liang; Zheng, Wei; Dong, Han-Qing; Wei, Bang-Guo

    2013-11-15

    A novel migration-addition sequence was discovered for the reaction of enantioenriched N-tert-butanesulfinyl iminoacetate 1a with functionalized benzylzinc bromide reagents, producing tert-leucine derivatives in excellent diastereoselectivity (dr 98:2). The absolute configurations of two new chiral centers were unambiguously assigned by chemical transformations and X-ray crystallography. In addition, the regio- and diastereoselectivities of this novel reaction were both explained through the key N-sulfinamine intermediate M6 generated by the tert-butyl radical attack on the imine. Computational analysis of this reaction process, which was performed at the B3LYP/6-311++G(3df,2p)//B3LYP/6-31G*-LANL2DZ level, also supported our proposed two-stage mechanism. PMID:24160561

  11. The Scavenging of DPPH, Galvinoxyl and ABTS Radicals by Imine Analogs of Resveratrol

    PubMed Central

    Kotora, Peter; Šeršeň, František; Filo, Juraj; Loos, Dušan; Gregáň, Juraj; Gregáň, Fridrich

    2016-01-01

    Resveratrol (3,5,4′-trihydroxystilbene) is a phytoalexin produced by plants. Resveratrol is known for its anti-cancer, antiviral and antioxidant properties. We prepared imine analogs of resveratrol ((hydroxyphenyliminomethyl)phenols) and tested their antioxidant activity. All prepared resveratrol analogs were able to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH), galvinoxyl radical (GOR) and 2,2′-azino-bis(3-ethylbenzothiazoline)-6-sulphonic acid (ABTS) radicals. The antioxidant activity efficiency correlated with the number and position of hydroxyl groups. The most effective antioxidants were resveratrol analogs containing three hydroxyl groups in the benzylidene part of their molecules. These results provide new insights into the relationship between the chemical structure and biological activity of resveratrol analogs. PMID:26805801

  12. Synthesis and biology of cyclic imine toxins, an emerging class of potent, globally distributed marine toxins.

    PubMed

    Stivala, Craig E; Benoit, Evelyne; Aráoz, Rómulo; Servent, Denis; Novikov, Alexei; Molgó, Jordi; Zakarian, Armen

    2015-03-01

    From a small group of exotic compounds isolated only two decades ago, Cyclic Imine (CI) toxins have become a major class of marine toxins with global distribution. Their distinct chemical structure, biological mechanism of action, and intricate chemistry ensures that CI toxins will continue to be the subject of fascinating fundamental studies in the broad fields of chemistry, chemical biology, and toxicology. The worldwide occurrence of potent CI toxins in marine environments, their accumulation in shellfish, and chemical stability are important considerations in assessing risk factors for human health. This review article aims to provide an account of chemistry, biology, and toxicology of CI toxins from their discovery to the present day. PMID:25338021

  13. Docking of ethanamine Schiff base imines & metal (II) complexes, cytotoxicity & DNA interaction studies

    NASA Astrophysics Data System (ADS)

    Sujarani, S.; Ramu, A.

    2015-01-01

    The present study deals with a series of biologically and stereo chemically important novel transition metal (II) Schiff base chelates. The Cu (II), Co (II), Mn (II) and Ni (II) ions containing complexes were synthesized by using diphenylethanamine and 2-hydroxy/2, 4-dihydroxy/2-hydroxy-4-methoxybenzaldehydes. The synthesized complexes were characterized using micro analytical, IR, NMR, ESI-Mass, UV-Visible, cyclic voltammetry and the EPR spectroscopic techniques. The spectral data evidenced the action of ligands as a neutral bidentate Schiff bases, coordinating through azomethine nitrogen and oxygen atom of hydroxyl group. The interaction studies revealed the groove binding nature of complexes with CT-DNA. The ligand and synthesized metal complexes showed cytotoxicity against cancerous cells. The strong binding affinity of the imine and metal complexes was also confirmed by molecular docking studies.

  14. Proton interrogation

    SciTech Connect

    Morris, Christopher L

    2008-01-01

    Energetic proton beams may provide an attractive alternative when compared to electromagnetic and neutron beams for active interrogation of nuclear threats because: they have large fission cross sections, long mean free paths and high penetration, and proton beams can be manipulated with magnetic optics. We have measured time-dependent cross sections for delayed neutrons and gamma-rays using the 800 MeV proton beam from the Los Alamos Neutron Science Center for a set of bare and shielded targets. The results show significant signals from both unshielded and shielded nuclear materials. Results will be presented.

  15. From Alcohol Dehydrogenase to a “One-way” Carbonyl Reductase by Active-site Redesign

    PubMed Central

    Klimacek, Mario; Nidetzky, Bernd

    2010-01-01

    Directional preference in catalysis is often used to distinguish alcohol dehydrogenases from carbonyl reductases. However, the mechanistic basis underpinning this discrimination is weak. In mannitol 2-dehydrogenase from Pseudomonas fluorescens, stabilization of (partial) negative charge on the substrate oxyanion by the side chains of Asn-191 and Asn-300 is a key feature of catalysis in the direction of alcohol oxidation. We have disrupted this ability through individual and combined substitutions of the two asparagines by aspartic acid. Kinetic data and their thermodynamic analysis show that the internal equilibrium of enzyme-NADH-fructose and enzyme-NAD+-mannitol (Kint) was altered dramatically (104- to 105-fold) from being balanced in the wild-type enzyme (Kint ≈ 3) to favoring enzyme-NAD+-mannitol in the single site mutants, N191D and N300D. The change in Kint reflects a selective slowing down of the mannitol oxidation rate, resulting because Asn → Asp replacement (i) disfavors partial abstraction of alcohol proton by Lys-295 in a step preceding catalytic hydride transfer, and (ii) causes stabilization of a nonproductive enzyme-NAD+-mannitol complex. N191D and N300D appear to lose fructose binding affinity due to deprotonation of the respective Asp above apparent pK values of 5.3 ± 0.1 and 6.3 ± 0.2, respectively. The mutant incorporating both Asn→Asp substitutions behaved as a slow “fructose reductase” at pH 5.2, lacking measurable activity for mannitol oxidation in the pH range 6.8–10. A mechanism is suggested in which polarization of the substrate carbonyl by a doubly protonated diad of Asp and Lys-295 facilitates NADH-dependent reduction of fructose by N191D and N300D under optimum pH conditions. Creation of an effectively “one-way” reductase by active-site redesign of a parent dehydrogenase has not been previously reported and holds promise in the development of carbonyl reductases for application in organic synthesis. PMID:20639204

  16. Clinical features of schizophrenia with enhanced carbonyl stress.

    PubMed

    Miyashita, Mitsuhiro; Arai, Makoto; Kobori, Akiko; Ichikawa, Tomoe; Toriumi, Kazuya; Niizato, Kazuhiro; Oshima, Kenichi; Okazaki, Yuji; Yoshikawa, Takeo; Amano, Naoji; Miyata, Toshio; Itokawa, Masanari

    2014-09-01

    Accumulating evidence suggests that advanced glycation end products, generated as a consequence of facilitated carbonyl stress, are implicated in the development of a variety of diseases. These diseases include neurodegenerative illnesses, such as Alzheimer disease. Pyridoxamine is one of the 3 forms of vitamin B6, and it acts by combating carbonyl stress and inhibiting the formation of AGEs. Depletion of pyridoxamine due to enhanced carbonyl stress eventually leads to a decrease in the other forms of vitamin B6, namely pyridoxal and pyridoxine. We previously reported that higher levels of plasma pentosidine, a well-known biomarker for advanced glycation end products, and decreased serum pyridoxal levels were found in a subpopulation of schizophrenic patients. However, there is as yet no clinical characterization of this subset of schizophrenia. In this study, we found that these patients shared many clinical features with treatment-resistant schizophrenia. These include a higher proportion of inpatients, low educational status, longer durations of hospitalization, and higher doses of antipsychotic medication, compared with patients without carbonyl stress. Interestingly, psychopathological symptoms showed a tendency towards negative association with serum vitamin B6 levels. Our results support the idea that treatment regimes reducing carbonyl stress, such as supplementation of pyridoxamine, could provide novel therapeutic benefits for this subgroup of patients. PMID:24062594

  17. Determination of toxic carbonyl compounds in cigarette smoke.

    PubMed

    Fujioka, Kazutoshi; Shibamoto, Takayuki

    2006-02-01

    Toxic carbonyl compounds, including formaldehyde, malonaldehyde, and glyoxal, formed in mainstream cigarette smoke were quantified by derivatization-solid phase extraction-gas chromatography methods. Cigarette smoke from 14 commercial brands and one reference (2R1F) was drawn into a separatory funnel containing aqueous phosphate-buffered saline. Reactive carbonyl compounds trapped in the buffer solution were derivatized into stable nitrogen containing compounds (pyrazoles for beta-dicarbonyl and alpha,beta-unsaturated aldehyde; quinoxalines for alpha-dicarbonyls; and thiazolidines for alkanals). After derivatives were recovered using C(18) solid phase extraction cartridges, they were analyzed quantitatively by a gas chromatograph with a nitrogen phosphorus detector. The total carbonyl compounds recovered from regular size cigarettes ranged from 1.92 mg/cigarette(-1) to 3.14 mg/cigarette(-1). The total carbonyl compounds recovered from a reference cigarette and a king size cigarette were 3.23 mg/cigarette(-1) and 3.39 mg/cigarette(-1), respectively. The general decreasing order of the carbonyl compounds yielded was acetaldehyde (1110-2101 microg/cigarette(-1)) > diacetyl (301-433 microg/cigarette(-1)), acrolein (238-468 microg/cigarette(-1)) > formaldehyde (87.0-243 microg/cigarette(-1)), propanal (87.0-176 microg/cigarette(-1)) > malonaldehyde (18.9-36.0 microg/cigarette(-1)), methylglyoxal (13.4-59.6 microg/cigarette(-1)) > glyoxal (1.93-6.98 microg/cigarette(-1)). PMID:16463255

  18. [Protein carbonylation and its role in physiological processes in plants].

    PubMed

    Debska, Karolina; Bogatek, Renata; Gniazdowska, Agnieszka

    2012-01-01

    Plant cells produce reactive oxygen species (ROS) continuously as a byproducts of oxygen metabolism and reaction to various environmental stresses. ROS are considered as chemicals inducing damage of cellular components (DNA, lipids and proteins), but also might act as signaling agents. Protein oxidation is one of covalent modification of protein induced by ROS or other products of oxidative stress. Carbonylation of particular amino acid residues (arginine, lysine, treonine or proline) is one of the most commonly occurring oxidative modification of proteins. This modification might lead to alteration in protein activity, its proteolytic breakdown or, in the opposite, aggregate formation. Carbonylated proteins have been identified in many plant species at different stage of growth and development. The analysis of subcellular localization of carbonylated proteins arised the hypothesis on their signaling function. We summarize the current knowledge on the detection of carbonylation protein in plants taking to the account the conditions which may influence their production or removal. We present also their putative role in plant physiology and discuss interaction between ROS and RNS in regulation of protein carbonylation. PMID:23214127

  19. Reaction electronic flux and its role in DNA intramolecular proton transfers.

    PubMed

    Durán, Rocío; Vöhringer-Martinez, Esteban; Toro-Labbé, Alejandro; Herrera, Bárbara

    2016-06-01

    Proton transfer reactions present a key step in many biological and chemical processes. Here, we focused on the electronic changes in the proton transfer reactions of the four DNA bases. In combination with the previous structural analysis the reaction electronic flux together with local descriptors as the Hirshfeld-I charges allow us to identify chemical events and rationalize the underlying reaction mechanism. Our results show that imine-enamine in adenine and citosyne, and keto-enol tautomerizations in thymine and guanine have different reaction mechanisms. The former involve net structural rearrangements driven by favoured electrostatic interactions between the proton and the acceptor atom whereas the keto-enol tautomerizations require electronic changes reflected in the reaction electronic flux and changes in the NBO bond orders which favour the proton transfer reaction. PMID:27256316

  20. Catalytic production of metal carbonyls from metal oxides

    DOEpatents

    Sapienza, Richard S.; Slegeir, William A.; Foran, Michael T.

    1984-01-01

    This invention relates to the formation of metal carbonyls from metal oxides and specially the formation of molybdenum carbonyl and iron carbonyl from their respective oxides. Copper is used here in admixed form or used in chemically combined form as copper molybdate. The copper/metal oxide combination or combined copper is utilized with a solvent, such as toluene and subjected to carbon monoxide pressure of 25 atmospheres or greater at about 150.degree.-260.degree. C. The reducing metal copper is employed in catalytic concentrations or combined concentrations as CuMoO.sub.4 and both hydrogen and water present serve as promoters. It has been found that the yields by this process have been salutary and that additionally the catalytic metal may be reused in the process to good effect.

  1. Catalytic production of metal carbonyls from metal oxides

    DOEpatents

    Sapienza, R.S.; Slegeir, W.A.; Foran, M.T.

    1984-01-06

    This invention relates to the formation of metal carbonyls from metal oxides and specially the formation of molybdenum carbonyl and iron carbonyl from their respective oxides. Copper is used here in admixed form or used in chemically combined form as copper molybdate. The copper/metal oxide combination or combined copper is utilized with a solvent, such as toluene and subjected to carbon monoxide pressure of 25 atmospheres or greater at about 150 to 260/sup 0/C. The reducing metal copper is employed in catalytic concentrations or combined concentrations as CuMoO/sub 4/ and both hydrogen and water present serve as promoters. It has been found that the yields by this process have been salutary and that additionally the catalytic metal may be reused in the process to good effect. 3 tables.

  2. Traditional reactive carbonyl scavengers do not prevent the carbonylation of brain proteins induced by acute glutathione depletion.

    PubMed

    Zheng, J; Bizzozero, O A

    2010-03-01

    This study investigated the effect of reactive carbonyl species (RCS)-trapping agents on the formation of protein carbonyls during depletion of brain glutathione (GSH). To this end, rat brain slices were incubated with the GSH-depletor diethyl maleate in the absence or presence of chemically different RCS scavengers (hydralazine, methoxylamine, aminoguanidine, pyridoxamine, carnosine, taurine and z-histidine hydrazide). Despite their strong reactivity towards the most common RCS, none of the scavengers tested, with the exception of hydralazine, prevented protein carbonylation. These findings suggest that the majority of protein-associated carbonyl groups in this oxidative stress paradigm do not derive from stable lipid peroxidation products like malondialdehyde (MDA), acrolein and 4-hydroxynonenal (4-HNE). This conclusion was confirmed by the observation that the amount of MDA-, acrolein- and 4-HNE-protein adducts does not increase upon GSH depletion. Additional studies revealed that the efficacy of hydralazine at preventing carbonylation was due to its ability to reduce oxidative stress, most likely by inhibiting mitochondrial production of superoxide and/or by scavenging lipid free radicals. PMID:20001647

  3. Infrared Photodissociation Spectroscopy of Metal Oxide Carbonyl Cations.

    NASA Astrophysics Data System (ADS)

    Brathwaite, Antonio D.; Duncan, Michael A.

    2013-06-01

    Mass selected metal oxide-carbonyl cations of the form MO_{m}(CO)_{n}^{+} are studied via infrared laser photodissociation spectroscopy, in the 600-2300cm^{1} region. Insight into the structure and bonding of these complexes is obtained from the number of infrared active bands, their relative intensities and their frequency positions. Density functional theory calculations are carried out in support of the experimental data. Insight into the bonding of CO ligands to metal oxides is obtained and the effect of oxidation on the carbonyl stretching frequency is revealed.

  4. DABCO-catalyzed [3 + 2] annulation of sulfamate-derived cyclic imines with isocyanoacetates: synthesis of sulfamate-fused 2-imidazoline.

    PubMed

    Gao, Zhenzhen; Zhang, Lei; Sun, Zhanhu; Yu, Hao; Xiao, Yumei; Guo, Hongchao

    2014-08-14

    DABCO-catalyzed [3 + 2] annulation reaction of sulfamate-derived cyclic imines with isocyanoacetate proceeds under mild conditions, providing sulfamate-fused 2-imidazolines in moderate to excellent yields with moderate to excellent diastereoselectivities. PMID:24965036

  5. Hydrogenation and Transfer Hydrogenation Promoted by Tethered Ru-S Complexes: From Cooperative Dihydrogen Activation to Hydride Abstraction/Proton Release from Dihydrogen Surrogates.

    PubMed

    Lefranc, Alice; Qu, Zheng-Wang; Grimme, Stefan; Oestreich, Martin

    2016-07-11

    Hydrogenation and transfer hydrogenation of imines with cyclohexa-1,4-dienes, as well as with a representative Hantzsch ester dihydrogen surrogate, are reported. Both processes are catalyzed by tethered Ru-S complexes but differ in the activation mode of the dihydrogen source: cooperative activation of the H-H bond at the Ru-S bond leads to the corresponding Ru-H complex and protonation of the sulfur atom, whereas the same cationic Ru-S catalyst abstracts a hydride from a donor-substituted cyclohexa-1,4-diene to form the neutral Ru-H complex and a low-energy Wheland intermediate. A sequence of proton and hydride transfers on the imine substrate then yields an amine. The reaction pathways are analyzed computationally, and the established mechanistic pictures are in agreement with the experimental observations. PMID:27311877

  6. Metal telluride clusters composed of niobocene carbonyl, telluride, and cobalt carbonyl units: syntheses, structures, and reactivity

    PubMed

    Brunner; Lucas; Monzon; Mugnier; Nuber; Stubenhofer; Stuckl; Wachter; Wanninger; Zabel

    2000-02-01

    Abstract: The reaction of [Cp#2NbTe2H] (1#; Cp# = Cp* (C5Me5) or Cp(x) (C5Me4Et)) with two equivalents of [Co2(CO)8] gives a series of cobalt carbonyl telluride clusters that contain different types of niobocene carbonyl fragments. At 0 degrees C, [Cp#2NbTe2CO3(CO)7] (2#) and [Co4Te2(CO)10] (3) are formed which disappear at higher temperatures: in boiling toluene a mixture of [cat2][Co9Te6(CO)8] (5#) (cat= [Cp#2Nb(CO)2]+) and [cat2][Co11Te7(CO)10] (6#) is formed along with [cat][Co(CO)4] (4#). Complexes 6# transform into [cat][Co11Te7(CO)10] (7#) upon interaction with HPF6 or wet SiO2. The molecular structures of 2(Cp(x)), 4(Cp(x)), 5(Cp*), 6(Cp*) and 7(Cp*) have been determined by X-ray crystallography. The structure of the neutral 2(Cp(x)) consists of a [Co3(CO)6Te2] bipyramid which is connected to a [(C5Me4Et)2Nb(CO)] fragment through a mu4-Te bridge. The ionic structures of 4(Cp(x)), 5(Cp*), 6(Cp*) and 7(Cp*) each contain one (4, 7) or two (5, 6) [Cp#2Nb(CO)2]+ cations. Apart from 4, the anionic counterparts each contain an interstitial Co atom and are hexacapped cubic cluster anions [Co9Te6(CO)8]2- (5) or heptacapped pentagonal prismatic cluster anions [Co11Te7(CO)10]n- (n=2: [6]2- , n=1: [7]-), respectively. Electrochemical studies established a reversible electron transfer between the anionic clusters [Co11,Te7(CO)10]- and [Co11Te7(CO)10]2in 6# and 7# and provided evidence for the existence of species containing [Co11Te7(CO),0] and [Co11Te7(CO)0]3-. The electronic structures of the new clusters and their relative stabilities are examined by means of DFT calculations. PMID:10747416

  7. Copper-Catalyzed Cascade Reaction via Intramolecular Hydroamination Cyclization of Homopropargylic Amines and Intermolecular Povarov Reaction with Imines.

    PubMed

    Wang, Hongkai; Wang, Chan; Huang, Kaimeng; Liu, Lingyan; Chang, Weixing; Li, Jing

    2016-05-20

    A new one-pot cascade reaction of homopropargylic amines with simple imines is developed in the presence of Cu(OTf)2 and affords a series of hexahydro-1H-pyrrolo[3,2-c]quinoline derivatives in good to high yields. This reaction proceeds through an intramolecular hydroamination cyclization of homopropargylic amine to generate a highly reactive dihydropyrrole intermediate in situ. It subsequently reacts with imine via an intermolecular inverse-electron-demand aza-Diels-Alder reaction and a 1,3-H shift to give the fused pyrroloquinoline structures, forming two new C-C bonds and one C-N bond and one N-H bond. PMID:27128977

  8. Synthesis of tetra-substituted imidazoles and 2-imidazolines by Ni(0)-catalyzed dehydrogenation of benzylic-type imines.

    PubMed

    Tlahuext-Aca, Adrian; Hernández-Fajardo, Oscar; Arévalo, Alma; García, Juventino J

    2014-11-14

    Ni(0)-catalyzed dehydrogenation of benzylic-type imines was performed to yield asymmetrical tetra-substituted imidazoles and 2-imidazolines. This was achieved with a single operational step while maintaining good selectivity and atom economy. The catalytic system shows low to moderate tolerance for fluoro-, trifluoromethyl-, methyl-, and methoxy-substituted benzylic-type imines. In addition, the substitution pattern at the N-heterocyclic products was easily controlled by the appropriate selection of R-groups in the starting organic substrates. Based on experimental observations, we propose a reaction mechanism in which benzylic C(sp(3))-H bond activation and insertion steps play pivotal roles in this nickel-catalyzed organic transformation. PMID:25232889

  9. Cytokinin inhibits the proteasome-mediated degradation of carbonylated proteins in Arabidopsis leaves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Under normal conditions, plants contain numerous carbonylated proteins, which are thought to be indicative of oxidative stress damage. Conditions that promote formation of reactive oxygen species (ROS) enhance protein carbonylation, and protein degradation is required to reverse the damage. However,...

  10. Development of Non-C2-symmetric ProPhenol Ligands. The Asymmetric Vinylation of N-Boc Imines.

    PubMed

    Trost, Barry M; Hung, Chao-I Joey; Koester, Dennis C; Miller, Yan

    2015-08-01

    The development and application of a new generation of non-C2-symmetric ProPhenol ligands is reported herein. Rational design of the ProPhenol ligand paved the way to the first catalytic and asymmetric vinylation of N-Boc imines via hydrozirconation giving rise to valuable allylic amines in excellent yields and enantioselectivities. The utility of this method was demonstrated by developing the shortest reported asymmetric synthesis of the selective serotonine reuptake inhibitor (SSRI) (-)-dapoxetine. PMID:26200769

  11. Copper-Catalyzed Borylative Cross-Coupling of Allenes and Imines: Selective Three-Component Assembly of Branched Homoallyl Amines.

    PubMed

    Rae, James; Yeung, Kay; McDouall, Joseph J W; Procter, David J

    2016-01-18

    A copper-catalyzed three-component coupling of allenes, bis(pinacolato)diboron, and imines allows regio-, chemo-, and diastereoselective assembly of branched α,β-substituted-γ-boryl homoallylic amines, that is, products bearing versatile amino, alkenyl, and borane functionality. Alternatively, convenient oxidative workup allows access to α-substituted-β-amino ketones. A computational study has been used to probe the stereochemical course of the cross-coupling. PMID:26632675

  12. Stereoretentive Addition of N-tert-Butylsulfonyl-α-Amido Silanes to Aldehydes, Ketones, α,β-Unsaturated Esters, and Imines.

    PubMed

    Mita, Tsuyoshi; Saito, Keisuke; Sugawara, Masumi; Sato, Yoshihiro

    2016-05-20

    Enantioenriched N-tert-butylsulfonyl-α-amido silanes were successfully reacted with aldehydes, ketones, imines, and α,β-unsaturated esters in the presence of a sub-stoichiometric amount of CsF (0.5 equiv) in 1,2-dimethoxyethane (DME) at -20 °C to afford the corresponding coupling products with up to 89 % enantiospecificity in a retentive manner. PMID:27027853

  13. Copper‐Catalyzed Borylative Cross‐Coupling of Allenes and Imines: Selective Three‐Component Assembly of Branched Homoallyl Amines

    PubMed Central

    Rae, James; Yeung, Kay; McDouall, Joseph J. W.

    2015-01-01

    Abstract A copper‐catalyzed three‐component coupling of allenes, bis(pinacolato)diboron, and imines allows regio‐, chemo‐, and diastereoselective assembly of branched α,β‐substituted‐γ‐boryl homoallylic amines, that is, products bearing versatile amino, alkenyl, and borane functionality. Alternatively, convenient oxidative workup allows access to α‐substituted‐β‐amino ketones. A computational study has been used to probe the stereochemical course of the cross‐coupling. PMID:26632675

  14. The intracellular proton gradient enables anaerobic ammonia oxidizing (anammox) bacteria to tolerate NO2 - inhibition.

    PubMed

    Carvajal-Arroyo, José M; Puyol, Daniel; Li, Guangbin; Sierra-Álvarez, Reyes; Field, Jim A

    2014-12-20

    Anammox bacteria are inhibited by nitrite, which is one of their substrates. By utilizing 2,4 dinitrophenol and carbonyl cyanide m-chlorophenyl hydrazone, two uncouplers of respiration, we demonstrate that nitrite tolerance of anammox cells is strongly dependent on their ability to maintain a proton gradient, which may be the driving force for active nitrite transport system. PMID:25449017

  15. Age-related variations of protein carbonyls in human saliva and plasma: is saliva protein carbonyls an alternative biomarker of aging?

    PubMed

    Wang, Zhihui; Wang, Yanyi; Liu, Hongchen; Che, Yuwei; Xu, Yingying; E, Lingling

    2015-06-01

    Free radical hypothesis which is one of the most acknowledged aging theories was developed into oxidative stress hypothesis. Protein carbonylation is by far one of the most widely used markers of protein oxidation. We studied the role of age and gender in protein carbonyl content of saliva and plasma among 273 Chinese healthy subjects (137 females and 136 males aged between 20 and 79) and discussed the correlation between protein carbonyl content of saliva and plasma. Protein carbonyl content of saliva and plasma were, respectively, 2.391 ± 0.639 and 0.838 ± 0.274 nmol/mg. Variations of saliva and plasma different age groups all reached significant differences in both male and female (all p < 0.05) while both saliva and plasma protein carbonyls were found to be significantly correlated with age (r = 0.6582 and r = 0.5176, all p < 0.001). Gender was discovered to be unrelated to saliva and plasma protein carbonyl levels (all p > 0.05). Saliva and plasma protein carbonyls were positively related (r = 0.4405, p < 0.001). Surprisingly, saliva and plasma protein carbonyls/ferric reducing ability of plasma (FRAP) ratios were proved to be significantly correlated with age (r = 0.7796 and r = 0.6938, all p < 0.001) while saliva protein carbonyls/FRAP ratio and plasma protein carbonyls/FRAP ratio were also correlated (r = 0.5573, p < 0.001). We concluded that saliva protein carbonyls seem to be an alternative biomarker of aging while the mechanisms of protein carbonylation and oxidative stress and the relationship between saliva protein carbonyls and diseases need to be further investigated. PMID:25943699

  16. Preparation, structure, and luminescence of dinuclear lanthanide complexes of a novel imine-amine phenolate macrocycle

    SciTech Connect

    Matthews, K.D.; Kahwa, I.A. ); Williams, D.J. )

    1994-03-30

    Metal-free condensation of 2,6-diformyl-p-cresol with 3,6-dioxa-1,8-octanediamine followed by reduction with sodium tetrahydroborate and addition of lanthanide(III) nitrate salts, in that order, yield (slowly) crystalline dinuclear complexes of a novel imine-amine phenolate macrocycle 2. The decacoordination geometry of the identical Pr[sup 3+] ions in a C[sub 2v] 4A,6B-extended dodecahedron made up of two bidentate NO[sub 3]-ions, two phenolate and two either oxygens, and one imine and one amine nitrogens. Dinuclear lanthanide complexes of 2 appear to be more stable than those of the totally reduced chelate 2 in alcoholic media. The Tb[sub 2]2(NO[sub 3])[sub 4][center dot]1.2CH[sub 3]-OH and (La[sub 0.97]Tb[sub 0.03])[sub 2]2(NO[sub 3])[sub 4][center dot]1.2CH[sub 3]OH compounds exhibit strong Tb[sup 3+] ([sup 5]D[sub 4] [yields] [sup 7]F[sub J]) emission sensitized by the single state of 2 at both 77 and 295 K. No Tb[sup 3+]-Tb[sup 3+] self-quenching or N-H trapping effects are observed at 77 K (decay rate is 598 s[sup [minus]1]); the coordination cavities of 2 are therefore potentially good hosts for Tb[sup 3+] in luminescent diagnostic agents. At room temperature the complex decay kinetics of Tb[sup 3+] in Tb[sub 2]2(NO[sub 3])[sub 4][center dot]1.2CH[sub 3]OH are similar to those of Tb[sub 2]1(NO[sub 3])[sub 4][center dot]H[sub 2]O. But for the dilute complex, (La[sub 0.97]-Tb[sub 0.03])[sub 2]2(NO[sub 3])[sub 4][center dot]1.35CH[sub 3]OH, unusual thermal equilibration of the ligand triplet and Tb[sup 3+] [sup 5]D[sub 4] states occurs at room temperature; the ligand-to-Tb[sup 3+] energy-transfer rate is [approx]4.36 x 10[sup 4] s[sup [minus]1], while Tb[sup 3+]-to-ligand back-energy-transfer is [approx]7.1 x 10[sup 4] s[sup [minus]1].

  17. Cobalt carbonyl catalyzed olefin hydroformylation in supercritical carbon dioxide

    DOEpatents

    Rathke, Jerome W.; Klingler, Robert J.

    1993-01-01

    A method of olefin hydroformylation is provided wherein an olefin reacts with a carbonyl catalyst and with reaction gases such as hydrogen and carbon monoxide in the presence of a supercritical reaction solvent, such as carbon dioxide. The invention provides higher yields of n-isomer product without the gas-liquid mixing rate limitation seen in conventional Oxo processes using liquid media.

  18. Cobalt carbonyl catalyzed olefin hydroformylation in supercritical carbon dioxide

    DOEpatents

    Rathke, J.W.; Klingler, R.J.

    1993-03-30

    A method of olefin hydroformylation is provided wherein an olefin reacts with a carbonyl catalyst and with reaction gases such as hydrogen and carbon monoxide in the presence of a supercritical reaction solvent, such as carbon dioxide. The invention provides higher yields of n-isomer product without the gas-liquid mixing rate limitation seen in conventional Oxo processes using liquid media.

  19. Metal-Diazo Radicals of α-Carbonyl Diazomethanes

    NASA Astrophysics Data System (ADS)

    Li, Feifei; Xiao, Longqiang; Liu, Lijian

    2016-03-01

    Metal-diazo radicals of α-carbonyl diazomethanes are new members of the radical family and are precursors to metal-carbene radicals. Herein, using electron paramagnetic resonance spectroscopy with spin-trapping, we detect diazo radicals of α-carbonyl diazomethanes, induced by [RhICl(cod)]2, [CoII(por)] and PdCl2, at room temperature. The unique quintet signal of the Rh-diazo radical was observed in measurements of α-carbonyl diazomethane adducts of [RhICl(cod)]2 in the presence of 5,5-dimethyl-pyrroline-1-N-oxide (DMPO). DFT calculations indicated that 97.2% of spin density is localized on the diazo moiety. Co- and Pd-diazo radicals are EPR silent but were captured by DMPO to form spin adducts of DMPO-N• (triplet-of-sextets signal). The spin-trapping also provides a powerful tool for detection of metal-carbene radicals, as evidenced by the DMPO-trapped carbene radicals (DMPO-C•, sextet signal) and 2-methyl-2-nitrosopropane-carbene adducts (MNP-C•, doublet-of-triplets signal). The transformation of α-carbonyl diazomethanes to metal-carbene radicals was confirmed to be a two-step process via metal-diazo radicals.

  20. Comparing Carbonyl Chemistry in Comprehensive Introductory Organic Chemistry Textbooks

    ERIC Educational Resources Information Center

    Nelson, Donna J.; Kumar, Ravi; Ramasamy, Saravanan

    2015-01-01

    Learning the chemistry of compounds containing carbonyl groups is difficult for undergraduate students partly because of a convolution of multiple possible reaction sites, competitive reactions taking place at those sites, different criteria needed to discern between the mechanisms of these reactions, and no straightforward selection method…

  1. Iron-Sulfur-Carbonyl and -Nitrosyl Complexes: A Laboratory Experiment.

    ERIC Educational Resources Information Center

    Glidewell, Christopher; And Others

    1985-01-01

    Background information, materials needed, procedures used, and typical results obtained, are provided for an experiment on iron-sulfur-carbonyl and -nitrosyl complexes. The experiment involved (1) use of inert atmospheric techniques and thin-layer and flexible-column chromatography and (2) interpretation of infrared, hydrogen and carbon-13 nuclear…

  2. CARBONYL SULFIDE INHALATION PRODUCES BRAIN LESIONS IN F344 RATS.

    EPA Science Inventory

    Carbonyl sulfide (COS) is an intermediate in the production of pesticides and herbicides, and is a metabolite of the neurotoxicant carbon disulfide. The potential neurotoxicity of inhaled COS was investigated in F344 rats. Male rats were exposed to 0, 75, 150, 300, or 600 ppm COS...

  3. CARBONYLATION OF MYOSIN HEAVY CHAINS IN RAT HEARTS DURING DIABETES

    PubMed Central

    Shao, Chun-Hong; Rozanski, George J.; Nagai, Ryoji; Stockdale, Frank E.; Patel, Kaushik P.; Wang, Mu; Singh, Jaipaul; Mayhan, William G.; Bidasee, Keshore R.

    2010-01-01

    Cardiac inotropy progressively declines during diabetes mellitus. To date, the molecular mechanisms underlying this defect remain incompletely characterized. This study tests the hypothesis that ventricular myosin heavy chains (MHC) undergo carbonylation by reactive carbonyl species (RCS) during diabetes and these modifications contribute to the inotropic decline. Male Sprague-Dawley rats were injected with streptozotocin (STZ). Fourteen days later animals were divided into two groups: one group was treated with the RCS blocker aminoguanidine for six weeks, while the other group received no treatment. After eight weeks of diabetes, cardiac ejection fraction, fractional shortening, left ventricular pressure development (+dP/dt) and myocyte shortening were decreased by 9%, 16%, 34% and 18%, respectively. Ca2+- and Mg2+-actomyosin ATPase activities and peak actomyosin syneresis were also reduced by 35%, 28%, and 72%. MHC-α to MHC-β ratio was 12:88. Mass spectrometry and Western blots revealed the presence of carbonyl adducts on MHC-α and MHC-β. Aminoguandine treatment did not alter MHC composition, but it blunted formation of carbonyl adducts and decreases in actomyosin Ca2+-sensitive ATPase activity, syneresis, myocyte shortening, cardiac ejection fraction, fractional shortening and +dP/dt induced by diabetes. From these new data it can be concluded that in addition to isozyme switching, modification of MHC by RCS also contributes to the inotropic decline seen during diabetes. PMID:20359464

  4. Nature of Amide Carbonyl−Carbonyl Interactions in Proteins

    PubMed Central

    2010-01-01

    Noncovalent interactions define and modulate biomolecular structure, function, and dynamics. In many protein secondary structures, an intimate interaction exists between adjacent carbonyl groups of the main-chain amide bonds. As this short contact contributes to the energetics of protein conformational stability as well as protein−ligand interactions, understanding its nature is crucial. The intimacy of the carbonyl groups could arise from a charge−charge or dipole−dipole interaction, or n→π * electronic delocalization. This last putative origin, which is reminiscent of the Bürgi−Dunitz trajectory, involves delocalization of the lone pairs (n) of the oxygen (Oi−1) of a peptide bond over the antibonding orbital (π*) of the carbonyl group (Ci=Oi) of the subsequent peptide bond. By installing isosteric chemical substituents in a peptidic model system and using NMR spectroscopy, X-ray diffraction analysis, and ab initio calculations to analyze the consequences, the intimate interaction between adjacent carbonyl groups is shown to arise primarily from n→π* electronic delocalization. This finding has implications for organic, biological, and medicinal chemistry. PMID:19469574

  5. Methyl substituted polyimides containing carbonyl and ether connecting groups

    NASA Technical Reports Server (NTRS)

    Hergenrother, Paul M. (Inventor); Havens, Stephen J. (Inventor)

    1992-01-01

    Polyimides were prepared from the reaction of aromatic dianhydrides with novel aromatic diamines having carbonyl and ether groups connecting aromatic rings containing pendant methyl groups. The methyl substituent polyimides exhibit good solubility and form tough, strong films. Upon exposure to ultraviolet irradiation and/or heat, the methyl substituted polyimides crosslink to become insoluble.

  6. Metal-Diazo Radicals of α-Carbonyl Diazomethanes

    PubMed Central

    Li, Feifei; Xiao, Longqiang; Liu, Lijian

    2016-01-01

    Metal-diazo radicals of α-carbonyl diazomethanes are new members of the radical family and are precursors to metal-carbene radicals. Herein, using electron paramagnetic resonance spectroscopy with spin-trapping, we detect diazo radicals of α-carbonyl diazomethanes, induced by [RhICl(cod)]2, [CoII(por)] and PdCl2, at room temperature. The unique quintet signal of the Rh-diazo radical was observed in measurements of α-carbonyl diazomethane adducts of [RhICl(cod)]2 in the presence of 5,5-dimethyl-pyrroline-1-N-oxide (DMPO). DFT calculations indicated that 97.2% of spin density is localized on the diazo moiety. Co- and Pd-diazo radicals are EPR silent but were captured by DMPO to form spin adducts of DMPO-N∙ (triplet-of-sextets signal). The spin-trapping also provides a powerful tool for detection of metal-carbene radicals, as evidenced by the DMPO-trapped carbene radicals (DMPO-C∙, sextet signal) and 2-methyl-2-nitrosopropane-carbene adducts (MNP-C∙, doublet-of-triplets signal). The transformation of α-carbonyl diazomethanes to metal-carbene radicals was confirmed to be a two-step process via metal-diazo radicals. PMID:26960916

  7. Exploring the biology of lipid peroxidation-derived protein carbonylation.

    PubMed

    Fritz, Kristofer S; Petersen, Dennis R

    2011-09-19

    The sustained overproduction of reactive oxygen and nitrogen species results in an imbalance of cellular prooxidant-antioxidant systems and is implicated in numerous disease states, including alcoholic liver disease, cancer, neurological disorders, inflammation, and cardiovascular disease. The accumulation of reactive aldehydes resulting from sustained oxidative stress and lipid peroxidation is an underlying factor in the development of these pathologies. Determining the biochemical factors that elicit cellular responses resulting from protein carbonylation remains a key element to developing therapeutic approaches and ameliorating disease pathologies. This review details our current understanding of the generation of reactive aldehydes via lipid peroxidation resulting in protein carbonylation, focusing on pathophysiologic factors associated with 4-hydroxynonenal-protein modification. Additionally, an overview of in vitro and in vivo model systems used to study the physiologic impact of protein carbonylation is presented. Finally, an update of the methods commonly used in characterizing protein modification by reactive aldehydes provides an overview of isolation techniques, mass spectrometry, and computational biology. It is apparent that research in this area employing state-of-the-art proteomics, mass spectrometry, and computational biology is rapidly evolving, yielding foundational knowledge concerning the molecular mechanisms of protein carbonylation and its relation to a spectrum of diseases associated with oxidative stress. PMID:21812433

  8. Cobalt carbonyl catalyzed olefin hydroformylation in supercritical carbon dioxide

    SciTech Connect

    Rathke, J.W.; Klingler, R.J.

    1992-12-31

    A method of olefin hydroformylation is provided wherein an olefin reacts with a carbonyl catalyst and with reaction gases such as hydrogen and carbon monoxide in the presence of a supercritical reaction solvent, such as carbon dioxide. The invention provides higher yields of n-isomer product without the gas-liquid mixing rate limitation seen in conventional Oxo processes using liquid media.

  9. Synthesis, structure, photophysical and catalytic properties of CuI-Iodide complexes of di-imine ligands

    NASA Astrophysics Data System (ADS)

    Mondal, Jahangir; Ghorai, Anupam; Singh, Sunil K.; Saha, Rajat; Patra, Goutam K.

    2016-03-01

    Two new multifunctional CuII based complexes [CuI(L1)] (1) and [Cu2(μ-I)2(L2)] (2) with bidentate N-N donor ligands L1 and imino-pyridyl ligand L2 have been synthesized and characterized by elemental analysis, IR, UV-Vis, NMR and single crystal X-ray crystallography. The bidentate di-imine ligand (L1) forms monomeric CuI complex (1) whereas the bis-bidentate di-imine ligand (L2) favours the formation of dimeric CuI complex (2) in association with two bridging iodides. Structural analysis reveals that in complex 1 each monomeric units are connected by π⋯π and C-H⋯π interactions to form 3D supramolecular structure whereas in complex 2 each molecules are connected by only π⋯π interactions to form 3D supramolecular structure. The photoluminescence properties of the complexes have been studied at room temperature. Theoretical analysis shows that HOMO is focused on the Cu and iodides while LUMO is focused on di-imine ligands and the luminescence behaviour arises due to metal to ligand charge transfer (MLCT) and halide to ligand charge transfer (XLCT). The complexes 1 and 2 are effective catalysts for the synthesis of 2-substituted benzoxazoles.

  10. 40 CFR 721.10409 - Poly(oxyalkylenediyl), .alpha. - [ [ [methyl - 3 - [ [ [ (polyfluoroalkyl)oxy]carbonyl ] amino...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Poly(oxyalkylenediyl), .alpha... Poly(oxyalkylenediyl), .alpha. - carbonyl ] amino] phenyl]amino]carbonyl] - .omega. - methoxy... identified generically as poly(oxyalkylenediyl), .alpha.- carbonyl]amino]phenyl]amino]...

  11. Proton therapy

    MedlinePlus

    ... skin redness in the radiation area, and temporary hair loss. AFTER THE PROCEDURE Following proton therapy, you should be able to resume your normal activities. You will likely see your doctor every 3 to 4 months for a follow-up exam.

  12. Experimental observation of supramolecular carbonyl-π/π-π/π-carbonyl assemblies of Cu II complex of iminodiacetate and dipyridylamine

    NASA Astrophysics Data System (ADS)

    Kumar Seth, Saikat; Dey, Biswajit; Kar, Tanusree; Mukhopadhyay, Subrata

    2010-06-01

    A mononuclear Cu II complex [Cu(IDA)(2,2'-dypam)(H 2O)]·H 2O ( 1) where H 2IDA and 2,2'-dypam are iminodiacetic acid and 2,2´-dipyridylamine, respectively, has been synthesized and characterized by X-ray single crystal structure analysis. The Cu(II) atom exhibits an unsymmetrical elongated octahedral coordination type 4 + 1 + 1. X-ray crystallography reveals that complex ( 1) has an unprecedented fac-O 2 + N(apical) IDA conformation, in the trans-site of Cu-N (IDA-like) bond, in contrast with structural co-relations for complexes with Cu/(IDA or IDA-like)/N-heterocyclic donor ratio 1/1/2 and closely related compounds fac-NO + O(apical) IDA-like conformation and one N-heterocyclic donor in the trans-site to the Cu-N (IDA-like) bond. These findings are attributed to the influence of π-π stacking, C-H⋯π interactions in the molecular recognition process. Moreover, the aromatic moieties of 2,2'-dypam are engaged in carbonyl⋯π interaction with the non-coordinated carbonyl groups of IDA ligand and giving rise to a remarkable supramolecular carbonyl-π/π-π/π-carbonyl interactions.

  13. Dopamine-assisted deposition of poly (ethylene imine) for efficient heparinization.

    PubMed

    Luo, Rifang; Wang, Xin; Deng, Jinchuan; Zhang, Hao; Maitz, Manfred F; Yang, Li; Wang, Jin; Huang, Nan; Wang, Yunbing

    2016-08-01

    Mussel-inspired self-polymerization of dopamine in the presence of catechols and amines can be used to form coatings on various substrates. In this work dopamine was co-polymerized with poly (ethylene imine) (PEI) to form coatings on 316L stainless steel (SS). The coating formation was confirmed by Fourier transform infrared spectra (FTIR) and X-ray photoelectron spectroscopy (XPS). Compared with a pure polydopamine coating, such hybrid coating presented a higher ratio of nitrogen and increased zeta potential due to the introduction of PEI components. QCM measurement showed good affinity for heparin immobilization on the amine-rich surfaces. Moreover, the heparin-binding surface significantly suppressed platelet adhesion and activation. Further, the interaction with vascular cells, like endothelial cells (ECs) and smooth muscle cells (SMCs) was also investigated. The heparin coating not only decreased the cytotoxicity of amines on ECs, but also significantly inhibited SMCs proliferation. These results showed that the hybrid coating allowed effective heparin immobilization, providing a promising platform for vascular devices modification. PMID:27070056

  14. Coarse-grained simulations of poly(propylene imine) dendrimers in solution.

    PubMed

    Smeijers, A F; Markvoort, A J; Pieterse, K; Hilbers, P A J

    2016-02-21

    The behavior of poly(propylene imine) (PPI) dendrimers in concentrated solutions has been investigated using molecular dynamics simulations containing up to a thousand PPI dendrimers of generation 4 or 5 in explicit water. To deal with large system sizes and time scales required to study the solutions over a wide range of dendrimer concentrations, a previously published coarse-grained model was applied. Simulation results on the radius of gyration, structure factor, intermolecular spacing, dendrimer interpenetration, and water penetration are compared with available experimental data, providing a clear concentration dependent molecular picture of PPI dendrimers. It is shown that with increasing concentration the dendrimer volume diminishes accompanied by a reduction of internalized water, ultimately resulting in solvent filled cavities between stacked dendrimers. Concurrently dendrimer interpenetration increases only slightly, leaving each dendrimer a separate entity also at high concentrations. Moreover, we compare apparent structure factors, as calculated in experimental studies relying on the decoupling approximation and the constant atomic form factor assumption, with directly computed structure factors. We demonstrate that these already diverge at rather low concentrations, not because of small changes in form factor, but rather because the decoupling approximation fails as monomer positions of separate dendrimers become correlated at concentrations well below the overlap concentration. PMID:26896998

  15. On the mechanism of imine elimination from Fischer tungsten carbene complexes

    PubMed Central

    Veit, Philipp

    2016-01-01

    Summary (Aminoferrocenyl)(ferrocenyl)carbene(pentacarbonyl)tungsten(0) (CO)5W=C(NHFc)Fc (W(CO) 5 ( E -2)) is synthesized by nucleophilic substitution of the ethoxy group of (CO)5W=C(OEt)Fc (M(CO) 5 (1 Et )) by ferrocenyl amide Fc-NH– (Fc = ferrocenyl). W(CO) 5 ( E -2) thermally and photochemically eliminates bulky E-1,2-diferrocenylimine (E -3) via a formal 1,2-H shift from the N to the carbene C atom. Kinetic and mechanistic studies to the formation of imine E -3 are performed by NMR, IR and UV–vis spectroscopy and liquid injection field desorption ionization (LIFDI) mass spectrometry as well as by trapping experiments for low-coordinate tungsten complexes with triphenylphosphane. W(CO) 5 ( E -2) decays thermally in a first-order rate-law with a Gibbs free energy of activation of ΔG ‡ 298K = 112 kJ mol−1. Three proposed mechanistic pathways are taken into account and supported by detailed (time-dependent) densitiy functional theory [(TD)-DFT] calculations. The preferred pathway is initiated by an irreversible CO dissociation, followed by an oxidative addition/pseudorotation/reductive elimination pathway with short-lived, elusive seven-coordinate hydrido tungsten(II) intermediates cis (N,H)-W(CO) 4 (H)( Z -15) and cis (C,H)-W(CO) 4 (H)( Z -15). PMID:27559381

  16. On the mechanism of imine elimination from Fischer tungsten carbene complexes.

    PubMed

    Veit, Philipp; Förster, Christoph; Heinze, Katja

    2016-01-01

    (Aminoferrocenyl)(ferrocenyl)carbene(pentacarbonyl)tungsten(0) (CO)5W=C(NHFc)Fc (W(CO) 5 ( E -2)) is synthesized by nucleophilic substitution of the ethoxy group of (CO)5W=C(OEt)Fc (M(CO) 5 (1 (Et) )) by ferrocenyl amide Fc-NH(-) (Fc = ferrocenyl). W(CO) 5 ( E -2) thermally and photochemically eliminates bulky E-1,2-diferrocenylimine ( E -3) via a formal 1,2-H shift from the N to the carbene C atom. Kinetic and mechanistic studies to the formation of imine E -3 are performed by NMR, IR and UV-vis spectroscopy and liquid injection field desorption ionization (LIFDI) mass spectrometry as well as by trapping experiments for low-coordinate tungsten complexes with triphenylphosphane. W(CO) 5 ( E -2) decays thermally in a first-order rate-law with a Gibbs free energy of activation of ΔG (‡) 298K = 112 kJ mol(-1). Three proposed mechanistic pathways are taken into account and supported by detailed (time-dependent) densitiy functional theory [(TD)-DFT] calculations. The preferred pathway is initiated by an irreversible CO dissociation, followed by an oxidative addition/pseudorotation/reductive elimination pathway with short-lived, elusive seven-coordinate hydrido tungsten(II) intermediates cis (N,H)-W(CO) 4 (H)( Z -15) and cis (C,H)-W(CO) 4 (H)( Z -15). PMID:27559381

  17. A NADH-accepting imine reductase variant: Immobilization and cofactor regeneration by oxidative deamination.

    PubMed

    Gand, Martin; Thöle, Christian; Müller, Hubertus; Brundiek, Henrike; Bashiri, Ghader; Höhne, Matthias

    2016-07-20

    Engineering cofactor specificity of enzymes is a promising approach that can expand the application of enzymes for biocatalytic production of industrially relevant chemicals. Until now, only NADPH-dependent imine reductases (IREDs) are known. This limits their applications to reactions employing whole cells as a cost-efficient cofactor regeneration system. For applications of IREDs as cell-free catalysts, (i) we created an IRED variant showing an improved activity for NADH. With rational design we were able to identify four residues in the (R)-selective IRED from Streptomyces GF3587 (IR-Sgf3587), which coordinate the 2'-phosphate moiety of the NADPH cofactor. From a set of 15 variants, the highest NADH activity was caused by the single amino acid exchange K40A resulting in a 3-fold increased acceptance of NADH. (ii) We showed its applicability using an immobilisate obtained either from purified enzyme or from lysate using the EziG(™) carriers. Applying the variant and NADH, we reached 88% conversion in a preparative scale biotransformation when employing 4% (w/v) 2-methylpyrroline. (iii) We demonstrated a one-enzyme cofactor regeneration approach using the achiral amine N-methyl-3-aminopentanone as a hydrogen donor co-substrate. PMID:27164259

  18. Phenolic carbonyls undergo rapid aqueous photodegradation to form low-volatility, light-absorbing products

    NASA Astrophysics Data System (ADS)

    Smith, Jeremy D.; Kinney, Haley; Anastasio, Cort

    2016-02-01

    We investigated the aqueous photochemistry of six phenolic carbonyls - vanillin, acetovanillone, guaiacyl acetone, syringaldehyde, acetosyringone, and coniferyl aldehyde - that are emitted from wood combustion. The phenolic carbonyls absorb significant amounts of solar radiation and decay rapidly via direct photodegradation, with lifetimes (τ) of 13-140 min under Davis, CA winter solstice sunlight at midday (solar zenith angle = 62°). The one exception is guaiacyl acetone, where the carbonyl group is not directly connected to the aromatic ring: This species absorbs very little sunlight and undergoes direct photodegradation very slowly (τ > 103 min). We also found that the triplet excited states (3C*) of the phenolic carbonyls rapidly oxidize syringol (a methoxyphenol without a carbonyl group), on timescales of 1-5 h for solutions containing 5 μM phenolic carbonyl. The direct photodegradation of the phenolic carbonyls, and the oxidation of syringol by 3C*, both efficiently produce low volatility products, with SOA mass yields ranging from 80 to 140%. Contrary to most aliphatic carbonyls, under typical fog conditions we find that the primary sink for the aromatic phenolic carbonyls is direct photodegradation in the aqueous phase. In areas of significant wood combustion, phenolic carbonyls appear to be small but significant sources of aqueous SOA: over the course of a few hours, nearly all of the phenolic carbonyls will be converted to SOA via direct photodegradation, enhancing the POA mass from wood combustion by approximately 3-5%.

  19. Nuclear chemistry. Synthesis and detection of a seaborgium carbonyl complex.

    PubMed

    Even, J; Yakushev, A; Düllmann, Ch E; Haba, H; Asai, M; Sato, T K; Brand, H; Di Nitto, A; Eichler, R; Fan, F L; Hartmann, W; Huang, M; Jäger, E; Kaji, D; Kanaya, J; Kaneya, Y; Khuyagbaatar, J; Kindler, B; Kratz, J V; Krier, J; Kudou, Y; Kurz, N; Lommel, B; Miyashita, S; Morimoto, K; Morita, K; Murakami, M; Nagame, Y; Nitsche, H; Ooe, K; Qin, Z; Schädel, M; Steiner, J; Sumita, T; Takeyama, M; Tanaka, K; Toyoshima, A; Tsukada, K; Türler, A; Usoltsev, I; Wakabayashi, Y; Wang, Y; Wiehl, N; Yamaki, S

    2014-09-19

    Experimental investigations of transactinoide elements provide benchmark results for chemical theory and probe the predictive power of trends in the periodic table. So far, in gas-phase chemical reactions, simple inorganic compounds with the transactinoide in its highest oxidation state have been synthesized. Single-atom production rates, short half-lives, and harsh experimental conditions limited the number of experimentally accessible compounds. We applied a gas-phase carbonylation technique previously tested on short-lived molybdenum (Mo) and tungsten (W) isotopes to the preparation of a carbonyl complex of seaborgium, the 106th element. The volatile seaborgium complex showed the same volatility and reactivity with a silicon dioxide surface as those of the hexacarbonyl complexes of the lighter homologs Mo and W. Comparison of the product's adsorption enthalpy with theoretical predictions and data for the lighter congeners supported a Sg(CO)6 formulation. PMID:25237098

  20. Role of Carbonyl Modifications on Aging-Associated Protein Aggregation

    NASA Astrophysics Data System (ADS)

    Tanase, Maya; Urbanska, Aleksandra M.; Zolla, Valerio; Clement, Cristina C.; Huang, Liling; Morozova, Kateryna; Follo, Carlo; Goldberg, Michael; Roda, Barbara; Reschiglian, Pierluigi; Santambrogio, Laura

    2016-01-01

    Protein aggregation is a common biological phenomenon, observed in different physiological and pathological conditions. Decreased protein solubility and a tendency to aggregate is also observed during physiological aging but the causes are currently unknown. Herein we performed a biophysical separation of aging-related high molecular weight aggregates, isolated from the bone marrow and splenic cells of aging mice and followed by biochemical and mass spectrometric analysis. The analysis indicated that compared to younger mice an increase in protein post-translational carbonylation was observed. The causative role of these modifications in inducing protein misfolding and aggregation was determined by inducing carbonyl stress in young mice, which recapitulated the increased protein aggregation observed in old mice. Altogether our analysis indicates that oxidative stress-related post-translational modifications accumulate in the aging proteome and are responsible for increased protein aggregation and altered cell proteostasis.

  1. Hydrogenation of coal liquid utilizing a metal carbonyl catalyst

    DOEpatents

    Feder, Harold M.; Rathke, Jerome W.

    1979-01-01

    Coal liquid having a dissolved transition metal, catalyst as a carbonyl complex such as Co.sub.2 (CO.sub.8) is hydrogenated with hydrogen gas or a hydrogen donor. A dissociating solvent contacts the coal liquid during hydrogenation to form an immiscible liquid mixture at a high carbon monoxide pressure. The dissociating solvent, e.g. ethylene glycol, is of moderate coordinating ability, while sufficiently polar to solvate the transition metal as a complex cation along with a transition metal, carbonyl anion in solution at a decreased carbon monoxide pressure. The carbon monoxide pressure is reduced and the liquids are separated to recover the hydrogenated coal liquid as product. The dissociating solvent with the catalyst in ionized form is recycled to the hydrogenation step at the elevated carbon monoxide pressure for reforming the catalyst complex within fresh coal liquid.

  2. Metal Carbonyl-Hydrosilane Reactions and Hydrosilation Catalysis

    SciTech Connect

    Cutler, A. R.

    2001-04-14

    Manganese carbonyl complexes serve as hydrosilation precatalysts for selectively transforming a carbonyl group into a siloxy methylene or a fully reduced methylene group. Substrates of interest include (1) aldehydes, ketones, carboxylic acids, silyl esters, and esters, and (2) their organometallic acyl counterparts. Three relevant catalytic reactions are shown. Two types of manganese precatalysts have been reported: (a) alkyl and acyl complexes (L)(C0){sub 4}MnR [L = CO, PPh{sub 3}; R = COCH{sub 3}, COPh, CH{sub 3}] and (b) halides (CO){sub 5}MnX and [(CO){sub 4}MnX]{sub 2} (X = Br, I). The former promote hydrosilation and deoxygenation catalysis; the latter promote dehydrogenative silation of alcohols and carboxylic acids as well as hydrosilation and deoxygenation of some metallocarboxylic acid derivatives. In every case studied, these Mn precatalysts are far more reactive or selective than traditional Rh(I) precatalysts.

  3. Role of Carbonyl Modifications on Aging-Associated Protein Aggregation

    PubMed Central

    Tanase, Maya; Urbanska, Aleksandra M.; Zolla, Valerio; Clement, Cristina C.; Huang, Liling; Morozova, Kateryna; Follo, Carlo; Goldberg, Michael; Roda, Barbara; Reschiglian, Pierluigi; Santambrogio, Laura

    2016-01-01

    Protein aggregation is a common biological phenomenon, observed in different physiological and pathological conditions. Decreased protein solubility and a tendency to aggregate is also observed during physiological aging but the causes are currently unknown. Herein we performed a biophysical separation of aging-related high molecular weight aggregates, isolated from the bone marrow and splenic cells of aging mice and followed by biochemical and mass spectrometric analysis. The analysis indicated that compared to younger mice an increase in protein post-translational carbonylation was observed. The causative role of these modifications in inducing protein misfolding and aggregation was determined by inducing carbonyl stress in young mice, which recapitulated the increased protein aggregation observed in old mice. Altogether our analysis indicates that oxidative stress-related post-translational modifications accumulate in the aging proteome and are responsible for increased protein aggregation and altered cell proteostasis. PMID:26776680

  4. [Carbonyl stress and oxidatively modified proteins in chronic renal failure].

    PubMed

    Bargnoux, A-S; Morena, M; Badiou, S; Dupuy, A-M; Canaud, B; Cristol, J-P

    2009-01-01

    Oxidative stress is commonly observed in chronic renal failure patients resulting from an unbalance between overproduction of reactive oxygen species and impairement of defense mechanisms. Proteins appear as potential targets of uremia-induced oxidative stress and may undergo qualitative modifications. Proteins could be directly modified by reactive oxygen species which leads to amino acid oxydation and cross-linking. Proteins could be indirectly modified by reactive carbonyl compounds produced by glycoxidation and lipo-peroxidation. The resulting post-traductional modifications are known as carbonyl stress. In addition, thiols could be oxidized or could react with homocystein leading to homocysteinylation. Finally, tyrosin could be oxidized by myeloperoxidase leading to advanced oxidative protein products (AOPP). Oxidatively modified proteins are increased in chronic renal failure patients and may contribute to exacerbate the oxidative stress/inflammation syndrome. They have been involved in long term complications of uremia such as amyloidosis and accelerated atherosclerosis. PMID:19297289

  5. Structural Basis for Substrate Specificity in Human Monomeric Carbonyl Reductases

    PubMed Central

    El-Hawari, Yasser; Dunford, James E.; Kochan, Grazyna; Wsol, Vladimir; Martin, Hans-Joerg; Maser, Edmund; Oppermann, Udo

    2009-01-01

    Carbonyl reduction constitutes a phase I reaction for many xenobiotics and is carried out in mammals mainly by members of two protein families, namely aldo-keto reductases and short-chain dehydrogenases/reductases. In addition to their capacity to reduce xenobiotics, several of the enzymes act on endogenous compounds such as steroids or eicosanoids. One of the major carbonyl reducing enzymes found in humans is carbonyl reductase 1 (CBR1) with a very broad substrate spectrum. A paralog, carbonyl reductase 3 (CBR3) has about 70% sequence identity and has not been sufficiently characterized to date. Screening of a focused xenobiotic compound library revealed that CBR3 has narrower substrate specificity and acts on several orthoquinones, as well as isatin or the anticancer drug oracin. To further investigate structure-activity relationships between these enzymes we crystallized CBR3, performed substrate docking, site-directed mutagenesis and compared its kinetic features to CBR1. Despite high sequence similarities, the active sites differ in shape and surface properties. The data reveal that the differences in substrate specificity are largely due to a short segment of a substrate binding loop comprising critical residues Trp229/Pro230, Ala235/Asp236 as well as part of the active site formed by Met141/Gln142 in CBR1 and CBR3, respectively. The data suggest a minor role in xenobiotic metabolism for CBR3. Enhanced version This article can also be viewed as an enhanced version in which the text of the article is integrated with interactive 3D representations and animated transitions. Please note that a web plugin is required to access this enhanced functionality. Instructions for the installation and use of the web plugin are available in Text S1. PMID:19841672

  6. The modulation of carbonyl reductase 1 by polyphenols.

    PubMed

    Boušová, Iva; Skálová, Lenka; Souček, Pavel; Matoušková, Petra

    2015-01-01

    Carbonyl reductase 1 (CBR1), an enzyme belonging to the short-chain dehydrogenases/reductases family, has been detected in all human tissues. CBR1 catalyzes the reduction of many xenobiotics, including important drugs (e.g. anthracyclines, nabumetone, bupropion, dolasetron) and harmful carbonyls and quinones. Moreover, it participates in the metabolism of a number of endogenous compounds and it may play a role in certain pathologies. Plant polyphenols are not only present in many human food sources, but are also a component of many popular dietary supplements and herbal medicines. Many studies reviewed herein have demonstrated the potency of certain flavonoids, stilbenes and curcuminoids in the inhibition of the activity of CBR1. Interactions of these polyphenols with transcriptional factors, which regulate CBR1 expression, have also been reported in several studies. As CBR1 plays an important role in drug metabolism as well as in the protection of the organism against potentially harmful carbonyls, the modulation of its expression/activity may have significant pharmacological and/or toxicological consequences. Some polyphenols (e.g. luteolin, apigenin and curcumin) have been shown to be very potent CBR1 inhibitors. The inhibition of CBR1 seems useful regarding the increased efficacy of anthracycline therapy, but it may cause the worse detoxification of reactive carbonyls. Nevertheless, all known information about the interactions of polyphenols with CBR1 have only been based on the results of in vitro studies. With respect to the high importance of CBR1 and the frequent consumption of polyphenols, in vivo studies would be very helpful for the evaluation of risks/benefits of polyphenol interactions with CBR1. PMID:26415702

  7. Iron(III)-catalysed carbonyl-olefin metathesis.

    PubMed

    Ludwig, Jacob R; Zimmerman, Paul M; Gianino, Joseph B; Schindler, Corinna S

    2016-05-19

    The olefin metathesis reaction of two unsaturated substrates is one of the most powerful carbon-carbon-bond-forming reactions in organic chemistry. Specifically, the catalytic olefin metathesis reaction has led to profound developments in the synthesis of molecules relevant to the petroleum, materials, agricultural and pharmaceutical industries. These reactions are characterized by their use of discrete metal alkylidene catalysts that operate via a well-established mechanism. While the corresponding carbonyl-olefin metathesis reaction can also be used to construct carbon-carbon bonds, currently available methods are scarce and severely hampered by either harsh reaction conditions or the required use of stoichiometric transition metals as reagents. To date, no general protocol for catalytic carbonyl-olefin metathesis has been reported. Here we demonstrate a catalytic carbonyl-olefin ring-closing metathesis reaction that uses iron, an Earth-abundant and environmentally benign transition metal, as a catalyst. This transformation accommodates a variety of substrates and is distinguished by its operational simplicity, mild reaction conditions, high functional-group tolerance, and amenability to gram-scale synthesis. We anticipate that these characteristics, coupled with the efficiency of this reaction, will allow for further advances in areas that have historically been enhanced by olefin metathesis. PMID:27120158

  8. Protein Carbonylation, Mitochondrial Dysfunction, and Insulin Resistance123

    PubMed Central

    Frohnert, Brigitte I.; Bernlohr, David A.

    2013-01-01

    Oxidative stress has been identified as a common mechanism for cellular damage and dysfunction in a wide variety of disease states. Current understanding of the metabolic changes associated with obesity and the development of insulin resistance has focused on the role of oxidative stress and its interaction with inflammatory processes at both the tissue and organismal level. Obesity-related oxidative stress is an important contributing factor in the development of insulin resistance in the adipocyte as well as the myocyte. Moreover, oxidative stress has been linked to mitochondrial dysfunction, and this is thought to play a role in the metabolic defects associated with oxidative stress. Of the various effects of oxidative stress, protein carbonylation has been identified as a potential mechanism underlying mitochondrial dysfunction. As such, this review focuses on the relationship between protein carbonylation and mitochondrial biology and addresses those features that point to either the causal or casual relationship of lipid peroxidation–induced protein carbonylation as a determining factor in mitochondrial dysfunction. PMID:23493532

  9. Fluorimetric screening assay for protein carbonyl evaluation in biological samples.

    PubMed

    Stocker, P; Ricquebourg, E; Vidal, N; Villard, C; Lafitte, D; Sellami, L; Pietri, S

    2015-08-01

    Many assays are available for the detection of protein carbonyls (PCs). Currently, the measurement of PC groups after their derivatization with 2,4-dinitrophenol hydrazine (DNPH) is widely used for measuring protein oxidation in biological samples. However, this method includes several washing steps. In this context, we have developed a rapid, sensitive, and accurate fluorimetric method adapted to 96-well microplates for the convenient assessment of protein carbonyl level in biological samples. The method reported here is based on the reaction of carbonyl content in proteins with 7-hydrazino-4-nitrobenzo-2,1,3-oxadiazole (NBDH) to form highly fluorescent derivatives via hydrazone formation. PCs were determined using the DNPH and NBDH assays in fully reduced bovine serum albumin (BSA) and plasma and liver homogenates obtained from healthy control rats up the addition of various amounts of HOCl-oxidized BSA (OxBSA). Using the NBDH assay, PC concentrations as low as 0.2 nmol/mg were detected with precision as low as 5%. Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectroscopy was used to successfully identify the formation of the NBDH adducts after derivatization with standard oxidized peptides. Finally, the two methods were further used for PC determination in plasma and liver samples from diabetic and normal rats, showing that the NBDH assay can be reliably used in biological experiments. PMID:25933703

  10. Glial cell line-derived neurotrophic factor gene delivery via a polyethylene imine grafted chitosan carrier

    PubMed Central

    Peng, Yu-Shiang; Lai, Po-Liang; Peng, Sydney; Wu, His-Chin; Yu, Siang; Tseng, Tsan-Yun; Wang, Li-Fang; Chu, I-Ming

    2014-01-01

    Parkinson’s disease is known to result from the loss of dopaminergic neurons. Direct intracerebral injections of high doses of recombinant glial cell line-derived neurotrophic factor (GDNF) have been shown to protect adult nigral dopaminergic neurons. Because GDNF does not cross the blood–brain barrier, intracerebral gene transfer is an ideal option. Chitosan (CHI) is a naturally derived material that has been used for gene transfer. However, the low water solubility often leads to decreased transfection efficiency. Grafting of highly water-soluble polyethylene imines (PEI) and polyethylene glycol onto polymers can increase their solubility. The purpose of this study was to design a non-viral gene carrier with improved water solubility as well as enhanced transfection efficiency for treating Parkinsonism. Two molecular weights (Mw =600 and 1,800 g/mol) of PEI were grafted onto CHI (PEI600-g-CHI and PEI1800-g-CHI, respectively) by opening the epoxide ring of ethylene glycol diglycidyl ether (EX-810). This modification resulted in a non-viral gene carrier with less cytotoxicity. The transfection efficiency of PEI600-g-CHI/deoxyribonucleic acid (DNA) polyplexes was significantly higher than either PEI1800-g-CHI/DNA or CHI/DNA polyplexes. The maximal GDNF expression of PEI600-g-CHI/DNA was at the polymer:DNA weight ratio of 10:1, which was 1.7-fold higher than the maximal GDNF expression of PEI1800-g-CHI/DNA. The low toxicity and high transfection efficiency of PEI600-g-CHI make it ideal for application to GDNF gene therapy, which has potential for the treatment of Parkinson’s disease. PMID:25061293

  11. Crystal structures of four chiral imine-substituted thio-phene derivatives.

    PubMed

    Hernández-Téllez, Guadalupe; Bernès, Sylvain; Mendoza, Angel; Ríos-Merino, Francisco Javier; Moreno, Gloria E; Portillo, Oscar; Gutiérrez, René

    2016-03-01

    A series of thio-phenes substituted in positions 2 and 5 by imine groups have been synthesized using a solvent-free approach, and their crystal structures determined. The substituents are chiral groups, and the expected absolute configuration for each mol-ecule was confirmed by refinement of the Flack parameter. The compounds are 2,5-bis-[(S)-(+)-(1,2,3,4-tetra-hydro-naphthalen-1-yl)imino]-thio-phene, C26H26N2S, (I), 2,5-bis-{[(R)-(-)-1-(4-meth-oxy-phen-yl)eth-yl]imino-meth-yl}thio-phene, C24H26N2O2S, (II), 2,5-bis-{[(R)-(-)-1-(4-fluoro-phen-yl)eth-yl]imino-meth-yl}thio-phene, C22H20F2N2S, (III), and 2,5-bis-{[(S)-(+)-1-(4-chloro-phen-yl)eth-yl]imino-meth-yl}thio-phene, C22H20Cl2N2S, (IV). A common feature of all four mol-ecules is the presence of twofold symmetry. For (I), which crystallizes in the triclinic space group P1, this symmetry is non-crystallographic, but for (II) in C2 and the isomorphous structures (III) and (IV) that crystallize in P21212, the twofold symmetry is crystallographically imposed with one half of each mol-ecule in the asymmetric unit. The comparable mol-ecular symmetry in the four structures is also reflected in similar packing, with mol-ecules aggregated to form chains through weak C-H⋯S inter-actions. PMID:27006806

  12. Hydroxyphenylation of Histone Lysines: Post-translational Modification by Quinone Imines.

    PubMed

    Ravindra, Kodihalli C; Trudel, Laura J; Wishnok, John S; Wogan, Gerald N; Tannenbaum, Steven R; Skipper, Paul L

    2016-05-20

    Monocyclic aromatic amines are widespread environmental contaminants with multiple sources such as combustion products, pharmaceuticals, and pesticides. Their phenolic metabolites are converted intracellularly to electrophilic quinone imines upon autoxidation and can embed in the cellular matrix through a transimination reaction that leaves a redox-active residue as a substituent of lysine side-chain amino groups. To demonstrate the occurrence of this process within the cellular nucleus, Chinese hamster ovary AA8 cells were treated with the para-phenol of 3,5-dimethylamine, after which the histone proteins were isolated, derivatized, and subjected to tryptic digestion. The resulting peptides were analyzed by tandem mass spectrometry to determine which lysines were modified. Nine residues in histones H2A, H2B, and H4 were identified; these were located in histone tails, close to where DNA makes contact with the nuclear core particle, elsewhere on the protein surface, and deep within the core. Kinetics of disappearance of the modified lysines in cultured cells was determined using isotope-dilution mass spectrometry. AA8 cells were also transfected with the genetically encoded hydrogen peroxide biosensor HyPer in constructs that lead to expression of HyPer in different cellular compartments. Challenging the resulting cells with the dimethylaminophenol resulted in sustained fluorescence emission in each of the compartments, demonstrating ongoing production of H2O2. The kinetics of modified lysine loss determined by mass spectrometry was consistent with persistence of HyPer fluorescence emission. We conclude that the para-phenol of 3,5-dimethylamine can become stably integrated into the histone proteins, which are minimally repaired, if at all, and function as a persistent source of intracellular H2O2. PMID:26866676

  13. Iridium-catalyzed enantioselective hydrogenation of imines in supercritical carbon dioxide

    SciTech Connect

    Kainz, S.; Brinkmann, A.; Leitner, W.; Pfaltz, A.

    1999-07-14

    Supercritical carbon dioxide (scCO{sub 2}) was shown to be a reaction medium with unique properties for highly efficient iridium-catalyzed enantioselective hydrogenation of prochiral imines. Cationic iridium(I) complexes with chiral phosphinodihydrooxazoles, modified with perfluoroalkyl groups in the ligand or in the anion, were synthesized and tested in the hydrogenation of N-(1-phenylethylidene)aniline. Both the side chains and the lipophilic anions increased the solubility, but the choice of the anion also had a dramatic effect on the enantioselectivity with tetrakis-3,5-bis(trifluoromethyl)phenylborate (BARF) leading to the highest asymmetric induction. (R)-N-phenyl-1-phenylethylamine was formed quantitatively within 1 h in scCO{sub 2}[d(CO{sub 2}) = 0.75 g mL{sup {minus}1}] at 40 C and a H{sub 2} pressure of 30 bar with enantiomeric excesses of up to 81% using 0.078 mol % catalyst. The use of scCO{sub 2} instead of conventional solvents such as CH{sub 2}Cl{sub 2} allowed the catalyst loading to be lowered significantly owing to a change in the rate profile of the reaction. the homogeneous nature of the catalytically active species under the reaction conditions was demonstrated and was found to depend strongly on the composition of the reaction mixture and especially on the presence of the substrate. Utilizing the selective extractive properties of scCO{sub 2}, the product could be readily separated from the catalyst, which could be recycled several times without significant loss of activity and enantioselectivity. High-pressure FT-IR and NMR investigations revealed that the reactivity of the products to form the corresponding carbamic acids plays an important role for the application of this new methodology.

  14. Silver nanoparticle monolayers on poly(ethylene imine) covered mica produced by colloidal self-assembly.

    PubMed

    Michna, Aneta; Adamczyk, Zbigniew; Siwek, Barbara; Oćwieja, Magdalena

    2010-05-15

    Monodisperse silver particles were synthesized according to the method of Creighton et al. by reduction of AgNO(3) solutions with NaBH(4) in the presence of polyvinyl alcohol as the stabilizing agent. Bulk characteristics of silver nanoparticles in aqueous solutions were carried out by measuring their extinction spectrum, fluorescence, diffusion coefficients using the PCS method and the electrophoretic mobilities. The average hydrodynamic diameter of PVA covered silver particles was 44 nm, being fairly independent of ionic strength and pH in the range of 3-9. It was also shown that the hydrodynamic radius did not change within prolonged storage of suspensions (up to 75 days), indicating that the sols were quite stable. A similar value of 45±8 nm was determined from SEM measurements. The electrophoretic mobility measurements showed that the zeta potential of silver nanoparticles was insensitive to pH and decreased with the ionic strength, attaining -45 mV for I=10(-5) M and -25 mV for I=10(-2) M. Additionally, the kinetics of silver particle deposition on mica modified by adsorption of a saturated layer of poly(ethylene imine) (PEI) was studied. Surface concentration was determined directly by counting the number of particles over various surface areas using the atomic force microscopy working in the semicontact mode. The maximum surface concentration for I=10(-3)M was 102 μm(-2), which corresponds to the coverage degree of 16%. The kinetic run and the maximum coverage value was in a good agreement with theoretical predictions stemming from the random sequential adsorption (RSA) model. This kinetic run allowed one to determine the size of Ag core, which was 20 nm and the thickness of the PVA layer, equal to 12 nm. PMID:20185145

  15. Crystal structures of four chiral imine-substituted thio­phene derivatives

    PubMed Central

    Hernández-Téllez, Guadalupe; Bernès, Sylvain; Mendoza, Angel; Ríos-Merino, Francisco Javier; Moreno, Gloria E.; Portillo, Oscar; Gutiérrez, René

    2016-01-01

    A series of thio­phenes substituted in positions 2 and 5 by imine groups have been synthesized using a solvent-free approach, and their crystal structures determined. The substituents are chiral groups, and the expected absolute configuration for each mol­ecule was confirmed by refinement of the Flack parameter. The compounds are 2,5-bis­[(S)-(+)-(1,2,3,4-tetra­hydro­naphthalen-1-yl)imino]­thio­phene, C26H26N2S, (I), 2,5-bis­{[(R)-(−)-1-(4-meth­oxy­phen­yl)eth­yl]imino­meth­yl}thio­phene, C24H26N2O2S, (II), 2,5-bis­{[(R)-(−)-1-(4-fluoro­phen­yl)eth­yl]imino­meth­yl}thio­phene, C22H20F2N2S, (III), and 2,5-bis­{[(S)-(+)-1-(4-chloro­phen­yl)eth­yl]imino­meth­yl}thio­phene, C22H20Cl2N2S, (IV). A common feature of all four mol­ecules is the presence of twofold symmetry. For (I), which crystallizes in the triclinic space group P1, this symmetry is non-crystallographic, but for (II) in C2 and the isomorphous structures (III) and (IV) that crystallize in P21212, the twofold symmetry is crystallographically imposed with one half of each mol­ecule in the asymmetric unit. The comparable mol­ecular symmetry in the four structures is also reflected in similar packing, with mol­ecules aggregated to form chains through weak C—H⋯S inter­actions. PMID:27006806

  16. 40 CFR 721.10409 - Poly(oxyalkylenediyl), .alpha.-[[[methyl-3-[[[(polyfluoroalkyl)oxy]carbonyl] amino]phenyl]amino...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Poly(oxyalkylenediyl), .alpha...(oxyalkylenediyl), .alpha.- carbonyl] amino]phenyl]amino]carbonyl]- .omega.-methoxy-(generic). (a) Chemical... as poly(oxyalkylenediyl), .alpha.- carbonyl]amino]phenyl]amino] carbonyl]-.omega.-methoxy- (PMN...

  17. 40 CFR 721.10409 - Poly(oxyalkylenediyl), .alpha.-[[[methyl-3-[[[(polyfluoroalkyl) oxy]carbonyl]amino]phenyl]amino...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Poly(oxyalkylenediyl), .alpha...(oxyalkylenediyl), .alpha.- carbonyl]amino]phenyl]amino] carbonyl]-.omega.-methoxy- (generic). (a) Chemical... as poly(oxyalkylenediyl), .alpha.- carbonyl]amino]phenyl]amino] carbonyl]-.omega.-methoxy- (PMN...

  18. Palladium(II) complexes with highly basic imidazolin-2-imines and their reactivity toward small bio-molecules.

    PubMed

    Bogojeski, Jovana; Volbeda, Jeroen; Freytag, Matthias; Tamm, Matthias; Bugarčić, Živadin D

    2015-10-21

    A series of novel Pd(ii) complexes with chelating mono(imidazolin-2-imine) and bis(imidazolin-2-imine) ligands were synthesized. The crystal structures of [Pd(DMEAIm(iPr))Cl2] and [Pd(DPENIm(iPr))Cl2] were determined by X-ray diffraction analysis. The reactivity of the six Pd(ii) complexes, namely, [Pd(en)Cl2], [Pd(EAIm(iPr))Cl2], [Pd(DMEAIm(iPr))Cl2], [Pd(DPENIm(iPr))Cl2], [Pd(BL(iPr))Cl2] and [Pd(DACH(Im(iPr))2)Cl2], were investigated. Spectrophotometric acid-base titrations were performed to determine the pKa values of the coordinated water molecules in [Pd(en)(H2O)2](2+), [Pd(EAIm(iPr))(H2O)2](2+), [Pd(DMEAIm(iPr))(H2O)2](2+), [Pd(DPENIm(iPr))(H2O)2](2+), [Pd(BL(iPr))(H2O)2](2+) and [Pd(DACH(Im(iPr))2)(H2O)2](2+). The substitution of the chloride ligands in these complexes by TU, l-Met, l-His and Gly was studied under pseudo-first-order conditions as a function of the nucleophile concentration and temperature using stopped-flow techniques; the sulfur-donor nucleophiles have shown better reactivity than nitrogen-donor nucleophiles. The obtained results indicate that there is a clear correlation between the nature of the imidazolin-2-imine ligands and the acid-base characteristics and reactivity of the resulting Pd(ii) complexes; the order of reactivity of the investigated Pd(ii) complexes is: [Pd(en)Cl2] > [Pd(EAIm(iPr))Cl2] > [Pd(DMEAIm(iPr))Cl2] > [Pd(DPENIm(iPr))Cl2] > [Pd(BL(iPr))Cl2] > [Pd(DACH(Im(iPr))2)Cl2]. The solubility measurements revealed good solubility of the studied imidazolin-2-imine complexes in water, despite the fact that these Pd(ii) complexes are neutral complexes. Based on the performed studies, three unusual features of the novel imidazolin-2-imine Pd(ii) complexes are observed, that is, good solubility in water, very low reactivity and high pKa values. The coordination geometries around the palladium atoms are distorted square-planar; the [Pd(DMEAIm(iPr))Cl2] complex displays Pd-N distances of 2.013(2) and 2.076(2) Å, while the [Pd

  19. Structure and conformation of protonated D-(+)-biotin in the unsolvated state.

    PubMed

    Fraschetti, Caterina; Filippi, Antonello; Guarcini, Laura; Steinmetz, Vincent; Speranza, Maurizio

    2015-05-21

    A combined computational and infrared multiphoton dissociation (IRMPD) spectroscopic investigation shows that protonated d-(+)-biotin, formed in the gas phase by ESI-MS, acquires a folded structure with proton bonding between the ureido and valeryl carbonyls, and that only a single conformer of such a structure predominates. A uniform frequency vs distance correlation function is proposed for the O(+)-H···O and N-H···O bonds involved in the folded conformers of O2'-protonated d-(+)-biotin in the gas phase which, therefore, depends exclusively on the corresponding geometric parameters. PMID:25938640

  20. Proton scaling

    SciTech Connect

    Canavan, Gregory H

    2009-01-01

    This note presents analytic estimates of the performance of proton beams in remote surveillance for nuclear materials. The analysis partitions the analysis into the eight steps used by a companion note: (1) Air scattering, (2) Neutron production in the ship and cargo, (3) Target detection probability, (4) Signal produced by target, (5) Attenuation of signal by ship and cargo, (6) Attenuation of signal by air, (7) Geometric dilution, and (8) Detector Efficiency. The above analyses indicate that the dominant air scattering and loss mechanisms for particle remote sensing are calculable with reliable and accepted tools. They make it clear that the conversion of proton beams into neutron sources rapidly goes to completion in all but thinnest targets, which means that proton interrogation is for all purposes executed by neutrons. Diffusion models and limiting approximations to them are simple and credible - apart from uncertainty over the cross sections to be used in them - and uncertainty over the structure of the vessels investigated. Multiplication is essentially unknown, in part because it depends on the details of the target and its shielding, which are unlikely to be known in advance. Attenuation of neutron fluxes on the way out are more complicated due to geometry, the spectrum of fission neutrons, and the details of their slowing down during egress. The attenuation by air is large but less uncertain. Detectors and technology are better known. The overall convolution of these effects lead to large but arguably tolerable levels of attenuation of input beams and output signals. That is particularly the case for small, mobile sensors, which can more than compensate for size with proximity to operate reliably while remaining below flux limits. Overall, the estimates used here appear to be of adequate accuracy for decisions. That assessment is strengthened by their agreement with companion calculations.

  1. [Chemical Characteristics and Sources of Atmospheric Carbonyls During the 2014 Beijing APEC].

    PubMed

    He, Xiao-lang; Tan, Ji-hua; Guo, Song-jun; Ma, Yong-liang; He, Ke-bin

    2016-03-15

    Pollution characteristic and variation trend of atmospheric carbonyls were investigated in November during the 2014 Beijing APEC. Formaldehyde, acetaldehyde and acetone were the dominant carbonyls, accounting for 82.66% of total carbonyls, and especially, formaldehyde accounted for 40.12% of total carbonyls. Atmospheric concentrations of total carbonyls decreased by around 64.10% after the clean air policy was carried out during the Beijing APEC, and the variation trend of carbonyls showed a similar pattern to those of other pollutants like PM₂.₅ during the APEC. Strong correlations (R² of 0.67-0.98) were observed among formaldehyde, acetaldehyde, acetone and total carbonyls during and after the APEC, indicating that they had similar sources; however, poor correlations (R² of -0.11-0.42 and 0.16-0.94, respectively) were observed before the APEC, implying different emission sources for ambient carbonyls. The calculated ratios of C1/C2, C2/C3 and OC/EC indicated that both vehicles and coal emissions were responsible for atmospheric carbonyls before the APEC, and emissions from coal burning were the major contributor to atmospheric carbonyls during and after the APEC, especially after the APEC. PMID:27337869

  2. Direct β-C(sp(3))-H Functionalization of Aliphatic Amines to α,β-Unsaturated Imines, Aldehydes, and Chromenes.

    PubMed

    Mandal, Sumana; Mahato, Sujit; Jana, Chandan K

    2015-08-01

    A metal-free method for direct β-C(sp(3))-H functionalization of aliphatic amine was developed. The method is based on a reaction that yields enamine directly from the corresponding aliphatic amine, which otherwise requires the aid of metallic reagent and/or external oxidant. The reaction is operationally simple, general, and highly efficient in functionalizing both cyclic and acyclic amines. Structurally diverse unsaturated imines were obtained from N-heterocycles, while acyclic amines provided 2-alkyl cinnamaldehyde and benzopyran derivatives with excellent E/Z-selectivity. PMID:26204435

  3. Synthesis of furans and pyrroles via migratory and double migratory cycloisomerization reactions of homopropargylic aldehydes and imines

    PubMed Central

    Shiroodi, Roohollah Kazem; Vera, Claudia I. Rivera; Dudnik, Alexander S.; Gevorgyan, Vladimir

    2015-01-01

    A novel gold-catalyzed divergent sysnthesis of furans and pyrroles employing readily available homopropargylic aldehydes and imines have been developed. The regiochemical outcome of this reaction is dependent on the substituent on the terminal alkyne of substrate. Thus, substrates possessing alkyl and aryl substituent at the alkyne moiety produce 2,3,5-substituted furans and pyrroles via a migratory cycloisomerizaton reaction. Whereas, their silicon analogues are capable to undergo a double migratory process leading to 2,3,4-substituted heterocycles. PMID:26185336

  4. Reactions of ozone with human skin lipids: Sources of carbonyls, dicarbonyls, and hydroxycarbonyls in indoor air

    PubMed Central

    Wisthaler, Armin; Weschler, Charles J.

    2010-01-01

    This study has used proton transfer reaction-mass spectrometry (PTR-MS) for direct air analyses of volatile products resulting from the reactions of ozone with human skin lipids. An initial series of small-scale in vitro and in vivo experiments were followed by experiments conducted with human subjects in a simulated office. The latter were conducted using realistic ozone mixing ratios (≈15 ppb with occupants present). Detected products included mono- and bifunctional compounds that contain carbonyl, carboxyl, or α-hydroxy ketone groups. Among these, three previously unreported dicarbonyls have been identified, and two previously unreported α-hydroxy ketones have been tentatively identified. The compounds detected in this study (excepting acetone) have been overlooked in surveys of indoor pollutants, reflecting the limitations of the analytical methods routinely used to monitor indoor air. The results are fully consistent with the Criegee mechanism for ozone reacting with squalene, the single most abundant unsaturated constituent of skin lipids, and several unsaturated fatty acid moieties in their free or esterified forms. Quantitative product analysis confirms that squalene is the major scavenger of ozone at the interface between room air and the human envelope. Reactions between ozone and human skin lipids reduce the mixing ratio of ozone in indoor air, but concomitantly increase the mixing ratios of volatile products and, presumably, skin surface concentrations of less volatile products. Some of the volatile products, especially the dicarbonyls, may be respiratory irritants. Some of the less volatile products may be skin irritants. PMID:19706436

  5. Theoretical and experimental (15)N NMR study of enamine-imine tautomerism of 4-trifluoromethyl[b]benzo-1,4-diazepine system.

    PubMed

    Semenov, Valentin A; Samultsev, Dmitry O; Rulev, Alexander Yu; Krivdin, Leonid B

    2015-12-01

    The tautomeric structure of 4-trifluoromethyl[b]benzo-1,4-diazepine system in solution has been evaluated by means of the calculation of (15)N NMR chemical shifts of individual tautomers in comparison with the averaged experimental shifts to show that the enamine-imine equilibrium is entirely shifted toward the imine form. The adequacy of the theoretical level used for the computation of (15)N NMR chemical shifts in this case has been verified based on the benchmark calculations in the series of the push-pull and captodative enamines together with related azomethynes, which demonstrated a good to excellent agreement with experiment. PMID:26290420

  6. On-surface synthesis of two-dimensional imine polymers with a tunable band gap: a combined STM, DFT and Monte Carlo investigation

    NASA Astrophysics Data System (ADS)

    Xu, Lirong; Yu, Yanxia; Lin, Jianbin; Zhou, Xin; Tian, Wei Quan; Nieckarz, Damian; Szabelski, Pawel; Lei, Shengbin

    2016-04-01

    Two-dimensional polymers are of great interest for many potential applications in nanotechnology. The preparation of crystalline 2D polymers with a tunable band gap is critical for their applications in nano-electronics and optoelectronics. In this work, we try to tune the band gap of 2D imine polymers by expanding the conjugation of the backbone of aromatic diamines both laterally and longitudinally. STM characterization reveals that the regularity of the 2D polymers can be affected by the existence of lateral bulky groups. Density functional theory (DFT) simulations discovered a significant narrowing of the band gap of imine 2D polymers upon the expansion of the conjugation of the monomer backbone, which has been confirmed experimentally by UV absorption measurements. Monte Carlo simulations help us to gain further insight into the controlling factors of the formation of regular 2D polymers, which demonstrated that based on the all rigid assumption, the coexistence of different conformations of the imine moiety has a significant effect on the regularity of the imine 2D polymers.Two-dimensional polymers are of great interest for many potential applications in nanotechnology. The preparation of crystalline 2D polymers with a tunable band gap is critical for their applications in nano-electronics and optoelectronics. In this work, we try to tune the band gap of 2D imine polymers by expanding the conjugation of the backbone of aromatic diamines both laterally and longitudinally. STM characterization reveals that the regularity of the 2D polymers can be affected by the existence of lateral bulky groups. Density functional theory (DFT) simulations discovered a significant narrowing of the band gap of imine 2D polymers upon the expansion of the conjugation of the monomer backbone, which has been confirmed experimentally by UV absorption measurements. Monte Carlo simulations help us to gain further insight into the controlling factors of the formation of regular 2D

  7. Discovery and Development of Pyridine-bis(imine) and Related Catalysts for Olefin Polymerization and Oligomerization.

    PubMed

    Small, Brooke L

    2015-09-15

    For over 40 years following the polyolefin catalyst discoveries of Hogan and Banks (Phillips) and Ziegler (Max Planck Institute), chemists traversed the periodic table searching for new transition metal and lanthanide-based olefin polymerization systems. Remarkably, none of these "hits" employed iron, that is, until three groups independently reported iron catalysts for olefin polymerization in the late 1990's. The history surrounding the discovery of these catalysts was only the beginning of their uniqueness, as the ensuing years have proven these systems remarkable in several regards. Of primary importance are the pyridine-bis(imine) ligands (herein referred to as PDI), which produced iron catalysts that are among the world's most active for ethylene polymerization, demonstrated "staying power" despite over 15 years of ligand improvement efforts, and generated highly active polymerization systems with cobalt, chromium, and vanadium. Although many ligands have been employed in iron-catalyzed polymerization, the PDI family has thus far provided the most information about iron's capabilities and tendencies. For example, iron systems tend to be highly selective for ethylene over higher olefins, making them strong candidates for producing highly crystalline polyethylene, or highly linear α-olefins. Iron PDI polymerizes propylene with 2,1-regiochemistry via a predominantly isotactic, chain end control mechanism. Because the first insertion proceeds via 1,2-regiochemistry, iron (and cobalt) PDI systems can be tailored to make highly linear dimers of α-olefins by "head-to-head" coupling, resulting from a switch in regiochemistry after the first insertion. Finally, PDI ligands, while not being surpassed in activity, have inspired the development of related ligand families and complexes, such as pendant donor diimines (PDD), which are also highly efficient at producing linear α-olefins. This Account will detail a variety of oligomerization and polymerization results

  8. Solid-phase receptor-based assay for the detection of cyclic imines by chemiluminescence, fluorescence, or colorimetry.

    PubMed

    Rodríguez, Laura P; Vilariño, Natalia; Molgó, Jordi; Aráoz, Rómulo; Antelo, Alvaro; Vieytes, Mercedes R; Botana, Luis M

    2011-08-01

    The spirolides and gymnodimines are marine phycotoxins included in the group of cyclic imines. The toxicity of these compounds to humans is still unknown, although their toxicity by intraperitoneal injection in rodents is very high. A receptor-based method was developed using the competition of the 13-desmethyl spirolide C with biotin-labeled α-bungarotoxin for binding to nicotinic acetylcholine receptors and the immobilization of the α-bungarotoxin-receptor complex on streptavidin-coated surfaces. The quantification of the immobilized receptor can be achieved using a specific antibody. Finally, after the addition of a secondary antibody labeled with horseradish peroxidase, three alternative substrates of this enzyme generate a chemiluminescent, fluorescent, or colorimetric signal. The assay performs well in shellfish extracts and the detection range is 5-150 nM of 13-desmethyl spirolide C in shellfish extracts, which is at least 5 times more sensitive than the existing fluorescence polarization assay. This assay can also detect gymnodimine, although with 10 times lower sensitivity than the spirolide. The detection of cyclic imines with microplate assays would be useful for screening purposes in order to reduce the number of samples to be processed by bioassays or analytical methods. PMID:21692532

  9. Evidence for covalent binding of acyl glucuronides to serum albumin via an imine mechanism as revealed by tandem mass spectrometry.

    PubMed Central

    Ding, A; Ojingwa, J C; McDonagh, A F; Burlingame, A L; Benet, L Z

    1993-01-01

    Acyl glucuronide metabolites of bilirubin and many drugs can react with serum albumin in vivo to form covalent adducts. Such adducts may be responsible for some toxic effects of carboxylic nonsteroidal antiinflammatory agents. The mechanism of formation of the adducts and their chemical structures are unknown. In this paper we describe the use of tandem mass spectrometry to locate binding sites and elucidate the binding mechanism involved in the formation of covalent adducts from tolmetin glucuronide and albumin in vitro. Human serum albumin and excess tolmetin glucuronide were coincubated in the presence of sodium cyanoborohydride to trap imine intermediates. The total protein product was reduced, carboxymethylated, and digested with trypsin. Six tolmetin-containing peptides (indicated by absorbance at 313 nm) were isolated by high-pressure liquid chromatography and analyzed by liquid secondary-ion mass spectrometry and collision-induced dissociation, using a four-sector tandem mass spectrometer. All six peptides contained tolmetin linked covalently via a glucuronic acid to protein lysine groups. Major attachment sites on the protein were Lys-195, -199, and -525; minor sites were identified as Lys-137, -351, and -541. Our results show unambiguously that the glucuronic acid moiety of acyl glucuronides can be retained within the structure when these reactive metabolites bind covalently to proteins, and they suggest that acyl migration followed by Schiff base (imine) formation is a credible mechanism for the generation of covalent adducts in vivo. PMID:8483897

  10. Synthesis of Diiron(I) Dithiolato Carbonyl Complexes.

    PubMed

    Li, Yulong; Rauchfuss, Thomas B

    2016-06-22

    Virtually all organosulfur compounds react with Fe(0) carbonyls to give the title complexes. These reactions are reviewed in light of major advances over the past few decades, spurred by interest in Fe2(μ-SR)2(CO)x centers at the active sites of the [FeFe]-hydrogenase enzymes. The most useful synthetic route to Fe2(μ-SR)2(CO)6 involves the reaction of thiols with Fe2(CO)9 and Fe3(CO)12. Such reactions can proceed via mono-, di-, and triiron intermediates. The reactivity of Fe(0) carbonyls toward thiols is highly chemoselective, and the resulting dithiolato complexes are fairly rugged. Thus, many complexes tolerate further synthetic elaboration directed at the organic substituents. A second major route involves alkylation of Fe2(μ-S2)(CO)6, Fe2(μ-SH)2(CO)6, and Li2Fe2(μ-S)2(CO)6. This approach is especially useful for azadithiolates Fe2[(μ-SCH2)2NR](CO)6. Elaborate complexes arise via addition of the FeSH group to electrophilic alkenes, alkynes, and carbonyls. Although the first example of Fe2(μ-SR)2(CO)6 was prepared from ferrous reagents, ferrous compounds are infrequently used, although the Fe(II)(SR)2 + Fe(0) condensation reaction is promising. Almost invariably low-yielding, the reaction of Fe3(CO)12, S8, and a variety of unsaturated substrates results in C-H activation, affording otherwise inaccessible derivatives. Thiones and related C═S-containing reagents are highly reactive toward Fe(0), often giving complexes derived from substituted methanedithiolates and C-H activation. PMID:27258046

  11. ``PROTON Sponges": a Rigid Organic Scaffold to Reveal the Quantum Structure of the Intramolecular Proton Bond

    NASA Astrophysics Data System (ADS)

    Deblase, Andrew F.; Johnson, Mark A.; Scerba, Michael T.; Bloom, Steven; Lectka, Thomas; Dudding, Travis

    2012-06-01

    Spectroscopic analysis of systems containing charged hydrogen bonds (e.g. the Zundel ion, {H}5{O}2+) in a vibrationally cold regime is useful in decongesting numerous anharmonic features common to room temperature measurements.[Roscioli, J. R.; et. al. Science 2007] This approach has been extended to conjugate acids of the ``Proton Sponge" family of organic compounds, which contain strong intramolecular hydrogen bonds between proton donor (D) and acceptor (A) groups at the 1- and 8-positions. By performing {H}_2/{D}_2 vibrational predissociation spectroscopy on cryogenically cooled ions, we explore how the proximity and spatial orientation of D and A moieties relates to the spectroscopic signature of the shared proton. In the cases studied ({D = Me2N-H+; A = OH, O(C=O)Ph}), we observe strong anharmonic couplings between the shared proton and dark states that persist at these cryogenic temperatures. This leads to intense NH stretching features throughout the nominal CH stretching region (2800-3000 {cm}-1). Isotopic substitution has verified that the oscillator strength of these broad features is driven by NH stretching. Furthermore, the study of A = O(C=O)Ph has provided a spectroscopic snapshot of the shared proton at work as an active catalytic moiety fostering ester hydrolysis by first order acylium fission ({AAC1}). This is apparent by the high frequency carbonyl stretch at 1792 {cm}-1, which is a consequence of the strong hydrogen bond to the ether-ester oxygen atom. Thus, these ``Proton Sponges" are useful model systems that unearth the quantum structure and reactivity of shared proton interactions in organic compounds.

  12. Palladium-Catalyzed Regioselective Difluoroalkylation and Carbonylation of Alkynes.

    PubMed

    Wang, Qiang; He, Yu-Tao; Zhao, Jia-Hui; Qiu, Yi-Feng; Zheng, Lan; Hu, Jing-Yuan; Yang, Yu-Chen; Liu, Xue-Yuan; Liang, Yong-Min

    2016-06-01

    A novel, four-component synthetic strategy to synthesize a series of β-difluoroalkyl unsaturated esters/amides with high regioslectivity is described. This Pd-catalyzed difluoroalkylation and carbonylation reaction can be carried out with simple starting materials. Through this protocol, two new C-C bonds (including one C-CF2 bond) and one C-O(N) bond are constructed simultaneously in a single step. The synthetic utility of this reaction system has been certified by the applicability to a wide scope of alkynes and nucleophiles. Preliminary mechanistic studies suggest that the difluoroalkyl radical pathway is involved in this reaction. PMID:27191858

  13. Selective transformation of carbonyl ligands to organic molecules

    SciTech Connect

    Cutler, A.R.

    1992-05-12

    Studies on the carbonylation of ({eta}{sup 5}-indenyl)(L)(CO)Ru-R complexes (L = CO, PPh{sub 3}; R = CH{sub 2}OMe, CH{sub 3}) have been completed. Particularly noteworthy is that the methoxymethyl complexes readily transform to their acyl derivatives under mild conditions that leave their iron congeners inert towards CO. Surprisingly, even ({eta}{sup 5}-indenyl)(PPh{sub 3}){sub 2}Ru-CH{sub 3} carbonylates and gives ({eta}{sup 5}-indenyl)(PPh{sub 3})(CO)Ru-C(O)CH{sub 3}. Mechanistic studies on the non catalyzed'' hydrosilation of the manganese acyls (CO){sub 5}Mn-C(O)CH{sub 2}R (R = H, OCH{sub 3}, CH{sub 3}) with Et{sub 3}SiH and of cobalt acetyls (CO){sub 3}(PR{sub 3})CoC(O)CH{sub 3} with several monohydrosilanes have been completed. The cobalt acetyls cleanly give ethoxysilanes (not acetaldehyde), and the manganese acyls provide {alpha}-siloxyvinyl complexes Z-(CO){sub 5}Mn-C(OSiEt{sub 3})=CHR (R = H, CH{sub 3}, OCH{sub 3}). Carbonylation and protolytic cleavage of the latter generate pyruvoyl complexes (CO){sub 5}Mn-COCOR (R = CH{sub 3}, CH{sub 2}CH{sub 3}), formally the products of net double carbonylation'' sequences. Studies in progress are concerned with how manganese complexes as diverse as (CO){sub 5}Mn-Y (Y = C(O)R, R, BR - but not SiMe{sub 3} or Mn(CO){sub 5}) and ({eta}{sup 3}-C{sub 3}H{sub 5})Mn(CO){sub 2}L (but not CpMn(CO){sub 3} or CpMn(CO){sub 2}({eta}{sup 2}HSiR{sub 3})) function as efficient hydrosilation catalysts towards Cp(CO){sub 2}FeC(O)CH{sub 3}, for example. These reactions cleanly afford fully characterized {alpha}-siloxyethyl complexes Fp-CH(OSiR{sub 3})CH{sub 3} under conditions where typically Rh(1) hydrosilation catalysts are inactive. Several of these manganese complexes also catalytically hydrosilate organic esters, including lactones, to their ethers R-CH{sub 2}OR; these novel ester reductions occur quantitatively at room temperature and appear to be general in scope.

  14. Two-dimensional gel electrophoretic detection of protein carbonyls derivatized with biotin-hydrazide.

    PubMed

    Wu, Jinzi; Luo, Xiaoting; Jing, Siqun; Yan, Liang-Jun

    2016-04-15

    Protein carbonyls are protein oxidation products that are often used to measure the magnitude of protein oxidative damage induced by reactive oxygen or reactive nitrogen species. Protein carbonyls have been found to be elevated during aging and in age-related diseases such as stroke, diabetes, and neurodegenerative diseases. In the present article, we provide detailed protocols for detection of mitochondrial protein carbonyls labeled with biotin-hydrazide followed by 2-dimensional isoelectric focusing (IEF)/SDS-PAGE and Western blotting probed with horse-radish peroxidase-conjugated streptavidin. The presented procedures can also be modified for detection of carbonylation of non-mitochondrial proteins. PMID:26590475

  15. Borane-Catalyzed Reductive α-Silylation of Conjugated Esters and Amides Leaving Carbonyl Groups Intact.

    PubMed

    Kim, Youngchan; Chang, Sukbok

    2016-01-01

    Described herein is the development of the B(C6F5)3-catalyzed hydrosilylation of α,β-unsaturated esters and amides to afford synthetically valuable α-silyl carbonyl products. The α-silylation occurs chemoselectively, thus leaving the labile carbonyl groups intact. The reaction features a broad scope of both acyclic and cyclic substrates, and the synthetic utility of the obtained α-silyl carbonyl products is also demonstrated. Mechanistic studies revealed two operative steps: fast 1,4-hydrosilylation of conjugated carbonyls and then slow silyl group migration of a silyl ether intermediate. PMID:26549843

  16. The carbonyl oxide-aldehyde complex: a new intermediate of the ozonolysis reaction

    NASA Astrophysics Data System (ADS)

    Cremer, Dieter; Kraka, Elfi; McKee, M. L.; Radharkrishnan, T. P.

    1991-12-01

    MP4(SDQ)/6-31G (d,p) calculations suggest that the ozonolysis of alkenes in solution phase does not proceed via carbonyl oxide, but via a dipole complex between aldehyde and carbonyl oxide, which is 9 kcal/mol more stable than the separated molecules. The dipole complex is probably formed in the solvent cage upon decomposition of primary ozonide to aldehyde and carbonyl oxide. Rotation of either aldehyde or carbonyl oxide in the solvent cage leads to an antiparallel alignment of molecular dipole moments and dipole-dipole attraction.

  17. Deuterium enrichment by selective photo-induced dissociation of an organic carbonyl compound

    DOEpatents

    Marling, John B.

    1981-01-01

    A method for producing a deuterium enriched material by photoinduced dissociation which uses as the working material a gas phase photolytically dissociable organic carbonyl compound containing at least one hydrogen atom bonded to an atom which is adjacent to a carbonyl group and consisting of molecules wherein said hydrogen atom is present as deuterium and molecules wherein said hydrogen atom is present as another isotope of hydrogen. The organic carbonyl compound is subjected to intense infrared radiation at a preselected wavelength to selectively excite and thereby induce dissociation of the deuterium containing species to yield a deuterium enriched stable molecular product. Undissociated carbonyl compound, depleted in deuterium, is preferably redeuterated for reuse.

  18. Indoor and outdoor carbonyl compounds in the hotel ballrooms in Guangzhou, China

    NASA Astrophysics Data System (ADS)

    Feng, Yanli; Wen, Sheng; Wang, Xinming; Sheng, Guoying; He, Qiusheng; Tang, Jianhui; Fu, Jiamo

    Twenty-one carbonyl compounds were measured simultaneously at four hotel ballrooms in urban Guangzhou during the autumn, 2002. In each ballroom, measurements were carried out in business hours in the evening (20:30-24:00) on 7 consecutive days without any disturbance of the ballroom's normal operation. Nineteen out of the 21 target carbonyl compounds were identified in indoor and outdoor air. In the outdoor environment, formaldehyde was the most abundant carbonyl, followed by acetaldehyde, and there existed a strong correlation between formaldehyde and acetaldehyde. In the indoor air, however, acetaldehyde was the most abundant carbonyl, its concentrations seemed to be affected significantly by smoking. The indoor concentrations of carbonyls were found higher than their outdoor counterparts with only a few exceptions. Further studies concerning the indoor/outdoor ratios and mutual correlation of the carbonyls indicated that apart from direct emission from indoor materials and infiltration of outdoor air, other anthropogenic sources, e.g. tobacco smoke, also significantly contributed to carbonyl compounds. The possible sources of some high molecular weight carbonyls, e.g. nonanaldehyde, were also discussed briefly. Preliminary estimate of the exposures and risks due to carbonyls in the ballrooms was made, which indicated that long-term exposure in such places might cause increased chance of developing cancers.

  19. Fluorescence labeling of carbonylated lipids and proteins in cells using coumarin-hydrazide

    PubMed Central

    Vemula, Venukumar; Ni, Zhixu; Fedorova, Maria

    2015-01-01

    Carbonylation is a generic term which refers to reactive carbonyl groups present in biomolecules due to oxidative reactions induced by reactive oxygen species. Carbonylated proteins, lipids and nucleic acids have been intensively studied and often associated with onset or progression of oxidative stress related disorders. In order to reveal underlying carbonylation pathways and biological relevance, it is crucial to study their intracellular formation and spatial distribution. Carbonylated species are usually identified and quantified in cell lysates and body fluids after derivatization using specific chemical probes. However, spatial cellular and tissue distribution have been less often investigated. Here, we report coumarin-hydrazide, a fluorescent chemical probe for time- and cost-efficient labeling of cellular carbonyls followed by fluorescence microscopy to evaluate their intracellular formation both in time and space. The specificity of coumarin-hydrazide was confirmed in time- and dose-dependent experiments using human primary fibroblasts stressed with paraquat and compared with conventional DNPH-based immunocytochemistry. Both techniques stained carbonylated species accumulated in cytoplasm with strong perinuclear clustering. Using a complimentary array of analytical methods specificity of coumarin-hydrazide probe towards both protein- and lipid-bound carbonyls has been shown. Additionally, co-distribution of carbonylated species and oxidized phospholipids was demonstrated. PMID:25974625

  20. Analysis of dynamic protein carbonylation in rice embryo during germination through AP-SWATH.

    PubMed

    Zhang, Hui; He, Dongli; Yu, Jianlan; Li, Ming; Damaris, Rebecca Njeri; Gupta, Ravi; Kim, Sun Tae; Yang, Pingfang

    2016-03-01

    Seed germination is an important aspect of the plant life cycle, during which, reactive oxygen species (ROS) accumulate. The accumulation of ROS results in an increase in protein oxidation of which carbonylation is the most canonical one. However, there is insufficient information concerning protein oxidation, especially carbonylation and its contribution to seed germination. In this study, biotin hydrazide labeled chromatography combined with sequential window acquisition of all theoretical fragment ion spectra (SWATH) method was used to analyze the dynamic pattern of protein carbonylation in rice embryos during germination. A total of 1872 unique proteins were quantified, among which 288 carbonylated peptides corresponding to 144 proteins were determined based on the filtering through mass shifts of modified amino acids. In addition, 66 carbonylated proteins were further analyzed based on their carbonylation intensity in four stages of germination. These identified carbonylated proteins were mainly involved in maintaining the levels of ROS, abscisic acid and seed reserves. Remarkably, a peroxiredoxin was found with 23 unique carbonylated peptides, and the expression of which was consistent with its increased activity. This study describes the dynamic pattern of carbonylated proteins during seed germination, and may help to further understand the biochemical mechanisms on this process. PMID:26801057

  1. Proton radiography to improve proton therapy treatment

    NASA Astrophysics Data System (ADS)

    Takatsu, J.; van der Graaf, E. R.; Van Goethem, M.-J.; van Beuzekom, M.; Klaver, T.; Visser, J.; Brandenburg, S.; Biegun, A. K.

    2016-01-01

    The quality of cancer treatment with protons critically depends on an accurate prediction of the proton stopping powers for the tissues traversed by the protons. Today, treatment planning in proton radiotherapy is based on stopping power calculations from densities of X-ray Computed Tomography (CT) images. This causes systematic uncertainties in the calculated proton range in a patient of typically 3-4%, but can become even 10% in bone regions [1,2,3,4,5,6,7,8]. This may lead to no dose in parts of the tumor and too high dose in healthy tissues [1]. A direct measurement of proton stopping powers with high-energy protons will allow reducing these uncertainties and will improve the quality of the treatment. Several studies have shown that a sufficiently accurate radiograph can be obtained by tracking individual protons traversing a phantom (patient) [4,6,10]. Our studies benefit from the gas-filled time projection chambers based on GridPix technology [2], developed at Nikhef, capable of tracking a single proton. A BaF2 crystal measuring the residual energy of protons was used. Proton radiographs of phantom consisting of different tissue-like materials were measured with a 30×30 mm2 150 MeV proton beam. Measurements were simulated with the Geant4 toolkit.First experimental and simulated energy radiographs are in very good agreement [3]. In this paper we focus on simulation studies of the proton scattering angle as it affects the position resolution of the proton energy loss radiograph. By selecting protons with a small scattering angle, the image quality can be improved significantly.

  2. Development of a photolabile carbonyl-protecting group toolbox.

    PubMed

    Yang, Haishen; Zhang, Xin; Zhou, Lei; Wang, Pengfei

    2011-04-01

    New salicyl alcohol derived photolabile carbonyl protecting groups have been developed, and the effect of substituents on the photochemical properties of photolabile protecting groups (PPGs) has been studied. The 3-(dimethylamino)phenyl groups at the α position prove to be important to the efficiency of the deprotection reactions, as shown in the photo reactions of the acetal 9. On the other hand, expansion of the salicyl alcohol's benzene skeleton to naphthalene does not improve the photochemical properties of PPGs. A neutral protecting protocol has been generalized to new PPGs with α,α-diaryl salicyl alcohol backbone. Thus, installation of PPGs onto aldehydes is readily achieved at 140 °C without using any other chemical reagents. These PPGs are stable under acidic conditions typical for hydrolyzing acetals and constitute orthogonal protecting groups with traditional 1,3-dioxane/1,3-dioxolane for carbonyl compounds. Highly efficient release of carbohydrate molecules is demonstrated, which can be potentially useful in site-specific release and immobilization of carbohydrates for preparation of high-density microarrays. With the enriched PPG toolbox, PPGs are divided into three subgroups based on their UV absorption profiles. PPGs from different subgroups can be sequentially removed by using different UV irradiation wavelengths. For PPGs absorbing UVA (λ >315 nm), photochemical deprotection can be carried out with sunlight in high yields. PMID:21370916

  3. Reactive Carbonyl Species In Vivo: Generation and Dual Biological Effects

    PubMed Central

    Semchyshyn, Halyna M.

    2014-01-01

    Reactive carbonyls are widespread species in living organisms and mainly known for their damaging effects. The most abundant reactive carbonyl species (RCS) are derived from oxidation of carbohydrates, lipids, and amino acids. Chemical modification of proteins, nucleic acids, and aminophospholipids by RCS results in cytotoxicity and mutagenicity. In addition to their direct toxicity, modification of biomolecules by RCS gives rise to a multitude of adducts and cross links that are increasingly implicated in aging and pathology of a wide range of human diseases. Understanding of the relationship between metabolism of RCS and the development of pathological disorders and diseases may help to develop effective approaches to prevent a number of disorders and diseases. On the other hand, constant persistence of RCS in cells suggests that they perform some useful role in living organisms. The most beneficial effects of RCS are their establishment as regulators of cell signal transduction and gene expression. Since RCS can modulate different biological processes, new tools are required to decipher the precise mechanisms underlying dual effects of RCS. PMID:24634611

  4. Carbonyl reductase of dog liver: purification, properties, and kinetic mechanism.

    PubMed

    Hara, A; Nakayama, T; Deyashiki, Y; Kariya, K; Sawada, H

    1986-01-01

    A carbonyl reductase has been extracted into 0.5 M KCl from dog liver and purified to apparent homogeneity by a three-step procedure consisting of chromatography on CM-Sephadex, Matrex green A, and Sephadex G-100 in high-ionic-strength buffers. The enzyme is a dimer composed of two identical subunits of molecular weight 27,000. The pH optimum is 5.5 and the isoelectric point of the enzyme is 9.3. The enzyme reduces aromatic ketones and aldehydes; the aromatic ketones with adjacent medium alkyl chains are the best substrates. Quinones, ketosteroids, prostaglandins, and aliphatic carbonyl compounds are poor or inactive substrates for the enzyme. As a cofactor the enzyme utilizes NADPH, the pro-S hydrogen atom of which is transferred to the substrate. Two moles of NADPH bind to one mole of the enzyme molecule, causing a blue shift and enhancement of the cofactor fluorescence. The reductase reaction is reversible and the equilibrium constant determined at pH 7.0 is 12.8. Steady-state kinetic measurements in both directions suggest that the reaction proceeds through a di-iso ordered bi-bi mechanism. PMID:3511844

  5. Transition-metal-catalyzed carbonylation reactions of olefins and alkynes: a personal account.

    PubMed

    Wu, Xiao-Feng; Fang, Xianjie; Wu, Lipeng; Jackstell, Ralf; Neumann, Helfried; Beller, Matthias

    2014-04-15

    Carbon monoxide was discovered and identified in the 18th century. Since the first applications in industry 80 years ago, academic and industrial laboratories have broadly explored CO's use in chemical reactions. Today organic chemists routinely employ CO in organic chemistry to synthesize all kinds of carbonyl compounds. Despite all these achievements and a century of carbonylation catalysis, many important research questions and challenges remain. Notably, apart from academic developments, industry applies carbonylation reactions with CO on bulk scale. In fact, today the largest applications of homogeneous catalysis (regarding scale) are carbonylation reactions, especially hydroformylations. In addition, the vast majority of acetic acid is produced via carbonylation of methanol (Monsanto or Cativa process). The carbonylation of olefins/alkynes with nucleophiles, such as alcohols and amines, represent another important type of such reactions. In this Account, we discuss our work on various carbonylations of unsaturated compounds and related reactions. Rhodium-catalyzed isomerization and hydroformylation reactions of internal olefins provide straightforward access to higher value aldehydes. Catalytic hydroaminomethylations offer an ideal way to synthesize substituted amines and even heterocycles directly. More recently, our group has also developed so-called alternative metal catalysts based on iridium, ruthenium, and iron. What about the future of carbonylation reactions? CO is already one of the most versatile C1 building blocks for organic synthesis and is widely used in industry. However, because of CO's high toxicity and gaseous nature, organic chemists are often reluctant to apply carbonylations more frequently. In addition, new regulations have recently made the transportation of carbon monoxide more difficult. Hence, researchers will need to develop and more frequently use practical and benign CO-generating reagents. Apart from formates, alcohols, and metal

  6. Carbonylation reactions of alkyl iodides through the interplay of carbon radicals and Pd catalysts.

    PubMed

    Sumino, Shuhei; Fusano, Akira; Fukuyama, Takahide; Ryu, Ilhyong

    2014-05-20

    Numerous methods for transition metal catalyzed carbonylation reactions have been established. Examples that start from aryl, vinyl, allyl, and benzyl halides to give the corresponding carboxylic acid derivatives have all been well documented. In contrast, the corresponding alkyl halides often encounter difficulty. This is inherent to the relatively slow oxidative addition step onto the metal center and subsequent β-hydride elimination which causes isomerization of the alkyl metal species. Radical carbonylation reactions can override such problems of reactivity; however, carbonylation coupled to iodine atom transfer (atom transfer carbonylation), though useful, often suffers from a slow iodine atom transfer step that affects the outcome of the reaction. We found that atom transfer carbonylation of primary, secondary, and tertiary alkyl iodides was efficiently accelerated by the addition of a palladium catalyst under light irradiation. Stereochemical studies support a mechanistic pathway based on the synergic interplay of radical and Pd-catalyzed reaction steps which ultimately lead to an acylpalladium species. The radical/Pd-combined reaction system has a wide range of applications, including the synthesis of carboxylic acid esters, lactones, amides, lactams, and unsymmetrical ketones such as alkyl alkynyl and alkyl aryl ketones. The design of unique multicomponent carbonylation reactions involving vicinal C-functionalization of alkenes, double and triple carbonylation reactions, in tandem with radical cyclization reactions, has also been achieved. Thus, the radical/Pd-combined strategy provides a solution to a longstanding problem of reactivity involving the carbonylation of alkyl halides. This novel methodology expands the breadth and utility of carbonylation chemistry over either the original radical carbonylation reactions or metal-catalyzed carbonylation reactions. PMID:24712759

  7. A step-by-step protocol for assaying protein carbonylation in biological samples.

    PubMed

    Colombo, Graziano; Clerici, Marco; Garavaglia, Maria Elisa; Giustarini, Daniela; Rossi, Ranieri; Milzani, Aldo; Dalle-Donne, Isabella

    2016-04-15

    Protein carbonylation represents the most frequent and usually irreversible oxidative modification affecting proteins. This modification is chemically stable and this feature is particularly important for storage and detection of carbonylated proteins. Many biochemical and analytical methods have been developed during the last thirty years to assay protein carbonylation. The most successful method consists on protein carbonyl (PCO) derivatization with 2,4-dinitrophenylhydrazine (DNPH) and consequent spectrophotometric assay. This assay allows a global quantification of PCO content due to the ability of DNPH to react with carbonyl giving rise to an adduct able to absorb at 366 nm. Similar approaches were also developed employing chromatographic separation, in particular HPLC, and parallel detection of absorbing adducts. Subsequently, immunological techniques, such as Western immunoblot or ELISA, have been developed leading to an increase of sensitivity in protein carbonylation detection. Currently, they are widely employed to evaluate change in total protein carbonylation and eventually to highlight the specific proteins undergoing selective oxidation. In the last decade, many mass spectrometry (MS) approaches have been developed for the identification of the carbonylated proteins and the relative amino acid residues modified to carbonyl derivatives. Although these MS methods are much more focused and detailed due to their ability to identify the amino acid residues undergoing carbonylation, they still require too expensive equipments and, therefore, are limited in distribution. In this protocol paper, we summarise and comment on the most diffuse protocols that a standard laboratory can employ to assess protein carbonylation; in particular, we describe step-by-step the different protocols, adding suggestions coming from our on-bench experience. PMID:26706659

  8. Double-addition reaction of aryl methyl sulfones with N-tert-butylsulfinyl imines: diastereoselective and concise synthesis of 2-sulfonylated 1,3-diamines.

    PubMed

    Li, Ya; Li, Desheng; Zheng, Tao; Li, Hongsen; Ren, Xinfeng

    2014-11-10

    We report a double-addition reaction of methyl phenyl sulfone and methyl 2-pyridyl sulfone with N-tert-butylsulfinyl imines. This method provides concise access to 2-sulfonylated 1,3-anti diamines with good to excellent diastereoselectivities. This protocol has the benefit of using readily accessible starting materials and is operationally simple. PMID:25288374

  9. Cyclopent-2-enylaluminium as allylzinc precursor for the diastereoselective allylmetallation of non-racemic imines: applications to the synthesis of enantiomerically enriched heterocycles.

    PubMed

    Coffinet, Michaël; Lamy, Samantha; Jaroschik, Florian; Vasse, Jean-Luc

    2016-01-01

    The generation of cyclopent-2-enylzinc from cyclopentadiene based on a titanium-catalyzed hydroalumination/transmetallation sequence is described. Applied to the allylmetallation of phenylglycinol-derived imines, this sequence leads to homoallylic amines with moderate to good stereoselectivities. The synthesis of disubstituted azetidines and piperidines illustrates the potential of the method. PMID:26563731

  10. On-surface synthesis of two-dimensional imine polymers with a tunable band gap: a combined STM, DFT and Monte Carlo investigation.

    PubMed

    Xu, Lirong; Yu, Yanxia; Lin, Jianbin; Zhou, Xin; Tian, Wei Quan; Nieckarz, Damian; Szabelski, Pawel; Lei, Shengbin

    2016-04-28

    Two-dimensional polymers are of great interest for many potential applications in nanotechnology. The preparation of crystalline 2D polymers with a tunable band gap is critical for their applications in nano-electronics and optoelectronics. In this work, we try to tune the band gap of 2D imine polymers by expanding the conjugation of the backbone of aromatic diamines both laterally and longitudinally. STM characterization reveals that the regularity of the 2D polymers can be affected by the existence of lateral bulky groups. Density functional theory (DFT) simulations discovered a significant narrowing of the band gap of imine 2D polymers upon the expansion of the conjugation of the monomer backbone, which has been confirmed experimentally by UV absorption measurements. Monte Carlo simulations help us to gain further insight into the controlling factors of the formation of regular 2D polymers, which demonstrated that based on the all rigid assumption, the coexistence of different conformations of the imine moiety has a significant effect on the regularity of the imine 2D polymers. PMID:27049517

  11. Photocatalytic organic transformation by layered double hydroxides: highly efficient and selective oxidation of primary aromatic amines to their imines under ambient aerobic conditions.

    PubMed

    Yang, Xiu-Jie; Chen, Bin; Li, Xu-Bing; Zheng, Li-Qiang; Wu, Li-Zhu; Tung, Chen-Ho

    2014-06-25

    We report the first application of layered double hydroxide as a photocatalyst in the transformation of primary aromatic amines to their corresponding imines with high efficiency and selectivity by using oxygen in an air atmosphere as a terminal oxidant under light irradiation. PMID:24827163

  12. Diastereoselective 1,3-Dipolar Cycloadditions of N,N'-Cyclic Azomethine Imines with Iminooxindoles for Access to Oxindole Spiro-N,N-bicyclic Heterocycles.

    PubMed

    Zhao, Hong-Wu; Li, Bo; Pang, Hai-Liang; Tian, Ting; Chen, Xiao-Qin; Song, Xiu-Qing; Meng, Wei; Yang, Zhao; Zhao, Yu-Di; Liu, Yue-Yang

    2016-02-19

    In the presence of CuI, 1,3-dipolar cycloadditions of N,N'-cyclic azomethine imines with iminooxindoles proceeded readily and furnished novel oxindole spiro-N,N-bicyclic heterocycles in moderate to excellent chemical yields with excellent diastereoselectivities. PMID:26853121

  13. Catalytic oxidation of imines based on methyltrioxorhenium/urea hydrogen peroxide: a mild and easy chemo- and regioselective entry to nitrones.

    PubMed

    Soldaini, Gianluca; Cardona, Francesca; Goti, Andrea

    2007-02-01

    [reaction: see text] The first successful catalytic oxidation procedure for the chemoselective conversion of imines to nitrones is reported. The reaction is general, high yielding, and user and environmentally friendly, and furnishes a solution to the yet unanswered issue of regioselective access to nitrones by oxidation of nitrogen derivatives. PMID:17249790

  14. Access to spirocyclic oxindoles via N-heterocyclic carbene-catalyzed reactions of enals and oxindole-derived α,β-unsaturated imines.

    PubMed

    Jiang, Kun; Tiwari, Bhoopendra; Chi, Yonggui Robin

    2012-05-01

    A diastereoselective access to β-lactam fused spirocyclic oxindoles and related compounds bearing all carbon spiro centers is described. This N-heterocyclic carbene-catalyzed process employed challenging β,β-disubstituted α,β-unsaturated imines to react with enals. PMID:22524534

  15. Proton decay theory

    SciTech Connect

    Marciano, W.J.

    1983-01-01

    Topics include minimal SU(5) predictions, gauge boson mediated proton decay, uncertainties in tau/sub p/, Higgs scalar effects, proton decay via Higgs scalars, supersymmetric SU(5), dimension 5 operators and proton decay, and Higgs scalars and proton decay. (WHK)

  16. Synchrotron based proton drivers

    SciTech Connect

    Weiren Chou

    2002-09-19

    Proton drivers are the proton sources that produce intense short proton bunches. They have a wide range of applications. This paper discusses the proton drivers based on high-intensity proton synchrotrons. It gives a review of the high-intensity proton sources over the world and a brief report on recent developments in this field in the U.S. high-energy physics (HEP) community. The Fermilab Proton Driver is used as a case study for a number of challenging technical design issues.

  17. Highly active, low-valence molybdenum- and tungsten-amide catalysts for bifunctional imine-hydrogenation reactions.

    PubMed

    Chakraborty, Subrata; Blacque, Olivier; Fox, Thomas; Berke, Heinz

    2014-01-01

    The reactions of [M(NO)(CO)4(ClAlCl3)] (M=Mo, W) with (iPr2PCH2CH2)2NH, (PN(H)P) at 90 °C afforded [M(NO)(CO)(PN(H)P)Cl] complexes (M=Mo, 1a; W, 1b). The treatment of compound 1a with KOtBu as a base at room temperature yielded the alkoxide complex [Mo(NO)(CO)(PN(H)P)(OtBu)] (2a). In contrast, with the amide base Na[N(SiMe3 )2 ], the PN(H) P ligand moieties in compounds 1a and 1b could be deprotonated at room temperature, thereby inducing dehydrochlorination into amido complexes [M(NO)(CO)(PNP)] (M=Mo, 3a; W, 3b; PNP=(iPr2PCH2CH2)2N)). Compounds 3a and 3b have pseudo-trigonal-bipyramidal geometries, in which the amido nitrogen atom is in the equatorial plane. At room temperature, compounds 3a and 3b were capable of adding dihydrogen, with heterolytic splitting, thereby forming pairs of isomeric amine-hydride complexes [Mo(NO)(CO)H(PN(H)P)] (4a(cis) and 4a(trans)) and [W(NO)(CO)H(PN(H)P)] (4b(cis) and 4b(trans); cis and trans correspond to the position of the H and NO groups). H2 approaches the Mo/W=N bond in compounds 3a,b from either the CO-ligand side or from the NO-ligand side. Compounds 4a(cis) and 4a(trans) were only found to be stable under a H2 atmosphere and could not be isolated. At 140 °C and 60 bar H2 , compounds 3a and 3b catalyzed the hydrogenation of imines, thereby showing maximum turnover frequencies (TOFs) of 2912 and 1120 h(-1), respectively, for the hydrogenation of N-(4-methoxybenzylidene)aniline. A Hammett plot for various para-substituted imines revealed linear correlations with a negative slope of -3.69 for para substitution on the benzylidene side and a positive slope of 0.68 for para substitution on the aniline side. Kinetics analysis revealed the initial rate of the hydrogenation reactions to be first order in c(cat.) and zeroth order in c(imine). Deuterium kinetic isotope effect (DKIE) experiments furnished a low kH /kD value (1.28), which supported a Noyori-type metal-ligand bifunctional mechanism with H2 addition as the rate

  18. Infrared multiple photon dissociation spectroscopy of ciprofloxacin: Investigation of the protonation site

    NASA Astrophysics Data System (ADS)

    Bodo, E.; Ciavardini, A.; Giardini, A.; Paladini, A.; Piccirillo, S.; Rondino, F.; Scuderi, D.

    2012-04-01

    The vibrational spectrum of isolated protonated ciprofloxacin was recorded in the range 1100-2000 cm-1 by means of infrared multiple photon dissociation (IRMPD) spectroscopy. The spectrum was obtained by electrospraying a methanol solution of ciprofloxacin in a Paul ion trap, coupled to the tunable IR radiation of a free electron laser. This spectroscopic study has been complemented by quantum chemical calculations at the DFT and MP2 levels of theory to identify the possible structures present under our experimental conditions. Several low-energy isomers with protonation occurring at the piperazinyl amino group and at the carbonyl group are predicted in the energy range 0-84 kJ mol-1. A good agreement between the measured IRMPD spectrum and the calculated absorption spectrum is observed for the isomer protonated at the piperazinyl amino group. This isomer is calculated at MP2 level of theory to lie about 76 kJ/mol above the most stable isomer which is protonated at the quinone carbonyl group. This discrepancy can be rationalized by assuming that the protonation at the piperazinyl amino group, typical of the zwitterionic form that is found in protic solvents, is retained in the ESI process. The vibrational bands observed in the IRMPD spectrum are assigned to normal modes of the isomer protonated at the piperazinyl amino group, with deviations of less than 20 cm-1 between measured and calculated frequencies.

  19. Proton Therapy - Accelerating Protons to Save Lives

    SciTech Connect

    Keppel, Cynthia

    2011-10-25

    In 1946, physicist Robert Wilson first suggested that protons could be used as a form of radiation therapy in the treatment of cancer because of the sharp drop-off that occurs on the distal edge of the radiation dose. Research soon confirmed that high-energy protons were particularly suitable for treating tumors near critical structures, such as the heart and spinal column. The precision with which protons can be delivered means that more radiation can be deposited into the tumor while the surrounding healthy tissue receives substantially less or, in some cases, no radiation. Since these times, particle accelerators have continuously been used in cancer therapy and today new facilities specifically designed for proton therapy are being built in many countries. Proton therapy has been hailed as a revolutionary cancer treatment, with higher cure rates and fewer side effects than traditional X-ray photon radiation therapy. Proton therapy is the modality of choice for treating certain small tumors of the eye, head or neck. Because it exposes less of the tissue surrounding a tumor to the dosage, proton therapy lowers the risk of secondary cancers later in life - especially important for young children. To date, over 80,000 patients worldwide have been treated with protons. Currently, there are nine proton radiation therapy facilities operating in the United States, one at the Hampton University Proton Therapy Institute. An overview of the treatment technology and this new center will be presented.

  20. Ketene as a Reaction Intermediate in the Carbonylation of Dimethyl Ether to Methyl Acetate over Mordenite.

    PubMed

    Rasmussen, Dominik B; Christensen, Jakob M; Temel, Burcin; Studt, Felix; Moses, Poul Georg; Rossmeisl, Jan; Riisager, Anders; Jensen, Anker D

    2015-06-15

    Unprecedented insight into the carbonylation of dimethyl ether over Mordenite is provided through the identification of ketene (CH2CO) as a reaction intermediate. The formation of ketene is predicted by detailed DFT calculations and verified experimentally by the observation of doubly deuterated acetic acid (CH2DCOOD), when D2O is introduced in the feed during the carbonylation reaction. PMID:25967363

  1. 40 CFR 721.10705 - Aromatic amine with cyclo amino carbonyls (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Aromatic amine with cyclo amino... Specific Chemical Substances § 721.10705 Aromatic amine with cyclo amino carbonyls (generic). (a) Chemical... as aromatic amine with cyclo amino carbonyls (PMN P-12-572) is subject to reporting under...

  2. In Situ Derivatization and Quantification of Seven Carbonyls in Cigarette Mainstream Smoke.

    PubMed

    Ding, Yan S; Yan, Xizheng; Wong, Joshua; Chan, Michele; Watson, Clifford H

    2016-01-19

    Carbonyls, especially aldehydes, are a group of harmful volatile organic compounds that are found in tobacco smoke. Seven carbonyls are listed on the FDA's harmful and potential harmful constituents list for tobacco or tobacco smoke. Carbonyls have reactive functional groups and thus are challenging to quantitatively measure in cigarette smoke. The traditional method of measuring carbonyls in smoke involves solvent-filled impinger trapping and derivatization. This procedure is labor-intensive and generates significant volumes of hazardous waste. We have developed a new method to efficiently derivatize and trap carbonyls from mainstream smoke in situ on Cambridge filter pads. The derivatized carbonyls are extracted from the pads and subsequently quantified by ultra-high-pressure liquid chromatography coupled with tandem mass spectrometry. The new method has been validated and applied to research and commercial cigarettes. Carbonyl yields from research cigarettes are comparable to those from other published literature data. With a convenient smoke collection apparatus, a 4 min sample analysis time, and a low- or submicrogram detection limit, this new method not only simplifies and speeds the detection of an important class of chemical constituents in mainstream smoke but also reduces reactive losses and provides a more accurate assessment of carbonyl levels in smoke. Excellent accuracy (average 98%) and precision (14% average relative standard deviation in research cigarettes) ensure this new method's sufficient fidelity to characterize conventional combusted tobacco products, with potential application toward new or emerging products. PMID:26700249

  3. Protein carbonylation during natural leaf senescence in winter wheat, as probed by fluorescein-5-thiosemicarbazide.

    PubMed

    Havé, M; Leitao, L; Bagard, M; Castell, J-F; Repellin, A

    2015-09-01

    Leaf senescence is characterised by a massive degradation of proteins in order to recycle nitrogen to other parts of the plant, such as younger leaves or developing grain/seed. Protein degradation during leaf senescence is a highly regulated process and it is suggested that proteins to be degraded are marked by an oxidative modification (carbonylation) that makes them more susceptible to proteolysis. However, there is as yet no evidence of an increase in protein carbonylation level during natural leaf senescence. The aim of our study was thus to monitor protein carbonylation level during the process of natural senescence in the flag leaf of field-grown winter wheat plants. For this purpose, we adapted a fluorescence-based method using fluorescein-5-thiosemicarbazide (FTC) as a probe for detecting protein carbonyl derivatives. As used for the first time on plant material, this method allowed the detection of both quantitative and qualitative modifications in protein carbonyl levels during the last stages of wheat flag leaf development. The method described herein represents a convenient, sensitive and reproducible alternative to the commonly used 2,4-dinitrophenylhydrazine (DNPH)-based method. In addition, our analysis revealed changes in protein carbonylation level during leaf development that were associated with qualitative changes in protein abundance and carbonylation profiles. In the senescing flag leaf, protein carbonylation increased concomitantly with a stimulation of endoproteolytic activity and a decrease in protein content, which supports the suggested relationship between protein oxidation and proteolysis during natural leaf senescence. PMID:25683278

  4. Metal-atom fluorescence from the quenching of metastable rare gases by metal carbonyls

    SciTech Connect

    Hollingsworth, W.E.

    1982-11-01

    A flowing afterglow apparatus was used to study the metal fluorescence resulting from the quenching of metastable rare-gas states by metal carbonyls. The data from the quenching or argon, neon, and helium by iron and nickel carbonyl agreed well with a restricted degree of freedom model indicating a concerted bond-breaking dissociation.

  5. AminoxyTMT: A novel multi-functional reagent for characterization of protein carbonylation.

    PubMed

    Afiuni-Zadeh, Somaieh; Rogers, John C; Snovida, Sergei I; Bomgarden, Ryan D; Griffin, Timothy J

    2016-01-01

    Protein carbonylation is a common oxidative stress (OS)-driven post-translational modification (PTM). Proteome-wide carbonylation events can best be characterized using a combination of analytical approaches. Immunoblotting of carbonylated proteins provides data on the extent of modifications within complex samples, as well as a broad comparison of carbonylation profiles between different biological states (e.g., disease versus control), while mass spectrometry (MS)-based analysis provides information on proteins susceptible to carbonylation, as well as the potential for quantitative characterization of specific sites of amino acid modification. Here, we present a novel use for aminoxyTMT, a derivative of the Tandem Mass Tag (TMT) isobaric labeling reagent, which utilizes an aminooxy functional group for covalent labeling of reactive carbonyls in proteins. When coupled with anti-TMT antibody, we demonstrate the use of aminoxyTMT for immunoblot profiling of protein carbonylation in complex mixtures, as well as enrichment of modified peptides from these mixtures. Proof-of-principle experiments also show the amenability of aminoxyTMT-labeled carbonylated peptides enriched from complex mixtures to identification using tandem MS (MS/MS) and database searching, as well as quantitative analysis using TMT-based reporter ion intensity measurements. PMID:27071607

  6. PROCESS OF COATING WITH NICKEL BY THE DECOMPOSITION OF NICKEL CARBONYL

    DOEpatents

    Hoover, T.B.

    1959-04-01

    An improved process is presented for the deposition of nickel coatings by the thermal decomposition of nickel carbonyl vapor. The improvement consists in incorporating a small amount of hydrogen sulfide gas in the nickel carbonyl plating gas. It is postulated that the hydrogen sulfide functions as a catalyst. i

  7. Protective mechanisms of Cucumis sativus in diabetes-related modelsof oxidative stress and carbonyl stress

    PubMed Central

    Heidari, Himan; Kamalinejad, Mohammad; Noubarani, Maryam; Rahmati, Mokhtar; Jafarian, Iman; Adiban, Hasan; Eskandari, Mohammad Reza

    2016-01-01

    Introduction: Oxidative stress and carbonyl stress have essential mediatory roles in the development of diabetes and its related complications through increasing free radicals production and impairing antioxidant defense systems. Different chemical and natural compounds have been suggested for decreasing such disorders associated with diabetes. The objectives of the present study were to investigate the protective effects of Cucumis sativus (C. sativus) fruit (cucumber) in oxidative and carbonyl stress models. These diabetes-related models with overproduction of reactive oxygen species (ROS) and reactive carbonyl species (RCS) simulate conditions observed in chronic hyperglycemia. Methods: Cytotoxicity induced by cumene hydroperoxide (oxidative stress model) or glyoxal (carbonyl stress model) were measured and the protective effects of C. sativus were evaluated using freshly isolated rat hepatocytes. Results: Aqueous extract of C. sativus fruit (40 μg/mL) prevented all cytotoxicity markers in both the oxidative and carbonyl stress models including cell lysis, ROS formation, membrane lipid peroxidation, depletion of glutathione, mitochondrial membrane potential decline, lysosomal labialization, and proteolysis. The extract also protected hepatocytes from protein carbonylation induced by glyoxal. Our results indicated that C. sativus is able to prevent oxidative stress and carbonyl stress in the isolated hepatocytes. Conclusion: It can be concluded that C. sativus has protective effects in diabetes complications and can be considered a safe and suitable candidate for decreasing the oxidative stress and carbonyl stress that is typically observed in diabetes mellitus. PMID:27340622

  8. Versatile, mild, and selective reduction of various carbonyl groups using an electron-deficient boron catalyst.

    PubMed

    Lucas, Katherine M; Kleman, Adam F; Sadergaski, Luke R; Jolly, Caitlyn L; Bollinger, Brady S; Mackesey, Brittany L; McGrath, Nicholas A

    2016-06-15

    A mild and selective new method was discovered to reduce acetanilides and other carbonyl compounds. Unlike sodium borohydride, which is selective in reducing aldehydes and ketones, this new protocol is uniquely selective in reducing acetanilides and nitriles over other carbonyl containing functional groups. Additionally, β-ketoamides were shown to be reduced at the ketone preferentially over the amide. PMID:27005847

  9. The Protonation Site of para-Dimethylaminobenzoic Acid Using Atmospheric Pressure Ionization Methods

    NASA Astrophysics Data System (ADS)

    Chai, Yunfeng; Weng, Guofeng; Shen, Shanshan; Sun, Cuirong; Pan, Yuanjiang

    2015-04-01

    The protonation site of para-dimethylaminobenzoic acid ( p-DMABA) was investigated using atmospheric pressure ionization methods (ESI and APCI) coupled with collision-induced dissociation (CID), nuclear magnetic resonance (NMR), and computational chemistry. Theoretical calculations and NMR experiments indicate that the dimethyl amino group is the preferred site of protonation both in the gas phase and aqueous solution. Protonation of p-DMABA occurs at the nitrogen atom by ESI independent of the solvents and other operation conditions under typical thermodynamic control. However, APCI produces a mixture of the nitrogen- and carbonyl oxygen-protonated p-DMABA when aprotic organic solvents (acetonitrile, acetone, and tetrahydrofuran) are used, exhibiting evident kinetic characteristics of protonation. But using protic organic solvents (methanol, ethanol, and isopropanol) in APCI still leads to the formation of thermodynamically stable N-protonated p-DMABA. These structural assignments were based on the different CID behavior of the N- and O-protonated p-DMABA. The losses of methyl radical and water are the diagnostic fragmentations of the N- and O-protonated p-DMABA, respectively. In addition, the N-protonated p-DMABA is more stable than the O-protonated p-DMABA in CID revealed by energy resolved experiments and theoretical calculations.

  10. Characterization of modified proteins in plasma from a subtype of schizophrenia based on carbonyl stress: Protein carbonyl is a possible biomarker of psychiatric disorders.

    PubMed

    Koike, Shin; Kayama, Tasuku; Arai, Makoto; Horiuchi, Yasue; Kobori, Akiko; Miyashita, Mitsuhiro; Itokawa, Masanari; Ogasawara, Yuki

    2015-11-13

    Although it's well known that protein carbonyl (PCO) and advanced glycation end-products (AGEs) levels are elevated in plasma from patients with renal dysfunction, we recently identified patients who had no renal dysfunction but possessed high levels of plasma pentosidine (PEN), which is an AGEs, and low vitamin B6 levels in serum. In this study, we investigated the status of carbonyl stress to characterize the subtype of schizophrenia. When plasma samples were subjected to Western blot analysis for various AGEs, clear differences were only observed with the anti-PEN antibody in the plasma from schizophrenic patients. Moreover, we determined the formation of protein carbonyl (PCO), a typical indicator of carbonyl stress, occurred prior to the accumulation of PEN in the plasma of schizophrenic patients. PCO levels in the plasma from schizophrenic patients were significantly higher than that from healthy subjects. Western blots analysis clearly showed that albumin and IgG were markedly carbonylated in the plasma of some patients. Thus, PCOs may be a novel marker of carbonyl stress-type schizophrenia in addition to albumin containing PEN structure. PMID:26431870

  11. Protein carbonylation after traumatic brain injury: cell specificity, regional susceptibility, and gender differences.

    PubMed

    Lazarus, Rachel C; Buonora, John E; Jacobowitz, David M; Mueller, Gregory P

    2015-01-01

    Protein carbonylation is a well-documented and quantifiable consequence of oxidative stress in several neuropathologies, including multiple sclerosis, Alzheimer׳s disease, and Parkinson׳s disease. Although oxidative stress is a hallmark of traumatic brain injury (TBI), little work has explored the specific neural regions and cell types in which protein carbonylation occurs. Furthermore, the effect of gender on protein carbonylation after TBI has not been studied. The present investigation was designed to determine the regional and cell specificity of TBI-induced protein carbonylation and how this response to injury is affected by gender. Immunohistochemistry was used to visualize protein carbonylation in the brains of adult male and female Sprague-Dawley rats subjected to controlled cortical impact (CCI) as an injury model of TBI. Cell-specific markers were used to colocalize the presence of carbonylated proteins in specific cell types, including astrocytes, neurons, microglia, and oligodendrocytes. Results also indicated that the injury lesion site, ventral portion of the dorsal third ventricle, and ventricular lining above the median eminence showed dramatic increases in protein carbonylation after injury. Specifically, astrocytes and limited regions of ependymal cells adjacent to the dorsal third ventricle and the median eminence were most susceptible to postinjury protein carbonylation. However, these patterns of differential susceptibility to protein carbonylation were gender dependent, with males showing significantly greater protein carbonylation at sites distant from the lesion. Proteomic analyses were also conducted and determined that the proteins most affected by carbonylation in response to TBI include glial fibrillary acidic protein, dihydropyrimidase-related protein 2, fructose-bisphosphate aldolase C, and fructose-bisphosphate aldolase A. Many other proteins, however, were not carbonylated by CCI. These findings indicate that there is both regional

  12. Impact of HVAC filter on indoor air quality in terms of ozone removal and carbonyls generation

    NASA Astrophysics Data System (ADS)

    Lin, Chi-Chi; Chen, Hsuan-Yu

    2014-06-01

    This study aims at detecting ozone removal rates and corresponding carbonyls generated by ozone reaction with HVAC filters from various building, i.e., shopping mall, school, and office building. Studies were conducted in a small-scale environmental chamber. By examining dust properties including organic carbon proportion and specific surface area of dusts adsorbed on filters along with ozone removal rates and carbonyls generation rate, the relationship among dust properties, ozone removal rates, and carbonyls generation was identified. The results indicate a well-defined positive correlation between ozone removal efficiency and carbonyls generation on filters, as well as a positive correlation among the mass of organic carbon on filters, ozone removal efficiency and carbonyls generations.

  13. Metal-Free, Multicomponent Synthesis of Pyrrole-Based π-Conjugated Polymers from Imines, Acid Chlorides, and Alkynes.

    PubMed

    Kayser, Laure V; Vollmer, Moritz; Welnhofer, Merve; Krikcziokat, Hanna; Meerholz, Klaus; Arndtsen, Bruce A

    2016-08-24

    Multicomponent coupling reactions (MCRs) are becoming increasingly used in the synthesis of macromolecules, as they can allow the rapid generation of libraries of materials as a method to tune properties. MCRs could prove particularly useful in the synthesis of π-conjugated polymers in which structural changes are necessary for fine-tuning of electronic properties. We describe here the first metal-free multicomponent approach to conjugated polymers. This reaction exploits the coupling of imines, acid chlorides, and (catechyl)PPh to generate phospha-münchnone-containing polymers, which can be converted to poly(pyrroles) via cycloaddition. The platform allows for the efficient synthesis of families of high molecular weight polymers in one step from readily available monomers. PMID:27471822

  14. Design of Redox/Radical Sensing Molecules via Nitrile Imine-Mediated Tetrazole-ene Cycloaddition (NITEC).

    PubMed

    Lederhose, Paul; Haworth, Naomi L; Thomas, Komba; Bottle, Steven E; Coote, Michelle L; Barner-Kowollik, Christopher; Blinco, James P

    2015-08-21

    The current study introduces a novel synthetic avenue for the preparation of profluorescent nitroxides via nitrile imine-mediated tetrazole-ene cycloaddition (NITEC). The photoinduced cycloaddition was performed under metal-free, mild conditions allowing the preparation of a library of the nitroxide functionalized pyrazolines and corresponding methoxyamines. High reaction rates and full conversion were observed, with the presence of the nitroxide having no significant impact on the cycloaddition performance. The formed products were investigated with respect to their photophysical properties in order to quantify their "switch on/off" behavior. The fluorescence quenching performance is strongly dependent on the distance between the chromophore and the free radical spin as demonstrated theoretically and experimentally. Highest levels of fluorescence quenching were achieved for pyrazolines with the nitroxide directly fused to the chromophore. Importantly, the pyrazoline profluorescent nitroxides were shown to efficiently act as sensors for redox/radical processes. PMID:26168007

  15. Asymmetric aza-Morita-Baylis-Hillman reactions of chiral N-phosphonyl imines with acrylates via GAP chemistry/technology.

    PubMed

    Yang, Bing; Ji, Xiaozhou; Xue, Yunsheng; Zhang, Haowei; Shen, Minxing; Jiang, Bo; Li, Guigen

    2016-07-01

    Chiral N-phosphonyl imines have been proven to be efficient electrophilic acceptors for asymmetric aza-Morita-Baylis-Hillman (aza-MBH) reactions with acrylates under convenient conditions. Thirty examples of β-amino acrylates were generated in high yields (up to 99.4%) and diastereoselectivity (up to >99 : 1 dr) in an atom-economical fashion. The synthesis was proved to follow the GAP (group-assisted purification) chemistry, i.e., the pure products can be obtained simply by washing the crude products with hexane/ethyl acetate (v/v, 10/1) without the use of chromatography or recrystallization. DFT calculations were also conducted to support an asymmetric induction model accounting for high diastereoselectivity. PMID:27232108

  16. Multifunctional imine-POSS as uncommon 3D nanobuilding blocks for supramolecular hybrid materials: synthesis, structural characterization, and properties.

    PubMed

    Janeta, Mateusz; John, Łukasz; Ejfler, Jolanta; Lis, Tadeusz; Szafert, Sławomir

    2016-08-01

    In this article, we report on the chemistry and the spectroscopic properties of well-defined imino-functionalized polyoctahedral oligomeric silsesquioxanes (imine-POSS) with various substitutions. Our efforts were mainly focused on side chains with sizable aryl groups possessing hydroxyl, nitro, and halide moieties. Such a choice enabled us to track their reduction abilities to secondary amine-POSS, tautomerization effects, and thermal properties. We also report for the first time the solid-state structures of five imino-functionalized cage-like octasilsesquioxanes. These structures provide unique examples of the complexities of three-dimensional packing motifs and their relationship with the assembly of tunable materials from nanobuilding blocks. PMID:27438046

  17. Metal-ligand cooperation on a diruthenium platform: selective imine formation through acceptorless dehydrogenative coupling of alcohols with amines.

    PubMed

    Saha, Biswajit; Rahaman, S M Wahidur; Daw, Prosenjit; Sengupta, Gargi; Bera, Jitendra K

    2014-05-19

    Metal-metal singly-bonded diruthenium complexes, bridged by naphthyridine-functionalized N-heterocyclic carbene (NHC) ligands featuring a hydroxy appendage on the naphthyridine unit, are obtained in a single-pot reaction of [Ru2(CH3COO)2(CO)4] with 1-benzyl-3-(5,7-dimethyl-1,8-naphthyrid-2-yl)imidazolium bromide (BIN⋅HBr) or 1-isopropyl-3-(5,7-dimethyl-1,8-naphthyrid-2-yl)imidazolium bromide (PIN⋅HBr), TlBF4, and substituted benzaldehyde containing an electron-withdrawing group. The modified NHC-naphthyridine-hydroxy ligand spans the diruthenium unit in which the NHC carbon and hydroxy oxygen occupy the axial sites. All the synthesized compounds catalyze acceptorless dehydrogenation of alcohols to the corresponding aldehydes in the presence of a catalytic amount of weak base 1,4-diazabicyclo[2.2.2]octane (DABCO). Further, acceptorless dehydrogenative coupling (ADHC) of the alcohol with amines affords the corresponding imine as the sole product. The substrate scope is examined with 1 (BIN, p-nitrobenzaldehyde). A similar complex [Ru2(CO)4(CH3COO)(3-PhBIN)][Br], that is devoid of a hydroxy arm, is significantly less effective for the same reaction. Neutral complex 1 a, obtained by deprotonation of the hydroxy arm in 1, is found to be active for the ADHC of alcohols and amines under base-free conditions. A combination of control experiments, deuterium labeling, kinetic Hammett studies, and DFT calculations support metal-hydroxyl/hydroxide and metal-metal cooperation for alcohol activation and dehydrogenation. The bridging acetate plays a crucial role in allowing β-hydride elimination to occur. The ligand architecture on the diruthenium core causes rapid aldehyde extrusion from the metal coordination sphere, which is responsible for exclusive imine formation. PMID:24715433

  18. Zirconocene-Mediated Carbonylative Coupling of Grignard Reagents.

    PubMed

    Moss, Melissa; Han, Xinping; Ready, Joseph M

    2016-08-16

    Organozirconocenes are versatile synthetic intermediates that can undergo carbonylation to yield acyl anion equivalents. Zirconocene hydrochloride ([Cp2 ZrHCl]) is often the reagent of choice for accessing these intermediates but generates organozirconocenes only from alkenes and alkynes. This requirement eliminates a broad range of substrates. For example, organozirconocenes in which the zirconium center is bonded to an aromatic ring, a benzylic group, or an alkyl group that possesses a tertiary or quaternary carbon atom α to the carbon-zirconium bond can not be formed in this way. To provide more generalized access to acyl zirconium reagents, we explored the transmetalation of Grignard reagents with zirconocene dichloride under a CO atmosphere. This protocol generates acyl zirconium(IV) complexes that are inaccessible with the Schwartz reagent, including those derived from secondary and tertiary alkyl and aryl Grignard reagents. PMID:27410720

  19. Photosynthetic Control of Atmospheric Carbonyl Sulfide during the Growing Season

    NASA Technical Reports Server (NTRS)

    Campbell, J. Elliott; Carmichael, Gregory R.; Chai, T.; Mena-Carrasco, M.; Tang, Y.; Blake, D. R.; Blake, N. J.; Vay, Stephanie A.; Collatz, G. James; Baker, I.; Berry, J. A.; Montzka, S. A.; Sweeney, C.; Schnoor, J. L.; Stanier, Charles O.

    2008-01-01

    Climate models incorporate photosynthesis-climate feedbacks, yet we lack robust tools for large-scale assessments of these processes. Recent work suggests that carbonyl sulfide (COS), a trace gas consumed by plants, could provide a valuable constraint on photosynthesis. Here we analyze airborne observations of COS and carbon dioxide concentrations during the growing season over North America with a three-dimensional atmospheric transport model. We successfully modeled the persistent vertical drawdown of atmospheric COS using the quantitative relation between COS and photosynthesis that has been measured in plant chamber experiments. Furthermore, this drawdown is driven by plant uptake rather than other continental and oceanic fluxes in the model. These results provide quantitative evidence that COS gradients in the continental growing season may have broad use as a measurement-based photosynthesis tracer.

  20. Magnetorheological Characterization of Organoclay Added Carbonyl-Iron Suspensions

    NASA Astrophysics Data System (ADS)

    Lim, S. T.; Cho, M. S.; Choi, H. J.; Jhon, M. S.

    Carbonyl-iron (CI) based magnetorheological (MR) fluid containing submicron-sized additive particles was prepared. The flow behavior at steady and oscillatory shear modes was investigated by comparing flow properties of CI-mineral oil suspensions without an additive via precise control of magnetic field strength. To enhance the dispersion stability and to examine submicron-sized filler effect for the CI suspensions, organically modified montmorillonite (organoclay) was added to the CI suspensions. In addition, with the precision control of magnetic field strength, we examined the novel features of submicron-sized particle filled CI suspensions, especially under weak magnetic field strengths, in steady shear modes; a temporal decrease of steady shear viscosity in sweeping magnetic field strengths was observed.

  1. Pt and Pt/(Cu) Carbonyl clusters synthesized by radiolysis

    NASA Astrophysics Data System (ADS)

    Le Gratiet, B.; Remita, H.; Picq, G.; Delcourt, M. O.

    1996-02-01

    In the mixed solvent: 50/50% v/v water/2-propanol, [Pt 3(CO) 6] n2- clusters with n = 3-10 have been obtained by irradiating solutions containing K 2PtCl 4 under 1 atm CO. n is deduced from the very typical UV-visible and IR absorption spectra. The reduction occurs by a combined effect of CO and of the radicals produced by radiolysis (radiocatalysis). The synthesis is selective: the nuclearity n can be chosen by adjusting the dose (high doses yield low n values). Increasing the Pt salt concentration leads to CO-stabilized subcolloid particles. Intermetallic cluster compounds are expected from solutions containing two metal salts: bimetallic Pt/Cu carbonyl clusters have been obtained. Two distinct compounds have been characterized by their UV-visible spectra. Attempts with Pt/Ru and Pt/Sn systems were unsuccessful.

  2. Gas-phase reactivity of ruthenium carbonyl cluster anions.

    PubMed

    Henderson, Matthew A; Kwok, Samantha; McIndoe, J Scott

    2009-04-01

    Partially-ligated anionic ruthenium carbonyl clusters react with alkenes, arenes, and alkanes in the gas phase; the products undergo extensive C-H activation and lose dihydrogen and carbon monoxide under collision-induced dissociation conditions. Triethylsilane and phenylsilane are also reactive towards the unsaturated clusters, and oxygen was shown to rapidly break down the cluster core by oxidative cleavage of the metal-metal bonds. These qualitative gas-phase reactivity studies were conducted using an easily-installed and inexpensive modification of a commercial electrospray ionization mass spectrometer. Interpretation of the large amounts of data generated in these studies is made relatively straightforward by employing energy-dependent electrospray ionization mass spectrometry (EDESI-MS). PMID:19185511

  3. Synthesis, characterization and bioactivities of N,O-carbonylated chitosan.

    PubMed

    Liu, Hongli; Liu, Xiaoli; Yue, Lin; Jiang, Qixing; Xia, Wenshui

    2016-10-01

    N,O-Carbonylated chitosan derivative (NTCS) was synthesized via oxidation and substitution reaction, respectively. The carboxyethylation of the polysaccharide was identified by Fourier transform infrared (FTIR), (1)H nuclear magnetic resonance (NMR), X-ray diffraction analysis (XRD), Zeta potential measurement and Thermogravimetric analysis (TGA). It is revealed that compared with chitosan (CS), NTCS exhibited an excellent solubility in distilled water, high in vitro bile acid binding capacity, as well as a low viscosity. The in vitro bile acid binding capacity reached 17.21mg/g, which was 4.5-fold higher than that of CS. The results suggest that NTCS may be useful as a potential functional food supplement in food industry or a key ingredient in the pharmaceutical industry. These findings provide important supports for developing new food additive, and expand the scope of application of CS in the food industry. PMID:27189702

  4. Palladium-Catalyzed Carbonylative Cyclization of Arenes by C-H Bond Activation with DMF as the Carbonyl Source.

    PubMed

    Chen, Jianbin; Feng, Jian-Bo; Natte, Kishore; Wu, Xiao-Feng

    2015-11-01

    A novel palladium-catalyzed CO-gas- and autoclave-free protocol for the synthesis of 11H-pyrido[2,1-b]quinazolin-11-ones has been developed. Quinazolinones, which are omnipresent motif in many pharmaceuticals and agrochemicals, were prepared in good yields by C-H bond activation and annulation using DMF as the CO surrogate. A (13) CO-labelled DMF control experiment demonstrated that CO gas was released from the carbonyl of DMF with acid as the promotor. The kinetic isotope effect (KIE) value indicated that the C-H activation step may not be involved in the rate-determining step. This methodology is operationally simple and showed a broad substrate scope with good to excellent yields. PMID:26406903

  5. Antioxidant and Antimicrobial Activity of 5-methyl-2-(5-methyl-1,3-diphenyl-1H-pyrazole-4-carbonyl)-2,4-dihydro-pyrazol-3-one

    PubMed Central

    Umesha, K. B.; Rai, K. M. L.; Harish Nayaka, M. A.

    2009-01-01

    Cycloaddition of nitrile imines 4 generated in situ by the catalytic dehydrogenation of diphenyl hydrazones 3 using Chloramine-T (CAT) as oxidant in glacial acetic acid with enolic form of ethyl acetoacetate 5 afforded Ethyl 3-aryl-5-methyl-1-phenyl-1H-pyrazol-4-carboxylate 6 in 80% yield. The said pyrazoles 6 refluxed with 80% hydrazine hydrate using absolute alcohol as solvent for about 2–3 hours to produce the respective 5-methyl-1,3-diphenyl-1H-pyrazole-4-carboxylic acid hydrazide 7. The alcoholic solution of pyrazole acid hydrazides on heating with ethyl acetoacetate 5 to give the 5-methyl-2-(5-methyl-1,3-diphenyl-1H-pyrazole-4-carbonyl)-2,4-dihydro-pyrazol-3-one 8. The synthesized compounds were found to exhibit good antimicrobial and antioxidant activity as evaluated by 1,1-diphenyl-2-picryl Hydrazyl (DPPH) radical scavenging, reducing power and DNA protection assays. PMID:23675159

  6. Gas-phase acidity and dynamics of the protonation processes of carbidopa and levodopa. A QM/QD study.

    PubMed

    Sukker, Ghader M; Elroby, Shaaban A; Hilal, Rifaat

    2016-10-01

    The present work details, our efforts to investigate and compare the acid-base properties of levodopa (LD) and carbidopa (CD), a drug combination being used in the treatment of Parkinson's disease. Protonation and deprotonation were examined for all possible sites in the two drugs. Proton affinity and proton detachment enthalpies were computed at the B3LYP/6-311++G** level of theory. Results of the present work reveal that CD is more basic and can abstract protons in solution much more efficiently than LD. Furthermore, at all deportation sites considered, CD is more acidic than LD. DFT-based ADMP, dynamic simulations have been performed to explore the dynamics of the protonation processes in LD and CD. Thus, while the dynamics of the protonation process of LD is very straightforward leading to the formation of the corresponding cation, the protonation process in CD is very complex involving a major geometry change and rearrangement. Results of the present work reveal that the active species in acid medium is not CD in its normal geometry but a carbonyl hydrazine form instead. The presence of the carbonyl group β to the hydrazine group may very well underlie its enhanced activity which allows it to bind to the active site of the DDC enzyme. The relative stabilities of various water-water-CD complexes have been computed and compared. PMID:26511889

  7. [Source emission characteristics of malodorous volatile organic carbonyls from a municipal sewage treatment plant].

    PubMed

    Zhou, Mi; Wang, Bo-Guang; Zhao, De-Jun; Zhang, Chun-Lin; Gu, Yin-Gang

    2011-12-01

    A 4-day field observation was conducted at Liede sewage treatment plant in Guangzhou, using PFPH/GC/MS method to analyse the composition and the concentration of volatile carbonyl compounds, and investigate the source emission characteristics of the pollutants. The results were as follows: 18 carbonyl species were detected, which including 15 malodorous volatile carbonyls with a concentration range from 0.39 microg x m(-3) to 19.92 microg x m(-3) at six processing units. Mean value of the total malodorous volatile carbonyls was (68.66 +/- 10.05) microg x m(-3). Normalization data process was used to research the source emission profile for malodorous volatile carbonyls, formaldehyde, acetaldehyde, propionaldehyde, 2-butanone, butyraldehyde and hexaldehyde were found to be molecular markers of the source emission with their percentage of total carbonyls up to 78.91%. Hexaldehyde was the most abundant carbonyl species with an average concentration of 11.71 microg x m(-3). Using a calculation model of area source emission, it estimated that the total annual emissions of the municipal sewage treatment plant was 2 302.33 kg(-1), and the contribution ratio of each processing unit was in an order of biochemical reaction basin, concentration basin, grade A aeration, ascending pump room, grit basin, dewatering house. The malodorous emission of sewage treatment plant is affected by many complex factors, so there's some uncertainty on the estimate. PMID:22468520

  8. Variation of ambient carbonyl levels in urban Beijing between 2005 and 2012

    NASA Astrophysics Data System (ADS)

    Chen, Wentai; Shao, Min; Wang, Ming; Lu, Sihua; Liu, Ying; Yuan, Bin; Yang, Yudong; Zeng, Limin; Chen, Zhongming; Chang, Chih-Chung; Zhang, Qian; Hu, Min

    2016-03-01

    Carbonyl compounds are important precursors of secondary air pollutants. With the rapid economic development and the implementation of stricter control measures in Beijing, the sources of carbonyls possibly changed. Based on measurement data obtained at an urban site in Beijing between 2005 and 2012, we investigated annual variations in carbonyl levels and sources during these years. In summer, formaldehyde and acetaldehyde levels decreased significantly at a rate of 9.1%/year and 7.2%/year, respectively, while acetone levels increased at a rate of 4.3%/year. In winter, formaldehyde levels increased and acetaldehyde levels decreased. We also investigated the factors driving the variation in carbonyls levels during summer by determination of emission ratios for carbonyls and their precursors, and calculation of photochemical formation of carbonyls. The relative declines for primary formaldehyde and acetaldehyde levels were larger than those for secondary formation. This is possibly due to the increasing usage of natural gas and liquefied petroleum gas which could result in the rise of carbonyl precursor emission ratios. The increase in acetone levels might be related to the rising solvent usage in Beijing during these years. The influences of these sources should be paid more attention in future research.

  9. Electroless plating preparation and electromagnetic properties of Co-coated carbonyl iron particles/polyimide composite

    NASA Astrophysics Data System (ADS)

    Zhou, Yingying; Zhou, Wancheng; Li, Rong; Qing, Yuchang; Luo, Fa; Zhu, Dongmei

    2016-03-01

    To solve the serious electromagnetic interference problems at elevated temperature, one thin microwave-absorbing sheet employing Co-coated carbonyl iron particles and polyimide was prepared. The Co-coated carbonyl iron particles were successfully prepared using an electroless plating method. The microstructure, composition, phase and static magnetic properties of Co-coated carbonyl iron particles were characterized by combination of scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The electromagnetic parameters of Co-coated carbonyl iron particles/polyimide composite were measured in the frequency range of 2-18 GHz, and the electromagnetic loss mechanism of the material-obtained was discussed. The microwave absorption properties of composites before and after heat treatment at 300 °C for 100 h were characterized in 2-18 GHz frequency range. It was established that composites based on Co-coated carbonyl iron demonstrate thermomagnetic stability, indicating that Co coating reduces the oxidation of carbonyl iron. Thus, Co-coated carbonyl iron particles/polyimide composites are useful in the design of microwave absorbers operating at temperatures up to 300 °C.

  10. A Theoretical Investigation of the Plausibility of Reactions Between Ammonia and Carbonyl Species (Formaldehyde, Acetaldehyde, and Acetone) in Interstellar Ice Analogs at Ultracold Temperatures

    NASA Technical Reports Server (NTRS)

    Chen, Lina; Woon, David E.

    2011-01-01

    We have reexamined the reaction between formaldehyde and ammonia, which was previously studied by us and other workers in modestly sized cluster calculations. Larger model systems with up to 12H2O were employed, and reactions of two more carbonyl species, acetaldehyde and acetone, were also carried out. Calculations were performed at the B3LYP/6-31+G** level with bulk solvent effects treated with a polarizable continuum model; limited MP2/6-31+G** calculations were also performed. We found that while the barrier for the concerted proton relay mechanism described in previous work remains modest, it is still prohibitively high for the reaction to occur under the ultracold conditions that prevail in dense interstellar clouds. However, a new pathway emerged in more realistic clusters that involves at least one barrierless step for two of the carbonyl species considered here: ammonia reacts with formaldehyde and acetaldehyde to form a partial charge transfer species in small clusters (4H2O) and a protonated hydroxyamino intermediate species in large clusters (9H2O, 12H2O); modest barriers that decrease sharply with cluster size are found for the analogous processes for the acetone-NH3 reaction. Furthermore, if a second ammonia replaces one of the water molecules in calculations in the 9H2O clusters, deprotonation can occur to yield the same neutral hydroxyamino species that is formed via the original concerted proton relay mechanism. In at least one position, deprotonation is barrierless when zero-point energy is included. In addition to describing the structures and energetics of the reactions between formaldehyde, acetaldehyde, and acetone with ammonia, we report spectroscopic predictions of the observable vibrational features that are expected to be present in ice mixtures of different composition.

  11. Elastic proton-proton scattering at RHIC

    SciTech Connect

    Yip, K.

    2011-09-03

    Here we describe elastic proton+proton (p+p) scattering measurements at RHIC in p+p collisions with a special optics run of {beta}* {approx} 21 m at STAR, at the center-of-mass energy {radical}s = 200 GeV during the last week of the RHIC 2009 run. We present preliminary results of single and double spin asymmetries.

  12. What's In a Proton?

    ScienceCinema

    Brookhaven Lab

    2010-01-08

    Physicist Peter Steinberg explains that fundamental particles like protons are themselves made up of still smaller particles called quarks. He discusses how new particles are produced when quarks are liberated from protons...a process that can be observed

  13. Proton pump inhibitors

    MedlinePlus

    Proton pump inhibitors (PPIs) are medicines that work by reducing the amount of stomach acid made by glands in ... Proton pump inhibitors are used to: Relieve symptoms of acid reflux, or gastroesophageal reflux disease (GERD). This is a ...

  14. What's In a Proton?

    SciTech Connect

    Brookhaven Lab

    2009-07-08

    Physicist Peter Steinberg explains that fundamental particles like protons are themselves made up of still smaller particles called quarks. He discusses how new particles are produced when quarks are liberated from protons...a process that can be observed

  15. Characteristics of carbonyls: Concentrations and source strengths for indoor and outdoor residential microenvironments in China

    NASA Astrophysics Data System (ADS)

    Wang, B.; Lee, S. C.; Ho, K. F.

    Indoor and outdoor carbonyl concentrations were measured simultaneously in 12 urban dwellings in Beijing, Shanghai, Guangzhou, and Xi'an, China in summer (from July to September in 2004) and winter (from December 2004 to February 2005). Formaldehyde was the most abundant indoor carbonyls species, while formaldehyde, acetaldehyde and acetone were found to be the most abundant outdoor carbonyls species. The average formaldehyde concentrations in summer indoor air varied widely between cities, ranging from a low of 19.3 μg m -3 in Xi'an to a high of 92.8 μg m -3 in Beijing. The results showed that the dwellings with tobacco smoke, incense burning or poor ventilation had significantly higher indoor concentrations of certain carbonyls. It was noticed that although one half of the dwellings in this study installed with low emission building materials or furniture, the carbonyls levels were still significantly high. It was also noted that in winter both the indoor and outdoor acetone concentrations in two dwellings in Guangzhou were significantly high, which were mainly caused by the usage of acetone as industrial solvent in many paint manufacturing and other industries located around Guangzhou and relatively longer lifetime of acetone for removal by photolysis and OH reaction than other carbonyls species. The indoor carbonyls levels in Chinese dwellings were higher than that in dwellings in the other countries. The levels of indoor and ambient carbonyls showed great seasonal differences. Six carbonyls species were carried out the estimation of indoor source strengths. Formaldehyde had the largest indoor source strength, with an average of 5.25 mg h -1 in summer and 1.98 mg h -1 in winter, respectively. However, propionaldehyde, crotonaldehyde and benzaldehyde had the weakest indoor sources.

  16. Proton: the particle.

    PubMed

    Suit, Herman

    2013-11-01

    The purpose of this article is to review briefly the nature of protons: creation at the Big Bang, abundance, physical characteristics, internal components, and life span. Several particle discoveries by proton as the experimental tool are considered. Protons play important roles in science, medicine, and industry. This article was prompted by my experience in the curative treatment of cancer patients by protons and my interest in the nature of protons as particles. The latter has been stimulated by many discussions with particle physicists and reading related books and journals. Protons in our universe number ≈10(80). Protons were created at 10(-6) -1 second after the Big Bang at ≈1.37 × 10(10) years beforethe present. Proton life span has been experimentally determined to be ≥10(34) years; that is, the age of the universe is 10(-24)th of the minimum life span of a proton. The abundance of the elements is hydrogen, ≈74%; helium, ≈24%; and heavier atoms, ≈2%. Accordingly, protons are the dominant baryonic subatomic particle in the universe because ≈87% are protons. They are in each atom in our universe and thus involved in virtually every activity of matter in the visible universe, including life on our planet. Protons were discovered in 1919. In 1968, they were determined to be composed of even smaller particles, principally quarks and gluons. Protons have been the experimental tool in the discoveries of quarks (charm, bottom, and top), bosons (W(+), W(-), Z(0), and Higgs), antiprotons, and antineutrons. Industrial applications of protons are numerous and important. Additionally, protons are well appreciated in medicine for their role in radiation oncology and in magnetic resonance imaging. Protons are the dominant baryonic subatomic particle in the visible universe, comprising ≈87% of the particle mass. They are present in each atom of our universe and thus a participant in every activity involving matter. PMID:24074929

  17. Proton: The Particle

    SciTech Connect

    Suit, Herman

    2013-11-01

    The purpose of this article is to review briefly the nature of protons: creation at the Big Bang, abundance, physical characteristics, internal components, and life span. Several particle discoveries by proton as the experimental tool are considered. Protons play important roles in science, medicine, and industry. This article was prompted by my experience in the curative treatment of cancer patients by protons and my interest in the nature of protons as particles. The latter has been stimulated by many discussions with particle physicists and reading related books and journals. Protons in our universe number ≈10{sup 80}. Protons were created at 10{sup −6} –1 second after the Big Bang at ≈1.37 × 10{sup 10} years beforethe present. Proton life span has been experimentally determined to be ≥10{sup 34} years; that is, the age of the universe is 10{sup −24}th of the minimum life span of a proton. The abundance of the elements is hydrogen, ≈74%; helium, ≈24%; and heavier atoms, ≈2%. Accordingly, protons are the dominant baryonic subatomic particle in the universe because ≈87% are protons. They are in each atom in our universe and thus involved in virtually every activity of matter in the visible universe, including life on our planet. Protons were discovered in 1919. In 1968, they were determined to be composed of even smaller particles, principally quarks and gluons. Protons have been the experimental tool in the discoveries of quarks (charm, bottom, and top), bosons (W{sup +}, W{sup −}, Z{sup 0}, and Higgs), antiprotons, and antineutrons. Industrial applications of protons are numerous and important. Additionally, protons are well appreciated in medicine for their role in radiation oncology and in magnetic resonance imaging. Protons are the dominant baryonic subatomic particle in the visible universe, comprising ≈87% of the particle mass. They are present in each atom of our universe and thus a participant in every activity involving matter.

  18. Extraction of dielectric and magnetic properties of carbonyl iron powder composites at high frequencies

    NASA Astrophysics Data System (ADS)

    Zivkovic, I.; Murk, A.

    2012-06-01

    In this paper, we examine carbonyl iron composites in silicone rubber and epoxy matrices. Transmission measurements were performed at W (70 to 110 GHz) and Ka (26 to 40 GHz) bands and effective permittivity and permeability of composites with 10% volume fraction of carbonyl iron powder (CIP) were extracted at these frequencies. To extract permittivity and permeability of carbonyl iron powder in W and Ka bands, we use Looyenga formula. We extract permittivity and permeability of CIP from both silicone rubber and epoxy based composites and good agreement is achieved.

  19. A Convenient Palladium-Catalyzed Reductive Carbonylation of Aryl Iodides with Dual Role of Formic Acid.

    PubMed

    Qi, Xinxin; Li, Chong-Liang; Wu, Xiao-Feng

    2016-04-18

    Palladium-catalyzed reductive carbonylation of aryl halides represents a straightforward pathway for the synthesis of aromatic aldehydes. The known reductive carbonylation procedures either require CO gas or complexed compounds as CO sources. In this communication, we developed a palladium-catalyzed reductive carbonylation of aryl iodides with formic acid as the formyl source. As a convenient, practical, and environmental friendly methodology, no additional silane or H2 was required. A variety of aromatic aldehydes were isolated in moderate to excellent yields under mild reaction conditions. Notably, this is the first procedure on using formic acid as the formyl source. PMID:26934464

  20. Chiral phosphoric acid catalyzed enantioselective synthesis of β-amino-α,α-difluoro carbonyl compounds.

    PubMed

    Kashikura, Wataru; Mori, Keiji; Akiyama, Takahiko

    2011-04-01

    A biphenol-based chiral phosphoric acid bearing a 9-anthryl group at each of the 3,3'-positions catalyzed the asymmetric Mannich-type reaction of N-Boc imine with difluoroenol silyl ethers in the presence of MS3A in THF to afford β-amino-α,α-difluoroketones in good yields and with excellent enantioselectivities. Optically pure 3,3-difluoroazetidin-2-one was readily synthesized from the Mannich-adduct. PMID:21391557

  1. Carbonyl compounds over urban Beijing: Concentrations on haze and non-haze days and effects on radical chemistry

    NASA Astrophysics Data System (ADS)

    Rao, Zhihan; Chen, Zhongming; Liang, Hao; Huang, Liubin; Huang, Dao

    2016-01-01

    Carbonyl compounds play an important role in the formation of secondary aerosols and the cycling of free radicals in the atmosphere. We measured carbonyl compounds over urban Beijing, a megacity in the North China Plain, in summer and winter to investigate the relation of carbonyl compounds with haze and the interaction between carbonyl compounds and atmospheric radical cycling. We also determined carbonyl compounds in summer rainwater. Data of carbonyl compounds were analyzed in four cases, i.e., summer haze days (SHD), summer non-haze days (SND), winter haze days (WHD), and winter non-haze days (WND). Interestingly, the level of carbonyl compounds during WHD approached that of summer days. The results of the principal component analysis showed that there was no obvious source difference between SHD and SND. On WHD, however, more carbonyl compounds originated from the "diesel engine exhaust emission" than those on WND. We evaluated the effect of carbonyl compounds on the free radical cycling and the NO consumption potential for OH formation in the photochemical reactions using a novel ratio method. It was found that the production rate of ROx (the sum of OH, HO2 and RO2 radicals) was highest on SND, while the yield of ROx radicals from the reactions of carbonyl compounds was highest on WHD. Further, carbonyl compounds consumed more NO to produce OH radicals on WHD compared to the other three cases.

  2. Understanding the Mechanism of the Divergent Reactivity of Non-Heteroatom-Stabilized Chromium Carbene Complexes with Furfural Imines: Formation of Benzofurans and Azetines.

    PubMed

    Funes-Ardoiz, Ignacio; González, Jairo; Santamaría, Javier; Sampedro, Diego

    2016-02-19

    The mechanisms of the reaction between non-heteroatom-stabilized alkynyl chromium carbene complexes prepared in situ and furfural imines to yield benzofurans and/or azetines have been explored by means of density functional theory method calculations. The reaction proceeds through a complex cascade of steps triggered by a nucleophilic addition of the imine nitrogen atom. The formation of two benzofuran regioisomers has been explained in terms of competitive nucleophilic attacks to different positions of the carbene complex. Each of these regioisomers can be obtained as the major product depending on the starting materials. The overall sequence could be controlled to yield benzofurans or azetines by adjusting the substituents present in the initial carbene complex. This mechanistic information allowed for the preparation of new benzofurans and azetinylcarbenes in good yields. PMID:26799934

  3. Contribution of reactivity indexes in the formation of β-lactams through [2+2] cycloaddition between substituted ketenes and imines

    NASA Astrophysics Data System (ADS)

    Sharma, Pratibha; Ahuja, Monika; Kumar, Ashok; Sahu, Vinita

    2015-05-01

    A quantum computational study has been performed at B3LYP/6-311G++(d, p) level to investigate mechanistic details of [2+2] cycloaddition reaction between substituted ketenes and imines. The global electrophilicity index, defined within the conceptual density functional theory (DFT), was used to distinguish the electrophilic and nucleophilic components of cycloaddition reaction on a unique scale of electrophilicity. In order to evaluate the feasibility of cycloaddition, the activation energies (B3LYP/6-311G(d)) have also been determined. An interesting interaction between a series of substituted ketenes (electrophiles) 1-10, and imines (nucleophiles) 1-3, has been deduced in order to rationalize these results.

  4. Pyridine Group-Assisted Addition of Diazo-Compounds to Imines in the 3-CC Reaction of 2-Aminopyridines, Aldehydes, and Diazo-Compounds

    PubMed Central

    Gulevich, Anton V.; Helan, Victoria; Wink, Donald J.

    2013-01-01

    A novel three-component (3-CC) coupling reaction of 2-aminoazines, aromatic aldehydes and diazo-compounds producing polyfunctional β-amino-α-diazo-compounds has been developed. The reaction features an unprecedented heterocycle-assisted addition of a diazo-compound to an imine. The obtained diazoesters were efficiently converted into valuable heterocycles, as well as to β-amino acid derivatives. PMID:23373731

  5. A Convenient Synthesis of γ–Amino-Ynamides via Additions of Lithiated Ynamides to Aryl Imines. Observation of an Aza-Meyer-Schuster Rearrangement.†

    PubMed Central

    Qi, Rui; Wang, Xiao-Na; Wang, Chao-Chao; Li, Qian; Li, Hui; Lv, Ming-Can; Yu, Qing

    2013-01-01

    Efforts in developing an expeditious and convenient method for synthesizing γ–amino-ynamides via nucleophilic addition of lithiated ynamides to aryl imines are described. This work also features an aza-variant of a Meyer-Schuster rearrangement of γ–amino-ynamides and the synthetic utility of γ–amino-ynamides in an intramolecular ketenimine-[2 + 2] cycloaddition. PMID:23976795

  6. Aqueous Sulfate Separation by Sequestration of [(SO4)2(H2O)4]4 Clusters within Highly Insoluble Imine-Linked Bis-Guanidinium Crystals

    DOE PAGESBeta

    Custelcean, Radu; Williams, Neil J.; Seipp, Charles A.; Ivanov, Aleksandr; Bryantsev, Vyacheslav

    2015-12-18

    Quantitative removal of sulfate from seawater was achieved by selective crystallization of the anion with a bis(guanidinium) ligand self-assembled in situ through imine condensation of simple components. The resulting crystalline salt has an exceptionally low aqueous solubility, on a par with BaSO4. Single-crystal X-ray diffraction analysis revealed pairs of sulfate anions clustered together with four water molecules within the crystals.

  7. Synthesis of two nickel (II) complexes bearing pyrrolide-imine ligand and their catalytic effects on thermal decomposition of ammonium perchlorate

    NASA Astrophysics Data System (ADS)

    Zhuo, Ji-Bin; Ma, Zai-He; Lin, Cai-Xia; Xie, Li-Li; Bai, Sha; Yuan, Yao-Feng

    2015-04-01

    Two pyrrolide-imine chelating Ni(II) complexes {[2-(2-CH3O-C6H4-NCH)C4H3N]2Ni (2a) and [(Fc-NCH)]C4H3N]2Ni (2b, Fc = ferrocenyl)} were prepared via treating corresponding Schiff base with 0.5 equiv. NiCl2·6H2O in moderate yields. The crystal structures of 2a and 2b were determined by single-crystal X-ray diffraction. Atom Ni(II) of 2a was coordinated by two pyrrolide-imine ligands in trans position to display a twisted octahedral coordination geometry. Ni(II) of 2b had a distorted square-planar geometry, bonded with two ferrocenyl pyrrole-imine ligands, each ferrocene and pyrrole of ligands adopting a trans conformation. The UV-vis spectroscopy and electrochemical measurements were investigated. The catalytic efficiency of the complexes on the thermal decomposition of ammonium perchlorate (AP) was studied by differential scanning calorimetry (DSC) and thermogravimetry (TG). Compared with the thermal decomposition of pure AP, the decomposition temperatures were decreased by 27 °C, 77 °C, 88 °C and 172 °C, respectively when 1a, 1b, 2a and 2b were added in AP. The results indicated that the Ni(II) complex 2b bearing ferrocene-based pyrrolide-imine N,N-chelate ligand displayed an excellent catalytic efficiency on the thermal decomposition of AP.

  8. Atmospheric Sulfur Cycle Effects of Carbonyl Sulfide (OCS)

    NASA Technical Reports Server (NTRS)

    McBee, Joshua

    1996-01-01

    Carbonyl Sulfide(OCS) is considered to be one of the major sources of sulfur appearing in the stratosphere due to its relative inertness, about I to 10 yearsl. However, the roles of OCS as well as other reduced sulfur compounds such as carbon disulfide (CS2), hydrogen sulfide (H2S), and dimethyl disulfide(CH3)2S2, are not completely understood in the atmosphenc sulfur cycle. Consequently vely little information is available about the effect of sulfur compounds in the stratosphere. The ability of OCS to penetrate into the stratosphere makes it an excellent tracer for study of the role of the sulfi r cycle in stratospheric chemistry. Previously techniques such as gas chromatography and whole air sampling have been used to measure OCS analytically. Each technique had its drawbacks however, with both being quite slow, and whole air sampling being somewhat unreliable. With molecular spectroscopy, however, it has been found in recent years that the tunable diode laser absorption spectrometer (TDL) provides a very rapid and accurate method of measuring OCS and other trace gases

  9. Solid Carbonyl Sulphide (OCS) in W33A

    NASA Technical Reports Server (NTRS)

    Palumbo, M. E.; Tielens, A. G. G. M.; Tokunaga, A. T.

    1995-01-01

    We present ground-based observations of the 2041/cm (4.9 micrometer) absorption feature toward the deeply embedded protostar W33A. We attribute this interstellar feature to solid carbonyl sulphide (OCS) embedded in icy grain mantles along the line of sight. We have made an extensive laboratory study of the infrared characteristics of OCS in various ice mixtures. Studies of the 2041/cm band of solid OCS and solid mixtures containing OCS show that its shape and peak position are sensitive to the molecular environment of the OCS molecule. Mie scattering calculations show that the peak position and profile of the OCS band depend on the shape and size of the absorbing grain when the OCS concentration is larger than 0.05. For lower OCS concentrations, laboratory-measured bulk spectra agree very well with the absorption spectra of small grains. We have compared the observed feature with laboratory and theoretical spectra of astrophysically relevant mixtures. The best agreement is obtained for mixtures with traces of OCS in a methanol-rich matrix. This would suggest the presence of independent grain components and in particular of a minor fraction of methanol-rich icy grain mantles in which OCS is embedded. From the strength of the absorption feature we deduce a OCS/H 20 ratio, along the line of sight, of 4 x 10(exp -4).

  10. Solid Carbonyl Sulphide (OCS) in W33A

    NASA Technical Reports Server (NTRS)

    Palumbo, M. E.; Tielens, A. G. G. M.; Tokunaga, A. T.

    1995-01-01

    We present ground-based observations of the 2041 cm(exp -1) (4.9 mm) absorption feature toward the deeply embedded protostar W33A. We attribute this interstellar feature to solid carbonyl sulphide (OCS) embedded in icy grain mantles along the line of sight. We have made an extensive laboratory study of the infrared characteristics of OCS in various ice mixtures. Studies of the 2041 cm(exp -1) band of solid OCS and solid mixtures containing OCS show that its shape and peak position are sensitive to the molecular environment of the OCS molecule. Mie scattering calculations show that the peak position and profile of the OCS band depend on the shape and size of the absorbing grain when the OCS concentration is larger than 0.05. For lower OCS concentrations, laboratory-measured bulk spectra agree very well with the absorption spectra of small grains. We have compared the observed feature with laboratory and theoretical spectra of astrophysically relevant mixtures. The best agreement is obtained for mixtures with traces of OCS in a methanol-rich matrix. This would suggest the presence of independent grain components and in particular of a minor fraction of methanol-rich icy grain mantles in which OCS is embedded. From the strength of the absorption feature we deduce a OCS/H2O ratio, along the line of sight, of 4 x 10(exp -4).

  11. Thermal characterization of magnetically aligned carbonyl iron/agar composites.

    PubMed

    Diaz-Bleis, D; Vales-Pinzón, C; Freile-Pelegrín, Y; Alvarado-Gil, J J

    2014-01-01

    Composites of magnetic particles into polymeric matrices have received increasing research interest due to their capacity to respond to external magnetic or electromagnetic fields. In this study, agar from Gelidium robustum has been chosen as natural biocompatible polymer to build the matrix of the magnetic carbonyl iron particles (CIP) for their uses in biomedical fields. Heat transfer behavior of the CIP-agar composites containing different concentrations (5, 10, 15, 20, 25 and 30% w/w) of magnetically aligned and non-aligned CIP in the agar matrix was studied using photothermal radiometry (PTR) in the back-propagation emission configuration. The morphology of the CIP-agar composites with aligned and non-aligned CIP under magnetic field was also evaluated by scanning electron microscopy (SEM). The results revealed a dominant effect of CIP concentration over the alignment patterns induced by the magnetic field, which agrees with the behavior of the thermal diffusivity and thermal conductivity. Agar served as a perfect matrix to be used with CIP, and CIP-agar composites magnetically aligned at 20% CIP concentration can be considered as promising 'smart' material for hyperthermia treatments in the biomedical field. PMID:24274482

  12. The effect of iodine on the peroxidation of carbonyl compounds.

    PubMed

    Zmitek, Katja; Zupan, Marko; Stavber, Stojan; Iskra, Jernej

    2007-08-17

    Peroxidation of ketones and aldehydes with iodine as a catalyst was studied. Ketones reacted with 30% aq hydrogen peroxide in the presence of 10 mol % of iodine to yield gem-dihydroperoxides in acetonitrile and hydroperoxyketals in methanol. The yield of hydroperoxidation of various cyclic ketones was 60-98%, including androstane-3,17-dione, while acyclic ketones were converted with a similar efficiency. Aromatic aldehydes were also converted to gem-dihydroperoxides with hydrogen peroxide and iodine as catalyst in acetonitrile and to hydroperoxyacetal in methanol, while the reactivity of aliphatic ones remained the same as in noncatalyzed reactions. tert-Butylhydroperoxide reacted in a similar manner, giving the corresponding perether derivatives. A study was also made of the relative kinetics of dihydroperoxidation from which the Hammet equation gave a reaction constant (rho) of -2.76, indicating the strong positive charge development in the transition state and the important role of rehybridization in the conversion of hydroperoxyhemiketal to gem-dihydroperoxide. In acetonitrile, the iodine catalyst is apparently able to discriminate between the elimination of a hydroxy, methoxy, and hydroperoxy group and addition of water, methanol, and H2O2 to a carbonyl group. PMID:17661522

  13. Human TTR conformation altered by rhenium tris-carbonyl derivatives.

    PubMed

    Ciccone, Lidia; Policar, Clotilde; Stura, Enrico A; Shepard, William

    2016-09-01

    Transthyretin (TTR) is a 54 kDa homotetrameric serum protein that transports thyroxine (T4) and retinol. TTR is potentially amyloidogenic due to homotetramer dissociation into monomeric intermediates that self-assemble as amyloid deposits and insoluble fibrils. Most crystallographic structures, including those of amyloidogenic variants show the same tetramer without major variations in the monomer-monomer interface nor in the volume of the interdimeric cavity. Soaking TTR crystals in a solution containing rhenium tris-carbonyl derivatives yields a TTR conformer never observed before. Only one of the two monomers of the crystallographic dimer is significantly altered, and the inner part of the T4 binding cavity is expanded at one end and shrunk at the other. The result redefines the mechanism of allosteric communication between the two sites, suggesting that negative cooperativity is a function of dimer asymmetry, which can be induced through internal or external binding. An aspect that remains unexplained is why the conformational changes are ubiquitous throughout the crystal although the heavy metal content of the derivatized crystals is relatively low. The conformational changes observed, which include Leu(82), may represent a form of TTR better at scavenging β-Amyloid. At a resolution of 1.69Å, with excellent refinement statistics and well defined electron density for all parts of the structure, it is possible to envisage answering important questions that range from protein cooperative behavior to heavy atom induced protein conformational modifications that can result in crystallographic non-isomorphism. PMID:27402536

  14. Hydroxyl radical substitution in halogenated carbonyls: oxalic acid formation.

    PubMed

    Christiansen, Carrie J; Dalal, Shakeel S; Francisco, Joseph S; Mebel, Alexander M; Gaffney, Jeffrey S

    2010-03-01

    An ab initio study of OH radical substitution reactions in halogenated carbonyls is conducted. Hydroxyl radical substitution into oxalyl dichloride [ClC(O)C(O)Cl] and oxalyl dibromide [BrC(O)C(O)Br], resulting in the formation of oxalic acid, is presented. Analogous substitution reactions in formyl chloride [ClCH(O)], acetyl chloride [ClC(O)CH(3)], formyl bromide [BrCH(O)], and acetyl bromide [BrC(O)CH(3)] are considered. Energetics of competing hydrogen abstraction reactions for all applicable species are computed for comparison. Geometry optimizations and frequency computations are performed using the second-order Møller-Plesset perturbation theory (MP2) and the 6-31G(d) basis set for all minimum species and transition states. Single point energy computations are performed using fourth-order Møller-Plesset perturbation theory (MP4) and coupled cluster theory [CCSD(T)]. Potential energy surfaces, including activation energies and enthalpies, are determined from the computations. These potential energy surfaces show that OH substitution into ClC(O)C(O)Cl and BrC(O)C(O)Br, resulting in the formation of oxalic acid and other minor products, is energetically favorable. Energetics of analogous reactions with ClCH(O), BrCH(O), ClC(O)CH(3), and BrC(O)CH(3) are also computed. PMID:20131850

  15. Seasonal fluxes of carbonyl sulfide in a midlatitude forest

    NASA Astrophysics Data System (ADS)

    Commane, Róisín; Meredith, Laura K.; Baker, Ian T.; Berry, Joseph A.; Munger, J. William; Montzka, Stephen A.; Templer, Pamela H.; Juice, Stephanie M.; Zahniser, Mark S.; Wofsy, Steven C.

    2015-11-01

    Carbonyl sulfide (OCS), the most abundant sulfur gas in the atmosphere, has a summer minimum associated with uptake by vegetation and soils, closely correlated with CO2. We report the first direct measurements to our knowledge of the ecosystem flux of OCS throughout an annual cycle, at a mixed temperate forest. The forest took up OCS during most of the growing season with an overall uptake of 1.36 ± 0.01 mol OCS per ha (43.5 ± 0.5 g S per ha, 95% confidence intervals) for the year. Daytime fluxes accounted for 72% of total uptake. Both soils and incompletely closed stomata in the canopy contributed to nighttime fluxes. Unexpected net OCS emission occurred during the warmest weeks in summer. Many requirements necessary to use fluxes of OCS as a simple estimate of photosynthesis were not met because OCS fluxes did not have a constant relationship with photosynthesis throughout an entire day or over the entire year. However, OCS fluxes provide a direct measure of ecosystem-scale stomatal conductance and mesophyll function, without relying on measures of soil evaporation or leaf temperature, and reveal previously unseen heterogeneity of forest canopy processes. Observations of OCS flux provide powerful, independent means to test and refine land surface and carbon cycle models at the ecosystem scale.

  16. Seasonal fluxes of carbonyl sulfide in a midlatitude forest.

    PubMed

    Commane, Róisín; Meredith, Laura K; Baker, Ian T; Berry, Joseph A; Munger, J William; Montzka, Stephen A; Templer, Pamela H; Juice, Stephanie M; Zahniser, Mark S; Wofsy, Steven C

    2015-11-17

    Carbonyl sulfide (OCS), the most abundant sulfur gas in the atmosphere, has a summer minimum associated with uptake by vegetation and soils, closely correlated with CO2. We report the first direct measurements to our knowledge of the ecosystem flux of OCS throughout an annual cycle, at a mixed temperate forest. The forest took up OCS during most of the growing season with an overall uptake of 1.36 ± 0.01 mol OCS per ha (43.5 ± 0.5 g S per ha, 95% confidence intervals) for the year. Daytime fluxes accounted for 72% of total uptake. Both soils and incompletely closed stomata in the canopy contributed to nighttime fluxes. Unexpected net OCS emission occurred during the warmest weeks in summer. Many requirements necessary to use fluxes of OCS as a simple estimate of photosynthesis were not met because OCS fluxes did not have a constant relationship with photosynthesis throughout an entire day or over the entire year. However, OCS fluxes provide a direct measure of ecosystem-scale stomatal conductance and mesophyll function, without relying on measures of soil evaporation or leaf temperature, and reveal previously unseen heterogeneity of forest canopy processes. Observations of OCS flux provide powerful, independent means to test and refine land surface and carbon cycle models at the ecosystem scale. PMID:26578759

  17. Magnetorheological characteristics of carbon nanotube wrapped carbonyl iron particles

    NASA Astrophysics Data System (ADS)

    Fang, Fei Fei; Choi, Byung Il; Choi, Hyoung Jin

    2009-02-01

    Carbonyl iron (CI) based magnetorheological (MR) fluid exhibits serious dispersion defect in general due to large density mismatch between CI particles and continuous medium, which restricts further MR application. Thus, various strategies were explored either to reduce the density or to prevent CI particle aggregation. Among them, polymer coating technology becomes more prevalent due to favorable morphology obtained and effective decrease in density by introducing polymeric shell; nevertheless, coating polymer on the surface of CI particles is always influenced by the selected grafting agent, mole ratio of reactant or the temperature of reaction. In this work, considering self-assembling trend of carbon nanotube (CNT) which exhibits similar density with polymer but better magnetic property due to the iron catalyst, we constructed a dense nest composed of CNT on the surface of CI particles by using 4-aminobenzoic acid (PABA) as a grafting agent under sonication. Thickness and morphology of the CNT nest were found to be related with sonication duration via SEM/TEM images. MR performances (yield stress behavior, shear viscosity) of the CI/CNT particles based MR fluid were investigated via controlled shear rate and controlled shear stress methods. Finally, sedimentation observation was checked to be improved.

  18. Aldol Condensation of Volatile Carbonyl Compounds in Acidic Aerosols

    NASA Astrophysics Data System (ADS)

    Noziere, B.; Esteve, W.

    2003-12-01

    Reactions of volatile organic compounds in acidic aerosols have been shown recently to be potentially important for organic aerosol formation and growth. Aldol condensation, the acid-catalyzed polymerization of carbonyl compounds, is a likely candidate to enhance the flux of organic matter from the gas phase to the condensed phase in the atmosphere. Until now these reactions have only been characterized for conditions relevant to synthesis (high acidities and liquid phase systems) and remote from atmospheric ones. In this work, the uptake of gas-phase acetone and 2,4\\-pentanedione by sulfuric acid solutions has been measured at room temperature using a Rotated Wetted Wall Reactor coupled to a Mass Spectrometer. The aldol condensation rate constants for 2,4\\-pentanedione measured so far for sulfuric acid solutions between 96 and 70 % wt. display a variation with acidity in agreement with what predicted in the organic chemical literature. The values of these constants, however, are much lower than expected for this compound, and comparable to the ones of acetone. Experiments are underway to complete this study to lower acidities and understand the discrepancies with the predicted reactivity.

  19. Characterization of Aura TES carbonyl sulfide retrievals over ocean

    NASA Astrophysics Data System (ADS)

    Kuai, L.; Worden, J.; Kulawik, S. S.; Montzka, S. A.; Liu, J.

    2014-01-01

    We present a description of the NASA Aura Tropospheric Emission Spectrometer (TES) carbonyl sulfide (OCS) retrieval algorithm for oceanic observations, along with evaluation of the biases and uncertainties using aircraft profiles from the HIPPO (HIAPER Pole-to-Pole Observations) campaign and data from the NOAA Mauna Loa site. In general, the OCS retrievals (1) have less than 1.0 degree of freedom for signals (DOFs), (2) are sensitive in the mid-troposphere with a peak sensitivity typically between 300 and 500 hPa, (3) but have much smaller systematic errors from temperature, CO2 and H2O calibrations relative to random errors from measurement noise. We estimate the monthly means from TES measurements averaged over multiple years so that random errors are reduced and useful information about OCS seasonal and latitudinal variability can be derived. With this averaging, TES OCS data are found to be consistent (within the calculated uncertainties) with NOAA ground observations and HIPPO aircraft measurements. TES OCS data also captures the seasonal and latitudinal variations observed by these in situ data.

  20. Behaviour of protein carbonyl groups in juvenile myocardial infarction.

    PubMed

    Caimi, Gregorio; Canino, Baldassare; Incalcaterra, Egle; Ferrera, Eleonora; Montana, Maria; Lo Presti, Rosalia

    2013-01-01

    Acute myocardial infarction (AMI) is accompanied by oxidative stress, and protein oxidation is among the consequences of oxidative stress. We examined the plasma concentration of protein carbonyl groups (PC), a marker of protein oxidation, in a group of young subjects with AMI (45 men and 5 women; mean age 40.4 ± 4.8 yrs). We found a significant increase of PC (p < 0.001) in comparison with normal controls. No difference was observed between patients with AMI characterized by elevated ST segment and those without elevation of ST segment. There was no correlation between the ejection fraction and PC in the whole group nor in the subgroups of STEMI and non-STEMI patients. Subdividing the whole group of AMI patients according to the number of risk factors and the number of stenosed coronary vessels, the difference in PC level was not statistically significant among the subgroups. This study showed an increased protein oxidation in young subjects with recent AMI. Further investigation is needed to ascertain whether this can be a target of therapeutic intervention. PMID:22504219

  1. Tropical sources and sinks of carbonyl sulfide observed from space

    NASA Astrophysics Data System (ADS)

    Glatthor, N.; Höpfner, M.; Baker, I. T.; Berry, J.; Campbell, J. E.; Kawa, S. R.; Krysztofiak, G.; Leyser, A.; Sinnhuber, B.-M.; Stiller, G. P.; Stinecipher, J.; Clarmann, T.

    2015-11-01

    According to current budget estimations the seasonal variation of carbonyl sulfide (COS) is governed by oceanic release and vegetation uptake. Its assimilation by plants is assumed to be similar to the photosynthetic uptake of CO2 but, contrary to the latter process, to be irreversible. Therefore, COS has been suggested as cotracer of the carbon cycle. Observations of COS, however, are sparse, especially in tropical regions. We use the comprehensive data set of spaceborne measurements of the Michelson Interferometer for Passive Atmospheric Sounding to analyze its global distribution. Two major features are observed in the tropical upper troposphere around 250 hPa: enhanced amounts over the western Pacific and the Maritime Continent, peaking around 550 parts per trillion by volume (pptv) in boreal summer, and a seasonally varying depletion of COS extending from tropical South America to Africa. The large-scale COS depletion, which in austral summer amounts up to -40 pptv as compared to the rest of the respective latitude band, has not been observed before and reveals the seasonality of COS uptake through tropical vegetation. The observations can only be reproduced by global models, when a large vegetation uptake and a corresponding increase in oceanic emissions as proposed in several recent publications are assumed.

  2. Seasonal fluxes of carbonyl sulfide in a midlatitude forest

    PubMed Central

    Commane, Róisín; Meredith, Laura K.; Baker, Ian T.; Berry, Joseph A.; Munger, J. William; Montzka, Stephen A.; Templer, Pamela H.; Juice, Stephanie M.; Zahniser, Mark S.; Wofsy, Steven C.

    2015-01-01

    Carbonyl sulfide (OCS), the most abundant sulfur gas in the atmosphere, has a summer minimum associated with uptake by vegetation and soils, closely correlated with CO2. We report the first direct measurements to our knowledge of the ecosystem flux of OCS throughout an annual cycle, at a mixed temperate forest. The forest took up OCS during most of the growing season with an overall uptake of 1.36 ± 0.01 mol OCS per ha (43.5 ± 0.5 g S per ha, 95% confidence intervals) for the year. Daytime fluxes accounted for 72% of total uptake. Both soils and incompletely closed stomata in the canopy contributed to nighttime fluxes. Unexpected net OCS emission occurred during the warmest weeks in summer. Many requirements necessary to use fluxes of OCS as a simple estimate of photosynthesis were not met because OCS fluxes did not have a constant relationship with photosynthesis throughout an entire day or over the entire year. However, OCS fluxes provide a direct measure of ecosystem-scale stomatal conductance and mesophyll function, without relying on measures of soil evaporation or leaf temperature, and reveal previously unseen heterogeneity of forest canopy processes. Observations of OCS flux provide powerful, independent means to test and refine land surface and carbon cycle models at the ecosystem scale. PMID:26578759

  3. The oceanic cycle and global atmospheric budget of carbonyl sulfide

    SciTech Connect

    Weiss, P.S.

    1994-12-31

    A significant portion of stratospheric air chemistry is influenced by the existence of carbonyl sulfide (COS). This ubiquitous sulfur gas represents a major source of sulfur to the stratosphere where it is converted to sulfuric acid aerosol particles. Stratospheric aerosols are climatically important because they scatter incoming solar radiation back to space and are able to increase the catalytic destruction of ozone through gas phase reactions on particle surfaces. COS is primarily formed at the surface of the earth, in both marine and terrestrial environments, and is strongly linked to natural biological processes. However, many gaps in the understanding of the global COS cycle still exist, which has led to a global atmospheric budget that is out of balance by a factor of two or more, and a lack of understanding of how human activity has affected the cycling of this gas. The goal of this study was to focus on COS in the marine environment by investigating production/destruction mechanisms and recalculating the ocean-atmosphere flux.

  4. Teratogenicity and embryotoxicity of nickel carbonyl in Syrian hamsters

    SciTech Connect

    Sunderman, F.W. Jr.; Shen, S.K.; Reid, M.C.; Allpass, P.R.

    1980-01-01

    Nickel carbonyl was administered to groups of pregnant hamsters by inhalation on days 4, 5, 6, 7, or 8 of gestation. The dams were killed on day 15 of gestation, and the fetuses were examined for malformations. Exposure to Ni(CO)/sub 4/ on days 4 or 5 of gestation resulted in malformation in 5.5% and 5.8% of the progeny, respectively. Progeny included 9 fetuses with cystic lungs, 7 fetuses with exencephaly, 1 fetus with exencephaly plus fused rib and 1 fetus with anophthalmia plus cleft palate. Hemorrhages into serious cavities were found. In progeny of dams exposed to Ni(CO)/sub 4/ on days 6 or 7 of gestation, there was 1 fetus with fused ribs and there were 2 fetuses with hydronephrosis. In another experiment, pregnant hamsters were exposed to inhalation of Ni(CO)/sub 4/ on day 5 of gestation; these dams were permitted to deliver their litters and to nurse their pups. There was no significant difference in the average number of live pups in the Ni(CO)/sub 4/-exposed litters compared to control litters. Neonatal mortality was increased in Ni(CO)/sub 4/-exposed litters. This study demonstrates that Ni(CO)/sub 4/ is teratogenic and embryotoxic in Syrian hamsters.

  5. Synthesis of 2-Cyclopentenone Derivatives via Palladium-Catalyzed Intramolecular Carbonyl α-Alkenylation.

    PubMed

    Chen, Panpan; Meng, Yinggao; Wang, Han; Han, Feipeng; Wang, Yulong; Song, Chuanjun; Chang, Junbiao

    2016-08-01

    2-Cyclopentenone derivatives have been efficiently synthesized from 5-bromo-5-hexen-2-ones via palladium-catalyzed intramolecular carbonyl α-alkenylation followed by double-bond migration under mild reaction conditions. PMID:27463262

  6. Development of a test method for carbonyl compounds from stationary source emissions

    SciTech Connect

    Zhihua Fan; Peterson, M.R.; Jayanty, R.K.M.

    1997-12-31

    Carbonyl compounds have received increasing attention because of their important role in ground-level ozone formation. The common method used for the measurement of aldehydes and ketones is 2,4-dinitrophenylhydrazine (DNPH) derivatization followed by high performance liquid chromatography and ultra violet (HPLC-UV) analysis. One of the problems associated with this method is the low recovery for certain compounds such as acrolein. This paper presents a study in the development of a test method for the collection and measurement of carbonyl compounds from stationary source emissions. This method involves collection of carbonyl compounds in impingers, conversion of carbonyl compounds to a stable derivative with O-2,3,4,5,6-pentafluorobenzyl hydroxylamine hydrochloride (PFBHA), and separation and measurement by electron capture gas chromatography (GC-ECD). Eight compounds were selected for the evaluation of this method: formaldehyde, acetaldehyde, acrolein, acetone, butanal, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and hexanal.

  7. Spectroscopic line parameters for the nu6 band of carbonyl fluoride

    NASA Technical Reports Server (NTRS)

    Goldman, Aaron; Blatherwick, Ronald D.; Bonomo, Francis S.; Rinsland, Curtis P.

    1990-01-01

    New measurements and analysis of high-resolution (0.0025/cm) laboratory spectra of the carbonyl fluoride nu6 band are described. The data are used to generate line parameters suitable for high-resolution atmospheric studies.

  8. Ruthenium carbonyl catalyst supported on ceric oxide for preparation of olefins from synthesis gas

    DOEpatents

    Pierantozzi, Ronald

    1985-01-01

    A catalyst comprising a ruthenium carbonyl compound deposited on a cerium oxide-containing support material provides for the selective synthesis of low molecular weight olefinic hydrocarbons from mixtures of hydrogen and carbon monoxide.

  9. Gas-aerosol partitioning of semi volatile carbonyls in polluted atmosphere in Hachioji, Tokyo

    NASA Astrophysics Data System (ADS)

    Matsunaga, Sou N.; Kato, Shungo; Yoshino, Ayako; Greenberg, Jim P.; Kajii, Yoshizumi; Guenther, Alex B.

    2005-06-01

    Gaseous and particulate semi volatile carbonyls have been measured in urban air using an annular denuder sampling system. Three dicarbonyls, five aliphatic aldehydes and two hydroxy carbonyls were observed. Concentrations of other biogenic and anthropogenic volatile organic compounds (VOCs), SO2, CO, NO2 and particle concentration were also measured. Estimated gas-aerosol equilibrium constants for the carbonyls showed an inverse correlation with the concentrations of anthropogenic pollutants such as benzene, isopentane and SO2. This suggests that the increase in the fraction of non-polar anthropogenic particles in the atmosphere could change the average property of the ambient aerosols and drive the gas particle equilibrium of the carbonyls to the gas phase. This trend is uncommon in remote forest air. In this study, we examined the factors controlling the equilibrium in the polluted atmosphere and show that there is a difference in gas-aerosol partition between polluted and clean air.

  10. Comparison of sampling methods for radiocarbon dating of carbonyls in air samples via accelerator mass spectrometry

    NASA Astrophysics Data System (ADS)

    Schindler, Matthias; Kretschmer, Wolfgang; Scharf, Andreas; Tschekalinskij, Alexander

    2016-05-01

    Three new methods to sample and prepare various carbonyl compounds for radiocarbon measurements were developed and tested. Two of these procedures utilized the Strecker synthetic method to form amino acids from carbonyl compounds with either sodium cyanide or trimethylsilyl cyanide. The third procedure used semicarbazide to form crystalline carbazones with the carbonyl compounds. The resulting amino acids and semicarbazones were then separated and purified using thin layer chromatography. The separated compounds were then combusted to CO2 and reduced to graphite to determine 14C content by accelerator mass spectrometry (AMS). All of these methods were also compared with the standard carbonyl compound sampling method wherein a compound is derivatized with 2,4-dinitrophenylhydrazine and then separated by high-performance liquid chromatography (HPLC).

  11. Reaction or organomagnesium compounds of the adamantane series with carbonyl compounds

    SciTech Connect

    Yurchenko, A.G.; Fedorenko, T.V.

    1987-10-10

    In the transformations of organomagnesium compounds of the adamantane series involving aldehydes, ketones, esters, and acid chlorides the nature of the reaction products and their yields are determined by the steric hindrances at the reaction centers of the organomagnesium and carbonyl compounds and by the ease of homolysis of the C-H bonds of the carbonyl reagent. The retardation of the faster addition of the Grignard reagent at the carbonyl group as a result of steric hindrances permits homolytic removal of a hydrogen atom from the carbonyl compound by the adamantyl radical. The PMR spectra were measured on a Tesla BS-487C spectrometer at 80 MHz in carbon tetrachloride with the substances at concentrations of 5-20% and with TMS as internal standard. The IR spectra were obtained in carbon tetrachloride on a UR-10 spectrophotometer.

  12. Ruthenium carbonyl catalyst supported on ceric oxide for preparation of olefins from synthesis gas

    DOEpatents

    Pierantozzi, R.

    1985-04-02

    A catalyst comprising a ruthenium carbonyl compound deposited on a cerium oxide-containing support material provides for the selective synthesis of low molecular weight olefinic hydrocarbons from mixtures of hydrogen and carbon monoxide.

  13. A carbonyl iron/carbon fiber material for electromagnetic wave absorption.

    PubMed

    Youh, Meng-Jey; Wu, Hung-Chih; Lin, Wang-Hua; Chiu, Sheng-Cheng; Huang, Chien-Fa; Yu, Hsin-Chih; Hsu, Jen-Sung; Li, Yuan-Yao

    2011-03-01

    A carbonyl iron/carbon fiber material consisting of carbon fibers grown on micrometer-sized carbonyl iron sphere, was synthesized by chemical vapor deposition using a mixture of C2H2 and H2. The hollow-core carbon fibers (outer diameter: 140 nm and inner diameter: 40 nm) were composed of well-ordered graphene layers which were almost parallel to the long axis of the fibers. A composite (2 mm thick) consisting of the carbonyl iron/carbon fibers and epoxy resin demonstrated excellent electromagnetic (EM) wave absorption. Minimum reflection losses of -36 dB (99.95% of EM wave absorption) at 7.6 GHz and -32 dB (99.92% of EM wave absorption) at 34.1 GHz were achieved. The well-dispersed and network-like carbon fibers in the resin matrix affected the dielectric loss of the EM wave while the carbonyl iron affected the magnetic loss. PMID:21449387

  14. Study of proton radioactivities

    SciTech Connect

    Davids, C.N.; Back, B.B.; Henderson, D.J.

    1995-08-01

    About a dozen nuclei are currently known to accomplish their radioactive decay by emitting a proton. These nuclei are situated far from the valley of stability, and mark the very limits of existence for proton-rich nuclei: the proton drip line. A new 39-ms proton radioactivity was observed following the bombardment of a {sup 96}Ru target by a beam of 420-MeV {sup 78}Kr. Using the double-sided Si strip detector implantation system at the FMA, a proton group having an energy of 1.05 MeV was observed, correlated with the implantation of ions having mass 167. The subsequent daughter decay was identified as {sup 166}Os by its characteristic alpha decay, and therefore the proton emitter is assigned to the {sup 167}Ir nucleus. Further analysis showed that a second weak proton group from the same nucleus is present, indicating an isomeric state. Two other proton emitters were discovered recently at the FMA: {sup 171}Au and {sup 185}Bi, which is the heaviest known proton radioactivity. The measured decay energies and half-lives will enable the angular momentum of the emitted protons to be determined, thus providing spectroscopic information on nuclei that are beyond the proton drip line. In addition, the decay energy yields the mass of the nucleus, providing a sensitive test of mass models in this extremely proton-rich region of the chart of the nuclides. Additional searches for proton emitters will be conducted in the future, in order to extend our knowledge of the location of the proton drip line.

  15. Synthesis of 2-Alkynoates by Palladium(II)-Catalyzed Oxidative Carbonylation of Terminal Alkynes and Alcohols.

    PubMed

    Cao, Qun; Hughes, N Louise; Muldoon, Mark J

    2016-08-16

    A homogeneous Pd(II) catalyst, utilizing a simple and inexpensive amine ligand (TMEDA), allows 2-alkynoates to be prepared in high yields by an oxidative carbonylation of terminal alkynes and alcohols. The catalyst system overcomes many of the limitations of previous palladium carbonylation catalysts. It has an increased substrate scope, avoids large excesses of alcohol substrate and uses a desirable solvent. The catalyst employs oxygen as the terminal oxidant and can be operated under safer gas mixtures. PMID:27305489

  16. Protein carbonylation and aggregation precede neuronal apoptosis induced by partial glutathione depletion

    PubMed Central

    Dasgupta, Anushka; Zheng, Jianzheng; Bizzozero, Oscar A.

    2012-01-01

    While the build-up of oxidized proteins within cells is believed to be toxic, there is currently no evidence linking protein carbonylation and cell death. In the present study, we show that incubation of nPC12 (neuron-like PC12) cells with 50 μM DEM (diethyl maleate) leads to a partial and transient depletion of glutathione (GSH). Concomitant with GSH disappearance there is increased accumulation of PCOs (protein carbonyls) and cell death (both by necrosis and apoptosis). Immunocytochemical studies also revealed a temporal/spatial relationship between carbonylation and cellular apoptosis. In addition, the extent of all three, PCO accumulation, protein aggregation and cell death, augments if oxidized proteins are not removed by proteasomal degradation. Furthermore, the effectiveness of the carbonyl scavengers hydralazine, histidine hydrazide and methoxylamine at preventing cell death identifies PCOs as the toxic species. Experiments using well-characterized apoptosis inhibitors place protein carbonylation downstream of the mitochondrial transition pore opening and upstream of caspase activation. While the study focused mostly on nPC12 cells, experiments in primary neuronal cultures yielded the same results. The findings are also not restricted to DEM-induced cell death, since a similar relationship between carbonylation and apoptosis was found in staurosporine- and buthionine sulfoximine-treated nPC12 cells. In sum, the above results show for the first time a causal relationship between carbonylation, protein aggregation and apoptosis of neurons undergoing oxidative damage. To the best of our knowledge, this is the first study to place direct (oxidative) protein carbonylation within the apoptotic pathway. PMID:22376187

  17. CarSPred: a computational tool for predicting carbonylation sites of human proteins.

    PubMed

    Lv, Hongqiang; Han, Jiuqiang; Liu, Jun; Zheng, Jiguang; Liu, Ruiling; Zhong, Dexing

    2014-01-01

    Protein carbonylation is one of the most pervasive oxidative stress-induced post-translational modifications (PTMs), which plays a significant role in the etiology and progression of several human diseases. It has been regarded as a biomarker of oxidative stress due to its relatively early formation and stability compared with other oxidative PTMs. Only a subset of proteins is prone to carbonylation and most carbonyl groups are formed from lysine (K), arginine (R), threonine (T) and proline (P) residues. Recent advancements in analysis of the PTM by mass spectrometry provided new insights into the mechanisms of protein carbonylation, such as protein susceptibility and exact modification sites. However, the experimental approaches to identifying carbonylation sites are costly, time-consuming and capable of processing a limited number of proteins, and there is no bioinformatics method or tool devoted to predicting carbonylation sites of human proteins so far. In the paper, a computational method is proposed to identify carbonylation sites of human proteins. The method extracted four kinds of features and combined the minimum Redundancy Maximum Relevance (mRMR) feature selection criterion with weighted support vector machine (WSVM) to achieve total accuracies of 85.72%, 85.95%, 83.92% and 85.72% for K, R, T and P carbonylation site predictions respectively using 10-fold cross-validation. The final optimal feature sets were analysed, the position-specific composition and hydrophobicity environment of flanking residues of modification sites were discussed. In addition, a software tool named CarSPred has been developed to facilitate the application of the method. Datasets and the software involved in the paper are available at https://sourceforge.net/projects/hqlstudio/files/CarSPred-1.0/. PMID:25347395

  18. (2.2.2-Cryptand)potassium tetra­carbonyl­cobaltate(−I)

    PubMed Central

    Brennessel, William W.; Ellis, John E.

    2014-01-01

    The title salt, [K(C18H36N2O6)][Co(CO)4], is an example of a classical carbonyl­metalate. The asymmetric unit contains one cation and one tetrahedral anion, both in general positions. Based on comparison of the four carbonyl C—O bond lengths and C—Co—C angles, the anion is unperturbed by the cation, which is normal for an alkali metal fully encased by a cryptand cage. PMID:24860312

  19. Fourier Transform Vibrational Circular Dichroism Of Carbonyl Stretching Modes In N-urethanyl-a-amino acids

    NASA Astrophysics Data System (ADS)

    Chernovitz, Anita C.; Freedman, Teresa B.; Nafie, Laurence A.

    1985-12-01

    The vibrational circular dichroism (VCD) spectra of the N-t-BOC and N-CBZ-derivatives of alanine, proline, phenylalanine and valine in 0.2M CHC13 solutions all exhibit a characteristic, strong bisignate couplet in the carbonyl stretching region. The VCD couplet is interpreted in terms of the coupled oscillation of the urethane and acid carbonyl groups in an intramolecularly hydrogen-bonded structure.

  20. Carbonyl Compounds in Electronic Cigarette Vapors: Effects of Nicotine Solvent and Battery Output Voltage

    PubMed Central

    Kosmider, Leon; Sobczak, Andrzej; Fik, Maciej; Knysak, Jakub; Zaciera, Marzena; Kurek, Jolanta

    2014-01-01

    Introduction: Glycerin (VG) and propylene glycol (PG) are the most common nicotine solvents used in e-cigarettes (ECs). It has been shown that at high temperatures both VG and PG undergo decomposition to low molecular carbonyl compounds, including the carcinogens formaldehyde and acetaldehyde. The aim of this study was to evaluate how various product characteristics, including nicotine solvent and battery output voltage, affect the levels of carbonyls in EC vapor. Methods: Twelve carbonyl compounds were measured in vapors from 10 commercially available nicotine solutions and from 3 control solutions composed of pure glycerin, pure propylene glycol, or a mixture of both solvents (50:50). EC battery output voltage was gradually modified from 3.2 to 4.8V. Carbonyl compounds were determined using the HPLC/DAD method. Results: Formaldehyde and acetaldehyde were found in 8 of 13 samples. The amounts of formaldehyde and acetaldehyde in vapors from lower voltage EC were on average 13- and 807-fold lower than in tobacco smoke, respectively. The highest levels of carbonyls were observed in vapors generated from PG-based solutions. Increasing voltage from 3.2 to 4.8V resulted in a 4 to more than 200 times increase in formaldehyde, acetaldehyde, and acetone levels. The levels of formaldehyde in vapors from high-voltage device were in the range of levels reported in tobacco smoke. Conclusions: Vapors from EC contain toxic and carcinogenic carbonyl compounds. Both solvent and battery output voltage significantly affect levels of carbonyl compounds in EC vapors. High-voltage EC may expose users to high levels of carbonyl compounds. PMID:24832759

  1. Effects of low doses of quercetin and genistein on oxidation and carbonylation in hemoglobin and myoglobin.

    PubMed

    Boadi, William Y; Johnson, Damitea

    2014-09-01

    Protein-bound carbonyls have been shown to increase with age as well as in numerous diseases including rheumatoid arthritis, adult respiratory syndrome pulmonary fibrosis, diabetes, Parkinson's disease, and Alzheimer's just to mention a few. The effects of the flavonoids quercetin and genistein were investigated according to their ability to inhibit the oxidation of hemoglobin and myoglobin via the Fenton's pathway. Antioxidative activity of the flavonoids were determined by oxidizing hemoglobin and myoglobin in separate experiments with 50 μM Fe(2+) and 0.01 mM hydrogen peroxide (H2O2) with and without quercetin and/or genistein. The samples were treated singly with either quercetin, genistein, or in combination at concentrations of 1.0, 1.5, 2.0, 2.5, 3.0, and 3.5 μM, respectively, dissolved in dimethyl sulfoxide (DMSO). Samples were then incubated in a water bath at 37°C for 8, 12, and 24 hr, respectively. Levels of carbonylation were assayed by the protein carbonyl assay and the carbonyl levels quantified and expressed per mg of protein. The results indicate that protein carbonyls for samples treated with quercetin or genistein decreased in a dose-dependent manner compared to the controls. That of quercetin compared to genistein was more efficient in reducing the levels of protein carbonylation in hemoglobin and myoglobin, respectively. The combination of both flavonoids did show a gradual decrease in carbonyl compounds for only hemoglobin for all the doses and times tested. The results indicate that both flavonoids at low doses inhibited carbonylation in both hemoglobin and myoglobin and the inhibition may be attributed to the prevention of protein oxidation. PMID:25026201

  2. 1,2,3-Triazoles from carbonyl azides and alkynes: filling the gap.

    PubMed

    Haldón, Estela; Álvarez, Eleuterio; Nicasio, M Carmen; Pérez, Pedro J

    2014-08-18

    Electron deficient azides are challenging substrates in CuAAC reactions. Particularly, when N-carbonyl azides are applied the formation of N-carbonyl triazoles has not yet been observed. We report herein the first example of this class of reaction, with a copper-based system that efficiently enables the synthesis of N-carbamoyl 1,2,3-triazoles by [3+2] cycloaddition of N-carbamoyl azides and alkynes. PMID:24980244

  3. The Epoxidation of Carbonyl Compounds with a Benzyne-Triggered Sulfur Ylide.

    PubMed

    Lou, Mei-Mei; Wang, Han; Song, Li; Liu, Hong-Yi; Li, Zhong-Qiu; Guo, Xiao-Shuang; Zhang, Fu-Geng; Wang, Bin

    2016-07-15

    An efficient method for the synthesis of epoxides from carbonyl compounds, sulfoxides, and benzyne is presented. The strategy involved an epoxidation by a sulfur ylide which is formed in situ from sulfoxide and benzyne through the S-O bond insertion and deprotonation. This one-pot reaction proceeds under mild and base-free conditions, providing a convenient way to introduce the substituted methylene groups onto the carbonyl carbon. PMID:27337065

  4. Carbonyl sulfide and carbon disulfide from the eruptions of Mount St. Helens

    SciTech Connect

    Rasmussen, R.A.; Khalil, M.A.K.; Dalluge, R.W.; Penkett, S.A.; Jones, B.

    1982-01-01

    Ash from the massive 18 May 1980 eruption of Mount St. Helens readily gave off large amounts of carbonyl sulfide and carbon disulfide gases at room temperature. These findings suggest that the sulfur that enhances the Junge sulfate layer in the stratosphere after volcanic eruptions could be carried directly to the upper atmosphere as carbonyl sulfide and carbon disulfide adsorbed on ash particles from major volcanic eruptions.

  5. Carbonyl sulfide and carbon disulfide from the eruptions of mount st. Helens.

    PubMed

    Rasmussen, R A; Khalil, M A; Dalluge, R W; Penkett, S A; Jones, B

    1982-02-01

    Ash from the massive 18 May 1980 eruption of Mount St. Helens readily gave off large amounts of carbonyl sulfide and carbon disulfide gases at room temperature. These findings suggest that the sulfur that enhances the Junge sulfate layer in the stratosphere after volcanic eruptions could be carried directly to the upper atmosphere as carbonyl sulfide and carbon disulfide adsorbed on ash particles from major volcanic eruptions. PMID:17842402

  6. Proteomic analysis of carbonylated proteins in the monkey substantia nigra after ischemia-reperfusion.

    PubMed

    Oikawa, Shinji; Kobayashi, Hatasu; Kitamura, Yuki; Zhu, Hong; Obata, Kumi; Minabe, Yoshio; Dazortsava, Maryia; Ohashi, Kyoko; Tada-Oikawa, Saeko; Takahashi, Hitoshi; Yata, Kenichiro; Murata, Mariko; Yamashima, Tetsumori

    2014-06-01

    In Parkinson's disease (PD), oxidative stresses cause cell death of dopaminergic neurons of the substantia nigra (SN), but its molecular mechanism still remains unclarified. Our previous study of proteomic analysis in the monkey CA1 hippocampus after ischemia-reperfusion revealed reactive oxygen species (ROS)-induced carbonyl modification of a molecular chaperone, heat shock 70-kDa protein 1 (Hsp70.1), especially in its key site, Arg469. Here, to clarify the mechanism of neurodegeneration in PD, the SN tissue of the same monkey experimental paradigm was studied for identifying and characterizing carbonylated proteins by the two-dimensional gel electrophoresis with immunochemical detection of protein carbonyls (2D Oxyblot). We found carbonyl modification not only of Hsp70.1 but also of mitochondrial aconitase, dihydropyrimidinase-related protein 2, T-complex protein 1 subunit alpha, dihydrolipoyl dehydrogenase, fructose-bisphosphate aldolase C, glutamate dehydrogenase 1, and aspartate aminotransferase. Intriguingly, in the SN also, the carbonylation site of Hsp70.1 was identified to be Arg469. Since Hsp70.1 is recently known to stabilize the lysosomal membrane, its oxidative injury conceivably plays an important role in the ROS-mediated neuronal cell death by inducing lysosomal destabilization. Implications of each carbonylated proteins for the dopaminergic neuronal death were discussed, in comparison with the CA1 neuronal death. PMID:24697733

  7. Detection of oxidative stress-induced carbonylation in live mammalian cells.

    PubMed

    Mukherjee, Kamalika; Chio, Tak Ian; Sackett, Dan L; Bane, Susan L

    2015-07-01

    Oxidative stress is often associated with etiology and/or progression of disease conditions, such as cancer, neurodegenerative diseases, and diabetes. At the cellular level, oxidative stress induces carbonylation of biomolecules such as lipids, proteins, and DNA. The presence of carbonyl-containing biomolecules as a hallmark of these diseases provides a suitable target for diagnostic detection. Here, a simple, robust method for detecting cellular aldehydes and ketones in live cells using a fluorophore is presented. A hydrazine-functionalized synthetic fluorophore serves as an efficient nucleophile that rapidly reacts with reactive carbonyls in the cellular milieu. The product thus formed exhibits a wavelength shift in the emission maximum accompanied by an increase in emission intensity. The photochemical characteristics of the fluorophore enable the identification of the fluorophore-conjugated cellular biomolecules in the presence of unreacted dye, eliminating the need for removal of excess fluorophore. Moreover, this fluorophore is found to be nontoxic and is thus appropriate for live cell analysis. Utility of the probe is demonstrated in two cell lines, PC3 and A549. Carbonylation resulting from serum starvation and hydrogen peroxide-induced stress is detected in both cell lines using fluorescence microscopy and a fluorescence plate reader. The fluorescent signal originates from carbonylated proteins and lipids but not from oxidized DNA, and the majority of the fluorescence signal (>60%) is attributed to fluorophore-conjugated lipid oxidation products. This method should be useful for detecting cellular carbonylation in a high-content assay or high-throughput assay format. PMID:25801292

  8. Oxidative Stress and Carbonyl Lesions in Ulcerative Colitis and Associated Colorectal Cancer

    PubMed Central

    Wang, Zhiqi; Li, Sai; Cao, Yu; Tian, Xuefei; Zeng, Rong; Liao, Duan-Fang; Cao, Deliang

    2016-01-01

    Oxidative stress has long been known as a pathogenic factor of ulcerative colitis (UC) and colitis-associated colorectal cancer (CAC), but the effects of secondary carbonyl lesions receive less emphasis. In inflammatory conditions, reactive oxygen species (ROS), such as superoxide anion free radical (O2∙−), hydrogen peroxide (H2O2), and hydroxyl radical (HO∙), are produced at high levels and accumulated to cause oxidative stress (OS). In oxidative status, accumulated ROS can cause protein dysfunction and DNA damage, leading to gene mutations and cell death. Accumulated ROS could also act as chemical messengers to activate signaling pathways, such as NF-κB and p38 MAPK, to affect cell proliferation, differentiation, and apoptosis. More importantly, electrophilic carbonyl compounds produced by lipid peroxidation may function as secondary pathogenic factors, causing further protein and membrane lesions. This may in turn exaggerate oxidative stress, forming a vicious cycle. Electrophilic carbonyls could also cause DNA mutations and breaks, driving malignant progression of UC. The secondary lesions caused by carbonyl compounds may be exceptionally important in the case of host carbonyl defensive system deficit, such as aldo-keto reductase 1B10 deficiency. This review article updates the current understanding of oxidative stress and carbonyl lesions in the development and progression of UC and CAC. PMID:26823956

  9. Direct photolysis of carbonyl compounds dissolved in cloud and fog droplets

    NASA Astrophysics Data System (ADS)

    Epstein, S. A.; Tapavicza, E.; Furche, F.; Nizkorodov, S. A.

    2013-04-01

    Gas phase photolysis is an important tropospheric sink for many carbonyl compounds, however the significance of direct photolysis of carbonyl compounds dissolved in cloud and fog droplets is uncertain. We develop a theoretical approach to assess the importance of aqueous photolysis for a series of carbonyls that possess carboxyl and hydroxyl functional groups by comparison with rates of other atmospheric processes. We use computationally and experimentally derived Henry's law parameters, hydration equilibrium parameters, aqueous hydroxyl radical (OH) rate constants, and optical extinction coefficients to identify types of compounds that will not have competitive aqueous photolysis rates. We also present molecular dynamics simulations of atmospherically relevant carbonyl compounds designed to estimate gas and aqueous phase extinction coefficients. In addition, experiments designed to measure the photolysis rate of glyceraldehyde, an atmospherically relevant water soluble organic compound, reveal that aqueous quantum yields are highly molecule-specific and cannot be extrapolated from measurements of structurally similar compounds. We find that only three out of the 92 carbonyl compounds investigated, pyruvic acid, 3-oxobutanoic acid, and 3-oxopropanoic acid, may have aqueous photolysis rates that exceed the rate of oxidation by dissolved OH. For almost all carbonyl compounds lacking α, β conjugation, atmospheric removal by direct photolysis in cloud and fog droplets can be neglected.

  10. Characteristics of carbonyl compounds in public vehicles of Beijing city: Concentrations, sources, and personal exposures

    NASA Astrophysics Data System (ADS)

    Pang, Xiaobing; Mu, Yujing

    The characteristics of carbonyl compounds (carbonyls) including concentrations, major sources, and personal exposure were investigated for 29 vehicles including taxi, bus and subway in Beijing. It was found that the taxis (Xiali, TA) and buses (Huanghe, BA) fueled by gasoline with longer service years had the higher indoor carbonyl levels (178±42.7 and 188±31.6 μg m -3) while subways energized by electricity without exhaust and the jingwa buses (BB) driven in the suburb had the lower levels with total concentrations of 98.5±26.3 and 92.1±20.3 μg m -3, respectively. Outdoor carbonyls of taxi cars and buses were nearly at the same level with their total concentrations varying from 80 to 110 μg m -3. The level of outdoor subways carbonyls was equal with the ambient air levels. Exhaust leakage, indoor material emissions, photochemical formation, and infiltration of outdoor air were considered to be the major sources to in-vehicle carbonyls. Personal exposures and cancer risk to formaldehyde and acetaldehyde were calculated for professional bus and taxi drivers, respectively. Taxi drivers had the highest cancer risk with personal exposure to formaldehyde and acetaldehyde of 212 and 243 μg day -1, respectively. The public concern should pay considerable attention to professional drivers' health.

  11. A new agent for derivatizing carbonyl species used to investigate limonene ozonolysis

    NASA Astrophysics Data System (ADS)

    Wells, J. R.; Ham, Jason E.

    2014-12-01

    A new method for derivatizing carbonyl compounds is presented. The conversion of a series of dicarbonyls to oximes in aqueous solution and from gas-phase sampling was achieved using O-tert-butylhydroxylamine hydrochloride (TBOX). Some advantages of using this derivatization agent include: aqueous reactions, lower molecular weight oximes, and shortened oxime-formation reaction time. Additionally, the TBOX derivatization technique was used to investigate the carbonyl reaction products from limonene ozonolysis. With ozone (O3) as the limiting reagent, four carbonyl compounds were detected: 7-hydroxy-6-oxo-3-(prop-1-en-2-yl)heptanal; 3-Isopropenyl-6-oxoheptanal (IPOH), 3-acetyl-6-oxoheptanal (3A6O) and one carbonyl of unknown structure. Using cyclohexane as a hydroxyl (OHrad) radical scavenger, the relative yields (peak area) of the unknown carbonyl, IPOH, and 3A6O were reduced indicating the influence secondary OH radicals have on limonene ozonolysis products. The relative yield of the hydroxy-dicarbonyl based on the chromatogram was unchanged suggesting it is only made by the limonene + O3 reaction. The detection of 3A6O using TBOX highlights the advantages of a smaller molecular weight derivatization agent for the detection of multi-carbonyl compounds. The use of TBOX derivatization if combined with other derivatization agents may address a recurring need to simply and accurately detect multi-functional oxygenated species in air.

  12. Protein carbonylation associated to high-fat, high-sucrose diet and its metabolic effects.

    PubMed

    Méndez, Lucía; Pazos, Manuel; Molinar-Toribio, Eunice; Sánchez-Martos, Vanesa; Gallardo, José M; Rosa Nogués, M; Torres, Josep L; Medina, Isabel

    2014-12-01

    The present research draws a map of the characteristic carbonylation of proteins in rats fed high-caloric diets with the aim of providing a new insight of the pathogenesis of metabolic diseases derived from the high consumption of fat and refined carbohydrates. Protein carbonylation was analyzed in plasma, liver and skeletal muscle of Sprague-Dawley rats fed a high-fat, high-sucrose (HFHS) diet by a proteomics approach based on carbonyl-specific fluorescence-labeling, gel electrophoresis and mass spectrometry. Oxidized proteins along with specific sites of oxidative damage were identified and discussed to illustrate the consequences of protein oxidation. The results indicated that long-term HFHS consumption increased protein oxidation in plasma and liver; meanwhile, protein carbonyls from skeletal muscle did not change. The increment of carbonylation by HFHS diet was singularly selective on specific target proteins: albumin from plasma and liver, and hepatic proteins such as mitochondrial carbamoyl-phosphate synthase (ammonia), mitochondrial aldehyde dehydrogenase, argininosuccinate synthetase, regucalcin, mitochondrial adenosine triphosphate synthase subunit beta, actin cytoplasmic 1 and mitochondrial glutamate dehydrogenase 1. The possible consequences that these specific protein carbonylations have on the excessive weight gain, insulin resistance and nonalcoholic fatty liver disease resulting from HFHS diet consumption are discussed. PMID:25282656

  13. In vivo targeted gene delivery to peripheral neurons mediated by neurotropic poly(ethylene imine)-based nanoparticles.

    PubMed

    Lopes, Cátia Df; Oliveira, Hugo; Estevão, Inês; Pires, Liliana Raquel; Pêgo, Ana Paula

    2016-01-01

    A major challenge in neuronal gene therapy is to achieve safe, efficient, and minimally invasive transgene delivery to neurons. In this study, we report the use of a nonviral neurotropic poly(ethylene imine)-based nanoparticle that is capable of mediating neuron-specific transfection upon a subcutaneous injection. Nanoparticles were targeted to peripheral neurons by using the nontoxic carboxylic fragment of tetanus toxin (HC), which, besides being neurotropic, is capable of being retrogradely transported from neuron terminals to the cell bodies. Nontargeted particles and naked plasmid DNA were used as control. Five days after treatment by subcutaneous injection in the footpad of Wistar rats, it was observed that 56% and 64% of L4 and L5 dorsal root ganglia neurons, respectively, were expressing the reporter protein. The delivery mediated by HC-functionalized nanoparticles spatially limited the transgene expression, in comparison with the controls. Histological examination revealed no significant adverse effects in the use of the proposed delivery system. These findings demonstrate the feasibility and safety of the developed neurotropic nanoparticles for the minimally invasive delivery of genes to the peripheral nervous system, opening new avenues for the application of gene therapy strategies in the treatment of peripheral neuropathies. PMID:27354797

  14. Microwave assisted synthesis, spectroscopic, electrochemical and DNA cleavage studies of lanthanide(III) complexes with coumarin based imines

    NASA Astrophysics Data System (ADS)

    Kapoor, Puja; Fahmi, Nighat; Singh, R. V.

    2011-12-01

    The present work stems from our interest in the synthesis, characterization and biological evaluation of lanthanide(III) complexes of a class of coumarin based imines which have been prepared by the interaction of hydrated lanthanide(III) chloride with the sodium salts of 3-acetylcoumarin thiosemicarbazone (ACTSZH) and 3-acetylcoumarin semicarbazone (ACSZH) in 1:3 molar ratio using thermal as well as microwave method. Characterization of the ligands as well as the metal complexes have been carried out by elemental analysis, melting point determinations, molecular weight determinations, magnetic moment, molar conductance, IR, 1H NMR, 13C NMR, electronic, EPR, X-ray powder diffraction and mass spectral studies. Spectral studies confirm ligands to be monofunctional bidentate and octahedral environment around metal ions. The redox behavior of one of the synthesized metal complex was investigated by cyclic voltammetry. Further, free ligands and their metal complexes have been screened for their antimicrobial as well as DNA cleavage activity. The results of these findings have been presented and discussed.

  15. In vivo targeted gene delivery to peripheral neurons mediated by neurotropic poly(ethylene imine)-based nanoparticles

    PubMed Central

    Lopes, Cátia DF; Oliveira, Hugo; Estevão, Inês; Pires, Liliana Raquel; Pêgo, Ana Paula

    2016-01-01

    A major challenge in neuronal gene therapy is to achieve safe, efficient, and minimally invasive transgene delivery to neurons. In this study, we report the use of a nonviral neurotropic poly(ethylene imine)-based nanoparticle that is capable of mediating neuron-specific transfection upon a subcutaneous injection. Nanoparticles were targeted to peripheral neurons by using the nontoxic carboxylic fragment of tetanus toxin (HC), which, besides being neurotropic, is capable of being retrogradely transported from neuron terminals to the cell bodies. Nontargeted particles and naked plasmid DNA were used as control. Five days after treatment by subcutaneous injection in the footpad of Wistar rats, it was observed that 56% and 64% of L4 and L5 dorsal root ganglia neurons, respectively, were expressing the reporter protein. The delivery mediated by HC-functionalized nanoparticles spatially limited the transgene expression, in comparison with the controls. Histological examination revealed no significant adverse effects in the use of the proposed delivery system. These findings demonstrate the feasibility and safety of the developed neurotropic nanoparticles for the minimally invasive delivery of genes to the peripheral nervous system, opening new avenues for the application of gene therapy strategies in the treatment of peripheral neuropathies. PMID:27354797

  16. Structural dependence of in vitro cytotoxicity, oxidative stress and uptake mechanisms of poly(propylene imine) dendritic nanoparticles.

    PubMed

    Khalid, Humza; Mukherjee, Sourav Prasanna; O'Neill, Luke; Byrne, Hugh J

    2016-03-01

    The in vitro cytotoxic and intracellular oxidative stress responses to exposure to poly(propylene imine) (PPI) dendritic nanoparticles of increasing generation (number of repeated branching cycles) (G0-G4) were assessed in an immortal non-cancerous human keratinocyte cell line (HaCaT). Confocal fluorescence microscopy with organelle staining was used to explore the uptake and intracellular trafficking mechanisms. A generation- and dose-dependent cytotoxic response was observed, increasing according to generation and, therefore, number of surface amino groups. A comparison of the cytotoxic response of G4 PPI and the related G4 poly(amido amine) dendrimer indicates that the PPI with the same number of surface amino groups elicits a significantly higher cytotoxic response. The trend of cytotoxicity versus dendrimer generation and, therefore, size is discontinuous in the region of G2, however, indicating a difference in uptake mechanism for higher compared to lower generations. Whereas the higher generations elicit an oxidative stress response at short exposure times, the lower generations indicate an antioxidant response. Confocal microscopy indicates that, whereas they are prominent at early exposure times for the larger PPI dendrimers, no evidence of early stage endosomes was observed for lower generations of PPI. The results are consistent with an alternative uptake mechanism of physical diffusion across the semipermeable cell membrane for the lower generation dendrimers and are discussed in terms of their implications for predictive models for nanotoxicology and design strategies for nanomedical applications. PMID:26671548

  17. Characterization of oligosaccharide-functionalized hyperbranched poly(ethylene imine) and their complexes with retinol in aqueous solution.

    PubMed

    Bekhradnia, Sara; Naz, Iram; Lund, Reidar; Effenberg, Christiane; Appelhans, Dietmar; Sande, Sverre Arne; Nyström, Bo

    2015-11-15

    Structure, internal density distribution, and size of hyperbranched poly(ethylene imine) (PEI) functionalized with various amounts of maltose (PEI-Mal) in phosphate buffer were studied by small angle X-ray scattering (SAXS) and dynamic light scattering (DLS). The value of pH was varied in the range from 3 to 9. Virtually no effect of pH on the nanostructure was found in this interval. The SAXS results revealed a broad segmental radial density distribution, i.e. a "fluffy" globular structure rather than a distinct core-shell structure with a high-density compact core and a low-density corona. This suggests that the maltose units are rather evenly distributed both in the interior and on the surface of the species with a PEI-core of molar mass of 25,000g/mol. The DLS measurements showed that the overall size of the PEI-Mal derivatives increased as the number of maltose units in the PEI-Mal structures rises. The interaction of the hydrophobic model drug retinol with PEI or PEI-Mal derivatives was also investigated. The UV-visible spectroscopy results disclosed that the solubility of retinol in the phosphate buffer is very poor and it takes a very long time to solubilize retinol. Moreover, retinol induces aggregation of dendritic glycopolymers where the growth of aggregates occurs continuously over several days and then remains virtually constant. PMID:26218197

  18. Oral delivery of insulin via polyethylene imine-based nanoparticles for colonic release allows glycemic control in diabetic rats.

    PubMed

    Salvioni, Lucia; Fiandra, Luisa; Del Curto, Maria Dorly; Mazzucchelli, Serena; Allevi, Raffaele; Truffi, Marta; Sorrentino, Luca; Santini, Benedetta; Cerea, Matteo; Palugan, Luca; Corsi, Fabio; Colombo, Miriam

    2016-08-01

    In this study, insulin-containing nanoparticles were loaded into pellet cores and orally administered to diabetic rats. Polyethylene imine-based nanoparticles, either placebo or loaded with insulin, were incorporated by extrusion and spheronization technology into cores that were subsequently coated with three overlapping layers and a gastroresistant film. The starting and coated systems were evaluated in vitro for their physico-technololgical characteristics, as well as disintegration and release performance. Nanoparticles-loaded cores showed homogeneous particle size distribution and shape. When a superdisintegrant and a soluble diluent were included in the composition enhanced disintegration and release performance were observed. The selected formulations, coated either with enteric or three-layer films, showed gastroresistant and release delayed behavior in vitro, respectively. The most promising formulations were finally tested for their hypoglycemic effect in diabetic rats. Only the nanoformulations loaded into the three-layer pellets were able to induce a significant hypoglycemic activity in diabetic rats. Our results suggest that this efficient activity could be attributed to a retarded release of insulin into the distal intestine, characterized by relatively low proteolytic activity and optimal absorption. PMID:27181095

  19. Mercury(II) ion-selective electrodes based on p-tert-butyl calix[4]crowns with imine units.

    PubMed

    Mahajan, Rakesh Kumar; Kaur, Ravneet; Kaur, Inderpreet; Sharma, Vandana; Kumar, Manoj

    2004-05-01

    A PVC membrane incorporating p-tert-butyl calix[4]crown with imine units as an ionophore was prepared and used in an ion-selective electrode for the determination of mercury(II) ions. An electrode based on this ionophore showed a good potentiometric response for mercury(II) ions over a wide concentration range of 5.0 x 10(-5) - 1.0 x 10(-1) M with a near-Nernstian slope of 27.3 mV per decade. The detection limit of the electrode was 2.24 x 10(-5) M and the electrode worked well in the pH range of 1.3 - 4.0. The electrode showed a short response time of less than 20 s. The electrode also showed better selectivity for mercury(II) ions over many of the alkali (Na+, -1.69; K+, -1.54), alkaline-earth (Ca2+, -3.30; Ba2+, -3.32), and heavy metal ions (Co2+, -3.67; Ni2+, -3.43; Pb2+, -3.31; Fe3+, -1.82). Ag+ ion was found to be the strongest interfering ion. Also, sharp end points were obtained when the sensor was used as an indicator electrode for the potentiometric titration of mercury(II) ions with iodide and dichromate ions. PMID:15171285

  20. Modification of poly(L-lactic acid) electrospun fibers and films with poly(propylene imine) dendrimer

    NASA Astrophysics Data System (ADS)

    Khaliliazar, Sh.; Akbari, S.; Kish, M. H.

    2016-02-01

    Poly(L-lactic acid) (PLLA) electrospun fibers and films were modified with the second generation of poly(propylene imine) dendrimer (PPI-G2) by three different approaches, namely, sodium hydroxide hydrolysis, plasma treatment and direct application of PPI-G2. For the first and the second approaches, PLLA was modified by sodium hydroxide hydrolysis or plasma treatment to produce carboxylic acid groups. Then, the carboxylic acid groups were activated by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDAC) and N,N‧-dicyclohexyl carbodiimide (DCC) as a hetero bi-functional cross-linker. The cross-linkers promoted the grafting of carboxylic acid groups on the modified PLLA with NH2 groups of PPI-G2. In the third approach, the PPI-G2 dendrimer was directly used as an aminolysis agent for the functionalization of PLLA in a one step process. FTIR analysis confirmed the presence of sbnd NH2 groups of PPI-G2 on the modified PLLA samples, resulting from each one of the three modification methods. Studies by SEM shows bead free electrospun fibers. Also, FE-SEM shows nano-cracks on the surface of films after modification. Contact angle, drug release tests, antibacterial effects and the dying results confirmed that these functionalization methods increased hydrophilicity and reactive side-chains of PLLA in the wet chemical process resulted in providing host-guest properties on the PLLA surface for adsorbing various kinds of guest molecules.

  1. Syntheses and Properties of Homoleptic Carbonyl and Trifluorophosphane Niobates: [Nb(CO)(6)](-), [Nb(PF(3))(6)](-) and [Nb(CO)(5)](3)(-) (,)(1).

    PubMed

    Barybin, Mikhail V.; Ellis, John E.; Pomije, Marie K.; Tinkham, Mary L.; Warnock, Garry F.

    1998-12-14

    Reductive carbonylations of NbCl(4)(THF)(2), THF = tetrahydrofuran, mediated by sodium naphthalene in 1,2-dimethoxyethane, DME, or sodium anthracene in THF, provide [Nb(CO)(6)](-) as the tetraethylammonium salt in 60% or 70% isolated yields, respectively, the highest known for atmospheric pressure syntheses of this metal carbonyl. Corresponding reductions involving PF(3) give about 40% yields of [Et(4)N][Nb(PF(3))(6)], which in the past was only accessible by a photochemical route. Electrochemical data for [Nb(CO)(6)](-) and [Nb(PF(3))(6)](-) are compared and show that the PF(3) complex is almost 1 V more difficult to oxidize than the CO analogue. Protonation of [Nb(PF(3))(6)](-) by concentrated sulfuric acid yields a volatile, thermally unstable species, which has been shown by (1)H NMR and mass spectral studies to be the new niobium hydride, Nb(PF(3))(6)H. Previously unpublished (93)Nb and (13)C NMR studies corroborate prior claims that the sodium metal reduction of [Nb(CO)(6)](-) in liquid ammonia affords [Nb(CO)(5)](3)(-), the only known Nb(III-) species. The first details of this synthesis and those of [Nb(CO)(5)H](2)(-), [Nb(CO)(5)SnPh(3)](2)(-), [Nb(CO)(5)NH(3)](-), and [Nb(CO)(5)(CNtBu)](-) are presented. PMID:11670773

  2. Protein carbonylation, protein aggregation and neuronal cell death in a murine model of multiple sclerosis

    NASA Astrophysics Data System (ADS)

    Dasgupta, Anushka

    Many studies have suggested that oxidative stress plays an important role in the pathophysiology of both multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE). Yet, the mechanism by which oxidative stress leads to tissue damage in these disorders is unclear. Recent work from our laboratory has revealed that protein carbonylation, a major oxidative modification caused by severe and/or chronic oxidative stress conditions, is elevated in MS and EAE. Furthermore, protein carbonylation has been shown to alter protein structure leading to misfolding/aggregation. These findings prompted me to hypothesize that carbonylated proteins, formed as a consequence of oxidative stress and/or decreased proteasomal activity, promote protein aggregation to mediate neuronal apoptosis in vitro and in EAE. To test this novel hypothesis, I first characterized protein carbonylation, protein aggregation and apoptosis along the spinal cord during the course of myelin-oligodendrocyte glycoprotein (MOG)35-55 peptide-induced EAE in C57BL/6 mice [Chapter 2]. The results show that carbonylated proteins accumulate throughout the course of the disease, albeit by different mechanisms: increased oxidative stress in acute EAE and decreased proteasomal activity in chronic EAE. I discovered not only that there is a temporal correlation between protein carbonylation and apoptosis but also that carbonyl levels are significantly higher in apoptotic cells. A high number of juxta-nuclear and cytoplasmic protein aggregates containing the majority of the oxidized proteins are also present during the course of EAE, which seems to be due to reduced autophagy. In chapter 3, I show that when gluthathione levels are reduced to those in EAE spinal cord, both neuron-like PC12 (nPC12) cells and primary neuronal cultures accumulate carbonylated proteins and undergo cell death (both by necrosis and apoptosis). Immunocytochemical and biochemical studies also revealed a temporal

  3. Mesoporous Silica-Supported Amidozirconium-Catalyzed Carbonyl Hydroboration

    DOE PAGESBeta

    Eedugurala, Naresh; Wang, Zhuoran; Chaudhary, Umesh; Nelson, Nicholas; Kandel, Kapil; Kobayashi, Takeshi; Slowing, Igor I.; Pruski, Marek; Sadow, Aaron D.

    2015-11-04

    The hydroboration of aldehydes and ketones using a silica-supported zirconium catalyst is reported. Reaction of Zr(NMe2)4 and mesoporous silica nanoparticles (MSN) provides the catalytic material Zr(NMe2)n@MSN. Exhaustive characterization of Zr(NMe2)n@MSN with solid-state (SS)NMR and infrared spectroscopy, as well as through reactivity studies, suggests its surface structure is primarily ≡SiOZr(NMe2)3. The presence of these nitrogen-containing zirconium sites is supported by 15N NMR spectroscopy, including natural abundance 15N NMR measurements using dynamic nuclear polarization (DNP) SSNMR. The Zr(NMe2)n@MSN material reacts with pinacolborane (HBpin) to provide Me2NBpin and the material ZrH/Bpin@MSN that is composed of interacting surface-bonded zirconium hydride and surface-bonded borane ≡SiOBpinmore » moieties in an approximately 1:1 ratio, as well as zirconium sites coordinated by dimethylamine. The ZrH/Bpin@MSN is characterized by 1H/2H and 11B SSNMR and infrared spectroscopy and through its reactivity with D2. The zirconium hydride material or the zirconium amide precursor Zr(NMe2)n@MSN catalyzes the selective hydroboration of aldehydes and ketones with HBpin in the presence of functional groups that are often reduced under hydroboration conditions or are sensitive to metal hydrides, including olefins, alkynes, nitro groups, halides, and ethers. Remarkably, this catalytic material may be recycled without loss of activity at least eight times, and air-exposed materials are catalytically active. These supported zirconium centers are robust catalytic sites for carbonyl reduction and that surface-supported, catalytically reactive zirconium hydride may be generated from zirconium-amide or zirconium alkoxide sites.« less

  4. Intramolecular hydrogen bond in biologically active o-carbonyl hydroquinones.

    PubMed

    Martínez-Cifuentes, Maximiliano; Weiss-López, Boris E; Santos, Leonardo S; Araya-Maturana, Ramiro

    2014-01-01

    Intramolecular hydrogen bonds (IHBs) play a central role in the molecular structure, chemical reactivity and interactions of biologically active molecules. Here, we study the IHBs of seven related o-carbonyl hydroquinones and one structurally-related aromatic lactone, some of which have shown anticancer and antioxidant activity. Experimental NMR data were correlated with theoretical calculations at the DFT and ab initio levels. Natural bond orbital (NBO) and molecular electrostatic potential (MEP) calculations were used to study the electronic characteristics of these IHB. As expected, our results show that NBO calculations are better than MEP to describe the strength of the IHBs. NBO energies (∆Eij(2)) show that the main contributions to energy stabilization correspond to LP-->σ* interactions for IHBs, O1…O2-H2 and the delocalization LP-->π* for O2-C2=Cα(β). For the O1…O2-H2 interaction, the values of ∆Eij(2) can be attributed to the difference in the overlap ability between orbitals i and j (Fij), instead of the energy difference between them. The large energy for the LP O2-->π* C2=Cα(β) interaction in the compounds 9-Hydroxy-5-oxo-4,8, 8-trimethyl-l,9(8H)-anthracenecarbolactone (VIII) and 9,10-dihydroxy-4,4-dimethylanthracen-1(4H)-one (VII) (55.49 and 60.70 kcal/mol, respectively) when compared with the remaining molecules (all less than 50 kcal/mol), suggests that the IHBs in VIII and VII are strongly resonance assisted. PMID:24995921

  5. Soil fluxes of carbonyl sulfide (COS) across four distinct ecosystems

    NASA Astrophysics Data System (ADS)

    Sun, W.; Maseyk, K. S.; Lett, C.; Juarez, S.; Kooijmans, L.; Mammarella, I.; Vesala, T.; Chen, H.; Seibt, U.

    2015-12-01

    Soils are additional but poorly resolved sinks of carbonyl sulfide (COS) in terrestrial ecosystems. COS has been proposed as a tracer for quantifying gross photosynthesis based on the coupled stomatal uptake of COS and CO2. But applying this tracer requires the soil COS flux to be subtracted from the ecosystem flux to obtain the actual plant flux. To simulate soil COS fluxes, we have built a 1-D diffusion-reaction model accounting for vertical transport in the soil, microbial sinks and sources, and a litter layer. Uptake and production of COS in the soil column are linked with soil temperature and moisture through empirical functions adapted from enzyme kinetics and lab incubations. We have measured soil COS fluxes and the related soil variables in four distinct ecosystems: a wheat field (Southern Great Plains, OK, USA), an oak woodland (Santa Monica Mountains, CA, USA), a tropical rainforest (La Selva Biological Station, Costa Rica) and a boreal pine forest (Hyytiälä, Finland). Across all sites, a lower soil temperature and a humid climate are generally favorable to soil COS uptake. Strong COS emissions were observed in the wheat field at high soil temperatures after harvesting but were absent in other ecosystems, indicating that COS exchange may behave differently in agricultural soils. We simulated the soil fluxes in all ecosystems using the diffusion-reaction model, and optimized the source/sink strength parameters with field data. The optimized model provides insights that are not attainable from data analysis alone: For example, the wheat field soil must have continued uptake activity even when it showed net emissions, and leaf litter contributed dominantly to the COS sink after rain in the oak woodland. We expect the new model to be useful for simulating global soil COS fluxes as field data on soil fluxes from a broader range of ecosystems become available.

  6. New Ir Bis-Carbonyl Precursor for Water Oxidation Catalysis.

    PubMed

    Huang, Daria L; Beltrán-Suito, Rodrigo; Thomsen, Julianne M; Hashmi, Sara M; Materna, Kelly L; Sheehan, Stafford W; Mercado, Brandon Q; Brudvig, Gary W; Crabtree, Robert H

    2016-03-01

    This paper introduces Ir(I)(CO)2(pyalc) (pyalc = (2-pyridyl)-2-propanoate) as an atom-efficient precursor for Ir-based homogeneous oxidation catalysis. This compound was chosen to simplify analysis of the water oxidation catalyst species formed by the previously reported Cp*Ir(III)(pyalc)OH water oxidation precatalyst. Here, we present a comparative study on the chemical and catalytic properties of these two precursors. Previous studies show that oxidative activation of Cp*Ir-based precursors with NaIO4 results in formation of a blue Ir(IV) species. This activation is concomitant with the loss of the placeholder Cp* ligand which oxidatively degrades to form acetic acid, iodate, and other obligatory byproducts. The activation process requires substantial amounts of primary oxidant, and the degradation products complicate analysis of the resulting Ir(IV) species. The species formed from oxidation of the Ir(CO)2(pyalc) precursor, on the other hand, lacks these degradation products (the CO ligands are easily lost upon oxidation) which allows for more detailed examination of the resulting Ir(pyalc) active species both catalytically and spectroscopically, although complete structural analysis is still elusive. Once Ir(CO)2(pyalc) is activated, the system requires acetic acid or acetate to prevent the formation of nanoparticles. Investigation of the activated bis-carbonyl complex also suggests several Ir(pyalc) isomers may exist in solution. By (1)H NMR, activated Ir(CO)2(pyalc) has fewer isomers than activated Cp*Ir complexes, allowing for advanced characterization. Future research in this direction is expected to contribute to a better structural understanding of the active species. A diol crystallization agent was needed for the structure determination of 3. PMID:26901517

  7. Environmental variables controlling the uptake of carbonyl sulfide by lichens

    NASA Astrophysics Data System (ADS)

    Kuhn, U.; Kesselmeier, J.

    2000-11-01

    The uptake of atmospheric carbonyl sulfide (COS) by the lichen species Ramalina menziesii, representative for the open oak woodland in central California, was studied under laboratory conditions. By use of a dynamic cuvette system, the controlling parameters for the COS uptake were investigated under climate chamber conditions. The thallus water content, essential for the overall physiology of lichens, was found to be of basic importance for the trace gas exchange. A water content of 30% was the approximate minimum for COS uptake, with increasing activity up to a water content of 200%. Additionally, actual atmospheric mixing ratios have a significant influence on the exchange. The COS uptake was found to be a linear function of the ambient COS mixing ratio resulting in a compensation point as low as 37 ppt. A temperature optimum of 25°C was indicative of a physiological basis of the COS uptake. The inhibition of the COS consumption in the presence of a specific inhibitor for the enzyme carbonic anhydrase proved this enzyme to be of key relevance for the uptake. All these variables controlling the COS deposition were integrated into an uptake algorithm to model the exchange behavior of this lichen. The applicability of the model to field data is demonstrated. Uptake rates on a dry weight basis normalized to optimized conditions (25°C; 450 ppt COS) reached 0.17±0.09 pmol g-1 s-1 (i.e. 4.2±2.2 pmol m-2 s-1 thallus surface area, respectively). The contribution of lichens to the global COS sink strength is assigned to be about 0.3 Tg a-1, representing not a major but a significant sink.

  8. From allylic alcohols to aldols by using iron carbonyls as catalysts: computational study on a novel tandem isomerization-aldolization reaction.

    PubMed

    Branchadell, Vicenç; Crévisy, Christophe; Grée, René

    2004-11-01

    The tandem isomerization-aldolization reaction between allyl alcohol and formaldehyde mediated by [Fe(CO)3] was studied with the density functional B3LYP method. Starting from the key [(enol)Fe(CO)3] complex, several reaction paths for the reaction with formaldehyde were explored. The results show that the most favorable reaction path involves first an enol/allyl alcohol ligand-exchange process followed by direct condensation of formaldehyde with the free enol. During this process, formation of the new C-C bond takes place simultaneously with a proton transfer between the enol and the aldehyde. Therefore, the role of [Fe(CO)3] is to catalyze the allyl alcohol to enol isomerization affording the free enol, which adds to the aldehyde in a carbonyl-ene type reaction. Similar results were obtained for the reaction between allyl alcohol and acetaldehyde. PMID:15472940

  9. Photoinduced proton transfer promoted by peripheral subunits for some Hantzsch esters.

    PubMed

    Azizi, Sébastien; Ulrich, Gilles; Guglielmino, Maud; le Calvé, Stéphane; Hagon, Jerry P; Harriman, Anthony; Ziessel, Raymond

    2015-01-01

    It is noted that, for a small series of 3,5-diacetyl-1,4-dihydrolutidine (DDL) derivatives and the corresponding Hantzsch esters, the presence of methyl groups at the 2,6-positions serves to extinguish fluorescence in solution but not in the solid state. Emission is weakly activated and affected by changes in solvent polarity. The latter situation arises because the optical transition involves intramolecular charge transfer. Calculations, both semiempirical and DFT, indicate that, in all cases, rotation of the carbonyl function is facile and that the dihydropyridine ring is planar. These calculations also indicate that the 2,6-methyl groups do not affect the generic structure of the molecule. It is proposed that illumination increases the molecular dipole moment and pushes electron density toward the carbonyl oxygen atom. Proton transfer can now occur from one of the methyl groups, leading to formation of a relatively low-energy, neutral intermediate, followed by a second proton transfer step that forms the enol. Reaction profiles computed for the ground-state species indicate that this route is highly favored relative to hydrogen transfer from the 4-position. The barriers for light-induced proton transfer are greatly reduced relative to the ground-state process but such large-scale structural transformations are hindered in the solid state. A rigid analogue that cannot form an enol is highly emissive in solution, supporting the conclusion that proton transfer is in competition to fluorescence in solution. PMID:25474121

  10. Proteomic identification of carbonylated proteins in F344 rat hippocampus after 1-bromopropane exposure

    SciTech Connect

    Huang, Zhenlie; Ichihara, Sahoko; Oikawa, Shinji; Chang, Jie; Zhang, Lingyi; Subramanian, Kaviarasan; Mohideen, Sahabudeen Sheik; Ichihara, Gaku

    2012-08-15

    1-Bromopropane (1-BP) is neurotoxic in both experimental animals and humans. Previous proteomic analysis of rat hippocampus implicated alteration of protein expression in oxidative stress, suggesting that oxidative stress plays a role in 1-BP-induced neurotoxicity. To understand this role at the protein level, we exposed male F344 rats to 1-BP at 0, 400, or 1000 ppm for 8 h/day for 1 week or 4 weeks by inhalation and quantitated changes in hippocampal protein carbonyl using a protein carbonyl assay, two-dimensional gel electrophoresis (2-DE), immunoblotting, and matrix-assisted laser-desorption ionization time-of-flight mass spectrometry (MALDI-TOF-TOF/MS). Hippocampal reactive oxygen species and protein carbonyl were significantly increased, demonstrating 1-BP-associated induction of oxidative stress and protein damage. MALDI-TOF-TOF/MS identified 10 individual proteins with increased carbonyl modification (p < 0.05; fold-change ≥ 1.5). The identified proteins were involved in diverse biological processes including glycolysis, ATP production, tyrosine catabolism, GTP binding, guanine degradation, and neuronal metabolism of dopamine. Hippocampal triosephosphate isomerase (TPI) activity was significantly reduced and negatively correlated with TPI carbonylation (p < 0.001; r = 0.83). Advanced glycation end-product (AGE) levels were significantly elevated both in the hippocampus and plasma, and hippocampal AGEs correlated negatively with TPI activity (p < 0.001; r = 0.71). In conclusion, 1-BP-induced neurotoxicity in the rat hippocampus seems to involve oxidative damage of cellular proteins, decreased TPI activity, and elevated AGEs. -- Highlights: ► 1-BP increases hippocampal ROS levels and hippocampal and plasma protein carbonyls. ► 1-BP increases TPI carbonylation and decreases TPI activity in the hippocampus. ► 1-BP increases hippocampal and plasma AGE levels.

  11. Ferrous Carbonyl Dithiolates as Precursors to FeFe, FeCo, and FeMn Carbonyl Dithiolates

    PubMed Central

    2015-01-01

    Reported are complexes of the formula Fe(dithiolate)(CO)2(diphos) and their use to prepare homo- and heterobimetallic dithiolato derivatives. The starting iron dithiolates were prepared by a one-pot reaction of FeCl2 and CO with chelating diphosphines and dithiolates, where dithiolate = S2(CH2)22– (edt2–), S2(CH2)32– (pdt2–), S2(CH2)2(C(CH3)2)2– (Me2pdt2–) and diphos = cis-C2H2(PPh2)2 (dppv), C2H4(PPh2)2 (dppe), C6H4(PPh2)2 (dppbz), C2H4[P(C6H11)2]2 (dcpe). The incorporation of 57Fe into such building block complexes commenced with the conversion of 57Fe into 57Fe2I4(iPrOH)4, which then was treated with K2pdt, CO, and dppe to give 57Fe(pdt)(CO)2(dppe). NMR and IR analyses show that these complexes exist as mixtures of all-cis and trans-CO isomers, edt2– favoring the former and pdt2– the latter. Treatment of Fe(dithiolate)(CO)2(diphos) with the Fe(0) reagent (benzylideneacetone)Fe(CO)3 gave Fe2(dithiolate)(CO)4(diphos), thereby defining a route from simple ferrous salts to models for hydrogenase active sites. Extending the building block route to heterobimetallic complexes, treatment of Fe(pdt)(CO)2(dppe) with [(acenaphthene)Mn(CO)3]+ gave [(CO)3Mn(pdt)Fe(CO)2(dppe)]+ ([3d(CO)]+). Reduction of [3d(CO)]+ with BH4– gave the Cs-symmetric μ-hydride (CO)3Mn(pdt)(H)Fe(CO)(dppe) (H3d). Complex H3d is reversibly protonated by strong acids, the proposed site of protonation being sulfur. Treatment of Fe(dithiolate)(CO)2(diphos) with CpCoI2(CO) followed by reduction by Cp2Co affords CpCo(dithiolate)Fe(CO)(diphos) (4), which can also be prepared from Fe(dithiolate)(CO)2(diphos) and CpCo(CO)2. Like the electronically related (CO)3Fe(pdt)Fe(CO)(diphos), these complexes undergo protonation to afford the μ-hydrido complexes [CpCo(dithiolate)HFe(CO)(diphos)]+. Low-temperature NMR studies indicate that Co is the kinetic site of protonation. PMID:24803716

  12. Mesoporous Silica-Supported Amidozirconium-Catalyzed Carbonyl Hydroboration

    SciTech Connect

    Eedugurala, Naresh; Wang, Zhuoran; Chaudhary, Umesh; Nelson, Nicholas; Kandel, Kapil; Kobayashi, Takeshi; Slowing, Igor I.; Pruski, Marek; Sadow, Aaron D.

    2015-11-04

    The hydroboration of aldehydes and ketones using a silica-supported zirconium catalyst is reported. Reaction of Zr(NMe2)4 and mesoporous silica nanoparticles (MSN) provides the catalytic material Zr(NMe2)n@MSN. Exhaustive characterization of Zr(NMe2)n@MSN with solid-state (SS)NMR and infrared spectroscopy, as well as through reactivity studies, suggests its surface structure is primarily ≡SiOZr(NMe2)3. The presence of these nitrogen-containing zirconium sites is supported by 15N NMR spectroscopy, including natural abundance 15N NMR measurements using dynamic nuclear polarization (DNP) SSNMR. The Zr(NMe2)n@MSN material reacts with pinacolborane (HBpin) to provide Me2NBpin and the material ZrH/Bpin@MSN that is composed of interacting surface-bonded zirconium hydride and surface-bonded borane ≡SiOBpin moieties in an approximately 1:1 ratio, as well as zirconium sites coordinated by dimethylamine. The ZrH/Bpin@MSN is characterized by 1H/2H and 11B SSNMR and infrared spectroscopy and through its reactivity with D2. The zirconium hydride material or the zirconium amide precursor Zr(NMe2)n@MSN catalyzes the selective hydroboration of aldehydes and ketones with HBpin in the presence of functional groups that are often reduced under hydroboration conditions or are sensitive to metal hydrides, including olefins, alkynes, nitro groups, halides, and ethers. Remarkably, this catalytic material may be recycled without loss of activity at least eight times, and air-exposed materials are catalytically active. These supported zirconium centers are robust catalytic sites for carbonyl reduction and that surface-supported, catalytically reactive zirconium hydride may be generated from zirconium-amide or zirconium alkoxide sites.

  13. Positive trends in Southern Hemisphere observations of carbonyl sulfide

    NASA Astrophysics Data System (ADS)

    Kremser, Stefanie; Jones, Nicholas; Smale, Dan; Palm, Mathias; Lejeune, Bernard; Wang, Yuting; Deutscher, Nicholas

    2016-04-01

    Carbonyl sulfide (OCS; lifetime of about 5.7 years) is the longest lived reduced sulfur-containing gas in the atmosphere. The primary source of OCS is the ocean, which is both a direct source (through OCS emission) and an indirect source (due to oxidation of carbon disulfide, CS2, and dimethyl sulfide). Other natural sources of OCS include volcanic outgassing and direct fluxes from wetland regions. The removal of OCS from the atmosphere is dominated by soil and vegetation uptake, with minor contributions from reactions with the hydroxyl radical. Small anthropogenic sources of OCS are coal combustion, biomass burning, and aluminum production. A dominant indirect source results from CS2 emissions from the rayon industry. Transport of tropospheric OCS to the stratosphere during volcanically quiescent periods has been suggested to contribute sulfur to the stratospheric aerosol layer which affects atmospheric radiative balance. If, however, production of stratospheric aerosols from OCS oxidation is smaller than typical estimates, this OCS contribution would be overestimated. The magnitude of the OCS flux to the stratosphere is currently not well quantified as is the relative contribution of OCS to background aerosol loading. While earlier model simulations indicate OCS fluxes into the atmosphere exceeding removal, past total column observations of OCS show no significant trend. Analysis of tropospheric OCS columns at Arrival Heights (Antarctica) and Lauder (New Zealand) show strong positive trends from 2001-2008 followed by weaker trends to 2015, with unexpected temporal coherence. Since trends in ocean and land sources/sinks at these two sites, respectively, are unlikely to be similar, the coherence in trend structure likely results from changes in transport of OCS from the tropics to middle and high latitudes. Potential causes for OCS increases are (i) increases in tropical lower stratospheric OCS and/or (ii) strengthening of the large-scale circulation which

  14. Transformation of acetaminophen by chlorination produces the toxicants 1,4-benzoquinone and N-acetyl-p-benzoquinone imine.

    PubMed

    Bedner, Mary; MacCrehan, William A

    2006-01-15

    The reaction of the common pain reliever acetaminophen (paracetamol, 4-acetamidophenol) with hypochlorite was investigated over time under conditions that simulate wastewater disinfection. Initially, the reaction was studied in pure water at neutral pH (7.0), a range of reaction times (2-90 min), and a molar excess of hypochlorite (2-57 times) relative to the acetaminophen concentration. The reaction was monitored using reversed-phase liquid chromatography (LC) with ultraviolet absorbance, electrochemical, and mass spectrometric detection. At 1 micromol/L (150 ppb) and 10 micromol/L (1.5 ppm) levels, acetaminophen readily reacted to form at least 11 discernible products, all of which exhibited greater LC retention than the parent. Two of the products were unequivocally identified as the toxic compounds 1,4-benzoquinone and N-acetyl-p-benzoquinone imine (NAPQI), which is the toxicant associated with lethality in acetaminophen overdoses. With a hypochlorite dose of 57 micromol/L (4 ppm as Cl2), 88% of the acetaminophen (10 micromol/L initial) was transformed in 1 h. The two quinoidal oxidation products 1,4-benzoquinone and NAPQI accounted for 25% and 1.5% of the initial acetaminophen concentration, respectively, at a 1 h reaction time. Other products that were identified included two ring chlorination products, chloro-4-acetamidophenol and dichloro-4-acetamidophenol, which combined were approximately 7% of the initial acetaminophen concentration at 1 h. The reaction was also studied in wastewater, where similar reactivity was noted. These results demonstrate that acetaminophen is likely to be transformed significantly during wastewater chlorination. The reactivity of the chlorine-transformation products was also studied with sulfite to simulate dechlorination, and 1,4-benzoquinone and NAPQI were completely reduced. PMID:16468397

  15. Doxorubicin-loaded aromatic imine-contained amphiphilic branched star polymer micelles: synthesis, self-assembly, and drug delivery

    PubMed Central

    Qiu, Liang; Hong, Chun-Yan; Pan, Cai-Yuan

    2015-01-01

    Redox-and pH-sensitive branched star polymers (BSPs), BP(DMAEMA-co-MAEBA-co-DTDMA)(PMAIGP)ns, have been successively prepared by two steps of reversible addition–fragmentation chain transfer (RAFT) polymerization. The first step is RAFT polymerization of 2-(N,N-dimethylaminoethyl)methacrylate (DMAEMA) and p-(methacryloxyethoxy) benzaldehyde (MAEBA) in the presence of divinyl monomer, 2,2′-dithiodiethoxyl dimethacrylate (DTDMA). The resultant branched polymers were used as a macro-RAFT agent in the subsequent RAFT polymerization. After hydrolysis of the BSPs to form BP(DMAEMA-co-MAEBA-co-DTDMA)(PMAGP)ns (BSP-H), the anticancer drug doxorubicin (DOX) was covalently linked to branched polymer chains by reaction of primary amine of DOX and aldehyde groups in the polymer chains. Their compositions, structures, molecular weights, and molecular weight distributions were respectively characterized by nuclear magnetic resonance spectra and gel permeation chromatography measurements. The DOX-loaded micelles were fabricated by self-assembly of DOX-containing BSPs in water, which were characterized by transmission electron microscopy and dynamic light scattering. Aromatic imine linkage is stable in neutral water, but is acid-labile; controlled release of DOX from the BSP-H-DOX micelles was realized at pH values of 5 and 6, and at higher acidic solution, fast release of DOX was observed. In vitro cytotoxicity experiment results revealed low cytotoxicity of the BSPs and release of DOX from micelles in HepG2 and HeLa cells. Confocal laser fluorescence microscopy observations showed that DOX-loaded micelles have specific interaction with HepG2 cells. Thus, this type of BSP micelle is an efficient drug delivery system. PMID:26056444

  16. Characterization of poly(ethylene imine) layers on mica by the streaming potential and particle deposition methods.

    PubMed

    Adamczyk, Zbigniew; Michna, Aneta; Szaraniec, Magdalena; Bratek, Anna; Barbasz, Jakub

    2007-09-01

    Deposition kinetics of polystyrene latex (averaged particle size of 0.66 microm) on mica covered by poly(ethylene imine) (PEI), a cationic polyelectrolyte having an average molecular mass of 75,000 g mol(-1), was studied using the impinging-jet method. The hydrodynamic radius of PEI, determined by PCS measurements, was 5.3 nm. The electrophoretic mobility of PEI was measured as a function of pH for ionic strengths of 10(-3) and 10 (-2) M, which made it possible one to determine the amount of electrokinetic charge of the molecule and its zeta potential. Formation of the polyelectrolyte layer on mica was followed by measuring the streaming potential in the parallel-plate channel. From these measurements, the dependence of the apparent zeta potential of mica on the surface coverage of PEI was determined. The amount of adsorbed PEI on mica was calculated from the convective diffusion theory. These results were quantitatively interpreted in terms of the theoretical model postulating a particle-like adsorption mechanism for PEI with not too significant shape deformation upon adsorption. On the other hand, the Gouy-Chapman model postulating the adsorption in the form of flat disks was proved inappropriate. After the surface was fully characterized, particle deposition experiments were carried out with the aim of finding the correlation between the polymer coverage and the initial rate of latex particle deposition. In the range of small polyelectrolyte coverage, a monotonic relation between the polymer coverage and the initial deposition rate of particles, as well as the jamming coverage, was found. For Theta(PEI)>0.25, the initial particle deposition rate attained the value predicted from the convective diffusion theory for homogeneous surfaces. These results were interpreted theoretically by postulating that an effective immobilization of colloid particles occurred on local polyelectrolyte assemblages containing between two and three PEI molecules. PMID:17521663

  17. (Photo)physical Properties of New Molecular Glasses End-Capped with Thiophene Rings Composed of Diimide and Imine Units

    PubMed Central

    2014-01-01

    New symmetrical arylene bisimide derivatives formed by using electron-donating–electron-accepting systems were synthesized. They consist of a phthalic diimide or naphthalenediimide core and imine linkages and are end-capped with thiophene, bithiophene, and (ethylenedioxy)thiophene units. Moreover, polymers were obtained from a new diamine, N,N′-bis(5-aminonaphthalenyl)naphthalene-1,4,5,8-dicarboximide and 2,5-thiophenedicarboxaldehyde or 2,2′-bithiophene-5,5′-dicarboxaldehyde. The prepared azomethine diimides exhibited glass-forming properties. The obtained compounds emitted blue light with the emission maximum at 470 nm. The value of the absorption coefficient was determined as a function of the photon energy using spectroscopic ellipsometry. All compounds are electrochemically active and undergo reversible electrochemical reduction and irreversible oxidation processes as was found in cyclic voltammetry and differential pulse voltammetry (DPV) studies. They exhibited a low electrochemically (DPV) calculated energy band gap (Eg) from 1.14 to 1.70 eV. The highest occupied molecular orbital and lowest unoccupied molecular orbital levels and Eg were additionally calculated theoretically by density functional theory at the B3LYP/6-31G(d,p) level. The photovoltaic properties of two model compounds as the active layer in organic solar cells in the configuration indium tin oxide/poly(3,4-(ethylenedioxy)thiophene):poly(styrenesulfonate)/active layer/Al under an illumination of 1.3 mW/cm2 were studied. The device comprising poly(3-hexylthiophene) with the compound end-capped with bithiophene rings showed the highest value of Voc (above 1 V). The conversion efficiency of the fabricated solar cell was in the range of 0.69–0.90%. PMID:24966893

  18. (Photo)physical Properties of New Molecular Glasses End-Capped with Thiophene Rings Composed of Diimide and Imine Units.

    PubMed

    Grucela-Zajac, Marzena; Bijak, Katarzyna; Kula, Slawomir; Filapek, Michal; Wiacek, Malgorzata; Janeczek, Henryk; Skorka, Lukasz; Gasiorowski, Jacek; Hingerl, Kurt; Sariciftci, Niyazi Serdar; Nosidlak, Natalia; Lewinska, Gabriela; Sanetra, Jerzy; Schab-Balcerzak, Ewa

    2014-06-19

    New symmetrical arylene bisimide derivatives formed by using electron-donating-electron-accepting systems were synthesized. They consist of a phthalic diimide or naphthalenediimide core and imine linkages and are end-capped with thiophene, bithiophene, and (ethylenedioxy)thiophene units. Moreover, polymers were obtained from a new diamine, N,N'-bis(5-aminonaphthalenyl)naphthalene-1,4,5,8-dicarboximide and 2,5-thiophenedicarboxaldehyde or 2,2'-bithiophene-5,5'-dicarboxaldehyde. The prepared azomethine diimides exhibited glass-forming properties. The obtained compounds emitted blue light with the emission maximum at 470 nm. The value of the absorption coefficient was determined as a function of the photon energy using spectroscopic ellipsometry. All compounds are electrochemically active and undergo reversible electrochemical reduction and irreversible oxidation processes as was found in cyclic voltammetry and differential pulse voltammetry (DPV) studies. They exhibited a low electrochemically (DPV) calculated energy band gap (E g) from 1.14 to 1.70 eV. The highest occupied molecular orbital and lowest unoccupied molecular orbital levels and E g were additionally calculated theoretically by density functional theory at the B3LYP/6-31G(d,p) level. The photovoltaic properties of two model compounds as the active layer in organic solar cells in the configuration indium tin oxide/poly(3,4-(ethylenedioxy)thiophene):poly(styrenesulfonate)/active layer/Al under an illumination of 1.3 mW/cm(2) were studied. The device comprising poly(3-hexylthiophene) with the compound end-capped with bithiophene rings showed the highest value of V oc (above 1 V). The conversion efficiency of the fabricated solar cell was in the range of 0.69-0.90%. PMID:24966893

  19. PEGylation affects cytotoxicity and cell-compatibility of poly(ethylene imine) for lung application: Structure-function relationships

    SciTech Connect

    Beyerle, Andrea; Merkel, Olivia; Stoeger, Tobias; Kissel, Thomas

    2010-01-15

    Poly(ethylene imine) (PEI) has widely been used as non-viral gene carrier due to its capability to form stable complexes by electrostatic interactions with nucleic acids. To reduce cytotoxicity of PEI, several studies have addressed modified PEIs such as block or graft copolymers containing cationic and hydrophilic non-ionic components. Copolymers of PEI and hydrophilic poly(ethylene glycol) (PEG) with various molecular weights and graft densities were shown to exhibit decreased cytotoxicity and potential for DNA and siRNA delivery. In this study, we evaluated the cytotoxicity and cell-compatibility of different PEGylated PEI polymers in two murine lung cell lines. We found that the degree of PEGylation correlated with both cytotoxicity and oxidative stress, but not with proinflammatory effects. AB type copolymers with long PEG blocks caused high membrane damage and significantly decreased the metabolic activity of lung cells. In addition, they significantly increased the release of two lipid mediators such as 8-isoprostanes (8-IP) and prostaglandin E{sub 2} (PGE{sub 2}) in a dose-dependent manner. In contrast, the cytokine profiles which indicated high levels of acute-phase cytokines such as TNF-alpha, IL-6, and G-CSF did not follow any clear structure-function relationship. In conclusion, we found that modification of PEI 25kDa with high degree of PEGylation and low PEG chain length reduced cytotoxic and oxidative stress response in lung cells, while the proinflammatory potential remained unaffected. A degree of substitution in the range of 10 to 30 and PEG-chain lengths up to 2000 Da seem to be beneficial and merit further investigations.

  20. Conversion of a monodentate amidinate-germylene ligand into chelating imine-germanate ligands (on mononuclear manganese complexes).

    PubMed

    Cabeza, Javier A; García-Álvarez, Pablo; Pérez-Carreño, Enrique; Polo, Diego

    2014-08-18

    The unprecedented transformation of a terminal two-electron-donor amidinate-germylene ligand into a chelating three-electron-donor κ(2)-N,Ge-imine-germanate ligand has been achieved by treating the manganese amidinate-germylene complex [MnBr{Ge((i)Pr2bzam)(t)Bu}(CO)4] (1; (i)Pr2bzam = N,N'-bis(isopropyl)benzamidinate) with LiMe or Ag[BF4]. In these reactions, which afford [Mn{κ(2)Ge,N-GeMe((i)Pr2bzam)(t)Bu}(CO)4] (2) and [Mn{κ(2)Ge,N-GeF((i)Pr2bzam)(t)Bu}(CO)4] (3), respectively, the anionic nucleophile, Me(-) or F(-), ends on the Ge atom while an arm of the amidinate fragment migrates from the Ge atom to the Mn atom. In contrast, the reaction of 1 with AgOTf (OTf = triflate) leads to [Mn(OTf){Ge((i)Pr2bzam)(t)Bu}(CO)4] (4), which maintains intact the amidinate-germylene ligand. Complex 4 is very moisture-sensitive, leading to [Mn2{μ-κ(4)Ge2,O2-Ge2(t)Bu2(OH)2O}(CO)8] (5) and [(i)Pr2bzamH2]OTf (6) in wet solvents. In 5, a novel digermanate(II) ligand, [(t)Bu(OH)GeOGe(OH)(t)Bu](2-), doubly bridges two Mn(CO)4 units. The structures of 1-6 have been characterized by spectroscopic (IR, NMR) and single-crystal X-ray diffraction methods. PMID:25084394

  1. Doxorubicin-loaded aromatic imine-contained amphiphilic branched star polymer micelles: synthesis, self-assembly, and drug delivery.

    PubMed

    Qiu, Liang; Hong, Chun-Yan; Pan, Cai-Yuan

    2015-01-01

    Redox-and pH-sensitive branched star polymers (BSPs), BP(DMAEMA-co-MAEBA-co-DTDMA)(PMAIGP)(n)s, have been successively prepared by two steps of reversible addition-fragmentation chain transfer (RAFT) polymerization. The first step is RAFT polymerization of 2-(N,N-dimethylaminoethyl)methacrylate (DMAEMA) and p-(methacryloxyethoxy) benzaldehyde (MAEBA) in the presence of divinyl monomer, 2,2'-dithiodiethoxyl dimethacrylate (DTDMA). The resultant branched polymers were used as a macro-RAFT agent in the subsequent RAFT polymerization. After hydrolysis of the BSPs to form BP(DMAEMA-co-MAEBA-co-DTDMA)(PMAGP)(n)s (BSP-H), the anticancer drug doxorubicin (DOX) was covalently linked to branched polymer chains by reaction of primary amine of DOX and aldehyde groups in the polymer chains. Their compositions, structures, molecular weights, and molecular weight distributions were respectively characterized by nuclear magnetic resonance spectra and gel permeation chromatography measurements. The DOX-loaded micelles were fabricated by self-assembly of DOX-containing BSPs in water, which were characterized by transmission electron microscopy and dynamic light scattering. Aromatic imine linkage is stable in neutral water, but is acid-labile; controlled release of DOX from the BSP-H-DOX micelles was realized at pH values of 5 and 6, and at higher acidic solution, fast release of DOX was observed. In vitro cytotoxicity experiment results revealed low cytotoxicity of the BSPs and release of DOX from micelles in HepG2 and HeLa cells. Confocal laser fluorescence microscopy observations showed that DOX-loaded micelles have specific interaction with HepG2 cells. Thus, this type of BSP micelle is an efficient drug delivery system. PMID:26056444

  2. Waterpipe smoking: the role of humectants in the release of toxic carbonyls.

    PubMed

    Schubert, Jens; Heinke, Volkmar; Bewersdorff, Jana; Luch, Andreas; Schulz, Thomas G

    2012-08-01

    In recent years, the number of waterpipe smokers has increased substantially worldwide. Here, we present a study on the identification and quantification of seven carbonylic compounds including formaldehyde, acetaldehyde and acrolein in the mainstream smoke of the waterpipe. Smoking was conducted with a smoking machine, and carbonyls were scavenged from the smoke with two impingers containing an acidic solution of 2,4-dinitrophenylhydrazine. The derivatives were then analyzed by high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). For instance, during one waterpipe smoking session, up to 111 ± 12 μg formaldehyde could be detected. This value is about 5 times higher when compared to one 2R4F reference cigarette. We also found a distinct filter effect of the bowl water for all carbonyls investigated. Our data further demonstrate that increasing amounts of humectants in the unburned tobacco lowers the temperature in the waterpipe head during smoking, thereby resulting in decreasing levels of carbonyls in the smoke produced. Altogether, considerable amounts of toxic carbonyls are present in the waterpipe smoke, thus conferring a health risk to waterpipe smokers. PMID:22707202

  3. Novel DNPH-based method for determination of protein carbonylation in muscle and meat.

    PubMed

    Soglia, Francesca; Petracci, Massimiliano; Ertbjerg, Per

    2016-04-15

    Protein oxidation is considered an ongoing deteriorative process during storage of fresh and processed meat. Carbonyl compounds have traditionally been detected spectrophotometrically after derivatization with 2,4-dinitrophenylhydrazine (DNPH) to form protein-bound hydrazones with absorbance at 370 nm. Here we describe a novel DNPH-based method to quantify protein carbonylation in muscle and meat. The additional steps of the novel method aimed at increasing the protein solubility and inducing protein unfolding before labeling with DNPH. Compared to the traditional method, the new procedure reflected an increased protein carbonylation level measuring overall two to fourfold more carbonyls in muscles from different species as well as in soluble, salt-soluble and insoluble protein fractions. The study suggested that protein unfolding is a more important phenomenon than solubilization for increased DNPH labeling. The novel method resulted in three to fourfold larger carbonyl content determined in chicken, pork and beef (2.8, 3.6 and 3.1 nmol/mg of protein, respectively). PMID:26617002

  4. Detection of Oxidative Stress-Induced Carbonylation in Live Mammalian Cells

    PubMed Central

    Mukherjee, Kamalika; Chio, Tak Ian; Sackett, Dan L.; Bane, Susan L.

    2015-01-01

    Oxidative stress is often associated with etiology and/or progression of disease conditions, such as cancer, neurodegenerative diseases, and diabetes. At the cellular level, oxidative stress induces carbonylation of biomolecules such as lipids, proteins and DNA. The presence of carbonylcontaining biomolecules as a hallmark of these diseases provides a suitable target for diagnostic detection. Here, a simple, robust method for detecting cellular aldehydes and ketones in live cells using a fluorophore is presented. A hydrazine-functionalized synthetic fluorophore serves as an efficient nucleophile that rapidly reacts with reactive carbonyls in the cellular milieu. The product thus formed exhibits a wavelength shift in the emission maximum accompanied by an increase in emission intensity. The photochemical characteristics of the fluorophore enable the identification of the fluorophore-conjugated cellular biomolecules in the presence of unreacted dye, eliminating the need for removal of excess fluorophore. Moreover, this fluorophore is found to be non-toxic and is thus appropriate for live cell analysis. Utility of the probe is demonstrated in two cell lines, PC3 and A549. Carbonylation resulting from serum starvation and hydrogen peroxide induced stress is detected in both cell lines using fluorescence microscopy and a fluorescence plate reader. The fluorescent signal originates from carbonylated proteins and lipids but not from oxidized DNA, and the majority of the fluorescence signal (>60%) is attributed to fluorophore-conjugated lipid oxidation products. This method should be useful for detecting cellular carbonylation in a high content assay or high throughput assay format. PMID:25801292

  5. Seasonal, diurnal and nocturnal behaviors of lower carbonyl compounds in the urban environment of Beirut, Lebanon

    NASA Astrophysics Data System (ADS)

    Moussa, Samar G.; El-Fadel, Mutassem; Saliba, Najat A.

    Lower carbonyl concentrations were measured for the first time in two different sampling sites (American University of Beirut (AUB) and Abdel-Aziz (AA)) in Beirut, Lebanon. Formaldehyde (C1) and acetaldehyde (C2) were the most abundant carbonyls with respective maximum concentrations of 12.2 and 5.2 ppbv at AUB and 8.6 and 5.1 ppbv at AA. Diurnal variations of carbonyls exhibited similar behaviors, suggesting related formation and decomposition routes. Morning levels of carbonyls were either equal or higher than the ones in the afternoon at the coastal site (AUB) due to atmospheric dilution. However, morning levels were mostly lower than noon levels at a three-busy street intersection (AA) due to the enhancement of photochemical activities. Vehicle emissions constituted the dominant source of carbonyls measured as confirmed by the good correlation between C1, C2 and propanal (C3) and the C1/CO and C2/CO ratios in the mornings. Seasonal variation showed the predominance of summertime photolysis and photo-oxidation reactions of aldehydes. Based on the measured formaldehyde levels, ozone and nitrous acid concentrations, morning and afternoon OH radical fluxes are computed and consequently their contribution to photochemical smog processes are assessed.

  6. Formation of carbonyl groups on cellulose during ozone treatment of pulp: consequences for pulp bleaching.

    PubMed

    Pouyet, Frédéric; Chirat, Christine; Potthast, Antje; Lachenal, Dominique

    2014-08-30

    The formation of carbonyl groups during the ozone treatment (Z) of eucalyptus (Eucalyptus grandis and Eucalyptus urophylla hybrid) kraft pulps and their behaviors during subsequent alkaline stages were investigated by the CCOA method with carbazole-9-carboxylic acid [2-(2-aminooxethoxy)-ethoxy] amide (CCOA) as the carbonyl-selective fluorescence label. Several pulp samples with or without lignin and hexenuronic acids (hexA) were used to elucidate the effects of these components when present in unbleached kraft pulp. Both hexA and lignin increased the formation of carbonyl groups on cellulose and hemicellulose during ozonation. It was concluded that radicals are likely formed when ozone reacts with either lignin or hexA. These carbonyl groups were involved in cellulose depolymerization during subsequent alkaline extraction stages with sodium hydroxide (E) and alkaline hydrogen peroxide (P, in ZEP or ZP). Their numbers decreased after E but increased during P when H2O2 was not stabilized enough. Several ways to minimize the occurrence of carbonyl group formation are suggested. PMID:24815405

  7. Ambient levels of atmospheric carbonyls in Beijing during the 2008 Olympic Games.

    PubMed

    Xu, Zhu; Liu, Junfeng; Zhang, Yujie; Liang, Peng; Mu, Yujing

    2010-01-01

    The measurements of atmospheric carbonyls concentrations in Beijing were conducted from 12 July to 8 October, 2008, covering the periods of the 2008 Olympic Games and Paralympic Games. Six carbonyls, including formaldehyde, acetaldehyde, acetone, butyraldehyde, valeraldehyde, and hexaldehyde, were identified in all air samples. The total average concentrations of these carbonyls before, during, and after traffic restriction were (48.1 +/- 15.2), (36.6 +/- 14.5) and (23.4 +/- 12.3) microg/m3, respectively. Compared with the period after traffic restriction, the distinct high concentrations of the carbonyls before and during traffic restriction were primarily ascribed to the remarkable contribution of photochemical reactions. With respect to our previous investigation in the summer of 2005, the reductions of formaldehyde, acetaldehyde and acetone during traffic restriction period were about 64%, 47% and 27%, respectively, indicating that the air cleaning actions adopted by the Chinese government for the two games were efficient. The lowest levels of atmospheric carbonyls and the extremely high composition proportion of acetone after the traffic restriction were mainly attributed to the long-term effect of the control measures for the two games. PMID:21174965

  8. Fructose-Induced Carbonyl/Oxidative Stress in S. cerevisiae: Involvement of TOR.

    PubMed

    Valishkevych, Bohdana V; Vasylkovska, Ruslana A; Lozinska, Liudmyla M; Semchyshyn, Halyna M

    2016-01-01

    The TOR (target of rapamycin) signaling pathway first described in the budding yeast Saccharomyces cerevisiae is highly conserved in eukaryotes effector of cell growth, longevity, and stress response. TOR activation by nitrogen sources, in particular amino acids, is well studied; however its interplay with carbohydrates and carbonyl stress is poorly investigated. Fructose is a more potent glycoxidation agent capable of producing greater amounts of reactive carbonyl (RCS) and oxygen species (ROS) than glucose. The increased RCS/ROS production, as a result of glycoxidation in vivo, is supposed to be involved in carbonyl/oxidative stress, metabolic disorders, and lifespan shortening of eukaryotes. In this work we aim to expand our understanding of how TOR is involved in carbonyl/oxidative stress caused by reducing monosaccharides. It was found that in fructose-grown compared with glucose-grown cells the level of carbonyl/oxidative stress markers was higher. The defects in the TOR pathway inhibited metabolic rate and suppressed generation of glycoxidation products in fructose-grown yeast. PMID:27019749

  9. Fructose-Induced Carbonyl/Oxidative Stress in S. cerevisiae: Involvement of TOR

    PubMed Central

    Valishkevych, Bohdana V.; Vasylkovska, Ruslana A.; Lozinska, Liudmyla M.; Semchyshyn, Halyna M.

    2016-01-01

    The TOR (target of rapamycin) signaling pathway first described in the budding yeast Saccharomyces cerevisiae is highly conserved in eukaryotes effector of cell growth, longevity, and stress response. TOR activation by nitrogen sources, in particular amino acids, is well studied; however its interplay with carbohydrates and carbonyl stress is poorly investigated. Fructose is a more potent glycoxidation agent capable of producing greater amounts of reactive carbonyl (RCS) and oxygen species (ROS) than glucose. The increased RCS/ROS production, as a result of glycoxidation in vivo, is supposed to be involved in carbonyl/oxidative stress, metabolic disorders, and lifespan shortening of eukaryotes. In this work we aim to expand our understanding of how TOR is involved in carbonyl/oxidative stress caused by reducing monosaccharides. It was found that in fructose-grown compared with glucose-grown cells the level of carbonyl/oxidative stress markers was higher. The defects in the TOR pathway inhibited metabolic rate and suppressed generation of glycoxidation products in fructose-grown yeast. PMID:27019749

  10. The Schwarzschild Proton

    SciTech Connect

    Haramein, Nassim

    2010-11-24

    We review our model of a proton that obeys the Schwarzschild condition. We find that only a very small percentage ({approx}10{sup -39}%) of the vacuum fluctuations available within a proton volume need be cohered and converted to mass-energy in order for the proton to meet the Schwarzschild condition. This proportion is equivalent to that between gravitation and the strong force where gravitation is thought to be {approx}10{sup -38} to 10{sup -40} weaker than the strong force. Gravitational attraction between two contiguous Schwarzschild protons can accommodate both nucleon and quark confinement. We calculate that two contiguous Schwarzschild protons would rotate at c and have a period of 10{sup -23} s and a frequency of 10{sup 22} Hz which is characteristic of the strong force interaction time and a close approximation of the gamma emission typically associated with nuclear decay. We include a scaling law and find that the Schwarzschild proton data point lies near the least squares trend line for organized matter. Using a semi-classical model, we find that a proton charge orbiting at a proton radius at c generates a good approximation to the measured anomalous magnetic moment.

  11. Crystal structure of [N,N'-bis-(4-methyl-phen-yl)-1,2-di-phenyl-ethane-1,2-di-imine-κ(2) N,N']di-chlorido-palladium(II) methanol monosolvate.

    PubMed

    Peñaloza, Alfredo; Fronczek, Frank R; Isovitsch, Ralph

    2015-09-01

    The title compound, [PdCl2(C28H24N2)]·CH3OH, was pre-pared from the reaction of PdCl2(DMSO)2 (DMSO is di-methyl sulfoxide) and N,N'-bis-(4-methyl-phen-yl)-1,2-di-phenyl-ethane-1,2-di-imine in methanol. The chelating di-imine core of the title compound deviates slightly from planarity, with an N-C-C-N torsion angle of 5.3 (3)°. Delocalization in the di-imine core is indicated by N-C and C-C bonds that are, respectively, longer and shorter than those found in related nonchelating di-imines. The distorted square-planar coordination environment around the Pd(II) atom is manifested as bond angles that are smaller and larger than 90°, and palladacycle torsion angles of -173.22 (16) and 167.06 (16)°. These deviations are attributed to the small bite angle of 79.13 (8)° of the di-imine chelate. The crystal packing exhibits weak inter-molecular hydrogen-bonding inter-actions involving aromatic H atoms, Cl atoms and inter-calated methanol solvent mol-ecules, defining layers parallel to (010). PMID:26396867

  12. Electron-proton spectrometer

    NASA Technical Reports Server (NTRS)

    Winckler, J. R.

    1973-01-01

    An electron-proton spectrometer was designed to measure the geomagnetically trapped radiation in a geostationary orbit at 6.6 earth radii in the outer radiation belt. This instrument is to be flown on the Applications Technology Satellite-F (ATS-F). The electron-proton spectrometer consists of two permanent magnet surface barrier detector arrays and associated electronics capable of selecting and detecting electrons in three energy ranges: (1) 30-50 keV, (2) 150-200 keV, and (3) 500 keV and protons in three energy ranges. The electron-proton spectrometer has the capability of measuring the fluxes of electrons and protons in various directions with respect to the magnetic field lines running through the satellite. One magnet detector array system is implemented to scan between EME north and south through west, sampling the directional flux in 15 steps. The other magnet-detector array system is fixed looking toward EME east.

  13. Proton-proton colliding beam facility ISABELLE

    SciTech Connect

    Hahn, H

    1980-01-01

    This paper attempts to present the status of the ISABELLE construction project, which has the objective of building a 400 + 400 GeV proton colliding beam facility. The major technical features of the superconducting accelerators with their projected performance are described. Progress made so far, difficulties encountered, and the program until completion in 1986 is briefly reviewed.

  14. Characterization of cytochrome P450 isoforms involved in sequential two-step bioactivation of diclofenac to reactive p-benzoquinone imines.

    PubMed

    den Braver, Michiel W; den Braver-Sewradj, Shalenie P; Vermeulen, Nico P E; Commandeur, Jan N M

    2016-06-24

    Idiosyncratic drug-induced lever injury (IDILI) is a rare but severe side effect of diclofenac (DF). Several mechanisms have been proposed as cause of DF-induced toxicity including the formation of protein-reactive diclofenac-1',4'-quinone imine (DF-1',4'-QI) and diclofenac-2,5-quinone imine (DF-2,5-QI). Formation of these p-benzoquinone imines result from two-step oxidative metabolism involving aromatic hydroxylation to 4'-hydroxydiclofenac and 5-hydroxydiclofenac followed by dehydrogenation to DF-1',4'-QI and DF-2,5-QI, respectively. Although the contribution of individual cytochrome P450s (CYPs) in aromatic hydroxylation of DF is well studied, the enzymes involved in the dehydrogenation reactions have been poorly characterized. The results of the present study show that both formation of 4'-hydroxydiclofenac and it subsequent bioactivation to DF-1',4'-QI is selectively catalyzed by CYP2C9. However, the two-step bioactivation to DF-2,5-QI appears to be catalyzed with highest activity by two different CYPs: 5-hydroxylation of DF is predominantly catalyzed by CYP3A4, whereas its subsequent bioactivation to DF-2,5-QI is catalyzed with 14-fold higher intrinsic clearance by CYP2C9. The fact that both CYPs involved in two-step bioactivation of DF show large interindividual variability may play a role in different susceptibility of patients to DF-induced IDILI. Furthermore, expression levels of these enzymes and protective enzymes might be important factors determining sensitivity of in vitro models for hepatotoxicity. PMID:27130197

  15. Development of a solid-phase receptor-based assay for the detection of cyclic imines using a microsphere-flow cytometry system.

    PubMed

    Rodríguez, Laura P; Vilariño, Natalia; Molgó, Jordi; Aráoz, Rómulo; Louzao, M Carmen; Taylor, Palmer; Talley, Todd; Botana, Luis M

    2013-02-19

    Biologically active macrocycles containing a cyclic imine were isolated for the first time from aquaculture sites in Nova Scotia, Canada, during the 1990s. These compounds display a "fast-acting" toxicity in the traditional mouse bioassay for lipophilic marine toxins. Our work aimed at developing a receptor-based detection method for spirolides using a microsphere/flow cytometry Luminex system. For the assay, two alternatives were considered as binding proteins, the Torpedo marmorata nicotinic acetylcholine receptor (nAChR) and the Lymnaea stagnalis acetylcholine binding protein (Ls-AChBP). A receptor-based inhibition assay was developed using the immobilization of nAChR or Ls-AChBP on the surface of carboxylated microspheres and the competition of cyclic imines with biotin-α-bungarotoxin (α-BTX) for binding to these proteins. The amount of biotin-α-BTX bound to the surface of the microspheres was quantified using phycoerythrin (PE)-labeled streptavidin, and the fluorescence was analyzed in a Luminex 200 system. AChBP and nAChR bound to 13-desmethyl spirolide C efficiently; however, the cross-reactivity profile of the nAChR for spirolides and gymnodimine more closely matched the relative toxic potencies reported for these toxins. The nAChR was selected for further assay development. A simple sample preparation protocol consisting of an extraction with acetone yielded a final extract with no matrix interference on the nAChR/microsphere-based assay for mussels, scallops, and clams. This cyclic imine detection method allowed the detection of 13-desmethyl spirolide C in the range of 10-6000 μg/kg of shellfish meat, displaying a higher sensitivity and wider dynamic range than other receptor-based assays previously published. This microsphere-based assay provides a rapid, sensitive, and easily performed screening method that could be multiplexed for the simultaneous detection of several marine toxins. PMID:23343192

  16. Development of a Solid-Phase Receptor-Based Assay for the Detection of Cyclic Imines Using a Microsphere-Flow Cytometry System

    PubMed Central

    Rodríguez, Laura P.; Vilariño, Natalia; Molgó, Jordi; Aráoz, Rómulo; Louzao, M. Carmen; Taylor, Palmer; Talley, Todd; Botana, Luis M.

    2013-01-01

    Biologically active macrocycles containing a cyclic imine were isolated for the first time from aquaculture sites in Nova Scotia, Canada, during the 1990s. These compounds display a “fast-acting” toxicity in the traditional mouse bioassay for lipophilic marine toxins. Our work aimed at developing receptor-based detection method for spirolides using a microsphere/flow cytometry Luminex system. For the assay two alternatives were considered as binding proteins, the Torpedo marmorata nicotinic acetylcholine receptor (nAChR) and the Lymnaea stagnalis acetylcholine binding protein (Ls-AChBP). A receptor-based inhibition assay was developed using the immobilization of nAChR or Ls-AChBP on the surface of carboxylated microspheres and the competition of cyclic imines with biotin-α-bungarotoxin (α-BTX) for binding to these proteins. The amount of biotin-α-BTX bound to the surface of the microspheres was quantified using phycoerythrin (PE)-labeled streptavidin and the fluorescence was analyzed in a Luminex 200 system. AChBP and nAChR bound to 13-desmethyl spirolide C efficiently; however the cross-reactivity profile of the nAChR for spirolides and gymnodimine more closely matched the relative toxic potencies reported for these toxins. The nAChR was selected for further assay development. A simple sample preparation protocol consisting of an extraction with acetone yielded a final extract with no matrix interference on the nAChR/microsphere-based assay for mussels, scallops and clams. This cyclic imine detection method allowed the detection of 13-desmethyl spirolide C in the range of 10–6000 μg/kg of shellfish meat, displaying a higher sensitivity and wider dynamic range than other receptor-based assays previously published. This microsphere-based assay provides a rapid, sensitive and easily performed screening method that could be multiplexed for the simultaneous detection of several marine toxins. PMID:23343192

  17. Synthesis of Ti(IV) complexes of donor-functionalised phenoxy-imine tridentates and their evaluation in ethylene oligomerisation and polymerisation.

    PubMed

    Suttil, James A; Shaw, Miranda F; McGuinness, David S; Gardiner, Michael G; Evans, Stephen J

    2013-07-01

    A number of analogues of the Mitsui Chemicals ethylene trimerisation system (IV) have been explored, in which one of the donor atoms have been modified. Thus, a series of mono-anionic tridentate phenoxy-imine (3-(t-butyl)-2-(OH)-C6H4C=N(C(CH3)2CH2OMe) 1, 3-(adamantyl)-2-(OH)-C6H4C=N(2'-(2''-(SMe)C6H4)-C6H4) 2, 3-(t-butyl)-2-(OSiMe3)-C6H4C=N(C(CH3)2CH2OMe) 3) or phenoxy-amine (3,5-di(t-butyl)-2-(OH)-C6H4CH2-N(2'-(2''-(OMe)C6H4)-C6H4) 4) ligands have been prepared and reacted with TiCl4 or TiCl4(thf)2 to give the mono-ligand complexes 5-7. The solid state structures of compounds 4-6 have been determined. Complexes 5-7 have been tested for their potential as ethylene oligomerisation/polymerisation systems in conjunction with MAO activator and benchmarked against the Mitsui phenoxy-imine trimerisation system IV. While the phenoxy-amine complex 6 shows a propensity for polymer formation, the phenoxy-imine complexes 5 and 7 show somewhat increased formation of short chain LAOs. Complex 5 is selective for 1-butene in the oligomeric fraction, while 7 displays liquid phase selectivity to 1-hexene. As such 7, which is a sulfur substituted analogue of the Mitsui system IV, displays similar characteristics to the parent catalyst. However, its utility is limited by the lower activity and predominant formation of polyethylene. PMID:23403608

  18. Mechanistic differences between methanol and dimethyl ether carbonylation in side pockets and large channels of mordenite.

    PubMed

    Boronat, Mercedes; Martínez, Cristina; Corma, Avelino

    2011-02-21

    The activity and selectivity towards carbonylation presented by Brønsted acid sites located inside the 8MR pockets or in the main 12MR channels of mordenite is studied by means of quantum-chemical calculations, and the mechanistic differences between methanol and DME carbonylation are investigated. The selectivity towards carbonylation is higher inside the 8MR pockets, where the competitive formation of DME and hydrocarbons that finally leads to catalyst deactivation is sterically impeded. Moreover, inclusion of dispersion interactions in the calculations leads to agreement between the calculated activation barriers for the rate determining step and the experimentally observed higher reactivity of methoxy groups located inside the 8MR channels. PMID:21249237

  19. A Carbonyl Capture Approach for Profiling Oxidized Metabolites in Cell Extracts

    PubMed Central

    Mattingly, Stephanie J.; Xu, Tao; Nantz, Michael H.; Higashi, Richard M.; Fan, Teresa W.-M.

    2012-01-01

    Fourier-transform ion-cyclotron resonance mass spectrometry (FT-ICR-MS) detection of oxidized cellular metabolites is described using isotopologic, carbonyl-selective derivatizing agents that integrate aminooxy functionality for carbonyl capture, quaternary nitrogen for electrospray enhancement, and a hydrophobic domain for sample cleanup. These modular structural features enable rapid, sensitive analysis of complex mixtures of metabolite-derivatives by FT-ICR-MS via continuous nanoelectrospray infusion. Specifically, this approach can be used to globally assess levels of low abundance and labile aldehyde and ketone metabolites quantitatively and in high throughput manner. These metabolites are often key and unique indicators of various biochemical pathways and their perturbations. Analysis of lung adenocarcinoma A549 cells established a profile of carbonyl metabolites spanning multiple structural classes. We also demonstrate a procedure for metabolite quantification using pyruvate as a model analyte. PMID:23175637

  20. Effect of carbonyl iron particles composition on the physical characteristics of MR grease

    NASA Astrophysics Data System (ADS)

    Mohamad, Norzilawati; Mazlan, Saiful Amri; Ubaidillah

    2016-03-01

    Magnetorheological (MR) grease is an extension of the study of magnetorheological materials. The MR grease can help to reduce the particles sedimentation problem occurred in the MR fluids. Within this study, an effort has been taken to investigate the effect of different weight compositions of carbonyl iron particles on the physical and chemical characteristics of the MR grease under off-state condition (no magnetic field). The MR grease is prepared by mixing carbonyl iron particles having a size range of 1 to 10 µm with commercial NPC Highrex HD-3 grease. Characterizations of MR grease are investigated using Vibrating Sample Magnetometer (VSM), Environmental Scanning Electron Microscopy (ESEM), Differential Scanning Calorimeter (DSC) and rheometer. The dependency of carbonyl iron particles weight towards the magnetic properties of MR grease and other characterizations are investigated.

  1. Access to 4,6-Diarylpicolinates via a Domino Reaction of Cyclic Sulfamidate Imines with Morita-Baylis-Hillman Acetates of Nitroolefins/Nitrodienes.

    PubMed

    Majee, Debashis; Biswas, Soumen; Mobin, Shaikh M; Samanta, Sampak

    2016-05-20

    An interesting domino reaction of 5-membered cyclic sulfamidate imines with a variety of Morita-Baylis-Hillman acetates of nitroolefins/nitrodienes in the presence of DABCO as an organic base at 55 °C is reported for the first time. This new synthetic strategy provides a series of pharmacologically interesting 4,6-diarylpicolinates in high to excellent yields and allows several compatible functionalities on aryl rings. Moreover, the biologically interesting imidazo[1,2-a]pyridine (alpidem derivative) has been prepared in high chemical yield through a unique procedure. PMID:27129356

  2. Brønsted Acid-Catalyzed Transfer Hydrogenation of Imines and Alkenes Using Cyclohexa-1,4-dienes as Dihydrogen Surrogates.

    PubMed

    Chatterjee, Indranil; Oestreich, Martin

    2016-05-20

    Cyclohexa-1,4-dienes are introduced to Brønsted acid-catalyzed transfer hydrogenation as an alternative to the widely used Hantzsch dihydropyridines. While these hydrocarbon-based dihydrogen surrogates do offer little advantage over established protocols in imine reduction as well as reductive amination, their use enables the previously unprecedented transfer hydrogenation of structurally and electronically unbiased 1,1-di- and trisubstituted alkenes. The mild procedure requires 5.0 mol % of Tf2NH, but the less acidic sulfonic acids TfOH and TsOH work equally well. PMID:27181437

  3. Synthesis of 3H-pyrazolo[3,4-c]isoquinolines and thieno[3,2-c]isoquinolines via cascade imination/intramolecular decarboxylative coupling.

    PubMed

    Pandey, Garima; Bhowmik, Subhendu; Batra, Sanjay

    2013-10-01

    A general approach for the synthesis of 3H-pyrazolo[3,4-c]isoquinolines and thieno[3,2-c]isoquinolines is described involving the implementation of a cascade imination/intramolecular decarboxylative coupling between potassium 2-amino(hetero)benzoates and 2-haloarylaldehydes. The reactions of pyrazole-based substrates require a Pd-Cu bimetallic system for superior yields whereas the thienyl-based substrates afford the products in excellent yields with a Pd-catalyst only. PMID:24047440

  4. Carbonyls and non-methane hydrocarbons at a rural mountain site in northeastern United States.

    PubMed

    Khwaja, Haider A; Narang, Amarjit

    2008-05-01

    Measurements of carbonyls and C(2)-C(6) non-methane hydrocarbons (NMHCs) were made in ambient air at a rural site at the summit of Whiteface Mountain (WFM) in New York State. Alkanes dominated in the samples, with ethane and propane making up about 55% of the total on a carbon-atom basis. Ethane, the longest-lived of the NMHCs, showed a mixing ratio in the range of 0.86-2.1 ppbv. Photochemical ageing analysis indicated an anthropogenic influence on the NMHC levels. The photochemical reactivity of the hydrocarbons, calculated in terms of propylene-equivalent concentration, was dominated by alkenes (propene and ethene), which accounted for 74% of the total NMHC sum. Air mass back-trajectories have been used to investigate the origin of the observed NMHCs and carbonyls. Higher concentrations were found when air masses arrived from the midwestern US corridor. Acetone was the most abundant species, comprising from 31% to 53% of the total detected carbonyls, followed by MEK (15-53%), HCHO (7-39%), and CH(3)CHO (7-19%). Average concentrations were determined to be 1.61 ppbv for CH(3)C(O)CH(3), 1.40 ppbv for MEK, 1.16 ppbv for HCHO, and 0.49 ppbv for CH(3)CHO. The variations in carbonyl concentrations were observed to follow patterns similar to variations in O(3) concentrations, typical of secondary products. Correlations and statistical analysis of the carbonyls and NMHCs were performed, and showed that most of the compounds derived from mixing and photochemical transformation of long-range transported pollutants from the major source areas. Ranking of the carbonyls with respect to removal of the OH radical showed HCHO to be the most important species, followed by CH(3)CHO, MEK, and CH(3)C(O)CH(3). PMID:18420251

  5. Flash Proton Radiography

    NASA Astrophysics Data System (ADS)

    Merrill, Frank E.

    Protons were first investigated as radiographic probes as high energy proton accelerators became accessible to the scientific community in the 1960s. Like the initial use of X-rays in the 1800s, protons were shown to be a useful tool for studying the contents of opaque materials, but the electromagnetic charge of the protons opened up a new set of interaction processes which complicated their use. These complications in combination with the high expense of generating protons with energies high enough to penetrate typical objects resulted in proton radiography becoming a novelty, demonstrated at accelerator facilities, but not utilized to their full potential until the 1990s at Los Alamos. During this time Los Alamos National Laboratory was investigating a wide range of options, including X-rays and neutrons, as the next generation of probes to be used for thick object flash radiography. During this process it was realized that the charge nature of the protons, which was the source of the initial difficulty with this idea, could be used to recover this technique. By introducing a magnetic imaging lens downstream of the object to be radiographed, the blur resulting from scattering within the object could be focused out of the measurements, dramatically improving the resolution of proton radiography of thick systems. Imaging systems were quickly developed and combined with the temporal structure of a proton beam generated by a linear accelerator, providing a unique flash radiography capability for measurements at Los Alamos National Laboratory. This technique has now been employed at LANSCE for two decades and has been adopted around the world as the premier flash radiography technique for the study of dynamic material properties.

  6. Total Synthesis of Tetrahydrolipstatin and Stereoisomers via a Highly Regio- and Diastereoselective Carbonylation of Epoxyhomoallylic Alcohols

    PubMed Central

    2015-01-01

    A concise enantioselective synthesis of tetrahydrolipstatin (THL) and seven stereoisomers has been achieved. The synthesis of THL was accomplished in 10 steps and 31% overall yield from an achiral ynone. Key to the success of the approach is the use of a bimetallic [Lewis acid]+[Co(CO)4]− catalyst for a late-stage regioselective carbonylation of an enantiomerically pure cis-epoxide to a trans-β-lactone. The success of this route to THL and its stereoisomers also demonstrated the practicality of the carbonylation catalyst for complex molecule synthesis as well as its functional group compatibility. PMID:25004122

  7. Activation of Carbonyl-Containing Molecules with Solid Lewis Acids in Aqueous Media

    SciTech Connect

    Román-Leshkov, Yuriy; Davis, Mark E.

    2011-09-28

    Current interest in reacting carbonyl-containing molecules in aqueous media is primarily due to the growing emphasis on conversion of biomass to fuels and chemicals. Recently, solid Lewis acids have been shown to perform catalytic reactions with carbonyl-containing molecules such as sugars in aqueous media. Here, catalysis mediated by Lewis acids is briefly discussed, Lewis acid solids that perform catalysis in aqueous media are then described, and the review is concluded with a few comments on the outlook for the future.

  8. Synthesis of diversely substituted 2-(furan-3-yl)acetates from allenols through cascade carbonylations.

    PubMed

    He, Yan; Zhang, Xinying; Fan, Xuesen

    2015-11-21

    Novel synthesis of diversely substituted 2-(furan-3-yl)acetates via palladium-catalyzed one-pot multi-component reactions of allenols, aryl iodides, alcohols, and carbon monoxide has been developed. Notably, the formation of the title compounds features a cascade process combining carbonylation of aryl iodide, alcohoxyl carbonylation of the in situ formed allyl palladium complex, and intramolecular condensation of the α-hydroxyl enone intermediate. Moreover, the 2-(furan-3-yl)acetates obtained herein were found to be ready intermediates for the construction of the biologically significant naphtho[1,2-b]furan-5-ol scaffold. PMID:26399394

  9. 1,3-Dipolar Cycloaddition Reactions of Azomethine Ylides with Carbonyl Dipolarophiles Yielding Oxazolidine Derivatives.

    PubMed

    Meyer, Adam G; Ryan, John H

    2016-01-01

    We provide a comprehensive account of the 1,3-dipolar cycloaddition reactions of azomethine ylides with carbonyl dipolarophiles. Many different azomethine ylides have been studied, including stabilized and non-stabilized ylides. Of the carbonyl dipolarophiles, aldehydes including formaldehyde are the most studied, although there are now examples of cycloadditions with ketones, ketenes and carboxyl systems, in particular isatoic anhydrides and phthalic anhydrides. Intramolecular cycloadditions with esters can also occur under certain circumstances. The oxazolidine cycloadducts undergo a range of reactions triggered by the ring-opening of the oxazolidine ring system. PMID:27455230

  10. Are protons nonidentical fermions?

    SciTech Connect

    Mart, T.

    2014-09-25

    We briefly review the progress of our investigation on the electric (charge) radius of the proton. In order to explain the recently measured proton radius, which is significantly smaller than the standard CODATA value, we assume that the real protons radii are not identical, they are randomly distributed in a certain range. To obtain the measured radius we average the radii and fit both the mean radius and the range. By using an averaged dipole form factor we obtain the charge radius r{sub E} = 0.8333 fm, in accordance with the recent measurement of the Lamb shift in muonic hydrogen.

  11. Synthesis of 3,3'-carbonyl-bis(chromones) and their activity as mammalian alkaline phosphatase inhibitors.

    PubMed

    Miliutina, Mariia; Ejaz, Syeda Abida; Iaroshenko, Viktor O; Villinger, Alexander; Iqbal, Jamshed; Langer, Peter

    2016-01-14

    Hitherto unknown 3,3'-carbonyl-bis(chromones) 8, dimeric chromones bridged by a carbonyl group, were prepared by reaction of chromone-3-carboxylic acid chloride with 3-(dimethylamino)-1- (2-hydroxyphenyl)-2-propen-1-ones 9. The method is generally applicable for the synthesis of novel symmetrical or non-symmetrical products which were found to inhibit mammalian alkaline phosphatases. PMID:26490672

  12. Tandem semi-hydrogenation/isomerization of propargyl alcohols to saturated carbonyl analogues by dodecanethiolate-capped palladium nanoparticle catalysts†

    PubMed Central

    Gavia, Diego J.; Koeppen, Jordan; Sadeghmoghaddam, Elham; Shon, Young-Seok

    2016-01-01

    The efficient one-pot conversion of propargyl alcohols to their saturated carbonyl analogues is carried out for the first time using metal nanoparticle catalysts, dodecanethiolate-capped Pd nanoparticles. Kinetic studies reveal that the reaction progresses through a semi-hydrogenation intermediate (allyl alcohols) followed by isomerization to carbonyls.

  13. DEVELOPMENT AND APPLICATION OF A SENSITIVE METHOD TO DETERMINE CONCENTRATIONS OF ACROLEIN AND OTHER CARBONYLS IN AMBIENT AIR

    EPA Science Inventory

    The sampler developed by Charles and Cahill, with Dr. Vincent Seaman, consists of a custom-built glass mist chamber in which air enters at a high flow rate and carbonyls are trapped in a solution of sodium bisulfite as carbonyl-bisulfite adducts. This reaction is rapid (on ...

  14. Ruthenium nitrosyls derived from polypyridine ligands with carboxamide or imine nitrogen donor(s): isoelectronic complexes with different NO photolability.

    PubMed

    Rose, Michael J; Patra, Apurba K; Alcid, Eric A; Olmstead, Marylin M; Mascharak, Pradip K

    2007-03-19

    As part of our search for photoactive ruthenium nitrosyls, a set of {RuNO}6 nitrosyls has been synthesized and structurally characterized. In this set, the first nitrosyl [(SBPy3)Ru(NO)](BF4)3 (1) is derived from a polypyridine Schiff base ligand SBPy3, while the remaining three nitrosyls are derived from analogous polypyridine ligands containing either one ([(PaPy3)Ru(NO)](BF4)2 (2)) or two ([(Py3P)Ru(NO)]BF4 (3) and [(Py3P)Ru(NO)(Cl)] (4)) carboxamide group(s). The coordination structures of 1 and 2 are very similar except that in 2, a carboxamido nitrogen is coordinated to the ruthenium center in place of an imine nitrogen in case of 1. In 3 and 4, the ruthenium center is coordinated to two carboxamido nitrogens in the equatorial plane and the bound NO is trans to a pyridine nitrogen (in 3) and chloride (in 4), respectively. Complexes 1-3 contain N6 donor set, and the NO stretching frequencies (nuNO) correlate well with the N-O bond distances. All four diamagnetic {RuNO}(6) nitrosyls are photoactive and release NO rapidly upon illumination with low-intensity (5-10 mW) UV light. Interestingly, photolysis of 1 generates the diamagnetic Ru(II) photoproduct [(SBPy3)Ru(MeCN)](2+) while 2-4 afford paramagnetic Ru(III) species in MeCN solution. The quantum yield values of NO release under UV illumination (lambda(max) = 302 nm) lie in the range 0.06-0.17. Complexes 3 and 4 also exhibit considerable photoactivity under visible light. The efficiency of NO release increases in the order 2 < 3 < 4, indicating that photorelease of NO is facilitated by (a) the increase in the number of coordinated carboxamido nitrogen(s) and (b) the presence of negatively charged ligands (like chloride) trans to the bound NO. PMID:17315866

  15. Carbon and proton Overhauser DNP from MD simulations and ab initio calculations: TEMPOL in acetone.

    PubMed

    Küçük, Sami Emre; Biktagirov, Timur; Sezer, Deniz

    2015-10-14

    A computational analysis of the Overhauser effect is reported for the proton, methyl carbon, and carbonyl carbon nuclei of liquid acetone doped with the nitroxide radical TEMPOL. A practical methodology for calculating the dynamic nuclear polarization (DNP) coupling factors by accounting for both dipole-dipole and Fermi-contact interactions is presented. The contribution to the dipolar spectral density function of nuclear spins that are not too far from TEMPOL is computed through classical molecular dynamics (MD) simulations, whereas the contribution of distant spins is included analytically. Fermi contacts are obtained by subjecting a few molecules from every MD snapshot to ab initio quantum mechanical calculations. Scalar interaction is found to be an essential part of the (13)C Overhauser DNP. While mostly detrimental to the carbonyl carbon of acetone it is predicted to result in large enhancements of the methyl carbon signal at magnetic fields of 9 T and beyond. In contrast, scalar coupling is shown to be negligible for the protons of acetone. The additional influence of proton polarization on the carbon DNP (three-spin effect) is also analyzed computationally. Its effect, however, is concluded to be practically insignificant for liquid acetone. PMID:26343351

  16. THEORY OF PROTON EMITTERS

    SciTech Connect

    P. TALOU

    2000-08-01

    Modern theoretical methods used to interpret recent experimental data on ground-state proton emission near the proton drip line are reviewed. Most of them are stationary and are aimed to compute proton decay widths {Gamma}{sub p} only. Comparison is made between these approaches before being compared to experimental data. Our time-dependent approach based on the numerical solution of the time-dependent Schroedinger equation (TDSE) for initial quasi-stationary single-proton states is then introduced. It is shown that much deeper insights into the physics of this clean multidimensional quantum tunneling effect can be accessed, and that in addition to {Gamma}{sub p}, other physical quantities could be tested experimentally, offering new stringent tests on nuclear physics models away from the valley of {beta}-stability. Finally, the necessity of using the TDSE approach in more complex, dynamical, problems is demonstrated.

  17. The Proton Radius Puzzle

    NASA Astrophysics Data System (ADS)

    Downie, E. J.

    2016-03-01

    The proton radius puzzle is the difference between the proton radius as measured with electron scattering and in the excitation spectrum of atomic hydrogen, and that measured with muonic hydrogen spectroscopy. Since the inception of the proton radius puzzle in 2010 by the measurement of Pohl et al.[1], many possible resolutions to the puzzle have been postulated, but, to date, none has been generally accepted. New data are therefore necessary to resolve the issue. We briefly review the puzzle, the proposed solutions, and the new electron scattering and spectroscopy experiments planned and underway. We then introduce the MUSE experiment, which seeks to resolve the puzzle by simultaneously measuring elastic electron and muon scattering on the proton, in both charge states, thereby providing new information to the puzzle. MUSE addresses issues of two-photon effects, lepton universality and, possibly, new physics, while providing simultaneous form factor, and therefore radius, measurements with both muons and electrons.

  18. Apparatus for proton radiography

    DOEpatents

    Martin, Ronald L.

    1976-01-01

    An apparatus for effecting diagnostic proton radiography of patients in hospitals comprises a source of negative hydrogen ions, a synchrotron for accelerating the negative hydrogen ions to a predetermined energy, a plurality of stations for stripping extraction of a radiography beam of protons, means for sweeping the extracted beam to cover a target, and means for measuring the residual range, residual energy, or percentage transmission of protons that pass through the target. The combination of information identifying the position of the beam with information about particles traversing the subject and the back absorber is performed with the aid of a computer to provide a proton radiograph of the subject. In an alternate embodiment of the invention, a back absorber comprises a plurality of scintillators which are coupled to detectors.

  19. Proton channel models

    PubMed Central

    Pupo, Amaury; Baez-Nieto, David; Martínez, Agustín; Latorre, Ramón; González, Carlos

    2014-01-01

    Voltage-gated proton channels are integral membrane proteins with the capacity to permeate elementary particles in a voltage and pH dependent manner. These proteins have been found in several species and are involved in various physiological processes. Although their primary topology is known, lack of details regarding their structures in the open conformation has limited analyses toward a deeper understanding of the molecular determinants of their function and regulation. Consequently, the function-structure relationships have been inferred based on homology models. In the present work, we review the existing proton channel models, their assumptions, predictions and the experimental facts that support them. Modeling proton channels is not a trivial task due to the lack of a close homolog template. Hence, there are important differences between published models. This work attempts to critically review existing proton channel models toward the aim of contributing to a better understanding of the structural features of these proteins. PMID:24755912

  20. Proton beam therapy facility

    SciTech Connect

    Not Available

    1984-10-09

    It is proposed to build a regional outpatient medical clinic at the Fermi National Accelerator Laboratory (Fermilab), Batavia, Illinois, to exploit the unique therapeutic characteristics of high energy proton beams. The Fermilab location for a proton therapy facility (PTF) is being chosen for reasons ranging from lower total construction and operating costs and the availability of sophisticated technical support to a location with good access to patients from the Chicago area and from the entire nation. 9 refs., 4 figs., 26 tabs.

  1. Poly-Cross-Linked PEI Through Aromatically Conjugated Imine Linkages as a New Class of pH-Responsive Nucleic Acids Packing Cationic Polymers

    PubMed Central

    Chen, Shun; Jin, Tuo

    2016-01-01

    Cationic polyimines polymerized through aromatically conjugated bis-imine linkages and intra-molecular cross-linking were found to be a new class of effective transfection materials for their flexibility in structural optimization, responsiveness to intracellular environment, the ability to facilitate endosome escape and cytosol release of the nucleic acids, as well as self-metabolism. When three phthalaldehydes of different substitution positions were used to polymerize highly branched low-molecular weight polyethylenimine (PEI 1.8K), the product through ortho-phthalimines (named PPOP) showed significantly higher transfection activity than its two tere- and iso-analogs (named PPTP and PPIP). Physicochemical characterization confirmed the similarity of three polyimines in pH-responded degradability, buffer capacity, as well as the size and Zeta potential of the polyplexes formed from the polymers. A mechanistic speculation may be that the ortho-positioned bis-imine linkage of PPOP may only lead to the straight trans-configuration due to steric hindrance, resulting in larger loops of intra-polymer cross-linking and more flexible backbone. PMID:26869931

  2. Synthesis, vibrational spectral and nonlinear optical studies of N-(4-hydroxy-phenyl)-2-hydroxybenzaldehyde-imine: A combined experimental and theoretical investigation

    NASA Astrophysics Data System (ADS)

    Wang, Yufeng; Yu, Zongxue; Sun, Yuxi; Wang, Yishi; Lu, Lude

    2011-09-01

    The study of imine-bridged organics has been the one hot spot of photo-responsive material sciences in recent years. Herein we make a study of the synthesis, characteristics and potential application of N-(4-hydroxy-phenyl)-2-hydroxy-benzaldehyde-imine (HPHBI), C 13H 11NO 2. The studied compound was synthesized in one step by the condensation reaction of salicylaldehyde and 4-aminophenol in methanol solution, and characterized by single crystal X-ray diffraction, FT-IR and FT-Raman techniques with theoretical calculations at B3LYP/6-31G(d) level. The molecule adopts trans configuration about central C dbnd6 N bond with intramolecular hydrogen bonding, and the adjacent molecules form wave-shaped structure linked by strong intermolecular hydrogen bonding mechanism along b axis. The vibrational spectra have been precisely assigned with the aid of theoretical frequencies. Furthermore, the thermodynamic properties have been obtained by the theoretical vibrational analysis for HPHBI. The total linear polarizability and first-order hyperpolarizabilities calculated on the studied compound respectively present 25.378 Å 3 and 1.655 × 10 -29 cm 5/esu, which indicates the compound has relatively good nonlinear optical property.

  3. PROTON MICROSCOPY AT FAIR

    SciTech Connect

    Merrill, F. E.; Mariam, F. G.; Golubev, A. A.; Turtikov, V. I.; Varentsov, D.

    2009-12-28

    Proton radiography was invented in the 1990's at Los Alamos National Laboratory (LANL) as a diagnostic to study dynamic material properties under extreme pressures, strain and strain rate. Since this time hundreds of dynamic proton radiography experiments have been performed at LANL and a facility has been commissioned at the Institute for Theoretical and Experimental Physics (ITEP) in Russia for similar applications in dynamic material studies. Recently an international effort has investigated a new proton radiography capability for the study of dynamic material properties at the Facility for Anti-proton and Ion Research (FAIR) located in Darmstadt, Germany. This new Proton microscope for FAIR(PRIOR) will provide radiographic imaging of dynamic systems with unprecedented spatial, temporal and density resolution, resulting in a window for understanding dynamic material properties at new length scales. It is also proposed to install the PRIOR system at the GSI Helmholtzzentrum fuer Schwerionenforschung before installation at FAIR for dynamic experiments with different drivers including high explosives, pulsed power and lasers. The design of the proton microscope and expected radiographic performance is presented.

  4. Synthesis, spectroscopic characterizations, crystal structures and DFT studies of nalidixic acid carbonyl hydrazones derivatives

    NASA Astrophysics Data System (ADS)

    Bergamini, F. R. G.; Ribeiro, M. A.; Lancellotti, M.; Machado, D.; Miranda, P. C. M. L.; Cuin, A.; Formiga, A. L. B.; Corbi, P. P.

    2016-09-01

    This article describes the synthesis and characterization of the 1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbohydrazide (hzd) and six carbonyl hydrazones derivatives of the nalidixic with 1H-pyrrol-2-ylmethylidene (hpyrr), 1H-imidazol-2-ylmethylidene (h2imi), pyridin-2-ylmethylidene (h2py), pyridin-3-ylmethylidene (h3py), pyridin-4-ylmethylidene(h4py) and (2-hydroxyphenyl)methylidene (hsali). The carbonyl hydrazones were characterized by elemental and ESI-QTOF-MS analyses, IR and detailed NMR spectroscopic measurements. The 2D NMR experiments allowed the unambiguous assignment of the hydrogen, carbon and nitrogen atoms, which have not been reported for nalidixic acid carbonyl hydrazone derivatives so far. Crystal structures of hzd and the new carbonyl hydrazones h2imi, hpyrr and h3py were determined by X-ray diffraction studies. Although the synthesis of hzd was reported decades ago, the hzd crystal structure have not been reported yet. Geometric optimizations of all the characterized structures were performed with the aid of DFT studies. Despite the fact that the hydrazones with 2-pyridine carboxylic acid (h2py) and salicyl aldehyde (hsali) were already reported by literature, a detailed spectroscopic study followed by DFT studies are also reported for such compounds in this manuscript. Antimicrobial studies of the compounds are also presented.

  5. Palladium-catalyzed carbonylative synthesis of quinazolinones from 2-aminobenzamide and aryl bromides.

    PubMed

    Wu, Xiao-Feng; He, Lin; Neumann, Helfried; Beller, Matthias

    2013-09-16

    C from CO! A straightforward procedure for the carbonylative synthesis of quinazolinones from readily available 2-aminobenzamide and aryl bromides has been developed. In the presence of a palladium catalyst, various quinazolinones were produced in moderate to excellent yields. Remarkably, no chromatography was needed for purification (see scheme). PMID:24175339

  6. HYDROGENATION OF UNSATURATED CARBONYLS IN SCCO2 AS REACTION MEDIUM OVER NI-SUPPORTED CATALYSTS

    EPA Science Inventory

    Selective hydrogenation of a, a unsaturated carbonyls where molecules containing C=C and C=O double bonds has both practical importance for fine chemicals industry and theoretical significance. Various studies are reported to enhance the selective hydrogenation of C=O over group...

  7. Magnetic Silica-Supported Ruthenium Nanoparticles: An Efficient Catalyst for Transfer Hydrogenation of Carbonyl Compounds

    EPA Science Inventory

    One-pot synthesis of ruthenium nanoparticles on magnetic silica is described which involve the in situ generation of magnetic silica (Fe3O4@ SiO2) and ruthenium nano particles immobilization; the hydration of nitriles and transfer hydrogenation of carbonyl compounds occurs in hi...

  8. α-Regioselective Barbier Reaction of Carbonyl Compounds and Allyl Halides Mediated by Praseodymium.

    PubMed

    Wu, San; Li, Ying; Zhang, Songlin

    2016-09-01

    The first utility of praseodymium as a mediating metal in the Barbier reaction of carbonyl compounds with allyl halides was reported in this paper. In contrast to the traditional metal-mediated or catalyzed Barbier reactions, exclusive α-adducts were obtained in this one-pot reaction with a broad scope of substrates and feasible reaction conditions. PMID:27490708

  9. 40 CFR 721.1620 - Benzenesulfonamide, alkylphenyl substituted phenyl substituted carbonyl- (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... phenyl substituted carbonyl- (PMN P-00-368) is subject to reporting under this section for the... in § 721.125(a), (b), (c), (d), (f), (g), (h), and (k) are applicable to manufacturers, importers... ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF...

  10. 40 CFR 721.1620 - Benzenesulfonamide, alkylphenyl substituted phenyl substituted carbonyl- (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... phenyl substituted carbonyl- (PMN P-00-368) is subject to reporting under this section for the... in § 721.125(a), (b), (c), (d), (f), (g), (h), and (k) are applicable to manufacturers, importers... ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF...

  11. 40 CFR 721.1620 - Benzenesulfonamide, alkylphenyl substituted phenyl substituted carbonyl- (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... phenyl substituted carbonyl- (PMN P-00-368) is subject to reporting under this section for the... in § 721.125(a), (b), (c), (d), (f), (g), (h), and (k) are applicable to manufacturers, importers... ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF...

  12. 40 CFR 721.1620 - Benzenesulfonamide, alkylphenyl substituted phenyl substituted carbonyl- (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... phenyl substituted carbonyl- (PMN P-00-368) is subject to reporting under this section for the... in § 721.125(a), (b), (c), (d), (f), (g), (h), and (k) are applicable to manufacturers, importers... ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF...

  13. Carbonyl clusters of transition metals on oxide supports as heterogeneous catalysts for hydrocarbon synthesis

    SciTech Connect

    Kuznetsov, B.N.; Koval`chuk, V.I.

    1995-05-01

    The methods of preparation of heterogeneous catalysts by immobilization of carbonyl clusters of transition metals on oxide supports, as well as the study of the state of supported compounds and their catalytic properties in CO hydrogenation and olefin hydroformulation are briefly reviewed.

  14. [Determination of major carbonyls in mainstream smoke by rapid column high performance liquid chromatography].

    PubMed

    Huang, Yun; Wang, Yigeng; Miao, Mingming; Zhao, Qihua; Yang, Guangyu

    2007-03-01

    Abstract: The determination of major carbonyl compounds in mainstream cigarette smoke by rapid column high performance liquid chromatography was investigated. The cigarette smoke was collected using a Cambridge filter treated with acidic solution of 2, 4-dinitrophenyl-hydrazine. Formaldehyde, acetaldehyde, acetone, acrolein, propionaldehyde, crotonaldehyde, 2-butanone and butyraldehyde were extracted from the Cambridge filter with 50 mL of 2% pyridine acetonitrile solution. The carbonyl compounds in samples were separated on a ZORBAX Stable Bound rapid column (50 mm x 4. 6 mm, 1. 8 microm) in approximately seven minutes and then determined by high performance liquid chromatography with a diode array detector. The average recoveries were in the range of 89. 1% to 99. 2% and the relative standard deviations (RSDs) were generally below 6. 0%. The eight carbonyl compounds in the mainstream smoke of five brands of cigarettes were determined using this method. This method is faster, simpler and consumes less solvent. It is suitable for rapid analysis of carbonyl compounds in mainstream cigarette smoke. PMID:17580693

  15. Palladium/copper-catalyzed oxidative C-H alkenylation/N-dealkylative carbonylation of tertiary anilines.

    PubMed

    Shi, Renyi; Lu, Lijun; Zhang, Hua; Chen, Borui; Sha, Yuchen; Liu, Chao; Lei, Aiwen

    2013-09-27

    C-H/C-N activation: The first palladium/copper-catalyzed aerobic oxidative C-H alkenylation/N-dealkylative carbonylation of tertiary anilines has been developed. Various functional groups were tolerated and acrylic ester could also be suitable substrates. This transformation provided efficient and straightforward synthesis of biologically active 3-methyleneindolin-2-one derivatives from cheap and simple substrates. PMID:23946242

  16. Formation of phenol under conditions of the reaction of oxidative carbonylation of benzene to benzoic acid

    SciTech Connect

    Kalinovsky, I.O.; Leshcheva, A.N.; Pogorelov, V.V.; Gelbshtein, A.I.

    1993-12-31

    This paper describes conditions for the oxidation of benzene to phenol. It is shown that a reaction mixture of water, carbon monoxide, and oxygen are essential to the oxidation. The oxidation is a side reaction found to occur during the oxidative carbonylation of benzene to benzoic acid in a medium of trifluoroacetic acid.

  17. Trends of ambient carbonyl compounds in the urban environment of Hong Kong

    NASA Astrophysics Data System (ADS)

    Sin, Della W. M.; Wong, Yiu-Chung; Louie, Peter K. K.

    The concentrations of C 1-C 8 carbonyl compounds were measured at two urban sites in Hong Kong from October 1997 to September 2000. The daily total carbonyl concentrations were found to range from 2.4 to 37 μg m -3. Formaldehyde was the most abundant species, which comprised from 36 to 43% of the total detected carbonyls, followed by acetaldehyde (18-21%) and acetone (8-20%). The highest 24-hour average concentrations measured were 10 and 7.7 μg m -3 for formaldehyde and acetaldehyde, respectively. Seasonal and temporal variations in the concentrations of formaldehyde and acetaldehyde were not obvious, but lowest concentrations often occurred from June to August. The mean formaldehyde/acetaldehyde molar ratios at the two sites in summer (2.8±1.1 and 2.5±1.2) were significantly higher ( p⩽0.01) than those in winter periods (1.9±0.6 and 2.0±0.6). The phenomena were explained by influences of both photochemical reactions and local meteorological conditions. Better correlations between formaldehyde and acetaldehyde, and between NO x and each of the two major carbonyls were obtained in winter periods indicating direct vehicular emissions were the principal sources. The ambient formaldehyde and acetaldehyde concentrations in the urban atmosphere of Hong Kong were within the normal ranges reported in the literature for other urban sites world-wide.

  18. Magnetically Recoverable Supported Ruthenium Catalyst for Hydrogenation of Alkynes and Transfer Hydrogenation of Carbonyl Compounds

    EPA Science Inventory

    A ruthenium (Ru) catalyst supported on magnetic nanoparticles (NiFe2O4) has been successfully synthesized and used for hydrogenation of alkynes at room temperature as well as transfer hydrogenation of a number of carbonyl compounds under microwave irradiation conditions. The cata...

  19. Direct photolysis of carbonyl compounds dissolved in cloud and fog~droplets

    NASA Astrophysics Data System (ADS)

    Epstein, S. A.; Tapavicza, E.; Furche, F.; Nizkorodov, S. A.

    2013-09-01

    Gas-phase photolysis is an important tropospheric sink for many carbonyl compounds; however the significance of direct photolysis of these compounds dissolved in cloud and fog droplets is uncertain. We develop a theoretical approach to assess the importance of aqueous photolysis for a series of carbonyls that possess carboxyl and hydroxyl functional groups by comparison with rates of other atmospheric processes. We use computationally and experimentally derived effective Henry's law constants, hydration equilibrium parameters, aqueous hydroxyl radical (OH) rate constants, and optical extinction coefficients to identify types of compounds that will (or will not) have competitive aqueous photolysis rates. We also present molecular dynamics simulations designed to estimate gas- and aqueous-phase extinction coefficients of unstudied atmospherically relevant compounds found in d-limonene and isoprene secondary organic aerosol. In addition, experiments designed to measure the photolysis rate of glyceraldehyde, an atmospherically relevant water-soluble organic compound, reveal that aqueous quantum yields are highly molecule-specific and cannot be extrapolated from measurements of structurally similar compounds. We find that only two out of the 92 carbonyl compounds investigated, pyruvic acid and acetoacetic acid, may have aqueous photolysis rates that exceed the rate of oxidation by dissolved OH. For almost all carbonyl compounds lacking α,β-conjugation that were investigated, atmospheric removal by direct photolysis in cloud and fog droplets can be neglected under typical atmospheric conditions.

  20. NEUROTOXICITY OF CARBONYL SULFIDE IN F344 RATS FOLLOWING INHALATION EXPOSURE FOR UP TO 12 WEEKS.

    EPA Science Inventory

    Carbonyl sulfide (COS) was nominated to the National Toxicology Program for testing in 1996 due to emissions levels and a lack of data. Through an inter-agency collaboration, functional and electrophysiological endpoints were included in the studies. This manuscript describes b...

  1. Modeling Vibrational Spectra of Ester Carbonyl Stretch in Water and DMSO Based on Molecular Dynamics Simulation.

    PubMed

    Fang, Bin; Wang, Tianjun; Chen, Xian; Jin, Tan; Zhang, Ruiting; Zhuang, Wei

    2015-09-24

    On the basis of molecular dynamics simulation, we model the ester carbonyl stretch FTIR signals of methyl acetate in D2O and DMSO. An ab initio map is constructed at the B3LYP/6-311++G** level to relate the carbonyl stretch frequency to the external electric field. Using this map, fluctuating Hamiltonian of the carbonyl stretch is constructed from the MD simulation trajectory. The IR spectra calculated based on this Hamiltonian are found to be in good agreement with the experiment. For methyl acetate in D2O, hydrogen bonding on alkoxy oxygen causes a blue shift of frequency, while that on carbonyl oxygen causes a red shift. Two peaks observed in FTIR signals originate from the balance of these two effects. Furthermore, in both D2O and DMSO solutions, correlations are found between the instantaneous electric field on C═O and the frequencies. Broader line width of the signal in D2O suggests a more inhomogeneous electric field distribution due to the complicated hydrogen-bonding environment. PMID:26335032

  2. Proteomic and Carbonylation Profile Analysis of Rat Skeletal Muscles following Acute Swimming Exercise

    PubMed Central

    Pietrovito, Laura; Fiaschi, Tania; Bini, Luca; Esposito, Fabio; Marini, Marina; Abruzzo, Provvidenza Maria; Gulisano, Massimo; Modesti, Alessandra

    2013-01-01

    Previous studies by us and other groups characterized protein expression variation following long-term moderate training, whereas the effects of single bursts of exercise are less known. Making use of a proteomic approach, we investigated the effects of acute swimming exercise (ASE) on protein expression and carbonylation patterns in two hind limb muscles: the Extensor Digitorum Longus (EDL) and the Soleus, mostly composed of fast-twitch and slow-twitch fibres, respectively. Carbonylation is one of the most common oxidative modifications of proteins and a marker of oxidative stress. In fact, several studies suggest that physical activity and the consequent increase in oxygen consumption can lead to increase in reactive oxygen and nitrogen species (RONS) production, hence the interest in examining the impact of RONS on skeletal muscle proteins following ASE. Results indicate that protein expression is unaffected by ASE in both muscle types. Unexpectedly, the protein carbonylation level was reduced following ASE. In particular, the analysis found 31 and 5 spots, in Soleus and EDL muscles respectively, whose carbonylation is reduced after ASE. Lipid peroxidation levels in Soleus were markedly reduced as well. Most of the decarbonylated proteins are involved either in the regulation of muscle contractions or in the regulation of energy metabolism. A number of hypotheses may be advanced to account for such results, which will be addressed in future studies. PMID:23967250

  3. Mechanisms of the Water-Gas Shift Reaction Catalyzed by Ruthenium Carbonyl Complexes.

    PubMed

    Liu, Naying; Guo, Ling; Cao, Zhaoru; Li, Wenli; Zheng, Xiaoli; Shi, Yayin; Guo, Juan; Xi, Yaru

    2016-04-21

    Density functional theory (DFT) is employed to study the water-gas shift (WGS) reaction in the gas phase for two complexes, Ru3(CO)12 and Ru(CO)5. Here we report four mechanisms of ruthenium carbonyl complexes catalyzed for WGS reaction. The energetic span model is applied to evaluate efficiency of the four catalytic pathways. Our results indicate that mechanism C and D show a good catalytic behavior, which is in agreement with results from the literature. The mechanism C and D not only include the important intermediate Ru3(CO)11H(-) but also exclude the energy-demanding OH(-) desorption and revise an unfavorable factor of the previous mechanism. Two complexes along mechanisms B have the highest turnover frequency (TOF) values. The trinuclear carbonyl complexes-Ru3(CO)12 is preferred over mononuclear carbonyl Ru(CO)5 by comparing TOF due to the fact that metal-metal cooperativity can enhance activity to the WGS reaction. In this work, the nature of interaction between transition states and intermediates is also analyzed by the detailed electronic densities of states, and we further clarify high catalytic activity of ruthenium carbonyl complexes as well. Our conclusions provide a guide to design catalysts for the WGS reaction. PMID:27064302

  4. The Potential of Carbonyl Sulfide as a Tracer for Gross Primary Productivity at Flux Tower Sites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Regional/continental scale studies of atmospheric carbonyl sulfide (OCS) seasonal dynamics and leaf level studies of plant OCS uptake have shown a close relationship to CO2 dynamics and uptake, suggesting potential for OCS as a tracer for gross primary productivity (GPP). Canopy CO2 and OCS differen...

  5. The Potential of Carbonyl Sulfide as a Proxy for Gross Primary Production at Flux Tower Sites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Regional and continental scale studies of the seasonal dynamics of atmospheric carbonyl sulfide (OCS) mole fractions and leaf-level studies of plant OCS exchange have shown a close relationship with those for CO2. CO2 has sinks and sources within terrestrial ecosystems, but the primary terrestrial e...

  6. Iron Dextran treatment does not induce serum protein carbonyls in the newborn pig

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Oxidation of serum proteins can lead to carbonyl formation which alters their function and is often associated with stress-related diseases. Since it is recommended that all pigs reared in modern production facilities be given supplemental iron at birth to prevent anemia, and metals can catalyze th...

  7. Towards a General Understanding of Carbonyl-Stabilised Ammonium Ylide-Mediated Epoxidation Reactions.

    PubMed

    Novacek, Johanna; Roiser, Lukas; Zielke, Katharina; Robiette, Raphaël; Waser, Mario

    2016-08-01

    The key factors for carbonyl-stabilised ammonium ylide-mediated epoxidation reactions were systematically investigated by experimental and computational means and the hereby obtained energy profiles provide explanations for the observed experimental results. In addition, we were able to identify the first tertiary amine-based chiral auxiliary that allows for high enantioselectivities and high yields for such epoxidation reactions. PMID:27381752

  8. Anisotropic thermal motion in transition-metal carbonyls from experiments and ab initio theory.

    PubMed

    Deringer, Volker L; Wang, Ai; George, Janine; Dronskowski, Richard; Englert, Ulli

    2016-09-21

    The thermal motion of atoms in crystals is quantified by anisotropic displacement parameters (ADPs). Here we show that dispersion-corrected periodic density-functional theory can be used to compute accurate ADPs for transition metal carbonyls, which serve as model systems for crystalline organometallic and coordination compounds. PMID:27513896

  9. Heterogeneous Chemistry of Carbonyls and Alcohols With Sulfuric Acid: Implications for Secondary Organic Aerosol Formation

    NASA Astrophysics Data System (ADS)

    Zhao, J.; Levitt, N.; Zhang, R.

    2006-12-01

    Recent environmental chamber studies have suggested that acid-catalyzed particle-phase reactions of organic carbonyls lead to multifold increases in secondary organic aerosol (SOA) mass and acid-catalyzed reactions between alcohols and aldehydes in the condensed phase lead to the formation of hemiacetals and acetals, also enhancing secondary organic aerosol growth. The kinetics and mechanism of the heterogeneous chemistry of carbonyls and alcohols with sulfuric acid, however, remain largely uncertain. In this talk, we present measurements of heterogeneous uptake of several carbonyls and alcohols on liquid H2SO4 in a wide range of acid concentrations and temperatures. The results indicate that uptake of larger carbonyls is explained by aldol condensation. For small dicarbonyls, heterogeneous reactions are shown to decrease with acidity and involve negligible formation of sulfate esters. Hydration and polymerization likely explain the measured uptake of such small dicarbonyls on H2SO4 and the measurements do not support an acid- catalyzed uptake. Atmospheric implications from our findings will be discussed.

  10. [pi] Backbonding in Carbonyl Complexes and Carbon-Oxygen Stretching Frequencies: A Molecular Modeling Exercise

    ERIC Educational Resources Information Center

    Montgomery, Craig D.

    2007-01-01

    An exercise is described that has illustrated the effect of various factors on [pi] backbonding to carbonyl ligands, where the students can view the molecular orbitals corresponding to the M-CO [pi] interaction as well as the competing interaction between the metal and co-ligands. The visual and hands-on nature of the modeling exercise has helped…

  11. Analysis of selected carbonyl oxidation products in wine by liquid chromatography with diode array detection.

    PubMed

    Elias, Ryan J; Laurie, V Felipe; Ebeler, Susan E; Wong, Jon W; Waterhouse, Andrew L

    2008-09-19

    A high performance liquid chromatography (HPLC) method for the detection and quantitation of acetaldehyde, glyceraldehyde, pyruvic acid, 2-ketoglutaric acid, and formaldehyde in wine, based on the formation of the 2,4-dinitrophenylhydrazones, is presented. These carbonyl compounds often result from the chemical oxidation of major wine components, and are known to affect flavor and color stability. Their analysis in wine is complicated due to their instability and their tendency to react reversibly with bisulfite to form alpha-hydroxysulfonates. Published methods that break down the sulfonates for the quantitation of total carbonyls in wine involve alkaline hydrolysis of sulfite-bound carbonyls, but we show, for the first time, that this alkaline treatment step significantly increases the concentration of carbonyls during analysis. A solution based on oxygen exclusion is described. The technique offers good specificity, reproducibility (%RSD 0.45-10.6), and limits of detection (1.29-7.53microgL(-1)). The method was successfully used to monitor concentration changes of these compounds in both white and red wines. PMID:18761127

  12. Identification of Protein Carbonyls in serum of the fetal and neonatal pig.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Oxidation of serum proteins leads to non-reversible carbonyl formation which alters their function and has long been associated with stress-related disease processes. The primary objective of this study was to identify oxidized serum protein biomarkers of metabolic stress in baby pigs. Protein carb...

  13. A structural role for arginine in proteins: multiple hydrogen bonds to backbone carbonyl oxygens.

    PubMed

    Borders, C L; Broadwater, J A; Bekeny, P A; Salmon, J E; Lee, A S; Eldridge, A M; Pett, V B

    1994-04-01

    We propose that arginine side chains often play a previously unappreciated general structural role in the maintenance of tertiary structure in proteins, wherein the positively charged guanidinium group forms multiple hydrogen bonds to backbone carbonyl oxygens. Using as a criterion for a "structural" arginine one that forms 4 or more hydrogen bonds to 3 or more backbone carbonyl oxygens, we have used molecular graphics to locate arginines of interest in 4 proteins: Arg 180 in Thermus thermophilus manganese superoxide dismutase, Arg 254 in human carbonic anhydrase II, Arg 31 in Streptomyces rubiginosus xylose isomerase, and Arg 313 in Rhodospirillum rubrum ribulose-1,5-bisphosphate carboxylase/oxygenase. Arg 180 helps to mold the active site channel of superoxide dismutase, whereas in each of the other enzymes the structural arginine is buried in the "mantle" (i.e., inside, but near the surface) of the protein interior well removed from the active site, where it makes 5 hydrogen bonds to 4 backbone carbonyl oxygens. Using a more relaxed criterion of 3 or more hydrogen bonds to 2 or more backbone carbonyl oxygens, arginines that play a potentially important structural role were found in yeast enolase, Bacillus stearothermophilus glyceraldehyde-3-phosphate dehydrogenase, bacteriophage T4 and human lysozymes, Enteromorpha prolifera plastocyanin, HIV-1 protease, Trypanosoma brucei brucei and yeast triosephosphate isomerases, and Escherichia coli trp aporepressor (but not trp repressor or the trp repressor/operator complex).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8003972

  14. NEAR-CONTINUOUS MEASUREMENT OF HYDROGEN SULFIDE AND CARBONYL SULFIDE BY AN AUTOMATIC GAS CHROMATOGRAPH

    EPA Science Inventory

    An automatic gas chromatograph with a flame photometric detector that samples and analyzes hydrogen sulfide and carbonyl sulfide at 30-s intervals is described. Temperature programming was used to elute trace amounts of carbon disulfide present in each injection from a Supelpak-S...

  15. NMR Studies of Structure-Reactivity Relationships in Carbonyl Reduction: A Collaborative Advanced Laboratory Experiment

    ERIC Educational Resources Information Center

    Marincean, Simona; Smith, Sheila R.; Fritz, Michael; Lee, Byung Joo; Rizk, Zeinab

    2012-01-01

    An upper-division laboratory project has been developed as a collaborative investigation of a reaction routinely taught in organic chemistry courses: the reduction of carbonyl compounds by borohydride reagents. Determination of several trends regarding structure-activity relationship was possible because each student contributed his or her results…

  16. Exotic Protonated Species Produced by UV-Induced Photofragmentation of a Protonated Dimer: Metastable Protonated Cinchonidine.

    PubMed

    Alata, Ivan; Scuderi, Debora; Lepere, Valeria; Steinmetz, Vincent; Gobert, Fabrice; Thiao-Layel, Loïc; Le Barbu-Debus, Katia; Zehnacker-Rentien, Anne

    2015-10-01

    A metastable protonated cinchona alkaloid was produced in the gas phase by UV-induced photodissociation (UVPD) of its protonated dimer in a Paul ion trap. The infrared multiple photon dissociation (IRMPD) spectrum of the molecular ion formed by UVPD was obtained and compared to DFT calculations to characterize its structure. The protonation site obtained thereby is not accessible by classical protonation ways. The protonated monomer directly formed in the ESI source or by collision-induced dissociation (CID) of the dimer undergoes protonation at the most basic alkaloid nitrogen. In contrast, protonation occurs at the quinoline aromatic ring nitrogen in the UVPD-formed monomer. PMID:26347997

  17. Novel polyamide-imines

    NASA Technical Reports Server (NTRS)

    Dezern, James F.

    1988-01-01

    An account is given of tough, thermally stable linear polyimides containing amide linkages that recommend themselves for use in high temperature-resistant films and coatings as well as matrix resins for graphite-reinforced structures. Four such polymers were synthesized from unsubstituted amide diamines, and two others from N-substituted amide diamines. High inherent viscosities and glass transition temperatures were obtained. The films exhibit good resistance to organic solvents. Films of the 4,4-prime-isomer polyamide-imide yielded exceptionally high modulus and toughness during impact evaluation.

  18. Regenerable solid imine sorbents

    DOEpatents

    Gray, McMahan; Champagne, Kenneth J.; Fauth, Daniel; Beckman, Eric

    2013-09-10

    Two new classes of amine-based sorbents are disclosed. The first class comprises new polymer-immobilized tertiary amine sorbents; the second class new polymer-bound amine sorbents. Both classes are tailored to facilitate removal of acid anhydrides, especially carbon dioxide (CO.sub.2), from effluent gases. The amines adsorb acid anhydrides in a 1:1 molar ratio. Both classes of amine sorbents adsorb in the temperature range from about 20.degree. C. upwards to 90.degree. C. and can be regenerated by heating upwards to 100.degree. C.

  19. Hepatocellular carcinoma protein carbonylation in virus C and metabolic syndrome patients.

    PubMed

    Martin, Fernando Ariel; Mebarki, Mouniya; Paradis, Valérie; Friguet, Bertrand; Radman, Miroslav

    2014-10-01

    Metabolic syndrome (MS) is becoming the leading cause of chronic liver diseases worldwide. Hepatocellular carcinoma (HCC) development in MS is peculiar compared to other chronic liver diseases. Carbohydrate and lipid metabolic imbalance in MS increase reactive oxygen species damaging proteins. In the present work we study the difference in protein oxidative damage (carbonylation) in human HCC derived from virus C infection (VHC) and from MS (MS_HCC) as the only subjacent cause. We selected a patient cohort containing of 10 non-tumoral and 10 tumoral liver resections in each study group (virus C and MS HCC) based on clinical patient history and histological parameters. Protein samples were labeled to saturation using CF 647-hydrazide™ dye. This approach allows us to perform carbonyl detection alongside with a DIGE experiment. We detected a total of 1184 spots with 36 differentially expressed proteins and 47 spots differentially carbonylated between VHC and MS_HCC (fold change >1.5, p<0.05). VHC up-regulated proteins are involved in signaling pathways related to cancer development such as signaling by EGFR, Wnt, Cdc20 and cell cycle. Further, up-regulated proteins in MS HCC, are implicated in metabolism of carbohydrates and amino acids. Differential carbonylation analysis between VHC and MS_HCC showed protein damage in proteins such as glucose phosphate isomerase, isocitrate dehydrogenase, and 3-ketoacyl-CoA thiolase. Higher protein carbonylation in MS_HCC samples was observed in proteins involved in redox response and lipid metabolism. In conclusion, the observed difference in protein oxidative damage between MS and Virus C derived carcinoma could account for the different cancer development pathway. PMID:26461368

  20. Oxi-DIGE: A novel proteomic approach for detecting and quantifying carbonylated proteins.

    PubMed

    Baraibar, Martin; Ladouce, Romain; Friguet, Bertrand

    2014-10-01

    Proteins are involved in key cellular functions and our health and wellness depends on their quality. Accumulation of oxidatively damaged proteins is a hallmark of deleterious processes such increased oxidative stress, chronic inflammation, ageing and age-related diseases. Thus, quantifying and identifying oxidized proteins is a biomarker of choice for monitoring biological ageing and/or the efficiency of anti-oxidant, ant-inflammatory and anti-ageing therapies. However, the absence of reliable tools for analyses has inhibited its establishment as the gold standard for measuring the efficacy of anti-ageing and age related diseases interventions. Herein, we present a novel proteomics technology, named Oxi-DIGE?, which provides a significant improvement in terms of specificity, reproducibility and statistical support for proteomic analysis of carbonylated proteins. In Oxi-DIGE, protein carbonyls are labelled with fluorescent hydrazide probes that bind specifically to carbonyl groups in proteins. Experimental groups (e.g. control and experimental samples) are labelled with different flurophore-binded hydrazides that fluoresce light at different wavelengths, producing different colour fluorescence. Thus samples from different experimental groups are co-resolved on a single 2D gel. Increased accuracy is provided due to: (i) reduced false positives by using an exogenous synthetic fluorescent tag; (ii) multiplexing, that is the possibility to run multiple samples on the same gel, (iii) the use of an internal standard on each gel which eliminates inter-gel variations and provides an increased statistical confidence. In addition, the resolution of the carbonyl groups is improved, forming distinct spots that can be identified by mass spectrometry. ?Patent Application (M. Baraibar, R. Ladouce., B. Friguet, A method for detecting and/or quantifying carbonylated proteins (WO/2012/175519) filed by UPMC and referring to the technology described in this abstract. PMID:26461312