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Sample records for acid catalyzed friedel-crafts

  1. Lewis Acid Catalyzed Friedel-Crafts Alkylation of Alkenes with Trifluoropyruvates.

    Science.gov (United States)

    Xiang, Bin; Xu, Teng-Fei; Wu, Liang; Liu, Ren-Rong; Gao, Jian-Rong; Jia, Yi-Xia

    2016-05-01

    A Friedel-Crafts alkylation reaction of styrenes with trifluoropyruvates has been developed, which delivered allylic alcohols in excellent yields (up to 98%) using the Ni(ClO4)2·6H2O/bipyridine complex as a catalyst. The asymmetric reaction was catalyzed by the chiral Cu(OTf)2/bisoxazoline complex to afford the corresponding chiral allylic alcohols bearing trifluoromethylated quaternary stereogenic centers in moderate enantioselectivities (up to 75% ee). PMID:27028539

  2. The synthesis of mono- and diacetyl-9H-fluorenes. Reactivity and selectivity in the Lewis acid catalyzed Friedel-Crafts acetylation of 9H-fluorene

    DEFF Research Database (Denmark)

    Titinchi, Salam J.J.; Kamounah, Fadhil S.; Abbo, Hanna S.;

    2008-01-01

    Friedel-Crafts acetylation of 9H-fluorene is an effective route for the preparation of mono- and diacetyl-9H-fluorenes. Using acetylchloride as the reagent and aluminum chloride as the Lewis acid catalyst the effect of the solvent polarity, the temperature, the reaction time and the mode of addit......Friedel-Crafts acetylation of 9H-fluorene is an effective route for the preparation of mono- and diacetyl-9H-fluorenes. Using acetylchloride as the reagent and aluminum chloride as the Lewis acid catalyst the effect of the solvent polarity, the temperature, the reaction time and the mode...

  3. Friedel-Crafts alkylation of indoles with nitroalkenes catalyzed by Cu(Ⅱ)-imine complex

    Institute of Scientific and Technical Information of China (English)

    Ning Ning Wan; Yong Lei Yang; Wen Ping Wang; Zheng Feng Xie; Ji De Wang

    2011-01-01

    A series of new ligands L1-L7 were readily prepared in one step. Friedel-Crafts alkylation of indoles with nitroalkenes catalyzed by a novel Cu(Ⅱ)-L complex has been developed. The remarkable advantages of this reaction are mild reaction conditions, simple workup procedure, high yields of products and the use of ethanol as a green solvent.

  4. Organocatalytic Enantioselective Aza-Friedel-Crafts Reaction of Cyclic Ketimines with Pyrroles using Imidazolinephosphoric Acid Catalysts.

    Science.gov (United States)

    Nakamura, Shuichi; Matsuda, Nazumi; Ohara, Mutsuyo

    2016-07-01

    Organocatalytic enantioselective aza-Friedel-Crafts reactions of cyclic ketimines with pyrroles or indoles were catalyzed by imidazoline/phosphoric acid catalysts. The reaction was applied to various 3H-indol-3-ones to afford products in excellent yields and enantioselectivities. The chiral catalysts can be recovered by a single separation step using column chromatography and are reusable without further purification. Based on the experimental investigations, a possible transition state has been proposed to explain the origin of the asymmetric induction. PMID:27124556

  5. The synthesis of mono- and diacetyl-9H-fluorenes. Reactivity and selectivity in the Lewis acid catalyzed Friedel-Crafts acetylation of 9H-fluorene

    DEFF Research Database (Denmark)

    Titinchi, Salam J.J.; Kamounah, Fadhil S.; Abbo, Hanna S.;

    2008-01-01

    Friedel-Crafts acetylation of 9H-fluorene is an effective route for the preparation of mono- and diacetyl-9H-fluorenes. Using acetylchloride as the reagent and aluminum chloride as the Lewis acid catalyst the effect of the solvent polarity, the temperature, the reaction time and the mode of......-fluorene was obtained in 5-11 % yield when carbon disulfide was used as the solvent. Acetylation of 9H-fluorene in dichloroethane and carbon disulfide, using an excess of acetyl chloride and aluminum chloride at reflux temperature, gives 2,7-diacetyl-9H-fluorene exclusively in high yields (> 97%). Attempts to...

  6. A practical synthesis of 3,4-diethoxybenzthioamide based on Friedel-Crafts reaction with potassium thiocyanate in methanesulfonic acid.

    Science.gov (United States)

    Aki, Shinji; Fujioka, Takafumi; Ishigami, Masashi; Minamikawa, Jun-ichi

    2002-09-01

    The synthesis of 3,4-diethoxybenzthioamide, the key intermediate for OPC-6535, is achieved by employing Friedel-Crafts reaction of 1,2-diethoxybenzene with potassium thiocyanate in methanesulfonic acid at ambient temperature.

  7. One-pot Synthesis of Lewis Acidic Ionic Liquids for Friedel-Crafts Alkylation

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Novel Lewis acidic ionic liquids containing thionyl cations and chloroaluminate anions were obtained by one-pot synthesis for the first time. Their acidities were determined by acetonitrile probe on IR spectrography. The ionic liquids were used as catalyst for Friedel-Crafts alkylation of benzene and 1-dodecene. The turnovers of 1-dodecene were higher than 99%. Monoalkylbenzene selectivity was 98%, while the 2-substituent product selectivity was 45%.

  8. Platinum-Catalyzed Friedel-Crafts-Type C-H Coupling-Allylic Amination Cascade to Synthesize 3,4-Fused Tricyclic Indoles.

    Science.gov (United States)

    Suzuki, Yuta; Tanaka, Yuito; Nakano, Shun-ichi; Dodo, Kosuke; Yoda, Natsumi; Shinohara, Ken-Ichi; Kita, Kazuko; Kaneda, Atsushi; Sodeoka, Mikiko; Hamada, Yasumasa; Nemoto, Tetsuhiro

    2016-03-18

    A novel platinum-catalyzed cascade cyclization reaction was developed by intramolecular Friedel-Crafts-type C-H coupling of aniline derivatives with a propargyl carbonate unit-allylic amination sequence. Treatment of various propargyl carbonates tethered to meta-aniline derivatives with a Pt(dba)3/DPEphos catalyst system afforded the corresponding 3,4-fused tricyclic 3-alkylidene indolines in 42-99% yield, which were transformed into 3,4-fused indole derivatives by reaction with trifluoroacetic acid. The reaction products exhibited antiproliferative activities against cancer cells, but not normal cells, revealing the potential usefulness of this reaction for medicinal chemistry. PMID:26833557

  9. Catalytic Friedel-Crafts reaction of aminocyclopropanes.

    Science.gov (United States)

    de Nanteuil, Florian; Loup, Joachim; Waser, Jérôme

    2013-07-19

    A Lewis acid catalyzed Friedel-Crafts reaction between donor-acceptor aminocyclopropanes and indoles and other electron-rich aromatic compounds is reported. Indole alkylation at the C3 position was generally obtained for a broad range of functional groups and substitution patterns. In the case of C3-substituted indoles, C2 alkylation was observed. The reaction gives a rapid access to gamma amino acid derivatives present in numerous bioactive molecules. PMID:23815365

  10. An efficient combination of Zr-MOF and microwave irradiation in catalytic Lewis acid Friedel-Crafts benzoylation.

    Science.gov (United States)

    Doan, Tan L H; Dao, Thong Q; Tran, Hai N; Tran, Phuong H; Le, Thach N

    2016-05-01

    A zirconium-based metal-organic framework, an effective heterogeneous catalyst, has been developed for the Friedel-Crafts benzoylation of aromatic compounds under microwave irradiation. Constructed by a Zr(iv) cluster and a linker 1,4-bis(2-[4-carboxyphenyl]ethynyl)benzene (H2CPEB), the MOF, possessing large pores and high chemical stability, was appropriate for the enhancement of Lewis acid activity under microwave irradiation. The reaction studies demonstrated that the material could give high yields for a few minutes and maintain its reactivity and structure over several cycles. PMID:27064371

  11. Heteropoly acid encapsulated into zeolite imidazolate framework (ZIF-67) cage as an efficient heterogeneous catalyst for Friedel-Crafts acylation

    Science.gov (United States)

    Ammar, Muhammad; Jiang, Sai; Ji, Shengfu

    2016-01-01

    A new strategy has been developed for the encapsulation of the phosphotungstic heteropoly acid (H3PW12O40 denoted as PTA) into zeolite imidazolate framework (ZIF-67) cage and the PTA@ZIF-67(ec) catalysts with different PTA content were prepared. The structure of the catalysts was characterized by XRD, BET, SEM, FT-IR, ICP-AES and TG. The catalytic activity and recovery properties of the catalysts for the Friedel-Crafts acylation of anisole with benzoyl chloride were evaluated. The results showed that 14.6-31.7 wt% PTA were encapsulated in the ZIF-67 cage. The PTA@ZIF-67(ec) catalysts had good catalytic activity for Friedel-Crafts acylation. The conversion of anisole can reach ~100% and the selectivity of the production can reach ~94% over 26.5 wt% PTA@ZIF-67(ec) catalyst under the reaction condition of 120 °C and 6 h. After reaction, the catalyst can be easily separated from the reaction mixture by the centrifugation. The recovered catalyst can be reused five times and the selectivity can be kept over 90%.

  12. Metal halide hydrates as lewis acid catalysts for the conjugated friedel-crafts reactions of indoles and activated olefins

    Energy Technology Data Exchange (ETDEWEB)

    Schwalm, Cristiane S.; Ceschi, Marco Antonio; Russowsky, Dennis, E-mail: dennis@iq.ufrgs.b [Universidade Federal do Rio Grande do Sul (IQ/UFRGS), Porto Alegre, RS (Brazil). Inst. de Quimica

    2011-07-01

    Metal halide hydrates such as SnCl{sub 2{center_dot}}2H{sub 2}O, MnCl{sub 2{center_dot}}4H{sub 2}O, SrCl{sub 2{center_dot}}6H{sub 2}O, CrCl{sub 2{center_dot}}6H{sub 2}O, CoCl{sub 2{center_dot}}6H{sub 2}O e CeCl{sub 3{center_dot}}7H{sub 2}O were investigated as mild Lewis acids catalysts for the conjugate Friedel-Crafts reaction between indoles and activated olefins. The reactions were carried out with aliphatic unsaturated ketones over a period of days at room temperature, while chalcones reacted only under reflux conditions. The reactions with nitrostyrene s were either performed in solvent or under solventless conditions. In all cases reasonable to good yields were obtained. (author)

  13. Methanetrisulfonic Acid: A Highly Efficient Strongly Acidic Catalyst for Wagner-Meerwein Rearrangement, Friedel-Crafts Alkylation and Acylation Reactions. Examples from Vitamin E Synthesis

    OpenAIRE

    Francesco Pace; Thomas Netscher; Simone Hoppmann; Alois Haas; Fabrice Aquino; Werner Bonrath; Horst Pauling

    2009-01-01

    Methanetrisulfonic acid had been prepared for the first time over 140 years ago, but it was used only scarcely in chemical transformations. In the course of our activities dealing with key-steps of industrial syntheses of vitamins, e.g. economically important vitamin E (acetate), we found that methanetrisulfonic acid is an extremely effective catalyst in a variety of reactions. Examples of its applications are Wagner-Meerwein rearrangements, Friedel-Crafts alkylations and ring closures, as we...

  14. Methanetrisulfonic Acid: A Highly Efficient Strongly Acidic Catalyst for Wagner-Meerwein Rearrangement, Friedel-Crafts Alkylation and Acylation Reactions. Examples from Vitamin E Synthesis

    Directory of Open Access Journals (Sweden)

    Francesco Pace

    2009-04-01

    Full Text Available Methanetrisulfonic acid had been prepared for the first time over 140 years ago, but it was used only scarcely in chemical transformations. In the course of our activities dealing with key-steps of industrial syntheses of vitamins, e.g. economically important vitamin E (acetate, we found that methanetrisulfonic acid is an extremely effective catalyst in a variety of reactions. Examples of its applications are Wagner-Meerwein rearrangements, Friedel-Crafts alkylations and ring closures, as well as acylation reactions. Use of this catalyst in truly catalytic amounts (0.04-1.0 mol% resulted in highly selective transformations and yields over 95%. (Remark by the authors: We are describing only one example each for the various types of reactions. Therefore, it would be more appropriate to write (here and in the Introduction and in the Conclusion sections: “Wagner-Meerwein rearrangement, Friedel-Crafts alkylation and ring closure, as well as acylation reactions”

  15. Cu(I)-Catalyzed Enantioselective Friedel-Crafts Alkylation of Indoles with 2-Aryl-N-sulfonylaziridines as Alkylating Agents.

    Science.gov (United States)

    Ge, Chen; Liu, Ren-Rong; Gao, Jian-Rong; Jia, Yi-Xia

    2016-07-01

    A highly enantioselective Friedel-Crafts alkylation of indoles with N-sulfonylaziridines as alkylating agents has been developed by utilizing the complex of Cu(CH3CN)4BF4/(S)-Segphos as a catalyst. A range of optically active tryptamine derivatives are obtained in good to excellent yields and enantioselectivities (up to >99% ee) via a kinetic resolution process. PMID:27309541

  16. Facile synthesis of nonsymmetrical heteroaryl-substituted triarylmethanes via the FeCl3·6H2O-catalyzed two-step Friedel-Crafts-type reaction.

    Science.gov (United States)

    Ruengsangtongkul, S; Taprasert, P; Sirion, U; Jaratjaroonphong, J

    2016-09-28

    The FeCl3·6H2O-catalyzed three-component aza-Friedel-Crafts reaction of aromatic/heteroaromatic compounds, aromatic aldehydes and tert-butyl carbamate was reported. The subsequent Friedel-Crafts-type alkylation of the resulting tert-butyl diarylmethyl carbamate with heteroaromatic compounds under "open-flask" at room temperature was also performed. The two-step reaction was especially useful for the synthesis of functionalized nonsymmetrical heteroaryl-substituted triarylmethanes in good yields under an air atmosphere at room temperature. PMID:27541849

  17. Temperature Dual Enantioselective Control in a Rhodium-Catalyzed Michael-Type Friedel-Crafts Reaction: A Mechanistic Explanation.

    Science.gov (United States)

    Méndez, Isabel; Rodríguez, Ricardo; Polo, Víctor; Passarelli, Vincenzo; Lahoz, Fernando J; García-Orduña, Pilar; Carmona, Daniel

    2016-07-25

    By changing the temperature from 283 to 233 K, the S (99 % ee) or R (96 % ee) enantiomer of the Friedel-Crafts (FC) adduct of the reaction between N-methyl-2-methylindole and trans-β-nitrostyrene can be obtained by using (SRh ,RC )-[(η(5) -C5 Me5 )Rh{(R)-Prophos}(H2 O)][SbF6 ]2 as the catalyst precursor. This catalytic system presents two other uncommon features: 1) The ee changes with reaction time showing trends that depend on the reaction temperature and 2) an increase in the catalyst loading results in a decrease in the ee of the S enantiomer. Detection and characterization of the intermediate metal-nitroalkene and metal-aci-nitro complexes, the free aci-nitro compound, and the FC adduct-complex, together with solution NMR measurements, theoretical calculations, and kinetic studies have allowed us to propose two plausible alternative catalytic cycles. On the basis of these cycles, all the above-mentioned observations can be rationalized. In particular, the reversibility of one of the cycles together with the kinetic resolution of the intermediate aci-nitro complexes account for the high ee values achieved in both antipodes. On the other hand, the results of kinetic measurements explain the unusual effect of the increment in catalyst loading. PMID:27345293

  18. Sulfamic acid as a cost-effective and recyclable solid acid catalyst for Friedel-Crafts alkylation of indole with α,β-unsaturated carbonyl compound and benzyl alcohol

    Institute of Scientific and Technical Information of China (English)

    Jing Yang; Juan Zhang; Tian Tian Chen; De Mei Sun; Ji Li; Xue Fen Wu

    2011-01-01

    Sulfamic acid was proved to be a cost-effective and recyclable catalyst for Friedel-Crafts type reaction of indole with α,β-unsaturated carbonyl compound and benzyl alcohol. Various indoles, α,β-unsaturated carbonyl compounds and a benzyl alcohol were successfully used in this type of reaction, and the corresponding products were obtained in good to excellent yields.

  19. A Quinine-Squaramide Catalyzed Enantioselective Aza-Friedel-Crafts Reaction of Cyclic Trifluoromethyl Ketimines with Naphthols and Electron-Rich Phenols.

    Science.gov (United States)

    Zhou, Ding; Huang, Zheng; Yu, Xueting; Wang, Youxin; Li, Jian; Wang, Wei; Xie, Hexin

    2015-11-20

    A highly enantioselective aza-Friedel-Crafts (aza-F-C) reaction of cyclic trifluoromethyl ketimines and naphthols/phenols was developed with fluorenyl-substituted quinine-squaramide as the catalyst. This protocol enables direct access to biologically important chiral trifluoromethyl dihydroquinazolinones with up to 99% yields and up to 99% ee's.

  20. Chelation-assisted Pd-catalysed ortho-selective oxidative C-H/C-H cross-coupling of aromatic carboxylic acids with arenes and intramolecular Friedel-Crafts acylation: one-pot formation of fluorenones.

    Science.gov (United States)

    Sun, Denan; Li, Bijin; Lan, Jingbo; Huang, Quan; You, Jingsong

    2016-03-01

    Pd-Catalysed ortho-selective oxidative C-H/C-H cross-coupling of aromatic carboxylic acids with arenes and subsequent intramolecular Friedel-Crafts acylation has been accomplished for the first time through a chelation-assisted C-H activation strategy. Starting from the readily available substrates, a variety of fluorenone derivatives are obtained in one pot. The direct use of naturally occurring carboxylic acid functionalities as directing groups avoids unnecessary steps for installation and removal of an extra directing group. PMID:26861768

  1. Friedel-Crafts Alkylation of Indoles with p-Quinols: The Role of Hydrogen Bonding of Water for the Desymmetrization of the Cyclohexadienone System.

    Science.gov (United States)

    García-García, Carolina; Ortiz-Rojano, Laura; Álvarez, Susana; Álvarez, Rosana; Ribagorda, María; Carreño, M Carmen

    2016-05-01

    Lewis acid catalyzed Friedel-Crafts alkylation of indoles has been achieved in high yields and selectivities using p-quinols as electrophiles. (S)-Binol-3,3'-(9-anthracenyl)-phosphoric acid was able to catalyze the enantioselective formation of 5-(3-indole)-2-cyclohexenone derivatives. Experimental results and theoretical calculations explained the enantioselectivity based on a transition state where two water molecules act as a tether joining the p-quinol with the phosphoric acid and the NH of indole, thus facilitating the desymmetrization of the prochiral cyclohexadienone framework. PMID:27088217

  2. Enantioselective Friedel-Crafts Alkylation Reactions of 3-Substituted Indoles with Electron-Deficient Alkenes.

    Science.gov (United States)

    Weng, Jian-Quan; Fan, Ren-Jie; Deng, Qiao-Man; Liu, Ren-Rong; Gao, Jian-Rong; Jia, Yi-Xia

    2016-04-01

    Highly enantioselective Friedel-Crafts C2-alkylation reactions of 3-substituted indoles with α,β-unsaturated esters and nitroalkenes were developed using chiral Lewis acids as catalysts, which afforded chiral indole derivatives bearing C2-benzylic stereogenic centers in good to excellent yields (up to 99%) and enantioselectivities (up to 96% ee). PMID:26959867

  3. Enantioselective Organocatalytic Construction of Spiroindane Derivatives by Intramolecular Friedel-Crafts-Type 1,4-Addition.

    Science.gov (United States)

    Yoshida, Keisuke; Itatsu, Yukihiro; Fujino, Yuta; Inoue, Hiroki; Takao, Ken-Ichi

    2016-06-01

    The highly enantioselective organocatalytic construction of spiroindanes containing an all-carbon quaternary stereocenter by intramolecular Friedel-Crafts-type 1,4-addition is described. The reaction was catalyzed by a cinchonidine-based primary amine and accelerated by water and p-bromophenol. A variety of spiro compounds containing quaternary stereocenters were obtained with excellent enantioselectivity (up to 95 % ee). The reaction was applied to the asymmetric formal synthesis of the spirocyclic natural products (-)-cannabispirenones A and B. PMID:27111396

  4. Friedel-Crafts Fluoroacetylation of Indoles with Fluorinated Acetic Acids for the Synthesis of Fluoromethyl Indol-3-yl Ketones under Catalyst- and Additive-Free Conditions.

    Science.gov (United States)

    Yao, Shun-Jiang; Ren, Zhi-Hui; Wang, Yao-Yu; Guan, Zheng-Hui

    2016-05-20

    A simple and efficient protocol for the fluoroacetylation of indoles is reported. The reaction uses fluorinated acetic acids as the fluoroacetylation reagents to synthesize diverse fluoromethyl indol-3-yl ketones in good yields under catalyst- and additive-free conditions. In addition, the only byproduct is water in this transformation. The synthetic utility of this reaction was also demonstrated by the concise synthesis of α-(trifluoromethyl)(indol-3-yl)methanol and indole-3-carboxylic acid. PMID:27101475

  5. Brønsted Acid-Promoted Formation of Stabilized Silylium Ions for Catalytic Friedel-Crafts C-H Silylation.

    Science.gov (United States)

    Chen, Qing-An; Klare, Hendrik F T; Oestreich, Martin

    2016-06-29

    A counterintuitive approach to electrophilic aromatic substitution with silicon electrophiles is disclosed. A strong Brønsted acid that would usually promote the reverse reaction, i.e., protodesilylation, was found to initiate the C-H silylation of electron-rich (hetero)arenes with hydrosilanes. Protonation of the hydrosilane followed by liberation of dihydrogen is key to success, fulfilling two purposes: to generate the stabilized silylium ion and to remove the proton released from the Wheland intermediate. PMID:27303857

  6. A Research-Based Undergraduate Organic Laboratory Project: Investigation of a One-Pot, Multicomponent, Environmentally Friendly Prins-Friedel-Crafts-Type Reaction

    Science.gov (United States)

    Dintzner, Matthew R.; Maresh, Justin J.; Kinzie, Charles R.; Arena, Anthony F.; Speltz, Thomas

    2012-01-01

    Students in the undergraduate organic laboratory synthesize tetrahydro-2-(4-nitrophenyl)-4-phenyl-2"H"-pyran via the Montmorillonite K10 clay-catalyzed reaction of p-nitrobenzaldehye with methanol, 3-buten-1-ol, and benzene. The synthesis comprises an environmentally friendly tandem Prins-Friedel-Crafts-type multicomponent reaction (MCR) and sets…

  7. A reactivity-selectivity study of the Friedel-Crafts acetylation of 3,3′-dimethylbiphenyl and the oxidation of the acetyl derivatives

    DEFF Research Database (Denmark)

    Titinchi, Salam JJ; Kamounah, Fadhil S.; Abbo, Hanna S.;

    2012-01-01

    Background: Friedel-Crafts acetylation is an important route to aromatic ketones, in research laboratories and in industry. The acetyl derivatives of 3,3'-dimethylbiphenyl (3,3'-dmbp) have applications in the field of liquid crystals and polymers and may be oxidized to the dicarboxylic acids...... converted to the carboxylic acids by hypochlorite oxidation. The relative stabilities of the isomeric products and the corresponding s-complexes were studied by DFT calculations and the data indicated that mono-and diacetylation followed different mechanisms. Conclusions: Friedel-Crafts acetylation of 3...

  8. Environmentally benign Friedel-Crafts benzylation over nano-TiO2/SO4 2-

    Science.gov (United States)

    Devi, Kalathiparambil RPS; Sreeja, Puthenveetil B.; Sugunan, Sankaran

    2013-05-01

    During the past decade, much attention has been paid to the replacement of homogeneous catalysts by solid acid catalysts. Friedel-Crafts benzylation of toluene with benzyl chloride (BC) in liquid phase was carried out over highly active, nano-crystalline sulfated titania systems. These catalysts were prepared using the sol gel method. Modification was done by loading 3% of transition metal oxides over sulfated titania. Reaction parameters such as catalyst mass, molar ratio, temperature, and time have been studied. More than 80% conversion of benzyl chloride and 100% selectivity are shown by all the catalysts under optimum conditions. Catalytic activity is correlated with Lewis acidity obtained from perylene adsorption studies. The reaction appears to proceed by an electrophile, which involves the reaction of BC with the acidic titania catalyst. The catalyst was regenerated and reused up to four reaction cycles with equal efficiency as in the first run. The prepared systems are environmentally friendly and are easy to handle.

  9. Polystyrene or Magnetic Nanoparticles as Support in Enantioselective Organocatalysis? A Case Study in Friedel-Crafts Chemistry.

    Science.gov (United States)

    Ranjbar, Sara; Riente, Paola; Rodríguez-Escrich, Carles; Yadav, Jagjit; Ramineni, Kishore; Pericàs, Miquel A

    2016-04-01

    Heterogenized versions of the second-generation MacMillan imidazolidin-4-one are described for the first time. This versatile organocatalyst has been supported on 1% DVB Merrifield resin and Fe3O4 magnetic nanoparticles through a copper-catalyzed alkyne-azide cycloaddition (CuAAC) reaction. The resulting catalytic materials have been successfully applied to the asymmetric Friedel-Crafts alkylation of indoles with α,β-unsaturated aldehydes. While both catalytic systems can be easily recovered and admit repeated recycling, the polystyrene-based catalyst shows higher stability and provides better stereoselectivities. PMID:27010999

  10. A Zeolite Imidazolate Framework ZIF-8 Catalyst for Friedel-Crafts Acylation

    Institute of Scientific and Technical Information of China (English)

    LienT.L.NGUYEN; Ky K.A.LE; Nam T.S.PHAN

    2012-01-01

    A zeolite imidazolate framework,ZIF-8,was synthesized and characterized by dynamic laser light scattering,X-ray powder diffraction,scanning electron microscopy,transmission electron microscopy,thermogravimetric analysis,Fourier transform infrared,atomic absorption spectrophotometry,and nitrogen adsorption measurements.The ZIF-8 was highly crystalline and porous with a surface area of over 1600 m2/g.Friedel-Crafts acylation of anisole and benzoyl chloride proceeded well in the presence of ZIF-8 (2-6 mol%) without the need for an inert atmosphere.The reaction afforded a selectivity of 93%-95% to the p-isomer.The solid catalyst can be separated from the reaction mixture by simple centrifugation and reused without significant degradation in catalytic activity.There was no leaching of active acid species into the reaction solution.

  11. Sterically-controlled intermolecular Friedel-Crafts acylation with twisted amides via selective N-C cleavage under mild conditions.

    Science.gov (United States)

    Liu, Yongmei; Meng, Guangrong; Liu, Ruzhang; Szostak, Michal

    2016-05-21

    Highly chemoselective Friedel-Crafts acylation with twisted amides under mild conditions is reported for the first time. The reaction shows high functional group tolerance, obviating the need for preformed sensitive organometallic reagents and expensive transition metal catalysts. The high reactivity of amides is switched on by ground-state steric distortion to disrupt the amide bond nN→πCO* resonance as a critical design feature. Conceptually, this new acid-promoted mechanism of twisted amides provides direct access to bench-stable acylating reagents under mild, metal-free conditions. PMID:27139813

  12. Lewis Acid Catalyzed Selective Reactions of Donor-Acceptor Cyclopropanes with 2-Naphthols.

    Science.gov (United States)

    Kaicharla, Trinadh; Roy, Tony; Thangaraj, Manikandan; Gonnade, Rajesh G; Biju, Akkattu T

    2016-08-16

    Lewis acid-catalyzed reactions of 2-substituted cyclopropane 1,1-dicarboxylates with 2-naphthols is reported. The reaction exhibits tunable selectivity depending on the nature of Lewis acid employed and proceed as a dearomatization/rearomatization sequence. With Bi(OTf)3 as the Lewis acid, a highly selective dehydrative [3+2] cyclopentannulation takes place leading to the formation of naphthalene-fused cyclopentanes. Interestingly, engaging Sc(OTf)3 as the Lewis acid, a Friedel-Crafts-type addition of 2-naphthols to cyclopropanes takes place, thus affording functionalized 2-naphthols. Both reactions furnished the target products in high regioselectivity and moderate to high yields. PMID:27391792

  13. A reactivity-selectivity study of the Friedel-Crafts acetylation of 3,3'-dimethylbiphenyl and the oxidation of the acetyl derivatives

    DEFF Research Database (Denmark)

    Titinchi, Salam J.J.; Kamounah, Fadhil S.; Abbo, Hanna S.;

    2012-01-01

    Background: Friedel-Crafts acetylation is an important route to aromatic ketones, in research laboratories and in industry. The acetyl derivatives of 3,3'-dimethylbiphenyl (3,3'-dmbp) have applications in the field of liquid crystals and polymers and may be oxidized to the dicarboxylic acids and...... converted to the carboxylic acids by hypochlorite oxidation. The relative stabilities of the isomeric products and the corresponding s-complexes were studied by DFT calculations and the data indicated that mono-and diacetylation followed different mechanisms. Conclusions: Friedel-Crafts acetylation of 3...... derivatives that are of interest in cancer treatment. Findings: The effect of solvent and temperature on the selectivity of monoacetylation of 3,3'-dmbp by the Perrier addition procedure was studied using stoichiometric amounts of reagents. 4-Ac-3,3'-dmbp was formed almost quantitatively in boiling 1...

  14. Facile construction of pyrrolo[1,2-b]isoquinolin-10(5H)-ones via a redox-amination-aromatization-Friedel-Crafts acylation cascade reaction and discovery of novel topoisomerase inhibitors.

    Science.gov (United States)

    Wu, Shanchao; Liu, Na; Dong, Guoqiang; Ma, Lin; Wang, Shengzheng; Shi, Wencai; Fang, Kun; Chen, Shuqiang; Li, Jian; Zhang, Wannian; Sheng, Chunquan; Wang, Wei

    2016-07-21

    An efficient redox-amination-aromatization-Friedel-Crafts acylation cascade process from trans-4-hydroxyproline and 2-formylbenzoic acids has been developed for the synthesis of pyrrolo[1,2-b]isoquinolin-10(5H)-ones. Compound 3h was identified as a new potent dual topoisomerase I/II inhibitor. PMID:27400278

  15. Poly(vinyl chloride-grafted multi-walled carbon nanotubes via Friedel-Crafts alkylation

    Directory of Open Access Journals (Sweden)

    2010-11-01

    Full Text Available A novel approach was developed for the surface modification of the multi-walled carbon nanotubes (MWCNTs with high percentage of grafting (PG% by the grafting of polymer via the Friedel-Crafts alkylation. The graft reaction conditions, such as the amount of catalyst added, the reaction temperature, and the reaction time were optimized for the Friedel-Crafts alkylation of the MWCNTs with poly(vinyl chloride (PVC with anhydrous aluminum chloride (AlCl3 as catalyst in chloroform (CHCl3. The Fourier Transform Infrared (FT-IR, Raman, and thermogravimetric (TGA analysis showed that PVC had been successfully grafted onto MWCNTs both at the ends and on the sidewalls by the proposed Friedel-Crafts alkylation. The PVC grafted MWCNTs (PVC-MWCNTs could be dispersed well in organic solvent and the dispersion was more stable.

  16. Highly enantioselective synthesis of beta-heteroaryl-substituted dihydrochalcones through Friedel-Crafts alkylation of indoles and pyrrole.

    Science.gov (United States)

    Wang, Wentao; Liu, Xiaohua; Cao, Weidi; Wang, Jun; Lin, Lili; Feng, Xiaoming

    2010-02-01

    A highly enantioselective Friedel-Crafts (F-C) alkylation of indoles and pyrrole with chalcone derivatives catalyzed by a chiral N,N'-dioxide-Sc(OTf)(3) complex has been developed that tolerates a wide range of substrates. The reaction proceeds in moderate to excellent yields and high enantioselectivities (85-92 % enantiomeric excess) using 2 mol % (for indole) or 0.5 mol % (for pyrrole) catalyst loading, which showed the potential value of the catalyst system. Meanwhile, a strong positive nonlinear effect was observed. On the basis of the experimental results and previous reports, a possible working model is proposed to explain the origin of the activation and asymmetric induction. PMID:20013964

  17. Stereoselective Synthesis of Spiro Bis-C,C-α-arylglycosides by Tandem Heck Type C-Glycosylation and Friedel-Crafts Cyclization.

    Science.gov (United States)

    Chen, Yen-Bo; Liu, Shi-Hao; Hsieh, Min-Tsang; Chang, Chih-Shiang; Lin, Chun-Hung; Chen, Chen-Yin; Chen, Po-Yen; Lin, Hui-Chang

    2016-04-01

    Spiro bis-C,C-α-arylglycosides were synthesized in three steps in 78-85% overall yields starting from exo-glycals. The initial Heck type C-aryl addition of exo-glycals with arylboronic acids afforded α-aryl-β-substituted C-glycosides with exclusive α-stereoselectivity. Among the products, β-ethanal α-aryl C-glycosides further reacted with alkylthiol in the presence of InCl3, followed by in situ Friedel-Crafts cyclization to yield the desirable final products. We proposed a mechanism to explain how the α-aryl group serves as a main determinant of the cyclization. PMID:26986781

  18. Tetranuclear Zn/4f coordination clusters as highly efficient catalysts for Friedel-Crafts alkylation.

    Science.gov (United States)

    Griffiths, Kieran; Kumar, Prashant; Akien, Geoffrey R; Chilton, Nicholas F; Abdul-Sada, Alaa; Tizzard, Graham J; Coles, Simon J; Kostakis, George E

    2016-06-14

    A series of custom-designed, high yield, isoskeletal tetranuclear Zn/4f coordination clusters showing high efficiency as catalysts with low catalytic loadings in Friedel-Crafts alkylation are described for the first time. The possibility of altering the 4f centers in these catalysts without altering the core topology allows us to further confirm their stability via EPR and NMR, as well to gain insights into the plausible reaction mechanism, showcasing the usefulness of these bimetallic systems as catalysts. PMID:27248829

  19. Benzylic Phosphates in Friedel-Crafts Reactions with Activated and Unactivated Arenes: Access to Polyarylated Alkanes.

    Science.gov (United States)

    Pallikonda, Gangaram; Chakravartya, Manab

    2016-03-01

    Easily reachable electron-poor/rich primary and secondary benzylic phosphates are suitably used as substrates for Friedel-Crafts benzylation reactions with only 1.2 equiv activated/deactivated arenes (no additional solvent) to access structurally and electronically diverse polyarylated alkanes with excellent yields and selectivities at room temperature. Specifically, diversely substituted di/triarylmethanes are generated within 2-30 min using this approach. A wide number of electron-poor polyarylated alkanes are easily accomplished through this route by just tuning the phosphates. PMID:26835977

  20. Catalytic Selenium-Promoted Intermolecular Friedel-Crafts Alkylation with Simple Alkenes.

    Science.gov (United States)

    Tang, E; Zhao, Yinjiao; Li, Wen; Wang, Weilin; Zhang, Meng; Dai, Xin

    2016-03-01

    A method for conducting selenium-promoted intermolecular Friedel-Crafts (F-C) alkylation reactions has been developed with simple alkenes using trimethylsilyl trifluoromethanesulfonate as a catalyst and N-phenylselenophthalimide as an efficient selenium source. Electron-rich arenes smoothly underwent F-C alkylation with a variety of alkenes to afford alkylated products in good yield and with high regioselectivity and diastereoselectivity. The regioselectivity and stereoselectivity of arenes and alkenes as well as a preliminary mechanism of the F-C alkylation reaction are discussed. PMID:26882088

  1. Friedel-Crafts Polyketones: Synthesis, Characterization and Antimicrobial Properties of Unsaturated Polyketones and Copolyketones Based on Difurfurylidene Cycloheptanone

    Directory of Open Access Journals (Sweden)

    Nayef S. Al-Muaikel

    2011-01-01

    Full Text Available A new type of unsaturated polyketones and copolyketones having cycloheptanone moiety in a p-conjugated main chain were synthesized via Friedel-Crafts reaction through the polymerization of the monomer: 2,7-bis furfurylidene cycloheptanone I with different diacid chlorides. The model compound was synthesized by reacting I with benzoyl chloride and characterized by 1H-NMR, IR, and elemental analyses. The polyketones and copolyketones were soluble easily in protic solvents like H2SO4 and trifluoroacetic acid. The thermal properties of these polyketones and copolyketones were evaluated and correlated to their structural units by TGA and DSC measurements. The crystallinity of some polymers was tested by X-ray analyses; also the morphological properties of selected examples of poly and copolyketones were detected by SEM. All the polyketones were tested for their biological activity against bacteria, fungi, and yeast. It was observed that the majority of the polyketones and its copolymers synthesized can be used as antibacterial and antifungal agents.

  2. Friedel-Crafts Crosslinked Highly Sulfonated Polyether Ether Ketone (SPEEK) Membranes for a Vanadium/Air Redox Flow Battery.

    Science.gov (United States)

    Merle, Géraldine; Ioana, Filipoi Carmen; Demco, Dan Eugen; Saakes, Michel; Hosseiny, Seyed Schwan

    2013-12-30

    Highly conductive and low vanadium permeable crosslinked sulfonated poly(ether ether ketone) (cSPEEK) membranes were prepared by electrophilic aromatic substitution for a Vanadium/Air Redox Flow Battery (Vanadium/Air-RFB) application. Membranes were synthesized from ethanol solution and crosslinked under different temperatures with 1,4-benzenedimethanol and ZnCl2 via the Friedel-Crafts crosslinking route. The crosslinking mechanism under different temperatures indicated two crosslinking pathways: (a) crosslinking on the sulfonic acid groups; and (b) crosslinking on the backbone. It was observed that membranes crosslinked at a temperature of 150 °C lead to low proton conductive membranes, whereas an increase in crosslinking temperature and time would lead to high proton conductive membranes. High temperature crosslinking also resulted in an increase in anisotropy and water diffusion. Furthermore, the membranes were investigated for a Vanadium/Air Redox Flow Battery application. Membranes crosslinked at 200 °C for 30 min with a molar ratio between 2:1 (mol repeat unit:mol benzenedimethanol) showed a proton conductivity of 27.9 mS/cm and a 100 times lower VO2+ crossover compared to Nafion.

  3. Tandem Esterification/1,4-Addition-Type Friedel-Crafts Alkylation Reactions of Phenols/Naphthols with Olefinic Thioazlactones: Access to Functionalized 1,2-Dihydrobenzo[f]chromen-3-ones and 3,4-Dihydrochromen-2-ones.

    Science.gov (United States)

    Ziyaei Halimehjani, Azim; Khoshdoun, Maryam

    2016-07-01

    An efficient approach for the synthesis of novel alkyl 2,3-dihydro-3-oxo-1-aryl-1H-benzo[f]chromen-2-ylcarbamodithioates and alkyl 3,4-dihydro-2-oxo-4-aryl-2H-chromen-3-ylcarbamodithioates from 2-(alkylthio)thioazlactones (thioazlactones) and phenols or naphthols catalyzed by PTSA was developed. The reaction proceeds via a domino esterification/intramolecular 1,4-addition-type Friedel-Crafts alkylation reaction to afford interesting complex molecules by a simple procedure with high yields and diastereoselectivity. An X-ray analysis was carried out to firmly establish the stereochemistry of the products. PMID:27310869

  4. A reactivity-selectivity study of the Friedel-Crafts acetylation of 3,3′-dimethylbiphenyl and the oxidation of the acetyl derivatives

    Directory of Open Access Journals (Sweden)

    Titinchi Salam JJ

    2012-06-01

    Full Text Available Abstract Background Friedel-Crafts acetylation is an important route to aromatic ketones, in research laboratories and in industry. The acetyl derivatives of 3,3′-dimethylbiphenyl (3,3′-dmbp have applications in the field of liquid crystals and polymers and may be oxidized to the dicarboxylic acids and derivatives that are of interest in cancer treatment. Findings The effect of solvent and temperature on the selectivity of monoacetylation of 3,3’-dmbp by the Perrier addition procedure was studied using stoichiometric amounts of reagents. 4-Ac-3,3′-dmbp was formed almost quantitatively in boiling 1,2-dichloroethane and this is almost twice the yield hitherto reported. Using instead a molar ratio of substrate:AcCl:AlCl3 equal to 1:4:4 or 1:6:6 in boiling 1,2-dichloroethane, acetylation afforded 4,4′- and 4,6′-diacetyl-3,3′-dmbp in a total yield close to 100%. The acetyl derivatives were subsequently converted to the carboxylic acids by hypochlorite oxidation. The relative stabilities of the isomeric products and the corresponding σ-complexes were studied by DFT calculations and the data indicated that mono- and diacetylation followed different mechanisms. Conclusions Friedel-Crafts acetylation of 3,3′-dmbp using the Perrier addition procedure in boiling 1,2-dichloroethane was found to be superior to other recipes. The discrimination against the 6-acetyl derivative during monoacetylation seems to reflect a mechanism including an AcCl:AlCl3 complex or larger agglomerates as the electrophile, whereas the less selective diacetylations of the deactivated 4-Ac-3,3′-dmbp are suggested to include the acetyl cation as the electrophile. The DFT data also showed that complexation of intermediates and products with AlCl3 does not seem to be important in determining the mechanism.

  5. Calcium-Catalyzed, Dehydrative, Ring-Opening Cyclizations of Cyclopropyl Carbinols Derived from Donor-Acceptor Cyclopropanes.

    Science.gov (United States)

    Sandridge, Matthew J; France, Stefan

    2016-09-01

    A calcium-catalyzed, dehydrative, ring-opening cyclization of (hetero)aryl cyclopropyl carbinols is reported. The cyclopropyl carbinols are prepared directly from the corresponding donor-acceptor (D-A) cyclopropanes. The calcium catalyst catalyzes the formation of putative (hetero)aryl cyclopropyl carbinyl cations that undergo ring-opening to allylcarbinyl cations. Subsequent intramolecular Friedel-Crafts reaction affords (hetero)aryl-fused cyclohexa-1,3-dienes in up to 97% yield. This approach represents the first example of catalysis for this intramolecular, dehydrative ring-opening cyclization and outperforms the previous reports using stoichiometric Lewis acids. PMID:27517711

  6. A facile Friedel-Crafts acylation for the synthesis of polyethylenimine-grafted multi-walled carbon nanotubes as efficient gene delivery vectors.

    Science.gov (United States)

    Nia, Azadeh Hashem; Amini, Abbas; Taghavi, Sahar; Eshghi, Hossein; Abnous, Khalil; Ramezani, Mohammad

    2016-04-11

    Low chemical reactivity of carbon nanotubes is one of the major obstacles in their functionalization via chemical reactions. As a non-destructive method, Friedel-Crafts acylation was suggested among the explored reactions for which only a few methods have been reported under harsh reaction conditions, e.g., high temperature all leading to low yields. In this study, we propose a novel method for the acylation of multi-walled carbon nanotubes (MWCNTs) at a low temperature (i.e., 42°C), using SiO2-Al2O3 as a catalyst and 6-bromohexanoic acid as the acylating agent to produce high yield functionalized MWCNTs. After acylation, MWCNTs are conjugated with polyethylenimines (PEIs) with three molecular weights (1.8, 10 and 25kDa). Three different MWCNT-PEI conjugates are synthesized and evaluated for their condensation ability, viability, size and zeta potential properties. The transfection efficiency of the functionalized MWCNTs is evaluated using luciferase assay and flow cytometry in a Neuroblastoma cell line. MWCNT-PEI (10 kDa) conjugate shows the highest transfection efficacy compared to others. For this carrier transfection efficacy exceeds the amount of PEI 25 kDa at similar carrier to plasmid weight ratio (C/P) and is around 3 times higher compared to PEI 25 kDa at C/P=0.8 as positive control regarding its high transfection efficiency and low cytotoxicity. PMID:26906459

  7. Fe3+-Exchanged Titanate Nanotubes: A New Kind of Highly Active Heterogeneous Catalyst for Friedel-Crafts Type Benzylation

    Directory of Open Access Journals (Sweden)

    Yunchen Du

    2015-01-01

    Full Text Available Heterogeneous catalysis for Friedel-Crafts type benzylation has received much attention in recent years due to its characteristic of environmental benefits. In this paper, titanate nanotubes (TNTs were employed as heterogeneous catalyst support, and a new kind of Fe3+-exchanged titanate nanotubes (Fe-TNTs catalyst with highly dispersed ferric sites was constructed by an ion exchange technique. The obtained catalyst was systematically characterized by XRD, TEM, N2 adsorption, XPS, and UV-vis spectra. As expected, Fe-TNTs showed excellent catalytic activities in the benzylation of benzene and benzene derivatives. The recycling tests for Fe-TNTs were also carried out, where the reason for the gradually decreased activity was carefully investigated. Superior to some reported catalysts, the catalytic ability of used Fe-TNTs could be easily recovered by ion exchange again, indicating that Fe-TNTs herein were a highly active and durable heterogeneous catalyst for Friedel-Crafts type benzylation. These results might be helpful for the design and preparation of novel heterogeneous catalysts by combining the structural advantages of titanate nanotubes and active metal ions.

  8. Friedel-Craft Acylation of ar-Himachalene: Synthesis of Acyl-ar-Himachalene and a New Acyl-Hydroperoxide

    Directory of Open Access Journals (Sweden)

    Abdallah Karim

    2011-07-01

    Full Text Available Friedel-Craft acylation at 100 °C of 2,5,9,9-tetramethyl-6,7,8,9-tetrahydro-5H-benzocycloheptene [ar-himachalene (1], a sesquiterpenic hydrocarbon obtained by catalytic dehydrogenation of α-, β- and γ-himachalenes, produces a mixture of two compounds: (3,5,5,9-tetramethyl-6,7,8,9-tetrahydro-5H-benzocyclohepten-2-yl-ethanone (2, in 69% yield, with a conserved reactant backbone, and 3, with a different skeleton, in 21% yield. The crystal structure of 3 reveals it to be 1-(8-ethyl-8-hydroperoxy-3,5,5-trimethyl-5,6,7,8-tetrahydronaphthalen-2-yl-ethanone. In this compound O-H…O bonds form dimers. These hydrogen-bonds, in conjunction with weaker C-H…O interactions, form a more extended supramolecular arrangement in the crystal.

  9. Diaryl fluorene-Based Shape-Persistent Organic Nano molecular Frameworks via Iterative Friedel-Crafts Protocol toward Multicomponent Organic Semiconductors

    International Nuclear Information System (INIS)

    We describe bottom-up fluorenol approach to create soluble covalent organic nano molecular architectures (ONAs) as potential multicomponent organic semiconductors (MOSs). BPyFBFFA as a typical model of ONAs and MOSs exhibits a persistent chair-shaped geometric structure that consists of hole-transporting tri phenylamine (TPA), high-efficiency ter fluorene, and high-mobility pyrenes. BPyFBFFA was synthesized via the intermediates PyFA and BPyFA with iterative Friedel-Crafts reactions and Suzuki cross-coupling reactions. BPyFBFFA behaves as an efficient blue light-emitter without the low-energy green emission band. Complex diaryl fluorenes (CDAFs) are promising candidates for nano scale covalent organic frameworks and MOSs. Friedel-Crafts protocols offer versatile toolboxes for molecular architects to frame chemistry and materials, nano science, and molecular nano technology as well as molecular manufactures

  10. Werner-type Cobalt Complexes and Ruthenium Complexes with Substituted 2-Guanidinobenzimidazole Ligands as Catalysts for Michael and Friedel Crafts Reactions

    OpenAIRE

    Ganzmann, Carola

    2010-01-01

    In this thesis, chiral cobalt(III) complexes with en ligands (en = ethylenediamine) and ruthenium complexes with 2-guanidinobenzimidazole (GBI) and N-(2-benzimidazolyl)thiourea (BITU) ligands are developed. Their efficiency as catalysts for Friedel Crafts and Michael reactions are assayed. Chapter 1 provides an overview of the development of bifunctional thiourea catalysts and analyzes crystal structures of previously reported [Co(diamine)3]3+ complexes as well as GBI systems and correspondin...

  11. Synthesis of New C2- Symmetric Fluoren-9-ylidene Malonate Derived Bis(oxazoline Ligands and Their Application in Friedel-Crafts Reactions

    Directory of Open Access Journals (Sweden)

    Lei Liu

    2010-11-01

    Full Text Available A series of new C2-symmetric fluoren-9-ylidene malonate-derived bis(oxazoline ligands were synthesized from fluoren-9-ylidene malonate and enantiomerically pure amino alcohols via a convenient route. Their asymmetric catalytic properties in the Friedel-Crafts reactions of indoles with arylidene malonates were evaluated, and the Cu(OTf2 complex of a fluoren-9-ylidene malonate-derived bis(oxazoline bearing a phenyl group showed moderate to good enantioselectivity (up to 88% ee.

  12. An efficient and green synthesis of 1-indanone and 1-tetralone via intramolecular Friedel-Crafts acylation reaction

    DEFF Research Database (Denmark)

    Tran, Phuong Hoang; Huynh, Vy Hieu; Hansen, Poul Erik;

    2015-01-01

    Metal-triflate-catalyzed intramolecular Friedel–Crafts acylation of 3-arylpropanoic and 4-arylbutanoic acids in triflate-anion ionic liquids under monomodal microwave irradiation is reported. The environmentally benign synthetic procedure allows the formation of cyclic ketones in good yields with...

  13. Alkylidene malonates and α,β-unsaturated α'-hydroxyketones as practical substrates for vinylogous Friedel-Crafts alkylations in water catalysed by scandium(III) triflate/SDS

    NARCIS (Netherlands)

    Oelerich, Jens; Roelfes, Gerard

    2015-01-01

    Alkylidene malonates and α,β-unsaturated α'-hydroxyketones are demonstrated to be efficient classes of electrophiles for the scandium(III) triflate/sodium dodecyl sulphate (SDS) catalysed vinylogous Friedel-Crafts alkylation of indoles and pyrroles in water. These substrates contain an easily remova

  14. Gold-Catalyzed Direct Assembly of Aryl-Annulated Carbazoles from 2-Alkynyl Arylazides and Alkynes.

    Science.gov (United States)

    Li, Nan; Lian, Xiao-Lei; Li, Yu-Hui; Wang, Tian-Yi; Han, Zhi-Yong; Zhang, Liming; Gong, Liu-Zhu

    2016-09-01

    An unprecedented gold-catalyzed synthetic method for the direct assembly of aryl-annulated carbazoles from 2-alkynyl arylazides and alkynes is described. The reaction is proposed to proceed via a sequential cyclopropenation and intramolecular metal carbene/arene Friedel-Crafts-type reaction, respectively, mediated by two gold carbene intermediates. PMID:27529360

  15. Pd-catalyzed cascade allylic alkylation and dearomatization reactions of indoles with vinyloxirane.

    Science.gov (United States)

    Gao, Run-Duo; Xu, Qing-Long; Dai, Li-Xin; You, Shu-Li

    2016-09-14

    We have developed Pd-catalyzed intermolecular Friedel-Crafts-type allylic alkylation and allylic dearomatization reactions of substituted indoles bearing a nucleophilic group with vinyloxirane, providing an efficient method to synthesize structurally diverse tetrahydrocarboline and spiroindolenine derivatives under mild conditions. PMID:27511802

  16. Friedel-Crafts alkylations of electron-rich aromatics with 3-hydroxy-2-oxindoles: scope and limitations.

    Science.gov (United States)

    Kinthada, Lakshmana K; Ghosh, Santanu; Babu, K Naresh; Sharique, Mohd; Biswas, Soumava; Bisai, Alakesh

    2014-11-01

    A Lewis acid-catalyzed nucleophilic addition of electron rich aromatics with 3-hydroxy-2-oxindoles 5 was developed. The reaction is believed to proceed through the 2H-indol-2-one ring system 9, which eventually reacts with various electron-rich aromatics to afford a variety of 2-oxindoles with an all-carbon quaternary center at the pseudobenzylic position (4, 8, 13, and 16) in high yields. The methodology provides an expeditious route to the tetracyclic core (3) of diazonamide (1), and azonazine (2) as well as the tricyclic core of asperazine (6a), idiospermuline (6b), and calycosidine (6c) viz. C(3a)-arylpyrroloindolines 7 having an all-carbon quaternary center on further synthetic elaboration.

  17. A Large Scale Formal Synthesis of CoQ{sub 10}: Highly Stereoselective Friedel-Crafts Allylation Reaction of Tetramethoxytoluene with (E)-4-Chloro-2-methyl-1-phenylsulfonyl-2-butene in the Presence of Montmorillonite K-10

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Who; Lee, Hee Bong; Kim, Bong Chan; Sadaiah, Kadivendi; Lee, Kyuwoong; Shin, Hyunik [LG Life Sciences, Ltd., Daejeon (Korea, Republic of)

    2013-04-15

    We disclosed that MK-10 is a highly effective catalyst for the Friedel-Crafts reaction of 6 and 7 in terms of yield and of stereoselectivity. Although there are numerous applications of clays in Friedel-Crafts reaction, there is very limited example which demonstrated its effect on the stereoselectivity. In that context, our result is significant and further expansion in this direction is highly envisioned. Ubiquinone, as its name represents, exists ubiquitously in human body, particularly in the heart. It mediates the electron transfer process in mitochondria and also exerts strong antioxidant effect in its reduced form. In clinical trial, it showed beneficial effect on heart-related diseases such as myocardial infarction, angina, and other related symptoms to cause decreased mortality compared to the placebo group.

  18. Friedel-Crafts Alkylation of Arenes with 2-Halogeno-2-CF3-styrenes under Superacidic Conditions. Access to Trifluoromethylated Ethanes and Ethenes.

    Science.gov (United States)

    Sandzhieva, Maria A; Kazakova, Anna N; Boyarskaya, Irina A; Ivanov, Alexandr Yu; Nenajdenko, Valentine G; Vasilyev, Aleksander V

    2016-06-17

    The formation of the corresponding benzyl cations [ArHC(+)-CH(X)CF3] takes place under protonation of E-/Z-2-halogeno-2-CF3 styrenes [ArCH═C(X)CF3, X = F, Cl, Br] in superacids. The structures of these new electrophiles were studied by means of NMR and theoretical DFT calculations. According to these data, in the case of bromo derivatives, the formed cations, most probably, exist as cyclic bromonium ions; however, in the cases of chloro and fluoro derivatives, open forms are more preferable. Subsequent reaction of these benzyl cations with arenes proceeds as Friedel-Crafts alkylation to afford 1,1-diaryl-2-halo-3,3,3-trifluoropropanes [Ar(Ar')CH-CH(X)CF3] in high yields (up to 96%) as a mixture of two diastereomers. The prepared halogenopropanes were easily converted into the corresponding mixtures of E-/Z-trifluoromethylated diarylethenes [Ar(Ar')C═CCF3] (in yields up to 96%) by dehydrohalogenation with base (KOH or t-BuOK). The mechanism of elimination (E2 and Ecb) depends on the nature of the leaving group and reaction conditions. PMID:27227747

  19. 以氯代酰氯为试剂的聚砜膜材料的付-克酰基化反应%Friedel-Crafts Acylation Reaction of Polysulfone Membrane Material with Chloroacyl Chlorides

    Institute of Scientific and Technical Information of China (English)

    杜瑞奎; 高保娇; 李延斌; 曾庆湘

    2011-01-01

    采用氯乙酰氯和氯丁酰氯两种ω-氯代酰氯化试剂,在Lewis酸催化剂存在下,于室温下分别对聚砜(PSF)材料实施了Friedel-Crafts酰基化反应,制备了氯代酰基化(CA)聚砜材料CAPSF。用FT-IR、1H-NMR与佛尔哈德分析法表征了该产物的化学结构与组成。结果表明:在室温(25°C)下,以CH2Cl2为溶剂,以SnCl4为Lewis酸催化剂,聚砜的氯代酰基化反应可以顺利地进行,反应3 h,即可制得氯含量为0.5 mmol/g的产物;采用氯丁酰氯对PSF进行氯代酰基化反应的效果明显好于氯乙酰氯。%Friedel-Crafts acylation reactions of polysulfone(PSF) membrane material were conducted in the presence of Lewis acid catalysts at room temperature using two kinds of ω-chloroacyl chloride,chloroacetyl chloride and chlorobutyryl chloride,and chloroacylated polysulfone(CAPSF) were prepared.The chemical structure and composition of the product were characterized by FT-IR,1H-NMR and Volhard methods.The reaction processes on the chloroacylation reactions of PSF were primarily investigated.The experimental results show that the chloroacylation reaction of PSF can be carried out successfully,and a product CAPSF with a chlorine content of 0.5 mmol/g can be obtained in 3 h at room temperature(25°C) with CH2Cl2 as solvent and SnCl4 as Lewis acid catalyst.The experimental results also indicate that chlorobutyryl chloride is better than chloroacetyl chloride in the chloroacylation reactions.

  20. 分子内酰基化反应合成新型六环稠杂环化合物%Synthesis of Novel Hexacyclic -fused Heterocyclic Compounds via Intramolecular Friedel -Crafts Acylation

    Institute of Scientific and Technical Information of China (English)

    聂成铭; 徐良玉; 李阳; 高文涛

    2013-01-01

    The hitherto unreported benzo[h]naphtho[1′,2′,6,7]oxepino[3,4-b] quinolin-17(8H) -one (3a) was synthesized by the intramolecular Friedel -Crafts acylation reaction of 2 -(( naphthalen -2 -yloxy)methyl)benzo[h]quinoline -3-carboxylic acid 2 under the treatment of Eaton′s reagent (P2O5 -Me-SO3 ) .The precursor 2 was prepared through one -pot reaction of ethyl 2-( chloromethyl ) benzo [ h] quinoline-3-carboxylate 1 with α-naphthol or β-naphthol .The substrate 1 was obtained in good yield by a mild , effi-cient and direct reaction of α-naphthylamine with 4 -chloroacetoacetate under the treatment of Vilsmeier -Haack reagent.The structures of all the new compounds were identified by ESI -MS, IR, NMR spectra and Ele-mental analysis .%以2-氯甲基-3-苯并喹啉甲酸乙酯(1)为底物与α-萘酚、β-萘酚反应经“一锅法”合成了中间体2-(α-萘氧甲基)苯并[ h]喹啉-3-羧酸(2a)、2-(β-萘氧甲基)苯并[ H]喹啉-3-羧酸(2b)。化合物2a,2b在Eaton′s试剂作用下合成两种新型六环稠杂环化合物萘并[2′,1′,6,7]氧杂卓并[3,4-b]苯并喹啉-7(14H)-酮(3a)和萘并[1′,2′,6,7]氧杂卓并[3,4-b]苯并喹啉-15(8H)-酮(3b)。化合物2a,2b发生分子内傅一克酰基化闭环反应,所合成的新化合物2a、2b、3a、3b的结构经红外光谱、核磁共振谱、质谱及元素分析等得以确认。

  1. 三丁基锡/SBA-15功能配合物的合成、表征及对Friedel-Crafts反应的选择性催化%Synthesis, Characterization and Catalytic Performance Toward the Friedel-Crafts Acylation of Tributyltin Functionalized SBA-15

    Institute of Scientific and Technical Information of China (English)

    荆涛; 覃志乐; 宋伟明; 赵云鹏; 邓启刚

    2013-01-01

    将三丁基氯化锡与SBA-15介孔分子筛在N2气气氛中进行回流反应,得到有机锡无机配合物(C4H9)3Sn-O-SBA-15[Bu3SnS].利用X射线衍射(XRD)、透射电子显微镜(TEM)、氮气吸附脱附、固体核磁(NMR)和吡啶吸附脱附红外光谱分析(Py-IR)等方法对产物的组成、结构和性质进行了表征.结果表明,产物Bu3 SnS具有高度有序的六方介孔结构,与SBA-15相比,Bu3 SnS比表面积、孔容和孔径变小,酸性增强.Bu3 SnS对苯甲醚Friedel-Crafts酰基化反应具有优异的催化性能,当反应温度为130℃,n(苯甲醚)∶n(苯甲酰氯)=1.0∶2.0,w(cat) =6%(相对于苯甲醚用量),反应时间为5h,苯甲醚的转化率达到76.0%,对甲氧基二苯酮(p-MBP)选择性达到97.8%.%The organotin inorganic complexes (C4H9) 3Sn-O-SBA-15 [Bu3SnS] were successfully synthesized by grafting tributyhin on SBA-15 mesoporous molecular sieves in a nitrogen atmosphere.The composition,structure and properties of the samples were characterized by X-ray diffraction (XRD),transmittance electron microscopy(TEM),Hammett indicator method,N2 adsorption-desorption,solid nuclear magnetic resonance (NMR),in-situ pyridine infrared spectroscopy(Py-IR) and so on.The results show that the hexagonal P6mm mesostructure of parent siliceous SBA-15 is maintained in Bu3SnS.The surface areas,proe size and volume of Bu3 SnS are all deceased with the increase of acidity,compared to those of SBA-15.Friedel-Crafts acylation of anisole and benzoyl chloride can be efficiently catalyzed in the presence of Bu3 SnS.The reaction conversion of anisole and the selectivity ofp-benzoylanisole are 76.0% and 97.8%,respectively,when the molar ratio of anisole to benzoyl chloride is 0.5∶ 1.0,the amount of catalyst is 6%,the reaction temperature is 130 ℃ and the reaction time is 5 h.

  2. Efficient One-Pot Synthesis of Indol-3-yl-Glycines via Uncatalyzed Friedel-Crafts Reaction in Water

    Directory of Open Access Journals (Sweden)

    Mehdi Ghandi

    2009-03-01

    Full Text Available The three component reaction of primary aliphatic amines, glyoxalic acid and indole or N-methylindole in water at ambient temperature affords indol-3-yl or N-methylindol-3-yl-glycine in almost quantitative yields.

  3. Indium triflate in 1-isobutyl-3-methylimidazolium dihydrogenphosphate: an efficient and green catalytic system for Friedel-Crafts acylation

    DEFF Research Database (Denmark)

    Tran, Phuong Hoang; Hoang, Huy Manh; Chau, Duy-Khiem Nguyen;

    2015-01-01

    Indium triflate in the ionic liquid, 1-isobutyl-3-methylimidazolium dihydrogen phosphate ([i-BMIM]H2PO4), was found to show enhanced catalytic activity in the Friedel–Crafts acylation of various aromatic compounds with acid anhydrides. The catalytic system was easily recovered and reused without ...

  4. Ga doped SBA-15 as an active and stable catalyst for Friedel-Crafts liquid-phase acylation

    OpenAIRE

    EL BERRICHI, Zohra; CHERIF, Leila; ORSEN O.; TESSONIER, Jean-Philippe; VANHAECKE, Estelle; LOUIS, Benoit; LEDOUX, Marc-Jacques; Pham-Huu, Cuong

    2013-01-01

    Gallium containing SBA-15 mesoporous materials with different Si/Ga ratio were synthesized using a post-treatment procedure with an aqueous solution of Ga(NO3)3. The materials were characterised by means of elemental analysis, BET, XRD, TEM and H/D isotope exchange techniques. It appears that stable Ga-species were anchored to the siliceous matrix of SBA-15, thus generating acid properties in their host material. The catalytic activity of Ga-SBA-15 materials has been evaluated in the FriedelC...

  5. Intramolecular Acylation of Aryl- and Aroyl-Aliphatic Acids by the Action of Pyrophosphoryl Chloride and Phosphorus Oxychloride

    Directory of Open Access Journals (Sweden)

    Saleh Rayyan

    2001-03-01

    Full Text Available Both pyrophosphoryl chloride and phosphorus oxychloride react with aryl aliphatic acids to form mixed anhydrides which undergo intramolecular acylation to afford cyclic ketones without the addition of a Friedel-Crafts catalyst. Aryl and aroylbenzoic acids could be cyclized to the corresponding anthrones and anthraquinones respectively.

  6. Iron(III)-Catalyzed Arylation of Spiro-Epoxyoxindoles with Phenols/Naphthols towards the Synthesis of Spirocyclic Oxindoles.

    Science.gov (United States)

    Luo, Mupeng; Yuan, Rongju; Liu, Xuesong; Yu, Linqian; Wei, Wanguo

    2016-07-01

    An efficient and highly regioselective iron(III)-catalyzed Friedel-Crafts-type arylation of spiro-epoxyoxindoles with phenols was developed for rapid access to 3-(3-indolyl)-oxindole-3-methanols, which could be further elaborated into benzofuranyl-spirooxindoles under Mitsunobu conditions. When spiro-epoxyoxindoles were reacted with naphthols in the presence of a catalytic amount of FeCl3 ⋅6 H2 O in dichloromethane, they underwent a tandem Friedel-Crafts-type arylation and O-cyclization to yield novel naphthofuranyl-spirooxindoles in excellent yields. This method is applied to enable the efficient and highly regioselective synthesis of a small-molecule inhibitor of the sodium channel Nav 1.7 (±)-XEN402, which is currently in a phase IIb clinical trial for the treatment of pain. PMID:27244669

  7. Synthesis of 2,2'-Dipyrryl Ketones from Pyrrole-2-carboxylic Acids with Trifluoroacetic Anhydride

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Se Hee; Lim, Jin Woo; Yu, Jin; Kim, Jae Nyoung [Chonnam National Univ., Gwangju (Korea, Republic of)

    2013-09-15

    An efficient synthesis of 2,2'-dipyrryl ketones has been carried out from pyrrole-2-carboxylic acids using trifluoroacetic anhydride (TFAA). Simultaneous generation of both mixed anhydride and 2-unsubstituted pyrrole, via facile decarboxylation with in-situ generated TFA, made their cross reaction (intermolecular Friedel-Crafts acylation) possible and efficient.

  8. Highly Chemo- and Regioselective Reaction of Hydroxybenzenes in Acidic Ionic Liquid

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Hui; Zhuang, Yu Wei; Cao, Jian; Zhang, Guo Bao [High New Technology Research Center of Henan Academy of Sciences, Zhengzhou (China)

    2013-09-15

    Highly chemo- and regioselective reaction of hydroxybenzenes with α,β-unsaturated compounds in acidic ionic liquid l-butyl-3-methylimidazolium hydrogen sulphate ([BMIM]HSO{sub 4}) was reported for the first time. A series of oxa-Michael adducts and Friedel-Crafts alkylated products were synthesized with good yields. The acidic ionic liquid could be easily recycled for at least 5 times with only minor loss in activity.

  9. Phenylalanine Ammonia-Lyase-Catalyzed Deamination of an Acyclic Amino Acid: Enzyme Mechanistic Studies Aided by a Novel Microreactor Filled with Magnetic Nanoparticles.

    Science.gov (United States)

    Weiser, Diána; Bencze, László Csaba; Bánóczi, Gergely; Ender, Ferenc; Kiss, Róbert; Kókai, Eszter; Szilágyi, András; Vértessy, Beáta G; Farkas, Ödön; Paizs, Csaba; Poppe, László

    2015-11-01

    Phenylalanine ammonia-lyase (PAL), found in many organisms, catalyzes the deamination of l-phenylalanine (Phe) to (E)-cinnamate by the aid of its MIO prosthetic group. By using PAL immobilized on magnetic nanoparticles and fixed in a microfluidic reactor with an in-line UV detector, we demonstrated that PAL can catalyze ammonia elimination from the acyclic propargylglycine (PG) to yield (E)-pent-2-ene-4-ynoate. This highlights new opportunities to extend MIO enzymes towards acyclic substrates. As PG is acyclic, its deamination cannot involve a Friedel-Crafts-type attack at an aromatic ring. The reversibility of the PAL reaction, demonstrated by the ammonia addition to (E)-pent-2-ene-4-ynoate yielding enantiopure l-PG, contradicts the proposed highly exothermic single-step mechanism. Computations with the QM/MM models of the N-MIO intermediates from L-PG and L-Phe in PAL show similar arrangements within the active site, thus supporting a mechanism via the N-MIO intermediate.

  10. Phenylalanine Ammonia-Lyase-Catalyzed Deamination of an Acyclic Amino Acid: Enzyme Mechanistic Studies Aided by a Novel Microreactor Filled with Magnetic Nanoparticles.

    Science.gov (United States)

    Weiser, Diána; Bencze, László Csaba; Bánóczi, Gergely; Ender, Ferenc; Kiss, Róbert; Kókai, Eszter; Szilágyi, András; Vértessy, Beáta G; Farkas, Ödön; Paizs, Csaba; Poppe, László

    2015-11-01

    Phenylalanine ammonia-lyase (PAL), found in many organisms, catalyzes the deamination of l-phenylalanine (Phe) to (E)-cinnamate by the aid of its MIO prosthetic group. By using PAL immobilized on magnetic nanoparticles and fixed in a microfluidic reactor with an in-line UV detector, we demonstrated that PAL can catalyze ammonia elimination from the acyclic propargylglycine (PG) to yield (E)-pent-2-ene-4-ynoate. This highlights new opportunities to extend MIO enzymes towards acyclic substrates. As PG is acyclic, its deamination cannot involve a Friedel-Crafts-type attack at an aromatic ring. The reversibility of the PAL reaction, demonstrated by the ammonia addition to (E)-pent-2-ene-4-ynoate yielding enantiopure l-PG, contradicts the proposed highly exothermic single-step mechanism. Computations with the QM/MM models of the N-MIO intermediates from L-PG and L-Phe in PAL show similar arrangements within the active site, thus supporting a mechanism via the N-MIO intermediate. PMID:26345352

  11. Ferrocenyl-derived electrophilic phosphonium cations (EPCs) as Lewis acid catalysts.

    Science.gov (United States)

    Mallov, Ian; Stephan, Douglas W

    2016-04-01

    Oxidation of diphenylphosphinoferrocene and 1,1'-bis(diphenylphosphino)ferrocene with XeF2, resulted in the formation of CpFe(η(5)-C5H4PF2Ph2) 1 and Fe(η(5)-C5H4PF2Ph2)22 respectively. Subsequent reactions with [SiEt3][B(C6F5)4] yielded [CpFe(η(5)-C5H4PFPh2)][B(C6F5)4] 3 and [Fe(η(5)-C5H4PFPh2)2] [B(C6F5)4]24. PhP(η(5)-C5H4)2Fe 5 was prepared, converted to [PhMeP(η(5)-C5H4)2Fe][O3SCF3] 6 and then to [PhMeP(η(5)-C5H4)2Fe][B(C6F5)4] 7. The ability of the salts 3, 4 and 7 to catalyze Friedel-Crafts dimerization of 1,1-diphenylethylene, dehydrocoupling of phenol and triethylsilane, deoxygenation of acetophenone and hydrodefluorination of 1-fluoropentane were probed. While compound 7 proved to be ineffective, compounds 3 and 4 were useful Lewis acid catalysts. Compounds 3 and 4 were shown to catalyze the deoxygenation of a series of ketones. PMID:26911641

  12. Antisolvent Precipitation for the Synthesis of Monodisperse Mesoporous Niobium Oxide Spheres as Highly Effective Solid Acid Catalysts

    KAUST Repository

    Li, Cheng Chao

    2012-03-20

    We have developed a low-cost reaction protocol to synthesize mesoporous Nb 2O 5-based solid acid catalysts with external shape control. In the synthesis, monodisperse glycolated niobium oxide spheres (GNOS) were prepared by means of a simple antisolvent precipitation approach and subsequently converted to mesoporous niobium oxide spheres (MNOS) with a large surface area of 312m 2g -1 by means of the hydrothermal treatment. The antisolvent acetone used to obtain GNOS was recovered through distillation at high purity. The obtained mesoporous MNOS were functionalized further with sulfate anions at different temperatures or incorporated with tungstophosphoric acid to obtain recyclable solid acid catalysts. These MNOS-based catalysts showed excellent performance in a wide range of acid-catalyzed reactions, such as Friedel-Crafts alkylation, esterification, and hydrolysis of acetates. As they are monodisperse spheres with diameters in the submicrometer range, the catalysts can be easily separated and reused. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Lipase catalyzed synthesis of epoxy-fatty acids

    Institute of Scientific and Technical Information of China (English)

    CHEN, Qian; LI, Zu-Yi

    2000-01-01

    Lipase catalyzed synthesis of epoxy-fatty acidas from unsaturated carboxylic acids was investigated.Under mild conditions unsaturated arboxylic acids were convcveed to peroxide,then the unsaturated peroxycarboxylic acids epoxidised the C=C bond of themselves

  14. 全氟辛基磺酸稀土金属盐催化氟两相Friedel-Crafts烷基化反应%Friedel-Crafts Alkylation in Fluorous Biphasic System Catalyzed by Rare Earth(Ⅲ) Perfluorooctanesulfonates

    Institute of Scientific and Technical Information of China (English)

    易文斌; 蔡春

    2006-01-01

    制备了全氟辛基磺酸稀土金属盐[RE(OSO2C8C17)3,RE:Sc,Y,La~Lu],并研究了将其作为催化剂催化氟两相烷基化反应. 全氟己烷(C6F14)、全氟甲苯(C7F8)、全氟甲基环己烷(C7F14)、全氟辛烷(C8F18)、1-溴代全氟辛烷(C8F17Br)和全氟萘烷(C10F18,顺式与反式的混合物)可作为该反应的氟溶剂. 考察了带有不同配体的稀土金属催化剂对反应的影响. 研究表明,Yb(OSO2C8F17)3和C10F18分别是最好的氟代催化剂和氟溶剂. 以Yb(OSO2C8F17)3为催化剂在C10F18中苯甲醚和苯甲醇的烷基化反应得率为96%. 含有催化剂的氟相通过简单的相分离,可回收利用. 氟相重复使用5次,其催化活性降低不大.

  15. Friedel-Crafts Acylation in Fluorous Biphasic Systems Catalyzed by Rare Earth( Ⅲ ) Perfluorooctanesulfonates%全氟辛基磺酸稀土金属盐催化氟两相Friedel-Crafts酰化反应

    Institute of Scientific and Technical Information of China (English)

    易文斌; 蔡春

    2005-01-01

    制备了全氟辛基磺酸稀土金属盐(RE(OSO2C8F17)3,RE=Y,La~Lu),研究了该催化剂作用下氟两相Friedel-Crafts酰化反应.全氟己烷(C6F14)、全氟甲苯(C7F8)、全氟甲基环己烷(C7F14)、全氟辛烷(C8F18)、1-溴代全氟辛烷(C8F17Br)和全氟萘烷(C10F18,顺式与反式的混合物)可作为该反应的氟溶剂.考察了氟相和有机相的相比与酰化试剂种类对反应的影响.结果表明,反应具有强对位选择性酰化能力;Y(OSO2C8F17)3和C10F18分别是最好的催化剂和氟溶剂,以Y(OSO2C8F17)3为催化剂在C10F18中苯甲醚和乙酸酐的Friedel-Crafts酰化反应得率为56%,对位选择性超过99%;随着氟相和有机相相比的减小,产率升高,对位选择性降低;含有催化剂的氟相通过简单的相分离,就可回收利用,氟相重复使用5次,其催化活性减少不大.

  16. The Iron-Catalyzed Oxidation of Hydrazine by Nitric Acid

    Energy Technology Data Exchange (ETDEWEB)

    Karraker, D.G.

    2001-07-17

    To assess the importance of iron to hydrazine stability, the study of hydrazine oxidation by nitric acid has been extended to investigate the iron-catalyzed oxidation. This report describes those results.

  17. New Alkylation Route of Benzene with Ethylene Catalyzed by [bmim]Cl/FeCl3 Ionic Liquid%[bmim]Cl/FeCl3离子液体催化苯与乙烯烷基化反应的新型机理

    Institute of Scientific and Technical Information of China (English)

    孙学文; 赵锁奇; 王仁安

    2004-01-01

    Up to now the mechanism of Friedel-Crafts reactions catalyzed by ionic liquid have not been fully understood, while carbocation mechanism was assumed. It was found that the source of H+ and the route of reaction initiated the alkylation of benzene with ethylene catalyzed by [bmim]Cl/FeCl3 ionic liquid. The fact that dewatered ionic liquids have catalytic activity for the alkylation of benzene with ethylene suggests that there exists a new catalytic route. The distinctly Bronsted acid properties of 2-H in [bmim]Cl were found through FT-IR and HNMR analysis of [bmim]Cl after titration with water free KOH in alcohol solution. In addition, the chemical shifts of proton on the [bmim]Cl ring, especially 2-H, are sensitive to the change of FeCl3 content and shifted downfield when FeCl3 was added into [bmim]Cl to form ionic liquid. Thus 2-H was easy to be disengaged from imidazolium ring with formation of H+ to initiate the reaction. The isotope-substituted method was employed to prove this mechanism, through the GC-MS analysis of alkylation products of deuterated benzene with ethylene. The route of alkylation catalyzed by FeCl3 ionic liquid was found to follow the carbocation mechanism, the resource of H+ was presented and proved using HNMR analysis of ionic liquid to inspect the intensity change of 2-H. It was found that the intensity of 2-H reduced 23% after reaction showing that the H+ arising from alkylation reaction was supplied by 2-H on the imidazole ring.

  18. Palladium-Catalyzed alpha-Arylation of Tetramic Acids

    DEFF Research Database (Denmark)

    Storgaard, Morten; Dorwald, F. Z.; Peschke, B.;

    2009-01-01

    A mild, racemization-free, palladium-Catalyzed alpha-arylation of tetramic acids (2,4-pyrrolidinediones) has been developed. Various amino acid-derived tetramic acids were cleanly arylated by treatment with 2 mol % of Pd(OAc)(2), 4 mol % of a sterically demanding biaryl phosphine, 2.3 equiv of K2...

  19. Kinetic study on the acid-catalyzed hydrolysis of cellulose to levulinic acid

    NARCIS (Netherlands)

    Girisuta, B.; Janssen, L. P. B. M.; Heeres, H. J.

    2007-01-01

    A variety of interesting bulk chemicals is accessible by the acid-catalyzed hydrolysis of cellulose. An interesting example is levulinic acid, a versatile precursor for fuel additives, polymers, and resins. A detailed kinetic study on the acid-catalyzed hydrolysis of cellulose to levulinic acid is r

  20. Amino Acids Catalyzed Direct Aldol Reactions in Aqueous Micelles

    Institute of Scientific and Technical Information of China (English)

    PENG Yi-Yuan; WANG Qi; DING Qiu-Ping; HE Jia-Qi; CHENG Jin-Pei

    2003-01-01

    @@ Since the discovery of its roles as a good small-organic-molecule catalyst in intramolecular aldol reactions, pro line has drawn considerable attention in synthetic chemistry due to its similarity to the type-Ⅰ aldolases. Recently,List and others have reported some new direct asymmetric intermolecular reactions catalyzed by proline, including aldol, Mannich, Michael, and other analogous reactions. Except for two recent examples, [1,2] proline catalyzed aldol reactions in aqueous micelles have not been reported, nor have other amino acids as organocatalysts in directly catalyzing aldol reaction been reported. Herein we wish to present our recent results regarding environmentally be nign direct aldol reactions catalyzed by amino acids including proline, histidine and arginine in aqueous media.

  1. Polyphosphorous acid catalyzed cyclization in the synthesis of cryptolepine derivatives

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    11-Oxo-10,11-dihydroxy-5H-indolo[3,2,b]quinoline7-carboxylic acid was obtained specifically by polyphosphorous acid catalyzed cyclization with optimal reaction conditions. Biological assays showed that it potentially inhibits the proteasomal chymotrypsin-like activity in vitro and suppresses breast cancer cell growth.

  2. Rh-Catalyzed arylation of fluorinated ketones with arylboronic acids.

    Science.gov (United States)

    Dobson, Luca S; Pattison, Graham

    2016-09-25

    The Rh-catalyzed arylation of fluorinated ketones with boronic acids is reported. This efficient process allows access to fluorinated alcohols in high yields under mild conditions. Competition experiments suggest that difluoromethyl ketones are more reactive than trifluoromethyl ketones in this process, despite their decreased electronic activation, an effect we postulate to be steric in origin.

  3. A SIMPLE, EFFICIENT AND SOLVENT FREE ONE POT SYNTHESIS OF 3, 3 DIHETEROAROMATIC OXINDOLE

    Directory of Open Access Journals (Sweden)

    Syed Shahed Ali

    2013-04-01

    Full Text Available Formic acid catalyzed, single step and environmentally friendly process for synthesis of 3, 3- diheteroaromatic oxindole derivatives is described. This adopted protocol for Friedel- Crafts substitution reaction has the advantage of reusability of the catalyst, high yields and ease of separation of pure products.

  4. Lipase-Catalyzed Modification of Canola Oil with Caprylic Acid

    DEFF Research Database (Denmark)

    Wang, Yingyao; Luan, Xia; Xu, Xuebing;

    Lipase-catalyzed acidolysis of canola oil with caprylic acid was performed to produce structured lipids. Six commercial lipases from different sources were screened for their ability to incorporate the caprylic acid into the canola oil. The positional distribution of FA on the glycerol backbone...... parameters studied included substrate mole ratio, enzyme load, reaction time and temperature. Incorporation of caprylic acid was higher when reactions were carried with 10% lipase of the total weight of substrates at a mole ratio of oil to caprylic acid of 1:4. The optimal time course and temperature...

  5. Acid-catalyzed kinetics of indium tin oxide etching

    International Nuclear Information System (INIS)

    We report the kinetic characterization of indium tin oxide (ITO) film etching by chemical treatment in acidic and basic electrolytes. It was observed that film etching increased under more acidic conditions, whereas basic conditions led to minimal etching on the time scale of the experiments. Quartz crystal microbalance was employed in order to track the reaction kinetics as a function of the concentration of hydrochloric acid and accordingly solution pH. Contact angle measurements and atomic force microscopy experiments determined that acid treatment increases surface hydrophilicity and porosity. X-ray photoelectron spectroscopy experiments identified that film etching is primarily caused by dissolution of indium species. A kinetic model was developed to explain the acid-catalyzed dissolution of ITO surfaces, and showed a logarithmic relationship between the rate of dissolution and the concentration of undisassociated hydrochloric acid molecules. Taken together, the findings presented in this work verify the acid-catalyzed kinetics of ITO film dissolution by chemical treatment, and support that the corresponding chemical reactions should be accounted for in ITO film processing applications. - Highlights: • Acidic conditions promoted indium tin oxide (ITO) film etching via dissolution. • Logarithm of the dissolution rate depended linearly on the solution pH. • Acid treatment increased ITO surface hydrophilicity and porosity. • ITO film etching led to preferential dissolution of indium species over tin species

  6. Acid-catalyzed oxygen-18 labeling of peptides.

    Science.gov (United States)

    Niles, Richard; Witkowska, H Ewa; Allen, Simon; Hall, Steven C; Fisher, Susan J; Hardt, Markus

    2009-04-01

    In enzymatic (18)O-labeling strategies for quantitative proteomics, the exchange of carboxyl oxygens at low pH is a common, undesired side reaction. We asked if acid-catalyzed back exchange could interfere with quantitation and whether the reaction itself could be used as method for introducing (18)O label into peptides. Several synthetic peptides were dissolved in dilute acid containing 50% (v/v) H(2)(18)O and incubated at room temperature. Aliquots were removed over a period of 3 weeks and analyzed by tandem mass spectrometry (MS/MS). (18)O-incorporation ratios were determined by linear regression analysis that allowed for multiple stable-isotope incorporations. At low pH, peptides exchanged their carboxyl oxygen atoms with the aqueous solvent. The isotope patterns gradually shifted to higher masses until they reached the expected binomial distribution at equilibrium after approximately 11 days. Reaction rates were residue- and sequence-specific. Due to its slow nature, the acid-catalyzed back exchange is expected to minimally interfere with enzymatic (18)O-labeling studies provided that storage and analysis conditions minimize low-pH exposure times. On its own, acid-catalyzed (18)O labeling is a general tagging strategy that is an alternative to the chemical, metabolic, and enzymatic isotope-labeling schemes currently used in quantitative proteomics. PMID:19243188

  7. 1-, 2-, and 4-Ethynylpyrenes in the Structure of Twisted Intercalating Nucleic Acids: Structure, Thermal Stability, and Fluorescence Relationship

    DEFF Research Database (Denmark)

    Filichev, Vyacheslav V; Astakhova, Irina V.; Malakhov, Andrei D.;

    2008-01-01

    A postsynthetic, on-column Sonogashira reaction was applied on DNA molecules modified by 2- or 4-iodophenylmethylglycerol in the middle of the sequence, to give the corresponding ortho- and para-twisted intercalating nucleic acids (TINA) with 1-, 2-, and 4-ethynylpyrene residues. The convenient...... synthesis of 2- and 4-ethynylpyrenes started from the hydrogenolysis of pyrene that has had the sulfur removed and separation of 4,5,9,10-tetrahydropyrene and 1,2,3,6,7,8-hexahydropyrene, which were later converted to the final compounds by successive Friedel-Crafts acetylation, aromatization by 2...

  8. Synthesis of Rosin Acid Starch Catalyzed by Lipase

    OpenAIRE

    Rihui Lin; He Li; Han Long; Jiating Su; Wenqin Huang

    2014-01-01

    Rosin, an abundant raw material from pine trees, was used as a starting material directly for the synthesis of rosin acid starch. The esterification reaction was catalyzed by lipase (Novozym 435) under mild conditions. Based on single factor experimentation, the optimal esterification conditions were obtained as follows: rosin acid/anhydrous glucose unit in the molar ratio 2 : 1, reaction time 4 h at 45°C, and 15% of lipase dosage. The degree of substitution (DS) reaches 0.098. Product from e...

  9. Synthesis of Rosin Acid Starch Catalyzed by Lipase

    Directory of Open Access Journals (Sweden)

    Rihui Lin

    2014-01-01

    Full Text Available Rosin, an abundant raw material from pine trees, was used as a starting material directly for the synthesis of rosin acid starch. The esterification reaction was catalyzed by lipase (Novozym 435 under mild conditions. Based on single factor experimentation, the optimal esterification conditions were obtained as follows: rosin acid/anhydrous glucose unit in the molar ratio 2 : 1, reaction time 4 h at 45°C, and 15% of lipase dosage. The degree of substitution (DS reaches 0.098. Product from esterification of cassava starch with rosin acid was confirmed by FTIR spectroscopy and iodine coloration analysis. Scanning electron microscopy and X-ray diffraction analysis showed that the morphology and crystallinity of the cassava starch were largely destroyed. Thermogravimetric analysis indicated that thermal stability of rosin acid starch decreased compared with native starch.

  10. Direct amidation of amino acid derivatives catalyzed by arylboronic acids : applications in dipeptide synthesis.

    OpenAIRE

    Liu, S.; Yang, Y.; Liu, X.; Ferdousi, F. K.; Batsanov, A.S.; Whiting, A

    2013-01-01

    The direct amidation of amino acid derivatives catalyzed by arylboronic acids has been examined. The reaction was generally slow relative to simple amine-carboxylic acid combinations though proceeded at 65–68 °C generally avoiding racemization. 3,4,5-Trifluorophenylboronic and o-nitrophenylboronic acids were found to be the best catalysts, though for slower dipeptide formations, high catalyst loadings were required and an interesting synergistic catalytic effect between two arylboronic acids ...

  11. Solid acid catalyzed biodiesel production from waste cooking oil

    Energy Technology Data Exchange (ETDEWEB)

    Jacobson, Kathlene; Gopinath, Rajesh; Meher, Lekha Charan; Dalai, Ajay Kumar [Catalysis and Chemical Reaction Engineering Laboratories, Department of Chemical Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK, S7N 5A9 (Canada)

    2008-12-17

    Various solid acid catalysts were evaluated for the production of biodiesel from low quality oil such as waste cooking oil (WCO) containing 15 wt.% free fatty acids. The zinc stearate immobilized on silica gel (ZS/Si) was the most effective catalyst in simultaneously catalyzing the transesterification of triglycerides and esterification of free fatty acid (FFA) present in WCO to methyl esters. The optimization of reaction parameters with the most active ZS/Si catalyst showed that at 200 C, 1:18 oil to alcohol molar ratio and 3 wt.% catalysts loading, a maximum ester yield of 98 wt.% could be obtained. The catalysts were recycled and reused many times without any loss in activity. (author)

  12. MOLYBDENUM CATALYZED ACID PEROXIDE BLEACHING OF EUCALYPTUS KRAFT PULP

    OpenAIRE

    Marcos S. Rabelo; Jorge L. Colodette; Vera M. Sacon; Marcelo R. Silva; Marco A. B. Azevedo

    2008-01-01

    Molybdenum catalyzed peroxide bleaching (PMo Stage) consists of pulp treatment with hydrogen peroxide under acidic conditions in the presence of a molybdenum catalyst. Molybdenum is applied in catalytic doses (50-200 mg/kg pulp) and may originate from various sources, including (NH4)6Mo7O24.4H2O, Na2MoO4.2H2O, siliconmolybdate, etc. This work is aimed at optimizing the PMo stage and evaluating its industrial application in the OAZDP sequence. Optimum PMo stage conditions for bleaching eucalyp...

  13. An Efficient Procedure for Esterification of Aryloxyacetic Acid and Arylthioacetic Acid Catalyzed by Silica Sulfuric Acid

    Institute of Scientific and Technical Information of China (English)

    LI,Hong-Ya; LI,Ji-Tai; LI,Hui-Zhang

    2004-01-01

    @@ Aryloxyacetate and arylthioacetate are wildly used in herbicides, plant regulator and insecticides. Recently, Wille et al. have reported that methyl aryloxyacetate is an efficient agent to prevent and treat allergic contact dermatitis.[1] The most popular synthesis is by heating sodium phenoxide (mercaptide) with ethyl chloroacetate in DMF,[2] or by the esterification of acid with alcohol using concentrated H2SO4 as catalyst.[3] In this paper, synthesis of aryloxyacetate and aryl thioacetate from aryloxyacetic acid and arylthioacetic acid respectively in ether catalyzed by silica sulfuric acid in 83%~94% yields is described. The catalyst is reused for 3 times without significant loss of activity (Entry 4). Compared with common procedures, the present procedure possesses the advantages of the operational simplicity, short reaction time,less-corrosion, high yield and reusable catalyst.

  14. Acid base catalyzed transesterification kinetics of waste cooking oil

    Energy Technology Data Exchange (ETDEWEB)

    Jain, Siddharth; Sharma, M.P.; Rajvanshi, Shalini [Alternate Hydro Energy Centre, Indian Institute of Technology, Roorkee (India)

    2011-01-15

    The present study reports the results of kinetics study of acid base catalyzed two step transesterification process of waste cooking oil, carried out at pre-determined optimum temperature of 65 C and 50 C for esterification and transesterification process respectively under the optimum condition of methanol to oil ratio of 3:7 (v/v), catalyst concentration 1%(w/w) for H{sub 2}SO{sub 4} and NaOH and 400 rpm of stirring. The optimum temperature was determined based on the yield of ME at different temperature. Simply, the optimum concentration of H{sub 2}SO{sub 4} and NaOH was determined with respect to ME Yield. The results indicated that both esterification and transesterification reaction are of first order rate reaction with reaction rate constant of 0.0031 min{sup -1} and 0.0078 min{sup -1} respectively showing that the former is a slower process than the later. The maximum yield of 21.50% of ME during esterification and 90.6% from transesterification of pretreated WCO has been obtained. This is the first study of its kind which deals with simplified kinetics of two step acid-base catalyzed transesterification process carried under the above optimum conditions and took about 6 h for complete conversion of TG to ME with least amount of activation energy. Also various parameters related to experiments are optimized with respect to ME yield. (author)

  15. Acid-Catalyzed Preparation of Biodiesel from Waste Vegetable Oil: An Experiment for the Undergraduate Organic Chemistry Laboratory

    Science.gov (United States)

    Bladt, Don; Murray, Steve; Gitch, Brittany; Trout, Haylee; Liberko, Charles

    2011-01-01

    This undergraduate organic laboratory exercise involves the sulfuric acid-catalyzed conversion of waste vegetable oil into biodiesel. The acid-catalyzed method, although inherently slower than the base-catalyzed methods, does not suffer from the loss of product or the creation of emulsion producing soap that plagues the base-catalyzed methods when…

  16. MOLYBDENUM CATALYZED ACID PEROXIDE BLEACHING OF EUCALYPTUS KRAFT PULP

    Directory of Open Access Journals (Sweden)

    Marcos S. Rabelo

    2008-08-01

    Full Text Available Molybdenum catalyzed peroxide bleaching (PMo Stage consists of pulp treatment with hydrogen peroxide under acidic conditions in the presence of a molybdenum catalyst. Molybdenum is applied in catalytic doses (50-200 mg/kg pulp and may originate from various sources, including (NH46Mo7O24.4H2O, Na2MoO4.2H2O, siliconmolybdate, etc. This work is aimed at optimizing the PMo stage and evaluating its industrial application in the OAZDP sequence. Optimum PMo stage conditions for bleaching eucalyptus pulp were 90 ºC, pH 3.5, 2 h, 0.1 kg/adt Mo and 5 kg/adt H2O2. The PMo stage was more efficient to remove pulp hexenuronic acids than lignin. Its efficiency decreased with increasing pH in the range of 1.5-5.5, while it increased with increasing temperature and peroxide and molybdenum doses. The application of the PMo stage as replacement for the A-stage of the AZDP sequence significantly decreased chlorine dioxide demand. The PMo stage caused a decrease of 20-30% in the generation of organically bound chlorine. The quality parameters of the pulp produced during the PMo stage mill trial were comparable to those obtained with the reference A-stage.

  17. A novel polar-modified post-cross-linked resin and its enhanced adsorption to salicylic acid: Equilibrium, kinetics and breakthrough studies.

    Science.gov (United States)

    Wang, Xiaomei; Li, Guoqiang; Guo, Deping; Zhang, Yaling; Huang, Jianhan

    2016-05-15

    Improving the surface polarity is of significance for the post-cross-linked resins to enhance their adsorption to polar aromatic compounds. In the present study, we prepared a novel polar-modified post-cross-linked PDEpc_D by the Friedel-Crafts alkylation reaction and the amination reaction, the Brunauer-Emmett-Teller (BET) surface area and pore volume increased significantly after the Friedel-Crafts alkylation reaction and the surface polarity improved greatly after the amination reaction. Batch adsorption showed that PDEpc_D possessed a much enhanced adsorption to salicylic acid as compared the precursors PDE and PDEpc as well as the non-polar post-cross-linked PDVBpc. The equilibrium data was characterized by the Freundlich model, π-π stacking, hydrogen bonding and static interaction were the possible driving forces. The adsorption was a fast process and the kinetic data obeyed the micropore diffusion model. Column adsorption-desorption experiments suggested that PDEpc_D was a potential candidate for adsorptive removal of salicylic acid from aqueous solution. PMID:26928058

  18. Chiral Brønsted Acids for Asymmetric Organocatalysis

    Science.gov (United States)

    Kampen, Daniela; Reisinger, Corinna M.; List, Benjamin

    Chiral Brønsted acid catalysis is an emerging area of organocatalysis. Since the pioneering studies of the groups of Akiyama and Terada in 2004 on the use of chiral BINOL phosphates as powerful Brønsted acid catalysts in asymmetric Mannich-type reactions, numerous catalytic asymmetric transformations involving imine activation have been realized by means of this catalyst class, including among others Friedel-Crafts, Pictet-Spengler, Strecker, cycloaddition reactions, transfer hydrogenations, and reductive aminations. More recently, chiral BINOL phosphates found application in multicomponent and cascade reactions as for example in an asymmetric version of the Biginelli reaction. With the introduction of chiral BINOL-derived N-triflyl phosphoramides in 2006, asymmetric Brønsted acid catalysis is no longer restricted to reactive substrates. Also certain carbonyl compounds can be activated through these stronger Brønsted acid catalysts. In dealing with sensitive substrate classes, chiral dicarboxylic acids proved of particular value.

  19. Biodiesel Production from Spent Fish Frying Oil Through Acid-Base Catalyzed Transesterification

    OpenAIRE

    Abdalrahman B. Fadhil; Mohammed M. Dheyab; Kareem M. Ahmed; Marwa H. Yahya

    2012-01-01

    Biodiesel fuels were prepared from a special type of frying oil namely spent fish frying oil through two step transesterification viz. acid-base catalyzed transesterification. Hydrochloric acid and potassium hydroxide with methanol were used for this purpose. The oil was pre-treated with (1.0 wt% HCl) and methanol to reduce free fatty acids content of the oil. Then, conditions of the base catalyzed step such as base concentration, reaction temperature, methanol to oil molar ratio and reaction...

  20. Acid-catalyzed reactions of hexanal on sulfuric acid particles: Identification of reaction products

    Science.gov (United States)

    Garland, Rebecca M.; Elrod, Matthew J.; Kincaid, Kristi; Beaver, Melinda R.; Jimenez, Jose L.; Tolbert, Margaret A.

    While it is well established that organics compose a large fraction of the atmospheric aerosol mass, the mechanisms through which organics are incorporated into atmospheric aerosols are not well understood. Acid-catalyzed reactions of compounds with carbonyl groups have recently been suggested as important pathways for transfer of volatile organics into acidic aerosols. In the present study, we use the aerodyne aerosol mass spectrometer (AMS) to probe the uptake of gas-phase hexanal into ammonium sulfate and sulfuric acid aerosols. While both deliquesced and dry non-acidic ammonium sulfate aerosols showed no organic uptake, the acidic aerosols took up substantial amounts of organic material when exposed to hexanal vapor. Further, we used 1H-NMR, Fourier transform infrared (FTIR) spectroscopy and GC-MS to identify the products of the acid-catalyzed reaction of hexanal in acidic aerosols. Both aldol condensation and hemiacetal products were identified, with the dominant reaction products dependent upon the initial acid concentration of the aerosol. The aldol condensation product was formed only at initial concentrations of 75-96 wt% sulfuric acid in water. The hemiacetal was produced at all sulfuric acid concentrations studied, 30-96 wt% sulfuric acid in water. Aerosols up to 88.4 wt% organic/11.1 wt% H 2SO 4/0.5 wt% water were produced via these two dimerization reaction pathways. The UV-VIS spectrum of the isolated aldol condensation product, 2-butyl 2-octenal, extends into the visible region, suggesting these reactions may impact aerosol optical properties as well as aerosol composition. In contrast to previous suggestions, no polymerization of hexanal or its products was observed at any sulfuric acid concentration studied, from 30 to 96 wt% in water.

  1. Integrated Production of Xylonic Acid and Bioethanol from Acid-Catalyzed Steam-Exploded Corn Stover.

    Science.gov (United States)

    Zhu, Junjun; Rong, Yayun; Yang, Jinlong; Zhou, Xin; Xu, Yong; Zhang, Lingling; Chen, Jiahui; Yong, Qiang; Yu, Shiyuan

    2015-07-01

    High-efficiency xylose utilization is one of the restrictive factors of bioethanol industrialization. However, xylonic acid (XA) as a new bio-based platform chemical can be produced by oxidation of xylose with microbial. So, an applicable technology of XA bioconversion was integrated into the process of bioethanol production. After corn stover was pretreated with acid-catalyzed steam-explosion, solid and liquid fractions were obtained. The liquid fraction, also named as acid-catalyzed steam-exploded corn stover (ASC) prehydrolyzate (mainly containing xylose), was catalyzed with Gluconobacter oxydans NL71 to prepare XA. After 72 h of bioconversion of concentrated ASC prehydrolyzate (containing 55.0 g/L of xylose), the XA concentration reached a peak value of 54.97 g/L, the sugar utilization ratio and XA yield were 94.08 and 95.45 %, respectively. The solid fraction was hydrolyzed to produce glucose with cellulase and then fermented with Saccharomyces cerevisiae NL22 to produce ethanol. After 18 h of fermentation of concentrated enzymatic hydrolyzate (containing 86.22 g/L of glucose), the ethanol concentration reached its highest value of 41.48 g/L, the sugar utilization ratio and ethanol yield were 98.72 and 95.25 %, respectively. The mass balance showed that 1 t ethanol and 1.3 t XA were produced from 7.8 t oven dry corn stover.

  2. Research Progress in the Asymmetric Reaction Catalyzed by Chiral BINOL Phosphoric Acids%BINOL衍生的手性磷酸催化的不对称反应研究进展

    Institute of Scientific and Technical Information of China (English)

    郭海明; 李建国; 王东超; 渠桂荣

    2009-01-01

    综述了近年来BINOL衍生的手性磷酸作为一类强酸性Brφnsted酸催化剂,在不对称氢转移反应、Friedel-Crafts, Mannich, Aza Diels-Alder, Aza-ene-type, Pictet-Spengler等反应中的研究进展.参考文献37篇.

  3. The different roles of a cationic gold(i) complex in catalysing hydroarylation of alkynes and alkenes with a heterocycle.

    Science.gov (United States)

    Mehrabi, Tahmineh; Ariafard, Alireza

    2016-08-01

    The mechanism of twofold hydroarylation of terminal alkynes with pyrrole catalyzed by a cationic gold(i) complex was investigated using DFT. It was found that while both the hydroarylation reactions proceed via a Friedel-Crafts-type mechanism, the first hydroarylation is directly promoted by gold(i) but the second hydroarylation by a proton released through interaction of the alkene product with gold-bound acidic organic species such as acetic acid and terminal alkynes. PMID:27377712

  4. Solid Acid-Catalyzed Cellulose Hydrolysis Monitored by In Situ ATR-IR Spectroscopy

    NARCIS (Netherlands)

    Zakzeski, J.; Grisel, R.J.H.; Smit, A.T.; Weckhuysen, B.M.

    2012-01-01

    The solid acid-catalyzed hydrolysis of cellulose was studied under elevated temperatures and autogenous pressures using in situ ATR-IR spectroscopy. Standards of cellulose and pure reaction products, which include glucose, fructose, hydroxymethylfurfural (HMF), levulinic acid (LA), formic acid, and

  5. Selective and recyclable depolymerization of cellulose to levulinic acid catalyzed by acidic ionic liquid.

    Science.gov (United States)

    Ren, Huifang; Girisuta, Buana; Zhou, Yonggui; Liu, Li

    2015-03-01

    Cellulose depolymerization to levulinic acid (LA) was catalyzed by acidic ionic liquids (ILs) selectively and recyclably under hydrothermal conditions. The effects of reaction temperature, time, water amount and cellulose intake were investigated. Dilution effect becomes more pronounced at lower cellulose intake, dramatically improving the yield of LA to 86.1%. A kinetic model has been developed based on experimental data, whereby a good fit was obtained and kinetic parameters were derived. The relationships between IL structure, polymeric structure and depolymerization efficiency were established, shedding light on the in-depth catalytic mechanism of IL, inclusive of acidity and hydrogen bonding ability. The LA product can be readily separated through extraction by methyl isobutyl ketone (MIBK) and IL can be reused over five cycles without loss of activity. This environmentally friendly methodology can be applied to selective production of LA from versatile biomass feedstocks, including cellulose and derivatives, glucose, fructose and HMF.

  6. Organocatalytic Asymmetric Synthesis of Dihydrobenzoxazinones Bearing Trifluoromethylated Quaternary Stereocenters.

    Science.gov (United States)

    Lou, Hengqiao; Wang, Yongtao; Jin, Enze; Lin, Xufeng

    2016-03-01

    Chiral phosphoric acid-catalyzed enantioselective aza-Friedel-Crafts reaction of trifluoromethyl benzoxazinones with pyrroles is reported. Under mild conditions, a range of enantioenriched dihydrobenzoxazinones bearing trifluoromethylated quaternary stereocenters could be obtained in good to excellent yield and ee. A remarkable fluorine effect is observed, and preliminary mechanistic studies combined with theory calculations suggest that triple-hydrogen-bonding interactions hold the transition structure rigidly and allow the bulky substituents of the catalyst to influence the enantioselectivity. PMID:26882280

  7. An unprecedented benzannulation of oxindoles with enalcarbenoids: a regioselective approach to functionalized carbazoles.

    Science.gov (United States)

    Rathore, Kuldeep Singh; Lad, Bapurao Sudam; Chennamsetti, Haribabu; Katukojvala, Sreenivas

    2016-04-30

    A novel Rh(ii)/Brønsted acid catalyzed tandem benzannulation of oxindoles with enaldiazo carbonyls led to the formation of valuable 1-hydroxy-2-acylcarbazoles. This reaction is proposed to involve a formal insertion of a rhodium enalcarbenoid into an oxindole sp(2) C-O bond, an oxa-Michael addition, Friedel-Crafts reaction and a semipinacol type 1,2-carbonyl migration. PMID:26992045

  8. Degradation of acid red 14 by silver ion-catalyzed peroxydisulfate oxidation in an aqueous solution

    OpenAIRE

    RASOULIFARD, Mohammad Hossein; MOHAMMADI, Seied Mohammad Mahdi DOUST

    2012-01-01

    Silver ion (Ag1+)-catalyzed peroxydisulfate was studied for the degradation of acid red 14 (AR-14) in an aqueous medium. The effect of different parameters, such as temperature, peroxydisulfate concentration, and dye and Ag1+ concentrations, were investigated. Application of Ag1+-catalyzed peroxydisulfate, as an advanced oxidation process, introduces an effectual method for wastewater treatment. An accelerated reaction using S2O82- to destroy dyes can be achieved via chemical activat...

  9. Brønsted Acid-Catalyzed Direct Substitution of 2-Ethoxytetrahydrofuran with Trifluoroborate Salts

    Directory of Open Access Journals (Sweden)

    Kayla M. Fisher

    2016-06-01

    Full Text Available Metal-free transformations of organotrifluoroborates are advantageous since they avoid the use of frequently expensive and sensitive transition metals. Lewis acid-catalyzed reactions involving potassium trifluoroborate salts have emerged as an alternative to metal-catalyzed protocols. However, the drawbacks to these methods are that they rely on the generation of unstable boron dihalide species, thereby resulting in low functional group tolerance. Recently, we discovered that in the presence of a Brønsted acid, trifluoroborate salts react rapidly with in situ generated oxocarbenium ions. Here, we report Brønsted acid-catalyzed direct substitution of 2-ethoxytetrahydrofuran using potassium trifluoroborate salts. The reaction occurs when tetrafluoroboric acid is used as a catalyst to afford functionalized furans in moderate to excellent yields. A variety of alkenyl- and alkynyltrifluoroborate salts readily participate in this transformation.

  10. Synthesis of Tetrahydrofuran and Tetrahydropyran Derivatives Catalyzed by Tungstophosphoric Acid in Ionic Liquid

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Synthesis of tetrahydrofuran and tetrahydropyran derivatives catalyzed by tungstophosphoric acid (H3PW12O4o) were conveniently performed with high yield from the corresponding unsaturated alcohols in ionic liquid. Sufuric acid (H2SO4), trifluoromathanesulfonic acid (TfOH)and p-toluenesulfonic acid (TsOH) were also explored for preparing these products in ionic liquid.The catalysts and ionic liquid can be easily recovered and reused.

  11. GSTP1-1 stereospecifically catalyzes glutathione conjugation of ethacrynic acid

    NARCIS (Netherlands)

    Iersel, M.L.P.S. van; Lipzig, M.M.H. van; Rietjens, I.M.C.M.; Vervoort, J.; Bladeren, P.J. van

    1998-01-01

    Using 1H NMR two diastereoisomers of the ethacrynic acid glutathione conjugate (EASG) as well as ethacrynic acid (EA) could be distinguished and quantified individually. Chemically prepared EASG consists of equal amounts of both diastereoisomers. GSTP1-1 stereospecifically catalyzes formation of one

  12. Fe-Catalyzed Oxidative Cleavage of Unsaturated Fatty Acids

    OpenAIRE

    Spannring, P.

    2013-01-01

    The oxidative cleavage of unsaturated fatty acids into aldehydes or carboxylic acids gives access to valuable products. The products can be used as chemical building blocks, as emulsifiers or in the paint or polymer industry. Ozonolysis is applied industrially to cleave the fatty acid oleic acid into the aldehydes nonanal and 9-oxo-nonanoic acid or into pelargonic and azelaic acid. Considerable hazards, including explosion risks, are associated with the use of ozone, and alternative processes...

  13. Fe-Catalyzed Oxidative Cleavage of Unsaturated Fatty Acids

    NARCIS (Netherlands)

    Spannring, P.

    2013-01-01

    The oxidative cleavage of unsaturated fatty acids into aldehydes or carboxylic acids gives access to valuable products. The products can be used as chemical building blocks, as emulsifiers or in the paint or polymer industry. Ozonolysis is applied industrially to cleave the fatty acid oleic acid int

  14. Manganese-Mediated C-H Alkylation of Unbiased Arenes Using Alkylboronic Acids.

    Science.gov (United States)

    Castro, Susana; Fernández, Juan J; Fañanás, Francisco J; Vicente, Rubén; Rodríguez, Félix

    2016-06-27

    The alkylation of arenes is an essential synthetic step of interest not only from the academic point of view but also in the bulk chemical industry. Despite its limitations, the Friedel-Crafts reaction is still the method of choice for most of the arene alkylation processes. Thus, the development of new strategies to synthesize alkyl arenes is a highly desirable goal, and herein, we present an alternative method to those conventional reactions. Particularly, a simple protocol for the direct C-H alkylation of unbiased arenes with alkylboronic acids in the presence of Mn(OAc)3 ⋅2H2 O is reported. Primary or secondary unactivated alkylboronic acids served as alkylating agents for the direct functionalization of representative polyaromatic hydrocarbons (PAHs) or benzene. The results are consistent with a free-radical mechanism. PMID:27124250

  15. 5-Position-selective C-H trifluoromethylation of 8-aminoquinoline derivatives.

    Science.gov (United States)

    Kuninobu, Yoichiro; Nishi, Mitsumi; Kanai, Motomu

    2016-09-14

    We developed a copper-catalyzed 5-position-selective C-H trifluoromethylation of 8-aminoquinoline derivatives. The reaction proceeded with high functional group tolerance under mild conditions. In the case of quinolines with an amide, carbamate, urea, or sulfonamide group at the 8-position of quinoline moieties, a radical scavenger experiment indicated that the reaction proceeded via a radical pathway. The protecting group of an 8-amidoquinoline derivative could be removed by hydrolysis. On the other hand, the trifluoromethylation of 8-aminoquinolines was also promoted by other Lewis acids as well as a copper catalyst and proceeded even in the presence of a radical scavenger. These results indicated that the trifluoromethylation of 8-aminoquinolines proceeded via a Friedel-Crafts-type reaction. Interestingly, the copper salt works as either a catalyst for the formation of a CF3 radical or a Lewis acid to promote a Friedel-Crafts-type reaction, depending on the substrate. PMID:27506919

  16. Kinetics of Ethyl Acetate Synthesis Catalyzed by Acidic Resins

    Science.gov (United States)

    Antunes, Bruno M.; Cardoso, Simao P.; Silva, Carlos M.; Portugal, Ines

    2011-01-01

    A low-cost experiment to carry out the second-order reversible reaction of acetic acid esterification with ethanol to produce ethyl acetate is presented to illustrate concepts of kinetics and reactor modeling. The reaction is performed in a batch reactor, and the acetic acid concentration is measured by acid-base titration versus time. The…

  17. Modification of oligo-Ricinoleic Acid and Its Derivatives with 10-Undecenoic Acid via Lipase-Catalyzed Esterification

    Directory of Open Access Journals (Sweden)

    M. Claudia Montiel

    2012-04-01

    Full Text Available Lipases were employed under solvent-free conditions to conjugate oligo-ricinoleic acid derivatives with 10-undecenoic acid, to incorporate a reactive terminal double bond into the resultant product. First, undecenoic acid was covalently attached to oligo-ricinoleic acid using immobilized Candida antarctica lipase (CAL at a 30% yield. Thirty percent conversion also occurred for CAL-catalyzed esterification between undecenoic acid and biocatalytically-prepared polyglycerol polyricinoleate (PGPR, with attachment of undecenoic acid occurring primarily at free hydroxyls of the polyglycerol moiety. The synthesis of oligo-ricinoleyl-, undecenoyl- structured triacylglycerols comprised two steps. The first step, the 1,3-selective lipase-catalyzed interesterification of castor oil with undecenoic acid, occurred successfully. The second step, the CAL-catalyzed reaction between ricinoleyl-, undecenoyl structured TAG and ricinoleic acid, yielded approximately 10% of the desired structured triacylglycerols (TAG; however, a significant portion of the ricinoleic acid underwent self-polymerization as a side-reaction. The employment of gel permeation chromatography, normal phase HPLC, NMR, and acid value measurements was effective for characterizing the reaction pathways and products that formed.

  18. Enantioselective BINOL-phosphoric acid catalyzed Pictet-Spengler reactions of N-benzyltryptamine

    NARCIS (Netherlands)

    N.V. Sewgobind; M.J. Wanner; S. Ingemann; R. de Gelder; J.H. van Maarseveen; H. Hiemstra

    2008-01-01

    Optically active tetrahydro-beta-carbolines were synthesized via an (R)-BINOL-phosphoric acid-catalyzed asynunetric Pictet-Spengler reaction of N-benzyltryptamine with a series of aromatic and aliphatic aldehydes. The tetrahydro-beta-carbolines were obtained in yields ranging from 77% to 97% and wit

  19. Iron-Catalyzed Acylation of Polyfunctionalized Aryl- and Benzylzinc Halides with Acid Chlorides.

    Science.gov (United States)

    Benischke, Andreas D; Leroux, Marcel; Knoll, Irina; Knochel, Paul

    2016-08-01

    FeCl2 (5 mol %) catalyzes a smooth and convenient acylation of functionalized arylzinc halides at 50 °C (2-4 h) and benzylic zinc chlorides at 25 °C (0.5-4 h) with a variety of acid chlorides leading to polyfunctionalized diaryl and aryl heteroaryl ketones. PMID:27457108

  20. Palladium-catalyzed homo-coupling of boronic acids with supported reagents in supercritical carbon dioxide

    Institute of Scientific and Technical Information of China (English)

    Lei Zhou; Qiu Xiang Xu; Huan Feng Jiang

    2007-01-01

    Palladium-catalyzed homo-coupling of arylboronic acids could proceed smoothly with a commercially available resin functionlised by phosphino or amino group as the ligand in supercritical carbon dioxide thereby offering a simple and efficient protocol for the synthesis of symmetrical bi-aryl molecules and their higher homologues.

  1. Monitoring the Hydrolysis of Olive Oil Catalyzed by Lipase via Acid Value Detection

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Hydrolysis of olive oil catalyzed by Candida lipolytica lipase was investigated. The relative concentration of the components in the product was determined by using high performance liquid chromatography(HPLC). Furthermore, a novel rapid method to detect the hydrolytic process of olive oil was developed based on the relationship between the acid value and the relative concentration of the different components.

  2. Furfural production from fruit shells by acid-catalyzed hydrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Demirbas, A. [Selcuk Univ., Konya (Turkey). Dept. of Chemical Engineering

    2006-01-21

    Pentosans are hydrolyzed to pentoses by dilute mineral acid hydrolysis. The main source of pentosans is hemicelluloses. Furfural can be produced by the acid hydrolysis of pentosan from fruit shells such as hazelnut, sunflower, walnut, and almond of agricultural wastes. Further dehydration reactions of the pentoses yield furfural. The hydrolysis of each shell sample was carried out in dilute sulfuric acid (0.05 to 0.200 mol/l), at high temperature (450-525 K), and short reaction times (from 30 to 600 s). (author)

  3. Palladium-Catalyzed C–C Bond Formations via Activation of Carboxylic Acids and Their Derivatives

    OpenAIRE

    Song, Bingrui

    2013-01-01

    Applications of carboxylic acids and their derivatives in transition metal-catalyzed cross-coupling reactions regio-selectively forming Csp3-Csp2, and Csp2-Csp2 bonds were explored in this thesis. Several important organic building blocks such as aryl acetates, diaryl acetates, imines, ketones, biaryls, styrenes and polysubstituted alkenes were successfully accessed from carboxylic acids and their derivatives by the means of C–H activation and decarboxylative cross-couplings. An efficient ...

  4. On the Brønsted acid-catalyzed homogeneous hydrolysis of furans.

    Science.gov (United States)

    Nikbin, Nima; Caratzoulas, Stavros; Vlachos, Dionisios G

    2013-11-01

    Furan affairs: Electronic structure calculations of the homogeneous Brønsted acid-catalyzed hydrolysis of 2,5-dimethylfuran show that proton transfer to the β-position is rate-limiting and provides support that the hydrolysis follows general acid catalysis. By means of projected Fukui indices, we show this to be the case for unsubstituted, 2-, and 2,5-substituted furans with electron-donating groups.

  5. Copper-catalyzed intermolecular oxyamination of olefins using carboxylic acids and O-benzoylhydroxylamines

    Directory of Open Access Journals (Sweden)

    Brett N. Hemric

    2016-01-01

    Full Text Available This paper reports a novel approach for the direct and facile synthesis of 1,2-oxyamino moieties via an intermolecular copper-catalyzed oxyamination of olefins. This strategy utilizes O-benzoylhydroxylamines as an electrophilic amine source and carboxylic acids as a nucleophilic oxygen source to achieve a modular difunctionalization of olefins. The reaction proceeded in a regioselective manner with moderate to good yields, exhibiting a broad scope of carboxylic acid, amine, and olefin substrates.

  6. Tandem Aldol Condensation – Platinacycle-Catalyzed Addition Reactions of Aldehydes, Methyl Ketones and Arylboronic Acids

    OpenAIRE

    Liao, Yuan-Xi; Hu, Qiao-Sheng

    2012-01-01

    Tandem aldol condensation of aldehydes with methyl ketones followed by anionic four-electron donor-based (Type I) platinacycle-catalyzed addition reactions of arylboronic acids to form β-arylated ketones is described. Good to excellent yields of β-arylated ketones were obtained for the tandem reactions of aromatic/aliphatic aldehydes, methyl ketones and arylboronic acids, and moderate yields were observed for the tandem reaction with α, β-unsaturated aldehydes as the aldehyde source.

  7. Cu2+-Catalyzed Oscillatory Oxidation of Ascorbic Acid by O2 Flow

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A novel heterogeneous oscillator, the Cu2+-catalyzed oscillatory oxidation of ascorbic acid (Vitamin C) in aqueous solution by O2 flow was reported. Both the potential oscillations on Pt-electrode corresponding to [Cu2+] and the absorbance oscillations at l=260 nm corresponding to [ascorbic acid] were observed. Oscillations in the completely homogeneous system were also observed. Effects of several factors on the oscillations were investigated.

  8. Investigation of emulsified, acid and acid-alkali catalyzed mesoporous bioactive glass microspheres for bone regeneration and drug delivery

    International Nuclear Information System (INIS)

    Acid-catalyzed mesoporous bioactive glass microspheres (MBGMs-A) and acid-alkali co-catalyzed mesoporous bioactive glass microspheres (MBGMs-B) were successfully synthesized via combination of sol-gel and water-in-oil (W/O) micro-emulsion methods. The structural, morphological and textural properties of mesoporous bioactive glass microspheres (MBGMs) were characterized by various techniques. Results show that both MBGMs-A and MBGMs-B exhibit regularly spherical shape but with different internal porous structures, i.e., a dense microstructure for MBGMs-A and internally porous structure for MBGMs-B. 29Si NMR data reveal that MGBMs have low polymerization degree of silica network. The in vitro bioactivity tests indicate that the apatite formation rate of MBGMs-B was faster than that of MBGMs-A after soaking in simulated body fluid (SBF) solution. Furthermore, the two kinds of MBGMs have similar storage capacity of alendronate (AL), and the release behaviors of AL could be controlled due to their unique porous structure. In conclusion, the microspheres are shown to be promising candidates as bone-related drug carriers and filling materials of composite scaffold for bone repair. - Graphical abstract: The morphologies and microstructures of acid-catalyzed mesoporous bioactive glass microspheres (MBGMs-A) and acid-alkali co-catalyzed mesoporous bioactive glass microspheres (MBGMs-B) were observed by scanning electron microscope and transmission electron microscope. MBGMs-A exhibits a dense structure and a porous can be observed in MBGMs-B. The microspheres have a quick inducing-apatite formation ability and show a sustained release of alendronate (AL). Highlights: • A rapid method was reported to prepare mesoporous bioactive glass microspheres. • The addition of ammonia significantly shortens the preparation time. • Acid and acid-alkali co-catalyzed microspheres were studied for the first time. • The materials exhibited excellent in vitro bioactivity and drug

  9. 磷钨酸原位改性HMS催化苯甲醚乙酰化反应%Catalytic Synthesis of p-Methoxy Acetophenone with Modification Catalyst HMS by Phosphotungstic Acid

    Institute of Scientific and Technical Information of China (English)

    周晓; 张亚洲; 王伟; 刘向东; 陈平

    2013-01-01

    The modification solid catalyst HMS by phosphotungstic acid was prepared by in-situ synthesis from DDA,TEOS,and phosphotungstic acid,and applied in p-Methoxy acetophenone production with the Friedel-Crafts acylation reaction of phenyl methyl ether and Acetic anhydride.The factors including reaction temperature,reaction time,catalyst amount,reactants molar ratio phenyl methyl ether to Acetic anhydride on the Friedel-Crafts acylation reaction were investigated.The experimental effects show that solid acid catalyst HMS has high catalytic activity.The acylation reaction conversion can reach 83.1% and the selectivity of p-Methoxy acetophenone production is 97.3% under the following optimal conditions:reaction temperature of 100 ℃,reaction time of 4 h,amount catalyst of 0.15 g,molar ratio of n(anisole) ∶ n(acetic anhydride) =1 ∶1.5.%以正十二胺(DDA)为模板剂、正硅酸四乙酯(TEOS)为硅源、磷钨酸(HPW)为活性组分,经原位合成法制备了HPW改性的介孔材料HMS(HPW-HMS),并以此催化剂催化苯甲醚与乙酸酐发生傅-克(Friedel-Crafts)酰基化反应合成对甲氧基苯乙酮,对催化剂进行了XRD和IR表征,研究了催化剂制备方法、脱除模板剂的方式以及催化反应条件,考察反应温度、反应时间、催化剂质量、反应物的物质的量等对苯甲醚转化率和主产物对甲氧基苯乙酮选择性的影响.实验结果表明,固体催化剂HPW-HMS在此反应中具有较高的催化活性,当反应温度100℃,反应时间4h,催化剂质量0.15g,原料物质的量比n(苯甲醚)∶n(乙酸酐)=1∶1.5时,苯甲醚转化率达到83.1%,对甲氧基苯乙酮选择性达97.3%.

  10. Synthesis of pteroylglutamic acid-3',5'-2H2 by trifluoroacetic acid catalyzed exchange with deuterium oxide

    International Nuclear Information System (INIS)

    Pteroylglutamic acid (PGA) was deuterated by trifluoroacetic acid catalyzed exchange with deuterium oxide. The product, pteroylglutamic acid-3',5'-2H2, was specifically deuterated in the aromatic protons of the p-aminobenzoyl (PABA) moiety; the protons on C7 and C9 and in the glutamic acid residue were not exchanged. Deuterium incorporation was measured by chemical ionization mass spectrometry (CI-MS). Pteroylglutamates were cleaved by a base-catalyzed, oxidative hydrolysis to PABA, which was converted to the methyl ester, N-trifluoroacetate for analysis by gas chromatography-chemical ionization-mass spectrometry. Products from the exchange typically contained 1 percent 2H1 and 90 percent 2H2 species. The procedure may be used to label specifically various analogs of PGA with deuterium in the PABA portion of the molecule

  11. Dy(OTf)3 Catalyzed Reaction of Indole with Aldehydes and Ketones in Ionic Liquids

    Institute of Scientific and Technical Information of China (English)

    MI Xue-Ling; LUO San-Zhong; HE Jia-Qi; CHENG Jin-Pei

    2003-01-01

    @@ The use of environmentally benign reaction media is very important in view of today' s environmentally con scious attitude. In connect with this, room temperature ionic liquids that are air and moisture stable have received a good deal of attention in recent years as novel solvent systems for organic synthesis. A number of reactions such as Friedel-Crafts reactions, Diels-Alder cycloadditions, hydrogenations, and Heck reactions have employed ionic liquids as solvents. Among them, the Friedel-Crafts reaction[1] is of great synthetic significance in view of laboratory synthesis and industrial production. Recent studies showed that Friedel-Crafts reaction of indole with carbonyl compounds proceeded readily in aqueous media. [2] However, the aqueous reactions suffer from some common problems,such as tedious work-up, reuse of catalyst and so on.

  12. Choline Chloride Catalyzed Amidation of Fatty Acid Ester to Monoethanolamide: A Green Approach.

    Science.gov (United States)

    Patil, Pramod; Pratap, Amit

    2016-01-01

    Choline chloride catalyzed efficient method for amidation of fatty acid methyl ester to monoethanolamide respectively. This is a solvent free, ecofriendly, 100% chemo selective and economically viable path for alkanolamide synthesis. The Kinetics of amidation of methyl ester were studied and found to be first order with respect to the concentration of ethanolamine. The activation energy (Ea) for the amidation of lauric acid methyl ester catalyzed by choline chloride was found to be 50.20 KJ mol(-1). The 98% conversion of lauric acid monoethanolamide was obtained at 110°C in 1 h with 6% weight of catalyst and 1:1.5 molar ratio of methyl ester to ethanolamine under nitrogen atmosphere. PMID:26666271

  13. Heteropoly acid catalyzed hydrolysis of glycogen to glucose

    International Nuclear Information System (INIS)

    Complete conversion of glycogen to glucose is achieved by using H3PW12O40·nH2O (HPW) and H4SiW12O40·nH2O (HSiW) as catalysts for the hydrolysis under optimized hydrothermal conditions (mass fraction of catalyst 2.4%, 373 K and 2 h reaction time). The reusability of the catalyst (HPW) was demonstrated. In addition to carrying out the glycogen hydrolysis in an autoclave, other novel methods such as microwave irradiation and sonication have also been investigated. At higher mass fraction of the heteropoly acids (10.5%), glycogen could be completely converted to glucose under microwave irradiation. Sonication of an aqueous solution of glycogen in the presence of HPW and HSiW also yielded glucose. Thus, heteropoly acids are efficient, environmentally friendly and reusable catalysts for the conversion of glycogen to glucose. - Highlights: • Hydrothermal, microwave and sonication based methods of hydrolysis. • Heteropoly acids are green catalysts for glycogen hydrolysis. • Glycogen from cyanobacteria is demonstrated as a potential feedstock for glucose

  14. Development of Fluorous Lewis Acid-Catalyzed Reactions

    Directory of Open Access Journals (Sweden)

    Joji Nishikido

    2006-08-01

    Full Text Available Organic synthetic methodology in the 21st century aims to conform to the principles of green sustainable chemistry (GSC and we may expect that in the future, the realization of GSC will be an important objective for chemical industries. An important aim of synthetic organic chemistry is to implement waste-free and environmentally-benign industrial processes using Lewis acids as versatile as aluminum choride. A key technological objective of our work in this area has been to achieve a “catalyst recycling system that utilizes the high activity and structural features of fluorous Lewis acid catalysts”. Thus, we have developed a series of novel fluorous Lewis acid catalysts, namely the ytterbium(III, scandium(III, tin(IV or hafnium(IV bis(perfluoroalkanesulfonylamides or tris(perfluoro- alkanesulfonylmethides. Our catalysts are recyclable and effective for acylations of alcohols and aromatics, Baeyer-Villiger reactions, direct esterifications and transesterifications in a fluorous biphasic system (FBS, in supercritical carbon dioxide and on fluorous silica gel supports.

  15. Palladium-Catalyzed α-Arylation of Aryl Acetic Acid Derivatives via Dienolate Intermediates with Aryl Chlorides and Bromides

    OpenAIRE

    Sha, Sheng-Chun; Zhang, Jiadi; Walsh, Patrick J.

    2015-01-01

    To date, examples of α-arylation of carboxylic acids remain scarce. Using a deprotonative cross-coupling process (DCCP), a method for palladium-catalyzed γ-arylation of aryl acetic acids with aryl halides has been developed. This protocol is applicable to a wide range of aryl bromides and chlorides. A procedure for the palladium-catalyzed α-arylation of styryl acetic acids is also described.

  16. Development of Fluorous Lewis Acid-Catalyzed Reactions

    OpenAIRE

    Joji Nishikido; Osamu Yamazaki; Xiuhua Hao; Akihiro Yoshida

    2006-01-01

    Organic synthetic methodology in the 21st century aims to conform to the principles of green sustainable chemistry (GSC) and we may expect that in the future, the realization of GSC will be an important objective for chemical industries. An important aim of synthetic organic chemistry is to implement waste-free and environmentally-benign industrial processes using Lewis acids as versatile as aluminum choride. A key technological objective of our work in this area has been to achieve a “c...

  17. Kinetics of acid-catalyzed aldol condensation reactions of aliphatic aldehydes

    Science.gov (United States)

    Casale, Mia T.; Richman, Aviva R.; Elrod, Matthew J.; Garland, Rebecca M.; Beaver, Melinda R.; Tolbert, Margaret A.

    Field observations of atmospheric aerosols have established that organic compounds compose a large fraction of the atmospheric aerosol mass. However, the physical/chemical pathway by which organic compounds are incorporated into atmospheric aerosols remains unclear. The potential role of acid-catalyzed reactions of organic compounds on acidic aerosols has been explored as a possible chemical pathway for the incorporation of organic material into aerosols. In the present study, ultraviolet-visible (UV-vis) spectroscopy was used to monitor the kinetics of formation of the products of the acid-catalyzed aldol condensation reaction of a range of aliphatic aldehydes (C 2-C 8). The experiments were carried out at various sulfuric acid concentrations and a range of temperatures in order to estimate the rate constants of such reactions on sulfuric acid aerosols under tropospheric conditions. The rate constants were generally found to decrease as the chain length of the aliphatic aldehyde increased (except for acetaldehyde, which had an unusually small rate constant), increase as a function of sulfuric acid concentration as predicted by excess acidity theory, and showed normal Arrhenius behavior as a function of temperature. While the kinetic data are generally consistent with previous laboratory reports of aldehyde reactivity in various sulfuric acid media, the aldol condensation reactions involving aliphatic aldehydes do not appear fast enough to be responsible for significant transfer of organic material into atmospheric aerosols.

  18. Kinetics of the Esterification Reaction between Pentanoic Acid and Methanol Catalyzed by Noncorrosive Cation Exchange Resin

    OpenAIRE

    Sharma, M.; Toor, A. P.; R. K. Wanchoo

    2014-01-01

    Methyl pentanoate, commonly known as methyl valerate, is the methyl ester of pentanoic acid (valeric acid) with a fruity odour. Methyl pentanoate is commonly used in fragrances, beauty care, soap, laundry detergents at levels of 0.1 – 1 %. In its very pure form (purity 99.5 %) it is used as a plasticizer in the manufacture of plastics. In the present investigation, kinetics of esterification of pentanoic acid with methanol catalyzed by heterogeneous catalyst in a batch-type reactor is reporte...

  19. Acid-Catalyzed Oxygen-18 Labeling of Peptides for Proteomics Applications

    OpenAIRE

    Niles, Richard; Witkowska, H. Ewa; Allen, Simon; Hall, Steven C.; Fisher, Susan J.; Hardt, Markus

    2009-01-01

    In enzymatic 18O-labeling strategies for quantitative proteomics, the exchange of carboxyl oxygens at low pH is a common, undesired side reaction. We asked if acid-catalyzed back exchange could interfere with quantitation and whether the reaction itself could be used as an alternative method for introducing 18O label into peptides. Several synthetic amino acid sequences were dissolved in dilute acid containing 50% (v/v) H218O and incubated at room temperature. Aliquots were removed over a per...

  20. Nickel-Catalyzed Cross-Coupling of Redox-Active Esters with Boronic Acids.

    Science.gov (United States)

    Wang, Jie; Qin, Tian; Chen, Tie-Gen; Wimmer, Laurin; Edwards, Jacob T; Cornella, Josep; Vokits, Benjamin; Shaw, Scott A; Baran, Phil S

    2016-08-01

    A transformation analogous in simplicity and functional group tolerance to the venerable Suzuki cross-coupling between alkyl-carboxylic acids and boronic acids is described. This Ni-catalyzed reaction relies upon the activation of alkyl carboxylic acids as their redox-active ester derivatives, specifically N-hydroxy-tetrachlorophthalimide (TCNHPI), and proceeds in a practical and scalable fashion. The inexpensive nature of the reaction components (NiCl2 ⋅6 H2 O-$9.5 mol(-1) , Et3 N) coupled to the virtually unlimited commercial catalog of available starting materials bodes well for its rapid adoption. PMID:27380912

  1. Organosolv liquefaction of sugarcane bagasse catalyzed by acidic ionic liquids.

    Science.gov (United States)

    Chen, Zhengjian; Long, Jinxing

    2016-08-01

    An efficient and eco-friendly process is proposed for sugarcane bagasse liquefaction under mild condition using IL catalyst and environmental friendly solvent of ethanol/H2O. The relationship between IL acidic strength and its catalytic performance is investigated. The effects of reaction condition parameters such as catalyst dosage, temperature, time and solvent are also intensively studied. The results show that ethanol/H2O has a significant promotion effect on the simultaneous liquefaction of sugarcane bagasse carbohydrate and lignin. 97.5% of the bagasse can be liquefied with 66.46% of volatile product yield at 200°C for 30min. Furthermore, the IL catalyst shows good recyclability where no significant loss of the catalytic activity is exhibited even after five runs. PMID:27115746

  2. CLAY CATALYZED SYNTHESIS OF BIO-DEGRADABLE POLY(GLYCOLIC ACID)

    Institute of Scientific and Technical Information of China (English)

    K. Durai Murugan; S. Radhika; I. Baskaran; R. Anbarasan

    2008-01-01

    Glycolic acid was polymerized under vacuum in the presence and absence of nano sized clay. The added clay catalyzed the condensation polymerization which can be confirmed by recording FT1R spectroscopy and intrinsic viscosity (Ⅳ) values. The relative intensity of C =O/CH is increased while increasing the amount of clay. DSC showed the appearance of multiple endotherms of poly(glycolic acid). TGA showed the percentage weight residue remain above 750℃ for polymer-nano composite system was 21% and hence proved the flame retardancy (char forming) nature. TEM confirmed the nano size of the clay used to catalyze the condensation reaction. The intrinsic viscosity value was increased with the increase of percentage weight of Hectorite type clay.

  3. Contribution to the study of the oxidation reaction of Np(V) by nitric acid catalyzed par nitrous acid

    International Nuclear Information System (INIS)

    The oxidation reaction kinetics of Np(V) to Np(VI) by nitric acid catalyzed by nitrous acid was studied. In a first part, a detailed bibliographical survey was made of the oxidation-reduction reactions of U, Np, Pu, Am with nitrous and nitric acids (51 references). It is shown that only when both the organic and aqueous phases are mixed up, the extraction of a reaction product (NpVI) induces an equilibrium displacement. TBP was used as solvent. It is shown that the extraction of nitrous acid from the solvent enables the nitrous acid concentration to be kept constant and in the same order of magnitude than that of Np. This enables to show that Np(V) and nitrous acid have no simple orders. The temperature and nitric acid concentration dependence was studied. It is shown that tetravalent nitrogen must play a major part in the Np(V) oxidation

  4. Stereoselectivities in α- and β-Amino Acids Catalyzed Mannich Reactions Involving Cyclohexanone

    Institute of Scientific and Technical Information of China (English)

    WANG Ying; FU Ai-ping; LI Hong-liang; TIAN Feng-hui; YUAN Shu-ping; SI Hong-zong; DUAN Yun-bo; WANG Zong-hua

    2011-01-01

    The effects of two different amino acid catalysts on the stereoselectivities in the direct Mannich reactions of cyclohexanone,p-anisidine and p-nitrobenzaldehyde were studied with the aid of density functional theory.Transition states of the stereo-determining C-C bond-forming step with the addition of enamine intermediate to the imine for the L-proline(α-amino acid) and (R)-3-pyrrolidinecarboxylic acid(β-amino acid)-catalyzed processes were reported.B3LYP/6-31G** calculations provide a good explanation for the opposite syn vs.anti diastereoselectivities of these two different kinds of catalysts(syn-selectivity for the α-amino acid catalysts,anti-selectivity for the β-amino acid catalysts).Calculated and observed diastereomeric ratio and enantiomeric excess values are in reasonable agreement.

  5. Origins of Stereoselectivities in Chiral Phosphoric Acid-Catalyzed Allylborations and Propargylations of Aldehydes

    OpenAIRE

    Wang, Hao; Jain, Pankaj; Antilla, Jon C.; Houk, K. N.

    2013-01-01

    The chiral BINOL-phosphoric acid catalyzed allylboration and propargylation reactions are studied with density functional theory (B3LYP and B3LYP-D3). Two different models were recently proposed for these reactions by Goodman and our group, respectively. In Goodman's model for allylborations, the catalyst interacts with the boronate pseudo-axial oxygen. By contrast, our model for propargylations predicts that the catalyst interacts with the boronate pseudo-equatorial oxygen. In both models, t...

  6. Enantioselective aldol reaction between isatins and cyclohexanone catalyzed by amino acid sulphonamides.

    Science.gov (United States)

    Wang, Jun; Liu, Qi; Hao, Qing; Sun, Yanhua; Luo, Yiming; Yang, Hua

    2015-04-01

    Sulphonamides derived from primary α-amino acid were successfully applied to catalyze the aldol reaction between isatin and cyclohexanone under neat conditions. More interestingly, molecular sieves, as privileged additives, were found to play a vital role in achieving high enantioselectivity. Consequently, high yields (up to 99%) along with good enantioselectivities (up to 92% ee) and diastereoselectivities (up to 95:5 dr) were obtained. In addition, this reaction was also conveniently scaled up, demonstrating the applicability of this protocol.

  7. Keto-Enol Tautomerizations Catalyzed by Water and Carboxylic Acids

    Science.gov (United States)

    da Silva, G.

    2009-12-01

    The ability of weakly-bound complexes to influence the kinetics of gas phase reactions, particularly in atmospheric chemistry, has long been speculated. This study uses quantum chemistry and statistical reaction rate theory to identify that bound water molecules can significantly reduce barriers to intramolecular hydrogen shift reactions, via a double-hydrogen-shift mechanism. The bound water molecule directly participates in the hydrogen shift reaction, exchanging a H atom with its counterpart. For the vinyl alcohol to acetaldehyde keto-enol tautomerization this mechanism cuts the reaction barrier approximately in half, reducing it by over 30 kcal mol-1. In contrast, while a non-participatory ‘bystander’ water molecule also reduces the hydrogen shift barrier, it is only by around 3 kcal/mol. When a carboxylic acid replaces water in the double-hydrogen-shift mechanism the barrier to keto-enol tautomerization is decimated, reduced to less than 6 kcal/mol (around 15 kcal/mol in the reverse direction). This results from reduced strain in the hydrogen shift transition state, and achieves enol lifetimes in the troposphere that become short on relevant timescales. Rapid enol to ketone isomerizations are currently required to explain the oxidation products of isoprene. The wider significance of rapid hydrogen shift reactions in atmospherically relevant molecules and radicals is also explored.

  8. Acetic acid-catalyzed formation of N-phenylphthalimide from phthalanilic acid: a computational study of the mechanism.

    Science.gov (United States)

    Takahashi, Ohgi; Kirikoshi, Ryota; Manabe, Noriyoshi

    2015-05-28

    In glacial acetic acid, phthalanilic acid and its monosubstituents are known to be converted to the corresponding phthalimides in relatively good yields. In this study, we computationally investigated the experimentally proposed two-step (addition-elimination or cyclization-dehydration) mechanism at the second-order Møller-Plesset perturbation (MP2) level of theory for the unsubstituted phthalanilic acid, with an explicit acetic acid molecule included in the calculations. In the first step, a gem-diol tetrahedral intermediate is formed by the nucleophilic attack of the amide nitrogen. The second step is dehydration of the intermediate to give N-phenylphthalimide. In agreement with experimental findings, the second step has been shown to be rate-determining. Most importantly, both of the steps are catalyzed by an acetic acid molecule, which acts both as proton donor and acceptor. The present findings, along with those from our previous studies, suggest that acetic acid and other carboxylic acids (in their undissociated forms) can catalyze intramolecular nucleophilic attacks by amide nitrogens and breakdown of the resulting tetrahedral intermediates, acting simultaneously as proton donor and acceptor. In other words, double proton transfers involving a carboxylic acid molecule can be part of an extensive bond reorganization process from cyclic hydrogen-bonded complexes.

  9. Acetic Acid Can Catalyze Succinimide Formation from Aspartic Acid Residues by a Concerted Bond Reorganization Mechanism: A Computational Study

    Directory of Open Access Journals (Sweden)

    Ohgi Takahashi

    2015-01-01

    Full Text Available Succinimide formation from aspartic acid (Asp residues is a concern in the formulation of protein drugs. Based on density functional theory calculations using Ace-Asp-Nme (Ace = acetyl, Nme = NHMe as a model compound, we propose the possibility that acetic acid (AA, which is often used in protein drug formulation for mildly acidic buffer solutions, catalyzes the succinimide formation from Asp residues by acting as a proton-transfer mediator. The proposed mechanism comprises two steps: cyclization (intramolecular addition to form a gem-diol tetrahedral intermediate and dehydration of the intermediate. Both steps are catalyzed by an AA molecule, and the first step was predicted to be rate-determining. The cyclization results from a bond formation between the amide nitrogen on the C-terminal side and the side-chain carboxyl carbon, which is part of an extensive bond reorganization (formation and breaking of single bonds and the interchange of single and double bonds occurring concertedly in a cyclic structure formed by the amide NH bond, the AA molecule and the side-chain C=O group and involving a double proton transfer. The second step also involves an AA-mediated bond reorganization. Carboxylic acids other than AA are also expected to catalyze the succinimide formation by a similar mechanism.

  10. Grape skins (Vitis vinifera L.) catalyze the in vitro enzymatic hydroxylation of p-coumaric acid to caffeic acid

    DEFF Research Database (Denmark)

    Arnous, Anis; Meyer, Anne S.

    2009-01-01

    The ability of grape skins to catalyze in vitro conversion of p-coumaric acid to the more potent antioxidant caffeic acid was studied. Addition of different concentrations of p-coumaric to red grape skins (Cabernet Sauvignon) resulted in formation of caffeic acid. This caffeic acid formation (Y......) correlated positively and linearly to p-coumaric acid consumption (X): Y = 0.5 X + 9.5; R 2 = 0.96, P skin concentrations, indicated that the grape skins harboured an o......-hydroxylation activity, proposedly a monophenol- or a flavonoid 3′-monooxygenase activity (EC 1.14.18.1 or EC 1.14.13.21). The K m of this crude o-hydroxylation activity in the red grape skin was 0.5 mM with p-coumaric acid....

  11. Solid acid-catalyzed depolymerization of barley straw driven by ball milling.

    Science.gov (United States)

    Schneider, Laura; Haverinen, Jasmiina; Jaakkola, Mari; Lassi, Ulla

    2016-04-01

    This study describes a time and energy saving, solvent-free procedure for the conversion of lignocellulosic barley straw into reducing sugars by mechanocatalytical pretreatment. The catalytic conversion efficiency of several solid acids was tested which revealed oxalic acid dihydrate as a potential catalyst with high conversion rate. Samples were mechanically treated by ball milling and subsequently hydrolyzed at different temperatures. The parameters of the mechanical treatment were optimized in order to obtain sufficient amount of total reducing sugar (TRS) which was determined following the DNS assay. Additionally, capillary electrophoresis (CE) and Fourier transform infrared spectrometry (FT-IR) were carried out. Under optimal conditions TRS 42% was released using oxalic acid dihydrate as a catalyst. This study revealed that the acid strength plays an important role in the depolymerization of barley straw and in addition, showed, that the oxalic acid-catalyzed reaction generates low level of the degradation product 5-hydroxymethylfurfural (HMF). PMID:26859328

  12. Preliminary Study on Lipase-catalyzed Synthesis of Polyesters Containing L-Malic Acid Units

    Institute of Scientific and Technical Information of China (English)

    Da Hu YAO; Guang Ji LI

    2006-01-01

    Terpolymer of 1, 8-octanediol, adipic acid, and L-malic acid was synthesized via a lipase-catalyzed direct polycondensation. The products were characterized by GPC and 1H NMR.The results indicated that the molecular weight of the prepared polymers decreased with increasing L-malic acid content in the monomer feed ratio, and that change in the L-malic acid content from 0to 20 mol % did not remarkably influenced on the molecular weight distribution Mw/Mn of the prepared samples. The 1H NMR spectra of the obtained copolymer samples showed that hydroxyl groups of L-malic acid did not take part in the polymerization reaction.

  13. Palladium-catalyzed cross-coupling reactions of aryl boronic acids with aryl halides in water.

    Science.gov (United States)

    Wang, Shaoyan; Zhang, Zhiqiang; Hu, Zhizhi; Wang, Yue; Lei, Peng; Chi, Haijun

    2009-01-01

    An efficient Suzuki cross-coupling reaction using a variety of aryl halides in neat water was developed. The Pd-catalyzed reaction between aryl bromides or chlorides and phenyl boronic acids was compatible with various functional groups and affords biphenyls in good to excellent yields without requirement of organic cosolvents. The air stability and solubility in water of the palladium-phosphinous acid complexes were considered to facilitate operation of the coupling reaction and product isolation. The reaction conditions including Pd catalyst selection, temperature, base and catalyst recoverability were also investigated. PMID:25084408

  14. Silica-supported Copper(Ⅱ) Catalyzed Coupling of Arylboronic Acids with Imidazoles

    Institute of Scientific and Technical Information of China (English)

    ZHANG Li-Yuan; WANG Lei

    2006-01-01

    Immobilized copper(Ⅱ) in organic-inorganic hybrid materials catalyzed Ar-N coupling of arylboronic acids with imidazoles has been developed. Arylboronic acids reacted with imidazoles smoothly in the presence of a 3-(2-aminoethylamino)propyl functionalized silica gel immobilized copper(Ⅱ) catalyst (10 mol%) in methanol without any additives and bases. The reactions generated the corresponding cross-coupling products in good yields.Furthermore, silica-supported copper can be recovered and recycled by a simple filtration procedure and used for five consecutive trials without decreases in activity.

  15. Acid-Catalyzed Oxygen-18 Labeling of Peptides for Proteomics Applications

    Science.gov (United States)

    Niles, Richard; Witkowska, H. Ewa; Allen, Simon; Hall, Steven C.; Fisher, Susan J.; Hardt, Markus

    2010-01-01

    In enzymatic 18O-labeling strategies for quantitative proteomics, the exchange of carboxyl oxygens at low pH is a common, undesired side reaction. We asked if acid-catalyzed back exchange could interfere with quantitation and whether the reaction itself could be used as an alternative method for introducing 18O label into peptides. Several synthetic amino acid sequences were dissolved in dilute acid containing 50% (v/v) H218O and incubated at room temperature. Aliquots were removed over a period of 3 weeks and analyzed by tandem mass spectrometry (MS/MS). 18O-incorporation ratios were determined by linear regression analysis that allowed for multiple stable isotope incorporations. At low pH, peptides exchanged their carboxyl oxygen atoms with the aqueous solvent. The isotope patterns gradually shifted to higher masses until they reached the expected binomial distribution at equilibrium after ~11 days. Reaction rates were residue and sequence specific. Due to its slow nature, the acid-based back exchange is expected to minimally interfere with enzymatic 18O-labeling studies provided that storage and analysis conditions minimize low pH exposure times. On its own, acid-catalyzed 18O labeling is a general tagging strategy that is an alternative to the chemical, metabolic and enzymatic isotope-labeling schemes currently used in quantitative proteomics. PMID:19243188

  16. Base catalyzed transesterification of acid treated vegetable oil blend for biodiesel production

    Energy Technology Data Exchange (ETDEWEB)

    Yusup, Suzana; Khan, Modhar Ali [Chemical Engineering Department, Universiti Teknologi PETRONAS, Seri Iskandar, Tronoh, Perak 31750 (Malaysia)

    2010-10-15

    Biodiesel can be produced from low cost non-edible oils and fats. However, most of these sources are of high free fatty acid content which requires two stage transesterification to reduce the acid value and produce biodiesel. The acid treatment step is usually followed by base transesterification since the latter can yield higher conversions of methyl esters at shorter reaction time when compared with acid catalyzed reaction. In the current study, base transesterification in the second stage of biodiesel synthesis is studied for a blend of crude palm/crude rubber seed oil that had been characterized and treated with acid esterification. Optimum conditions for the reaction were established and effect of each variable was investigated. The base catalyzed transesterification favored a temperature of 55 C with methanol/oil molar ratio of 8/1 and potassium hydroxide at 2% (ww{sup -1}) (oil basis). The conversion of methyl esters exceeded 98% after 5 h and the product quality was verified to match that for biodiesel with international standards. (author)

  17. Formation of linear polyenes in poly(vinyl alcohol) films catalyzed by phosphotungstic acid, aluminum chloride, and hydrochloric acid

    Science.gov (United States)

    Tretinnikov, O. N.; Sushko, N. I.; Malyi, A. B.

    2016-07-01

    Formation of linear polyenes-(CH=CH)n-via acid-catalyzed thermal dehydration of polyvinyl alcohol in 9- to 40-µm-thick films of this polymer containing hydrochloric acid, aluminum chloride, and phosphotungstic acid as dehydration catalysts was studied by electronic absorption spectroscopy. The concentration of long-chain ( n ≥ 8) polyenes in films containing phosphotungstic acid is found to monotonically increase with the duration of thermal treatment of films, although the kinetics of this process is independent of film thickness. In films containing hydrochloric acid and aluminum chloride, the formation rate of polyenes with n ≥ 8 rapidly drops as film thickness decreases and the annealing time increases. As a result, at a film thickness of less than 10-12 µm, long-chain polyenes are not formed at all in these films no matter how long thermal duration is. The reason for this behavior is that hydrochloric acid catalyzing polymer dehydration in these films evaporates from the films during thermal treatment, the evaporation rate inversely depending on film thickness.

  18. [Asymmetric synthesis of aromatic L-amino acids catalyzed by transaminase].

    Science.gov (United States)

    Xia, Wenna; Sun, Yu; Min, Cong; Han, Wei; Wu, Sheng

    2012-11-01

    Aromatic L-Amino acids are important chiral building blocks for the synthesis of many drugs, pesticides, fine chemicals and food additives. Due to the high activity and steroselectivity, enzymatic synthesis of chiral building blocks has become the main research direction in asymmetric synthesis field. Guided by the phylogenetic analysis of transaminases from different sources, two representative aromatic transaminases TyrB and Aro8 in type I subfamily, from the prokaryote Escherichia coli and eukaryote Saccharomyces cerevisia, respectively, were applied for the comparative study of asymmetric transamination reaction process and catalytic efficiency of reversely converting keto acids to the corresponding aromatic L-amino acid. Both TyrB and Aro8 could efficiently synthesize the natural aromatic amino acids phenylalanine and tyrosine as well as non-natural amino acid phenylglycine. The chiral HPLC analysis showed the produced amino acids were L-configuration and the e.e value was 100%. L-alanine was the optimal amino donor, and the transaminase TyrB and Aro8 could not use D-amino acids as amino donor. The optimal molar ratio of amino donor (L-alanine) and amino acceptor (aromatic alpha-keto acids) was 4:1. Both of the substituted group on the aromatic ring and the length of fatty acid carbon chain part in the molecular structure of aromatic substrate alpha-keto acid have the significant impact on the enzyme-catalyzed transamination efficiency. In the experiments of preparative-scale transamination synthesis of L-phenylglycine, L-phenylalanine and L-tyrosine, the specific production rate catalyzed by TryB were 0.28 g/(g x h), 0.31 g/(g x h) and 0.60 g/(g x h) and the specific production rate catalyzed by Aro8 were 0.61 g/(g x h), 0.48 g/(g x h) and 0.59 g/(g x h). The results obtained here were useful for applying the transaminases to asymmetric synthesis of L-amino acids by reversing the reaction balance in industry.

  19. Esterification of Oleic Acid for Biodiesel Production Catalyzed by SnCl2: A Kinetic Investigation

    Directory of Open Access Journals (Sweden)

    Marcio J. da Silva

    2008-09-01

    Full Text Available The production of biodiesel from low-cost raw materials which generally contain high amounts of free fatty acids (FFAs is a valuable alternative that would make their production costs more competitive than petroleum-derived fuel. Currently, the production of biodiesel from this kind of raw materials comprises a two-stage process, which requires an initial acid-catalyzed esterification of the FFA, followed by a basecatalyzed transesterification of the triglycerides. Commonly, the acid H2SO4 is the catalyst on the first step of this process. It must be said, however, that major drawbacks such as substantial reactor corrosion and the great generation of wastes, including the salts formed due to neutralization of the mineral acid, are negative and virtually unsurmountable aspects of this protocol. In this paper, tin(II chloride dihydrate (SnCl2·2H2O, an inexpensive Lewis acid, was evaluated as catalyst on the ethanolysis of oleic acid, which is the major component of several fat and vegetable oils feedstocks. Tin chloride efficiently promoted the conversion of oleic acid into ethyl oleate in ethanol solution and in soybean oil samples, under mild reaction conditions. The SnCl2 catalyst was shown to be as active as the mineral acid H2SO4. Its use has relevant advantages in comparison to mineral acids catalysts, such as less corrosion of the reactors and as well as avoiding the unnecessary neutralization of products. Herein, the effect of the principal parameters of reaction on the yield and rate of ethyl oleate production has been investigated. Kinetic measurements revealed that the esterification of oleic acid catalyzed by SnCl2·2H2O is first-order in relation to both FFAs and catalyst concentration. Experimentally, it was verified that the energy of activation of the esterification reaction of oleic acid catalyzed by SnCl2 was very close those reported for H2SO4.

  20. Amine-Catalyzed Highly Regioselective and Stereoselective C(sp(2) )-C(sp(2) ) Cross-Coupling of Naphthols with trans-α,β-Unsaturated Aldehydes.

    Science.gov (United States)

    Hu, Yang; Ma, Yueyue; Sun, Rengwei; Yu, Xinhong; Xie, Hexin; Wang, Wei

    2015-09-01

    A metal-free C(sp(2) )-C(sp(2) ) cross-coupling approach to highly congested (E)-α-naphtholylenals from simple naphthols and enals is described. The mild reaction conditions with pyridine hydrobromideperbromide (PHBP) as the bromination reagent in the presence of piperidine or diphenylprolinol trimethylsilyl (TMS) ether as promoters enable the process in good yields and with high chemoselectivity, regioselectivity, and stereoselectivity. The process involves an unprecedented pathway of in situ regioselective 4-bromination of 1-naphthols and the subsequent unusual aromatic nucleophilic substitution of the resulting 4-bromo-1-naphthols with the α-C(sp(2) ) of enals through a Michael-type Friedel-Crafts alkylation-dearomatization followed by a cyclopropanation ring-opening cascade process. The noteworthy features of this strategy are highlighted by the highly efficient creation of a C(sp(2) )-C(sp(2) ) bond from readily available unfunctionalized naphthols and enals catalyzed by non-metal, readily available cyclic secondary amines under mild reaction conditions. PMID:26096893

  1. Synthesis of 2-monoacylglycerols and structured triacylglycerols rich in polyunsaturated fatty acids by enzyme catalyzed reactions.

    Science.gov (United States)

    Rodríguez, Alicia; Esteban, Luis; Martín, Lorena; Jiménez, María José; Hita, Estrella; Castillo, Beatriz; González, Pedro A; Robles, Alfonso

    2012-08-10

    This paper studies the synthesis of structured triacylglycerols (STAGs) by a four-step process: (i) obtaining 2-monoacylglycerols (2-MAGs) by alcoholysis of cod liver oil with several alcohols, catalyzed by lipases Novozym 435, from Candida antartica and DF, from Rhizopus oryzae, (ii) purification of 2-MAGs, (iii) formation of STAGs by esterification of 2-MAGs with caprylic acid catalyzed by lipase DF, from R. oryzae, and (iv) purification of these STAGs. For the alcoholysis of cod liver oil, absolute ethanol, ethanol 96% (v/v) and 1-butanol were compared; the conditions with ethanol 96% were then optimized and 2-MAG yields of around 54-57% were attained using Novozym 435. In these 2-MAGs, DHA accounted for 24-31% of total fatty acids. In the operational conditions this lipase maintained a stable level of activity over at least 11 uses. These results were compared with those obtained with lipase DF, which deactivated after only three uses. The alcoholysis of cod liver oil and ethanol 96% catalyzed by Novozym 435 was scaled up by multiplying the reactant amounts 100-fold and maintaining the intensity of treatment constant (IOT=3g lipase h/g oil). In these conditions, the 2-MAG yield attained was about 67%; these 2-MAGs contained 36.6% DHA. The synthesized 2-MAGs were separated and purified from the alcoholysis reaction products by solvent extraction using solvents of low toxicity (ethanol and hexane); 2-MAG recovery yield and purity of the target product were approximately 96.4% and 83.9%, respectively. These 2-MAGs were transformed to STAGs using the optimal conditions obtained in a previous work. After synthesis and purification, 93% pure STAGs were obtained, containing 38% DHA at sn-2 position and 60% caprylic acid (CA) at sn-1,3 positions (of total fatty acids at these positions), i.e. the major TAG is the STAG with the structure CA-DHA-CA.

  2. Acid-catalyzed hydrogenation of olefins. A theoretical study of the HF- and H/sub 3/O/sup +/-catalyzed hydrogenation of ethylene

    Energy Technology Data Exchange (ETDEWEB)

    Siria, J.C.; Duran, M.; Lledos, A.; Bertran, J.

    1987-12-09

    The HF- and H/sub 3/O/sup +/-catalyzed hydrogenation of ethylene and the direct addition of molecular hydrogen to ethylene have been studied theoretically by means of ab initio MO calculations using different levels of theory. The main results are that catalysis by HF lowers the potential energy barrier to a large extent, while catalysis by H/sub 3/O/sup +/ diminishes dramatically the barrier for the reaction. Entropic contributions leave these results unchanged. The mechanisms of the two acid-catalyzed hydrogenations are somewhat different. While catalysis by HF exhibits bifunctional characteristics, catalysis by H/sub 3/O/sup +/ proceeds via an initial formation of a carbocation. It is shown that catalysis by strong acids may be an alternate way for olefin hydrogenation.

  3. Biodiesel Production from Spent Fish Frying Oil Through Acid-Base Catalyzed Transesterification

    Directory of Open Access Journals (Sweden)

    Abdalrahman B. Fadhil

    2012-06-01

    Full Text Available Biodiesel fuels were prepared from a special type of frying oil namely spent fish frying oil through two step transesterification viz. acid-base catalyzed transesterification. Hydrochloric acid and potassium hydroxide with methanol were used for this purpose. The oil was pre-treated with (1.0 wt% HCl and methanol to reduce free fatty acids content of the oil. Then, conditions of the base catalyzed step such as base concentration, reaction temperature, methanol to oil molar ratio and reaction time were optimized. The study raveled that, 0.50% KOH w/w of oil; a 6:1 methanol to oil molar ratio; a reaction temperature of 60°C and a duration of 1h were the optimal conditions because they resulted in high biodiesel yield. Fuel properties of the products were assessed and found better than those of the parent oil. Furthermore, they met the specified limits according to the ASTM standards. Thin layer chromatography was used as a simple technique to monitor the transesterification of the oil. Blending of the optimal biodiesel sample with petro diesel using specified volume percentages was done as well. The results indicated that biodiesel had slight effect on the values of the assessed properties.

  4. Palladium(II)-Catalyzed Tandem Synthesis of Acenes Using Carboxylic Acids as Traceless Directing Groups.

    Science.gov (United States)

    Kim, Kiho; Vasu, Dhananjayan; Im, Honggu; Hong, Sungwoo

    2016-07-18

    A straightforward synthetic strategy for generating useful anthracene derivatives was developed involving palladium(II)-catalyzed tandem transformation with carboxylic acids as traceless directing groups. Carboxyl-directed C-H alkenylation, carboxyl-directed secondary C-H activation and rollover, intramolecular C-C bond formation, and decarboxylative aromatization are proposed as the key steps in the tandem reaction pathway. This novel synthetic route utilizes a broad range of substrates and provides a convenient synthetic tool that allows access to acenes. PMID:27244536

  5. Facile isothermal solid acid catalyzed ionic liquid pretreatments to enhance the combined sugars production from Arundo donax Linn.

    OpenAIRE

    You, Tingting; Shao, Lupeng; Wang, Ruizhen; Zhang, Liming; Feng XU

    2016-01-01

    Background Solid acid catalyzed inexpensive ionic liquid (IL) pretreatment is promising because of its effectiveness at decreasing biomass recalcitrance to subsequent enzymatic hydrolysis or in situ hydrolysis of carbohydrate oligomers. However, the conventional strategy was limited by the complex non-isothermal process and considering only one aspect of sugar recovery. In this study, facile isothermal pretreatments using Amberlyst 35DRY catalyzed 1-n-butyl-3-methylimidazolium chloride ([C4mi...

  6. 7-deoxyloganetic acid synthase catalyzes a key 3 step oxidation to form 7-deoxyloganetic acid in Catharanthus roseus iridoid biosynthesis.

    Science.gov (United States)

    Salim, Vonny; Wiens, Brent; Masada-Atsumi, Sayaka; Yu, Fang; De Luca, Vincenzo

    2014-05-01

    Iridoids are key intermediates required for the biosynthesis of monoterpenoid indole alkaloids (MIAs), as well as quinoline alkaloids. Although most iridoid biosynthetic genes have been identified, one remaining three step oxidation required to form the carboxyl group of 7-deoxyloganetic acid has yet to be characterized. Here, it is reported that virus-induced gene silencing of 7-deoxyloganetic acid synthase (7DLS, CYP76A26) in Catharanthus roseus greatly decreased levels of secologanin and the major MIAs, catharanthine and vindoline in silenced leaves. Functional expression of this gene in Saccharomyces cerevisiae confirmed its function as an authentic 7DLS that catalyzes the 3 step oxidation of iridodial-nepetalactol to form 7-deoxyloganetic acid. The identification of CYP76A26 removes a key bottleneck for expression of iridoid and related MIA pathways in various biological backgrounds. PMID:24594312

  7. Enantioselective and Regiodivergent Functionalization of N-Allylcarbamates by Mechanistically Divergent Multicatalysis.

    Science.gov (United States)

    Richmond, Edward; Khan, Ismat Ullah; Moran, Joseph

    2016-08-22

    A pair of mechanistically divergent multicatalytic reaction sequences has been developed consisting of nickel-catalyzed isomerization of N-allylcarbamates and subsequent phosphoric-acid-catalyzed enantioselective functionalization of the resulting intermediates. By appropriate selection of reaction partners, in situ generated imines and ene-carbamates are mechanistically partitioned to yield opposing functionalized products. Formal α-functionalization to give protected α-arylamines is achieved upon enantioselective Friedel-Crafts reaction with arene nucleophiles, whereas formal β-functionalization is achieved upon reaction with diarylimine electrophiles in an enantioselective Povarov-[4+2] cycloaddition. PMID:27461524

  8. Noble metal catalyzed hydrogen generation from formic acid in nitrite-containing simulated nuclear waste media

    International Nuclear Information System (INIS)

    The Hanford Waste Vitrification Plant (HWVP) is being designed by the U.S. Department of Energy to immobilize high-level nuclear waste. Simulants for the HWVP feed containing the major nonradioactive components Al, Cd, Fe, Mn, Nd, Ni, Si, Zr, Na, CO32-, NO3- and NO2- were used as media to evaluate the stability of formic acid towards hydrogen evolution by the reaction HCO2H→H2+/CO2 catalyzed by the noble metals Ru, Rh, and/or Pd found in significant quantities in uranium fission products. Small-scale experiments using 40-50 mL of feed simulant in closed glass reactors (250-550 mL total volume) at 80-100 degree C were used to study the effect of nitrite and nitrate ion on the catalytic activities of the noble metals for formic acid decomposition. Reactions were monitored using gas chromatography to analyze the CO2, H2, NO, and N2O in the gas phase as a function of time. Rhodium, which was introduced as soluble RhCl3.3H2O, was found to be the most active catalyst for hydrogen generation from formic acid above nearly 80 degree C in the presence of nitrite ion in accord with earlier observations. The apparent homogeneous nature of the nitrite-promoted Rh-catalyzed formic acid decomposition is consistent with the approximate pseudo-first-order dependence of the hydrogen production rate on Rh concentration. 24 refs., 7 figs., 2 tabs

  9. Lewis Acid Pairs for the Activation of Biomass-derived Oxygenates in Aqueous Media

    Energy Technology Data Exchange (ETDEWEB)

    Roman, Yuriy [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2015-09-14

    post-synthetic modifications, layered zeolite precursors can be transformed into 2-dimensional (2D), zeolites with open architectures. These novel hierarchical microporous/mesoporous materials with exposed active sites can facilitate the conversion of bulky substrates while maintaining higher stability than amorphous mesoporous materials. However, post-synthetic exfoliation techniques are energy intensive, multi-step and require highly alkaline conditions that result in low silica yields and a partially amorphous product. In this aim, we demonstrate an effective one-pot synthesis method to generate exfoliated single-unit-cell thick MWW nanosheets. The new material, named MIT-1, is synthesized using a rationally-designed OSDA and results in a material with high crystallinity, surface area, and acidity that does not require post-synthetic treatments other than calcination. A parametric study of Al, Na, and water content reveals that MIT-1 crystallizes over a wide synthetic window. Characterization data show that MIT-1 has high mesoporosity with an external surface area exceeding 500 m2g-1 and a high external acid site density of 21 x 10-5 mol g-1. Catalytic tests demonstrate that MIT-1 has three-fold higher catalytic activity for the Friedel-Crafts alkylation of benzene with benzyl alcohol as compared to that of other 3D MWW topology zeolites.

  10. Recovery of arabinan in acetic acid-catalyzed hydrothermal pretreatment on corn stover

    DEFF Research Database (Denmark)

    Xu, Jian; Hedegaard, Mette Christina; Thomsen, Anne Belinda

    2009-01-01

    Acetic acid-catalyzed hydrothermal pretreatment was done on corn stover under 195 °C, 15 min with the acetic acid ranging from 5 × 10−3 to 0.2 g g−1 corn stover. After pretreatment, the water-insoluble solids (WISs) and liquors were collected respectively. Arabinan recoveries from both WIS...... and liquors were investigated. The results indicate that there was no detectable arabinan left in the WIS when the acetic acid of 0.1 and 0.2 g g−1 corn stover were used in the pretreatment. The arabinan contents in the other WISs were not more than 10%. However, the arabinan found in the liquors...... was not covering the amount of arabinan released from the raw corn stover. For the arabinan recovery from liquor fractions, the highest of 43.57% was obtained by the pretreatment of acetic acid of 0.01 g g−1 of corn stover and the lowest was only 26.77% when the acetic acid of 0.2 g g−1 corn stover was used...

  11. Palladium-atom catalyzed formic acid decomposition and the switch of reaction mechanism with temperature.

    Science.gov (United States)

    He, Nan; Li, Zhen Hua

    2016-04-21

    Formic acid decomposition (FAD) reaction has been an innovative way for hydrogen energy. Noble metal catalysts, especially palladium-containing nanoparticles, supported or unsupported, perform well in this reaction. Herein, we considered the simplest model, wherein one Pd atom is used as the FAD catalyst. With high-level theoretical calculations of CCSD(T)/CBS quality, we investigated all possible FAD pathways. The results show that FAD catalyzed by one Pd atom follows a different mechanism compared with that catalyzed by surfaces or larger clusters. At the initial stage of the reaction, FAD follows a dehydration route and is quickly poisoned by CO due to the formation of very stable PdCO. PdCO then becomes the actual catalyst for FAD at temperatures approximately below 1050 K. Beyond 1050 K, there is a switch of catalyst from PdCO to Pd atom. The results also show that dehydration is always favoured over dehydrogenation on either the Pd-atom or PdCO catalyst. On the Pd-atom catalyst, neither dehydrogenation nor dehydration follows the formate mechanism. In contrast, on the PdCO catalyst, dehydrogenation follows the formate mechanism, whereas dehydration does not. We also systematically investigated the performance of 24 density functional theory methods. We found that the performance of the double hybrid mPW2PLYP functional is the best, followed by the B3LYP, B3PW91, N12SX, M11, and B2PLYP functionals.

  12. An atom-economic approach to carboxylic acids via Pd-catalyzed direct addition of formic acid to olefins with acetic anhydride as a co-catalyst.

    Science.gov (United States)

    Wang, Yang; Ren, Wenlong; Shi, Yian

    2015-08-21

    An effective Pd-catalyzed hydrocarboxylation of olefins using formic acid with acetic anhydride as a co-catalyst is described. A variety of carboxylic acids are obtained in good yields with high regioselectivities under mild reaction conditions without the use of toxic CO gas.

  13. Phenylalanine Aminomutase-Catalyzed Addition of Ammonia to Substituted Cinnamic Acids : a Route to Enantiopure alpha- and beta-Amino Acids

    NARCIS (Netherlands)

    Szymanski, Wiktor; Wu, Bian; Weiner, Barbara; Wildeman, Stefaan de; Feringa, Ben L.; Janssen, Dick B.

    2009-01-01

    An approach is described for the synthesis of aromatic alpha- and beta-amino acids that Uses phenylalanine aminomutase to catalyze a highly enantioselective addition of ammonia to substituted cinnamic acids. The reaction has a broad scope and yields Substituted alpha- and beta-phenylalanines with ex

  14. Intrinsic oxidation kinetics of sulfite catalyzed by peracetic acid under different water quality and light conditions

    Institute of Scientific and Technical Information of China (English)

    WANG LiDong; ZHAO Yi; LI QiangWei; CHEN ZhouYan; LIU SongTao; MA YongLiang; HAO JiMing

    2009-01-01

    Oxidation of sulfite is an important process in wet flue gas desulfurization. Using highly purified water or distilled water as a reaction medium and a transparent or an opaque intermittent reaction apparatus, the intrinsic oxidation kinetics of sulfite catalyzed by peracetic acid was investigated under four dif-ferent conditions. The reaction order of the reagents and the activation energy were obtained. The re-sults indicate that water quality and light have no obvious effects on the reaction order and activation energy, but have an influence on the reaction rate constant. The mechanism of the intrinsic reaction is proposed. The results derived with this mechanism are in good agreement with the experimental re-sults.

  15. Intrinsic oxidation kinetics of sulfite catalyzed by peracetic acid under different water quality and light conditions

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Oxidation of sulfite is an important process in wet flue gas desulfurization.Using highly purified water or distilled water as a reaction medium and a transparent or an opaque intermittent reaction apparatus,the intrinsic oxidation kinetics of sulfite catalyzed by peracetic acid was investigated under four dif-ferent conditions.The reaction order of the reagents and the activation energy were obtained.The re-sults indicate that water quality and light have no obvious effects on the reaction order and activation energy,but have an influence on the reaction rate constant.The mechanism of the intrinsic reaction is proposed.The results derived with this mechanism are in good agreement with the experimental re-sults.

  16. Investigation of acetic acid-catalyzed hydrothermal pretreatment on corn stover

    DEFF Research Database (Denmark)

    Xu, Jian; Thomsen, Mette Hedegaard; Thomsen, Anne Belinda

    2010-01-01

    xylan recovery of 81.82% was observed by the pretreatment with 10 g AA/kg RCS. The toxic test on liquors showed that the inhibition effect happened to Baker's yeast when the acetic acid used in the pretreatment was higher than 100 g/kg RCS. The WIS obtained from the pretreatment with 15 g and 30 g....../kg RCS were subjected to enzymatic hydrolysis and more easily converted to ethanol by Baker's yeast, which gave the ethanol concentration of 33.72 g/L and 32.06 g/L, respectively, higher than 22.04 g/L which was from the non-catalyzed LHW pretreatment (195 °C, 15 min). The ethanol concentration from...

  17. Kinetics of Acid-Catalyzed Dehydration of Cyclic Hemiacetals in Organic Aerosol Particles in Equilibrium with Nitric Acid Vapor.

    Science.gov (United States)

    Ranney, April P; Ziemann, Paul J

    2016-04-28

    Previous studies have shown that 1,4-hydroxycarbonyls, which are often major products of the atmospheric oxidation of hydrocarbons, can undergo acid-catalyzed cyclization and dehydration in aerosol particles to form highly reactive unsaturated dihydrofurans. In this study the kinetics of dehydration of cyclic hemiacetals, the rate-limiting step in this process, was investigated in a series of environmental chamber experiments in which secondary organic aerosol (SOA) containing cyclic hemiacetals was formed from the reaction of n-pentadecane with OH radicals in dry air in the presence of HNO3. A particle beam mass spectrometer was used to monitor the formation and dehydration of cyclic hemiacetals in real time, and SOA and HNO3 were quantified in filter samples by gravimetric analysis and ion chromatography. Measured dehydration rate constants increased linearly with increasing concentration of HNO3 in the gas phase and in SOA, corresponding to catalytic rate constants of 0.27 h(-1) ppmv(-1) and 7.0 h(-1) M(-1), respectively. The measured Henry's law constant for partitioning of HNO3 into SOA was 3.7 × 10(4) M atm(-1), ∼25% of the value for dissolution into water, and the acid dissociation constant was estimated to be water. The results indicate that HNO3 was only weakly dissociated in the SOA and that dehydration of cyclic hemiacetals was catalyzed by molecular HNO3 rather than by H(+). The Henry's law constant and kinetics relationships measured here can be used to improve mechanisms and models of SOA formation from the oxidation of hydrocarbons in dry air in the presence of NOx, which are conditions commonly used in laboratory studies. The fate of cyclic hemiacetals in the atmosphere, where the effects of higher relative humidity, organic/aqueous phase separation, and acid catalysis by molecular H2SO4 and/or H(+) are likely to be important, is discussed.

  18. Lipase-catalyzed synthesis of fatty acid amide (erucamide) using fatty acid and urea.

    Science.gov (United States)

    Awasthi, Neeraj Praphulla; Singh, R P

    2007-01-01

    Ammonolysis of fatty acids to the corresponding fatty acid amides is efficiently catalysed by Candida antartica lipase (Novozym 435). In the present paper lipase-catalysed synthesis of erucamide by ammonolysis of erucic acid and urea in organic solvent medium was studied and optimal conditions for fatty amides synthesis were established. In this process erucic acid gave 88.74 % pure erucamide after 48 hour and 250 rpm at 60 degrees C with 1:4 molar ratio of erucic acid and urea, the organic solvent media is 50 ml tert-butyl alcohol (2-methyl-2-propanol). This process for synthesis is economical as we used urea in place of ammonia or other amidation reactant at atmospheric pressure. The amount of catalyst used is 3 %.

  19. Synthesis, isolation and characterization of methyl levulinate from cellulose catalyzed by extremely low concentration acid

    Institute of Scientific and Technical Information of China (English)

    Hui; Li; Lincai; Peng; Lu; Lin; Keli; Chen; Heng; Zhang

    2013-01-01

    A direct synthesis of methyl levulinate from cellulose alcoholysis in methanol medium under mild condition(180 210 C)catalyzed by extremely low concentration sulfuric acid(0.01 mol/L)and the product isolation were developed in this study.Effects of different process variables towards the catalytic performance were performed as a function of reaction time.The results indicated that sulfuric acid concentration,temperature and initial cellulose concentration had significant effects on the synthesis of methyl levulinate.An optimized yield of around 50%was achieved at 210 C for 120 min with sulfuric acid concentration of 0.01 mol/L and initial cellulose concentration below 100 g/L.The resulting product mixture was isolated by a distillation technique that combines an atmospheric distillation with a vacuum distillation where n-dodecane was added to help distill the heavy fraction.The light fraction including mainly methanol could be reused as the reaction medium without any substantial change in the yield of methyl levulinate.The chemical composition and structural of lower heavy fraction were characterized by GC/MS,FTIR,1H-NMR and13C-NMR techniques.Methyl levulinate was found to be a major ingredient of lower heavy fraction with the content over 96%.This pathway is efficient,environmentally benign and economical for the production of pure levulinate esters from cellulose.

  20. Acid-Catalyzed Transesterification Reaction of Beef Tallow For Biodiesel Production By Factor Variation

    Directory of Open Access Journals (Sweden)

    R.C. Ehiri

    2014-07-01

    Full Text Available Biodiesel is a diesel grade fuel made by transesterification reaction of vegetable oils and animal fats with alcohol. Three variable factors that affect the yield of biodiesel namely, reaction time, reaction temperature and catalyst concentration were studied in this work. The biodiesel was produced via a batchprocess acid-catalyzed transesterification reaction of beef tallow with methanol. Optimal conditions for the reaction were established in a three factor two-level (23 central composite design with the biodiesel pretreatment yield as the response surface. The results show that the mean yield of biodiesel was 92.04% with a standard deviation of 5.16. An optimal biodiesel yield of 96.30% occurred at 0.5% HCl catalyst concentration and at constant conditions of 1.5h reaction time, 60oC reaction temperature and 6:1 methanol: tallow volume ratio. Gas chromatographic analysis of the beef tallow identified palmitic, stearic and oleic acids in it while the fatty acid methyl esters in the biodiesel product were oleate and linoleate. Catalysis was the most significant factor in the transesterification process.

  1. (Salen)Ti(Ⅳ)-Catalyzed Asymmetric Ring-opening of meso Epoxides Using Dithiophosphorus Acid as the Nucleophile

    Institute of Scientific and Technical Information of China (English)

    Zheng Hong ZHOU; Zhao Ming LI; Bing LIU; Kang Ying LI; Li Xin WANG; Guo Feng ZHAO; Qi Lin ZHOU; Chu Chi TANG

    2006-01-01

    The asymmetric ring-opening of epoxides with dithiophosphorus acids catalyzed by a (salen)Ti(Ⅳ) complex formed in situ from the reaction of Ti(OPr-i)4 and the chiral Schiff base derived from (1R,2R)-(+)-diaminocyclohexane was realized. The resulting products were obtained with low to good enantioselectivity (up to 73% ee).

  2. Aerobic oxidation of benzylic aldehydes to acids catalyzed by iron (Ⅲ) meso-tetraphenylporphyrin chloride under ambient conditions

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Highly efficient aerobic oxidation of benzylic aldehydes to the corresponding acids catalyzed by iron (Ⅲ) meso-tetraphenylporphyrin chloride (Fe(TPP)Cl) under ambient conditions was developed. The catalyst has been proved to be an excellent catalyst for the system in the presence of molecular oxygen and isobutryaldehyde at room temperature.

  3. Selective Synthesis of Unsaturated N-Acylethanolamines by Lipase-Catalyzed N-Acylation of Ethanolamine with Unsaturated Fatty Acids

    NARCIS (Netherlands)

    Plastina, P.; Vincken, J.P.; Gruppen, H.; Witkamp, R.F.; Gabriele, B.

    2009-01-01

    The selective synthesis of unsaturated N-acylethanolamines 1b-6b by lipase-catalyzed direct condensation between unsaturated fatty acids 1a-6a and ethanolamine is reported. Reactions were carried out in hexane at 40 °C, in the presence of Candida antarctica Lipase B as the catalyst, to give the corr

  4. Ru/Me-BIPAM-Catalyzed Asymmetric Addition of Arylboronic Acids to Aliphatic Aldehydes and α-Ketoesters

    Directory of Open Access Journals (Sweden)

    Momoko Watanabe

    2011-06-01

    Full Text Available A ruthenium-catalyzed asymmetric arylation of aliphatic aldehydes and α-ketoesters with arylboronic acids has been developed, giving chiral alkyl(arylmethanols and α-hydroxy esters in good yields. The use of a chiral bidentate phosphoramidite ligand (Me-BIPAM achieved excellent enantioselectivities.

  5. Potential of phosphoric acid-catalyzed pretreatment and subsequent enzymatic hydrolysis for biosugar production from Gracilaria verrucosa.

    Science.gov (United States)

    Kwon, Oh-Min; Kim, Sung-Koo; Jeong, Gwi-Taek

    2016-07-01

    This study combined phosphoric acid-catalyzed pretreatment and enzymatic hydrolysis to produce biosugars from Gracilaria verrucosa as a potential renewable resource for bioenergy applications. We optimized phosphoric acid-catalyzed pretreatment conditions to 1:10 solid-to-liquid ratio, 1.5 % phosphoric acid, 140 °C, and 60 min reaction time, producing a 32.52 ± 0.06 % total reducing sugar (TRS) yield. By subsequent enzymatic hydrolysis, a 68.61 ± 0.90 % TRS yield was achieved. These results demonstrate the potential of phosphoric acid to produce biosugars for biofuel and biochemical production applications.

  6. Enantioselective total synthesis of (+)-Lingzhiol via tandem semipinacol rearrangement/Friedel-Crafts type cyclization.

    Science.gov (United States)

    Chen, Dong; Xu, Wen-Dan; Liu, Hao-Miao; Li, Ming-Ming; Yan, Yong-Min; Li, Xiao-Nian; Li, Yan; Cheng, Yong-Xian; Qin, Hong-Bo

    2016-06-30

    Enantioselective total synthesis of (+)-Lingzhiol has been achieved. It is the first example of in tandem semipinacol rearrangement reactions, the migrated aryl group further reacting with the carbonyl oxonium electrophile to furnish a polycyclic skeleton. Our synthesis involves 13 steps and proceeds in 6% overall yield. PMID:27321202

  7. Microwave-assisted facile and rapid Friedel-Crafts benzoylation of arenes catalysed by bismuth trifluoromethanesulfonate

    DEFF Research Database (Denmark)

    Tran, Phoung Hoang; Hansen, Poul Erik; Pham, Thuy Than;

    2014-01-01

    The catalytic activity of metal triflates was investigated in Friedel–Crafts benzoylation under microwave irradiation. Friedel–Crafts benzoylation with benzoyl chloride of a variety of arenes containing electron-rich and electron-poor rings using bismuth triflate under microwave irradiation is...

  8. Mechanistic insights into a BINOL-derived phosphoric acid-catalyzed asymmetric Pictet-Spengler reaction.

    Science.gov (United States)

    Overvoorde, Lois M; Grayson, Matthew N; Luo, Yi; Goodman, Jonathan M

    2015-03-01

    The reaction of tryptamine and (2-oxocyclohexyl)acetic acid can be catalyzed by 3,3'-bis(triphenylsilyl)-1,1'-bi-2-naphthol phosphoric acid to give an asymmetric β-carboline. This reaction was first studied by Holloway et al. ( Org. Lett. 2010 , 12 , 4720 - 4723 ), but their mechanistic work did not explain the high stereoselectivity achieved. This study uses density functional theory and hybrid quantum mechanics/molecular mechanics calculations to investigate this reaction and provide a model to explain its outcome. The step leading to diastereo- and enantioselectivity is an asymmetric Pictet-Spengler reaction involving an N-acyliminium ion bound to the catalyst in a bidentate fashion. This interaction occurs via hydrogen bonds between the two terminal oxygen atoms of the catalyst phosphate group and the hydrogen atoms at N and C2 of the substrate indole group. These bonds hold the transition structure rigidly and thus allow the catalyst triphenylsilyl groups to influence the enantioselectivity. PMID:25654215

  9. Brönsted Acid of Keggin Type Polyoxometalate Catalyzed Pinacol Rearrangement

    Directory of Open Access Journals (Sweden)

    Aldes Lesbani

    2014-07-01

    Full Text Available Keggin type polyoxometalates K4[a-SiW12O40] was synthesized and transformed to H4[a-SiW12O40]. Both catalysts have been used for pinacol rearrangement in toluene at 373 oK. The results showed that reaction of pinacol rearrangement did not proceed using K4[a-SiW12O40] as catalyst. The extent reac-tion time until 20 h also did not produce pinacolone as main product. By using H4[a-SiW12O40] as cata-lyst at 1 h reaction time gave conversion 100% with formation of pinacolone 72%. The reaction produce 27% of 2,3-dimethyl-1,3-butadiene as byproduct and 99% carbon balance for the reaction. This phe-nomenon indicated the Brönsted acid is a key role for catalytic reaction of pinacol rearrangement to pinacolone. © 2014 BCREC UNDIP. All rightsSubmitted: 21st January 2014; Revised: 21st April 2014; Accepted: 3rd May 2014[ How to Cite: Lesbani, A., Mohadi, R., (2014. Brönsted Acid of Keggin Type Polyoxometalate Catalyzed Pinacol Rearrangement. Bulletin of Chemical Reaction Engineering & Catalysis, 9 (2: 136-141. (doi:10.9767/bcrec.9.2.6074.136-141 ][ Permalink/DOI: http://dx.doi.org/10.9767/bcrec.9.2.6074.136-141

  10. Hetropolyacid-Catalyzed Oxidation of Glycerol into Lactic Acid under Mild Base-Free Conditions.

    Science.gov (United States)

    Tao, Meilin; Yi, Xiaohu; Delidovich, Irina; Palkovits, Regina; Shi, Junyou; Wang, Xiaohong

    2015-12-21

    Lactic acid (LA) is a versatile platform molecule owing to the opportunity to transform this compound into useful chemicals and materials. Therefore, efficient production of LA based on inexpensive renewable feedstocks is of utmost importance for insuring its market availability. Herein, we report the efficient conversion of glycerol into LA catalyzed by heteropolyacids (HPAs) under mild base-free conditions. The catalytic performance of molecular HPAs appears to correlate with their redox potential and Brønsted acidity. Namely, H3 PMo(12)O(40) (HPMo) exhibits the best selectivity towards LA (90 %) with 88 % conversion of glycerol. Loading of HPMo onto a carbon support (HPMo/C) further improves LA productivity resulting in 94 % selectivity at 98 % conversion under optimized reaction conditions. The reaction takes place through the formation of dihydroxyacetone/glyceraldehyde and pyruvaldehyde as intermediates. No leaching of HPMo was observed under the applied reaction conditions and HPMo/C could be recycled 5 times without significant loss of activity. PMID:26611678

  11. Origins of stereoselectivities in chiral phosphoric acid catalyzed allylborations and propargylations of aldehydes.

    Science.gov (United States)

    Wang, Hao; Jain, Pankaj; Antilla, Jon C; Houk, K N

    2013-02-01

    The chiral BINOL-phosphoric acid catalyzed allylboration and propargylation reactions are studied with density functional theory (B3LYP and B3LYP-D3). Two different models were recently proposed for these reactions by Goodman and our group, respectively. In Goodman's model for allylborations, the catalyst interacts with the boronate pseudoaxial oxygen. By contrast, our model for propargylations predicts that the catalyst interacts with the boronate pseudoequatorial oxygen. In both models, the phosphoric acid stabilizes the transition state by forming a strong hydrogen bond with the oxygen of the boronate and is oriented by a formyl hydrogen bond (Goodman model) and by other electrostatic attractions in our model. Both of these models have now been reinvestigated for both allylborations and propargylations. For the most effective catalyst for these reactions, the lowest energy transition state corresponds to Goodman's axial model, while the best transition state leading to the minor enantiomer involves the equatorial model. The high enantioselectivity observed with only the bulkiest catalyst arises from the steric interactions between the substrates and the bulky groups on the catalyst, and the resulting necessity for distortion of the catalyst in the disfavored transition state. PMID:23298338

  12. Glycolic acid-catalyzed deamidation of asparagine residues in degrading PLGA matrices: a computational study.

    Science.gov (United States)

    Manabe, Noriyoshi; Kirikoshi, Ryota; Takahashi, Ohgi

    2015-03-31

    Poly(lactic-co-glycolic acid) (PLGA) is a strong candidate for being a drug carrier in drug delivery systems because of its biocompatibility and biodegradability. However, in degrading PLGA matrices, the encapsulated peptide and protein drugs can undergo various degradation reactions, including deamidation at asparagine (Asn) residues to give a succinimide species, which may affect their potency and/or safety. Here, we show computationally that glycolic acid (GA) in its undissociated form, which can exist in high concentration in degrading PLGA matrices, can catalyze the succinimide formation from Asn residues by acting as a proton-transfer mediator. A two-step mechanism was studied by quantum-chemical calculations using Ace-Asn-Nme (Ace = acetyl, Nme = NHCH3) as a model compound. The first step is cyclization (intramolecular addition) to form a tetrahedral intermediate, and the second step is elimination of ammonia from the intermediate. Both steps involve an extensive bond reorganization mediated by a GA molecule, and the first step was predicted to be rate-determining. The present findings are expected to be useful in the design of more effective and safe PLGA devices.

  13. Cooperative Effects Between Arginine and Glutamic Acid in the Amino Acid-Catalyzed Aldol Reaction.

    Science.gov (United States)

    Valero, Guillem; Moyano, Albert

    2016-08-01

    Catalysis of the aldol reaction between cyclohexanone and 4-nitrobenzaldehyde by mixtures of L-Arg and of L-Glu in wet dimethyl sulfoxide (DMSO) takes place with higher enantioselectivity (up to a 7-fold enhancement in the anti-aldol for the 1:1 mixture) than that observed when either L-Glu or L-Arg alone are used as the catalysts. These results can be explained by the formation of a catalytically active hydrogen-bonded complex between both amino acids, and demonstrate the possibility of positive cooperative effects in catalysis by two different α-amino acids. Chirality 28:599-605, 2016. © 2016 Wiley Periodicals, Inc. PMID:27362554

  14. Intramolecular hydroarylation of aryl propargyl ethers catalyzed by indium: the mechanism of the reaction and identifying the catalytic species.

    Science.gov (United States)

    Menkir, Mengistu Gemech; Lee, Shyi-Long

    2016-07-01

    The mechanism and regioselectivity of the intramolecular hydroarylation of phenyl propargyl ether catalyzed by indium in gas and solvent phases were investigated by means of the density functional theory method. The computed results revealed that the reaction proceeds through initial π-coordination of the propargyl moiety to the catalyst, which triggers the nucleophilic attack of the phenyl ring via an exo- or endo-dig pathway in a Friedel-Crafts type mechanism. Calculation results obtained employing InI2(+) as the possible catalyst show similar activation energies for the 5-exo-dig and 6-endo-dig pathways. In contrast, the neural catalyst InI3 shows a kinetic preference for 6-endo-dig versus 5-exo-dig cyclizations leading to the experimentally observed product, 2H-chromene. The calculation results suggest that InI3 could be the real catalytic species for this reaction as it shows regioselectivity in agreement with the experimental observation. Furthermore, the 6-endo-dig cyclization through deprotonation/protonation steps is kinetically more favored than the stepwise two consecutive [1,2]-H shift steps. The rate determining step of the whole catalytic cycle is the deprotonation step with an energy barrier of 18.9 kcal mol(-1) in toluene solvent. The effects of substituents on both the phenyl ring and the propargyl moiety on the selectivity and elementary steps of the hydroarylation process were investigated. A methoxy group, particularly at the meta-position, on the phenyl ring largely decreases the energy barrier of the first step for the 6-endo path, though it shows little effect on the activation energies of the second and third steps. Our calculation results are in good agreement with the experimental results. PMID:27298068

  15. Kinetics of Acid-Catalyzed Dehydration of Cyclic Hemiacetals in Organic Aerosol Particles in Equilibrium with Nitric Acid Vapor.

    Science.gov (United States)

    Ranney, April P; Ziemann, Paul J

    2016-04-28

    Previous studies have shown that 1,4-hydroxycarbonyls, which are often major products of the atmospheric oxidation of hydrocarbons, can undergo acid-catalyzed cyclization and dehydration in aerosol particles to form highly reactive unsaturated dihydrofurans. In this study the kinetics of dehydration of cyclic hemiacetals, the rate-limiting step in this process, was investigated in a series of environmental chamber experiments in which secondary organic aerosol (SOA) containing cyclic hemiacetals was formed from the reaction of n-pentadecane with OH radicals in dry air in the presence of HNO3. A particle beam mass spectrometer was used to monitor the formation and dehydration of cyclic hemiacetals in real time, and SOA and HNO3 were quantified in filter samples by gravimetric analysis and ion chromatography. Measured dehydration rate constants increased linearly with increasing concentration of HNO3 in the gas phase and in SOA, corresponding to catalytic rate constants of 0.27 h(-1) ppmv(-1) and 7.0 h(-1) M(-1), respectively. The measured Henry's law constant for partitioning of HNO3 into SOA was 3.7 × 10(4) M atm(-1), ∼25% of the value for dissolution into water, and the acid dissociation constant was estimated to be <8 × 10(-4), at least a factor of 10(4) less than that for HNO3 in water. The results indicate that HNO3 was only weakly dissociated in the SOA and that dehydration of cyclic hemiacetals was catalyzed by molecular HNO3 rather than by H(+). The Henry's law constant and kinetics relationships measured here can be used to improve mechanisms and models of SOA formation from the oxidation of hydrocarbons in dry air in the presence of NOx, which are conditions commonly used in laboratory studies. The fate of cyclic hemiacetals in the atmosphere, where the effects of higher relative humidity, organic/aqueous phase separation, and acid catalysis by molecular H2SO4 and/or H(+) are likely to be important, is discussed. PMID:27043733

  16. Ion-exchange Resin Catalyzed Esterification of Lactic Acid with Isopropanol: a Kinetic Study

    Directory of Open Access Journals (Sweden)

    Amrit P. Toor

    2011-05-01

    Full Text Available The kinetic behavior of esterification of lactic acid with isopropanol over an acidic cation exchange resin, Amberlyst 15, was studied under isothermal condition. Isopropyl lactate synthesized in this reaction is an important pharmaceutical intermediate. The experiments were carried out in a stirred batch reactor in the temperature range of 323.15 to 353.15 K. The effect of various parameters such as temperature, molar ratio and catalyst loading was studied. Variation in parameters on rate of reaction demonstrated that the reaction was intrinsically controlled. Kinetic modeling was performed using Eley-Rideal model which acceptably fits the experimental data. The activation energy was found to be 22.007 kJ/mol and frequency factor was 0.036809 l2 g-1 mol-1 min-1 for forward reaction. The value of entropy for the forward reaction was found to be 182.317 J K-1 mol-1 . © 2011 BCREC UNDIP. All rights reserved(Received: 19th January 2011, Revised: 16th March 2011; Accepted: 16th March 2011[How to Cite: A.P. Toor, M. Sharma, S. Thakur, and R. K. Wanchoo. (2011. Ion-exchange Resin Catalyzed Esterification of Lactic Acid with Isopropanol: a Kinetic Study. Bulletin of Chemical Reaction Engineering and Catalysis, 6(1: 39-45. doi:10.9767/bcrec.6.1.791.39-45][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.6.1.791.39-45 || or local:  http://ejournal.undip.ac.id/index.php/bcrec/article/view/791 ] | View in  

  17. Catalytic, Interrupted Formal Homo-Nazarov Cyclization with (Hetero)arenes: Access to α-(Hetero)aryl Cyclohexanones.

    Science.gov (United States)

    Williams, Corey W; Shenje, Raynold; France, Stefan

    2016-09-16

    The first examples of a Lewis-acid catalyzed (hetero)arene interrupted, formal homo-Nazarov cyclization have been disclosed. Using SnCl4 as the catalyst, alkenyl cyclopropyl ketones undergo ring-opening cyclization to form six-membered cyclic oxyallyl cations. Subsequent intermolecular Friedel-Crafts-type arylation with various electron-rich arenes and heteroarenes provides functionalized α-(hetero)arylated cyclohexanones, a scaffold present in many natural products and bioactive compounds, in yields up to 88% and diastereomeric ratios up to 12:1. Regiospecific arylation occurs at the α-carbon of the oxyallyl cation due to polarization caused by the ester group. PMID:27529123

  18. Lipase-catalyzed Synthesis of Caffeic Acid Phenethyl Ester in Ionic Liquids:Effect of Specific Ions and Reaction Parameters

    Institute of Scientific and Technical Information of China (English)

    王俊; 李晶; 张磊霞; 顾双双; 吴福安

    2013-01-01

    Caffeic acid phenethyl ester (CAPE) is a rare, naturally occurring phenolic food additive. This work systematically reported fundamental data on conversion of caffeic acid (CA), yield of CAPE, and reactive selectiv-ity during the lipase-catalyzed esterification process of CA and phenylethanol (PE) in ionic liquids (ILs). Sixteen ILs were selected as the reaction media, and the relative lipase-catalyzed synthesis properties of CAPE were meas-ured in an effort to enhance the yield of CAPE with high selectivity. The results indicated that ILs containing weakly coordinating anions and cations with adequate alkyl chain length improved the synthesis of CAPE. [Emim][Tf2N] was selected as the optimal reaction media. The optimal parameters were as follows by response surface methodology (RSM):reaction temperature, 84.0 °C;mass ratio of Novozym 435 to CA, 14︰1;and molar ratio of PE to CA, 16︰1. The highest reactive selectivity of CAPE catalyzed by Novozym 435 in [Emim][Tf2N] reached 64.55%(CA conversion 98.76%and CAPE yield 63.75%, respectively). Thus, lipase-catalyzed esterifica-tion in ILs is a promising method suitable for CAPE production.

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

    Science.gov (United States)

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

    2015-04-20

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

  20. A heteromeric membrane-bound prenyltransferase complex from hop catalyzes three sequential aromatic prenylations in the bitter acid pathway.

    Science.gov (United States)

    Li, Haoxun; Ban, Zhaonan; Qin, Hao; Ma, Liya; King, Andrew J; Wang, Guodong

    2015-03-01

    Bitter acids (α and β types) account for more than 30% of the fresh weight of hop (Humulus lupulus) glandular trichomes and are well known for their contribution to the bitter taste of beer. These multiprenylated chemicals also show diverse biological activities, some of which have potential benefits to human health. The bitter acid biosynthetic pathway has been investigated extensively, and the genes for the early steps of bitter acid synthesis have been cloned and functionally characterized. However, little is known about the enzyme(s) that catalyze three sequential prenylation steps in the β-bitter acid pathway. Here, we employed a yeast (Saccharomyces cerevisiae) system for the functional identification of aromatic prenyltransferase (PT) genes. Two PT genes (HlPT1L and HlPT2) obtained from a hop trichome-specific complementary DNA library were functionally characterized using this yeast system. Coexpression of codon-optimized PT1L and PT2 in yeast, together with upstream genes, led to the production of bitter acids, but no bitter acids were detected when either of the PT genes was expressed by itself. Stepwise mutation of the aspartate-rich motifs in PT1L and PT2 further revealed the prenylation sequence of these two enzymes in β-bitter acid biosynthesis: PT1L catalyzed only the first prenylation step, and PT2 catalyzed the two subsequent prenylation steps. A metabolon formed through interactions between PT1L and PT2 was demonstrated using a yeast two-hybrid system, reciprocal coimmunoprecipitation, and in vitro biochemical assays. These results provide direct evidence of the involvement of a functional metabolon of membrane-bound prenyltransferases in bitter acid biosynthesis in hop. PMID:25564559

  1. Manganese(II) catalyzes the bicarbonate-dependent oxidation of amino acids by hydrogen peroxide and the amino acid-facilitated dismutation of hydrogen peroxide.

    OpenAIRE

    Berlett, B S; Chock, P B; Yim, M B; Stadtman, E. R.

    1990-01-01

    In bicarbonate/CO2 buffer, Mn(II) and Fe(II) catalyze the oxidation of amino acids by H2O2 and the dismutation of H2O2. As the Mn(II)/Fe(II) ratio is increased, the yield of carbonyl compounds per mole of leucine oxidized is essentially constant, but the ratio of alpha-ketoisocaproate to isovaleraldehyde formed increases, and the fraction of H2O2 converted to O2 increases. In the absence of Fe(II), the rate of Mn(II)-catalyzed leucine oxidation is directly proportional to the H2O2, Mn(II), an...

  2. 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.

  3. Probing the "additive effect" in the proline and proline hydroxamic acid catalyzed asymmetric addition of nitroalkanes to cyclic enones.

    Science.gov (United States)

    Hanessian, Stephen; Govindan, Subramaniyan; Warrier, Jayakumar S

    2005-11-01

    The effect of chirality and steric bulk of 2,5-disubstituted piperazines as additives in the conjugate addition of 2-nitropropane to cyclohexenone, catalyzed by l-proline, was investigated. Neither chirality nor steric bulk affects the enantioselectivity of addition, which gives 86-93% ee in the presence of achiral and chiral nonracemic 2,5-disubstituted piperazines. Proline hydroxamic acid is shown for the first time to be an effective organocatalyst in the same Michael reaction. PMID:16189834

  4. Tandem Suzuki-Miyaura coupling/acid-catalyzed cyclization between vinyl ether boronates and vinyl halides: a concise approach to polysubstituted furans.

    Science.gov (United States)

    Butkevich, Alexey N; Meerpoel, Lieven; Stansfield, Ian; Angibaud, Patrick; Corbu, Andrei; Cossy, Janine

    2013-08-01

    Polysubstituted 2-(ω-hydroxyalkyl)furans were prepared by tandem Suzuki-Miyaura coupling/acid-catalyzed cyclization starting from appropriately substituted 3-haloallylic alcohols and dihydrofuran-, dihydropyran- or glycal-derived pinacol boronates. PMID:23855589

  5. Acid-catalyzed conversion of mono- and poly-sugars into platform chemicals: effects of molecular structure of sugar substrate.

    Science.gov (United States)

    Hu, Xun; Wu, Liping; Wang, Yi; Song, Yao; Mourant, Daniel; Gunawan, Richard; Gholizadeh, Mortaza; Li, Chun-Zhu

    2013-04-01

    Hydrolysis/pyrolysis of lignocellulosic biomass always produces a mixture of sugars with distinct structures as intermediates or products. This study tried to elucidate the effects of molecular structure of sugars on their acid-catalyzed conversions in ethanol/water. Location of carbonyl group in sugars (fructose versus glucose) and steric configuration of hydroxyl groups (glucose versus galactose) significantly affected yields of levulinic acid/ester (fructose>glucose>galactose). The dehydration of fructose to 5-(hydroxymethyl)furfural produces much less soluble polymer than that from glucose and galactose, which results in high yields of levulinic acid/ester from fructose. Anhydrate sugar such as levoglucosan tends to undergo the undesirable decomposition to form less levulinic acid/ester. Catalytic behaviors of the poly-sugars (sucrose, maltose, raffinose, β-cyclodextrins) were determined much by their basic units. However, their big molecular sizes create the steric hindrance that significantly affects their followed conversion over solid acid catalyst. PMID:23454803

  6. The Formation of Pyrroline and Tetrahydropyridine Rings in Amino Acids Catalyzed by Pyrrolysine Synthase (PylD)

    KAUST Repository

    Quitterer, Felix

    2014-06-10

    The dehydrogenase PylD catalyzes the ultimate step of the pyrrolysine pathway by converting the isopeptide L-lysine-Nε-3R-methyl-D-ornithine to the 22nd proteinogenic amino acid. In this study, we demonstrate how PylD can be harnessed to oxidize various isopeptides to novel amino acids by combining chemical synthesis with enzyme kinetics and X-ray crystallography. The data enable a detailed description of the PylD reaction trajectory for the biosynthesis of pyrroline and tetrahydropyridine rings as constituents of pyrrolysine analogues. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Iron-Catalyzed, Highly Regioselective Synthesis of alpha-Aryl Carboxylic Acids from Styrene Derivatives and CO2

    OpenAIRE

    Greenhalgh, Mark D.; Thomas, Stephen P.

    2012-01-01

    The iron-catalyzed hydrocarboxylation of aryl alkenes has been developed using a highly active bench-stable iron(II) precatalyst to give alpha-aryl carboxylic acids in excellent yields and with near-perfect regioselectivity. Using just 1 mol % FeCl2, bis(imino)pyridine 6 (1 mol %), CO2 (atmospheric pressure), and a hydride source (EtMgBr, 1.2 equiv), a range of sterically and electronically differentiated aryl alkenes were transformed to the corresponding alpha-aryl carboxylic acids (up to 96...

  8. Iodine-Catalyzed Decarboxylative Amidation of β,γ-Unsaturated Carboxylic Acids with Chloramine Salts Leading to Allylic Amides.

    Science.gov (United States)

    Kiyokawa, Kensuke; Kojima, Takumi; Hishikawa, Yusuke; Minakata, Satoshi

    2015-10-26

    The iodine-catalyzed decarboxylative amidation of β,γ-unsaturated carboxylic acids with chloramine salts is described. This method enables the regioselective synthesis of allylic amides from various types of β,γ-unsaturated carboxylic acids containing substituents at the α- and β-positions. In the reaction, N-iodo-N-chloroamides, generated by the reaction of a chloramine salt with I2 , function as a key active species. The reaction provides an attractive alternative to existing methods for the synthesis of useful secondary allylic amine derivatives. PMID:26493878

  9. Palladium(II-catalyzed Heck reaction of aryl halides and arylboronic acids with olefins under mild conditions

    Directory of Open Access Journals (Sweden)

    Tanveer Mahamadali Shaikh

    2013-08-01

    Full Text Available A series of general and selective Pd(II-catalyzed Heck reactions were investigated under mild reaction conditions. The first protocol has been developed employing an imidazole-based secondary phosphine oxide (SPO ligated palladium complex (6 as a precatalyst. The catalytic coupling of aryl halides and olefins led to the formation of the corresponding coupled products in excellent yields. A variety of substrates, both electron-rich and electron-poor olefins, were converted smoothly to the targeted products in high yields. Compared with the existing approaches employing SPO–Pd complexes in a Heck reaction, the current strategy features mild reaction conditions and broad substrate scope. Furthermore, we described the coupling of arylboronic acids with olefins, which were catalyzed by Pd(OAc2 and employed N-bromosuccinimide as an additive under ambient conditions. The resulted biaryls have been obtained in moderate to good yields.

  10. Pd-catalyzed ethylene methoxycarbonylation with Brønsted acid ionic liquids as promoter and phase-separable reaction media

    DEFF Research Database (Denmark)

    Garcia-Suarez, Eduardo J.; Khokarale, Santosh Govind; Nguyen van Buu, Olivier;

    2014-01-01

    Brønsted acid ionic liquids (BAILs) were prepared and applied as combined acid promoters and reaction media in Pd–phosphine catalyzed methoxycarbonylation of ethylene to produce methyl propionate. The BAILs served as alternatives to common mineral acids required for the reaction, e.g. methanesulf...

  11. Practical synthesis of enantiomerically pure beta2-amino acids via proline-catalyzed diastereoselective aminomethylation of aldehydes.

    Science.gov (United States)

    Chi, Yonggui; English, Emily P; Pomerantz, William C; Horne, W Seth; Joyce, Leo A; Alexander, Lane R; Fleming, William S; Hopkins, Elizabeth A; Gellman, Samuel H

    2007-05-01

    Proline-catalyzed diastereoselective aminomethylation of aldehydes using a chiral iminium ion, generated from a readily prepared precursor, provides alpha-substituted-beta-amino aldehydes with 85:15 to 90:10 dr. The alpha-substituted-beta-amino aldehydes can be reduced to beta-substituted-gamma-amino alcohols, the major diastereomer of which can be isolated via crystallization or column chromatography. The amino alcohols are efficiently transformed to protected beta2-amino acids, which are valuable building blocks for beta-peptides, natural products, and other interesting molecules. Because conditions for the aminomethylation and subsequent reactions are mild, beta2-amino acid derivatives with protected functional groups in the side chain, such as beta2-homoglutamic acid, beta2-homotyrosine, and beta2-homolysine, can be prepared in this way. The synthetic route is short, and purifications are simple; therefore, this method enables the preparation of protected beta2-amino acids in useful quantities.

  12. Recent Progress in Metal-Catalyzed Reactions of 2(5H)-Furanones%金属催化的2(5H)-呋喃酮反应研究进展

    Institute of Scientific and Technical Information of China (English)

    毛超旭; 汪朝阳; 谭越河; 薛福玲

    2011-01-01

    2(5H)-呋喃酮结构单元广泛存在于天然产物中,同时许多2(5H)-呋喃酮类化合物也是重要的有机合成中间体.因此,基于常见2(5H)-呋喃酮的有机合成研究近年来引起了人们的关注,尤其是金属催化的2(5H)-呋喃酮反应的地位日趋彰显重要,从而成为众多化学工作者的研究热点.按照反应类型的不同,对近年来金属催化的2(5H)-呋喃酮反应的研究进展进行了综述,主要包括Sonogashira,Suzuki,Stille等偶联反应,以及Michael加成反应、Friedel-Crafts烷基化反应、Baylis-Hillman反应、亲核取代反应、还原反应等.%The unique carbon skeleton of 2(5H)-furanone is widely present in a variety of natural products, and many compounds containing 2(5H)-furanone skeleton are important synthetic intermediates. Recently, more and more attentions have been attracted to the organic synthesis based on 2(5H)-furanones, especially via the metal-catalyzed reactions of 2(5H)-furanones. Classified as different types, the recent progress in metal-catalyzed reactions of 2(5H)-furanones, mainly including Sonogashira reaction, Suzuki reaction, Stille reaction, Michael addition, Friedel-Crafts alkylation, Baylis-Hillman reaction, nucleophilic substitution, and reduction reaction, is reviewed in this paper.

  13. (+)-Tartaric Acid-Catalyzed High Regio- and Stereoselective Aminobromination of Olefins%(+)-Tartaric Acid-Catalyzed High Regio- and Stereoselective Aminobromination of Olefins

    Institute of Scientific and Technical Information of China (English)

    陈战国; 魏俊发; 李文丽; 王芸; 赵朋飞; 石先莹

    2011-01-01

    (+)-Tartaric acid-catalyzed aminobromination of α,β-unsaturated ketones, α,β-unsaturated esters and simple olefins utilizing TsNHJNBS as the nitrogen/halogen sources at room temperature without protection of inert gases achieved good yields (up to 92% yield) of vicinal haloamino products with excellent regio- and stereoselectivity, even just 10% of (+)-tartaric acid was used as catalyst. The regio- and stereochemistry was unambiguously confirmed by X-ray structural analysis of products 2b and 12e. The electron-rich and deficient olefins show significant differences in activity to the aminobromination reaction and give the opposite regioselectivities. The 21 cases have been investigated which indicated that our protocol has the advantage of a large scope of olefins. Additionally, tartaric acid as catalyst has the advantage of avoiding any hazardous metals retained in products.

  14. Preparation of highly conjugated water-dispersible graphene-butyric acid for the enhancement of electron transfer within polyamic acid-benzoxazole: potential applications in electrochemical sensing.

    Science.gov (United States)

    Chen, Hsiao-Chien; Chen, Yen-Hsuan; Chen, Shi-Liang; Chern, Yaw-Terng; Tsai, Rung-Ywan; Hua, Mu-Yi

    2013-08-15

    To break through the long time and complex procedures for the preparation of highly conjugated reduced graphene oxide (r-GO) in developing electrochemical sensor, a time-saving and simple method is investigated in this study. One novel step of the exfoliated accompanying carboxylated graphene sheet from pristine is achieved via Friedel-Crafts acylation. By electrophilic aromatic substitution, the succinic anhydride ring is opened and attaches covalently to the graphene sheet (Gs) to form exfoliated graphene with grafted 1-one-butyric acid (Gs-BA). The grafting chain converts anions in aqueous solution to maintain Gs-BA in a stable dispersion and noticeably decreases the π-π stacking of the exfoliated Gs during the drying process. The analytical results of the absorption spectroscopy demonstrate that the conjugation of Gs-BA is not significantly destroyed by this chemical modification; Gs-BA retains the Gs electrical properties favorable for developing electrochemical sensors. When polyamic acid-benzoxazole (PAA-BO), a hydrogen peroxide (H₂O₂)-sensitive probe, hybridizes with Gs-BA to form Gs-BA-PAA-BO, the electron transfer rate relating to the response time improves markedly from 1.09 s(-1) to 38.8 s(-1). Additionally, it offers a high performance for H₂O₂ sensing in terms of sensitivity and response time, making this method applicable for developing glucose and choline biosensors.

  15. Influence of organic acids on oscillations and waves in the ferroin-catalyzed Belousov-Zhabotinsky reaction

    Science.gov (United States)

    Krüger, Frank; Nagy-Ungvárai, Zsuzsanna; Müller, Stefan C.

    Experiments of the influence of mesoxalic and tartronic acid on the oscillatory behavior and on the spiral tip motion in a ferroin-catalyzed Belousov-Zhabotinsky (BZ) solution are reported. The oscillations were observed in batch and CSTR systems, and for the investigations of the spiral tip motion an open gel reactor was used. A characteristic shoulder in the oscillations is associated with an additional Br - production phase. The chemical parameters for a transition from a hypocycloidal to a circular tip trajectory are found. The findings are compared with the temporal and spatial dynamic behavior, occurring during the ageing process of the solution.

  16. High fluorescence emission of carboxylic acid functionalized polystyrene/BaTiO{sub 3} nanocomposites and rare earth metal complexes: Preparation and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Cao, X. T.; Showkat, A. M.; Wang, Z.; Lim, K. T., E-mail: ktlim@pknu.ac.kr [Department of Imaging System Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of)

    2015-03-30

    Noble fluorescence nanocomposite compound based on barium titanate nanoparticles (BTO), polystyrene (PSt), and terbium ion (Tb{sup 3+}) was synthesized by a combination of surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization, Friedel-Crafts alkylation reaction and coordinate chemistry. Initially, a modification of surface of BTO was conducted by an exchange process with S-benzyl S’-trimethoxysilylpropyltrithiocarbonate to create macro-initiator for polymerization of styrene. Subsequently, aryl carboxylic acid functionalized polystyrene grafted barium titanate (BTO-g-PSt-COOH) was generated by substitution reaction between 4-(Chloromethyl) benzoic acid and PSt chains. The coordination of the nanohybrids with Tb{sup 3+} ions afforded fluorescent Tb{sup 3+} tagged aryl carboxylic acid functionalized polystyrene grafted barium titanate (BTO-g-PSt-Tb{sup 3+}) complexes. Structure, morphology, and fluorescence properties of nanohybrid complexes were investigated by respective physical and spectral studies. FT-IR and SEM analyses confirmed the formation of BTO-g-PSt-Tb{sup 3+}nanohybrids. Furthermore, TGA profiles demonstrated the grafting of aryl carboxylic acid functionalized polystyrene on BTO surface. Optical properties of BTO-g-PSt-Tb{sup 3+} complexes were investigated by fluorescence spectroscopy.

  17. An Efficient Synthesis of 1-Alkyl-2-phenyl-4-quinolones from 2-Halobenzoic Acids

    Energy Technology Data Exchange (ETDEWEB)

    Song, Yoon Ju; Choi, Jin Sun; Lee, Jae In [Duksung Women' s Univ., Seoul (Korea, Republic of)

    2013-10-15

    The present method offers an efficient synthesis of 1-alkyl-2-phenyl-4-quinolones from 2-haloben-zoic acids. It has the advantages with respect to (i) synthesis of 2 equiv of alkynones 5 from 1 equiv of 4,6-pyrimidyl di(2-halobenzoates) 3, (ii) synthesis of versatile 1-alkyl-2-phenyl-4-quinolones in high overall yields, and (iii) use of readily available and cheap starting materials. Therefore, this method could be utilized as a practical synthesis of 1-alkyl-2-phenyl-4-quinolones. Several methods have been developed to synthesize 1-alkyl-2-phenyl-4-quinolones from 2'-substituted acetophenones, anilines, and 2-halobenzoyl chlorides as starting materials. The reaction of N-methylisatoic anhydride with the lithium enolate of an 4'-methoxyacetophenone afforded the 1-methyl-2-phenyl-4-quinolone in a short sequence, but the yield was low. N-(2-Acetylphenyl)benzamides, prepared by Friedel-Crafts acylation of N-phenyl benzamides with acetyl chloride or benzoylation of 2'-aminoacetophenones with benzoyl chlorides,8 were cyclized with potassium t-butoxide to yield 2-aryl-4-quinolones, which were further alkylated with alkyl iodides to give 1-alkyl-2-aryl-4-quinolones.

  18. Pd-Catalyzed Coupling of γ-C(sp(3))-H Bonds of Oxalyl Amide-Protected Amino Acids with Heteroaryl and Aryl Iodides.

    Science.gov (United States)

    Han, Jian; Zheng, Yongxiang; Wang, Chao; Zhu, Yan; Huang, Zhi-Bin; Shi, Da-Qing; Zeng, Runsheng; Zhao, Yingsheng

    2016-07-01

    Pd-catalyzed regioselective coupling of γ-C(sp(3))-H bonds of oxalyl amide-protected amino acids with heteroaryl and aryl iodides is reported. A wide variety of iodides are tolerated, giving the corresponding products in moderate to good yields. Various oxalyl amide-protected amino acids were compatible in this C-H transformation, thus representing a practical method for constructing non-natural amino acid derivatives. PMID:27286881

  19. Catalytic Synthesis of 4- Hydroxy-3-methyl Ethyl Ketone by Poly Phosphoric Acid%多聚磷酸催化合成4-羟基-3-甲氧基苯乙酮的实验研究

    Institute of Scientific and Technical Information of China (English)

    郗伟

    2016-01-01

    4-羟基-3-甲氧基苯乙酮是一种非常重要的化工原料,可用来生产食品添加,制备香料、合成多种药品,在造纸工业中用来合成邻醌型木质素模型物。邻甲氧基苯酚乙酰化合成4-羟基-3-甲氧基苯乙酮的反应属于傅列德尔-克拉夫茨(Friedel-Crafts)酰基化反应,传统的催化剂是 AlCl3,但是 AlCl3作为催化剂自身有很多难以克服的缺点。通过对乙酰化反应催化剂(路易斯酸或质子酸)的分析探讨,研究表明,多聚磷酸(PPA)在温和的催化条件下,具有不易水解酯类化合物、对乙酰基化反应尤其对芳香烃类酯化反应的催化活性好、副反应少、目标产物易于分离等优点。以多聚磷酸 PPA 为催化剂,通过实验分析判别出了该合成工艺的最佳催化剂用量、反应温度、反应时间和原料摩尔比。%4-Hydroxy-3-methoxy-acetophenone is an important organic chemical raw material, and can be used to produce food additives, perfume, various intermediates of pesticides, pharmaceuticals, and so on. Synthesis reaction of 4-hydroxy-3-methoxy-acetophenone by guaiacol acetylation belongs to Friedel-Crafts acylation reaction, conventional catalyst is AlCl3, but AlCl3 catalyst has many insurmountable drawbacks. In this paper, the acetylation catalysts (Lewis acid or a proton acid) were analyzed. The results show that, PPA catalyst has many advantages, such as mild reaction condition, high catalytic activity, and fewer side reactions and so on. At last, the best synthesis conditions including PPA catalyst dosage, reaction temperature, reaction time and molar ratio of the raw materials were determined through experiments.

  20. Determination of DNA adducts by combining acid-catalyzed hydrolysis and chromatographic analysis of the carcinogen-modified nucleobases.

    Science.gov (United States)

    Leung, Elvis M K; Deng, Kailin; Wong, Tin-Yan; Chan, Wan

    2016-01-01

    The commonly used method of analyzing carcinogen-induced DNA adducts involves the hydrolysis of carcinogen-modified DNA samples by using a mixture of enzymes, followed by (32)P-postlabeling or liquid chromatography (LC)-based analyses of carcinogen-modified mononucleotides/nucleosides. In the present study, we report the development and application of a new approach to DNA adduct analysis by combining the H(+)/heat-catalyzed release of carcinogen-modified nucleobases and the use of LC-based methods to analyze DNA adducts. Results showed that heating the carcinogen-modified DNA samples at 70 °C for an extended period of 4 to 6 h in the presence of 0.05% HCl can efficiently induce DNA depurination, releasing the intact carcinogen-modified nucleobases for LC analyses. After optimizing the hydrolysis conditions, DNA samples with C8- and N (2) -modified 2'-deoxyguanosine, as well as N (6) -modified 2'-deoxyadenosine, were synthesized by reacting DNA with 1-nitropyrene, acetaldehyde, and aristolochic acids, respectively. These samples were then hydrolyzed, and the released nucleobase adducts were analyzed using LC-based analytical methods. Analysis results demonstrated a dose-dependent release of target DNA adducts from carcinogen-modified DNA samples, indicating that the developed H(+)/heat-catalyzed hydrolysis method was quantitative. Comparative studies with enzymatic digestion method on carcinogen-modified DNA samples revealed that the two hydrolysis methods did not yield systematically different results.

  1. Influence of fatty acid on lipase-catalyzed synthesis of ascorbyl esters and their free radical scavenging capacity.

    Science.gov (United States)

    Stojanović, Marija; Carević, Milica; Mihailović, Mladen; Veličković, Dušan; Dimitrijević, Aleksandra; Milosavić, Nenad; Bezbradica, Dejan

    2015-01-01

    Fatty acid (FA) ascorbyl esters are recently emerging food, cosmetic, and pharmaceutical additives, which can be prepared in an eco-friendly way by using lipases as catalysts. Because they are amphiphilic molecules, which possess high free radical scavenging capacity, they can be applied as liposoluble antioxidants as well as emulsifiers and biosurfactants. In this study, the influence of a wide range of acyl donors on ester yield in lipase-catalyzed synthesis and ester antioxidant activity was examined. Among saturated acyl donors, higher yields and antioxidant activities of esters were achieved when short-chain FAs were used. Oleic acid gave the highest yield overall and its ester exhibited a high antioxidant activity. Optimization of experimental factors showed that the highest conversion (60.5%) in acetone was achieved with 5 g L(-1) of lipase, 50 mM of vitamin C, 10-fold molar excess of oleic acid, and 0.7 mL L(-1) of initial water. Obtained results showed that even short- and medium-chain ascorbyl esters could be synthesized with high yields and retained (or even exceeded) free radical scavenging capacity of l-ascorbic acid, indicating prospects of broadening their application in emulsions and liposomes. PMID:25224149

  2. Kinetic Study of Esterification of Acetic Acid with n-butanol and isobutanol Catalyzed by Ion Exchange Resin

    Directory of Open Access Journals (Sweden)

    Amrit Pal Toor

    2011-05-01

    Full Text Available Esters are an important pharmaceutical intermediates and very useful perfumery agents. In this study the esterification of acetic acid with n-butanol and iso-butanol over an acidic cation exchange resin, Amberlyst 15 were carried out. The effects of certain parameters such as temperature, catalyst loading, initial molar ratio between reactants on the rate of reaction were studied. The experiments were conducted in a stirred batch reactor in the temperature range of 351.15 K to 366.15K.Variation of parameters on rate of reaction demonstrated that the reaction was intrinsically controlled.The activation energy for the esterification of acetic acid with n-butanol and iso butanol is found to be 28.45 k J/mol and 23.29 kJ/mol respectively. ©2011 BCREC UNDIP. All rights reserved.(Received: 16th December 2010, Revised: 19th March 2011; Accepted: 7th April 2011[How to Cite: A.P. Toor, M. Sharma, G. Kumar, and R. K. Wanchoo. (2011. Kinetic Study of Esterification of Acetic Acid with n-butanol and isobutanol Catalyzed by Ion Exchange Resin. Bulletin of Chemical Reaction Engineering and Catalysis, 6(1: 23-30. doi:10.9767/bcrec.6.1.665.23-30][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.6.1.665.23-30 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/665 ] | View in 

  3. The Acid Hydrolysis Mechanism of Acetals Catalyzed by a Supramolecular Assembly in Basic Solution

    Energy Technology Data Exchange (ETDEWEB)

    Pluth, Michael D.; Bergman, Robert G.; Raymond, Kenneth N.

    2008-09-24

    A self-assembled supramolecular host catalyzes the hydrolysis of acetals in basic aqueous solution. The mechanism of hydrolysis is consistent with the Michaelis-Menten kinetic model. Further investigation of the rate limiting step of the reaction revealed a negative entropy of activation ({Delta}S{double_dagger} = -9 cal mol{sup -1}K{sup -1}) and an inverse solvent isotope effect (k(H{sub 2}O)/k(D{sub 2}O) = 0.62). These data suggest that the mechanism of hydrolysis that takes place inside the assembly proceeds through an A-2 mechanism, in contrast to the A-1 mechanism operating in the uncatalyzed reaction. Comparison of the rates of acetal hydrolysis in the assembly with the rate of the reaction of unencapsulated substrates reveals rate accelerations of up to 980 over the background reaction for the substrate diethoxymethane.

  4. Effect of polyvinylpyrrolidone on mesoporous silica morphology and esterification of lauric acid with 1-butanol catalyzed by immobilized enzyme

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jinyu; Zhou, Guowei, E-mail: guoweizhou@hotmail.com; Jiang, Bin; Zhao, Minnan; Zhang, Yan

    2014-05-01

    Mesoporous silica materials with a range of morphology evolution, i.e., from curved rod-shaped mesoporous silica to straight rod-shaped mesoporous silica, were successfully prepared using polyvinylpyrrolidone (PVP) and triblock copolymer as dual template. The effects of PVP molecular weight and concentration on mesoporous silica structure parameters were studied. Results showed that surface area and pore volume continuously decreased with increased PVP molecular weight. Mesoporous silica prepared with PVP K30 also possessed larger pore diameter, interplanar spacing (d{sub 100}), and cell parameter (a{sub 0}) than that prepared with PVP K15 and PVP K90. In addition, with increased PVP concentration, d{sub 100} and a{sub 0} continuously decreased. The mechanism of morphology evolution caused by the change in PVP concentration was investigated. The conversion rate of lauric acid with 1-butanol catalyzed by immobilized Porcine pancreatic lipase (PPL) was also evaluated. Results showed that PPL immobilized on amino-functionalized straight rod-shaped mesoporous silica maintained 50% of its esterification conversion rate even after five cycles of use with a maximum conversion rate was about 90.15%. - Graphical abstract: Curved rod-shaped mesoporous silica can be obtained at low and the highest PVP concentration, while straight rod-shaped mesoporous silica can be obtained at higher PVP concentration. - Highlights: • Mesoporous silica with morphology evolution from CRMS to SRMS were prepared. • Effects of PVP molecular weight and concentration on silica morphology were studied. • A possible mechanism for the formation of morphology evolution SiO{sub 2} was proposed. • Esterification of lauric acid with 1-butanol catalyzed by immobilized PPL.

  5. The Optimized Synthesis of Starch-g-Lactic Acid Copolymer with High Grafting Degree Catalyzed by Sulfuric Acid

    Institute of Scientific and Technical Information of China (English)

    HU Zhiying

    2014-01-01

    The starch-g-lactic acid copolymer was synthesized with catalysis of sulfuric acid by one-step process, and the structure of starch-g-lactic acid copolymer was characterized by means of IR, 13C-NMR, HMBC, XRD, and SEM. The experimental results show that the maximum grafting degree of starch can reach 75%when the starch-g-lactic acid copolymer is activated at 80℃for 2 h and reacted with lactic acid at 90℃for 4 h in vacuum.

  6. Two-step synthesis of fatty acid ethyl ester from soybean oil catalyzed by Yarrowia lipolytica lipase

    Directory of Open Access Journals (Sweden)

    Chen Jinnan

    2011-03-01

    Full Text Available Abstract Background Enzymatic biodiesel production by transesterification in solvent media has been investigated intensively, but glycerol, as a by-product, could block the immobilized enzyme and excess n-hexane, as a solution aid, would reduce the productivity of the enzyme. Esterification, a solvent-free and no-glycerol-release system for biodiesel production, has been developed, and two-step catalysis of soybean oil, hydrolysis followed by esterification, with Yarrowia lipolytica lipase is reported in this paper. Results First, soybean oil was hydrolyzed at 40°C by 100 U of lipase broth per 1 g of oil with approximately 30% to 60% (vol/vol water. The free fatty acid (FFA distilled from this hydrolysis mixture was used for the esterification of FFA to fatty acid ethyl ester by immobilized lipase. A mixture of 2.82 g of FFA and equimolar ethanol (addition in three steps were shaken at 30°C with 18 U of lipase per 1 gram of FFA. The degree of esterification reached 85% after 3 hours. The lipase membranes were taken out, dehydrated and subjected to fresh esterification so that over 82% of esterification was maintained, even though the esterification was repeated every 3 hours for 25 batches. Conclusion The two-step enzymatic process without glycerol released and solvent-free demonstrated higher efficiency and safety than enzymatic transesterification, which seems very promising for lipase-catalyzed, large-scale production of biodiesel, especially from high acid value waste oil.

  7. Mercapturic acid formation and enzyme-catalyzed conjugations with glutathione in pigeons

    NARCIS (Netherlands)

    Wit, J.G.; Leeuwangh, P.

    1969-01-01

    Pigeons are able to metabolize 3,4-dichloronitrobenzene (DCNB) and 2,3,5,6-tetrachloronitrobenzene (TCNB). The main metabolic route for DCNB is reduction of the nitro group and mercapturic acid is a minor metabolite. TCNB is converted to mercapturic acid. High-speed supernatant of pigeon liver conta

  8. C8-Selective Acylation of Quinoline N-Oxides with α-Oxocarboxylic Acids via Palladium-Catalyzed Regioselective C-H Bond Activation.

    Science.gov (United States)

    Chen, Xiaopei; Cui, Xiuling; Wu, Yangjie

    2016-08-01

    A facile and efficient protocol for palladium-catalyzed C8-selective acylation of quinoline N-oxides with α-oxocarboxylic acids has been developed. In this approach, N-oxide was utilized as a stepping stone for the remote C-H functionalization. The reactions proceeded efficiently under mild reaction conditions with excellent regioselectivity and broad functional group tolerance. PMID:27441527

  9. Kinetics and Mechanism of Ruthenium(III) Catalyzed Oxidation of Butanone and Uncatalyzed Oxidation of Cychlohexanone by Cerium(IV) in Acid Sulphate Medium

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Priyamvada; Hemkar, Shalini; Khandelwal, C. L.; Sharma, P. D. [Univ. of Rajasthan, Jaipur (India)

    2012-02-15

    The kinetics of ruthenium(III) chloride catalyzed oxidation of butanone and uncatalyzed oxidation of cyclohexanone by cerium(IV) in sulphuric acid medium have been studied. The kinetic rate law(I) in case of butanone conforms to the proposed mechanism. Kinetics and activation parameters have been evaluated conventionally. Kinetically preferred mode of reaction is via ketonic and not the enolic forms.

  10. Synthesis of Novel Monophosphoramidite Ligands Derived from L-Proline for Rh-catalyzed Asymmetric Hydrogenation of α-Dehydroamino Acid Esters

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Two novel monophosphoramidites were synthesized through a five-step transformation from commercially available L-proline. In the Ph-catalyzed asymmetric hydrogenation of α-dehydroamino acid derivatives, ligand (Sc,Ra)-1b showed good enantioselectivity and up to 91% e.e. was obtained.

  11. Synthesis of solution-phase phosphoramidite and phosphite ligand libraries and their in situ screening in the rhodium-catalyzed asymmetric addition of arylboronic acids

    NARCIS (Netherlands)

    Jagt, Richard B. C.; Toullec, Patrick Y.; Schudde, Ebe P.; de Vries, Johannes G.; Feringa, Ben L.; Minnaard, Adriaan J.

    2007-01-01

    Herein, we report the automated parallel synthesis of solution-phase libraries of phosphoramidite ligands for the development of enantioselective catalysts. The ligand libraries are screened in situ in the asymmetric rhodium-catalyzed addition of arylboronic acids to aldehydes and imines. It is show

  12. Oxidation of saturated hydrocarbons with peroxyacetic acid catalyzed by vanadium complexes

    OpenAIRE

    Gonzalez Cuervo, Laura; Kozlov, Yuriy N.; Süss-Fink, Georg; Shul’pin, Georgiy B.

    2009-01-01

    Peroxyacetic acid (PAA) oxidizes alkanes in acetonitrile or acetic acid at 60 °C if a soluble vanadium(V) salt, n-Bu4NVO3 (1), is used as a catalyst. Corresponding ketones, alcohols and alkyl hydroperoxides are the main products. Methane, ethane, propane, cyclohexane, and other higher alkanes were substrates in the oxidations. The proposed mechanism involves the formation of a complex between (1) and PAA with equilibrium constants 3.3 and 6.8 dm3 mol−1 for acetonitrile and acetic acid as solv...

  13. Acid-catalyzed steam pretreatment of lodgepole pine and subsequent enzymatic hydrolysis and fermentation to ethanol.

    Science.gov (United States)

    Ewanick, Shannon M; Bura, Renata; Saddler, John N

    2007-11-01

    Utilization of ethanol produced from biomass has the potential to offset the use of gasoline and reduce CO(2) emissions. This could reduce the effects of global warming, one of which is the current outbreak of epidemic proportions of the mountain pine beetle (MPB) in British Columbia (BC), Canada. The result of this is increasing volumes of dead lodgepole pine with increasingly limited commercial uses. Bioconversion of lodgepole pine to ethanol using SO(2)-catalyzed steam explosion was investigated. The optimum pretreatment condition for this feedstock was determined to be 200 degrees C, 5 min, and 4% SO(2) (w/w). Simultaneous saccharification and fermentation (SSF) of this material provided an overall ethanol yield of 77% of the theoretical yield from raw material based on starting glucan, mannan, and galactan, which corresponds to 244 g ethanol/kg raw material within 30 h. Three conditions representing low (L), medium (M), and high (H) severity were also applied to healthy lodgepole pine. Although the M severity conditions of 200 degrees C, 5 min, and 4% SO(2) were sufficiently robust to pretreat healthy wood, the substrate produced from beetle-killed (BK) wood provided consistently higher ethanol yields after SSF than the other substrates tested. BK lodgepole pine appears to be an excellent candidate for efficient and productive bioconversion to ethanol.

  14. Enantioselective synthesis of benzazepinoindoles bearing trifluoromethylated quaternary stereocenters catalyzed by chiral spirocyclic phosphoric acids.

    Science.gov (United States)

    Li, Xuejian; Chen, Di; Gu, Haorui; Lin, Xufeng

    2014-07-18

    The first highly enantioselective iso-Pictet-Spengler reaction of C-2-linked o-aminobenzylindoles with trifluoromethyl ketones was developed using chiral spirocyclic phosphoric acids as organocatalysts, which afforded optically active benzazepinoindoles bearing trifluoromethylated quaternary stereocenters. PMID:24890313

  15. Sulfanilic acid catalyzed solvent-free synthesis of 1,5-benzodiazepine derivatives

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Sulfanilic acid has been found to be an efficient catalyst for the synthesis of 1,5-benzodiazepines from o-phenylenediamine and ketones. This method is simple, effective and environmentally friendly and gives better yields.

  16. Acid Catalyzed Condensation of Phenylethanal Enol or Thiol Enol Ether to 2-Phenylnaphthalene

    Institute of Scientific and Technical Information of China (English)

    CHANG, Yu-An

    2007-01-01

    Treatment of enol ether or thiol enol ether of phenylethanals with sulfuric or polyphosphoric acid in toluene or xylene gave 2-phenylnaphthalene in good yield. More importantly, a one-pot reaction has been developed.

  17. Regiospecific O-methylation of naphthoic acids catalyzed by NcsB1, an O-methyltransferase involved in the biosynthesis of the enediyne antitumor antibiotic neocarzinostatin.

    Science.gov (United States)

    Luo, Yinggang; Lin, Shuangjun; Zhang, Jian; Cooke, Heather A; Bruner, Steven D; Shen, Ben

    2008-05-23

    Neocarzinostatin, a clinical anticancer drug, is the archetypal member of the chromoprotein family of enediyne antitumor antibiotics that are composed of a nonprotein chromophore and an apoprotein. The neocarzinostatin chromophore consists of a nine-membered enediyne core, a deoxyaminosugar, and a naphthoic acid moiety. We have previously cloned and sequenced the neocarzinostatin biosynthetic gene cluster and proposed that the biosynthesis of the naphthoic acid moiety and its incorporation into the neocarzinostatin chromophore are catalyzed by five enzymes NcsB, NcsB1, NcsB2, NcsB3, and NcsB4. Here we report the biochemical characterization of NcsB1, unveiling that: (i) NcsB1 is an S-adenosyl-L-methionine-dependent O-methyltransferase; (ii) NcsB1 catalyzes regiospecific methylation at the 7-hydroxy group of its native substrate, 2,7-dihydroxy-5-methyl-1-naphthoic acid; (iii) NcsB1 also recognizes other dihydroxynaphthoic acids as substrates and catalyzes regiospecific O-methylation; and (iv) the carboxylate and its ortho-hydroxy groups of the substrate appear to be crucial for NcsB1 substrate recognition and binding, and O-methylation takes place only at the free hydroxy group of these dihydroxynaphthoic acids. These findings establish that NcsB1 catalyzes the third step in the biosynthesis of the naphthoic acid moiety of the neocarzinostatin chromophore and further support the early proposal for the biosynthesis of the naphthoic acid and its incorporation into the neocarzinostatin chromophore with free naphthoic acids serving as intermediates. NcsB1 represents another opportunity that can now be exploited to produce novel neocarzinostatin analogs by engineering neocarzinostatin biosynthesis or applying directed biosynthesis strategies. PMID:18387946

  18. Alkylation of Catechol with tert-Butyl Alcohol Catalyzed by Mesoporous Acidic Montmorillonite Heterostructure Catalysts

    Institute of Scientific and Technical Information of China (English)

    周春晖; 葛忠华; 李小年; 童东绅; 李庆伟; 郭红强

    2004-01-01

    The liquid phase alkylation of catechol with tert-butyl alcohol to produce 4-tert-butyl catechol (4-TBC) was carried out over MCM-41, HZSM-5, H-exchanged montmorillonite and novel acidic porous montmorillonite heterostructures (PMHs). Upon all catalysts tested, 4-TBC is the main product and 3-tert-butyl catechol (3-TBC) and 3,5-di-tert-butyl catechol are the side products. The synthetic PMHs showed higher conversion of catechol and better selectivity to 4-TBC compared to other solid acid catalysts tested. Over the PMHs derived from H-exchanged montmorillonite through template extraction processes, the suitable reaction temperature is ca 410 K, the ratio of catechol to tert-butyl alcohol is 1:2. Increasing the amount of catalyst (lower weight hourly space velocity) can improve the conversion of catechol and influence the selectivity slightly. The reasonable reaction time is ca 8 h.The type and strength of acidity of H-montmorillonite and PMH were determined by pyridine adsorption FT-IR and ammonia temperature-programmed desorption techniques. The medium and strong acid sites are conducive to producing 4-TBC and the weak acid sites to facilitating the 3-TBC formation. The differences between the PMHs from calcination and those fi'om extraction are attributed to proton migration and acidity change in the gallery surface.

  19. 菊粉酸降解动力学研究%Kinetic Studies on Acid Catalyzed Hydrolysis of Inulin

    Institute of Scientific and Technical Information of China (English)

    许威; 罗登林; 陈瑞红; 刘建学

    2012-01-01

    通过考察温度、溶液pH值及水分含量对菊粉酸降解的影响,探索菊粉酸水解规律。结果表明:菊粉水溶液在pH 5.0~7.0、温度低于100℃时具有良好的稳定性;但当pH值低于4.0时,菊粉出现明显的水解反应。菊粉溶液在不同温度和pH值下的酸降解动力学表明,其水解反应遵循一级反应动力学方程。利用菊粉凝胶特性考察水分含量与菊粉酸降解的关系,发现相同pH值(pH=3)条件下,水分含量越高,菊粉降解速率越快,凝胶中菊粉降解速率低于菊粉水溶液降解速率。%The effects of temperature,pH and water content on inulin hydrolysis were studied to understand the acid catalyzed hydrolysis process of inulin for industrial production of high-fructose syrup.The results showed that inulin solution had a good thermal stability at a pH value in the range of 5.0-7.0 and a temperature below 100 ℃,while inulin degradation started to occur when the pH was lower than 4.0.The acid catalyzed hydrolysis dynamics of inulin at different levels of temperature and pH showed that the reaction followed the first-order kinetics well.The relation between inulin gel degradation induced by acid and water content was also investigated.At the same pH,the higher water content,the faster inulin hydrolysis,and the degradation rate of inulin was lower in gel than in aqueous solution.

  20. Synthesis of ascorbyl oleate by transesterification of olive oil with ascorbic acid in polar organic media catalyzed by immobilized lipases.

    Science.gov (United States)

    Moreno-Perez, Sonia; Filice, Marco; Guisan, Jose M; Fernandez-Lorente, Gloria

    2013-09-01

    The reaction of transesterification between oils (e.g., olive oil) and ascorbic acid in polar anhydrous media (e.g., tert-amyl alcohol) catalyzed by immobilized lipases for the preparation of natural liposoluble antioxidants (e.g., ascorbyl oleate) was studied. Three commercial lipases were tested: Candida antarctica B lipase (CALB), Thermomyces lanuginosus lipase (TLL) and Rhizomucor miehei lipase (RML). Each lipase was immobilized by three different protocols: hydrophobic adsorption, anionic exchange and multipoint covalent attachment. The highest synthetic yields were obtained with CALB adsorbed on hydrophobic supports (e.g., the commercial derivative Novozym 435). The rates and yields of the synthesis of ascorbyl oleate were higher when using the solvent dried with molecular sieves, at high temperatures (e.g. 45°C) and with a small excess of oil (2 mol of oil per mol of ascorbic acid). The coating of CALB derivatives with polyethyleneimine (PEI) improved its catalytic behavior and allowed the achievement of yields of up to 80% of ascorbyl oleate in less than 24h. CALB adsorbed on a hydrophobic support and coated with PEI was 2-fold more stable than a non-coated derivative and one hundred-fold more stable than the best TLL derivative. The best CALB derivative exhibited a half-life of 3 days at 75°C in fully anhydrous media, and this derivative maintained full activity after 28 days at 45°C in dried tert-amyl alcohol. PMID:23891831

  1. Enhancement of Lipase-catalyzed Synthesis of Caffeic Acid Phenethyl Ester in Ionic Liquid with DMSO Co-solvent☆

    Institute of Scientific and Technical Information of China (English)

    Shuangshuang Gu; Jun Wang; Xianbin Wei; Hongsheng Cui; Xiangyang Wu; Fuan Wu

    2014-01-01

    Caffeic acid phenethyl ester (CAPE) is a natural and rare ingredient with several biological activities, but its indus-trial production using lipase-catalyzed esterification of caffeic acid (CA) and 2-phenylethanol (PE) in ionic liquids (ILs) is hindered by low substrate concentrations and long reaction time. To set up a high-efficiency bioprocess for production of CAPE, a novel dimethyl sulfoxide (DMSO)–IL co-solvent system was established in this study. The 2%(by volume) DMSO–[Bmim][Tf2N] system was found to be the best medium with higher substrate solu-bility and conversion of CA. Under the optimum conditions, the substrate concentration of CA was raised 8-fold, the reaction time was reduced by half, and the conversion reached 96.23%. The kinetics follows a ping-pong bi-bi mechanism with inhibition by PE, with kinetic parameters as follows:Vmax=0.89 mmol · min−1 · g−1, Km,CA=42.9 mmol · L−1, Km,PE=165.7 mmol · L−1, and Ki,PE=146.2 mmol · L−1. The results suggest that the DMSO co-solvent effect has great potential to enhance the enzymatic synthesis efficiency of CAPE in ILs.

  2. Phenylalanine ammonia lyase catalyzed synthesis of amino acids by an MIO-cofactor independent pathway.

    Science.gov (United States)

    Lovelock, Sarah L; Lloyd, Richard C; Turner, Nicholas J

    2014-04-25

    Phenylalanine ammonia lyases (PALs) belong to a family of 4-methylideneimidazole-5-one (MIO) cofactor dependent enzymes which are responsible for the conversion of L-phenylalanine into trans-cinnamic acid in eukaryotic and prokaryotic organisms. Under conditions of high ammonia concentration, this deamination reaction is reversible and hence there is considerable interest in the development of PALs as biocatalysts for the enantioselective synthesis of non-natural amino acids. Herein the discovery of a previously unobserved competing MIO-independent reaction pathway, which proceeds in a non-stereoselective manner and results in the generation of both L- and D-phenylalanine derivatives, is described. The mechanism of the MIO-independent pathway is explored through isotopic-labeling studies and mutagenesis of key active-site residues. The results obtained are consistent with amino acid deamination occurring by a stepwise E1 cB elimination mechanism.

  3. Electro-oxidation of ascorbic acid catalyzed on cobalt hydroxide-modified glassy carbon electrode

    Directory of Open Access Journals (Sweden)

    GHASEM KARIM-NEZHAD

    2009-05-01

    Full Text Available The electrochemical behavior of ascorbic acid on a cobalt hydroxide modified glassy carbon (CHM–GC electrode in alkaline solution was investigated. The process of the involved oxidation and its kinetics were established using the cyclic voltammetry, chronoamperometry techniques, as well as by steady state polarization measurements. The results revealed that cobalt hydroxide promotes the rate of oxidation by increasing the peak current; hence ascorbic acid is oxidized at lower potentials, which is thermodynamically more favorable. The cyclic voltammograms and chronoamperometry indicate a catalytic EC mechanism is operative with the electrogeneration of Co(IV as the electrochemical process. Also, the process is diffusion-controlled and the current–time responses follow Cottrellian behavior. This result was confirmed by steady state measurements. The rate constants of the catalytic oxidation of ascorbic acid and the electron-transfer coefficient are reported.

  4. Convenient synthetic method of starch/lactic acid graft copolymer catalyzed with sodium hydroxide

    Indian Academy of Sciences (India)

    Qingling Wang; Yingmo Hu; Jianhua Zhu; Yang Liu; Xue Yang; Jing Bian

    2012-06-01

    Copolymer of starch grafted with lactic acid (LA) could be directly prepared by reaction of cornstarch with lactic acid and with sodium hydroxide (NaOH) as the catalyst. The structure of starch/LA copolymer was characterized by IR, XRD, SEM and 1H-NMR. The effects of NaOH concentration, ratios of starch and LA, reaction temperature and reaction time on the grafting degree were also investigated and the results showed that the highest grafting degree of starch could reach 33.60% when the graft copolymerization was carried out in 0.40 mol l-1 NaOH aqueous solution for 9 h at 90°C with 1: 6 ratio of starch and lactic acid.

  5. Lipase catalyzed synthesis of neutral glycerides rich in micronutrients from rice bran oil fatty acid distillate.

    Science.gov (United States)

    Nandi, Sumit; Gangopadhyay, Sarbani; Ghosh, Santinath

    2008-01-01

    Neutral glycerides with micronutrients like sterols, tocopherols and squalene may be prepared from cheap raw material like rice bran oil fatty acid distillate (RBO FAD). RBO FAD is an important byproduct of vegetable oil refining industries in the physical refining process. Glycerides like triacylglycerols (TAG), diacylglycerols (DAG) and monoacylglycerols (MAG) containing significant amounts of unsaponifiable matter like sterols, tocopherols and hydrocarbons (mainly squalene) may certainly be considered as novel functional food ingredients. Fatty acids present in RBO FAD were esterified with glycerol of varying amount (1:0.33, 1:0.5, 1:1 and 1:1.5 of FAD : glycerol ratio) for 8 h using non-specific enzyme NS 40013 (Candida antartica). After esterification the product mixture containing mono, di- and triglycerides was purified by molecular distillation to remove excess free fatty acids and also other volatile undesirable components. The purified product containing sterols, tocopherols and squalene can be utilized in various food formulations.

  6. Brønsted acid ionic liquid catalyzed formation of pyruvaldehyde dimethylacetal from triose sugars

    DEFF Research Database (Denmark)

    Shunmugavel, Saravanamurugan; Riisager, Anders

    2013-01-01

    A series of sulfonic acid functionalized ionic liquids (SO3H-ILs) have been synthesized, characterized and investigated as catalysts for the conversion of the triose sugars, 1,3-dihydroxyacetone (DHA) and glyceraldehyde (GLA), to pyruvaldehyde dimethylacetal (PADA) in methanol. Depending on the r......A series of sulfonic acid functionalized ionic liquids (SO3H-ILs) have been synthesized, characterized and investigated as catalysts for the conversion of the triose sugars, 1,3-dihydroxyacetone (DHA) and glyceraldehyde (GLA), to pyruvaldehyde dimethylacetal (PADA) in methanol. Depending...

  7. ESTERIFICATION OF ACRYLIC ACID WITH 1-BUTANOL IN LIQUID PHASE CATALYZED WITH AL-MCM-41

    OpenAIRE

    Edson Avellaneda Maytán; Gustavo Paim Valença

    2010-01-01

    This work studies the esterification of acrylic acid with 1-butanol using Al-MCM-41 as catalyst with different degrees of acidity at different temperatures. Al-MCM-41 synthesis was made from bromate Cetyl trimethyl ammonium using as router agent, NH4OH (25%), deionized H2O and Al2(SO4)3. Catalytic tests were carried out by groups and worked with temperature ranges among (333 to 348) K and a small sample was collected at predetermined intervals of time for subsequent gas chromatography analysi...

  8. Preparation of fructone catalyzed by water-soluble Br(φ)nsted acid ionic liquids

    Institute of Scientific and Technical Information of China (English)

    Yuan Yuan Wang; Rong Wang; Liang Chun Wu; Li Yi Dai

    2007-01-01

    Fructone (2-methyl-2-ethylacetoacetate-1,3-dioxolane), a flavouring material, has been synthesized from ethyl acetoacetate and glycol using five water-soluble Br(φ)nsted acid ionic liquids as catalysts for the first time. The used Br(φ)nsted acid ionic liquids include [Hmim]Tfa, [Hmim]Tsa, [Hmim]BF4, [Bmim]HSO4, [Bmim]H2PO4, and [Hmim]BF4 showed the highest catalytic activity for the preparation of fructone. After reaction, the product could be isolated from the reaction system automatically, and the ionic liquid could be directly reused without dehydration.

  9. Lipase-catalyzed synthesis of oligoesters of 2,5-furandicarboxylic acid with aliphatic diols

    NARCIS (Netherlands)

    Cruz-Izquierdo, Álvaro; Broek, van den Lambertus A.M.; Serra, Juan L.; Llama, María J.; Boeriu, Carmen G.

    2015-01-01

    2,5-Furandicarboxylic acid is a platform chemical for the production of biobased polymers and materials. This study reports the synthesis of furan oligoesters via polytransesterification of dimethyl furan-2,5-dicarboxylate and linear α, ω-aliphatic diols with chain length ranging from C2 to C12,

  10. Studies concerning the anion ex-change resins catalyzed esterification of epichlorohydrin with organic acids

    Directory of Open Access Journals (Sweden)

    E.I. Muresan

    2009-09-01

    Full Text Available The paper studies the esterification of carboxylic acids with epichlorohydrin over two macroporous strong base anion exchange resins with different polymer matrix. For both resins, the influence of reaction parameters (temperature, catalyst loading, molar ratio on the reaction rate and the yields of the two isomeric esters were investigated.

  11. Lewis-acid catalyzed depolymerization of Protobind lignin in supercritical water and ethanol

    NARCIS (Netherlands)

    Guvenatam, Burcu; Heeres, Erik H.J.; Pidko, Evgeny A.; Hensen, Ernie J. M.

    2016-01-01

    The use of metal acetates, metal chlorides and metal triflates as Lewis acid catalysts for the depolymerization of soda lignin under supercritical conditions was investigated. The reactions were carried out at 400 degrees C in water and ethanol. Lignin conversion in supercritical water led to format

  12. Tannic acid Catalyzed an Efficient Synthesis of 2,4,5-Triaryl-1H-Imidazole

    Directory of Open Access Journals (Sweden)

    Shitole Nana Vikram

    2013-05-01

    Full Text Available Tannic acid (C76H52O46 has been found to be an efficient catalyst for one-pot synthesis of 2,4,5-triaryl substituted imidazoles by the reaction of an arylaldehyde, benzyl/benzoin and an ammonium acetate. The short reaction time and excellent yields making this protocol practical and economically attractive.

  13. Nonmetal catalyzed insertion reactions of diazocarbonyls to acid derivatives in fluorinated alcohols.

    Science.gov (United States)

    Dumitrescu, Lidia; Azzouzi-Zriba, Kaouther; Bonnet-Delpon, Danièle; Crousse, Benoit

    2011-02-18

    The insertion reaction of diazocarbonyls to acids could be performed smoothly in fluorinated alcohols in the absence of metal catalyst. This new procedure allowed the chemoselective preparation of various functionalized compounds such as acyloxyesters, depsipeptides, and sulfonate, phosphonate, or boronate derivatives.

  14. Mass transfer effects in the H2SO4 catalyzed pivalic acid synthesis

    NARCIS (Netherlands)

    Brilman, D.W.F.; Meesters, N.G.; Swaaij, W.P.M. van; Versteeg, G.F.

    2001-01-01

    The synthesis of carboxylic acids from alkenes, carbon monoxide and water according to the Koch process is usually carried out in a stirred gas–liquid–liquid multiphase reactor. Due to the complex reaction system with fast, equilibrium reactions and fast, irreversible reactions the yield and product

  15. Lewis base additives improve the zeolite ferrierite-catalyzed synthesis of isostearic acid

    Science.gov (United States)

    Isostearic acid (IA) is of interest for industrial purposes especially in the area of biolubricants, such as cosmetics and slip additives for polyolefin and related copolymer films. This study was designed to develop a zeolitic catalysis process for IA production through isomerization of fatty aci...

  16. Oxalic acid catalyzed solvent-free one pot synthesis of coumarins

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Oxalic acid was found to be an efficient catalyst for Pechmann condensation, which includes the reaction between phenols and β-keto esters leading to formation of coumarin derivatives. The advantages of present methods are the use of cheap and easy available catalyst, solvent-free reaction conditions, better yields and shorter reaction time.

  17. Coupling of Carbon Dioxide with Epoxides Catalyzed by Amino Acid Hydrochloride Salts

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Using amino acid hydrochloride salt as a catalyst, the coupling reaction of CO2 with epoxides could proceed smoothly to give cyclic carbonates in very good yields and high selectivity. The reaction conditions such as the pressure of carbon dioxide, reaction temperature, time and catalyst loading were carefully investigated.

  18. INTERESTERIFICATION OF MILK-FAT WITH OLEIC-ACID CATALYZED BY IMMOBILIZED RHIZOPUS-ORYZAE LIPASE

    NARCIS (Netherlands)

    OBA, T; WITHOLT, B

    1994-01-01

    Milk fat was interesterified with oleic acid by catalysis of an immobilized lipase in a microaqueous two-phase system. A commercial lipase from Rhizopus oryzae and a controlled pore glass carrier were selected for preparation of an immobilized lipase. The prepared immobilized lipase showed a Michael

  19. Imidase catalyzing desymmetric imide hydrolysis forming optically active 3-substituted glutaric acid monoamides for the synthesis of gamma-aminobutyric acid (GABA) analogs.

    Science.gov (United States)

    Nojiri, Masutoshi; Hibi, Makoto; Shizawa, Hiroaki; Horinouchi, Nobuyuki; Yasohara, Yoshihiko; Takahashi, Satomi; Ogawa, Jun

    2015-12-01

    The recent use of optically active 3-substituted gamma-aminobutyric acid (GABA) analogs in human therapeutics has identified a need for an efficient, stereoselective method of their synthesis. Here, bacterial strains were screened for enzymes capable of stereospecific hydrolysis of 3-substituted glutarimides to generate (R)-3-substituted glutaric acid monoamides. The bacteria Alcaligenes faecalis NBRC13111 and Burkholderia phytofirmans DSM17436 were discovered to hydrolyze 3-(4-chlorophenyl) glutarimide (CGI) to (R)-3-(4-chlorophenyl) glutaric acid monoamide (CGM) with 98.1% enantiomeric excess (e.e.) and 97.5% e.e., respectively. B. phytofirmans DSM17436 could also hydrolyze 3-isobutyl glutarimide (IBI) to produce (R)-3-isobutyl glutaric acid monoamide (IBM) with 94.9% e.e. BpIH, an imidase, was purified from B. phytofirmans DSM17436 and found to generate (R)-CGM from CGI with specific activity of 0.95 U/mg. The amino acid sequence of BpIH had a 75% sequence identity to that of allantoinase from A. faecalis NBRC13111 (AfIH). The purified recombinant BpIH and AfIH catalyzed (R)-selective hydrolysis of CGI and IBI. In addition, a preliminary investigation of the enzymatic properties of BpIH and AfIH revealed that both enzymes were stable in the range of pH 6-10, with an optimal pH of 9.0, stable at temperatures below 40 °C, and were not metalloproteins. These results indicate that the use of this class of hydrolase to generate optically active 3-substituted glutaric acid monoamide could simplify the production of specific chiral GABA analogs for drug therapeutics.

  20. Kinetics of cytochrome P450 2E1-catalyzed oxidation of ethanol to acetic acid via acetaldehyde.

    Science.gov (United States)

    Bell-Parikh, L C; Guengerich, F P

    1999-08-20

    The P450 2E1-catalyzed oxidation of ethanol to acetaldehyde is characterized by a kinetic deuterium isotope effect that increases K(m) with no effect on k(cat), and rate-limiting product release has been proposed to account for the lack of an isotope effect on k(cat) (Bell, L. C., and Guengerich, F. P. (1997) J. Biol. Chem. 272, 29643-29651). Acetaldehyde is also a substrate for P450 2E1 oxidation to acetic acid, and k(cat)/K(m) for this reaction is at least 1 order of magnitude greater than that for ethanol oxidation to acetaldehyde. Acetic acid accounts for 90% of the products generated from ethanol in a 10-min reaction, and the contribution of this second oxidation has been overlooked in many previous studies. The noncompetitive intermolecular kinetic hydrogen isotope effects on acetaldehyde oxidation to acetic acid ((H)(k(cat)/K(m))/(D)(k(cat)/K(m)) = 4.5, and (D)k(cat) = 1.5) are comparable with the isotope effects typically observed for ethanol oxidation to acetaldehyde, and k(cat) is similar for both reactions, suggesting a possible common catalytic mechanism. Rapid quench kinetic experiments indicate that acetic acid is formed rapidly from added acetaldehyde (approximately 450 min(-1)) with burst kinetics. Pulse-chase experiments reveal that, at a subsaturating concentration of ethanol, approximately 90% of the acetaldehyde intermediate is directly converted to acetic acid without dissociation from the enzyme active site. Competition experiments suggest that P450 2E1 binds acetic acid and acetaldehyde with relatively high K(d) values, which preclude simple tight binding as an explanation for rate-limiting product release. The existence of a rate-determining step between product formation and release is postulated. Also proposed is a conformational change in P450 2E1 occurring during the course of oxidation and the discrimination of P450 2E1 between acetaldehyde and its hydrated form, the gem-diol. This multistep P450 reaction is characterized by kinetic

  1. Enantioselective CuH-Catalyzed Reductive Coupling of Aryl Alkenes and Activated Carboxylic Acids.

    Science.gov (United States)

    Bandar, Jeffrey S; Ascic, Erhad; Buchwald, Stephen L

    2016-05-11

    A new method for the enantioselective reductive coupling of aryl alkenes with activated carboxylic acid derivatives via copper hydride catalysis is described. Dual catalytic cycles are proposed, with a relatively fast enantioselective hydroacylation cycle followed by a slower diastereoselective ketone reduction cycle. Symmetrical aryl carboxyclic anhydrides provide access to enantioenriched α-substituted ketones or alcohols with excellent stereoselectivity and functional group tolerance. PMID:27121395

  2. Hydrolysis of Selected Tropical Plant Wastes Catalyzed by a Magnetic Carbonaceous Acid with Microwave

    Science.gov (United States)

    Su, Tong-Chao; Fang, Zhen; Zhang, Fan; Luo, Jia; Li, Xing-Kang

    2015-12-01

    In this study, magnetic carbonaceous acids were synthesized by pyrolysis of the homogeneous mixtures of glucose and magnetic Fe3O4 nanoparticles, and subsequent sulfonation. The synthesis conditions were optimized to obtain a catalyst with both high acid density (0.75 mmol g-1) and strong magnetism [magnetic saturation, Ms = 19.5 Am2 kg-1]. The screened catalyst (C-SO3H/Fe3O4) was used to hydrolyze ball-milled cellulose in a microwave reactor with total reducing sugar (TRS) yield of 25.3% under the best conditions at 190 °C for 3.5 h. It was cycled for at least seven times with high catalyst recovery rate (92.8%), acid density (0.63 mmol g-1) and magnetism (Ms = 12.9 Am2 kg-1), as well as high TRS yield (20.1%) from the hydrolysis of ball-milled cellulose. The catalyst was further successfully tested for the hydrolysis of tropical biomass with high TRS and glucose yields of 79.8% and 58.3% for bagasse, 47.2% and 35.6% for Jatropha hulls, as well as 54.4% and 35.8% for Plukenetia hulls.

  3. Phenylsulfonic Acid Functionalized Mesoporous Silica Catalyzed Transetherification of Alcohols with Dimethoxymethane

    Institute of Scientific and Technical Information of China (English)

    杨建明; 吕剑

    2005-01-01

    Phenylsulfonic acid functionalized mesoporous silica was synthesized by condensation of tetraethylorthosilicate with phenyltrimethoxysilane, and then sulfonation using 30% fuming sulfuric acid. The material was characterized using FT-IR, DSC, XPS, TEM and N2 adsorption/desorption measurements. DSC revealed that sulfonic acid group of the catalyst was decomposed at 354.8℃, indicating that the catalyst exhibited high thermal stability. XPS showed that there existed three kinds of different silicon species on surface of the catalyst. The catalytic performance of the catalyst was evaluated using transetherification of alcohols with dimethoxymethane. It was found that among primary alcohols, the selectivities of the two long-chain alcohols for n-dedocanol and n-tetradecyl alcohol were higher than 97.0% at the conversions of 43.6% and 65.3%, respectively, while the selectivities of the short-chain alcohols except for n-hexanol were less than 90.0% at the conversions of over 80.0%. Due to steric bartier, the secondary alcohols such as /so-butanol and cyclohexanol afforded conversions of 79.4% and 60.5%, and the selectivities of the two alcohols were more than 90.0%. The sequence in conversion of the substituted phenols isas follows: p-nitrophenol>p-fluorophenol≥p-bromophenol>p-cresol>m-cresol.

  4. Asymmetric Aldol Reaction Catalyzed by L-Proline and Achiral Thiourea Fluoroboric Acid Salt

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Eun; Lee, Haney; Kim, Taek Hyeon [Chonnam National University, Gwangju (Korea, Republic of)

    2015-01-15

    Considering its ready availability and low cost, L-proline would be the first choice catalyst for preparing aldol adducts with high diastereo- and enantioselectivity. However, proline presents some major drawbacks, including poor performance in direct aldol reactions with aromatic aldehydes, limited solubility, and reactivity in nonpolar organic solvents, and side reactions that make using high catalyst loadings necessary to reach satisfactory conversions. Therefore, numerous proline-modified organo catalysts such as prolinamides, proline thioamides, sulfonamides, chiral amines, and organic salts have been designed for direct aldol reactions. An alternative is to add a readily available additive to the reactions containing proline. This last approach is clearly advantageous in avoiding tedious chemical syntheses of organo catalysts and would ultimately allow the construction of libraries of catalyst protocols by simply changing the additive. Acid additives can influence the outcome of enamine mediated reactions; however, only a few screening studies of acid additions to thiourea organo catalysts are available in the literature. The reaction between cyclohexanone and 4-nitrobenzaldehyde was selected as a standard model reaction for screening of more effective acid additives to thiourea.

  5. Preparation of mono- and diacetyl 4,4′-dimethylbiphenyl and their corresponding carboxylic acids

    DEFF Research Database (Denmark)

    Titinchi, Salam J.J.; Kamounah, Fadhil S.; Abbo, Hanna S.

    2007-01-01

    Shape selective acetylation of 4,4′-dimethylbiphenyl using anhydrous aluminum chloride as catalyst is an effective route for the production of mono- and di-acetyl-4,4′-dimethylbiphenyl. Preparations, characterization and a catalytic study of the Friedel-Crafts acetylation of 4,4′-dimethylbiphenyl...

  6. Phase Transfer Catalyzed Synthesis of Thiosemicarbazide Derivatives of 2-ethoxybenzoic Acid

    Institute of Scientific and Technical Information of China (English)

    WEI TaiBao; ZHANG YouMing; WU JiaWei

    2001-01-01

    @@ A series of 1,4-disubstitued thiosemicarbazides and their related heterocyclic compounds have been found to possess important biological activities[1]. Some thiosemicarbazides have been found to be useful as herbicides, insecticides and plant-growth regulators [1]. In view of these and in continuation of our earlier work on the synthesis and biological activity of thiosemicarbaides derivatives [2], we now report a convenient and efficient method for the preparation of thiosemicarbazides derivatives of 2-ethoxybenzoic acid under the condition of solid-liquid phase transfer catalysis using PEG-400 as the catalyst.

  7. Phase Transfer Catalyzed Synthesis of Thiosemicarbazide Derivatives of 2-ethoxybenzoic Acid

    Institute of Scientific and Technical Information of China (English)

    WEI; TaiBao

    2001-01-01

    A series of 1,4-disubstitued thiosemicarbazides and their related heterocyclic compounds have been found to possess important biological activities[1]. Some thiosemicarbazides have been found to be useful as herbicides, insecticides and plant-growth regulators [1]. In view of these and in continuation of our earlier work on the synthesis and biological activity of thiosemicarbaides derivatives [2], we now report a convenient and efficient method for the preparation of thiosemicarbazides derivatives of 2-ethoxybenzoic acid under the condition of solid-liquid phase transfer catalysis using PEG-400 as the catalyst.  ……

  8. Lipase-catalyzed esterification of lactic acid with straight-chain alcohols

    DEFF Research Database (Denmark)

    Rønne, Torben Harald; Xu, Xuebing; Tan, Tianwei

    2005-01-01

    Candida antarctica lipase B (Novozym 435) as well as the textile-immobilized Candida sp. lipase. A method was established to obtain ester yields in the range of 71 to 82% for the different alcohols, and the most favorable conditions for the esterification reaction using Novozym 435 were an equimolar ratio......% of Novozym 435. The immobilized Candida sp. lipase prepared in the laboratory also could be used to produce esters of lactic acid and straight-chain alcohols, but it had a much lower activity than Novozym 435 with a temperature optimum of 40°C....

  9. Self-catalyzed syntheses, structural characterization, DPPH radical scavenging-, cytotoxicity-, and DFT studies of phenoxyaliphatic acids of 1,8-dioxo-octahydroxanthene derivatives

    Science.gov (United States)

    Suresh Kumar, G. S.; Antony Muthu Prabhu, A.; Seethalashmi, P. G.; Bhuvanesh, N.; Kumaresan, S.

    2014-02-01

    One-pot, in-water syntheses of phenoxyaliphatic acids of 1,8-dioxo-octahydroxanthene derived from dimedone and formylphenoxyaliphatic acids are reported. Geometries of compounds 2b, 2c, and 5a have been examined crystallographically. The synthesized compounds showed better DPPH radical scavenging activity and cytotoxicity against A431 cancer cell line. The molecular properties of all synthesized xanthenes have been investigated using single crystal XRD and DFT method. Self-catalyzed Bronsted-Lowry acid catalytic behavior was also investigated by both experimental and theoretical methods.

  10. Upward Trend in Catalytic Efficiency of Rare-Earth Triflate Catalysts in Friedel-Crafts Aromatic Sulfonylation Reactions

    DEFF Research Database (Denmark)

    Duus, Fritz; Le, Thach Ngoc; Nguyen, Vo Thu An

    2014-01-01

    90 % were achieved for short irradiation periods. This was the case especially for Tm(OTf)3, Yb(OTf)3, and Lu(OTf)3, of which Yb(OTf)3 was the most efficient. The upward trend in catalytic efficiency therefore correlates with the lanthanide sequence in the periodic table. The results can be explained...

  11. Highly active and reusable catalyst from Fe-Mg-hydrotalcite anionic clay for Friedel-Crafts type benzylation reactions

    Indian Academy of Sciences (India)

    Vasant R Choudhary; Rani Jha; Pankaj A Choudhari

    2005-11-01

    Fe-Mg-hydrotalcite (Mg/Fe = 3) anionic clay with or without calcination (at 200-800°C) has been used for the benzylation of toluene and other aromatic compounds by benzyl chloride. Hydrotalcite before and after its calcination was characterized for surface area, crystalline phases and basicity. Both the hydrotalcite, particularly after its use in the benzylation reaction, and the catalyst derived from it by its calcination at 200-800°C show high catalytic activity for the benzylation of toluene and other aromatic compounds. The catalytically active species present in the catalyst in its most active form are the chlorides and oxides of iron on the catalyst surface.

  12. Effect of polyvinylpyrrolidone on mesoporous silica morphology and esterification of lauric acid with 1-butanol catalyzed by immobilized enzyme

    Science.gov (United States)

    Zhang, Jinyu; Zhou, Guowei; Jiang, Bin; Zhao, Minnan; Zhang, Yan

    2014-05-01

    Mesoporous silica materials with a range of morphology evolution, i.e., from curved rod-shaped mesoporous silica to straight rod-shaped mesoporous silica, were successfully prepared using polyvinylpyrrolidone (PVP) and triblock copolymer as dual template. The effects of PVP molecular weight and concentration on mesoporous silica structure parameters were studied. Results showed that surface area and pore volume continuously decreased with increased PVP molecular weight. Mesoporous silica prepared with PVP K30 also possessed larger pore diameter, interplanar spacing (d100), and cell parameter (a0) than that prepared with PVP K15 and PVP K90. In addition, with increased PVP concentration, d100 and a0 continuously decreased. The mechanism of morphology evolution caused by the change in PVP concentration was investigated. The conversion rate of lauric acid with 1-butanol catalyzed by immobilized Porcine pancreatic lipase (PPL) was also evaluated. Results showed that PPL immobilized on amino-functionalized straight rod-shaped mesoporous silica maintained 50% of its esterification conversion rate even after five cycles of use with a maximum conversion rate was about 90.15%.

  13. Unsaturated Fatty Acid Esters Metathesis Catalyzed by Silica Supported WMe5

    KAUST Repository

    Riache, Nassima

    2015-11-14

    Metathesis of unsaturated fatty acid esters (FAEs) by silica supported multifunctional W-based catalyst is disclosed. This transformation represents a novel route towards unsaturated di-esters. Especially, the self-metathesis of ethyl undecylenate results almost exclusively on the homo-coupling product whereas with such catalyst, 1-decene gives ISOMET (isomerization and metathesis olefin) products. The olefin metathesis in the presence of esters is very selective without any secondary cross-metathesis products demonstrating that a high selective olefin metathesis could operate at 150 °C. Additionally, a cross-metathesis of unsaturated FAEs and α-olefins allowed the synthesis of the corresponding ester with longer hydrocarbon skeleton without isomerisation.

  14. Biomimetic Fenton-catalyzed lignin depolymerization to high-value aromatics and dicarboxylic acids.

    Science.gov (United States)

    Zeng, Jijiao; Yoo, Chang Geun; Wang, Fei; Pan, Xuejun; Vermerris, Wilfred; Tong, Zhaohui

    2015-03-01

    By mimicking natural lignin degradation systems, the Fenton catalyst (Fe(3+), H2O2) can effectively facilitate lignin depolymerization in supercritical ethanol (7 MPa, 250 °C) to give organic oils that consist of mono- and oligomeric aromatics, phenols, dicarboxylic acids, and their derivatives in yields up to (66.0±8.5) %. The thermal properties, functional groups, and surface chemistry of lignin before and after Fenton treatment were examined by thermogravimetric analysis, pyrolysis-gas chromatography-mass spectrometry, (31)P NMR spectroscopy, and X-ray photoelectron spectroscopy. The results suggest that the Fenton catalyst facilitates lignin depolymerization through cleavage of β-ether bonds between lignin residues. The formation of a lignin-iron chelating complex effectively depresses lignin recondensation; thus minimizing charcoal formation and enhancing the yield of liquid products.

  15. Synthesis of 5-hydroxymethylfurfural (HMF) by acid catalyzed dehydration of glucose-fructose mixtures

    DEFF Research Database (Denmark)

    Pedersen, Asbjørn Toftgaard; Ringborg, Rolf Hoffmeyer; Grotkjær, Thomas;

    2015-01-01

    -products: soluble humins, glucose dimers, anhydroglucose, and formic acid. The reaction conditions in four different reactor configurations were optimized and compared using the kinetic model. It was found that a recirculating reactor setup is preferable, where the equilibrium controlled by-products (anhydroglucose...... a detailed experimental investigation a reaction network was proposed, and subsequently the corresponding kinetic model was fitted to experimental data in order to obtain estimates of the reaction kinetic parameters. The kinetic model is capable of predicting the formation of HMF along with the important by...... and glucose dimers) are recirculated to the dehydration reactor. The model predicts an HMF selectivity of close to 70% in a recirculating reactor at conditions where HMF degradation is avoided....

  16. Hydrogenation of phenylpyruvic acid to phenylalanine catalyzed by Ni-B/SiO2

    Institute of Scientific and Technical Information of China (English)

    Qunfang Liang; Aiqing Zhang; Lin Li

    2008-01-01

    Phenylalanine(Phe)is a significant amino acid that cannot be synthesized by human themselves but must be taken from environment.It was initially found that the nanosized amorphous Ni-B/SiO2 alloy prepared by the chemical reduction method was an effective catalyst for the preparation of Phe from phenylpyruvic acid(PPA)by amination and hydrogenation.It has been found that the amorphous Ni-B/SiO2 alloy catalyst exhibits superior activity and selectivity to the traditional catalysts Raney Nj and Urushibara nickel.The effects of reaction time.amounts of catalysts and ammonia solution,reaction temperature,and H2 pressure on the reaction have been investigated systematically.The results indicated that the yield of Phe was 97.9%.and the selectivity for Phe reached 98.9%when the reaction was carried out for 3 h at 333 K and 2.0 Mpa of H2 with m(Cat.):m(PPA)=0.6:1.0 and n(NH3):n(PPA)=3:1.The catalysts were characterized by XRD,AAS,XPS,BET,and TEM.and the relationship between the catalyst structure and the catalytic activity was discussed in detail.It was found that the reason why Ni-B/SiO2 amorphous alloy catalyst was much more active for the preparation of Phe could be accounted for by the presence of electron-rich Ni due to electron donation from alloying B:the smaller size of Ni-B particles,the larger specific surface area of Ni-B/SiO2.

  17. Efficient Lewis Acids Catalyzed Aza-Michael Reactions of Enones with Carbamates

    Institute of Scientific and Technical Information of China (English)

    XIA Chun-Gu; XU Li-Wen

    2004-01-01

    The a-amino carbonyl functionality is not only a segment of biologically important natural products but also a versatile intermediate for the synthesis of nitrogen-containing compounds.1 The development of novel synthetic methods leading to a-amino ketone, a-amino acids or their derivatives has attracted much attention in organic synthesis.2 Among the traditional methods for generating a-amino carbonyl compounds, Mannich-type reaction is one of the classical and powerful methods.3 However, the classic Mannich reaction presents serious disadvantages, for example, there is still a drawback in that the silyl enolates have to be prepared from the corresponding carbonyl compounds. Alternatively, aza-Michael additions can be used to create carbon-heteroatom bonds by reaction of a,a-unsaturated carbonyl compounds with amines. Although recent advances have made this route more attractive, development of cheaper, simpler, and more efficient metal catalyst, especially which can be applied to chalcone, is highly desirable.In this paper, we demonstrated that the first aza-Michael reaction of chalcone with a less nucleophilic carbamates can be accomplished on Me3SiCFFeCl3 catalyst system under very mild conditions. Apart from experimental simplicity, the advantages of this methodology are the use of a very cheap Lewis acid catalyst and the insensitivity of the reaction mixture towards air and moisture.catalyst for aza-Michael reaction of chalcone and cyclic enones with carbamates. And with the cyclic enones with carbamates in dichloromethane at room temperature were also investigated. In this conjugate addition reaction, good to excellent yields of a-amino ketones were obtained with system could also mediates aza-Michael addition of carbamates to chalcone and derivatives.These new strategies opened efficient procedures for the synthesis of a-amino ketones under mild conditions.

  18. Sulfamic Acid-Catalyzed Lead Perovskite Formation for Solar Cell Fabrication on Glass or Plastic Substrates.

    Science.gov (United States)

    Guo, Yunlong; Sato, Wataru; Shoyama, Kazutaka; Nakamura, Eiichi

    2016-04-27

    Lead perovskite materials such as methylammonium triiodoplumbate(II) (CH3NH3PbI3, PV) are promising materials for printable solar cell (SC) applications. The preparation of PV involves a series of energetically costly cleavages of the μ-iodo bridges via conversion of a mixture of PbI2 (PI) and methylammonium iodide (CH3NH3I, MAI) in N,N-dimethylformamide (DMF) into a precursor solution containing a polymeric strip of a plumbate(II) dimer [(MA(+))2(PbI3(-))2·(DMF)2]m, which then produces a perovskite film with loss of DMF upon spin-coating and heating of the substrate. We report here that the PI-to-PV conversion and the PV crystal growth to micrometer size can be accelerated by a small amount of zwitterionic sulfamic acid (NH3SO3, SA) and that sulfamic acid facilitates electron transfer to a neighboring electron-accepting layer in an SC device. As a result, an SC device on indium tin oxide (ITO)/glass made of a 320 nm thick PV film using 0.7 wt % SA showed a higher short-circuit current, open-circuit voltage, and fill factor and hence a 22.5% higher power conversion efficiency of 16.02% compared with the device made without SA. The power conversion efficiency value was reproducible (±0.3% for 25 devices), and the device showed very small hysteresis. The device without any encapsulation showed a respectable longevity on a shelf under nitrogen under ambient light. A flexible device similarly fabricated on ITO/poly(ethylene naphthalate) showed an efficiency of 12.4%. PMID:27054265

  19. 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.

  20. Ruthenium-Catalyzed Selective Hydrogenation of bis-Arylidene Tetramic Acids. Application to the Synthesis of Novel Structurally Diverse Pyrrolidine-2,4-diones

    Directory of Open Access Journals (Sweden)

    Olga Igglessi-Markopoulou

    2011-07-01

    Full Text Available Catalytic hydrogenation of 3,5-bis-arylidenetetramic acids, known for their biological activity, has been developed. The chemoselective ruthenium-catalyzed reduction of the exocyclic carbon-carbon double bonds on pyrrolidine-2,4-dione ring system, containing other reducible functions, has been investigated. Depending on the substrate the yield of the hydrogenation process can reach up to 95%. The structural elucidation has been established using NMR and HRMS spectral data.

  1. Visible-Light Photoredox-Catalyzed Giese Reaction: Decarboxylative Addition of Amino Acid Derived α-Amino Radicals to Electron-Deficient Olefins

    KAUST Repository

    Millet, Anthony

    2016-06-20

    A tin- and halide-free, visible-light photoredox-catalyzed Giese reaction was developed. Primary and secondary α-amino radicals were generated readily from amino acids in the presence of catalytic amounts of an iridium photocatalyst. The reactivity of the α-amino radicals has been evaluated for the functionalization of a variety of activated olefins. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

  2. Progressive deconstruction of Arundo donax Linn. to fermentable sugars by acid catalyzed ionic liquid pretreatment.

    Science.gov (United States)

    You, Ting-Ting; Zhang, Li-Ming; Xu, Feng

    2016-01-01

    Acid enhanced ionic liquid (IL) 1-n-butyl-3-methylimidazolium chloride ([C4 mim]Cl) pretreatment has shown great potential for boosting the yield of sugars from biomass cost-effectively and environmental-friendly. Pretreatment with shorter processing time will promote the commercial viability. In this work, pretreatment of reduced Amberlyst catalysis time of 34 min was demonstrated to be the most effective among time-varying pretreatments, evidenced by partial removal of hemicellulose and cellulose crystal transformation of Arundo donax Linn. A higher fermentable sugar concentration of 10.42 g/L (2% substrate) was obtained after 72 h of saccharification than the others. Total processing time to reach 92% glucose yield was cut down to approximately 26 h. Progressive deconstruction of crop cell wall was occurred with increased catalysis time by gradual releasing of H3O(+) of Amberlyst. However, vast lignin re-deposited polymers on fibers could hinder further enzymatic hydrolysis. These discoveries provide new insights into a more economic pretreatment for bioethanol production. PMID:26363822

  3. Synthesis of acetals and ketals catalyzed by tungstosilicic acid supported on active carbon

    Institute of Scientific and Technical Information of China (English)

    YANG Shui-jin; DU Xin-xian; HE Lan; SUN Ju-tang

    2005-01-01

    Catalytic activity of activated carbon supported tungstosilicic acidin synthesizing 2-methyl-2-ethoxycarbonylmethyl1,3-dioxolane, 2,4-dimethyl-2-ethoxycarbonylmethyl-l,3-dioxolane, cyclohexanone ethylene ketal, cyclohexanone 1,2-propanediol ketal, butanone ethylene ketal, butanone 1,2-propanediol ketal, 2-phenyl-1,3-dioxolane, 4-methyl-2-phenyl-1,3-dioxolane,2-propyl-1,3-dioxolane, 4-methyl-2-propyl-1,3-dioxolane was reported. It has been demonstrated that activated carbon supported tungstosilicic acid is an excellent catalyst. Various factors involved in these reactions were investigated. The optimum conditions found were: molar ratio of aldehyde/ketone to glycol is 1/1.5, mass ratio of the catalyst used to the reactants is 1.0%, and reaction time is 1.0 h. Under these conditions, the yield of 2-methyl-2-ethoxycarbonylmethyl-l,3-dioxolane is 61.5%, of 2,4-dimethyl2-ethoxycarbonylmethyl-1,3-dioxolane is 69.1%, of cyclohexanone ethylene ketal is 74.6%, of cyclohexanone 1,2-propanediol ketal is 80.1%, of butanone ethylene ketal is 69.5%, of butanone 1,2-propanediol ketal is 78.5%, of 2-phenyl-1,3-dioxolane is 56.7%, of 4-methyl-2-phenyl- 1,3-dioxolane is 86.2%, of 2-propyl-1,3-dioxolane is 87.5%, of 4-methyl-2-propyl-1,3-dioxolane is 87.9%.

  4. Reaction kinetics for synthesis of sec-butyl alcohol catalyzed by acid-functionalized ionic liquid

    Institute of Scientific and Technical Information of China (English)

    Ting Qiu; Wenli Tang; Chenggang Li; Chengming Wu; Ling Li

    2015-01-01

    The acid-functionalized ionic liquid ([HSO3Pmim]HSO4) was synthesized by a two-step method. Nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FT-IR) show that the synthesis method is feasible and high purity of ionic liquid can be obtained. Using [HSO3Pmim]HSO4 as the catalyst, we studied the reaction kinetics of synthesizing sec-butyl alcohol from sec-butyl acetate and methanol by transesterification in a high-pressure batch reactor. The effects of temperature, initial molar ratio of methanol to ester, and catalyst concentration on the conversion of sec-butyl acetate were studied. Based on its possible reaction mechanism, a ho-mogeneous kinetic model was established. The results show that the reaction heatΔH is 10.94 × 103 J·mol−1, so the reaction is an endothermic reaction. The activation energies Ea+and Ea−are 60.38 × 103 and 49.44 × 103 J·mol−1, respectively.

  5. Glutamate 190 is a general acid catalyst in the 6-phosphogluconate-dehydrogenase-catalyzed reaction.

    Science.gov (United States)

    Karsten, W E; Chooback, L; Cook, P F

    1998-11-10

    Site-directed mutagenesis was used to change E190 of sheep liver 6-phosphogluconate dehydrogenase to A, D, H, K, Q, and R to probe its possible role as a general acid catalyst. Each of the mutant proteins was characterized with respect to the pH dependence of kinetic parameters. Mutations that eliminate a titrable group at position 190, result in pH-rate profiles with no observable pK on the basic side of the V/K6PG profile. Mutations that change the pK of the group at position 190 result in the expected pK perturbations in the V/K6PG profile. Kinetic parameters obtained at the pH optimum in the pH-rate profiles are consistent with a rate-limiting tautomerization of the 1,2-enediol of ribulose 5-phosphate consistent with the proposed role of E190. Data are also consistent with some participation of E190 in an isomerization required to form the active Michaelis complex.

  6. Super phosphoric acid catalyzed esterification of Palm Fatty Acid Distillate for biodiesel production: physicochemical parameters and kinetics

    Directory of Open Access Journals (Sweden)

    Metre Anand V.

    2015-03-01

    Full Text Available In the present study the esterification of palm fatty acid distillate (PFAD, a by-product from palm oil industry, in the presence of super phosphoric acid (SPA catalyst was studied. The effects of various physico-chemical parameters such as temperature, PFAD to methanol molar ratio and amount of catalyst on the conversion of biodiesel were investigated. The percent conversion of FFA and properties of the biodiesel were determined following standard methodologies. Percent conversion of biodiesel was found to increase with the increase in PFAD to methanol molar ratio and at 1:12 molar ratio and 70°C temperature 95% conversion was achieved. Thermodynamic parameters were also evaluated in terms of Gibbs free energy, enthalpy and entropy at different molar ratio and temperatures. Both pseudo first and second order irreversible kinetics were applied to a wide range of experimental data. However, according to regression coefficient (R2 the second order described better experimental behavior of kinetic data.

  7. Optimization of Two-Step Acid-Catalyzed Hydrolysis of Oil Palm Empty Fruit Bunch for High Sugar Concentration in Hydrolysate

    Directory of Open Access Journals (Sweden)

    Dongxu Zhang

    2014-01-01

    Full Text Available Getting high sugar concentrations in lignocellulosic biomass hydrolysate with reasonable yields of sugars is commercially attractive but very challenging. Two-step acid-catalyzed hydrolysis of oil palm empty fruit bunch (EFB was conducted to get high sugar concentrations in the hydrolysate. The biphasic kinetic model was used to guide the optimization of the first step dilute acid-catalyzed hydrolysis of EFB. A total sugar concentration of 83.0 g/L with a xylose concentration of 69.5 g/L and a xylose yield of 84.0% was experimentally achieved, which is in well agreement with the model predictions under optimal conditions (3% H2SO4 and 1.2% H3PO4, w/v, liquid to solid ratio 3 mL/g, 130°C, and 36 min. To further increase total sugar and xylose concentrations in hydrolysate, a second step hydrolysis was performed by adding fresh EFB to the hydrolysate at 130°C for 30 min, giving a total sugar concentration of 114.4 g/L with a xylose concentration of 93.5 g/L and a xylose yield of 56.5%. To the best of our knowledge, the total sugar and xylose concentrations are the highest among those ever reported for acid-catalyzed hydrolysis of lignocellulose.

  8. Molecular mechanism of acid-catalyzed hydrolysis of peptide bonds using a model compound.

    Science.gov (United States)

    Pan, Bin; Ricci, Margaret S; Trout, Bernhardt L

    2010-04-01

    The stability of peptide bonds is a critical aspect of biological chemistry and therapeutic protein applications. Recent studies found elevated nonenzymatic hydrolysis in the hinge region of antibody molecules, but no mechanism was identified. As a first step in providing a mechanistic interpretation, this computational study examines the rate-determining step of the hydrolytic reaction of a peptide bond under acidic pH by a path sampling technique using a model compound N-MAA. Most previous computational studies did not include explicit water molecules, whose effects are significant in solution chemistry, nor did they provide a dynamic picture for the reaction process in aqueous conditions. Because no single trajectory can be used to describe the reaction dynamics due to fluctuations at finite temperatures, a variant version of the transition path sampling technique, the aimless shooting algorithm, was used to sample dynamic trajectories and to generate an ensemble of transition trajectories according to their statistical weights in the trajectory space. Each trajectory was computed as the time evolution of the molecular system using the Car-Parrinello molecular dynamics technique. The likelihood maximization procedure and its modification were used in extracting dynamically relevant degrees of freedom in the system, and approximations of the reaction coordinate were compared. Its low log-likelihood score and poor p(B) histogram indicate that the C-O distance previously assumed as the reaction coordinate for the rate-determining step is inadequate in describing the dynamics of the reaction. More than one order parameter in a candidate set including millions of geometric quantities was required to produce a convergent reaction coordinate model; its involvement of many degrees of freedom suggests that this hydrolytic reaction step is very complex. In addition to affecting atoms directly involved in bond-making and -breaking processes, the water network also has

  9. Purification, molecular cloning, and expression of 2-hydroxyphytanoyl- CoA lyase, a peroxisomal thiamine pyrophosphate-dependent enzyme that catalyzes the carbon-carbon bond cleavage during à-oxidation of 3- methyl-branched fatty acids

    CERN Document Server

    Foulon, V; Croes, K; Waelkens, E

    1999-01-01

    Purification, molecular cloning, and expression of 2-hydroxyphytanoyl- CoA lyase, a peroxisomal thiamine pyrophosphate-dependent enzyme that catalyzes the carbon-carbon bond cleavage during à-oxidation of 3- methyl-branched fatty acids

  10. Amino acid-catalyzed seed regrowth synthesis of photostable high fluorescent silica nanoparticles with tunable sizes for intracellular studies

    International Nuclear Information System (INIS)

    Size-controlled fluorescence silica nanoparticles (NPs) are widely used for nanotoxicological studies, and diagnostic and targeted therapies. Such particles can be easily visualized and localized within cell environments and their interactions with cellular components can be monitored. We developed an amino acid-catalyzed seed regrowth technique (ACSRT) to synthesize spherical rhodamine-doped silica NPs with tunable sizes, low polydispersity index as well as high labeling efficiency and enhanced fluorescence photostability. Via ACSRT, fluorescent silica NPs can be obtained by introducing the fluorophore in seed formation step, while a precise control over particle size can be achieved by simply adjusting the concentration of reactants in the regrowth step. Unlike the conventional methods, the proposed ACSRT permits the synthesis of fluorescent silica NPs in a water-based system, without the use of any surfactants and co-surfactants. By this approach, additional linkers for covalent coupling of the fluorophore to silica matrix can be omitted, while a remarkable doping efficiency is achieved. The suitability of these particles for biomedical application is demonstrated by in vitro tests with normal and malignant bone cells. We show that the particles can be easily and unambiguously visualized by a conventional fluorescence microscope, localized, and distinguished within intracellular components. In addition, it is presented that the cellular uptake and cytotoxic profile of silica NPs are strongly correlated to the particle size, concentration, and cell line. The results of in vitro experiments demonstrate that tunable fluorescent silica NPs synthesized with ACSRT can be potentially used for toxicological assessments and nanomedical studies

  11. Amino acid-catalyzed seed regrowth synthesis of photostable high fluorescent silica nanoparticles with tunable sizes for intracellular studies

    Energy Technology Data Exchange (ETDEWEB)

    Shahabi, Shakiba; Treccani, Laura, E-mail: treccani@uni-bremen.de; Rezwan, Kurosch [University of Bremen, Advanced Ceramics (Germany)

    2015-06-15

    Size-controlled fluorescence silica nanoparticles (NPs) are widely used for nanotoxicological studies, and diagnostic and targeted therapies. Such particles can be easily visualized and localized within cell environments and their interactions with cellular components can be monitored. We developed an amino acid-catalyzed seed regrowth technique (ACSRT) to synthesize spherical rhodamine-doped silica NPs with tunable sizes, low polydispersity index as well as high labeling efficiency and enhanced fluorescence photostability. Via ACSRT, fluorescent silica NPs can be obtained by introducing the fluorophore in seed formation step, while a precise control over particle size can be achieved by simply adjusting the concentration of reactants in the regrowth step. Unlike the conventional methods, the proposed ACSRT permits the synthesis of fluorescent silica NPs in a water-based system, without the use of any surfactants and co-surfactants. By this approach, additional linkers for covalent coupling of the fluorophore to silica matrix can be omitted, while a remarkable doping efficiency is achieved. The suitability of these particles for biomedical application is demonstrated by in vitro tests with normal and malignant bone cells. We show that the particles can be easily and unambiguously visualized by a conventional fluorescence microscope, localized, and distinguished within intracellular components. In addition, it is presented that the cellular uptake and cytotoxic profile of silica NPs are strongly correlated to the particle size, concentration, and cell line. The results of in vitro experiments demonstrate that tunable fluorescent silica NPs synthesized with ACSRT can be potentially used for toxicological assessments and nanomedical studies.

  12. Highly Efficient C--N Bond Forming Reactions in Water Catalyzed by Copper(I) Iodide with Calix[4]arene Supported Amino Acid Ionic Liquid%Highly Efficient C--N Bond Forming Reactions in Water Catalyzed by Copper(I) Iodide with Calix[4]arene Supported Amino Acid Ionic Liquid

    Institute of Scientific and Technical Information of China (English)

    黄利; 金灿; 苏为科

    2012-01-01

    A novel and effective protocol has been developed for the Ullmann-type C--N coupling reaction catalyzed by calix[4]arene supported amino acid ionic liquid and copper(I) iodide in water under microwave irradiation condition The protocol uses ealix[4]arene supported amino acid ionic liquid as double function of the ligand and phase-transfer catalyst, and shows good tolerance in good to excellent yields.

  13. Synthesis of oxacyclic scaffolds via dual ruthenium hydride/Brønsted acid-catalyzed isomerization/cyclization of allylic ethers.

    Science.gov (United States)

    Ascic, Erhad; Ohm, Ragnhild G; Petersen, Rico; Hansen, Mette R; Hansen, Casper L; Madsen, Daniel; Tanner, David; Nielsen, Thomas E

    2014-03-17

    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 to enol ethers (Ru catalysis), then to oxocarbenium ions (Brønsted acid catalysis) amenable to endo cyclization with tethered nucleophiles. This methodology provides not only an attractive alternative to the traditional oxa-Pictet-Spengler reaction for the synthesis of THPIs, but also convenient access to THPI congeners and other important oxacycles such as acetals. PMID:24616060

  14. Target-catalyzed autonomous assembly of dendrimer-like DNA nanostructures for enzyme-free and signal amplified colorimetric nucleic acids detection.

    Science.gov (United States)

    He, Hongfei; Dai, Jianyuan; Duan, Zhijuan; Meng, Yan; Zhou, Cuisong; Long, Yuyin; Zheng, Baozhan; Du, Juan; Guo, Yong; Xiao, Dan

    2016-12-15

    Self-assembly of DNA nanostructures is of great importance in nanomedicine, nanotechnology and biosensing. Herein, a novel target-catalyzed autonomous assembly pathway for the formation of dendrimer-like DNA nanostructures that only employing target DNA and three hairpin DNA probes was proposed. We use the sticky-ended Y shape DNA (Y-DNA) as the assembly monomer and it was synthesized by the catalyzed hairpin assembly (CHA) instead of the DNA strand annealing method. The formed Y-DNA was equipped with three ssDNA sticky ends and two of them were predesigned to be complementary to the third one, then the dendrimer-like DNA nanostructures can be obtained via an autonomous assembly among these sticky-ended Y-DNAs. The resulting nanostructure has been successfully applied to develop an enzyme-free and signal amplified gold nanoparticle (AuNP)-based colorimetric nucleic acids assay. PMID:27498325

  15. A Ruthenium/Phosphoramidite-Catalyzed Asymmetric Interrupted Metallo-ene Reaction.

    Science.gov (United States)

    Trost, Barry M; Ryan, Michael C

    2016-03-01

    Allylic chlorides prepared from commercially available trans-1,4-dichloro-2-butene were converted to trans-disubstituted 5- and 6-membered ring systems with perfect diastereoselectivity and high enantioselectivity under chiral ruthenium catalysis. These products contain stereodefined secondary and tertiary alcohols that originate from the trapping of an alkylruthenium intermediate with adventitious water. Key to the success of this transformation was the development of a new BINOL-based phosphoramidite ligand containing bulky substitution at its 3- and 3'-positions. As a demonstration of product utility, diastereoselective Friedel-Crafts reactions were performed on the chiral benzylic alcohols in high yield and stereoselectivity. PMID:26899551

  16. Additional Nucleophile-Free FeCl3-Catalyzed Green Deprotection of 2,4-Dimethoxyphenylmethyl-Protected Alcohols and Carboxylic Acids.

    Science.gov (United States)

    Sawama, Yoshinari; Masuda, Masahiro; Honda, Akie; Yokoyama, Hiroki; Park, Kwihwan; Yasukawa, Naoki; Monguchi, Yasunari; Sajiki, Hironao

    2016-01-01

    The deprotection of the methoxyphenylmethyl (MPM) ether and ester derivatives can be generally achieved by the combinatorial use of a catalytic Lewis acid and stoichiometric nucleophile. The deprotections of 2,4-dimethoxyphenylmethyl (DMPM)-protected alcohols and carboxylic acids were found to be effectively catalyzed by iron(III) chloride without any additional nucleophile to form the deprotected mother alcohols and carboxylic acids in excellent yields. Since the present deprotection proceeds via the self-assembling mechanism of the 2,4-DMPM protective group itself to give the hardly-soluble resorcinarene derivative as a precipitate, the rigorous purification process by silica-gel column chromatography was unnecessary and the sufficiently-pure alcohols and carboxylic acids were easily obtained in satisfactory yields after simple filtration. PMID:27373632

  17. Ruthenium(III) catalyzed oxidation of sulfanilic acid by diperiodatocuprate(III) in aqueous alkaline medium. A kinetic and mechanistic approach

    Science.gov (United States)

    Munavalli, D. S.; Patil, R. K.; Chimatadar, S. A.; Nandibewoor, S. T.

    2009-12-01

    The kinetics of ruthenium(III) catalyzed oxidation of sulfanilic acid by diperiodatocuprate(III) (DPC) in alkaline medium at a constant ionic strength of (0.50 mol dm-3) has been studied spectrophoto-metrically. The reaction between sulfanilic acid and DPC in alkaline medium exhibits 1: 4 stoichiometry (sulfanilic acid: DPC). The reaction is first order with respect to [DPC] and [RuIII] and has less than unit order both in [sulfanilic acid] and [alkali]. The active species of catalyst and oxidant have been identified. Intervention of free radicals was observed in the reaction. The main products were identified by spot test and IR. Probable mechanism is proposed and discussed. The reaction constants involved in the different steps of the mechanism are calculated. The activation parameters with respect to the slow step of the mechanism are computed and discussed. Thermodynamic quantities are also determined.

  18. Hydrolysis of cellooligosaccharides catalyzed by organic acid%有机酸催化水解纤维低聚糖的研究

    Institute of Scientific and Technical Information of China (English)

    马淑玲; 彭红

    2014-01-01

    The order of catalytic activity of organic acids for hydrolysis of cellooligosaccharides is oxalic acid>maleic acid>malonic acid>acetic acid>formic acid>butanedioic acid. Butanedioic acid could not catalyze the hydrolysis of cellooligosaccharides. The catalytic activity of biatomic acids is relative to their acidity. The acid with higher acidity resulted in higher conversion of cellooligosaccharides. The hydrolysis of cellooligosaccharides catalyzed by organic acid processed step by step,glucose and cellooligosaccharides with lower degree of polymerization produced first,and the produced oligosaccharides was hydrolyzed further. When cellotriose,cellotetraose,and cellopentaose were hydrolyzed under the conditions of substrate concentration 1.5 mg/mL,oxalic acid dosage 0.05 mmol/mL,reaction time 9 h,and temperature 95℃,the product concentrations of glucose were 0.51, 0.53,and 0.13 mg/mL respectively.%有机酸催化水解纤维低聚糖的能力强弱顺序为:草酸>顺丁烯二酸>丙二酸>乙酸>甲酸>丁二酸,丁二酸不能催化水解纤维低聚糖。二元羧酸水解纤维低聚糖时的能力与其水溶液酸性强弱有关,酸性越强,催化水解能力越大,低聚糖的水解率高。有机酸水解纤维低聚糖是分步进行的,先生成葡萄糖和低一级的低聚糖,低一级的低聚糖再水解生成葡萄糖和更低一级的低聚糖。在初始低聚糖浓度为1.5 mg/mL、水解时间9 h和水解温度95℃的条件下,0.05 mmol/mL草酸分别催化水解纤维三糖、纤维四糖和纤维五糖后产物葡萄糖浓度分别为0.51、0.53和0.13 mg/mL。

  19. Synthesis, X-ray Structure and Aggregation Effect of Tetramethoxy Substituted Dibenzo[fg, op]naphthacene

    Institute of Scientific and Technical Information of China (English)

    CHENG Xiao-Hong; FU Chang-Jin

    2007-01-01

    Tetramethoxy substituted dibenzo[fg,op]naphthacene was synthesised by using Friedel-Crafts acylation, tandem Aldol-Michael solvent-free reaction and palladium catalyzed dehydrohalogenation cyclization as key steps. The X-ray structure of the product and its aggregation effect in solvent were also reported.

  20. Synthesis of bio-based methacrylic acid by decarboxylation of itaconic acid and citric acid catalyzed by solid transition-metal catalysts

    NARCIS (Netherlands)

    Notre, le J.E.L.; Witte-van Dijk, S.C.M.; Haveren, van J.; Scott, E.L.; Sanders, J.P.M.

    2014-01-01

    Methacrylic acid, an important monomer for the plastics industry, was obtained in high selectivity (up to 84%) by the decarboxylation of itaconic acid using heterogeneous catalysts based on Pd, Pt and Ru. The reaction takes place in water at 200–2508C without any external added pressure, conditions

  1. Directing Group in Decarboxylative Cross-Coupling: Copper-Catalyzed Site-Selective C-N Bond Formation from Nonactivated Aliphatic Carboxylic Acids.

    Science.gov (United States)

    Liu, Zhao-Jing; Lu, Xi; Wang, Guan; Li, Lei; Jiang, Wei-Tao; Wang, Yu-Dong; Xiao, Bin; Fu, Yao

    2016-08-01

    Copper-catalyzed directed decarboxylative amination of nonactivated aliphatic carboxylic acids is described. This intramolecular C-N bond formation reaction provides efficient access to the synthesis of pyrrolidine and piperidine derivatives as well as the modification of complex natural products. Moreover, this reaction presents excellent site-selectivity in the C-N bond formation step through the use of directing group. Our work can be considered as a big step toward controllable radical decarboxylative carbon-heteroatom cross-coupling. PMID:27439145

  2. Use of immobilized phospholipase A1-catalyzed acidolysis for the production of structured phosphatidylcholine with an elevated conjugated linoleic acid content

    OpenAIRE

    Baeza-Jiménez, R.; GonzáLez-RodríGuez, J.; Kim, In-H.; García, H. S.; Otero, C.

    2012-01-01

    Structured phosphatidylcholine (SPC) was successfully produced via immobilized phospholipase A1 (PLA1) – catalyzed acidolysis of phosphatidylcholine (PC) with conjugated linoleic acid (CLA). The effects of enzyme loading (2, 5, 10, 15 and 20%, with respect to the weight of substrates), temperature (20, 30, 40, 50 and 60 °C) and the molar ratio of substrates (1:2, 1:4, 1:6, 1:8 and 1:10, PC/CLA) were evaluated to maximize the incorporation of CLA i...

  3. 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...

  4. Reaction Between U(Ⅳ)and Nitrous Acid Catalyzed by Plutonium%Pu催化HNO2氧化U(Ⅳ)的研究

    Institute of Scientific and Technical Information of China (English)

    王浩文; 周贤明; 李高亮; 兰天; 刘金平; 常尚文; 何辉; 段红卫

    2014-01-01

    The oxidation of U(Ⅳ)by nitrous acid in the present of plutonium was studied. The influence of the concentration of nitrous acid,nitric acid,plutonium on the oxidation of U(Ⅳ)was investigated.The results show that plutonium can catalyze the reaction between U(Ⅳ)and nitrous acid.And the rate equation of the reaction between U(Ⅳ)and nitrous acid catalyzed by plutonium was obtained:-dc(U(Ⅳ))/dt=kc(U(Ⅳ))c1.3 (HNO3 )c1.3 (NO-2 ), k=(0.69±0.04)L2.6/(mol2.6 ·min)when the temperature was 29 ℃.The mechanism of the oxidation of U(Ⅳ)was discussed.%研究了Pu存在条件下 HNO2氧化 U(Ⅳ)的反应,并考察了 HNO2浓度、反应温度、HNO3浓度、Pu 浓度对 U(Ⅳ)氧化速率的影响。结果表明:Pu对 HNO2氧化 U(Ⅳ)的反应具有显著催化作用;获得了 Pu催化条件下 HNO2氧化 U(Ⅳ)的动力学方程:-dc(U(Ⅳ))/dt=kc(U(Ⅳ))c1.3(HNO3)c1.3(NO-2),得到了29℃时的反应速率常数k=(0.69±0.04)L2.6/(mol2.6·min)。并对反应历程进行了探讨。

  5. Saturation mutagenesis on Arg244 of the tryptophan C4-prenyltransferase FgaPT2 leads to enhanced catalytic ability and different preferences for tryptophan-containing cyclic dipeptides.

    Science.gov (United States)

    Fan, Aili; Li, Shu-Ming

    2016-06-01

    FgaPT2 from Aspergillus fumigatus catalyzes a Friedel-Crafts alkylation at C-4 of L-tryptophan and is involved in the biosynthesis of the ergot alkaloids fumigaclavines. Several tryptophan-containing cyclic dipeptides had also been prenylated by FgaPT2, but the turnover rate (k cat) was low. Here, we report the generation of FgaPT2 mutants by saturation mutagenesis at the amino acid residue Arg244 to improve its catalytic efficiency toward cyclic dipeptides. Thirteen mutated enzymes demonstrated up to 76-fold higher turnover number toward seven cyclic dipeptides than the non-mutated FgaPT2. More importantly, the mutated enzymes exhibited different preferences toward these substrates. This study provides a convenient approach for creation of new biocatalysts for production of C4-prenylated cyclic dipeptides. PMID:26875876

  6. Modification of diphenylamine-linked bis(oxazoline) ligands: Tuning of electronic effect and rigidity of ligand skeleton

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The electronic effect of diphenylamine-linked bis(oxazoline) ligands was tuned through introduction of electron-withdrawing bromo and nitro substituents onto the 4 and 4′ position. The variation of the NH bond acidity was determined by the different chemical shifts of NH. The catalytic activity and enantioselectivity of the modified ligands were tested in the asymmetric Friedel-Crafts alkylation of indole with β-nitrostyrene. The effect of ligand skeleton rigidity was also investigated through the synthesis of iminodibenzyl-linked bis(oxazoline) ligands and evaluation of their catalytic activity in Friedel-Crafts alkylation.

  7. Highly Efficient Esterification of an Equimolar Amount of Carboxylic Acids and Alcohols Catalyzed by ZrOCl2·8H2O

    Institute of Scientific and Technical Information of China (English)

    Sun Hong-Bin; Hua Ruimao; Yin Ying-Wu

    2004-01-01

    Esterification of carboxylic acids with alcohols is one of the most fundamental and useful transformations in organic synthesis. The most common catalysts are H2SO4 and TsOH. However,H2SO4 or TsOH-catalyzed esterification procedure has some problems such as corrosion, side reactions, difficulty in separation. Hence, recently, various solid acid catalysts such as ion-exchanged resins, molecular sieve, and heteropoly acids etc. have been employed for esterification reaction.However, the solid acid catalysts are usually not easily accessible and expensive In addition, for achieving the high yield of esters, it is usually to carry out the esterification reaction by addition of an excess of one of the reactants. Therefore it is still interesting to develop the high activity,cost-effective catalyst system.which is a commercially available and very cheap inorganic salt.The esterification was carried out in the presence of ZrOCl2. 8H2O (0.05 mol %) using equimolar amount of carboxylic acids and alcohols at room temperature or at 50℃. For example, the esterification of propionic acid with methanol at room temperature for 24 h gave methyl propionate in 81% GC yield. A higher yield of esters can be obtained by the removal of water azeotropically.The present esterification procedure has the following advantages:1) Esters can be obtained in high yield with the use of equimolar amount of carboxylic acids and alcohols.2) Esterification proceeds at room temperature, the catalyst system is suitable for the esterification of highly reactive carboxylic acids such as acrylic acid.3) It is easy to isolate and purify the esters, and the catalyst is recyclable. The complete reaction mixture becomes two phases at room temperature, the esters in the organic phase can be separated conveniently by decanting, and the catalyst in the water can be reused without any treatment.

  8. Oxidation of alkanes with m-chloroperbenzoic acid catalyzed by iron(III) chloride and a polydentate amine

    OpenAIRE

    Shul’pin, Georgiy B.; Stoeckli-Evans, Helen; Mandelli, Dalmo; Kozlov, Yuriy N.; Tesouro Vallina, Ana; Woitiski, Camile B.; Jimenez, Ricardo S.; Carvalho, Wagner A.

    2009-01-01

    Tetradentate amine N,N′-bis(2-pyridylmethylene)-1,4-diaminodiphenyl ether (compound 1) dramatically accelerates the oxidation of alkanes with MCPBA in acetonitrile catalyzed by FeCl3, whereas N,N′-bis(2-pyrrolidinmethylene)-1,4-diaminodiphenyl ether (2) does not affect the reaction. The selectivity of the reaction in the presence of 1 is noticeably higher than that in its absence. On the basis of the kinetic study and selectivity parameters a mechanism has been proposed which includes the for...

  9. Solid State Synthesis of Malonic Acid Monoanilide and Its Cyclization with Eaton′s Reagent or Polyphosphoric Acid%丙二酸单苯酰胺的固相法合成及其在Eaton试剂或多聚磷酸作用下的环化反应

    Institute of Scientific and Technical Information of China (English)

    高文涛; 侯文端; 郑美茹

    2008-01-01

    Malonic acid monoanilides (1a~1f) were prepared by reactions of aniline and substituted anilines with Meldrum's acid under solid state conditions without using catalyst, the yield was 81.0 %~92.2 %. 4-Hydroxyquinolin-2-one derivatives (2a~2f) were facially synthesized in the yields of 63.2 %~93.8 % and 56.5~81.3 % by the intramolecular Friedel-Crafts reactions of 1a~1f using Eaton's reagent (phosphoric anhydride+methylsulfonic acid) or polyphosphoric acid (PPA) as cyclization reagents. The products were characterized by IR, 1H NMR and elemental analysis.%苯胺及取代的苯胺和Meldrum's acid在固相无催化剂条件下反应,合成了丙二酸单苯酰胺(1a~1f) ,收率81.0 %~92.2 %. 化合物1a~1f在Eaton试剂(五氧化二磷+甲基磺酸)或多聚磷酸为环化试剂的条件下发生Friedel-Crafts分子内环化反应,以63.2 %~93.8 %和56.5 %~81.3 %的收率方便地得到4-羟基喹啉-2-酮衍生物(2a~2f). 产物的结构通过IR, 1H NMR和元素分析得以证实.

  10. Use of immobilized phospholipase A1-catalyzed acidolysis for the production of structured phosphatidylcholine with an elevated conjugated linoleic acid content

    Energy Technology Data Exchange (ETDEWEB)

    Baeza-Jimenez, R.; Gonzalez-Rodriguez, J.; Kim, I. H.; Gracia, H. S.; Otero, C.

    2012-11-01

    Structured phosphatidylcholine (SPC) was successfully produced via immobilized phospholipase A1 (PLA1) catalyzed acidolysis of phosphatidylcholine (PC) with conjugated linoleic acid (CLA). The effects of enzyme loading (2, 5, 10, 15 and 20%, with respect to the weight of substrates), temperature (20, 30, 40, 50 and 60 degree centigrade) and the molar ratio of substrates (1:2, 1:4, 1:6, 1:8 and 1:10, PC/CLA) were evaluated to maximize the incorporation of CLA into PC. The maximum incorporation of CLA achieved was ca. 90% for 24 h of reaction at 50 degree centigrade and 200 rpm, using a 1:4 substrate molar ratio and an enzyme loading of 15%. (Author) 30 refs.

  11. Long-chain ethers as solvents can amplify the enantioselectivity of the Carica papaya lipase-catalyzed transesterification of 2-(substituted phenoxy)propanoic acid esters.

    Science.gov (United States)

    Miyazawa, Toshifumi; Iguchi, Wakana

    2013-10-01

    The enantioselectivity of the transesterification of the 2,2,2-trifluoroethyl esters of 2-(substituted phenoxy)propanoic acids, as catalyzed by the lipase from Carica papaya, was greatly improved by using long-chain ethers, such as di-n-hexyl ether, as solvents instead of the conventional diisopropyl ether. Thus, for example, the E value was enhanced from 21 [in diisopropyl ether (0.8 ml)] to 57 [in di-n-hexyl ether (0.8 ml)] in the reaction of 2,2,2-trifluoroethyl(RS)-2-phenoxypropanoate (0.1 mmol) with methanol (0.4 mmol) in the presence of the plant lipase preparation (10 mg); it was also improved from 13 (in diisopropyl ether) to 44 (in di-n-hexyl ether) in the reaction of 2,2,2-trifluoroethyl(RS)-2-(2-chlorophenoxy)propanoate with methanol under the same reaction conditions.

  12. Camphor-10-sulfonic acid catalyzed condensation of 2-naphthol with aromatic/aliphatic aldehydes to 14-aryl/alkyl-14H-dibenzo[a,j]xanthenes

    Directory of Open Access Journals (Sweden)

    Kundu Kshama

    2014-01-01

    Full Text Available (±-Camphor-10-sulfonic acid (CSA catalyzed condensation of 2-naphthol with both aliphatic/aromatic aldehydes at 80°C yielded 14-alkyl/aryl-dibenzoxanthenes as the sole product in high yields. However, the same condensation with benzaldehyde at 25°C afforded a mixture of intermediate 1,1-bis-(2-hydroxynaphthylphenylmethane and 14-phenyl-dibenzoxanthene while the condensation with aliphatic aldehydes at 25°C furnished the corresponding 14-alkyl-dibenzoxanthenes as the sole product. Moreover, condensation of 2-naphthol with aromatic/aliphatic aldehydes with low catalyst loading (2 mol% was greatly accelerated under microwave irradiation to afford the corresponding 14-aryl/alkyl-dibenzoxanthenes as the sole product in high yields.

  13. 酶法生产共轭亚油酸的研究进展%Development of linoleate isomerase catalyzes forproduction of conjugated linoleic acid

    Institute of Scientific and Technical Information of China (English)

    张艳禾; 王春来; 刘思国; 张兰威

    2011-01-01

    共轭亚油酸(Conjugated linoleic acid,CLA)具有抗癌、抗动脉粥样硬化、减肥和免疫调节等生理活性.共轭亚油酸可以通过酶法异构化获得,将底物亚油酸异构形成具有生物活性物质-共轭亚油酸的异构酶称为亚油酸异构酶.因此,通过介绍亚油酸异构酶的来源、作用机制、酶学性质和基因工程菌生产等方面的研究进展,结合不断发展的基因工程技术,旨在提高亚油酸异构酶的活性、产量和异构化效率,以扩大反应底物范围,降低生产成本,从而推进共轭亚油酸的规模化、可持续性的工业生产.%CLA (Conjugated linoleic acid, CLA) possesses a wide range of biological activities including anti-cancer activity, anti-atherosclerosis activity, capability of helping reduce weight fat and regulate immune system. The fatty acid isomerase from bacteria, which catalyzes the isomerization of linoleic acid (LA) to CLA production, is a promising candidate for other approachs. This paper introduces the source of linoleate isomerase, the mechanism of its function as well as reviewing recent advances regarding the key property of this important enzyme. The preparation of linoleate isomerase and how to use it to produce high yield of isomers of conjugated linoleic acid with high purity are also demonstrated,which will help to realize sustainability and industrial scale production of conjugated linoleic acid.

  14. Conversion of nicotinic acid to trigonelline is catalyzed by N-methyltransferase belonged to motif B′ methyltransferase family in Coffea arabica

    Energy Technology Data Exchange (ETDEWEB)

    Mizuno, Kouichi, E-mail: koumno@akita-pu.ac.jp [Faculty of Bioresource Sciences, Akita Prefectural University, Akita City, Akita 010-0195 (Japan); Matsuzaki, Masahiro [Faculty of Bioresource Sciences, Akita Prefectural University, Akita City, Akita 010-0195 (Japan); Kanazawa, Shiho [Graduate School of Humanities and Sciences, Ochanomizu University, Otsuka, Bunkyo-ku, Tokyo 112-8610 (Japan); Tokiwano, Tetsuo; Yoshizawa, Yuko [Faculty of Bioresource Sciences, Akita Prefectural University, Akita City, Akita 010-0195 (Japan); Kato, Misako [Graduate School of Humanities and Sciences, Ochanomizu University, Otsuka, Bunkyo-ku, Tokyo 112-8610 (Japan)

    2014-10-03

    Graphical abstract: Trigonelline synthase catalyzes the conversion of nicotinic acid to trigonelline. We isolated and characterized trigonelline synthase gene(s) from Coffea arabica. - Highlights: • Trigonelline is a major compound in coffee been same as caffeine is. • We isolated and characterized trigonelline synthase gene. • Coffee trigonelline synthases are highly homologous with coffee caffeine synthases. • This study contributes the fully understanding of pyridine alkaloid metabolism. - Abstract: Trigonelline (N-methylnicotinate), a member of the pyridine alkaloids, accumulates in coffee beans along with caffeine. The biosynthetic pathway of trigonelline is not fully elucidated. While it is quite likely that the production of trigonelline from nicotinate is catalyzed by N-methyltransferase, as is caffeine synthase (CS), the enzyme(s) and gene(s) involved in N-methylation have not yet been characterized. It should be noted that, similar to caffeine, trigonelline accumulation is initiated during the development of coffee fruits. Interestingly, the expression profiles for two genes homologous to caffeine synthases were similar to the accumulation profile of trigonelline. We presumed that these two CS-homologous genes encoded trigonelline synthases. These genes were then expressed in Escherichiacoli, and the resulting recombinant enzymes that were obtained were characterized. Consequently, using the N-methyltransferase assay with S-adenosyl[methyl-{sup 14}C]methionine, it was confirmed that these recombinant enzymes catalyzed the conversion of nicotinate to trigonelline, coffee trigonelline synthases (termed CTgS1 and CTgS2) were highly identical (over 95% identity) to each other. The sequence homology between the CTgSs and coffee CCS1 was 82%. The pH-dependent activity curve of CTgS1 and CTgS2 revealed optimum activity at pH 7.5. Nicotinate was the specific methyl acceptor for CTgSs, and no activity was detected with any other nicotinate derivatives, or

  15. Conversion of nicotinic acid to trigonelline is catalyzed by N-methyltransferase belonged to motif B′ methyltransferase family in Coffea arabica

    International Nuclear Information System (INIS)

    Graphical abstract: Trigonelline synthase catalyzes the conversion of nicotinic acid to trigonelline. We isolated and characterized trigonelline synthase gene(s) from Coffea arabica. - Highlights: • Trigonelline is a major compound in coffee been same as caffeine is. • We isolated and characterized trigonelline synthase gene. • Coffee trigonelline synthases are highly homologous with coffee caffeine synthases. • This study contributes the fully understanding of pyridine alkaloid metabolism. - Abstract: Trigonelline (N-methylnicotinate), a member of the pyridine alkaloids, accumulates in coffee beans along with caffeine. The biosynthetic pathway of trigonelline is not fully elucidated. While it is quite likely that the production of trigonelline from nicotinate is catalyzed by N-methyltransferase, as is caffeine synthase (CS), the enzyme(s) and gene(s) involved in N-methylation have not yet been characterized. It should be noted that, similar to caffeine, trigonelline accumulation is initiated during the development of coffee fruits. Interestingly, the expression profiles for two genes homologous to caffeine synthases were similar to the accumulation profile of trigonelline. We presumed that these two CS-homologous genes encoded trigonelline synthases. These genes were then expressed in Escherichiacoli, and the resulting recombinant enzymes that were obtained were characterized. Consequently, using the N-methyltransferase assay with S-adenosyl[methyl-14C]methionine, it was confirmed that these recombinant enzymes catalyzed the conversion of nicotinate to trigonelline, coffee trigonelline synthases (termed CTgS1 and CTgS2) were highly identical (over 95% identity) to each other. The sequence homology between the CTgSs and coffee CCS1 was 82%. The pH-dependent activity curve of CTgS1 and CTgS2 revealed optimum activity at pH 7.5. Nicotinate was the specific methyl acceptor for CTgSs, and no activity was detected with any other nicotinate derivatives, or with

  16. Bispalladacycle-catalyzed Brønsted acid/base-promoted asymmetric tandem azlactone formation-Michael addition.

    Science.gov (United States)

    Weber, Manuel; Jautze, Sascha; Frey, Wolfgang; Peters, René

    2010-09-01

    Cooperative activation by a soft bimetallic catalyst, a hard Brønsted acid, and a hard Brønsted base has allowed the formation of highly enantioenriched, diastereomerically pure masked alpha-amino acids with adjacent quaternary and tertiary stereocenters in a single reaction starting from racemic N-benzoylated amino acids. The products can, for example, be used to prepare bicyclic dipeptides. PMID:20715774

  17. HPLC-ESI-MS/MS analysis of oxidized di-caffeoylquinic acids generated by metalloporphyrin-catalyzed reactions

    OpenAIRE

    Michel D. Santos; Norberto P. Lopes; Yassuko Iamamoto

    2008-01-01

    This paper reports an HPLC-ESI-MS/MS investigation on the oxidation of 3,5- and 4,5- dicaffeoylquinic acid using iron(III) tetraphenylporphyrin chloride as catalyst. Two major mono-oxidised products of the quinic acid moiety have been identified for both compounds. However, only the 4,5-derivative afforded two different tri-oxo products. Thus, it seems that the oxidation pattern depends on the number and positions of the caffeic acid moieties present in caffeoylquinic acid molecules.

  18. HPLC-ESI-MS/MS analysis of oxidized di-caffeoylquinic acids generated by metalloporphyrin-catalyzed reactions

    Directory of Open Access Journals (Sweden)

    Michel D. Santos

    2008-01-01

    Full Text Available This paper reports an HPLC-ESI-MS/MS investigation on the oxidation of 3,5- and 4,5- dicaffeoylquinic acid using iron(III tetraphenylporphyrin chloride as catalyst. Two major mono-oxidised products of the quinic acid moiety have been identified for both compounds. However, only the 4,5-derivative afforded two different tri-oxo products. Thus, it seems that the oxidation pattern depends on the number and positions of the caffeic acid moieties present in caffeoylquinic acid molecules.

  19. Enzymatic α-glucuronylation of maltooligosaccharides using α-glucuronic acid 1-phosphate as glycosyl donor catalyzed by a thermostable phosphorylase from Aquifex aeolicus VF5.

    Science.gov (United States)

    Umegatani, Yuta; Izawa, Hironori; Nawaji, Mutsuki; Yamamoto, Kazuya; Kubo, Akiko; Yanase, Michiyo; Takaha, Takeshi; Kadokawa, Jun-ichi

    2012-03-01

    This paper describes thermostable phosphorylase-catalyzed α-glucuronylation of maltooligosaccharides for the direct synthesis of anionic oligosaccharides having a glucuronic acid residue at the non-reducing end. When the reaction of α-glucuronic acid 1-phosphate (GlcA-1-P) as a glycosyl donor and maltotriose as a glycosyl acceptor was performed in the presence of thermostable phosphorylase from Aquifex aeolicus VF5, high performance anion exchange chromatography analysis of the reaction mixture suggested the production of a glucuronylated tetrasaccharide, whose structure was also confirmed by the MALDI-TOF MS measurement of the crude products. Furthermore, treatment of the crude products with glucoamylase supported that the α-glucuronic acid unit was positioned at the non-reducing end of the tetrasaccharide and (1)H NMR analysis suggested that it was bound in an α-(1→4)-linkage. When the α-glucuronylation of maltotetraose using GlcA-1-P was conducted, α-glucuronylated oligosaccharides with various degrees of polymerization were produced. On the other hand, the α-glucuronylation of maltotetraose using GlcA-1-P in the presence of potato phosphorylase did not occur at all, indicating no recognition of GlcA-1-P by potato phosphorylase. PMID:22265379

  20. DFT Study of Solvent Effects in Acid-Catalyzed Diels-Alder Cycloadditions of 2,5-Dimethylfuran and Maleic Anhydride.

    Science.gov (United States)

    Salavati-fard, Taha; Caratzoulas, Stavros; Doren, Douglas J

    2015-09-24

    Density functional theory electronic structure calculations were used to explore the mechanism for the Diels-Alder reaction between 2,5-dimethylfuran and maleic anhydride (MA). Reaction paths are reported for uncatalyzed and Lewis and Brønsted acid-catalyzed reactions in vacuum and in a broad range of solvents. The calculations show that, while the uncatalyzed Diels-Alder reaction is thermally feasible in vacuum, a Lewis acid (modeled as Na(+)) lowers the activation barrier by interacting with the dienophile (MA) and decreasing the HOMO-LUMO gap of the reactants. A Brønsted acid (modeled as a proton) can bind to a carbonyl oxygen in MA, changing the reaction mechanism from concerted to stepwise and eliminating the activation barrier. Solvation effects were studied with the SMD model. Electrostatic effects play the largest role in determining the solvation energy of the transition state, which tracks the net dipole moment at the transition state. For the uncatalyzed reaction, the dipole moment is largely determined by charge transfer between the reactants, but in the reactions with ionic catalysts, there is no simple relationship between solvation of the transition state and charge transfer between the reactants. Nonelectrostatic contributions to solvation of the reactants and transition state also make significant contributions to the activation energy. PMID:26331220

  1. Transition metal-catalyzed oxidative double bond cleavage of simple and bio-derived alkenes and unsaturated fatty acids

    NARCIS (Netherlands)

    Spannring, Peter; Bruijnincx, Pieter C. A.; Weckhuysen, Bert. M.; Klein Gebbink, Bert

    2014-01-01

    The oxidative cleavage of the C=C double bond in unsaturated fatty acids into aldehydes or carboxylic acids is a reaction of current interest in biomass valorization. The products of this reaction, which is currently being performed on an industrial scale by means of ozonolysis, can be applied for t

  2. Aspergillus niger lipase-catalyzed synthesis of high contentlauric acid monoglyceride%黑曲霉脂肪酶合成单月桂酸甘油酯

    Institute of Scientific and Technical Information of China (English)

    邓颖颖; 杨哪; 徐学明

    2012-01-01

    A lipase from Aspergillus niger has been found with strong catalytic activity and selectivity.In order to prove the lipase high selectivity,it was used to catalyze the fatty acids and glycerin synthetic fatty acid glyceride and optimize the reaction process parameters.The results showed that when the ratio of glycerol to lauric acid 1:1.5,the lipase dosage 0.5%(W/W),the water dosage 3%(W/W)based on the reactant which was employed in the reacting system,the conversion rate of lauric acid could reach 91.2% at 50℃ for 12h reaction.The content of lauric acid monoglycerid was about 70% in the reacting production.%从黑曲霉中提出了一种具有很高催化活性和选择性的脂肪酶,为证明这种脂肪酶的高选择性,用此酶直接催化甘油和月桂酸反应合成单月桂酸甘油酯,并且优化了反应的工艺参数。实验表明,采用甘油月桂酸摩尔比为1∶1.5,脂肪酶与底物质量比为0.5%,水与底物质量比为3%的条件在50℃下反应12h,可使月桂酸转化率达到91.2%,单酯含量高达70%。

  3. Photo-degradation of Acid-red 3B dye catalyzed by TiO2 nanotubes

    Institute of Scientific and Technical Information of China (English)

    JIANG Fang; ZHENG Shou-rong; ZHENG Zheng; XU Zhao-yi; WANG Yan-jin

    2006-01-01

    TiO2 nanotube precursor was synthesized by the hydrothermal reaction of TiO2 powders with NaOH solution and the properties of the nanotube materials were tuned using different post-treatments. Transmission electron microscopic (TEM) observation revealed that the nanotube could be obtained by either a direct rinse with acid solution or rinse with distilled water followed by acid solution. The results of X-ray diffraction (XRD) and inductively coupled plasma (ICP) analysis indicated that the nanotube material on the post-treatment. The results of the photocatalytic reaction showed that the degradation of Acid-red 3B dye fitted pseudo-zero-order kinetics and TiO2 nanotube prepared under direct rinse with acid solution exhibited a higher catalytic efficiency compared to other catalysts.

  4. Biomimetic Decarboxylation of Carboxylic Acids with PhI(OAc)2 Catalyzed by Manganese Porphyrin [Mn(TPP)OAcl

    Institute of Scientific and Technical Information of China (English)

    GHOLAM REZA Karimipour; ROXANA Ahmadpour

    2008-01-01

    Manganese(Ⅲ) meso-tetraphenylporphyrin acetate [Mn(TPP)OAc] served as an effective catalyst for the oxidative decarboxylation of carboxylic acids with (diacetoxyiodo)benzene [Phl(OAc)2] in CH2C12-H2O(95:5,volume ratio),The aryl substituted acetic acids are more reactive than the less electron rich linear carboxylic acids in the presence of catalyst Mn(TPP)OAc,In the former case,the formation of carbonyl products was complete within just a few minutes with >97% selectivities,and no further oxidation of the produced aldehydes was achieved under these catalytic conditions,This method provides a benign procedure owing to the utilization of low toxic(diacetoxyiodo)benzene,biologically relevant manganese porphyrins,and carboxylic acids.

  5. Effect of Solvent and Acid-Base on Palladium(ll)-catalyzed Dicarbonylation of Terminal Acetylenes: a General, Efficient andStereoselective Synthesis of Maleic Diesters and Maleic Anhydrides

    Institute of Scientific and Technical Information of China (English)

    JIANG, Huan-Feng; LI, JiN-Heng; CHEN, Ming-Cai

    2001-01-01

    The productions of maleic diesters and maleic anhydrises depend on the effect of solvint and acid-bade of solvent and acid-base in palladium-catalyzed dicarbonylation of terminal acetylenes. For primaryand secondary alcohol in benzene.only maleic diesters wereobtained stereospecifically from the sicabonylation ofacetylenes in the presence of PdCl2,and NaHCO3.For tERTIARy alcohols,maleic anhydrides were synthesized selectively.

  6. Synthesis of high molecular weight polylactic acid from aqueous lactic acid co-catalyzed by tin(II)chloride dihydrate and succinic anhydride

    Institute of Scientific and Technical Information of China (English)

    LEI Ziqiang; BAI Yanbin; WANG Shoufeng

    2005-01-01

    Polylactic acid was synthesized from commercial available cheap aqueous lactic acid (85%―90% w/w) using succinic anhydride and SnCl2·2H2O as catalyst in the absence of organic solvents. As a result, polylactic acid with a molecular weight of 60000 was prepared in 10 h. The new procedure is much simple, cheap and outstanding in that the start material is aqueous lactic acid; the catalytic system is environmentally benign.

  7. Evolution of diterpene metabolism: Sitka spruce CYP720B4 catalyzes multiple oxidations in resin acid biosynthesis of conifer defense against insects.

    Science.gov (United States)

    Hamberger, Björn; Ohnishi, Toshiyuki; Hamberger, Britta; Séguin, Armand; Bohlmann, Jörg

    2011-12-01

    Diterpene resin acids (DRAs) are specialized (secondary) metabolites of the oleoresin defense of conifers produced by diterpene synthases and cytochrome P450s of the CYP720B family. The evolution of DRA metabolism shares common origins with the biosynthesis of ent-kaurenoic acid, which is highly conserved in general (primary) metabolism of gibberellin biosynthesis. Transcriptome mining in species of spruce (Picea) and pine (Pinus) revealed CYP720Bs of four distinct clades. We cloned a comprehensive set of 12 different Sitka spruce (Picea sitchensis) CYP720Bs as full-length cDNAs. Spatial expression profiles, methyl jasmonate induction, and transcript enrichment in terpenoid-producing resin ducts suggested a role of CYP720B4 in DRA biosynthesis. CYP720B4 was characterized as a multisubstrate, multifunctional enzyme by the formation of oxygenated diterpenoids in metabolically engineered yeast, yeast in vivo transformation of diterpene substrates, in vitro assays with CYP720B4 protein produced in Escherichia coli, and alteration of DRA profiles in RNA interference-suppressed spruce seedlings. CYP720B4 was active with 24 different diterpenoid substrates, catalyzing consecutive C-18 oxidations in the biosynthesis of an array of diterpene alcohols, aldehydes, and acids. CYP720B4 was most active in the formation of dehydroabietic acid, a compound associated with insect resistance of Sitka spruce. We identified patterns of convergent evolution of CYP720B4 in DRA metabolism and ent-kaurene oxidase CYP701 in gibberellin metabolism and revealed differences in the evolution of specialized and general diterpene metabolism in a gymnosperm. The genomic and functional characterization of the gymnosperm CYP720B family highlights that the evolution of specialized metabolism involves substantial diversification relative to conserved, general metabolism. PMID:21994349

  8. Evolution of Diterpene Metabolism: Sitka Spruce CYP720B4 Catalyzes Multiple Oxidations in Resin Acid Biosynthesis of Conifer Defense against Insects1[C][W][OA

    Science.gov (United States)

    Hamberger, Björn; Ohnishi, Toshiyuki; Hamberger, Britta; Séguin, Armand; Bohlmann, Jörg

    2011-01-01

    Diterpene resin acids (DRAs) are specialized (secondary) metabolites of the oleoresin defense of conifers produced by diterpene synthases and cytochrome P450s of the CYP720B family. The evolution of DRA metabolism shares common origins with the biosynthesis of ent-kaurenoic acid, which is highly conserved in general (primary) metabolism of gibberellin biosynthesis. Transcriptome mining in species of spruce (Picea) and pine (Pinus) revealed CYP720Bs of four distinct clades. We cloned a comprehensive set of 12 different Sitka spruce (Picea sitchensis) CYP720Bs as full-length cDNAs. Spatial expression profiles, methyl jasmonate induction, and transcript enrichment in terpenoid-producing resin ducts suggested a role of CYP720B4 in DRA biosynthesis. CYP720B4 was characterized as a multisubstrate, multifunctional enzyme by the formation of oxygenated diterpenoids in metabolically engineered yeast, yeast in vivo transformation of diterpene substrates, in vitro assays with CYP720B4 protein produced in Escherichia coli, and alteration of DRA profiles in RNA interference-suppressed spruce seedlings. CYP720B4 was active with 24 different diterpenoid substrates, catalyzing consecutive C-18 oxidations in the biosynthesis of an array of diterpene alcohols, aldehydes, and acids. CYP720B4 was most active in the formation of dehydroabietic acid, a compound associated with insect resistance of Sitka spruce. We identified patterns of convergent evolution of CYP720B4 in DRA metabolism and ent-kaurene oxidase CYP701 in gibberellin metabolism and revealed differences in the evolution of specialized and general diterpene metabolism in a gymnosperm. The genomic and functional characterization of the gymnosperm CYP720B family highlights that the evolution of specialized metabolism involves substantial diversification relative to conserved, general metabolism. PMID:21994349

  9. Studies of manufacturing controlled-release graphene acid and catalyzing synthesis of chalcone with Claisen-Schmidt condensation reaction

    Science.gov (United States)

    Li, Jihui; Feng, Jia; Li, Mei; Wang, Qiaolian; Su, Yumin; Jia, Zhixin

    2013-07-01

    In the paper, graphene acid (GA) was manufactured, using flake graphite as raw material, and the acidity and the structure of GA were characterized as well as. Then, chalcone was synthesized in the presence of GA, using acetophenone and benzaldehyde as the reactant. The results showed that the acidity of GA was for pH = 1.12 in aqueous solution, and it was structured by the graphene sheets with the spaces between the graphene sheet and the graphene sheet and sulfuric acid (H2SO4) and acetic acid (CH3CO2H) inside the spaces. At the same time, the results also exhibited that the chalcone yield was able to reach 60.36% when GA dosage was 5 g, and the chalcone yields could attain apart 60.36, 52.05 and 31.16% when 5 g of GA was used thrice. This shows that GA is not only a high-performance catalyst, but also a controlled-release catalyst.

  10. Evidence for a transient peroxynitro acid in the reaction catalyzed by nitronate monooxygenase with propionate 3-nitronate.

    Science.gov (United States)

    Smitherman, Crystal; Gadda, Giovanni

    2013-04-16

    Nitronate monooxygenase is a flavin-dependent enzyme that catalyzes the denitrification of propionate 3-nitronate (P3N) and other alkyl nitronates. The enzyme was previously known as 2-nitropropane dioxygenase, until its reclassification in 2010 by the IUBMB. Physiologically, the monooxygenase from fungi protects the organism from the environmental occurrence of P3N, which shuts down the Krebs cycle by inactivating succinate dehydrogenase and fumarase. The inhibition of these enzymes yields severe neurological disorders or death. Here, we have used for the first time steady-state and rapid kinetics, viscosity and pH effects, and time-resolved absorbance spectroscopy of the enzyme in turnover with P3N and the substrate analogue ethyl nitronate (EN) to elucidate the mechanism of the reaction. A transient increase in absorbance at ∼300 nm, never reported before, was seen during steady-state turnover of the enzyme with P3N and oxygen, with no concomitant changes between 400 and 600 nm. The transient species was not detected when oxygen was absent. Anaerobic reduction of the enzyme with P3N yielded anionic flavosemiquinone and was fast (e.g., ≥1900 s(-1)). Steady-state kinetics demonstrated that oxygen reacts before the release of the product of P3N oxidation from the enzyme. No pH effects were seen with P3N on kcat/Km, kcat/Koxygen, and kcat; in contrast, with EN, the kcat/Km and kcat decreased with increasing pH defining two plateaus and a pKa ∼ 8.0. Solvent viscosity at the pH optima suggested product release as being partially controlling the overall rate of turnover with the physiological substrate and its analogue. A mechanism that satisfies the kinetic results is proposed. PMID:23530838

  11. Diastereoselective synthesis of substituted hexahydrobenzo[de]isochromanes and evaluation of their antileishmanial activity.

    Science.gov (United States)

    Saikia, Anil K; Sultana, Sabera; Devi, Ngangbam Renubala; Deka, Manash J; Tiwari, Kartikeya; Dubey, Vikash K

    2016-01-21

    Hexahydrobenzo[de]isochromanes and hexahydropyrano[3,4,5-ij]isoquinolines can be efficiently synthesized via Friedel Crafts and oxa Pictet-Spengler reaction of acrylyl enol ethers mediated by triflic acid in good yields. The reaction is highly stereoselective. Two of the hexahydrobenzo[de]isochromanes are found to have moderate antileishmanial activity. PMID:26625982

  12. A simple, effective, green method for regioselective 3-acylation of unprotected indoles

    DEFF Research Database (Denmark)

    Tran, Phuong Huong; Tran, Hai N.; Hansen, Poul Erik;

    2015-01-01

    A fast and green method is developed for regioselective acylation of indoles in the 3-position without the need for protection of the NH position. The method is based on Friedel-Crafts acylation using acid anhydrides. The method has been optimized, and Y(OTf)3 in catalytic amounts is found...

  13. The decolorization of Acid Orange II in non-homogeneous Fenton reaction catalyzed by natural vanadium-titanium magnetite

    Energy Technology Data Exchange (ETDEWEB)

    Liang Xiaoliang; Zhong Yuanhong [Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 510640 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China); Zhu Sanyuan; Zhu Jianxi; Yuan Peng [Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 510640 (China); He Hongping, E-mail: hehp@gig.ac.cn [Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 510640 (China); Zhang Jing [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)

    2010-09-15

    The catalytic activity of natural vanadium-titanium magnetite was investigated in the decolorization of Acid Orange II by non-homogeneous Fenton process. The natural catalysts purified by magnetic separation were characterized using X-ray diffraction (XRD), polarizing microscope, X-ray absorption fine structure (XAFS) analysis and Moessbauer spectroscopy. The obtained results show that the natural samples after magnetic separation mainly contain titanomagnetite, with a small amount of ilmenite and chlorite. Titanomagnetite is doped with vanadium, whose the valency is mainly +3 and occupies the octahedral site. Batch decolorization studies were performed to evaluate the influences of various experimental parameters like initial pH, the amount of catalyst and initial concentration of hydrogen peroxide on the decolorization efficiency of Acid Orange II. The decolorization of the dye mainly relied on degradation. The degradation efficiency was strongly dependent on pH of the medium where it increased as the pH decreased in acid range. The increase of catalyst and hydrogen peroxide could accelerate the degradation. The catalytic property of natural vanadium-titanium magnetite in the degradation of Acid Orange II was stronger than that of synthetic magnetite (Fe{sub 3}O{sub 4}). The catalytic activity of the natural samples was greatly related to the titanomagnetite content. The degradation process was dominated by heterogeneous Fenton reaction, complying with pseudo-first-order rate law. The natural catalyst has a good catalytic stability.

  14. N-Arylation of azaheterocycles with aryl and heteroaryl halides catalyzed by iminodiacetic acid resin-chelated copper complex

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Iminodiacetic acid resin-chelated copper(Ⅱ) complex is effective in cross-coupling reactions between azaheterocycles and aryl or heteroaryl halides,providing N-arylated products in good to excellent yields.The copper catalyst is air stable and can be readily recovered and reused with minimal loss of activity for three runs.

  15. Erbium trifluoromethanesulfonate-catalyzed Friedel–Crafts acylation using aromatic carboxylic acids as acylating agents under monomode-microwave irradiation

    DEFF Research Database (Denmark)

    Tran, Phuong Hoang; Hansen, Poul Erik; Nguyen, Hai Truong;

    2015-01-01

    Erbium trifluoromethanesulfonate is found to be a good catalyst for the Friedel–Crafts acylation of arenes containing electron-donating substituents using aromatic carboxylic acids as the acylating agents under microwave irradiation. An effective, rapid and waste-free method allows the preparation...... of a wide range of aryl ketones in good yields and in short reaction times with minimum amounts of waste...

  16. SYNTHESIS OF METHYL TERT-BUTYL ETHER CATALYZED BY ACIDIC ION-EXCHANGE RESINS - INFLUENCE OF THE PROTON ACTIVITY

    NARCIS (Netherlands)

    PANNEMAN, HJ; BEENACKERS, AACM

    1995-01-01

    The catalytic activity of various strong acid ion-exchange resins on the synthesis of methyl tert-butyl ether (MtBE) from methanol and isobutene has been investigated. Relative to Amberlyst 15, Kastel CS 381 and Amberlyst CSP have similar rate constants, whereas Duolite ES 276 and Amberlyst XE 307 h

  17. Lipase-Catalyzed Production of 6-O-cinnamoyl-sorbitol from D-sorbitol and Cinnamic Acid Esters.

    Science.gov (United States)

    Kim, Jung-Ho; Bhatia, Shashi Kant; Yoo, Dongwon; Seo, Hyung Min; Yi, Da-Hye; Kim, Hyun Joong; Lee, Ju Hee; Choi, Kwon-Young; Kim, Kwang Jin; Lee, Yoo Kyung; Yang, Yung-Hun

    2015-05-01

    To overcome the poor properties of solubility and stability of cinnamic acid, cinnamate derivatives with sugar alcohols were produced using the immobilized Candida antarctica lipase with vinyl cinnamate and D-sorbitol as substrate at 45 °C. Immobilized C. antarctica lipase was found to synthesize 6-O-cinnamoyl-sorbitol and confirmed by HPLC and (1)H-NMR and had a preference for vinyl cinnamate over other esters such as allyl-, ethyl-, and isobutyl cinnamate as co-substrate with D-sorbitol. Contrary to D-sorbitol, vinyl cinnamate, and cinnamic acid, the final product 6-O-cinnamoyl-sorbitol was found to have radical scavenging activity. This would be the first report on the biosynthesis of 6-O-cinnamoyl-sorbitol with immobilized enzyme from C. antarctica.

  18. Aza-Michael addition reactions between nitroolefins and benzotriazole catalyzed by MCM-41 immobilized heteropoly acids in water

    Institute of Scientific and Technical Information of China (English)

    Shao-Lei Xie; Yong-Hai Hui; Xiang-Ju Long; Chang-Chun Wang; Zheng-Feng Xie

    2013-01-01

    MCM-41 supported heteropoly acids (HPAs) catalysts were synthesized,characterized and their catalytic activity was evaluated in an aza-Michael addition reaction between nitroolefins and benzotriazole in water at room temperature.50 wt% PW/MCM-41 showed the highest activity (up to 96% yield).The catalyst was used in six consecutive experiments without obvious loss of activity,confirming the success of the anchoring process and the catalyst stability.

  19. Efficient Synthesis of Functionalized 1-oxo-1-phenyl-2-acetic Acids through Ru(II)-catalyzed Transfer Hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaowei; Gong, Binwei; Meng, Yanqiu [Shenyang Univ. of Chemical Technology, Shenyang (Korea, Republic of); Yan, Yunnan [Gannan Medical Univ., Ganzhou (Korea, Republic of); Tang, Xiaobo; Eric Xu, H.; Yi, Wei [Chinese Academy of Sciences, Shanghai (China); Li, Qiu [Univ. of Science and Technology of China, Suzhou (China)

    2013-10-15

    A new and alternative method for the efficient synthesis of indanylacetic acid 2 has been developed. The methodology used RuCl(p-cymene)[(R,R)-TsDPEN] as the catalyst and formic acid-triethylamine as the hydrogen source at room temperature under solvent-free conditions, and the reactions have excellent chemoselectivity and good compatibility of substrates. Used our developed method as the starting step, gram scale synthesis of GR24 was achieved smoothly with an overall yield of 72%. All the results suggested that further development of such methodology may be of interest. Further work to establish the mechanistic reasons for selectivity and to further explore the synthetic scope of this mode of transfer hydrogenation is in progress. The synthetic SL analog, GR24 is a very potent germination stimulant, which is widely used in parasitic weed research to stimulate germination and as a standard for comparison of new germinating agents. Owing to the prevalence of GR24, its total synthesis constitutes a hot area of research. So far all known synthetic routes of GR24 used indanylacetic acid 2 as a key intermediate, for which very few methods of building compound 2 have been reported.

  20. Experimental and Kinetic Modeling Studies on the Sulfuric Acid Catalyzed Conversion of D-Fructose to 5-Hydroxymethylfurfural and Levulinic Acid in Water

    NARCIS (Netherlands)

    Fachri, Boy A.; Abdilla, Ria M.; van de Bovenkamp, Henk H.; Rasrendra, Carolus B.; Heeres, Hero J.

    2015-01-01

    Levulinic acid (LA) and 5-hydroxymethylfurfural (HMF) have been identified as promising biomass-derived platform chemicals. A kinetic study on the conversion of D-fructose to HMF and LA in water using sulfuric acid as the catalyst has been performed in batch setups. The experiments were carried out

  1. H8-BINOL chiral imidodiphosphoric acids catalyzed enantioselective synthesis of dihydroindolo-/-pyrrolo[1,2-a]quinoxalines.

    Science.gov (United States)

    Fan, Yan-Sen; Jiang, Yi-Jun; An, Dong; Sha, Di; Antilla, Jon C; Zhang, Suoqin

    2014-12-01

    The first enantioselective synthesis of 5,6-dihydroindolo[1,2-a]quinoxalines is achieved by using a newly developed H8-BINOL-type imidodiphosphoric acid catalyst with low catalyst loading through efficient Pictet-Spengler-type reactions of indolyl anilines with ketones. This methodology also generates phenyl-4,5-dihydropyrrolo[1,2-a]quinoxalines with high yields and excellent enantioselectivities. Moreover, this method was utilized to synthesize an HIV-1 inhibitor with high yield and good enantioselectivity through a one-step procedure. PMID:25415871

  2. One-Pot Synthesis of 5-Alkoxycarbonyl-4-aryl-3,4-dihydropyrimidin-2- ones Catalyzed by Phosphotungstic Acid

    Institute of Scientific and Technical Information of China (English)

    JIN Tong-Shou; XIAO Jin-Chong; LI Tong-Shuang

    2003-01-01

    @@ Many dihydropyrimidinones and their derivatives play an important role in medicine due to their therapeutic and pharmacological properties. [1] They have emerged as the integral backbones of several calcium channel blockers, antihypertensive agents, alpha-1α-antagonists. [2] Strategies for the synthesis of dihydropyrimidinone nucleus have varied from one-pot to multistep approaches. Although high yields can be achieved by the following complex multistep procedures, these methods lack the simplicity comparing with Biginelli protocol which firstly reported by Biginelli by one-pot condensation of aryl aldehyde, β-ketoesters and urea with catalytic acid in 1993, and these multistep methods suffer from low yields particularly for substituted aromatic aldehyde.

  3. Catalyzed Ester Synthesis Using Candida rugosa Lipase Entrapped by Poly(N-isopropylacrylamide-co-itaconic Acid) Hydrogel

    OpenAIRE

    2014-01-01

    This study reports the synthesis of polymeric matrices based on N-isopropylacrylamide and itaconic acid and its application for immobilization of lipase from Candida rugosa. The lipase was immobilized by entrapment method. Free and immobilized lipase activities, pH and temperature optima, and storage stability were investigated. The optimum temperature for free and entrapped lipase was found to be 40 and 45°C, while the optimum pH was observed at pH 7 and 8, respectively. Both hydrolytic acti...

  4. Impact of zeolite aging in hot liquid water on activity for acid-catalyzed dehydration of alcohols

    Energy Technology Data Exchange (ETDEWEB)

    Vjunov, Aleksei; Derewinski, Miroslaw A.; Fulton, John L.; Camaioni, Donald M.; Lercher, Johannes A.

    2015-08-19

    The catalytic performance of zeolite in aqueous medium depends on a multitude of factors, such as the concentration and distribution of active sites and framework integrity. Al K–edge extended X–ray absorption fine structure and 27Al MAS NMR spectroscopies in combination with DFT calculations are used to determine the distribution of tetrahedral Al sites both qualitatively and quantitatively for both parent and 48 h 160 ºC water treated HBEA catalysts. There is no evidence of Al coordination modification after aging in water. The distribution and concentration of Al T–sites, active centers for the dehydration of cyclohexanol, do not markedly impact the catalytic performance in water, because the Brønsted acidic protons are present in the form of hydrated hydronium ions and thus have very similar acid properties. The results suggest that all Brønsted acid sites are equally active in aqueous medium. The decrease of zeolite catalytic performance after water treatment is attributed to the reduced concentration of Brønsted acid sites. Increasing the stability of pore walls and decreasing the rate of Si–O–Si group hydrolysis may result in improved apparent zeolite catalytic performance in aqueous medium. Authors thank B. W. Arey (PNNL) for HIM measurements, T. Huthwelker for support during Al XAFS measurements at the Swiss Light Source (PSI, Switzerland), J. Z. Hu and S. D. Burton (PNNL) for support during NMR experiments. This work was supported by the U. S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. MD acknowledges support by the Materials Synthesis and Simulation Across Scales (MS3 Initiative) conducted under Laboratory Directed Research & Development Program at PNNL. HIM imaging and NMR experiments were performed at the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the DOE Office of Science, Office of Biological

  5. Dehydrogenative Synthesis of Carboxylic Acids from Primary Alcohols and Hydroxide Catalyzed by a Ruthenium N-Heterocyclic Carbene Complex

    DEFF Research Database (Denmark)

    Santilli, Carola; Makarov, Ilya; Fristrup, Peter;

    2016-01-01

    Primary alcohols have been reacted with hydroxide and the ruthenium complex [RuCl2(IiPr)(p-cymene)] to afford carboxylic acids and dihydrogen. The dehydrogenative reaction is performed in toluene, which allows for a simple isolation of the products by precipitation and extraction. The transformat......Primary alcohols have been reacted with hydroxide and the ruthenium complex [RuCl2(IiPr)(p-cymene)] to afford carboxylic acids and dihydrogen. The dehydrogenative reaction is performed in toluene, which allows for a simple isolation of the products by precipitation and extraction...... reaction is most likely involved in this case. The kinetic isotope effect was determined to be 0.67 using 1-butanol as the substrate. A plausible catalytic cycle was characterized by DFT/B3LYP-D3 and involved coordination of the alcohol to the metal, β-hydride elimination, hydroxide attack...... on the coordinated aldehyde, and a second β-hydride elimination to furnish the carboxylate....

  6. FAME Production from Jatropha curcas Seed Oil via Calcium Oxide Catalyzed Transesterification and its Purification using Acid Activated Bentonite

    Directory of Open Access Journals (Sweden)

    Novizar Nazir

    2013-01-01

    Full Text Available This paper presents the study of transesterification of Jatropha curcas oil (JCO via environmentally benign process using calcium oxide as heterogeneous catalyst.  Response surface methodology (RSM based on central composite design (CCD was performed to optimize three reaction variables in this study.  The transesterification process variables were reaction time, x1 (60 minutes-120 minutes,   molar ratio of methanol: oil, x2 (5:1 – 13:1, and amount of catalyst,  x3 (0.5 % –1.50 % of mass fraction.  Since water washing method is not suitable to purify CaO synthesized fatty acid methyl esters (FAME,   the purification of as-synthesized FAME with acid-activated bentonites to eliminate the remaining calcium was also investigated.   It was found that the yield of JCO FAME could reach up to 94.35 % using the following reaction conditions: 79.33 minutes reaction time, 10.41:1 methanol:oil molar ratio and 0.99 %  catalyst at reaction temperature 65oC.  Among bentonites used in the purification,   2.5% of H2SO4-activated bentonite shows a good performance as decalcifying agent for FAME purification.  The properties of purified jatropha FAME were comparable to those of diesel and satisfied the international standard.

  7. The effect of metal ions as co-catalysts on acidic ionic liquid catalyzed single-step saccharification of corn stover in water.

    Science.gov (United States)

    Wiredu, Bernard; Amarasekara, Ananda S

    2015-01-01

    The effects of adding Cr(3+), Mn(2+), Fe(3+), Co(2+) Ni(2+), Cu(2+), Zn(2+) and La(3+) chlorides as co-catalysts to 1-(1-propylsulfonic)-3-methylimidazolium chloride acidic ionic liquid catalyzed saccharification of corn stover in aqueous medium was studied at 140-170 °C, by measuring the total reducing sugar (TRS) and glucose yields. The samples with Mn(2+), Fe(3+), Co(2+) as co-catalysts produced higher TRS yields compared to the sample without the metal ions. The Mn(2+) produced the highest catalytic effect enhancements and produced TRS yields of 68.0%, 72.9%, 90.2% and 87.9% at 140, 150, 160 and 170 °C respectively; whereas the corn stover samples without the Mn(2+) produced TRS yields of 42.9%, 52.3%, 54.4% and 53.5% at the same four temperatures. At higher temperatures of 160 and 170 °C, all metal ions studied produced significant enhancements in glucose yields, except Cr(3+). The addition of La(3+) as a co-catalyst produced the highest glucose yield improvement.

  8. Kinetics of an acid-base catalyzed reaction (aspartame degradation) as affected by polyol-induced changes in buffer pH and pK values.

    Science.gov (United States)

    Chuy, S; Bell, L N

    2009-01-01

    The kinetics of an acid-base catalyzed reaction, aspartame degradation, were examined as affected by the changes in pH and pK(a) values caused by adding polyols (sucrose, glycerol) to phosphate buffer. Sucrose-containing phosphate buffer solutions had a lower pH than that of phosphate buffer alone, which contributed, in part, to reduced aspartame reactivity. A kinetic model was introduced for aspartame degradation that encompassed pH and buffer salt concentrations, both of which change with a shift in the apparent pK(a) value. Aspartame degradation rate constants in sucrose-containing solutions were successfully predicted using this model when corrections (that is, lower pH, lower apparent pK(a) value, buffer dilution from the polyol) were applied. The change in buffer properties (pH, pK(a)) from adding sucrose to phosphate buffer does impact food chemical stability. These effects can be successfully incorporated into predictive kinetic models. Therefore, pH and pK(a) changes from adding polyols to buffer should be considered during food product development.

  9. Polarity Sensitive Bioorthogonally Applicable Far-Red Emitting Labels for Postsynthetic Nucleic Acid Labeling by Copper-Catalyzed and Copper-Free Cycloaddition.

    Science.gov (United States)

    Eördögh, Ádám; Steinmeyer, Jeannine; Peewasan, Krisana; Schepers, Ute; Wagenknecht, Hans-Achim; Kele, Péter

    2016-02-17

    Two series of new, water-soluble, membrane-permeable, far-red/NIR emitting benzothiazolium-based fluorescent labels with large Stokes' shifts were synthesized that can be conjugated to alkyne-modified biomolecules through their azide moiety via azide-alkyne cycloaddition. We have used these azide bearing labels to make fluorescent DNA constructs using copper-catalyzed "click" reaction. All dyes showed good or remarkable fluorescence intensity enhancement upon conjugation to DNA. We also investigated the possibility to incorporate the benzocyclooctyne motif through rigid (ethnynyl) or flexible (ethyl) linkers into the DNA, thus enabling copper-free labeling schemes. We observed that there is a marked difference between the two linkers applied in terms of optical properties of the labeled oligonucleotides. We have also tested the in vivo labeling potential of these newly synthesized dyes on HeLa cells previously transfected with cyclooctynylated DNA. Confocal fluorescent images showed that the dyes are all able to cross the membrane and suitable for background-fluorescence free fluorescent tagging of nucleic acids. Moreover, we have observed different accumulation of the two dye series in the endosomal particles, or in the nuclei, respectively. PMID:26786593

  10. A study of the acid-catalyzed hydrolysis of cellulose dissolved in ionic liquids and the factors influencing the dehydration of glucose and the formation of humins.

    Science.gov (United States)

    Dee, Sean J; Bell, Alexis T

    2011-08-22

    An investigation was carried out into the hydrolysis of cellulose dissolved in 1-ethyl-3-methylimidazolium chloride ([Emim][Cl]) and 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]) catalyzed by mineral acids. Glucose, cellobiose, and 5-hydroxymethylfurfural (5-HMF) were observed as the primary reaction products. The initial rate of glucose formation was determined to be of first order in the concentrations of dissolved glucan and protons and of zero order in the concentration of water. The absence of a dependence on water concentration suggests that cleavage of the β-1,4-glycosidic linkages near chain ends is irreversible. The apparent activation energy for glucose formation is 96 kJ mol(-1). The absence of oligosaccharides longer than cellobiose suggests that cleavage of interior glycosidic bonds is reversible due to the slow diffusional separation of cleaved chains in the highly viscous glucan/ionic liquid solution. Progressive addition of water during the course of glucan hydrolysis inhibited the rate of glucose dehydration to 5-HMF and the formation of humins. The inhibition of glucose dehydration is attributed to stronger interaction of protons with water than the 2-OH atom of the pyranose ring of glucose, the critical step in the proposed mechanism for the formation of 5-HMF. The reduction in humin formation associated with water addition is ascribed to the lowered concentration of 5-HMF, since the formation of humins is suggested to proceed through the condensation polymerization of 5-HMF with glucose. PMID:21809450

  11. Selective Oxidation of Glycerol to Glyceric Acid in Base-Free Aqueous Solution at Room Temperature Catalyzed by Platinum Supported on Carbon Activated with Potassium Hydroxide

    KAUST Repository

    Tan, Hua

    2016-04-18

    Pt supported on KOH-activated mesoporous carbon (K-AMC) was used to catalyze glycerol oxidation under base-free conditions at room temperature. To study the relationship between the carbon surface chemistry and the catalytic performance of the K-AMC-based Pt catalysts, different levels of surface oxygen functional groups (SOFGs) on the AMC supports were induced by thermal treatment at different temperatures under inert or H2 gas. A strong effect of the surface chemistry was observed on AMC-supported Pt catalysts for glycerol oxidation. The presence of carboxylic acid groups impedes the adsorption of glycerol, which leads to the reduction of catalytic activity, whereas the presence of high-desorption-temperature SOFGs, such as phenol, ether, and carbonyl/quinone groups, provide hydrophilicity to the carbon surface that improves the adsorption of glycerol molecules on Pt metal surface, which is beneficial for the catalytic activity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Synthesis of 1,8-Dioxo-octahydroxanthene Derivatives Catalyzed by p-Dodecylbenezenesulfonic Acid in Water

    Institute of Scientific and Technical Information of China (English)

    JIN,Tong-Shou; ZHANG,Jian-She; WANG,Ai-Qing; LI,Tong-Shuang

    2004-01-01

    @@ With the increasing concerns of the environment, more and more chemists are devoted to the research of the "green synthesis" which means that the reagent, solvent and catalyst are environmentally friendly in the organic chemical reactions. The importance of aqueous reaction is now generally recognized, and development of carbon-carbon bond-forming reactions that can be carried out in aqueous media is now one of the most challenging topics in organic synthesis.[1]Herein, we report a clean synthesis of 3,3,6,6-tetramethyl-9-aryl-1,8-dioxo-octahydroxanthene derivatives from aromatic aldehyde and 5,5-dimethyl-1,3-cyclohexadione using p-dodecylbenezenesulfonic acid (DBSA) as the catalyst in water.This method provides several advantages such as high yield, simple work-up procedure and environmental friendliness and water was chosen as a green solvent. All the products were characterized by m.p., 1H NMR, IR and elemental analyses.

  13. Hydrolysis of p-Nitrophenyl Picolinate Catalyzed by Mono-and Binuclear Transition Metal Complexes with Polyether Bridged Dihydroxamic Acid

    Institute of Scientific and Technical Information of China (English)

    李建章; 李鸿波; 冯发美; 谢家庆; 李慎新; 周波; 秦圣英

    2005-01-01

    Two polyether bridged dihydroxamic acids and their mono-and binuclear manganese(Ⅱ), zinc(Ⅱ) complexes have been synthesized and employed as models to mimic hydrolase in catalytic hydrolysis of p-nitrophenyl picolinate (PNPP). The reaction kinetics and the mechanism of hydrolysis of PNPP have been investigated. The kinetic mathematical model for PNPP cleaved by the complexes has been proposed. The effects of the different central metal ion, mono-and binuclear metal, the pseudo-macrocyclic polyether constructed by polyethoxy group of the complexes, and reactive temperature on the rate for catalytic hydrolysis of PNPP have been examined. The results showed that the transition metal dthydroxamates exhibited high catalytic activity to the hydrolysis of PNPP, the catalytic activity of binuclear complexes was higher than that of mononuclear ones, and the pseudo-macrocyclic polyether might synergetically activate H20 coordinated to metal ion with central metal ion together and promote the catalytic hydrolysis of PNPP.

  14. Hydrolysis of palm oil catalyzed by acid%棕榈油的酸催化水解工艺研究

    Institute of Scientific and Technical Information of China (English)

    张玲玲; 王晖

    2015-01-01

    以棕榈油为原料进行常压酸催化水解工艺研究。考察了反应时间、反应温度、催化剂用量、油水质量比及乳化剂用量对棕榈油水解反应的影响,得出棕榈油一次酸催化水解的最佳反应条件:反应时间7 h,反应温度100℃,催化剂浓硫酸用量7.5%,油水质量比1∶1,乳化剂磺酸用量0.5%;在最佳反应条件下棕榈油水解产物酸值(KOH)为192.77 mg/g,水解率达到91.96%。并研究出一套循环水解的工艺流程,实现油脂水解产物的循环利用,提高了水相中甘油的含量。%The hydrolysis of palm oil catalyzed by acid was studied. The effects of reaction time,reaction temperature,catalyst dosage,mass ratio of oil to water and emulsifier dosage on the hydrolysis of palm oil were investigated. The optimal reaction conditions of palm oil hydrolysis were obtained as follows:reaction time 7 h,reaction temperature 100℃,mass ratio of oil to water 1∶1,dosage of sulfonic acid used as emul-sifier 0. 5% and catalyst( concentrated sulfonic acid) dosage 7. 5%. Under the optimal reaction condi-tions,the acid value of the hydrolysates was up to 192. 77 mgKOH/g and the hydrolysis rate of palm oil was 91. 96%. A circulated hydrolysis process was designed, then the recycling of hydrolysates was real-ized,and the content of glycerin in the aqueous phase increased.

  15. An Efficient Synthesis of 3,4-Dihydropyrimidin-2(1H-Ones and Thiones Catalyzed by a Novel Brønsted Acidic Ionic Liquid under Solvent-Free Conditions

    Directory of Open Access Journals (Sweden)

    Yonghong Zhang

    2015-02-01

    Full Text Available We report here an efficient and green method for Biginelli condensation reaction of aldehydes, β-ketoesters and urea or thiourea catalyzed by Brønsted acidic ionic liquid [Btto][p-TSA] under solvent-free conditions. Compared to the classical Biginelli reaction conditions, the present method has the advantages of giving good yields, short reaction times, near room temperature conditions and the avoidance of the use of organic solvents and metal catalyst.

  16. Catalyzed Ester Synthesis Using Candida rugosa Lipase Entrapped by Poly(N-isopropylacrylamide-co-itaconic Acid Hydrogel

    Directory of Open Access Journals (Sweden)

    Nikola Milašinović

    2014-01-01

    Full Text Available This study reports the synthesis of polymeric matrices based on N-isopropylacrylamide and itaconic acid and its application for immobilization of lipase from Candida rugosa. The lipase was immobilized by entrapment method. Free and immobilized lipase activities, pH and temperature optima, and storage stability were investigated. The optimum temperature for free and entrapped lipase was found to be 40 and 45°C, while the optimum pH was observed at pH 7 and 8, respectively. Both hydrolytic activity in an aqueous medium and esterolytic activity in an organic medium have been evaluated. Maximum reaction rate (Vmax and Michaelis-Menten constants (Km were also determined for immobilized lipase. Storage stability of lipase was increased as a result of immobilization process. Furthermore, the operational stability and reusability of the immobilized lipase in esterification reaction have been studied, and it was observed that after 10 cycles, the residual activity for entrapped lipase was as high as 50%, implying that the developed hydrogel and immobilized system could provide a promising solution for the flavor ester synthesis at the industrial scale.

  17. Advanced Model Compounds for Understanding Acid-Catalyzed Lignin Depolymerization: Identification of Renewable Aromatics and a Lignin-Derived Solvent.

    Science.gov (United States)

    Lahive, Ciaran W; Deuss, Peter J; Lancefield, Christopher S; Sun, Zhuohua; Cordes, David B; Young, Claire M; Tran, Fanny; Slawin, Alexandra M Z; de Vries, Johannes G; Kamer, Paul C J; Westwood, Nicholas J; Barta, Katalin

    2016-07-20

    The development of fundamentally new approaches for lignin depolymerization is challenged by the complexity of this aromatic biopolymer. While overly simplified model compounds often lack relevance to the chemistry of lignin, the direct use of lignin streams poses significant analytical challenges to methodology development. Ideally, new methods should be tested on model compounds that are complex enough to mirror the structural diversity in lignin but still of sufficiently low molecular weight to enable facile analysis. In this contribution, we present a new class of advanced (β-O-4)-(β-5) dilinkage models that are highly realistic representations of a lignin fragment. Together with selected β-O-4, β-5, and β-β structures, these compounds provide a detailed understanding of the reactivity of various types of lignin linkages in acid catalysis in conjunction with stabilization of reactive intermediates using ethylene glycol. The use of these new models has allowed for identification of novel reaction pathways and intermediates and led to the characterization of new dimeric products in subsequent lignin depolymerization studies. The excellent correlation between model and lignin experiments highlights the relevance of this new class of model compounds for broader use in catalysis studies. Only by understanding the reactivity of the linkages in lignin at this level of detail can fully optimized lignin depolymerization strategies be developed. PMID:27310182

  18. Advanced Model Compounds for Understanding Acid-Catalyzed Lignin Depolymerization: Identification of Renewable Aromatics and a Lignin-Derived Solvent.

    Science.gov (United States)

    Lahive, Ciaran W; Deuss, Peter J; Lancefield, Christopher S; Sun, Zhuohua; Cordes, David B; Young, Claire M; Tran, Fanny; Slawin, Alexandra M Z; de Vries, Johannes G; Kamer, Paul C J; Westwood, Nicholas J; Barta, Katalin

    2016-07-20

    The development of fundamentally new approaches for lignin depolymerization is challenged by the complexity of this aromatic biopolymer. While overly simplified model compounds often lack relevance to the chemistry of lignin, the direct use of lignin streams poses significant analytical challenges to methodology development. Ideally, new methods should be tested on model compounds that are complex enough to mirror the structural diversity in lignin but still of sufficiently low molecular weight to enable facile analysis. In this contribution, we present a new class of advanced (β-O-4)-(β-5) dilinkage models that are highly realistic representations of a lignin fragment. Together with selected β-O-4, β-5, and β-β structures, these compounds provide a detailed understanding of the reactivity of various types of lignin linkages in acid catalysis in conjunction with stabilization of reactive intermediates using ethylene glycol. The use of these new models has allowed for identification of novel reaction pathways and intermediates and led to the characterization of new dimeric products in subsequent lignin depolymerization studies. The excellent correlation between model and lignin experiments highlights the relevance of this new class of model compounds for broader use in catalysis studies. Only by understanding the reactivity of the linkages in lignin at this level of detail can fully optimized lignin depolymerization strategies be developed.

  19. Impact of Biochemical Composition on Susceptibility of Algal Biomass to Acid-Catalyzed Pretreatment for Sugar and Lipid Recovery

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Tao; Van Wychen, Stefanie; Nagle, Nick; Pienkos, Philip T.; Laurens, Lieve M. L.

    2016-09-01

    One of the major challenges associated with algal biofuels production in a biorefinery-type setting is improving biomass utilization in its entirety, increasing the process energetic yields and providing economically viable and scalable co-product concepts. We focus on the impact of compositional characteristics of biomass on the susceptibility to pretreatment in order to maximize the valorization of algal biomass conversion for biofuels and bioproducts. The release of monomeric carbohydrates in the aqueous phase and extractability of the lipid fraction was measured based a response surface methodology to find significant explanatory variables and interaction terms. We studied the effect of harvest timing on the conversion yields, using three algal strains; Chlorella vulgaris and Scenedesmus acutus and Nannochloropsis granulata representing three different nutritional metabolic phases. Four cultivation conditions of high (= 90 gallon gasoline equivalent/ton biomass) value for a combined sugar- and lipid-based biofuels process were identified. These four conditions represent either mid or late stage harvest cultivation regimes. The results indicate that acid pretreatment has potential to be applicable for a vast range of biomass samples to obtain high energy yields, but that the exact conditions and optima are dependent on the strain and likely the starting composition of the biomass.

  20. Synthesis of acetylsalicylic acid catalyzed by carbon-based solid acid%碳基固体酸催化合成乙酰水杨酸

    Institute of Scientific and Technical Information of China (English)

    占昌朝; 曹小华; 严平; 王剑波; 余祖进; 江小平

    2012-01-01

    Carbon-based solid acid catalysts synthesized from starch andp-toluene sulphonic acid were characterized by FTIR, TG, BET, SEM and EDS. Its catalytic activity and effect of conventional heat and microwave heat on yield of acetylsalicylic acid were studied. The better condition was determined with single factor tests, which is as follows: the molar ratio of acetic anhydride to salicylic acid was 1.5 : 1, the weight ratio of carbon-based solid acid to salicylic acid was 5.8%, acylation reaction temperature was 76--80 ~C, reaction time was 25 min under conventional heat. The yield of acetylsalicylic acid was 82.1% and kept 78.2% after used five times under conventional heat. The carbon-based solid acid catalyst has high catalytic activity and retrievability under conventional heat, which are better than that of microwave heat.%以淀粉和对甲苯磺酸为原料合成了碳基固体酸催化剂,并采用FTIR、TG、BET、SEM和EDS对催化剂进行了表征。研究了催化剂对乙酰水杨酸合成反应的催化活性,并比较了常规加热和微波加热方式对反应的影响。通过单因素试验确定了较佳工艺条件为:乙酸酐与水杨酸物质的量比为1.5∶1,催化剂用量为水杨酸质量的5.8%,反应时间25 min,反应温度76~80℃。常规加热条件下收率82.1%,使用5次后,收率仍保持在78.2%。碳基固体酸催化剂在常规加热条件下催化性能和重复使用性能均优于微波加热条件反应。

  1. Visual detection of trace copper ions based on copper-catalyzed reaction of ascorbic acid with oxygen

    Science.gov (United States)

    Hou, Xin Yan; Chen, Shu; Shun, Lian Ju; Zhao, Yi Ni; Zhang, Zhi Wu; Long, Yun Fei; Zhu, Li

    2015-10-01

    A visual detection method for trace Cu2+ in aqueous solutions using triangular silver nanoplates (abbreviated as TAgNPs) as the probe was developed. The method is based on that TAgNPs could be corroded in sodium thiosulfate (Na2S2O3) solutions. The absorption spectrum of TAgNPs solution changed when it is corroded by Na2S2O3. The reaction of oxygen with ascorbic acid (Vc) in the presence of a low concentration of Cu2+ generates hydrogen peroxide that reacts with Na2S2O3, which leads the concentration of Na2S2O3 in the solution to be decreased. Therefore, the reaction between TAgNPs and the reacted mixture of Na2S2O3/Vc/Cu2+ was prevented efficiently. When the Na2S2O3 concentration and reaction time are constant, the decrease in the concentration of Na2S2O3 is directly proportional to the Cu2+ concentration. Thus, morphology, color, and maximum absorption wavelength of TAgNPs changed with the change of Cu2+ concentration. The changed maximum absorption wavelength of TAgNPs (Δλ) is proportional to Cu2+ concentration in the range from 7.5 × 10-9 to 5.0 × 10-7 M with a correlation coefficient of r = 0.9956. Moreover, color change of TAgNP solution was observed clearly over a Cu2+ concentration range from 7.5 × 10-8 to 5.0 × 10-7 M. This method has been used to detect the Cu2+ content of a human hair sample, and the result is in agreement with that obtained by the atomic absorption spectroscopy (AAS) method.

  2. Sulfate radical-induced degradation of Acid Orange 7 by a new magnetic composite catalyzed peroxymonosulfate oxidation process

    International Nuclear Information System (INIS)

    Graphical abstract: Organic dyes could be absorbed on the surface of the composite or dispersed in the solution. Sulfate radicals (SO4·−) generated by the synergistic reaction between peroxymonosulfate (PMS) and the composite, attacked the organic functional groups of the dyes molecules both adsorbed on the composite surface and dispersed in the solution, which resulted in the degradation of AO7 dye. - Highlights: • A new composite was synthesized successfully via microwave hydrothermal method. • The complete degradation in the system of FLCN and PMS can be achieved. • The catalytic behavior of FLCN can be reused at least for five times. • The AO7 degradation mechanism in the system of FLCN and PMS was demonstrated. - Abstract: We synthesized a novel magnetic composite, Fe3O4/Cu(Ni)Cr-LDH, as a heterogeneous catalyst for the degradation of organic dyes in the solution using sulfate radical-based advanced oxidation processes. The physicochemical properties of the composite synthesized via two-step microwave hydrothermal method were characterized by several techniques, such as X-ray diffraction (XRD), inductively coupled plasma (ICP), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The degradation tests were performed at 25 °C with Acid Orange 7 (AO7) initial concentration of 25 mg/L and AO7/peroxymonosulfate (PMS) molar ratio of 1:10, which showed that the complete degradation by Fe3O4/Cu1.5Ni0.5Cr-LDH could be achieved and the mineralization rate could reach 46%. PMS was activated by Cu (II) and Fe (II/III) of Fe3O4/Cu(Ni)Cr-LDH to generate sulfate radicals (SO4·−). Subsequently, the organic functional groups of AO7 molecules were destroyed by sulfate radicals (SO4·−), inducing the degradation of AO7. Moreover, the catalytic behavior of the catalysts could be reused five times. Therefore, our work suggested that the Fe3O4/Cu(Ni)Cr-LDH composite could be applied widely for the treatment of organic dyes in wastewater

  3. Sulfate radical-induced degradation of Acid Orange 7 by a new magnetic composite catalyzed peroxymonosulfate oxidation process

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Dan; Ma, Xiaolong; Zhou, Jizhi [School of Environmental and Chemical Engineering, Shanghai University, No. 99 Shangda Road, Shanghai 200444 (China); Chen, Xi [Department of Earth and Environmental Engineering, Columbia University, West 120th Street, New York, NY 10027 (United States); Qian, Guangren, E-mail: grqian@shu.edu.cn [School of Environmental and Chemical Engineering, Shanghai University, No. 99 Shangda Road, Shanghai 200444 (China)

    2014-08-30

    Graphical abstract: Organic dyes could be absorbed on the surface of the composite or dispersed in the solution. Sulfate radicals (SO{sub 4}·{sup −}) generated by the synergistic reaction between peroxymonosulfate (PMS) and the composite, attacked the organic functional groups of the dyes molecules both adsorbed on the composite surface and dispersed in the solution, which resulted in the degradation of AO7 dye. - Highlights: • A new composite was synthesized successfully via microwave hydrothermal method. • The complete degradation in the system of FLCN and PMS can be achieved. • The catalytic behavior of FLCN can be reused at least for five times. • The AO7 degradation mechanism in the system of FLCN and PMS was demonstrated. - Abstract: We synthesized a novel magnetic composite, Fe{sub 3}O{sub 4}/Cu(Ni)Cr-LDH, as a heterogeneous catalyst for the degradation of organic dyes in the solution using sulfate radical-based advanced oxidation processes. The physicochemical properties of the composite synthesized via two-step microwave hydrothermal method were characterized by several techniques, such as X-ray diffraction (XRD), inductively coupled plasma (ICP), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The degradation tests were performed at 25 °C with Acid Orange 7 (AO7) initial concentration of 25 mg/L and AO7/peroxymonosulfate (PMS) molar ratio of 1:10, which showed that the complete degradation by Fe{sub 3}O{sub 4}/Cu{sub 1.5}Ni{sub 0.5}Cr-LDH could be achieved and the mineralization rate could reach 46%. PMS was activated by Cu (II) and Fe (II/III) of Fe{sub 3}O{sub 4}/Cu(Ni)Cr-LDH to generate sulfate radicals (SO{sub 4}·{sup −}). Subsequently, the organic functional groups of AO7 molecules were destroyed by sulfate radicals (SO{sub 4}·{sup −}), inducing the degradation of AO7. Moreover, the catalytic behavior of the catalysts could be reused five times. Therefore, our work suggested that the Fe{sub 3}O{sub 4

  4. Lewis酸性离子液体催化合成丁二酸二异丙酯%Synthesis of succinic acid diisopropyl ester catalyzed by Lewis acid ionic liquids

    Institute of Scientific and Technical Information of China (English)

    赵地顺; 葛京京; 翟建华; 张娟; 刘猛帅; 李俊盼

    2014-01-01

    采用两步法制备了9种不同的Lewis酸性离子液体,采用1H NMR、FT-IR对离子液体的结构进行了表征,并系统地考察了其对丁二酸和异丙醇酯化反应的催化性能。结果表明,离子液体随着卤化物用量增加表现出更强的酸性。其中[Bmim]Br-Fe2Cl6催化合成丁二酸二异丙酯效果良好,催化剂用量为丁二酸质量的10.0%,反应温度100℃,反应时间4 h,酸醇摩尔比为1:5,丁二酸二异丙酯收率为88.9%,酯化率达92.7%。离子液体重复使用6次后,产品收率下降1.7%。%Nine kinds of different Lewis acid ionic liquids were synthesized by two-step process and their structures were characterized with 1H NMR and FT-IR. Lewis acid ionic liquids prepared were used to catalyze the esterification reaction of succinic acid and isopropyl alcohol. With the increase of dosage of halide, the ionic liquids showed stronger acidity. [Bmim]Br-Fe2Cl6 had the best catalytic performance, and optimal conditions for the synthesis of succinic acid diisopropyl ester were obtained as follows, amount of catalyst 10.0%(g/g)of succinic acid, reaction temperature 100℃ and reaction time 4 h, succinic acid and isopropyl alcohol ratio 1:5. Under the optimal conditions, the yield of succinic acid diisopropyl ester was up to 88.9%, esterification rate was 92.7%.The catalyst was recycled 6 times, and the yield of succinic acid diisopropyl ester only decreased by 1.7%.

  5. Inhibition of lactoperoxidase-catalyzed 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) and tyrosine oxidation by tyrosine-containing random amino acid copolymers.

    Science.gov (United States)

    Clausen, Morten R; Skibsted, Leif H; Stagsted, Jan

    2008-09-24

    Oxidation of 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) by lactoperoxidase was found to be inhibited by tyrosine-containing random amino acid copolymers but not by tyrosine. Both electrostatic effects and polymer size were found to be important by comparison of negatively and positively charged copolymers of varying lengths, with poly(Glu, Tyr)4:1 ([E 4Y 1] approximately 40) as the strongest competitive inhibitor (EC 50 approximately 20 nM). This polymer did not form dityrosine in the presence of lactoperoxidase (LPO) and peroxide. Furthermore, incubation with tert-butyl hydroperoxide, as opposed to hydrogen peroxide, resulted in a peculiar long lag phase of the reaction between the redox intermediate compound II and [E 4Y 1] approximately 40, indicating a very tight association between enzyme and inhibitor. We propose that interactions between multiple positively charged areas on the surface of LPO and the polymer are required for optimal inhibition.

  6. Palladium-phosphinous acid complexes catalyzed Suzuki cross-coupling reaction of heteroaryl bromides with phenylboronic acid in water/alcoholic solvents

    Institute of Scientific and Technical Information of China (English)

    Ben Li; Cuiping Wang; Guang Chen; Zhiqiang Zhang

    2013-01-01

    Highly active,air-stable and water-soluble palladium-phosphinous acid complexes have been applied to Suzuki cross-coupling reaction of heteroaryl bromides under mild conditions in water/alcoholic solvents.Suzuki cross-coupling reaction of heteroaryl bromides with phenylboronic acid occurred efficiently using palladium phosphinous acid complexes (POPd) and phase transfer catalyst (tetrabutylammonium bromide and polyethylene glycol) in water/ethanol mixture,water/propanol mixture and neat water respectively,the corresponding yields of cross-coupling heteroaryl-aryls were satisfied.The tert-butyl substituted ligand di-tert-butylphosphino in combination with POPd was found to be more active than the same family derived catalysts dipalladium complexes POPdl and POPd2,and other two kinds of Pd-catalysts Pd(PPh3)4 and Pd2(dba)3.The mechanism of Suzuki cross-coupling reaction between heteroaryl bromides and phenylboronic acid in water was proposed with respect to the key role of phase transfer catalyst on the transmetallation step.Compared with other solid phase transfer catalysts,TBAB was tested as the ideal one.The alkalinity of base and the molar proportion between POPd and TBAB were investigated in water and alcoholic solvents.Notably,in the presence of TBAB adding alcoholic solvents into water enhanced the yields of target products.However in terms of the liquid phase transfer catalyst of PEGs,mixing water into PEGs could slightly decrease the yields with respect to the water free PEGs bulk phase,which was probably due to the homogenous liquid conditions in pure PEGs and weak interactions between PEGs and heteroaryl bromide molecules in water depending on their molecular chain lengths.

  7. Effect of acid-catalyzed formation rates of benzimidazole-linked polymers on porosity and selective CO2 capture from gas mixtures.

    Science.gov (United States)

    Altarawneh, Suha; İslamoğlu, Timur; Sekizkardes, Ali Kemal; El-Kaderi, Hani M

    2015-04-01

    Benzimidazole-linked polymers (BILPs) are emerging candidates for gas storage and separation applications; however, their current synthetic methods offer limited control over textural properties which are vital for their multifaceted use. In this study, we investigate the impact of acid-catalyzed formation rates of the imidazole units on the porosity levels of BILPs and subsequent effects on CO2 and CH4 binding affinities and selective uptake of CO2 over CH4 and N2. Treatment of 3,3'-Diaminobenzidine tetrahydrochloride hydrate with 1,2,4,5-tetrakis(4-formylphenyl)benzene and 1,3,5-(4-formylphenyl)-benzene in anhydrous DMF afforded porous BILP-15 (448 m(2) g(-1)) and BILP-16 (435 m(2) g(-1)), respectively. Alternatively, the same polymers were prepared from the neutral 3,3'-Diaminobenzidine and catalytic amounts of aqueous HCl. The resulting polymers denoted BILP-15(AC) and BILP-16(AC) exhibited optimal surface areas; 862 m(2) g(-1) and 643 m(2) g(-1), respectively, only when 2 equiv of HCl (0.22 M) was used. In contrast, the CO2 binding affinity (Qst) dropped from 33.0 to 28.9 kJ mol(-1) for BILP-15 and from 32.0 to 31.6 kJ mol(-1) for BILP-16. According to initial slope calculations at 273 K/298 K, a notable change in CO2/N2 selectivity was observed for BILP-15(AC) (61/50) compared to BILP-15 (83/63). Similarly, ideal adsorbed solution theory (IAST) calculations also show the higher specific surface area of BILP-15(AC) and BILP-16(AC) compromises their CO2/N2 selectivity.

  8. Hydrogen Isotope Measurements of Organic Acids and Alcohols by Pyrolysis-GC-MS-TC-IRMS: Application to Analysis of Experimentally Derived Hydrothermal Mineral-Catalyzed Organic Products

    Science.gov (United States)

    Socki, Richard A.; Fu, Qi; Niles, Paul B.; Gibson, Everett K., Jr.

    2012-01-01

    We report results of experiments to measure the H isotope composition of organic acids and alcohols. These experiments make use of a pyroprobe interfaced with a GC and high temperature extraction furnace to make quantitative H isotope measurements. This work compliments our previous work that focused on the extraction and analysis of C isotopes from the same compounds [1]. Together with our carbon isotope analyses our experiments serve as a "proof of concept" for making C and H isotope measurements on more complex mixtures of organic compounds on mineral surfaces in abiotic hydrocarbon formation processes at elevated temperatures and pressures. Our motivation for undertaking this work stems from observations of methane detected within the Martian atmosphere [2-5], coupled with evidence showing extensive water-rock interaction during Mars history [6-8]. Methane production on Mars could be the result of synthesis by mineral surface-catalyzed reduction of CO2 and/or CO by Fischer-Tropsch Type (FTT) reactions during serpentization [9,10]. Others have conducted experimental studies to show that FTT reactions are plausible mechanisms for low-molecular weight hydrocarbon formation in hydrothermal systems at mid-ocean ridges [11-13]. Our H isotope measurements utilize an analytical technique combining Pyrolysis-Gas Chromatograph-Mass Spectrometry-High Temperature Conversion-Isotope Ratio Mass Spectrometry (Py-GC-MS-TC-IRMS). This technique is designed to carry a split of the pyrolyzed GC-separated product to a Thermo DSQII quadrupole mass spectrometer as a means of making qualitative and semi-quantitative compositional measurements of separated organic compounds, therefore both chemical and isotopic measurements can be carried out simultaneously on the same sample.

  9. Palladium-Catalyzed Asymmetric Conjugate Addition of Arylboronic Acids to Five-, Six-, and Seven-Membered β-Substituted Cyclic Enones: Enantioselective Construction of All-Carbon Quaternary Stereocenters

    KAUST Repository

    Kikushima, Kotaro

    2011-05-11

    The first enantioselective Pd-catalyzed construction of all-carbon quaternary stereocenters via 1,4-addition of arylboronic acids to β-substituted cyclic enones is reported. Reaction of a wide range of arylboronic acids and cyclic enones using a catalyst prepared from Pd(OCOCF(3))(2) and a chiral pyridinooxazoline ligand yields enantioenriched products bearing benzylic stereocenters. Notably, this transformation is tolerant to air and moisture, providing a practical and operationally simple method of synthesizing enantioenriched all-carbon quaternary stereocenters.

  10. Synergistic catalysis of isolated Fe3+ and Fe2O3 on FeOx/HZSM-5 catalysts for Friedel-Crafts benzylation of benzene

    Institute of Scientific and Technical Information of China (English)

    Tao Lin; Xin Zhang; Rong Li; Ting Bai; Si Ying Yang

    2011-01-01

    FeOx/HZSM-5 catalyst with 8 wt.% Fe-loading (8-FeZ) exhibited significantly higher reactivity in the benzylation of benzene with benzyl chloride than FeOx/HZSM-5 catalyst with 2.5 wt.% Fe-loading (2.5-FeZ) because the synergistic catalysis between isolated Fe3+ and superfine Fe2O3 occurred on 8-FeZ in the reaction.

  11. Synthesis and Applications of (-)-(S)-3-Aminoquinuclidine- Derived Thiourea

    OpenAIRE

    Rolava, E; Turks, M

    2015-01-01

    A synthesis of enantiopure thiourea organocatalyst based on (-)-(S)-3-aminoquinuclidine dihydrochloride was developed with quantitative product yield. The catalyst was tested in different reactions: asymmetric Michael addition of ketones and malonates to nitroalkenes, nitromethane 1,4-addition to trans-chalcone, and Friedel-Crafts alkylation of indoles with trans-β-nitrostyrene. The novel thiourea proved to catalyze the aforementioned reactions and expected products were ...

  12. Understanding the Mechanism of the Hydrogen Abstraction from Arachidonic Acid Catalyzed by the Human Enzyme 15-Lipoxygenase-2. A Quantum Mechanics/Molecular Mechanics Free Energy Simulation.

    Science.gov (United States)

    Suardíaz, Reynier; Jambrina, Pablo G; Masgrau, Laura; González-Lafont, Àngels; Rosta, Edina; Lluch, José M

    2016-04-12

    Lipoxygenases (LOXs) are a family of enzymes involved in the biosynthesis of several lipid mediators. In the case of human 15-LOX, the 15-LOX-1 and 15-LOX-2 isoforms show slightly different reaction regiospecificity and substrate specificity, indicating that substrate binding and recognition may be different, a fact that could be related to their different biological role. Here, we have used long molecular dynamics simulations, QM(DFT)/MM potential energy and free energy calculations (using the newly developed DHAM method), to investigate the binding mode of the arachidonic acid (AA) substrate into 15-LOX-2 and the rate-limiting hydrogen-abstraction reaction 15-LOX-2 catalyzes. Our results strongly indicate that hydrogen abstraction from C13 in 15-LOX-2 is only consistent with the "tail-first" orientation of AA, with its carboxylate group interacting with Arg429, and that only the pro-S H13 hydrogen will be abstracted (being the pro-R H13 and H10 too far from the acceptor oxygen atom). At the B3LYP/6-31G(d) level the potential and free energy barriers for the pro-S H13 abstraction of AA by 15-LOX-2 are 18.0 and 18.6 kcal/mol, respectively. To analyze the kinetics of the hydrogen abstraction process, we determined a Markov model corresponding to the unbiased simulations along the state-discretized reaction coordinate. The calculated rates based on the second largest eigenvalue of the Markov matrices agree well with experimental measurements, and also provide the means to directly determine the pre-exponential factor for the reaction by comparing with the free energy barrier height. Our calculated pre-exponential factor is close to the value of kBT/h. On the other hand, our results suggest that the spin inversion of the complete system (including the O2 molecule) that is required to happen at some point along the full process to lead to the final hydroperoxide product, is likely to take place during the hydrogen transfer, which is a proton coupled electron transfer

  13. The Practical Asymmetric Syntheses of Key Chiral Intermediates of Chiral Drug from Four-Carbon Chiral Pool

    Institute of Scientific and Technical Information of China (English)

    MI; AiQiao

    2001-01-01

    (S)-or (R)-2-Amino-4-phenylbutyric acid and (S)-or (R)-2-hydroxy-4-phenylbutyric acid and their ethyl esters are key chiral intermediates for the preparation of angiotensin converting enzyme inhibitors (ACEI) and other chiral drugs. Their practically asymmetric synthetic methods in large scale from four-carbon chiral pool, commercially available L-aspartic acid and L-malic acid, will be presented (as scheme).  (S)-2-Amino-4-phenylbutyric acid and its ethyl ester hydrochloride were prepared from the easily available L-aspartic acid via activation by forming anhydride hydrochloride, Friedel-Crafts reaction with benzene, hydrogenolysis and esterification with ethanol in the presence of thionyl chloride in overall yield of 80% and 73.6% respectively with 99% ee. We first used amino acid anhydride hydrochloride as the acylating agent in Friedel-Crafts reaction without racemization. [1]……

  14. The Practical Asymmetric Syntheses of Key Chiral Intermediates of Chiral Drug from Four-Carbon Chiral Pool

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ (S)-or (R)-2-Amino-4-phenylbutyric acid and (S)-or (R)-2-hydroxy-4-phenylbutyric acid and their ethyl esters are key chiral intermediates for the preparation of angiotensin converting enzyme inhibitors (ACEI) and other chiral drugs. Their practically asymmetric synthetic methods in large scale from four-carbon chiral pool, commercially available L-aspartic acid and L-malic acid, will be presented (as scheme). (S)-2-Amino-4-phenylbutyric acid and its ethyl ester hydrochloride were prepared from the easily available L-aspartic acid via activation by forming anhydride hydrochloride, Friedel-Crafts reaction with benzene, hydrogenolysis and esterification with ethanol in the presence of thionyl chloride in overall yield of 80% and 73.6% respectively with 99% ee. We first used amino acid anhydride hydrochloride as the acylating agent in Friedel-Crafts reaction without racemization. [1

  15. Process Condition Optimization of the a-linolenic Acid Catalyzed by Pichia pastoris%巴斯德毕赤酵母催化生成a-亚麻酸的工艺条件优化

    Institute of Scientific and Technical Information of China (English)

    冯康; 葛军军; 张昕欣

    2015-01-01

    利用正交实验优化了巴斯德毕赤酵母催化硬脂酸生成a-亚麻酸的工艺条件,结果显示催化时巴斯德毕赤酵母接种量对催化效率影响显著,在此基础上得到的最佳催化条件为pH值6.5,硬脂酸乙醇饱和溶液加量4 mL,巴斯德毕赤酵母接种量为1 mL。在此条件下,以a-亚麻酸甲酯气相色谱积分面积(18:3)/硬脂酸甲酯气相色谱积分面积(18:0)为标准计算出的转化率为7.16。%For a-linolenic acid production, process condition optimization of stearic acide catalyzed by Pichia pastoris was done by orthogonal design. The results indicated that there was a significant effect of the catalytic efficiency by inoculum size of Pichia pastoris. On this basis, the best catalyzed conditions were obtained:pH of 6. 5, addition amount of saturated ethanol solution of stearic acide was 4 mL, inoculum size of Pichia pastoris was 1 mL. Under the condition, conversion of stearic acide toa-linolenic acid was 7. 16.

  16. Study on Biodiesel Preparation by a Two-step Catalyzed Process from Waste Cooking Oil with a High Acid Value%两步法利用高酸值潲水油制备生物柴油研究

    Institute of Scientific and Technical Information of China (English)

    马顺; 汪勇; 唐书泽

    2011-01-01

    A two-step catalyzed process was developed to prepare biodiesel from waste cooking oil (WCO) in this study.Free fatty acid of WCO was esterified with methanol catalyzed by polyferric sulfate in the first step, and then triglyceride of WCO was transesterified with methanol catalyzed by potassium hydroxide.Results showed that polyferric sulfate had strong activity to catalyze the esterification.The optimal parameters of esterification obtained by response surface as follows :5.87 % ( of the WCO mass) of polyferric sulfate, 108.7% (of the WCO mass) of methanol,6.0 h of reaction time and 80 ℃ of reaction temperature.Under this condition, the AV reached as low as 2.20 mgKOH/g,and the esterification rate was 97.71%.The yield of purified biodiesel was 98.20% from the crude biodiesel obtained by this two-step process by molecular distillation at 110 ℃.Composition of fatty acid methyl ester of the purified biodiesel was analyzed by gas chromatography (GC).Some physical and chemical properties of purified biodiesel were detected according to national standards for biodiesel.%以潲水油为原料,采用两步催化法制备生物柴油.先用聚合硫酸铁催化潲水油中游离脂肪酸和甲醇酯转化为脂肪酸甲酯,然后再通过碱催化剩余的甘油三酯进行酯交换反应.通过响应面试验设计优化酯化反应,结果表明,在反应时间6.0 h、甲醇用量108.7%(质量比,按油质量)、催化剂用量5.87%(质量比,按油质量)、反应温度80℃下,酸值可达到2.20 mgKOH/g,即酯化率为97.71%.在¨0℃下对经两步催化得到的生物柴油进行分子蒸馏,得率为98.20%,测定了生物柴油的脂肪酸甲酯组成,按照国标检测了纯化的生物柴油的物化性质.

  17. Hydrogen Peroxide-Resistant CotA and YjqC of Bacillus altitudinis Spores Are a Promising Biocatalyst for Catalyzing Reduction of Sinapic Acid and Sinapine in Rapeseed Meal

    Science.gov (United States)

    Zhang, Yanzhou; Li, Xunhang; Hao, Zhikui; Xi, Ruchun; Cai, Yujie; Liao, Xiangru

    2016-01-01

    For the more efficient detoxification of phenolic compounds, a promising avenue would be to develop a multi-enzyme biocatalyst comprising peroxidase, laccase and other oxidases. However, the development of this multi-enzyme biocatalyst is limited by the vulnerability of fungal laccases and peroxidases to hydrogen peroxide (H2O2)-induced inactivation. Therefore, H2O2-resistant peroxidase and laccase should be exploited. In this study, H2O2-stable CotA and YjqC were isolated from the outer coat of Bacillus altitudinis SYBC hb4 spores. In addition to the thermal and alkali stability of catalytic activity, CotA also exhibited a much higher H2O2 tolerance than fungal laccases from Trametes versicolor and Trametes trogii. YjqC is a sporulation-related manganese (Mn) catalase with striking peroxidase activity for sinapic acid (SA) and sinapine (SNP). In contrast to the typical heme-containing peroxidases, the peroxidase activity of YjqC was also highly resistant to inhibition by H2O2 and heat. CotA could also catalyze the oxidation of SA and SNP. CotA had a much higher affinity for SA than B. subtilis CotA. CotA and YjqC rendered from B. altitudinis spores had promising laccase and peroxidase activities for SA and SNP. Specifically, the B. altitudinis spores could be regarded as a multi-enzyme biocatalyst composed of CotA and YjqC. The B. altitudinis spores were efficient for catalyzing the degradation of SA and SNP in rapeseed meal. Moreover, efficiency of the spore-catalyzed degradation of SA and SNP was greatly improved by the presence of 15 mM H2O2. This effect was largely attributed to synergistic biocatalysis of the H2O2-resistant CotA and YjqC toward SA and SNP. PMID:27362423

  18. Hydrogen Peroxide-Resistant CotA and YjqC of Bacillus altitudinis Spores Are a Promising Biocatalyst for Catalyzing Reduction of Sinapic Acid and Sinapine in Rapeseed Meal.

    Directory of Open Access Journals (Sweden)

    Yanzhou Zhang

    Full Text Available For the more efficient detoxification of phenolic compounds, a promising avenue would be to develop a multi-enzyme biocatalyst comprising peroxidase, laccase and other oxidases. However, the development of this multi-enzyme biocatalyst is limited by the vulnerability of fungal laccases and peroxidases to hydrogen peroxide (H2O2-induced inactivation. Therefore, H2O2-resistant peroxidase and laccase should be exploited. In this study, H2O2-stable CotA and YjqC were isolated from the outer coat of Bacillus altitudinis SYBC hb4 spores. In addition to the thermal and alkali stability of catalytic activity, CotA also exhibited a much higher H2O2 tolerance than fungal laccases from Trametes versicolor and Trametes trogii. YjqC is a sporulation-related manganese (Mn catalase with striking peroxidase activity for sinapic acid (SA and sinapine (SNP. In contrast to the typical heme-containing peroxidases, the peroxidase activity of YjqC was also highly resistant to inhibition by H2O2 and heat. CotA could also catalyze the oxidation of SA and SNP. CotA had a much higher affinity for SA than B. subtilis CotA. CotA and YjqC rendered from B. altitudinis spores had promising laccase and peroxidase activities for SA and SNP. Specifically, the B. altitudinis spores could be regarded as a multi-enzyme biocatalyst composed of CotA and YjqC. The B. altitudinis spores were efficient for catalyzing the degradation of SA and SNP in rapeseed meal. Moreover, efficiency of the spore-catalyzed degradation of SA and SNP was greatly improved by the presence of 15 mM H2O2. This effect was largely attributed to synergistic biocatalysis of the H2O2-resistant CotA and YjqC toward SA and SNP.

  19. Hydrogen Peroxide-Resistant CotA and YjqC of Bacillus altitudinis Spores Are a Promising Biocatalyst for Catalyzing Reduction of Sinapic Acid and Sinapine in Rapeseed Meal.

    Science.gov (United States)

    Zhang, Yanzhou; Li, Xunhang; Hao, Zhikui; Xi, Ruchun; Cai, Yujie; Liao, Xiangru

    2016-01-01

    For the more efficient detoxification of phenolic compounds, a promising avenue would be to develop a multi-enzyme biocatalyst comprising peroxidase, laccase and other oxidases. However, the development of this multi-enzyme biocatalyst is limited by the vulnerability of fungal laccases and peroxidases to hydrogen peroxide (H2O2)-induced inactivation. Therefore, H2O2-resistant peroxidase and laccase should be exploited. In this study, H2O2-stable CotA and YjqC were isolated from the outer coat of Bacillus altitudinis SYBC hb4 spores. In addition to the thermal and alkali stability of catalytic activity, CotA also exhibited a much higher H2O2 tolerance than fungal laccases from Trametes versicolor and Trametes trogii. YjqC is a sporulation-related manganese (Mn) catalase with striking peroxidase activity for sinapic acid (SA) and sinapine (SNP). In contrast to the typical heme-containing peroxidases, the peroxidase activity of YjqC was also highly resistant to inhibition by H2O2 and heat. CotA could also catalyze the oxidation of SA and SNP. CotA had a much higher affinity for SA than B. subtilis CotA. CotA and YjqC rendered from B. altitudinis spores had promising laccase and peroxidase activities for SA and SNP. Specifically, the B. altitudinis spores could be regarded as a multi-enzyme biocatalyst composed of CotA and YjqC. The B. altitudinis spores were efficient for catalyzing the degradation of SA and SNP in rapeseed meal. Moreover, efficiency of the spore-catalyzed degradation of SA and SNP was greatly improved by the presence of 15 mM H2O2. This effect was largely attributed to synergistic biocatalysis of the H2O2-resistant CotA and YjqC toward SA and SNP. PMID:27362423

  20. 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.

  1. 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 ...

  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. A Novel poly {(2,5-diyl thiophene) (2-Thiophenyl Methine)} from the Acid-Catalyzed Polycondensation of thiophene and thiophene-2-carbanaldehyde

    Science.gov (United States)

    Belmokhtar, A.; Yahiaoui, A.; Hachemaoui, A.; Sahli, N.; Benyoucef, A.; Belfedal, A.; Belbachir, M.

    2012-02-01

    Conjugated poly [(thiophene methine) have been synthesized by a simple method: Condensation of thiophene-2-carbaldehyde with thiophene, catalyzed by Maghnite-H+, which is an exchanged montmorillonite sheet silicate with protons to produce Maghnite-H+ non-toxic cationic catalyst, and characterized by FT-IR and UV-Vis. The result reveals that the yield of PTTM increase with time and amount of Mag-H. The results obtained with optical measurements and analyzed by different models, show clearly that our material (PTTM) is a good semi-conductor, when the average gap around 5 eV. The effect of the amount of Mag-H+, and the time of polymer was studied.

  4. Lewis acid catalyzed cyclization of glycals/2-deoxy-D-ribose with arylamines: additional findings on product structure and reaction diastereoselectivity.

    Science.gov (United States)

    Du, Chengtang; Li, Fulong; Zhang, Xuefeng; Hu, Wenxiang; Yao, Qizheng; Zhang, Ao

    2011-11-01

    The cyclization reactions of arylamines with 2-deoxy-D-ribose or glycals were reinvestigated in the current report. In the montmorillonite KSF- or InCl(3)-initiated reactions of 2-deoxy-D-ribose with arylamines, a pair of diastereomeric tetrahydro-2H-pyran-fused tetrahydroquinolines was obtained in a nearly 1:1 ratio where the structure of one diastereomer was incorrectly assigned in the literature. Meanwhile, the diastereoselectivity in InBr(3)-catalyzed cyclization of glycals with arylamines was also incorrectly reported previously. It was found that high diastereomeric selectivity was achieved only when a C5-substituted glycal was used; otherwise, a pair of diastereomers was obtained in moderate yield with 1:1 diastereomeric ratio. Furthermore, tetrahydrofuran-fused tetrahydroquinolines 5b and 5b' were also prepared successfully by using TBDPS-protected ribose as the glycal precursor and montmorillonite KSF as the activator.

  5. Effect of low-molecular-weight organic acids on photo-degradation of phenanthrene catalyzed by Fe(III)-smectite under visible light.

    Science.gov (United States)

    Jia, Hanzhong; Chen, Hongxia; Nulaji, Gulimire; Li, Xiyou; Wang, Chuanyi

    2015-11-01

    The photolysis of polycyclic aromatic hydrocarbons (PAHs) is potentially an important process for its transformation and fate on contaminated soil surfaces. In this study, phenanthrene is employed as a model to explore PAH photodegradation with the assistance of Fe(III)-smectite under visible-light while focusing on roles played by five low-molecular-weight organic acids (LMWOAs), i.e., malic acid, oxalic acid, citric acid, ethylenediaminetetraacetic acid (EDTA), and nitrilotriacetic acid. Our results show that oxalic acid is most effective in promoting the photodegradation of phenanthrene, while only a slight increase in the rate of phenanthrene photodegradation is observed in the presence of malic acid. Electron paramagnetic resonance experiments confirm the formation of CO2(-) radicals in the presence of malic and oxalic acid, which provides strong evidence for generating OH and subsequent photoreaction pathways. The presence of EDTA or nitrilotriacetic acid significantly inhibits both Fe(II) formation and phenanthrene photodegradation because these organic anions tend to chelate with Fe(III), leading to decreases in the electron-accepting potential of Fe(III)-smectite and a weakened interaction between phenanthrene and Fe(III)-smectite. These observations provide valuable insights into the transformation and fate of PAHs in the natural soil environment and demonstrate the potential for using some LMWOAs as additives for the remediation of contaminated soil.

  6. Synthesis of 2,4-diisopropyl-5,5-dimethyl- 1,3-dioxane catalyzed by Brφnsted acidic ionic liquids

    Institute of Scientific and Technical Information of China (English)

    WANG WenJuan; WANG YouFei; CHENG WenPing; WANG Jian; YANG JianGuo; HE MingYuan

    2008-01-01

    The acetalization reactions of isobutyraldehyde with 2,2,4-trimethyl-1,3-pentanediol (TMPD) for the synthesis of 2,4-diisopropyl-5,5-dimethyl-1,3-dioxane were carried out under mild reaction conditions using four water-stable Brφnsted-acidic task-specific ionic liquids ([HMIM]BF4, -SO3H functionalized acidic ionic liquid, -COOH functionalized acidic ionic liquid, [NMP][HSO4]) as environmentally benign catalysts for the first time. The process is highly effective and very selective. The -COOH functional-ized Bronsted acidic ionic liquid with the two acid sites (IL-3) exhibited the most excellent catalytic performance under mild reaction conditions. The --COOH functionalized Brφnsted acidic ionic liquid could be conveniently separated from the product and easily recycled in subsequent runs.

  7. SYNTHESIS OF ISOAMYL SALICYLATE CATALYZED BY GERMANOTUNGSTIC ACID CATALYST%锗钨酸催化合成水杨酸异戊酯

    Institute of Scientific and Technical Information of China (English)

    蒋维

    2000-01-01

    Isoamyl salicylate was synthesized by using germanotungtic acid as catalyst.The effects of the amaunt of catalyst,the molar ratio of salicycic acid of isoamy l alcohol,the reaction temperature and the reaction time on the yield of ester w ere studied.The optimum reaction conditions were 1.3∶100 (mass ratio) of cataly st to reactants,1∶2.5 (molar ratio) of acid to alcohol,135~153℃ being satisfa ctary reaction temperature and reaction time suitable being 3h.Under such condit ion,the yield of ester was up to 94%.Germanotungtic acid catalyst can be used re peatedly.

  8. Ultrasound-assisted MnO2 catalyzed homolysis of peracetic acid for phenol degradation: The assessment of process chemistry and kinetics

    NARCIS (Netherlands)

    Rokhina, E.V.; Makarova, K.; Lathinen, M.; Golovina, E.A.; As, van H.; Virkutyte, J.

    2013-01-01

    The combination of peracetic acid (PAA) and heterogeneous catalyst (MnO2) was used for the degradation of phenol in an aqueous solution in the presence of ultrasound irradiation (US). As a relevant source of free radicals (e.g. OH), peracetic acid was comprehensively studied by means of electron spi

  9. Metalloporphyrin-Based Hypercrosslinked Polymers Catalyze Hetero-Diels-Alder Reactions of Unactivated Aldehydes with Simple Dienes: A Fascinating Strategy for the Construction of Heterogeneous Catalysts.

    Science.gov (United States)

    Dou, Zhiyu; Xu, Li; Zhi, Yongfeng; Zhang, Yuwei; Xia, Hong; Mu, Ying; Liu, Xiaoming

    2016-07-11

    We describe a novel and intriguing strategy for the construction of efficient heterogeneous catalysts by hypercrosslinking catalyst molecules in a one-pot Friedel-Crafts alkylation reaction. The new hypercrosslinked polymers (HCPs) as porous solid catalysts exhibit the combined advantages of homogeneous and heterogeneous catalysis, owing to their high surface area, good stability, and tailoring of catalytic centers on the frameworks. Indeed, a new class of metalloporphyrin-based HCPs were successfully synthesized using modified iron(III) porphyrin complexes as building blocks, and the resulting networks were found to be excellent recyclable heterogeneous catalysts for the hetero-Diels-Alder reaction of unactivated aldehydes with 1,3-dienes. Moreover, this new strategy showed wide adaptability, and many kinds of homogeneous-like solid-based catalysts with high catalytic performance and excellent recyclability were also constructed. PMID:27147500

  10. Kinetics of phosphotungstic acid catalyzed oxidation of propan-1,3-diol and butan-1,4-diol by N-chlorosaccharin

    Directory of Open Access Journals (Sweden)

    Sanjay Kumar Singh

    2011-09-01

    Full Text Available The kinetic studies of N-chlorosaccharin (NCSA oxidation of propan-1,3-diol and butan-1,4-diol have been reported in presence of phophotungstic acid and in aqueous acetic acid medium. The reactions follow first-order in NCSA and one to zero order with respect to substrate and phosphotungstic acid. Increase in the concentration of added perchloric acid increases the rate of oxidation. A negative effect on the oxidation rate is observed for solvent whereas the ionic strength does not influence the rate of reaction. Addition of the reaction product, saccharin, exhibited retarding effect. Various activation parameters have been evaluated. The products of the reactions were identified as the corresponding aldehydes. A suitable scheme of mechanism consistent with the experimental results has been proposed.

  11. The effect of the distance between acidic site and basic site immobilized on mesoporous solid on the activity in catalyzing aldol condensation

    Science.gov (United States)

    Yu, Xiaofang; Yu, Xiaobo; Wu, Shujie; Liu, Bo; Liu, Heng; Guan, Jingqi; Kan, Qiubin

    2011-02-01

    Acid-base bifunctional heterogeneous catalysts containing carboxylic and amine groups, which were immobilized at defined distance from one another on the mesoporous solid were synthesized by immobilizing lysine onto carboxyl-SBA-15. The obtained materials were characterized by X-ray diffraction (XRD), N 2 adsorption, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron micrographs (SEM), transmission electron micrographs (TEM), elemental analysis, and back titration. Proximal-C-A-SBA-15 with a proximal acid-base distance was more active than maximum-C-A-SBA-15 with a maximum acid-base distance in aldol condensation reaction between acetone and various aldehydes. It appears that the distance between acidic site and basic site immobilized on mesoporous solid should be an essential factor for catalysis optimization.

  12. CuO and Ag2O/CuO Catalyzed Oxidation of Aldehydes to the Corresponding Carboxylic Acids by Molecular Oxygen

    Directory of Open Access Journals (Sweden)

    Yaowu Sha

    2008-04-01

    Full Text Available Furfural was oxidized to furoic acid by molecular oxygen under catalysis by 150nm-sized Ag2O/CuO (92% or simply CuO (86.6%. When 30 nm-size catalyst was used,the main product was a furfural Diels-Alder adduct. Detailed reaction conditions andregeneration of catalysts were investigated. Under optimal conditions, a series of aromaticand aliphatic aldehydes were oxidized to the corresponding acids in good yields.

  13. Conversion of hemicellulose sugars catalyzed by formic acid: kinetics of the dehydration of D-xylose, L-arabinose, and D-glucose.

    Science.gov (United States)

    Dussan, Karla; Girisuta, Buana; Lopes, Marystela; Leahy, James J; Hayes, Michael H B

    2015-04-24

    The pre-treatment of lignocellulosic biomass produces a liquid stream of hemicellulose-based sugars, which can be further converted to high-value chemicals. Formosolv pulping and the Milox process use formic acid as the fractionating agent, which can be used as the catalyst for the valorisation of hemicellulose sugars to platform chemicals. The objective of this study was to investigate the reaction kinetics of major components in the hemicelluloses fraction of biomass, that is, D-xylose, L-arabinose and D-glucose. The kinetics experiments for each sugar were performed at temperatures between 130 and 170 °C in various formic acid concentrations (10-64 wt %). The implications of these kinetic models on the selectivity of each sugar to the desired products are discussed. The models were used to predict the reaction kinetics of solutions that resemble the liquid stream obtained from the fractionation process of biomass using formic acid. PMID:25821128

  14. Synthesis of butyl hexanoate catalyzed by solid acid catalyst%新型固体酸催化合成己酸丁酯

    Institute of Scientific and Technical Information of China (English)

    闫鹏; 郭海福; 陈志胜; 王赵志

    2011-01-01

    Butyl hexanoate was synthesized by hexanoic acid and n-butanol,using solid acid Zr( SO4 )2/SiO2 as catalyst. Effects of n(hexanoic acid):n( n-butanol), catalyst dosage and reaction time on the esterification rate were discussed by orthogonal experiment design,which showed that the influence order of esterification rate was: catalyst dosage > reaction time > n ( hexanoic acid ): n ( n- butanol ) .The optimum technical conditions were as follow: n( hexanoic acid):n(n-butanol) = 1:3, mass fraction of Zr(SO4) 2/SiO2 in hexanoic acid 4.0% and reaction time 2.5h,the esterification rate was 99.6%.%以新型固体酸zr(SO4)2/SiO2为催化荆,己酸和正丁醇为原料,催化合成葡萄酒用香料己酸丁酯.通过正交实验设计考察影响反应的因素.结果表明,在酸醇摩尔比、催化剂用量、反应时间三个因素中,其影响次序为催化剂用量>反应时间>酸醇比.适宜的工艺条件为:酸醇物质的量比为1:3,催化剂用量为4%,反应时间为2.5h,酯化率可达99.6%.

  15. 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.

  16. Phosphotungstic Acid Catalyzed One-Pot Synthesis of 2-amino-3,5-dicarbonitrile-6-thio-pyridines in Aqueous Media

    International Nuclear Information System (INIS)

    In this study, we report the one-pot synthesis of 2-amino-3,5-dicarbonitrile-6-thio-pyridines with benzaldehyde, malononitrile, and thiophenol by using phosphotungstic acid as an efficient catalyst to aqueous media. This method has the advantages of easy separation, high storage stability, and environmental friendliness. (author)

  17. Nickel-catalyzed cross-coupling of phenols and arylboronic acids through an in situ phenol activation mediated by PyBroP.

    Science.gov (United States)

    Chen, Guo-Jun; Huang, Jie; Gao, Lian-Xun; Han, Fu-She

    2011-03-28

    A new method for the Suzuki-Miyaura cross-coupling of phenols and arylboronic acids through in situ phenol activation mediated by PyBroP is presented. The reaction proceeds efficiently by using cost-effective, markedly stable [NiCl(2)(dppp)] (dppp=1,3-bis(diphenylphosphino)propane) as the catalyst in only 5 mol % loading, as well as in the absence of extra ligands. The method exhibits broad applicability and high efficiency towards a wide range of both phenols and boronic acids, including activated, nonactivated, deactivated, and heteroaromatic coupling partners. In addition, various functional groups, such as ether, amino, cyano, ester, and ketone groups, are compatible with this transformation. Notably, arylboronic acids containing an unprotected NH(2) group and 2-heterocyclic boronic acids, which are generally problematic for coupling under conventional conditions, are also viable substrates, although moderate yields were obtained for sterically hindered substrates. Consequently, the in situ cross-coupling methodology coupled with the use of an inexpensive and stable nickel catalyst provides a rapid and efficient pathway for the assembly of biaryls and heterobiaryls with structural diversity from readily available phenol compounds.

  18. Influence of acid-base properties on the Lebedev ethanol-to-butadiene process catalyzed by SiO2-MgO materials

    NARCIS (Netherlands)

    Angelici, Carlo; Velthoen, Marjolein E. Z.; Weckhuysen, Bert M.; Bruijnincx, Pieter C. A.

    2015-01-01

    The Lebedev ethanol-to-butadiene process entails a complex chain of reactions that require catalysts to possess a subtle balance in the number and strength of acidic and basic sites. SiO2-MgO materials can be excellent Lebedev catalysts if properly prepared, as catalyst performance has been found to

  19. Synthesis of ferulic acid catalyzed by ammonium acetate%乙酸铵催化合成阿魏酸的工艺研究

    Institute of Scientific and Technical Information of China (English)

    梁红冬; 蔡庆荣

    2011-01-01

    以香草醛和丙二酸为原料,乙酸铵为催化剂,合成阿魏酸.考察反应时间、投料物质的量比、催化剂用量和溶剂体积比等因素对收率的影响.结果表明,N,N-二甲基甲酰胺作溶剂,环已烷作带水剂,在V(环己烷)∶以N,N-二甲基甲酰胺)=2∶1、催化剂用量占香草醛质量的6%、n(香草醛)∶n(丙二酸)=1∶1.3和反应时间4h条件下,阿魏酸收率为70.87%.%Ferulic acid was synthesized by using vanillic aldehyde and malonic acid as raw materials, and ammonium acetate as the catalyst. The influence of reaction time, molar ratio of reactants, catalyst dosage and volume ratio of cyclohexane to N ,N-dimethylformamide( DMF) on ferulic acid yield was investigated. The experimental results indicated that ferulic acid yield of 70. 87% was attained under the optimum reaction condition as follows;DMF as the solvent,cyclohexane as the water carrying agent,volume ratio of cyclohexane to DMF =2∶1, catalyst dosage 6% of mass of vanillic aldehyde, molar ratio of vanillic aldehyde to malonic acid 1∶1∶3, and reaction time 4 h.

  20. Synthesis of 1-tert-butoxy-4-methylbenzene with p-cresol and isobutene catalyzed by Lewis acid%Lewis酸催化对甲酚与异丁烯合成对叔丁氧基甲苯

    Institute of Scientific and Technical Information of China (English)

    林富荣; 颉林; 周永生

    2012-01-01

    1-tert-Butoxy-4-methylbenzene was prepared through O-alkylation of p-cresol and isobutene catalyzed by Lewis acid. The effects of reaction conditions such as type of catalyst, the amount of catalyst, temperature, and mole ratios between materials on O-alkylation were optimized. The yield of product can be 76% with content of 99. 6% when weight ratio of p-cresol/crystal ferric chloride is 11. 8: 1,molar ratio of isobutene/p-cresol 1.6- 1, reaction temperaturef30 ℃ , reaction time 9 h, condensed isobutene dropped with resistant and constant pressure dropping funnel. The reaction mechanism of O-alkylation catalyzed by Lewis acid was discussed. The method is characterized by excellent atom economy and high selectivity of O-alkylation.%以Lewis酸为催化剂,对甲苯酚与异丁烯经O-烷基化反应合成对叔丁氧基甲苯.考察了催化剂种类、催化剂用量、反应温度、物料比等因素对反应的影响.实验表明适宜的工艺条件是对甲酚与结晶氯化铁的质量比为11.8∶1,异丁烯与对甲酚的物质的量为1.6∶1,异丁烯通过耐压恒压滴液漏斗滴加,反应温度为30℃,反应时间为9h,收率达76%,纯度为99.6%.探讨了Lewis酸催化O-烷基化反应的机理.该方法具有原子经济性好,0-烷基化反应选择性高特点.

  1. Synthesis and Docking Studies of 2,4,6-Trihydroxy-3-Geranylacetophenone Analogs as Potential Lipoxygenase Inhibitor

    Directory of Open Access Journals (Sweden)

    Chean Hui Ng

    2014-08-01

    Full Text Available The natural product molecule 2,4,6-trihydroxy-3-geranyl-acetophenone (tHGA isolated from the medicinal plant Melicope ptelefolia was shown to exhibit potent lipoxygenase (LOX inhibitory activity. It is known that LOX plays an important role in inflammatory response as it catalyzes the oxidation of unsaturated fatty acids, such as linoleic acid to form hydroperoxides. The search for selective LOX inhibitors may provide new therapeutic approach for inflammatory diseases. Herein, we report the synthesis of tHGA analogs using simple Friedel-Craft acylation and alkylation reactions with the aim of obtaining a better insight into the structure-activity relationships of the compounds. All the synthesized analogs showed potent soybean 15-LOX inhibitory activity in a dose-dependent manner (IC50 = 10.31–27.61 μM where compound 3e was two-fold more active than tHGA. Molecular docking was then applied to reveal the important binding interactions of compound 3e in soybean 15-LOX binding site. The findings suggest that the presence of longer acyl bearing aliphatic chain (5Cs and aromatic groups could significantly affect the enzymatic activity.

  2. Diastereoselective Synthesis of Biologically Active Cyclopenta[b]indoles.

    Science.gov (United States)

    Santos, Marilia S; Fernandes, Daniara C; Rodrigues, Manoel T; Regiani, Thais; Andricopulo, Adriano D; Ruiz, Ana Lúcia T G; Vendramini-Costa, Débora B; de Carvalho, João E; Eberlin, Marcos N; Coelho, Fernando

    2016-08-01

    The cyclopenta[b]indole motif is present in several natural and synthetic biologically active compounds, being directly responsible for the biological effects some of them present. We described herein a three step sequence for the synthesis of cyclopenta[b]indoles with a great structural diversity. The method is based on an oxidative Michael addition of suitable indoles on the double bond of Morita-Baylis-Hillman adducts mediated by a hypervalent iodine reagent (IBX) to form β-ketoesters, which were chemoselectively reduced with NaBH4 in THF to give the corresponding β-hydroxy-esters. The diastereoisomeric mixture was then treated with a catalytic amount of triflic acid (20 mol %) to give cyclopenta[b]indoles with overall yields ranging from 8 to 73% (for 2 steps). The acid-catalyzed cyclization step gave the required heterocycles, via an intramolecular Friedel-Crafts reaction, with high diastereoselectivity, where only the trans product was observed. A mechanistic study monitored by ESI-(+)-MS was also conducted to collect evidence about the mechanism of this reaction. The new molecules herein synthesized were also evaluated against a panel of human cancer cells demonstrating a promising antitumoral profile. PMID:27403650

  3. Synthesis and Characterization of Sulfonated Poly(Phenylene Containing a Non-Planar Structure and Dibenzoyl Groups

    Directory of Open Access Journals (Sweden)

    Hohyoun Jang

    2016-02-01

    Full Text Available Polymers for application as sulfonated polyphenylene membranes were prepared by nickel-catalyzed carbon-carbon coupling reaction of bis(4-chlorophenyl-1,2-diphenylethylene (BCD and 1,4-dichloro-2,5-dibenzoylbenzene (DCBP. Conjugated cis/trans isomer (BCD had a non-planar conformation containing four peripheral aromatic rings that facilitate the formation of π–π interactions. 1,4-Dichloro-2,5-dibenzoylbenzene was synthesized from the oxidation reaction of 2,5-dichloro-p-xylene, followed by Friedel-Crafts reaction with benzene. DCBP monomer had good reactivity in polymerization affecting the activity of benzophenone as an electron-withdrawing group. The polyphenylene was sulfonated using concentrated sulfuric acid. These polymers without any ether linkages on the polymer backbone were protected from nucleophilic attack by hydrogen peroxide, hydroxide anion, and radicals generated by polymer electrolyte membrane fuel cell (PEMFC operation systems. The mole fraction of the sulfonic acid groups was controlled by varying the mole ratio of bis(4-chlorophenyl-1,2-diphenylethylene in the copolymer. In comparison with Nafion 211® membrane, these SBCDCBP membranes showed ion exchange capacity (IEC ranging from 1.04 to 2.07 meq./g, water uptake from 36.5% to 69.4%, proton conductivity from 58.7 to 101.9 mS/cm, and high thermal stability.

  4. 固体碱催化合成中碳链脂肪酸聚甘油酯%Synthesis of polyglycerol medium chain fatty acid ester catalyzed by solid base catalyst

    Institute of Scientific and Technical Information of China (English)

    曾哲灵; 邹强; 聂蓉蓉; 龙俊敏; 张驰

    2012-01-01

    以聚甘油、樟树籽仁油脂肪酸为原料,固体碱KOH/Al2O3为催化剂,催化酯化合成中碳链脂肪酸聚甘油酯.采用单因素试验研究反应温度、反应时间、聚甘油与中碳链脂肪酸质量比、催化剂用量对酯化率的影响,通过正交试验优化中碳链脂肪酸聚甘油酯的合成工艺.最优合成工艺条件为反应温度220℃、反应时间2.5h、聚甘油与中碳链脂肪酸质量比2∶1、催化剂用量4.5%,该条件下酯化率为87.5%,所得中碳链脂肪酸聚甘油酯的酸值(KOH)、皂化值(KOH)、碘值(Ⅰ)、熔点分别为1.86 mg/g、148.4 mg/g、2.9 g/100 g、47.3℃.%The solid base KOH/A12O3 was used as catalyst to catalyze esterification of polyglycerol and fatty acids of camphor tree seed kernel oil to synthesize polyglycerol medium chain fatty acid ester. The effects of reaction temperature, reaction time, mass ratio of polyglycerol to medium chain fatty acid and dosage of catalyst on esterification rate were studied by single factor tests, and the synthesis technology of polyglycerol medium chain fatty acid ester was optimized by an orthogonal test. The optimal synthesis conditions were as follows: reaction temperature 220 °C , reaction time 2. 5 h, mass ratio of polyglycerol to medium chain fatty acid 2:1, dosage of catalyst 4. 5%. Under the optimal conditions, the esterification yield reached 87. 5% , and the acid value, saponification value, iodine value, and melting point of the product were 1.86 mgKOH/g,148.4 mgKOH/g, 2.9 gl/100 g and 47. 3 °C , respectively.

  5. Computational Study on the Acid Catalyzed Reactions of Fluorine-Containing 2,4-Dialkoxy-3,4-dihydro-2H-pyrans with Aromatic Compounds

    Directory of Open Access Journals (Sweden)

    Norio Ota

    2012-02-01

    Full Text Available The reaction of 2,4-diethoxy-6-trifluoromethyl-3,4-dihydro-2H-pyran (1 with aromatic compounds in refluxing acetonitrile in the presence of p-toluenesulfonic acid gave the mixture of 4-aryl-2-trifluoromethyl-4H-pyrans (3 and 6-aryl-1,1,1-trifluorohexa-3,5-dien-2-ones (4. In contrast, the same reaction carried out in trifluoroacetic acid at ambient temperature afforded 4-aryl-2-ethoxy-6-trifluoromethyl-3,4-dihydro-2H-pyrans (2 selectively. These two types of reactions giving quite different products under each condition were studied on the basis of DFT calculations. Moreover, the proposed mechanism for the reaction of 5-trifluoroacetyl-6-trifluoromethyl-3,4-dihydro-2H-pyran (5 with aromatic compounds affording butadiene derivatives (6 exclusively was also discussed based on the calculations and comparison with the reactivity of pyrylium intermediate (7.

  6. COPOLYMERIZATION OF CARBON DIOXIDE AND CYCLOHEXENE OXIDE CATALYZED BY ALUMINUM PORPHYRIN-QUATERNARY AMMONIUM SALT IN THE PRESENCE OF BULKY LEWIS ACID

    Institute of Scientific and Technical Information of China (English)

    Yu-sheng Qin; Xian-hong Wang; Xiao-jiang Zhao; Fo-song Wang

    2008-01-01

    Chloro(5,10,15,20-tetraphenyl-porphyrinato)-aluminum/tetraethylammonium bromide (Et4NBr) in combinationwith bulky Lewis acid was used for the copolymerization of CO2 and cyclohexene oxide (CHO). Bulky Lewis acid havingsubstituents at the ortho positions of the phenolate ligands, like methylaluminum bis(2,6-di-tert-butyl-4-methylphenolate),significantly shortened the induction period and raised the catalytic activity, the corresponding turnover frequency reached44.9 h-1 in 9 h, which was 23.8% higher than that from (TPP)AICI/EtaNBr binary catalyst. The resulting polycarbonate hascarbonate linkage over 93% with number average molecular weight of (4.5-6.5)×103 and polydispersity index below 1.10.

  7. Research progress of heteropoly acid catalyzed oxidative desulfurization%杂多酸催化剂催化氧化脱硫研究进展

    Institute of Scientific and Technical Information of China (English)

    张海燕; 代跃利; 蔡蕾

    2013-01-01

    Research progress of applications of heteropoly acid catalyst in the oxidative desulfurization of fuel oil was introduced. Heteropoly acid catalysts, including those containing transition metal, alkali metal, rare earth metal, quaternary ammonium salt, ionic liquid and catalysts supported on carriers, such as carbon materials, titanium dioxide, silica, polymer materials were described and the characteristics and catalytic effects of the catalysts were summerized.Comprehensive utilization of heteropoly acid catalysts' properties and the development of novel high performance heteropoly acid catalysts with high activity, less oxygen consumption and strong reusability were important research topics for deep desulfurization through catalytic oxidation.%介绍了杂多酸催化剂在燃料油氧化脱硫中的应用研究进展.详细叙述了过渡金属、碱金属和稀土金属杂多酸催化剂、杂多酸季铵盐催化剂、杂多酸离子液体催化剂和以碳材料、二氧化钛、二氧化硅、高分子材料等为载体的负载型杂多酸催化剂,阐述了各种杂多酸催化剂的特点及脱硫效果,指出综合应用杂多酸催化剂特性开发活性高、耗氧少、重复使用性强的优良新型杂多酸催化剂是催化氧化深度脱硫的重要研究方向.

  8. VO(acac)2 catalyzed condensation of o-phenylenediamine with aromatic carboxylic acids/aldehydes under microwave radiation affording benzimidazoles

    Institute of Scientific and Technical Information of China (English)

    Madhudeepa Dey; Krishnajyoti Deb; Siddhartha Sankar Dhar

    2011-01-01

    Vanadyl acetylacetonate, VO(acac)2, has been found to be very effective catalyst for synthesis of a variety of benzimidazoles under solvent-free condition. The methodology involves the exposure of a mixture of o-phenylenediamine and a selected aromatic carboxylic acid/aldehyde to microwave radiation without the use of any solvent or supporting agents. The benzimidazoles were obtained in quick time with high yields.

  9. Thermally Stable Forms of Pure Polyaniline Catalyzed by an Acid-Exchanged Montmorillonite Clay Called Maghnite- H + as an Effective Catalyst

    OpenAIRE

    Rahmouni Abdelkader; Harrane Amine; Belbachir Mohammed

    2012-01-01

    Polyaniline salt form (PANI-ES) was synthesized by oxidative polymerization of aniline using potassium persulfate as an oxidant and an acid-exchanged montmorillonite clay called Maghnite-H+ as an effective catalyst. The clay, which was used as a catalyst, was supplied by a local company known as ENOF Maghnia (Western Algeria). The chemical stability of PANI has been investigated by thermogravimetry and differential scanning calorimetry, that a good thermal stability of PANI could be improved ...

  10. Sulphamic Acid (H2NSO3H)-Catalyzed Multicomponent Reaction of β-Naphthol: An Expeditious Synthesis of Amidoalkyl Naphthols

    Institute of Scientific and Technical Information of China (English)

    NAGAWADE Rahul R.; SHINDE Devanand B.

    2007-01-01

    Sulphamic acid (H2NSO3H) was found to be an efficient catalyst for the multicomponent condensation reaction of β-naphthol, aromatic aldehydes and urea or amides to afford the corresponding a-amidoalkyl-β-naphthols in good yields. The remarkable features of this new procedure are high conversions, short reaction time, clean reaction profiles and simple experimental and work-up procedures.

  11. Structured lipids via lipase-catalyzed incorporation of eicosapentaenoic acid into borage (Borago officinalis L.) and evening primrose (Oenothera biennis L.) oils.

    Science.gov (United States)

    Senanayake, S P J Namal; Shahidi, Fereidoon

    2002-01-30

    Enzymatic acidolysis of borage oil (BO) or evening primrose oil (EPO) with eicosapentaenoic acid (20:5n-3; EPA) was studied. Of the six lipases that were tested in the initial screening, nonspecific lipase PS-30 from Pseudomonas sp. resulted in the highest incorporation of EPA into both oils. This enzyme was further studied for the influence of enzyme load, temperature, time, type of organic solvent, and mole ratio of substrates. The products from the acidolysis reaction were analyzed by gas chromatography (GC). The highest incorporation of EPA in both oils occurred at 45-55 degrees C and at 150-250 enzyme activity units. One unit of lipase activity was defined as nanomoles of fatty acids (oleic acid equivalents) produced per minute per gram of enzyme. Time course studies indicated that EPA incorporation was increased up to 26.8 and 25.2% (after 24 h) in BO and EPO, respectively. Among the solvents examined, n-hexane served best for the acidolysis of EPA with both oils. The effect of the mole ratio of oil to EPA was studied from 1:1 to 1:3. As the mole ratio of EPA increased, the incorporation increased from 25.2-26.8 to 37.4-39.9% (after 24 h). The highest EPA incorporations of 39.9 and 37.4% in BO and EPO, respectively, occurred at the stoichiometric mole ratio of 1:3 for oil to EPA. PMID:11804516

  12. High-yield preparation of wax esters via lipase-catalyzed esterification using fatty acids and alcohols from crambe and camelina oils.

    Science.gov (United States)

    Steinke, G; Weitkamp, P; Klein, E; Mukherjee, K D

    2001-02-01

    Fatty acids obtained from seed oils of crambe (Crambe abyssinica) and camelina (Camelina sativa) via alkaline saponification or steam splitting were esterified using lipases as biocatalysts with oleyl alcohol and the alcohols derived from crambe and camelina oils via hydrogenolysis of their methyl esters. Long-chain wax esters were thus obtained in high yields when Novozym 435 (immobilized lipase B from Candida antarctica) and papaya (Carica papaya) latex lipase were used as biocatalysts and vacuum was applied to remove the water formed. The highest conversions to wax esters were obtained with Novozym 435 (> or =95%) after 4-6 h of reaction, whereas with papaya latex lipase such a high degree of conversion was attained after 24 h. Products obtained from stoichiometric amounts of substrates were almost exclusively (>95%) composed of wax esters having compositions approaching that of jojoba (Simmondsia chinensis) oil, especially when crambe fatty acids in combination with camelina alcohols or camelina fatty acids in combination with crambe alcohols were used as substrates.

  13. Effective Liquid-phase Nitration of Benzene Catalyzed by a Stable Solid Acid Catalyst: Silica Supported Cs2.5H0.5PMo12O40

    International Nuclear Information System (INIS)

    Silica supported Cs2.5H0.5PMo12O40 catalyst was prepared through sol-gel method with ethyl silicate-40 as silicon resource and characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, nitrogen adsorption-desorption and potentiometric titration methods. The Cs2.5H0.5PMo12O40 particles with Keggin-type structure well dispersed on the surface of silica, and the catalyst exhibited high surface area and acidity. The catalytic performance of the catalysts for benzene liquid-phase nitration was examined with 65% nitric acid as nitrating agent, and the effects of various parameters were tested, which including temperature, time and amount of catalyst, reactants ratio, especially the recycle of catalyst was emphasized. Benzene was effectively nitrated to mononitro-benzene with high conversion (95%) in optimized conditions. Most importantly, the supported catalyst was proved has excellent stability in the nitration progress, and there were no any other organic solvent and sulfuric acid were used in the reaction system, so the liquid-phase nitration of benzene that we developed was an eco-friendly and attractive alternative for the commercial technology

  14. 固体酸催化合成二氯乙酸乙酯%Synthesis of ethyl dichloroacetate catalyzed by solid acid

    Institute of Scientific and Technical Information of China (English)

    刘俊峰; 朱莹莹; 冯桂英; 王胜华; 何超

    2014-01-01

    One kind of method was introduled for the synthesis of dichloro -acetic acid ethyl ester. Dichloroacetic acid was used as staring material,the catalysis of the catalyst on dehydration of dichloroacetic acid and ethanol to produce the ether was discussed.At the same times,The effects of different water-carrying agent such as benzene,toluene,cyclohexane and their dosage on the reaction were investigated.Taking FeCl3·6H2O as catalyst,cyclohexane as dehydrant,ethanol as reaction solvent and raw materials,dichloro-acetic acid ethyl ester was product.The best reaction condition was as follows:12.9 g dichloroacetic acid,20 ml dehydrated alcohol,15 ml cyclohexane,0.5 g ferric trichloride,reaction temperature was reflux ,reaction time was 40 min. After the reaction was finished ,distilling and collecting 153 ~156 ℃ distillation to get dichloro -acetic acid ethyl ester of a colourless liquid.The yield was 85 .4% and the purity is greater than or equa 98%.After the solvent was distilled,the catalyst was reused total 240 mins.The dichloro-acetic acid ethyl ester productivities of four tests are as follows respectively:85.4%,77.1%,83.4%,78.3%.%介绍一种二氯乙酸乙酯的合成方法.以二氯乙酸为起始原料,研究了催化剂对二氯乙酸与乙醇脱水醚化反应的催化性能,同时讨论了不同带水剂苯、甲苯、环己烷及其用量对反应的影响,得到以FeCl3·6H2 O为催化剂,环己烷为带水剂,乙醇既作反应原料又为溶剂,制备二氯乙酸乙酯,最佳反应条件:二氯乙酸12.9 g,无水乙醇20 mL,环己烷15 mL,催化剂用量0.5 g,反应温度:回流,反应时间40 min.反应产物蒸馏收集153~156℃的馏分得到无色液体二氯乙酸乙酯,纯度大于98%,蒸干溶剂后,进行催化剂重复使用试验,其结果为:重复反应4次,累计反应时间为240 min,二氯乙酸乙酯产率分别为85.4%,77.1%,83.4%,78.3%.

  15. Antibody-Catalyzed Degradation of Cocaine

    Science.gov (United States)

    Landry, Donald W.; Zhao, Kang; Yang, Ginger X.-Q.; Glickman, Michael; Georgiadis, Taxiarchis M.

    1993-03-01

    Immunization with a phosphonate monoester transition-state analog of cocaine provided monoclonal antibodies capable of catalyzing the hydrolysis of the cocaine benzoyl ester group. An assay for the degradation of radiolabeled cocaine identified active enzymes. Benzoyl esterolysis yields ecgonine methyl ester and benzoic acid, fragments devoid of cocaine's stimulant activity. Passive immunization with such an artificial enzyme could provide a treatment for dependence by blunting reinforcement.

  16. Tritium catalyzed deuterium tokamaks

    International Nuclear Information System (INIS)

    A preliminary assessment of the promise of the Tritium Catalyzed Deuterium (TCD) tokamak power reactors relative to that of deuterium-tritium (D-T) and catalyzed deuterium (Cat-D) tokamaks is undertaken. The TCD mode of operation is arrived at by converting the 3He from the D(D,n)3He reaction into tritium, by neutron capture in the blanket; the tritium thus produced is fed into the plasma. There are three main parts to the assessment: blanket study, reactor design and economic analysis and an assessment of the prospects for improvements in the performance of TCD reactors (and in the promise of the TCD mode of operation, in general)

  17. Asymmetric Ring-Opening of Cyclopropyl Ketones with Thiol, Alcohol, and Carboxylic Acid Nucleophiles Catalyzed by a Chiral N,N'-Dioxide-Scandium(III) Complex.

    Science.gov (United States)

    Xia, Yong; Lin, Lili; Chang, Fenzhen; Fu, Xuan; Liu, Xiaohua; Feng, Xiaoming

    2015-11-01

    A highly efficient asymmetric ring-opening reaction of cyclopropyl ketones with a broad range of thiols, alcohols and carboxylic acids has been first realized by using a chiral N,N'-dioxide-scandium(III) complex as catalyst. The corresponding sulfides, ethers, and esters were obtained in up to 99% yield and 95% ee. This is also the first example of one catalytic system working for the ring-opening reaction of donor-acceptor cyclopropanes with three different nucleophiles, let alone in an asymmetric version. PMID:26398505

  18. Influence of acid-base properties on the Lebedev ethanol-to-butadiene process catalyzed by SiO2-MgO materials

    OpenAIRE

    Angelici, Carlo; Velthoen, Marjolein E. Z.; Weckhuysen, Bert M.; Bruijnincx, Pieter C. A.

    2015-01-01

    The Lebedev ethanol-to-butadiene process entails a complex chain of reactions that require catalysts to possess a subtle balance in the number and strength of acidic and basic sites. SiO2-MgO materials can be excellent Lebedev catalysts if properly prepared, as catalyst performance has been found to depend significantly on the synthesis method. To assess the specific requirements for butadiene production in terms of active sites and to link their presence to the specific preparation method ap...

  19. Direct and remarkably efficient conversion of methane into acetic acid catalyzed by amavadine and related vanadium complexes. A synthetic and a theoretical DFT mechanistic study.

    Science.gov (United States)

    Kirillova, Marina V; Kuznetsov, Maxim L; Reis, Patrícia M; da Silva, José A L; da Silva, João J R Fraústo; Pombeiro, Armando J L

    2007-08-29

    Vanadium(IV or V) complexes with N,O- or O,O-ligands, i.e., [VO{N(CH2CH2O)3}], Ca[V(HIDPA)2] (synthetic amavadine), Ca[V(HIDA)2], or [Bu4N]2[V(HIDA)2] [HIDPA, HIDA = basic form of 2,2'-(hydroxyimino)dipropionic or -diacetic acid, respectively], [VO(CF3SO3)2], Ba[VO(nta)(H2O)]2 (nta = nitrilotriacetate), [VO(ada)(H2O)] (ada = N-2-acetamidoiminodiacetate), [VO(Hheida)(H2O)] (Hheida = 2-hydroxyethyliminodiacetate), [VO(bicine)] [bicine = basic form of N,N-bis(2-hydroxyethyl)glycine], and [VO(dipic)(OCH2CH3)] (dipic = pyridine-2,6-dicarboxylate), are catalyst precursors for the efficient single-pot conversion of methane into acetic acid, in trifluoroacetic acid (TFA) under moderate conditions, using peroxodisulfate as oxidant. Effects on the yields and TONs of various factors are reported. TFA acts as a carbonylating agent and CO is an inhibitor for some systems, although for others there is an optimum CO pressure. The most effective catalysts (as amavadine) bear triethanolaminate or (hydroxyimino)dicarboxylates and lead, in a single batch, to CH3COOH yields > 50% (based on CH4) or remarkably high TONs up to 5.6 x 103. The catalyst can remain active upon multiple recycling of its solution. Carboxylation proceeds via free radical mechanisms (CH3* can be trapped by CBrCl3), and theoretical calculations disclose a particularly favorable process involving the sequential formation of CH3*, CH3CO*, and CH3COO* which, upon H-abstraction (from TFA or CH4), yields acetic acid. The CH3COO* radical is formed by oxygenation of CH3CO* by a peroxo-V complex via a V{eta1-OOC(O)CH3} intermediate. Less favorable processes involve the oxidation of CH3CO* by the protonated (hydroperoxo) form of that peroxo-V complex or by peroxodisulfate. The calculations also indicate that (i) peroxodisulfate behaves as a source of sulfate radicals which are methane H-abstractors, as a peroxidative and oxidizing agent for vanadium, and as an oxidizing and coupling agent for CH3CO* and that (ii) TFA is

  20. 固体酸催化合成乳酸正丁酯%Synthesis of n-Butyl Lactate Catalyzed by Solid Acid

    Institute of Scientific and Technical Information of China (English)

    苏兆祥; 邓旭忠; 杨辉荣; 谢光炎

    2000-01-01

    In the presence of roasted ferric sulfate as catalyst,lactic acid can react with n-butyl alcohol to form n-butyl lactate. The optimum conditions are follows:molar ratio of lactic acid to n-butyl alcohol = 1:4.5,reaction temperature time = 150min, weight of catalyst=2g. The yield under the optimum conditions was up to 87.4%.The catalyst has many advantages,such as being able to manufacture very easy,use repeatedly and less pollution to the environment.%以焙烧的Fe2(SO4)3为催化剂,实现了乳酸与正丁酸与正丁醇反应合成乳酸正丁酯.最佳合成条件为:以0.085mol乳酸为准,乳酸与丁醇的摩尔比是1:4,催化剂用量为2g,反应时间为150min,产率达87.4%.该催化剂具有制备易,可循环使用,不污染环境等优点.

  1. 对甲苯磺酸催化查尔酮的合成%Synthtsis of Chalcone Catalyzed by P-toluenesulfonic Acid

    Institute of Scientific and Technical Information of China (English)

    谭昌会; 郑荣选; 罗淑云; 林俏焰

    2012-01-01

    研究了查耳酮的制备方法和缩合反应的影响因素选择最佳的反应条件,实验的结果表明,合成查尔酮的缩合反应的较佳条件是:n(苯乙酮)加(间硝基苯甲醛)=1∶1,反应温度是70℃,反应的时间3h,对甲笨磺酸为3 g,乙酸用量为20 mL,在此条件下查尔酮的收率达71.6%.%Synthesis methods of chalcone were studied, affecting factors of the condensation reaction were discussed so as to select the best reaction conditions. The experimental results show that the better reaction conditions of the synthesis are as follows: n (m-nitrobenzaldehyde) / n (preparation) = 1 : 1, the reaction temperature is 70 ℃, the reaction time is 3 h, p-toluene sulfonic acid dosage and acetic acid dosage are 3 g and 20 mL , respectively. Under above conditions, the chalcone yield can reach 71.6%.

  2. Production of oleic acid ethyl ester catalyzed by crude rice bran (Oryza sativa lipase in a modified fed-batch system: problem and its solution

    Directory of Open Access Journals (Sweden)

    Indro Prastowo

    2015-01-01

    Full Text Available A fed-batch system was modified for the enzymatic production of Oleic Acid Ethyl Ester (OAEE using rice bran (Oryza sativa lipase by retaining the substrate molar ratio (ethanol/oleic acid at 2.05: 1 during the reaction. It resulted in an increase in the ester conversion up to 76.8% in the first 6 h of the reaction, and then followed by a decrease from 76.8% to 22.9% in 6 h later. Meanwhile, the production of water in the reaction system also showed a similar trend to the trend of ester production. The water was hypothesized to lead lipase to reverse the reaction which resulted in a decrease in both (water and esters in the last 6 h of the reaction. In order to overcome the problem, zeolite powders (25 and 50 mg/ml were added into the reaction system at 5 h of the reaction. As the result, final ester conversions increased drastically up to 90 - 95.7% (1.17 – 1.24 times. The addition also proved a hypothesis that the water was involved in reducing the ester conversion in the last 6 h of the reaction. Thus, the combination was effective to produce the high final ester conversion.

  3. The mechanism of Fe (Ⅲ)-catalyzed ozonation of phenol

    Institute of Scientific and Technical Information of China (English)

    竹湘锋; 徐新华

    2004-01-01

    Fe (Ⅲ)-catalyzed ozonation yielded better degradation rate and extent of COD (Chemical Oxygen Demand) or oxalic acid as compared with oxidation by ozone alone. Two parameters with strong effects on the efficiency of ozonation are pH of the solution and the catalyst (Fe3+) dosage. The existence of a critical pH value determining the catalysis of Fe (Ⅲ) in acid conditions was observed in phenol and oxalic acid systems. The best efficiency of catalysis was obtained at a moderate concentration of the catalyst. A reasonable mechanism of Fe (Ⅲ)-catalyzed ozonation of phenol was obtained based on the results and literature.

  4. Mechanism of the Enantioselective Intramolecular [2 + 2] Photocycloaddition Reaction of Coumarin Catalyzed by a Chiral Lewis Acid: Comparison with Enone Substrates.

    Science.gov (United States)

    Wang, Hongjuan; Fang, Wei-Hai; Chen, Xuebo

    2016-08-19

    The asymmetric catalysis of the intramolecular enone [2 + 2] photocycloaddition reaction relies on a complicated regulation mechanism to control its reactivity and selectivity as well as quantum yield. The multiconfiguration perturbation theory associated with energy-consistent relativistic pseudopotentials offers a mechanistic comparison between representative coumarin and enone substrates. A pair of bright ππ* states govern the unselective background reaction of the free coumarin through the direct cycloaddition in the singlet hypersurface and the elimination of the reaction channel in the triplet manifold due to the existence of anti El Sayed type singlet-triplet crossing. The opening of a reaction channel in the triplet state is repeatedly verified to depend on the presence of relativistic effects, i.e., spin-orbit coupling due to heavy atoms in the chiral Lewis acid catalyst. PMID:27322795

  5. Thermally Stable Forms of Pure Polyaniline Catalyzed by an Acid-Exchanged Montmorillonite Clay Called Maghnite-H+ as an Effective Catalyst

    Directory of Open Access Journals (Sweden)

    Rahmouni Abdelkader

    2012-01-01

    Full Text Available Polyaniline salt form (PANI-ES was synthesized by oxidative polymerization of aniline using potassium persulfate as an oxidant and an acid-exchanged montmorillonite clay called Maghnite-H+ as an effective catalyst. The clay, which was used as a catalyst, was supplied by a local company known as ENOF Maghnia (Western Algeria. The chemical stability of PANI has been investigated by thermogravimetry and differential scanning calorimetry, that a good thermal stability of PANI could be improved by combining PANI with montmorillonite. TGA results illustrated that there were two major stages for weight loss of the ES-form PANI powder sample. The different forms of PANI were characterized by infrared spectroscopy, thermal analysis, and H-NMR spectroscopy and conductivity measurements.

  6. Palladium(II)-catalyzed oxidation of L-tryptophan by hexacyanoferrate(III) in perchloric acid medium: a kinetic and mechanistic approach

    Indian Academy of Sciences (India)

    Ahmed Fawzy

    2016-02-01

    The catalytic effect of palladium(II) on the oxidation of L-tryptophan by potassium hexacyanoferrate( III) has been investigated spectrophotometrically in aqueous perchloric acid medium. A first order dependence in [hexacyanoferrate(III)] and fractional-first order dependences in both [L-tryptophan] and [palladium(II)] were obtained. The reaction exhibits fractional-second order kinetics with respect to [H+]. Reaction rate increased with increase in ionic strength and dielectric constant of the medium. The effect of temperature on the reaction rate has also been studied and activation parameters have been evaluated and discussed. Initial addition of the reaction product, hexacyanoferrate(II), does not affect the rate significantly. A plausible mechanistic scheme explaining all the observed kinetic results has been proposed. The final oxidation products are identified as indole-3-acetaldehyde, ammonium ion and carbon dioxide. The rate law associated with the reaction mechanism is derived.

  7. A propionate CoA-transferase of Ralstonia eutropha H16 with broad substrate specificity catalyzing the CoA thioester formation of various carboxylic acids.

    Science.gov (United States)

    Lindenkamp, Nicole; Schürmann, Marc; Steinbüchel, Alexander

    2013-09-01

    In this study, we have investigated a propionate CoA-transferase (Pct) homologue encoded in the genome of Ralstonia eutropha H16. The corresponding gene has been cloned into the vector pET-19b to yield a histidine-tagged enzyme which was expressed in Escherichia coli BL21 (DE3). After purification, high-performance liquid chromatography/mass spectrometry (HPLC/MS) analyses revealed that the enzyme exhibits a broad substrate specificity for carboxylic acids. The formation of the corresponding CoA-thioesters of acetate using propionyl-CoA as CoA donor, and of propionate, butyrate, 3-hydroxybutyrate, 3-hydroxypropionate, crotonate, acrylate, lactate, succinate and 4-hydroxybutyrate using acetyl-CoA as CoA donor could be shown. According to the substrate specificity, the enzyme can be allocated in the family I of CoA-transferases. The apparent molecular masses as determined by gel filtration and detected by SDS polyacrylamide gel electrophoresis were 228 and 64 kDa, respectively, and point to a quaternary structure of the native enzyme (α4). The enzyme exhibited similarities in sequence and structure to the well investigated Pct of Clostridium propionicum. It does not contain the typical conserved (S)ENG motif, but the derived motif sequence EXG with glutamate 342 to be, most likely, the catalytic residue. Due to the homo-oligomeric structure and the sequence differences with the subclasses IA-C of family I CoA-transferases, a fourth subclass of family I is proposed, comprising - amongst others - the Pcts of R. eutropha H16 and C. propionicum. A markerless precise-deletion mutant R. eutropha H16∆pct was generated. The growth and accumulation behaviour of this mutant on gluconate, gluconate plus 3,3'-dithiodipropionic acid (DTDP), acetate and propionate was investigated but resulted in no observable phenotype. Both, the wild type and the mutant showed the same growth and storage behaviour with these carbon sources. It is probable that R. eutropha H16 is upregulating

  8. Rhodotorula glutinis Phenylalanine/Tyrosine Ammonia Lyase Enzyme Catalyzed Synthesis of the Methyl Ester of para-Hydroxycinnamic Acid and its Potential Antibacterial Activity

    Science.gov (United States)

    MacDonald, Marybeth C.; Arivalagan, Pugazhendhi; Barre, Douglas E.; MacInnis, Judith A.; D’Cunha, Godwin B.

    2016-01-01

    Biotransformation of L-tyrosine methyl ester (L-TM) to the methyl ester of para- hydroxycinnamic acid (p-HCAM) using Rhodotorula glutinis yeast phenylalanine/tyrosine ammonia lyase (PTAL; EC 4.3.1.26) enzyme was successfully demonstrated for the first time; progress of the reaction was followed by spectrophotometric determination at 315 nm. The following conditions were optimized for maximal formation of p-HCAM: pH (8.5), temperature (37°C), speed of agitation (50 rpm), enzyme concentration (0.080 μM), and substrate concentration (0.50 mM). Under these conditions, the yield of the reaction was ∼15% in 1 h incubation period and ∼63% after an overnight (∼18 h) incubation period. The product (p-HCAM) of the reaction of PTAL with L-TM was confirmed using Nuclear Magnetic Resonance spectroscopy (NMR). Fourier Transform Infra-Red spectroscopy (FTIR) was carried out to rule out potential hydrolysis of p-HCAM during overnight incubation. Potential antibacterial activity of p-HCAM was tested against several strains of Gram-positive and Gram-negative bacteria. This study describes a synthetically useful transformation, and could have future clinical and industrial applications. PMID:27014206

  9. Nitric acid activation of graphite granules to increase the performance of the non-catalyzed oxygen reduction reaction (ORR) for MFC applications

    Energy Technology Data Exchange (ETDEWEB)

    Erable, Benjamin [School of Chemical Engineering and Advanced Materials, Newcastle University, Newcastle upon Tyne - NE1 7RU (United Kingdom); Laboratoire de Genie Chimique, CNRS-Universite de Toulouse, 5 rue Paulin Talabot, BP1301, 31106 Toulouse (France); Duteanu, Narcis [School of Chemical Engineering and Advanced Materials, Newcastle University, Newcastle upon Tyne - NE1 7RU (United Kingdom); Faculty of Industrial Chemistry and Environmental Engineering, University ' ' POLITEHNICA' ' Timisoara, 300006 Timisoara (Romania); Kumar, S.M. Senthil; Scott, Keith [School of Chemical Engineering and Advanced Materials, Newcastle University, Newcastle upon Tyne - NE1 7RU (United Kingdom); Feng, Yujie [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, No. 202, Haihe Road, Harbin 150090 (China); Ghangrekar, Makarand M. [School of Chemical Engineering and Advanced Materials, Newcastle University, Newcastle upon Tyne - NE1 7RU (United Kingdom); Department of Civil Engineering, Indian Institute of Technology, Kharagpur - 721302 (India)

    2009-07-15

    Nitric acid and thermal activation of graphite granules were explored to increase the electrocatalytic performance of dissolved oxygen reduction at neutral pH for microbial fuel cell (MFC) applications. Electrochemical experiments showed an improvement of +400 mV in open circuit potential for graphite granules when they were activated. The improvement of ORR performance observed with activated granules was correlated to the increase of Brunauer-Emmett-Teller (BET) surface of the activated material and the emergence of nitrogen superficial groups revealed by X-ray photoelectron spectroscopy (XPS) analysis on its surface. The use of activated graphite granules in the cathodic compartment of a dual-chamber MFC led to a high open circuit voltage of 1050 mV, which is among one of the highest reported so far. The stable performance of this cathode material (current density of 96 A m{sup -3} at +200 mV/Ag-AgCl) over a period of 10 days demonstrated its applicability as a cathode material without any costly noble metal. (author)

  10. Sonolytic and Silent Polymerization of Methacrlyic Acid Butyl Ester Catalyzed by a New Onium Salt with bis-Active Sites in a Biphasic System — A Comparative Investigation

    Directory of Open Access Journals (Sweden)

    Perumberkandgai A. Vivekanand

    2013-02-01

    Full Text Available Currently, ingenious new analytical and process experimental techniques which are environmentally benign techniques, viz., ultrasound irradiation, have become immensely popular in promoting various reactions. In this work, a novel soluble multi-site phase transfer catalyst (PTC viz., 1,4-bis-(propylmethyleneammounium chloridebenzene (BPMACB was synthesized and its catalytic efficiency was assessed by observing the kinetics of sonolytic polymerization of methacrylic acid butyl ester (MABE using potassium persulphate (PPS as an initiator. The ultrasound–multi-site phase transfer catalysis (US-MPTC-assisted polymerization reaction was compared with the silent (non-ultrasonic polymerization reaction. The effects of the catalyst and various reaction parameters on the catalytic performance were in detail investigated by following the kinetics of polymerization of MABE in an ethyl acetate-water biphasic system. From the detailed kinetic investigation we propose a plausible mechanism. Further the kinetic results demonstrate clearly that ultrasound-assisted phase-transfer catalysis significantly increased the reaction rate when compared to silent reactions. Notably, this environmentally benign and cost-effective process has great potential to be applied in various polymer industries.

  11. Syntheses and Crystal Structures of Chiral BINOL Derivatives and Their Applications in Enantioselective Lewis Acid Catalyzed Addition of Diethylzinc to Aldehydes

    Institute of Scientific and Technical Information of China (English)

    LIU Guo-Hua; YU Han; Yang Liang-Zhun; YAO Mei; FANG Hai-Bin; XUE Yun-Ning

    2007-01-01

    Two novel chiral BINOL derivatives with bis(benzylamine) groups at the 3,3' positions have been synthesized through the condensation reaction between 2,2'-bis(methoxy- methyleneoxy)-1,1'-binaphthyl-3,3'-dicarboxylic acid and benzylamine or N-phenyl benzylamine in the presence of triethylamine. Suitable single crystal of (R)-N,N'-dibenzyl-2,2'-dihydroxy-1,1'-binaphthly-3,3'-diformamide (R)-3 for X-ray diffraction was obtained by recrystallization at room temperature from the mixture solvents. Crystallographic data of (R)-3: C40H36N2O6, Mr=640.71, monoclinic, space group P21, a=6.746(3), b=21.883(9), c=11.723(5) (A), β=104.605(7)°, Z=2, V=1674.7(12) (A)3, Dc=1.271 g/cm3, F(000)=676, R=0.0729, Wr=0.1687 and μ(MoKα)=0.086 mm-1. Two chiral BINOL ligands were found to be effective in the enantioselective addition of diethylzinc to aldehydes and much different enantioselectivity was observed both in the presence and absence of Ti(OiPr)4. In the former case, (R)-3 showed moderate enantioselectivity, which was lower than that of (R)-BINOL's; and in the latter case, (R)-4 gave the highest enantioselectivity up to 93.3% ee.*

  12. Rhodotorulaglutinis phenylalanine/tyrosine ammonia lyase enzyme catalyzed synthesis of the methyl ester of para-hydroxycinnamic acid and its potential antibacterial activity

    Directory of Open Access Journals (Sweden)

    Marybeth C MacDonald

    2016-03-01

    Full Text Available Biotransformation of L-tyrosine methyl ester (L-TM to the methyl ester of para- hydroxycinnamic acid (p-HCAM using Rhodotorula glutinis yeast phenylalanine/tyrosine ammonia lyase (PTAL; EC 4.3.1.26 enzyme was successfully demonstrated for the first time; progress of the reaction was followed by spectrophotometric determination at 315 nm. The following conditions were optimized for maximal formation of p-HCAM: pH (8.5, temperature (37 C, speed of agitation (50 rpm, enzyme concentration (0.080 µM, and substrate concentration (0.50 mM. Under these conditions, the yield of the reaction was ~15% in 1 h incubation period and ~63% after an overnight (~18 h incubation period. The product (p-HCAM of the reaction of PTAL with L-TM was confirmed using Nuclear Magnetic Resonance spectroscopy (NMR. Fourier Transform Infra-Red spectroscopy (FTIR was carried out to rule out potential hydrolysis of p-HCAM during overnight incubation. Potential antibacterial activity of p-HCAM was tested against several strains of Gram positive and Gram negative bacteria. This study describes a synthetically useful transformation, and could have future clinical and industrial applications.

  13. Rhodotorula glutinis Phenylalanine/Tyrosine Ammonia Lyase Enzyme Catalyzed Synthesis of the Methyl Ester of para-Hydroxycinnamic Acid and its Potential Antibacterial Activity.

    Science.gov (United States)

    MacDonald, Marybeth C; Arivalagan, Pugazhendhi; Barre, Douglas E; MacInnis, Judith A; D'Cunha, Godwin B

    2016-01-01

    Biotransformation of L-tyrosine methyl ester (L-TM) to the methyl ester of para- hydroxycinnamic acid (p-HCAM) using Rhodotorula glutinis yeast phenylalanine/tyrosine ammonia lyase (PTAL; EC 4.3.1.26) enzyme was successfully demonstrated for the first time; progress of the reaction was followed by spectrophotometric determination at 315 nm. The following conditions were optimized for maximal formation of p-HCAM: pH (8.5), temperature (37°C), speed of agitation (50 rpm), enzyme concentration (0.080 μM), and substrate concentration (0.50 mM). Under these conditions, the yield of the reaction was ∼15% in 1 h incubation period and ∼63% after an overnight (∼18 h) incubation period. The product (p-HCAM) of the reaction of PTAL with L-TM was confirmed using Nuclear Magnetic Resonance spectroscopy (NMR). Fourier Transform Infra-Red spectroscopy (FTIR) was carried out to rule out potential hydrolysis of p-HCAM during overnight incubation. Potential antibacterial activity of p-HCAM was tested against several strains of Gram-positive and Gram-negative bacteria. This study describes a synthetically useful transformation, and could have future clinical and industrial applications.

  14. 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

  15. Lipase-catalyzed synthesis of L-ascorbyl fatty acid esters and D-isoascorbyl fatty acid esters%脂肪酶催化合成L-抗坏血酸脂肪酸酯和D-异抗坏血酸脂肪酸酯

    Institute of Scientific and Technical Information of China (English)

    郑大贵; 祝显虹; 余泗莲; 彭化南; 张小兰

    2012-01-01

    The lipase-catalyzed synthesis of L.-ascorbyl fatty acid esters and D-isoascorbyl fatty acid esters were studied by direct es-terification and transesterification,respectively. The structures of products were confirmed by IR,1H NMR,13C NMR and MS. It was found that the yield of the direct esterification were higher than that of the corresponding transesterification under the similar synthetic conditions. The raw material fatty acids and fatty acid methyl esters could be recycled and reused.%用固定化脂肪酶Lipozyme 435作催化剂,分别用直接酯化法和酯交换法合成L-抗坏血酸脂肪酸酯和D-异抗坏血酸脂肪酸酯.产物结构经IR、1HNMR、13CNMR和MS表征.结果表明,对于同一目标化合物,相似条件下,直接酯化法的效果优于酯交换法,原料脂肪酸和脂肪酸甲酯均可回收循环使用.

  16. Liquefaction of wheat straw catalyzed by acidic ionic liquid and analysis of liquefied products%酸性离子液体催化麦秸液化及其产物分析

    Institute of Scientific and Technical Information of China (English)

    关倩; 蒋剑春; 徐俊明; 王奎; 冯君锋

    2016-01-01

    With the increasing energy requirements and pollution problems worldwide, energy from renewable resources has received global attention in recent decades. Biomass is one of the most abundant renewable resources. It mainly includes forest residues, agricultural wastes, industrial residues, municipal solid wastes, bagasse, aquatic plants, and algae animal wastes. Due to the advantages of abundance, non-polluting, being renewable and easy to obtain, biomass is considered as the most promising energy feedstock to replace the traditional energy. Meanwhile, it is the only resource that can be converted into solid, liquid, and gaseous products for use of fuels. Thermo-chemical conversion is an effective technology of biomass conversion. Liquefaction is the typical thermo-chemical technology for the conversion of biomass to obtain liquid biofuels and valuable chemicals, such as bio-oil and fuel additives. The conversion process is not only influenced by organic reagents but also by different catalysts. Effective catalyst is an essential factor to improve liquefaction efficiency. As catalyst, sulfuric acid has very strong corrosion and needs high-quality liquefaction equipment, and its recycling is difficult. Solid acid is used to overcome shortcomings of organic acid in the liquefaction, but it is easy to form coke to cause the deactivation of catalyst, and needs to be calcined before re-use, which increases the reaction cost. Now, it is found that the ionic liquid has non-corrosiveness, low melting point, high thermal stability and low vapor pressure, and some other merits. It has a broad application prospect used as solvents and catalysts in catalytic reactions. Ionic liquid, especially sulfonated bisulfate ionic liquid can dissolve cellulose, because it has higher acidic sites that can easily break the hydrogen bonds of biomass material, and promote the degradation and conversion of cellulose. At present, ionic liquid is usually used to catalyze carbohydrate, which is

  17. 杂交杨木纤维中碳水化合物的稀酸催化分离%Dilute Acid-catalyzed Fractionation of Carbohydrates in Hybrid Poplar Fibers

    Institute of Scientific and Technical Information of China (English)

    张春辉; Troy Runge; 詹怀宇

    2012-01-01

    In this paper, the acid-catalyzed fractionation of pentosans and hexosans from hybrid poplar fibers was studied using a circulation reactor. Kinetic models of both pentosan and hexosan hydrolysis/degradation were crea- ted to predict the hydrolysis yield of both substances. The extraction conditions were varied, including a tempera- ture range of 140 - 170℃ , a sulfuric acid concentration range of 0.1% - 0.9% wt with a constant liquor-to-wood ratio of 6: 1. The yields of both substances were favored at high acid concentration and temperature, while pentosan being considerable more reactive. Under optimal conditions, 91 percent of pentosan could be separated from the fi- ber, while more than 93 percent of hexosan was retained in the solids. This study demonstrates that pentosan and hexosans could be fractionated from poplar fibers using acid hydrolysis and converted into liquid fuel and valued chemicals separately.%本文采用循环式反应器研究了杂交杨木纤维中聚戊糖和聚己糖在稀酸条件下的催化分离,分别得出了聚戊糖和聚己糖稀酸水解/降解的动力学模型,以预测在不同反应条件下戊糖和己糖的水解得率。反应条件为温度140~170℃,硫酸浓度0.1%~0.9%wt,液比为6:1。研究发现,较高的酸浓和温度对提高戊糖和己糖的得率都有利,但相同条件下聚戊糖的反应活性更高。经动力学模型优化得出,在较佳条件下有91%的聚戊糖可以以单体、低聚体及其降解产物的形式从杨木纤维中分离出来,同时超过93%的聚己糖可以以固体的形式保留在纤维中。研究表明,在适宜的稀酸催化条件下杂交杨木纤维中的碳水化合物可以得到很好的分离,为下一步戊糖和聚己糖的分别单独转化打下了基础,不仅可以充分利用木材生物质资源,而且为反应提供了相对均一的条件,从而提高反应选择性和产物的纯度。

  18. Kinetic Study of Esterification of Lactic Acid with Isobutanol and n-Butanol Catalyzed by Ion-exchange Resins%离子交换树脂催化乳酸与异丁醇及正丁醇酯化反应的动力学研究

    Institute of Scientific and Technical Information of China (English)

    屈一新; 彭少君; 王水; 张志强; 王际东

    2009-01-01

    The esterification reactions of lactic acid with isobutanol and n-butanol have been studied in the presence of acid ion-exchange resin Weblyst D009. The influences of catalyst loading, stirrer speed, catalyst particle size, initial reactant molar ratio and temperature on the reaction rate have been examined. Experimental kinetic data were correlated by using the Pseudo-homogeneous, Langmuir-Hinshelwood and Eley-Rideal models. Nonideality of the liquid phase was taken into account by using activities instead of molar fractions. The activity coefficients were calculated according to the group contribution method UNIFAC. Provided that the nonideality of the liquid is taken into account, the esterification kinetics of lactic acid with isobutanol and n-butanol catalyzed by the acid ion-exchange resin can be described using all three models with reasonable errors.

  19. Chiral Diamine-catalyzed Asymmetric Aldol Reaction

    Institute of Scientific and Technical Information of China (English)

    LI Hui; XU Da-zhen; WU Lu-lu; WANG Yong-mei

    2012-01-01

    A highly efficient catalytic system composed of a simple and commercially available chiral primary diamine (1R,2R)-cyclohexane-1,2-diamine(6) and trifluoroacetic acid(TFA) was employed for asymmetric Aldol reaction in i-PrOH at room temperature.A loading of 10%(molar fraction) catalyst 6 with TFA as a cocatalyst could catalyze the Aldol reactions of various ketones or aldehydes with a series of aromatic aldehydes,furnishing Aldol products in moderate to high yields(up to >99%) with enantioselectivities of up to >99% and diastereoselectivities of up to 99:1.

  20. Ruthenium-catalyzed C–H activation of thioxanthones

    OpenAIRE

    Danny Wagner; Stefan Bräse

    2015-01-01

    Thioxanthones – being readily available in one step from thiosalicylic acid and arenes – were used in ruthenium-catalyzed C–H-activation reaction to produce 1-mono- or 1,8-disubstituted thioxanthones in good to excellent yields. Scope and limitation of this reaction are presented.

  1. Ruthenium-catalyzed C–H activation of thioxanthones

    Science.gov (United States)

    Wagner, Danny

    2015-01-01

    Summary Thioxanthones – being readily available in one step from thiosalicylic acid and arenes – were used in ruthenium-catalyzed C–H-activation reaction to produce 1-mono- or 1,8-disubstituted thioxanthones in good to excellent yields. Scope and limitation of this reaction are presented. PMID:25977717

  2. CU(II): catalyzed hydrazine reduction of ferric nitrate

    International Nuclear Information System (INIS)

    A method is described for producing ferrous nitrate solutions by the cupric ion-catalyzed reduction of ferric nitrate with hydrazine. The reaction is complete in about 1.5 hours at 400C. Hydrazoic acid is also produced in substantial quantities as a reaction byproduct

  3. Synthesis of DOTA-conjugated multimeric [Tyr3]octreotide peptides via a combination of Cu(I)-catalyzed "click" cycloaddition and thio acid/sulfonyl azide "sulfo-click" amidation and their in vivo evaluation.

    NARCIS (Netherlands)

    Yim, C.B.; Dijkgraaf, I.; Merkx, R.; Versluis, C.; Eek, A.; Mulder, G.E.; Rijkers, D.T.; Boerman, O.C.; Liskamp, R.M.

    2010-01-01

    Herein, we describe the design, synthesis, and biological evaluation of a series of DOTA-conjugated monomeric, dimeric, and tetrameric [Tyr(3)]octreotide-based analogues as a tool for tumor imaging and/or radionuclide therapy. These compounds were synthesized using a Cu(I)-catalyzed 1,3-dipolar cycl

  4. Lipase-catalyzed synthesis of monoacylglycerol in a homogeneous system.

    Science.gov (United States)

    Monteiro, Julieta B; Nascimento, Maria G; Ninow, Jorge L

    2003-04-01

    The 1,3-regiospecifique lipase, Lipozyme IM, catalyzed the esterification of lauric acid and glycerol in a homogeneous system. To overcome the drawback of the insolubility of glycerol in hexane, which is extensively used in enzymatic synthesis, a mixture of n-hexane/tert-butanol (1:1, v/v) was used leading to a monophasic system. The conversion of lauric acid into monolaurin was 65% in 8 h, when a molar ratio of glycerol to fatty acid (5:1) was used with the fatty acid at 0.1 M, and the phenomenon of acyl migration was minimized.

  5. Gas Chromatographic Analysis of Medium Chain Fatty Acids in Coconut Oil

    Directory of Open Access Journals (Sweden)

    Julius Pontoh

    2016-09-01

    Full Text Available Analysis of medium chain of fatty acids in coconut oil becomes important due to their roles in health issues. The present analysis methods for fatty acids present in food mainly focused to the overall fatty acid concentration. The analytical method for specific medium chain fatty acids is not so much be given attention. This research is focused to the analytical methods for these particular fatty acids in coconut oil. Several analytical methods were compared including acid catalyzed, basic catalyzed and acid boron trifluoride catalyzed derivatization. The response of each fatty acid toward the derivatization methods are different. Formation of the fatty acid methyl ester from caprylic and capric was low for acid catalyzed method compared to basic catalyzed method and acid boron trifluoride catalyzed methods. This finding shows that the kinetics of the esterification among the fatty acids are not the same. The analysis of all fatty acids in coconut oil is better using basic catalyzed than the other methods.

  6. 生物炭催化过硫酸盐脱色偶氮染料金橙Ⅱ%Biochar Catalyzed Persulfate Decoloration of Azo Dye Acid Orange 7

    Institute of Scientific and Technical Information of China (English)

    刘娜; 王柳; 邱华; Alberto Bento Charru; 王航; 王锐

    2014-01-01

    As a kind of inexpensive material-biochar,the function of soil restoration and other aspects has caused wide public concern,but its catalytic role has been studied rarely.The feasibility of persulfate (PS)catalyzed by biochar(BC)to decolor an azo dye (acid orange (AO7))was studied.Some factors influencing the decolorizing efficiency of PS/BC system were evaluated, including pH, concentration of biochar and PS/AO7 mole ratio.What’s more,the recycle effect and characteristics of biochar were studied.Results showed that the decolorizing effect of the PS/BC system was obviously better than the only PS system.The decoloration of AO7 by both reaction systems followed first order reaction kinetics. The optimum pH of PS/BC system was near-neutral. The higher the biochar concentration,the better the decolorizing effect was.Similar trend was observed for the PS/AO7 mole ratio,whereas the catalytic effect did not increase accordingly.The reused biochar could still decolor %生物炭作为一种廉价易得的材料,在土壤修复等各方面的功能已引起广泛关注,但其催化作用却鲜有研究。首次对生物炭(biochar BC)催化过硫酸盐(Na2 S2 O8 PS)使偶氮染料金橙Ⅱ(AO7)脱色的可行性进行研究,对影响催化体系脱色效率的因素(包括 pH、生物炭质量浓度和 PS/AO7摩尔比)进行探讨,同时研究了生物炭的重复利用效果及前后性质变化。结果表明:PS/BC 体系明显比单独的 PS 体系脱色效果好;两个反应体系都遵循一级反应动力学;PS/BC 体系反应的最适 pH 接近中性;生物炭质量浓度越大,脱色效果越好;PS/AO7摩尔比越大,脱色效果越好,但是催化效果却没有相应的改善;生物炭重复利用后对 AO7仍然有脱色效果;BC 的孔大多位于层状结构表面,且为小孔,重复使用后,表面孔会堵塞;除了灰分和氧元素外,其他元素(C、N、H、S)含量都有一定程度的减小;BC 表面官能团种类很多,主要

  7. Catalyzed Oxidation of Methanol on Acid/Base Modified VOx/Al2O3 Studied by Solid-state NMR%改性VOx/Al2O3催化剂催化氧化甲醇的固体核磁共振研究

    Institute of Scientific and Technical Information of China (English)

    曾丹林; 杨俊; 郑安民; 陈雷; 徐君; 叶朝辉; 邓风

    2007-01-01

    采用固体核磁共振研究了NaOH和HNO3改性的VOx/Al2O3上甲醇选择性催化氧化反应.实验结果表明:在甲醇的氧化反应中,酸位对二甲氧基甲烷的生成起了重要作用.与VOx/Al2O3催化剂相比,酸改性的VOx/Al2O3上的强的Bronsted酸位对二甲氧基甲烷的选择性较高,没有Bronsted酸位的碱改性的VOx/Al2O3上生成的不是二甲氧基甲烷而是甲酸盐.%Oxidation of methanol catalyzed by NaOH or HNO3 modified VOx/Al2O3 was studied by solid-state nuclear magnetic resonance (NMR) spectroscopy. The acid-treated VOx/Al2O3 catalyst showed stronger Bronsted acid sites compared to the unmodified VOx/Al2O3 catalyst, while the base-treated VOx/Al2O3 catalyst had no Bronsted acid sites. As a result, the former exhibited higher selectivity in producing dimethoxymethane from oxidation of methanol whereas the oxidation reaction catalyzed by the later yielded mainly formate. These results indicate that the Bronsted acid sites in VOx/Al2O3 catalysts play a key role in the oxidation reaction converting methanol to dimethoxymethane.

  8. One-pot green synthesis of 1,3,5-triarylpentane-1,5-dione and triarylmethane derivatives as a new class of tyrosinase inhibitors.

    Science.gov (United States)

    Zheng, Zong-Ping; Zhang, Yi-Nan; Zhang, Shuang; Chen, Jie

    2016-02-01

    A new method was developed for one-pot green synthesis 1,3,5-triarylpentane-1,5-dione, triarylmethane, and flavonoid derivatives from the reaction between 2,4-dihydroxybenzaldehyde and hydroxyacetophenones via Aldol, Michael, and Friedel-Crafts additions using boric acid as catalyst in polyethylene glycol 400. The synthetic compounds demonstrated significant tyrosinase inhibitory activities much stronger than that of kojic acid. More important, 1,3,5-triarylpentane-1,5-dione and triarylmethane derivatives were found to be a new class of tyrosinase inhibitors.

  9. 碱/酸两步催化法制备耐候性SiO2增透膜的研究%Preparation and Characterization of Environment-Resistant Silica Antireflective Coating by Base/Acid Two-Step Catalyzed Sol-Gel Process

    Institute of Scientific and Technical Information of China (English)

    业海平; 张欣向; 肖波; 晏良宏; 江波

    2011-01-01

    Antireflective (AR) coatings with high transmittance and abrasion-resistance were prepared by a two-step base/acid catalyzed sol-gel process using tetraethylorthosilicate (TEOS) as precursor. It was found that addition of 50% acid-catalyzed SiO2 in the sol afforded the AR coatings relatively high transmittance and enhanced abrasion-resistance. It provided the AR coating with highest transmittance while the mole ratio of nH2O/nHCl was 1∶0.001 0. The water contact angle of base/acid two-step catalyzed AR coating was 11.3°, in this work,hexamethyldisiloxane (HMDS) was further used to modify the hydrophobicity of AR coatings. After HMDS treatment, the hydroxyl groups of AR coating were replaced by -OSi (CH3)3, which greatly increases the hydrophobicity of the coating, affording HMDS modified AR coating excellent environment resistance.%以正硅酸乙酯(TEOS)为先驱体,采用碱/酸两步催化溶胶-凝胶法制备出一种兼具碱催化增透膜的高透过率和酸催化增透膜的良好耐摩擦性能的优点的SiO2增透膜.对酸碱催化SiO2相对比例及酸催化时水含量的系统研究表明,当酸催化SiO2的含量为50%时,增透膜综合性能最好,即具有高透过率和高耐摩擦性;当nH2o/nHCI=1∶0.0010时,增透膜的透过率最高.碱/酸两步催化法制备的增透膜与水的接触角仅为11.3°,本文进一步用六甲基二硅氧烷(HMDS)对增透膜表面进行了修饰,修饰后增透膜的接触角提高至52.5°,增透膜的疏水性及环境稳定性得到较大的提高.

  10. 硫酸存在时N-溴代苯二甲酰亚胺对甘露糖的胶束催化氧化%Micelle Catalyzed Oxidation of Mannose by N-Bromophthalimide in the Presence of Sulfuric Acid

    Institute of Scientific and Technical Information of China (English)

    KATRE Yokraj; SINGH Minu; PATIL Sangeeta; SINGH Ajaya K

    2009-01-01

    The kinetics of micellar-catalyzed oxidation of mannose by N-bromophthalimide was studied in the presence of sulfuric acid at 313 K. The orders of reaction with respect to [mannose], [oxidant], and [H+] were found to be fractional, first, and negative fractional order, respectively. Anionic micelles of sodium dodecyl sulfate showed a partial inhibitory effect, while cationic micelles of cetyltrimethylammonium bromide increased the reaction rate with the same kinetic behavior. The reaction was catalyzed by cationic micelles, because of favorable electrostatic/thermodynamic/ hydrophobic/hydrogen bonding between reactants and cationic micelles. Their catalytic roles are best explained by Berezin's model. A variation of [phthalimide] showed that the rate of reaction decreased with increasing [phthalimide]. It was observed that, an increase of [mercuric acetate] had no effect on reaction velocity. The influence of salts on the reaction rate was also studied. The rate constant (kw), binding constants (Ks+Ko), and corresponding activation parameters (Ea, △H#, △S#, and △G#) were determined. A detailed mechanism with associated reaction kinetics is presented and discussed.

  11. Inhibitory Effect of Ferulic Acid on Oxidation of L-DOPA Catalyzed by Mushroom Tyrosinase%阿魏酸对蘑菇酪氨酸酶的抑制效应

    Institute of Scientific and Technical Information of China (English)

    龚盛昭; 程江; 杨卓如

    2005-01-01

    The inhibitory effect of ferulic acid on the diphenolase activity of mushroom tyrosinase and the kinetic behavior were studied with L-3,4-dihydroxyphenylalanine (L-DOPA) as substrate. The inhibitor concentration from Lineweaver-Burk plots shows that ferulic acid is a competitive inhibitor and the inhibition of tyrosinase by ferulic acid is a reversible reaction. The equilibrium constant for ferulic acid binding with the tyrosinase was determined to be 0.25 mmol· L-1 for diphenolase.

  12. Stereoselective Palladium Catalyzed Cyclizations of Enediyne Compounds

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Chang Ho; Rhim, Chul Yun; Jung, Hyung Hoon; Jung, Seung Hyun [Hanyang University, Seoul (Korea, Republic of)

    1999-06-15

    Hydropalladium carboxylates, formed from {pi}-allylpalladium chloride dimer plus carboxylic acids, have been shown to catalyze cyclization of structurally diverse enediynes to form the corresponding six- or five-membered rings depending upon the reaction conditions. Some enediynes having an oxygen linker in an appropriate position under the similar condition yielded the corresponding cyclopropanation products in highly stereoselective manner. A study using deuterated formic acid has proven that the alkylpalladium intermediates formed in our conditions were reduced by the pendant formate ligand. The dienediyne 10 yielded only the tricyclic product 12 in 67% yield, although it was expected to form the cyclic product 11. All these cyclizations seemed to occur via the corresponding alkylpalladium intermediates I, which could proceed to the corresponding cyclic products depending on the reaction conditions and the substrates. The study using deuterated formic acid could provide an important information to understand the present cyclization mechanism. Overall the present study could play an important role in developing new synthetic methodologies for constructing complex polycyclic compounds

  13. Olefin metathesis and side reactions with the binary systems of WCl/sub 6/ and metal alkyls. [Bu/sub 4/Sn, Et/sub 2/Zn, Et/sub 3/Al, BuLi co-catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Ichikawa, K.; Watanabe, O.; Takagi, T.; Fukuzumi, K.

    1976-09-01

    The comparison of the behaviors of the WCl/sub 6/-metal alkyl systems (metal alkyls are Bu/sub 4/Sn, Et/sub 2/Zn, Et/sub 3/Al, and BuLi) was carried out in the metathesis of 2-heptene in benzene. The WCl/sub 6/--Et/sub 2/Zn and the WCl/sub 6/--BuLi systems showed the sharp dependence of metathesis on the co-catalyst/WCl/sub 6/ ratio. The yield of the Friedel--Crafts products, heptylbenzenes, increased with a decrease in the co-catalyst/WCl/sub 6/ and the olefin/WCl/sub 6/ ratios, though the WCl/sub 6/--BuLi system barely catalyzed this side reaction. A proper amount of dicyclopentadiene, phenylacetylene, ethyl ether, ethanol, and esters repressed the Friedel--Crafts reaction, and the metathesis products were obtained in high yield and high selectivity in the metathesis of 2-heptene catalyzed by the WCl/sub 6/--Bu/sub 4/Sn system.

  14. 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

  15. Asymmetric Aldol Reaction Catalyzed by Modularly Designed Organocatalysts

    Institute of Scientific and Technical Information of China (English)

    Sinha, Debarshi; Mandal, Tanmay; Gogoi, Sanjib; Goldman, Joshua J.; 赵从贵

    2012-01-01

    The self-assembly of the precatalyst modules, which are amino acids and cinchona alkaloid derivatives, leads to the direct formation of the desired organocatalysts without any synthesis. These modularly designed organocatalysts (MDOs) may be used for catalyzed asymmetric aldol reaction the corresponding aldol products may be obtained in mediocre diastereoselectivities (up to 79 : 21 dr). Depending on structure of the aldehyde substrates, to excellent ee values (up to 92% ee) with moderate

  16. Modeling Lewis catalyzed reactions in Metal Organic Frameworks

    OpenAIRE

    Vandichel, Matthias; Cottenie, Stijn; Vermoortele, Frederik; De Vos, Dirk; Waroquier, Michel; Van Speybroeck, Veronique

    2011-01-01

    Recently, the spectrum of nanoporous materials like zeolites and zeotype structures has been further expanded through the discovery of a new class of hybrid porous solids [1]. Those materials, nowadays also known as metal organic frameworks or MOFs, consist of both inorganic and organic moieties. Certain MOFs exhibit a very interesting adsorption and even catalytic behavior [2]. Within this study, we will focus on the modeling of different Lewis acid catalyzed reactions in various MOFs: Cu co...

  17. Iodine-catalyzed coal liquefaction

    Energy Technology Data Exchange (ETDEWEB)

    Joseph, J.T.; Duffield, J.E.; Davidson, M.G. (Amoco Oil Company, Naperville, IL (USA). Research and Development Dept.)

    Coals of two different ranks were liquefied in high yields using catalytic quantities of elemental iodine or iodine compounds. Iodine monochloride was found to be especially effective for enhancing both coal conversion and product quality. It appears that enhancement in coal conversion is due to the unique ability of iodine to catalyze radical-induced bond scission and hydrogen addition to the coal macromolecule or coal-derived free radicals. The starting iodine can be fully accounted for in the reaction products as both organic-bound and water-soluble forms. Unconverted coal and the heavy product fractions contain the majority of the organic-bound iodine. The results of iodine-catalyzed coal reactions emphasize the need for efficient hydrogen atom transfer along with bond scission to achieve high conversion and product quality. 22 refs., 12 tabs.

  18. Asymmetric Stetter reactions catalyzed by thiamine diphosphate-dependent enzymes.

    Science.gov (United States)

    Kasparyan, Elena; Richter, Michael; Dresen, Carola; Walter, Lydia S; Fuchs, Georg; Leeper, Finian J; Wacker, Tobias; Andrade, Susana L A; Kolter, Geraldine; Pohl, Martina; Müller, Michael

    2014-12-01

    The intermolecular asymmetric Stetter reaction is an almost unexplored transformation for biocatalysts. Previously reported thiamine diphosphate (ThDP)-dependent PigD from Serratia marcescens is the first enzyme identified to catalyze the Stetter reaction of α,β-unsaturated ketones (Michael acceptor substrates) and α-keto acids. PigD is involved in the biosynthesis of the potent cytotoxic agent prodigiosin. Here, we describe the investigation of two new ThDP-dependent enzymes, SeAAS from Saccharopolyspora erythraea and HapD from Hahella chejuensis. Both show a high degree of homology to the amino acid sequence of PigD (39 and 51 %, respectively). The new enzymes were heterologously overproduced in Escherichia coli, and the yield of soluble protein was enhanced by co-expression of the chaperone genes groEL/ES. SeAAS and HapD catalyze intermolecular Stetter reactions in vitro with high enantioselectivity. The enzymes possess a characteristic substrate range with respect to Michael acceptor substrates. This provides support for a new type of ThDP-dependent enzymatic activity, which is abundant in various species and not restricted to prodigiosin biosynthesis in different strains. Moreover, PigD, SeAAS, and HapD are also able to catalyze asymmetric carbon-carbon bond formation reactions of aldehydes and α-keto acids, resulting in 2-hydroxy ketones.

  19. The mechanism of Fe (Ⅲ)-catalyzed ozonation of phenol

    Institute of Scientific and Technical Information of China (English)

    竹湘锋; 徐新华

    2004-01-01

    Fe (Ⅲ)-catalyzed ozonation yielded better degradation rate and extent of COD (Chemical Oxygen Demand) or oxalic acid as compared with oxidation by ozone alone. Two parameters with strong effects on the efficiency of ozonation are pH of the solution and the catalyst (Fe3+) dosage. The existence of a critical pH value determining the catalysis ofFe (Ⅲ) in acid conditions was observed in phenol and oxalic acid systems. The best efficiency of catalysis was obtained at a moderate concentration of the catalyst. A reasonable mechanism of Fe (Ⅲ)-catalyzed ozonation of phenol was obtained based on the results and literature.

  20. Diastereoselective Synthesis of 5-Heteroaryl-Substituted Prolines Useful for Controlling Peptide-Bond Geometry.

    Science.gov (United States)

    Ali, Rafat; Singh, Gajendra; Singh, Shalini; Ampapathi, Ravi Sankar; Haq, Wahajul

    2016-06-17

    A versatile diastereoselective Friedel-Crafts alkylation reaction of heteroaryl systems with a cyclic enecarbamate for the preparation of 5-heteroaryl-substituted proline analogues in good yields has been developed. These heterocyclic tethered cyclic amino acid building blocks constitute important structural motifs in many biologically active molecules. The impact of the substitution on proline cis/trans isomerization was explored by carrying out solution conformational studies by NMR on 5-furanyl-substituted proline-containing peptides. Conformational analysis revealed that the peptide bond is constrained in an exclusively trans conformation. PMID:27228427

  1. Synthesis of five- and six-membered 2-trimethylsilyl-1,3,3-trimethylcycloalkenes: A novel preparation of alkyl/alkenyl/aryl-(1′,3′,3′-trimethylcyclopentenylketones

    Directory of Open Access Journals (Sweden)

    Achanna Venkatesha M.

    2013-01-01

    Full Text Available 2-Trimethylsilyl-1,3,3-trimethylcyclopentene and 2-trimethylsilyl-1,3,3-trimethylcyclohexene were prepared in good yields by the Wurtz-Fittig coupling reaction of the corresponding 2-iodo-1,3,3-trimethylcyclopentene and 2-chloro-1,3,3-trimethylcyclohexene with metallic sodium and chlorotrimethylsilane in anhydrous ether solvent. The Friedel-Crafts acylation reaction of 2-trimethylsilyl-1,3,3-trimethylcyclopentene with six different acid chlorides and the novel preparation of six alkyl/alkenyl/aryl-(1′,3′,3′-trimethylcyclopentenylketones is reported.

  2. Practical Synthesis of Hydroxychromenes and Evaluation of Their Biological Activity

    Directory of Open Access Journals (Sweden)

    Jae-Chul Jung

    2011-12-01

    Full Text Available A simple and efficient seven steps synthesis of brodifacoum and difethialone from phenylacetyl chloride is described. The key synthetic strategies involve Friedel-Crafts acylation, intramolecular ring cyclization and condensation reaction in the presence of Brønsted-Lowry acids. It was found that brodifacoum showed favorable inhibiting activities on LPS-stimulated nitrite production in BV-2 microglia cells. Brodifacoum exhibited superior anti-inflammatory effects than difethialone. We expect that an efficient linear synthesis of 4-hydroxycoumarin derivatives and key fragments that are useful agents for the modulation of inflammation as well as inhibition of coagulation will be of practical use.

  3. Synthesis and antiinflammatory activity of 6-Acylsubstituted benzo-1,4-dioxanes and dihydrobenzopyrans

    Energy Technology Data Exchange (ETDEWEB)

    Daukshas, V.K.; Brukshtus, A.B.; Gaidyalis, P.G.; Pyatrauskas, O.Yu.; Udrenaite, E.B.

    1986-07-01

    6-Acylsubstituted benzo-1,4-dioxanes and dihydrobenzopyrans were synthesized by the Friedel-Crafts reaction by the acylation of benzo-1,4-dioxane or corresponding dihydrobenzopyran with an acid chloride in the presence of anhydrous AlCl/sub 3/; the ketone was obtained by the hydrogenation of the chalcone using Raney nickel. The antiinflammatory activity was studied on experimental models of carragheen and bentonite edema of the foot of white rats. Results indicate that derivatives of benzo-1,4-dioxane and dihydrobenzopyran of the type studied show promise as antiinflammatory agents.

  4. Modification of diphenylamine-linked bis(oxazoline)ligands:Tuning of electronic effect and rigidity of ligand skeleton

    Institute of Scientific and Technical Information of China (English)

    LIU Han; LI Wei; DU DaMing

    2009-01-01

    The electronic effect of diphenylamine-linked bis(oxazoline) ligands was tuned through introduction of electron-withdrawing bromo and nitro substituents onto the 4 and 4' position.The variation of the NH bond acidity was determined by the different chemical shifts of NH.The catalytic activity and enantioselectivity of the modified ligands were tested in the asymmetric FriedeI-Crafts alkylation of indole with β-nitrostyrene.The effect of iigand skeleton rigidity was also investigated through the synthesis of iminodibenzyl-linked bis(oxazoline) ligands and evaluation of their catalytic activity in Friedel-Crafts alkylation.

  5. Efficient synthesis of spironaphthopyrano [2,3-d]pyrimidine-5,3'-indolines under solvent-free conditions catalyzed by SBA-Pr-SO3H as a nanoporous acid catalyst.

    Science.gov (United States)

    Ziarani, Ghodsi Mohammadi; Lashgari, Negar; Faramarzi, Sakineh; Badiei, Alireza

    2014-01-01

    A green, simple one-pot synthesis of spironaphthopyrano[2,3-d]pyrimidine-5,3'-indoline derivatives by a three-component reaction of isatins, 2-naphthol, and barbituric acids under solvent-free conditions in the presence of SBA-Pr-SO(3)H has been accomplished. Sulfonic acid functionalized SBA-15 (SBA-Pr-SO(3)H) as a heterogeneous nanoporous solid acid catalyst was found to be an efficient and recyclable acid catalyst in this synthesis. PMID:25286212

  6. An efficient synthesis of isocoumarins via a CuI catalyzed cascade reaction process

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    3-Alkyl isocoumarins are provided by CuI/amino acid-catalyzed Sonogashira coupling reaction of o-bromo benzoic acids and terminal alkynes and the subsequent additive cyclization. This cascade process allows synthesis of diverse isocoumarins by varying both coupling partners bearing a wide range of functional groups.

  7. The concise synthesis of chiral tfb ligands and their application to the rhodium-catalyzed asymmetric arylation of aldehydes

    OpenAIRE

    Nishimura, Takahiro; Kumamoto, Hana; Nagaosa, Makoto; Hayashi, Tamio

    2009-01-01

    New C2-symmetric tetrafluorobenzobarrelene ligands were prepared and applied successfully to the rhodium-catalyzed asymmetric addition of arylboronic acids to aromatic aldehydes giving chiral diarylmethanols in high yield with high enantioselectivity.

  8. Discussion on Synthesis and Reaction Mechanism of Chalcone Catalyzed by Acidic Ionic Liquids[BPy]HSO4 and[BMMIm]HSO4%酸性离子液体[BPy]HSO4和[BMMIm]HSO4催化合成查尔酮反应机理探讨

    Institute of Scientific and Technical Information of China (English)

    杜玉英; 韩利民; 李永栋; 竺宁; 张桂峰

    2012-01-01

    离子液体作为绿色的溶剂和催化剂具有很多独特的性质,特别是离子液体的可设计性,使其具有酸性可调的特点.分别以酸性离子液体[BPy] HSO4和[BMMIm] HSO4为催化剂,在无溶剂条件下考察了两种离子液体对Claisen-Schmidt缩合的不同催化效果,探讨了两种离子液体在查尔酮合成中可能的催化机理.%Ionic liquids (ILs) as green solvents and catalysts have unique properties such as a broad liquid range,good solvating ability,high thermal stability,and negligible vapor pressure,especially designability of ILs, which makes the acidity of ILs can be adjustable. [BPy]HSO4 and[BM-MIm]HSO4 acidic ILs catalyzing Claisen-Schmidt (CS) condensation of acetophenone with benzal-dehyde were investigated under solvent-free conditions. The plausible mechanism was elucidated for the synthesis of chalcone using the two ILs as Br0nsted acid catalysts.

  9. Fatty acid biosynthesis in actinomycetes

    OpenAIRE

    Gago, Gabriela; Diacovich, Lautaro; Arabolaza, Ana; Tsai, Shiou-Chuan; Gramajo, Hugo

    2011-01-01

    All organisms that produce fatty acids do so via a repeated cycle of reactions. In mammals and other animals, these reactions are catalyzed by a type I fatty acid synthase (FAS), a large multifunctional protein to which the growing chain is covalently attached. In contrast, most bacteria (and plants) contain a type II system in which each reaction is catalyzed by a discrete protein. The pathway of fatty acid biosynthesis in Escherichia coli is well established and has provided a foundation fo...

  10. The effects of zeolite and silica gel on synthesis of amylisobutyrate catalyzed by lipase from Candida rugosa

    OpenAIRE

    Stojaković Sanja B.; Bezbradica Dejan I.; Mijin Dušan Ž.; Knežević Zorica D.; Šiler-Marinković Slavica S.

    2008-01-01

    Lipase-catalyzed synthesis of esters has been widely investigated due to numerous advantages in comparison with the conventional chemical process catalyzed with concentrated acids since use of chemical catalysts leads to several problems. The most important disadvantages are corrosion of equipment, hazards of handling of the corrosive acids that are not reused, loss of conversion, yield and selectivity. The activity of water in reaction mixture seems to be one of the crucial factors affecting...

  11. A SABATH Methyltransferase from the moss Physcomitrella patens catalyzes

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Nan [ORNL; Ferrer, Jean-Luc [Universite Joseph Fourier, France; Moon, Hong S [Department of Plant Sciences, University of Tennessee; Kapteyn, Jeremy [Institute of Biological Chemistry, Washington State University; Zhuang, Xiaofeng [Department of Plant Sciences, University of Tennessee; Hasebe, Mitsuyasu [Laboratory of Evolutionary Biology, National Institute for Biology, 38 Nishigounaka; Stewart, Neal C. [Department of Plant Sciences, University of Tennessee; Gang, David R. [Institute of Biological Chemistry, Washington State University; Chen, Feng [University of Tennessee, Knoxville (UTK)

    2012-01-01

    Known SABATH methyltransferases, all of which were identified from seed plants, catalyze methylation of either the carboxyl group of a variety of low molecular weight metabolites or the nitrogen moiety of precursors of caffeine. In this study, the SABATH family from the bryophyte Physcomitrella patens was identified and characterized. Four SABATH-like sequences (PpSABATH1, PpSABATH2, PpSABATH3, and PpSABATH4) were identified from the P. patens genome. Only PpSABATH1 and PpSABATH2 showed expression in the leafy gametophyte of P. patens. Full-length cDNAs of PpSABATH1 and PpSABATH2 were cloned and expressed in soluble form in Escherichia coli. Recombinant PpSABATH1 and PpSABATH2 were tested for methyltransferase activity with a total of 75 compounds. While showing no activity with carboxylic acids or nitrogen-containing compounds, PpSABATH1 displayed methyltransferase activity with a number of thiols. PpSABATH2 did not show activity with any of the compounds tested. Among the thiols analyzed, PpSABATH1 showed the highest level of activity with thiobenzoic acid with an apparent Km value of 95.5 lM, which is comparable to those of known SABATHs. Using thiobenzoic acid as substrate, GC MS analysis indicated that the methylation catalyzed by PpSABATH1 is on the sulfur atom. The mechanism for S-methylation of thiols catalyzed by PpSABATH1 was partially revealed by homology-based structural modeling. The expression of PpSABATH1 was induced by the treatment of thiobenzoic acid. Further transgenic studies showed that tobacco plants overexpressing PpSABATH1 exhibited enhanced tolerance to thiobenzoic acid, suggesting that PpSABATH1 have a role in the detoxification of xenobiotic thiols.

  12. 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.

  13. Stau-catalyzed Nuclear Fusion

    OpenAIRE

    Hamaguchi, K.; Hatsuda, T.(Theoretical Research Division, Nishina Center, RIKEN, Saitama, 351-0198, Japan); Yanagida, T. T.

    2006-01-01

    We point out that the stau may play a role of a catalyst for nuclear fusions if the stau is a long-lived particle as in the scenario of gravitino dark matter. In this letter, we consider d d fusion under the influence of stau where the fusion is enhanced because of a short distance between the two deuterons. We find that one chain of the d d fusion may release an energy of O(10) GeV per stau. We discuss problems of making the stau-catalyzed nuclear fusion of practical use with the present tec...

  14. Gold-catalyzed naphthalene functionalization

    OpenAIRE

    Iván Rivilla; M. Mar Díaz-Requejo; Pedro J. Pérez

    2011-01-01

    The complexes IPrMCl (IPr = 1,3-bis(diisopropylphenyl)imidazol-2-ylidene, M = Cu, 1a; M = Au, 1b), in the presence of one equiv of NaBAr'4 (Ar' = 3,5-bis(trifluoromethyl)phenyl), catalyze the transfer of carbene groups: C(R)CO2Et (R = H, Me) from N2C(R)CO2Et to afford products that depend on the nature of the metal center. The copper-based catalyst yields exclusively a cycloheptatriene derivative from the Buchner reaction, whereas the gold analog affords a mixture of products derived either f...

  15. Stereoselectivity in (Acyloxy)borane-Catalyzed Mukaiyama Aldol Reactions.

    Science.gov (United States)

    Lee, Joshua M; Zhang, Xin; Norrby, Per-Ola; Helquist, Paul; Wiest, Olaf

    2016-07-01

    The origin of diastereo- and enantioselectivity in a Lewis acid-catalyzed Mukaiyama aldol reaction is investigated using a combination of dispersion corrected DFT calculations and transition state force fields (TSFF) developed using the quantum guided molecular mechanics (Q2MM) method. The reaction proceeds via a closed transition structure involving a nontraditional hydrogen bond that is 3.3 kJ/mol lower in energy than the corresponding open transition structure. The correct prediction of the diastereoselectivity of a Mukaiyama aldol reaction catalyzed by the conformationally flexible Yamamoto chiral (acyloxy) borane (CAB) requires extensive conformational sampling at the transition structure, which is achieved using a Q2MM-derived TSFF, followed by DFT calculations of the low energy conformational clusters. Finally, a conceptual model for the rationalization of the observed diastereo- and enantioselectivity of the reaction using a closed transition state model is proposed. PMID:27247023

  16. Mechanism of Intramolecular Rhodium- and Palladium-Catalyzed Alkene Alkoxyfunctionalizations

    KAUST Repository

    Vummaleti, Sai V. C.

    2015-11-13

    Density functional theory calculations have been used to investigate the reaction mechanism for the [Rh]-catalyzed intramolecular alkoxyacylation ([Rh] = [RhI(dppp)+] (dppp, 1,3-bis(diphenylphosphino)propane) and [Pd]/BPh3 dual catalytic system assisted intramolecular alkoxycyanation ([Pd] = Pd-Xantphos) using acylated and cyanated 2-allylphenol derivatives as substrates, respectively. Our results substantially confirm the proposed mechanism for both [Rh]- and [Pd]/ BPh3-mediated alkoxyfunctionalizations, offering a detailed geometrical and energetical understanding of all the elementary steps. Furthermore, for the [Rh]-mediated alkoxyacylation, our observations support the hypothesis that the quinoline group of the substrate is crucial to stabilize the acyl metal complex and prevent further decarbonylation. For [Pd]/BPh3-catalyzed alkoxycyanation, our findings clarify how the Lewis acid BPh3 cocatalyst accelerates the only slow step of the reaction, corresponding to the oxidative addition of the cyanate O-CN bond to the Pd center. © 2015 American Chemical Society.

  17. Research progress of lipase-catalyzed synthesis of L-ascorbyl organic acid ester%脂肪酶催化合成L-抗坏血酸有机酸酯的研究进展

    Institute of Scientific and Technical Information of China (English)

    蒋相军; 胡燚; 刘维明; 黄和

    2011-01-01

    To broaden the applications of L-ascorbic acid, it is an economical and feasible way to convert L-aseorbic acid into L-ascorbyl organic acid ester. The recent research progress of enzymatic synthesis of L-ascorbyl organic acid ester is summarized, by focusing on enzymatic synthesis of L-ascorbyl saturated fatty acid ester, unsaturated fatty acid ester and mixed fatty acid ester in organic solvents. The types of lipase, organic solvents and methods of separation and purification in the synthesis are discussed. Furthermore, the prospect of enzymatic synthesis of L-ascorbyl organic acid ester is also presented.%为了拓宽L-抗坏血酸酯在维护人体健康中的应用,将L-抗坏血酸转化成L-抗坏血酸酯是经济可行的手段。综述了近年来酶催化L-抗坏血酸有机酸酯的研究进展,重点介绍了有机相中L-抗坏血酸饱和脂肪酸酯、不饱和脂肪酸酯、脂肪酸混合酯的酶促合成,对于酶的种类、有机溶剂的选择及分离纯化方法进行了探讨,并对酶催化L-抗坏血酸有机酸酯合成前景进行了展望。

  18. Regiospecific O-Methylation of Naphthoic Acids Catalyzed by NcsB1, an O-Methyltransferase Involved in the Biosynthesis of the Enediyne Antitumor Antibiotic Neocarzinostatin*S⃞

    OpenAIRE

    Luo, Yinggang; Lin, Shuangjun; Zhang, Jian; Cooke, Heather A.; Bruner, Steven D.; Shen, Ben

    2008-01-01

    Neocarzinostatin, a clinical anticancer drug, is the archetypal member of the chromoprotein family of enediyne antitumor antibiotics that are composed of a nonprotein chromophore and an apoprotein. The neocarzinostatin chromophore consists of a nine-membered enediyne core, a deoxyaminosugar, and a naphthoic acid moiety. We have previously cloned and sequenced the neocarzinostatin biosynthetic gene cluster and proposed that the biosynthesis of the naphthoic acid moiety and its incorporation in...

  19. PHOSPHORUS PENTOXIDE-METHANESULFONIC ACID CATALYZED EFFICIENT SYNTHESIS OF 5-SUBSTITUTED 1H-TETRAZOLE DERIVATIVES Phosphorpentoxid-Methansulfonsäure KATALYSIERTEN EFFICIENT Synthese von 5-substituierten 1H-Tetrazolderivate

    Directory of Open Access Journals (Sweden)

    Amulrao U. Borse,Mahesh N. Patil, Nilesh L. Patil, and Sandesh R. Tetgure

    2012-07-01

    Full Text Available The mixture of phosphorus pentoxide-methanesulfonic acid (Eaton’s reagent is prove to be an efficient protocol for the [3+2] cycloaddition reaction between sodium azide and organic nitriles to give the corresponding 5-substituted 1H-tetrazole derivatives in good to excellent yields. The in situ formation of hydrazoic acid helps for the [3+2] cycloaddition reaction providing 5- substituted 1H-tetrazole with short reaction time.

  20. 漆酶催化4-香豆酸与聚木糖接枝改善其强度性能的研究∗%4-coumaric acid grafted onto xylan catalyzed by laccase for improving its strength properties

    Institute of Scientific and Technical Information of China (English)

    裴继诚; 王兵; 张方东; 李中阳; 殷允北

    2015-01-01

    利用漆酶催化,使4-香豆酸与聚木糖发生接枝共聚反应,从而改善聚木糖的成膜性能.通过红外光谱(FT-IR)、核磁共振碳谱(13 C NMR)、裂解-气相色谱/质谱(Py-GC/MS)联用等分析,表明接枝反应后聚木糖与4-香豆酸之间产生化学键连接,发生了接枝共聚反应;通过聚合度测试,接枝后聚木糖的聚合度提高了17.78%;薄膜拉伸性能的测试结果得出,接枝反应后聚木糖薄膜的杨氏模量提高了25.29%,拉伸强度提高了19.41%.聚木糖与4-香豆酸之间的接枝作用在增强薄膜性能中发挥了重要的作用,接枝后聚木糖制得的薄膜具有良好强度性能.%The reaction of graft copolymerization of xylan with 4-coumaric acid by laccase-catalyzed oxidation,in a way to improve quality of filming of xylan.It was analyzed by infrared FT-IR analysis,13 C NMR analysis,Py-GC/MS analysis techniques for determining the reaction between xylan and 4-coumaric acid which were chemi-cally connected,and occurred copolymer.By testing the degree of polymerization,results showed that the de-gree of polymerization of the xylan improved 17.78%;and the films showed a significant increase in Young's modulus by 25.29%,tensile strength increased from 0.601 to 0.753 MPa and 1.020 to 1.218 MPa,respectively. The grafting between xylan and laccase-catalyzed oxidation of 4-coumaric acid played an important role in rein-forcing the films.The superior properties of the new films could have great potential applications.

  1. Synthesis of n-butyl p-hydroxyl benzoate catalyzed by dawson structure phosphotungstic acid%Dawso结构磷钨酸催化合成对羟基苯甲酸正丁酯

    Institute of Scientific and Technical Information of China (English)

    曹小华; 张杨帆; 徐常龙; 叶兴琳; 周德志

    2015-01-01

    Preparation of n-butyl p-hydroxybenzoate by the esterification of p-hydroxy benzoic acid and n-butanol using dawson structure phosphotungstic acid as catalyst was reported. The catalyst was characterized by Py-IR and NH3-TPD. The main influential factors of reaction were investigated by orthogonal experiments and the possible reaction mechanism was discussed. Py-IR results showed that both Bronsted(B)acid sites and Lewis(L)acid sites co-exist on the surface of the catalyst. The results of NH3-TPD suggested that the catalyst possessed weak,medium and strong acid sites,among which the medium acid sites accounted for the lar-gest proportion. The results obtained indicated that the esterification reaction was a Brö nsted acid-Lewis acid cooperativity catalytic reaction. Dawson structure phosphotungstic acid possessed a fairly high catalytic activity for the esterification reaction. The optimal condition could be listed as follows:the best reaction temperature was 125℃,the reaction time was 3. 0 h,the mass ratio of the cata-lyst to total reactants was 4. 9%,and the molar ratio of n-butyl alcohol to p-hydroxyl benzoic acid was 2∶1. Under these conditions, the yield of butyl p-hydroxyl benzoate could reach 91. 3%, and it was still over 70. 3%when the catalyst was reused for five times. The primary advantage of replacement of sulphuric acid to dawson structure phosphotungstic acid might be not only as the im-provement of yield and selectivity,but also the simplification of the process and the reduction of environmental pollution. The cata-lyst could be used repeatedly after being treated simply.%以对羟基苯甲酸和正丁醇为原料、Dawson结构磷钨酸( H6 P2 W18 O62·13H2 O)为催化剂,催化对合成对羟基苯甲酸正丁酯,并对催化剂进行Py-IR、NH3-TPD表征。通过正交实验考察了各因素对酯收率的影响,探索了反应机理。 Py-IR结果显示催化剂同时具有Brönsted酸中心和Lewis酸中心,NH3-TPD证实催化剂表面

  2. Unprecedentedly mild direct Pd-catalyzed arylation of oxazolo[4,5-b]pyridine

    DEFF Research Database (Denmark)

    Zhuravlev, Fedor

    2006-01-01

    Pd-catalyzed C-2 arylation of oxazolo[4,5-b]pyridine proceeds efficiently at 30 degrees C and tolerates a variety of aryl halides, including derivatized amino acids for which no racemization was observed during the reaction. Experimental evidence for facile deprotonation of oxazolo[4,5-b]pyridine......Pd-catalyzed C-2 arylation of oxazolo[4,5-b]pyridine proceeds efficiently at 30 degrees C and tolerates a variety of aryl halides, including derivatized amino acids for which no racemization was observed during the reaction. Experimental evidence for facile deprotonation of oxazolo[4,5-b...

  3. Gold-catalyzed formation of pyrrolo- and indolo-oxazin-1-one derivatives: The key structure of some marine natural products

    OpenAIRE

    Sultan Taskaya; Nurettin Menges; Metin Balci

    2015-01-01

    Various N-propargylpyrrole and indolecarboxylic acids were efficiently converted into 3,4-dihydropyrrolo- and indolo-oxazin-1-one derivatives by a gold(III)-catalyzed cyclization reaction. Some of the products underwent TFA-catalyzed double bond isomerization and some did not. Cyclization reactions in the presence of alcohol catalyzed by Au(I) resulted in the formation of hemiacetals after cascade reactions.

  4. Gold-catalyzed formation of pyrrolo- and indolo-oxazin-1-one derivatives: The key structure of some marine natural products

    Directory of Open Access Journals (Sweden)

    Sultan Taskaya

    2015-05-01

    Full Text Available Various N-propargylpyrrole and indolecarboxylic acids were efficiently converted into 3,4-dihydropyrrolo- and indolo-oxazin-1-one derivatives by a gold(III-catalyzed cyclization reaction. Some of the products underwent TFA-catalyzed double bond isomerization and some did not. Cyclization reactions in the presence of alcohol catalyzed by Au(I resulted in the formation of hemiacetals after cascade reactions.

  5. AN EFFICIENT SYNTHESIS OF 1,3-DIOXANE-4,6-DIONES CATALYZED BY BORIC ACID. Eine effiziente Synthese von 1,3-Dioxan-4 ,6-dione BY BORSÄURE katalysierten

    Directory of Open Access Journals (Sweden)

    Zhao hui XU*,Chun hua Lin ,Jian hui Xia

    2013-07-01

    Full Text Available Several kinds of 1,3-dioxane-4,6-diones have been synthesized from malonic acid and ketones using boric acid as catalyst, acetic anhydride as condensing regent at room temperature. The present method does not involve any hazardous organic solvents, it gives some notable advantages such as mild reaction conditions, short reaction time,less catalyst dosage and high yields.Further study showed that H3BO3 was reused for four times without any noticeable decrease in the catalytic activity.

  6. Can laccases catalyze bond cleavage in lignin?

    DEFF Research Database (Denmark)

    Munk, Line; Sitarz, Anna Katarzyna; Kalyani, Dayanand;

    2015-01-01

    illustrations of the putative laccase catalyzed reactions, including the possible reactions of the reactive radical intermediates taking place after the initial oxidation of the phenol-hydroxyl groups, we show that i) Laccase activity is able to catalyze bond cleavage in low molecular weight phenolic lignin...

  7. Cp2TiCl2-Catalyzed Regioselective Hydrocarboxylation of Alkenes with CO2.

    Science.gov (United States)

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

    2016-05-01

    Cp2TiCl2-catalyzed regioselective hydrocarboxylation of alkenes with CO2 to give carboxylic acids in high yields has been developed in the presence of (i)PrMgCl. The reaction proceeds with a wide range of alkenes under mild conditions. Styrene and its derivatives can transform to α-aryl carboxylic acids, and aliphatic alkenes can transform to form alkanoic acids. PMID:27097225

  8. Microwave-assisted solvent-free synthesis of 14-aryl/alkyl-14H-dibenzo[a,j]xanthenes and tetrahydrobenzo[a]xanthen-11-ones catalyzed by nano silica phosphoric acid

    OpenAIRE

    Abdolhamid Bamoniri; Bi Bi Fatemeh Mirjalili; Sedigeh Nazemian

    2013-01-01

    Nano silica phosphoric acid (nano SPA) was applied as a catalyst for synthesis of 14-aryl/alkyl-14H-dibenzo[a,j]xanthenes and tetrahydrobenzo[a]xanthen-11-ones in microwave oven under solvent free conditions. High efficiency, easy availability and reusability are some advantages of this catalyst.

  9. 微波辐射硫酸氢钠催化合成对氨基苯甲酸苄酯%Synthesis of 4-aminobenzoic acid benzyl ester catalyzed by sodium bisulfate under microwave radiation

    Institute of Scientific and Technical Information of China (English)

    杨晓军; 李西安

    2011-01-01

    在微波辐射下,以一水合硫酸氢钠为催化剂,对氨基苯甲酸和苯甲醇为原料,合成对氨基苯甲酸苄酯.结果表明,当微波辐射功率为500W,0.05mol对氨基苯甲酸为基准,催化剂的用量为1.6 g,酸醇的摩尔比为1∶1.2,反应时间14 min时,醋化率达93.8%.%The 4-aminobcnzoic acid benzyl ester was synthesized under microwave radiacion from 4-aminobenzoic acid and benzyl alcohol using sodium bisulfate as catalyst. When the power of microwave radiation was 500 W, amount of catalyst was 1. 6 g, the molar ratio of acid to alcohol was 1∶ 1.2( using 0. 05 mol of 4-aminobenzoic acid ) and reaction time was 14 min, the yield reached 93. 8% .

  10. Gold-catalyzed naphthalene functionalization

    Directory of Open Access Journals (Sweden)

    Iván Rivilla

    2011-05-01

    Full Text Available The complexes IPrMCl (IPr = 1,3-bis(diisopropylphenylimidazol-2-ylidene, M = Cu, 1a; M = Au, 1b, in the presence of one equiv of NaBAr'4 (Ar' = 3,5-bis(trifluoromethylphenyl, catalyze the transfer of carbene groups: C(RCO2Et (R = H, Me from N2C(RCO2Et to afford products that depend on the nature of the metal center. The copper-based catalyst yields exclusively a cycloheptatriene derivative from the Buchner reaction, whereas the gold analog affords a mixture of products derived either from the formal insertion of the carbene unit into the aromatic C–H bond or from its addition to a double bond. In addition, no byproducts derived from carbene coupling were observed.

  11. Catalyzed electrolytic plutonium oxide dissolution

    International Nuclear Information System (INIS)

    Catalyzed electrolytic plutonium oxide dissolution (CEPOD) was first demonstrated at Pacific Northwest Laboratory (PNL) in early 1974 in work funded by the Exxon Corporation. The work, aimed at dissolution of Pu-containing residues remaining after the dissolution of spent mixed-oxide reactor fuels, was first publicly disclosed in 1981. The process dissolves PuO2 in an anolyte containing small (catalytic) amounts of elements that form kinetically fast, strongly oxidizing ions. These are continuously regenerated at the anode. Catalysts used, in their oxidized form, include Ag2+, Ce4+, Co3+, and AmO22+. This paper reviews the chemistry involved in CEPOD and the results of its application to the dissolution of the Pu content of a variety of PuO2-containing materials such as off-standard oxide, fuels dissolution residues, incinerator ash, contaminated soils, and other scraps or wastes. Results are presented for both laboratory-scale and plant-scale dissolves

  12. Synthesis of Free Amino Acid Esters Co-catalyzed by Ionic Liquid%离子液体协同催化合成游离氨基酸酯

    Institute of Scientific and Technical Information of China (English)

    尚岩; 贾俊英; 高海鹏; 裴蕾; 仲昭琪

    2011-01-01

    以L-氨基酸和醇为原料,酸性离子液体辅以少量强酸性阳离子交换树脂作催化剂,直接酯化合成了8种游离的L-氨基酸酯,并用1HNMR对产物进行了表征.通过L-苯丙氨酸正丁酯的合成对离子液体的活性进行了考察,结果表明,所选用的11种离子液体在反应过程中均起到了一定的催化作用和助溶作用.其中,[Hmim][HSO4]效果较好,在重复使用后,显示了较好的稳定性,是氨基酸酯化反应理想的催化剂和助溶剂.%Eight kinds of free L-amino acid esters including L-phenylalanine ethyl ester, L-phenylalanine n-butyl ester, L-phenylalanine i-butyl ester, L-tyrosine n-butyl ester, L-tyrosine i-butyl ester, L-tyrosine i-amyl ester, L-aspartic n-butyl diester and L-aspartic i-butyl diester were synthesized by direct esterification of L-amino acid and alcohol with acidic ionic liquid assisted by strong acidic cation resin as catalyst. The structures of free L-amino acid esters were characterized by 1HNMR.Optimal reaction conditions were obtained when synthesizing L-phenylalanine n-butyl ester. Among eleven kinds of the acidic ionic liquids used in this case, [Hmim] [ HSO4 ] indicated excellent activity and the catalyst is easily regenerated and reused. By this token, it exhibits its potential application as catalyst and co-solvent in the esterification of amino acid.

  13. Hydrogen evolution catalyzed by cobaloximes.

    Science.gov (United States)

    Dempsey, Jillian L; Brunschwig, Bruce S; Winkler, Jay R; Gray, Harry B

    2009-12-21

    Natural photosynthesis uses sunlight to drive the conversion of energy-poor molecules (H(2)O, CO(2)) to energy-rich ones (O(2), (CH(2)O)(n)). Scientists are working hard to develop efficient artificial photosynthetic systems toward the "Holy Grail" of solar-driven water splitting. High on the list of challenges is the discovery of molecules that efficiently catalyze the reduction of protons to H(2). In this Account, we report on one promising class of molecules: cobalt complexes with diglyoxime ligands (cobaloximes). Chemical, electrochemical, and photochemical methods all have been utilized to explore proton reduction catalysis by cobaloxime complexes. Reduction of a Co(II)-diglyoxime generates a Co(I) species that reacts with a proton source to produce a Co(III)-hydride. Then, in a homolytic pathway, two Co(III)-hydrides react in a bimolecular step to eliminate H(2). Alternatively, in a heterolytic pathway, protonation of the Co(III)-hydride produces H(2) and Co(III). A thermodynamic analysis of H(2) evolution pathways sheds new light on the barriers and driving forces of the elementary reaction steps involved in proton reduction by Co(I)-diglyoximes. In combination with experimental results, this analysis shows that the barriers to H(2) evolution along the heterolytic pathway are, in most cases, substantially greater than those of the homolytic route. In particular, a formidable barrier is associated with Co(III)-diglyoxime formation along the heterolytic pathway. Our investigations of cobaloxime-catalyzed H(2) evolution, coupled with the thermodynamic preference for a homolytic route, suggest that the rate-limiting step is associated with formation of the hydride. An efficient water splitting device may require the tethering of catalysts to an electrode surface in a fashion that does not inhibit association of Co(III)-hydrides. PMID:19928840

  14. Nitroreductase catalyzed biotransformation of CL-20.

    Science.gov (United States)

    Bhushan, Bharat; Halasz, Annamaria; Hawari, Jalal

    2004-09-10

    Previously, we reported that a salicylate 1-monooxygenase from Pseudomonas sp. ATCC 29352 biotransformed CL-20 (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaaza-isowurtzitane) (C(6)H(6)N(12)O(12)) and produced a key metabolite with mol. wt. 346 Da corresponding to an empirical formula of C(6)H(6)N(10)O(8) which spontaneously decomposed in aqueous medium to produce N(2)O, NH(4)(+), and HCOOH [Appl. Environ. Microbiol. (2004)]. In the present study, we found that nitroreductase from Escherichia coli catalyzed a one-electron transfer to CL-20 to form a radical anion (CL-20(-)) which upon initial N-denitration also produced metabolite C(6)H(6)N(10)O(8). The latter was tentatively identified as 1,4,5,8-tetranitro-1,3a,4,4a,5,7a,8,8a-octahydro-diimidazo[4,5-b:4',5'-e]pyrazine [IUPAC] which decomposed spontaneously in water to produce glyoxal (OHCCHO) and formic acid (HCOOH). The rates of CL-20 biotransformation under anaerobic and aerobic conditions were 3.4+/-0.2 and 0.25+/-0.01 nmol min(-1)mg of protein(-1), respectively. The product stoichiometry showed that each reacted CL-20 molecule produced about 1.8 nitrite ions, 3.3 molecules of nitrous oxide, 1.6 molecules of formic acid, 1.0 molecule of glyoxal, and 1.3 ammonium ions. Carbon and nitrogen products gave mass-balances of 60% and 81%, respectively. A comparative study between native-, deflavo-, and reconstituted-nitroreductase showed that FMN-site was possibly involved in the biotransformation of CL-20. PMID:15313201

  15. Reduction of nitrobenzene by the catalyzed Fe/Cu process

    Institute of Scientific and Technical Information of China (English)

    XU Wenying; LI Ping; FAN Jinhong

    2008-01-01

    The polarization behavior of the couple Fe/Cu in 100 mg/L nitrobenzene aqueous solution was studied using Evans coupling diagrams. The results indicated that the iron corrosion was limited by both anodic and cathodic half-cell reactions under the neutral conditions and cathodically controlled under the alkaline conditions. Batch experiments were performed to study the effect of solution pH, reaction duration, concentration, type of electrolyte and dissolved oxygen (DO) on the reduction of nitrobenzene by the catalyzed Fe/Cu process. This process proved effective in the pH range of 3 to 11. The conversion efficiency of nitrobenzene at pH ≈ 10.1 was almost the same as that under highly acid conditions (pH ≈ 3). The degradation of nitrobenzene fell into two phases: adsorption and surface reduction, and the influence of adsorption and mass transfer became more extensive with solution concentration. The reduction rate decreased in the presence of DO in the solution, indicating that a need for aeration was eliminated in the catalyzed Fe/Cu process. Accordingly, spending on energy consumption would be reduced. Economic analysis indicated that merely 0.05 kg was required for the treatment of a ton of nitrobenzene-containing water with pH from 3 to 11. The catalyzed Fe/Cu process is cost-effective and of practical value.

  16. Study on the synthesis of phenoxyacetic acid with the polyethylene glycol-600 by phase transfer catalyzed method%聚乙二醇-600相转移催化合成苯氧乙酸的研究

    Institute of Scientific and Technical Information of China (English)

    程冬梅; 王学明; 张铁军

    2011-01-01

    研究了用杉甲苯作反应介质,在相转移催化剂聚乙二醇-600的作用下,以苯酚、氯乙酸水溶液和氢氧化钠水溶液为原料合成苯氧乙酸的新工艺,较系统地研究了苯酚/氯乙酸摩尔比、催化剂用量、反应时间等因素对产品收率的影响.实验结果表明,最佳条件为:苯酚、氯乙酸摩尔比为1:1.2,催化剂用量占苯酚和氯乙酸的质量百分比为9.5%,在回流状态下反应2.5h.该工艺具有反应条件温和的优点,收率达到83.5%,含量在90%左右.%The new craft of the synthesis of phenoxyacetic acid, which takes phenol, chloroacetic acid and sodium hydroxide water-soluble fluid as the raw material, polyethylene glycol-600 as the phase transfer catalyst and water/toluene as the reaction medium, is studied in this paper. The effects of the molar ratio of phenol and chloroacetic acid, catalyst dosage and reaction time on the yield were studied systematically. The experiment re- suits showed that the optimal reaction conditions are as follows : the molar ratio of phenol to chloroacetic acid is 1:1.2,the quality percentage of catalyst amount in phenol and chloroacetic acid was 9.5% ,and reflux reac- tion time is 2.5 h. The reaction condition was mild, the yield can reach 83.5%, and the content was about 90%.

  17. Heterogeneous oxidation of cyclohexanone catalyzed by TS-1:Combined experimental and DFT studies

    Institute of Scientific and Technical Information of China (English)

    Changjiu Xia; Xingtian Shu; Long Ju; Yi Zhao; Hongyi Xu; Bin Zhu; Feifei Gao; Min Lin; Zhenyu Dai; Xiaodong Zou

    2015-01-01

    The reaction mechanism of the oxidation of cyclohexanone catalyzed by titanium silicate zeolite TS-1 using aqueous H2O2 as the oxidant was investigated by combining density function theory (DFT) calculations with experimental studies. DFT calculations showed that H2O2 was adsorbed and activated at the tetrahedral Ti sites. By taking into account the adsorption energy, molecular size, steric hindrance and structural information, a reaction mechanism of Baeyer-Villiger oxidation catalyzed by TS-1 that involves the activation of H2O2 was proposed. Experimental studies showed that the major products of cyclohexanone oxidation by H2O2 catalyzed by a hollow TS-1 zeolite wereε-carprolactone, 6-hydroxyhexanoic acid, and adipic acid. These products were analyzed by GC-MS and were in good agreement with the proposed mechanism. Our studies showed that the reaction mechanism on TS-1 zeolite was different from that on Sn-beta zeolite.

  18. Deoxyribonucleoside kinases: two enzyme families catalyze the same reaction

    DEFF Research Database (Denmark)

    Sandrini, Michael; Piskur, Jure

    2005-01-01

    Mammals have four deoxyribonucleoside kinases, the cytoplasmic (TK1) and mitochondrial (TK2) thymidine kinases, and the deoxycytidine (dCK) and deoxyguanosine (dGK) kinases, which salvage the precursors for nucleic acids synthesis. In addition to the native deoxyribonucleoside substrates, the kin......, the kinases can phosphorylate and thereby activate a variety of anti-cancer and antiviral prodrugs. Recently, the crystal structure of human TK1 has been solved and has revealed that enzymes with fundamentally different origins and folds catalyze similar, crucial cellular reactions....

  19. Decomposition Studies of Triphenylboron, Diphenylborinic Acid and Phenylboric Acid in Aqueous Alkaline Solutions Containing Copper

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, C.L. [Westinghouse Savannah River Company, AIKEN, SC (United States); Peterson, R. A.

    1997-02-11

    This report documents the copper-catalyzed chemical kinetics of triphenylboron, diphenylborinic acid and phenylboric acid (3PB, 2PB and PBA) in aqueous alkaline solution contained in carbon-steel vessels between 40 and 70 degrees C.

  20. Br(o)nsted酸性离子液体催化3,4-二氢嘧啶-2-酮衍生物的合成%Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones Catalyzed by Br(o)nsted Acidic Ionic Liquid

    Institute of Scientific and Technical Information of China (English)

    刘伟华; 高书涛; 冯成; 臧晓欢; 周欣; 马晶军; 王春

    2012-01-01

    以Br(o)nsted酸性离子液体3-甲基咪唑丙烷磺酸-三氟乙酸作为催化剂,无溶剂条件下由芳香醛、乙酰乙酸乙酯和尿素合成了系列3,4-二氢嘧啶-2-酮衍生物.沸水浴中反应30~40 min,产物产率在81%~94%之间.该方法具有反应时间短、收率高、催化剂可回收重复使用等优点.产物结构经1H NMR,IR确证.%A series of 3,4-dihydropyrimidin-2(1H)-ones were prepared through the Biginelli condensation reactions of aromatic aldehydes, keto ester and urea catalyzed by Bronsted acidic ionic liquid 3-methyl-l-(3-sulfopropyl)-imidazolium trifluoroacetate under solvent free conditions. The method is simple, solvent free, high yields and environmental friendly. The catalyst could be recycled and reused. The reactions were carried out in boiling water bath for 30~40 min. The yields of the products were between 81%-4%. All the products have been characterized by 1H NMR and IR spectra.