WorldWideScience

Sample records for catalyzed carbonyl allylation

  1. Iridium-Catalyzed Allylic Substitution

    Science.gov (United States)

    Hartwig, John F.; Pouy, Mark J.

    Iridium-catalyzed asymmetric allylic substitution has become a valuable method to prepare products from the addition of nucleophiles at the more substituted carbon of an allyl unit. The most active and selective catalysts contain a phosphoramidite ligand possessing at least one arylethyl substituent on the nitrogen atom of the ligand. In these systems, the active catalyst is generated by a base-induced cyclometalation at the methyl group of this substituent to generate an iridium metalacycle bound by the COD ligand of the [Ir(COD)Cl]2 precursor and one additional labile dative ligand. Such complexes catalyze the reactions of linear allylic esters with alkylamines, arylamines, phenols, alcohols, imides, carbamates, ammonia, enolates and enolate equivalents, as well as typical stabilized carbon nucleophiles generated from malonates and cyanoesters. Iridium catalysts for enantioselective allylic substitution have also been generated from phosphorus ligands with substituents bound by heteroatoms, and an account of the studies of such systems, along with a description of the development of iridium catalysts is included.

  2. Palladium-catalyzed amination of allyl alcohols.

    Science.gov (United States)

    Ghosh, Raju; Sarkar, Amitabha

    2011-10-21

    An efficient catalytic amination of aryl-substituted allylic alcohols has been developed. The complex [(η(3)-allyl)PdCl](2) modified by a bis phosphine ligand, L, has been used as catalyst in the reaction that afforded a wide range of allyl amines in good to excellent yield under mild conditions.

  3. Green Synthesis and Regioselective Control of Sn/I2 Mediated Allylation of Carbonyl Compounds with Crotyl Halide in Water

    Institute of Scientific and Technical Information of China (English)

    ZHANG,Yan; ZHA,Zhang-Gen; ZHOU,Yu-Qing; WANG,Zhi-Yong

    2004-01-01

    @@ Barbier-type carbonyl allylation is particularly useful due to ease of operation and the availability and tractability of allylic substrates,[1] Metals such as indium, zinc and tin are often used as the mediator. Here we present a green approach toward the synthesis, that is, Sn/I2 mediated allylation of carbonyl compounds with crotyl halide in water.

  4. Nano-Aluminum Powder Mediated Allylation of Carbonyl Compounds in Aqueous Media

    Institute of Scientific and Technical Information of China (English)

    YUAN Shi-Zhen; LIU Jin

    2008-01-01

    A new and effective Barbier-Grignard allylation of aldehydes or ketones has been carried out with nano-aluminum powder in aqueous 0.1 mol·L-1 NH4Cl (aq.) under an atmosphere of nitrogen. Aromatic carbonyl compounds gave homoallylic alcohols in good yields. The effectiveness of reaction was strongly influenced by the steric environment surrounding the carbonyl group. Aliphatic carbonyl compounds proceeded in low yields. The dominant stereoisomer was an erythro-isomer when an ortho-hydroxyl carbonyl compound was reacted under such a reaction condition.

  5. Cp*Co(III)-Catalyzed Dehydrative C-H Allylation of 6-Arylpurines and Aromatic Amides Using Allyl Alcohols in Fluorinated Alcohols.

    Science.gov (United States)

    Bunno, Youka; Murakami, Nanami; Suzuki, Yudai; Kanai, Motomu; Yoshino, Tatsuhiko; Matsunaga, Shigeki

    2016-05-01

    Cp*Co(III)-catalyzed C-H allylation of various aromatic C-H bonds using allyl alcohols as allylating reagents is described. Improved reaction conditions using fluorinated alcohol solvents afforded efficient directed C-H allylation of 6-arylpurines, benzamides, and a synthetically useful Weinreb amide with good functional group compatibility.

  6. Redox-Neutral Rh(III)-Catalyzed Olefination of Carboxamides with Trifluoromethyl Allylic Carbonate.

    Science.gov (United States)

    Park, Jihye; Han, Sangil; Jeon, Mijin; Mishra, Neeraj Kumar; Lee, Seok-Yong; Lee, Jong Suk; Kwak, Jong Hwan; Um, Sung Hee; Kim, In Su

    2016-11-18

    The rhodium(III)-catalyzed olefination of various carboxamides with α-CF3-substituted allylic carbonate is described. This reaction provides direct access to linear CF3-allyl frameworks with complete trans-selectivity. In particular, a rhodium catalyst provided Heck-type γ-CF3-allylation products via the β-O-elimination of rhodacycle intermediate and subsequent olefin migration process.

  7. Ab Initio MO Studies on the Reaction Mechanism for Carbonyl Insertion Catalyzed by Carbonyl Cobalt Complex

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Ab initio method, under the effective core potential(ECP) approximation at HF/LANL2DZ level, has been employed to study the reaction mechanism of the carbonyl insertion of olefin hydroformylation catalyzed by a carbonyl cobalt HCo(CO)3. The two reaction paths have been discussed. The calculated potential energy barriers for the carbonyl migration and the ethyl group migration are 105.0 kJ/mol and 39.17 kJ/mol, respectively. The results indicate that the reaction path via ethyl migration is more energetically favorable than that via carbonyl insertion.

  8. Copper-Catalyzed SN2'-Selective Allylic Substitution Reaction of gem-Diborylalkanes.

    Science.gov (United States)

    Zhang, Zhen-Qi; Zhang, Ben; Lu, Xi; Liu, Jing-Hui; Lu, Xiao-Yu; Xiao, Bin; Fu, Yao

    2016-03-04

    A Cu/(NHC)-catalyzed SN2'-selective substitution reaction of allylic electrophiles with gem-diborylalkanes is reported. Different substituted gem-diborylalkanes and allylic electrophiles can be employed in this reaction, and various synthetic valuable functional groups can be tolerated. The asymmetric version of this reaction was initially researched with chiral N-heterocyclic carbene (NHC) ligands.

  9. Memory effects in palladium-catalyzed allylic Alkylations of 2-cyclohexen-1-yl acetate

    DEFF Research Database (Denmark)

    Svensen, Nina; Fristrup, Peter; Tanner, David Ackland;

    2007-01-01

    The objective of this work was to characterize the enantiospecificity of the allylic alkylation of enantioenriched 2-cyclohexen-1-yl acetate with the enolate ion of dimethyl malonate catalyzed by unsymmetrical palladium catalysts. The precatalysts employed were (eta(3)-allyl)PdLCl, where L is a m...

  10. Rh-Catalyzed Chemo- and Enantioselective Hydrogenation of Allylic Hydrazones.

    Science.gov (United States)

    Hu, Qiupeng; Hu, Yanhua; Liu, Yang; Zhang, Zhenfeng; Liu, Yangang; Zhang, Wanbin

    2017-01-23

    A highly efficient P-stereogenic diphosphine-rhodium complex was applied to the chemo- and enantioselective hydrogenation of allylic hydrazones for the synthesis of chiral allylic hydrazines in 89-96 % yields and with 82-99 % ee values. This methodology was successfully applied to the preparation of versatile chiral allylic amine derivatives.

  11. Copper-catalyzed regioselective allylic substitution reactions with indium organometallics.

    Science.gov (United States)

    Rodríguez, David; Sestelo, José Pérez; Sarandeses, Luis A

    2003-03-21

    The first nucleophilic allylic substitution reactions of triorganoindium compounds with allylic halides and phosphates are reported. The reactions of trialkyl- and triarylindium reagents with cinnamyl and geranyl halides and phosphates, with the aid of copper catalysis [Cu(OTf)(2)/P(OEt)(3)], are described. In general, the reaction proceeds efficiently to give good yields and regioselectively to afford the S(N)2' product.

  12. Additive-Free Pd-Catalyzed α-Allylation of Imine-Containing Heterocycles.

    Science.gov (United States)

    Kljajic, Marko; Puschnig, Johannes G; Weber, Hansjörg; Breinbauer, Rolf

    2017-01-06

    An additive-free Pd-catalyzed α-allylation of different imino-group-ontaining heterocycles is reported. The activation of α-CH pronucleophiles (pKa (DMSO) > 25) occurs without the addition of strong bases or Lewis acids using only the Pd/Xantphos catalyst system. The reaction scope has been studied for various 5- and 6-membered nitrogen-containing heterocycles (yields up to 96%). Mechanistic investigations suggest an initial allylation of the imine-N followed by a Pd-catalyzed formal aza-Claisen rearrangement.

  13. Direct activation of allylic alcohols in palladium catalyzed coupling reactions

    OpenAIRE

    Gümrükçü, Y.

    2014-01-01

    The direct use of allylic alcohols in substitution reactions without pre-activation of the hydroxyl-group into a better leaving group or the use of additional stoichiometric in situ activators remains challenging due to the poor leaving group ability of the hydroxyl-group. Hence, it is important to develop new methods to activate (bio-mass derived) allyl-alcohols, which allow ‘green’ chemical processes for a broad substrate range. This may have a considerable impact on the methodology for fin...

  14. Direct activation of allylic alcohols in palladium catalyzed coupling reactions

    NARCIS (Netherlands)

    Gümrükçü, Y.

    2014-01-01

    The direct use of allylic alcohols in substitution reactions without pre-activation of the hydroxyl-group into a better leaving group or the use of additional stoichiometric in situ activators remains challenging due to the poor leaving group ability of the hydroxyl-group. Hence, it is important to

  15. Palladium-catalyzed asymmetric allylic substitution of 2-arylcyclohexenol derivatives: asymmetric total syntheses of (+)-crinamine, (-)-haemanthidine, and (+)-pretazettine.

    Science.gov (United States)

    Nishimata, Toyoki; Sato, Yoshihiro; Mori, Miwako

    2004-03-19

    Much interest has been shown in Amaryllidaceae alkaloids as synthetic targets due to their wide range of biological activities. Over 100 alkaloids have been isolated from members of the Amaryllidaceae family; most of them can be classified into eight skeletally homogeneous groups. We have succeeded in the first asymmetric total syntheses of the crinane-type alkaloids (+)-crinamine (1), (-)-haemanthidine (2), and (+)-pretazettine (3). The starting cyclohexenylamine 14 was obtained from allyl phosphonate 11c by palladium-catalyzed asymmetric amination in 82% yield and with 74% ee. The product was recrystallized from MeOH. Interestingly, (-)-14 with 99% ee was obtained from the mother liquor (74% recovery). Intramolecular carbonyl-ene reaction of (-)-10 proceeds in a highly stereoselective manner to give hexahydroindole derivative 9 as the sole product. In the Lewis-acid-catalyzed carbonyl-ene reaction, an interesting rearrangement product, 20, was isolated in high yield. From 9, (+)-crinamine was synthesized. Thus, the asymmetric total synthesis of (+)-crinamine was achieved in 10 steps from 11c, and the overall yield is 19%. The total synthesis of (-)-haemanthidine was also achieved from 9 by a short sequence of steps.

  16. A Mechanistic Study of Direct Activation of Allylic Alcohols in Palladium Catalyzed Amination Reactions

    Directory of Open Access Journals (Sweden)

    Yasemin Gumrukcu

    2015-03-01

    Full Text Available We here report a computational approach on the mechanism of allylicamination reactions using allyl-alcohols and amines as the substrates and phosphoramidite palladium catalyst 1a, which operates in the presence of catalytic amount of 1,3-diethylurea as a co-catalyst. DFT calculations showed a cooperative hydrogen-bonding array between the urea moiety and the hydroxyl group of the allyl alcohol, which strengthens the hydrogen bond between the O-H moiety of the coordinated allyl-alcohol and the carbonyl-moiety of the ligand. This hydrogen bond pattern facilitates the (rate-limiting C-O oxidative addition step and leads to lower energy isomers throughout the catalytic cycle, clarifying the role of the urea-moiety.

  17. Rationalizing Ring-Size Selectivity in Intramolecular Pd-Catalyzed Allylations of Resonance-Stabilized Carbanions

    DEFF Research Database (Denmark)

    Norrby, Per-Ola; Mader, Mary M.; Vitale, Maxime

    2003-01-01

    Computational methods were applied to the Pd-catalyzed intramolecular allylations of resonance-stabilized carbanions obtained from amide and ketone substrates, with the aim of rationalizing the endo- vs. exo-selectivity in the cyclizations. In addition, ester substrates were prepared and subjecte...

  18. Palladium-catalyzed cross-coupling reactions of allylic halides and acetates with indium organometallics.

    Science.gov (United States)

    Rodríguez, David; Pérez Sestelo, José; Sarandeses, Luis A

    2004-11-12

    The palladium(0)-catalyzed cross-coupling reaction of allylic halides and acetates with indium organometallics is reported. In this synthetic transformation, triorganoindium compounds and tetraorganoindates (aryl, alkenyl, and methyl) react with cinnamyl and geranyl halides and acetates to afford the S(N)2 product regioselectively and in good yield. The reaction proceeds with net inversion of the stereochemical configuration.

  19. Enantioconvergent synthesis by sequential asymmetric Horner-Wadsworth-Emmons and palladium-catalyzed allylic substitution reactions

    DEFF Research Database (Denmark)

    Pedersen, Torben Møller; Hansen, E. Louise; Kane, John

    2001-01-01

    A new method for enantioconvergent synthesis has been developed. The strategy relies on the combination of an asymmetric Horner-Wadsworth-Emmons (HWE) reaction and a palladium-catalyzed allylic substitution. Different $alpha@-oxygen-substituted, racemic aldehydes were initially transformed...

  20. Surprisingly Mild Enolate-Counterion-Free Pd(0)-Catalyzed Intramolecular Allylic Alkylations

    DEFF Research Database (Denmark)

    Madec, David; Prestat, Guillaume; Martini, Elisabetta;

    2005-01-01

    Palladium-catalyzed intramolecular allylic alkylations of unsaturated EWG-activated amides can take place under phase-transfer conditions or in the presence of a crown ether. These new reaction conditions are milder and higher yielding than those previously reported. A rationalization for such an...

  1. Copper-catalyzed asymmetric allylic substitution reactions with organozinc and Grignard reagents

    NARCIS (Netherlands)

    Geurts, Koen; Fletcher, Stephen P.; van Zijl, Anthoni W.; Minnaard, Adriaan J.; Feringa, Ben L.; Bignall, H. E.; Jauncey, D. L.; Lovell, J. E. J.; Tzioumis, A. K.; Kedziora-Chudczer, L. L.; MacQuart, J. P.; Tingay, S. J.; Rayner, D. P.; Clay, R. W.

    2008-01-01

    Asymmetric allylic alkylations (AAAs) are among the most powerful C-C bond-forming reactions. We present a brief overview of copper-catalyzed AAAs with organometallic reagents and discuss our own contributions to this field. Work with zinc reagents and phosphoramidite ligands provided a framework fo

  2. SnCl2/Cu-Mediated Carbonyl Allylation Reaction in Water:Scope,Selectivity and Mechanism

    Institute of Scientific and Technical Information of China (English)

    TAN,Xiang-Hui(谭翔晖); HOU,Yong-Quan(侯永泉); LIU,Lei(刘磊); GUO,Qing-Xiang(郭庆祥)

    2004-01-01

    Copper was found to be able to promote the SnC12-mediated carbonyl allylation reactions in water,giving the corresponding homoallylic alcohol products in very high yields.Detailed studies showed that the reaction could be applied to a variety of carbonyl compounds including those with hydroxyl,amino and nitro groups.It was also found that this reaction showed good regioselectivities for some substrates.Furthermore,carefully controled experiments and in situ NMR measurements provided important insights into the mechanism of the newly developed reaction.

  3. Rh2(esp)2-catalyzed allylic and benzylic oxidations.

    Science.gov (United States)

    Wang, Yi; Kuang, Yi; Wang, Yuanhua

    2015-04-07

    The dirhodium(II) catalyst Rh2(esp)2 allows direct solvent-free allylic and benzylic oxidations by T-HYDRO with a remarkably low catalyst loading. This method is operationally simple and scalable at ambient temperature without the use of any additives. The high catalyst stability in these reactions may be attributed to a dirhodium(II,II) catalyst resting state, which is less prone to decomposition.

  4. Gold-catalyzed intermolecular coupling of sulfonylacetylene with allyl ethers: [3,3]- and [1,3]-rearrangements

    Directory of Open Access Journals (Sweden)

    Jungho Jun

    2013-08-01

    Full Text Available Gold-catalyzed intermolecular couplings of sulfonylacetylenes with allyl ethers are reported. A cooperative polarization of alkynes both by a gold catalyst and a sulfonyl substituent resulted in an efficient intermolecular tandem carboalkoxylation. Reactions of linear allyl ethers are consistent with the [3,3]-sigmatropic rearrangement mechanism, while those of branched allyl ethers provided [3,3]- and [1,3]-rearrangement products through the formation of a tight ion–dipole pair.

  5. IRC analysis of methanol carbonylation reaction catalyzed by rhodium complex

    Institute of Scientific and Technical Information of China (English)

    HAO Maorong; FENG Wenlin; JI Yongqiang; LEI Ming

    2004-01-01

    In the reaction cycle for methanol carbonylation catalyzed by Rh complex, the structure geometries of the reactant, intermediates, transition states and product of each elemental reaction have been studied by using the energy gradient method at HF/LANL2DZ level, and the changes of their potential profiles have also been calculated. Through IRC analyses of the transition states for each elemental reaction, it is confirmed that the various structure geometries obtained are stationary points on the cycle reaction pathway of methanol carbonylation catalyzed by Rh complex, and the changes are given in energies and structure geometries of the reactant molecules along the reaction pathway of lowest energy. It has been proposed that the geometrical conversions of intermediates play an important role during the cycle reaction. Through analyses of structure geometries, it has been suggested that, in addition to cis- and trans- structure exchange linkage of catalysis reactive species, the two pathways, cis- and trans-cata- lyzed cycle reactions, can also be linked through geometrical conversion of intermediates, of which the activation energy is 49.79 kJ/mol. Moreover, the reductive elimination elemental reaction may be neither cis-cycle nor trans- one, showing that the cycle reaction can be achieved through various pathways. However different the pathway, the oxidative addition elemental reaction of CH3I is the rate-controlling step.

  6. Lewis base catalyzed enantioselective allylic hydroxylation of Morita-Baylis-Hillman carbonates with water

    KAUST Repository

    Zhu, Bo

    2011-08-19

    A Lewis base catalyzed allylic hydroxylation of Morita-Baylis-Hillman (MBH) carbonates has been developed. Various chiral MBH alcohols can be synthesized in high yields (up to 99%) and excellent enantioselectivities (up to 94% ee). This is the first report using water as a nucleophile in asymmetric organocatalysis. The nucleophilic role of water has been verified using 18O-labeling experiments. © 2011 American Chemical Society.

  7. Synthesis of Aminophosphine Ligands with Binaphthyl Backbones for Silver(I)-catalyzed Enantioselective Allylation of Benzaldehyde

    Institute of Scientific and Technical Information of China (English)

    WANG,Yi(王以); JI,Bao-Ming(吉保明); DING,Kui-Ling(丁奎岭)

    2002-01-01

    A series of aminophosphine ligands was synthesized from 2amino-2′-hydroxy-1,1′-binaphthyl (NOBIN). Their asymmetric induction efficiency was examined for silver(I)catalyzed enantioselective allylation reaction of benzaldehyde with allyltributyltin.Under the optimized reaction conditions,quantitative yield as well as moderate ee value (54.5% ee)of product was achieved by the catalysis with silver(I)/3 complex. The effects of the binaphthyl backbone and the substituted situated at chelating N, Patoms on enantioselectivity of the reaction were also discussed.

  8. FeCl3 -Catalyzed Ring-Closing Carbonyl-Olefin Metathesis.

    Science.gov (United States)

    Ma, Lina; Li, Wenjuan; Xi, Hui; Bai, Xiaohui; Ma, Enlu; Yan, Xiaoyu; Li, Zhiping

    2016-08-22

    Exploiting catalytic carbonyl-olefin metathesis is an ongoing challenge in organic synthesis. Reported herein is an FeCl3 -catalyzed ring-closing carbonyl-olefin metathesis. The protocol allows access to a range of carbo-/heterocyclic alkenes with good efficiency and excellent trans diastereoselectivity. The methodology presents one of the rare examples of catalytic ring-closing carbonyl-olefin metathesis. This process is proposed to take place by FeCl3 -catalyzed oxetane formation followed by retro-ring-opening to deliver metathesis products.

  9. Synthesis of novel chiral phosphine-triazine ligand derived from α-phenylethylamine for Pd-catalyzed asymmetric allylic alkylation

    Institute of Scientific and Technical Information of China (English)

    Jia Di Huang; Xiang Ping Hu; Zhuo Zheng

    2008-01-01

    A novel chiral phosphine-triazine ligand was synthesized from chiral model reaction of Pd-catalyzed allylic alkylation of rac-l,3-diphenylprop-2-en-l-yl pivalate with dimethyl malonate, good enantioselectivity (90% e.e.) was obtained by using this ligand.

  10. New chiral N, S-ligands with Thiophenyl at Benzylic Position. Palladium(Ⅱ)-catalyzed Enantioselective Allylic Alkylation

    Institute of Scientific and Technical Information of China (English)

    WU,Hao(吴昊); WU,Xun-Wei(巫循伟); HOU,Xue-Long(侯雪龙); DAI,Li-Xin(戴立信); WANG,Quan-Rui(王全瑞)

    2002-01-01

    New chiral N, S-ligands with oxazoline and thiphenyl substituents at benzene ring and benzylic position have been prepared and applied in palladium-catalyzed asymmetric allylic alkylation reaction to provide the product with high yield and entantioselectivity (82%-93% ee).

  11. Phosphine-catalyzed [4 + 1] annulation between α,β-unsaturated imines and allylic carbonates: synthesis of 2-pyrrolines.

    Science.gov (United States)

    Tian, Junjun; Zhou, Rong; Sun, Haiyun; Song, Haibin; He, Zhengjie

    2011-04-01

    In this report, a phosphine-catalyzed [4 + 1] annulation between α,β-unsaturated imines and allylic carbonates is described. This reaction represents the first realization of catalytic [4 + 1] cyclization of 1,3-azadienes with in situ formed phosphorus ylides, which provides highly efficient and diastereoselective synthesis of 2-pyrrolines.

  12. Immobilization of Chiral Ferrocenyl Ligands on Silica Gel and their Testing in Pd-catalyzed Allylic Substitution and Rh-catalyzed Hydrogenation

    Directory of Open Access Journals (Sweden)

    Duncan J. Macquarrie

    2005-07-01

    Full Text Available Five different silica gels containing two chiral ferrocenyl ligands were prepared by various synthetic routes and tested in an enantioselective Pd(0-catalyzed allylic substitution and Rh-catalyzed hydrogenation. All the prepared anchored ligands were characterized by porosimetry data, DRIFTS spectra, thermal data and AAS. The aim of the work was to compare the influence of the carrier, surface properties and immobilization strategy on the performance of the catalyst.

  13. Mechanism of the cobalt oxazoline palladacycle (COP)-catalyzed asymmetric synthesis of allylic esters.

    Science.gov (United States)

    Cannon, Jeffrey S; Kirsch, Stefan F; Overman, Larry E; Sneddon, Helen F

    2010-11-03

    The catalytic enantioselective S(N)2' displacement of (Z)-allylic trichloroacetimidates catalyzed by the palladium(II) complex [COP-OAc](2) is a broadly useful method for the asymmetric synthesis of chiral branched allylic esters. A variety of experiments aimed at elucidating the nature of the catalytic mechanism and its rate- and enantiodetermining steps are reported. Key findings include the following: (a) the demonstration that a variety of bridged-dipalladium complexes are present and constitute resting states of the COP catalyst (however, monomeric palladium(II) complexes are likely involved in the catalytic cycle); (b) labeling experiments establishing that the reaction proceeds in an overall antarafacial fashion; (c) secondary deuterium kinetic isotope effects that suggest substantial rehybridization at both C1 and C3 in the rate-limiting step; and (d) DFT computational studies (B3-LYP/def2-TZVP) that provide evidence for bidentate substrate-bound intermediates and an anti-oxypalladation/syn-deoxypalladation pathway. These results are consistent with a novel mechanism in which chelation of the imidate nitrogen to form a cationic palladium(II) intermediate activates the alkene for attack by external carboxylate in the enantiodetermining step. Computational modeling of the transition-state structure for the acyloxy palladation step provides a model for enantioinduction.

  14. Protein carbonylation and metal-catalyzed protein oxidation in a cellular perspective

    DEFF Research Database (Denmark)

    Møller, Ian Max; Rogowska-Wrzesinska, Adelina; Rao, R S P

    2011-01-01

    Proteins can become oxidatively modified in many different ways, either by direct oxidation of amino acid side chains and protein backbone or indirectly by conjugation with oxidation products of polyunsaturated fatty acids and carbohydrates. While reversible oxidative modifications are thought...... to be relevant in physiological processes, irreversible oxidative modifications are known to contribute to cellular damage and disease. The most well-studied irreversible protein oxidation is carbonylation. In this work we first examine how protein carbonylation occurs via metal-catalyzed oxidation (MCO) in vivo...... and in vitro with an emphasis on cellular metal ion homeostasis and metal binding. We then review proteomic methods currently used for identifying carbonylated proteins and their sites of modification. Finally, we discuss the identified carbonylated proteins and the pattern of carbonylation sites in relation...

  15. Direct Nucleophilic Substitution of Free Allylic Alcohols in Water Catalyzed by FeCl3⋅6 H2O: Which is the Real Catalyst?

    OpenAIRE

    Trillo Alarcón, María Paz; Baeza, Alejandro; Nájera Domingo, Carmen

    2013-01-01

    The allylic substitution reaction, and particularly the direct allylic amination reaction, of free allylic alcohols in water catalyzed by FeCl3⋅6 H2O is described. This novel environmentally-friendly methodology allows the use of a wide variety of nitrogenated nucleophiles such as sulfonamides, carbamates, benzamides, anilines, benzotriazoles, and azides, generally giving good yields of the corresponding substitution products. The synthetic applicability of the process is also demonstrated be...

  16. Cobalt carbonyl catalyzed olefin hydroformylation in supercritical carbon dioxide

    Science.gov (United States)

    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.

  17. Particle growth by acid-catalyzed heterogeneous reactions of organic carbonyls on preexisting aerosols.

    Science.gov (United States)

    Jang, Myoseon; Carroll, Brian; Chandramouli, Bharadwaj; Kamens, Richard M

    2003-09-01

    Aerosol growth by the heterogeneous reactions of different aliphatic and alpha,beta-unsaturated carbonyls in the presence/absence of acidified seed aerosols was studied in a 2 m long flow reactor (2.5 cm i.d.) and a 0.5-m3 Teflon film bag under darkness. For the flow reactor experiments, 2,4-hexadienal, 5-methyl-3-hexen-2-one, 2-cyclohexenone, 3-methyl-2-cyclopentenone, 3-methyl-2-cyclohexenone, and octanal were studied. The carbonyls were selected based on their reactivity for acid-catalyzed reactions, their proton affinity, and their similarity to the ring-opening products from the atmospheric oxidation of aromatics. To facilitate acid-catalyzed heterogeneous hemiacetal/acetal formation, glycerol was injected along with inorganic seed aerosols into the flow reactor system. Carbonyl heterogeneous reactions were accelerated in the presence of acid catalysts (H2SO4), leading to higher aerosol yields than in their absence. Aldehydes were more reactive than ketones for acid-catalyzed reactions. The conjugated functionality also resulted in higher organic aerosol yieldsthan saturated aliphatic carbonyls because conjugation with the olefinic bond increases the basicity of the carbonyl leading to increased stability of the protonated carbonyl. Aerosol population was measured from a series of sampling ports along the length of the flow reactor using a scanning mobility particle sizer. Fourier transform infrared spectrometry of either an impacted liquid aerosol layer or direct reaction of carbonyls as a thin liquid layer on a zinc selenide FTIR disk was employed to demonstrate the direct transformation of chemical functional groups via the acid-catalyzed reactions. These results strongly indicate that atmospheric multifunctional organic carbonyls, which are created by atmospheric photooxidation reactions, can contribute significantly to secondary organic aerosol formation through acid-catalyzed heterogeneous reactions. Exploratory studies in 25- and 190-m3 outdoor chambers

  18. Palladium-Catalyzed Carbonylation of Primary Amines in Supercritical Carbon Dioxide

    Institute of Scientific and Technical Information of China (English)

    李金恒; 江焕峰; 陈鸣才

    2001-01-01

    The chemoselectity of the palladimm-catalyzed carbonylation of amines was affected by the addition of MeOH in supercritical carbon dioxide. The results show different selectivity in supercritical carbon dioxide CO2(sc) from that in alcohol.Methyl carbamate and its derivatives were obtained in high yields in CO2(sc).

  19. Decarboxylative-coupling of allyl acetate catalyzed by group 10 organometallics, [(phen)M(CH3)]+.

    Science.gov (United States)

    Woolley, Matthew; Ariafard, Alireza; Khairallah, George N; Kwan, Kim Hong-Yin; Donnelly, Paul S; White, Jonathan M; Canty, Allan J; Yates, Brian F; O'Hair, Richard A J

    2014-12-19

    Gas-phase carbon-carbon bond forming reactions, catalyzed by group 10 metal acetate cations [(phen)M(O2CCH3)](+) (where M = Ni, Pd or Pt) formed via electrospray ionization of metal acetate complexes [(phen)M(O2CCH3)2], were examined using an ion trap mass spectrometer and density functional theory (DFT) calculations. In step 1 of the catalytic cycle, collision induced dissociation (CID) of [(phen)M(O2CCH3)](+) yields the organometallic complex, [(phen)M(CH3)](+), via decarboxylation. [(phen)M(CH3)](+) reacts with allyl acetate via three competing reactions, with reactivity orders (% reaction efficiencies) established via kinetic modeling. In step 2a, allylic alkylation occurs to give 1-butene and reform metal acetate, [(phen)M(O2CCH3)](+), with Ni (36%) > Pd (28%) > Pt (2%). Adduct formation, [(phen)M(C6H11O2)](+), occurs with Pt (24%) > Pd (21%) > Ni(11%). The major losses upon CID on the adduct, [(phen)M(C6H11O2)](+), are 1-butene for M = Ni and Pd and methane for Pt. Loss of methane only occurs for Pt (10%) to give [(phen)Pt(C5H7O2)](+). The sequences of steps 1 and 2a close a catalytic cycle for decarboxylative carbon-carbon bond coupling. DFT calculations suggest that carbon-carbon bond formation occurs via alkene insertion as the initial step for all three metals, without involving higher oxidation states for the metal centers.

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

    Science.gov (United States)

    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

  1. Hydrolysis of cellulose catalyzed by quaternary ammonium perrhenates in 1-allyl-3-methylimidazolium chloride.

    Science.gov (United States)

    Wang, Jingyun; Zhou, Mingdong; Yuan, Yuguo; Zhang, Quan; Fang, Xiangchen; Zang, Shuliang

    2015-12-01

    Quaternary ammonium perrhenates were applied as catalyst to promote the hydrolysis of cellulose in 1-allyl-3-methylimidazolium chloride ([Amim]Cl). The quaternary ammonium perrhenates displayed good catalytic performance for cellulose hydrolysis. Water was also proven to be effective to promote cellulose hydrolysis. Accordingly, 97% of total reduced sugar (TRS) and 42% of glucose yields could be obtained under the condition of using 5mol% of tetramethyl ammonium perrhenate as catalyst, 70μL of water, ca. 0.6mmol of microcrystalline cellulose (MCC) and 2.0g of [Amim]Cl as solvent under microwave irradiation for 30min at 150°C (optimal conditions). The influence of quaternary ammonium cation on the efficiency of cellulose hydrolysis was examined based on different cation structures of perrhenates. The mechanism on perrhenate catalyzed cellulose hydrolysis is also discussed, whereas hydrogen bonding between ReO4 anion and hydroxyl groups of cellulose is assumed to be the key step for depolymerization of cellulose.

  2. Ruthenium Catalyzed Diastereo- and Enantioselective Coupling of Propargyl Ethers with Alcohols: Siloxy-Crotylation via Hydride Shift Enabled Conversion of Alkynes to π-Allyls

    Science.gov (United States)

    Liang, Tao; Zhang, Wandi; Chen, Te-Yu; Nguyen, Khoa D.; Krische, Michael J.

    2015-01-01

    The first enantioselective carbonyl crotylations through direct use of alkynes as chiral allylmetal equivalents are described. Chiral ruthenium(II) complexes modified by Josiphos (SL-J009-1) catalyze the C-C coupling of TIPS-protected propargyl ether 1a with primary alcohols 2a-2o to form products of carbonyl siloxy-crotylation 3a-3o, which upon silyl deprotection-reduction deliver 1,4-diols 5a-5o with excellent control of regio-, anti-diastereo- and enantioselectivity. Structurally related propargyl ethers 1b and 1c bearing ethyl- and phenyl-substituents engage in diastereo- and enantioselective coupling, as illustrated in the formation of adducts 5p and 5q, respectively. Selective mono-tosylation of diols 5a, 5c, 5e, 5f, 5k and 5m is accompanied by spontaneous cyclization to deliver the trans-2,3-disubstituted furans 6a, 6c, 6e, 6f, 6k and 6m, respectively. Primary alcohols 2a, 2l and 2p were converted to the siloxy-crotylation products 3a, 3l and 3p, which upon silyl deprotection-lactol oxidation were transformed to the trans-4,5-disubstituted γ-butyrolactones 7a, 7l and 7p. The formation of 7p represents a total synthesis of (+)-trans-whisky lactone. Unlike closely related ruthenium catalyzed alkyne-alcohol C-C couplings, deuterium labeling studies provide clear evidence of a novel 1,2-hydride shift mechanism that converts metal-bound alkynes to π-allyls in the absence of intervening allenes. PMID:26418572

  3. Silver-Catalyzed Decarboxylative Allylation of Aliphatic Carboxylic Acids in Aqueous Solution.

    Science.gov (United States)

    Cui, Lei; Chen, He; Liu, Chao; Li, Chaozhong

    2016-05-06

    Direct decarboxylative radical allylation of aliphatic carboxylic acids is described. With K2S2O8 as the oxidant and AgNO3 as the catalyst, the reactions of aliphatic carboxylic acids with allyl sulfones in aqueous CH3CN solution gave the corresponding alkenes in satisfactory yields under mild conditions. This site-specific allylation method is applicable to all primary, secondary, and tertiary alkyl acids and exhibits wide functional group compatibility.

  4. Chiral Phosphoric Acid Catalyzed Enantioselective Allylation of Aldehydes with Allyltrichlorosilane%Chiral Phosphoric Acid Catalyzed Enantioselective Allylation of Aldehydes with Allyltrichlorosilane

    Institute of Scientific and Technical Information of China (English)

    程柯; 范甜甜; 孙健

    2011-01-01

    Easily accessible chiral phosphoric acid lb has been applied as efficient organocatalyst for the asymmetric al- lylation of aldehydes with allyltrichlorosilane. In the presence of 20 mol% of lb, the allylation of a broad range of aldehydes proceeded smoothly to give the corresponding homoallylic alcohol with up to 87% ee and 97% yield.

  5. Synthesis of Carbazoles and Carbazole-Containing Heterocycles via Rhodium-Catalyzed Tandem Carbonylative Benzannulations.

    Science.gov (United States)

    Song, Wangze; Li, Xiaoxun; Yang, Ka; Zhao, Xian-liang; Glazier, Daniel A; Xi, Bao-min; Tang, Weiping

    2016-04-01

    Polycyclic aromatic compounds are important constituents of pharmaceuticals and other materials. We have developed a series of Rh-catalyzed tandem carbonylative benzannulations for the synthesis of tri-, tetra-, and pentacyclic heterocycles from different types of aryl propargylic alcohols. These tandem reactions provide efficient access to highly substituted carbazoles, furocarbazoles, pyrrolocarbazoles, thiophenocarbazoles, and indolocarbazoles. While tricyclic heterocycles could be derived from vinyl aryl propargylic alcohols, tetra- and pentacyclic heterocycles were synthesized from diaryl propargylic alcohols. The tandem carbonylative benzannulation is initiated by a π-acidic rhodium(I) catalyst-mediated nucleophilic addition to alkyne to generate a key metal-carbene intermediate, which is then trapped by carbon monoxide to form a ketene species for 6π electrocyclization. Overall, three bonds and two rings are formed in all of these tandem carbonylative benzannulation reactions.

  6. Yttrium (III chloride catalyzed Mannich reaction: An efficient procedure for the synthesis of β-amino carbonyl compounds

    Directory of Open Access Journals (Sweden)

    Venkateswarlu Yekkirala

    2014-12-01

    Full Text Available Yttrium (III chloride catalyzed Mannich reaction of aldehydes with ketones and amines in acetonitrile at reflux temperature to give various β-amino carbonyl compounds in very good yields.

  7. A Mechanistic Study of Direct Activation of Allylic Alcohols in Palladium Catalyzed Amination Reactions

    OpenAIRE

    Yasemin Gumrukcu; Bas de Bruin; Reek, Joost N. H.

    2015-01-01

    We here report a computational approach on the mechanism of allylicamination reactions using allyl-alcohols and amines as the substrates and phosphoramidite palladium catalyst 1a, which operates in the presence of catalytic amount of 1,3-diethylurea as a co-catalyst. DFT calculations showed a cooperative hydrogen-bonding array between the urea moiety and the hydroxyl group of the allyl alcohol, which strengthens the hydrogen bond between the O-H moiety of the coordinated allyl-alcohol and th...

  8. Direct use of allylic alcohols for platinum-catalyzed monoallylation of amines.

    Science.gov (United States)

    Utsunomiya, Masaru; Miyamoto, Yoshiki; Ipposhi, Junji; Ohshima, Takashi; Mashima, Kazushi

    2007-08-16

    A new direct catalytic amination of allylic alcohols promoted by the combination of platinum and a large bite-angle ligand DPEphos was developed in which the allylic alcohol was effectively converted to a pi-allylplatinum intermediate without the use of an activating reagent. The use of the DPEphos ligand was essential for obtaining high catalyst activity and high monoallylation selectivity of primary amines, allowing the formation of a variety of monoallylation products in good to excellent yield.

  9. Platinum-catalyzed direct amination of allylic alcohols under mild conditions: ligand and microwave effects, substrate scope, and mechanistic study.

    Science.gov (United States)

    Ohshima, Takashi; Miyamoto, Yoshiki; Ipposhi, Junji; Nakahara, Yasuhito; Utsunomiya, Masaru; Mashima, Kazushi

    2009-10-14

    Transition metal-catalyzed amination of allylic compounds via a pi-allylmetal intermediate is a powerful and useful method for synthesizing allylamines. Direct catalytic substitution of allylic alcohols, which forms water as the sole coproduct, has recently attracted attention for its environmental and economical advantages. Here, we describe the development of a versatile direct catalytic amination of both aryl- and alkyl-substituted allylic alcohols with various amines using Pt-Xantphos and Pt-DPEphos catalyst systems, which allows for the selective synthesis of various monoallylamines, such as the biologically active compounds Naftifine and Flunarizine, in good to high yield without need for an activator. The choice of the ligand was crucial toward achieving high catalytic activity, and we demonstrated that not only the large bite-angle but also the linker oxygen atom of the Xantphos and DPEphos ligands was highly important. In addition, microwave heating dramatically affected the catalyst activity and considerably decreased the reaction time compared with conventional heating. Furthermore, several mechanistic investigations, including (1)H and (31)P{(1)H} NMR studies; isolation and characterization of several catalytic intermediates, Pt(xantphos)Cl(2), Pt(eta(2)-C(3)H(5)OH)(xantphos), etc; confirmation of the structure of [Pt(eta(3)-allyl)(xantphos)]OTf by X-ray crystallographic analysis; and crossover experiments, suggested that formation of the pi-allylplatinum complex through the elimination of water is an irreversible rate-determining step and that the other processes in the catalytic cycle are reversible, even at room temperature.

  10. Highly selective palladium–benzothiazole carbene-catalyzed allylation of active methylene compounds under neutral conditions

    Directory of Open Access Journals (Sweden)

    Antonio Monopoli

    2015-06-01

    Full Text Available The Pd–benzothiazol-2-ylidene complex I was found to be a chemoselective catalyst for the Tsuji–Trost allylation of active methylene compounds carried out under neutral conditions and using carbonates as allylating agents. The proposed protocol consists in a simplified procedure adopting an in situ prepared catalyst from Pd2dba3 and 3-methylbenzothiazolium salt V as precursors. A comparison of the performance of benzothiazole carbene with phosphanes and an analogous imidazolium carbene ligand is also proposed.

  11. On the Nature of the Intermediates and the Role of Chloride Ions in Pd-Catalyzed Allylic Alkylations: Added Insight from Density Functional Theory

    DEFF Research Database (Denmark)

    Fristrup, Peter; Ahlquist, Mårten Sten Gösta; Tanner, David Ackland

    2008-01-01

    The reactivity of intermediates in palladium-catalyzed allylic alkylation was investigated using DFT (B3LYP) calculations including a PB-SCRF solvation model. In the presence of both phosphine and chloride ligands, the allyl intermediate is in equilibrium between a cationic eta(3)-allylPd complex...... with two phosphine ligands, the corresponding neutral complex with one phosphine and one chloride ligand, and a neutral eta(1)-allylPd complex with one chloride and two phosphine ligands. The eta(1)-complex is unreactive toward nucleophiles. The cationic eta(3)-complex is the intermediate most frequently...... invoked in the title reaction, but in the presence of halides, the neutral, unsymmetrically substituted eta(3)-CoMplex will be formed rapidly from anionic Pd(0) complexes in solution. Since the latter will prefer both leaving group ionization and reaction with nucleophiles in the position trans...

  12. Zirconium-allyl complexes as resting states in zirconocene-catalyzed α-olefin polymerization.

    Science.gov (United States)

    Panchenko, Valentina N; Babushkin, Dmitrii E; Brintzinger, Hans H

    2015-01-01

    UV-vis spectroscopic data indicate that zirconocene cations with Zr-bound allylic chain ends are generally formed during olefin polymerization with zirconocene catalysts. The rates and extent of their formation and of their re-conversion to the initial pre-catalyst cations depend on the types of zirconocene complexes and activators used.

  13. A Mechanistic Study of Direct Activation of Allylic Alcohols in Palladium Catalyzed Amination Reactions

    NARCIS (Netherlands)

    Gumrukcu, Y.; de Bruin, B.; Reek, J.N.H.

    2015-01-01

    We here report a computational approach on the mechanism of allylicamination reactions using allyl-alcohols and amines as the substrates and phosphoramidite palladium catalyst 1a, which operates in the presence of catalytic amount of 1,3-diethylurea as a co-catalyst. DFT calculations showed a cooper

  14. In(OTf)3 catalyzed allylation reaction of imines with tetraallyltin

    Institute of Scientific and Technical Information of China (English)

    Xiao Ning Wei; Ling Yan Liu; Bing Wang; Wei Xing Chang; Jing Li

    2009-01-01

    In the presence of catalytic amount of In(OTf)3 (10 mol%), a series of aldimines reacted with tetraallyltin in a 2:1 molar ratio to afford the corresponding homoallylic amines in good yields. The good atom efficiency was achieved under mild reaction conditions and a new protocol (allyl)4Sn/In(OTf)3 for simple imines was developed.

  15. Nickel-catalyzed enantioselective hydrovinylation of silyl-protected allylic alcohols:An efficient access to homoallylic alcohols with a chiral quaternary center

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Asymmetric hydrovinylation of silyl-protected allylic alcohols catalyzed by nickel complexes of chiral spiro phosphoramidite ligands was developed.A series of homoallylic alcohols with a chiral quaternary center were produced in high yields(up to 97%) and high enantioselectivities(up to 95% ee).The reaction provides an efficient method for preparing bifunctional compounds with a chiral quaternary carbon center.

  16. Synthesis of Oxacyclic Scaffolds via Dual Ruthenium Hydride/Brønsted Acid‐Catalyzed Isomerization/Cyclization of Allylic Ethers

    DEFF Research Database (Denmark)

    Ascic, Erhad; Ohm, Ragnhild Gaard; Petersen, Rico;

    2014-01-01

    A ruthenium hydride/Brønsted acid‐catalyzed tandem sequence is reported for the synthesis of 1,3,4,9‐tetrahydropyrano[3,4‐b]indoles (THPIs) and related oxacyclic scaffolds. The process was designed on the premise that readily available allylic ethers would undergo sequential isomerization, first ...

  17. Highly Regioselective Palladium-Catalyzed Carboxylation of Allylic Alcohols with CO2.

    Science.gov (United States)

    Mita, Tsuyoshi; Higuchi, Yuki; Sato, Yoshihiro

    2015-11-01

    Various allylic alcohols were carboxylated in the presence of a catalytic amount of PdCl2 and PPh3 using ZnEt2 as a stoichiometric transmetalation agent under a CO2 atmosphere (1 atm). This carboxylation proceeded in a highly regioselective manner to afford branched carboxylic acids predominantly. The β,γ-unsaturated carboxylic acid thus obtained was successfully converted into an optically active γ-butyrolactone, a known intermediate of (R)-baclofen.

  18. Iron(III) chloride catalyzed glycosylation of peracylated sugars with allyl/alkynyl alcohols

    Energy Technology Data Exchange (ETDEWEB)

    Narayanaperumal, Senthil; Silva, Rodrigo Cesar da; Monteiro, Julia L.; Correa, Arlene G.; Paixao, Marcio W., E-mail: mwpaixao@ufscar.br [Universidade Federal de Sao Carlos (UFSCAR), SP (Brazil). Dept. de Quimica

    2012-11-15

    In this work, the use of ferric chloride as an efficient catalyst in glycosylation reactions of sugars in the presence of allyl and alkynyl alcohols is described. The corresponding glycosides were obtained with moderate to good yields. This new procedure presented greater selectivity when compared to classic methods found in the literature. Principal features of this simple method include non-hazardous reaction conditions, low-catalyst loading, good yields and high anomeric selectivity (author)

  19. Synthesis of Unsymmetric Ureas by Selenium-Catalyzed Oxidative-Reductive Carbonylation with CO

    Institute of Scientific and Technical Information of China (English)

    MEI Jian-Ting; LU Shi-Wei

    2003-01-01

    @@ Unsymmetric, substituted ureas that contain the peptide bond (NHCONH), many of which possess biological activities, are widely used as herbicides, agrochemicals and pharmaceuticals. [1,2] A series of unsymmetric ureascontaining substituted groups have been synthesized via selenium-catalyzed selective oxidative-reductive carbonylation of amines and nitro compounds with CO instead of phosgene in one-pot reaction. [3,4] These catalytic reactions are important from both synthetic and industrial points of view, because not only the reactions can be proceeded with high selectivity of higher than 99% towards desired unsymmetric ureas, but also there exists a phase-transfer process of the selenium catalyst in thereaction, so that the after-treatment of the catalysts and products from the reaction systems can be easily separated by simple phase separation.

  20. Oxidative Carbonylation of Aromatic Amines with CO Catalyzed by 1,3-Dialkylimidazole-2-selenone in Ionic Liquids

    Directory of Open Access Journals (Sweden)

    Fengshou Tian

    2015-01-01

    Full Text Available 1,3-Dialkylimidazole-2-selenone as a novel substituted selenium heterocyclic catalyst was used to catalyze oxidative carbonylation of aromatic amines with carbon monoxide in the presence of air to symmetrical ureas in up to 97% yield in ionic liquids.

  1. Pd-catalyzed carbonylative α-arylation of aryl bromides: scope and mechanistic studies.

    Science.gov (United States)

    Nielsen, Dennis U; Lescot, Camille; Gøgsig, Thomas M; Lindhardt, Anders T; Skrydstrup, Troels

    2013-12-23

    Reaction conditions for the three-component synthesis of aryl 1,3-diketones are reported applying the palladium-catalyzed carbonylative α-arylation of ketones with aryl bromides. The optimal conditions were found by using a catalytic system derived from [Pd(dba)2] (dba=dibenzylideneacetone) as the palladium source and 1,3-bis(diphenylphosphino)propane (DPPP) as the bidentate ligand. These transformations were run in the two-chamber reactor, COware, applying only 1.5 equivalents of carbon monoxide generated from the CO-releasing compound, 9-methylfluorene-9-carbonyl chloride (COgen). The methodology proved adaptable to a wide variety of aryl and heteroaryl bromides leading to a diverse range of aryl 1,3-diketones. A mechanistic investigation of this transformation relying on 31P and 13C NMR spectroscopy was undertaken to determine the possible catalytic pathway. Our results revealed that the combination of [Pd(dba)2] and DPPP was only reactive towards 4-bromoanisole in the presence of the sodium enolate of propiophenone suggesting that a [Pd(dppp)(enolate)] anion was initially generated before the oxidative-addition step. Subsequent CO insertion into an [Pd(Ar)(dppp)(enolate)] species provided the 1,3-diketone. These results indicate that a catalytic cycle, different from the classical carbonylation mechanism proposed by Heck, is operating. To investigate the effect of the dba ligand, the Pd0 precursor, [Pd(η3-1-PhC3H4)(η5-C5H5)], was examined. In the presence of DPPP, and in contrast to [Pd(dba)2], its oxidative addition with 4-bromoanisole occurred smoothly providing the [PdBr(Ar)(dppp)] complex. After treatment with CO, the acyl complex [Pd(CO)Br(Ar)(dppp)] was generated, however, its treatment with the sodium enolate led exclusively to the acylated enol in high yield. Nevertheless, the carbonylative α-arylation of 4-bromoanisole with either catalytic or stoichiometric [Pd(η3-1-PhC3H4)(η5-C5H5)] over a short reaction time, led to the 1,3-diketone product

  2. Transition-Metal-Catalyzed C-H Bond Addition to Carbonyls, Imines, and Related Polarized π Bonds.

    Science.gov (United States)

    Hummel, Joshua R; Boerth, Jeffrey A; Ellman, Jonathan A

    2016-12-12

    The transition-metal-catalyzed addition of C-H bonds to carbonyls, imines, and related polarized π bonds has emerged as a particularly efficient and powerful approach for the construction of an incredibly diverse array of heteroatom-substituted products. Readily available and stable inputs are typically employed, and reactions often proceed with very high functional group compatibility and without the production of waste byproducts. Additionally, many transition-metal-catalyzed C-H bond additions to polarized π bonds occur within cascade reaction sequences to provide rapid access to a diverse array of different heterocyclic as well as carbocyclic products. This review highlights the diversity of transformations that have been achieved, catalysts that have been used, and types of products that have been prepared through the transition-metal-catalyzed addition of C-H bonds to carbonyls, imines, and related polarized π bonds.

  3. A configurational switch based on iridium-catalyzed allylic cyclization: application in asymmetric total syntheses of prosopis, dendrobate, and spruce alkaloids.

    Science.gov (United States)

    Gnamm, Christian; Brödner, Kerstin; Krauter, Caroline M; Helmchen, Günter

    2009-10-12

    A method for the stereoselective synthesis of 2,6-disubstituted piperidines has been developed that is based on the use of an intramolecular iridium-catalyzed allylic substitution as a configurational switch. The procedure allows the preparation of 2-vinylpiperidines with enantiomeric excesses (ee) of greater than 99%. As applications, total syntheses of piperidine alkaloids have been elaborated, most often by using Ru-catalyzed cross-metatheses as a key step for introduction of a side chain. Asymmetric total syntheses of the prosopis alkaloids (+)-prosopinine, (+)-prosophylline, (+)-prosopine, and of the dendrobate alkaloid (+)-241D and its C6 epimer are described.

  4. Crystallization experiments with the dinuclear chelate ring complex di-μ-chlorido-bis[(η(2)-2-allyl-4-methoxy-5-{[(propan-2-yloxy)carbonyl]methoxy}phenyl-κC(1))platinum(II)].

    Science.gov (United States)

    Nguyen Thi Thanh, Chi; Pham Van, Thong; Le Thi Hong, Hai; Van Meervelt, Luc

    2016-10-01

    Crystallization experiments with the dinuclear chelate ring complex di-μ-chlorido-bis[(η(2)-2-allyl-4-methoxy-5-{[(propan-2-yloxy)carbonyl]methoxy}phenyl-κC(1))platinum(II)], [Pt2(C15H19O4)2Cl2], containing a derivative of the natural compound eugenol as ligand, have been performed. Using five different sets of crystallization conditions resulted in four different complexes which can be further used as starting compounds for the synthesis of Pt complexes with promising anticancer activities. In the case of vapour diffusion with the binary chloroform-diethyl ether or methylene chloride-diethyl ether systems, no change of the molecular structure was observed. Using evaporation from acetonitrile (at room temperature), dimethylformamide (DMF, at 313 K) or dimethyl sulfoxide (DMSO, at 313 K), however, resulted in the displacement of a chloride ligand by the solvent, giving, respectively, the mononuclear complexes (acetonitrile-κN)(η(2)-2-allyl-4-methoxy-5-{[(propan-2-yloxy)carbonyl]methoxy}phenyl-κC(1))chloridoplatinum(II) monohydrate, [Pt(C15H19O4)Cl(CH3CN)]·H2O, (η(2)-2-allyl-4-methoxy-5-{[(propan-2-yloxy)carbonyl]methoxy}phenyl-κC(1))chlorido(dimethylformamide-κO)platinum(II), [Pt(C15H19O4)Cl(C2H7NO)], and (η(2)-2-allyl-4-methoxy-5-{[(propan-2-yloxy)carbonyl]methoxy}phenyl-κC(1))chlorido(dimethyl sulfoxide-κS)platinum(II), determined as the analogue {η(2)-2-allyl-4-methoxy-5-[(ethoxycarbonyl)methoxy]phenyl-κC(1)}chlorido(dimethyl sulfoxide-κS)platinum(II), [Pt(C14H17O4)Cl(C2H6OS)]. The crystal structures confirm that acetonitrile interacts with the Pt(II) atom via its N atom, while for DMSO, the S atom is the coordinating atom. For the replacement, the longest of the two Pt-Cl bonds is cleaved, leading to a cis position of the solvent ligand with respect to the allyl group. The crystal packing of the complexes is characterized by dimer formation via C-H...O and C-H...π interactions, but no π-π interactions are observed despite the presence of

  5. Cp*Rh(III)-Catalyzed Low Temperature C-H Allylation of N-Aryl-trichloro Acetimidamide.

    Science.gov (United States)

    Debbarma, Suvankar; Bera, Sourav Sekhar; Maji, Modhu Sudan

    2016-12-02

    The readily synthesized trichloro acetimidamide was found to be an excellent directing group for the directed C-H-allylation reactions. Depending on the allylating agent used, selectively either mono- or diallylated products were readily synthesized. Moreover, the trichloro acetimidamide directing group was found to be highly efficient even at lower temperature for the C-H-allylation reaction. Due to mildness of the reaction conditions, double bond isomerization or cyclization to indole side product was not observed.

  6. Organic Synthesis in Ionic Liquids: Condensation of 3-Methyl-1-phenyl-5-pyrazolone with Carbonyl Compounds Catalyzed by Ethylenediammonium Diacetate(EDDA)

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    An efficient and environmental benign method is reported for the condensation of 3-methyl-1-phenyl-5-pyrazolone with carbonyl compounds in ionic liquids [Bmim]BF4 and [Bmim]PF6 catalyzed by ethylenediammonium diacetate.

  7. Deconvoluting the memory effect in Pd-catalyzed allylic alkylation; effect of leaving group and added chloride

    DEFF Research Database (Denmark)

    Fristrup, Peter; Jensen, Thomas; Hoppe, Jakob;

    2006-01-01

    An analysis of product distributions in the Tsuji-Trost reaction indicates that several instances of reported memory effects can be attributed to slow interconversion of the initially formed syn- and anti-[Pd(eta3-allyl)] complexes. Addition of chloride triggers a true memory effect, in which...... the allylic terminus originally bearing the leaving group has a higher reactivity. The latter effect, termed regioretention, can be rationalized by ionization from a palladium complex bearing a chloride ion, forming an unsymmetrically substituted [Pd(eta3-allyl)] complex. DFT calculations verify...

  8. Iron(III)-Catalyzed Ring-Closing Carbonyl-Olefin Metathesis.

    Science.gov (United States)

    Saá, Carlos

    2016-09-01

    Recent developments in catalytic carbonyl-olefin metathesis are summarized in this Highlight. Schindler and co-workers have reported that the environmentally benign FeCl3 catalyst promotes ring-closing carbonyl-olefin metathesis (RCCOM) in high yield under very mild conditions.

  9. Allylation of Aromatic Aldehyde under Microwave Irradiation

    Institute of Scientific and Technical Information of China (English)

    ZHANG,Yu-Mei; JIA,Xue-Feng; WANG,Jin-Xian

    2004-01-01

    @@ Allylation of carbonyl compounds is one of the most interesting processes for the preparation of homoallylic alcohols. Over the past few decades, many reagents have been developed for such reactions[1~3]. In this paper, we first report allylic zinc reagent 1, which can be prepared from zinc dust and allyl bromide conveniently in THF, and reacted with aromatic aldehyde to give homo-allylic alcohols under microwave irradiation.

  10. Direct Substitution of the Hydroxy Group at the Allylic/propargylic Position with Carbon-and Heteroatomcentered Nucleophiles Catalyzed by Yb(OTf)3

    Institute of Scientific and Technical Information of China (English)

    HUANG Wen; SHEN Quan-Sheng; WANG Jia-Liang; ZHOU Xi-Geng

    2008-01-01

    An efficient and highly selective Yb(OTf)3-catalyzed direct substitution of the hydroxy group at the allylic and propargylic positions with a variety of heteroatom- and carbon-centered nucleophiles, such as alcohols, thiols,amines, amides and active methylene compounds has been developed. The advantages of the present catalytic system are wide availability of the starting materials, especially for tolerance to thiols, no need for dried solvents and additives, mild conditions, short time of reaction, simple manipulation and environmentally friendly catalyst that can be recovered and reused at least ten times without significant reduction of activity.

  11. Palladacyclic imidazoline-naphthalene complexes: synthesis and catalytic performance in Pd(II)-catalyzed enantioselective reactions of allylic trichloroacetimidates.

    Science.gov (United States)

    Cannon, Jeffrey S; Frederich, James H; Overman, Larry E

    2012-02-17

    A new family of air- and moisture-stable enantiopure C,N-palladacycles (PIN-acac complexes) were prepared in good overall yield in three steps from 2-iodo-1-naphthoic acid and enantiopure β-amino alcohols. Three of these PIN complexes were characterized by single-crystal X-ray analysis. As anticipated, the naphthalene and imidazoline rings of PIN-acac complexes 18a and 18b were canted significantly from planarity and projected the imidazoline substituents R(1) and R(2) on opposite faces of the palladium square plane. Fifteen PIN complexes were evaluated as catalysts for the rearrangement of prochiral (E)-allylic trichloroacetimidate 19 (eq 2) and the S(N)2' allylic substitution of acetic acid with prochiral (Z)-allylic trichloroacetimidate 23. Although these complexes were kinetically poor catalysts for the Overman rearrangement, they were good catalysts for the allylic substitution reaction, providing branched allylic esters in high yield. However, enantioselectivities were low to moderate and significantly less than that realized with palladacyclic complexes of the COP family. Computational studies support an anti-acetoxypalladation/syn-deoxypalladation mechanism analogous to that observed with COP catalysts. The computational study further suggests that optimizing steric influence in the vicinity of the carbon ligand of a chiral C,N-palladacycle, rather than near the nitrogen heterocycle, is the direction to pursue in future development of improved enantioselective catalysts of this motif.

  12. Stereochemistry of Pd(II)-Catalyzed THF Ring Formation of ε-Hydroxy Allylic Alcohols and Synthesis of 2,3,5-Trisubstituted and 2,3,4,5-Tetrasubstituted Tetrahydrofurans.

    Science.gov (United States)

    Murata, Yuki; Uenishi, Jun'ichi

    2016-09-02

    Pd(II)-catalyzed ring formation of 2,3,5-trisubstituted and 2,3,4,5-tetrasubstituted tetrahydrofurans is described. Oxypalladation of a chiral ε-hydroxy allylic alcohol provides a 5-alkenyltetrahydrofuran ring in excellent yields via a 5-exo-trigonal process. Nine substrates including six secondary allylic alcohols and three primary allylic alcohols with or without an additional secondary hydroxy substituent at the γ-position have been examined. Their structures are restricted by a 2,2,4,4-tetraisopropyl-1,3,5,2,4-trioxadisilocane ring. The stereochemistry of the resulting tetrahydrofuran products was determined by chemical transformation. The reaction mechanism is discussed on the basis of the stereochemical results. The steps in the chiral allylic alcohol directed or the nucleophilic alcohol directed facial selection for the formation of the alkene-Pd(II)-π-complex, the cis-oxypalladation, and a syn-elimination mechanism account for the observed stereochemistry of the reaction.

  13. N-Heterocyclic Carbene-Palladium Complex Catalyzed Oxidative Carbonylation of Amines to Ureas

    Institute of Scientific and Technical Information of China (English)

    ZHENG,Shu-Zhan; PENG,Xin-Gao; LIU,Jian-Ming; SUN,Wei; XIA,Chun-Gu

    2007-01-01

    Palladium carbene shows high efficiency without any promoter on oxidative carbonylation of amines to ureas and a new type of palladium carbene complex containing both an aniline and an NHC ligands was found to be the active species for the reaction.

  14. Epoxidation of olefins and allylic alcohols with hydrogen peroxide catalyzed by heteropoly acids in the presence of cetylpyridinium chloride

    Energy Technology Data Exchange (ETDEWEB)

    Okabayashi, Takuji; Yamawaki, Kazumasa; Nishihara, Hideki; Yamada, Hiroshi; Ura, Toshikazu; Ishii, Yasutaka; Ogawa, Masaya

    1987-11-01

    The epoxidation of olefins and allylic alcohols with aqueous hydrogen peroxide could be achieved in good yield when 12-tungustophosphoric acid(WPA) was used with two phase condition using chloroform as the solvent. From the epoxidation result by 12-molybdophosphoric acid(MPA) and WPA catalysts, epoxidation activity of WPA catalyst was found to be remarkably higher than that of MPA. The rate of epoxidation by heteropoly acids catalyst depended markedly upon the activity of the reaction medium. Epoxidation of allylic alcohols with hydrogen peroxide proceeded under mild conditions, resulting good yield of epoxi-alcohols. Epoxidation of olefins by WPA/cetylpyridium chloride was confirmed to be promoted selectively with cheap and pure hydrogen peroxide, resulting good yield. (3 figs, 2 tabs, 18 refs)

  15. Lewis Base-Catalyzed Formation of α-Trifluoromethyl Alcohol from CF3SiMe3 and Carbonyl-Containing Compounds

    Institute of Scientific and Technical Information of China (English)

    ZHU Shi-Fa; PANG Wan; XING Chun-Hui; ZHU Shi-Zheng

    2007-01-01

    Lewis base could catalyze the formation of α-trifluoromethyl alcohol from CF3SiMe3 and carbonyl-containingcompounds. It was found that the a-trilluoromethyl alcohol could also be used to promote the synthesis in basic conditions.

  16. Palladium-catalyzed Carbonylative Cyclization of 2-Bromocyclohex-1-enecarbalde-hydes with Aliphatic Primary Amines Leading to 3-Aminohydroisoindol-1-ones

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Yeon Kyu; Cho, Chan Sik; Yoon, Nam Sik [Kyungpook National Univ., Daegu (Korea, Republic of)

    2013-09-15

    It has been shown that 2-bromocyclohex-1-enecarbaldehydes, which are readily prepared from α-methylene containing cyclohexanones under the bromination conditions of Vilsmeier-Haak reaction, undergo carbonylative cyclization with aliphatic primary amines in the presence of a palladium catalyst and a bidentate phosphorus ligand to give 3-aminohydroisoindol-1-ones. The present reaction provides a promising route for the synthesis of valuable heterocycles from readily available starting ketones. Further study of synthetic applications to heterocycles using these ketones is currently under investigation. Palladium-catalyzed carbonylation of organic halides (or triflates) followed by intramolecular cyclization (carbonyl-ative cyclization) has been widely explored and used as a promising synthetic tool for the construction of the structural core of many pharmacologically and biologically active lactones and lactams.

  17. An Efficient One-pot Synthesis of β-Amino/β-Acetamido Car-bonyl Compounds via ZrCl4-catalyzed Mannich-type Reaction

    Institute of Scientific and Technical Information of China (English)

    SANJEEVA REDDY,Cherkupally; PURNACHANDRA REDDY,Gurrala

    2008-01-01

    Zirconium(IV) chloride catalyzed efficient one-pot synthesis of β-amino/β-acetamido carbonyl compounds at room temperature is described. In the presence of ZrCl4, the three-component Mannich-type reaction via a variety of in situ generated aldimines, with various ketones, aromatic aldehydes and aromatic amines in ethanol, led to the formation of β-amino carbonyl compounds and the four-component Mannich-type reaction of aromatic aldehydes with various ketones, acetonitrile and acetyl chloride resulted in the corresponding β-acetamido carbonyl com-pounds in high to excellent yields. This methodology has also been applied towards the synthesis of dimeric β-amino/β-acetamido carbonyl compounds.

  18. A Green Approach for Allylations of Aldehydes and Ketones: Combining Allylborate, Mechanochemistry and Lanthanide Catalyst

    Directory of Open Access Journals (Sweden)

    Viviane P. de Souza

    2016-11-01

    Full Text Available Secondary and tertiary alcohols synthesized via allylation of aldehydes and ketones are important compounds in bioactive natural products and industry, including pharmaceuticals. Development of a mechanochemical method using potassium allyltrifluoroborate salt and water, to successfully perform the allylation of aromatic and aliphatic carbonyl compounds is reported for the first time. By controlling the grinding parameters, the methodology can be selective, namely, very efficient for aldehydes and ineffective for ketones, but by employing lanthanide catalysts, the reactions with ketones can become practically quantitative. The catalyzed reactions can also be performed under mild aqueous stirring conditions. Considering the allylation agent and its by-products, aqueous media, energy efficiency and use of catalyst, the methodology meets most of the green chemistry principles.

  19. Cp*Rh(iii)-catalyzed C(sp(3))-H alkylation of 8-methylquinolines in aqueous media.

    Science.gov (United States)

    Kim, Saegun; Han, Sangil; Park, Jihye; Sharma, Satyasheel; Mishra, Neeraj Kumar; Oh, Hyunjung; Kwak, Jong Hwan; Kim, In Su

    2017-03-09

    The rhodium(iii)-catalyzed cross-coupling reaction of 8-methylquinolines with a range of allylic alcohols in water is described. This approach leads to the synthesis of various γ-quinolinyl carbonyl compounds, which are synthetically useful precursors for the construction of bioactive tetrahydroquinoline and azasteroid derivatives.

  20. New chiral diamino-bis(tert-thiophene): an effective ligand for Pd- and Zn-catalyzed asymmetric transformations.

    Science.gov (United States)

    Bandini, Marco; Melucci, Manuela; Piccinelli, Fabio; Sinisi, Riccardo; Tommasi, Simona; Umani-Ronchi, Achille

    2007-11-21

    Enantiomerically pure diamino-bis(tert-thiophene) proved to be a valuable and flexible chiral ligand for Pd- and Zn-catalyzed transformations, allowing for high levels of stereocontrol in asymmetric allylic alkylation (ee up to 99%) and hydrosilylations of prochiral carbonyls (ee up to 97%).

  1. Palladium-Catalyzed Carbonylation of Aryl Bromides with N-Substituted Cyanamides

    DEFF Research Database (Denmark)

    Lian, Zhong; Friis, Stig D.; Lindhardt, Anders T.;

    2014-01-01

    The palladium(0)-catalyzed three-component coupling reaction of aryl bromides, carbon monoxide, and N-alkyl cyan­amides has been developed employing a two-chamber system with ex situ generation of carbon monoxide from a silacarboxylic acid. The reactions proceeded well and were complete with a re...

  2. Synthesis of 3-Allyl-4-phosphachromones by Cyclized Coupling of Ethyl o-Hydroxyphenyl(ethynyl)phosphinate with Allyl Bromide

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    3-Allyl-4-phosphachromones as the phosphorus analogues of chromone were firstly prepared in good yields and high regioselectivity by the palladium(Ⅱ)-catalyzed cyclized coupling reaction of ethyl o-hydroxyphenyl(ethynyl)-phosphinate with allyl bromide.

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

    Science.gov (United States)

    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.

  4. Transition metal catalysed Grignard-like allylic activation across tetragonal tin(II) oxide

    Indian Academy of Sciences (India)

    Pradipta Sinha; Moloy Banerjee; Abhijit Kundu; Sujit Roy

    2002-08-01

    The reaction of allyl halide and a carbonyl compound under the aegis of tetragonal tin(II) oxide and catalytic 8, 10 metal complexes provides the corresponding homoallylic alcohol, via a novel allyl tin intermediate.

  5. The unexpected mechanism of carbonyl hydrosilylation catalyzed by (Cp)(ArN[double bond, length as m-dash])Mo(H)(PMe(3)).

    Science.gov (United States)

    Shirobokov, Oleg G; Gorelsky, Serge I; Simionescu, Razvan; Kuzmina, Lyudmila G; Nikonov, Georgii I

    2010-11-07

    Complex (Cp)(ArN[double bond, length as m-dash])Mo(H)(PMe(3)) (2, Ar = 2,6-diisopropylphenyl) catalyzes the hydrosilylation of carbonyls by an unexpected associative mechanism. Complex 2 also reacts with PhSiH(3) by a σ-bond metathesis mechanism to give the silyl derivative (Cp)(ArN[double bond, length as m-dash])Mo(SiH(2)Ph)(PMe(3)).

  6. Aerobic Oxidation of Alcohols to Carbonyl Compounds Catalyzed by N-Hydroxyphthalimide (NHPI) Combined with CoTPP-Zn2sub>Al-LDH

    Indian Academy of Sciences (India)

    WEIYOU ZHOU; DONGWEI CHEN; AIJUN CUI; JUNFENG QIAN; MINGYANG HE; QUN CHEN

    2017-03-01

    A catalytic system for the aerobic oxidation of alcohols by N-hydroxyphthalimide (NHPI) combined with cobalt porphyrin intercalated heterogeneous hybrid catalyst (CoTPP-Zn2Al-LDH) has been developed. The results showed that this catalytic system can effectively catalyze the oxidation of alcohols to thecorresponding carbonyl compounds. And the hybrid catalyst can be reused for five times with no appreciable reduction of activity.

  7. Allyl 4-hydroxyphenyl carbonate

    Directory of Open Access Journals (Sweden)

    Víctor Hugo Flores Ahuactzin

    2009-07-01

    Full Text Available The title molecule, C10H10O4, is a functionalized carbonate used in the synthetic route to organic glasses. The central CH fragment of the allyl group is disordered over two positions, with occupancies in a 0.758 (10:0.242 (10ratio. This disorder reflects the torsional flexibility of the oxygen–allyl group, although both disordered parts present the expected anticlinal conformation, with O—CH2—CH=CH2 torsion angles of −111 (2 and 119.1 (4°. The crystal structure is based on chains parallel to [010], formed by O...H—O hydrogen bonds involving hydroxyl and carbonyl groups as donors and acceptors, respectively. The molecular packing is further stabilized by two weak C—H...π contacts from the benzene ring of the asymmetric unit with two benzene rings of neighboring molecules.

  8. Visible-light-induced, Ir-catalyzed reactions of N-methyl-N-((trimethylsilylmethylaniline with cyclic α,β-unsaturated carbonyl compounds

    Directory of Open Access Journals (Sweden)

    Dominik Lenhart

    2014-04-01

    Full Text Available N-Methyl-N-((trimethylsilylmethylaniline was employed as reagent in visible-light-induced, iridium-catalyzed addition reactions to cyclic α,β-unsaturated carbonyl compounds. Typical reaction conditions included the use of one equivalent of the reaction substrate, 1.5 equivalents of the aniline and 2.5 mol % (in MeOH or 1.0 mol % (in CH2Cl2 [Ir(ppy2(dtbbpy]BF4 as the catalyst. Two major reaction products were obtained in combined yields of 30–67%. One product resulted from aminomethyl radical addition, the other product was a tricyclic compound, which is likely formed by attack of the intermediately formed α-carbonyl radical at the phenyl ring. For five-membered α,β-unsaturated lactone and lactam substrates, the latter products were the only products isolated. For the six-membered lactones and lactams and for cyclopentenone the simple addition products prevailed.

  9. Iron-Catalyzed Ortho C-H Methylation of Aromatics Bearing a Simple Carbonyl Group with Methylaluminum and Tridentate Phosphine Ligand.

    Science.gov (United States)

    Shang, Rui; Ilies, Laurean; Nakamura, Eiichi

    2016-08-17

    Iron-catalyzed C-H functionalization of aromatics has attracted widespread attention from chemists in recent years, while the requirement of an elaborate directing group on the substrate has so far hampered the use of simple aromatic carbonyl compounds such as benzoic acid and ketones, much reducing its synthetic utility. We describe here a combination of a mildly reactive methylaluminum reagent and a new tridentate phosphine ligand for metal catalysis, 4-(bis(2-(diphenylphosphanyl)phenyl)phosphanyl)-N,N-dimethylaniline (Me2N-TP), that allows us to convert an ortho C-H bond to a C-CH3 bond in aromatics and heteroaromatics bearing simple carbonyl groups under mild oxidative conditions. The reaction is powerful enough to methylate all four ortho C-H bonds in benzophenone. The reaction tolerates a variety of functional groups, such as boronic ester, halide, sulfide, heterocycles, and enolizable ketones.

  10. Regio-selective synthesis of diversely substituted benzo[a]carbazoles through Rh(iii)-catalyzed annulation of 2-arylindoles with α-diazo carbonyl compounds.

    Science.gov (United States)

    Li, Bin; Zhang, Beibei; Zhang, Xinying; Fan, Xuesen

    2017-01-19

    A novel synthetic approach toward benzo[a]carbazoles or 6-amino benzo[a]carbazoles containing an unprotected NH unit through Rh(iii)-catalyzed cascade reactions of 2-arylindoles or 2-arylindole-3-carbonitriles with α-diazo carbonyl compounds has been established. To our knowledge, this is the first example in which the NH unit of indole is used as a directing group for an intramolecular C(sp(2))-H bond functionalization to give benzo[a]carbazole derivatives. Notably, this method features easily obtainable substrates, good functional group tolerance, excellent regio-selectivity, and high atom-efficiency.

  11. Low-temperature Rh-catalyzed asymmetric 1,4-addition of arylboronic acids to α,β-unsaturated carbonyl compounds.

    Science.gov (United States)

    Korenaga, Toshinobu; Ko, Aram; Shimada, Kazuaki

    2013-10-04

    Rhodium-catalyzed asymmetric 1,4-addition of arylboronic acids to α,β-unsaturated carbonyl compounds was achieved at temperatures below 0 °C using a Rh/MeO-F12-BIPHEP catalyst. The reaction of cyclohexenone or N-R-maleimide with arylboronic acids proceeded even at -80 °C in the presence of the Rh catalyst. In the latter case, high enantioselectivity was observed because a low-temperature method was used, regardless of the type of substituent on maleimide.

  12. 铑催化乙酸乙酯羰基化合成丙酸的研究%Rh Catalyzed Carbonylation of Ethyl Acetate to Propionic Acid

    Institute of Scientific and Technical Information of China (English)

    凌晨; 黄志军

    2013-01-01

    以乙酸乙酯为原料,在金属铑催化下与一氧化碳进行羰基化反应,生成丙酸.研究了碘化物添加剂和反应条件对丙酸产率的影响.由于避免了乙醇在酸性条件下的酯化和分子间脱水等副反应,丙酸产率显著提高.乙酸乙酯羰基化具有与甲醇羰基化相似的动力学行为.碘化物添加剂的加入能有效提高反应速率和丙酸选择性.通过优化反应条件,丙酸产率大于95%.%Rhodium was used to catalyze the carbonylation of ethyl acetate with carbon monoxide to propionic acid.The effect of iodide additives and reaction conditions on yield of propionic acid was studied.Because of avoiding the esterification and intermolecular dehydration of ethanol the yield of propionic acid was improved significantly.The kinetic behavior of ethyl acetate carbonylation was similar with methanol carbonylation.The reaction rate and propionic acid selectivity were increased obviously with the introduction of iodide additives.The propionic acid yield is greater than 95% under the optimum conditions.

  13. Iodine-catalyzed addition of 2-mercaptoethanol to chalcone derivatives: Synthesis of the novel β-mercapto carbonyl compounds

    Directory of Open Access Journals (Sweden)

    Gürkan Yerli

    2012-01-01

    Full Text Available In this study, a series of novel β-mercapto carbonyl derivatives (3-(2-hydroxyethylthio-1,3-diarylpropan-1-one (5a-i were prepared by addition of 2-mercaptoethanol (4 to chalcones (3a-i in the presence of catalytic amount of iodine (10 mol % in CH 2Cl 2.

  14. Pd/C-Catalyzed Carbonylative Esterification of Aryl Halides with Alcohols by Using Oxiranes as CO Sources.

    Science.gov (United States)

    Min, Byul-Hana; Kim, Dong-Su; Park, Hyo-Soon; Jun, Chul-Ho

    2016-04-25

    A carbonylative esterification reaction between aryl bromides and alcohols, promoted by Pd/C and NaF in the presence of oxiranes, has been developed. In this process, oxiranes serve as sources of carbon monoxide by their conversion to aldehydes through a palladium-promoted Meinwald rearrangement pathway. Intramolecular versions of this process serve as methods for the synthesis of lactones and phthalimides.

  15. New Initiation Modes for Directed Carbonylative C–C Bond Activation: Rhodium-Catalyzed (3 + 1 + 2) Cycloadditions of Aminomethylcyclopropanes

    Science.gov (United States)

    2016-01-01

    Under carbonylative conditions, neutral Rh(I)-systems modified with weak donor ligands (AsPh3 or 1,4-oxathiane) undergo N-Cbz, N-benzoyl, or N-Ts directed insertion into the proximal C–C bond of aminomethylcyclopropanes to generate rhodacyclopentanone intermediates. These are trapped by N-tethered alkenes to provide complex perhydroisoindoles. PMID:27709913

  16. γ‐ and δ-Lactams through Palladium-Catalyzed Intramolecular Allylic Alkylation: Enantioselective Synthesis, NMR Investigation, and DFT Rationalization

    DEFF Research Database (Denmark)

    Bantreil, Xavier; Prestat, Guillaume; Moreno, Aitor;

    2011-01-01

    the cyclization reactions to take place in up to 94:6 enantiomeric ratio. A model Pd-allyl complex has been prepared and studied through NMR spectroscopic analysis, which provided insight into the processes responsible for the observed enantiomeric ratios. DFT studies were used to characterize the diastereomeric...

  17. Study towards diversity oriented synthesis of optically active substituted cyclopentane fused carbocyclic and oxacyclic medium-sized rings: Competition between Grubbs-II catalyzed ring closing olefin metathesis and ring closing carbonyl-olefin metathesis

    Indian Academy of Sciences (India)

    P CHAKRABORTY; S C ROY

    2016-12-01

    A study towards diversity-oriented synthesis of optically active cyclopentane fused bicyclic frameworks has been accomplished. The common intermediate was prepared from commercially available starting material (S)-carvone. The observations on competition between Grubbs-II catalyzed ring closing metathesis (RCM) and ring closing carbonyl-olefin metathesis (RCCOM) were the key features of the study.

  18. Fe(Ⅲ)催化的烯丙醇的Friedel-Crafts环化反应合成多取代茚%Synthesis of Multisubstituted Indenes by Fe(Ⅲ)-Catalyzed Friedel-Crafts Cyclization of Allylic Alcohols

    Institute of Scientific and Technical Information of China (English)

    张继坦; 张金花; 方旷; 束官莹; 谢美华

    2012-01-01

    在FeCl3·6H2O催化下,多取代的烯丙醇可以顺利进行分子内Friedel-Crafts环化反应,以中等到优良的产率得到一系列多取代茚化合物,该反应操作简单、反应条件温和.产物结构经IR,1H NMR,13C NMR,HR MS及X射线单晶衍射分析确证.%FeCl3·6H2O-catalyzed intramolecular Friedel-Crafts cyclization of multisubstituted allylic alcohols proceeded smoothly and a series of multisubstituted indenes were synthesized in moderate to high yields. The reaction has the advantages of simple manipulation and mild reaction conditions. The products were characterized by IR, 'H NMR, 13C NMR, HR MS and X-ray diffraction analysis.

  19. Stereoselective synthesis of tricyclic compounds by intramolecular palladium-catalyzed addition of aryl iodides to carbonyl groups

    Science.gov (United States)

    Saadi, Jakub; Bentz, Christoph; Redies, Kai; Lentz, Dieter; Zimmer, Reinhold

    2016-01-01

    Summary Starting from γ-ketoesters with an o-iodobenzyl group we studied a palladium-catalyzed cyclization process that stereoselectively led to bi- and tricyclic compounds in moderate to excellent yields. Four X-ray crystal structure analyses unequivocally defined the structure of crucial cyclization products. The relative configuration of the precursor compounds is essentially transferred to that of the products and the formed hydroxy group in the newly generated cyclohexane ring is consistently in trans-arrangement with respect to the methoxycarbonyl group. A transition-state model is proposed to explain the observed stereochemical outcome. This palladium-catalyzed Barbier-type reaction requires a reduction of palladium(II) back to palladium(0) which is apparently achieved by the present triethylamine. PMID:27559374

  20. High efficient acetalization of carbonyl compounds with diols catalyzed by novel carbon-based solid strong acid catalyst

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The novel carbon-based acid catalyst has been applied to catalyzing the acetalization and ketalization. The results showed that the catalyst was very efficient with the average yield over 93%. The novel heterogeneous catalyst has the advantages of high activity, wide applicability even to 7-membered ring acetals, strikingly simple workup procedure, non-pollution, and reusability, which will contribute to the green process greatly.

  1. Interception and characterization of catalyst species in rhodium bis(diazaphospholane)-catalyzed hydroformylation of octene, vinyl acetate, allyl cyanide, and 1-phenyl-1,3-butadiene.

    Science.gov (United States)

    Nelsen, Eleanor R; Brezny, Anna C; Landis, Clark R

    2015-11-11

    In the absence of H2, reaction of [Rh(H) (CO)2(BDP)] [BDP = bis(diazaphospholane)] with hydroformylation substrates vinyl acetate, allyl cyanide, 1-octene, and trans-1-phenyl-1,3-butadiene at low temperatures and pressures with passive mixing enables detailed NMR spectroscopic characterization of rhodium acyl and, in some cases, alkyl complexes of these substrates. For trans-1-phenyl-1,3-butadiene, the stable alkyl complex is an η(3)-allyl complex. Five-coordinate acyl dicarbonyl complexes appear to be thermodynamically preferred over the four-coordinate acyl monocarbonyls at low temperatures and one atmosphere of CO. Under noncatalytic (i.e., no H2 present) reaction conditions, NMR spectroscopy reveals the kinetic and thermodynamic selectivity of linear and branched acyl dicarbonyl formation. Over the range of substrates investigated, the kinetic regioselectivity observed at low temperatures under noncatalytic conditions roughly predicts the regioselectivity observed for catalytic transformations at higher temperatures and pressures. Thus, kinetic distributions of off-cycle acyl dicarbonyls constitute reasonable models for catalytic selectivity. The Wisconsin high-pressure NMR reactor (WiHP-NMRR) enables single-turnover experiments with active mixing; such experiments constitute a powerful strategy for elucidating the inherent selectivity of acyl formation and acyl hydrogenolysis in hydroformylation reactions.

  2. A broadly applicable NHC-Cu-catalyzed approach for efficient, site-, and enantioselective coupling of readily accessible (pinacolato)alkenylboron compounds to allylic phosphates and applications to natural product synthesis.

    Science.gov (United States)

    Gao, Fang; Carr, James L; Hoveyda, Amir H

    2014-02-05

    A set of protocols for catalytic enantioselective allylic substitution (EAS) reactions that allow for additions of alkenyl units to readily accessible allylic electrophiles is disclosed. Transformations afford 1,4-dienes that contain a tertiary carbon stereogenic site and are promoted by 1.0-5.0 mol % of a copper complex of an N-heterocyclic carbene (NHC). Aryl- as well as alkyl-substituted electrophiles bearing a di- or trisubstituted alkene may be employed. Reactions can involve a variety of robust alkenyl-(pinacolatoboron) [alkenyl-B(pin)] compounds that can be either purchased or prepared by various efficient, site-, and/or stereoselective catalytic reactions, such as cross-metathesis or proto-boryl additions to terminal alkynes. Vinyl-, E-, or Z-disubstituted alkenyl-, 1,1-disubstituted alkenyl-, acyclic, or heterocyclic trisubstituted alkenyl groups may be added in up to >98% yield, >98:2 SN2':SN2, and 99:1 enantiomeric ratio (er). NHC-Cu-catalyzed EAS with alkenyl-B(pin) reagents containing a conjugated carboxylic ester or aldehyde group proceed to provide the desired 1,4-diene products in good yield and with high enantioselectivity despite the presence of a sensitive stereogenic tertiary carbon center that could be considered prone to epimerization. In most instances, the alternative approach of utilizing an alkenylmetal reagent (e.g., an Al-based species) represents an incompatible option. The utility of the approach is illustrated through applications to enantioselective synthesis of natural products such as santolina alcohol, semburin, nyasol, heliespirone A, and heliannuol E.

  3. Cobalt-catalyzed C-H olefination of aromatics with unactivated alkenes.

    Science.gov (United States)

    Manoharan, Ramasamy; Sivakumar, Ganesan; Jeganmohan, Masilamani

    2016-08-18

    A cobalt-catalyzed C-H olefination of aromatic and heteroaromatic amides with unactivated alkenes, allyl acetates and allyl alcohols is described. This method offers an efficient route for the synthesis of vinyl and allyl benzamides in a highly stereoselective manner. It is observed that the ortho substituent on the benzamide moiety is crucial for the observation of allylated products in unactivated alkenes.

  4. Palladium-catalyzed Reppe carbonylation.

    Science.gov (United States)

    Kiss, G

    2001-11-01

    PdX2L2/L/HA (A = weakly coordinating anion, L = phosphine) complexes are active catalysts in the hydroesterification of alkenes, alkynes, and conjugated dienes. Shell, the only major corporate player in the field, recently developed two very active catalyst systems tailored to the hydroesterification of either alkenes or alkynes. The hydroesterification of propyne with their Pd(OAc)2/PN/HA (PN = (2-pyridyl)diphenylphosphine, HA = strong acid with weakly coordinating anion, like methanesulfonic acid) catalyst has been declared commercially ready. However, despite the significant progress in the activity of Pd-hydroesterification catalysts, further improvements are warranted. Thus, for example, activity maintenance still seems to be an issue. Homogeneous Pd catalysts are prone to a number of deactivation reactions. Activity and stability promoters are often corrosive and add to the complexity of the system, making it less attractive. Nonetheless, the versatility of the process and its tolerance toward the functional groups of substrates should appeal especially to the makers of specialty products. Although hydroesterification yields esters from alkenes, alkynes, and dienes in fewer steps than hydroformylation does, the latter has some advantages at the current state of the art. (1) Hydroformylation catalysts, particularly some recently published phosphine-modified Rh systems, can achieve very high regioselectivity for the linear product that hydroesterification catalysts cannot match yet. By analogy with hydroformylation, bulkier ligands ought to be tested in hydroesterification to increase normal-ester selectivity. (2) Hydroformylation is proven, commercial. Hydroesterification can only replace it if it can provide significant economic incentives. Similar or just marginally better performance could not justify the cost of development of a new technology. (3) Hydroesterification requires pure CO while hydroformylation uses syngas, a mixture of CO and H2. The latter is typically more available and less expensive (for industrial applications CO is most often separated from syngas). (4) The acid component of the hydroesterification catalyst makes the process corrosive. It would be desirable to develop new hydroesterification catalysts that do not require acid stabilizer/activity booster. Clearly, any new hydroesterification technology will directly compete with the hydroformylation route. This is especially true for olefin feeds, since both processes add one CO to the olefin, yielding oxygenates that can be converted into identical products. For some niche applications, like the production of MMA from propyne, hydroesterification seems to have an advantage as compared to hydroformylation due to the high activity and selectivity of the Pd(OAc)2/(2-pyridyl)diphenylphosphine catalyst. Since hydroesterification is an emerging technology, it is reasonable to assume that the potential for improvement is greater than in the mature hydroformylation. It is therefore possible that hydroesterification will become competitive in the future; thus, continued effort in the field is warranted.

  5. Enantioselective, iridium-catalyzed monoallylation of ammonia.

    Science.gov (United States)

    Pouy, Mark J; Stanley, Levi M; Hartwig, John F

    2009-08-19

    Highly enantioselective, iridium-catalyzed monoallylations of ammonia are reported. These reactions occur with electron-neutral, -rich, and -poor cinnamyl carbonates, alkyl and trityloxy-substituted allylic carbonates, and dienyl carbonates in moderate to good yields and excellent enantioselectivities. This process is enabled by the use of an iridium catalyst that does not require a Lewis acid for activation and that is stable toward a large excess of ammonia. This selective formation of primary allylic amines allows for one-pot syntheses of heterodiallylamines and allylic amides that are not otherwise accessible via iridium-catalyzed allylic amination without the use of blocking groups and protective group manipulations.

  6. An Unexpected Reaction of Allylic Propynoate under Palladium(Ⅱ) Catalysis

    Institute of Scientific and Technical Information of China (English)

    ZHANG,Zhao-Guo(张兆国); LU,Xi-Yan(陆熙炎); LANG,Shen-Hui(郎深慧)

    2002-01-01

    Palladium (Ⅱ) catalyzed reactions of allyl propynoate in the presence of excess halide ions with or without allyl halide or acrolein were studied, yielding (E)-3-halo-2-allyl-acrylic acid as the sole product. A mechanism involving halopalladation, carbopalladation, ring opening and β-heteroatom elimination was prioposed and was further justified by the reaction with deuterated substrate.keywords palladium, enyne, halopalladation, carbopalladation,β-heteroatom elimination was proposed and was further justified by the reaction with deuterated substrate.

  7. CATALYTIC ENANTIOSELECTIVE ALLYLIC OXIDATION

    NARCIS (Netherlands)

    Rispens, Minze T.; Zondervan, Charon; Feringa, Bernard

    1995-01-01

    Several chiral Cu(II)-complexes of cyclic amino acids catalyse the enantioselective allylic oxidation of cyclohexene to cyclohexenyl esters. Cyclohexenyl propionate was obtained in 86% yield with e.e.'s up to 61%.

  8. Kinetics of the Double Carbonylation of Benzylchloride

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    It is a multi-phase-catalyzed reaction to produce calcium phenylpyruvate by double carbonylation of benzylchloride. Based on the analysis of the reaction mechanism, a kinetic model of the carbonylation reaction was obtained. The model was verified through experiments in which the diffusion effect was neglected with the appropriate operation manner. But it is inevitable that the carbonylation process is controlled by diffusion as the autoclave scaling up.

  9. Synthesis of acrylic and allylic bifunctional cross-linking monomers derived from PET waste

    Science.gov (United States)

    Cruz-Aguilar, A.; Herrera-González, A. M.; Vázquez-García, R. A.; Navarro-Rodríguez, D.; Coreño, J.

    2013-06-01

    An acrylic and two novel allylic monomers synthesized from bis (hydroxyethyl) terephthalate, BHET, are reported. This was obtained by glycolysis of post-consumer PET with boiling ethylene glycol. The bifunctional monomer bis(2-(acryloyloxy)ethyl) terephthalate was obtained from acryloyl chloride, while the allylic monomers 2-(((allyloxi)carbonyl)oxy) ethyl (2-hydroxyethyl) terephthalate and bis(2-(((allyloxi)carbonyl)oxy)ethyl) terephthalate, from allyl chloroformate. Cross-linking was studied in bulk polymerization using two different thermal initiators. Monomers were analyzed by means of 1H NMR and the cross-linked polymers by infrared spectroscopy. Gel content higher than 90% was obtained for the acrylic monomer. In the case of the mixture of the allylic monomers, the cross-linked polymer was 80 % using BPO initiator, being this mixture 24 times less reactive than the acrylic monomer.

  10. A New Route to Biaryl Ketones via Carbonylative Suzuki Coupling Catalyzed by MCM-41-supported Bidentate Phosphine Palladium(O) Complex

    Institute of Scientific and Technical Information of China (English)

    ZHENG, Guomin; WANG, Pingping; CAI, Mingzhong

    2009-01-01

    A variety of biaryl ketones can be conveniently synthesized in good to high yields via the first heterogeneous carbonylative Suzuki coupling of arylboronic acids with aryl iodides under atmospheric pressure of carbon monox- ide in the presence of a catalytic amount of MCM-41-supported bidentate phosphine palladium(0) complex [MCM-41-2P-Pd(0)]. This polymeric palladium catalyst can be reused at least 10 times without any decrease in ac- tivity.

  11. 有机金催化胺氧化羰化制氨基甲酸酯%The Oxidative Carbonylation of Amines Catalyzed by Organic Gold(Ⅰ) Complexes

    Institute of Scientific and Technical Information of China (English)

    石峰; 邓友全; 司马天龙; 龚成科

    2001-01-01

    At 200 ℃ and 50 mPa, the oxidative carbonylation of amines catalyzed by organic gold complexes HAuCl4, Au(PPh3)Cl, Au(PPh3)2Cl, Au(PPh3)NO3 and [Au(PPh3)]2S afforded R(NHCO2CH3)n with a high conversion and selectivity. The best results were obtained when using the catalyst Au(PPh3)Cl in the presence of PPh3. The catalytic efficiency of catalytic Au(PPh3)Cl was compared to Pd(PPh3)2Cl2, e.g. the conversion was 97.2% and selectivity was 89% when using catalyst Au(PPh3)Cl in the presence of PPh3, while the conversion was 98.8% and selectivity was 86% when using catalyst Pd(PPh3)2Cl2 in the presence of PPh3. The experimental results suggested that Au complexes might be promising catalysts instead of Pd catalysts for the oxidative carbonylation of amines to carbamates.

  12. Fish Proteins as Targets of Ferrous-Catalyzed Oxidation: Identification of Protein Carbonyls by Fluorescent Labeling on Two-Dimensional Gels and MALDI-TOF/TOF Mass Spectrometry

    DEFF Research Database (Denmark)

    Pazos, Manuel; da Rocha, Angela Pereira; Roepstorff, Peter

    2011-01-01

    Protein oxidation in fish meat is considered to affect negatively the muscle texture. An important source of free radicals taking part in this process is Fenton's reaction dependent on ferrous ions present in the tissue. The aim of this study was to investigate the susceptibility of cod muscle......, indicating that post-translational modifications may change the resistance of proteins to oxidative damage. The Fe(II)/ascorbate treatment significantly increased carbonylation of important structural proteins in fish muscle, mainly actin and myosin, and degradation products of those proteins were observed...

  13. Acetalization of carbonyl compounds with 2,2,4-trimethyl-1,3-pentanedio catalyzed by novel carbon based solid acid catalyst

    Institute of Scientific and Technical Information of China (English)

    Ling Liu; Yuechang Zhao; Shan Gan; Xuezheng Liang; Jianguo Yang; Mingyuan He

    2008-01-01

    The synthesis of 2, 4-diisopropyl-5,5-dimethyl-1,3-dioxane through the acetalization of isobutyraldehyde with 2, 2,4-trimethyl-1,3-pentanediol (TMPD) catalyzed by the novel carbon based acid was first carried out. High conversion (≥98%) and specific selectivity were obtained using the novel carbon based acid, which kept high activity after it was reused 5 times.Moreover, the catalyst could be used to catalyze the acetalization and ketalization of different aldehydes and ketones with superior yield. The yield of several products was over 90%. The novel heterogeneous catalyst has the distinct advantages of high activity, strikingly simple workup procedure, non-pollution, and reusability, which will contribute to the success of the green process greatly.

  14. Experimental Design-Based Response Surface Methodology Optimization for Synthesis of β-Mercapto Carbonyl Derivatives as Antimycobacterial Drugs Catalyzed by Calcium Pyrophosphate

    Directory of Open Access Journals (Sweden)

    Younes Abrouki

    2014-01-01

    Full Text Available A simple protocol for the efficient preparation of β-mercapto carbonyl derivatives as antimycobacterial drugs has been achieved via Thia-Michael reaction between chalcones derivatives and thiols in the presence of calcium pyrophosphate as a heterogeneous catalyst under mild reaction conditions. The central composite design was used to design an experimental program to provide data to model the effects of various factors on reaction yield (Y. The variables chosen were catalyst weight X1, reaction time X2, and solvent volume X3. The mathematical relationship of reaction yield on the three significant independent variables can be approximated by a nonlinear polynomial model. Predicted values were found to be in good agreement with experimental values. The optimum reaction conditions for reaction model (chalcone and thiophenol obtained by response surface were applied to other substrates. This procedure provides several advantages such as high yield, clean product formation, and short reaction time.

  15. An Efficient Synthesis of de novo Imidates via Aza-Claisen Rearrangements of N-Allyl Ynamides.

    Science.gov (United States)

    Dekorver, Kyle A; North, Troy D; Hsung, Richard P

    2010-10-01

    A novel thermal 3-aza-Claisen rearrangement of N-allyl ynamides for the synthesis of α-allyl imidates is described. Also, a sequential aza-Claisen, Pd-catalyzed Overman rearrangement is described for the synthesis of azapine-2-ones.

  16. First Magnesium-mediated Carbonyl Benzylation in Water

    Institute of Scientific and Technical Information of China (English)

    DENG,Wei(邓维); TAN,Xiang-Hui(谭翔辉); LIU,Lei(刘磊); GUO,Qing-Xiang(郭庆祥)

    2004-01-01

    Catalyzed by AgNO3, Mg was found for the first time to be able to mediate the coupling reaction between aromatic aldehydes and benzyl bromide or chloride in water. The yields were slightly higher than the recent results for Mg-mediated allylation despite the fact that aqueous benzylation is intrinsically much harder than allylation. It was also found that the coupling reaction was chemoselective for aromatic aldehydes over aliphatic aldehydes, and chemoselective for aromatic aldehydes over aromatic ketones.

  17. Facile coupling of propargylic, allylic and benzylic alcohols with allylsilane and alkynylsilane, and their deoxygenation with Et3SiH, catalyzed by Bi(OTf)3 in [BMIM][BF4] ionic liquid (IL), with recycling and reuse of the IL.

    Science.gov (United States)

    Kumar, G G K S Narayana; Laali, Kenneth K

    2012-09-28

    Allyltrimethylsilane (allyl-TMS) reacts with propargylic alcohols 1a-1d in the presence of 10% Bi(OTf)(3) in [BMIM][BF(4)] solvent to furnish the corresponding 1,5-enynes in respectable isolated yields (87-93%) at room temperature. The utility of Bi(OTf)(3) as a superior catalyst was demonstrated in a survey study on coupling of allyl-TMS with employing several metallic triflates (Bi, Ln, Al, Yb) as well as, B(C(6)F(5))(3), Zn(NTf(2))(2) and Bi(NO(3))(3)·5H(2)O. Coupling of cyclopropyl substituted propargylic alcohol with allyl-TMS gave the skeletally intact 1,5-enyne and a ring opened derivative as a mixture. Coupling of propargylic/allylic alcohol with allyl-TMS resulted in allylation at both benzylic (2 isomers) and propargylic positions, as major and minor products respectively. The scope of this methodology for allylation of a series of allylic and benzylic alcohols was explored. Chemoselective reduction of a host of propargylic, propagylic/allylic, bis-allylic, allylic, and benzylic alcohols with Et(3)SiH was achieved in high yields with short reaction times. The same approach was successfully applied to couple representative propargylic and allylic alcohols with 1-phenyl-2-trimethylsilylacetylene. The recovery and reuse of the ionic liquid (IL) was gauged in a case study with minimal decrease in isolated yields after six cycles.

  18. Tsuji-Trost N-allylation with allylic acetates using cellulose-Pd catalyst

    Science.gov (United States)

    Allylic amines are synthesized using heterogeneous cellulose-Pd catalyst via N-allylation of amines; aliphatic and benzyl amines undergo facile reaction with substituted and unsubstituted allyl acetates in high yields.

  19. Organocatalytic asymmetric allylic amination of Morita–Baylis–Hillman carbonates of isatins

    Directory of Open Access Journals (Sweden)

    Hang Zhang

    2012-08-01

    Full Text Available The investigation of a Lewis base catalyzed asymmetric allylic amination of Morita–Baylis–Hillman carbonates derived from isatins afforded an electrophilic pathway to access multifunctional oxindoles bearing a C3-quaternary stereocenter, provided with good to excellent enantioselectivity (up to 94% ee and in high yields (up to 97%.

  20. 壳聚糖席夫碱钴催化环己烯烯丙位氧化反应的研究%Allylic oxidation of cyclohexene catalyzed by chitosan Schiff base cobalt catalyst

    Institute of Scientific and Technical Information of China (English)

    刘丽君; 慈英倩; 刘翠娥; 高洪霞; 崔庆新

    2014-01-01

    制备了壳聚糖( CS)水杨醛席夫碱钴配合物,利用X射线粉末衍射( XRD)、红外( IR)等方法对其结构特征进行了分析,并以氧气为氧化剂,评价了该配合物的环己烯氧化催化性能,初步考察了催化剂用量、反应温度以及反应时间等因素对氧化反应的影响。实验结果表明:CS-席夫碱钴配合物具有良好的环己烯催化氧化活性和较高的烯丙位氧化选择性,在较优条件下,环己烯转化率和烯丙位氧化选择性分别达到85.3%和81.3%;催化剂具有较好的稳定性,易分离可多次重复使用。%A chitosan-schiff base cobalt comples( CS-Schiff base-Co) was prepared and characterized by X-ray diffraction,infrared spectroscopy and TG method,as well as the catalytic properties of this complex in oxidation of cyclohexene were studied in the pres-ence of oxygen. And the influences of the amount of catalyst,reaction temperature and reaction time on oxidation were also investiga-ted. These results indicated that CS-Schiff base-Co catalyst had excellent catalytic activity and selectivity for the allylic oxidation in cyclohexene. The conversion and selectivity were 85. 3%and 81. 3%under suitable conditons,respectively. The catalyst was perfect-ly leach-proof and could be resued at least four times.

  1. 全氟丁基磺酸锡催化醛烯丙基化和Mukaiyama-aldol反应%Bisperfluorobutylsulfonate Bisbutyltin Catalyzed Allylation and Mukaiyama-aldol Reaction of Aldehyde

    Institute of Scientific and Technical Information of China (English)

    刘毅; 王勰; 陈锦杨; 李宁波; 许新华

    2012-01-01

    二丁基二氯化锡与全氟丁基磺酸银在丙酮中室温反应,得到二丁基二全氟丁基磺酸锡.该配合物在空气中放置2d,1H NMR表明其结构未发生变化,TG-DSC表明在220℃是稳定的;配合物C4F9SO3)2SnBu2能溶解在乙酸乙酯、丙酮、乙腈、四氢呋喃、乙醚等极性有机溶剂中,但室温下,在非极性溶剂己烷、二氯甲烷、甲苯中不溶.以乙腈作溶剂,室温下,(C4F9SO3)2SnBu2的用量分别为1.0和5.0 mol%,醛的烯丙基化反应和Mukaiyama-aldol反应有效进行,高产率得到对应产物.%Bisperfluorobutylsulfonate bisbutyltin complex was successfully synthesized by treating C4F9SO3Ag with Bu2SnCl2 in acetone at room temperature. When the complex was exposed to air two days, 1H NMR spectra showed that its structure had no change. TG-DSC showed that the complex was stable below 220 ℃. The complex had a good solubility in polar solvents, such as ethyl acetate, acetone, acetonitrile, THF, ethyl ether. But it was poor soluble in hexane, CH2Cl2, toluene at room temperature. In the presence of 1.0 and 5.0 mol% of bisperfluorobutylsulfonate bisbutyltin respectively, allylation of aldehyde and Mukaiyama aldol reaction could efficiently occur in CH3CN at room temperature and give high yield of the corresponding products.

  2. Palladium-Catalyzed Environmentally Benign Acylation.

    Science.gov (United States)

    Suchand, Basuli; Satyanarayana, Gedu

    2016-08-05

    Recent trends in research have gained an orientation toward developing efficient strategies using innocuous reagents. The earlier reported transition-metal-catalyzed carbonylations involved either toxic carbon monoxide (CO) gas as carbonylating agent or functional-group-assisted ortho sp(2) C-H activation (i.e., ortho acylation) or carbonylation by activation of the carbonyl group (i.e., via the formation of enamines). Contradicting these methods, here we describe an environmentally benign process, [Pd]-catalyzed direct carbonylation starting from simple and commercially available iodo arenes and aldehydes, for the synthesis of a wide variety of ketones. Moreover, this method comprises direct coupling of iodoarenes with aldehydes without activation of the carbonyl and also without directing group assistance. Significantly, the strategy was successfully applied to the synthesis n-butylphthalide and pitofenone.

  3. A one-pot stereoselective synthesis of 1,4-dienyl selenides by hydrostannylation-Stille tandem reaction of acetylenic selenides with Bu3SnH and allylic bromides

    Institute of Scientific and Technical Information of China (English)

    La Mei Yu; Wen Yan Hao; Ming Zhong Cai

    2008-01-01

    1,4-Dienyl selenides can be stereoselectively synthesized in one pot under mild conditions in good yields by the palladium-catalyzed hydrostannylation of acetylenic selenides, followed by Stille coupling with allylic bromides.

  4. The allylic chalcogen effect in olefin metathesis

    Directory of Open Access Journals (Sweden)

    Yuya A. Lin

    2010-12-01

    Full Text Available Olefin metathesis has emerged as a powerful tool in organic synthesis. The activating effect of an allylic hydroxy group in metathesis has been known for more than 10 years, and many organic chemists have taken advantage of this positive influence for efficient synthesis of natural products. Recently, the discovery of the rate enhancement by allyl sulfides in aqueous cross-metathesis has allowed the first examples of such a reaction on proteins. This led to a new benchmark in substrate complexity for cross-metathesis and expanded the potential of olefin metathesis for other applications in chemical biology. The enhanced reactivity of allyl sulfide, along with earlier reports of a similar effect by allylic hydroxy groups, suggests that allyl chalcogens generally play an important role in modulating the rate of olefin metathesis. In this review, we discuss the effect of allylic chalcogens in olefin metathesis and highlight its most recent applications in synthetic chemistry and protein modifications.

  5. The allylic chalcogen effect in olefin metathesis

    Science.gov (United States)

    Lin, Yuya A

    2010-01-01

    Summary Olefin metathesis has emerged as a powerful tool in organic synthesis. The activating effect of an allylic hydroxy group in metathesis has been known for more than 10 years, and many organic chemists have taken advantage of this positive influence for efficient synthesis of natural products. Recently, the discovery of the rate enhancement by allyl sulfides in aqueous cross-metathesis has allowed the first examples of such a reaction on proteins. This led to a new benchmark in substrate complexity for cross-metathesis and expanded the potential of olefin metathesis for other applications in chemical biology. The enhanced reactivity of allyl sulfide, along with earlier reports of a similar effect by allylic hydroxy groups, suggests that allyl chalcogens generally play an important role in modulating the rate of olefin metathesis. In this review, we discuss the effect of allylic chalcogens in olefin metathesis and highlight its most recent applications in synthetic chemistry and protein modifications. PMID:21283554

  6. Interplay of metal-allyl and metal-metal bonding in dimolybdenum allyl complexes

    Energy Technology Data Exchange (ETDEWEB)

    John, Kevin D [Los Alamos National Laboratory; Martin, Richard L [Los Alamos National Laboratory; Obrey, Steven J [Los Alamos National Laboratory; Scott, Brian L [Los Alamos National Laboratory

    2008-01-01

    Addition of PMe{sub 3} to Mo{sub 2}(allyl){sub 4} afforded Mo{sub 2}(allyl){sub 4}(PMe{sub 3}){sub 2}, in which two of the allyl groups adopt an unprecedented {mu}{sub 2{sup -}}{eta}{sup 1}, {eta}{sup 3} bonding mode; theoretical studies elucidate the role sof the {sigma}- and {pi}-donor ligands in the interplay of metal-allyl and metal-metal bonding.

  7. Asymmetric allylic alkylation in combination with ring-closing metathesis for the preparation of chiral N-heterocycles

    NARCIS (Netherlands)

    Teichert, Johannes F.; Zhang, Suyan; Zijl, Anthoni W. van; Slaa, Jan Willem; Minnaard, Adriaan J.; Feringa, Bernard

    2010-01-01

    Asymmetric copper-catalyzed allylic substitution with methylmagnesium bromide is employed in combination with ring-closing olefin metathesis or ene-yne metathesis to achieve the synthesis of chiral, unsaturated nitrogen heterocycles. The resulting six- to eight-membered chiral heterocycles are acces

  8. Efficient and selective α-bromination of carbonyl compounds with N-bromosuccinimide under microwave

    KAUST Repository

    Guan, Xiao-Yu

    2014-02-07

    A highly efficient method for the synthesis of α-halocarbonyl compounds has been achieved via selective monobromination of aromatic and aliphatic carbonyl compounds with N-bromosuccinimide catalyzed by p-toluenesulfonic acid under microwave irradiation within 30 min.

  9. Synthetic Studies on Tricyclic Diterpenoids: Direct Allylic Amination Reaction of Isopimaric Acid Derivatives.

    Science.gov (United States)

    Timoshenko, Mariya A; Kharitonov, Yurii V; Shakirov, Makhmut M; Bagryanskaya, Irina Yu; Shults, Elvira E

    2016-02-01

    A selective synthesis of 7- or 14-nitrogen containing tricyclic diterpenoids was completed according to a strategy in which the key step was the catalyzed direct allylic amination of methyl 14α-hydroxy-15,16-dihydroisopimarate with a wide variety of nitrogenated nucleophiles. It was revealed that the selectivity of the reaction depends on the nature of nucleophile. The catalyzed reaction of the mentioned diterpenoid allylic alcohol with 3-nitroaniline, 3-(trifluoromethyl)aniline, and 4-(trifluoromethyl)aniline yield the subsequent 7α-, 7β- and 14αnitrogen-containing diterpenoids. The reaction with 2-nitroaniline, 4-nitro-2-chloroaniline, 4-methoxy-2-nitroaniline, phenylsulfamide, or tert-butyl carbamate proceeds with the formation of 7α-nitrogen-substituted diterpenoids as the main products.

  10. Gold-Catalyzed Synthesis of Heterocycles

    Science.gov (United States)

    Arcadi, Antonio

    2014-04-01

    The following sections are included: * Introduction * Synthesis of Heterocycles via Gold-Catalyzed Heteroatom Addition to Unsaturated C-C Bonds * Synthesis of Heterocyclic Derivatives through Gold-Catalyzed Cyclization of Polyunsaturated Compounds * Synthesis of Heterocyclic Compounds via α-Oxo Gold Carbenoid * Synthesis of Heterocyclic Derivatives through Gold-Catalyzed Cycloaddition Reactions * Synthesis of Heterocyclic Derivatives through Gold-Catalyzed Activation of Carbonyl Groups and Alcohols * Synthesis of Heterocyclic Compounds through Gold-Mediated C-H Bond Functionalization * Gold-Catalyzed Domino Cyclization/Oxidative Coupling Reactions * Conclusions * References

  11. On the key role of water in the allylic activation catalysed by Pd (II) bisphosphinite complexes

    Indian Academy of Sciences (India)

    Rakesh Kumar Sharma; Ashoka G Samuelson

    2006-11-01

    Palladium and platinum complexes of bisphosphinites and bisphosphines derived from mandelic acid have been prepared and characterized. Their ability to catalyze allylation of imines with allyltributylstannane has been studied. Bisphophinite complexes of Pd (II) are shown to be ideal and they work best in the presence of one equivalent of water. The near neutral conditions employed make the catalysts suitable for a wide variety of substrates.

  12. Synthesis of heterocycles through transition-metal-catalyzed isomerization reactions

    DEFF Research Database (Denmark)

    Ishøy, Mette; Nielsen, Thomas Eiland

    2014-01-01

    of structurally complex and diverse heterocycles. In this Concept article, we attempt to cover this area of research through a selection of recent versatile examples. A sea of opportunities! Transition-metal-catalyzed isomerization of N- and O-allylic compounds provides a mild, selective and synthetically......Metal-catalyzed isomerization of N- and O-allylic systems is emerging as an effective method to form synthetically useful iminium and oxocarbenium intermediates. In the presence of tethered nucleophiles, several recent examples illuminate this approach as a powerful strategy for the synthesis...

  13. Synthetic Study of Dragmacidin E: Construction of the Core Structure Using Pd-Catalyzed Cascade Cyclization and Rh-Catalyzed Aminoacetoxylation.

    Science.gov (United States)

    Inoue, Naoya; Nakano, Shun-Ichi; Harada, Shingo; Hamada, Yasumasa; Nemoto, Tetsuhiro

    2017-03-03

    We developed a novel synthetic method of the core structure of dragmacidin E bearing a 7-membered ring-fused bis(indolyl)pyrazinone skeleton. Formation of the 7-membered ring-fused tricyclic indole skeleton was accomplished using a palladium-catalyzed Heck insertion-allylic amination cascade. Vicinal difunctionalization of the 7-membered ring was realized via a rhodium-catalyzed aminoacetoxylation.

  14. Highly enantio- and diastereoselective allylic alkylation of Morita-Baylis-Hillman carbonates with allyl ketones

    KAUST Repository

    Tong, Guanghu

    2013-05-17

    The asymmetric allylic alkylation of Morita-Baylis-Hillman (MBH) carbonates with allyl ketones has been developed. The α-regioselective alkylation adducts, containing a hexa-1,5-diene framework with important synthetic value, were achieved in up to 83% yield, >99% ee, and 50:1 dr by using a commercially available Cinchona alkaloid as the catalyst. From the allylic alkylation adduct, a cyclohexene bearing two adjacent chiral centers was readily prepared. © 2013 American Chemical Society.

  15. Regio- and Stereospecific Formation of Protected Allylic Alcohols via Zirconium-Mediated SN2' Substitution of Allylic Chlorides

    OpenAIRE

    Fox, Richard J; Lalic, Gojko; Bergman, Robert G.

    2007-01-01

    A new, highly regio- and stereospecific SN2' substitution reaction between a zirconium oxo complex and allylic chloride has been achieved. The resulting allylic alcohol or TBS-protected allylic ether products were isolated in good to excellent yields with a wide range of E-allylic chlorides. A mechanism for the SN2' allylic substitution consistent with kinetic, stereochemical and secondary isotope effect studies was proposed.

  16. [bmim][Br] as a solvent and activator for the Ga-mediated Barbier allylation: direct formation of an N-heterocyclic carbene from Ga metal.

    Science.gov (United States)

    Goswami, Dibakar; Chattopadhyay, Angshuman; Sharma, Anubha; Chattopadhyay, Subrata

    2012-12-21

    The room-temperature ionic liquid (RTIL) [bmim][Br] has been found to be an excellent green and inexpensive medium for the Ga-mediated allylation of aromatic and aliphatic aldehydes and ketones. The RTIL activated the metal via formation of a Ga-N-heterocyclic carbene complex that assisted in the completion of the reaction at ambient temperature with only 0.5 equiv of Ga and 1.2 equiv of allyl bromide with respect to the carbonyl substrates. The present protocol required a much shorter time than those reported in the literature using other metals and solvents and proceeded with good yields and excellent selectivity.

  17. Metal-free carbonylations by photoredox catalysis.

    Science.gov (United States)

    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.

  18. Hydroformylation of butyl acrylate catalyzed by water-soluble rhodium carbonyl complexes%水溶性铑羰基配合物催化丙烯酸丁酯的氢甲酰化反应

    Institute of Scientific and Technical Information of China (English)

    黄雪原; 李贤均

    2004-01-01

    The hydroformylation of butyl acrylate was carried out in biphasic system water/toluene in the presence of rhodium carbonyl complexes with the water-soluble ligands to produce the effects of the temperature, ligand-to-rhodium ratio, hydrogen and carbon monoxide partial pressures on the activity and selectivity of the reaction. The performance of monophosphine ligand(TPPTS) was compared with that of diphosphine ligand(BDPXS).%在两相催化体系水/甲苯中,考察了反应温度、配体与催化剂摩尔比率、氢气/一氧化碳压力比对铑羰基配合物与水溶性膦配体催化丙烯酸丁酯的氢甲酰化反应的催化活性和选择性的影响,并比较了单膦配体(TPPTS)和双膦配体(BDPXS)的催化性能.

  19. Chiral N,N’-Dioxide-Ni(Ⅱ) Complex Catalyzed Asymmetric Carbonyl-Ene Reaction of Ethyl Trifluoropyruvate%手性氮氧-Ni(Ⅱ)络合物催化三氟甲基酮酸酯的不对称羰基ene反应

    Institute of Scientific and Technical Information of China (English)

    郑柯; 林丽丽; 冯小明

    2012-01-01

    本工作对手性氮氧–镍络合物催化剂在不对称羰基ene反应中的应用进行了深入研究,通过对配体结构和反应条件的优化,实现了三氟甲基酮酸酯的不对称羰基ene反应.实验发现,氮氧配体的结构对反应对映选择性有很大影响,其中酰胺结构中苯环2,6-位大位阻供电取代基对于反应立体选择性控制起着至关重要的作用.该催化体系有广泛的底物普适性,对一系列α-甲基烯烃都能得到高达80%~96%的收率和97%~〉99%ee的对映选择性.同时,通过对照实验以及对催化剂单晶结构的分析,提出了可能的反应过渡态,为该系列催化剂的拓展提供了基础.%The optically active homoallylic alcohols are widespread in natural products and have been frequently used as convenient building blocks in organic synthesis.As one of the most efficient synthetic methods to obtain chiral homoallylic alcohols,the asymmetric ene reaction of carbonyl compounds has attracted significant attentions.N,N’-dioxide-amide compounds,which could be easily prepared from chiral amino acids,have been developed into a type of privileged ligand and organocatalyst in various asymmetric reactions.On the other hand,the fluoroorganic compounds are important building blocks for the total synthesis of complex natural products,pharmaceuticals,and plant pesticides due to the unique abilities of the fluorine atom to significantly modify their physicochemical and biological properties.In recent years,the interest of the pharmaceutical industry in trifluoromethyl-containing compounds has grown significantly.In this manuscript,a series of Ni(II)-N,N’-dioxide complexes have been investigated for the asymmetric carbonyl-ene reaction of ethyl trifluoropyruvate.It was found that the electronic and steric characteristics of substituents on the amide moieties of the ligand greatly affected the reaction outcomes.The catalyst L4 with bulky and electron-donating groups at the

  20. Compound list: allyl alcohol [Open TG-GATEs

    Lifescience Database Archive (English)

    Full Text Available allyl alcohol AA 00010 ftp://ftp.biosciencedbc.jp/archive/open-tggates/LATEST/Human/in_vitro/allyl_alcohol....Human.in_vitro.Liver.zip ftp://ftp.biosciencedbc.jp/archive/open-tggates/LATEST/Rat/in_vitro/allyl_alcohol...dbc.jp/archive/open-tggates/LATEST/Rat/in_vivo/Liver/Repeat/allyl_alcohol.Rat.in_vivo.Liver.Repeat.zip ftp:/.../ftp.biosciencedbc.jp/archive/open-tggates/LATEST/Rat/in_vivo/Kidney/Single/allyl_alcohol.Rat.in_vivo.Kidney....Single.zip ftp://ftp.biosciencedbc.jp/archive/open-tggates/LATEST/Rat/in_vivo/Kidney/Repeat/allyl_alcohol.Rat.in_vivo.Kidney.Repeat.zip ...

  1. Tether-directed synthesis of highly substituted oxasilacycles via an intramolecular allylation employing allylsilanes

    Directory of Open Access Journals (Sweden)

    Cox Liam R

    2007-02-01

    Full Text Available Abstract Background Using a silyl tether to unite an aldehyde electrophile and allylsilane nucleophile into a single molecule allows a subsequent Lewis-acid-mediated allylation to proceed in an intramolecular sense and therefore receive all the benefits associated with such processes. However, with the ability to cleave the tether post allylation, a product that is the result of a net intermolecular reaction can be obtained. In the present study, four diastereoisomeric β-silyloxy-α-methyl aldehydes, which contain an allylsilane tethered through the β-carbinol centre, have been prepared, in order to probe how the relative configuration of the two stereogenic centres affects the efficiency and selectivity of the intramolecular allylation. Results Syn-aldehydes, syn-4a and syn-4b, both react poorly, affording all four possible diastereoisomeric oxasilacycle products. In contrast, the anti aldehydes anti-4a and anti-4b react analogously to substrates that lack substitution at the α-site, affording only two of the four possible allylation products. Conclusion The outcome of the reaction with anti-aldehydes is in accord with reaction proceeding through a chair-like transition state (T.S.. In these systems, the sense of 1,3-stereoinduction can be rationalised by the aldehyde electrophile adopting a pseudoaxial orientation, which will minimise dipole-dipole interactions in the T.S. The 1,4-stereoinduction in these substrates is modest and seems to be modulated by the R substituent in the starting material. In the case of the syn-substrates, cyclisation through a chair T.S. is unlikely as this would require the methyl substituent α to the reacting carbonyl group to adopt an unfavourable pseudoaxial position. It is therefore proposed that these substrates react through poorly-defined T.S.s and consequently exhibit essentially no stereoselectivity.

  2. Elementary reaction allyl radical with oxygen

    Institute of Scientific and Technical Information of China (English)

    DONG Feng; KONG Fanao

    2003-01-01

    The elementary reaction between allyl radical with oxygen molecule wasexperimentally investigated. The allyl radical was produced via laser photolysis of C3H5Br in gaseous phase. Nascent vibrational excited products HCO, CO2, CH3CHO and HCOOH were recorded by the time- resolved Fourier transform infrared spectroscopy. The product channels of C2H5+CO2, CH3CHO+HCO, and HCOOH + C2H3 have been identified. The vibrational populations of product CO2 are obtained by spectral simulation. A mechanism forming a series of three-membered ring-struc- ture intermediates is suggested.

  3. Allyl/propenyl phenol synthases from the creosote bush and engineering production of specialty/commodity chemicals, eugenol/isoeugenol, in Escherichia coli.

    Science.gov (United States)

    Kim, Sung-Jin; Vassão, Daniel G; Moinuddin, Syed G A; Bedgar, Diana L; Davin, Laurence B; Lewis, Norman G

    2014-01-01

    The creosote bush (Larrea tridentata) harbors members of the monolignol acyltransferase, allylphenol synthase, and propenylphenol synthase gene families, whose products together are able to catalyze distinct regiospecific conversions of various monolignols into their corresponding allyl- and propenyl-phenols, respectively. In this study, co-expression of a monolignol acyltransferase with either substrate versatile allylphenol or propenylphenol synthases in Escherichia coli established that various monolignol substrates were efficiently converted into their corresponding allyl/propenyl phenols, as well as providing proof of concept for efficacious conversion in a bacterial platform. This capability thus potentially provides an alternate source to these important plant phytochemicals, whether for flavor/fragrance and fine chemicals, or ultimately as commodities, e.g., for renewable energy or other intermediate chemical purposes. Previous reports had indicated that specific and highly conserved amino acid residues 84 (Phe or Val) and 87 (Ile or Tyr) of two highly homologous allyl/propenyl phenol synthases (circa 96% identity) from a Clarkia species mainly dictate their distinct regiospecific catalyzed conversions to afford either allyl- or propenyl-phenols, respectively. However, several other allyl/propenyl phenol synthase homologs isolated by us have established that the two corresponding amino acid 84 and 87 residues are not, in fact, conserved.

  4. Validation of protein carbonyl measurement

    DEFF Research Database (Denmark)

    Augustyniak, Edyta; Adam, Aisha; Wojdyla, Katarzyna;

    2015-01-01

    Protein carbonyls are widely analysed as a measure of protein oxidation. Several different methods exist for their determination. A previous study had described orders of magnitude variance that existed when protein carbonyls were analysed in a single laboratory by ELISA using different commercial...

  5. Validation of protein carbonyl measurement

    DEFF Research Database (Denmark)

    Augustyniak, Edyta; Adam, Aisha; Wojdyla, Katarzyna

    2015-01-01

    Protein carbonyls are widely analysed as a measure of protein oxidation. Several different methods exist for their determination. A previous study had described orders of magnitude variance that existed when protein carbonyls were analysed in a single laboratory by ELISA using different commercial...... kits. We have further explored the potential causes of variance in carbonyl analysis in a ring study. A soluble protein fraction was prepared from rat liver and exposed to 0, 5 and 15min of UV irradiation. Lyophilised preparations were distributed to six different laboratories that routinely undertook...... protein carbonyl analysis across Europe. ELISA and Western blotting techniques detected an increase in protein carbonyl formation between 0 and 5min of UV irradiation irrespective of method used. After irradiation for 15min, less oxidation was detected by half of the laboratories than after 5min...

  6. Pressure Dependent Product Formation in the Photochemically Initiated Allyl + Allyl Reaction

    Directory of Open Access Journals (Sweden)

    Thomas Zeuch

    2013-11-01

    Full Text Available Photochemically driven reactions involving unsaturated radicals produce a thick global layer of organic haze on Titan, Saturn’s largest moon. The allyl radical self-reaction is an example for this type of chemistry and was examined at room temperature from an experimental and kinetic modelling perspective. The experiments were performed in a static reactor with a volume of 5 L under wall free conditions. The allyl radicals were produced from laser flash photolysis of three different precursors allyl bromide (C3H5Br, allyl chloride (C3H5Cl, and 1,5-hexadiene (CH2CH(CH22CHCH2 at 193 nm. Stable products were identified by their characteristic vibrational modes and quantified using FTIR spectroscopy. In addition to the (re- combination pathway C3H5+C3H5 → C6H10 we found at low pressures around 1 mbar the highest final product yields for allene and propene for the precursor C3H5Br. A kinetic analysis indicates that the end product formation is influenced by specific reaction kinetics of photochemically activated allyl radicals. Above 10 mbar the (re- combination pathway becomes dominant. These findings exemplify the specificities of reaction kinetics involving chemically activated species, which for certain conditions cannot be simply deduced from combustion kinetics or atmospheric chemistry on Earth.

  7. SYNTHESIS OF ALLYL PHENYL ETHER AND CLAISEN REARRANGEMENT

    Directory of Open Access Journals (Sweden)

    Gagik Torosyan

    2011-12-01

    Full Text Available It has been established the possibility for phenol allylation on natural zeolites and them analogs. Here is demonstrated the synthesis of allyl phenol, which has wide industrial applications. The offered method in comparison with the traditional methods has more advantages – higher selectivity, smaller material and power resources consumption. It has been obtained the mixture of allylating phenols (30% in general with allyl phenyl ether (1 with 80% yields. At 600 K is obtained allylphenyl ether, at 700 K beginning the formation of allyl phenols, which is the result of direct C-allylation of the aromatic ring. It has been investigated the possibility of Claisen rearrangement in the same conditions. All of that are established by gas-liquid chromatography and liquid chromatography data.

  8. STUDY OF CARBONYLATION OF METHANOL TO ACETIC ACID AND ACETIC ANHYDRIDE OVER A BIDENTATE POLYMER BOUND CIS-DICARBONYLRHODIUM COMPLEX AS CATALYST

    Institute of Scientific and Technical Information of China (English)

    WANG Xiaojun; LIU Zhongyang; PAN Pinglai; YUAN Guoqing

    1996-01-01

    Copolymer of 2-vinylpyridine and vinylacetate coordinated with dicarbonylrhodium used as a catalyst for carbonylation of methanol to acetic acid and anhydride has been studied. The structural characteristics of the copolymer ligand and complex, and the influences of the reaction conditions on the carbonylation catalyzed by this polymer complex have been investigated. In comparison with small molecule catalyst of Rh complex, the bidentate copolymer coordinated complex has better thermal stability. The reaction mechanism of the carbonylation reaction is also illustrated.

  9. Single Carbonyl Reduction of 1,2-cyclohexanedione Catalyzed by Recombinant Strain Heterologously Expressing Ketoreductase%异源表达酮还原酶的重组菌单羰基还原1,2-环己二酮∗

    Institute of Scientific and Technical Information of China (English)

    李尧益; 李凌凌; 吕早生; 左振宇

    2016-01-01

    Recombinant strain Escherichia coli BL21(pET-eryKR1)2, which heterologously expressed ketoreductase in the first module of polyketide synthase from Saccharopolyspora erythraea, fermented with 1,2-cyclohexanedione as reduction substrate. In that reaction, the reduced product of substrate was 2-hydroxycyclohexanone, its single carbonyl was reduced. The conditions with substrate concentration of 20 mmol/L, cell density of 80 g/L, pH of 6. 0, rotation speed of 120 r/min and reaction temperature of 37 ℃ were optimal for this biocatalytic conversion with the addition of 10 g/L of coenzyme regeneration system E. coli BL21 ( pET-gdh1 ) and 0. 2 mmol/L of NADPH. The conversion rate of 1 ,2-cyclohexanedione catalyzed by the recombinant cells for 10 h could reach 84. 2% under these conditions.%利用表达糖多孢红霉菌聚酮合成酶模块1的酮还原酶的重组大肠杆菌细胞Escherichia coli BL21( pET-eryKR1)2对1,2-环己二酮进行了催化还原反应,该还原反应为单羰基还原而非双羰基还原,生成的产物为2-羟基环己酮。对重组细胞催化1,2-环己二酮还原的反应条件进行了优化,发现最优的反应条件为底物浓度20 mmol/L,细胞密度80 g/L, pH 6.0,转速120 r/min,温度37℃,且需要添加10 g/L E. coli BL21(pET-gdh1)辅酶再生系统和0.2 mmol/L NADPH。在该反应条件下,重组菌催化反应10 h后,底物的转化率可高达84.2%。

  10. 49 CFR 173.198 - Nickel carbonyl.

    Science.gov (United States)

    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...

  11. Highly Efficient and Versatile Acetalization of Glycol Catalyzed by Cupric p-Toluenesulfonate

    Institute of Scientific and Technical Information of China (English)

    LIU,Cai-Hua; YU,Xin-Yu; LIANG,Xue-Zheng; WANG,Wen-Juan; YANG,Jian-Guo; HE,Ming-Yuan

    2007-01-01

    Acetalization of glycol with carbonyl compounds was carried out catalyzed by cupric p-toluenesulfonate. These carbonyl compounds included cyclohexanone, propionoaldehyde, n-butyraldehyde, iso-butyraldehyde, n-valeraldehyde, benzaldehyde and butanone. Satisfactory results were obtained: the conversions of these carbonyl compounds were more than 90%, the selectivities were higher than 99.1%, only 0.1% mole ratio of catalyst to substrate and 90 min were sufficient in most cases. The catalyst and products were separated easily by phase separation.

  12. Synthesis of heterocycles through transition-metal-catalyzed isomerization reactions.

    Science.gov (United States)

    Ishoey, Mette; Nielsen, Thomas E

    2014-07-14

    Metal-catalyzed isomerization of N- and O-allylic systems is emerging as an effective method to form synthetically useful iminium and oxocarbenium intermediates. In the presence of tethered nucleophiles, several recent examples illuminate this approach as a powerful strategy for the synthesis of structurally complex and diverse heterocycles. In this Concept article, we attempt to cover this area of research through a selection of recent versatile examples.

  13. Regio- and Diasteroselectivity of Rhodium-catalyzed Ring Opening Reaction of Oxabenzonorbornadienes with Heteroatom Nucleophiles

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A new rhodium catalyzed ring opening reaction of oxabenzonorbornadienes and its derivatives was described. This reaction forms a new carbon-nitrogen bond via an intermolecular allylic displacement of the bridgehead oxygen with a piperazine's derivatives, which proceeds with very high regioselectivity.

  14. Direct Vapor Phase Carbonylation of Methanol over NiCl2/C Catalyst

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@ Introduction The carbonylation of alcohols via homogenous catalysis is important in manufacturing acetic acid and higher carboxylic acids and their esters[1,2]. The main route to produce acetic acid is to make methanol carbonylated by means of the Monsanto and BP process in which a homogeneous rhodium catalyst is used. Although the homogeneous carbonylation of methanol is a highly selective process, it is affected by the disadvantages associated with a highly corrosive reaction medium due to the use of methyl iodide as the promoter, and the difficulty of the product separation[3]. The use of a heterogeneous catalyst seems very interesting and attractive to us[4], especially the direct vapor phase carbonylation of methanol without a halide promoter is of considerable importance and is strong incentive economically. There has, however, been very little success in finding either heterogeneous or homogeneous catalysts that can catalyze the reaction effectively without the addition of a promoter[5,6]. According to the known carbonylation mechanism[7,8], the methyl iodide directly carbonylates with CO to from MeCOI which interacts with methanol(MeOH) to produce methyl acetate(MeCOOMe) and HI, and then MeOH reacts with HI to from CH3I. In fact, this carbonylation reaction is the indirect catalytic carbonylation of methanol[9]. In this work, a novel catalyst for the direct vapor phase carbonylation of methanol without the addition of any halide in the feed as a promoter was investigated. Compared to the known liquid phase methanol carbonylation process, some advantages of this vapor phase reaction are as follows:

  15. Amination of allylic alcohols in water at room temperature.

    Science.gov (United States)

    Nishikata, Takashi; Lipshutz, Bruce H

    2009-06-04

    The "trick" to carrying out regiocontrolled aminations of allylic alcohols in water as the only medium is use of a nanomicelle's interior as the organic reaction solvent. When HCO(2)Me is present, along with the proper base and source of catalytic Pd, allylic amines are cleanly formed at room temperature.

  16. Allyl borates: a novel class of polyhomologation initiators

    KAUST Repository

    Wang, De

    2016-12-24

    Allyl borates, a new class of monofunctional polyhomologation initiators, are reported. These monofunctional initiators are less sensitive and more effective towards polymethylene-based architectures. As an example, the synthesis of α-vinyl-ω-hydroxypolymethylenes is given. By designing/synthesizing different allylic borate initiators, and using 1H and 11B NMR spectroscopy, the initiation mechanism was elucidated.

  17. Radiation and thermal polymerization of allyl(p-allylcarbonate) benzoate

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-V, D., E-mail: dlopez@siu.buap.m [Facultad de Ciencias Quimicas, Benemerita Universidad Autonoma de Puebla, Antiguo Edificio de la Fac. de Cs., Quimica. Av. San Claudio y Boulevard de la 14 sur, Col. San Manuel, Puebla, Pue., CP 72500 (Mexico); Herrera-G, A.M., E-mail: mherrera@uaeh.reduaeh.m [Centro de Inv. en Materiales y Metalurgia, UAEH. Km 4.5, C.U., CP 42184, Pachuca de S. Hidalgo (Mexico); Castillo-Rojas, S., E-mail: castillo@nucleares.unam.m [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, 04510 DF (Mexico)

    2011-03-15

    Bulk polymerization of novel allyl(p-allylcarbonate) benzoate was investigated using different sources of energy, such as gamma rays, ultraviolet rays as well as thermal polymerization. The poly(allyl(p-allylcarbonate) benzoate) obtained is a cross-linking, transparent, thermoset polycarbonate. Compositions of the monomer and the polycarbonate were analyzed by infrared spectroscopy, elemental analysis, and {sup 1}H NMR spectroscopy.

  18. Catalytic enantioselective 1,6-conjugate additions of propargyl and allyl groups

    Science.gov (United States)

    Meng, Fanke; Li, Xiben; Torker, Sebastian; Shi, Ying; Shen, Xiao; Hoveyda, Amir H.

    2016-09-01

    Conjugate (or 1,4-) additions of carbanionic species to α,β-unsaturated carbonyl compounds are vital to research in organic and medicinal chemistry, and there are several chiral catalysts that facilitate the catalytic enantioselective additions of nucleophiles to enoates. Nonetheless, catalytic enantioselective 1,6-conjugate additions are uncommon, and ones that incorporate readily functionalizable moieties, such as propargyl or allyl groups, into acyclic α,β,γ,δ-doubly unsaturated acceptors are unknown. Chemical transformations that could generate a new bond at the C6 position of a dienoate are particularly desirable because the resulting products could then be subjected to further modifications. However, such reactions, especially when dienoates contain two equally substituted olefins, are scarce and are confined to reactions promoted by a phosphine-copper catalyst (with an alkyl Grignard reagent, dialkylzinc or trialkylaluminium compounds), a diene-iridium catalyst (with arylboroxines), or a bisphosphine-cobalt catalyst (with monosilyl-acetylenes). 1,6-Conjugate additions are otherwise limited to substrates where there is full substitution at the C4 position. It is unclear why certain catalysts favour bond formation at C6, and—although there are a small number of catalytic enantioselective conjugate allyl additions—related 1,6-additions and processes involving a propargyl unit are non-existent. Here we show that an easily accessible organocopper catalyst can promote 1,6-conjugate additions of propargyl and 2-boryl-substituted allyl groups to acyclic dienoates with high selectivity. A commercially available allenyl-boron compound or a monosubstituted allene may be used. Products can be obtained in up to 83 per cent yield, >98:2 diastereomeric ratio (for allyl additions) and 99:1 enantiomeric ratio. We elucidate the mechanistic details, including the origins of high site selectivity (1,6- versus 1,4-) and enantioselectivity as a function of the catalyst

  19. Divergent synthetic routes for ring expansion or cyclization from 1,4-allylic diol derivatives via gold(I) catalysis or zinc(II) mediation.

    Science.gov (United States)

    Zhu, Li-Li; Li, Xiao-Xiao; Zhou, Wen; Li, Xin; Chen, Zili

    2011-11-04

    A new efficient method was developed to transform cyclic alkanols into one-carbon higher homologated ketones using various esters as the leaving groups through gold-catalyzed allylic cation-promoted pinacol-type rearrangement. This reaction, coupled with oxy-Cope rearrangement, provided a new strategy to synthesize five-carbon homologated ring ketones. In addition, using ZnBr(2), 2,5-dihydrofuran products were obtained in moderate to good yields via an intramolecular cyclization process.

  20. A green and efficient deoximation using H2O2 catalyzed by montmorillonite-K10 supported COCl2

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Oximes were oxidized to the corresponding carbonyl compounds in good to high yields by environmentally friendly and green oxidant, H2O2 catalyzed by montmorillonite K310 supported cobalt(Ⅱ) chloride.

  1. 对甲苯磺酸盐作为两相催化剂催化邻苯二酚与羰基化合物的缩合%Ketalization of Catechol with Carbonyl Compounds Catalyzed by Metal p-Toluenesulfonate as Biphasic Acid Catalyst

    Institute of Scientific and Technical Information of China (English)

    梁学正; 高珊; 王雯娟; 程文萍; 杨建国

    2008-01-01

    Ketalization of catechol was studied with various carbonyl compounds using metal p-toluenesulfonate as biphasic catalysts. The results showed that copper p-toluenesulfonate was the most efficient catalysts for the re-action. The advantages of high activity, stability, reusability and low cost for the simple synthetic procedure made the catalyst one of the best choice for the reaction.

  2. Ab initio MO study of reaction mechanism for carbonyl migration of Co complex

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Ab initio method under the effective core potential (ECP) approximation is employed to study the reaction mechanism of carbonyl migration of the cycle of olefin hydroformylation catalyzed by a carbonyl cobalt HCo(CO)3 at Hartree-Fock (HF) level. The structures of the reactant, transition state and product for the reaction are determined. The energy of each stationary point is corrected at MP2/LAN2DZ//LANL2DZ+ZPE (zero-point energy) level. The calculated activation barrier is 28.89 kJ/mol.

  3. An Efficient Amide-Aldehyde-Alkene Condensation: Synthesis for the N-Allyl Amides.

    Science.gov (United States)

    Quan, Zheng-Jun; Wang, Xi-Cun

    2016-02-01

    The allylamine skeleton represents a significant class of biologically active nitrogen compounds that are found in various natural products and drugs with well-recognized pharmacological properties. In this personal account, we will briefly discuss the synthesis of allylamine skeletons. We will focus on showing a general protocol for Lewis acid-catalyzed N-allylation of electron-poor N-heterocyclic amides and sulfonamide via an amide-aldehyde-alkene condensation reaction. The substrate scope with respect to N-heterocyclic amides, aldehydes, and alkenes will be discussed. This method is also capable of preparing the Naftifine motif from N-methyl-1-naphthamide or methyl (naphthalene-1-ylmethyl)carbamate, with paraformaldehyde and styrene in a one-pot manner.

  4. Zinc Mediated Tandem Fragmentation-Allylation of Methyl 5-Iodopentofuranosides

    DEFF Research Database (Denmark)

    Hyldtoft, Lene; Madsen, Robert

    1999-01-01

    In the presence of zinc and allyl bromide methyl 5-iodopentofuranosides undergo a tandem fragmentation alkylation to give functionalized dienes. These can undergo ring-closing olefin metathesis to produce cyclohexenes which on dihydroxylation give quercitols....

  5. Chiral allylic and allenic metal reagents for organic synthesis.

    Science.gov (United States)

    Marshall, James A

    2007-10-26

    This account traces the evolution of our work on the synthesis of chiral allylic and allenic organometal compounds of tin, silicon, zinc, and indium and their application to natural product synthesis over the past quarter century.

  6. Molecular Mechanics and Quantum Chemistry Based Study of Nickel-N-Allyl Urea and N-Allyl Thiourea Complexes

    Directory of Open Access Journals (Sweden)

    P. D. Sharma

    2009-01-01

    Full Text Available Eigenvalue, eigenvector and overlap matrix of nickel halide complex of N-allyl urea and N-allyl thiourea have been evaluated. Our results indicate that ligand field parameters (Dq, B’ and β evaluated earlier by electronic spectra are very close to values evaluated with the help of eigenvalues and eigenvectors. Eigenvector analysis and population analysis shows that in bonding 4s, 4p, and 3dx2-y2, 3dyz orbitals of nickel are involved but the coefficient values differ in different complexes. Out of 4px, 4py, 4pz the involvement of either 4pz or 4py, is noticeable. The theoretically evaluated positions of infrared bands indicate that N-allyl urea is coordinated to nickel through its oxygen and N-allyl thiourea is coordinated to nickel through its sulphur which is in conformity with the experimental results.

  7. Unusual Reaction of β-Hydroxy α-Diazo Carbonyl Compounds with Trichloroacetonitrile (CI3CCN) and Sodium Hydride

    Institute of Scientific and Technical Information of China (English)

    SHI Wei-Feng; JIANG Nan; WANG Jian-Bo

    2003-01-01

    @@ In the process of preparing α-diazo carbonyl compound 2 by imidation of 1, we unexpectedly observed a direct conversion of the hydroxyl group into trichloroacetylamino group. In this presentation, we report this unprecedented reaction, as well as the Rh2(OAc)4-catalyzed reaction of the resulting β-(trichloroacetyl)amino β-diazo carbonylcompounds 3. [ 1

  8. Structurally defined allyl compounds of main group metals: coordination and reactivity.

    Science.gov (United States)

    Lichtenberg, Crispin; Okuda, Jun

    2013-05-10

    Organometallic allyl compounds are important as allylation reagents in organic synthesis, as polymerization catalysts, and as volatile metal precursors in material science. Whereas the allyl chemistry of synthetically relevant transition metals such as palladium and of the lanthanoids is well-established, that of main group metals has been lagging behind. Recent progress on allyl complexes of Groups 1, 2, and 12-16 now provides a more complete picture. This is based on a fundamental understanding of metal-allyl bonding interactions in solution and in the solid state. Furthermore, reactivity trends have been rationalized and new types of allyl-specific reactivity patterns have been uncovered. Key features include 1) the exploitation of the different types of metal-allyl bonding (highly ionic to predominantly covalent), 2) the use of synergistic effects in heterobimetallic compounds, and 3) the adjustment of Lewis acidity by variation of the charge of allyl compounds.

  9. Scalable and sustainable electrochemical allylic C-H oxidation

    Science.gov (United States)

    Horn, Evan J.; Rosen, Brandon R.; Chen, Yong; Tang, Jiaze; Chen, Ke; Eastgate, Martin D.; Baran, Phil S.

    2016-05-01

    New methods and strategies for the direct functionalization of C-H bonds are beginning to reshape the field of retrosynthetic analysis, affecting the synthesis of natural products, medicines and materials. The oxidation of allylic systems has played a prominent role in this context as possibly the most widely applied C-H functionalization, owing to the utility of enones and allylic alcohols as versatile intermediates, and their prevalence in natural and unnatural materials. Allylic oxidations have featured in hundreds of syntheses, including some natural product syntheses regarded as “classics”. Despite many attempts to improve the efficiency and practicality of this transformation, the majority of conditions still use highly toxic reagents (based around toxic elements such as chromium or selenium) or expensive catalysts (such as palladium or rhodium). These requirements are problematic in industrial settings; currently, no scalable and sustainable solution to allylic oxidation exists. This oxidation strategy is therefore rarely used for large-scale synthetic applications, limiting the adoption of this retrosynthetic strategy by industrial scientists. Here we describe an electrochemical C-H oxidation strategy that exhibits broad substrate scope, operational simplicity and high chemoselectivity. It uses inexpensive and readily available materials, and represents a scalable allylic C-H oxidation (demonstrated on 100 grams), enabling the adoption of this C-H oxidation strategy in large-scale industrial settings without substantial environmental impact.

  10. Study of decomposing carbonyl slag

    Institute of Scientific and Technical Information of China (English)

    CHEN Ai-liang; SUN Pei-mei; ZHAO Zhong-wei; LI Hong-gui; CHEN Xing-yu

    2006-01-01

    A new technology was put forward to deal with the carbonyl slag at low acidity and low oxygen pressure in the kettle.With the orthogonal experiments for analyzing the sequence of four factors and some single factor experiments for the best conditions. The best conditions are used for extracting nickel, cobalt and copper and enriching precious metals: the cupric ion concentration is 5 g/L; and pH=6; the sulfur coefficient is 1.4; the oxygen pressure is 0.08 MPa; the time bubbling oxygen is 20 min;the ratio of liquid to solid is 8:1; the leaching time is 2 h; the heating time is 2.5 h. The leaching rates of nickel and cobalt are more than 98% and that of copper is above 97%. Nickel and cobalt can be separated efficiently from copper and precious metals from the carbonyl slag. Moreover, its leaching liquor has less copper. Nickel and cobalt can be reclaimed only once. During the whole process,the leaching rates of Au and Ag are more than 99.9%, while other precious metals are still in the residue without any loss.

  11. A green and efficient oxidation of benzylic alcohols using H2O2 catalyzed by Montmorillonite-K10 supported MnCl2

    Institute of Scientific and Technical Information of China (English)

    Cholam Reza Najafi

    2010-01-01

    Primary and secondary benzylic alcohols were oxidized to the corresponding carbonyl compounds in good to high yields by environmentally friendly and green oxidant, H2O2 catalyzed by Montmorillonite-K10 supported manganese(Ⅱ) chloride.

  12. Non-Directed Allylic C-H Acetoxylation in the Presence of Lewis Basic Heterocycles.

    Science.gov (United States)

    Malik, Hasnain A; Taylor, Buck L H; Kerrigan, John R; Grob, Jonathan E; Houk, K N; Du Bois, J; Hamann, Lawrence G; Patterson, Andrew W

    2014-06-01

    We outline a strategy to enable non-directed Pd(II)-catalyzed C-H functionalization in the presence of Lewis basic heterocycles. In a high-throughput screen of two Pd-catalyzed C-H acetoxylation reactions, addition of a variety of N-containing heterocycles is found to cause low product conversion. A pyridine-containing test substrate is selected as representative of heterocyclic scaffolds that are hypothesized to cause catalyst arrest. We pursue two approaches in parallel that allow product conversion in this representative system: Lewis acids are found to be effective in situ blocking groups for the Lewis basic site, and a pre-formed pyridine N-oxide is shown to enable high yield of allylic C-H acetoxylation. Computational studies with density functional theory (M06) of binding affinities of selected heterocycles to Pd(OAc)2 provide an inverse correlation of the computed heterocycle-Pd(OAc)2 binding affinities with the experimental conversions to products. Additionally, (1)H NMR binding studies provide experimental support for theoretical calculations.

  13. Catalytic Enantioselective Allylic Amination of Olefins for the Synthesis of ent-Sitagliptin.

    Science.gov (United States)

    Bao, Hongli; Bayeh, Liela; Tambar, Uttam K

    2013-11-01

    The presence of nitrogen atoms in most chiral pharmaceutical drugs has motivated the development of numerous strategies for the synthesis of enantioenriched amines. Current methods are based on the multi-step transformation of pre-functionalized allylic electrophiles into chiral allylic amines. The enantioselective allylic amination of unactivated olefins represents a more direct and attractive strategy. We report the enantioselective synthesis of ent-sitagliptin via an allylic amination of an unactivated terminal olefin.

  14. Impact of Substituents Attached to N-Heterocyclic Carbenes on the Catalytic Activity of Copper Complexes in the Reduction of Carbonyl Compounds with Triethoxysilane

    Institute of Scientific and Technical Information of China (English)

    PENG, Jiajian; CHEN, Lingzhen; XU, Zheng; HU, Yingqian; LI, Jiayun; BAI, Ying; QIU, Huayu; LAI, Guoqiao

    2009-01-01

    By using functionalized imidazolium salts such as 1-allyl-3-alkylimidazolium or 1-alkyi-3-vinylimidazolium salts as carbene ligand precursors, the reduction of aryl ketones with triethoxysilane may be catalyzed by copper salt/imidazolium salt/KO~tBu systems. The functional substituents attached to the N-heterocyclic carbene (NHC) serve to enhance the catalytic activity. Different copper salts also have an effect on the catalytic activity, with copper(Ⅱ) acetate monohydrate being superior to copper(I) chloride.

  15. A convenient procedure for the synthesis of allyl and benzyl ethers from alcohols and phenols

    Indian Academy of Sciences (India)

    H Surya Prakash Rao; S P Senthilkumar

    2001-06-01

    Allyl and benzyl ethers of alcohols can be prepared conveniently and in high yield with allyl and benzyl bromide in the presence of solid potassium hydroxide without use of any solvent. Phenols can be converted to allyl ethers but are inert to benzylation under above conditions.

  16. 40 CFR 721.7000 - Polymer of disodium maleate, allyl ether, and ethylene oxide.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Polymer of disodium maleate, allyl... New Uses for Specific Chemical Substances § 721.7000 Polymer of disodium maleate, allyl ether, and... substance identified generically as a polymer of disodium maleate, allyl ether, and ethylene oxide...

  17. PHOTOINDUCED GRAFTING OF ACRYLIC AND ALLYL MONOMERS ON POLYETHYLENE SURFACE

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhenfeng; HU Xingzhou; YAN Qing

    1995-01-01

    Photoinduced grafting of acrylic and allyl monomers on polyethylene surface was generally studied by using benzophenone (BP) as a photoinitiator. The grafting process was carried out either in vapor-phase or in solution of the monomers. In the vapor-phase reaction with a filter used to cut off the short wavelength UV light, allyl amine is the most reactive of the four monomers used and acrylic amide is comparatively more reactive than acrylic acid and allyl alcohol. Acetone, as a solvent and carrier for initiator and monomers, however, shows its reactivity to participate the reaction. The solution grafting with a filter is much faster than the corresponding vapor-phase reaction, and a fully covered surface by the grafted polymer can be achieved in this way.

  18. Ab initio study on the mechanism of rhodium-complexcatalyzed carbonylation of methanol to acetic acid

    Institute of Scientific and Technical Information of China (English)

    LEI; Ming

    2001-01-01

    [1]Thomas, R., Cundari, T. R., Computational studies of transition metal-main group multiple bonding, Chem. Rev., 2000,100: 807.[2]Maricel Torrent, Miquel Sola, Gernot Frenking, Theoretical studies of some transition-metal-mediated reactions of industrial and synthetic importance, Chem. Rev., 2000, 100: 439.[3]Paulik, F. E., Roth, J. F., Catalysts for the low-pressure carbonylation of menthanol to acetic acid, Chem. Commun., 1968,24: 1578.[4]Jiang Hua, Diao Kaisheng, Pan Pinglai et al., A new class of rhodium complexes containing free donor atoms and their intramolecular substitution reaction, Chin. J. Chem., 2000, 18: 752.[5]Jiang Dazhi, Li Xiaobao, Wang Enlai, Synthesis Chemistry ofCarbonylation, Beijing: Chemical Technology Press, 1996.[6]Adamson, G. W., Daly, J. J., Forster, D., Reduction of iolocarbonyl rhodium ions with methyl iodide, structure of the rho-dium acetyl complex: [Me3PhN+], [Rh2I6-(Me(O)2(CO)2)]2-, J. Organomet. Chem., 1974, 71: C 17.[7]Forster, D., On the mechanism of a rhodium-complex-catalyzed carbonylation of methanol to acetic acid, J. Am. Chem.Soc., 1976, 98: 846.[8]Hjortkjaer, J., Jensen, O. R., Rhodium complexes catalyzed methanol carbonylation, Ind. Eng. Chem. Prod. Dev., 1976, 15:46.[9]Jeffrey, P., Wadt, W. R., Ab initio effective core potentials for molecular calculations, Potentials for the transition metalatoms Sc to Hg, J. Chem. Phys., 1995, 82: 270.[10]Frisch, M. J., Trunks, G. W., Schlegel, H. B. et al., Gaussian 94, Pittsburgh PA: Gaussian, Inc., 1995.[11]Lei Ming, Feng Wenlin, Xu Zhenfeng et al., A theoretical study on the key reactions of hydroformylation cycle by modi-fied carbonyl cobalt, Chemical Journal of Chinese University, 2001, 22: 455.[12]Lei Ming, Feng Wenlin, Xu Zhenfeng, Ab initio MO study on the reaction mechanism for carbonyl insertion catalyzed by the carbonyl cobalt complex, Chemical Research in Chinese University, 2000, 19:31.

  19. Glutathione Adduct Patterns of Michael-Acceptor Carbonyls.

    Science.gov (United States)

    Slawik, Christian; Rickmeyer, Christiane; Brehm, Martin; Böhme, Alexander; Schüürmann, Gerrit

    2017-02-22

    Glutathione (GSH) has so far been considered to facilitate detoxification of soft organic electrophiles through covalent binding at its cysteine (Cys) thiol group, followed by stepwise catalyzed degradation and eventual elimination along the mercapturic acid pathway. Here we show that in contrast to expectation from HSAB theory, Michael-acceptor ketones, aldehydes and esters may form also single, double and triple adducts with GSH involving β-carbon attack at the much harder N-terminus of the γ-glutamyl (Glu) unit of GSH. In particular, formation of the GSH-N single adduct contradicts the traditional view that S alkylation always forms the initial reaction of GSH with Michael-acceptor carbonyls. To this end, chemoassay analyses of the adduct formation of GSH with nine α,β-unsaturated carbonyls employing high performance liquid chromatography and tandem mass spectrometry have been performed. Besides enriching the GSH adductome and potential biomarker applications, electrophilic N-terminus functio-nalization is likely to impair GSH homeostasis substantially through blocking the γ-glutamyl transferase catalysis of the first breakdown step of modified GSH, and thus its timely reconstitution. The discussion includes a comparison with cyclic adducts of GSH and furan metabolites as reported in literature, and quantum chemically calculated thermodynamics of hard-hard, hard-soft and soft-soft adducts.

  20. Palladium-catalyzed 1,4-difunctionalization of butadiene to form skipped polyenes.

    Science.gov (United States)

    McCammant, Matthew S; Liao, Longyan; Sigman, Matthew S

    2013-03-20

    A palladium-catalyzed 1,4-addition across the commodity chemical 1,3-butadiene to afford skipped polyene products is reported. Through a palladium σ → π → σ allyl isomerization, two new carbon-carbon bonds are formed with high regioselectivity and trans stereoselectivity of the newly formed alkene. The utility of this method is highlighted by the successful synthesis of the ripostatin A skipped triene core.

  1. Surface decorated platinum carbonyl clusters

    Science.gov (United States)

    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

  2. Copper(I) catalyzed asymmetric 1,2-addition of Grignard reagents to α-methyl substituted α,β-unsaturated ketones

    NARCIS (Netherlands)

    Madduri, Ashoka V.R.; Minnaard, Adriaan J.; Harutyunyan, Syuzanna R.

    2012-01-01

    The first catalytic enantioselective 1,2-addition of Grignard reagents to ketones is presented. This additive-free copper(I) catalyzed 1,2-addition provides chiral allylic tertiary alcohols with an er of up to 98 : 2 and excellent yields due to the complete shift of overwhelming 1,4-selectivity of c

  3. 1-Ethyl-3-methylimidazolium acetate as a highly efficient organocatalyst for cyanosilylation of carbonyl compounds with trimethylsilyl cyanide

    Science.gov (United States)

    Ullah, Bakhtar; Chen, Jingwen; Zhang, Zhiguo; Xing, Huabin; Yang, Qiwei; Bao, Zongbi; Ren, Qilong

    2017-01-01

    1-Ethyl-3-methylimidazolium acetate is introduced as a robust organocatalyst for solvent-free cyanosilylation of carbonyl compounds with trimethylsilyl cyanide (TMSCN). The catalyst loading can be reduced to as low as 0.1–0.0001 mol % under mild reaction conditions, giving considerably high TOF values from 10,843 h−1 to 10,602,410 h−1 in the field of organocatalyzed transformations. The present protocol not only tolerates with extensive carbonyl compounds but also provides somewhat insight into the mechanism of ionic liquids (ILs)-catalyzed reactions. PMID:28198462

  4. Sulfonium-based Ionic Liquids Incorporating the Allyl Functionality

    Directory of Open Access Journals (Sweden)

    Paul J. Dyson

    2007-04-01

    Full Text Available A series of sulfonium halides bearing allyl groups have been prepared andcharacterized. Anion metathesis with Li[Tf2N] and Ag[N(CN2] resulted in sulfonium-basedionic liquids which exhibit low viscosities at room temperature. The solid state structure ofone of the halide salts was determined by single crystal X-ray diffraction.

  5. Single pulse shock tube study of allyl radical recombination.

    Science.gov (United States)

    Fridlyand, Aleksandr; Lynch, Patrick T; Tranter, Robert S; Brezinsky, Kenneth

    2013-06-13

    The recombination and disproportionation of allyl radicals has been studied in a single pulse shock tube with gas chromatographic measurements at 1-10 bar, 650-1300 K, and 1.4-2 ms reaction times. 1,5-Hexadiene and allyl iodide were used as precursors. Simulation of the results using derived rate expressions from a complementary diaphragmless shock tube/laser schlieren densitometry study provided excellent agreement with precursor consumption and formation of all major stable intermediates. No significant pressure dependence was observed at the present conditions. It was found that under the conditions of these experiments, reactions of allyl radicals in the cooling wave had to be accounted for to accurately simulate the experimental results, and this unusual situation is discussed. In the allyl iodide experiments, higher amounts of allene, propene, and benzene were found at lower temperatures than expected. Possible mechanisms are discussed and suggest that iodine containing species are responsible for the low temperature formation of allene, propene, and benzene.

  6. Electrochemical Allylic Oxidation of Olefins: Sustainable and Safe.

    Science.gov (United States)

    Waldvogel, Siegfried R; Selt, Maximilian

    2016-10-01

    The power you're supplying: With the application of an optimized electrochemical approach, the allylic oxidation of olefins, which is an important C-H activation process that provides access to enones, becomes a sustainable, versatile, and potent key reaction for organic synthesis.

  7. 1-Allyl-5-chloroindoline-2,3-dione

    Directory of Open Access Journals (Sweden)

    Zineb Tribak

    2016-06-01

    Full Text Available In the title compound, C11H8ClNO2, the allyl side chain is almost perpendicular to the 5-chloroindoline-2,3-dione ring system, with a dihedral angle of 88.0 (3°. In the crystal, C—H...O interactions link the molecules into layers lying parallel to the bc plane.

  8. Gold-catalyzed oxidative cycloadditions to activate a quinoline framework.

    Science.gov (United States)

    Huple, Deepak B; Ghorpade, Satish; Liu, Rai-Shung

    2013-09-23

    Going for gold! Gold-catalyzed reactions of 3,5- and 3,6-dienynes with 8-alkylquinoline oxides results in an oxidative cycloaddition with high stereospecificity (see scheme; EWG = electron-withdrawing group); this process involves a catalytic activation of a quinoline framework. The reaction mechanism involves the intermediacy of α-carbonyl pyridinium ylides (I) in a concerted [3+2]-cycloaddition with a tethered alkene.

  9. Highly efficient and eco-friendly gold-catalyzed synthesis of homoallylic ketones

    KAUST Repository

    Gómez-Suárez, Adrián

    2014-08-01

    We report a new catalytic protocol for the synthesis of γ,δ-unsaturated carbonyl units from simple starting materials, allylic alcohols and alkynes, via a hydroxalkoxylation/Claisen rearrangement sequence. This new process is more efficient (higher TON and TOF) and more eco-friendly (increased mass efficiency) than the previous state-of-the-art technique. In addition, this method tolerates both terminal and internal alkynes. Moreover, computational studies have been carried out in order to shed light on how the Claisen rearrangement is initiated. © 2014 American Chemical Society.

  10. Trifluoromethylation of Carbonyl Compounds with Sodium Trifluoroacetate

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    In the presence of copper (Ⅰ) halide as catalyst, a variety of carbonyl compounds could be trifluoromethylated with sodium trifluoroacetate to give the corresponding alcohols in moderate to high yields.

  11. The carbonylation of phenyl bromide and its derivatives under visible light irradiation

    Institute of Scientific and Technical Information of China (English)

    Wen Hui Zhong; Ying Na Cui; Shen Min Li; Ying Ping Jia; Jing Mei Yin

    2012-01-01

    The carbonylation of phenyl bromide catalyzed by Co(OAc)2 has been investigated with PhCOPh as a sensitizer under visible light in the presence of basic additive.With strong base CH3ONa,PhCOOCH3 is produced in 70% yield with 100% selectivity,the similar results are also obtained with a stronger base (CH3)3CONa.However,with another strong base NaOH,the yield of the ester is only 40%.On the other hand,with weak base NaOAc or (n-C4Hg)3N,phenyl bromide cannot be carbonylated.The results of carbonylation of the six substituted phenyl bromides suggest that the activities of o,m,p-BrC6H4CH3 are similar to phenyl bromide,while the activities of o,m,p-BrC6H4Cl are higher with the high yields (≥93%) of the corresponding chloro-esters.In addition,the relative position of bromine and chlorine or methyl on phenyl ring has little effect on the activity of the carbonylation.

  12. Palladium complexes with a tridentate PNO ligand. Synthesis of eta1-allyl complexes and cross-coupling reactions promoted by boron compounds.

    Science.gov (United States)

    Crociani, Bruno; Antonaroli, Simonetta; Burattini, Marcello; Paoli, Paola; Rossi, Patrizia

    2010-04-21

    The iminophosphine 2-(2-Ph(2)P)C(6)H(4)N=CHC(6)H(4)OH (P-N-OH) reacts with [Pd(mu-Cl)(eta(3)-C(3)H(5))](2) yielding [PdCl(P-N-O)] and propene. In the presence of NEt(3), the reaction of P-N-OH with [Pd(mu-Cl)(eta(3)-1-R(1),3-R(2)C(3)H(3))](2) (R(1) = R(2) = H, Ph; R(1) = H, R(2) = Ph) affords the eta(1)-allyl derivatives [Pd(eta(1)-1-R(1),3-R(2)C(3)H(3))](P-N-O)] (R(1) = R(2) = H: 1; R(1) = H, R(2) = Ph: 2; R(1) = R(2) = Ph: 3). In solution, the complexes 1 and 3 undergo a slow dynamic process which interconverts the bonding site of the allyl ligand. The X-ray structural analysis of 1 indicates a square-planar coordination geometry around the palladium centre with a P,N,O,-tridentate ligand and a sigma bonded allyl group. The complexes [PdR(P-N-O)] (R = C(6)H(4)Me-4, C[triple bond]CPh) react slowly with p-bromoanisole in the presence of p-tolylboronic acid to give [PdBr(P-N-O)] and the coupling product RC(6)H(4)OMe-4. The latter reactions also proceed at a low rate under catalytic conditions. The coupling of allyl bromide with p-tolylboronic acid is catalyzed by [PdCl(P-N-O)]/K(2)CO(3) to give 4-allyltoluene.

  13. ION EXCHANGE SUBSTANCES BY SAPONIFICATION OF ALLYL PHOSPHATE POLYMERS

    Science.gov (United States)

    Kennedy, J.

    1959-04-14

    An ion exchange resin having a relatively high adsorption capacity tor uranyl ion as compared with many common cations is reported. The resin comprises an alphyl-allyl hydrogen phosphate polymer, the alphyl group being either allyl or a lower alkyl group having up to 5 carbon atoins. The resin is prepared by polymerizing compounds such as alkyl-diallyl phosphate and triallyl phosphate in the presence of a free radical generating substance and then partially hydrolyzing the resulting polymer to cause partial replacement of organic radicals by cations. A preferred free radical gencrating agent is dibenzoyl peroxide. The partial hydrolysis is brought about by refluxing the polymer with concentrated aqueous NaOH for three or four hours.

  14. Radiation initiated copolymerization of allyl alcohol with acrylonitrile

    Energy Technology Data Exchange (ETDEWEB)

    Solpan, Dilek; Guven, Olgun [Hacettepe Univ., Ankara (Turkey). Dept. of Chemistry

    1996-07-01

    Copolymerization of allyl alcohol (AA) with acrylonitrile (AN) initiated by {gamma}-rays has been investigated to determine the respective reactivity ratios. Three different experimental techniques, namely Fourier Transform Infrared (FTIR), Ultraviolet (UV/vis) and elemental analysis (EA) have been used for the determination of copolymer compositions. Fineman-Ross (FR), Kelen-Tudos (KT), Non-Linear Least Square (NLLS) Analysis and Q-e methods have been applied to the three sets of experimental data. It has been concluded that data obtained from elemental analysis as applied to the Non-Linear Least Square approach gave the most reliable reactivity ratios as 2.09 and 0.40 for acrylonitrile and allyl alcohol, respectively. (Author).

  15. Radiation initiated copolymerization of allyl alcohol with acrylonitrile

    Science.gov (United States)

    Şolpan, Dilek; Güven, Olgun

    1996-07-01

    Copolymerization of allyl alcohol (AA) with acrylonitrile (AN) initiated by γ-rays has been investigated to determine the respective reactivity ratios. Three different experimental techniques, namely Fourier Transform Infrared (FTIR), Ultraviolet (UV/vis) and elemental analysis (EA) have been used for the determination of copolymer compositions. Fineman-Ross (FR), Kelen-Tüdös (KT), Non-Linear Least Square (NLLS) Analysis and Q-e methods have been applied to the three sets of experimental data. It has been concluded that data obtained from elemental analysis as applied to the Non-Linear Least Square approach gave the most reliable reactivity ratios as 2.09 and 0.40 for acrylonitrile and allyl alcohol, respectively.

  16. Synthesis of quinolones by nickel-catalyzed cycloaddition via elimination of nitrile.

    Science.gov (United States)

    Nakai, Kenichiro; Kurahashi, Takuya; Matsubara, Seijiro

    2013-02-15

    Substituted quinolones were efficiently synthesized via the nickel-catalyzed cycloaddition of o-cyanophenylbenzamide derivatives with alkynes. The reaction involves elimination of a nitrile group by cleavage of the two independent aryl-cyano and aryl-carbonyl C-C bonds of the amides.

  17. Synthesis of 2-substituted tetraphenylenes via transition-metal-catalyzed derivatization of tetraphenylene

    Directory of Open Access Journals (Sweden)

    Shulei Pan

    2016-06-01

    Full Text Available A new strategy for the synthesis of 2-substituted tetraphenylenes through a transition-metal-catalyzed derivatization has been developed. Three types of functionalities, including OAc, X (Cl, Br, I and carbonyl, were introduced onto tetraphenylene, which allows the easy access to a variety of monosubstituted tetraphenylenes. These reactions could accelerate research on the properties and application of tetraphenylene derivatives.

  18. Synthesis of 2-substituted tetraphenylenes via transition-metal-catalyzed derivatization of tetraphenylene

    Science.gov (United States)

    Pan, Shulei; Jiang, Hang; Zhang, Yu; Chen, Dushen

    2016-01-01

    Summary A new strategy for the synthesis of 2-substituted tetraphenylenes through a transition-metal-catalyzed derivatization has been developed. Three types of functionalities, including OAc, X (Cl, Br, I) and carbonyl, were introduced onto tetraphenylene, which allows the easy access to a variety of monosubstituted tetraphenylenes. These reactions could accelerate research on the properties and application of tetraphenylene derivatives. PMID:27559378

  19. A new manganese-mediated, cobalt-catalyzed three-component synthesis of (diarylmethylsulfonamides

    Directory of Open Access Journals (Sweden)

    Antoine Pignon

    2014-02-01

    Full Text Available The synthesis of (diarylmethylsulfonamides and related compounds by a new manganese-mediated, cobalt-catalyzed three-component reaction between sulfonamides, carbonyl compounds and organic bromides is described. This organometallic Mannich-like process allows the formation of the coupling products within minutes at room temperature. A possible mechanism, emphasizing the crucial role of manganese is proposed.

  20. Gold(I)-Assisted α-Allylation of Enals and Enones with Alcohols.

    Science.gov (United States)

    Mastandrea, Marco Michele; Mellonie, Niall; Giacinto, Pietro; Collado, Alba; Nolan, Steven P; Miscione, Gian Pietro; Bottoni, Andrea; Bandini, Marco

    2015-12-01

    The intermolecular α-allylation of enals and enones occurs by the condensation of variously substituted allenamides with allylic alcohols. Cooperative catalysis by [Au(ItBu)NTf2] and AgNTf2 enables the synthesis of a range of densely functionalized α-allylated enals, enones, and acyl silanes in good yield under mild reaction conditions. DFT calculations support the role of an α-gold(I) enal/enone as the active nucleophilic species.

  1. Allyl strontium compounds: synthesis, molecular structure and properties.

    Science.gov (United States)

    Jochmann, Phillip; Davin, Julien P; Maslek, Stefanie; Spaniol, Thomas P; Sarazin, Yann; Carpentier, Jean-Francois; Okuda, Jun

    2012-08-14

    The synthesis and attempted isolation of neutral bis(allyl)strontium [Sr(C(3)H(5))(2)] (1) resulted in the isolation of potassium tris(allyl)strontiate K[Sr(C(3)H(5))(3)] (2). In situ generated 1 shows a pronounced Brønsted basicity, inducing polymerisation of THF. Ate complex 2 crystallises as [K(THF)(2){Sr(C(3)H(5))(3)}(THF)](∞) (2·(THF)(3)). The salt-like solid state structure of 2·(THF)(3) comprises a two-dimensional network of (μ(2)-η(3):η(3)-C(3)H(5))(-) bridged potassium and strontium centres. Synthesis of allyl complexes 1 and 2 utilised SrI(2), [Sr(TMDS)(2)] (3) (TMDS = tetramethyldisilazanide), and [Sr(HMDS)(2)] (HMDS = hexamethyldisilazanide) as strontium precursors. The solid state structure of previously reported [Sr(TMDS)(2)] (3) was established by X-ray single crystal analysis as a dissymmetric dimer of [Sr(2)(TMDS)(4)(THF)(3)] (3·(THF)(3)) with multiple Si-HSr agostic interactions. The presence of ether ligands (THF, 18-crown-6) influenced the Si-HSr resonances in the NMR spectra of the amido complex 3.

  2. Pattern of occurrence and occupancy of carbonylation sites in proteins

    DEFF Research Database (Denmark)

    Rao, R Shyama Prasad; Møller, Ian Max

    2011-01-01

    Proteins are targets for modification by reactive oxygen species, and carbonylation is an important irreversible modification that increases during oxidative stress. While information on protein carbonylation is accumulating, its pattern is not yet understood. We have made a meta......-analysis of the available literature data (456 carbonylation sites on 208 proteins) to appreciate the nature of carbonylation sites in proteins. Of the carbonylated (Arg, Lys, Pro, and Thr – RKPT) amino acids, Lys is the most abundant, whereas Pro is the most susceptible and Thr is the least susceptible. The incidence...... of carbonylation is lower in the N-terminal part of the protein primary sequence. Although a significantly higher number of carbonylated sites occur in Arg-, Lys-, Pro- and Thr-rich regions of proteins, the hydropathy environment of carbonylated sites is not significantly different from potential carbonylation...

  3. Diastereoselective Synthesis of γ-Substituted 2-Butenolides via (CDC)-Rh-Catalyzed Intermolecular Hydroalkylation of Dienes with Silyloxyfurans.

    Science.gov (United States)

    Goldfogel, Matthew J; Roberts, Courtney C; Manan, Rajith S; Meek, Simon J

    2017-01-06

    Catalytic intermolecular hydroalkylation of dienes with silyloxyfuran nucleophiles is reported. Reactions are catalyzed by 5 mol % of a (CDC)-Rh complex and proceed in up to 87% yield and 6:1 dr (syn/anti) to provide allylic butenolides bearing vicinal stereocenters. Reactions proceed with terminal aryl and alkyl dienes and with modified silyl enol ether nucleophiles including a thiophenone variant. Utility of the products is demonstrated in the synthesis of a polypropionate anti,syn-stereotriad.

  4. Carbonyl compounds indoors in a changing climate

    Directory of Open Access Journals (Sweden)

    Brimblecombe Peter

    2012-03-01

    Full Text Available Abstract 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.

  5. Catalytic Enantioselective Electrophilic Aminations of Acyclic α-Alkyl β-Carbonyl Nucleophilies.

    Science.gov (United States)

    Liu, Xiaofeng; Sun, Bingfeng; Deng, Li

    2009-06-01

    Highly enantioselective aminations of acyclic α-alkyl β-keto thioesters and trifluoroethyl α-methyl α-cyanoacetate (12) with as low as 0.05 mol % of a bifunctional cinchona alkaloid catalyst were established. This ability to afford highly enantioselectivity for the amination of α-alkyl β-carbonyl compounds renders the 6'-OH cinchona alkaloid-catalyzed amination applicable for the enantioselective synthesis of acyclic chiral compounds bearing N-substituted quaternary stereocenters. The synthetic application of this reaction is illustrated in a concise asymmetric synthesis of α-methylserine, a key intermediate previously utilized in the total synthesis of a small molecule immunomodulator, conagenin.

  6. Catalyst-free synthesis of skipped dienes from phosphorus ylides, allylic carbonates, and aldehydes via a one-pot SN2' allylation-Wittig strategy.

    Science.gov (United States)

    Xu, Silong; Zhu, Shaoying; Shang, Jian; Zhang, Junjie; Tang, Yuhai; Dou, Jianwei

    2014-04-18

    A catalyst-free allylic alkylation of stabilized phosphorus ylides with allylic carbonates via a regioselective SN2' process is presented. Subsequent one-pot Wittig reaction with both aliphatic and aromatic aldehydes as well as ketenes provides structurally diverse skipped dienes (1,4-dienes) in generally high yields and moderate to excellent stereoselectivity with flexible substituent patterns. This one-pot SN2' allylation-Wittig strategy constitutes a convenient and efficient synthetic method for highly functionalized skipped dienes from readily available starting materials.

  7. Nickel-catalyzed enantioselective cross-couplings of racemic secondary electrophiles that bear an oxygen leaving group.

    Science.gov (United States)

    Oelke, Alexander J; Sun, Jianwei; Fu, Gregory C

    2012-02-15

    To date, effective nickel-catalyzed enantioselective cross-couplings of alkyl electrophiles that bear oxygen leaving groups have been limited to reactions of allylic alcohol derivatives with Grignard reagents. In this Communication, we establish that, in the presence of a nickel/pybox catalyst, a variety of racemic propargylic carbonates are suitable partners for asymmetric couplings with organozinc reagents. The method is compatible with an array of functional groups and utilizes commercially available catalyst components. The development of a versatile nickel-catalyzed enantioselective cross-coupling process for electrophiles that bear a leaving group other than a halide adds a significant new dimension to the scope of these reactions.

  8. Catalytic membrane-installed microchannel reactors for one-second allylic arylation.

    Science.gov (United States)

    Yamada, Yoichi M A; Watanabe, Toshihiro; Torii, Kaoru; Uozumi, Yasuhiro

    2009-10-07

    A variety of catalytic membranes of palladium-complexes with linear polymer ligands were prepared inside a microchannel reactor via coordinative and ionic molecular convolution to provide catalytic membrane-installed microdevices, which were applied to the instantaneous allylic arylation reaction of allylic esters and aryl boron reagents under microflow conditions to afford the corresponding coupling products within 1 second of residence time.

  9. Allyl sulphides in olefin metathesis: catalyst considerations and traceless promotion of ring-closing metathesis.

    Science.gov (United States)

    Edwards, Grant A; Culp, Phillip A; Chalker, Justin M

    2015-01-11

    Allyl sulphides are reactive substrates in ruthenium-catalysed olefin metathesis reactions, provided each substrate is matched with a suitable catalyst. A profile of catalyst activity is described, along with the first demonstration of allyl sulphides as traceless promoters in relayed ring-closing metathesis reactions.

  10. Corn oil and milk enhance the absorption of orally administered allyl isothiocyanate in rats.

    Science.gov (United States)

    Ippoushi, Katsunari; Ueda, Hiroshi; Takeuchi, Atsuko

    2013-11-15

    Allyl isothiocyanate, a chief component of mustard oil, exhibits anticancer effects in both cultured cancer cells and animal models. The accumulation of the N-acetylcysteine conjugate of allyl isothiocyanate, the final metabolite of allyl isothiocyanate, in urine was evaluated in rats that were orally coadministered allyl isothiocyanate with fluids (e.g., water, green tea, milk, and 10% ethanol) or corn oil. The N-acetylcysteine conjugate of allyl isothiocyanate content in urine when allyl isothiocyanate (2 or 4μmol) was coadministered with corn oil or milk showed a greater increase (1.4±0.22 or 2.7±0.34μmol or 1.2±0.32 or 2.5±0.36μmol, 1.6- to 1.8-fold or 1.5-fold, respectively) than when allyl isothiocyanate (2 or 4μmol) was coadministered with water (0.78±0.10 or 1.7±0.17μmol). This result demonstrates that corn oil and milk enhance the absorption of allyl isothiocyanate in rats.

  11. The mechanism for iron-catalyzed alkene isomerization in solution

    Energy Technology Data Exchange (ETDEWEB)

    Sawyer, Karma R.; Glascoe, Elizabeth A.; Cahoon, James F.; Schlegel, Jacob P.; Harris, Charles B.

    2008-05-27

    Here we report nano- through microsecond time-resolved IR experiments of iron-catalyzed alkene isomerization in room-temperature solution. We have monitored the photochemistry of a model system, Fe(CO){sub 4}({eta}{sup 2}-1-hexene), in neat 1-hexene solution. UV-photolysis of the starting material leads to the dissociation of a single CO to form Fe(CO){sub 3}({eta}{sup 2}-1-hexene), in a singlet spin state. This CO loss complex shows a dramatic selectivity to form an allyl hydride, HFe(CO){sub 3}({eta}{sup 3}-C{sub 6}H{sub 11}), via an internal C-H bond-cleavage reaction in 5-25 ns. We find no evidence for the coordination of an alkene molecule from the bath to the CO loss complex, but do observe coordination to the allyl hydride, indicating that it is the key intermediate in the isomerization mechanism. Coordination of the alkene ligand to the allyl hydride leads to the formation of the bis-alkene isomers, Fe(CO){sub 3}({eta}{sup 2}-1-hexene)({eta}{sup 2}-2-hexene) and Fe(CO){sub 3}({eta}{sup 2}-1-hexene){sub 2}. Because of the thermodynamic stability of Fe(CO){sub 3}({eta}{sup 2}-1-hexene)({eta}{sup 2}-2-hexene) over Fe(CO){sub 3}({eta}{sup 2}-1-hexene){sub 2} (ca. 12 kcal/mol), nearly 100% of the alkene population will be 2-alkene. The results presented herein provide the first direct evidence for this mechanism in solution and suggest modifications to the currently accepted mechanism.

  12. Millimeter wave spectra of carbonyl cyanide ⋆

    Science.gov (United States)

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

    2016-01-01

    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. PMID:27738349

  13. Reaction Mechanism for Cocaine Esterase-Catalyzed Hydrolyses of (+)- and (−)-Cocaine: Unexpected Common Rate-Determining Step

    OpenAIRE

    Liu, Junjun; Zhao, Xinyun; Yang, Wenchao; Zhan, Chang-Guo

    2011-01-01

    First-principles quantum mechanical/molecular mechanical (QM/MM)-free energy (FE) calculations have been performed to examine catalytic mechanism for cocaine esterase (CocE)-catalyzed hydrolysis of (+)-cocaine in comparison with CocE-catalyzed hydrolysis of (−)-cocaine. It has been shown that the acylation of (+)-cocaine consists of nucleophilic attack of hydroxyl group of Ser117 on carbonyl carbon of (+)-cocaine benzoyl ester and the dissociation of (+)-cocaine benzoyl ester. The first react...

  14. Construction of an Asymmetric Quaternary Carbon Center via Allylation of Hydrazones

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Bum; Satyender, Apuri; Jang, Doo Ok [Yonsei Univ., Wonju (Korea, Republic of)

    2013-11-15

    Asymmetric indium-mediated allylation of imine derivatives bearing a chiral auxiliary is a reliable strategy for the synthesis of chiral homoallylic amines. Various techniques for indium-mediated stereoselective allylation of imines bearing a chiral auxiliary have been reported. In 1997 Loh and co-workers reported indium-mediated allylation with imines derived from L-valine methyl ester. Since then, many forms of indium-mediated allylation bearing a chiral auxiliary have been reported, including imines derived from (S)-valinol, (R)-phenylglycinol, uracil, (R)-phenylglycinol methyl ester, N-tert-butanesufinamide, and (1R,2S)-1-amino-2-indanol. However, the synthesis of chiral auxiliaries often involves a laborious multi-step synthesis with expensive reagents. Therefore, the development of readily accessible chiral auxiliaries for asymmetric indium-mediated all-ylation is in high demand.

  15. Do garlic-derived allyl sulfides scavenge peroxyl radicals?

    Science.gov (United States)

    Amorati, Riccardo; Pedulli, Gian Franco

    2008-03-21

    The chain-breaking antioxidant activities of two garlic-derived allyl sulfides, i.e. diallyl disulfide (1), the main component of steam-distilled garlic oil, and allyl methyl sulfide (3) were evaluated by studying the thermally initiated autoxidation of cumene or styrene in their presence. Although the rate of cumene oxidation was reduced by addition of both 1 and 3, the dependence on the concentration of the two sulfides could not be explained on the basis of the classic antioxidant mechanism as with phenolic antioxidants. The rate of oxidation of styrene, on the other hand, did not show significant changes upon addition of either 1 or 3. This unusual behaviour was explained in terms of the co-oxidant effect, consisting in the decrease of the autoxidation rate of a substrate forming tertiary peroxyl radicals (i.e. cumene) upon addition of little amounts of a second oxidizable substrate giving rise instead to secondary peroxyl radicals. The relevant rate constants for the reaction of ROO(.) with 1 and 3 were measured as 1.6 and 1.0 M(-1) s(-1), respectively, fully consistent with the H-atom abstraction from substituted sulfides. It is therefore concluded that sulfides 1 and 3 do not scavenge peroxyl radicals and therefore cannot be considered chain-breaking antioxidants.

  16. Copper-Catalyzed Enantioselective Synthesis of α-Hydroxyamine Using Monodentate Phosphoramidites

    Institute of Scientific and Technical Information of China (English)

    DONG,Lin; CUN,Lin-Feng; GONG,Liu-Zhu; MI,Ai-Qiao; JIANG,Yao-Zhong

    2004-01-01

    @@ Development of new methods for the introduction of a nitrogen atom to a carbonyl group is still the most important synthetic target. Cu-catalyzed addition of organozinc reagents to α,β-unsaturated carbonyl compounds has been the subject of intensive investigation.[1] Moreover, trapping of the intermediate Zn-enolates has been achieved using nitrosobenzene. To demonstrate the feasibility of developing enantioselective variants of these tandem C-C bond formations,α,β-unsaturated substrates a~d was subjected to standard reaction conditions using Feringa's (L1*, L2*) and our own phosphoramidite ligands (L3*, L4*). In this reaction, medium to high levels of enantioselectivities were observed.

  17. Efficient Synthesis of Functionalized Benzimidazoles and Perimidines: Ytterbium Chloride Catalyzed CmC Bond Cleavage%Efficient Synthesis of Functionalized Benzimidazoles and Perimidines: Ytterbium Chloride Catalyzed CmC Bond Cleavage

    Institute of Scientific and Technical Information of China (English)

    Cai, Lijian; Ji, Xiaofeng; Yao, Zhigang; Xu, Fan; Shen, Qi

    2011-01-01

    An efficient method is developed for the synthesis of functionalized benzimidazoles and perimidines by the condensation of aryl diamines with β-carbonyl compounds catalyzed by ytterbium chloride. The reactions give good yields under mild conditions. A mechanism involving a lanthanide activated C--C bond cleavage is proposed.

  18. Oxidation of Reduced Sulfur Species: Carbonyl Sulfide

    DEFF Research Database (Denmark)

    Glarborg, Peter; Marshall, Paul

    2013-01-01

    A detailed chemical kinetic model for oxidation of carbonyl sulfide (OCS) has been developed, based on a critical evaluation of data from the literature. The mechanism has been validated against experimental results from batch reactors, flow reactors, and shock tubes. The model predicts satisfact......A detailed chemical kinetic model for oxidation of carbonyl sulfide (OCS) has been developed, based on a critical evaluation of data from the literature. The mechanism has been validated against experimental results from batch reactors, flow reactors, and shock tubes. The model predicts...... by the competition between chain‐branching and ‐propagating steps; modeling predictions are particularly sensitive to the branching fraction for the OCS + O reaction to form CO + SO or CO2 + S....

  19. Carbonyl compounds generated from electronic cigarettes.

    Science.gov (United States)

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

    2014-10-28

    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.

  20. Carbonyl Compounds Generated from Electronic Cigarettes

    Directory of Open Access Journals (Sweden)

    Kanae Bekki

    2014-10-01

    Full Text Available 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.

  1. Catalyzing RE Project Development

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Kate; Elgqvist, Emma; Walker, Andy; Cutler, Dylan; Olis, Dan; DiOrio, Nick; Simpkins, Travis

    2016-09-01

    This poster details how screenings done with REopt - NREL's software modeling platform for energy systems integration and optimization - are helping to catalyze the development of hundreds of megawatts of renewable energy.

  2. Muon Catalyzed Fusion

    Science.gov (United States)

    Armour, Edward A.G.

    2007-01-01

    Muon catalyzed fusion is a process in which a negatively charged muon combines with two nuclei of isotopes of hydrogen, e.g, a proton and a deuteron or a deuteron and a triton, to form a muonic molecular ion in which the binding is so tight that nuclear fusion occurs. The muon is normally released after fusion has taken place and so can catalyze further fusions. As the muon has a mean lifetime of 2.2 microseconds, this is the maximum period over which a muon can participate in this process. This article gives an outline of the history of muon catalyzed fusion from 1947, when it was first realised that such a process might occur, to the present day. It includes a description of the contribution that Drachrnan has made to the theory of muon catalyzed fusion and the influence this has had on the author's research.

  3. Phosphine-catalyzed [4+1] annulation of 1,3-(aza)dienes with maleimides: highly efficient construction of azaspiro[4.4]nonenes.

    Science.gov (United States)

    Yang, Mei; Wang, Tianyi; Cao, Shixuan; He, Zhengjie

    2014-11-14

    Phosphine-catalyzed [4+1] annulation of electron-deficient 1,3-dienes or 1,3-azadienes with maleimides has been successfully developed under very mild conditions, providing a convenient and highly efficient method for constructing 2-azaspiro[4.4]nonenes and 1,7-diazaspiro[4.4]nonenes. This reaction represents the first example of [4+1] cyclization between electron-deficient 4π-conjugated systems and non-allylic phosphorus ylides.

  4. Highly stereoselective synthesis of functionalized 1,3-dienes from a new allyl bromide

    Directory of Open Access Journals (Sweden)

    Asma Fray

    2014-05-01

    Full Text Available New and highly functionalized 1,3-dienes 3 and 4 have been synthesized via two different pathways starting from allyl bromide 1. Firstly, the reaction of allyl bromide 1 with triethylphosphite leads to an allylphosphonate 2, which undergoes the Wittig-Horner reaction with a range of saturated and unsaturated aldehydes gives rise to the corresponding 1,3-dienes 3. Secondly, a highly stereoselective reaction between allyl bromide 1 and nitroalkane salts, offers the possibility to obtaining functionalized (E-1,3-dienes 4.

  5. Carbonyl Emissions from Gasoline and Diesel Motor Vehicles

    Energy Technology Data Exchange (ETDEWEB)

    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.

  6. Synthesis, Molecular Structure and Characterization of Allylic Derivatives of 6-Amino-3-methyl-1,2,4-triazolo[3,4-f][1,2,4]-triazin-8(7H-one

    Directory of Open Access Journals (Sweden)

    Gene-Hsiang Lee

    2006-06-01

    Full Text Available 1-Allyl- (2 and 7-allyl-6-amino-3-methyl-1,2,4-triazolo[3,4-f][1,2,4]triazin-8(7H-one (3 were obtained via the 18-crown-6-ether catalyzed room temperature reactionof 6-amino-3-methyl-1,2,4-triazolo[3,4-f][1,2,4]triazin-8(7H-one (1 with potassiumcarbonate and allyl bromide in dry acetone. The structures of these two derivatives wereverified by 2D-NMR measurements, including gHSQC and gHMBC measurements. Theminor compound 2 may possess aromatic character. A single crystal X-ray diffractionexperiment indicated that the major compound 3 crystallizes from dimethyl sulfoxide in themonoclinic space group P21/n and its molecular structure includes an attached dimethylsulfoxide molecule, resulting in the molecular formula C10H16N6O2S. Molecular structuresof 3 are linked by extensive intermolecular N-H···N hydrogen bonding [graph set C 1 (7]. 1Each molecule is attached to the dimethyl sulfoxide oxygen via N-H···O intermolecularhydrogen bonding. The structure is further stabilized by π-π stacking interactions.

  7. Chemoselective allylation of ketones in ionic liquids containing sulfonate anions.

    Science.gov (United States)

    Galletti, Paola; Moretti, Fabio; Samorì, Chiara; Tagliavini, Emilio

    2009-01-01

    The chemoselective addition of tetraallyltin to dialkyl, alkenyl-alkyl, and alkynyl-alkyl ketones can be performed with high yields in N-methyl-N-butylpyrrolidinium trifuoromethansulfonate (MBP-Tf). Other room temperature ionic liquids (RTILs) can also be successfully employed if some sulfonic acid is added. The reaction is very sensitive to the electronic properties of the substrate. Aryl alkyl ketones bearing electron-withdrawing substituents behave like dialkyl ketones and react promptly; on the contrary, electron-rich aryl alkyl ketones react sluggishly, which allows selective competitive allylation of dialkyl substrates to occur. The ionic liquid solvent can be easily recycled, which meets the green chemistry principles of selectivity and reuse of chemicals. NMR spectroscopic data support the formation of tin-triflate catalysts in situ.

  8. Aerobic Linear Allylic C-H Amination: Overcoming Benzoquinone Inhibition.

    Science.gov (United States)

    Pattillo, Christopher C; Strambeanu, Iulia I; Calleja, Pilar; Vermeulen, Nicolaas A; Mizuno, Tomokazu; White, M Christina

    2016-02-03

    An efficient aerobic linear allylic C-H amination reaction is reported under palladium(II)/bis-sulfoxide/Brønsted base catalysis. The reaction operates under preparative, operationally simple conditions (1 equiv of olefin, 1 atm O2 or air) with reduced Pd(II)/bis-sulfoxide catalyst loadings while providing higher turnovers and product yields than systems employing stoichiometric benzoquinone (BQ) as the terminal oxidant. Pd(II)/BQ π-acidic interactions have been invoked in various catalytic processes and are often considered beneficial in promoting reductive functionalizations. When such electrophilic activation for functionalization is not needed, however, BQ at high concentrations may compete with crucial ligand (bis-sulfoxide) binding and inhibit catalysis. Kinetic studies reveal an inverse relationship between the reaction rate and the concentration of BQ, suggesting that BQ is acting as a ligand for Pd(II) which results in an inhibitory effect on catalysis.

  9. Reductive Umpolung of Carbonyl Derivatives with Visible-Light Photoredox Catalysis: Direct Access to Vicinal Diamines and Amino Alcohols via α-Amino Radicals and Ketyl Radicals

    KAUST Repository

    Fava, Eleonora

    2016-05-02

    Visible-light-mediated photoredox-catalyzed aldimine-aniline and aldehyde-aniline couplings have been realized. The reductive single electron transfer (SET) umpolung of various carbonyl derivatives enabled the generation of intermediary ketyl and α-amino radical anions, which were utilized for the synthesis of unsymmetrically substituted 1,2-diamines and amino alcohols. Anilines can be coupled with aldimines or aldehydes in a visible-light-mediated photoredox-catalyzed process. Reductive single electron transfer (SET) umpolung of the carbonyl derivatives leads to the generation of intermediary ketyl and α-amino radical anions, which were used for the synthesis of unsymmetrically substituted 1,2-diamines and amino alcohols.

  10. Biomarkers derived from heterolytic and homolytic cleavage of allylic hydroperoxides resulting from alkenone autoxidation

    Digital Repository Service at National Institute of Oceanography (India)

    Rontania, J.F.; Harji, R.; Volkmanc, J.K.

    , hydroxyacids and alkyldiols resulted from the reduction during the NaBH4 treatment of the corresponding aldehydes, ketoxyacids and ketoxyaldehydes formed from heterolytic or hemolytic cleavages of allylic hydroperoxyl groups resulting from the oxidation...

  11. Facile synthesis of allyl resinate monomer in an aqueous solution under microwave irradiation

    Indian Academy of Sciences (India)

    Yanju Lu; Mixia Wang; Zhendong Zhao; Yuxiang Chen; Shichao Xu; Jing Wang; Liangwu Bi

    2015-07-01

    We have developed a facile method for production of allyl resinate monomer (allyl rosin ester) via a phase transfer reaction under microwave irradiation. The synthesis of allyl resinate was conducted using allyl chloride and sodium resinate as starting materials in aqueous solution at 50°C for 30 min with a yield of 94.7%, which is 20% higher than conventional heating method. The products precipitated spontaneously from the aqueous phase after reaction, which significantly facilitated the subsequent separation of monomer products. The synthesized monomer product appeared as a viscous liquid, with a viscosity of 460 mPa·s at 25°C and a density of 1.0469 g/cm3. The physical and chemical properties suggested that the synthesized monomer has great potential for free radical polymerization.

  12. Acute inhalation toxicity of carbonyl sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Benson, J.M.; Hahn, F.F.; Barr, E.B. [and others

    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).

  13. Selective epoxidation of allylic alcohols with a titania-silica aerogel

    Energy Technology Data Exchange (ETDEWEB)

    Dusi, M.; Mallat, T.; Baiker, A. [Lab. of Technical Chemistry, Swiss Federal Inst. of Technology, ETH-Zentrum, Zuerich (Switzerland)

    1998-12-31

    An amorphous mesoporous titania-silica aerogel (20 wt%TiO{sub 2} - 80 wt% SiO{sub 2}) and tert.-butylhydroperoxide (TBHP) have been used for the epoxidation of various allylic alcohols. Allylic alcohols possessing an internal double bond were more reactive than those with a terminal C=C bond. Epoxide selectivities could be improved by addition of (basic) zeolite 4 A and NaHCO{sub 3} to the reaction mixture. (orig.)

  14. Pollution survey of carbonyl compounds in train air

    Institute of Scientific and Technical Information of China (English)

    LU Hao; ZHU Lizhong

    2007-01-01

    The train iS an important vehicle in China,but its air quality has important impacts on passengers' health.In this work,pollution from carbonyl compounds was measured in the air of six trains.The obiectives of this work were to investigate carbonyl compound levels in selected air from trains,identify their emission sources,and assess the intake of carbonyl compounds for passengers.The methods for sampling and analyzing 10 carbonyl compounds such as formaldehyde,acetaldehyde,acrolein,acetone,propionalde hyde,crotonaldehyde,butyraldehyde,benzaldehyde,cyclo hexanone,and valeraldehyde in indoor air were proposed with the sampling efficiency,recovery,and detection limit being 92%-100%,91%-104%,and 0.26-0.82 ng/m3,respec tively.It was indicated that the total concentrations of carbonyl compounds were 0.159-0.2828 mg/m3 with the average concentration of 0.2330 mg/m3.The average concen trations of formaldehyde.acetaldehyde and acetone were 0.0922,0.0499,and 0.0580 mg/m3,accounting for 42.6%,21.4%.and 24.9% of the total concentrations of carbonyl compounds,respectively.The carbonyl compounds probably came from woodwork and cigarette smoking.The intake of carbonyl compounds for the passengers was approximately 0.043-0.076 mg/h.The carbonyl compounds in train air could be harmful to human health.

  15. Effect of hydrogen atoms on the structures of trinuclear metal carbonyl clusters: trinuclear manganese carbonyl hydrides.

    Science.gov (United States)

    Liu, Xian-mei; Wang, Chao-yang; Li, Qian-shu; Xie, Yaoming; King, R Bruce; Schaefer, Henry F

    2009-05-18

    The structures of the trinuclear manganese carbonyl hydrides H(3)Mn(3)(CO)(n) (n = 12, 11, 10, 9) have been investigated by density functional theory (DFT). Optimization of H(3)Mn(3)(CO)(12) gives the experimentally known structure in which all carbonyl groups are terminal and each edge of a central Mn(3) equilateral triangle is bridged by a single hydrogen atom. This structure establishes the canonical distance 3.11 A for the Mn-Mn single bond satisfying the 18-electron rule. The central triangular (mu-H)(3)Mn(3) unit is retained in the lowest energy structure of H(3)Mn(3)(CO)(11), which may thus be derived from the H(3)Mn(3)(CO)(12) structure by removal of a carbonyl group with concurrent conversion of one of the remaining carbonyl groups into a semibridging carbonyl group to fill the resulting hole. The potential energy surface of H(3)Mn(3)(CO)(10) is relatively complicated with six singlet and five triplet structures. One of the lower energy H(3)Mn(3)(CO)(10) structures has one of the hydrogen atoms bridging the entire Mn(3) triangle and the other two hydrogen atoms bridging Mn-Mn edges. This H(3)Mn(3)(CO)(10) structure achieves the favored 18-electron configuration with a very short MnMn triple bond of 2.36 A. The other low energy H(3)Mn(3)(CO)(10) structure retains the (mu-H)(3)Mn(3) core of H(3)Mn(3)(CO)(12) but has a unique six-electron donor eta(2)-mu(3) carbonyl group bridging the entire Mn(3) triangle similar to the unique carbonyl group in the known compound Cp(3)Nb(3)(CO)(6)(eta(2)-mu(3)-CO). For H(3)Mn(3)(CO)(9) a structure with a central (mu(3)-H)(2)Mn(3) trigonal bipyramid lies >20 kcal/mol below any of the other structures. Triplet structures were found for the unsaturated H(3)Mn(3)(CO)(n) (n = 11, 10, 9) systems but at significantly higher energies than the lowest lying singlet structures.

  16. Effect of allyl isothiocyanate on developmental toxicity in exposed Xenopus laevis embryos

    Directory of Open Access Journals (Sweden)

    John Russell Williams

    2015-01-01

    Full Text Available The pungent natural compound allyl isothiocyanate isolated from the seeds of Cruciferous (Brassica plants such as mustard is reported to exhibit numerous beneficial health-promoting antimicrobial, antifungal, anticarcinogenic, cardioprotective, and neuroprotective properties. Because it is also reported to damage DNA and is toxic to aquatic organisms, the objective of the present study was to determine whether it possesses teratogenic properties. The frog embryo teratogenesis assay-Xenopus (FETAX was used to determine the following measures of developmental toxicity of the allyl isothiocyanate: (a 96-h LC50, defined as the median concentration causing 50% embryo lethality; (b 96-h EC50, defined as the median concentration causing 50% malformations of the surviving embryos; and (c teratogenic malformation index (TI, equal to 96-h LC50/96-h EC50. The quantitative results and the photographs of embryos before and after exposure suggest that allyl isothiocyanate seems to exhibit moderate teratogenic properties. The results also indicate differences in the toxicity of allyl isothiocyanate toward exposed embryos observed in the present study compared to reported adverse effects of allyl isothiocyanate in fish, rodents, and humans. The significance of the results for food safety and possible approaches to protect against adverse effects of allyl isothiocyanate are discussed.

  17. Kinetics of Methanol Carbonylation to Methyl Formate Catalyzed by Sodium Methoxide

    Institute of Scientific and Technical Information of China (English)

    Liang Chen; Jianghong Zhang; Ping Ning; Yunhua Chen; Wenbing Wu

    2004-01-01

    Kinetics of synthesis of methyl formate from carbon monoxide and methanol, using sodium methoxide as the catalyst and pyridine as the promoter in a batch reactor, was studied. Kinetic parameters such as the apparent reaction orders, the rate constant and the apparent activation energies were obtained.The experimental results showed that both the reaction orders with respect to CO and methanol equal to 1, the general reaction kinetic equation is (-r)=-dp(CO)/dt=k. p(CO).[MeOH], and the rate constant is decreased 6.44 k J/mol and the rate constant had increased more than 1.5 times when pyridine was used as the promoter in the catalyst system.

  18. Carbonyl sulfide: No remedy for global warming

    Science.gov (United States)

    Taubman, Steven J.; Kasting, James F.

    1995-04-01

    The enhancement of the stratospheric aerosol layer caused by the eruption of Mt. Pinatubo (June 15, 1991), and the subsequent cooling of the earth's lower atmosphere [Dutton and Christy, 1992; Minnis et al., 1993] shows that stratospheric aerosols can have a strong effect on the earth's climate. This supports the notion that the intentional enhancement of the stratospheric aerosol layer through increased carbonyl sulfide (OCS) emissions might be an effective means for counteracting global warming. Through the use of a one-dimensional photochemical model, we investigate what effect such a program might have on global average stratospheric ozone. In addition, we consider the impact of enhanced OCS emissions on rainwater acidity and on the overall health of both plants and animals. We find that while the warming produced by a single CO2 doubling (1 to 4°C) might be offset with ozone losses of less than 5%, any attempt to use carbonyl sulfide as a permanent solution to global warming could result in depletion of global average ozone by 30% or more. We estimate that in order to achieve cooling of 4°C rainwater pH would fall to between 3.5 and 3.8. Finally, a 4°C cooling at the surface will require that ambient near ground OCS levels rise to above 10 ppmv which is probably greater than the safe exposure limit for humans. Thus, enhanced OCS emissions do not provide an environmentally acceptable solution to the problem of global warming.

  19. Muon catalyzed fusion

    Energy Technology Data Exchange (ETDEWEB)

    Ishida, K. [Advanced Meson Science Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Nagamine, K. [Muon Science Laboratory, IMSS-KEK, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Matsuzaki, T. [Advanced Meson Science Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Kawamura, N. [Muon Science Laboratory, IMSS-KEK, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)

    2005-12-15

    The latest progress of muon catalyzed fusion study at the RIKEN-RAL muon facility (and partly at TRIUMF) is reported. The topics covered are magnetic field effect, muon transfer to {sup 3}He in solid D/T and ortho-para effect in dd{mu} formation.

  20. Characterization of oxidative carbonylation on recombinant monoclonal antibodies.

    Science.gov (United States)

    Yang, Yi; Stella, Cinzia; Wang, Weiru; Schöneich, Christian; Gennaro, Lynn

    2014-05-20

    In the biotechnology industry, oxidative carbonylation as a post-translational modification of protein pharmaceuticals has not been studied in detail. Using Quality by Design (QbD) principles, understanding the impact of oxidative carbonylation on product quality of protein pharmaceuticals, particularly from a site-specific perspective, is critical. However, comprehensive identification of carbonylation sites has so far remained a very difficult analytical challenge for the industry. In this paper, we report for the first time the identification of specific carbonylation sites on recombinant monoclonal antibodies with a new analytical approach via derivatization with Girard's Reagent T (GRT) and subsequent peptide mapping with high-resolution mass spectrometry. Enhanced ionization efficiency and high quality MS(2) data resulted from GRT derivatization were observed as key benefits of this approach, which enabled direct identification of carbonylation sites without any fractionation or affinity enrichment steps. A simple data filtering process was also incorporated to significantly reduce false positive assignments. Sensitivity and efficiency of this approach were demonstrated by identification of carbonylation sites on both unstressed and oxidized antibody bulk drug substances. The applicability of this approach was further demonstrated by identification of 14 common carbonylation sites on three highly similar IgG1s. Our approach represents a significant improvement to the existing analytical methodologies and facilitates extended characterization of oxidative carbonylation on recombinant monoclonal antibodies and potentially other protein pharmaceuticals in the biotechnology industry.

  1. Synthesis of main-chain metal carbonyl organometallic macromolecules (MCMCOMs).

    Science.gov (United States)

    Cao, Kai; Murshid, Nimer; Wang, Xiaosong

    2015-04-01

    Synthesis of main-chain metal carbonyl organometallic macromolecules (MCMCOMs) is difficult, mainly due to the instability of metal carbonyl complexes. Despite its challenge a number of MCMCOMs has been prepared by strategically using organometallic, organic, and polymer synthetic chemistry. Main contributions to this research field were reported by the groups of Tyler, Pannell, and Wang and are briefly summarized in this article.

  2. Bifunctional dendrons for multiple carbohydrate presentation via carbonyl chemistry

    Directory of Open Access Journals (Sweden)

    Davide Bini

    2014-07-01

    Full Text Available The synthesis of new dendrons of the generations 0, 1 and 2 with a double bond at the focal point and a carbonyl group at the termini has been carried out. The carbonyl group has been exploited for the multivalent conjugation to a sample saccharide by reductive amination and alkoxyamine conjugation.

  3. Detection of Protein Carbonyls by Means of Biotin Hydrazide-Streptavidin Affinity Methods.

    Science.gov (United States)

    Hensley, Kenneth

    2015-01-01

    Oxidative posttranslational protein modifications occur as a normal process of cell biology and to a greater extent during pathogenic conditions. The detection and quantitation of protein oxidation has posed a continuing challenge to bioanalytical chemists because of the following reasons: The products of oxidative protein damage are chemically diverse; protein oxidation generally occurs at low background levels; and the complexity of biological samples introduces high background noise when standard techniques such as immunolabeling are applied to "dirty" tissue extracts containing endogenous immunoglobulins or small molecular weight, chemically reactive compounds has been developed which circumvents these difficulties by incorporating a biotin label at sites of protein carbonylation. Biotin hydrazide-labeled proteins are detectable using standard streptavidin-coupled detection techniques such as peroxidase-catalyzed chemiluminescence of immunoblots. Advantages of the biotin hydrazide-labeling technique are its sensitivity and its lack of reliance upon antibodies that inevitably suffer from nonspecific background noise and contaminating endogenous immunoglobulins.

  4. Carbonyl-Olefin Exchange Reaction: Present State and Outlook

    Science.gov (United States)

    Kalinova, Radostina; Jossifov, Christo

    The carbonyl-olefin exchange reaction (COER) is a new reaction between carbonyl group and olefin double bond, which has a formal similarity with the olefin metathesis (OM) - one carbon atom in the latter is replaced with an oxygen atom. Till now the new reaction is performed successfully only when the two functional groups (carbonyl group and olefin double bond) are in one molecule and are conjugated. The α, β-unsaturated carbonyl compounds (substituted propenones) are the compounds with such a structure. They polymerize giving substituted polyacetylenes. The chain propagation step of this polymerization is in fact the COER. The question arises: is it possible the COER to take place when the two functional groups are not in one molecule and are not conjugated, and could this reaction became an alternative of the existing carbonyl olefination reactions?

  5. Catalyst Initiation in the Oscillatory Carbonylation Reaction

    Directory of Open Access Journals (Sweden)

    Katarina Novakovic

    2011-01-01

    Full Text Available Palladium(II iodide is used as a catalyst in the phenylacetylene oxidative carbonylation reaction that has demonstrated oscillatory behaviour in both pH and heat of reaction. In an attempt to extract the reaction network responsible for the oscillatory nature of this reaction, the system was divided into smaller parts and they were studied. This paper focuses on understanding the reaction network responsible for the initial reactions of palladium(II iodide within this oscillatory reaction. The species researched include methanol, palladium(II iodide, potassium iodide, and carbon monoxide. Several chemical reactions were considered and applied in a modelling study. The study revealed the significant role played by traces of water contained in the standard HPLC grade methanol used.

  6. SN2 reactions with allylic substrates--Trends in reactivity

    Science.gov (United States)

    Ochran, Richard A.; Uggerud, Einar

    2007-09-01

    The gas-phase identity SN2 reactions of allylic substrates has been studied by systematic altering of the nucleophile/nucleofuge X, the remote substituent Y, and the number of methyl substituents at the reaction centre: X- + YCHCHCZ2X --> YCHCHCZ2X + X- (X = H, CH3, NH2, F, Cl; Y = F, OH, H, CHO, BH2; Z = H, CH3). Key regions of the potential energy surfaces have been explored by MP2, B3LYP, G3B3 and G3 calculations; the latter two methods providing accurate estimates of the reaction barrier. The calculations show that irrespective of theoretical level, for the second row of the periodic table (X = CH3, NH2, OH, and F), the tendency is that the barrier height decreases in going from left to right in agreement with the previously observed trend for identity SN2 reactions at methyl. The barrier height decreases by introduction a [pi] electron withdrawing substituents, Y, remote 6rom the reaction centre. The barrier height increases by introducing methyl groups (Z = CH3) next to the reaction centre, but the effect is less than half of that of changing the remote substituent from Y = CHO to Y = OH. The trends cannot be explained by simplified valence bond theory and are discussed in light of a simple electrostatic bonding model of the transition structure.

  7. Allyl isothiocyanate induced stress response in Caenorhabditis elegans

    Directory of Open Access Journals (Sweden)

    Saini AkalRachna K

    2011-11-01

    Full Text Available Abstract Background Allyl isothiocyanate (AITC from mustard is cytotoxic; however the mechanism of its toxicity is unknown. We examined the effects of AITC on heat shock protein (HSP 70 expression in Caenorhabditis elegans. We also examined factors affecting the production of AITC from its precursor, sinigrin, a glucosinolate, in ground Brassica juncea cv. Vulcan seed as mustard has some potential as a biopesticide. Findings An assay to determine the concentration of AITC in ground mustard seed was improved to allow the measurement of AITC release in the first minutes after exposure of ground mustard seed to water. Using this assay, we determined that temperatures above 67°C decreased sinigrin conversion to AITC in hydrated ground B. juncea seed. A pH near 6.0 was found to be necessary for AITC release. RT-qPCR revealed no significant change in HSP70A mRNA expression at low concentrations of AITC ( 1.0 μM resulted in a four- to five-fold increase in expression. A HSP70 ELISA showed that AITC toxicity in C. elegans was ameliorated by the presence of ground seed from low sinigrin B. juncea cv. Arrid. Conclusions • AITC induced toxicity in C. elegans, as measured by HSP70 expression. • Conditions required for the conversion of sinigrin to AITC in ground B. juncea seed were determined. • The use of C. elegans as a bioassay to test AITC or mustard biopesticide efficacy is discussed.

  8. High throughput assay for evaluation of reactive carbonyl scavenging capacity

    Directory of Open Access Journals (Sweden)

    N. Vidal

    2014-01-01

    Full Text Available 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.

  9. 16th Carbonyl Metabolism Meeting: from enzymology to genomics

    Directory of Open Access Journals (Sweden)

    Maser Edmund

    2012-12-01

    Full Text Available Abstract The 16th International Meeting on the Enzymology and Molecular Biology of Carbonyl Metabolism, Castle of Ploen (Schleswig-Holstein, Germany, July 10–15, 2012, covered all aspects of NAD(P-dependent oxido-reductases that are involved in the general metabolism of xenobiotic and physiological carbonyl compounds. Starting 30 years ago with enzyme purification, structure elucidation and enzyme kinetics, the Carbonyl Society members have meanwhile established internationally recognized enzyme nomenclature systems and now consider aspects of enzyme genomics and enzyme evolution along with their roles in diseases. The 16th international meeting included lectures from international speakers from all over the world.

  10. A New HPLC Method to Determine Carbonyl Compounds in Air

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In this paper, a new HPLC method was established to determine the carbonyl compounds in air. As the absorbent, 2, 4-dinitrophenylhydrazine (2, 4-DNPH) reacted with carbonyls specifically, which form the corresponding 2,4-dinitrophenylhydrazones, then analyzed by HPLC. The chromatographic conditions, the recovery rate, stability of samples, reagent blank, sampling efficiency were all studied systematically. The results showed that this established method had high sensitivity and good selectivity compared with other analytical methods, and it can determine ten carbonyl compounds in air in 26 min simultaneously.

  11. Catalyst-Free Imidation of Allyl Sulfides with Chloramine-T and Subsequent [2,3]-Sigmatropic Rearrangement

    Institute of Scientific and Technical Information of China (English)

    江玉波; 莫凡洋; 邱迪; 匡春香; 张艳; 王剑波

    2012-01-01

    A facile synthesis of various allyl sulfonamides based on imidation of allyl sulfides with chloramine-T and sub- sequent [2,3]-sigmatropic rearrangement has been achieved without metal catalysts. The reaction completes smoothly within 10 min, providing excellent yields in environment friendly solvent of alcohol. Functional groups such as bromine, hydroxyl, protected amido and aldehyde are tolerant under this condition.

  12. Allyl isothiocyanate sensitizes TRPV1 to heat stimulation.

    Science.gov (United States)

    Alpizar, Yeranddy A; Boonen, Brett; Gees, Maarten; Sanchez, Alicia; Nilius, Bernd; Voets, Thomas; Talavera, Karel

    2014-03-01

    The powerful plant-derived irritant allyl isothiocyanate (AITC, aka mustard oil) induces hyperalgesia to heat in rodents and humans through mechanisms that are not yet fully understood. It is generally believed that AITC activates the broadly tuned chemosensory cation channel transient receptor potential cation channel subfamily A member 1 (TRPA1), triggering an inflammatory response that sensitizes the heat sensor transient receptor potential cation channel subfamily V member 1 (TRPV1). In the view of recent data demonstrating that AITC can directly activate TRPV1, we here explored the possibility that this compound sensitizes TRPV1 to heat stimulation in a TRPA1-independent manner. Patch-clamp recordings and intracellular Ca(2+) imaging experiments in HEK293T cells over-expressing mouse TRPV1 revealed that the increase in channel activation induced by heating is larger in the presence of AITC than in control conditions. The analysis of the effects of AITC and heat on the current-voltage relationship of TRPV1 indicates that the mechanism of sensitization is based on additive shifts of the voltage dependence of activation towards negative voltages. Finally, intracellular Ca(2+) imaging experiments in mouse sensory neurons isolated from Trpa1 KO mice yielded that AITC enhances the response to heat, specifically in the subpopulation expressing TRPV1. Furthermore, this effect was strongly reduced by the TRPV1 inhibitor capsazepine and virtually absent in neurons isolated from double Trpa1/Trpv1 KO mice. Taken together, these findings demonstrate that TRPV1 is a locus for cross sensitization between AITC and heat in sensory neurons and may help explaining, at least in part, the role of this channel in AITC-induced hyperalgesia to heat.

  13. How phenyl makes a difference: mechanistic insights into the ruthenium( ii )-catalysed isomerisation of allylic alcohols

    KAUST Repository

    Manzini, Simone

    2013-10-16

    [RuCl(η5-3-phenylindenyl)(PPh3)2] (1) has been shown to be a highly active catalyst for the isomerisation of allylic alcohols to the corresponding ketones. A variety of substrates undergo the transformation, typically with 0.25-0.5 mol% of catalyst at room temperature, outperforming commonly-used complexes such as [RuCl(Cp)(PPh3) 2] and [RuCl(η5-indenyl)(PPh3) 2]. Mechanistic experiments and density functional theory have been employed to investigate the mechanism and understand the effect of catalyst structure on reactivity. These investigations suggest a oxo-π-allyl mechanism is in operation, avoiding intermediate ruthenium hydride complexes and leading to a characteristic 1,3-deuterium shift. Important mechanistic insights from DFT and experiments also allowed for the design of a protocol that expands the scope of the transformation to include primary allylic alcohols. © 2013 The Royal Society of Chemistry.

  14. Theoretical Studies on the Iodine-catalyzed Nucleophilic Addition of Acetone with Five-membered Heterocycles

    Institute of Scientific and Technical Information of China (English)

    WANG Yan-hua; LI Li; CHEN Xue-song

    2008-01-01

    The iodine-catalyzed nucleophilic addition reactions of pyrrole,furan,or thiophene with acetone were studied in gas and solvent by the density functional theory at the level of Lan12DZ*,It was seen that the halogen bond between iodine and carbonyl oxygen appeared to have an important catalytic effect on such reactions,and the first iodine molecule maximally diminished the barrier height by 41 kJ/mol,while the second iodine molecule could not improve such reactions largely,It was concluded that the C2-addition was generally more favorable than the C3-addition for the three heterocycles;however,iodine considerably more effectively catalyzed the C3-addition than the C2-addition for pyrrole,It was also revealed by PCM calculation that the iodine-catalyzed nucleophilic additions occurred more easily in solvent than in gas,which explained the experiment performed by Bandgar et al..

  15. Bite angle effects of diphosphines in carbonylation reactions

    NARCIS (Netherlands)

    P.W.N.M. van Leeuwen; Z. Freixa

    2008-01-01

    This chapter contains sections titled: * Introduction * Rhodium-Catalyzed Hydroformylation o Introduction o Steric Bite Angle Effect and Regioselectivity o Electronic Bite Angle Effect and Activity o Isotope Effects [24] * Platinum-Catalyzed Alkene Hydroformylation * Palladium-Catalyzed CO/Ethene Co

  16. Deposition of carbonyl sulphide to soils

    Science.gov (United States)

    Kluczewski, S. M.; Brown, K. A.; Bel, J. N. B.

    Carbonyl sulphide (COS) is a trace constituent of the atmosphere and is also the main form in which 35S is released from CO 2-cooled nuclear reactors. Measurements of its deposition velocity ( Vg) are therefore important for validating radiological dose models and for interpreting the role of COS in the global S cycle. The Vg of [ 35S]COS to thin layers of several contrasting soils was measured in a through-flow fumigation system. Deposition velocity was not significantly affected by soil type, although deposition to moist soil was significantly greater ( P dried soils, mean values being 5.71 × 10 -6 ms -1 and 3.06 × 10 -6 ms -1, respectively. The results obtained are about three orders of magnitude smaller than published Vg values for SO 2 to similar soils, which suggests that uptake by soils is not a major sink for atmospheric COS. The results are consistent with the hypothesis that deposition to soil of [ 35S]COS from nuclear reactors is unlikely to contribute significantly to radiation dose from the food chain pathway. The reduction in Vg observed in heat-treated soils indicates a microbial involvement in uptake. However, it seems unlikely that microbial metabolism is the rate-controlling step, since stimulation of the microflora by the addition of nutrients did not increase COS deposition.

  17. Chemoselective and stereoselective lithium carbenoid mediated cyclopropanation of acyclic allylic alcohols.

    Science.gov (United States)

    Durán-Peña, M J; Flores-Giubi, M E; Botubol-Ares, J M; Harwood, L M; Collado, I G; Macías-Sánchez, A J; Hernández-Galán, R

    2016-03-01

    The reaction of geraniol with different lithium carbenoids generated from n-BuLi and the corresponding dihaloalkane has been evaluated. The reaction occurs in a chemo and stereoselective manner, which is consistent with a directing effect from the oxygen of the allylic moiety. Furthermore, a set of polyenes containing allylic hydroxyl or ether groups were chemoselectively and stereoselectively converted into the corresponding gem-dimethylcyclopropanes in one single step in moderate to good yields mediated by a lithium carbenoid generated in situ by the reaction of n-BuLi and 2,2-dibromopropane.

  18. Transient overexpression of adh8a increases allyl alcohol toxicity in zebrafish embryos.

    Directory of Open Access Journals (Sweden)

    Nils Klüver

    Full Text Available Fish embryos are widely used as an alternative model to study toxicity in vertebrates. Due to their complexity, embryos are believed to more resemble an adult organism than in vitro cellular models. However, concerns have been raised with respect to the embryo's metabolic capacity. We recently identified allyl alcohol, an industrial chemical, to be several orders of magnitude less toxic to zebrafish embryo than to adult zebrafish (embryo LC50 = 478 mg/L vs. fish LC50 = 0.28 mg/L. Reports on mammals have indicated that allyl alcohol requires activation by alcohol dehydrogenases (Adh to form the highly reactive and toxic metabolite acrolein, which shows similar toxicity in zebrafish embryos and adults. To identify if a limited metabolic capacity of embryos indeed can explain the low allyl alcohol sensitivity of zebrafish embryos, we compared the mRNA expression levels of Adh isoenzymes (adh5, adh8a, adh8b and adhfe1 during embryo development to that in adult fish. The greatest difference between embryo and adult fish was found for adh8a and adh8b expression. Therefore, we hypothesized that these genes might be required for allyl alcohol activation. Microinjection of adh8a, but not adh8b mRNA led to a significant increase of allyl alcohol toxicity in embryos similar to levels reported for adults (LC50 = 0.42 mg/L in adh8a mRNA-injected embryos. Furthermore, GC/MS analysis of adh8a-injected embryos indicated a significant decline of internal allyl alcohol concentrations from 0.23-58 ng/embryo to levels below the limit of detection (< 4.6 µg/L. Injection of neither adh8b nor gfp mRNA had an impact on internal allyl alcohol levels supporting that the increased allyl alcohol toxicity was mediated by an increase in its metabolization. These results underline the necessity to critically consider metabolic activation in the zebrafish embryo. As demonstrated here, mRNA injection is one useful approach to study the role of candidate enzymes

  19. Theoretical Estimate of Hydride Affinities of Aromatic Carbonyl Compounds

    Institute of Scientific and Technical Information of China (English)

    AI Teng; ZHU Xiao-Qing; CHENG Jin-Pei

    2003-01-01

    @@ Aromatic carbonyl compounds are one type of the most important organic compounds, and the reductions ofthem by hydride agents such as LiAlH4 or NaBH4 are widely used in organic synthesis. The reactivity of carbonyl compounds generally increases in the following order: ketone < aldehyde, and amide < acid < ester < acid halide, which could be related to their hydride affinities (HA). In the previous paper, Robert[1] calculated the absolute HAof a series of small non-aromatic carbonyl compounds. In this paper, we use DFT method at B3LYP/6-311 + + G (2d, 2p)∥B3LYP/6-31 + G* level to estimate hydride affinities of five groups of aromatic carbonyl compounds. The detailed results are listed in Table 1.

  20. Catalyzed Ceramic Burner Material

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, Amy S., Dr.

    2012-06-29

    Catalyzed combustion offers the advantages of increased fuel efficiency, decreased emissions (both NOx and CO), and an expanded operating range. These performance improvements are related to the ability of the catalyst to stabilize a flame at or within the burner media and to combust fuel at much lower temperatures. This technology has a diverse set of applications in industrial and commercial heating, including boilers for the paper, food and chemical industries. However, wide spread adoption of catalyzed combustion has been limited by the high cost of precious metals needed for the catalyst materials. The primary objective of this project was the development of an innovative catalyzed burner media for commercial and small industrial boiler applications that drastically reduce the unit cost of the catalyzed media without sacrificing the benefits associated with catalyzed combustion. The scope of this program was to identify both the optimum substrate material as well as the best performing catalyst construction to meet or exceed industry standards for durability, cost, energy efficiency, and emissions. It was anticipated that commercial implementation of this technology would result in significant energy savings and reduced emissions. Based on demonstrated achievements, there is a potential to reduce NOx emissions by 40,000 TPY and natural gas consumption by 8.9 TBtu in industries that heavily utilize natural gas for process heating. These industries include food manufacturing, polymer processing, and pulp and paper manufacturing. Initial evaluation of commercial solutions and upcoming EPA regulations suggests that small to midsized boilers in industrial and commercial markets could possibly see the greatest benefit from this technology. While out of scope for the current program, an extension of this technology could also be applied to catalytic oxidation for volatile organic compounds (VOCs). Considerable progress has been made over the course of the grant

  1. Carbonyl-Olefin Exchange Reaction and Related Chemistry

    Science.gov (United States)

    Jossifov, Christo; Kalinova, Radostina

    A new carbon—carbon double bond forming reaction (carbonyl olefin exchange reaction) mediated by transition metal catalytic systems has been discovered. The catalytic systems used (transition metal halides or oxohalides alone or in combination with Lewis acids) are active only in the case when the two reacting groups are in one molecules and are conjugated. In addition these systems accelerate other reactions which run simultaneously with the carbonyl olefin metathesis rendering a detailed investigation of the process very complicated.

  2. DNA damage by carbonyl stress in human skin cells

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Michael J.; Wondrak, Georg T.; Laurean, Daniel Cervantes; Jacobson, Myron K.; Jacobson, Elaine L

    2003-01-28

    Reactive carbonyl species (RCS) are potent mediators of cellular carbonyl stress originating from endogenous chemical processes such as lipid peroxidation and glycation. Skin deterioration as observed in photoaging and diabetes has been linked to accumulative protein damage from glycation, but the effects of carbonyl stress on skin cell genomic integrity are ill defined. In this study, the genotoxic effects of acute carbonyl stress on HaCaT keratinocytes and CF3 fibroblasts were assessed. Administration of the {alpha}-dicarbonyl compounds glyoxal and methylglyoxal as physiologically relevant RCS inhibited skin cell proliferation, led to intra-cellular protein glycation as evidenced by the accumulation of N{sup {epsilon}}-(carboxymethyl)-L-lysine (CML) in histones, and caused extensive DNA strand cleavage as assessed by the comet assay. These effects were prevented by treatment with the carbonyl scavenger D-penicillamine. Both glyoxal and methylglyoxal damaged DNA in intact cells. Glyoxal caused DNA strand breaks while methylglyoxal produced extensive DNA-protein cross-linking as evidenced by pronounced nuclear condensation and total suppression of comet formation. Glycation by glyoxal and methylglyoxal resulted in histone cross-linking in vitro and induced oxygen-dependent cleavage of plasmid DNA, which was partly suppressed by the hydroxyl scavenger mannitol. We suggest that a chemical mechanism of cellular DNA damage by carbonyl stress occurs in which histone glycoxidation is followed by reactive oxygen induced DNA stand breaks. The genotoxic potential of RCS in cultured skin cells and its suppression by a carbonyl scavenger as described in this study have implications for skin damage and carcinogenesis and its prevention by agents selective for carbonyl stress.

  3. Carbonyl species characteristics during the evaporation of essential oils

    Science.gov (United States)

    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.

  4. Aldo-keto reductase family 1 B10 protein detoxifies dietary and lipid-derived alpha, beta-unsaturated carbonyls at physiological levels

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Linlin [Department of Medical Microbiology, Immunology, and Cell Biology, SimmonsCooper Cancer Institute, Southern Illinois University School of Medicine, 913 N. Rutledge Street, Springfield, IL 62794-9626 (United States); Department of Neurobiology and Anatomy, China Medical University, Shenyang 110001 (China); Liu, Ziwen [Department of Medical Microbiology, Immunology, and Cell Biology, SimmonsCooper Cancer Institute, Southern Illinois University School of Medicine, 913 N. Rutledge Street, Springfield, IL 62794-9626 (United States); Department of Surgery, Peking Union Medical College Hospital, Beijing 100730 (China); Yan, Ruilan [Department of Medical Microbiology, Immunology, and Cell Biology, SimmonsCooper Cancer Institute, Southern Illinois University School of Medicine, 913 N. Rutledge Street, Springfield, IL 62794-9626 (United States); Johnson, Stephen [Carbon Dynamics Institute, LLC, 2835 via Verde Drive, Springfield, IL 62703-4325 (United States); Zhao, Yupei [Department of Surgery, Peking Union Medical College Hospital, Beijing 100730 (China); Fang, Xiubin [Department of Neurobiology and Anatomy, China Medical University, Shenyang 110001 (China); Cao, Deliang, E-mail: dcao@siumed.edu [Department of Medical Microbiology, Immunology, and Cell Biology, SimmonsCooper Cancer Institute, Southern Illinois University School of Medicine, 913 N. Rutledge Street, Springfield, IL 62794-9626 (United States)

    2009-09-18

    Alpha, beta-unsaturated carbonyls are highly reactive mutagens and carcinogens to which humans are exposed on a daily basis. This study demonstrates that aldo-keto reductase family 1 member B10 (AKR1B10) is a critical protein in detoxifying dietary and lipid-derived unsaturated carbonyls. Purified AKR1B10 recombinant protein efficiently catalyzed the reduction to less toxic alcohol forms of crotonaldehyde at 0.90 {mu}M, 4-hydroxynonenal (HNE) at 0.10 {mu}M, trans-2-hexanal at 0.10 {mu}M, and trans-2,4-hexadienal at 0.05 {mu}M, the concentrations at or lower than physiological exposures. Ectopically expressed AKR1B10 in 293T cells eliminated immediately HNE at 1 (subtoxic) or 5 {mu}M (toxic) by converting to 1,4-dihydroxynonene, protecting the cells from HNE toxicity. AKR1B10 protein also showed strong enzymatic activity toward glutathione-conjugated carbonyls. Taken together, our study results suggest that AKR1B10 specifically expressed in the intestine is physiologically important in protecting the host cell against dietary and lipid-derived cytotoxic carbonyls.

  5. Enantiodivergent Fluorination of Allylic Alcohols: Data Set Design Reveals Structural Interplay between Achiral Directing Group and Chiral Anion.

    Science.gov (United States)

    Neel, Andrew J; Milo, Anat; Sigman, Matthew S; Toste, F Dean

    2016-03-23

    Enantioselectivity values represent relative rate measurements that are sensitive to the structural features of the substrates and catalysts interacting to produce them. Therefore, well-designed enantioselectivity data sets are information rich and can provide key insights regarding specific molecular interactions. However, if the mechanism for enantioselection varies throughout a data set, these values cannot be easily compared. This premise, which is the crux of free energy relationships, exposes a challenging issue of identifying mechanistic breaks within multivariate correlations. Herein, we describe an approach to addressing this problem in the context of a chiral phosphoric acid catalyzed fluorination of allylic alcohols using aryl boronic acids as transient directing groups. By designing a data set in which both the phosphoric and boronic acid structures were systematically varied, key enantioselectivity outliers were identified and analyzed. A mechanistic study was executed to reveal the structural origins of these outliers, which was consistent with the presence of several mechanistic regimes within the data set. While 2- and 4-substituted aryl boronic acids favored the (R)-enantiomer with most of the studied catalysts, meta-alkoxy substituted aryl boronic acids resulted in the (S)-enantiomer when used in combination with certain (R)-phosphoric acids. We propose that this selectivity reversal is the result of a lone pair-π interaction between the substrate ligated boronic acid and the phosphate. On the basis of this proposal, a catalyst system was identified, capable of producing either enantiomer in high enantioselectivity (77% (R)-2 to 92% (S)-2) using the same chiral catalyst by subtly changing the structure of the achiral boronic acid.

  6. Polystyrene-supported Selenides and Selenoxide:Versatile Routes to Synthesize Allylic Alcohols

    Institute of Scientific and Technical Information of China (English)

    Wei Ming XU; You Chu ZHANG; Xian HUANG

    2003-01-01

    Several polystyrene-supported selenides and selenoxide have been prepared firstly. These novel reagents were treated with LDA to produce selenium stabilized carbanions, which reacted with aldehydes and alkyl halides, followed by selenoxide syn-elimination and [2,3] sigmatropic rearrangement respectively to give Z-allylic alcohols stereoselectively.

  7. Method of preparing water purification membranes. [polymerization of allyl amine as thin films in plasma discharge

    Science.gov (United States)

    Hollahan, J. R.; Wydeven, T. J., Jr. (Inventor)

    1974-01-01

    Allyl amine and chemically related compounds are polymerized as thin films in the presence of a plasma discharge. The monomer compound can be polymerized by itself or in the presence of an additive gas to promote polymerization and act as a carrier. The polymerized films thus produced show outstanding advantages when used as reverse osmosis membranes.

  8. Facile Formation of Ytterbium Diiodide and Its Use in the Synthesis of Allyl Selenides

    Institute of Scientific and Technical Information of China (English)

    SU,Wei-Ke(苏为科); ZHANG,Yong-Min(张永敏); ZHENG,Yun-Fa(郑云法); LI,Yong-Shu(李永曙)

    2002-01-01

    Ytterbium metal reacts with iodine to generate ytterbium diiodide directly, which can react with diselenides to form ytterbium selenolates (RSeYbI2). These species reacted smoothly with allyl bromide to give allylselenides in moderate to good yields under neutral conditions.

  9. Combined experimental and theoretical mechanistic investigation of the Barbier allylation in aqueous media

    DEFF Research Database (Denmark)

    Dam, Johan Hygum; Fristrup, Peter; Madsen, Robert

    2008-01-01

    -determining step. For Zn, In, Sn, Sb, and Bi, an inverse secondary kinetic isotope effect was found (k(H)/k(D) = 0.75-0.95), which was compatible with the formation of a discrete organometallic species prior to allylation via a closed six-membered transition state. With Mg, a significantly larger build...

  10. Unusual selectivity-determining factors in the phosphine-free Heck arylation of allyl ethers

    DEFF Research Database (Denmark)

    Ambrogio, I.; Fabrizi, G.; Cacchi, S.

    2008-01-01

    The Heck reaction of aryl iodides and bromides with allyl ethers has been investigated. Using phosphinefree Pd(OAc)(2) in DNIF at 90 degrees C in the presence of Bu4NOAc, the reaction gave cinnamyl derivatives, usually in good to high yields, with a wide range of aryl halides. The reaction tolera...

  11. Synthesis of allyl esters of fatty acids and their ovicidal effect on Cydia pomonella (L.).

    Science.gov (United States)

    Escribà, Marc; Barbut, Montserrat; Eras, Jordi; Canela, Ramon; Avilla, Jesús; Balcells, Mercè

    2009-06-10

    Eight allyl esters of fatty acids were synthesized in moderate to high yields with a novel two-step procedure using glycerol as a starting material. The two-step methodology avoids the use of allyl alcohol. The first step consisted of heating at 80 degrees C for 48 h a 2:1:5 mmol mixture of glycerol, a fatty acid, and chlorotrimethylsilane in a solvent-free medium. The crude compound was then dissolved in butanone and heated at 115 degrees C in the presence of NaI. A tandem Finkelstein rearrangement-elimination reaction occurs, producing the corresponding allyl ester. The activity of these esters against Cydia pomonella (L.) (Lepidoptera: Tortricidae) eggs was tested in the laboratory by topical application of one 0.1 microL drop. All of the compounds showed a concentration-mortality response and caused 100% mortality at the highest concentration tested (10 mg/mL). There was an inverse relationship between the alkyl chain length and the ovicidal activity of the allyl ester; the LC(50) and the LC(90) of the two compounds that have the longer alkyl chains were significantly higher than those of the rest of the compounds. The ovicidal and IGR activities of this kind of compound appear to be unprecedented.

  12. Cooperative catalysis by palladium and a chiral phosphoric acid: enantioselective amination of racemic allylic alcohols.

    Science.gov (United States)

    Banerjee, Debasis; Junge, Kathrin; Beller, Matthias

    2014-11-24

    Cooperative catalysis by [Pd(dba)2] and the chiral phosphoric acid BA1 in combination with the phosphoramidite ligand L8 enabled the efficient enantioselective amination of racemic allylic alcohols with a variety of functionalized amines. This catalytic protocol is highly regio- and stereoselective (up to e.r. 96:4) and furnishes valuable chiral amines in almost quantitative yield.

  13. Electrochemical studies and self diffusion coefficients in cyclic ammonium based ionic liquids with allyl substituents

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Tzi-Yi [Department of Chemistry, National Cheng Kung University, Tainan 701, Taiwan (China); Department of Polymer Materials, Kun Shan University, Tainan 71003, Taiwan (China); Su, Shyh-Gang [Department of Chemistry, National Cheng Kung University, Tainan 701, Taiwan (China); Wang, H. Paul [Department of Environmental Engineering, National Cheng Kung University, Tainan, Taiwan (China); Lin, Yuan-Chung [Institute of Environmental Engineering, National Sun Yat-Sen University, Kaohsiung 804, Taiwan (China); Gung, Shr-Tusen; Lin, Ming-Wei [Department of Chemistry, National Cheng Kung University, Tainan 701, Taiwan (China); Sun, I.-Wen, E-mail: iwsun@mail.ncku.edu.t [Department of Chemistry, National Cheng Kung University, Tainan 701, Taiwan (China)

    2011-03-30

    Research highlights: Cyclic ammonium-based ionic liquids with allyl substituent have high conductivity. Ionic liquids with allyl substituent have wide electrochemical window. Electrochemical and self diffusion coefficients are available for comparison. The Stokes-Einstein plots of DT{sup -1} vs. {eta}{sup -1} for redox couples in ILs are evaluated. Stokes-Einstein product of ferrocene is larger than that of cobaltocenium in ILs. - Abstract: Several cyclic ammonium-based ionic liquids (ILs) with allyl substituent are synthesized, these allyl substituent ILs have high ionic conductivity (up to 4.72 mS cm{sup -1} at 30 {sup o}C) and wide electrochemical window of 5 V. The electrochemical behaviors of two organometallic redox couples Fc/Fc{sup +} (ferrocene/ferrocenium) and Cc/Cc{sup +} (cobaltocene/cobaltocenium) have been studied in these ILs, the calculated Stokes-Einstein product (D{eta} T{sup -1}) of ferrocene in ILs is larger than that of cobaltocenium in ILs. The self-diffusion coefficients of cation and anion in these ILs are studied using pulsed gradient spin-echo NMR technique. There are very few reports where electrochemically derived diffusion coefficients and self diffusion coefficients are available for comparison, so a new key concept in electrochemistry could be developed in this paper.

  14. [N-allyl-Dmt1]-endomorphins are micro-opioid receptor antagonists lacking inverse agonist properties.

    Science.gov (United States)

    Marczak, Ewa D; Jinsmaa, Yunden; Li, Tingyou; Bryant, Sharon D; Tsuda, Yuko; Okada, Yoshio; Lazarus, Lawrence H

    2007-10-01

    [N-allyl-Dmt1]-endomorphin-1 and -2 ([N-allyl-Dmt1]-EM-1 and -2) are new selective micro-opioid receptor antagonists obtained by N-alkylation with an allyl group on the amino terminus of 2',6'-dimethyl-L-tyrosine (Dmt) derivatives. To further characterize properties of these compounds, their intrinsic activities were assessed by functional guanosine 5'-O-(3-[35S]thiotriphosphate) binding assays and forskolin-stimulated cyclic AMP accumulation in cell membranes obtained from vehicle, morphine, and ethanol-treated SK-N-SH cells and brain membranes isolated from naive and morphine-dependent mice; their mode of action was compared with naloxone or naltrexone, which both are standard nonspecific opioid-receptor antagonists. [N-allyl-Dmt1]-EM-1 and -2 were neutral antagonists under all of the experimental conditions examined, in contrast to naloxone and naltrexone, which behave as neutral antagonists only in membranes from vehicle-treated cells and mice but act as inverse agonists in membranes from morphine- and ethanol-treated cells as well as morphine-treated mice. Both endomorphin analogs inhibited the naloxone- and naltrexone-elicited withdrawal syndromes from acute morphine dependence in mice. This suggests their potential therapeutic application in the treatment of drug addiction and alcohol abuse without the adverse effects observed with inverse agonist alkaloid-derived compounds that produce severe withdrawal symptoms.

  15. A Novel, One-Step Palladium and Phenylsilane Activated Amidation from Allyl Ester on Solid Support

    Directory of Open Access Journals (Sweden)

    Zheming Ruan

    2008-01-01

    Full Text Available The direct conversion of solid-supported carboxylic acid allyl esters to carboxamides through the use of phenylsilane and catalytic Pd(PPh34 under mild reaction conditions is reported. The use of this methodology for the generation of a 48 compound solid-phase array is described herein.

  16. Catalytic allylation of phenols : chloride-free route towards epoxy resins

    NARCIS (Netherlands)

    Rijn, Jimmy Antonius van

    2010-01-01

    An industrially applicable process was developed for the synthesis of epoxy resin components. A catalytic reaction was explored towards allyl phenyl ethers that prevents the use of chloride-containing starting materials and thus formation of chloride-containing side products. The preferred allylatin

  17. Cobalt catalyzed hydroesterification of a wide range of olefins

    Energy Technology Data Exchange (ETDEWEB)

    Van Rensburg, H.; Hanton, M.; Tooze, R.P.; Foster, D.F. [Sasol Technology UK, St Andrews (United Kingdom)

    2011-07-01

    Petrochemical raw materials are an essential raw material for the production of detergents with a substantial portion of synthetic fatty alcohols being produced via hydroformylation of oil or coal derived olefins. Carbonylation processes other than hydroformylation have to date not been commercially employed for the production of fatty esters or alcohols. In this document we highlight the opportunities of converting olefins to esters using cobalt catalyzed alkoxycarbonylation. This process is highly versatile and applicable to a wide range of olefins, linear or branched, alpha or internal in combination with virtually any chain length primary or secondary alcohol allowing the synthesis of a diverse array of compounds such as ester ethoxylated surfactants, methyl branched detergents, lubricants and alkyl propanoates. Furthermore, alkoxycarbonylation of a broad olefin/paraffin hydrocarbon range could be used to produce the corresponding broad cut detergent alcohols. (orig.)

  18. Synthesis, Characterization, and Some Properties of Cp*W(NO)(H)(η(3)-allyl) Complexes.

    Science.gov (United States)

    Baillie, Rhett A; Holmes, Aaron S; Lefèvre, Guillaume P; Patrick, Brian O; Shree, Monica V; Wakeham, Russell J; Legzdins, Peter; Rosenfeld, Devon C

    2015-06-15

    Sequential treatment at low temperatures of Cp*W(NO)Cl2 in THF with 1 equiv of a binary magnesium allyl reagent, followed by an excess of LiBH4, affords three new Cp*W(NO)(H)(η(3)-allyl) complexes, namely, Cp*W(NO)(H)(η(3)-CH2CHCMe2) (1), Cp*W(NO)(H)(η(3)-CH2CHCHPh) (2), and Cp*W(NO)(H)(η(3)-CH2CHCHMe) (3). Complexes 1-3 are isolable as air-stable, analytically pure yellow solids in good to moderate yields by chromatography or fractional crystallization. In solutions, complex 1 exists as two coordination isomers in an 83:17 ratio differing with respect to the endo/exo orientation of the allyl ligand. In contrast, complexes 2 and 3 each exist as four coordination isomers, all differing by the orientation of their allyl ligands which can have either an endo or an exo orientation with the phenyl or methyl groups being either proximal or distal to the nitrosyl ligand. A DFT computational analysis using the major isomer of Cp*W(NO)(H)(η(3)-CH2CHCHMe) (3a) as the model complex has revealed that its lowest-energy thermal-decomposition pathway involves the intramolecular isomerization of 3a to the 16e η(2)-alkene complex, Cp*W(NO)(η(2)-CH2═CHCH2Me). Such η(2)-alkene complexes are isolable as their 18e PMe3 adducts when compounds 1-3 are thermolyzed in neat PMe3, the other organometallic products formed during these thermolyses being Cp*W(NO)(PMe3)2 (5) and, occasionally, Cp*W(NO)(H)(η(1)-allyl)(PMe3). All new complexes have been characterized by conventional spectroscopic and analytical methods, and the solid-state molecular structures of most of them have been established by single-crystal X-ray crystallographic analyses.

  19. Catalyzing alignment processes

    DEFF Research Database (Denmark)

    Lauridsen, Erik Hagelskjær; Jørgensen, Ulrik

    2004-01-01

    This paper describes how environmental management systems (EMS) spur the circulation of processes that support the constitution of environmental issues as specific environ¬mental objects and objectives. EMS catalyzes alignmentprocesses that produce coherence among the different elements involved......, the networks of environmental professionals that work in the environmental organisation, in consulting and regulatory enforcement, and dominating business cultures. These have previously been identified in the literature as individually significant in relation to the evolving environmental agendas....... They are here used to describe the context in which environmental management is implemented. Based on findings from contributions to a research program studying the implementation and impact of EMS in different settings, we highlight the diverse roles that these systems play in the Thai context. EMS may over...

  20. The Development and Application of Two-Chamber Reactors and Carbon Monoxide Precursors for Safe Carbonylation Reactions.

    Science.gov (United States)

    Friis, Stig D; Lindhardt, Anders T; Skrydstrup, Troels

    2016-04-19

    Low molecular weight gases (e.g., carbon monoxide, hydrogen, and ethylene) represent vital building blocks for the construction of a wide array of organic molecules. Whereas experimental organic chemists routinely handle solid and liquid reagents, the same is not the case for gaseous reagents. Synthetic transformations employing such reagents are commonly conducted under pressure in autoclaves or under atmospheric pressure with a balloon setup, which necessitates either specialized equipment or potentially hazardous and nonrecommended installations. Other safety concerns associated with gaseous reagents may include their toxicity and flammability and, with certain gases, their inability to be detected by human senses. Despite these significant drawbacks, industrial processes apply gaseous building blocks regularly due to their low cost and ready availability but nevertheless under a strictly controlled manner. Carbon monoxide (CO) fits with all the parameters for being a gas of immense industrial importance but with severe handling restrictions due to its inherent toxicity and flammability. In academia, as well as research and development laboratories, CO is often avoided because of these safety issues, which is a limitation for the development of new carbonylation reactions. With our desire to address the handling of CO in a laboratory setting, we designed and developed a two-chamber reactor (COware) for the controlled delivery and utilization of stoichiometric amounts of CO for Pd-catalyzed carbonylation reactions. In addition to COware, two stable and solid CO-releasing molecules (COgen and SilaCOgen) were developed, both of which release CO upon activation by either Pd catalysis or fluoride addition, respectively. The unique combination of COware with either COgen or SilaCOgen provides a simple reactor setup enabling synthetic chemists to easily perform safe carbonylation chemistry without the need for directly handling the gaseous reagent. With this technology

  1. The Wacker oxidation of allyl alcohol along cyclic-intermediate routes: An ab initio molecular dynamics investigation

    Science.gov (United States)

    Imandi, Venkataramana; Nair, Nisanth N.

    2016-09-01

    The absence of isotope scrambling observed by Henry and coworkers in the Wacker oxidation of deuterated allylic alcohol was used by them as support for the inner-sphere mechanism hydroxypalladation mechanism. One of the assumptions used to interpret their experimental data was that allyl alcohol oxidation takes place through non-cyclic intermediate routes as in the case of ethene. Here we verify this assumption through ab initio metadynamics simulations of the Wacker oxidation of allyl alcohol in explicit solvent. Importance of our results in interpreting the isotope scrambling experiments is discussed.

  2. Determination of Carbonyl Compounds in Exhaled Cigarette Smoke

    Directory of Open Access Journals (Sweden)

    Moldoveanu S

    2014-12-01

    Full Text Available This paper presents the findings on a quantitative evaluation of carbonyl levels in exhaled cigarette smoke from human subjects. The cigarettes evaluated include products with 5.0 mg ‘tar’, 10.6 mg ‘tar’ and 16.2 mg ‘tar’, where ‘tar’ is defined as the weight of total wet particulate matter (TPM minus the weight of nicotine and water, and the cigarettes are smoked following U.S. Federal Trade Commission (FTC recommendations. The measured levels of carbonyls in the exhaled smoke were compared with calculated yields of carbonyls in the inhaled smoke and a retention efficiency was obtained. The number of human subjects included a total of ten smokers for the 10.6 mg ‘tar’, five for the 16.2 mg ‘tar’, and five for the 5.0 mg ‘tar’ product, each subject smoking three cigarettes. The analyzed carbonyl compounds included several aldehydes (formaldehyde, acetaldehyde, acrolein, propionaldehyde, crotonaldehyde and n-butyraldehyde, and two ketones (acetone and 2-butanone. The smoke collection from the human subjects was vacuum assisted. Exhaled smoke was collected on Cambridge pads pretreated with a solution of dinitrophenylhydrazine (DNPH followed by high performance liquid chromatography (HPLC analysis of the dinitrophenylhydrazones of the carbonyl compounds. The cigarette butts from the smokers were collected and analyzed for nicotine. The nicotine levels for the cigarette butts from the smokers were used to calculate the level of carbonyls in the inhaled smoke, based on calibration curves. These were generated separately by analyzing the carbonyls in smoke and the nicotine in the cigarette butts obtained by machine smoking under different puffing regimes. The comparison of the level of carbonyl compounds in exhaled smoke with that from the inhaled smoke showed high retention of all the carbonyls. The retention of aldehydes was above 95% for all three different ‘tar’ levels cigarettes. The ketones were retained with a

  3. New methodology for removing carbonyl compounds from sweet wines.

    Science.gov (United States)

    Blasi, Mélanie; Barbe, Jean-Christophe; Maillard, Bernard; Dubourdieu, Denis; Deleuze, Hervé

    2007-12-12

    Sweet white wines from botrytized grapes present high SO2 levels because of their high sulfur dioxide binding power. The objective of this work was to develop a new method for reducing this binding power by partially eliminating the carbonyl compounds naturally present in these wines that are responsible for this phenomenon. A selective liquid-solid removal technique was developed. Phenylsulfonylhydrazine was selected as the best candidate for removing carbonyl compounds. Its reactivity in the presence or absence of sulfur dioxide was verified in model media containing acetaldehyde, pyruvic acid, and 2-oxoglutaric acid, some of the main carbonyl compounds responsible for the SO2 binding power of sweet wines. The scavenging function was grafted on porous polymer supports, and its efficiency was evaluated in model wines. Dependent upon the supports used, different quantities of carbonyl compounds (over 90% in some cases) were removed in a few days. The presence of sulfur dioxide delayed removal without changing its quality. The results obtained showed that the method removed carbonyl compounds efficiently and was applicable to wines at any stage in winemaking.

  4. Highly efficient redox isomerisation of allylic alcohols catalysed by pyrazole-based ruthenium(IV) complexes in water: mechanisms of bifunctional catalysis in water.

    Science.gov (United States)

    Bellarosa, Luca; Díez, Josefina; Gimeno, José; Lledós, Agustí; Suárez, Francisco J; Ujaque, Gregori; Vicent, Cristian

    2012-06-18

    The catalytic activity of ruthenium(IV) ([Ru(η(3):η(3)-C(10)H(16))Cl(2)L]; C(10)H(16) = 2,7-dimethylocta-2,6-diene-1,8-diyl, L = pyrazole, 3-methylpyrazole, 3,5-dimethylpyrazole, 3-methyl-5-phenylpyrazole, 2-(1H-pyrazol-3-yl)phenol or indazole) and ruthenium(II) complexes ([Ru(η(6)-arene)Cl(2)(3,5-dimethylpyrazole)]; arene = C(6)H(6), p-cymene or C(6)Me(6)) in the redox isomerisation of allylic alcohols into carbonyl compounds in water is reported. The former show much higher catalytic activity than ruthenium(II) complexes. In particular, a variety of allylic alcohols have been quantitatively isomerised by using [Ru(η(3):η(3)-C(10)H(16))Cl(2)(pyrazole)] as a catalyst; the reactions proceeded faster in water than in THF, and in the absence of base. The isomerisations of monosubstituted alcohols take place rapidly (10-60 min, turn-over frequency = 750-3000 h(-1)) and, in some cases, at 35 °C in 60 min. The nature of the aqueous species formed in water by this complex has been analysed by ESI-MS. To analyse how an aqueous medium can influence the mechanism of the bifunctional catalytic process, DFT calculations (B3LYP) including one or two explicit water molecules and using the polarisable continuum model have been carried out and provide a valuable insight into the role of water on the activity of the bifunctional catalyst. Several mechanisms have been considered and imply the formation of aqua complexes and their deprotonated species generated from [Ru(η(3):η(3)-C(10)H(16))Cl(2)(pyrazole)]. Different competitive pathways based on outer-sphere mechanisms, which imply hydrogen-transfer processes, have been analysed. The overall isomerisation implies two hydrogen-transfer steps from the substrate to the catalyst and subsequent transfer back to the substrate. In addition to the conventional Noyori outer-sphere mechanism, which involves the pyrazolide ligand, a new mechanism with a hydroxopyrazole complex as the active species can be at work in water. The

  5. The magnesium-ene cyclization stereochemically directed by an allylic oxyanionic group and its application to a highly stereoselective synthesis of (+/-)-matatabiether. Allylmagnesium compounds by reductive magnesiation of allyl phenyl sulfides.

    Science.gov (United States)

    Cheng, D; Zhu, S; Yu, Z; Cohen, T

    2001-01-10

    The first example of a magnesium-ene cyclization stereochemically directed by an allylic oxyanionic group is demonstrated by a highly stereoselective synthesis of the bicyclic terpene matatabiether 10. The synthetic method is particularly valuable, not only because of the stereochemical control and the utility of the versatile hydroxyl group introduced into the product, but also because the precursor of the allylmagnesium is an allyl phenyl sulfide, which is more stable and more easily prepared in a connective fashion than the usual allyl halide precursor. Since the presence of lithium ions encourages undesirable proton transfer to the cyclized organometallic and is detrimental to the stereochemical control, the conversion of the allylic thioether to the allylmagnesium utilizes a lithium-free method involving direct reductive magnesiation in the presence of the magnesium-anthracene complex.

  6. Progress of Chiral Schiff Bases with C1 Symmetry in Metal-Catalyzed Asymmetric Reactions.

    Science.gov (United States)

    Hayashi, Masahiko

    2016-12-01

    In this Personal Account, various chiral Schiff base-metal-catalyzed enantioselective organic reactions are reported; the Schiff bases used were O,N,O- as well as N,N,P-tridentate ligands and N,N-bidentate ligands having C1 symmetry. In particular, the enantioselective addition of trimethylsilyl cyanide, dialkylzinc, and organozinc halides to aldehydes, enantioselective 1,4-addition of dialkylzinc to cyclic and acyclic enones, and asymmetric allylic oxidation are reported. Typically, ketimine-type Schiff base-metal complexes exhibited higher reactivity and enantioselectivity compared with the corresponding aldimine-type Schiff base-metal complexes. Notably, remarkable ligand acceleration was observed for all reactions. The obtained products can be used as key intermediates for optically active natural products and pharmaceuticals.

  7. The Palladium-Catalyzed Aerobic Kinetic Resolution of Secondary Alcohols: Reaction Development, Scope, and Applications

    KAUST Repository

    Ebner, Davidâ C.

    2009-12-07

    The first palladium-catalyzed enantioselective oxidation of secondary alcohols has been developed, utilizing the readily available diamine (-)-sparteine as a chiral ligand and molecular oxygen as the stoichiometric oxidant. Mechanistic insights regarding the role of the base and hydrogen-bond donors have resulted in several improvements to the original system. Namely, addition of cesium carbonate and tert-butyl alcohol greatly enhances reaction rates, promoting rapid resolutions. The use of chloroform as solvent allows the use of ambient air as the terminal oxidant at 23 degrees C, resulting in enhanced catalyst selectivity. These improved reaction conditions have permitted the successful kinetic resolution of benzylic, allylic, and cyclopropyl secondary alcohols to high enantiomeric excess with good-to-excellent selectivity factors. This catalyst system has also been applied to the desymmetrization of meso-diols, providing high yields of enantioenriched hydroxyketones.

  8. From the tunneling dimer to the onset of microsolvation: Infrared spectroscopy of allyl radical water aggregates in helium nanodroplets

    Science.gov (United States)

    Leicht, Daniel; Kaufmann, Matin; Pal, Nitish; Schwaab, Gerhard; Havenith, Martina

    2017-03-01

    The infrared spectrum of allyl:water clusters embedded in helium nanodroplets was recorded. Allyl radicals were produced by flash vacuum pyrolysis and trapped in helium droplets. Deuterated water was added to the doped droplets, and the infrared spectrum of the radical water aggregates was recorded in the frequency range 2570-2820 cm-1. Several absorption bands are observed and assigned to 1:1 and 1:2 allyl:D2O clusters, based on pressure dependent measurements and accompanying quantum chemical calculations. The analysis of the 1:1 cluster spectrum revealed a tunneling splitting as well as a combination band. For the 1:2 cluster, we observe a water dimer-like motif that is bound by one π-hydrogen bond to the allyl radical.

  9. Copper-catalyzed oxidative C-O bond formation of 2-acyl phenols and 1,3-dicarbonyl compounds with ethers: direct access to phenol esters and enol esters.

    Science.gov (United States)

    Park, Jihye; Han, Sang Hoon; Sharma, Satyasheel; Han, Sangil; Shin, Youngmi; Mishra, Neeraj Kumar; Kwak, Jong Hwan; Lee, Cheong Hoon; Lee, Jeongmi; Kim, In Su

    2014-05-16

    A copper-catalyzed oxidative coupling of 2-carbonyl-substituted phenols and 1,3-dicarbonyl compounds with a wide range of dibenzyl or dialkyl ethers is described. This protocol provides an efficient preparation of phenol esters and enol esters in good yields with high chemoselectivity. This method represents an alternative protocol for classical esterification reactions.

  10. Isolation determination of garlic allyl sulfides and their antioxidant activity%大蒜烯丙基硫化物的分离鉴定及抗氧化性

    Institute of Scientific and Technical Information of China (English)

    刘玲; 陈琭璐; 张瑶; 白冰; 纪淑娟

    2015-01-01

    through comparing the compounds of SAC, ACSO and GSAC with glutathione (GSH) to evaluate the antioxidation. SAC, ACSO and GSAC were isolated from garlic bulbs using ion-exchange chromatography and pre-HPLC (high performance liquid chromatography). Their molecular structures were identified by high performance liquid chromatography-electrospray ionization-mass/mass spectrometry (HPLC-ESI-MS/MS), proton nuclear magnetic resonance (1H NMR), carbon-13 nuclear magnetic resonance (13C NMR) and specific rotatory power. SAC and ACSO which yielded the expected [M+H]+ of m/z 162.1 and 177.8 by the measurement of mass spectrometry under positive ion mode were conferred asS-allyl-L-cysteine (C6H11O2NS) andS-allyl-L-cysteine sulfoxide (C6H11O3NS) respectively compared with the data of corresponding standard. GSAC, showing the corresponding [M-H]- of m/z 288.8, was identified asγ-glutamyl-S-allyl-L-cysteine (C11H18O5N2S) by HPLC-MS. The1H NMR spectrum of SAC and ACSOindicated the presence of the cysteinyl (δ 2.96 and 3.83, 3H) and (δ 3.26 and 4.13, 3H) moieties. The13C NMR spectrum of compound SAC and ACSO showed the presence of the cysteinyl carboxyl (δ 175.6 andδ 188.0) carbons. Similarly, the1H NMR spectrum of GSAC indicated the presence of the glutamyl (δ 2.32-2.43, 2.66 and 3.46, 5H) and cysteinyl (δ 2.75 and 4.76, 3H) moieties. The13C NMR spectrum of GSACrevealed the presence of 11 magnetically nonequivalent carbon atoms, with three of them being the glutamyl carboxyl, glutamyl carbonyl and cysteinyl carboxyl (δ 182.5, 183.2 and 184.4) carbons. Meanwhile, the scavenging activity of DPPH free radical and the chelating activity of iron ion by allyl-substituted sulfides (SAC, ACSO and GSAC) were determined with reference to cysteine derivative of GSH. The scavenging activity of DPPH free radical had no significant difference between GSH (71.14%) and both of SAC (73.55%) andGSAC (72.68%). Iron ion is one of the main oxidizing auxiliaries which can initiate free radical in

  11. Carbonyl Sulfides as Possible Intermediates in the Photolysis of Oxathiiranes

    DEFF Research Database (Denmark)

    Carlsen, Lars; Snyder, J. P.; Holm, A.

    1981-01-01

    of sulfine to ketone via the oxathiirane and the subsequent blue intermediate implies the absence of triplet and biradical singlet transients. The unknown carbonyl sulfide functionality, R2C&z.dbnd;O&z.dbnd;S, thereby emerges as a strong candidate for producing the visible absorption. Comparison of the wave...... functions for CH2&z.dbnd;S&z.dbnd;O and CH2&z.dbnd;O&z.dbnd;S arising from MNDO limited CI geometry optimizations leads to the conclusion that the carbonyl sulfide structure is best described as a zwitterion rather than as a singlet biradical. The failure to observe cycloaddition products between the blue...

  12. Fe or Fe-NO catalysis? A quantum chemical investigation of the [Fe(CO)3(NO)](-)-catalyzed Cloke-Wilson rearrangement.

    Science.gov (United States)

    Klein, Johannes E M N; Knizia, Gerald; Miehlich, Burkhard; Kästner, Johannes; Plietker, Bernd

    2014-06-10

    A quantum chemical investigation of the Bu4N[Fe(CO)3(NO)]-catalyzed Cloke-Wilson rearrangement of vinyl cyclopropanes is reported. It was found that allylic C-C bond activation can proceed through a SN2' or SN2-type mechanism. The application of the recently reported intrinsic bond orbital (IBO) method for all structures indicated that one Fe-N π bond is directly involved. Further analysis showed that during the reaction oxidation occurs at the NO ligand exclusively.

  13. Ruthenium Hydride/Brønsted Acid-Catalyzed Tandem Isomerization/N-Acyliminium Cyclization Sequence for the Synthesis of Tetrahydro-β-carbolines

    DEFF Research Database (Denmark)

    Hansen, Casper Lykke; Clausen, Janie Regitse Waël; Ohm, Ragnhild Gaard;

    2013-01-01

    This paper describes an efficient tandem sequence for the synthesis of 1,2,3,4-tetrahydro-β-carbolines (THBCs) relying on a ruthenium hydride/Brønsted acid- catalyzed isomerization of allylic amides to N-acyliminium ion intermediates which are trapped by a tethered indolenucleophile. The methodol...... the Suzuki cross-coupling reaction to the isomerization/N-acyliminium cyclization sequence. Finally, diastereo- and enantioselective versions of the title reaction have been examined using substrate control (with dr >15: 1) and asymmetric catalysis (ee up to 57%), respectively...

  14. Chemoenzymatic one-pot synthesis in an aqueous medium: combination of metal-catalysed allylic alcohol isomerisation-asymmetric bioamination.

    Science.gov (United States)

    Ríos-Lombardía, Nicolás; Vidal, Cristian; Cocina, María; Morís, Francisco; García-Álvarez, Joaquín; González-Sabín, Javier

    2015-07-11

    The ruthenium-catalysed isomerisation of allylic alcohols was coupled, for the first time, with asymmetric bioamination in a one-pot process in an aqueous medium. In the cases involving prochiral ketones, the ω-TA exhibited excellent enantioselectivity, identical to that observed in the single step. As a result, amines were obtained from allylic alcohols with high overall yields and excellent enantiomeric excesses.

  15. An alternative method for monitoring carbonyls, and the development of a 24-port fully automated carbonyl sampler for PAMS program

    Energy Technology Data Exchange (ETDEWEB)

    Parmar, S.S.; Ugarova, L. [Atmospheric Analysis and Consulting, Ventura, CA (United States); Fernandes, C.; Guyton, J.; Lee, C.P. [Arizona Dept. of Environmental Quality, Phoenix, AZ (United States)

    1994-12-31

    The authors have investigated the possibility of collecting different aldehydes and ketones on different sorbents such as silica gel, molecular sieve and charcoal followed by solvent extraction, DNPH derivatization and HPLC/UV analysis. Carbonyl collection efficiencies for these sorbents were calculated relative to a DNPH coated C{sub 18} sep-pak cartridge. From a limited number of laboratory experiments, at various concentrations, it appears that silica gel tubes can be used for sampling aldehydes (collection efficiencies {approximately} 1), whereas charcoal tubes are suitable for collecting ketones. Molecular sieve was found to be unsuitable for collecting most of the carbonyl studied. The authors also report the development of a fully automated 24-port carbonyl sampler specially designed for EPA`s PAMS program.

  16. Theoretical Study of the Iodine-catalyzed Nucleophilic Addition by Halogen Bond

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The iodine-catalyzed nucleophilic addition of pyrrole to acetone has been studied by density functional theory at the level of Lanl2DZ*. It has been shown that the first iodine molecule appears to have a remarkable catalytic effect on this reaction by halogen bond between carbonyl oxygen and iodine molecule, but the second one does not improve the reaction largely. In general, the nucleophilic addition at the C(2) site of pyrrole is more favorable than that at the C(3)site;however, this trend is not prominent or even changed in acetronitrile solvent for the indole system, which is consistent with the experimental result by Bandgar.

  17. Iridium‐Catalyzed Condensation of Amines and Vicinal Diols to Substituted Piperazines

    DEFF Research Database (Denmark)

    Lorentz-Petersen, Linda Luise Reeh; Nordstrøm, Lars Ulrik Rubæk; Madsen, Robert

    2012-01-01

    A straightforward procedure is described for the synthesis of piperazines from amines and 1,2‐diols. The heterocyclization is catalyzed by [Cp*IrCl2]2 and sodium hydrogen carbonate and can be achieved with either toluene or water as solvent. The transformation does not require any stoichiometric...... is believed to involve dehydrogenation of the 1,2‐diol to the α‐hydroxy aldehyde, which condenses with the amine to form the α‐hydroxy imine. The latter rearranges to the corresponding α‐amino carbonyl compound, which then reacts with another amine followed by reduction of the resulting imine....

  18. DFT Study on the (S)-Proline-catalyzed Direct Aldol Reaction between Acetone and 4-Nitrobenzaldehyde

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    DFT/6-31G* calculations were applied to study the direct aldol reaction between acetone and 4-nitrobenzaldehyde catalyzed by (S)-proline. Four transition states associated with the stereo-controlling step, corresponding to syn and anti arrangements of methylene moiety related to the carboxylic acid group in enamine intermediate and re and si attacks to the aldehyde carbonyl carbon have been obtained. The solvent effect of DMSO was investigated with polarized continuum model. The computed energies of transition states reveal the stereo-selectivity of the reaction.

  19. A new approach to ferrocene derived alkenes via copper-catalyzed olefination

    Directory of Open Access Journals (Sweden)

    Vasily M. Muzalevskiy

    2015-11-01

    Full Text Available A new approach to ferrocenyl haloalkenes and bis-alkenes was elaborated. The key procedure involves copper catalyzed olefination of N-unsubstituted hydrazones, obtained from ferrocene-containing carbonyl compounds and hydrazine, with polyhaloalkanes. The procedure is simple, cheap and could be applied for the utilization of environmentally harmful polyhalocarbons. The cyclic voltammetry study of the representative examples of the synthesized ferrocenyl alkenes shows the strong dependence of the cathodic behavior on the amount of vinyl groups: while for the monoalkene containing molecules no reduction is seen, the divinyl products are reduced in several steps.

  20. A new approach to ferrocene derived alkenes via copper-catalyzed olefination.

    Science.gov (United States)

    Muzalevskiy, Vasily M; Shastin, Aleksei V; Demidovich, Alexandra D; Shikhaliev, Namiq G; Magerramov, Abel M; Khrustalev, Victor N; Rakhimov, Rustem D; Vatsadze, Sergey Z; Nenajdenko, Valentine G

    2015-01-01

    A new approach to ferrocenyl haloalkenes and bis-alkenes was elaborated. The key procedure involves copper catalyzed olefination of N-unsubstituted hydrazones, obtained from ferrocene-containing carbonyl compounds and hydrazine, with polyhaloalkanes. The procedure is simple, cheap and could be applied for the utilization of environmentally harmful polyhalocarbons. The cyclic voltammetry study of the representative examples of the synthesized ferrocenyl alkenes shows the strong dependence of the cathodic behavior on the amount of vinyl groups: while for the monoalkene containing molecules no reduction is seen, the divinyl products are reduced in several steps.

  1. Evaluation of the Effects of S-Allyl-L-cysteine, S-Methyl-L-cysteine, trans-S-1-Propenyl-L-cysteine, and Their N-Acetylated and S-Oxidized Metabolites on Human CYP Activities.

    Science.gov (United States)

    Amano, Hirotaka; Kazamori, Daichi; Itoh, Kenji

    2016-01-01

    Three major organosulfur compounds of aged garlic extract, S-allyl-L-cysteine (SAC), S-methyl-L-cysteine (SMC), and trans-S-1-propenyl-L-cysteine (S1PC), were examined for their effects on the activities of five major isoforms of human CYP enzymes: CYP1A2, 2C9, 2C19, 2D6, and 3A4. The metabolite formation from probe substrates for the CYP isoforms was examined in human liver microsomes in the presence of organosulfur compounds at 0.01-1 mM by using liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Allicin, a major component of garlic, inhibited CYP1A2 and CYP3A4 activity by 21-45% at 0.03 mM. In contrast, a CYP2C9-catalyzed reaction was enhanced by up to 1.9 times in the presence of allicin at 0.003-0.3 mM. SAC, SMC, and S1PC had no effect on the activities of the five isoforms, except that S1PC inhibited CYP3A4-catalyzed midazolam 1'-hydroxylation by 31% at 1 mM. The N-acetylated metabolites of the three compounds inhibited the activities of several isoforms to a varying degree at 1 mM. N-Acetyl-S-allyl-L-cysteine and N-acetyl-S-methyl-L-cysteine inhibited the reactions catalyzed by CYP2D6 and CYP1A2, by 19 and 26%, respectively, whereas trans-N-acetyl-S-1-propenyl-L-cysteine showed weak to moderate inhibition (19-49%) of CYP1A2, 2C19, 2D6, and 3A4 activities. On the other hand, both the N-acetylated and S-oxidized metabolites of SAC, SMC, and S1PC had little effect on the reactions catalyzed by the five isoforms. These results indicated that SAC, SMC, and S1PC have little potential to cause drug-drug interaction due to CYP inhibition or activation in vivo, as judged by their minimal effects (IC50>1 mM) on the activities of five major isoforms of human CYP in vitro.

  2. Synthesis, characterization and evaluation of antioxidant and anticancer activities of novel benzisoxazole-substituted-allyl derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Anand, Mohanam [Kingston Engineering College, Vellore (India); Selvaraj, Vaithialingam [University College of Engineering-Villupuram, Villupuram (India); Alagar, Muthukaruppan [Anna University, Chennai (India)

    2014-04-15

    A novel series of various 2-allylbenzo[d]isoxazol-3(2H)-ones were synthesized using benzo[d]isoxazol-3(2H)-one treated with different allyl bromides/chlorides in the presence of water-mediated cesium carbonate as a new catalyst 3(a-h). The structures of the newly synthesized Benzisoxazole-substituted-allyl derivatives were characterized by spectroscopic methods and mass spectrometry. These synthesized compounds were evaluated for their in vitro antioxidant and anticancer activity. Compounds 3b, d, f, h were identified as the best hit against HT-29 Human colon cancer cells. Similarly, compounds like 3b, d, f, h showed significant antioxidant activity compared to the standard drug butylated hydroxy toluene (BHT)

  3. Recent Advances in the Application of Chiral Phosphine Ligands in Pd-Catalysed Asymmetric Allylic Alkylation

    Directory of Open Access Journals (Sweden)

    Erika Martin

    2011-01-01

    Full Text Available One of the most powerful approaches for the formation of simple and complex chiral molecules is the metal-catalysed asymmetric allylic alkylation. This reaction has been broadly studied with a great variety of substrates and nucleophiles under different reaction conditions and it has promoted the synthesis of new chiral ligands to be evaluated as asymmetric inductors. Although the mechanism as well as the active species equilibria are known, the performance of the catalytic system depends on the fine tuning of factors such as type of substrate, nucleophile nature, reaction medium, catalytic precursor and type of ligand used. Particularly interesting are chiral phosphines which have proved to be effective asymmetric inductors in several such reactions. The present review covers the application of phosphine-donor ligands in Pd-catalysed asymmetric allylic alkylation in the last decade.

  4. Iron complexes of tetramine ligands catalyse allylic hydroxyamination via a nitroso-ene mechanism.

    Science.gov (United States)

    Porter, David; Poon, Belinda M-L; Rutledge, Peter J

    2015-01-01

    Iron(II) complexes of the tetradentate amines tris(2-pyridylmethyl)amine (TPA) and N,N'-bis(2-pyridylmethyl)-N,N'-dimethylethane-1,2-diamine (BPMEN) are established catalysts of C-O bond formation, oxidising hydrocarbon substrates via hydroxylation, epoxidation and dihydroxylation pathways. Herein we report the capacity of these catalysts to promote C-N bond formation, via allylic amination of alkenes. The combination of N-Boc-hydroxylamine with either FeTPA (1 mol %) or FeBPMEN (10 mol %) converts cyclohexene to the allylic hydroxylamine (tert-butyl cyclohex-2-en-1-yl(hydroxy)carbamate) in moderate yields. Spectroscopic studies and trapping experiments suggest the reaction proceeds via a nitroso-ene mechanism, with involvement of a free N-Boc-nitroso intermediate. Asymmetric induction is not observed using the chiral tetramine ligand (+)-(2R,2'R)-1,1'-bis(2-pyridylmethyl)-2,2'-bipyrrolidine ((R,R')-PDP).

  5. [Surface modification of poly methyl methacrylate intraocular lens by alpha-allyl glucoside].

    Science.gov (United States)

    Qu, Chao; Yao, Ke; Kou, Ruiqiang; Xu, Zhikang

    2004-02-01

    A method for improving the biocompatibility of the intraocular lens (IOL) and reducing the cell attachment was adopted in this study. The alpha-Allyl glucoside was used for the surface modification of the poly methyl methacrylate (PMMA) IOL by way of plasma-induced in situ polymerization. The surfaces of the control and treatment IOLs were characterized by contact angle estimation and ESCA techniques. The resolution, diopter and anti-fatigue of loops were determined by physical and optical methods. Cell attachment on the surfaces was examined by light microscopy. The results indicated that all of the treatment groups had excellent physical and optical properties. The modification with the use of alpha-Allyl glucoside could improve the hydrophilicity of the anterior surface of the PMMA IOLs and reduce the cell attachment.

  6. Epoxidation of allyl alcohol to glycidol over the microporous TS-1 catalyst.

    Science.gov (United States)

    Wróblewska, Agnieszka; Fajdek, Anna

    2010-07-15

    The results of the epoxidation of allyl alcohol with 30% hydrogen peroxide over the TS-1 catalyst have been presented. The studies were carried out under the atmospheric pressure and at the presence of methanol as a solvent. The influence of the following technological parameters on the course of epoxidation was examined: the temperature of 20-60 degrees C, the molar ratio of AA/H(2)O(2) 1:1-5:1, the methanol concentration of 5-90 wt%, the catalyst content of 0.1-5.0 wt% and the reaction time 5-300 min. The main functions describing the process were the selectivity to glycidol in relation to allyl alcohol consumed, the conversion of substrates, and the selectivity of transformation to organic compounds in relation to hydrogen peroxide consumed. The parameters at which the functions describing the process reached the highest values were determined.

  7. Crystal structure of (E-3-allyl-2-sulfanylidene-5-[(thiophen-2-ylmethylidene]thiazolidin-4-one

    Directory of Open Access Journals (Sweden)

    Rahhal El Ajlaoui

    2015-06-01

    Full Text Available Molecules of the title compound, C11H9NOS3, are built up by one thiophene and one 2-thioxathiazolidin-4-one ring which are connected by a methylene bridge. In addition, there is an allyl substituent attached to nitrogen. The two rings are almost coplanar, making a dihedral angle between them of 0.76 (11°. The allyl group is oriented perpendicular to the mean plane through both ring systems. The crystal structure exhibits inversion dimers in which molecules are linked by pairs of C—H...O hydrogen bonds. Additional π–π interactions between neighboring thiophene and 2-thioxathiazolidin-4-one rings [intercentroid distance = 3.694 (2 Å] lead to the formation of a three-dimensional network.

  8. Multiple abiotic stress tolerance in Vigna mungo is altered by overexpression of ALDRXV4 gene via reactive carbonyl detoxification.

    Science.gov (United States)

    Singh, Preeti; Kumar, Deepak; Sarin, Neera Bhalla

    2016-06-01

    Vigna mungo (blackgram) is an important leguminous pulse crop, which is grown for its protein rich edible seeds. Drought and salinity are the major abiotic stresses which adversely affect the growth and productivity of crop plants including blackgram. The ALDRXV4 belongs to the aldo-keto reductase superfamily of enzymes that catalyze the reduction of carbonyl metabolites in the cells and plays an important role in the osmoprotection and detoxification of the reactive carbonyl species. In the present study, we developed transgenic plants of V. mungo using Agrobacterium mediated transformation. The transgene integration was confirmed by Southern blot analysis whereas the expression was confirmed by RT-PCR, Western blot and enzyme activity. The T1 generation transgenic plants displayed improved tolerance to various environmental stresses, including drought, salt, methyl viologen and H2O2 induced oxidative stress. The increased aldose reductase activity, higher sorbitol content and less accumulation of the toxic metabolite, methylglyoxal in the transgenic lines under non-stress and stress (drought and salinity) conditions resulted in increased protection through maintenance of better photosynthetic efficiency, higher relative water content and less photooxidative damage. The accumulation of reactive oxygen species was remarkably decreased in the transgenic lines as compared with the wild type plants. This study of engineering multiple stress tolerance in blackgram, is the first report to date and this strategy for trait improvement is proposed to provide a novel germplasm for blackgram production on marginal lands.

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

    Science.gov (United States)

    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 saliva and plasma protein carbonyls were found to be significantly correlated with age (r = 0.6582 and r = 0.5176, all p saliva and plasma protein carbonyl levels (all p > 0.05). Saliva and plasma protein carbonyls were positively related (r = 0.4405, p 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 saliva protein carbonyls/FRAP ratio and plasma protein carbonyls/FRAP ratio were also correlated (r = 0.5573, p 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.

  10. Synthesis of alkenyl boronates from allyl-substituted aromatics using an olefin cross-metathesis protocol.

    Science.gov (United States)

    Hemelaere, Rémy; Carreaux, François; Carboni, Bertrand

    2013-07-01

    An efficient synthesis of 3-aryl-1-propenyl boronates from pinacol vinyl boronic ester and allyl-substituted aromatics by cross metathesis is reported. Although the allylbenzene derivatives are prone to isomerization reaction under metathesis conditions, we found that some ruthenium catalysts are effective for this methodology. This strategy thus provides an interesting alternative approach to alkyne hydroboration, leading to the preparation of unknown compounds. Moreover, the boron substituent can be replaced by various functional groups in good yields.

  11. α-Carbonyl Radical Cyclizatio n in Organic Synthesis

    Institute of Scientific and Technical Information of China (English)

    SHA Chin-Kang; CHIU Rei-Torng; LIH Shinn-Horng; SANTHOSH K. C.; CHANG Ching-Jung; TSENG Wei-Hong; HO Wen-Yueh

    2001-01-01

    @@ Intramolecular radical cyclization reactions are now used routinely to synthesize carbocyclic and heterocyclic structures. We have reported that α-carbonyl radicals 1, generated from the corresponding iodo ketones or enones, underwent intramolecular radical cyclization smoothly to afford products 2.1, 2,3

  12. Comparing Carbonyl Chemistry in Comprehensive Introductory Organic Chemistry Textbooks

    Science.gov (United States)

    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…

  13. Efficient Nd Promoted Rh Catalysts for Vapor Phase Methanol Carbonylation

    Institute of Scientific and Technical Information of China (English)

    Shu Feng ZHANG; Qing Li QIAN; Ping Lai PAN; Yi CHEN; Guo Qing YUAN

    2005-01-01

    A Nd promoted-Rh catalysts supported on polymer-derived carbon beads for vapor-phase methanol carbonylation was developed. Rh-Nd bimetallic catalysts obviously have higher activity than that of supported Rh catalyst under similar reaction condition. The difference between the activity of above two catalyst systems is clearly caused by the intrinsic properties generated by the introduction of Nd.

  14. Contamination of coal benzol by carbonyl compound impurities

    Energy Technology Data Exchange (ETDEWEB)

    Yakovleva, T.P.

    1985-03-01

    The origin of most carbonyl compounds in nitration-grade benzene produced from coke-oven crude benzole (causing problems in isopropylbenzene production) was concluded to be the piperylene fraction (a by-product of isoprene manufacture) used as an additive in the washing of the benzene with sulphuric acid.

  15. Metal-Diazo Radicals of α-Carbonyl Diazomethanes

    Science.gov (United States)

    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.

  16. Frustrated Lewis pairs-assisted reduction of carbonyl compounds

    DEFF Research Database (Denmark)

    Marek, Ales; Pedersen, Martin Holst Friborg

    2015-01-01

    An alternative and robust method for the reduction of carbonyl groups by frustrated Lewis pairs (FLPs) is reported in this paper. With its very mild reaction conditions, good to excellent yields, absolute regioselectivity and the non-metallic character of the reagent, it provides an excellent tool...

  17. - Wave Spectrum of Carbonyl Diazide in Pursuit of Diazirinone

    Science.gov (United States)

    Amberger, Brent K.; Esselman, Brian J.; Woods, R. Claude; McMahon, Robert J.

    2013-06-01

    Pyrolysis of carbonyl diazide (CO(N_3)_2) has been shown to give diazirinone (CON_2). While diazirione decomposes over the course of a few hours under terrestrial conditions, there is the possibility for it to exist in space. In the pursuit of obtaining a rotational spectrum for diazirinone, we have started with the rotational spectroscopy of its immediate precursor, carbonyl diazide. Carbonyl diazide is highly explosive, and requires careful synthesis. Spectra in the range of 260-360 GHz were collected at room temperature and at -60°C. Ab initio calculations at the CCSD/cc-pVDZ level predict that the conformation where both azide groups are syn to the carbonyl is preferred. A second conformation, where one azide is syn and one is anti, is calculated to lie about 2 kcal/ mol higher in energy. Pure rotational transitions for the ground state and multiple low-lying excited vibrational states of the syn- syn conformation are readily observed and assigned. X. Zeng, H. Beckers, H. Willner and J. F. Stanton, Angew. Chem. Int. Ed. 50 (2011), 1720-1723 A. M. Nolan, B. K. Amberger, B. J. Esselman, V. S. Thimmakondu, J. F. Stanton, R. C. Woods, and R. J. McMahon, Inorg. Chem. 51 (2012), 9846-9851

  18. Plasma protein carbonyl levels and breast cancer risk.

    Science.gov (United States)

    Rossner, Pavel; Terry, Mary Beth; Gammon, Marilie D; Agrawal, Meenakshi; Zhang, Fang Fang; Ferris, Jennifer S; Teitelbaum, Susan L; Eng, Sybil M; Gaudet, Mia M; Neugut, Alfred I; Santella, Regina M

    2007-01-01

    To study the role of oxidative stress in breast cancer risk, we analysed plasma levels of protein carbonyls in 1050 cases and 1107 controls. We found a statistically significant trend in breast cancer risk in relation to increasing quartiles of plasma protein carbonyl levels (OR = 1.2, 95% CI = 0.9-1.5; OR = 1.5, 95% CI = 1.2-2.0; OR = 1.6, 95% CI = 1.2-2.1, for the 2(nd), 3(rd) and 4(th) quartile relative to the lowest quartile, respectively, P for trend = 0.0001). The increase in risk was similar for younger ( or = 15 grams/day for 4(th) quartile versus lowest quartile OR = 2.3, 95% CI = 1.1-4.7), and hormone replacement therapy use (HRT, OR = 2.6, 95% CI = 1.6-4.4 for 4(th) quartile versus lowest quartile). The multiplicative interaction terms were statistically significant only for physical activity and HRT. The positive association between plasma protein carbonyl levels and breast cancer risk was also observed when the analysis was restricted to women who had not received chemotherapy or radiation therapy prior to blood collection. Among controls, oxidized protein levels significantly increased with cigarette smoking and higher fruit and vegetable consumption, and decreased with alcohol consumption >30 grams per day. Women with higher levels of plasma protein carbonyl and urinary 15F(2t)-isoprostane had an 80% increase in breast cancer risk (OR = 1.8, 95% CI = 1.2-2.6) compared to women with levels below the median for both markers of oxidative stress. In summary, our results suggest that increased plasma protein carbonyl levels may be associated with breast cancer risk.

  19. Ferricytochrome (c) directly oxidizes aminoacetone to methylglyoxal, a catabolite accumulated in carbonyl stress.

    Science.gov (United States)

    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.

  20. Optimized biotin-hydrazide enrichment and mass spectrometry analysis of peptide carbonyls

    DEFF Research Database (Denmark)

    Havelund, Jesper F.; Wojdyla, K; Jensen, O. N.;

    Irreversible cell damage through protein carbonylation is the result of reaction with reactive oxygen species (ROS) and has been coupled to many diseases. The precise molecular consequences of protein carbonylation, however, are still not clear. The localization of the carbonylated amino acid is ...

  1. A specific gas chromatographic detector for carbonyl compounds, based on polarography.

    Science.gov (United States)

    Fleet, B; Risby, T H

    1969-07-01

    The evaluation of a specific gas Chromatographie detector for carbonyl compounds is described. This is based on the polarographic reduction of the Girard T hydrazone derivative which is formed when the carbonyl compound is absorbed in a buffered supporting electrolyte containing the carbonyl reagent. The detector was used to monitor the separation of a homologous series of alkanals.

  2. Low pressure carbonylation of benzyl chloride = Die carbonylierung von benzylchlorid bei niedrigen drücken

    NARCIS (Netherlands)

    Luggenhorst, H.J.; Westerterp, K.R.

    1986-01-01

    For carbonylations, metal carbonyls, particularly cobalt and iron carbonyls, are often used as catalysts. These reactions take place under rather drastic reaction conditions, e.g. 200–300 °C and 60–100 MPa. In some patents it is stated that similar reactions using the same catalysts can also be carr

  3. Enzyme-like specificity in zeolites: a unique site position in mordenite for selective carbonylation of methanol and dimethyl ether with CO.

    Science.gov (United States)

    Boronat, Mercedes; Martínez-Sánchez, Cristina; Law, David; Corma, Avelino

    2008-12-03

    The mechanism of methanol carbonylation at different positions of zeolite MOR is investigated by quantum-chemical methods in order to discover which are the active sites that can selectively catalyze the desired reaction. It is shown that when methanol carbonylation competes with hydrocarbon formation, the first reaction occurs preferentially within 8MR channels. However, the unique selectivity for the carbonylation of methanol and dimethyl ether in mordenite is not only due to the size of the 8MR channel: neither process occurs equally at the two T3-O31 and T3-O33 positions. We show that only the T3-O33 positions are selective and that this selectivity is due to the unusual orientation of the methoxy group in relation to the 8MR channel (parallel to the cylinder axis). Only in this situation does the transition state for the attack of CO fit perfectly in the 8MR channel, while the reaction with methanol or DME is sterically impeded. This result explains why T3-O31, while also located in the 8MR channel of mordenite, is not as selective as the T3-O33 position and why ferrierite, although it contains 8MR channels, is less selective than mordenite. The competing effect of water is explained at the molecular level, and the molecular microkinetic reaction model has been established.

  4. Carbonyl compounds in gas and particle phases of mainstream cigarette smoke.

    Science.gov (United States)

    Pang, Xiaobing; Lewis, Alastair C

    2011-11-01

    Carbonyl compounds (carbonyls) are important constituents of cigarette smoke and some are toxic and may be carcinogenic or mutagenic to humans. In this study carbonyl emissions in the gas and particle phases of mainstream cigarette smoke were assessed by GC-MS with pentafluorophenyl hydrazine (PFPH) derivatization. Seven brands of cigarettes and one brand of cigar common in the UK market and having differing nicotine, tar and carbon monoxide yields were investigated. Sixteen carbonyl components were identified in gaseous emissions and twenty in the particle phase. In the gaseous emissions, acetaldehyde presented as the predominant species, followed by formaldehyde, 2-propenal, and pentanal. In the particulate emissions, 1-hydroxy-2-propanone was the most abundant followed by formaldehyde, benzaldehyde, and 2,5-dimethylbenzaldehyde. Significant differences were found in carbonyl emissions among the brands of cigarettes. The gaseous carbonyl emissions varied in the range of 216-405 μg cigarette(-1) (μg cig(-1)) and the particulate carbonyl emissions varied in the range of 23-127 μg cig(-1). Positive correlations were found between the total emission of carbonyls, tar yield and carbon monoxide yield. Similar gas/particle (G/P) partitioning ratios of carbonyls were found among all cigarettes, which implies that G/P partitions of carbonyls in smoke mainly depend on the physical properties of the carbonyls. The gaseous carbonyl emissions were enhanced by 40% to 130% when some of the water, accounting for 8-12% of cigarettes in mass, was removed from the tobacco. Non-filtered cigarettes showed significantly higher carbonyl emissions compared to their filtered equivalents. Carbonyl particulate accounted for 11-19% by mass of total particulate matter from tobacco smoke. The cigar generated 806 μg cig(-1) gaseous and 141 μg cig(-1) particulate carbonyls, which is 2-4 times greater than the cigarettes.

  5. Carbonyl Alkyl Nitrates as Trace Constituents in Urban Air

    Science.gov (United States)

    Woidich, S.; Gruenert, A.; Ballschmiter, K.

    2003-04-01

    Organic nitrates, esters of nitric acid, significantly contribute to the entire pool of odd nitrogen (NOY) in the atmosphere. Organic nitrates are formed in NO rich air by degradation of alkanes and alkenes initiated by OH and NO3 radicals during daytime and nighttime, respectively. Bifunctional organonitrates like the alkyl dinitrates and hydroxy alkyl nitrates are formed primarily from alkenes. The two main sources for Alkenes are traffic emissions and naturally occurring terpenes. So far a broad spectrum of alkyl dinitrates and hydroxy alkyl nitrates including six different isoprene nitrates has been identified in urban and marine air (1-3). We report here for the first time about the group of C4 C7 carbonyl alkyl nitrates as trace constituents in urban air collected on the campus of the University of Ulm Germany, and in the downtown area of Salt Lake City, Utah. Air sampling was done by high volume sampling (flow rate 25 m3/h) using a layer of 100 g silica gel (particle diameter 0.2 - 0.5 mm) as adsorbent. The organic nitrates were eluted from the silica gel by pentane/acetone (4:1, w/w) and the extract was concentrated to a volume of 500 µL for a group separation using normal phase HPLC. Final analysis was performed by high resolution capillary gas chromatography with electron capture detection as well as by mass selective detection in the (CH4)NCI mode using NO2- = m/e 46 as the indicator mass. The carbonyl alkyl nitrates were identified by self synthesized reference standards . So far we have identified eight non-branched a-carbonyl alkyl nitrates (vicinal carbonyl alkyl nitrates), two b-carbonyl alkyl nitrates and one g-carbonyl alkyl nitrate with carbon chains ranging from C4 to C7. The mixing ratios are between 0.05 and 0.30 ppt(v) for daytime samples and are two to three times higher for samples taken at night. (1) M. Schneider, O. Luxenhofer, Angela Deißler, K. Ballschmiter: 2C1-C15 Alkyl Nitrates, Benzyl Nitrate, and Bifunctional Nitrates

  6. Cross-linking proteins by laccase-catalyzed oxidation: importance relative to other modifications.

    Science.gov (United States)

    Steffensen, Charlotte L; Andersen, Mogens L; Degn, Peter E; Nielsen, Jacob H

    2008-12-24

    Laccase-catalyzed oxidation was able to induce intermolecular cross-links in beta-lactoglobulin, and ferulic acid-mediated laccase-catalyzed oxidation was able to induce intermolecular cross-links in alpha-casein, whereas transglutaminase cross-linked only alpha-casein. In addition, different patterns of laccase-induced oxidative modifications were detected, including dityrosine formation, formation of fluorescent tryptophan oxidation products, and carbonyls derived from histidine, tryptophan, and methionine. Laccase-catalyzed oxidation as well as transglutaminase induced only minor changes in surface tension of the proteins, and the changes could not be correlated to protein cross-linking. The presence of ferulic acid was found to influence the effect of laccase, allowing laccase to form irreducible intermolecular cross-links in beta-lactoglobulin and resulting in proteins exercising higher surface tensions due to cross-linking as well as other oxidative modifications. The outcome of using ferulic acid-mediated laccase-catalyzed oxidation to modify the functional properties of proteinaceous food components or other biosystems is expected to be highly dependent on the protein composition, resulting in different changes of the functional properties.

  7. Chemical Kinetics of Hydrogen Atom Abstraction from Allylic Sites by (3)O2; Implications for Combustion Modeling and Simulation.

    Science.gov (United States)

    Zhou, Chong-Wen; Simmie, John M; Somers, Kieran P; Goldsmith, C Franklin; Curran, Henry J

    2017-03-09

    Hydrogen atom abstraction from allylic C-H bonds by molecular oxygen plays a very important role in determining the reactivity of fuel molecules having allylic hydrogen atoms. Rate constants for hydrogen atom abstraction by molecular oxygen from molecules with allylic sites have been calculated. A series of molecules with primary, secondary, tertiary, and super secondary allylic hydrogen atoms of alkene, furan, and alkylbenzene families are taken into consideration. Those molecules include propene, 2-butene, isobutene, 2-methylfuran, and toluene containing the primary allylic hydrogen atom; 1-butene, 1-pentene, 2-ethylfuran, ethylbenzene, and n-propylbenzene containing the secondary allylic hydrogen atom; 3-methyl-1-butene, 2-isopropylfuran, and isopropylbenzene containing tertiary allylic hydrogen atom; and 1-4-pentadiene containing super allylic secondary hydrogen atoms. The M06-2X/6-311++G(d,p) level of theory was used to optimize the geometries of all of the reactants, transition states, products and also the hinder rotation treatments for lower frequency modes. The G4 level of theory was used to calculate the electronic single point energies for those species to determine the 0 K barriers to reaction. Conventional transition state theory with Eckart tunnelling corrections was used to calculate the rate constants. The comparison between our calculated rate constants with the available experimental results from the literature shows good agreement for the reactions of propene and isobutene with molecular oxygen. The rate constant for toluene with O2 is about an order magnitude slower than that experimentally derived from a comprehensive model proposed by Oehlschlaeger and coauthors. The results clearly indicate the need for a more detailed investigation of the combustion kinetics of toluene oxidation and its key pyrolysis and oxidation intermediates. Despite this, our computed barriers and rate constants retain an important internal consistency. Rate constants

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

    Science.gov (United States)

    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%.

  9. Genome wide association mapping in Arabidopsis thaliana identifies novel genes involved in linking allyl glucosinolate to altered biomass and defense

    Directory of Open Access Journals (Sweden)

    Marta Francisco

    2016-07-01

    Full Text Available A key limitation in modern biology is the ability to rapidly identify genes underlying newly identified complex phenotypes. Genome wide association studies (GWAS have become an increasingly important approach for dissecting natural variation by associating phenotypes with genotypes at a genome wide level. Recent work is showing that the Arabidopsis thaliana defense metabolite, allyl glucosinolate (GSL, may provide direct feedback regulation, linking defense metabolism outputs to the growth and defense responses of the plant. However, there is still a need to identify genes that underlie this process. To start developing a deeper understanding of the mechanism(s that modulate the ability of exogenous allyl GSL to alter growth and defense, we measured changes in plant biomass and defense metabolites in a collection of natural 96 A. thaliana accessions fed with 50 µM of allyl GSL. Exogenous allyl GSL was introduced exclusively to the roots and the compound transported to the leaf leading to a wide range of heritable effects upon plant biomass and endogenous GSL accumulation. Using natural variation we conducted GWAS to identify a number of new genes which potentially control allyl responses in various plant processes. This is one of the first instances in which this approach has been successfully utilized to begin dissecting a novel phenotype to the underlying molecular/polygenic basis.

  10. Metal Carbonyl-Hydrosilane Reactions and Hydrosilation Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    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.

  12. Emissions of Toxic Carbonyls in an Electronic Cigarette

    Directory of Open Access Journals (Sweden)

    Guthery William

    2016-01-01

    Full Text Available Electronic cigarettes (e-cigs provide a smoke-free alternative for inhalation of nicotine without the vast array of toxic and carcinogenic combustion products produced by tobacco smoke. Elevated levels of toxic carbonyls may be generated during vaporisation; however, it is unclear whether that is indicative of a fault with the device or is due to the applied conditions of the test. A device, designed and built at this facility, was tested to determine the levels of selected toxic carbonyls. The reservoir was filled with approximately 960 mg of an e-liquid formulation containing 1.8% (w/v nicotine. Devices were puffed 200 times in blocks of 40 using a standardised regime consisting of a 55 mL puff volume; 3 s puff duration; 30 s puff interval; square wave puff profile. Confirmatory testing for nicotine and total aerosol delivery resulted in mean (n = 8 values of 10 mg (RSD 12.3% and 716 mg (RSD 11.2%, respectively. Emissions of toxic carbonyls were highly variable yet were between < 0.1% and 22.9% of expected levels from a Kentucky Reference Cigarette (K3R4F puffed 200 times under Health Canada Intense smoking conditions. It has been shown that a device built to a high specification with relatively consistent nicotine and aerosol delivery emits inconsistent levels of carbonyls. The exposure is greatly reduced when compared with lit tobacco products. However, it was observed that as the reservoirs neared depletion then emission levels were significantly higher

  13. Resonance energies of the allyl cation and allyl anion: contribution by resonance and inductive effects toward the acidity and hydride abstraction enthalpy of propene.

    Science.gov (United States)

    Barbour, Josiah B; Karty, Joel M

    2004-02-06

    Density functional theory was employed to calculate the acidities and hydride abstraction enthalpies of propene (3) and propane (4), along with their vinylogues (5 and 6, respectively). The same reaction enthalpies were calculated for the propene vinylogues in which the terminal vinyl group was rotated perpendicular to the rest of the conjugated system (7). The contribution by resonance and inductive effects toward the acidity and hydride abstraction enthalpy of each vinylogue of 5 (n = 1-3) was computed and extrapolated to n = 0 (the parent propene system). The resonance energies of the allyl cation and anion were determined to be about 20-22 and 17-18 kcal/mol, respectively. Comparisons are made to resonance energies calculated using other methodologies.

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

    Science.gov (United States)

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

    2016-04-27

    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.

  15. Carbonylation of Ethene Catalysed by Pd(II-Phosphine Complexes

    Directory of Open Access Journals (Sweden)

    Gianni Cavinato

    2014-09-01

    Full Text Available This review deals with olefin carbonylation catalysed by Pd(II-phosphine complexes in protic solvents. In particular, the results obtained in the carbonylation with ethene are reviewed. After a short description of the basic concepts relevant to this catalysis, the review treats in greater details the influence of the bite angle, skeletal rigidity, electronic and steric bulk properties of the ligand on the formation of the products, which range from high molecular weight perfectly alternating polyketones to methyl propanoate. It is shown that the steric bulk plays a major role in directing the selectivity. Particular emphasis is given to the factors governing the very active and selective catalysis to methyl propanoate, including the mechanism of the catalytic cycles with diphosphine- and monophosphine-catalysts. A brief note on the synthesis of methyl propanoate using a “Lucite” type catalyst in ionic liquids is also illustrated. A chapter is dedicated to the carbonylation of olefins in aqueous reaction media. The nonalternating CO-ethene copolymerization is also treated.

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

    Science.gov (United States)

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

    2016-05-01

    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.

  17. Iron- and indium-catalyzed reactions toward nitrogen- and oxygen-containing saturated heterocycles.

    Science.gov (United States)

    Cornil, Johan; Gonnard, Laurine; Bensoussan, Charlélie; Serra-Muns, Anna; Gnamm, Christian; Commandeur, Claude; Commandeur, Malgorzata; Reymond, Sébastien; Guérinot, Amandine; Cossy, Janine

    2015-03-17

    A myriad of natural and/or biologically active products include nitrogen- and oxygen-containing saturated heterocycles, which are thus considered as attractive scaffolds in the drug discovery process. As a consequence, a wide range of reactions has been developed for the construction of these frameworks, much effort being specially devoted to the formation of substituted tetrahydropyrans and piperidines. Among the existing methods to form these heterocycles, the metal-catalyzed heterocyclization of amino- or hydroxy-allylic alcohol derivatives has emerged as a powerful and stereoselective strategy that is particularly interesting in terms of both atom-economy and ecocompatibility. For a long time, palladium catalysts have widely dominated this area either in Tsuji-Trost reactions [Pd(0)] or in an electrophilic activation process [Pd(II)]. More recently, gold-catalyzed formation of saturated N- and O-heterocycles has received growing attention because it generally exhibits high efficiency and diastereoselectivity. Despite their demonstrated utility, Pd- and Au-complexes suffer from high costs, toxicity, and limited natural abundance, which can be barriers to their widespread use in industrial processes. Thus, the replacement of precious metals with less expensive and more environmentally benign catalysts has become a challenging issue for organic chemists. In 2010, our group took advantage of the ability of the low-toxicity and inexpensive FeCl3 in activating allylic or benzylic alcohols to develop iron-catalyzed N- and O-heterocylizations. We first focused on N-heterocycles, and a variety of 2,6-disubstituted piperidines as well as pyrrolidines were synthesized in a highly diastereoselective fashion in favor of the cis-compounds. The reaction was further extended to the construction of substituted tetrahydropyrans. Besides triggering the formation of heterocycles, the iron salts were shown to induce a thermodynamic epimerization, which is the key to reach the high

  18. S-Allyl cysteine improves nonalcoholic fatty liver disease in type 2 diabetes Otsuka Long-Evans Tokushima Fatty rats via regulation of hepatic lipogenesis and glucose metabolism.

    Science.gov (United States)

    Takemura, Shigekazu; Minamiyama, Yukiko; Kodai, Shintaro; Shinkawa, Hiroji; Tsukioka, Takuma; Okada, Shigeru; Azuma, Hideki; Kubo, Shoji

    2013-09-01

    It is important to prevent and improve diabetes mellitus and its complications in a safe and low-cost manner. S-Allyl cysteine, an aged garlic extract with antioxidant activity, was investigated to determine whether S-allyl cysteine can improve type 2 diabetes in Otsuka Long-Evans Tokushima Fatty rats with nonalcoholic fatty liver disease. Male Otsuka Long-Evans Tokushima Fatty rats and age-matched Long-Evans Tokushima Otsuka rats were used and were divided into two groups at 29 weeks of age. S-Allyl cysteine (0.45% diet) was administered to rats for 13 weeks. Rats were killed at 43 weeks of age, and detailed analyses were performed. S-Allyl cysteine improved hemoglobinA1c, blood glucose, triglyceride, and low-density lipoprotein cholesterol levels. Furthermore, S-allyl cysteine normalized plasma insulin levels. S-Allyl cysteine activated the mRNA and protein expression of both peroxisome proliferator-activated receptor α and γ, as well as inhibiting pyruvate dehydrogenase kinase 4 in Otsuka Long-Evans Tokushima Fatty rat liver. Sterol regulatory element-binding protein 1c and forkhead box O1 proteins were normalized by S-allyl cysteine in Otsuka Long-Evans Tokushima Fatty rat liver. In conclusions, these findings support the hypothesis that S-allyl cysteine has diabetic and nonalcoholic fatty liver disease therapeutic potential as a potent regulating agent against lipogenesis and glucose metabolism.

  19. Thermosetting composite matrix materials based on allyl and/or propargyl substituted cyclopentadiene, indene and fluorene

    Science.gov (United States)

    Tregre, Gregory Jude

    A series of all-hydrocarbon thermoset composite matrix resins was synthesized via electrophilic substitution of cyclopentadiene, indene, and fluorene ring systems with allyl and/or propargyl halides under phase transfer conditions. Reaction of cyclopentadiene with allyl chloride (ACP resin), propargyl bromide (PCP resin) or various feed ratios of allyl chloride and propargyl bromide (APCP resins) yielded mixtures of products with 2-6 substituents per cyclopentadiene ring. Reaction of indene with allyl chloride (Al resins) or propargyl bromide (PI resins) yielded mixtures of products with 2-4 substituents per indene. In both sets of resins the allyl functionality obtained a greater average degree of substitution than the analogous propargyl species. Differential scanning calorimetric (DSC) analysis of the multifunctional resins showed broad, high-energy thermal cures in all cases. The enthalpies of cure for ACP and PCP were 750 J/g and 805 J/g, respectively, with peak cure energies occurring at 310 and 248sp°C. The enthalpy of cure for APCP resins ranged from 750 J/g to 800 J/g with higher propargyl-functional resins yielding higher enthalpies of cure. Physically mixed ACP/PCP resin systems gave peak cure temperatures and energy values comparable to APCP resins. The enthalpies of cure for Al and PI-resins were 480 J/g and 630 J/g, respectively. Peak cure temperature for Al resin was 320sp°C, while the peak cure for PI resin occurred at 282sp°C. Infrared spectroscopy (IR) and nuclear magnetic resonance spectroscopy (NMR) were used to evaluate mechanisms of cure in the experimental resins. The allyl functional resins cured through a combination of ene reactions and polyaddition reactions. The propargyl functional resins cured through ene reactions and polyadditions but also underwent some cyclotrimerization of the propargyl functionalities. A small amount of autoxidation was seen in all of the resins. Thermal stability and carbon yields of the cured resins were

  20. Beads,Necklaces, Chains and Strings in Capping Carbonyl Clusters

    Directory of Open Access Journals (Sweden)

    Enos Masheija Kiremire

    2015-09-01

    Full Text Available The paper attempts to explain at length the close relationship between transition metal carbonyl clusters with main group clusters especially the boranes using the 14n and 4n rules. When the ‘shielding’ electrons are removed from a transition metal carbonyl cluster and becomes ‘naked’, it resembles a corresponding one in the main group elements. A an expanded table of osmium carbonyl clusters was constructed using the capping fragment Os(CO2(14n-2 and the fragment Os(CO3 (14n+0. The table reveals the fact that the known series such closo, nido and arachno are part and parcel of a wide range of series especially the capping series 14n+q, where q takes up negative multiple integers of two including 0 such as such = 0, -2,-4, -6, and so on. The linkage between capping series in transition metal carbonyl clusters has also been identified. Apart from the capping series generated in the table, there is another type of series where the skeletal cluster elements remained the same but the number of carbonyl ligands successively decreased. These types of series are referred to as stripping series. Mapping generating functions were also derived which produces any cluster formula or series required. Also the table shows that many clusters form utilizing some of its atoms as closo nucleus around which the larger ones are built and thus forming clusters within larger clusters. The table may be used to categorize a given cluster formula that falls within its range. Otherwise, using the 14n rule or 4n rule can be used for cluster classification. Furthermore, the table indicated that atoms, fragments and molecules can be classified into series. Through this approach of using series, Hoffmann’s important isolobal relationship of chemical species can splendidly be explained.Using the 14n rule and 4n rules creates a framework under which chemical species such as atoms, fragments, molecules and ions some of which may appear unrelated from main group

  1. Chirality Transfer in Gold(I)-Catalysed Direct Allylic Etherifications of Unactivated Alcohols: Experimental and Computational Study.

    Science.gov (United States)

    Barker, Graeme; Johnson, David G; Young, Paul C; Macgregor, Stuart A; Lee, Ai-Lan

    2015-09-21

    Gold(I)-catalysed direct allylic etherifications have been successfully carried out with chirality transfer to yield enantioenriched, γ-substituted secondary allylic ethers. Our investigations include a full substrate-scope screen to ascertain substituent effects on the regioselectivity, stereoselectivity and efficiency of chirality transfer, as well as control experiments to elucidate the mechanistic subtleties of the chirality-transfer process. Crucially, addition of molecular sieves was found to be necessary to ensure efficient and general chirality transfer. Computational studies suggest that the efficiency of chirality transfer is linked to the aggregation of the alcohol nucleophile around the reactive π-bound Au-allylic ether complex. With a single alcohol nucleophile, a high degree of chirality transfer is predicted. However, if three alcohols are present, alternative proton transfer chain mechanisms that erode the efficiency of chirality transfer become competitive.

  2. Study on the Preparation of Allyl-modified Starch in Isopropyl/Water Medium for Warp Sizing

    Institute of Scientific and Technical Information of China (English)

    LI Man-li; ZHU Zhi-feng; ZHANG Long-qiu

    2008-01-01

    A new method for the pretreatment of starch by etherification was developed to eliminate the problems of lower grafting efficiency associated with the preparation of starch graft copolymers as warp sizing agents.The etherification of starch with allyl chloride was investigated in order to effectively enhance the reaction efficiency.The technological variables of the reaction considered for evaluating the etherification included sodium hydroxide amount,water content in water-isopropyi alcohol medium,allyl cldoride concentration,reaction temperature and reaction time.The experimental result demonstrated that the variables considered showed evident effect on the reaction efficiency.For the etherification,a condition of 20% for the water content,1.5:1 for the molar ratio of sodium hydroxide to allyl chloride.and at 30℃ under 24h reaction is Sufficient to retain the reaction efficiency above 50%.Furthermore,a contrast test demonstrated that the graft efficiency can be increased with the etherification pretreatment.

  3. Carbonyl compounds in gas and particle phases of mainstream cigarette smoke

    Energy Technology Data Exchange (ETDEWEB)

    Pang, Xiaobing, E-mail: pangxbyuanj@gmail.com [Department of Chemistry, University of York, Heslington, York, YO10 5DD (United Kingdom); Lewis, Alastair C., E-mail: ally.lewis@york.ac.uk [National Centre for Atmospheric Science, University of York, Heslington, York, YO10 5DD (United Kingdom)

    2011-11-01

    Carbonyl compounds (carbonyls) are important constituents of cigarette smoke and some are toxic and may be carcinogenic or mutagenic to humans. In this study carbonyl emissions in the gas and particle phases of mainstream cigarette smoke were assessed by GC-MS with pentafluorophenyl hydrazine (PFPH) derivatization. Seven brands of cigarettes and one brand of cigar common in the UK market and having differing nicotine, tar and carbon monoxide yields were investigated. Sixteen carbonyl components were identified in gaseous emissions and twenty in the particle phase. In the gaseous emissions, acetaldehyde presented as the predominant species, followed by formaldehyde, 2-propenal, and pentanal. In the particulate emissions, 1-hydroxy-2-propanone was the most abundant followed by formaldehyde, benzaldehyde, and 2,5-dimethylbenzaldehyde. Significant differences were found in carbonyl emissions among the brands of cigarettes. The gaseous carbonyl emissions varied in the range of 216-405 {mu}g cigarette{sup -1} ({mu}g cig{sup -1}) and the particulate carbonyl emissions varied in the range of 23-127 {mu}g cig{sup -1}. Positive correlations were found between the total emission of carbonyls, tar yield and carbon monoxide yield. Similar gas/particle (G/P) partitioning ratios of carbonyls were found among all cigarettes, which implies that G/P partitions of carbonyls in smoke mainly depend on the physical properties of the carbonyls. The gaseous carbonyl emissions were enhanced by 40% to 130% when some of the water, accounting for 8-12% of cigarettes in mass, was removed from the tobacco. Non-filtered cigarettes showed significantly higher carbonyl emissions compared to their filtered equivalents. Carbonyl particulate accounted for 11-19% by mass of total particulate matter from tobacco smoke. The cigar generated 806 {mu}g cig{sup -1} gaseous and 141 {mu}g cig{sup -1} particulate carbonyls, which is 2-4 times greater than the cigarettes. - Highlights: {yields} Carbonyl

  4. Non-thermal plasma destruction of allyl alcohol in waste gas: kinetics and modelling

    Science.gov (United States)

    DeVisscher, A.; Dewulf, J.; Van Durme, J.; Leys, C.; Morent, R.; Van Langenhove, H.

    2008-02-01

    Non-thermal plasma treatment is a promising technique for the destruction of volatile organic compounds in waste gas. A relatively unexplored technique is the atmospheric negative dc multi-pin-to-plate glow discharge. This paper reports experimental results of allyl alcohol degradation and ozone production in this type of plasma. A new model was developed to describe these processes quantitatively. The model contains a detailed chemical degradation scheme, and describes the physics of the plasma by assuming that the fraction of electrons that takes part in chemical reactions is an exponential function of the reduced field. The model captured the experimental kinetic data to less than 2 ppm standard deviation.

  5. Direct asymmetric allylic alkenylation of N-itaconimides with Morita-Baylis-Hillman carbonates

    KAUST Repository

    Yang, Wenguo

    2012-08-03

    The asymmetric allylic alkenylation of Morita-Baylis-Hillman (MBH) carbonates with N-itaconimides as nucleophiles has been developed using a commercially available Cinchona alkaloid catalyst. A variety of multifunctional chiral α-methylene-β-maleimide esters were attained in moderate to excellent yields (up to 99%) and good to excellent enantioselectivities (up to 91% ee). The origin of the regio- and stereoselectivity was verified by DFT methods. Calculated geometries and relative energies of various transition states strongly support the observed regio- and enantioselectivity. © 2012 American Chemical Society.

  6. Lanthanum triflate triggered synthesis of tetrahydroquinazolinone derivatives of N-allyl quinolone and their biological assessment

    Directory of Open Access Journals (Sweden)

    Jardosh Hardik H.

    2012-01-01

    Full Text Available A series of 24 derivatives of tetrahydroquinazolinone has been synthesized by one-pot cyclocondensation reaction of N-allyl quinolones, cyclic β-diketones and (thiourea/N-phenylthiourea in presence of lanthanum triflate catalyst. This methodology allowed us to achieve the products in excellent yield by stirring at room temperature. All the synthesized compounds were investigated against a representative panel of pathogenic strains using broth microdilution MIC (minimum inhibitory concentration method for their in vitro antimicrobial activity. Amongst these sets of heterocyclic compounds 5h, 6b, 6h, 5f, 5l, 5n and 6g found to have admirable activity.

  7. N-(2-Allyl-4-ethoxy-2H-indazol-5-yl-4-methylbenzenesulfonamide

    Directory of Open Access Journals (Sweden)

    Hakima Chicha

    2014-05-01

    Full Text Available The indazole ring system of the title compound, C19H21N3O3S, is almost planar (r.m.s. deviation = 0.0192 Å and forms dihedral angles of 77.99 (15 and 83.9 (3° with the benzene ring and allyl group, respectively. In the crystal, centrosymmetrically related molecules are connected by pairs of N—H...O hydrogen bonds into dimers, which are further linked by C—H...O hydrogen bonds, forming columns parallel to the b axis.

  8. Thermophysical properties and reaction kinetics of γ-irradiated poly allyl diglycol carbonates nuclear track detector

    Science.gov (United States)

    Elmaghraby, Elsayed K.; Seddik, Usama

    2015-07-01

    Kinetic thermogravimetric technique was used to study the effect of gamma irradiation on the poly allyl diglycol carbonates (PADC) within the dose range from 50 to ? Gy. The approach of Coats-Redfern was used to analyze the data. Results showed that low doses around 50 Gy make the polymer slightly more resistive to heat treatment. Higher radiation doses cause severe effects in the samples accompanied by the formation of lower molecular mass species and consequent crosslinking. Results support the domination of re-polymerization and crosslinking for the γ radiation interaction PADC at dose below about ? Gy, while the situation is inverted above ? Gy in which chain secession dominates.

  9. Synthesis of Aryl Allyl Ether in the Recyclable Ionic Liquid [bmim]PF6

    Institute of Scientific and Technical Information of China (English)

    Zhou Mei-Yun; Li Yi-Qun; Xu Xin-Ming

    2004-01-01

    Ionic liquids, especially imidazonium salts, have recently gained recognition as possible environmentally benign alternative chemical process solvents. This is mainly due to their nonvolatile nature, insolubility in some solvents as well as their ability to dissolve a wide range of organic and inorganic materials, allowing the ionic liquids easy recovery and recycling. Examples of their application in organic reactions have been summarized in a number of recent review articles.1Aryl allyl ether is very useful intermediate in organic synthesis. The Williamson reaction is a well knows method for the preparation ethers. However, the reaction of alkylating agents with the phenoxide ions was conventionally carried out in the organic solvents. The usual solvents for this type of reaction are DCM, 2 DMSO, 3 DMF, 4 CH3CN5 etc. With the current desire to avoid the use of organic molecular solvents in organic synthesis, we decide to investigate the use of the ionic liquid for the alternative solvent for the Williamson reaction to prepare the aryl allyl ethers. The ionic liquid employed here was the moisture stable 1-butyl-3-methylimidazolium hexafluorophosphate [bmim]PF6.6 The ionic liquid is non-volatile, thermally stable, and depending on the anion, can present low immiscible with water,alkanes and dialky ethers. We have now found that aryl allyl ethers can have been obtained from various phenols and allyl bromide in the presence of potassium hydroxide in [bmim]PF6 as a replacement for classical organic solvents in the ambient temperature. The results are shown in Scheme 1.The reaction were carried out by simple mixing the phenolwith the ally bromide and potassium hydroxide in [bmim]PF6 and stirred at room temperature for 4h. The results are summarized in Table 1.In conclusion, Williamson reaction can be successfully conducted in ionic liquid [bmim]PF6 with a number of advantages: the procedure is simple, the reaction condition is mild and the yields are excellent

  10. N-(1-Allyl-3-chloro-4-ethoxy-1H-indazol-5-yl-4-methylbenzenesulfonamide

    Directory of Open Access Journals (Sweden)

    Hakima Chicha

    2014-06-01

    Full Text Available In the title compound, C19H20ClN3O3S, the benzene ring is inclined to the indazole ring system by 51.23 (8°. In the crystal, molecules are linked by pairs of N—H...O hydrogen bonds, forming inversion dimers which stack in columns parallel to [011]. The atoms in the allyl group are disordered over two sets of sites with an occupancy ratio of 0.624 (8:0.376 (8.

  11. [3,3]-sigmatropic rearrangements of fluorinated allyl (Thio)cyanates - a tool for the synthesis of fluorinated (Thio)ureas.

    Science.gov (United States)

    Ramb, Daniel C; Kost, Lisa; Haufe, Günter

    2014-01-01

    The first (thio)cyanate to iso(thio)cyanate rearrangements based on 2-fluoroallylic alcohols are presented. Long-chain 2-fluoroallylic alcohols were converted to corresponding N-unsubstituted carbamates by treatment with trichloroacetyl isocyanate. Dehydration using trifluoroacetic anhydride in the presence of triethylamine formed intermediate allylic cyanates, which immediately underwent sigmatropic rearrangement to fluorinated allyl isocyanates. Without isolation the latter delivered fluorinated ureas by addition of amines. The thiocyanate to isothiocyanate rearrangements started from the same fluorinated allylic alcohols, which were first converted to mesylates. Heating in THF with potassium thiocyanate led to fluorinated allyl isothiocyanates, via [3,3]-sigmatropic rearrangement of intermediate allyl thiocyanates. The formed products were further reacted with amines to fluorinated thioureas.

  12. Determination of Carbonyl Functional Groups in Bio-oils by Potentiometric Titration: The Faix Method

    Energy Technology Data Exchange (ETDEWEB)

    Black, Stuart; Ferrell, Jack R.

    2017-01-01

    Carbonyl compounds present in bio-oils are known to be responsible for bio-oil property changes upon storage and during upgrading. Specifically, carbonyls cause an increase in viscosity (often referred to as 'aging') during storage of bio-oils. As such, carbonyl content has previously been used as a method of tracking bio-oil aging and condensation reactions with less variability than viscosity measurements. Additionally, carbonyls are also responsible for coke formation in bio-oil upgrading processes. Given the importance of carbonyls in bio-oils, accurate analytical methods for their quantification are very important for the bio-oil community. Potentiometric titration methods based on carbonyl oximation have long been used for the determination of carbonyl content in pyrolysis bio-oils. Here, we present a modification of the traditional carbonyl oximation procedures that results in less reaction time, smaller sample size, higher precision, and more accurate carbonyl determinations. While traditional carbonyl oximation methods occur at room temperature, the Faix method presented here occurs at an elevated temperature of 80 degrees C.

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

    Science.gov (United States)

    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.

  14. Indoor carbonyl compounds in an academic building in Beijing, China: concentrations and influencing factors

    Institute of Scientific and Technical Information of China (English)

    Chuanjia JIANG; Pengyi ZHANG

    2012-01-01

    Carbonyl compounds in indoor air are of great concern for their adverse health effects. Between February and May, 2009, concentrations of 13 carbonyl compounds were measured in an academic building in Beijing, China. Total concentration of the detected carbonyls ranged from 20.7 to 189.1 I.tg.m3, and among them acetone and formaldehyde were the most abundant, with mean concentrations of 26.4 and 22.6gg.m-3, respectively. Average indoor concentrations of other carbonyls were below I 0 gg. m~3. Principal component analysis identified a combined effect of common indoor carbonyl sources and ventilation on indoor carbonyl levels. Diurnal variations of the carbonyl compounds were investigated in one office room, and carbonyl concentrations tended to be lower in the daytime than at night, due to enhanced ventilation. Average concentrations of carbonyl compounds in the office room were generally higher in early May than in late February, indicating the influence of temperature. Carbo- nyl source emission rates from both the room and human occupants were estimated during two lectures, based on one-compartment mass balance model. The influence of human occupants on indoor carbonyl concentrations varies with environmental conditions, and may become signifi- cant in the case of a large human occupancy.

  15. Determination of Carbonyl Functional Groups in Bio-oils by Potentiometric Titration: The Faix Method.

    Science.gov (United States)

    Black, Stuart; Ferrell, Jack R

    2017-02-07

    Carbonyl compounds present in bio-oils are known to be responsible for bio-oil property changes upon storage and during upgrading. Specifically, carbonyls cause an increase in viscosity (often referred to as 'aging') during storage of bio-oils. As such, carbonyl content has previously been used as a method of tracking bio-oil aging and condensation reactions with less variability than viscosity measurements. Additionally, carbonyls are also responsible for coke formation in bio-oil upgrading processes. Given the importance of carbonyls in bio-oils, accurate analytical methods for their quantification are very important for the bio-oil community. Potentiometric titration methods based on carbonyl oximation have long been used for the determination of carbonyl content in pyrolysis bio-oils. Here, we present a modification of the traditional carbonyl oximation procedures that results in less reaction time, smaller sample size, higher precision, and more accurate carbonyl determinations. While traditional carbonyl oximation methods occur at room temperature, the Faix method presented here occurs at an elevated temperature of 80 °C.

  16. Pd(OAc)2-Catalyzed Tandem Reactions for the Synthesis of Indol-3-yl Substituted 1H-Isochromenes and 1,2-Dihydroisoquinolines%Pd(OAc)2-Catalyzed Tandem Reactions for the Synthesis of Indol-3-yl Substituted 1H-Isochromenes and 1,2-Dihydroisoquinolines

    Institute of Scientific and Technical Information of China (English)

    王欢; 韩秀玲; 陆熙炎

    2011-01-01

    A Pd(II) catalyzed tandem reaction of o-alkynylbenzaldehydes or o-alkynylbenzaldimines with substituted indoles initiated by the intermolecular addition of indoles to the carbonyl or imine group followed by the nucleopalladation of an intramolecular alkyne and quenching the carbon-palladium bond by protonolysis to regenerate the Pd(II) species was developed. The reaction can be carried out under mild conditions without the necessity of a redox system.

  17. Ni-, Pd-, or Pt-catalyzed ethylene dimerization: a mechanistic description of the catalytic cycle and the active species.

    Science.gov (United States)

    Roy, Dipankar; Sunoj, Raghavan B

    2010-03-07

    Two key mechanistic possibilities for group 10 transition metal [M(eta(3)-allyl)(PMe(3))](+) catalyzed (where M = Ni(II), Pd(II) and Pt(II)) ethylene dimerization are investigated using density functional theory methods. The nature of the potential active catalysts in these pathways is analyzed to gain improved insights into the mechanism of ethylene dimerization to butene. The catalytic cycle is identified as involving typical elementary steps in transition metal-catalyzed C-C bond formation reactions, such as oxidative insertion as well as beta-H elimination. The computed kinetic and thermodynamic features indicate that a commonly proposed metal hydride species (L(n)M-H) is less likely to act as the active species as compared to a metal-ethyl species (L(n)M-CH(2)CH(3)). Of the two key pathways considered, the active species is predicted to be a metal hydride in pathway-1, whereas a metal alkyl complex serves as the active catalyst in pathway-2. A metal-mediated hydride shift from a growing metal alkyl chain to the ethylene molecule, bound to the metal in an eta(2) fashion, is predicted to be the preferred route for the generation of the active species. Among the intermediates involved in the catalytic cycle, metal alkyls with a bound olefin are identified as thermodynamically stable for all three metal ions. In general, the Ni-catalyzed pathways are found to be energetically more favorable than those associated with Pd and Pt catalysts.

  18. Mechanism, reactivity, and regioselectivity in rhodium-catalyzed asymmetric ring-opening reactions of oxabicyclic alkenes: a DFT Investigation

    Science.gov (United States)

    Qi, Zheng-Hang; Zhang, Yi; Gao, Yun; Zhang, Ye; Wang, Xing-Wang; Wang, Yong

    2017-01-01

    The origin of the enantio- and regioselectivity of ring-opening reaction of oxabicyclic alkenes catalyzed by rhodium/Josiphos has been examined using M06-2X density functional theory(DFT). DFT calculations predict a 98% ee for the enantioselectivity and only the 1,2-trans product as one regio- and diastereomer, in excellent agreement with experimental results. The solvent tetrahydrofuran(THF) plays a key role in assisting nucleophilic attack. Orbital composition analysis of the LUMO and the NPA atomic charge calculations were conducted to probe the origins of the regioselectivity. The orbital composition analysis reveals two potential electrophilic sites of the Rh–π-allyl intermediate M3 and the NPA atomic charges demonstrate that Cα carries more positive charges than Cγ, which suggests that Cα is the electrophilic site. PMID:28074930

  19. Selective conversion of polyenes to monoenes by RuCl(3) -catalyzed transfer hydrogenation: the case of cashew nutshell liquid.

    Science.gov (United States)

    Perdriau, Sébastien; Harder, Sjoerd; Heeres, Hero J; de Vries, Johannes G

    2012-12-01

    Cardanol, a constituent of cashew nutshell liquid (CNSL), was subjected to transfer hydrogenation catalyzed by RuCl(3) using isopropanol as a reductant. The side chain of cardanol, which is a mixture of a triene, a diene, and a monoene, was selectively reduced to the monoene. Surprisingly, it is the C8-C9 double bond that is retained with high selectivity. A similar transfer hydrogenation of linoleic acid derivatives succeeded only if the substrate contained an aromatic ring, such as a benzyl ester. TEM and a negative mercury test showed that the catalyst was homogeneous. By using ESI-MS, ruthenium complexes were identified that contained one, two, or even three molecules of substrate, most likely as allyl complexes. The interaction between ruthenium and the aromatic ring determines selectivity in the hydrogenation reaction.

  20. Mechanism, reactivity, and regioselectivity in rhodium-catalyzed asymmetric ring-opening reactions of oxabicyclic alkenes: a DFT Investigation

    Science.gov (United States)

    Qi, Zheng-Hang; Zhang, Yi; Gao, Yun; Zhang, Ye; Wang, Xing-Wang; Wang, Yong

    2017-01-01

    The origin of the enantio- and regioselectivity of ring-opening reaction of oxabicyclic alkenes catalyzed by rhodium/Josiphos has been examined using M06-2X density functional theory(DFT). DFT calculations predict a 98% ee for the enantioselectivity and only the 1,2-trans product as one regio- and diastereomer, in excellent agreement with experimental results. The solvent tetrahydrofuran(THF) plays a key role in assisting nucleophilic attack. Orbital composition analysis of the LUMO and the NPA atomic charge calculations were conducted to probe the origins of the regioselectivity. The orbital composition analysis reveals two potential electrophilic sites of the Rh-π-allyl intermediate M3 and the NPA atomic charges demonstrate that Cα carries more positive charges than Cγ, which suggests that Cα is the electrophilic site.

  1. Fundamental reaction mechanism and free energy profile for (-)-cocaine hydrolysis catalyzed by cocaine esterase.

    Science.gov (United States)

    Liu, Junjun; Hamza, Adel; Zhan, Chang-Guo

    2009-08-26

    The fundamental reaction mechanism of cocaine esterase (CocE)-catalyzed hydrolysis of (-)-cocaine and the corresponding free energy profile have been studied by performing pseudobond first-principles quantum mechanical/molecular mechanical free energy (QM/MM-FE) calculations. On the basis of the QM/MM-FE results, the entire hydrolysis reaction consists of four reaction steps, including the nucleophilic attack on the carbonyl carbon of (-)-cocaine benzoyl ester by the hydroxyl group of Ser117, dissociation of (-)-cocaine benzoyl ester, nucleophilic attack on the carbonyl carbon of (-)-cocaine benzoyl ester by water, and finally dissociation between the (-)-cocaine benzoyl group and Ser117 of CocE. The third reaction step involving the nucleophilic attack of a water molecule was found to be rate-determining, which is remarkably different from (-)-cocaine hydrolysis catalyzed by wild-type butyrylcholinesterase (BChE; where the formation of the prereactive BChE-(-)-cocaine complex is rate-determining) or its mutants containing Tyr332Gly or Tyr332Ala mutation (where the first chemical reaction step is rate-determining). Besides, the role of Asp259 in the catalytic triad of CocE does not follow the general concept of the "charge-relay system" for all serine esterases. The free energy barrier calculated for the rate-determining step of CocE-catalyzed hydrolysis of (-)-cocaine is 17.9 kcal/mol, which is in good agreement with the experimentally derived activation free energy of 16.2 kcal/mol. In the present study, where many sodium ions are present, the effects of counterions are found to be significant in determining the free energy barrier. The finding of the significant effects of counterions on the free energy barrier may also be valuable in guiding future mechanistic studies on other charged enzymes.

  2. Role of allyl group in the hydroxyl and peroxyl radical scavenging activity of S-allylcysteine.

    Science.gov (United States)

    Maldonado, Perla D; Alvarez-Idaboy, J Raúl; Aguilar-González, Adriana; Lira-Rocha, Alfonso; Jung-Cook, Helgi; Medina-Campos, Omar Noel; Pedraza-Chaverrí, José; Galano, Annia

    2011-11-17

    S-Allylcysteine (SAC) is the most abundant compound in aged garlic extracts, and its antioxidant properties have been demonstrated. It is known that SAC is able to scavenge different reactive species including hydroxyl radical (•OH), although its potential ability to scavenge peroxyl radical (ROO•) has not been explored. In this work the ability of SAC to scavenge ROO• was evaluated, as well as the role of the allyl group (-S-CH(2)-CH═CH(2)) in its free radical scavenging activity. Two derived compounds of SAC were prepared: S-benzylcysteine (SBC) and S-propylcysteine (SPC). Their abilities to scavenge •OH and ROO• were measured. A computational analysis was performed to elucidate the mechanism by which these compounds scavenge •OH and ROO•. SAC was able to scavenge •OH and ROO•, in a concentration-dependent way. Such activity was significantly ameliorated when the allyl group was replaced by benzyl or propyl groups. It was shown for the first time that SAC is able to scavenge ROO•.

  3. Further exploration of the heterocyclic diversity accessible from the allylation chemistry of indigo

    Science.gov (United States)

    Shakoori, Alireza; Bremner, John B; Abdel-Hamid, Mohammed K; Willis, Anthony C; Haritakun, Rachada

    2015-01-01

    Summary Diversity-directed synthesis based on the cascade allylation chemistry of indigo, with its embedded 2,2’-diindolic core, has resulted in rapid access to new examples of the hydroxy-8a,13-dihydroazepino[1,2-a:3,4-b']diindol-14(8H)-one skeleton in up to 51% yield. Additionally a derivative of the novel bridged heterocycle 7,8-dihydro-6H-6,8a-epoxyazepino[1,2-a:3,4-b']diindol-14(13H)-one was produced when the olefin of the allylic substrate was terminally disubstituted. Further optimisation also produced viable one-pot syntheses of derivatives of the spiro(indoline-2,9'-pyrido[1,2-a]indol)-3-one (65%) and pyrido[1,2,3-s,t]indolo[1,2-a]azepino[3,4-b]indol-17-one (72%) heterocyclic systems. Ring-closing metathesis of the N,O-diallylic spiro structure and subsequent Claisen rearrangement gave rise to the new (1R,8aS,17aS)-rel-1,2-dihydro-1-vinyl-8H,17H,9H-benz[2',3']pyrrolizino[1',7a':2,3]pyrido[1,2-a]indole-8,17-(2H,9H)-dione heterocyclic system. PMID:25977722

  4. Further exploration of the heterocyclic diversity accessible from the allylation chemistry of indigo

    Directory of Open Access Journals (Sweden)

    Alireza Shakoori

    2015-04-01

    Full Text Available Diversity-directed synthesis based on the cascade allylation chemistry of indigo, with its embedded 2,2’-diindolic core, has resulted in rapid access to new examples of the hydroxy-8a,13-dihydroazepino[1,2-a:3,4-b']diindol-14(8H-one skeleton in up to 51% yield. Additionally a derivative of the novel bridged heterocycle 7,8-dihydro-6H-6,8a-epoxyazepino[1,2-a:3,4-b']diindol-14(13H-one was produced when the olefin of the allylic substrate was terminally disubstituted. Further optimisation also produced viable one-pot syntheses of derivatives of the spiro(indoline-2,9'-pyrido[1,2-a]indol-3-one (65% and pyrido[1,2,3-s,t]indolo[1,2-a]azepino[3,4-b]indol-17-one (72% heterocyclic systems. Ring-closing metathesis of the N,O-diallylic spiro structure and subsequent Claisen rearrangement gave rise to the new (1R,8aS,17aS-rel-1,2-dihydro-1-vinyl-8H,17H,9H-benz[2',3']pyrrolizino[1',7a':2,3]pyrido[1,2-a]indole-8,17-(2H,9H-dione heterocyclic system.

  5. Iron complexes of tetramine ligands catalyse allylic hydroxyamination via a nitroso–ene mechanism

    Directory of Open Access Journals (Sweden)

    David Porter

    2015-12-01

    Full Text Available Iron(II complexes of the tetradentate amines tris(2-pyridylmethylamine (TPA and N,N′-bis(2-pyridylmethyl-N,N′-dimethylethane-1,2-diamine (BPMEN are established catalysts of C–O bond formation, oxidising hydrocarbon substrates via hydroxylation, epoxidation and dihydroxylation pathways. Herein we report the capacity of these catalysts to promote C–N bond formation, via allylic amination of alkenes. The combination of N-Boc-hydroxylamine with either FeTPA (1 mol % or FeBPMEN (10 mol % converts cyclohexene to the allylic hydroxylamine (tert-butyl cyclohex-2-en-1-yl(hydroxycarbamate in moderate yields. Spectroscopic studies and trapping experiments suggest the reaction proceeds via a nitroso–ene mechanism, with involvement of a free N-Boc-nitroso intermediate. Asymmetric induction is not observed using the chiral tetramine ligand (+-(2R,2′R-1,1′-bis(2-pyridylmethyl-2,2′-bipyrrolidine ((R,R′-PDP.

  6. Rh(III) and Ru(II)-catalyzed site-selective C-H alkynylation of quinolones.

    Science.gov (United States)

    Kang, Dahye; Hong, Sungwoo

    2015-04-17

    C2- and C5-alkynylated quinolone scaffolds are core structures of numerous biologically active molecules. Utilizing TIPS-EBX as an alkynylating agent, we have developed an efficient and site-selective C5 alkynylation of 4-quinolones that is directed by the weakly coordinating carbonyl group. In addition, Ru(II) catalyzed C2-selective alkynylation was successfully realized via N-pyrimidyl group-directed cross-couplings to access valuable C2-alkynylated 4-quinolones. This strategy provides direct access to the C2 or C5 alkynylated 4-quinolones. Furthermore, the reaction was applied to isoquinolones for C3-selective alkynylation.

  7. Origin of stereoselectivity in a chiral N-heterocyclic carbene-catalyzed desymmetrization of substituted cyclohexyl 1,3-diketones.

    Science.gov (United States)

    Reddi, Yernaidu; Sunoj, Raghavan B

    2012-06-01

    The mechanism and stereoselectivity in a chiral N-heterocyclic carbene-catalyzed desymmetrization of a 1,3-diketone is established by using density functional theory computations. The Breslow intermediate formation is identified to involve Hunig's base-assisted proton transfer. The relative energies of stereoselectivity-determining intramolecular aldol cyclization transition states reveal that in the most preferred mode the re-face of enolate adds to the si-face of carbonyl leading to a tricyclic lactone with a configuration (2aS,4aS,8'S) in excellent agreement with previous experimental reports.

  8. Continuous In-situ Measurements of Carbonyl Sulfide to Constrain Ecosystem Carbon and Water Exchange

    Science.gov (United States)

    Rastogi, B.; Kim, Y.; Berkelhammer, M. B.; Noone, D. C.; Lai, C. T.; Hollinger, D. Y.; Bible, K.; Leen, J. B.; Gupta, M.; Still, C. J.

    2014-12-01

    Understanding the processes that control the terrestrial exchange of carbon and water are critical for examining the role of forested ecosystems in changing climates. A small but increasing number of studies have identified Carbonyl Sulfide (OCS) as a potential tracer for photosynthesis. OCS is hydrolyzed by an irreversible reaction in leaf mesophyll cells that is catalyzed by the enzyme, carbonic anhydrase. Leaf-level field and greenhouse studies indicate that OCS uptake is controlled by stomatal activity and that the ratio of OCS and CO2 uptake is reasonably constant. Existing studies on ecosystem OCS exchange have been based on laboratory measurements or short field campaigns and therefore little information on OCS exchange in a natural ecosystem over longer timescales is available. The objective of this study is to further assess the stability of OCS as a tracer for canopy photosynthesis in an active forested ecosystem and also to assess its utility for constraining transpiration, since both fluxes are mediated by canopy stomatal conductance. An off-axis integrated cavity output spectroscopy analyzer (Los Gatos Research Inc.) was deployed at the Wind River Experimental Forest in Washington (45.8205°N, 121.9519°W). Canopy air was sampled from three heights to measure vertical gradients of OCS within the canopy, and OCS exchange between the forest and the atmosphere. Here we take advantage of simultaneous measurements of the stable isotopologues of H2O and CO2 at corresponding heights as well as NEE (Net Ecosystem Exchange) from eddy covariance measurements to compare GPP (Gross Primary Production) and transpiration estimates from a variety of independent techniques. Our findings seek to allow assessment of the environmental and ecophysicological controls on evapotranspiration rates, which are projected to change in coming decades, and are otherwise poorly constrained.

  9. Determination of Carbonyl Compounds in Cigarette Mainstream Smoke. The CORESTA 2010 Collaborative Study and Recommended Method

    Directory of Open Access Journals (Sweden)

    Intorp M

    2014-12-01

    Full Text Available A recommended method has been developed and published by CORESTA, applicable to the quantification of selected carbonyl compounds (acetaldehyde, formaldehyde, acetone, acrolein, methyl ethyl ketone, crotonaldehyde, propionaldehyde and butyraldehyde in cigarette mainstream smoke. The method involved smoke collection in impinger traps, derivatisation of carbonyls with 2,4-dinitrophenylhydrazine (DNPH, separation of carbonyl hydrazones by reversed phase high performance liquid chromatography and detection by ultra violet or diode array.

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

    Science.gov (United States)

    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.

  11. A biotin enrichment strategy identifies novel carbonylated amino acids in proteins from human plasma

    DEFF Research Database (Denmark)

    Havelund, Jesper F.; Wojdyla, Katarzyna; Davies, Michael J.

    2017-01-01

    Protein carbonylation is an irreversible protein oxidation correlated with oxidative stress, various diseases and ageing. Here we describe a peptide-centric approach for identification and characterisation of up to 14 different types of carbonylated amino acids in proteins. The modified residues...... in vitro metal ion-catalysed oxidation. Furthermore, we assigned 133 carbonylated sites in 36 proteins in native human plasma protein samples. The optimised workflow enabled detection of 10 hitherto undetected types of carbonylated amino acids in proteins: aldehyde and ketone modifications of leucine...

  12. The NBS Reaction: A Simple Explanation for the Predominance of Allylic Substitution over Olefin Addition by Bromine at Low Concentrations.

    Science.gov (United States)

    Wamser, Carl C.; Scott, Lawrence T.

    1985-01-01

    Examines mechanisms related to use of N-bromosuccinimide (NBS) for bromination at an allylic position. Also presents derived rate laws for three possible reactions of molecular bromine with an alkene: (1) free radical substitution; (2) free radical addition; and (3) electrophilic addition. (JN)

  13. Antimicrobial activity of allyl isothiocyanate used to coat biodegradable composite films as affected by storage and handling conditions

    Science.gov (United States)

    We evaluated the effects of storage and handling conditions on the antimicrobial activity of biodegradable composite films (polylactic acid and sugar beet pulp) coated with allyl isothiocyanate (AIT). Polylactic acid (PLA) and chitosan were incorporated with AIT and coated on one side of the film. T...

  14. Spectra of carbanions formed from allyl cyanide during isomerization in zeolite NaY-FAU with strong basic sites

    Science.gov (United States)

    Hannus, István; Förster, Horst; Tasi, Gyula; Kiricsi, Imre; Molnár, Árpád

    1995-03-01

    Double bond isomerization of allyl cyanide to crotononitrile over a basic zeolite catalyst was monitored by IR and UV-VIS spectroscopy in order to get information on the surface intermediates involved. Due to the spectral changes the occurence of a carbanionic intermediate seems to be highly probable characterized by an absorption at 400 nm.

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

    Directory of Open Access Journals (Sweden)

    Halyna M. Semchyshyn

    2014-01-01

    Full Text Available 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.

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

    Science.gov (United States)

    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.

  17. Influences of characteristic meteorological conditions on atmospheric carbonyls in Beijing, China

    Science.gov (United States)

    Pang, Xiaobing; Mu, Yujing; Lee, Xinqing; Zhang, Yujie; Xu, Zhu

    2009-08-01

    Atmospheric pollutants are controlled not only by their production rates but also by meteorological conditions. The influences of dust storm, sauna weather (haze with high temperature and high humidity), wet precipitation and wind speed on atmospheric carbonyls in Beijing were investigated. During a severe dust episode (April 17, 2006), the mixing ratios of carbonyls were significantly elevated to 13-27 ppbV from 7 to 13 ppbV in the previous non-dust days (April 15 and 16) with the increasing extents of 38-154%. The accumulating effect and the lower photolysis rate in the dust day may be responsible for the increases of carbonyls' levels. Additionally, the contribution from heterogeneous reactions occurring on dust particles to formaldehyde and acetaldehyde cannot be ruled out. During the period of typical sauna weather, the concentrations of atmospheric carbonyls increased to 18-60 ppbV from 10 to 17 ppbV before the sauna days. The air mass over Beijing during the sauna days was controlled by a subtropical anticyclone and the boundary layer became quite stable, which was beneficial to the rapid accumulation of air pollutants including carbonyls. Wet precipitation was found to be an effective removal process to the atmospheric carbonyls. After one-hour of rain in summer, the total concentrations of atmospheric carbonyls decreased to less than half of that before the rainfall. The similar temporal varying patterns of carbonyls and inorganic ions in rainwater indicated that carbonyls were mainly washed out from the atmosphere into rainwater as inorganic ions were. Strong wind could evidently dilute atmospheric carbonyls and a negative correlation was found between wind speeds and the concentrations of carbonyls in spring in Beijing.

  18. Thermodynamics of Enzyme-Catalyzed Reactions Database

    Science.gov (United States)

    SRD 74 Thermodynamics of Enzyme-Catalyzed Reactions Database (Web, free access)   The Thermodynamics of Enzyme-Catalyzed Reactions Database contains thermodynamic data on enzyme-catalyzed reactions that have been recently published in the Journal of Physical and Chemical Reference Data (JPCRD). For each reaction the following information is provided: the reference for the data, the reaction studied, the name of the enzyme used and its Enzyme Commission number, the method of measurement, the data and an evaluation thereof.

  19. The Reaction of Allyl Isothiocyanate with Hydroxyl/Water and β-Cyclodextrin Using Ultraviolet Spectrometry

    Directory of Open Access Journals (Sweden)

    Zi-Tao Jiang

    2006-01-01

    Full Text Available The reaction of allyl isothiocyanate (AITC with hydroxyl/water and β-cyclodextrin (β-CD in different acidic-alkaline media has been investigated by ultraviolet spectrometry. The kinetic parameters of the reaction were measured. It was found that after AITC translating into thiourea, the absorption peak shifted from 240 to 226 nm and the molar absorptivity increased about 16 times. The reaction can be seen as a pseudo first order reaction because the concentration of hydroxyl was constant. β-CD can inhibit the reaction of AITC with hydroxyl/water, i.e. the hydrolysis of AITC. The formation constant (Ka and thermodynamic parameters of the complex reaction were calculated. Ka decreased with the increase of temperature. The experimental results indicated that the inclusive process was an exothermic and enthalpy-driven process accompanied with a negative entropic contribution.

  20. Enantioselective construction of quaternary N-heterocycles by palladium-catalysed decarboxylative allylic alkylation of lactams

    KAUST Repository

    Behenna, Douglas C.

    2011-12-18

    The enantioselective synthesis of nitrogen-containing heterocycles (N-heterocycles) represents a substantial chemical research effort and resonates across numerous disciplines, including the total synthesis of natural products and medicinal chemistry. In this Article, we describe the highly enantioselective palladium-catalysed decarboxylative allylic alkylation of readily available lactams to form 3,3-disubstituted pyrrolidinones, piperidinones, caprolactams and structurally related lactams. Given the prevalence of quaternary N-heterocycles in biologically active alkaloids and pharmaceutical agents, we envisage that our method will provide a synthetic entry into the de novo asymmetric synthesis of such structures. As an entry for these investigations we demonstrate how the described catalysis affords enantiopure quaternary lactams that intercept synthetic intermediates previously used in the synthesis of the Aspidosperma alkaloids quebrachamine and rhazinilam, but that were previously only available by chiral auxiliary approaches or as racemic mixtures. © 2012 Macmillan Publishers Limited. All rights reserved.

  1. Low-temperature Electrodeposition of Aluminium from Lewis Acidic 1-Allyl-3-methylimidazolium Chloroaluminate Ionic Liquids

    Institute of Scientific and Technical Information of China (English)

    郑勇; 张锁江; 吕兴梅; 王倩; 左勇; 刘恋

    2012-01-01

    Lewis acidic 1-allyl-3-methylimidazolium chloroaluminate ionic liquids were used as promising electrolytes in the low-temperature electrodeposition of aluminium. Systematic studies on deposition process have been performed by cYClic voltammetry and chronoamperometry. The surface morphology and X-ray diffraction (XRD) patterns of deposits prepared at different experimental conditions were also investigated. It was shown that the nucleation density and growth rate of crystallites had a great effect on the structure of aluminium deposited. The crys- tallographic orientation of deposits was mainly influenced by temperature and current density. Smooth, dense and well adherent aluminium coatings were obtained on copper substrates at 10-25 mA.cm^-2 and 313.2-353.2 K. More- over, the current efficiency of deposition and purity of aluminium have been significantly improved, demonstrating that the ionic liquids tested have a prospectful potential in electroplating and electrorefining of aluminium.

  2. Structural characteristics of green tea catechins for formation of protein carbonyl in human serum albumin.

    Science.gov (United States)

    Ishii, Takeshi; Mori, Taiki; Ichikawa, Tatsuya; Kaku, Maiko; Kusaka, Koji; Uekusa, Yoshinori; Akagawa, Mitsugu; Aihara, Yoshiyuki; Furuta, Takumi; Wakimoto, Toshiyuki; Kan, Toshiyuki; Nakayama, Tsutomu

    2010-07-15

    Catechins are polyphenolic antioxidants found in green tea leaves. Recent studies have reported that various polyphenolic compounds, including catechins, cause protein carbonyl formation in proteins via their pro-oxidant actions. In this study, we evaluate the formation of protein carbonyl in human serum albumin (HSA) by tea catechins and investigate the relationship between catechin chemical structure and its pro-oxidant property. To assess the formation of protein carbonyl in HSA, HSA was incubated with four individual catechins under physiological conditions to generate biotin-LC-hydrazide labeled protein carbonyls. Comparison of catechins using Western blotting revealed that the formation of protein carbonyl in HSA was higher for pyrogallol-type catechins than the corresponding catechol-type catechins. In addition, the formation of protein carbonyl was also found to be higher for the catechins having a galloyl group than the corresponding catechins lacking a galloyl group. The importance of the pyrogallol structural motif in the B-ring and the galloyl group was confirmed using methylated catechins and phenolic acids. These results indicate that the most important structural element contributing to the formation of protein carbonyl in HSA by tea catechins is the pyrogallol structural motif in the B-ring, followed by the galloyl group. The oxidation stability and binding affinity of tea catechins with proteins are responsible for the formation of protein carbonyl, and consequently the difference in these properties of each catechin may contribute to the magnitude of their biological activities.

  3. Preparation and microwave shielding property of silver-coated carbonyl iron powder

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Xiao Guo, E-mail: xgcao@gdut.edu.cn [School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, Guangdong (China); Ren, Hao [Guangzhou Research Institute of O-M-E Technology, Guangzhou 510006, Guangdong (China); Zhang, Hai Yan [School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, Guangdong (China)

    2015-05-15

    Highlights: • The silver-coated carbonyl iron powder is prepared by the electroless plating process. • The silver-coated carbonyl iron powder is a new kind of conductive filler. • The reflection and absorption dominate the shielding mechanism of the prepared powder. • Increasing the thickness of electroconductive adhesive will increase the SE. - Abstract: Electroless silver coating of carbonyl iron powder is demonstrated in the present investigation. The carbonyl iron powders are characterized by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction analysis (XRD) before and after the coating process. The relatively uniform and continuous silver coating is obtained under the given coating conditions. In this paper, the electromagnetic interference (EMI) shielding mechanism of the silver-coated carbonyl iron powder is suggested. The reflection of silver coating and absorption of carbonyl iron powder dominate the shielding mechanism of the silver-coated carbonyl iron powder. The silver-coated carbonyl iron powders are used as conductive filler in electroconductive adhesive for electromagnetic interference shielding applications. The effect of the thickness of electroconductive adhesive on the shielding effectiveness (SE) is investigated. The results indicate that the SE increases obviously with the increase of the thickness of electroconductive adhesive. The SE of the electroconductive adhesive with 0.35 mm thickness is above 38 dB across the tested frequency range.

  4. Asymmetric synthesis of chiral β-alkynyl carbonyl and sulfonyl derivatives via sequential palladium and copper catalysis† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c6sc01724j Click here for additional data file.

    Science.gov (United States)

    Masters, James T.; Taft, Benjamin R.; Lumb, Jean-Philip

    2016-01-01

    We present a full account detailing the development of a sequential catalysis strategy for the synthesis of chiral β-alkynyl carbonyl and sulfonyl derivatives. A palladium-catalyzed cross coupling of terminal alkyne donors with acetylenic ester, ketone, and sulfone acceptors generates stereodefined enynes in high yield. These compounds are engaged in an unprecedented, regio- and enantioselective copper-catalyzed conjugate reduction. The process exhibits a high functional group tolerance, and this enables the synthesis of a broad range of chiral products from simple, readily available alkyne precursors. The utility of the method is demonstrated through the elaboration of the chiral β-alkynyl products into a variety of different molecular scaffolds. Its value in complex molecule synthesis is further validated through a concise, enantioselective synthesis of AMG 837, a potent GPR40 receptor agonist. PMID:27746892

  5. Synthesis and characterization of bisoxazolines- and pybox-copper(II) complexes and their application in the coupling of α-carbonyls with functionalized amines

    KAUST Repository

    Jia, Weiguo

    2014-01-01

    Binuclear complexes [{(DMOX)CuCl}2(μ-Cl)2] (1), mononuclear complexes [(DMOX)CuBr2] (2) (DMOX = 4,5-dihydro-2-(4,5- dihydro-4,4-dimethyloxazol-2-yl)-4,4-dimethyloxazole) and the pybox Cu(ii) complex [(Dm-Pybox)CuBr2] (3) (Dm-Pybox = 2,6-bis[4′,4′- dimethyloxazolin-2′-yl]pyridine) were obtained by reactions of CuX 2 (X = Cl, Br) with DMOX and Dm-Pybox ligands, respectively. The molecular structures of 1, 2 and 3 have been determined by single-crystal X-ray diffraction analyses. The complexes 2 and 3 are efficient in catalyzing α-amination of ketones and esters through α-bromo carbonyl intermediate. The procedures are environmentally benign methods using molecular oxygen as an oxidant with water as the only byproduct. This journal is © the Partner Organisations 2014.

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

    Science.gov (United States)

    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.

  7. Rh(I-catalyzed intramolecular [2 + 2 + 1] cycloaddition of allenenes: Construction of bicyclo[4.3.0]nonenones with an angular methyl group and tricyclo[6.4.0.01,5]dodecenone

    Directory of Open Access Journals (Sweden)

    Chisato Mukai

    2011-04-01

    Full Text Available The [RhCl(COdppp]2-catalyzed intramolecular carbonylative [2 + 2 + 1] cycloaddition of allenenes was developed to prepare bicyclo[4.3.0]nonenones possessing a methyl group at the ring junction, which is difficult to achieve by the Pauson–Khand reaction of the corresponding enynes. This method also provided a new procedure for the construction of the tricyclo[6.4.0.01,5]dodecenone framework in a satisfactory yield.

  8. Carbonyl mediated conductance through metal bound peptides: a computational study

    Science.gov (United States)

    Perrine, Trilisa M.; Dunietz, Barry D.

    2007-10-01

    Large increases in the conductance of peptides upon binding to metal ions have recently been reported experimentally. The mechanism of the conductance switching is examined computationally. It is suggested that oxidation of the metal ion occurs after binding to the peptide. This is caused by the bias potential placed across the metal-peptide complex. A combination of configurational changes, metal ion involvement and interactions between carbonyl group oxygen atoms and the gold leads are all shown to be necessary for the large improvement in the conductance seen experimentally. Differences in the molecular orbitals of the nickel and copper complexes are noted and serve to explain the variation of the improvement in conductance upon binding to either a nickel or copper ion.

  9. Uptake and conversion of carbonyl sulfide in a lawn soil

    Science.gov (United States)

    Liu, Junfeng; Mu, Yujing; Geng, Chunmei; Yu, Yunbo; He, Hong; Zhang, Yuanhang

    Carbonyl sulfide (COS) exchange fluxes between a lawn soil and the atmosphere as well as influencing factors (temperature and water content of soil) were investigated using a static cuvette. The optimal soil temperature and water content for COS consumption were about 298 K and 12.5%, respectively. The converting products of the consumed COS in the lawn soil were researched using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The peaks of gas-phase products of CO2 and surface HCO3-, HS-, SO32-, HSO3-, and SO42- species were observed. The possible mechanism of COS conversion in the lawn soil was discussed. The conversion rates of consumed COS into water-soluble sulfate in the lawn soil were studied by ion chromatography (IC). The experimental results show that about 50% sulfur from the soil consumed COS was eventually converted into water-soluble sulfate.

  10. Modular access to vicinally functionalized allylic (thio)morpholinonates and piperidinonates by substrate-controlled annulation of 1,3-azadienes with hexacyclic anhydrides.

    Science.gov (United States)

    Braunstein, Hannah; Langevin, Spencer; Khim, Monique; Adamson, Jonathan; Hovenkotter, Katie; Kotlarz, Lindsey; Mansker, Brandon; Beng, Timothy K

    2016-09-21

    A modular substrate-controlled hexannulation of inherently promiscuous 1,3-azadienes with hexacyclic anhydrides, which affords versatile vicinally functionalized allylic lactams, in high yields, regio- and stereoselectivities is described.

  11. Anti-Amoebic Properties of Carbonyl Thiourea Derivatives

    Directory of Open Access Journals (Sweden)

    Maizatul Akma Ibrahim

    2014-04-01

    Full Text Available Thiourea derivatives display a broad spectrum of applications in chemistry, various industries, medicines and various other fields. Recently, different thiourea derivatives have been synthesized and explored for their anti-microbial properties. In this study, four carbonyl thiourea derivatives were synthesized and characterized, and then further tested for their anti-amoebic properties on two potential pathogenic species of Acanthamoeba, namely A. castellanii (CCAP 1501/2A and A. polyphaga (CCAP 1501/3A. The results indicate that these newly-synthesized thiourea derivatives are active against both Acanthamoeba species. The IC50 values obtained were in the range of 2.39–8.77 µg·mL‑1 (9.47–30.46 µM for A. castellanii and 3.74–9.30 µg·mL‑1 (14.84–31.91 µM for A. polyphaga. Observations on the amoeba morphology indicated that the compounds caused the reduction of the amoeba size, shortening of their acanthopodia structures, and gave no distinct vacuolar and nuclear structures in the amoeba cells. Meanwhile, fluorescence microscopic observation using acridine orange and propidium iodide (AOPI staining revealed that the synthesized compounds induced compromised-membrane in the amoeba cells. The results of this study proved that these new carbonyl thiourea derivatives, especially compounds M1 and M2 provide potent cytotoxic properties toward pathogenic Acanthamoeba to suggest that they can be developed as new anti-amoebic agents for the treatment of Acanthamoeba keratitis.

  12. Reaction mechanism for cocaine esterase-catalyzed hydrolyses of (+)- and (-)-cocaine: unexpected common rate-determining step.

    Science.gov (United States)

    Liu, Junjun; Zhao, Xinyun; Yang, Wenchao; Zhan, Chang-Guo

    2011-05-05

    First-principles quantum mechanical/molecular mechanical free energy calculations have been performed to examine the catalytic mechanism for cocaine esterase (CocE)-catalyzed hydrolysis of (+)-cocaine in comparison with CocE-catalyzed hydrolysis of (-)-cocaine. It has been shown that the acylation of (+)-cocaine consists of nucleophilic attack of the hydroxyl group of Ser117 on the carbonyl carbon of (+)-cocaine benzoyl ester and the dissociation of (+)-cocaine benzoyl ester. The first reaction step of deacylation of (+)-cocaine, which is identical to that of (-)-cocaine, is rate-determining, indicating that CocE-catalyzed hydrolyses of (+)- and (-)-cocaine have a common rate-determining step. The computational results predict that the catalytic rate constant of CocE against (+)-cocaine should be the same as that of CocE against (-)-cocaine, in contrast with the remarkable difference between human butyrylcholinesterase-catalyzed hydrolyses of (+)- and (-)-cocaine. The prediction has been confirmed by experimental kinetic analysis on CocE-catalyzed hydrolysis of (+)-cocaine in comparison with CocE-catalyzed hydrolysis of (-)-cocaine. The determined common rate-determining step indicates that rational design of a high-activity mutant of CocE should be focused on the first reaction step of the deacylation. Furthermore, the obtained mechanistic insights into the detailed differences in the acylation between the (+)- and (-)-cocaine hydrolyses provide indirect clues for rational design of amino acid mutations that could more favorably stabilize the rate-determining transition state in the deacylation and, thus, improve the catalytic activity of CocE. This study provides a valuable mechanistic base for rational design of an improved esterase for therapeutic treatment of cocaine abuse.

  13. Density functional study on enantioselective reduction of keto oxime ether with borane catalyzed by oxazaborolidine

    Institute of Scientific and Technical Information of China (English)

    LI; Ming; ZHENG; Wenxu

    2006-01-01

    The enantioselective reduction of keto oxime ether with borane catalyzed by oxazaborolidine is discussed by the density functional theory (DFT) method. The main intermediates and transition states for this reaction are optimized completely at the B3LYP/6-31g(d) level, and the transition states are verified by vibrational modes. As shown, the chirality-controlled steps for this reaction are the hydride transfer from borane to carbonyl carbon and oxime carbon of keto oxime ether, and the chirality for the reduced products is determined in these two reaction steps. In all examined reaction paths, the first hydride is transferred via a six-membered ring and the second hydride via a five-membered ring or a four-membered ring.

  14. Oxidation reaction of 4-allyl-4-hydroperoxy-2-methoxycyclohexa-2,5-dienone in the presence of potassium permanganate without a co-oxidant

    Directory of Open Access Journals (Sweden)

    Mehmet Serdar Gültekin

    2016-12-01

    Full Text Available 4-Allyl-4-hydroperoxy-2-methoxycyclohexa-2,5-dienone (5 was synthesized by photooxygenation of commercially available Eugenol in the presence of tetraphenylporphyrin (TPP as a singlet oxygen sensitizer. The brief and one-pot syntheses of some natural product skeletons were conducted using the corresponding allylic hydroperoxide at different temperatures (0 oC and room temperature with potassium permanganate (KMnO 4 in mild condition at N 2(g atm.

  15. A convenient and stereoselective synthesis of (Z)-allyl selenides via Sm/TMSCI system-promoted coupling of Baylis-Hillman adducts with diselenides

    Institute of Scientific and Technical Information of China (English)

    LIU Yun-kui; XU Dan-qian; XU Zhen-yuan; ZHANG Yong-min

    2006-01-01

    A simple and convenient procedure for stereoselective synthesis of (Z)-allyl selenides has been developed by a one-pot reaction of diselenides with Baylis-Hillman adducts in the presence of samarium metal-trimethylsilyl chloride under mild conditions. Presumably, the diselenides are cleaved by Sm/TMSCl system to form selenide anions, which then undergo SN2' substitution of Baylis-Hillman adducts to produce the (Z)-allyl selenides.

  16. Transition metal-catalyzed functionalization of pyrazines

    NARCIS (Netherlands)

    Nikishkin, Nicolai I.; Huskens, Jurriaan; Verboom, Willem

    2013-01-01

    Transition metal-catalyzed reactions are generally used for carbon–carbon bond formation on pyrazines and include, but are not limited to, classical palladium-catalyzed reactions like Sonogashira, Heck, Suzuki, and Stille reactions. Also a few examples of carbon–heteroatom bond formation in pyrazine

  17. REDUCING NONSELECTIVE PROTEIN ADSORPTION AND CELL ADHESION ON POLYACRYLONITRILE FILMS BY COPOLYMERIZATION OF ACRYLONITRILE WITH α-ALLYL GLUCOSIDE

    Institute of Scientific and Technical Information of China (English)

    Rui-qiang Kou; Chao Qu; Zhi-kang Xu; You-yi Xu; Ke Yao

    2003-01-01

    In this work, the surface properties of novel sugar-containing polymers, α-allyl glucoside (AG)/acrylonitrile (AN)copolymers, were studied by contact angle, protein adsorption and cell adhesion measurements. It was found that the contact angle of the copolymer films decreased from 68° to 30° with the increase of AG content in the copolymer. The adsorption amount of bovine serum albumin (BSA) and the adhesive macrophage onto the film surface also decreased significantly with increasing α-allyl glucoside content from 0 to 42 wt% in the copolymer. These preliminary results reveal that both the hydrophilicity and the biocompatibility of polyacrylonitrile-based membranes could be improved by copolymerizing acrylonitrile with vinyl carbohydrates.

  18. One-pot synthesis of enantiomerically pure N-protected allylic amines from N-protected α-amino esters

    Science.gov (United States)

    Silveira-Dorta, Gastón; Álvarez-Méndez, Sergio J; Martín, Víctor S

    2016-01-01

    Summary An improved protocol for the synthesis of enantiomerically pure allylic amines is reported. N-Protected α-amino esters derived from natural amino acids were submitted to a one-pot tandem reduction–olefination process. The sequential reduction with DIBAL-H at −78 °C and subsequent in situ addition of organophosphorus reagents yielded the corresponding allylic amines without the need to isolate the intermediate aldehyde. This circumvents the problem of instability of the aldehydes. The method tolerates well both Wittig and Horner–Wadsworth–Emmons organophosphorus reagents. A better Z-(dia)stereoselectivity was observed when compared to the previous one-pot method. The (dia)stereoselectivity of the process was affected neither by the reaction solvent nor by the amount of DIBAL-H employed. The method is compatible with the presence of free hydroxy groups as shown with serine and threonine derivatives. PMID:27340486

  19. Crystal structure of (Z-3-allyl-5-(3-bromobenzylidene-2-sulfanylidene-1,3-thiazolidin-4-one

    Directory of Open Access Journals (Sweden)

    Rahhal El Ajlaoui

    2015-12-01

    Full Text Available In the title compound, C13H10BrNOS2, the rhodanine (systematic name: 2-sulfanylidene-1,3-thiazolidin-4-one and the 3-bromobenzylidene ring systems are inclined slightly, forming a dihedral angle of 5.86 (12°. The rhodanine moiety is linked to an allyl group at the N atom and to the 3-bromobenzylidene ring system. The allyl group, C=C—C, is nearly perpendicular to the mean plane through the rhodanine ring, maling a dihedral angle of 87.2 (5°. In the crystal, molecules are linked by pairs of C—H...O hydrogen bonds, forming inversion dimers with an R22(10 ring motif.

  20. Method for the Determination of Carbonyl Compounds in E-Cigarette Aerosols

    Science.gov (United States)

    Flora, Jason W.; Wilkinson, Celeste T.; Wilkinson, James W.; Lipowicz, Peter J.; Skapars, James A.; Anderson, Adam; Miller, John H.

    2017-01-01

    Low levels of thermal degradation products such as carbonyls (formaldehyde, acetaldehyde, acrolein, crotonaldehyde) have been reported in e-cigarette aerosols. The collection and analysis of e-cigarette aerosol carbonyls are often adapted from methods developed for tobacco cigarette smoke. These methodologies are often not sensitive enough to detect low carbonyl levels in e-cigarette aerosols. One objective of this work was to develop and validate a rapid, selective and sensitive ultra-performance liquid chromatography with mass spectrometry method optimized for analysis of carbonyls in e-cigarette aerosols. Aerosols were trapped in 20-puff collections, 4-s durations, 55-mL volumes, 30-s intervals, square wave puff profiles. Collection apparatus involved a linear smoking machine with Cambridge filter pad followed by a glass impinger containing acidified 2,4-dinitrophenylhydrazine. This method showed limits of quantitation and detection of 0.016 and 0.003 µg puff−1, respectively, and run time of 4 min. Six e-cigarettes were evaluated (five devices each). All contained measurable levels of carbonyls. Levels were mostly well below those in conventional cigarettes. However, for some e-cigarettes, formaldehyde levels were above those for tobacco cigarettes (highest at 14.1 µg puff−1). Temperatures related to carbonyl yields in e-cigarette aerosols were explored to better understand carbonyl formation: formation of formaldehyde is low at temperatures below 350°C. PMID:28087758

  1. Electroless plating preparation and electromagnetic properties of Co-coated carbonyl iron particles/polyimide composite

    Science.gov (United States)

    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.

  2. Formation of Carbonyl and Carboxyl Groups on Cellulosic Pulps: Effect on Alkali Resistance

    Directory of Open Access Journals (Sweden)

    Jordan Perrin

    2014-10-01

    Full Text Available Ozone bleaching generates carbonyl groups on the cellulose polymer when applied to unbleached kraft pulps. This suggests that pulp fully bleached with a totally chlorine-free (TCF sequence may contain more oxidized groups than standard elemental chlorine-free (ECF bleached pulp. A fully bleached pulp was treated with sodium hypochlorite to form oxidized groups (mostly carbonyls on the pure carbohydrates, which were investigated during subsequent alkaline treatment. Carbonyl groups had a strong impact on color development during alkaline treatment. Among the carbonyls, the keto groups were the most active. This was confirmed by the behavior of carbohydrate model compounds that contained aldehyde, keto, and/or carboxyl groups when subjected to alkaline conditions. A subsequent hydrogen peroxide (P stage effectively decreased the carbonyl content, which reduced yellowing during alkaline treatment. However, the oxidized cellulose was severely depolymerized. The addition of magnesium sulfate (Mg into the P stage minimized depolymerization while maintaining some of the carbonyls in the carbohydrates. It is proposed that Mg cations can hinder alkaline β-elimination, possibly by forming a complex with the carbonyl groups.

  3. Paraquat exposure and Sod2 knockdown have dissimilar impacts on the Drosophila melanogaster carbonylated protein proteome.

    Science.gov (United States)

    Narayanasamy, Suresh K; Simpson, David C; Martin, Ian; Grotewiel, Mike; Gronert, Scott

    2014-11-01

    Exposure to Paraquat and RNA interference knockdown of mitochondrial superoxide dismutase (Sod2) are known to result in significant lifespan reduction, locomotor dysfunction, and mitochondrial degeneration in Drosophila melanogaster. Both perturbations increase the flux of the progenitor ROS, superoxide, but the molecular underpinnings of the resulting phenotypes are poorly understood. Improved understanding of such processes could lead to advances in the treatment of numerous age-related disorders. Superoxide toxicity can act through protein carbonylation. Analysis of carbonylated proteins is attractive since carbonyl groups are not present in the 20 canonical amino acids and are amenable to labeling and enrichment strategies. Here, carbonylated proteins were labeled with biotin hydrazide and enriched on streptavidin beads. On-bead digestion was used to release carbonylated protein peptides, with relative abundance ratios versus controls obtained using the iTRAQ MS-based proteomics approach. Western blotting and biotin quantitation assay approaches were also investigated. By both Western blotting and proteomics, Paraquat exposure, but not Sod2 knockdown, resulted in increased carbonylated protein relative abundance. For Paraquat exposure versus control, the median carbonylated protein relative abundance ratio (1.53) determined using MS-based proteomics was in good agreement with that obtained using a commercial biotin quantitation kit (1.36).

  4. Variation of ambient carbonyl levels in urban Beijing between 2005 and 2012

    Science.gov (United States)

    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.

  5. Simple and Efficient Ruthenium-Catalyzed Oxidation of Primary Alcohols with Molecular Oxygen.

    Science.gov (United States)

    Ray, Ritwika; Chandra, Shubhadeep; Maiti, Debabrata; Lahiri, Goutam Kumar

    2016-06-20

    Oxidative transformations utilizing molecular oxygen (O2 ) as the stoichiometric oxidant are of paramount importance in organic synthesis from ecological and economical perspectives. Alcohol oxidation reactions that employ O2 are scarce in homogeneous catalysis and the efficacy of such systems has been constrained by limited substrate scope (most involve secondary alcohol oxidation) or practical factors, such as the need for an excess of base or an additive. Catalytic systems employing O2 as the "primary" oxidant, in the absence of any additive, are rare. A solution to this longstanding issue is offered by the development of an efficient ruthenium-catalyzed oxidation protocol, which enables smooth oxidation of a wide variety of primary, as well as secondary benzylic, allylic, heterocyclic, and aliphatic, alcohols with molecular oxygen as the primary oxidant and without any base or hydrogen- or electron-transfer agents. Most importantly, a high degree of selectivity during alcohol oxidation has been predicted for complex settings. Preliminary mechanistic studies including (18) O labeling established the in situ formation of an oxo-ruthenium intermediate as the active catalytic species in the cycle and involvement of a two-electron hydride transfer in the rate-limiting step.

  6. Allyl group as a protecting group for internucleotide phosphate and thiophosphate linkages in oligonucleotide synthesis: facile oxidation and deprotection conditions.

    Science.gov (United States)

    Manoharan, M; Lu, Y; Casper, M D; Just, G

    2000-02-10

    [reaction: see text] The allyl group, which serves as a protecting group for an internucleotide bond for both phosphates and phosphorothioates, can be easily removed by good nucleophiles under weakly basic or neutral conditions. For a practical synthesis on solid support, camphorsulfonyloxaziridine was used as the oxidizing agent for synthesizing DNA, while the Beaucage reagent was used for preparing phosphorothioate oligomers. Both types of oligonucleotides were easily deprotected by concentrated ammonium hydroxide containing 2% mercaptoethanol.

  7. Direct Conversion of Aldehydes and Ketones to Allylic Halides by a NbX(5-)[3,3] Rearrangement.

    Science.gov (United States)

    Fleming, Fraser F; Ravikumar, P C; Yao, Lihua

    2009-01-01

    Sequential addition of vinylmagnesium bromide and NbCl(5), or NbBr(5), to a series of aldehydes and ketones directly provides homologated, allylic halides. Transposition of the intermediate vinyl alkoxide is envisaged through a metalla-halo-[3,3] rearrangement with concomitant delivery of the halogen to the terminal carbon. The [3,3] rearrangement is equally effective for the conversion of a propargyllic alcohol to the corresponding allenyl bromide.

  8. Direct Conversion of Aldehydes and Ketones to Allylic Halides by a NbX5-[3,3] Rearrangement

    Science.gov (United States)

    Fleming, Fraser F.; Ravikumar, P. C.; Yao, Lihua

    2009-01-01

    Sequential addition of vinylmagnesium bromide and NbCl5, or NbBr5, to a series of aldehydes and ketones directly provides homologated, allylic halides. Transposition of the intermediate vinyl alkoxide is envisaged through a metalla-halo-[3,3] rearrangement with concomitant delivery of the halogen to the terminal carbon. The [3,3] rearrangement is equally effective for the conversion of a propargyllic alcohol to the corresponding allenyl bromide. PMID:20046989

  9. Synchrotron Photoionization Mass Spectrometry Measurements of Kinetics and Product Formation in the Allyl Radical (H2CCHCH2)Self Reaction

    Science.gov (United States)

    Selby, Talitha M.; Melini, giovanni; Goulay, Fabien; Leone, Stephen R.; Fahr, Askar; Taatjes, Craig A.; Osborn, David L.

    2008-01-01

    Product channels for the self-reaction of the resonance-stabilized allyl radical, C3H5 + C3H5, have been studied with isomeric specificity at temperatures from 300-600 K and pressures from 1-6 Torr using time-resolved multiplexed photoionization mass spectrometry. Under these conditions 1,5-hexadiene was the only C6H10 product isomer detected. The lack of isomerization of the C6H10 product is in marked contrast to the C6H6 product in the related C3H3 + C3H3 reaction, and is due to the more saturated electronic structure of the C6H10 system. The disproportionation product channel, yielding allene + propene, was also detected, with an upper limit on the branching fraction relative to recombination of 0.03. Analysis of the allyl radical decay at 298 K yielded a total rate coefficient of (2.7 +/- 0.8) x 10(exp -11) cu cm/molecule/s, in good agreement with pre.vious experimental measurements using ultraviolet kinetic absorption spectroscopy and a recent theoretical determination using variable reaction coordinate transition state theory. This result provides independent indirect support for the literature value of the allyl radical ultraviolet absorption cross-section near 223 nm.

  10. Visible Light-Induced Carbonylation Reactions with Organic Dyes as the Photosensitizers.

    Science.gov (United States)

    Peng, Jin-Bao; Qi, Xinxin; Wu, Xiao-Feng

    2016-09-01

    Dyes can CO do it: Organic dyes and pigments are usually applied in textile dyeing, which can be dated back to the Neolithic period. Interestingly, the possibility to use organic dyes as photoredox catalysts has also been noticed by organic chemists and applied in organic synthesis. Carbonylation reactions as a powerful procedure in carbonyl-containing compound preparation have also been studied. In this manuscript, the recent achievements in using organic dyes as visible-light sensitizers in carbonylation chemistry are summarized and discussed.

  11. Rovibrational Spectroscopy of Aluminum Carbonyl Clusters in Helium Nanodroplets

    Science.gov (United States)

    Liang, T.; Morrison, A. M.; Flynn, S. D.; Douberly, G. E.

    2011-06-01

    Helium nanodroplet isolation and a tunable quantum cascade laser are used to probe the fundamental CO stretch bands of Aluminum Carbonyl complexes, Al-(CO)N (n ≤ 5). The droplets are doped with single aluminum atoms via the resistive heating of an aluminum wetted tantalum wire. The downstream sequential pick-up of CO molecules leads to the rapid formation and cooling of Al-(CO)N clusters within the droplets. Near 1900 Cm-1, rotational fine structure is resolved in bands that are assigned to the CO stretch of a 2Π1/2 linear Al-CO species, and the asymmetric and symmetric CO stretch vibrations of a planar C2v Al-(CO)2 complex in a 2B1 electronic state. Bands corresponding to clusters with n ≥ 3 lack resolved rotational fine structure; nevertheless, the small frequency shifts from the n=2 bands indicate that these clusters consist of an Al-(CO)2 core with additional CO molecules attached via van-der-Waals interactions. A second n=2 band is observed near the CO stretch of Al-CO, indicating a local minimum on the n=2 potential consisting of an ``unreacted" Al-CO-(CO) cluster. The linewidth of this band is ˜0.5 cm-1, which is over 50 times broader than transitions within the Al-CO band. The additional broadening is consistent with a homogeneous mechanism corresponding to a rapid vibrational excitation induced reaction within the Al-CO-(CO) cluster to form the covalently bonded Al-(CO)2 complex. For the n=1,2 complexes, CCSD(T) calculations and Natural Bond Orbital (NBO) analyses are carried out to investigate the nature of the bonding in these complexes. The NBO calculations show that both π ``back" donation (from the occupied aluminum p-orbital into the π antibonding CO orbital) and σ donation (from CO into the empty aluminum p-orbitals) play a significant role in the bonding, analogous to transition metal carbonyl complexes. The large redshift of the CO stretch vibrations is consistent with this bonding analysis.

  12. Density functional theory study of the carbonyl-ene reaction of encapsulated formaldehyde in Cu(I), Ag(I), and Au(I) exchanged FAU zeolites.

    Science.gov (United States)

    Wannakao, Sippakorn; Khongpracha, Pipat; Limtrakul, Jumras

    2011-11-17

    Carbonyl-ene reactions, which involve C-C bond formation, are essential in many chemical syntheses. The formaldehyde-propene reaction catalyzed by several of the group 11 metal cations, Cu(+), Ag(+), and Au(+) exchanged on the faujasite zeolite (metal-FAU) has been investigated by density functional theory at the M06-L/6-31G(d,p) level. The Au-FAU exhibits a higher activity than the others due to the high charge transfer between the Au and the reactant molecules, even though it is located at a negatively charged site of the zeolite. This site enables it to compensate for the charge of the Au(+) ion. The NBO analysis reveals that the 6s orbital of the Au atom plays an important role, inducing a charge on the probe molecules. Moreover, the effect of the zeolite framework makes the Au-FAU more active than the others by stabilizing the high charge induced transition structure. The activation energy of the reaction catalyzed by Au-FAU is 13.0 kcal/mol whereas that of Cu and Ag-FAU is found to be around 17 kcal/mol. The product desorption needs to be improved for Au-FAU; however, we suggest that catalysts with high charge transfer might provide a promising activity.

  13. 烯丙基酚醛树脂的固化动力学%Curing Kinetics of Allyl Phenolic Resin

    Institute of Scientific and Technical Information of China (English)

    刘洋; 刘诗薇; 李志强; 于景坤

    2012-01-01

    The curing behavior of allyl phenolic resin was analyzed at different heating rates using differential scanning calorimetry.The obtained kinetic data were treated by Kissinger and KAS(Kissinger-Akahira-Sunose) methods to obtain the curing reaction kinetic parameters.A curing kinetics model was established for allyl phenolic resin.Compared with phenolic resin,the curing temperature of allyl phenolic resin is higher,the reaction order is closer to 1,and the average activation energy of the curing reaction is lower,111.45 kJ/mol.The activation energy of allyl phenolic resin is almost constant and changes little with temperature in the curing process.The curing kinetics model of allyl phenolic resin provides a theoretical basis for the study of curing process parameters.%利用差示扫描量热法分析了烯丙基酚醛树脂在不同升温速率下的固化行为,用Kissinger法和KAS(Kissinger-Akahira-Sunose)法对获得的动力学数据进行处理,得到了固化反应动力学参数,并建立了烯丙基酚醛树脂的固化动力学模型.结果表明:与纯酚醛树脂相比,烯丙基酚醛树脂固化温度较高,反应级数更接近于1,固化反应所需的平均表观活化能较低,为111.45kJ/mol;在整个固化过程中,烯丙基酚醛树脂的活化能较为恒定,随温度变化不大;烯丙基酚醛树脂固化动力学模型为研究该体系固化工艺参数提供了理论依据.

  14. Mechanism of heterogeneous reaction of carbonyl sulfide on magnesium oxide.

    Science.gov (United States)

    Liu, Yongchun; He, Hong; Xu, Wenqing; Yu, Yunbo

    2007-05-24

    Heterogeneous reaction of carbonyl sulfide (OCS) on magnesium oxide (MgO) under ambient conditions was investigated by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), quadrupole mass spectrometer (QMS), and density functional theory (DFT) calculations. It reveals that OCS can be catalytically hydrolyzed by surface hydroxyl on MgO to produce carbon dioxide (CO2) and hydrogen sulfide (H2S), and then H2S can be further catalytically oxidized by surface oxygen or gaseous oxygen on MgO to form sulfite (SO3(2-)) and sulfate (SO4(2-)). Hydrogen thiocarbonate (HSCO2-) was found to be the crucial intermediate. Surface hydrogen sulfide (HS), sulfur dioxide (SO2), and surface sulfite (SO3(2-)) were also found to be intermediates for the formation of sulfate. Furthermore, the surface hydroxyl contributes not only to the formation of HSCO2- but also to HSCO2- decomposition. On the basis of experimental results, the heterogeneous reaction mechanism of OCS on MgO was discussed.

  15. Thermal characterization of magnetically aligned carbonyl iron/agar composites.

    Science.gov (United States)

    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.

  16. Photodecomposition of Molybdenum andTungsten Carbonyl Complexes

    Directory of Open Access Journals (Sweden)

    Thamer A. Alwani

    2009-01-01

    Full Text Available The photodecomposition of four different colored organometallic molybdenum and tungsten carbonyl complexes, i.e. [Mo(CO52LA] (complex I, [(Mo(CO3(bipy2LB] (complex II, [(W(CO3(tmen2LB] (complex III and [Mo(CO2LC]2 (complex I V where LA 2-phenyl-1,3-indandionebis(2-methyl anilines, LB 2-phenyl-1,3-indandione bis (4-hydroxy anilines and LCbis (2-hydroxo-benzalydine benzidine ion have been performed at 365 nm in chloroform at 25 °C under oxygen atmosphere. The absorbance spectrum of these complexes has been recorded with the time of irradiation in order to examine the kinetics of photodecomposition. The rate of the photodecomposition process was investigated and the relative values of the rate constants of dissociation (Kd for the first-order reaction are tabulated. The apparent rate constant of photodecomposition was found to be (8.33-11.50 × 10-5 s-1.

  17. Tropical sources and sinks of carbonyl sulfide observed from space

    Science.gov (United States)

    Glatthor, Norbert; Höpfner, Michael; Baker, Ian T.; Berry, Joe; Campbell, Elliott; Kawa, Stephan R.; Krysztofiak, Gisele; Sinnhuber, Björn-Martin; Stiller, Gabriele; Stinecipher, Jim; von Clarmann, Thomas

    2016-04-01

    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 co-tracer 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 (MIPAS) 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 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 is assumed.

  18. The oceanic cycle and global atmospheric budget of carbonyl sulfide

    Energy Technology Data Exchange (ETDEWEB)

    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.

  19. Carbonyl Sulfide for Tracing Carbon Fluxes Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, J. Elliott [Univ. of California, Merced, CA (United States); Berry, Joseph A. [Carnegie Inst. of Science, Stanford, CA (United States); Billesbach, Dave [Univ. of Nebraska, Lincoln, NE (United States); Torn, Margaret S [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Zahniser, Mark [Aerodyne Research, Inc., Billerica, MA (United States); Seibt, Ulrike [Univ. of California, Los Angeles, CA (United States); Maseyk, Kadmiel [Pierre and Marie Curie Univ., Paris (France)

    2016-04-01

    The April-June 2012 campaign was located at the U.S. Department of Energy (DOE)’s Atmospheric Radiation Measurement (ARM) Climate Research Facility Southern Great Plains (SGP) site Central Facility and had three purposes. One goal was to demonstrate the ability of current instrumentation to correctly measure fluxes of atmospheric carbonyl sulfide (COS). The approach has been describe previously as a critical approach to advancing carbon cycle science1,2, but requires further investigation at the canopy scale to resolve ecosystem processes. Previous canopy-scale efforts were limited to data rates of 1Hz. While 1 Hz measurements may work in a few ecosystems, it is widely accepted that data rates of 10 to 20 Hz are needed to fully capture the exchange of traces gases between the atmosphere and vegetative canopy. A second goal of this campaign was to determine if canopy observations could provide information to help interpret the seasonal double peak in airborne observations at SGP of CO2 and COS mixing ratios. A third goal was to detect potential sources and sinks of COS that must be resolved before using COS as a tracer of gross primary productivity (GPP).

  20. Regional-Scale Carbon Flux Partitioning Using Atmospheric Carbonyl Sulfide

    Science.gov (United States)

    Abu-Naser, M.; Campbell, J. E.; Berry, J. A.

    2011-12-01

    Simultaneous analysis of atmospheric concentrations of carbonyl sulfide (COS) and carbon dioxide (CO2) has been proposed as an approach to partitioning gross primary production and respiration fluxes at regional and global scales. The basis for this approach was that the observation and regional gradients in atmospheric CO2 are dominated by net ecosystem fluxes while regional gradients in atmospheric COS are dominated by GPP-related plant uptake. Here we investigate the spatial and temporal gradients in airborne COS and CO2 measurements in comparison to flux estimates from ecosystem models and eddy covariance methods over North America. The spatial gradients in the ecosystem relative uptake (ERU), the normalized ratio of COS and CO2 vertical gradients, were consistent with the theoretical relationship to flux estimates from ecosystem models and eddy covariance methods. The seasonality of the gross primary productivity flux estimates was consistent with airborne observations in the midwestern region but had mixed results in the southeastern region. Inter-annual changes in the ERU and regional drought index data suggested a potential relationship between drought stress and low ratios of gross primary production to net ecosystem exchange.

  1. Heterogeneous oxidation of carbonyl sulfide on mineral oxides

    Institute of Scientific and Technical Information of China (English)

    LIU YongChun; LIU JunFeng; HE Hong; YU YunBo; XUE Li

    2007-01-01

    Heterogeneous oxidation of carbonyl sulfide (OCS) on mineral oxides including SiO2, Fe2O3, CaO, MgO, ZnO and TiO2, which are the main components of atmospheric particles, were investigated using in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS), ion chromatography (IC), temperature-programmed desorption (TPD), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) methods. The main products and intermediates of the heterogeneous oxidation of OCS on these oxides were identified with in situ DRIFTS and IC. The reaction mechanism and kinetics were also discussed. It is found that the reaction mechanism on these mineral oxides is the same as that on Al2O3 for the same final products and the intermediates at room temperature. Namely, OCS can be catalytically oxidized to produce surface SO42- species and gaseous CO2 through the surface hydrogen thiocarbonate (HSCO2-) and HSO3- species. The activity series for heterogeneous oxidation of OCS follows: Al2O3 ≈ CaO>MgO>TiO2 ≈ ZnO>Fe2O3>SiO2. The specific area, basic hydroxyl and surface basicity of these oxides have effect on the reactivity. This study suggests that heterogeneous reactions of OCS on mineral dust may be an unneglectable sink of OCS.

  2. Teratogenicity and embryotoxicity of nickel carbonyl in Syrian hamsters

    Energy Technology Data Exchange (ETDEWEB)

    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.

  3. Carbonyl sulfide uptake and chloroform emissions from an Arctic site

    Science.gov (United States)

    Elkins, J. W.; Dutton, G. S.; Montzka, S. A.; Nance, J. D.; Hall, B. D.; Thoning, K. W.; Miller, J. B.; White, J.; Vaugh, B.; Manning, A.

    2008-12-01

    The Arctic Region is most sensitive to future climate change. Quantifying emissions and sinks of many important biogenic trace gases there may become important indicators of potential climate feedback. Once snowmelt at Pt. Barrow, Alaska (77o N) occurs, ground cover is exposed by sunlight and higher temperatures, then photosynthesis starts up. Peaks of chloroform (CHCl3) appear throughout the summer from southerly-based air masses based over northern Alaska and northwest Canada. Carbonyl sulfide (COS) undergoes uptake throughout the summer season through the same enzymes that uptake carbon dioxide (CO2). We will calculate the footprint of emissions of CHCl3 and uptake of COS using high frequency in situ observations, and the NAME and FLEXPART models. Previous studies show a large source of CHCl3 (8% of the total budget) may be coming from soils in high latitude pine forests. We will examine emissions of CHCl3 to see whether or not they are coming from the tundra just south of Pt. Barrow. We will identify the regions for uptake of COS and CO2 from the footprint generated from the models.

  4. Degradation of ambient carbonyl sulfide by Mycobacterium spp. in soil.

    Science.gov (United States)

    Kato, Hiromi; Saito, Masahiko; Nagahata, Yoshiko; Katayama, Yoko

    2008-01-01

    The ability to degrade carbonyl sulfide (COS) was confirmed in seven bacterial strains that were isolated from soil, without the addition of COS. Comparative 16S rRNA gene sequence analysis indicated that these isolates belonged to the genera Mycobacterium, Williamsia and Cupriavidus. For example, Mycobacterium sp. strain THI401, grown on PYG agar medium, was able to degrade an initial level of 30 parts per million by volume COS within 1 h, while 60 % of the initial COS was decreased by abiotic conversion in 30 h. Considering natural COS flux between soil and the atmosphere, COS degradation by these bacteria was confirmed at an ambient level of 500 parts per trillion by volume (p.p.t.v.), using sterilized soil to cultivate the bacterium. Autoclave sterilization of soil resulted in a small amount of COS emission, while Mycobacterium spp. degraded COS at a faster rate than it was emitted from the soil, and reduced the COS mixing ratio to a level that was lower than the ambient level: THI401 degraded COS from an initial level of 530 p.p.t.v. to a level of 330 p.p.t.v. in 30 h. These results provide experimental evidence of microbial activity in soil as a sink for atmospheric COS.

  5. Comparison of sampling methods for radiocarbon dating of carbonyls in air samples via accelerator mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Schindler, Matthias, E-mail: matthias.schindler@physik.uni-erlangen.de; Kretschmer, Wolfgang; Scharf, Andreas; Tschekalinskij, Alexander

    2016-05-15

    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 CO{sub 2} and reduced to graphite to determine {sup 14}C 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).

  6. Comparison of sampling methods for radiocarbon dating of carbonyls in air samples via accelerator mass spectrometry

    Science.gov (United States)

    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).

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

    Directory of Open Access Journals (Sweden)

    Himan Heidari

    2016-03-01

    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.

  8. A carbonyl iron/carbon fiber material for electromagnetic wave absorption.

    Science.gov (United States)

    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.

  9. Corrosion inhibition of α,β-unsaturated carbonyl compounds on steel in acid medium

    Institute of Scientific and Technical Information of China (English)

    Gao Jiancun; Weng Yongji; Salitanate; Feng Li; Yue Hong

    2009-01-01

    Corrosion inhibition of three α,β-unsaturated carbonyl compounds on N80 steel at high temperature and in concentrated acid medium was evaluated, and the inhibition mechanism was investigated.The results proved that both cinnamaidehyde and benzalacetone had an evident anticorrosion effect and could reduce the corrosion of steel effectively in acid medium, α,β-unsaturated carbonyl compounds with a benzene ring structure had good adsorption on steel surface.The experiments proved that polymerization of α,β-unsaturated carbonyl compounds on the steel surface at a high temperature and in concentrated acid medium resulted in a good corrosion inhibiting effect, which was attributed to the structures of α,β-unsaturated carbonyl compounds.

  10. Incorporating Cobalt Carbonyl Moieties onto Ethynylthiophene-Based Dithienylcyclopentene Switches. 1. Photochemistry

    NARCIS (Netherlands)

    Harvey, Emma C.; Areephong, Jetsuda; Cafolla, Attilio A.; Long, Conor; Browne, Wesley R.; Pryce, Mary T.; Feringa, Bernard

    2014-01-01

    The synthesis and characterization of a series of dithienyl perhydro- and perfluorocyclopentene photochromic molecular switches appended with cobalt carbonyl binding 3-ethynylthiophene and phenyl-3-ethynylthiophene substituents are reported. Their photochromic properties, fatigue resistance, and the

  11. On the antioxidant, neuroprotective and anti-inflammatory properties of S-allyl cysteine: An update.

    Science.gov (United States)

    Colín-González, Ana Laura; Ali, Syed F; Túnez, Isaac; Santamaría, Abel

    2015-10-01

    Therapeutic approaches based on isolated compounds obtained from natural products to handle central and peripheral disorders involving oxidative stress and inflammation are more common nowadays. The validation of nutraceutics vs. pharmaceutics as tools to induce preventive and protective profiles in human health alterations is still far of complete acceptance, but the basis to start more solid experimental and clinical protocols with natural products has already begun. S-allyl cysteine (SAC) is a promising garlic-derived organosulfur compound exhibiting a considerable number of positive actions in cell models and living systems. An update, in the form of review, is needed from time to time to get access to the state-of-the-art on this topic. In this review we visited recent and refreshing evidence of new already proven and potential targets to explain the benefits of using SAC against toxic and pathological conditions. The broad spectrum of protective actions covered by this molecule comprises antioxidant, redox modulatory and anti-inflammatory activities, accompanied by anti-apoptotic, pro-energetic and signaling capacities. Herein, we detail the evidence on these aspects to provide the reader a more complete overview on the promising aspects of SAC in research.

  12. Merging allylic carbon-hydrogen and selective carbon-carbon bond activation

    Science.gov (United States)

    Masarwa, Ahmad; Didier, Dorian; Zabrodski, Tamar; Schinkel, Marvin; Ackermann, Lutz; Marek, Ilan

    2014-01-01

    Since the nineteenth century, many synthetic organic chemists have focused on developing new strategies to regio-, diastereo- and enantioselectively build carbon-carbon and carbon-heteroatom bonds in a predictable and efficient manner. Ideal syntheses should use the least number of synthetic steps, with few or no functional group transformations and by-products, and maximum atom efficiency. One potentially attractive method for the synthesis of molecular skeletons that are difficult to prepare would be through the selective activation of C-H and C-C bonds, instead of the conventional construction of new C-C bonds. Here we present an approach that exploits the multifold reactivity of easily accessible substrates with a single organometallic species to furnish complex molecular scaffolds through the merging of otherwise difficult transformations: allylic C-H and selective C-C bond activations. The resulting bifunctional nucleophilic species, all of which have an all-carbon quaternary stereogenic centre, can then be selectively derivatized by the addition of two different electrophiles to obtain more complex molecular architecture from these easily available starting materials.

  13. Allyl functionalized phosphinite and phosphonite ligands: Synthesis, transition metal chemistry and orthopalladation reactions

    Indian Academy of Sciences (India)

    Singappagudem Govindaraju; Guddekoppa S Ananthnag; Susmita Naik; Shaikh M Mobin; Maravanji S Balakrishn

    2012-07-01

    Allyl functionalized phosphinite PPh2(OAr) [Ar=C6H4(-C3H5)] (1) and phosphonite PPh(OAr)2 (2) ligands were prepared by the reactions of 2-allylphenol with PPh2Cl and PPhCl2, respectively. The ruthenium(II) complexes, [Ru(6--cymene)(PPh2(OAr))Cl2] (3) and [Ru(6--cymene)(PPh(OAr)2Cl2)] (4) were obtained by reacting 1 or 2 with [Ru(6--cymene)Cl2]2 in 2:1 molar ratios, respectively. Reactions of 1 or 2 with AuCl(SMe2) gave [Au{PPh2(OAr)}Cl] (5) or [Au{PPh(OAr)2}Cl] (6) in good yield. The palladium complex, [Pd{PPh(OAr)2}2Cl2] (7) was prepared by reacting Pd(COD)Cl2 with 2 in 1:2 molar ratio. The reaction between Pd(COD)Cl2 and 1 yielded a mixture of orthopalladated cis- and trans-[Pd(Ph2P(OAr))Cl]2 (8a and 8b). The treatment of 8 with PPh3 and Ph2PCH2PPh2 resulted in the cleavage of chloro bridge to give respectively, [Ph2(OAr)PPd(PPh3)Cl] (9) and [Ph2(ArO)PPd(2-dppm)]OTf (10). Single crystal X-ray structure of the ruthenium complex 3 is described.

  14. Release and antibacterial activity of allyl isothiocyanate/β-cyclodextrin complex encapsulated in electrospun nanofibers.

    Science.gov (United States)

    Aytac, Zeynep; Dogan, Sema Y; Tekinay, Turgay; Uyar, Tamer

    2014-08-01

    Allyl isothiocyanate (AITC) is known as an efficient antibacterial agent but it has a very high volatility. Herein, AITC and AITC/β-cyclodextrin (CD)-inclusion complex (IC) incorporated in polyvinyl alcohol (PVA) nanofibers were produced via electrospinning. SEM images elucidated that incorporation of AITC and AITC/β-CD-IC into polymer matrix did not affect the bead-free fiber morphology of PVA nanofibers. (1)H-NMR and headspace GC-MS analyses revealed that very low amount of AITC was remained in PVA/AITC-NF because of the rapid evaporation of AITC during the electrospinning process. Nevertheless, much higher amount of AITC was preserved in the PVA/AITC/β-CD-IC-NF due to the CD inclusion complexation. The sustained release of AITC from nanofibers was evaluated at 30°C, 50°C and 75°C via headspace GC-MS. When compared to PVA/AITC-NF, PVA/AITC/β-CD-IC-NF has shown higher antibacterial activity against Escherichia coli and Staphylococcus aureus due to the presence of higher amount of AITC in this sample which was preserved by CD-IC.

  15. Synergistic effect of allyl isothiocyanate (AITC) on cisplatin efficacy in vitro and in vivo.

    Science.gov (United States)

    Ling, Xiang; Westover, David; Cao, Felicia; Cao, Shousong; He, Xiang; Kim, Hak-Ryul; Zhang, Yuesheng; Chan, Daniel Cf; Li, Fengzhi

    2015-01-01

    Although in vitro studies have shown that isothiocyanates (ITCs) can synergistically sensitize cancer cells to cisplatin treatment, the underlying mechanisms have not been well defined, and there are no in vivo demonstrations of this synergy. Here, we report the in vitro and in vivo data for the combination of allyl isothiocyanate (AITC), one of the most common naturally occurring ITCs, with cisplatin. Our study revealed that cisplatin and AITC combination synergistically inhibits cancer cell growth and colony formation, and enhances apoptosis in association with the downregulation of antiapoptotic proteins Bcl-2 and survivin. Importantly, the in vivo combination treatment suppresses human tumor growth in animal models without observable increases in toxicity (body weight loss) in comparison with single agent treatment. Furthermore, our data revealed that addition of AITC to cisplatin treatment changes the profile of G2/M arrest (e.g. increase in M phase cell number) and significantly extends the duration of G2/M arrest in comparison with cisplatin treatment alone. To explore the underlying mechanism, we found that AITC treatment rapidly depletes b-tubulin. Combination of AITC and cisplatin inhibits the expression of G2/M checkpoint-relevant proteins including CDC2, cyclin B1 and CDC25. Together, our findings reveal a novel mechanism for AITC enhancing cisplatin efficacy and provides the first in vivo evidence to support ITCs as potential candidates for developing new regimens to overcome platinum resistance.

  16. Pharmacokinetics, Tissue Distribution, and Anti-Lipogenic/Adipogenic Effects of Allyl-Isothiocyanate Metabolites.

    Directory of Open Access Journals (Sweden)

    Yang-Ji Kim

    Full Text Available Allyl-isothiocyanate (AITC is an organosulfur phytochemical found in abundance in common cruciferous vegetables such as mustard, wasabi, and cabbage. Although AITC is metabolized primarily through the mercapturic acid pathway, its exact pharmacokinetics remains undefined and the biological function of AITC metabolites is still largely unknown. In this study, we evaluated the inhibitory effects of AITC metabolites on lipid accumulation in vitro and elucidated the pharmacokinetics and tissue distribution of AITC metabolites in rats. We found that AITC metabolites generally conjugate with glutathione (GSH or N-acetylcysteine (NAC and are distributed in most organs and tissues. Pharmacokinetic analysis showed a rapid uptake and complete metabolism of AITC following oral administration to rats. Although AITC has been reported to exhibit anti-tumor activity in bladder cancer, the potential bioactivity of its metabolites has not been explored. We found that GSH-AITC and NAC-AITC effectively inhibit adipogenic differentiation of 3T3-L1 preadipocytes and suppress expression of PPAR-γ, C/EBPα, and FAS, which are up-regulated during adipogenesis. GSH-AITC and NAC-AITC also suppressed oleic acid-induced lipid accumulation and lipogenesis in hepatocytes. Our findings suggest that AITC is almost completely metabolized in the liver and rapidly excreted in urine through the mercapturic acid pathway following administration in rats. AITC metabolites may exert anti-obesity effects through suppression of adipogenesis or lipogenesis.

  17. Allyl Isothiocyanate Inhibits Actin-Dependent Intracellular Transport in Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Bjørnar Sporsheim

    2015-12-01

    Full Text Available Volatile allyl isothiocyanate (AITC derives from the biodegradation of the glucosinolate sinigrin and has been associated with growth inhibition in several plants, including the model plant Arabidopsis thaliana. However, the underlying cellular mechanisms of this feature remain scarcely investigated in plants. In this study, we present evidence of an AITC-induced inhibition of actin-dependent intracellular transport in A. thaliana. A transgenic line of A. thaliana expressing yellow fluorescent protein (YFP-tagged actin filaments was used to show attenuation of actin filament movement by AITC. This appeared gradually in a time- and dose-dependent manner and resulted in actin filaments appearing close to static. Further, we employed four transgenic lines with YFP-fusion proteins labeling the Golgi apparatus, endoplasmic reticulum (ER, vacuoles and peroxisomes to demonstrate an AITC-induced inhibition of actin-dependent intracellular transport of or, in these structures, consistent with the decline in actin filament movement. Furthermore, the morphologies of actin filaments, ER and vacuoles appeared aberrant following AITC-exposure. However, AITC-treated seedlings of all transgenic lines tested displayed morphologies and intracellular movements similar to that of the corresponding untreated and control-treated plants, following overnight incubation in an AITC-absent environment, indicating that AITC-induced decline in actin-related movements is a reversible process. These findings provide novel insights into the cellular events in plant cells following exposure to AITC, which may further expose clues to the physiological significance of the glucosinolate-myrosinase system.

  18. Allyl m-Trifluoromethyldiazirine Mephobarbital: An Unusually Potent Enantioselective and Photoreactive Barbiturate General Anesthetic

    Energy Technology Data Exchange (ETDEWEB)

    Savechenkov, Pavel Y.; Zhang, Xi; Chiara, David C.; Stewart, Deirdre S.; Ge, Rile; Zhou, Xiaojuan; Raines, Douglas E.; Cohen, Jonathan B.; Forman, Stuart A.; Miller, Keith W.; Bruzik, Karol S. (Harvard-Med); (Mass. Gen. Hosp.); (UIC)

    2012-12-10

    We synthesized 5-allyl-1-methyl-5-(m-trifluoromethyl-diazirynylphenyl)barbituric acid (14), a trifluoromethyldiazirine-containing derivative of general anesthetic mephobarbital, separated the racemic mixture into enantiomers by chiral chromatography, and determined the configuration of the (+)-enantiomer as S by X-ray crystallography. Additionally, we obtained the {sup 3}H-labeled ligand with high specific radioactivity. R-(-)-14 is an order of magnitude more potent than the most potent clinically used barbiturate, thiopental, and its general anesthetic EC{sub 50} approaches those for propofol and etomidate, whereas S-(+)-14 is 10-fold less potent. Furthermore, at concentrations close to its anesthetic potency, R-(-)-14 both potentiated GABA-induced currents and increased the affinity for the agonist muscimol in human {alpha}1{beta}2/3{gamma}2L GABA{sub A} receptors. Finally, R-(-)-14 was found to be an exceptionally efficient photolabeling reagent, incorporating into both {alpha}1 and {beta}3 subunits of human {alpha}1{beta}3 GABAA receptors. These results indicate R-(-)-14 is a functional general anesthetic that is well-suited for identifying barbiturate binding sites on Cys-loop receptors.

  19. Copper-Catalyzed Carbenoid Insertion Reactions of α-Diazoesters and α-Diazoketones into Si-H and S-H Bonds.

    Science.gov (United States)

    Keipour, Hoda; Jalba, Angela; Delage-Laurin, Léo; Ollevier, Thierry

    2017-01-28

    An efficient copper-catalyzed carbenoid insertion reaction of α-diazo carbonyl compounds into Si-H and S-H bonds was developed. A wide range of α-silylesters and α-thioesters was obtained in high yields (up to 98%) from α-diazoesters using 5 mol % of a simple copper(I) salt as catalyst. Using 0.05 mol % of the same catalyst, α-diazoketones led to α-silylketones in low to good yields (up to 70%).

  20. Efficient alpha-Methylenation of Carbonyl Compounds in Ionic Liquids at Room Temperature

    OpenAIRE

    Vale, JA; Zanchetta, DF; Moran, PJS; RODRIGUES, JAR

    2009-01-01

    The application of several 1-butyl-3-methylimidazolium (BMIM) salt ionic liquids as solvent in the alpha-methylenation of carbonyl compounds at room temperature is reported. The ionic liquid [BMIM][NTf(2)] gave a clean reaction in a short time and good yields of several alpha-methylene carbonyl compounds. This ionic liquid was reused without affecting the reaction rates or yields over seven runs.

  1. Efficicent (R-phenylethanol production with enantioselectivity-alerted (S-carbonyl reductase II and NADPH regeneration.

    Directory of Open Access Journals (Sweden)

    Rongzhen Zhang

    Full Text Available The NADPH-dependent (S-carbonyl reductaseII from Candida parapsilosis catalyzes acetophenone to chiral phenylethanol in a very low yield of 3.2%. Site-directed mutagenesis was used to design two mutants Ala220Asp and Glu228Ser, inside or adjacent to the substrate-binding pocket. Both mutations caused a significant enantioselectivity shift toward (R-phenylethanol in the reduction of acetophenone. The variant E228S produced (R-phenylethanol with an optical purity above 99%, in 80.2% yield. The E228S mutation resulted in a 4.6-fold decrease in the K M value, but nearly 5-fold and 21-fold increases in the k cat and k cat/K M values with respect to the wild type. For NADPH regeneration, Bacillus sp. YX-1 glucose dehydrogenase was introduced into the (R-phenylethanol pathway. A coexpression system containing E228S and glucose dehydrogenase was constructed. The system was optimized by altering the coding gene order on the plasmid and using the Shine-Dalgarno sequence and the aligned spacing sequence as a linker between them. The presence of glucose dehydrogenase increased the NADPH concentration slightly and decreased NADP(+ pool 2- to 4-fold; the NADPH/NADP(+ ratio was improved 2- to 5-fold. The recombinant Escherichia coli/pET-MS-SD-AS-G, with E228S located upstream and glucose dehydrogenase downstream, showed excellent performance, giving (R-phenylethanol of an optical purity of 99.5 % in 92.2% yield in 12 h in the absence of an external cofactor. When 0.06 mM NADP(+ was added at the beginning of the reaction, the reaction duration was reduced to 1 h. Optimization of the coexpression system stimulated an over 30-fold increase in the yield of (R-phenylethanol, and simultaneously reduced the reaction time 48-fold compared with the wild-type enzyme. This report describes possible mechanisms for alteration of the enantiopreferences of carbonyl reductases by site mutation, and cofactor rebalancing pathways for efficient chiral alcohols production.

  2. Measurement of airborne carbonyls using an automated sampling and analysis system.

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    Aiello, Mauro; McLaren, Robert

    2009-12-01

    Based upon the well established method of derivitization with 2,4-dinitrophenylhydrazine, an instrument was developed for ambient measurement of carbonyls with significantly improved temporal resolution and detection limits through automation, direct injection, and continuous use of a single microsilica DNPH cartridge. Kinetic experiments indicate that the derivitization reaction on the cartridge is fast enough for continuous measurements with 50 min air sampling. Reaction efficiencies measured on the cartridge were 100% for the carbonyls tested, including formaldehyde, acetaldehyde, propanal, acetone, and benzaldehyde. Transmission of the carbonyls through an ozone scrubber (KI) were in the range of 97-101%. Blank levels and detection limits were lower than those obtainable with conventional DNPH methods by an order of magnitude or greater. Mixing ratio detection limits of carbonyls in ambient air were 38-73 ppt for a 50 min air sample (2.5 L). The instrument made continuous measurements of carbonyls on a 2 h cycle over a period of 10 days during a field study in southwestern Ontario. Median mixing ratios were 0.58 ppb formaldehyde; 0.29 ppb acetaldehyde; 1.14 ppb acetone; and 0.45 ppb glyoxal. Glyoxal shows a significant correlation with ozone and zero intercept, consistent with a secondary source and minor direct source to the atmosphere. The method should easily be extendable to the detection of other low molecular weight carbonyls that have been previously reported using the DNPH technique.

  3. Oxidative Stress and Carbonyl Lesions in Ulcerative Colitis and Associated Colorectal Cancer

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    Zhiqi Wang

    2016-01-01

    Full Text Available 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.

  4. Direct photolysis of carbonyl compounds dissolved in cloud and fog droplets

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    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.

  5. A biotin enrichment strategy identifies novel carbonylated amino acids in proteins from human plasma.

    Science.gov (United States)

    Havelund, Jesper F; Wojdyla, Katarzyna; Davies, Michael J; Jensen, Ole N; Møller, Ian Max; Rogowska-Wrzesinska, Adelina

    2017-03-06

    Protein carbonylation is an irreversible protein oxidation correlated with oxidative stress, various diseases and ageing. Here we describe a peptide-centric approach for identification and characterisation of up to 14 different types of carbonylated amino acids in proteins. The modified residues are derivatised with biotin-hydrazide, enriched and characterised by tandem mass spectrometry. The strength of the method lies in an improved elution of biotinylated peptides from monomeric avidin resin using hot water (95°C) and increased sensitivity achieved by reduction of analyte losses during sample preparation and chromatography. For the first time MS/MS data analysis utilising diagnostic biotin fragment ions is used to pinpoint sites of biotin labelling and improve the confidence of carbonyl peptide assignments. We identified a total of 125 carbonylated residues in bovine serum albumin after extensive in vitro metal ion-catalysed oxidation. Furthermore, we assigned 133 carbonylated sites in 36 proteins in native human plasma protein samples. The optimised workflow enabled detection of 10 hitherto undetected types of carbonylated amino acids in proteins: aldehyde and ketone modifications of leucine, valine, alanine, isoleucine, glutamine, lysine and glutamic acid (+14Da), an oxidised form of methionine - aspartate semialdehyde (-32Da) - and decarboxylated glutamic acid and aspartic acid (-30Da).

  6. Advances in lipase-catalyzed esterification reactions.

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    Stergiou, Panagiota-Yiolanda; Foukis, Athanasios; Filippou, Michalis; Koukouritaki, Maria; Parapouli, Maria; Theodorou, Leonidas G; Hatziloukas, Efstathios; Afendra, Amalia; Pandey, Ashok; Papamichael, Emmanuel M

    2013-12-01

    Lipase-catalyzed esterification reactions are among the most significant chemical and biochemical processes of industrial relevance. Lipases catalyze hydrolysis as well as esterification reactions. Enzyme-catalyzed esterification has acquired increasing attention in many applications, due to the significance of the derived products. More specifically, the lipase-catalyzed esterification reactions attracted research interest during the past decade, due to an increased use of organic esters in biotechnology and the chemical industry. Lipases, as hydrolyzing agents are active in environments, which contain a minimum of two distinct phases, where all reactants are partitioned between these phases, although their distribution is not fixed and changes as the reaction proceeds. The kinetics of the lipase-catalyzed reactions is governed by a number of factors. This article presents a thorough and descriptive evaluation of the applied trends and perspectives concerning the enzymatic esterification, mainly for biofuel production; an emphasis is given on essential factors, which affect the lipase-catalyzed esterification reaction. Moreover, the art of using bacterial and/or fungal strains for whole cell biocatalysis purposes, as well as carrying out catalysis by various forms of purified lipases from bacterial and fungal sources is also reviewed.

  7. Enantioselective Cyclopropanation of a Wide Variety of Olefins Catalyzed by Ru(II)-Pheox Complexes.

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    Chanthamath, Soda; Iwasa, Seiji

    2016-10-18

    The transition-metal-catalyzed asymmetric cyclopropanation of olefins with diazoacetates has become one of the most important methods for the synthesis of optically active cyclopropane derivatives, which are key pharmaceutical building blocks and present in a large number of natural products. To date, significant progress has been made in this area of research, and efficient stereocontrolled synthetic approaches to cyclopropane derivatives have been developed using rhodium, ruthenium, copper, and cobalt catalysts. However, the vast majority of these strategies are limited to electron-rich olefins, such as styrene derivatives, due to the electrophilicity of the metal-carbene intermediates generated from the reaction of the metal with the diazo compound. Recently, the D2-symmetric Co(II)-phophyrin complexes developed by Zhang et al. were shown to be the most efficient catalysts for the asymmetric cyclopropanation of electron-deficient olefins. This catalytic system is mechanistically distinct from the previous rhodium and copper catalytic systems, proceeding via radical intermediates. However, the asymmetric cyclopropanation of vinyl carbamates, allenes, and α,β-unsaturated carbonyl compounds has rarely been reported. Therefore, the development of new powerful catalysts for the asymmetric cyclopropanation of a wide range of olefinic substrates is the next challenge in this field. In this Account, we summarize our recent studies on the Ru(II)-Pheox-catalyzed asymmetric cyclopropanation of various olefins, including vinyl carbamates, allenes, and α,β-unsaturated carbonyl compounds. We demonstrate that the developed catalytic system effectively promotes the asymmetric cyclopropanation of a wide variety of olefins to produce the desired cyclopropane products in high yields with excellent stereocontrol. The use of succinimidyl-, ketone-, and ester-functionalized diazoacetates as carbene sources was found to be crucial for the high stereoselectivity of the

  8. Protein carbonylation, protein aggregation and neuronal cell death in a murine model of multiple sclerosis

    Science.gov (United States)

    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

  9. Fluorinated alcohols as promoters for the metal-free direct substitution reaction of allylic alcohols with nitrogenated, silylated, and carbon nucleophiles.

    Science.gov (United States)

    Trillo, Paz; Baeza, Alejandro; Nájera, Carmen

    2012-09-01

    The direct allylic substitution reaction using allylic alcohols in 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) and 2,2,2-trifluoroethanol (TFE) as reaction media is described. The developed procedure is simple, works under mild conditions (rt, 50 and 70 °C), and proves to be very general, since different nitrogenated nucleophiles and carbon nucleophiles can be used achieving high yields, especially when HFIP is employed as solvent and aromatic allylic alcohols are the substrates. Thus, sulfonamides, carbamates, carboxamides, and amines can be successfully employed as nitrogen-based nucleophiles. Likewise, silylated nucleophiles such as trimethylsilylazide, allyltrimethylsilane, trimethylsilane, and trimethylsilylphenylacetylene give the corresponding allylic substitution products in high yields. Good results for the Friedel-Crafts adducts are also achieved with aromatic compounds (phenol, anisole, indole, and anilines) as nucleophiles. Particularly interesting are the results obtained with electron-rich anilines, which can behave as nitrogenated or carbon nucleophiles depending on their electronic properties and the solvent employed. In addition, 1,3-dicarbonyl compounds (acetylacetone and Meldrum's acid) are also successfully employed as soft carbon nucleophiles. Studies for mechanism elucidation are also reported, pointing toward the existence of carbocationic intermediates and two working reaction pathways for the obtention of the allylic substitution product.

  10. Fast retrievals of tropospheric carbonyl sulfide with IASI

    Science.gov (United States)

    Vincent, R. Anthony; Dudhia, Anu

    2017-02-01

    Iterative retrievals of trace gases, such as carbonyl sulfide (OCS), from satellites can be exceedingly slow. The algorithm may even fail to keep pace with data acquisition such that analysis is limited to local events of special interest and short time spans. With this in mind, a linear retrieval scheme was developed to estimate total column amounts of OCS at a rate roughly 104 times faster than a typical iterative retrieval. This scheme incorporates two concepts not utilized in previously published linear estimates. First, all physical parameters affecting the signal are included in the state vector and accounted for jointly, rather than treated as effective noise. Second, the initialization point is determined from an ensemble of atmospheres based on comparing the model spectra to the observations, thus improving the linearity of the problem. All of the 2014 data from the Infrared Atmospheric Sounding Interferometer (IASI), instruments A and B, were analysed and showed spatial features of OCS total columns, including depletions over tropical rainforests, seasonal enhancements over the oceans, and distinct OCS features over land. Error due to assuming linearity was found to be on the order of 11 % globally for OCS. However, systematic errors from effects such as varying surface emissivity and extinction due to aerosols have yet to be robustly characterized. Comparisons to surface volume mixing ratio in situ samples taken by NOAA show seasonal correlations greater than 0.7 for five out of seven sites across the globe. Furthermore, this linear scheme was applied to OCS, but may also be used as a rapid estimator of any detectable trace gas using IASI or similar nadir-viewing instruments.

  11. Intramolecular Hydrogen Bond in Biologically Active o-Carbonyl Hydroquinones

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    Maximiliano Martínez-Cifuentes

    2014-07-01

    Full Text Available 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 LPàσ* interactions for IHBs, O1…O2-H2 and the delocalization LPàπ* 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 O2àπ* 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.

  12. Metabolism of bupropion by carbonyl reductases in liver and intestine.

    Science.gov (United States)

    Connarn, Jamie N; Zhang, Xinyuan; Babiskin, Andrew; Sun, Duxin

    2015-07-01

    Bupropion's metabolism and the formation of hydroxybupropion in the liver by cytochrome P450 2B6 (CYP2B6) has been extensively studied; however, the metabolism and formation of erythro/threohydrobupropion in the liver and intestine by carbonyl reductases (CR) has not been well characterized. The purpose of this investigation was to compare the relative contribution of the two metabolism pathways of bupropion (by CYP2B6 and CR) in the subcellular fractions of liver and intestine and to identify the CRs responsible for erythro/threohydrobupropion formation in the liver and the intestine. The results showed that the liver microsome generated the highest amount of hydroxybupropion (Vmax = 131 pmol/min per milligram, Km = 87 μM). In addition, liver microsome and S9 fractions formed similar levels of threohydrobupropion by CR (Vmax = 98-99 pmol/min per milligram and Km = 186-265 μM). Interestingly, the liver has similar capability to form hydroxybupropion (by CYP2B6) and threohydrobupropion (by CR). In contrast, none of the intestinal fractions generate hydroxybupropion, suggesting that the intestine does not have CYP2B6 available for metabolism of bupropion. However, intestinal S9 fraction formed threohydrobupropion to the extent of 25% of the amount of threohydrobupropion formed by liver S9 fraction. Enzyme inhibition and Western blots identified that 11β-dehydrogenase isozyme 1 in the liver microsome fraction is mainly responsible for the formation of threohydrobupropion, and in the intestine AKR7 may be responsible for the same metabolite formation. These quantitative comparisons of bupropion metabolism by CR in the liver and intestine may provide new insight into its efficacy and side effects with respect to these metabolites.

  13. Soil fluxes of carbonyl sulfide (COS) across four distinct ecosystems

    Science.gov (United States)

    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.

  14. Organometallic and Bioorganometallic Chemistry - Ferrocene and Metal Carbonyls

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    Čakić Semenčić, M.

    2011-02-01

    Full Text Available Organometallic chemistry deals with compounds containing metal-carbon bonds. Basic organometallics derived from the s- and p-block metals (containing solely σ-bonds were understood earlier, while organometallic chemistry of the d- and f-block has developed much more recently. These compounds are characterized by three types of M-C bonds (σ, π and δand their structures are impossible to deduce by chemical means alone; fundamental advances had to await the development of X-ray diffraction, as well as IR- and NMR-spectroscopy. On the other hand, elucidation of the structure of e. g. vitamin B12 and ferrocene (discovered in 1951 contributed to progress in these instrumental analytical methods, influencing further phenomenal success of transition-metal organometallic chemistry in the second half of the twentieth century. The most thoroughly explored fields of application of organometallics were in the area of catalysis, asymmetric synthesis, olefin metathesis, as well as organic synthesis and access to new materials and polymers.The most usual ligands bound to d- and f-metals are carbon monoxide, phosphines, alkyls, carbenes and arenes, and in this review the bonding patterns in the metal carbonyls and ferrocene are elaborated. The common characteristics of these two classes are two-component bonds. The CO-M bonds include (i donation from ligand HOMO to vacant M d-orbitals (σ-bond, and (ii back-donation from the filled M d-orbitals in the ligand LUMO (π-bond. Similar (but much more complicated ferrocene contains delocalized bonds consisting of electron donation from Cp to Fe (σ-bonds- and π-bonding and δ-back-bonding from metal to Cp. In such a way ferrocene, i. e. (η5-Cp2Fe contains 18 bonding electrons giving to this compound "superaromatic" properties in the sense of stability and electrophilic substitution. In contrast to benzenoid aromatic compounds reactions in two Cp-rings can occur giving homo- and heteroannularly mono-, two-… per

  15. Recent advances in osmium-catalyzed hydrogenation and dehydrogenation reactions.

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    Chelucci, Giorgio; Baldino, Salvatore; Baratta, Walter

    2015-02-17

    CONSPECTUS: A current issue in metal-catalyzed reactions is the search for highly efficient transition-metal complexes affording high productivity and selectivity in a variety of processes. Moreover, there is also a great interest in multitasking catalysts that are able to efficiently promote different organic transformations by careful switching of the reaction parameters, such as temperature, solvent, and cocatalyst. In this context, osmium complexes have shown the ability to catalyze efficiently different types of reactions involving hydrogen, proving at the same time high thermal stability and simple synthesis. In the catalytic reduction of C═X (X = O, N) bonds by both hydrogenation (HY) and transfer hydrogenation (TH) reactions, the most interest has been focused on homogeneous systems based on rhodium, iridium, and in particular ruthenium catalysts, which have proved to catalyze chemo- and stereoselective hydrogenations with remarkable efficiency. By contrast, osmium catalysts have received much less attention because they are considered less active on account of their slower ligand exchange kinetics. Thus, this area remained almost neglected until recent studies refuted these prejudices. The aim of this Account is to highlight the impressive developments achieved over the past few years by our and other groups on the design of new classes of osmium complexes and their applications in homogeneous catalytic reactions involving the hydrogenation of carbon-oxygen and carbon-nitrogen bonds by both HY and TH reactions as well as in alcohol deydrogenation (DHY) reactions. The work described in this Account demonstrates that osmium complexes are emerging as powerful catalysts for asymmetric and non-asymmetric syntheses, showing a remarkably high catalytic activity in HY and TH reactions of ketones, aldehydes, imines, and esters as well in DHY reactions of alcohols. Thus, for instance, the introduction of ligands with an NH function, possibly in combination with a

  16. Concentrations of formaldehyde and other carbonyls in environments affected by incense burning.

    Science.gov (United States)

    Ho, Steven Sai Hang; Yu, Jian Zhen

    2002-10-01

    Burning incense to pay homage to deities is common in Chinese homes and temples. Air samples were collected and analyzed for carbonyls from a home and a temple in Hong Kong where incense burning occurs on a daily basis. Carbonyls in the air were trapped on a solid sorbent coated with O-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine, followed by thermal desorption and subsequent GC/MS analysis. The carbonyls identified include formaldehyde, acetaldehyde, acrolein, 2-furfural, benzaldehyde, glyoxal, and methylglyoxal. The levels of the above carbonyls correlate with the intensity of the incense-burning activities. The total mixing ratios of the carbonyls in the temple exceed those in the ambient air outside the temple by 11-23 times. Formaldehyde is the most abundant species, contributing to approximately 55% of the total carbonyl mixing ratios in both the temple and the home environments during incense burning. The mixing ratio of formaldehyde ranges from 108 to 346 ppbv in the temple and averages 103 ppbv in the home during incense burning. These values exceed the World Health Organization (WHO) air quality guideline of 100 microg m(-3) (88 ppbv) for formaldehyde. The highest formaldehyde level in the temple exceeds the WHO guideline by 3 times at peak incense burning hours. The mixing ratio of acrolein in the temple ranges from 20 to 99 ppbv, approaching or exceeding the WHO air quality guideline of 50 microg m(-3) (22 ppbv) for acrolein. Our measurements indicate that incense burning significantly elevates the concentrations of a number of carbonyls, most notably formaldehyde and acrolein, in the surrounding environments. This study provides preliminary insights on indoor air quality problems created by incense burning.

  17. Proteomic identification of carbonylated proteins in F344 rat hippocampus after 1-bromopropane exposure

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Zhenlie [Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Nagoya 466‐8550 (Japan); Department of Toxicology, Guangdong Prevention and Treatment Center for Occupational Diseases, Guangzhou 510‐300 (China); Ichihara, Sahoko [Graduate School of Regional Innovation Studies, Mie University, Tsu 514‐8507 (Japan); Oikawa, Shinji [Department of Environmental and Molecular Medicine, Mie University Graduate School of Medicine, Mie 514‐8507 (Japan); Chang, Jie; Zhang, Lingyi; Subramanian, Kaviarasan; Mohideen, Sahabudeen Sheik [Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Nagoya 466‐8550 (Japan); Ichihara, Gaku, E-mail: gak@med.nagoya-u.ac.jp [Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Nagoya 466‐8550 (Japan)

    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.

  18. S-Allyl-Cysteines Reduce Amelioration of Aluminum Induced Toxicity in Rats

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    Sadhana Shrivastava

    2011-01-01

    Full Text Available Problem statement: Aluminum (Al is a trivalent cation found in its ionic form in most kinds of animal tissues and in natural waters everywhere. Approach: It is a potent neurotoxin and has been associated in the pathogenesis of several clinical disorders including Alzheimer’s disease. Results: The aim of the study was to demonstrate the protective effect of S-Allyl-Cysteines (SAC against Al-induced toxicity in rat model on certain biochemical parameters, lipid peroxidation and oxidative stress enzymes of white albino rats. Six rats per group were divided into various treatment groups. Group one rats were given normal saline and served as control group. Group two animals received Al as aluminum nitrate 32.5 mg (i.p. for the induction of toxicity. Group three to five received different doses of SAC (25, 50 and 100 mg kg-1 for 3 days after 24 h of Al toxicity. Rats were orally administered their respective doses every day for 3 days. Evaluations were made in blood and tissues. The activity of Acetylcholinesterase (AchE was inhibited in all the parts of brain after Al intoxication. Significant rise were observed the Activities of Serum Transaminases (AST and ALT after toxicant exposure. The activity of â-Aminolevulinic acid Dehydratase (ALAD in blood and â-Aminolevulinic Acid Synthetase (ALAS in brain was decreased after Al exposure. Al significant increased cholesterol, triglyceride, creatinine and urea level in serum. TBARS level was significantly higher and GSH content were significantly lower during toxicity. Total and esterified cholesterol in liver, kidney and brain were increased after Al exposure. Histopathological changes in liver, kidney and brain were also recouped with the therapy. Conclusion/Recommendations: Our data proved that SAC which is a bioactive and bioavailable component of garlic has organosulfur compounds which regulates the thiol status of the cell and scavenges free radicals and work as an antioxidant. Thus SAC

  19. New copolymer of acrylamide with allyl methacrylate and its capacity for the removal of azo dyes

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    Yeliz Yildirim

    2015-04-01

    Full Text Available The copolymerization reactions of Acrylamide (AA with the different mole ratios of allyl methacrylate (AMA such as 25/75, 50/50 and 75/25 were studied by radical polymerization under argon atmosphere using 2,2’-Azobis (isobutyronitri1e (AIBN as initiator. The copolymers were characterized with Fourier transform infrared spectroscopy (FTIR and thermogravimetric analysis (TG. FTIR spectra showed that the C=O, C-N and N-H groups in copolymers remained during the copolymerization. It is concluded from the thermograms that Poly(AA-co-AMA copolymers which contained different ratios of monomer and comonomer exhibit similar thermal behavior. Adsorption capacity, kinetic and isotherm studies of Direct Brown 2 onto the copolymers have been evaluated. Different factors such as the monomer ratio, pH, initial dye concentration, copolymer dosage and contact time affecting the removal process were studied. It was found that the adsorption process agreed with the Freundlich and Dubinin-Raduskevich model and the adsorption of Direct Brown 2 depended on the acrylamide content and pH of the solution. The standard Gibb’s free energy was determined as - 14.7 kJ/mol, which means that adsorption occurred spontaneously and the process is feasible. Increasing the acrylamide content led to increased adsorption of Direct Brown 2 on the copolymer. Moreover, adsorption kinetic studies showed that the adsorption followed a pseudo-second-order kinetic model, indicating that the chemical adsorption was the rate-limiting step. These results show that Poly(AA-co-AMA can be used as adsorbent for water pollutants such as Direct Brown 2 and has potential applications in related industrial and environmental areas.

  20. Stereoselective coordination: a six-membered P,N-chelate tailored for asymmetric allylic alkylation.

    Science.gov (United States)

    Császár, Z; Farkas, G; Bényei, A; Lendvay, G; Tóth, I; Bakos, J

    2015-10-01

    Six-membered chelate complexes [Pd(1a-b)Cl2], (2a-b) and [Pd(1a-b)(η(3)-PhCHCHCHPh)]BF4, (3a-b) of P,N-type ligands 1a, ((2S,4S)-2-diphenyl-phosphino-4-isopropylamino-pentane) and 1b, ((2S,4S)-2-diphenyl-phosphino-4-methylamino-pentane) have been prepared. The Pd-complexes have been characterized in solution by 1D and 2D NMR spectroscopy. The observed structures were confirmed by DFT calculations and in the case of 2a also by X-ray crystallography. Unexpectedly, the coordination of the all-carbon-backbone aminophosphine 1a resulted in not only a stereospecific locking of the donor nitrogen atom into one of the two possible configurations but also the conformation of the six-membered chelate rings containing three alkyl substituents was forced into the same single chair structure showing the axially placed isopropyl group on the coordinated N-atom. The stereodiscriminative complexation of 1a led to the formation of a palladium catalyst with a conformationally rigid chelate having a configurationally fixed nitrogen and electronically different coordination sites due to the presence of P and N donors. The stereochemically fixed catalyst provided excellent ee's (up to 96%) and activities in asymmetric allylic alkylation reactions. In contrast, the chelate rings formed by 1b exist in two different chair conformations, both containing axial methyl groups, but with the opposite configurations of the coordinated N-atom. Pd-complexes of 1b provided low enantioselectivities in similar alkylations, therefore emphasizing the importance of the stereoselective coordination of N-atoms in analogous P-N chelates. The factors determining the coordination of the ligands were also studied with respect to the chelate ring conformation and the nitrogen configuration.

  1. Mechanisms of transient receptor potential vanilloid 1 activation and sensitization by allyl isothiocyanate.

    Science.gov (United States)

    Gees, Maarten; Alpizar, Yeranddy A; Boonen, Brett; Sanchez, Alicia; Everaerts, Wouter; Segal, Andrei; Xue, Fenqin; Janssens, Annelies; Owsianik, Grzegorz; Nilius, Bernd; Voets, Thomas; Talavera, Karel

    2013-09-01

    Allyl isothiocyanate (AITC; aka, mustard oil) is a powerful irritant produced by Brassica plants as a defensive trait against herbivores and confers pungency to mustard and wasabi. AITC is widely used experimentally as an inducer of acute pain and neurogenic inflammation, which are largely mediated by the activation of nociceptive cation channels transient receptor potential ankyrin 1 and transient receptor potential vanilloid 1 (TRPV1). Although it is generally accepted that electrophilic agents activate these channels through covalent modification of cytosolic cysteine residues, the mechanism underlying TRPV1 activation by AITC remains unknown. Here we show that, surprisingly, AITC-induced activation of TRPV1 does not require interaction with cysteine residues, but is largely dependent on S513, a residue that is involved in capsaicin binding. Furthermore, AITC acts in a membrane-delimited manner and induces a shift of the voltage dependence of activation toward negative voltages, which is reminiscent of capsaicin effects. These data indicate that AITC acts through reversible interactions with the capsaicin binding site. In addition, we show that TRPV1 is a locus for cross-sensitization between AITC and acidosis in nociceptive neurons. Furthermore, we show that residue F660, which is known to determine the stimulation by low pH in human TRPV1, is also essential for the cross-sensitization of the effects of AITC and low pH. Taken together, these findings demonstrate that not all reactive electrophiles stimulate TRPV1 via cysteine modification and help understanding the molecular bases underlying the surprisingly large role of this channel as mediator of the algesic properties of AITC.

  2. Elucidation of the regio- and chemoselectivity of enzymatic allylic oxidations with Pleurotus sapidus – conversion of selected spirocyclic terpenoids and computational analysis

    Directory of Open Access Journals (Sweden)

    Verena Weidmann

    2013-10-01

    Full Text Available Allylic oxidations of olefins to enones allow the efficient synthesis of value-added products from simple olefinic precursors like terpenes or terpenoids. Biocatalytic variants have a large potential for industrial applications, particularly in the pharmaceutical and food industry. Herein we report efficient biocatalytic allylic oxidations of spirocyclic terpenoids by a lyophilisate of the edible fungus Pleurotus sapidus. This ‘’mushroom catalysis’’ is operationally simple and allows the conversion of various unsaturated spirocyclic terpenoids. A number of new spirocyclic enones have thus been obtained with good regio- and chemoselectivity and chiral separation protocols for enantiomeric mixtures have been developed. The oxidations follow a radical mechanism and the regioselectivity of the reaction is mainly determined by bond-dissociation energies of the available allylic CH-bonds and steric accessibility of the oxidation site.

  3. Rheological and mechanical behavior of polyacrylamide hydrogels chemically crosslinked with allyl agarose for two-dimensional gel electrophoresis.

    Science.gov (United States)

    Suriano, R; Griffini, G; Chiari, M; Levi, M; Turri, S

    2014-02-01

    Two-dimensional (2-D) gel electrophoresis currently represents one of the most standard techniques for protein separation. In addition to the most commonly employed polyacrylamide crosslinked hydrogels, acrylamide-agarose copolymers have been proposed as promising systems for separation matrices in 2-D electrophoresis, because of the good resolution of both high and low molecular mass proteins made possible by careful control and optimization of the hydrogel pore structure. As a matter of fact, a thorough understanding of the nature of the hydrogel pore structure as well as of the parameters by which it is influenced is crucial for the design of hydrogel systems with optimal sieving properties. In this work, a series of acrylamide-based hydrogels covalently crosslinked with different concentrations of allyl agarose (0.2-1%) is prepared and characterized by creep-recovery measurements, dynamic rheology and tensile tests, in the attempt to gain a clearer understanding of structure-property relationships in crosslinked polyacrylamide-based hydrogels. The rheological and mechanical properties of crosslinked acrylamide-agarose hydrogels are found to be greatly affected by crosslinker concentration. Dynamic rheological tests show that hydrogels with a percentage of allyl agarose between 0.2% and 0.6% have a low density of elastically effective crosslinks, explaining the good separation of high molecular mass proteins in 2-D gel electrophoresis. Over the same range of crosslinker concentration, creep-recovery measurements reveal the presence of non-permanent crosslinks in the hydrogel network that justifies the good resolution of low molecular mass proteins as well. In tensile tests, the hydrogel crosslinked with 0.4% of allyl agarose exhibits the best results in terms of mechanical strength and toughness. Our results show how the control of the viscoelastic and the mechanical properties of these materials allow the design of mechanically stable hydrogels with improved

  4. Antimicrobial activity of allyl isothiocyanate used to coat biodegradable composite films as affected by storage and handling conditions.

    Science.gov (United States)

    Li, Weili; Liu, Linshu; Jin, Tony Z

    2012-12-01

    We evaluated the effects of storage and handling conditions on the antimicrobial activity of biodegradable composite films (polylactic acid and sugar beet pulp) coated with allyl isothiocyanate (AIT). Polylactic acid and chitosan were incorporated with AIT and used to coat one side of the film. The films were subjected to different storage conditions (storage time, storage temperature, and packed or unpacked) and handling conditions (washing, abrasion, and air blowing), and the antimicrobial activity of the films against Salmonella Stanley in tryptic soy broth was determined. The films (8.16 μl of AIT per cm(2) of surface area) significantly (P packaging.

  5. Tandem SN2' nucleophilic substitution/oxidative radical cyclization of aryl substituted allylic alcohols with 1,3-dicarbonyl compounds.

    Science.gov (United States)

    Zhang, Zhen; Li, Cheng; Wang, Shao-Hua; Zhang, Fu-Min; Han, Xue; Tu, Yong-Qiang; Zhang, Xiao-Ming

    2017-03-23

    A novel and efficient tandem SN2' nucleophilic substitution/oxidative radical cyclization reaction of aryl substituted allylic alcohols with 1,3-dicarbonyl compounds has been developed by using Mn(OAc)3 as an oxidant, which enables the expeditious synthesis of polysubstituted dihydrofuran (DHF) derivatives in moderate to high yields. The use of weakly acidic hexafluoroisopropanol (HFIP) as the solvent rather than AcOH has successfully improved the yields and expanded the substrate scope of this type of radical cyclization reactions. Mechanistic studies confirmed the cascade reaction process involving a final radical cyclization.

  6. A novel carbonyl reductase with anti-Prelog stereospecificity from Acetobacter sp. CCTCC M209061: purification and characterization.

    Directory of Open Access Journals (Sweden)

    Xiao-Hong Chen

    Full Text Available A novel carbonyl reductase (AcCR catalyzing the asymmetric reduction of ketones to enantiopure alcohols with anti-Prelog stereoselectivity was found in Acetobacter sp. CCTCC M209061 and enriched 27.5-fold with an overall yield of 0.4% by purification. The enzyme showed a homotetrameric structure with an apparent molecular mass of 104 kDa and each subunit of 27 kDa. The gene sequence of AcCR was cloned and sequenced, and a 762 bp gene fragment was obtained. Either NAD(H or NADP(H can be used as coenzyme. For the reduction of 4'-chloroacetophenone, the Km value for NADH was around 25-fold greater than that for NADPH (0.66 mM vs 0.026 mM, showing that AcCR preferred NADPH over NADH. However, when NADH was used as cofactor, the response of AcCR activity to increasing concentration of 4'-chloroacetophenone was clearly sigmoidal with a Hill coefficient of 3.1, suggesting that the enzyme might possess four substrate-binding sites cooperating with each other The Vmax value for NADH-linked reduction was higher than that for NADPH-linked reduction (0.21 mM/min vs 0.17 mM/min. For the oxidation of isopropanol, the similar enzymological properties of AcCR were found using NAD+ or NADP+ as cofactor. Furthermore, a broad range of ketones such as aryl ketones, α-ketoesters and aliphatic ketones could be enantioselectively reduced into the corresponding chiral alcohols by this enzyme with high activity.

  7. Positive trends in Southern Hemisphere observations of carbonyl sulfide

    Science.gov (United States)

    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

  8. Strong soil source of carbonyl sulfide in an agricultural field

    Science.gov (United States)

    Maseyk, K. S.; Seibt, U.; Berry, J. A.; Billesbach, D. P.; Campbell, J.; Torn, M. S.

    2012-12-01

    A promising new approach to constrain biosphere-atmosphere carbon and water exchange is the use of carbonyl sulfide (COS). COS is taken up by leaves via the same pathway as CO2, leading to a close coupling of vegetation COS and CO2 fluxes during photosynthesis. Therefore it has been proposed that the gross fluxes of photosynthesis and respiration can be quantified through the concurrent measurements of COS and CO2. A necessary requirement for this approach at ecosystem and continental scales are estimates of soil COS fluxes. Soil is largely considered a sink for COS, but our knowledge of in situ soil COS fluxes remains very limited. We measured soil COS fluxes in a wheat field in Oklahoma from April to June 2012, using a novel combination of an automated soil chamber coupled to a COS laser analyzer. We provide the first continuous record of soil COS fluxes under natural conditions, and report on a phenomenon that has not been observed before. In contrast to the majority of published results, we found that the agricultural soil was a strong source of COS under most conditions during the campaign. The COS flux over the study period was highly correlated with soil temperature. Up to a soil temperature of around 15°C, the soil acted as a COS sink. Above 15°C, it acted a source of COS, with fluxes of up to 25 pmol m-2 s-1. To locate the source of the COS production, we investigated different soil components. Wheat roots were found to be emitting COS under all conditions. Root-free soil was a COS sink up to a soil temperature of around 25°C, but turned into a COS source at higher soil temperatures. We also observed COS production from the roots of several other species, indicating that this may be a widespread phenomenon. Using eddy covariance data of COS and CO2 that was collected concurrently with the soil measurements, we also demonstrate how the soil COS source can be taken into account when partitioning net ecosystem exchange into photosynthesis and respiration.

  9. 烯丙基异硫氰酸酯的熏蒸毒力研究%FUMIGATION ACTIVITY OF THE ALLYL ISOTHIOCYANATE

    Institute of Scientific and Technical Information of China (English)

    陈春武; 谢令德; 陈雅群; 何君; 贺艳萍

    2012-01-01

    以玉米象和赤拟谷盗作为实验对象,采用熏蒸方式对烯丙基异硫氰酸酯的毒力进行测定.结果表明,烯丙基异硫氰酸酯对所研究的两种害虫有较好的快速致死作用,同时研究发现在相同熏蒸时间内烯丙基异硫氰酸酯对玉米象熏蒸的LC50和LC99均小于对赤拟谷盗的LC50和LC99,这说明烯丙基异硫氰酸酯对玉米象的熏蒸效果比对赤拟谷盗的好.%Chosing Si tophilus zesmais (Motschulsky) and Tribolium castaneun (Herbst) as experimental objects, the toxicity for the allyl isothiocyanate (AITC) is tested systematically by fumigation method. The result demonstrates that the allyl isothiocyanate presents rapid lethal effect against both of the two types of insects. The research also shows that both the LC50 and the LC99 of the fumigation of the allyl isothiocyanate to the Sitophilus zeamais are less than those of the allyl isothiocyanate to the Tribolium castaneum exposuring the same fumigating time, which indicates that the fumigating effect of the allyl isothiocyanate to the Sitophilus zeamais is more effective than that of the allyl isothiocyanate to the Tribolium castaneum.

  10. The utilization of the mesoporous Ti-SBA-15 catalyst in the epoxidation of allyl alcohol to glycidol and diglycidyl ether in the water medium

    Directory of Open Access Journals (Sweden)

    Wróblewska Agnieszka

    2015-12-01

    Full Text Available This work presents the studies on the optimization the process of allyl alcohol epoxidation over the Ti-SBA-15 catalyst. The optimization was carried out in an aqueous medium, wherein water was introduced into the reaction medium with an oxidizing agent (30 wt% aqueous solution of hydrogen peroxide and it was formed in the reaction medium during the processes. The main investigated technological parameters were: the temperature, the molar ratio of allyl alcohol/hydrogen peroxide, the catalyst content and the reaction time. The main functions the process were: the selectivity of transformation to glycidol in relation to allyl alcohol consumed, the selectivity of transformation to diglycidyl ether in relation to allyl alcohol consumed, the conversion of allyl alcohol and the selectivity of transformation to organic compounds in relation to hydrogen peroxide consumed. The analysis of the layer drawings showed that in water solution it is best to conduct allyl alcohol epoxidation in direction of glycidol (selectivity of glycidol 54 mol% at: the temperature of 10–17°C, the molar ratio of reactants 0.5–1.9, the catalyst content 2.9–4.0 wt%, the reaction time 2.7–3.0 h and in direction of diglycidyl ether (selectivity of diglycidyl ether 16 mol% at: the temperature of 18–33°C, the molar ratio of reactants 0.9–1.65, the catalyst content 2.0–3.4 wt%, the reaction time 1.7–2.6 h. The presented method allows to obtain two very valuable intermediates for the organic industry.

  11. Green synthesis of allyl isobornyl ether%烯丙基异冰片基醚绿色合成研究

    Institute of Scientific and Technical Information of China (English)

    王士康; 徐徐; 兰蓝; 樊媛媛; 王石发

    2012-01-01

    以莰烯和烯丙醇为原料,研究了烯丙基异冰片基醚的绿色合成工艺,探讨了催化剂种类及用量、反应温度、反应时间,以及烯丙醇与莰烯物质的量之比对莰烯醚化反应选择性及烯丙基异冰片基醚产物得率的影响.采用正交试验方法确定了烯丙基异冰片基醚的最适工艺条件:A-15型阳离子树脂为催化剂,催化剂用量为烯丙醇和莰烯原料总质量的5%,烯丙醇与莰烯物质的量之比为1.5:1,反应温度75℃,反应时间7h.在此条件下工业莰烯转化率为85.5%,反应选择性为97.5%,烯丙基异冰片基醚得率为83.4%.最后采用GC-MS、IR等分析技术对合成所得产物的结构进行了分析测定.%Green synthetic method of allyl isobornyl ether was investigated by using camphene and allyl alcohol as the raw materials in this paper. Influence of catalysts and their usages, reaction temperature, reaction time, and the molar ratio of allyl alcohol to camphene on the selectivity of etherification and the yield of allyl isobornyl ether were examined, and the optimum synthesis conditions were determined based on the orthogonal test results as follows: A-15 resin was used as the catalyst for etherification, and the amount of A-15 cationic exchange resin was 5 % (based on the total weight of camphene and allyl alcohol) ; molar ratio of allyl alcohol to camphene was 1. 5-1; reaction temperature and reaction time were 75 ℃ and 7 h, respectively. The conversion ratio of camphene and the reaction selectivity reached 85. 5 % and 97. 5 % respectively, and the yield of allyl isobornyl ether also reached 83. 4 %. The structure of allyl isobornyl ether was identified by GC-MS and IR spectra.

  12. Use of Cyclic Allylic Bromides in the Zinc–Mediated Aqueous Barbier–Grignard Reaction

    Directory of Open Access Journals (Sweden)

    Suzanne M. Perala

    2001-07-01

    Full Text Available The zinc–mediated aqueous Barbier–Grignard reaction of cyclic allylic bromide substrates with various aldehydes and ketones to afford homoallylic alcohols was investigated. Aromatic aldehydes and ketones afforded adducts in good yields (66–90% and with good diastereoselectivities. Non–aromatic aldehydes also reacted well under these conditions, but only poor yields were obtained with non–aromatic ketones. Regioselectivity was high when some substituted cyclic allylic bromides were investigated.

  13. Fructose-Induced Carbonyl/Oxidative Stress in S. cerevisiae: Involvement of TOR.

    Science.gov (United States)

    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.

  14. Attractor Explosions and Catalyzed Vacuum Decay

    Energy Technology Data Exchange (ETDEWEB)

    Green, Daniel; Silverstein, Eva; Starr, David

    2006-05-05

    We present a mechanism for catalyzed vacuum bubble production obtained by combining moduli stabilization with a generalized attractor phenomenon in which moduli are sourced by compact objects. This leads straightforwardly to a class of examples in which the Hawking decay process for black holes unveils a bubble of a different vacuum from the ambient one, generalizing the new endpoint for Hawking evaporation discovered recently by Horowitz. Catalyzed vacuum bubble production can occur for both charged and uncharged bodies, including Schwarzschild black holes for which massive particles produced in the Hawking process can trigger vacuum decay. We briefly discuss applications of this process to the population and stability of metastable vacua.

  15. A cleavable biotin tagging reagent that enables the enrichment and identification of carbonylation sites in proteins.

    Science.gov (United States)

    Coffey, Chelsea M; Gronert, Scott

    2016-01-01

    The utility of a new, cleavable tag for identifying and enriching protein carbonyls is examined. Using a model system, human serum albumin modified with acrolein, the EZ-Link alkoxyamine-PEG4-SS-PEG4-biotin affinity tag, was tested for its ability to label protein carbonyls in proteomic analyses of protein carbonylation. The efficiency of the labeling was assayed and compared to standard biotin hydrazide reagents. The label was also tested in liquid chromatography-tandem mass spectrometry (LC/MS/MS) experiments. The quality of the fragmentation spectra was assessed and the relative detection efficiency of various modification sites was compared to standard biotin hydrazide reagents. Finally, the viability of using the label with streptavidin bead enrichment protocols in a standard proteomics workflow was probed.

  16. Influence of the Dielectric Medium on the Carbonyl Infrared Absorption Peak of Acetylferrocene

    Directory of Open Access Journals (Sweden)

    F. López-Linares

    2005-02-01

    Full Text Available The solvent effect on the position of the carbonyl vibrational stretching ofacetylferrocene in aprotic media was studied in this work. The solvent-induced shifts in thisorganometallic compound were interpreted in terms of the alternative reaction field model(SCRF-MO proposed by Kolling. In contrast to the established trends for carbonyl groupsin organic systems, the results suggest that the continuum models for the reaction field arenot adequate and that the influence of dipolarity-polarizability described by aninhomogeneous coupling function θ (ε L(n 2 that assumes optical dielectric saturation isresponsible for the carbonyl band shift and, there is empirical evidence that the effect offield-induced intermolecular interaction on band shift, interpreted in terms of the van derWaals forces from the solvent, have a important contribution to this phenomena.

  17. Influence of carbonyl iron particle coating with silica on the properties of magnetorheological elastomers

    Science.gov (United States)

    Małecki, P.; Królewicz, M.; Hiptmair, F.; Krzak, J.; Kaleta, J.; Major, Z.; Pigłowski, J.

    2016-10-01

    In this paper, the influence of encapsulating carbonyl iron particles with various silica coatings on the properties of magnetorheological elastomers (MREs) was investigated. A soft styrene-ethylene-butylene-styrene thermoplastic elastomer was used as the composite’s polymer matrix. Spherical carbonyl iron powder (CIP) acted as the ferromagnetic filler. In order to improve the metal-polymer interaction, carbonyl iron particles were coated with two types of single and six types of double silica layers. The first layer was created through a TMOS or TEOS hydrolysis whereas the second one was composed of organosilanes. The mechanical properties of MREs containing 38.5 vol% of CIP were analysed under dynamic loading conditions. To investigate the magnetorheological effect in these composites, a 430 mT magnetic field, generated by an array of permanent magnets, was applied during testing. The results revealed that the magnetomechanical response of the MREs differs substantially, depending on the kind of particle coating.

  18. Fundamental reaction pathway and free energy profile for butyrylcholinesterase-catalyzed hydrolysis of heroin.

    Science.gov (United States)

    Qiao, Yan; Han, Keli; Zhan, Chang-Guo

    2013-09-17

    The pharmacological function of heroin requires an activation process that transforms heroin into 6-monoacetylmorphine (6-MAM), which is the most active form. The primary enzyme responsible for this activation process in human plasma is butyrylcholinesterase (BChE). The detailed reaction pathway of the activation process via BChE-catalyzed hydrolysis has been explored computationally, for the first time, in this study via molecular dynamics simulation and first-principles quantum mechanical/molecular mechanical free energy calculations. It has been demonstrated that the whole reaction process includes acylation and deacylation stages. The acylation consists of two reaction steps, i.e., the nucleophilic attack on the carbonyl carbon of the 3-acetyl group of heroin by the hydroxyl oxygen of the Ser198 side chain and the dissociation of 6-MAM. The deacylation also consists of two reaction steps, i.e., the nucleophilic attack on the carbonyl carbon of the acyl-enzyme intermediate by a water molecule and the dissociation of the acetic acid from Ser198. The calculated free energy profile reveals that the second transition state (TS2) should be rate-determining. The structural analysis reveals that the oxyanion hole of BChE plays an important role in the stabilization of rate-determining TS2. The free energy barrier (15.9 ± 0.2 or 16.1 ± 0.2 kcal/mol) calculated for the rate-determining step is in good agreement with the experimentally derived activation free energy (~16.2 kcal/mol), suggesting that the mechanistic insights obtained from this computational study are reliable. The obtained structural and mechanistic insights could be valuable for use in the future rational design of a novel therapeutic treatment of heroin abuse.

  19. Molecular detection and in vitro antioxidant activity of S-allyl-L-cysteine (SAC) extracted from Allium sativum.

    Science.gov (United States)

    Sun, Y-E; Wang, W-D

    2016-06-30

    It is well known that Allium sativum has potential applications to clinical treatment of various cancers due to its remarkable ability in eliminating free radicals and increasing metabolism. An allyl-substituted cysteine derivative - S-allyl-L-cysteine (SAC) was separated and identified from Allium sativum. The extracted SAC was reacted with 1-pyrenemethanol to obtain pyrene-labelled SAC (Py-SAC) to give SAC fluorescence properties. Molecular detection of Py-SAC was conducted by steady-state fluorescence spectroscopy and time-resolved fluorescence method to quantitatively measure concentrations of Py-SAC solutions. The ability of removing 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radical using Py-SAC was determined through oxygen radical absorbance capacity (ORAC). Results showed the activity of Py-SAC and Vitamin C (VC) with ORAC as index, the concentrations of Py-SAC and VC were 58.43 mg/L and 5.72 mg/L respectively to scavenge DPPH, and 8.16 mg/L and 1.67 mg/L to scavenge •OH respectively. Compared with VC, the clearance rates of Py-SAC to scavenge DPPH were much higher, Py-SAC could inhibit hydroxyl radical. The ability of removing radical showed a dose-dependent relationship within the scope of the drug concentration.

  20. The - - and Submm-Wave Spectrum of Allyl Isocyanide and Radioastronomical Observations in Orion KL and the Primos Line Survey

    Science.gov (United States)

    Haykal, I.; Motiyenko, R. A.; Margules, L.; Huet, T. R.; Ecija, P.; Cocinero, E. J.; Basterretxea, F.; Fernandez, J. A.; Castano, F.; Tercero, B.; Cernicharo, J.; Lesarri, A.; Guillemin, J. C.

    2013-06-01

    Last year we presented the first rotational analysis of the ground state of the two conformers of allyl isocyanide from 4 GHz to 905 GHz. The analysis of the rotational spectrum of the cis conformer of allyl isocyanide was extended. We resolved Coriolis interactions of a and b types between the excited vibrational states ν_1=1 and ν_2=1, calculated to be at 156 cm^{-1} (A^{'}) and 167 cm^{-1} (A^{''}) respectively (MP2/aug-cc-pvtz), from 150 GHz to 600 GHz. Strong perturbations were observed in the 150-310 GHz range for low values of the quantum number K_a starting from K_a = 0, 1. The anharmonicities appeared as well at higher frequencies for larger quantum numbers. The two modes were fitted together with the SPFIT/SPCAT suite of programs and a set of Coriolis parameters was accurately determined. The fit contains more than 3000 lines up to J = 99 and K_a = 12 for both modes. We did not detect these species neither in the IRAM 30-m line survey of Orion KL nor in the PRIMOS survey towards SgrB2. Nevertheless, we provided upper limits to their column density in Orion KL. This work was supported by the CNES and the Action sur Projets de l'INSU, PCMI. I. Haykal et al. manuscript in preparation H. Pickett J. Mol. Spec.{148}, 371-377, 1991.

  1. Ab initio determination of dark structures in radiationless transitions for aromatic carbonyl compounds.

    Science.gov (United States)

    Fang, Wei-Hai

    2008-03-01

    Mechanistic photodissociation of a polyatomic molecule has long been regarded as an intellectually challenging area of chemical physics, the results of which are relevant to atmospheric chemistry, biological systems, and many application fields. Carbonyl compounds play a unique role in the development of our understanding of the spectroscopy, photochemistry, and photophysics of polyatomic molecules and their photodissociation has been the subject of numerous studies over many decades. Upon irradiation, a molecule can undergo internal conversion (IC) and intersystem crossing (ISC) processes, besides photochemical and other photophysical processes. Transient intermediates formed in the IC and ISC radiationless processes, which are termed "dark", are not amenable to detection by conventional light absorption or emission. However, these dark intermediates play critical roles in IC and ISC processes and thus are essential to understanding mechanistic photochemistry of a polyatomic molecule. We have applied the multiconfiguration complete active space self-consistent field (CASSCF) method to determine the dark transient structures involved in radiationless processes for acetophenone and the related aromatic carbonyl compounds. The electronic and geometric structures predicted for the dark states are in a good agreement with those determined by ultrafast electron diffraction experiments. Intersection structure of different electronic states provides a very efficient "funnel" for the IC or ISC process. However, experimental determination of the intersection structure involved in radiationless transitions of a polyatomic molecule is impossible at present. We have discovered a minimum energy crossing point among the three potential energy surfaces (S1, T1, and T2) that appears to be common to a wide variety of aromatic carbonyl compounds with a constant structure. This new type of crossing point holds the key to understanding much about radiationless processes after

  2. Inhibition of bladder cancer cell proliferation by allyl isothiocyanate (mustard essential oil)

    Energy Technology Data Exchange (ETDEWEB)

    Sávio, André Luiz Ventura, E-mail: savio.alv@gmail.com [UNESP – Universidade Estadual Paulista, Faculdade de Medicina de Botucatu, Departamento de Patologia, Botucatu, SP (Brazil); Nicioli da Silva, Glenda [UFOP – Universidade Federal de Ouro Preto, Escola de Farmácia, Departamento de Análises Clínicas, Ouro Preto, MG (Brazil); Salvadori, Daisy Maria Fávero [UNESP – Universidade Estadual Paulista, Faculdade de Medicina de Botucatu, Departamento de Patologia, Botucatu, SP (Brazil)

    2015-01-15

    Highlights: • AITC inhibits mutant and wild-type TP53 cell proliferation. • Morphological changes and cells debris were observed after AITC treatment in both cells. • BAX and BCL2 expression modulation was observed in wild-type TP53 cells. • BCL2, BAX and ANLN increased and S100P decreased expression was detected in mutated TP53 cells. • AITC effects in gene modulation are dependent TP53 gene status. - Abstract: Natural compounds hold great promise for combating antibiotic resistance, the failure to control some diseases, the emergence of new diseases and the toxicity of some contemporary medical products. Allyl isothiocyanate (AITC), which is abundant in cruciferous vegetables and mustard seeds and is commonly referred to as mustard essential oil, exhibits promising antineoplastic activity against bladder cancer, although its mechanism of action is not fully understood. Therefore, the aim of this study was to investigate the effects of AITC activity on bladder cancer cell lines carrying a wild type (wt; RT4) or mutated (T24) TP53 gene. Morphological changes, cell cycle kinetics and CDK1, SMAD4, BAX, BCL2, ANLN and S100P gene expression were evaluated. In both cell lines, treatment with AITC inhibited cell proliferation (at 62.5, 72.5, 82.5 and 92.5 μM AITC) and induced morphological changes, including scattered and elongated cells and cellular debris. Gene expression profiles revealed increased S100P and BAX and decreased BCL2 expression in RT4 cells following AITC treatment. T24 cells displayed increased BCL2, BAX and ANLN and decreased S100P expression. No changes in SMAD4 and CDK1 expression were observed in either cell line. In conclusion, AITC inhibits cell proliferation independent of TP53 status. However, the mechanism of action of AITC differed in the two cell lines; in RT4 cells, it mainly acted via the classical BAX/BCL2 pathway, while in T24 cells, AITC modulated the activities of ANLN (related to cytokinesis) and S100P. These data confirm

  3. Is carbonyl sulfide a precursor for carbon disulfide in vegetation and soil? Interconversion of carbonyl sulfide and carbon disulfide in fresh grain tissues in vitro.

    Science.gov (United States)

    Ren, Y

    1999-05-01

    The interconversion of carbonyl sulfide (COS) and carbon disulfide (CS(2)) was studied in the roots and shoots of barley and chickpeas. Ratios of conversion gases, K, 40 h after the addition of COS or CS(2) are recorded. The proportion of COS converted to each of CS(2), CO, and H(2)S and the proportion of CS(2) converted to COS were greater in roots than in shoots. More COS was converted to CS(2) than CS(2) to COS in roots and shoots of barley and chickpeas. The amount of COS converted to H(2)S and CO was 8 times the amount converted to CS(2) in barley and 3-4 times the amount in chickpeas. Carbonyl sulfide may be a precursor for CS(2) in vegetation and soil, just as the reverse is true in the atmosphere. These two different results might form a cycle of COS and CS(2).

  4. Palladium catalyzed hydrogenation of bio-oils and organic compounds

    Science.gov (United States)

    Elliott, Douglas C.; Hu, Jianli; Hart, Todd R.; Neuenschwander, Gary G.

    2008-09-16

    The invention provides palladium-catalyzed hydrogenations of bio-oils and certain organic compounds. Experimental results have shown unexpected and superior results for palladium-catalyzed hydrogenations of organic compounds typically found in bio-oils.

  5. Impaired cardiac SIRT1 activity by carbonyl stress contributes to aging-related ischemic intolerance.

    Directory of Open Access Journals (Sweden)

    Chunhu Gu

    Full Text Available Reactive aldehydes can initiate protein oxidative damage which may contribute to heart senescence. Sirtuin 1 (SIRT1 is considered to be a potential interventional target for I/R injury management in the elderly. We hypothesized that aldehyde mediated carbonyl stress increases susceptibility of aged hearts to ischemia/reperfusion (I/R injury, and elucidate the underlying mechanisms with a focus on SIRT1. Male C57BL/6 young (4-6 mo and aged (22-24 mo mice were subjected to myocardial I/R. Cardiac aldehyde dehydrogenase (ALDH2, SIRT1 activity and protein carbonyls were assessed. Our data revealed that aged heart exhibited increased endogenous aldehyde/carbonyl stress due to impaired ALDH2 activity concomitant with blunted SIRT1 activity (P<0.05. Exogenous toxic aldehydes (4-HNE exposure in isolated cardiomyocyte verified that aldehyde-induced carbonyl modification on SIRT1 impaired SIRT1 activity leading to worse hypoxia/reoxygenation (H/R injury, which could all be rescued by Alda-1 (ALDH2 activator (all P<0.05. However, SIRT1 inhibitor blocked the protective effect of Alda-1 on H/R cardiomyocyte. Interestingly, myocardial I/R leads to higher carbonylation but lower activity of SIRT1 in aged hearts than that seen in young hearts (P<0.05. The application of Alda-1 significantly reduced the carbonylation on SIRT1 and markedly improved the tolerance to in vivo I/R injury in aged hearts, but failed to protect Sirt1(+/- knockout mice against myocardial I/R injury. This was verified by Alda-1 treatment improved postischemic contractile function recovery in ex vivo perfused aged but not in Sirt1(+/- hearts. Thus, aldehyde/carbonyl stress is accelerated in aging heart. These results provide a new insight that impaired cardiac SIRT1 activity by carbonyl stress plays a critical role in the increased susceptibility of aged heart to I/R injury. ALDH2 activation can restore this aging-related myocardial ischemic intolerance.

  6. Formation and emissions of carbonyls during and following gas-phase ozonation of indoor materials

    DEFF Research Database (Denmark)

    Poppendieck, D.G.; Hubbard, H.F.; Weschler, Charles J.;

    2007-01-01

    from 1 to 20 mg m(-2), with most of the carbonyls being of lower molecular weight (C-1-C-4). In contrast, total BOBP mass released from wood-based products ranged from 20 to 100 mg m(-2), with a greater fraction of the BOBPs being heavier carbonyls (C-5-C-9). The total BOBP mass released during...... relatively high BOBP releases. The greatest overall BOBP mass releases were observed for three materials that building occupants might have significant contact with: paper, office partition, and medium density fiberboard, e.g., often used in office furniture. These materials also exhibited extended BOBP...

  7. First application of supported ionic liquid phase (SILP) catalysis for continuous methanol carbonylation

    DEFF Research Database (Denmark)

    Riisager, Anders; Jørgensen, Betina; Wasserscheid, Peter

    2006-01-01

    A solid, silica-supported ionic liquid phase (SILP) rhodium iodide Monsanto-type catalyst system, [BMIM][Rh(CO)(2)I-2]-[BMIM]I -SiO2, exhibits excellent activity and selectivity towards acetyl products in fixed-bed, continuous gas-phase methanol carbonylation.......A solid, silica-supported ionic liquid phase (SILP) rhodium iodide Monsanto-type catalyst system, [BMIM][Rh(CO)(2)I-2]-[BMIM]I -SiO2, exhibits excellent activity and selectivity towards acetyl products in fixed-bed, continuous gas-phase methanol carbonylation....

  8. Photophysical properties of a synthetic, carbonyl-containing (N = 6+Cdbnd O) carotenoid analogue

    Science.gov (United States)

    Niedzwiedzki, Dariusz M.

    2014-05-01

    Retinyl-1 is a synthetic carotenoid analogue belonging to the retinal analogues family. It has six conjugated carbon-carbon double bonds with a carbonyl group conjugated to the π-electron system. Presence of the carbonyl group in vicinity of the conjugated carbon-carbon backbone leads to unique excited state properties that are extremely sensitive to solvent polarity and temperature. The simplicity of the synthesis of Retinyl-1 and ease of attachment to synthetic tetrapyrrole chromophores make Retinyl-1 attractive for use in artificial photosynthetic systems.

  9. Photophysical properties of a synthetic, carbonyl-containing (N=6+CO) carotenoid analogue

    Energy Technology Data Exchange (ETDEWEB)

    Niedzwiedzki, Dariusz M. [Washington Univ., St. Louis, MO (United States)

    2014-05-01

    Retinyl-1 is a synthetic carotenoid analogue belonging to the retinal analogues family. It has six conjugated carbon–carbon double bonds with a carbonyl group conjugated to the π-electron system. Presence of the carbonyl group in vicinity of the conjugated carbon–carbon backbone leads to unique excited state properties that are extremely sensitive to solvent polarity and temperature. The simplicity of the synthesis of Retinyl-1 and ease of attachment to synthetic tetrapyrrole chromophores make Retinyl-1 attractive for use in artificial photosynthetic systems.

  10. POLYMER—SUPPORTED RHODIUM CATALYSTS FOR CARBONYLATION OF METHYL ACETATE TO ACETIC ANHYDRIDE

    Institute of Scientific and Technical Information of China (English)

    CHENDean; HUANGShizhuan; 等

    1993-01-01

    Two kinds of rhodium catalysts supported on cross-linked styrene-divinylbenzene copolymers containing bipyridine or o-phenylene diamine have been prepared and found to display high activity for methyl acetate carbonylation to form acetic anhydride,the activities are even higher than their homogeneous counterparts. XPS analysis was used to characterize the synthetic catalysts.The apparent activation parameters were determined to be Eα=73.3KJ/mol,ΔH≠=66.3KJ/mol,ΔS≠=-28.6eu.These parameters are very close to those in methanol carbonylation and imply to have analogous mechanism in both cases.

  11. Hydrolysis of Carbonyl Sulfide in Binary Mixture of Diethylene Glycol Diethyl Ether and Water

    Institute of Scientific and Technical Information of China (English)

    李新学; 刘迎新; 魏雄辉

    2005-01-01

    The solubility and hydrolysis of carbonyl sulfide in binary mixture of diethylene glycol diethyl ether and water are studied as a function of composition. The use of an aqueous solution of diethylene glycol diethyl ether enhances the solubility and hydrolysis rate of carbonyl sulfide compared with that in pure water. The composition of the mixture with maximum hydrolysis rate varies with temperature. The thermophysical properties including density, viscosity, and surface tension as a function of composition at 20℃ under atmospheric pressure as well as liquid-liquid equilibrium (LLE) data over the temperature range from 28℃ to 90℃ are also measured for the binary mixture.

  12. Improvement on stability of square planar rhodium (Ⅰ) complexes for carbonylation of methanol to acetic acid

    Institute of Scientific and Technical Information of China (English)

    蒋华; 潘平来; 袁国卿; 陈新滋

    1999-01-01

    A series of square planar cis-dicarbonyl polymer coordinated rhodium complexes with uncoordinated donors near the central rhodium atoms for carbonylation of methanol to acetic acid are reported. Data of IR, XPS and thermal analysis show that these complexes are very stable. The intramolecular substitution reaction is proposed for their high stability. These complexes show excellent catalytic activity, selectivity and less erosion to the equipment for the methanol carbonylation to acetic acid. The distillation process may be used instead of flash vaporization in the manufacture of acetic acid, which reduces the investment on the equipment.

  13. Zeolite 5A Catalyzed Etherification of Diphenylmethanol

    Science.gov (United States)

    Cooke, Jason; Henderson, Eric J.; Lightbody, Owen C.

    2009-01-01

    An experiment for the synthetic undergraduate laboratory is described in which zeolite 5A catalyzes the room temperature dehydration of diphenylmethanol, (C[subscript 6]H[subscript 5])[subscript 2]CHOH, producing 1,1,1',1'-tetraphenyldimethyl ether, (C[subscript 6]H[subscript 5])[subscript 2]CHOCH(C[subscript 6]H[subscript 5])[subscript 2]. The…

  14. Catalyzing curriculum evolution in graduate science education.

    Science.gov (United States)

    Gutlerner, Johanna L; Van Vactor, David

    2013-05-09

    Strategies in life science graduate education must evolve in order to train a modern workforce capable of integrative solutions to challenging problems. Our institution has catalyzed such evolution through building a postdoctoral Curriculum Fellows Program that provides a collaborative and scholarly education laboratory for innovation in graduate training.

  15. Mechanochemical ruthenium-catalyzed olefin metathesis.

    Science.gov (United States)

    Do, Jean-Louis; Mottillo, Cristina; Tan, Davin; Štrukil, Vjekoslav; Friščić, Tomislav

    2015-02-25

    We describe the development of a mechanochemical approach for Ru-catalyzed olefin metathesis, including cross-metathesis and ring-closing metathesis. The method uses commercially available catalysts to achieve high-yielding, rapid, room-temperature metathesis of solid or liquid olefins on a multigram scale using either no or only a catalytic amount of a liquid.

  16. Pinacol Coupling Reactions Catalyzed by Active Zinc

    Institute of Scientific and Technical Information of China (English)

    Hui ZHAO; Wei DENG; Qing Xiang GUO

    2005-01-01

    Pinacol coupling reactions catalyzed by active zinc revealed high activity and extensive suitability. The efficiency of the reaction was improved apparently owing to decreasing reductive potential of zinc. In addition, the results indicated that the zinc activity has a direct relation to the coupling reactivity compared to untreated zinc or other general active zinc.

  17. Rhodium-catalyzed restructuring of carbon frameworks.

    Science.gov (United States)

    Murakami, Masahiro

    2010-10-01

    Metal-catalyzed reactions involving an elementary step which cleaves a carbon-carbon bond provide unique organic transformations. Restructuring reactions recently developed in our laboratory, through which the carbon framework of a starting substance is restructured into a totally different carbon framework, are discussed, with the possibility of applying such methods to the synthesis of natural products.

  18. Lysophosphatidylcholine synthesis by lipase-catalyzed ethanolysis.

    Science.gov (United States)

    Yang, Guolong; Yang, Ruoxi; Hu, Jingbo

    2015-01-01

    Lysophosphatidylcholine (LPC) is amphiphilic substance, and possesses excellent physiological functions. In this study, LPC was prepared through ethanolysis of phosphatidylcholine (PC) in n-hexane or solvent free media catalyzed by Novozym 435 (from Candida antarctica), Lipozyme TLIM (from Thermomcyces lanuginosus) and Lipozyme RMIM (from Rhizomucor miehei). The results showed that three immobilized lipases from Candida Antarctica, Thermomcyces lanuginosus and Rhizomucor miehei could catalyze ethanolysis of PC efficiently. In n-hexane, the LPC conversions of ethanolysis of PC catalyzed by Novozyme 435, Lipozyme TLIM and Lipozyme RMIM could reach to 98.5 ± 1.6%, 94.6 ± 1.4% and 93.7 ± 1.8%, respectively. In solvent free media, the highest LPC conversions of ethanolysis of PC catalyzed by Novozyme 435, Lipozyme TL IM and Lipozyme RM IM were 97.7 ± 1.7%, 93.5 ± 1.2% and 93.8 ± 1.9%, respectively. The catalytic efficiencies of the three lipases were in the order of Novozyme 435 > Lipozyme TLIM > Lipozyme RMIM. Furthermore, their catalytic efficiencies in n-hexane were better than those in solvent free media.

  19. Biodiesel production by enzyme-catalyzed transesterification

    Directory of Open Access Journals (Sweden)

    Stamenković Olivera S.

    2005-01-01

    Full Text Available The principles and kinetics of biodiesel production from vegetable oils using lipase-catalyzed transesterification are reviewed. The most important operating factors affecting the reaction and the yield of alkyl esters, such as: the type and form of lipase, the type of alcohol, the presence of organic solvents, the content of water in the oil, temperature and the presence of glycerol are discussed. In order to estimate the prospects of lipase-catalyzed transesterification for industrial application, the factors which influence the kinetics of chemically-catalysed transesterification are also considered. The advantages of lipase-catalyzed transesterification compared to the chemically-catalysed reaction, are pointed out. The cost of down-processing and ecological problems are significantly reduced by applying lipases. It was also emphasized that lipase-catalysed transesterification should be greatly improved in order to make it commercially applicable. The further optimization of lipase-catalyzed transesterification should include studies on the development of new reactor systems with immobilized biocatalysts and the addition of alcohol in several portions, and the use of extra cellular lipases tolerant to organic solvents, intracellular lipases (i.e. whole microbial cells and genetically-modified microorganisms ("intelligent" yeasts.

  20. Proline catalyzed α-aminoxylation reaction in the synthesis of biologically active compounds.

    Science.gov (United States)

    Kumar, Pradeep; Dwivedi, Namrata

    2013-02-19

    The search for new and efficient ways to synthesize optically pure compounds is an active area of research in organic synthesis. Asymmetric catalysis provides a practical, cost-effective, and efficient method to create a variety of complex natural products containing multiple stereocenters. In recent years, chemists have become more interested in using small organic molecules to catalyze organic reactions. As a result, organocatalysis has emerged both as a promising strategy and as an alternative to catalysis with expensive proteins or toxic metals. One of the most successful and widely studied secondary amine-based organocatalysts is proline. This small molecule can catalyze numerous reactions such as the aldol, Mannich, Michael addition, Robinson annulation, Diels-Alder, α-functionalization, α-amination, and α-aminoxylation reactions. Catalytic and enantioselective α-oxygenation of carbonyl compounds is an important reaction to access a variety of useful building blocks for bioactive molecules. Proline catalyzed α-aminoxylation using nitrosobenzene as oxygen source, followed by in situ reduction, gives enantiomerically pure 1,2-diol. This molecule can then undergo a variety of organic reactions. In addition, proline organocatalysis provides access to an assortment of biologically active natural products including mevinoline (a cholesterol lowering drug), tetrahydrolipstatin (an antiobesity drug), R(+)-α-lipoic acid, and bovidic acid. In this Account, we present an iterative organocatalytic approach to synthesize both syn- and anti-1,3-polyols, both enantio- and stereoselectively. This method is primarily based on proline-catalyzed sequential α-aminoxylation and Horner-Wadsworth-Emmons (HWE) olefination of aldehyde to give a γ-hydroxy ester. In addition, we briefly illustrate the broad application of our recently developed strategy for 1,3-polyols, which serve as valuable, enantiopure building blocks for polyketides and other structurally diverse and