Sample records for acid catalyzed friedel-crafts

  1. Asymmetric and efficient synthesis of homophenylalanine derivatives via Friedel-Crafts reaction with trifluoromethanesulfonic acid


    Murashige, Ryo; Hayashi, Yuka; Hashimoto, Makoto; 橋本, 誠


    An efficient Friedel-Crafts reaction of TFA-Asp(Cl)-OMe and stoichiometric amounts of benzene was established by using neat trifluoromethanesulfonic acid (TfOH) as solvent and catalyst under a mild condition. This methodology has been applied to many aromatic compounds and enabled synthesis of several homophenylalanine derivatives.

  2. Effective synthesis of optically active trifluoromethyldiazirinyl homophenylalanine and aroylalanine derivatives with the Friedel-Crafts reaction in triflic acid. (United States)

    Murashige, Ryo; Murai, Yuta; Hatanaka, Yasumaru; Hashimoto, Makoto


    The Friedel-Crafts reaction with 3-(3-methoxyphenyl)-3-(trifluoromethyl)-3H-diazirine and optically active N-TFA-Asp(Cl)-OMe in triflic acid afforded homophenylalanine derivatives without any loss of the optical purity.

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

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


    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.

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

    Institute of Scientific and Technical Information of China (English)


    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%.

  5. 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


    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)

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

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    Francesco Pace


    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”

  7. A Quinine-Squaramide Catalyzed Enantioselective Aza-Friedel-Crafts Reaction of Cyclic Trifluoromethyl Ketimines with Naphthols and Electron-Rich Phenols. (United States)

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


    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.

  8. Acilação de Friedel-Crafts do 2-metoxinaftaleno usando o ácido dodecafosfotúngstico suportado em sílica (HPW/SiO2 como catalisador e acetonitrila como solvente Friedel-Crafts acylation of the 2-methoxynaphthalene using the silica-supported dodecatungstophosphoric acid (HPW/SiO2 as catalyst and acetonitrile as solvent

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    Gil Luciano Guedes dos Santos


    Full Text Available The synthesis of fine chemicals intermediates using Friedel-Crafts acylation is one of the most important methods in chemical technology. In this work, the acylation of 2-methoxynaphthalene with acetic anhydride using a silica-supported dodecatungstophosphoric acid catalyst (HPW/SiO2 and acetonitrila as solvent was studied, showing that this reaction is a feasible alternative to produce intermediaries to replace the current methods of production. The reactions using acetonitrile solvent showed yields greater than or equal to the reactions using traditional solvents such as nitrobenzene and dichloroethane. Finally, the modified Eley-Rideal mechanism was proposed to elucidate the experimental data obtained.

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

    Institute of Scientific and Technical Information of China (English)

    张继坦; 张金花; 方旷; 束官莹; 谢美华


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

  10. Greener Friedel-Crafts Acylation using Microwave-enhanced reactivity of Bismuth Triflate in the Friedel-Crafts Benzoylation of Aromatic Compounds with Benzoic Anhydride

    DEFF Research Database (Denmark)

    Tran, Phuong Hoang; Nguyen, hai Truong; Hansen, Poul Erik


    An efficient and facile bismuth trifluoromethanesulfonate-catalyzed benzoylation of aromatic compounds using benzoic anhydride under solvent-free microwave irradiation has been developed. The microwave-assisted Friedel-Crafts benzoylation results in good yields within short reaction times. Bismut...

  11. One-Pot Synthesis of Pyrrolo[1,2-a]indoles by Chiral N-Triflyl Phosphoramide Catalyzed Friedel-Crafts Alkylation of 4,7-Dihydroindole with ②, y-Unsaturated a-Keto Esters

    Institute of Scientific and Technical Information of China (English)

    曾蜜; 张玮; 游书力


    Chiral N-triflyl phosphoramide was found an efficient catalyst for the enantioselective Friedel-Crafts alkylation reaction of 4,7-dihydroindole with β, γ-unsaturated a-keto esters. In the presence of 5 tool% of the optimized catalyst, various pyrrolo[1,2-a]indoles were obtained in excellent enantioselectivity, moderate yields and up to 3 : 1 di- astereoselectivity based on the one-pot synthesis including the Friedel-Crafts alkylation reaction and the subsequent p-benzoquinone oxidation.

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

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


    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.

  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.;


    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...... 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.......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...

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

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    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.

  15. 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.;


    of the total energies and the Gibbs free energies at 298K for 9H-fluorene, the five isomeric monoacetyl-9H-fluorenes and the four s-complexes leading to 1-, 2-, 3- and 4-acetyl-9H-fluorene, respectively, were computed at the DFT B3LYP 6-31G** level of theory. The data serve as a basis for the discussion...

  16. 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.;


    and the Gibbs free energies at 298K for 9H-fluorene, the five isomeric monoacetyl-9H-fluorenes and the four σ-complexes leading to 1-, 2-, 3- and 4-acetyl-9H-fluorene, respectively, were computed at the DFT B3LYP 6-31G** level of theory. The data serve as a basis for the discussion of the reactivity...

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

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


    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.

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

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    Nayef S. Al-Muaikel


    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.


    Institute of Scientific and Technical Information of China (English)

    李侃社; 黄虎; 李锦; 牛红梅; 闫兰英


    With tetrahydrofuran or cyclohexanone as dissolvent, Friedel-Crafts reaction grafting of polyvinyl chloride and polystyrene was realized through microwave irradiation. Graft of PVC-g-PS was successfully prepared. Influence of heating method, reaction temperature, type and mass fraction of catalyst on grafting reaction and grafting ratio was investigated. Graft structure of PVC-g-PS was characterized through FTIR,the mechanism and features were discussed. Results showed that Friedel-Crafts reaction grafting of polyvinyl chloride and polystyrene can carry out through heating by oil bath or microwave irradiation. Under heating with oil bath the graft of PVC-g-PS occurs at the meta position of the benzene ring, and the graft ratio is only 0. 27% ; while in the case of microwave irradiation,the graft of PVC-g-PS occurs at ortho-para positions of the benzene ring,and the graft ratio reaches up to 23%. Anhydrous AlCl3 ,FeCl3 or SnCl4 can all catalyze Friedel-Crafts reaction grafting of polyvinyl chloride and polystyrene, but the best catalytic activity is observed for anhydrous AlCl3. When the mass fraction of anhydrous AlCl3 is 3% ,the highest graft ratio reaches up to 29% , but when mass fraction of anhydrous AlCl3 is over 3% ,the graft ratio declines, PVC begins degradation and produces olefinic bonds. Research results demonstrate that microwave irradiation is an effective way of realizing Friedel-Crafts reaction grafting of polyvinyl chloride and polystyrene.%在四氢呋喃、环己酮等溶液中实现了聚氯乙烯(PVC)与聚苯乙烯(PS)的Friedel-Crafts接枝反应,考察了加热方式、反应温度、催化剂种类、催化剂用量对接枝反应的影响,通过FTIR表征了PVC-g-PS接枝物的结构,探讨了反应的机理和特点.研究发现,油浴加热和微波辐照都能使PVC和PS发生接枝反应,但微波辐照效果更好,油浴加热,接枝率仅0.27%,而微波辐照接枝率高达23%;油浴加热时产物少且多为间位,微波辐照

  20. A facile Friedel-Crafts acylation for the synthesis of polyethylenimine-grafted multi-walled carbon nanotubes as efficient gene delivery vectors. (United States)

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


    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.

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

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    Yunchen Du


    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.

  2. 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;


    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...

  3. Utilization of acidic α-amino acids as acyl donors: an effective stereo-controllable synthesis of aryl-keto α-amino acids and their derivatives. (United States)

    Wang, Lei; Murai, Yuta; Yoshida, Takuma; Okamoto, Masashi; Tachrim, Zetryana Puteri; Hashidoko, Yasuyuki; Hashimoto, Makoto


    Aryl-keto-containing α-amino acids are of great importance in organic chemistry and biochemistry. They are valuable intermediates for the construction of hydroxyl α-amino acids, nonproteinogenic α-amino acids, as well as other biofunctional components. Friedel-Crafts acylation is an effective method to prepare aryl-keto derivatives. In this review, we summarize the preparation of aryl-keto containing α-amino acids by Friedel-Crafts acylation using acidic α-amino acids as acyl-donors and Lewis acids or Brönsted acids as catalysts.

  4. 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)


    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.

  5. Friedel-Crafts alkylations of electron-rich aromatics with 3-hydroxy-2-oxindoles: scope and limitations. (United States)

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


    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.


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    Geovanna Tafurt


    Full Text Available En este trabajo se reporta el estudio experimental de la alquilación intramolecular de Friedel-Crafts de orto alilanilinas Nbencilo sustituidas, que explica desde los puntos de vista cinético y termodinámico la formación de dihidrodibenzo [b,e]azepinas y tetrahidrodibenzo[b,f] azocinas. El seguimiento de los cambios en concentración resultantes del tratamiento en condiciones heterogéneas se llevó a cabo por Cromatografía de Gases-Detector de Ionización en Llama (CG-DILL, mientras que la espectroscopía Ultravioleta-Visible (UV Vis y el análisis quimiométrico con el Método Multivariante de Resolución de Curvas-Mínimos Cuadrados Alternados (MMRC-MCA se usaron para examinar los efectos de las condiciones de reacción en fase homogénea e in situ. Con los resultados obtenidos se puede concluir que la supervisión de parámetros, tales como constantes de velocidad y energías de activación, hizo posible evidenciar los efectos de sustituyente, temperatura, velocidad de agitación y concentración, sobre la velocidad y regio selectividad e la reacción.

  7. 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


    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.

  8. 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


    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.

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

    Directory of Open Access Journals (Sweden)

    Mehdi Ghandi


    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.

  10. 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;


    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 ...

  11. Highly Efficient Synthesis of Unsymmetrical 3,3'-Bis(1H-indol-3-yl)methanes in Water%Highly Efficient Synthesis of Unsymmetrical 3,3'-Bis(1H-indol-3-yl)methanes in Water

    Institute of Scientific and Technical Information of China (English)

    林华; 臧扬; 孙兴文; 林国强


    A simple and practical approach for the preparation of unsymmetric bis(indolyl)methanes (BIMs) was realized by Lewis acid InBr3-catalyzed Friedel-Crafts reaction of indoles with 3-indolyl-substituted phthalides in water.

  12. Study on In-situ Compatibilization of SAN/POE Blends Using Friedel-Crafts Alkylation Reaction%Friedel-Crafts烷基化反应原位增容SAN/POE研究

    Institute of Scientific and Technical Information of China (English)

    徐建平; 张敏华


    Using Friedel-Crafts alkylation reaction in situ compatibilizing SAN/POE blends in the melting state, the effect of the A1C13 on the performance of the system were evaluated. The results showed that for SAN/POE (70/30) blends, adding 0.4% A1Cl3 the tensile strength was improved by 31% and the elongation at break was raised by 123%. The analysis of FT-IR indicated that A1Cl3 could initiate Friedel-Crafts alkylation reaction between SAN and POE; The dynamic rheological analysis, the thermal analysis and the phase morphology analysis showed that the apparent viscosity, the thermal stability and the dispersal uniformity of the compatibilized SAN/POE blends were improved due to the formation of SAN-g-POE graft copolymer.%在熔融状态下,利用Friedel-Crafts烷基化反应原位增容苯乙烯-丙烯腈共聚物(SAN)/乙烯-辛烯共聚物(POE)共混物,考察了AlCl3对该共混物性能的影响.结果表明,对于SAN/POE(70/30,质量比)共混物,加入0.4% AlCl3时,共混物的拉伸强度提高了31%,断裂伸长率提高了123%;红外光谱分析表明,AlCl3可以引发SAN与POE发生Friedel-Crafts烷基化反应生成SAN-g-POE接枝物;旋转流变分析、热分析以及微观结构分析表明,由于增容体系中有SAN-g-POE接枝物生成,共混体系的表观黏度增加,热稳定性提高,分散均匀性提高.

  13. Chiral BINOL-derived phosphoric acids: privileged Brønsted acid organocatalysts for C-C bond formation reactions. (United States)

    Zamfir, Alexandru; Schenker, Sebastian; Freund, Matthias; Tsogoeva, Svetlana B


    BINOL-derived phosphoric acids have emerged during the last five years as powerful chiral Brønsted acid catalysts in many enantioselective processes. The most successful transformations carried out with chiral BINOL phosphates include C-C bond formation reactions. The recent advances have been reviewed in this article with a focus being placed on hydrocyanations, aldol-type, Mannich, Friedel-Crafts, aza-ene-type, Diels-Alder, as well as cascade and multi-component reactions.

  14. 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)


    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.

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


    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.

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

    KAUST Repository

    Li, Cheng Chao


    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.

  17. Lipase catalyzed synthesis of epoxy-fatty acids

    Institute of Scientific and Technical Information of China (English)

    CHEN, Qian; LI, Zu-Yi


    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

  18. 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


    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.

  19. Palladium-Catalyzed alpha-Arylation of Tetramic Acids

    DEFF Research Database (Denmark)

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


    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 K2CO...

  20. 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 o...

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

    Institute of Scientific and Technical Information of China (English)


    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. Esterification of phenolic acids catalyzed by lipases immobilized in organogels. (United States)

    Zoumpanioti, M; Merianou, E; Karandreas, T; Stamatis, H; Xenakis, A


    Lipases from Rhizomucor miehei and Candida antarctica B were immobilized in hydroxypropylmethyl cellulose organogels based on surfactant-free microemulsions consisting of n-hexane, 1-propanol and water. Both lipases kept their catalytic activity, catalyzing the esterification reactions of various phenolic acids including cinnamic acid derivatives. High reaction rates and yields (up to 94%) were obtained when lipase from C. antarctica was used. Kinetic studies have been performed and apparent kinetic constants were determined showing that ester synthesis catalyzed by immobilized lipases occurs via the Michaelis-Menten mechanism.

  3. Rh-Catalyzed arylation of fluorinated ketones with arylboronic acids. (United States)

    Dobson, Luca S; Pattison, Graham


    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.

  4. An acid-catalyzed macrolactonization protocol. (United States)

    Trost, Barry M; Chisholm, John D


    [reaction: see text] An efficient macrolactonization protocol devoid of any base was developed derived from the use of vinyl esters in transesterification. Subjecting a hydroxy acid and ethoxyacetylene to 2 mol % [RuCl(2)(p-cymene)](2) in toluene followed by addition of camphorsulfonic acid or inverse addition provided macrolactones in good yields.

  5. Biodiesel by acid-catalyzed transesterification with butanol


    Bynes, Adrian


    Jatropha oil and Rapeseed oil was transesterified with n-butanol by the use of H2SO4. Before conducting the experiments a review of the effect of alcohol type was preformed. Alcohols from methanol to butanol, branched and straight, were reviewed for the effect on the acid catalyzed transesterification reaction. From the review it was found that propanol and butanol were the best for the acidic transesterification reaction. Variables such as time, temperature, alcohol amount and catalyst c...

  6. Kinetics of acid-catalyzed cleavage of cumene hydroperoxide. (United States)

    Levin, M E; Gonzales, N O; Zimmerman, L W; Yang, J


    The cleavage of cumene hydroperoxide, in the presence of sulfuric acid, to form phenol and acetone has been examined by adiabatic calorimetry. As expected, acid can catalyze cumene hydroperoxide reaction at temperatures below that of thermally-induced decomposition. At elevated acid concentrations, reactivity is also observed at or below room temperature. The exhibited reactivity behavior is complex and is significantly affected by the presence of other species (including the products). Several reaction models have been explored to explain the behavior and these are discussed.

  7. Facile synthesis of (S)-beta-hydroxy-beta-trichloromethylated aromatic ketones by the regioselective ring cleavage of chiral beta-trichloromethyl-beta-propiolactone under the Friedel-Crafts conditions

    NARCIS (Netherlands)

    Fujisawa, T; Ito, T; Fujimoto, K; Shimizu, M; Wynberg, H; Staring, EGJ


    The reaction of enantiomerically pure beta-trichloromethyl-beta-propiolactone (1) as a chiral building block with an aromatic compound in the presence of Lewis acid provided an acylated product with a chiral trichloromethyl carbinol moiety. The acylated product was used as an effective chiral syntho

  8. F-C烷基化反应原位增容工艺对PS/LLDPE合金结构与性能的影响%Effect of In-Situ Compatibilization Technique by Friedel-Crafts Alkylation Reaction on the Structure and Properties of PS/LLDPE Blends

    Institute of Scientific and Technical Information of China (English)

    徐建平; 刘涛涛; 陈建定


    在熔融状态下,利用无水AlCl3引发大分子之间的Friedel-Crafts烷基化反应来增容聚苯乙烯(PS)/线性低密度聚乙烯(LLDPE)(80/20)合金。研究了"一步法"和"两步法"增容工艺对PS/LLDPE合金结构和性能的影响。结果表明,以"一步法"增容PS/LLDPE(50/50)合金40份为母料,与60份聚苯乙烯混合("两步法")制备PS/LLDPE(80/20)合金,可有效地降低聚苯乙烯降解对合金性能的影响,提高合金的热稳定性和力学性能;从扫描电镜(SEM)照片可以看出,"两步法"制备的合金的分散相更加均匀细小,韧性断裂特征明显。%In the molten state,PS/LLDPE(80/20)blends were compatibilized by Friedel-Crafts alkylation reaction with anhydrous AlCl3.The effect of structure and properties of PS/LLDPE(80/20)blends by "one-step" and "two-step" compatibilization technique were studied.The results showed that using the "one-step" compatibilized PS/LLDPE(50/50)blends 40 parts as the master batch product,mixed with 60 parts polystyrene("two-step") to prepared PS/LLDPE(80/20)blends,which could effectively reduce the influence of the degradation of polystyrene,and improving the thermal stability and mechanical properties of the blends.As can be seen from SEM photographs,the dispersed phase of "two-step" preparation blends is more homogeneous and smaller,and ductile fracture characteristics significantly.

  9. Synthesis of Rosin Acid Starch Catalyzed by Lipase

    Directory of Open Access Journals (Sweden)

    Rihui Lin


    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. 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


    @@ 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.

  11. Acid-catalyzed production of biodiesel from waste frying oil

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, S.; Dube, M.A.; McLean, D.D. [Department of Chemical Engineering, University of Ottawa, Ottawa, ON (Canada); Kates, M. [Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON (Canada)


    The reaction kinetics of acid-catalyzed transesterification of waste frying oil in excess methanol to form fatty acid methyl esters (FAME), for possible use as biodiesel, was studied. Rate of mixing, feed composition (molar ratio oil:methanol:acid) and temperature were independent variables. There was no significant difference in the yield of FAME when the rate of mixing was in the turbulent range 100 to 600rpm. The oil:methanol:acid molar ratios and the temperature were the most significant factors affecting the yield of FAME. At 70{sup o}C with oil:methanol:acid molar ratios of 1:245:3.8, and at 80{sup o}C with oil:methanol:acid molar ratios in the range 1:74:1.9-1:245:3.8, the transesterification was essentially a pseudo-first-order reaction as a result of the large excess of methanol which drove the reaction to completion (99+/-1% at 4h). In the presence of the large excess of methanol, free fatty acids present in the waste oil were very rapidly converted to methyl esters in the first few minutes under the above conditions. Little or no monoglycerides were detected during the course of the reaction, and diglycerides present in the initial waste oil were rapidly converted to FAME. (author)

  12. 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)


    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)

  13. Acid-Catalyzed Preparation of Biodiesel from Waste Vegetable Oil: An Experiment for the Undergraduate Organic Chemistry Laboratory (United States)

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


    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…

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

    Energy Technology Data Exchange (ETDEWEB)

    Ammar, Muhammad; Jiang, Sai; Ji, Shengfu, E-mail:


    A new strategy has been developed for the encapsulation of the phosphotungstic heteropoly acid (H{sub 3}PW{sub 12}O{sub 40} 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%. - Graphical abstract: The PTA@ZIF-67 catalysts with different PTA content were prepared by encapsulating the PTA into ZIF-67 cage and the as-synthesized catalysts exhibited good catalytic activity for the Friedel–Craft acylation of anisole with benzoyl chloride.

  15. Kinetics of acid base catalyzed transesterification of Jatropha curcas oil. (United States)

    Jain, Siddharth; Sharma, M P


    Out of various non-edible oil resources, Jatropha curcas oil (JCO) is considered as future feedstock for biodiesel production in India. Limited work is reported on the kinetics of transesterification of high free fatty acids containing oil. The present study reports the results of kinetic study of two-step acid base catalyzed transesterification process carried out at an optimum temperature of 65 °C and 50 °C for esterification and transesterification respectively under the optimum methanol to oil ratio of 3:7 (v/v), catalyst concentration 1% (w/w) for H₂SO₄ and NaOH. The yield of methyl ester (ME) has been used to study the effect of different parameters. The results indicate that both esterification and transesterification reaction are of first order with reaction rate constant of 0.0031 min⁻¹ and 0.008 min⁻¹ respectively. The maximum yield of 21.2% of ME during esterification and 90.1% from transesterification of pretreated JCO has been obtained.

  16. Kinetic study of free fatty acid esterification reaction catalyzed by recoverable and reusable hydrochloric acid. (United States)

    Su, Chia-Hung


    The catalytic performance and recoverability of several homogeneous acid catalysts (hydrochloric, sulfuric, and nitric acids) for the esterification of enzyme-hydrolyzed free fatty acid (FFA) and methanol were studied. Although all tested catalysts drove the reaction to a high yield, hydrochloric acid was the only catalyst that could be considerably recovered and reused. The kinetics of the esterification reaction catalyzed by hydrochloric acid was investigated under varying catalyst loading (0.1-1M), reaction temperature (303-343K), and methanol/FFA molar ratio (1:1-20:1). In addition, a pseudo-homogeneous kinetic model incorporating the above factors was developed. A good agreement (r(2)=0.98) between the experimental and calculated data was obtained, thus proving the reliability of the model. Furthermore, the reusability of hydrochloric acid in FFA esterification can be predicted by the developed model. The recoverable hydrochloric acid achieved high yields of FFA esterification within five times of reuse.

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


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


    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...

  18. Integrated Production of Xylonic Acid and Bioethanol from Acid-Catalyzed Steam-Exploded Corn Stover. (United States)

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


    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.

  19. Optimizing the Acid Catalyzed Synthesis of Hyperbranched Poly(Glycerol-diacids) Oligomers (United States)

    Oligomeric pre-polymers were synthesized by the acid-catalyzed condensation of glycerol with succinic acid, glutaric acid and azelaic acid in dimethylsulfoxide (DMSO) or dimethylformamide (DMF). The prepolymers were obtained, on average in 84% yield, and were characterized by proton NMR, MALDI-TOF ...

  20. Synthesis and Characterization of 9-Hydroxyphenalenone Using 2D NMR Techniques (United States)

    Caes, Benjamin; Jensen, Dell, Jr.


    9-Hydroxyphenalenone is a planar multicyclic [beta]-keto-enol, which is synthesized via a Friedel-Crafts acylation followed by acid-catalyzed intramolecular Michael addition with the loss of a phenyl group in a one-pot reaction during a four-hour lab period. Tautomerization of the [beta]-keto-enol results in C[subscript 2v] symmetry on the NMR…

  1. Selective and recyclable depolymerization of cellulose to levulinic acid catalyzed by acidic ionic liquid. (United States)

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


    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.

  2. Silver-Catalyzed Decarboxylative Addition/Cyclization of Activated Alkenes with Aliphatic Carboxylic Acids. (United States)

    Xia, Xiao-Feng; Zhu, Su-Li; Chen, Chao; Wang, Haijun; Liang, Yong-Min


    A silver-catalyzed decarboxylative addition/aryl migration/desulfonylation of N-phenyl-N-(phenylsulfonyl)methacrylamide with primary, secondary, and tertiary carboxylic acids was described. The protocol provides an efficient approach for the synthesis of α-all-carbon quaternary stereocenters amides and isoquinolinediones. It was proposed that the radical generated from the silver-catalyzed decarboxylation was involved in the sequence reaction.

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

    Directory of Open Access Journals (Sweden)

    Kayla M. Fisher


    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.

  4. Formation of Linear Polyenes in Thermal Dehydration of Polyvinyl Alcohol, Catalyzed by Phosphotungstic Acid (United States)

    Tretinnikov, O. N.; Sushko, N. I.


    In order to obtain linear polyenes in polyvinyl alcohol films via acid-catalyzed thermal dehydration of the polyvinyl alcohol, we used phosphotungstic acid as the catalyst: a safe and heat-stable solid chemical compound. We established that phosphotungstic acid, introduced as solid nanoparticles into polyvinyl alcohol films, is a more effective dehydration catalyst than hydrochloric acid, since in contrast to HCl it does not evaporate from the film during heat treatment.

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

    DEFF Research Database (Denmark)

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


    Acetic acid (AA)-catalyzed liquid hot water (LHW) pretreatments on raw corn stover (RCS) were carried out at 195 °C at 15 min with the acetic acid concentrations between 0 and 400 g/kg RCS. After pretreatment, the liquor fractions and water-insoluble solids (WIS) were collected separately...

  6. 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


    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

  7. Iodine-catalyzed disproportionation of aryl-substituted ethers under solvent-free reaction conditions. (United States)

    Jereb, Marjan; Vražič, Dejan


    Iodine was demonstrated to be an efficient catalyst for disproportionation of aryl-substituted ethers under solvent-free reaction conditions. Variously substituted 1,1,1',1'-tetraaryldimethyl ethers were transformed into the corresponding diarylketone and diarylmethane derivatives. I2-catalyzed transformation of 4-methoxyphenyl substituted ethers yielded mono- and dialkylated Friedel-Crafts products as well. Treatment of trityl alkyl and trityl benzyl ethers with a catalytic amount of iodine produced triphenylmethane and the corresponding aldehydes and ketones. The electron-donating substituents facilitated the reaction, while the electron-withdrawing groups retarded it; the difference in reactivity is not very high. Such an observation may be in favour of hydride transfer, predominantly from the less electron rich side of the ether with more stable carbocation formation. With the isotopic studies it was established that a substantial portion of the C-H bond scission took place in the rate-determining step, while the carbonyl oxygen atom originated from the starting ether, and not from the air. The transformation took place under air and under argon, and HI was not a functioning catalyst.

  8. Kinetics of Ethyl Acetate Synthesis Catalyzed by Acidic Resins (United States)

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


    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…

  9. 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


    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.

  10. Dietary phenolic acids and ascorbic acid: Influence on acid-catalyzed nitrosative chemistry in the presence and absence of lipids. (United States)

    Combet, Emilie; El Mesmari, Aziza; Preston, Tom; Crozier, Alan; McColl, Kenneth E L


    Acid-catalyzed nitrosation and production of potentially carcinogenic nitrosative species is focused at the gastroesophageal junction, where salivary nitrite, derived from dietary nitrate, encounters the gastric juice. Ascorbic acid provides protection by converting nitrosative species to nitric oxide (NO). However, NO may diffuse into adjacent lipid, where it reacts with O(2) to re-form nitrosative species and N-nitrosocompounds (NOC). In this way, ascorbic acid promotes acid nitrosation. Using a novel benchtop model representing the gastroesophageal junction, this study aimed to clarify the action of a range of water-soluble antioxidants on the nitrosative mechanisms in the presence or absence of lipids. Caffeic, ferulic, gallic, or chlorogenic and ascorbic acids were added individually to simulated gastric juice containing secondary amines, with or without lipid. NO and O(2) levels were monitored by electrochemical detection. NOC were measured in both aqueous and lipid phases by gas chromatography-tandem mass spectrometry. In the absence of lipids, all antioxidants tested inhibited nitrosation, ranging from 35.9 + or - 7.4% with gallic acid to 93 + or - 0.6% with ferulic acid. In the presence of lipids, the impact of each antioxidant on nitrosation was inversely correlated with the levels of NO they generated (R(2) = 0.95, pascorbic acid promoted nitrosation, whereas ferulic and caffeic acids markedly inhibited nitrosation.

  11. Silver-catalyzed arylation of (hetero)arenes by oxidative decarboxylation of aromatic carboxylic acids. (United States)

    Kan, Jian; Huang, Shijun; Lin, Jin; Zhang, Min; Su, Weiping


    A long-standing challenge in Minisci reactions is achieving the arylation of heteroarenes by oxidative decarboxylation of aromatic carboxylic acids. To address this challenge, the silver-catalyzed intermolecular Minisci reaction of aromatic carboxylic acids was developed. With an inexpensive silver salt as a catalyst, this new reaction enables a variety of aromatic carboxylic acids to undergo decarboxylative coupling with electron-deficient arenes or heteroarenes regardless of the position of the substituents on the aromatic carboxylic acid, thus eliminating the need for ortho-substituted aromatic carboxylic acids, which were a limitation of previously reported methods.

  12. 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


    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.

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

    Institute of Scientific and Technical Information of China (English)


    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.

  14. 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


    allowing the use of the cheapest available source of fructose: high fructose corn syrup. The dehydration was catalyzed by hydrochloric acid and conducted in acetone-water mixtures, which ensured good selectivity towards HMF and eliminated precipitation of polymer by-products (insoluble humins). Through...

  15. A Meldrum's Acid Catalyzed Synthesis of Bis (indolyl) methanes in Water under Ultrasonic Condition

    Institute of Scientific and Technical Information of China (English)

    WANG,Shun-Yi; JI,Shun-Jun; SU,Xiao-Ming


    A highly effective Meldrum's acid catalyzed synthesis of bis(indol-3-yl)methanes has been developed. This reaction provides the corresponding bis(indol-3-yl)methanes in high yields after short reaction time in the presence of 2 mol% catalyst in water under ultrasonic condition.

  16. Palladium-catalyzed regioselective decarboxylative alkylation of arenes and heteroarenes with aliphatic carboxylic acids. (United States)

    Premi, Chanchal; Dixit, Ankit; Jain, Nidhi


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

  17. Facile synthesis of small crystal ZSM-5 zeolite by acid-catalyzed hydrolysis of tetraethylorthosilicate

    Institute of Scientific and Technical Information of China (English)


    Small crystal zeolites ZSM-5 with sizes of 150-300 nm were synthesized using the colloidal silicate precursors as the silica source created by the acid-catalyzed hydrolysis of tetraethylorthosilicate with tetrapropylammonium bromide as the structure-directing agent within a short crystallization time of 20-35 h. The precursors and final products were detected by XRD, SEM, ICP and DLS.

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

    NARCIS (Netherlands)

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


    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. 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


    @@ 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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


    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)

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

    Directory of Open Access Journals (Sweden)

    Brett N. Hemric


    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.

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

    Institute of Scientific and Technical Information of China (English)


    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.

  3. On the Brønsted acid-catalyzed homogeneous hydrolysis of furans. (United States)

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


    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.

  4. A Copper-Assisted Palladium(II)-catalyzed Direct Arylation of Cyclic Enaminones with Arylboronic Acids


    Kim, Yong Wook; Niphakis, Micah J.; Georg, Gunda I.


    Described herein is a palladium(II)-catalyzed direct arylation of cyclic enaminones with arylboronic acids. The versatility of this method is that both electron-rich and electron-poor boronic acids can be coupled in high yields. A mixture of two Cu(II) additives was crucial for efficient cross-coupling. The role of each Cu(II) reagent appears to be distinct and complementary serving to assist catalyst reoxidation and transmetallation through a putative arylcopper intermediate.

  5. Copper-catalyzed formic acid synthesis from CO2 with hydrosilanes and H2O. (United States)

    Motokura, Ken; Kashiwame, Daiki; Miyaji, Akimitsu; Baba, Toshihide


    A copper-catalyzed formic acid synthesis from CO2 with hydrosilanes has been accomplished. The Cu(OAc)2·H2O-1,2-bis(diphenylphosphino)benzene system is highly effective for the formic acid synthesis under 1 atm of CO2. The TON value approached 8100 in 6 h. The reaction pathway was revealed by in situ NMR analysis and isotopic experiments.

  6. Silver-catalyzed decarboxylative chlorination of aliphatic carboxylic acids. (United States)

    Wang, Zhentao; Zhu, Lin; Yin, Feng; Su, Zhongquan; Li, Zhaodong; Li, Chaozhong


    Decarboxylative halogenation of carboxylic acids, the Hunsdiecker reaction, is one of the fundamental functional group transformations in organic chemistry. As the initial method requires the preparations of strictly anhydrous silver carboxylates, several modifications have been developed to simplify the procedures. However, these methods suffer from the use of highly toxic reagents, harsh reaction conditions, or limited scope of application. In addition, none is catalytic for aliphatic carboxylic acids. In this Article, we report the first catalytic Hunsdiecker reaction of aliphatic carboxylic acids. Thus, with the catalysis of Ag(Phen)(2)OTf, the reactions of carboxylic acids with t-butyl hypochlorite afforded the corresponding chlorodecarboxylation products in high yields under mild conditions. This method is not only efficient and general, but also chemoselective. Moreover, it exhibits remarkable functional group compatibility, making it of more practical value in organic synthesis. The mechanism of single electron transfer followed by chlorine atom transfer is proposed for the catalytic chlorodecarboxylation.

  7. Ionic liquid supported acid/base-catalyzed production of biodiesel. (United States)

    Lapis, Alexandre A M; de Oliveira, Luciane F; Neto, Brenno A D; Dupont, Jairton


    The transesterification (alcoholysis) reaction was successfully applied to synthesize biodiesel from vegetable oils using imidazolium-based ionic liquids under multiphase acidic and basic conditions. Under basic conditions, the combination of the ionic liquid 1-n-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMINTf2), alcohols, and K2CO3 (40 mol %) results in the production of biodiesel from soybean oil in high yields (>98%) and purity. H2SO4 immobilized in BMINTf2 efficiently promotes the transesterification reaction of soybean oil and various primary and secondary alcohols. In this multiphase process the acid is almost completely retained in the ionic liquid phase, while the biodiesel forms a separate phase. The recovered ionic liquid containing the acid could be reused at least six times without any significant loss in the biodiesel yield or selectivity. In both catalytic processes (acid and base), the reactions proceed as typical multiphasic systems in which the formed biodiesel accumulates as the upper phase and the glycerol by-product is selectively captured by the alcohol-ionic liquid-acid/base phase. Classical ionic liquids such as 1-n-butyl-3-methylimidazolium tetrafluoroborate and hexafluorophosphate are not stable under these acidic or basic conditions and decompose.

  8. Particle growth by acid-catalyzed heterogeneous reactions of organic carbonyls on preexisting aerosols. (United States)

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


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

  9. Detoxification of acidic catalyzed hydrolysate of Kappaphycus alvarezii (cottonii). (United States)

    Meinita, Maria Dyah Nur; Hong, Yong-Ki; Jeong, Gwi-Taek


    Red seaweed, Kappaphycus alvarezii, holds great promise for use in biofuel production due to its high carbohydrate content. In this study, we investigated the effect of fermentation inhibitors to the K. alvarezii hydrolysate on cell growth and ethanol fermentation. In addition, detoxification of fermentation inhibitors was performed to decrease the fermentation inhibitory effect. 5-Hydroxymethylfurfural and levulinic acid, which are liberated from acidic hydrolysis, was also observed in the hydrolysate of K. alvarezii. These compounds inhibited ethanol fermentation. In order to remove these inhibitors, activated charcoal and calcium hydroxide were introduced. The efficiency of activated charcoals was examined and over-liming was used to remove the inhibitors. Activated charcoal was found to be more effective than calcium hydroxide to remove the inhibitors. Detoxification by activated charcoal strongly improved the fermentability of dilute acid hydrolysate in the production of bioethanol from K. alvarezii with Saccharomyces cerevisiae. The optimal detoxifying conditions were found to be below an activated charcoal concentration of 5%.

  10. Silver-Catalyzed Decarboxylative Azidation of Aliphatic Carboxylic Acids. (United States)

    Zhu, Yuchao; Li, Xinyao; Wang, Xiaoyang; Huang, Xiaoqiang; Shen, Tao; Zhang, Yiqun; Sun, Xiang; Zou, Miancheng; Song, Song; Jiao, Ning


    The catalytic decarboxylative nitrogenation of aliphatic carboxylic acids for the synthesis of alkyl azides is reported. A series of tertiary, secondary, and primary organoazides were prepared from easily available aliphatic carboxylic acids by using K2S2O8 as the oxidant and PhSO2N3 as the nitrogen source. The EPR experiment sufficiently proved that an alkyl radical process was generated in the process, and DFT calculations further supported the SET process followed by a stepwise SH2 reaction to afford azide product.

  11. Development of Fluorous Lewis Acid-Catalyzed Reactions

    Directory of Open Access Journals (Sweden)

    Joji Nishikido


    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.

  12. Efficient production of free fatty acids from ionic liquid-based acid- or enzyme-catalyzed bamboo hydrolysate. (United States)

    Mi, Le; Qin, Dandan; Cheng, Jie; Wang, Dan; Li, Sha; Wei, Xuetuan


    Two engineered Escherichia coli strains, DQ101 (MG1655 fadD (-))/pDQTES and DQ101 (MG1655 fadD (-))/pDQTESZ were constructed to investigate the free fatty acid production using ionic liquid-based acid- or enzyme-catalyzed bamboo hydrolysate as carbon source in this study. The plasmid, pDQTES, carrying an acyl-ACP thioesterase 'TesA of E. coli in pTrc99A was constructed firstly, and then (3R)-hydroxyacyl-ACP dehydratase was ligated after the TesA to give the plasmid pDQTESZ. These two strains exhibited efficient fatty acid production when glucose was used as the sole carbon source, with a final concentration of 2.45 and 3.32 g/L, respectively. The free fatty acid production of the two strains on xylose is not as efficient as that on glucose, which was 2.32 and 2.96 g/L, respectively. For mixed sugars, DQ101 (MG1655 fadD (-))-based strains utilized glucose and pentose sequentially under the carbon catabolite repression (CCR) regulation. The highest total FFAs concentration from the mixed sugar culture reached 2.81 g/L by DQ101 (MG1655 fadD (-))/pDQTESZ. Furthermore, when ionic liquid-based enzyme-catalyzed bamboo hydrolysate was used as the carbon source, the strain DQ101 (MG1655 fadD (-))/pDQTESZ could produce 1.23 g/L FFAs with a yield of 0.13 g/g, and while it just produced 0.65 g/L free fatty acid with the ionic liquid-based acid-catalyzed bamboo hydrolysate as the feedstock. The results suggested that enzymatic catalyzed bamboo hydrolysate with ionic liquid pretreatment could serve as an efficient feedstock for free fatty acid production.

  13. Homologation of α-aryl amino acids through quinone-catalyzed decarboxylation/Mukaiyama-Mannich addition. (United States)

    Haugeberg, Benjamin J; Phan, Johnny H; Liu, Xinyun; O'Connor, Thomas J; Clift, Michael D


    A new method for amino acid homologation by way of formal C-C bond functionalization is reported. This method utilizes a 2-step/1-pot protocol to convert α-amino acids to their corresponding N-protected β-amino esters through quinone-catalyzed oxidative decarboxylation/in situ Mukaiyama-Mannich addition. The scope and limitations of this chemistry are presented. This methodology provides an alternative to the classical Arndt-Eistert homologation for accessing β-amino acid derivatives. The resulting N-protected amine products can be easily deprotected to afford the corresponding free amines.

  14. Lewis acid catalyzed transformations of Z-ligustilide

    Energy Technology Data Exchange (ETDEWEB)

    Rios, Maria Yolanda [Universidad Autonoma del Estado de Morelos, Cuernavaca, Morelos (Mexico); Delgado, Guillermo [Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico)


    Some Lewis acid mediated reactions of Z-ligustilide (1), a bioactive constituent of the medicinal species Ligusticum porteri, were investigated. These reactions provided varying mixtures of Z-butylidenephthalide (7), E-butylidenephthalide (8), n-butyphthalide (13), and novel linear dimeric phthalides (9-12) as the main products. The formation of the dimers occurred in low yields and with regio and situ-selectivity. Initial competitive O- and C- complexation of the Lewis acid with Z-ligustilide promoted the formation of the dimers occurred in low yields and with regio and situ- selectivity. Initial competitive O- and C- complexation of the Lewis acid with Z-ligustilide promoted the formation of carbocations at C(8), C(6) and C(7), which were stabilized by the addition of the C(6')-C(7') olefin of a second unit of the starting material, to provide cations at C(6') and C(7'). Subsequent isomerizations and elimination of the catalyst afforded the dimeric products 9-12. The yields and structure of the products are quite dependent on variations of the reaction conditions and the catalyst employed. [Spanish] Se investigaron algunas reacciones de Z-ligustilidas (1), un constituyente bioactivo de la planta medicinal Ligusticum porteri, catalizadas por acidos de Lewis. Estas reacciones produjeron mezclas variables de Z-butilidenftalida (7), E-butilidenftalida (8), n-butilftalida (13), y ftalidos dimetricos lineales novedosos (9-12) como productos principales. La formacion de los dimeros procedio en rendimientos bajos y con regio- y situ-selectividad. La O- y C- complejacion competitiva inicial del acido de Lewis con Z-lingustilida promueve la formacion de cationes en C(8), C(6) y C(7), los cuales son estabilizados por la adicion de la olefina C(6')-C(7') de una segunda unidad de la materia prima para generar los cationes en C(6')-C(7'). Isomerizaciones subsecuentes y la eliminacion del catalizador conducen a los productos dimericos 9


    Institute of Scientific and Technical Information of China (English)

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


    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.

  16. 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


    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.

  17. Enantioselective aldol reaction between isatins and cyclohexanone catalyzed by amino acid sulphonamides. (United States)

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


    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.

  18. Acetic acid-catalyzed formation of N-phenylphthalimide from phthalanilic acid: a computational study of the mechanism. (United States)

    Takahashi, Ohgi; Kirikoshi, Ryota; Manabe, Noriyoshi


    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.

  19. Acetic Acid Can Catalyze Succinimide Formation from Aspartic Acid Residues by a Concerted Bond Reorganization Mechanism: A Computational Study (United States)

    Takahashi, Ohgi; Kirikoshi, Ryota; Manabe, Noriyoshi


    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. PMID:25588215

  20. 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


    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.

  1. 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.


    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 or EC The K m of this crude o-hydroxylation activity in the red grape skin was 0.5 mM with p-coumaric acid....

  2. 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


    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.

  3. Stability of prostacyclin analogues: an unusual lack of reactivity in acid-catalyzed alkene hydration. (United States)

    Magill, A; O'Yang, C; Powell, M F


    Prostacyclin analogue 5 undergoes specific acid-catalyzed hydration (kH+ = 1.9 x 10(-7)M-1 sec-1 at 25 degrees C) and a pH-independent oxidation reaction (k0 = 1.2 x 10(-10) sec-1 at 25 degrees C) above pH approximately 5. The hydration reaction for 5 is much slower than for other structurally similar exocyclic alkenes, even though the rate-determining step is proton transfer. This slowness of reaction and an analysis of the pH-rate profile show that 5 does not exhibit significant intramolecular general acid catalysis, as does prostacyclin.

  4. 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


    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.

  5. 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)


    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)

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

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


    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.

  7. [Asymmetric synthesis of aromatic L-amino acids catalyzed by transaminase]. (United States)

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


    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.

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

    Directory of Open Access Journals (Sweden)

    Marcio J. da Silva


    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.

  9. First Palladium-Catalyzed Addition of Organoboronic Acids to Allenes: A Magic Regioselectivity Switch by Using a Base or an Acid

    Institute of Scientific and Technical Information of China (English)

    MA Sheng-Ming; JIAO Ning


    @@ Organoboronic acids enjoy high prestige in the metal-catalyzed C-C bond formations. The most notable progress is the rhodium- and nickel-catalyzed conjugate addition with unsaturated carbon-carbon bond, aldehydes, N-sulfonyl imines reported by Miyaura, Hayashi and Shirakawa.[1

  10. Production of Biodiesel from High Acid Value Waste Cooking Oil Using an Optimized Lipase Enzyme/Acid-Catalyzed Hybrid Process

    Directory of Open Access Journals (Sweden)

    N. Saifuddin


    Full Text Available The present study is aimed at developing an enzymatic/acid-catalyzed hybrid process for biodiesel production using waste cooking oil with high acid value (poor quality as feedstock. Tuned enzyme was prepared using a rapid drying technique of microwave dehydration (time required around 15 minutes. Further enhancement was achieved by three phase partitioning (TPP method. The results on the lipase enzyme which was subjected to pH tuning and TPP, indicated remarkable increase in the initial rate of transesterification by 3.8 times. Microwave irradiation was found to increase the initial reaction rates by further 1.6 times, hence giving a combined increase in activity of about 5.4 times. The optimized enzyme was used for hydrolysis and 88% of the oil taken initially was hydrolyzed by the lipase. The hydrolysate was further used in acid-catalyzed esterification for biodiesel production. By using a feedstock to methanol molar ratio of 1:15 and a sulphuric acid concentration of 2.5%, a biodiesel conversion of 88% was obtained at 50 °C for an hour reaction time. This hybrid process may open a way for biodiesel production using unrefined and used oil with high acid value as feedstock.

  11. Role of Lewis acid additives in a palladium catalyzed directed C-H functionalization reaction of benzohydroxamic acid to isoxazolone. (United States)

    Athira, C; Sunoj, Raghavan B


    Metallic salts as well as protic additives are widely employed in transition metal catalyzed C-H bond functionalization reactions to improve the efficiency of catalytic protocols. In one such example, ZnCl2 and pivalic acid are used as additives in a palladium catalyzed synthesis of isoxazolone from a readily available benzohydroxamic acid under one pot conditions. In this article, we present some important mechanistic insights into the role of ZnCl2 and pivalic acid, gained by using density functional theory (M06) computations. Two interesting modes of action of ZnCl2 are identified in various catalytic steps involved in the formation of isoxazolone. The conventional Lewis acid coordination wherein zinc chloride (ZnCl2·(DMA)) binds to the carbonyl group is found to be more favored in the C-H activation step. However, the participation of a hetero-bimetallic Pd-Zn species is preferred in reductive elimination leading to Caryl-N bond formation. Pivalic acid helps in relay proton transfer in C-H bond activation through a cyclometallation deprotonation (CMD) process. The explicit inclusion of ZnCl2 and solvent N,N-dimethyl acetamide (DMA) stabilizes the transition state and also helps reduce the activation barrier for the C-H bond activation step. The electronic communication between the two metal species is playing a crucial role in stabilizing the Caryl-N bond formation transition state through a Pd-Zn hetero-bimetallic interaction.

  12. 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.


    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.

  13. The Acid Catalyzed Nitration of Methanol: Formation of Methyl Nitrate via Aerosol Chemistry (United States)

    Riffel, Brent G.; Michelsen, Rebecca R.; Iraci, Laura T.


    The liquid phase acid catalyzed reaction of methanol with nitric acid to yield methyl nitrate under atmospheric conditions has been investigated using gas phase infrared spectroscopy. This nitration reaction is expected to occur in acidic aerosol particles found in the upper troposphere/lower stratosphere as highly soluble methanol and nitric acid diffuse into these aerosols. Gaseous methyl nitrate is released upon formation, suggesting that some fraction of NO(x) may he liberated from nitric acid (methyl nitrate is later photolyzed to NO(x)) before it is removed from the atmosphere by wet deposition. Thus, this reaction may have important implications for the NO(x) budget. Reactions have been initiated in 45-62 wt% H2SO4 solutions at 10.0 C. Methyl nitrate production rates increased exponentially with acidity within the acidity regime studied. Preliminary calculations suggest that the nitronium ion (NO2(+) is the active nitrating agent under these conditions. The reaction order in methanol appears to depend on the water/methanol ratio and varies from first to zeroth order under conditions investigated. The nitration is first order in nitronium at all acidities investigated. A second order rate constant, kappa(sub 2), has been calculated to be 1 x 10(exp 8)/ M s when the reaction is first order in methanol. Calculations suggest the nitration is first order in methanol under tropospheric conditions. The infinitesimal percentage of nitric acid in the nitronium ion form in this acidity regime probably makes this reaction insignificant for the upper troposphere; however, this nitration may become significant in the mid stratosphere where colder temperatures increase nitric acid solubility and higher sulfuric acid content shifts nitric acid speciation toward the nitronium ion.

  14. Acid-catalyzed Furfuryl Alcohol Polymerization: Characterizations of Molecular Structure and Thermodynamic Properties

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Taejin; Assary, Rajeev A; Marshall, Christopher L; Gosztola, David J.; Curtiss, Larry A; Stair, Peter C


    The liquid-phase polymerization of furfuryl alcohol catalyzed by sulfuric acid catalysts and the identities of molecular intermediates were investigated by using Raman spectroscopy and density functional theory calculation. At room temperature, with an acid catalyst, a vigorous furfuryl alcohol polymerization reaction was observed, whereas even at a high water concentration, furfuryl alcohol was very stable in the absence of an acid catalyst. Theoretical studies were carried out to investigate the thermodynamics of protonation of furfuryl alcohol, initiation of polymerization, and formation of conjugated dienes and diketonic species by using the B3LYP level of theory. A strong aliphatic C=C band observed in the calculated and measured Raman spectra provided crucial evidence to understand the polymerization reaction mechanism. It is confirmed that the formation of a conjugated diene structure rather than a diketone structure is involved in the furfuryl alcohol polymerization reaction.

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

    Directory of Open Access Journals (Sweden)

    Abdalrahman B. Fadhil


    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.

  16. Hydrodeoxygenation of fatty acid esters catalyzed by Ni on nano-sized MFI type zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Schreiber, Moritz W.; Rodriguez-Niño, Daniella; Gutiérrez, Oliver Y.; Lercher, Johannes A.


    The impact of support morphology and composition on the intrinsic activity of Ni supported on MFI-type zeolite was explored in the hydrodeoxygenation of methyl stearate, tristearate, and algae oil (mixture of triglycerides). The nano-sized structure of the support (self-pillared nanosheets) is beneficial for the activity of the catalysts. Higher Ni dispersion and concomitant higher reaction rates were obtained on nano-structured supports than on zeolite with conventional morphology. Rates normalized to accessible Ni atoms (TOF), however, varied little with support morphology. Acidity of the support increases the rate of Ni-catalyzed C-O hydrogenolysis per surface metal site.

  17. Cobalt(II)-catalyzed 1,4-addition of organoboronic acids to activated alkenes: an application to highly cis-stereoselective synthesis of aminoindane carboxylic acid derivatives. (United States)

    Chen, Min-Hsien; Mannathan, Subramaniyan; Lin, Pao-Shun; Cheng, Chien-Hong


    It all adds up: The 1,4-addition of organoboronic acids to activated alkenes catalyzed by [Co(dppe)Cl(2)] is described. A [3+2]-annulation reaction of ortho-iminoarylboronic acids with acrylates to give various aminoindane carboxylic acid derivatives with cis-stereoselectivity is also demonstrated (see scheme; dppe = 1,2-bis(diphenylphosphino)ethane).

  18. Role of apparent pKa of carboxylic acids in lipase-catalyzed esterifications in biphasic systems

    NARCIS (Netherlands)

    Dominguez de Maria, Pablo; Fernandez-Alvaro, Elena; Kate, ten Antoon; Bargeman, Gerrald


    Lipase-catalyzed esterifications in biphasic media (heptane–water, 1:1) were conducted by using Thermomyces lanuginosus lipase (TLL) as biocatalyst. Different carboxylic acids (from acetic to lauric) were thus esterified with 1-butanol at different pH values (2–10). For all carboxylic acids tested,

  19. 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)


    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.

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

    DEFF Research Database (Denmark)

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


    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...

  1. Iron-catalyzed photochemical transformation of benzoic acid in atmospheric liquids: Product identification and reaction mechanisms (United States)

    Deng, Yiwei; Zhang, Kai; Chen, Hao; Wu, Taixing; Krzyaniak, Metthew; Wellons, Amina; Bolla, Dawn; Douglas, Kenneth; Zuo, Yuegang

    This study investigated iron-catalyzed photochemical oxidation of benzoic acid (BA), one of the major photodegradation products of petroleum hydrocarbons, under sunlight or monochromatic light irradiation in a wavelength range of 254-419 nm. The photochemical degradation of BA in the absence of iron (III) occurred at irradiation wavelengths below 300 nm. The photochemical transformation of BA in the presence Fe(III) was observed at both 254, 350, 419 nm and under solar irradiation. The half-life for the photodegradation of BA (100 μM) was 160±20 min in the presence of 20 μM Fe(III) at pH 3.20 on sunny August days at noon time. The degradation rate increased with increasing concentration of Fe(III). The reaction products were separated and identified using capillary electrophoresis (CE), gas chromatography/mass spectrometry (GC/MS) and UV-Visible spectrophotometry. The major reaction products were 2-hydroxybenzoic, 3-hydroxybenzoic and 4-hydroxybenzoic acids. Hydrogen peroxide (H 2O 2) and Fe(II) species were also formed during the photochemical reactions. The proposed reaction mechanisms include the photoexcitation of Fe(III) hydroxide complexes to form Fe(II) ions and hydroxyl radicals (OH rad ) that attack ortho, meta and para positions of BA to form corresponding monohydroxybenzoic acids and H 2O 2. The monohydroxybenzoic acids formed further react with hydroxyl and surperoxide radicals (HO 2- rad /O 2- rad ) to yield dihydroxybenzoic acids in atmospheric water droplets.

  2. Mechanism of arylboronic acid-catalyzed amidation reaction between carboxylic acids and amines. (United States)

    Wang, Chen; Yu, Hai-Zhu; Fu, Yao; Guo, Qing-Xiang


    Arylboronic acids were found to be efficient catalysts for the amidation reactions between carboxylic acids and amines. Theoretical calculations have been carried out to investigate the mechanism of this catalytic process. It is found that the formation of the acyloxyboronic acid intermediates from the carboxylic acid and the arylboronic acid is kinetically facile but thermodynamically unfavorable. Removal of water (as experimentally accomplished by using molecular sieves) is therefore essential for overall transformation. Subsequently C-N bond formation between the acyloxyboronic acid intermediates and the amine occurs readily to generate the desired amide product. The cleavage of the C-O bond of the tetracoordinate acyl boronate intermediates is the rate-determining step in this process. Our analysis indicates that the mono(acyloxy)boronic acid is the key intermediate. The high catalytic activity of ortho-iodophenylboronic acid is attributed to the steric effect as well as the orbital interaction between the iodine atom and the boron atom.

  3. Palladium-atom catalyzed formic acid decomposition and the switch of reaction mechanism with temperature. (United States)

    He, Nan; Li, Zhen Hua


    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.

  4. Application of acid-catalyzed hydrolysis of dispersed organic solvent in developing new microencapsulation process technology. (United States)

    Lee, Honghwa; Lee, Sunhwa; Bhattacharjee, Himanshu; Sah, Hongkee


    The aim of this study was to evaluate a new microencapsulation technology employing an acid-catalyzed solvent extraction method in conjunction to an emulsion-based microencapsulation process. Its process consisted of emulsifying a dispersed phase of poly(D,L-lactide-co-glycolide) and isopropyl formate in an aqueous phase. This step was followed by adding hydrochloric acid to the resulting oil-in-water emulsion, in order to initiate the hydrolysis of isopropyl formate dissolved in the aqueous phase. Its hydrolysis caused the liberation of water-soluble species, that is, isopropanol and formic acid. This event triggered continual solvent leaching out of emulsion droplets, thereby initiating microsphere solidification. This new processing worked well for encapsulation of progesterone and ketoprofen that were chosen as a nonionizable model drug and a weakly acidic one, respectively. Furthermore, the structural integrity of poly(D,L-lactide-co-glycolide) was retained during microencapsulation. The new microencapsulation technology, being conceptually different from previous approaches, might be useful in preparing various polymeric particles.

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

    Wang, Yang; Ren, Wenlong; Shi, Yian


    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.

  6. 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; de Wildeman, Stefaan; Feringa, B.L.; B. Janssen, Dick


    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

  7. Regioselective, borinic acid-catalyzed monoacylation, sulfonylation and alkylation of diols and carbohydrates: expansion of substrate scope and mechanistic studies. (United States)

    Lee, Doris; Williamson, Caitlin L; Chan, Lina; Taylor, Mark S


    Synthetic and mechanistic aspects of the diarylborinic acid-catalyzed regioselective monofunctionalization of 1,2- and 1,3-diols are presented. Diarylborinic acid catalysis is shown to be an efficient and general method for monotosylation of pyranoside derivatives bearing three secondary hydroxyl groups (7 examples, 88% average yield). In addition, the scope of the selective acylation, sulfonylation, and alkylation is extended to 1,2- and 1,3-diols not derived from carbohydrates (28 examples); the efficiency, generality, and operational simplicity of this method are competitive with those of state-of-the-art protocols including the broadly applied organotin-catalyzed or -mediated reactions. Mechanistic details of the organoboron-catalyzed processes are explored using competition experiments, kinetics, and catalyst structure-activity relationships. These experiments are consistent with a mechanism in which a tetracoordinate borinate complex reacts with the electrophilic species in the turnover-limiting step of the catalytic cycle.

  8. 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


    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.

  9. 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)


    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.

  10. Kinetics of Acid-Catalyzed Dehydration of Cyclic Hemiacetals in Organic Aerosol Particles in Equilibrium with Nitric Acid Vapor. (United States)

    Ranney, April P; Ziemann, Paul J


    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.

  11. Lipase catalyzed synthesis of organic acid esters of lactic acid in non-aqueous media. (United States)

    Kiran, K R; Divakar, S


    Lipases from Rhizomucor miehei (Lipozyme IM20) and porcine pancreas (PPL) were employed as catalysts for the esterification reaction between the hydroxyl group of lactic acid and the carboxyl group of organic acids. Reactions were carried out at both shake-flask and bench-scale levels. Various parameters, such as solvent, temperature, substrate and enzyme concentrations, effect of buffer volume, buffer pH and water volume, were investigated for optimization of yields. While ethylmethyl ketone (EMK) was found to be the best solvent for shake-flask reactions, chloroform gave higher yields at bench-scale level. Detailed studies were carried out with respect to the synthesis of palmitoyl and stearoyl lactic acids. At shake-flask level, maximum yields of 37.5 and 40% were observed in case of palmitoyl and stearoyl lactic acids, respectively, with Lipozyme IM20; at bench-scale level, the maximum yields were 85.1 and 99% respectively, when PPL was employed. Of all the organic acids employed (C(2)--C(18)), only lauric, palmitic and stearic acids gave yields above 50%. At bench-scale level, PPL could be reused for up to three cycles with yields above 40%. Esters prepared were found to conform to Food Chemical Codex (FCC) specifications in terms of acid value, ester value, sodium and lactic acid contents.

  12. Laccase-catalyzed modification of PES membranes with 4-hydroxybenzoic acid and gallic acid

    NARCIS (Netherlands)

    Nady, N.; Schroën, C.G.P.H.; Franssen, M.C.R.; Mohy Eldin, M.S.; Zuilhof, H.; Boom, R.M.


    We here report on the performance of poly(ethersulfone) membranes modified with 4-hydroxybenzoic acid and gallic acid as substrates, and using laccase as biocatalyst under several modification conditions. The average flux of the base membrane was never reduced more than 20% (mostly below 10% reducti

  13. Mechanistic Investigation of Acid-Catalyzed Cleavage of Aryl-Ether Linkages: Implications for Lignin Depolymerization

    Energy Technology Data Exchange (ETDEWEB)

    Sturgeon, M. R.; Kim, S.; Chmely, S. C.; Foust, T. D.; Beckham, G. T.


    Carbon-oxygen bonds are the primary inter-monomer linkages lignin polymers in plant cell walls, and as such, catalyst development to cleave these linkages is of paramount importance to deconstruct biomass to its constituent monomers for the production of renewable fuels and chemicals. For many decades, acid catalysis has been used to depolymerize lignin. Lignin is a primary component of plant cell walls, which is connected primarily by aryl-ether linkages, and the mechanism of its deconstruction by acid is not well understood, likely due to its heterogeneous and complex nature compared to cellulose. For effective biomass conversion strategies, utilization of lignin is of significant relevance and as such understanding the mechanisms of catalytic lignin deconstruction to constituent monomers and oligomers is of keen interest. Here, we present a comprehensive experimental and theoretical study of the acid catalysis of a range of dimeric species exhibiting the b-O-4 linkage, the most common inter-monomer linkage in lignin. We demonstrate that the presence of a phenolic species dramatically increases the rate of cleavage in acid at 150 degrees C. Quantum mechanical calculations on dimers with the para-hydroxyl group demonstrate that this acid-catalyzed pathway differs from the nonphenolic dimmers. Importantly, this result implies that depolymerization of native lignin in the plant cell wall will proceed via an unzipping mechanism wherein b-O-4 linkages will be cleaved from the ends of the branched, polymer chains inwards toward the center of the polymer. To test this hypothesis further, we synthesized a homopolymer of b-O-4 with a phenolic hydroxyl group, and demonstrate that it is cleaved in acid from the end containing the phenolic hydroxyl group. This result suggests that genetic modifications to lignin biosynthesis pathways in plants that will enable lower severity processes to fractionate lignin for upgrading and for easier access to the carbohydrate fraction of


    Institute of Scientific and Technical Information of China (English)

    陶敬奇; 李景宁; 王广洪; 曾广益


    The Polysuccinimide is Synthesized by means of pyrocondensation catalyze polymerization,using L-aspartic acid as a monomer.Poly-aspartic Acid is achieved by hydrolization of Polysuccinimide.The effect of temperature,time,catalyzer and condition of hydrolization on yield and quality is studied.The research results show that the method has the advantages of simple equipment and high yield.

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

    Directory of Open Access Journals (Sweden)

    R.C. Ehiri


    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.

  16. 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


    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.

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

    Directory of Open Access Journals (Sweden)

    Momoko Watanabe


    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.

  18. Lipase-catalyzed process in an anhydrous medium with enzyme reutilization to produce biodiesel with low acid value. (United States)

    Azócar, Laura; Ciudad, Gustavo; Heipieper, Hermann J; Muñoz, Robinson; Navia, Rodrigo


    One major problem in the lipase-catalyzed production of biodiesel or fatty acid methyl esters (FAME) is the high acidity of the product, mainly caused by water presence, which produces parallel hydrolysis and esterification reactions instead of transesterification to FAME. Therefore, the use of reaction medium in absence of water (anhydrous medium) was investigated in a lipase-catalyzed process to improve FAME yield and final product quality. FAME production catalyzed by Novozym 435 was carried out using waste frying oil (WFO) as raw material, methanol as acyl acceptor, and 3Å molecular sieves to extract the water. The anhydrous conditions allowed the esterification of free fatty acids (FFA) from feedstock at the initial reaction time. However, after the initial esterification process, water absence avoided the consecutives reactions of hydrolysis and esterification, producing FAME mainly by transesterification. Using this anhydrous medium, a decreasing in both the acid value and the diglycerides content in the product were observed, simultaneously improving FAME yield. Enzyme reuse in the anhydrous medium was also studied. The use of the moderate polar solvent tert-butanol as a co-solvent led to a stable catalysis using Novozym 435 even after 17 successive cycles of FAME production under anhydrous conditions. These results indicate that a lipase-catalyzed process in an anhydrous medium coupled with enzyme reuse would be suitable for biodiesel production, promoting the use of oils of different origin as raw materials.

  19. (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


    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).

  20. Ru/Me-BIPAM-catalyzed asymmetric addition of arylboronic acids to aliphatic aldehydes and α-ketoesters. (United States)

    Yamamoto, Yasunori; Shirai, Tomohiko; Watanabe, Momoko; Kurihara, Kazunori; Miyaura, Norio


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

  1. Kinetic studies on the Rhizomucor miehei lipase catalyzed esterification reaction of oleic acid with 1-butanol in a biphasic system

    NARCIS (Netherlands)

    Kraai, G.N.; Winkelman, J.G.M.; de Vries, Johannes; Heeres, H.J.


    The kinetics of the esterification of oleic acid with 1 -butanol catalyzed by free Rhizomucor miehei lipase in a biphasic system was studied in a batch reactor. The reaction appeared to proceed via a Ping Pong bi-bi mechanism with I -butanol inhibition. The kinetic constants of the model were determ

  2. Pilot-scale study on the acid-catalyzed steam explosion of rice straw using a continuous pretreatment system. (United States)

    Chen, Wen-Hua; Tsai, Chia-Chin; Lin, Chih-Feng; Tsai, Pei-Yuan; Hwang, Wen-Song


    A continuous acid-catalyzed steam explosion pretreatment process and system to produce cellulosic ethanol was developed at the pilot-scale. The effects of the following parameters on the pretreatment efficiency of rice straw feedstocks were investigated: the acid concentration, the reaction temperature, the residence time, the feedstock size, the explosion pressure and the screw speed. The optimal presteaming horizontal reactor conditions for the pretreatment process are as follows: 1.7 rpm and 100-110 °C with an acid concentration of 1.3% (w/w). An acid-catalyzed steam explosion is then performed in the vertical reactor at 185 °C for 2 min. Approximately 73% of the total saccharification yield was obtained after the rice straw was pretreated under optimal conditions and subsequent enzymatic hydrolysis at a combined severity factor of 0.4-0.7. Moreover, good long-term stability and durability of the pretreatment system under continuous operation was observed.

  3. Potential of phosphoric acid-catalyzed pretreatment and subsequent enzymatic hydrolysis for biosugar production from Gracilaria verrucosa. (United States)

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


    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.

  4. Inhibition of Homo-coupling of Arylboronic Acids in Ligand Free Pd(Ⅱ)-Catalyzed Suzuki Reaction

    Institute of Scientific and Technical Information of China (English)

    TAO,Xiao-Chun; ZHANG,Yue-Ping; HE,Tian-Xiong; SHEN,Dong


    A series of solvents were examined for the ligand free Pd(Ⅱ)-catalyzed Suzuki reaction of 4-bromotoluene with phenylboronic acid. It was found that the PdCl2/i-PrOH system could efficiently inhibit the homo-coupling of phenylboronic acid and give a cross-coupling product in high yields. The substrates with a wide variety of functional groups were tolerated in the system. A possible mechanism for this system was proposed.

  5. Rh(III)-catalyzed decarboxylative ortho-heteroarylation of aromatic carboxylic acids by using the carboxylic acid as a traceless directing group. (United States)

    Qin, Xurong; Sun, Denan; You, Qiulin; Cheng, Yangyang; Lan, Jingbo; You, Jingsong


    Highly selective decarboxylative ortho-heteroarylation of aromatic carboxylic acids with various heteroarenes has been developed through Rh(III)-catalyzed two-fold C-H activation, which exhibits a wide substrate scope of both aromatic carboxylic acids and heteroarenes. The use of naturally occurring carboxylic acid as the directing group avoids troublesome extra steps for installation and removal of an external directing group.

  6. 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;


    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 de...

  7. Glycolic Acid-Catalyzed Deamidation of Asparagine Residues in Degrading PLGA Matrices: A Computational Study

    Directory of Open Access Journals (Sweden)

    Noriyoshi Manabe


    Full Text Available 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.

  8. Glycolic acid-catalyzed deamidation of asparagine residues in degrading PLGA matrices: a computational study. (United States)

    Manabe, Noriyoshi; Kirikoshi, Ryota; Takahashi, Ohgi


    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.

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

    Directory of Open Access Journals (Sweden)

    Amrit P. Toor


    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: || or local: ] | View in  

  10. 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


    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.

  11. Disproportionation Kinetics of Hypoiodous Acid As Catalyzed and Suppressed by Acetic Acid-Acetate Buffer. (United States)

    Urbansky, Edward T.; Cooper, Brian T.; Margerum, Dale W.


    The kinetics of the disproportionation of hypoiodous acid to give iodine and iodate ion (5HOI right harpoon over left harpoon 2I(2) + IO(3)(-) + H(+) + 2H(2)O) are investigated in aqueous acetic acid-sodium acetate buffer. The rate of iodine formation is followed photometrically at -log [H(+)] = 3.50, 4.00, 4.50, and 5.00, &mgr; = 0.50 M (NaClO(4)), and 25.0 degrees C. Both catalytic and inhibitory buffer effects are observed. The first process is proposed to be a disproportionation of iodine(I) to give HOIO and I(-); the iodide then reacts with HOI to give I(2). The reactive species (acetato-O)iodine(I), CH(3)CO(2)I, is postulated to increase the rate by assisting in the formation of I(2)O, a steady-state species that hydrolyzes to give HOIO and I(2). Inhibition is postulated to result from the formation of the stable ion bis(acetato-O)iodate(I), (CH(3)CO(2))(2)I(-), as buffer concentration is increased. This species is observed spectrophotometrically with a UV absorption shoulder (lambda = 266 nm; epsilon = 530 M(-)(1) cm(-)(1)). The second process is proposed to be a disproportionation of HOIO to give IO(3)(-) and I(2). Above 1 M total buffer, the reaction becomes reversible with less than 90% I(2) formation. Rate and equilibrium constants are resolved and reported for the proposed mechanism.

  12. Oxygenase-Catalyzed Desymmetrization of N,N-Dialkyl-piperidine-4-carboxylic Acids** (United States)

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


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

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

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


    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.

  14. Drosophila melanogaster CYP6A8, an insect P450 that catalyzes lauric acid (omega-1)-hydroxylation. (United States)

    Helvig, Christian; Tijet, Nathalie; Feyereisen, René; Walker, F Ann; Restifo, Linda L


    Only a handful of P450 genes have been functionally characterized from the approximately 90 recently identified in the genome of Drosophila melanogaster. Cyp6a8 encodes a 506-amino acid protein with 53.6% amino acid identity with CYP6A2. CYP6A2 has been shown to catalyze the metabolism of several insecticides including aldrin and heptachlor. CYP6A8 is expressed at many developmental stages as well as in adult life. CYP6A8 was produced in Saccharomyces cerevisiae and enzymatically characterized after catalytic activity was reconstituted with D. melanogaster P450 reductase and NADPH. Although several saturated or non-saturated fatty acids were not metabolized by CYP6A8, lauric acid (C12:0), a short-chain unsaturated fatty acid, was oxidized by CYP6A8 to produce 11-hydroxylauric acid with an apparent V(max) of 25 nmol/min/nmol P450. This is the first report showing that a member of the CYP6 family catalyzes the hydroxylation of lauric acid. Our data open new prospects for the CYP6 P450 enzymes, which could be involved in important physiological functions through fatty acid metabolism.

  15. Acetic Acid Catalyzed Steam Explosion for Improving the Sugar Recovery of Wheat Straw

    Directory of Open Access Journals (Sweden)

    Mengru Liu


    Full Text Available Acetic acid-catalyzed steam explosion pretreatment was applied to wheat straw at temperatures of 190 and 210 °C for 2, 6, and 10 min of residence time. The effects of pretreatment conditions on the total gravimetric recovery, hemicellulose sugars, glucose content, and yield of the enzymatic hydrolysis of cellulose were studied. The results indicated that the total gravimetric recovery decreases while the solubility of hemicellulose and the yield of cellulose enzymatic hydrolysis increase as the pretreatment severity increases. Pretreatment at 190 °C with a 2-min residence time resulted in the highest total gravimetric recovery, 58.9%. The optimum defiberation, glucose content, and enzymatic hydrolysis yields of 70.4 and 79.6%, respectively, occurred following pretreatment at 210 °C with a 10-min residence time. The optimal pretreatment condition was determined to be 190 °C for 10 min. Under the optimum conditions, the recovery yield of all sugars reached 42.7%. This pretreatment resulted in the highest recovery yield of all sugars.

  16. Synthesis of deuterium-labeled imipramine using acid-catalyzed exchange reaction

    Energy Technology Data Exchange (ETDEWEB)

    Baba, S.; Furuta, T.; Sasaki, Y.; Kasuya, Y. (Tokyo Coll. of Pharmacy (Japan))


    Synthesis of three forms of selectively deuterated imipramine with high isotopic purity using acid catalyzed hydrogen-deuterium exchange reaction is described. Deuterated imipramine labeled at the positions of 2,4,6 and 8 (IP-d/sub 4/(I)) was prepared directly by heating imipramine in 10% DC1-D/sub 2/O at 80/sup 0/ for 8hr. Imipramine labeled at all of the eight aromatic positions (IP-d/sub 8/) was synthesized from iminodibenzyl-1,2,3,4,6,7,8,9-d/sub 8/ which was prepared by treating iminodibenzyl (IDB) in 37% DC1-D/sub 2/O at 160/sup 0/ for 24hr. An imipramine labeled at the positions of 1,3,7 and 9 (IP-d/sub 4/(II)) was obtained by ''back-exchange'' of IP-d/sub 8/ under the protio condition according to the exchange procedure of IP-d/sub 4/(I).

  17. Oligomerization of 10,16-Dihydroxyhexadecanoic Acid and Methyl 10,16-Dihydroxyhexadecanoate Catalyzed by Lipases

    Directory of Open Access Journals (Sweden)

    Daniel Arrieta-Baez


    Full Text Available The main monomer of tomato cuticle, 10,16-dihydroxyhexadecanoic acid (10,16-DHPA and its methyl ester derivative (methyl-10,16-dihydroxyhexadecanote; methyl-10,16-DHHD, were used to study their oligomerization reactions catalyzed by five lipases: Candida antarctica lipase B (CAL-B, Rhizomucor miehei lipase (RM, Thermomyces lanuginosus lipase (TL, Pseudomonas cepacia lipase (PCL and porcine pancreatic lipase (PPL. For 10,16-DHPA, optimum yields were obtained at 60 °C using toluene and 2-methyl-2-butanol (2M2B as solvent, while for methyl-10,16-DHHD the bests yields were obtained in toluene and acetonitrile. Both reactions leaded to linear polyesters according to the NMR and FT-IR analysis, and there was no data indicating the presence of branched polymers. Using optimized conditions, poly(10,16-DHPA and poly(methyl-10,16-DHHD with Mw = 814 and Mn = 1,206 Da, and Mw = 982 and Mn = 860 Da, respectively, were formed according to their MALDI-TOF MS and ESI-MS data. The self-assembly of the polyesters obtained were analyzed by AFM.

  18. Synthesis of 24-phenyl-24-oxo steroids derived from bile acids by palladium-catalyzed cross coupling with phenylboronic acid. NMR characterization and X-ray structures. (United States)

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


    Palladium-catalyzed cross coupling of phenyboronic acid with acetylated bile acids in which the carboxyl functions have been activated by formation of a mixed anhydride with pivalic anhydride afforded moderate to good yield of 24-phenyl-24-oxo-steroids. Unambiguous assignments of the NMR signals were made with the aid of combined 1D and 2D NMR techniques. X-ray diffraction studies confirmed the obtained structures.

  19. Kinetically controlled synthesis of monoglyceryl esters from chiral and prochiral acids methyl esters catalyzed by immobilized Rhizomucor miehei lipase. (United States)

    Acosta, Andreina; Filice, Marco; Fernandez-Lorente, Gloria; Palomo, Jose M; Guisan, Jose M


    Partial acylation of only one primary hydroxyl group of glycerol generates a chiral center at position 2. Rhizomucor miehei lipase (RML) catalyzes the kinetically controlled transesterification of different aromatic carboxylic acids methyl esters with glycerol. High synthetic yields of glyceryl esters (around 70-80%) were obtained even in the presence of significant concentrations of water (from 5% to 20%). After a long incubation of the reaction mixture in the presence of the biocatalyst only pure free acid was obtained. Other lipases (from Geobacillus thermocatenulatus and from Thermomyces lanuginose) also catalyzed similar kinetically controlled transesterifications although less efficiently. RML immobilized on Sepharose-Q showed a high activity and specificity, compared to the immobilization by other techniques, only producing monoglyceryl esters with all substrates. In particular, monoglyceryl-phenylmalonate product was synthesized in 82% overall yield and >99% diastereomeric excess at pH 7.0 and 37°C and 90% glycerol.

  20. Stereocontrol in proline-catalyzed asymmetric amination: a comparative assessment of the role of enamine carboxylic acid and enamine carboxylate. (United States)

    Sharma, Akhilesh K; Sunoj, Raghavan B


    The transition state models in two mechanistically distinct pathways, involving (i) an enamine carboxylic acid (path-A, 4) and (ii) an enamine carboxylate (path-B, 8), in the proline-catalyzed asymmetric α-amination have been examined using DFT methods. The path-A predicts the correct product stereochemistry under base-free conditions while path-B accounts for reversal of configuration in the presence of a base.

  1. 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)


    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.

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

    KAUST Repository

    Quitterer, Felix


    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.

  3. DFT Mechanistic Study of Rh(III)-Catalyzed [3 + 2]/[5 + 2] Annulation of 4-Aryl-1,2,3-triazoles and Alkynes Unveils the Dual C-H Activation Strategy. (United States)

    Zhang, Zhongchao; Yang, Shengwen; Li, Juan; Liao, Xiaojian


    Li and co-workers recently developed a dual C-H bond activation strategy, using a Rh(III) catalyst, for [3 + 2]/[5 + 2] annulation of primary 4-aryl-1,2,3-triazoles and alkynes. The Rh(III)-catalyzed dual annulation of 4-aryl-1,2,3-triazoles and alkynes is challenging because only single annulation is achieved using Rh(II) and Ni(0) catalysts. Intrigued by the novel strategy, we performed a density functional theory study to unravel this challenging dual C-H bond activation. A Friedel-Crafts type mechanism proved be more favorable than a concerted metalation-deprotonation (CMD) mechanism for the first C-H bond activation. The second C-H bond activation proceeded via a CMD mechanism. More importantly, the calculation explained why only AgSbF6, among several candidates, performed perfectly, whereas others failed, and why the dual annulation of 4-aryl-1,2,3-triazoles with alkynes was achieved with a Rh(III) catalyst but not with Rh(II) and Ni(0) catalysts. Due to the active catalyst being [Cp*Rh(OAc)](+), AgSbF6, in which SbF6(-) is a stable anion, among several candidates performed perfectly. The success of the Rh(III)-catalyzed dual C-H bond activation has two origins: (i) the active catalyst [Cp*Rh(OAc)](+) is more stable than Cp*Rh(OAc)2 when the Ag salt is AgSbF6, and this facilitates the first alkyne insertion; and (ii) a rhodium-carbene is easily formed.

  4. 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


    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.

  5. Studies of Grafted and Sulfonated Spiro Poly(isatin-ethersulfone Membranes by Super Acid-Catalyzed Reaction

    Directory of Open Access Journals (Sweden)

    Lei Jin


    Full Text Available Spiro poly(isatin-ethersulfone polymers were prepared from isatin and bis-2,6-dimethylphenoxyphenylsulfone by super acid catalyzed polyhydroxyalkylation reactions. We designed and synthesized bis-2,6-dimethylphenoxyphenylsulfone, which is structured at the meta position steric hindrance by two methyl groups, because this structure minimized crosslinking reaction during super acid catalyzed polymerization. In addition, sulfonic acid groups were structured in both side chains and main chains to form better polymer chain morphology and improve proton conductivity. The sulfonation reactions were performed in two steps which are: in 3-bromo-1-propanesulfonic acid potassium salt and in con. sulfuric acid. The membrane morphology was studied by tapping mode atomic force microscope (AFM. The phase difference between the hydrophobic polymer main chain and hydrophilic sulfonated units of the polymer was shown to be the reasonable result of the well phase separated structure. The correlations of proton conductivity, ion exchange capacity (IEC and single cell performance were clearly described with the membrane morphology.

  6. Production of high-oleic acid tallow fractions using lipase-catalyzed directed interesterification, using both batch and continuous processing. (United States)

    MacKenzie; Stevenson


    Immobilized lipases were used to catalyze batch-directed interesterification of tallow, resulting in oleins containing significantly higher levels of unsaturated fatty acids than obtained by fractionation without lipase. After 14 days, a reaction catalyzed by 2% Novozym 435 yielded 57% olein unsaturation, compared with 45% in a no-enzyme control. Free fatty acid levels increased to 2-3% during reactions. Incubation of the enzyme in multiple batches of melted fat caused a gradual loss of interesterification activity, apparently due to progressive dehydration. The activity could be restored by addition of water to the reaction medium. Immobilized lipase was also used to catalyze directed interesterification in a continuous flow reactor. Melted tallow was circulated through a packed bed enzyme reactor and a separate crystallization vessel. The temperatures of the two parts of the apparatus were controlled separately to allow crystallization to occur separately from interesterification. Operation of the reactor with conventionally dry, prefractionated tallow allowed the formation of an olein consisting of up to 60% unsaturated fatty acids. The greatest changes in olein fatty acid composition were achieved when the fractionation temperature was kept constant at a value that promoted selective crystallization of trisaturated triglycerides that were continuously produced by enzymic interesterification. The enzyme could be reused without apparent loss of activity, and its activity was apparently enhanced by preincubation in melted tallow for up to several days. Control of both the water activity of the enzyme and tallow feedstock and of the absorption of atmospheric water vapor were required to maintain enzyme activity, during multiple reuse and minimize free fatty acid formation. This method may form the basis for a process to produce highly mono-unsaturated tallow fractions for use in food applications (e.g. frying) where a "healthy" low saturated fat product is required.

  7. 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


    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.

  8. Synthesis, characterization and adsorption properties of diethylenetriamine-modified hypercrosslinked resins for efficient removal of salicylic acid from aqueous solution. (United States)

    Huang, Jianhan; Jin, Xiaoying; Mao, Jinglin; Yuan, Bin; Deng, Rujie; Deng, Shuguang


    We report an effective approach for tailoring the pore textural properties and surface polarity of a hypercrosslinked resin to enhance its adsorption capacity and selectivity for removing salicylic acid from aqueous solution. Four hypercrosslinked resins were synthesized by controlling the reaction time of the self Friedel-Crafts reaction of chloromethylated polystyrene-co-divinylbenzene, and then modified with diethylenetriamine to adjust their surface polarity. The resins were characterized with N(2) adsorption for pore textural properties, Fourier transform infrared spectroscopy (FT-IR) for surface functional groups, chemical analysis for residual chlorine content and weak basic exchange capacity. Adsorption equilibrium, kinetics and breakthrough performance were determined for the removal of salicylic acid from aqueous solution on a selected resin HJ-M01. The equilibrium adsorption capacity of salicylic acid on HJ-M01 is significantly higher than that on its precursor HJ-11 and a few commercial adsorbents including AB-8, XAD-4 and XAD-7. The dynamic adsorption capacity of salicylic acid on HJ-M01 was found to be 456.4 mg/L at a feed concentration of 1000 mg/L and 294 K. The used resin could be fully regenerated with 1% sodium hydroxide solution. The hypercrosslinked resins being developed were promising alternatives to commercial adsorbents for removing salicylic acid and other volatile organic compounds (VOCs) from aqueous solution.

  9. Lipase-catalyzed acidolysis of canola oil with caprylic acid to produce medium-, long- and medium-chain-type structured lipids

    DEFF Research Database (Denmark)

    Wang, Yingyao; Xia, Luan; Xu, Xuebing


    Lipase-catalyzed acidolysis of canola oil with caprylic acid was performed to produce structured lipids (SLs) containing medium-chain fatty acid (M) at position sn-1,3 and long-chain fatty acid (L) at the sn-2 position in a solvent-free system. Six commercial lipases from different sources were s...

  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;


    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. Microwave-assisted chemoselective copper-catalyzed amination of o-chloro and o-bromobenzoic acids using aromatic amines under solvent free conditions

    Institute of Scientific and Technical Information of China (English)

    Yaghoub Sarrafi; Manijeh Mohadeszadeh; Kamal Alimohammadi


    Copper-catalyzed synthesis of N-aryl anthranilic acid derivatives using effective amination of 2-chloro and 2-bromobenzoic acid under microwave irradiation is reported. Some of the advantages of this method axe high chemoselectivity, short reaction times, ease of work up procedure and elimination of the need for acid protection.

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


    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.

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

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


    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.

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

  15. β-Amino acid catalyzed asymmetric Michael additions: design of organocatalysts with catalytic acid/base dyad inspired by serine proteases. (United States)

    Yang, Hui; Wong, Ming Wah


    A new type of chiral β-amino acid catalyst has been computationally designed, mimicking the enzyme catalysis of serine proteases. Our catalyst approach is based on the bioinspired catalytic acid/base dyad, namely, a carboxyl and imidazole pair. DFT calculations predict that this designed organocatalyst catalyzes Michael additions of aldehydes to nitroalkenes with excellent enantioselectivities and remarkably high anti diastereoselectivities. The unusual stacked geometry of the enamine intermediate, hydrogen bonding network, and the adoption of an exo transition state are the keys to understand the stereoselectivity.

  16. Microwave-Assisted Synthesis of Chiral β-Amino Acids%微波辅助法合成手性β-氨基酸

    Institute of Scientific and Technical Information of China (English)

    刘发明; 冯柏年


    手性β-氨基酸是一类在药物开发和生物研究中具有广泛应用的中间体,尝试了以L-天冬氨酸为手性源合成手性β-氨基酸的研究,其合成方法:首先对天冬氨酸进行氨基保护,然后利用微波,高效地合成( S)-N-保护的丝氨酸-γ-内酯,最后通过傅克反应,合成具有芳香性的手性β氨基酸。具有路线短、操作方便、绿色经济等优点,适合工业化大生产。%Chiral β-amino acids were intermediates , having a wide range of applications in biological research and drug development.Trying to use L-aspartic acid as chiral pool to synthesis β-amino acids , the synthesis method was that protecting the amino group of aspartic acid , then the microwave efficiently synthesized ( S ) -N -protected homoserine γ-lactone , and aromatic chiral βamino acids through Friedel -Crafts reaction was obtained , which had the characteristics of a line short , easy to operate , green economy , suitable for industrial production , etc.

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

    Institute of Scientific and Technical Information of China (English)

    程柯; 范甜甜; 孙健


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

  18. [Analysis of fatty acids in Gmnocypris przewalskii oil by gas chromatography/mass spectrometry with base-catalyzed transesterification]. (United States)

    Bo, Haibo; Wang, Xia; Zhai, Zongde; Li, Yongmin; Chen, Liren


    The composition of fatty acids (FA) in Gymnocypris przewalskii oil was identified and quantified by gas chromatography (GC)/electron impact (EI) mass spectrometry (MS). A base-catalyzed transesterification method was used to convert fatty acids to methyl esters. The lipids were extracted using petroleum ether and the total lipids in dried meat and skin of Gymnocypris przewalskii were about 25%. Forty-seven fatty acids were identified in the current study. Main types of fatty acids found in the oils were normal saturated, mono-branched, multi-branched, cyclopropane, furanoid, normal monounsaturated and polyunsaturated fatty acids. Saturated fatty acids were approximately 25. 7% of the total, and the main components were C(14:0) (3.4%), C(16:0) (19.4%) and C(18:0) (1.1%). Unsaturated fatty acids were totally 73.6%, and the major components of monounsaturated fatty acids were C(16:1 (9)) (19.8%), C(18:1) (9)) (18. 6%) and C(18:1 (11)) (7.3%); polyunsaturated fatty acids were mainly composed of C(18:2 (9,12)) (4.8%), C(18:3 (9, 12, 15)) (3.1%), C(20:4 (5, 8, 1, 14)) (1.2%), C(20:5 (5, 8, 11, 14, 17)) (EPA, 9.4%) and C(22:6 (4, 7, 10, 13, 16, 19)) (DHA, 6.7%). Especially, furyl-, cyclopropane- and several odd and branched chain fatty acids were found in Gymnocypris przewalskii oil. It is thus an important dietary resource of functional fatty acids.

  19. 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: [Department of Imaging System Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of)


    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.

  20. Vascular peroxidase 1 catalyzes the formation of hypohalous acids: characterization of its substrate specificity and enzymatic properties. (United States)

    Li, Hong; Cao, Zehong; Zhang, Guogang; Thannickal, Victor J; Cheng, Guangjie


    The heme-containing peroxidase family comprises eight members in humans. The physiological and pathophysiological roles of heme-containing peroxidases are not well understood. Phagocyte-derived myeloperoxidase (MPO) utilizes chloride and bromide, in the presence of hydrogen peroxide (H(2)O(2)), to generate hypochlorous acid and hypobromous acid, potent oxidizing species that are known to kill invading pathogens. Vascular peroxidase 1 (VPO1) is a new member of the heme-containing peroxidase family; VPO1 is highly expressed in the cardiovascular system, lung, liver, pancreas, and spleen. However, functional roles of VPO1 have not been defined. In this report, we demonstrate the capacity for VPO1 to catalyze the formation of hypohalous acids, and characterize its enzymatic properties. VPO1, like MPO but unlike lactoperoxidase, is able to generate hypochlorous acid, hypobromous acid, and hypothiocyanous acid in the presence of H(2)O(2). Under physiological pH and concentrations of halides (100μM KBr, 100μM KSCN, and 100mM NaCl), VPO1 utilizes approximately 45% of H(2)O(2) for the generation of hypobromous acid, 35% for hypothiocyanous acid, and 18% for hypochlorous acid. The specific activity of VPO1 is ∼10- to 70-fold lower than that of MPO, depending on the specific substrate. These studies demonstrate that the enzymatic properties and substrate specificity of VPO1 are similar to MPO; however, significantly lower catalytic rate constants of VPO1 relative to MPO suggest the possibility of other physiologic roles for this novel heme-containing peroxidase.

  1. Nafion-assisted cross-linking of sulfonated poly(arylene ether ketone) bearing carboxylic acid groups and their composite membranes for fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Haidan; Zhao, Chengji; Na, Hui [Alan G. MacDiarmid Institute, College of Chemistry, Jilin University, Qianjin street 2699, Changchun 130012, Jilin (China)


    In this study, a new type of cross-linked composite membrane is prepared and considered for its potential applications in direct methanol fuel cell. Nafion and sulfonated poly(arylene ether ketone) bearing carboxylic acid groups (SPAEK-C) are blended and subsequently cross-linked by a Friedel-Craft reaction using the carboxylic acid groups in the SPAEK-C to achieve lower methanol permeability. The perfluoroalkyl sulfonic acid groups of Nafion act as a benign solid catalyst, which assist the cross-linking of SPAEK-C. The physical and chemical characterizations of the cross-linked composite membranes are performed by varying the contents of SPAEK-C. The c-Nafion-15% membrane exhibits appropriate water uptake (10.49-25.22%), low methanol permeability (2.57 x 10{sup -7} cm{sup 2} s{sup -1}), and high proton conductivity (0.179 S cm{sup -1} at 80 C). DSC and FTIR analyze suggest the cross-linking reaction. These results show that the self-cross-linking of SPAEK-C in the Nafion membrane can effectively reduce methanol permeability while maintaining high proton conductivity. (author)

  2. Palladium-catalyzed difluoroalkylation of aryl boronic acids: a new method for the synthesis of aryldifluoromethylated phosphonates and carboxylic acid derivatives. (United States)

    Feng, Zhang; Min, Qiao-Qiao; Xiao, Yu-Lan; Zhang, Bo; Zhang, Xingang


    The palladium-catalyzed difluoroalkylation of aryl boronic acids with bromodifluoromethylphosphonate, bromodifluoroacetate, and further derivatives has been developed. This method provides a facile and useful access to a series of functionalized difluoromethylated arenes (ArCF2 PO(OEt)2 , ArCF2 CO2 Et, and ArCF2 CONR(1) R(2) ) that have important applications in drug discovery and development. Preliminary mechanistic studies reveal that a single electron transfer (SET) pathway may be involved in the catalytic cycle.

  3. Determination of DNA adducts by combining acid-catalyzed hydrolysis and chromatographic analysis of the carcinogen-modified nucleobases. (United States)

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


    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.

  4. Acid and Base Catalyzed Hydrolysis of Cyanophycin for the Biobased Production of Nitrogen Containing Chemicals

    NARCIS (Netherlands)

    Könst, P.M.; Scott, E.L.; Franssen, M.C.R.; Sanders, J.P.M.


    While growing on side-streams of the agro-industries, engineered microorganisms can produce ethanol and simultaneously bind L-aspartic acid and L-arginine in equimolar amounts in the polyamino acid cyanophycin. In this way, widely available amino acids can be isolated and utilized as an alternative

  5. 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


    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: || or local: ] | View in 

  6. Cloning and characterization of a new laccase from Bacillus licheniformis catalyzing dimerization of phenolic acids. (United States)

    Koschorreck, Katja; Richter, Sven M; Ene, Augusta B; Roduner, Emil; Schmid, Rolf D; Urlacher, Vlada B


    A new laccase gene (cotA) was cloned from Bacillus licheniformis and expressed in Escherichia coli. The recombinant protein CotA was purified and showed spectroscopic properties, typical for blue multi-copper oxidases. The enzyme has a molecular weight of approximately 65 kDa and demonstrates activity towards canonical laccase substrates 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), syringaldazine (SGZ) and 2,6-dimethoxyphenol (2,6-DMP). Kinetic constants KM and kcat for ABTS were of 6.5+/-0.2 microM and 83 s(-1), for SGZ of 4.3+/-0.2 microM and 100 s(-1), and for 2,6-DMP of 56.7+/-1.0 microM and 28 s(-1). Highest oxidizing activity towards ABTS was obtained at 85 degrees C. However, after 1 h incubation of CotA at 70 degrees C and 80 degrees C, a residual activity of 43% and 8%, respectively, was measured. Furthermore, oxidation of several phenolic acids and one non-phenolic acid by CotA was investigated. CotA failed to oxidize coumaric acid, cinnamic acid, and vanillic acid, while syringic acid was oxidized to 2,6-dimethoxy-1,4-benzoquinone. Additionally, dimerization of sinapic acid, caffeic acid, and ferulic acid by CotA was observed, and highest activity of CotA was found towards sinapic acid.

  7. Mono-thioesters and di-thioesters by lipase-catalyzed reactions of alpha,omega-alkanedithiols with palmitic acid or its methyl ester. (United States)

    Weber, N; Klein, E; Vosmann, K; Mukherjee, K D


    1- S-Mono-palmitoyl-hexanedithiol and 1- S-mono-palmitoyl-octanedithiol were prepared in high yield (80-90%) by solvent-free lipase-catalyzed thioesterification of palmitic acid with the corresponding alpha,omega-alkanedithiols in vacuo. Similarly, 1,6-di- S-palmitoyl-hexanedithiol and 1,8-di- S-palmitoyl-octanedithiol were prepared in moderate yield (50-60%) by solvent-free lipase-catalyzed thioesterification of palmitic acid with 1- S-Mono-palmitoyl-hexanedithiol and 1- S-mono-palmitoyl-octanedithiol, respectively. An immobilized lipase preparation from Rhizomucor miehei (Lipozyme RM IM) was more effective than a lipase B preparation from Candida antarctica (Novozym 435) or a lipase preparation from Thermomyces lanuginosus (Lipozyme TL IM). Lipase-catalyzed transthioesterifications of methyl palmitate with alpha,omega-alkanedithiols using the same enzymes were less effective than thioesterification for the preparation of the corresponding 1- S-mono-palmitoyl thioesters.

  8. 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.


    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.

  9. In situ detection of denitrifying bacteria by mRNA-targeted nucleic acid probes and catalyzed reporter deposition

    DEFF Research Database (Denmark)

    Kofoed, Michael Vedel; Stief, Peter; Poulsen, Morten;

    In situ detection of denitrifying bacteria by mRNA-targeted nucleic acid probes and catalyzed reporter deposition   Michael V.W. Kofoed, Peter Stief, Morten Poulsen, and Andreas Schramm Department of Biological Sciences, Microbiology, University of Aarhus, Denmark Denitrification, the sequential...... reduction of nitrate to dinitrogen gas, is essential for the removal of fixed nitrogen from natural and engineered ecosystems. However, community structure and activity dynamics of denitrifying bacteria in most systems are poorly understood, partially due to difficulties in identifying and quantifying...... (active) denitrifiers. The goal of this study was therefore to develop a protocol for the in situ detection of denitrifying bacterial cells by targeting the mRNA of denitrification genes, hereby linking denitrification activity directly to the single-cell level. Target genes were narG (encoding nitrate...

  10. Brønsted-acid-catalyzed asymmetric multicomponent reactions for the facile synthesis of highly enantioenriched structurally diverse nitrogenous heterocycles. (United States)

    Yu, Jie; Shi, Feng; Gong, Liu-Zhu


    Optically pure nitrogenous compounds, and especially nitrogen-containing heterocycles, have drawn intense research attention because of their frequent isolation as natural products. These compounds have wide-ranging biological and pharmaceutical activities, offering potential as new drug candidates. Among the various synthetic approaches to nitrogenous heterocycles, the use of asymmetric multicomponent reactions (MCRs) catalyzed by chiral phosphoric acids has recently emerged as a particularly robust tool. This method combines the prominent merits of MCRs with organocatalysis, thus affording enantio-enriched nitrogenous heterocyclic compounds with excellent enantioselectivity, atom economy, bond-forming efficiency, structural diversity, and complexity. In this Account, we discuss a variety of asymmetric MCRs catalyzed by chiral phosphoric acids that lead to the production of structurally diverse nitrogenous heterocycles. In MCRs, three or more reagents are combined simultaneously to produce a single product containing structural contributions from all the components. These one-pot processes are especially useful in the construction of heterocyclic cores: they can provide a high degree of both complexity and diversity for a targeted set of scaffolds while minimizing the number of synthetic operations. Unfortunately, enantioselective MCRs have thus far been relatively underdeveloped. Particularly lacking are reactions that proceed through imine intermediates, which are formed from the condensation of carbonyls and amines. The concomitant generation of water in the condensation reaction can deactivate some Lewis acid catalysts, resulting in premature termination of the reaction. Thus, chiral catalysts typically must be compatible with water for MCRs to generate nitrogenous compounds. Recently, organocatalytic MCRs have proven valuable in this respect. Brønsted acids, an important class of organocatalysts, are highly compatible with water and thereby offer great

  11. 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:; Jiang, Bin; Zhao, Minnan; Zhang, Yan


    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.

  12. Silver-Catalyzed Decarboxylative Allylation of Aliphatic Carboxylic Acids in Aqueous Solution. (United States)

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


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

  13. Investigation of the behaviour of solid acid catalysts for acylations and cyanisations of aromatics. Final report; Untersuchungen zur Wirkungsweise von festen sauren Katalysatoren bei Acylierungen und Cyanierungen von Aromaten. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Kemnitz, E.


    The present state of the art in the field of FRIEDEL-CRAFTS-ACYLATIONS is characterized by the application of homogenous catalysts (at least stochiometric amounts) like AlCl{sub 3} or FeCl{sub 3}. Problems arising from this application are corrosions, difficult product separations from the catalyst and the origin of acid waste water. Hence, the aim of this project was the development of suitable solid catalysts which overcome the problems ascribed above. Sulfated zirconia (SZ) was found to be an excellent solid Br.o/nsted-acid to be used especially in their aerogel or cryogel form. Thus with this catalyst system, in the benzoylation of anisol nearly 100% conversion may be achieved. In this way it could be proved, that with SZ a solid Br.o/nsted-acid might be available which gives reasonable hope to substitute in a near future, at least for some reactions, the classical homogeneous catalysts and to overcome their problems in use. (orig.)

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

    Directory of Open Access Journals (Sweden)

    Chen Jinnan


    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.

  15. 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


    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.


    NARCIS (Netherlands)



    The liquid-phase hydration of cyclohexene, a pseudo-first-order reversible reaction catalyzed by a strong acid ion-exchange resin, was investigated in solvent mixtures of water and sulfolane. Macroporous Amberlite XE 307 was used because of its superior catalytic activity. Chemical equilibrium conve

  17. 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)


    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.

  18. 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.


    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

  19. The nature of fatty acid modifies the equilibrium position in the esterification catalyzed by lipase

    NARCIS (Netherlands)

    Flores, M.V.; Sewalt, J.J.W.; Janssen, A.E.M.; Padt, van der A.


    The equilibrium position in lipase mediated esterification of various fatty acids and butanol was studied. The influence of the chain length and the presence of unsaturations in the fatty acids on the equilibrium position was measured and predicted. To predict equilibrium position the program TREP e

  20. Acid-catalyzed steam pretreatment of lodgepole pine and subsequent enzymatic hydrolysis and fermentation to ethanol. (United States)

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


    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.

  1. Thiol-functionalized copolymeric polyesters by lipase-catalyzed esterification and transesterification of 1,12-dodecanedioic acid and its diethyl ester, respectively, with 1-thioglycerol


    Fehling, Eberhard; Bergander, Klaus; Klein, Erika; Weber, Nikolaus; Vosmann, Klaus


    Abstract Copolymeric polyoxoesters containing branched-chain methylenethiol functions, i.e., poly(1,12-dodecanedioic acid-co-1-thioglycerol) and poly(diethyl 1,12-dodecanedioate-co-1-thioglycerol), were formed by lipase-catalyzed polyesterification and polytransesterification of 1,12-dodecanedioic acid and diethyl 1,12-dodecanedioate, respectively, with 1-thioglycerol (3-mercaptopropane-1,2-diol) using immobilized lipase B from Candida antarctica (Novozym 435) in vacuo without dryi...

  2. Role of keto–enol tautomerization in a chiral phosphoric acid catalyzed asymmetric thiocarboxylysis of meso-epoxide: a DFT study

    KAUST Repository

    Ajitha, Manjaly John


    The mechanism of a chiral phosphoric acid catalyzed thiocarboxylysis of meso-epoxide was investigated by density functional theory (DFT) calculations (M06-2X). The nucleophilic ring opening of epoxide by thiobenzoic acid was found to proceed via a concerted termolecular transition state with a simultaneous dual proton transfer to yield the β-hydroxy thioester product. Electrostatic interactions together with the steric environment inside the chiral catalyst play an important role in determining the enantioselectivity of the reaction.

  3. Copper-catalyzed decarboxylative C-P cross-coupling of alkynyl acids with H-phosphine oxides: a facile and selective synthesis of (E)-1-alkenylphosphine oxides. (United States)

    Hu, Gaobo; Gao, Yuxing; Zhao, Yufen


    A novel and efficient copper-catalyzed decarboxylative cross-coupling of alkynyl acids for the stereoselective synthesis of E-alkenylphosphine oxides has been developed. In the presence of 10 mol % of CuCl without added ligand, base, and additive, various alkynyl acids reacted with H-phosphine oxides to afford E-alkenylphosphine oxides with operational simplicity, broad substrate scope, and the stereoselectivity for E-isomers.

  4. 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


    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.

  5. An efficient synthesis of 1,5-benzodiazepine derivatives catalyzed by boric acid

    Institute of Scientific and Technical Information of China (English)

    Xin Zhou; Mei Yue Zhang; Shu Tao Gao; Jing Jun Ma; Chun Wang; Chao Liu


    1,5-Benzodiazepine derivatives have been synthesized by the condensation of o-phenylenediamines and ketones in the presence of boric acid as catalyst under mild conditions. This method is simple, environmentally benign and high yielding.

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

    Institute of Scientific and Technical Information of China (English)


    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.

  7. A convenient synthesis of pyrroles catalyzed by acidic resin under solvent-free condition

    Institute of Scientific and Technical Information of China (English)



    A convenient and effective Paal-Knorr condensations of 2,5-hexanedione with most amines have been carried out at room temperature under solvent-free condition. Macroporous strongly acidic styrol resin (D001) as a novel, efficient, cost-effective, and reusable solid acid catalyst for the synthesis of pyrroles under the same conditions. The pyrroles were obtained in high yields in short reaction times.

  8. Lewis base activation of Lewis acids: development of a Lewis base catalyzed selenolactonization. (United States)

    Denmark, Scott E; Collins, William R


    The concept of Lewis base activation of Lewis acids has been applied to the selenolactonization reaction. Through the use of substoichiometric amounts of Lewis bases with "soft" donor atoms (S, Se, P) significant rate enhancements over the background reaction are seen. Preliminary mechanistic investigations have revealed the resting state of the catalyst as well as the significance of a weak Brønsted acid promoter.

  9. Chiral-at-Metal Rh(III) Complex-Catalyzed Decarboxylative Michael Addition of β-Keto Acids with α,β-Unsaturated 2-Acyl Imidazoles or Pyridine. (United States)

    Li, Shi-Wu; Gong, Jun; Kang, Qiang


    A newly prepared chiral-at-metal Rh(III) complex-catalyzed, highly efficient enantioselective decarboxylative Michael addition of β-keto acids with α,β-unsaturated 2-acyl imidazoles or pyridine has been developed, affording the corresponding adducts in 94-98% yield with up to 96% enantioselectivity. This protocol exhibits remarkable reactivity, as the complex with a Rh(III) loading as low as 0.05 mol % can catalyze the decarboxylative Michael addition on a gram scale without loss of enantioselectivity.

  10. 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


    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.

  11. 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


    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.

  12. Lipase-catalyzed esterification of ferulic Acid with oleyl alcohol in ionic liquid/isooctane binary systems. (United States)

    Chen, Bilian; Liu, Huanzhen; Guo, Zheng; Huang, Jian; Wang, Minzi; Xu, Xuebing; Zheng, Lifei


    Lipase-catalyzed synthesis of ferulic acid oleyl alcohol ester in an ionic liquid (IL)/isooctane system was investigated. Considerable bioconversion and volumetric productivity were achieved in inexpensive 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF(6)]) and 1-methyl-3-octylimidazolium hexafluorophosphate ([Omim][PF(6)]) mediated systems, and thus, the two types of ILs were selected for further optimization of variables. The results showed that, before reaching a maximum, the increase of ferulic acid concentration, temperature, or enzyme dosage led to an increase in volumetric productivity. Variations of the ratios of IL/isooctane and concentrations of oleyl alcohol also profoundly affected the volumetric productivity. To a higher extent, [Hmim][PF(6)]/isooctane and [Omim][PF(6)]/isooctane show similar reaction behaviors. Under the optimized reaction conditions (60 °C, 150 mg of Novozym 435 and 100 mg of molecular sieves), up to 48.50 mg/mL productivity of oleyl feruleate could be achieved for the [Hmim][PF(6)]/isooctane (0.5 mL/1.5 mL) system with a substrate concentration of ferulic acid of 0.08 mmol/mL and oleyl alcohol of 0.32 mmol; while an optimum volumetric productivity of 26.92 mg/mL was obtained for the [Omim][PF(6)]/ isooctane (0.5 mL/1.5 mL) system under a similar reaction condition other than the substrate concentrations of ferulic acid at 0.05 mmol/mL and oleyl alcohol at 0.20 mmol.

  13. 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


    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.

  14. The Aerobic Oxidation of Bromide to Dibromine Catalyzed by Homogeneous Oxidation Catalysts and Initiated by Nitrate in Acetic Acid

    Energy Technology Data Exchange (ETDEWEB)

    Partenheimer, Walt; Fulton, John L.; Sorensen, Christina M.; Pham, Van Thai; Chen, Yongsheng


    A small amount of nitrate, ~0.002 molal, initiates the Co/Mn catalyzed aerobic oxidation of bromide compounds (HBr,NaBr,LiBr) to dibromine in acetic acid at room temperature. At temperatures 40oC or less , the reaction is autocatalytic. Co(II) and Mn(II) themselves and mixed with ionic bromide are known homogeneous oxidation catalysts. The reaction was discovered serendipitously when a Co/Br and Co/Mn/Br catalyst solution was prepared for the aerobic oxidation of methyaromatic compounds and the Co acetate contained a small amount of impurity i.e. nitrate. The reaction was characterized by IR, UV-VIS, MALDI and EXAFS spectroscopies and the coordination chemistry is described. The reaction is inhibited by water and its rate changed by pH. The change in these variables, as well as others, are identical to those observed during homogeneous, aerobic oxidation of akylaromatics. A mechanism is proposed. Accidental addition of a small amount of nitrate compound into a Co/Mn/Br/acetic acid mixture in a large, commercial feedtank is potentially dangerous.

  15. Lipase-Catalyzed Esterification of Ferulic Acid with Oleyl Alcohol in Ionic Liquid/Isooctane Binary Systems

    DEFF Research Database (Denmark)

    Chen, Bilian; Liu, Huanzhen; Guo, Zheng;


    Lipase-catalyzed synthesis of ferulic acid oleyl alcohol ester in an ionic liquid (IL)/isooctane system was investigated. Considerable bioconversion and volumetric productivity were achieved in inexpensive 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF6]) and 1-methyl-3-octylimidazolium....... Variations of the ratios of IL/isooctane and concentrations of oleyl alcohol also profoundly affected the volumetric productivity. To a higher extent, [Hmim][PF6]/isooctane and [Omim][PF6]/isooctane show similar reaction behaviors. Under the optimized reaction conditions (60 °C, 150 mg of Novozym 435 and 100...... mg of molecular sieves), up to 48.50 mg/mL productivity of oleyl feruleate could be achieved for the [Hmim][PF6]/isooctane (0.5 mL/1.5 mL) system with a substrate concentration of ferulic acid of 0.08 mmol/mL and oleyl alcohol of 0.32 mmol; while an optimum volumetric productivity of 26.92 mg...

  16. Synthesis of ascorbyl oleate by transesterification of olive oil with ascorbic acid in polar organic media catalyzed by immobilized lipases. (United States)

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


    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.

  17. Graphene oxide for acid catalyzed-reactions: Effect of drying process (United States)

    Gong, H. P.; Hua, W. M.; Yue, Y. H.; Gao, Z.


    Graphene oxides (GOs) were prepared by Hummers method through various drying processes, and characterized by XRD, SEM, FTIR, XPS and N2 adsorption. Their acidities were measured using potentiometric titration and acid-base titration. The catalytic properties were investigated in the alkylation of anisole with benzyl alcohol and transesterification of triacetin with methanol. GOs are active catalysts for both reaction, whose activity is greatly affected by their drying processes. Vacuum drying GO exhibits the best performance in transesterification while freezing drying GO is most active for alkylation. The excellent catalytic behavior comes from abundant surface acid sites as well as proper surface functional groups, which can be obtained by selecting appropriate drying process.

  18. Phenylalanine ammonia lyase catalyzed synthesis of amino acids by an MIO-cofactor independent pathway. (United States)

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


    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.

  19. 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


    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.

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

    DEFF Research Database (Denmark)

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


    Enzymatic synthesis of esters of lactic acid and straight-chain alcohols with different chain lengths (C6–C18) were investigated in batch reactions with hexadecanol (C16) as the model alcohol. Cyclohexane was the best solvent for higher ester yields, and the best biocatalyst was the immobilized...... of lactic acid to alcohol, each at a concentration of 120 mM each; a 50°C reaction temperature; 190 rpm shaking speed; and the addition of 100 mg molecular sieves (4 Å) for drying. The ester yield increased with increasing lipase load, and a yield of 79.2% could be obtained after 24 h of reaction at 20 wt......% 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....

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

    DEFF Research Database (Denmark)

    Shunmugavel, Saravanamurugan; Riisager, Anders


    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...

  2. Silver-Catalyzed Decarboxylative Radical Azidation of Aliphatic Carboxylic Acids in Aqueous Solution. (United States)

    Liu, Chao; Wang, Xiaoqing; Li, Zhaodong; Cui, Lei; Li, Chaozhong


    We report herein an efficient and general method for the decarboxylative azidation of aliphatic carboxylic acids. Thus, with AgNO3 as the catalyst and K2S2O8 as the oxidant, the reactions of various aliphatic carboxylic acids with tosyl azide or pyridine-3-sulfonyl azide in aqueous CH3CN solution afforded the corresponding alkyl azides under mild conditions. A broad substrate scope and wide functional group compatibility were observed. A radical mechanism is proposed for this site-specific azidation.

  3. 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


    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.

  4. Primary deuterium isotope effects for the 3-methylaspartase-catalyzed deamination of (2S)-aspartic acid, (2S,3S)-3-ethylaspartic acid, and (2S,3S)-3-ethylaspartic acid

    Energy Technology Data Exchange (ETDEWEB)

    Botting, N.P.; Cohen, M.A.; Akhtar, M.; Gani, D.


    3-Methylaspartate ammonia-lyase catalyzes the deamination of (2S)-aspartic acid 137 times more slowly than the deamination of (2S,3S)-3-methylaspartic acid but catalyzes the amination of fumaric acid 1.8 times faster than the amination of mesaconic acid. In order to understand the mechanistic basis for these observations, the deamination reaction was examined kinetically with (2S)-aspartic acid, (2S,3S)-3-methylaspartic acid, (2S,3S)-3-ethylaspartic acid, and the corresponding C-3-deuteriated isotopomers. Comparison of the double-reciprocal plots of the initial reaction velocities for each of the three pairs of substrates revealed that the magnitude of the primary isotope effect on both V/sub max/ and VK varied with the substituent at C-3 of the substrate. These results, which are inconsistent with earlier reports that there is no primary isotope effect for 3-methylaspartic acid, suggest that for both 3-methylaspartic acid and 3-ethylaspartic acid elimination occurs via a predominantly concerted mechanism whereas for aspartic acid in El/sub cb/ mechanism prevails. It is expected that the change in mechanism arises as a result of the loss of the hydrophobic interaction between the C-3-alkyl substituent of the substrate and the complementary active site pocket of the enzyme, which leads to poor orbital alignment of the nascent negative charge with the C-N bond in the carbanion derived from aspartic acid. Substrate C-3 hydrogen exchange experiments suggest that the intermediate carbanionconjugate acid is not accessible to solvent during catalysis.

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

    Institute of Scientific and Technical Information of China (English)


    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.

  6. Nonmetal catalyzed insertion reactions of diazocarbonyls to acid derivatives in fluorinated alcohols. (United States)

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


    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.

  7. A highly enantioselective phase-transfer catalyzed epoxidation of enones with a mild oxidant, trichloroisocyanuric acid. (United States)

    Ye, Jinxing; Wang, Yongcan; Liu, Renhua; Zhang, Guofu; Zhang, Qing; Chen, Jiping; Liang, Xinmiao


    The enantioselective epoxidation can be carried out using trichloroisocyanuric acid (TCCA) as oxidant in the presence of chiral quaternary ammonium salt as a phase-transfer catalyst; treatment of chalcone derivatives with TCCA under mild conditions afforded the corresponding epoxy ketones in good yields with moderate to excellent enantioselectivities of up to 96%.

  8. 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.


    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

  9. Interesterification of Milk Fat with Oleic Acid Catalyzed by Immobilized Rhizopus oryzae Lipase

    NARCIS (Netherlands)

    OBA, T; Witholt, B.


    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

  10. Oxalic Acid Catalyzed Three Component One Pot Synthesis of 3,4-Dihydroquinazolin-4-ones

    Institute of Scientific and Technical Information of China (English)

    SANGSHETTI Jaiprakash-N.; KOKARE Nagnnath-D.; SHINDE Devanand-B.


    An efficient one-pot method for synthesis of an array of 3,4-dihydroquinazolin-4-ones from anthranilicacid, triethyl orthoformate, and anilines using oxalic acid as a catalyst was described. The present protocol offers im-provements for the synthesis of 3,4-dihydroquinazolin-4-ones with regard to short reaction time, high yields of products, and simplicity in operation.

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

    Institute of Scientific and Technical Information of China (English)


    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.

  12. The influence of acidity on zeolite H-BEA catalyzed isobutane/n-butene alkylation

    NARCIS (Netherlands)

    Nivarthy, Gautam S.; Seshan, K.; Lercher, Johannes A.


    The influence of the concentration of acid sites for isobutane/n-butene alkylation on zeolite BEA with varying degrees of Na+ ion exchange is reported. All catalysts studied showed complete n-butene conversion over a significant time-on-stream. Isooctanes were the dominating products over H-BEA, whi

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

    Directory of Open Access Journals (Sweden)

    E.I. Muresan


    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.


    SPARC (SPARC Performs Automated Reasoning in Chemistry) chemical reactivity models were extended to calculate acid and neutral hydrolysis rate constants of phosphate esters in water. The rate is calculated from the energy difference between the initial and transition states of a ...

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

    Directory of Open Access Journals (Sweden)

    Shitole Nana Vikram


    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.

  16. 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.


    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,

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


    NARCIS (Netherlands)



    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. Temperature regulated Brønsted acidic ionic liquid-catalyze esterification of oleic acid for biodiesel application (United States)

    Rafiee, Ezzat; Mirnezami, Fakhrosadat


    By combining phosphotungstic acid (PW) and SO3H- functioned zwitterion, heteropoly anion-based Brønsted acidic ionic liquids (HPA-ILs) were successfully obtained. Scanning electron microscopy and energy dispersive X-ray spectroscopy were provided the morphology and composition of the prepared material. Catalytic performance and reusability of the catalysts were evaluated through an esterification reaction between oleic acid and methanol for production of biodiesel. Relationship between catalytic activities and acidity of the catalysts have been discussed by potentiometric titration. The results showed that HPA-ILs had good activity and reusability. HPA-ILs dissolved in the reaction mixture during the reaction process and could be precipitated and separated from products at lower temperature.

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

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


    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.

  1. Dehydrogenation of Formic Acid Catalyzed by a Ruthenium Complex with an N,N′-Diimine Ligand

    KAUST Repository

    Guan, Chao


    We report a ruthenium complex containing an N,N′-diimine ligand for the selective decomposition of formic acid to H and CO in water in the absence of any organic additives. A turnover frequency of 12000 h and a turnover number of 350 000 at 90 °C were achieved in the HCOOH/HCOONa aqueous solution. Efficient production of high-pressure H and CO (24.0 MPa (3480 psi)) was achieved through the decomposition of formic acid with no formation of CO. Mechanistic studies by NMR and DFT calculations indicate that there may be two competitive pathways for the key hydride transfer rate-determining step in the catalytic process.

  2. Acid-base jointly promoted copper(I)-catalyzed azide-alkyne cycloaddition. (United States)

    Shao, Changwei; Wang, Xinyan; Zhang, Qun; Luo, Sheng; Zhao, Jichen; Hu, Yuefei


    In this novel acid-base jointly promoted CuAAC, the combination of CuI/DIPEA/HOAc was developed as a highly efficient catalytic system. The functions of DIPEA and HOAc have been assigned, and HOAc was recognized to accelerate the conversions of the C-Cu bond-containing intermediates and buffer the basicity of DIPEA. As a result, all drawbacks occurring in the popular catalytic system CuI/NR(3) were overcome easily.

  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


    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)


    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. Hydrolysis of Selected Tropical Plant Wastes Catalyzed by a Magnetic Carbonaceous Acid with Microwave (United States)

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


    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.

  6. Hierarchical porous photoanode based on acid boric catalyzed sol for dye sensitized solar cells (United States)

    Maleki, Khatereh; Abdizadeh, Hossein; Golobostanfard, Mohammad Reza; Adelfar, Razieh


    The hierarchical porous photoanode of the dye sensitized solar cell (DSSC) is synthesized through non-aqueous sol-gel method based on H3BO3 as an acid catalyst and the efficiencies of the fabricated DSSC based on these photoanodes are compared. The sol parameters of 0.17 M, water mole ratio of 4.5, acid mole ratio of 0.45, and solvent type of ethanol are introduced as optimum parameters for photoanode formation without any detectable cracks. The optimized hierarchical photoanode mainly contains anatase phase with slight shift toward higher angles, confirming the doping of boron into titania structure. Moreover, the porous structure involves two ranges of average pore sizes of 20 and 635 nm. The diffuse reflectance spectroscopy (DRS) shows the proper scattering and blueshift in band gap. The paste parameters of solid:liquid, TiO2:ethyl cellulose, and terpineol:ethanol equal to 11:89, 3.5:7.5, and 25:64, respectively, are assigned as optimized parameters for this novel paste. The photovoltaic properties of short circuit current density, open circuit voltage, fill factor, and efficiency of 5.89 mA/cm2, 703 mV, 0.7, and 2.91% are obtained for the optimized sample, respectively. The relatively higher short circuit current of the main sample compared to other samples is mainly due to higher dye adsorption in this sample corresponding to its higher surface area and presumably higher charge transfer confirmed by low RS and Rct in electrochemical impedance spectroscopy data. Boric acid as a catalyst in titania sol not only forms hierarchical porous structure, but also dopes the titania lattice, which results in appreciated performance in this device.

  7. Acid, silver, and solvent-free gold-catalyzed hydrophenoxylation of internal alkynes

    Directory of Open Access Journals (Sweden)

    Marcia E. Richard


    Full Text Available A range of arylgold compounds have been synthesized and investigated as single-component catalysts for the hydrophenoxylation of unactivated internal alkynes. Both carbene and phosphine-ligated compounds were screened as part of this work, and the most efficient catalysts contained either JohnPhos or IPr/SIPr. Phenols bearing either electron-withdrawing or electron-donating groups were efficiently added using these catalysts. No silver salts, acids, or solvents were needed for the catalysis, and either microwave or conventional heating afforded moderate to excellent yields of the vinyl ethers.

  8. Acid, silver, and solvent-free gold-catalyzed hydrophenoxylation of internal alkynes (United States)

    Richard, Marcia E; Fraccica, Daniel V; Garcia, Kevin J; Miller, Erica J; Ciccarelli, Rosa M; Holahan, Erin C; Resh, Victoria L; Shah, Aakash; Findeis, Peter M


    Summary A range of arylgold compounds have been synthesized and investigated as single-component catalysts for the hydrophenoxylation of unactivated internal alkynes. Both carbene and phosphine-ligated compounds were screened as part of this work, and the most efficient catalysts contained either JohnPhos or IPr/SIPr. Phenols bearing either electron-withdrawing or electron-donating groups were efficiently added using these catalysts. No silver salts, acids, or solvents were needed for the catalysis, and either microwave or conventional heating afforded moderate to excellent yields of the vinyl ethers. PMID:24204410

  9. Silver-catalyzed decarboxylative alkynylation of aliphatic carboxylic acids in aqueous solution. (United States)

    Liu, Xuesong; Wang, Zhentao; Cheng, Xiaomin; Li, Chaozhong


    C(sp(3))-C(sp) bond formations are of immense interest in chemistry and material sciences. We report herein a convenient, radical-mediated and catalytic method for C(sp(3))-C(sp) cross-coupling. Thus, with AgNO(3) as the catalyst and K(2)S(2)O(8) as the oxidant, various aliphatic carboxylic acids underwent decarboxylative alkynylation with commercially available ethynylbenziodoxolones in aqueous solution under mild conditions. This site-specific alkynylation is not only general and efficient but also functional group compatible. In addition, it exhibits remarkable chemo- and stereoselectivity.

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

    Institute of Scientific and Technical Information of China (English)

    WEI; TaiBao


    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.  ……

  11. 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


    @@ 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.

  12. The acid-catalyzed hydrolysis of an α-pinene-derived organic nitrate: kinetics, products, reaction mechanisms, and atmospheric impact (United States)

    Rindelaub, Joel D.; Borca, Carlos H.; Hostetler, Matthew A.; Slade, Jonathan H.; Lipton, Mark A.; Slipchenko, Lyudmila V.; Shepson, Paul B.


    data, product identification confirms that a unimolecular specific acid-catalyzed mechanism is responsible for organic nitrate hydrolysis under acidic conditions. The free energies and enthalpies of the isobutyl nitrate hydrolysis intermediates and products were calculated using a hybrid density functional (ωB97X-V) to support the proposed mechanisms. These findings provide valuable information regarding the organic nitrate hydrolysis mechanism and its contribution to the fate of atmospheric NOx, aerosol phase processing, and BSOA composition.

  13. N-heterocyclic carbene-assisted, bis(phosphine)nickel-catalyzed cross-couplings of diarylborinic acids with aryl chlorides, tosylates, and sulfamates. (United States)

    Ke, Haihua; Chen, Xiaofeng; Zou, Gang


    Efficient bis(phosphine)nickel-catalyzed cross-couplings of diarylborinic acids with aryl chlorides, tosylates, and sulfamates have been effected with an assistance of N-heterocyclic carbene (NHC) generated in situ from N,N'-dialkylimidazoliums, e.g., N-butyl-N'-methylimidazolium bromide ([Bmim]Br), in toluene using K3PO4·3H2O as base. In contrast to bis(NHC)nickel-catalyzed conventional Suzuki coupling of arylboronic acids, mono(NHC)bis(phosphine)nickel species generated in situ from Ni(PPh3)2Cl2/[Bmim]Br displayed high catalytic activities in the cross-couplings of diarylborinic acids. The structural influences from diarylborinic acids were found to be rather small, while electronic factors from aryl chlorides, tosylates, and sulfamates affected the couplings remarkably. The couplings of electronically activated aryl chlorides, tosylates, and sulfamates could be efficiently effected with 1.5 mol % NiCl2(PPh3)2/[Bmim]Br as catalyst precursor to give the biaryl products in excellent yields, while 3-5 mol % loadings had to be used for the couplings of non- and deactivated ones. A small ortho-substitutent on the aromatic ring of aryl chlorides, tosylates, and sulfamates was tolerable. Applicability of the nickel-catalyzed cross-couplings in practical synthesis of fine chemicals has been demonstrated in process development for a third-generation topical retinoid, Adapalene.

  14. Kinetics and Mechanism of Iridium(Ⅲ)-Catalyzed Oxidation of Ethanol Amine by Cerium(Ⅳ) in Sulfuric Acid Media

    Institute of Scientific and Technical Information of China (English)

    ZHAI Yong-qing; LIU Hong-mei; YANG Lin; YANG Guo-zhong; SONG Wen-yu; LIU Yu-kai


    In this study, the kinetics and mechanism of the iridium(Ⅲ)-catalyzed oxidation of ethanol amine(EAN) by cerium(Ⅳ) in a sulfuric acid medium was investigated using titrimetric technique of redox in a temperature range of 298-313 K. It was found that the reaction is of first order with respect to Ce(Ⅳ) and Ir(Ⅲ), and a positive fractional order with respect to EAN. It was also found that the pseudo-first-order([EAN](》)[Ce(Ⅳ)]) rate constant kobs decreases with the increase of [H+] and [HSO-4]. Under the protection of nitrogen gas, the reaction system can initiate the polymerization of acrylonitrile, indicating the generation of free radicals. On the basis of the experimental results, a suitable mechanism was proposed. From the dependence of kobs on the concentration of hydrogen sulfate, Ce(SO4)2 was found to be the kinetically active species. The rate constants of the rate-determining step together with the activation parameters were evaluated.

  15. Effect of polyvinylpyrrolidone on mesoporous silica morphology and esterification of lauric acid with 1-butanol catalyzed by immobilized enzyme (United States)

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


    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%.

  16. 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


    A series of 14 lanthanide (Ln) triflates were investigated as sustainable catalysts for aromatic sulfonylation reactions under microwave irradiation. The catalytic efficiency of the early triflates La(OTf)3–Eu(OTf)3 is good for long irradiation times. For the later lanthanides, yields reaching over...... 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......(OTf)3, which matched the “gadolinium break”; the well-known discontinuity in lanthanide properties...

  17. 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


    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.

  18. A combination of friedel-crafts and lawesson reactions to 5-substituted-2,2´-bithiophenes


    Raposo, M. Manuela M; Kirsch, G


    Gama-Keto esters (2) derivatives of thiophene were obtained from hemi-succinic esters and transformed to the corresponding amides (4). Lawesson´s treatment of 2 and 4 gave the corresponding bithiophenes (5) with alkoxy or amino substituents. Fundação para a Ci~Encia e Tecnologia. ICCTI/French Embassy - Technical and Scientific~Cooperation Programme.


    Directory of Open Access Journals (Sweden)



    Full Text Available


    In the present study, a kinetic model for the biocatalytic synthesis of esters using Rhizopus oryzae resting cells is proposed. The kinetic study has been made in a range of 30-50 °C and atmospheric pressure. The Influence of operating variables, water content, pH, amount of mycelium was studied. Different values of temperature, initial mycelium concentration and acid/alcohol molar ratio were tested. Initial rates were estimated from the slope of the concentration of palmitic acid, or their corresponding ester at conversions of less than 10%, versus time and reported as mmol l-1 min -1. The values of kinetic constants were computed using the freeware program SIMFIT (http:\\

    Key words: bound lipase, esterification, fungal resting cells, Rhizopus oryzae, palmitic acid, propanol.


    En el presente estudio, un modelo cinético para la síntesis de esteres usando Rhizopus oryzae resting cells es propuesto. El estudio cinético fue realizado en un rango de temperatura de 30-50 ºC a presión atmosférica reducida. La influencia de las variables de operación tales como temperatura, pH y contenido de agua fueron estudiadas. Diferentes valores de concentración de micelio y relación molar de ácido/alcohol son ensayadas, Las velocidades iníciales se estimaron de la curva de concentración de acido palmítico, y su correspondiente conversión a ester en menos del 10%, frente a tiempo y reportadas en mmol I-1 min -1. Los valores de las constantes cinéticas fueron calculados usando el programa freeware SIMFIT (http:\\

    Palabras clave: Lipasas, esterificación, resting cells, Rhizopus oryzae, acido palmítico, propanol.

  20. Ozone toxicity: hormone-like oxidation products from arachidonic acid by ozone-catalyzed autoxidation

    Energy Technology Data Exchange (ETDEWEB)

    Roycroft, J.H.; Cunter, W.B.; Menzel, D.B.


    The effects of peroxidation by ozone on the activity of arachidonic acid (AA) with and without vitamin E, on the initiation of human platelet aggregation, and on the contraction of superfused smooth muscle strips, are described. AA was rapidly oxidized by a stream of air containing 2 ppm of ozone to peroxides having biological activity similar to prostaglandin endoperoxides. Ozone-formed AA peroxides contracted both rabbit aortic strips and rat fundus strips in the presence of indomethacin and vasoactive hormones at doses comparable to naturally formed prostaglandin endoperoxides. Vitamin E had no effect on the activity of AA peroxides once formed. Ozone-formed AA peroxides also aggregated human platelets in platelet rich plasma, but this activity was blocked by the addition of indomethacin. (2 diagrams, 3 graphs, 8 references)

  1. Optimization of oligoglycerol fatty acid esters preparation catalyzed by Lipozyme 435

    Directory of Open Access Journals (Sweden)

    Wan, F. L.


    Full Text Available Oli goglycerol fatty acid esters (OGEs are an important kind of polyglycerol fatty acid esters (PGEs which have been widely used as emulsifiers in food, medicine and cosmetic industries. The aim of this study was to investigate the preparation of OGEs by the esterification of olig oglycerol with linoleic acid in a solvent- free system using Lipozyme 435 as the catalyst. The effects of substrate molar ratio, reaction time, reaction temperature, enzyme dosage, and water addition on the efficiency of esterification (EE were studied. Single factor experiments and response surface methodology (RSM were employed to optimize the reaction parameters. The optimum conditions were obtained as follows: reaction time 4.52 h, reaction temperature 90 °C, enzyme dosage 2 wt% (based on the total substrate mass, the molar ratio of oligoglycerol to linoleic acid 1.59:1 and no water addition. Under these conditions, the experimental EE (95.82±0.22% fitted well with that predicted by RSM (96.15%. Similar results were obtained when the process was scaled up to a production of 500 g in a pilot bubble column reactor (BCR. The enzyme maintained 98.2% of the relative activity after 10 batches of reaction in the BCR. Electro spray ionization mass spectrum was employed to rapidly analyze the esterification products, and most species of OGEs have been identified.Los ésteres grasos de oligoglicerol (OGEs son una clase importante de ésteres de ácidos grasos de poliglicerol (PGE que han sido ampliamente utilizados como emulsionantes en alimentación, medicina y en la industria cosmética. El objetivo de este estudio fue investigar la preparación de OGEs mediante la esterificación de oligoglicerol con ácido linoleico en un sistema libre de disolvente utilizando Lipozyme 435 como catalizador. Se estudiaron los efectos en la eficiencia de esterificación (EE de la relación molar de sustratos, de los tiempos de reacción, las temperaturas de reacción, la dosis de la

  2. Biomimetic Fenton-catalyzed lignin depolymerization to high-value aromatics and dicarboxylic acids. (United States)

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


    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.

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

    KAUST Repository

    Riache, Nassima


    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.

  4. 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


    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.

  5. 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


    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.

  6. 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


    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.

  7. Regio-, Diastereo-, and Enantioselective Nitroso-Diels-Alder Reaction of 1,3-Diene-1-carbamates Catalyzed by Chiral Phosphoric Acids. (United States)

    Pous, Jonathan; Courant, Thibaut; Bernadat, Guillaume; Iorga, Bogdan I; Blanchard, Florent; Masson, Géraldine


    Chiral phosphoric acid-catalyzed asymmetric nitroso-Diels-Alder reaction of nitrosoarenes with carbamate-dienes afforded cis-3,6-disubstituted dihydro-1,2-oxazines in high yields with excellent regio-, diastereo-, and enantioselectivities. Interestingly, we observed that the catalyst is able not only to control the enantioselectivity but also to reverse the regioselectivity of the noncatalyzed nitroso-Diels-Alder reaction. The regiochemistry reversal and asynchronous concerted mechanism were confirmed by DFT calculations.

  8. 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


    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.

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

    KAUST Repository

    Millet, Anthony


    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

  10. Directing Group in Decarboxylative Cross-Coupling: Copper-Catalyzed Site-Selective C-N Bond Formation from Nonactivated Aliphatic Carboxylic Acids. (United States)

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


    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.

  11. 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


    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.

  12. Activated carbon catalyzed persulfate oxidation of Azo dye acid orange 7 at ambient temperature. (United States)

    Yang, Shiying; Yang, Xin; Shao, Xueting; Niu, Rui; Wang, Leilei


    Persulfate (PS) oxidative degradation of azo dye acid orange 7 (AO7) in an aqueous solution was studied in the presence of suspended granular activated carbon (GAC) at ambient temperature (e.g., 25°C). It was observed that there existed a remarkable synergistic effect in the GAC/PS combined system. Higher PS concentration and GAC dosage resulted in higher AO7 degrading rates. Near-neutral was the optimal initial pH. Adsorption had an adverse effect on AO7 degradation. AO7 had not only a good decolorization, but a good mineralization. The decomposition of PS followed a first-order kinetics behavior both in the presence and in the absence of AO7. Radical mechanism was studied and three radical scavengers (methanol (MA), tert-butanol (TBA), phenol) were used to determine the kind of major active species taking part in the degradation of AO7 and the location of degradation reaction. It was assumed that the degradation of AO7 did not occur in the liquid phase, but in the porous bulk and boundary layer on the external surface of GAC. SO(4)(-•) or HO•, generated on or near the surface of GAC, played a major role in the AO7 degradation. Finally, the recovery performance of GAC was studied through the GAC reuse experiments.

  13. 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


    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%.

  14. Lewis acid-catalyzed in situ transesterification/esterification of microalgae in supercritical ethanol. (United States)

    Jin, Binbin; Duan, Peigao; Xu, Yuping; Wang, Bing; Wang, Feng; Zhang, Lei


    The activities of several Lewis acid catalysts such SnCl2, FeCl3, ZnCl2, AlCl3, and NbCl5 for the in situ transesterification/esterification of lipid contained within a microalga (Chlorella pyrenoidosa) in ethanol at 350°C were examined to identify the most suitable catalyst in term of crude biodiesel (CBD) yield. Of those catalysts tested, ZnCl2 showed the highest performance toward the CBD production. Using ZnCl2 as catalyst, effects of reaction temperature (200-370 °C), time (0-120 min), ethanol to microalga ratio (EtOH:MA) (5/5-40/5), catalyst loading (0-30 wt.%), and algae moisture (0-80 wt.%) on the yields of product fractions and the properties of CBD were studied. The presence of ZnCl2 not only promoted the production of CBD but also showed activities toward the deoxygenation and denitrogenation of CBD. The moisture content in the starting material is the most influential factor affecting the yield and properties of CBD.

  15. Preparation and structural characterization of poly-mannose synthesized by phosphoric acid catalyzation under microwave irradiation. (United States)

    Wang, Haisong; Cheng, Xiangrong; Shi, Yonghui; Le, Guowei


    Poly-mannose with molecular weight of 2.457 kDa was synthesized using d-mannose as substrate and phosphoric acid as catalyst under the condition of microwave irradiation for the first time. The optimum reaction conditions were microwave output power of 900 W, temperature 115°C, proton concentration 2.5 mol/L, and microwave irradiation time 5 min. The actual maximum yield was 91.46%. After purified by Sepherdex G-25 column chromatography, the structural features of poly-mannose were investigated by high-performance anion-exchange chromatography (HPAEC), high-performance gel-permeation chromatography (HPGPC), infrared (IR) spectroscopy, methylation analysis and NMR spectroscopy analysis ((1)H, (13)C, COSY, TOCSY, HMQC, and HMBC). HPAEC analysis showed that the composition of synthetic polysaccharides was d-mannose, its purity was demonstrated by HPGPC as a single symmetrical sharp peak, and additionally IR spectra demonstrated the polymerization of d-mannose. Methylation analysis and NMR spectroscopy revealed that the backbone of poly-mannose consisting of (1→3)-linked β-d-Manp, (1→3)-linked α-d-Manp, and (1→6)-linked α-d-Manp residues, and the main chain were branched at the O-2, O-3, O-4, O-6 position.

  16. Glutamate 190 is a general acid catalyst in the 6-phosphogluconate-dehydrogenase-catalyzed reaction. (United States)

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


    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.

  17. Human CYP4Z1 catalyzes the in-chain hydroxylation of lauric acid and myristic acid. (United States)

    Zöllner, Andy; Dragan, Calin-Aurel; Pistorius, Dominik; Müller, Rolf; Bode, Helge B; Peters, Frank T; Maurer, Hans H; Bureik, Matthias


    Overexpression of human CYP4Z1, a cytochrome P450 enzyme, has been correlated with poor prognosis in human cancer. However, its catalytic properties are not yet known. We expressed this P450 in Schizosaccharomyces pombe and demonstrate by whole-cell biotransformation assays CYP4Z1-dependent in-chain hydroxylation of lauric and myristic acid, which in both cases leads to the formation of four different monohydroxylated products at positions omega-2, omega-3, omega-4, and omega-5, respectively. The CYP4Z1-expressing fission yeast should be a new valuable tool for testing cancer drugs or for the development of new prodrug strategies.

  18. 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


    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.

  19. 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


    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

  20. Amino acid catalyzed bulk-phase gelation of organoalkoxysilanes via a transient co-operative self-assembly. (United States)

    Shen, Shukun; Hu, Daodao; Sun, Peipei; Zhang, Xiaoru; Parikh, Atul N


    We report acceleration in the rate of bulk phase gelation of an organoalkoxysilane, 3-methacryloxypropyltrimethoxysilane (MAPTMS), in the presence of an amphiphilic additive, N-phenyl glycine (NPG). The MAPTMS gelation occurs within 30 min in the presence of 0.5 wt % NPG, which took several months in the absence of NPG. Using a combination of ATR-FT IR, (29)Si NMR, (1)H NMR, viscosity analysis, SEM, UV-vis, and pi-A isotherm measurements, we elucidate the molecular-level details of the structural changes during NPG-catalyzed MPTMS gelation rate. On the basis of these results, we propose a gelation mechanism in which a transient cooperative self-assembly process fosters hydrolysis and retards early condensation thereby promoting the formation of extended three-dimensionally cross-linked gels. Specifically, the amphiphilic character of the hydrolysis product of MAPTMS, consisting of a hydrophobic tail R = -CH(2)CH(2)CH(2)O(CO)C(CH(3)) horizontal lineCH(2) and a hydrophilic Si-OH headgroup, promotes micelle formation at high MAPTMS/water ratio. NPG readily inserts within these micelles thus retarding the topotactic condensation of silanols at the micellar surface. This in turn allows for a more complete hydrolysis of Si-OCH(3) groups prior to condensation in MAPTMS. With increased silanol concentration at the micellar periphery, a delayed condensation phase initiates. This formation of a covalently bonded Si-O-Si framework (and possibly also the formation of the methanol byproduct) likely destabilizes the micellar motif thus promoting its transformation into condensed mesophases (e.g., lamellar microstructure) upon gelation. Because of the generality of this transient and co-operative organic-inorganic self-assembly between hydrolyzed amphiphilic organoalkoxysilanes and surfactant-like amino acid additives, we envisage applications in controlling bulk phase gelation of many chain-substituted organoalkoxysilanes.

  1. 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:; Rezwan, Kurosch [University of Bremen, Advanced Ceramics (Germany)


    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.

  2. Low-temperature Rh-catalyzed asymmetric 1,4-addition of arylboronic acids to α,β-unsaturated carbonyl compounds. (United States)

    Korenaga, Toshinobu; Ko, Aram; Shimada, Kazuaki


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

  3. Kinetics and mechanism of OsOsub(4) catalyzed oxidation of chalcones by Cesub(4) in aqueous acetic sulfuric acid media

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasulu, P.V.; Adinarayana, M.; Sethuram, B.; Rao, T.N. (Osmania Univ., Hyderabad (India). Dept. of Chemistry)


    Kinetics of OsOsub(4) catalyzed oxidation of chalcones by Cesup(4+) was studied in aqueous acetic-sulfuric acid medium in the temperature range 313 to 338 K. The order in oxidant is zero while the order with respect to substrate and catalyst are each fractional. The rate of the reaction decreased with increase in percentage of acetic acid while (Hsup(+)) had practically no effect on the rate. The rates of various substituted chalcones are given. A mechanism in which formation of a cyclic ester between chalcone and OsOsub(4) in a fast step followed by its decomposition in a rate-determining step is envisaged.

  4. 氨基磺酸催化合成脂肪酸丁酯的研究%Synthesis of fatty acid butyl ester catalyzed by amino sulfonic acid

    Institute of Scientific and Technical Information of China (English)

    程正载; 龚凯; 张卫星; 高松; 雷锐; 颜晓潮; 从野


    The fatty acid butyl ester was respectively synthesized by the esterification of oleic acid with bu-tanol and the transesterification of rapeseed oil with butanol catalyzed by amino sulfonic acid. The fatty acid butyl ester product was analyzed by GC and its structure was characterized by FT-IR. The effects of molar ratio of butanol to oil ( oleic acid or rapeseed oil) , catalyst dosage, reaction temperature and reac-tion time on the conversion rates of oleic acid and rapeseed oil were investigated. The results showed that the optimal esterification conditions were obtained as follows: molar ratio of butanol to oleic acid 3∶1 , catalyst dosage 0. 8% (based on the mass of oleic acid), reaction temperature 110℃and reaction time 1. 5 h. Under these conditions, the conversion rate of oleic acid and the yield of fatty acid butyl ester reached 88. 6% and 83. 5%, respectively. The optimal transesterification conditions were obtained as follows:molar ratio of butanol to rapeseed oil 10∶1, catalyst dosage 1. 0% (based on the mass of rapeseed oil), reaction temperature 115℃ and reaction time 2. 0 h. Under the optimal conditions, the conversion rate of rapeseed oil and the yield of fatty acid butyl ester achieved 85. 6% and 80. 1%, respectively.%以氨基磺酸为催化剂,油酸及菜籽油与正丁醇分别进行酯化反应与酯交换反应制备脂肪酸丁酯。并利用气相色谱及红外光谱对产物进行分析及结构表征。考察了醇(正丁醇)油(油酸及菜籽油)摩尔比、催化剂用量、反应温度和反应时间对油酸及菜籽油转化率的影响。结果表明,油酸酯化反应的最佳工艺条件为:醇油摩尔比3∶1,催化剂用量为油酸质量的0.8%,反应温度110℃,反应时间1.5 h,此时油酸转化率达到88.6%,产品收率为83.5%;菜籽油酯交换反应的最佳工艺条件为:醇油摩尔比10∶1,催化剂用量为菜籽油质量的1.0%,反应温度115℃,反应时间2.0 h,

  5. Catalytic Enantioselective Synthesis of Tetrahydocarbazoles and Exocyclic Pictet-Spengler-Type Reactions

    DEFF Research Database (Denmark)

    Hansen, Casper Lykke; Ohm, Ragnhild Gaard; Olsen, Lasse Bohn;


    A synthetic strategy for the synthesis of chiral tetrahydrocarbazoles (THCAs) has been developed. The strategy relies on two types of 6-exo-trig cyclization of 3-substituted indole substrates. Enantioselective domino Friedel-Crafts-type reactions leading to THCAs can be catalyzed by chiral phosph...

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

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


    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.

  7. Efficient production of fermentable sugars from oil palm empty fruit bunch by combined use of acid and whole cell culture-catalyzed hydrolyses. (United States)

    Li, Qingxin; Ng, Wei Ting; Puah, Sze Min; Bhaskar, Ravindran Vijay; Soh, Loon Siong; MacBeath, Calum; Parakattil, Pius; Green, Phil; Wu, Jin Chuan


    Empty fruit bunch (EFB) of oil palm trees was converted to fermentable sugars by the combined use of dilute acids and whole fungal cell culture-catalyzed hydrolyses. EFB (5%, w/v) was hydrolyzed in the presence of 0.5% H2 SO4 and 0.2% H3 PO4 at 160 °C for 10 Min. The solid fraction was separated from the acid hydrolysate by filtration and subjected to enzymatic hydrolysis at 50 °C using the whole cell culture of Trichoderma reesei RUT-C30 (2%, w/v), which was prepared by cultivation at 30 °C for 7 days to reach its maximal cellulase activity. The combined hydrolyses of EFB gave a total sugar yield of 82.0%. When used as carbon sources for cultivating Escherichia coli in M9 medium at 37 °C, the combined EFB hydrolysates were shown to be more favorable or at least as good as pure glucose for cell growth in terms of the higher (1.1 times) optical density of E. coli cells. The by-products generated during the acid-catalyzed hydrolysis did not seem to obviously affect cell growth. The combined use of acid and whole cell culture hydrolyses might be a commercially promising method for pretreatment of lignocellulose to get fermentable sugars.

  8. 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


    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。

  9. The role of the alcohol and carboxylic acid in directed ruthenium-catalyzed C(sp3)-H α-alkylation of cyclic amines. (United States)

    Bergman, Sheba D; Storr, Thomas E; Prokopcová, Hana; Aelvoet, Karel; Diels, Gaston; Meerpoel, Lieven; Maes, Bert U W


    A general directed Ru-catalyzed C(sp(3))-H α-alkylation protocol for piperidines (less-reactive substrates than the corresponding five-membered cyclic amines) has been developed. The use of a hindered alcohol (2,4-dimethyl-3-pentanol) as the solvent and catalyst activator, and a catalytic amount of trans-1,2-cyclohexanedicarboxylic acid is necessary to achieve a high conversion to product. This protocol was used to effectively synthesize a number of 2-hexyl- and 2,6-dihexyl piperidines, as well as the alkaloid (±)-solenopsin A. Kinetic studies have revealed that the carboxylic acid additive has a significant effect on catalyst initiation, catalyst longevity, and reverses the reaction selectivity compared with the acid-free reaction (promotes alkylation versus competing alkene reduction).

  10. Thiol-functionalized copolymeric polyesters by lipase-catalyzed esterification and transesterification of 1,12-dodecanedioic acid and its diethyl ester, respectively, with 1-thioglycerol. (United States)

    Fehling, Eberhard; Bergander, Klaus; Klein, Erika; Weber, Nikolaus; Vosmann, Klaus


    Copolymeric polyoxoesters containing branched-chain methylenethiol functions, i.e., poly(1,12-dodecanedioic acid-co-1-thioglycerol) and poly(diethyl 1,12-dodecanedioate-co-1-thioglycerol), were formed by lipase-catalyzed polyesterification and polytransesterification of 1,12-dodecanedioic acid and diethyl 1,12-dodecanedioate, respectively, with 1-thioglycerol (3-mercaptopropane-1,2-diol) using immobilized lipase B from Candida antarctica (Novozym 435) in vacuo without drying agent in the reaction mixture. After 360-480 h, both polyoxoesters were purified by extraction from the reaction mixtures followed by solvent fractionation. The precipitate of poly(1,12-dodecanedioic acid-co-1-thioglycerol) demonstrated a M(W) of ~170,000 Da, whereas a M(W) of ~7,100 Da only was found for poly(diethyl 1,12-dodecanedioate-co-1-thioglycerol). Both polycondensates were analyzed by GPC/SEC, alkali-catalyzed transmethylation, NMR- and FTIR-spectrometry.

  11. Zirconium phosphate nanoparticles as a remarkable solid acid catalyst for selective solvent-free alkylation of phenol

    Institute of Scientific and Technical Information of China (English)

    Abdol R. Hajipour; Hirbod Karimi


    A facile synthesis of α-zirconium phosphate (ZP) nanoparticles as an effective, eco-friendly, and recyclable solid acid catalyst is reported. Polyvinylpyrrolidone (PVP) and polyvinyl alcohol (PVA) were used as organic matrix as dispersing agents and served as a template for the nanoparticles. Hydrogen bonds between ZP and PVA or PVP, along the polymer chains, appear to play an im-portant role for improving the dispersion of in situ formed ZP. Following calcination of PVA/ZP or PVP/ZP, pure hexagonal ZP nanoparticles were obtained. The catalysts were characterized by ni-trogen sorption, inductively coupled plasma optical emission spectroscopy, X-ray diffraction, Fouri-er transform infrared spectroscopy (FTIR), scanning electron microscopy, and transmission elec-tron microscopy. Pyridine-FTIR and temperature-programmed desorption of NH3 suggest the presence of Brönsted acid sites. The acidic properties of the catalyst were studied in Friedel-Crafts alkylation of phenol by tert-butanol, producing 2-tert-butylphenol, 4-tert-butylphenol, and 2,4-di-tert-butylphenol. The alkylation reaction was performed in the presence of catalysts P2O5/Al2O3, P2O5/SiO2, α-ZrP (prepared in the absence of the polymers), and various ionic liquids. The use of the hexagonal ZP nanoparticle catalyst afforded an excellent phenol conversion (86%) and selectivity towards 4-tert-butylphenol (83%) under optimized reaction conditions. The catalyst was easily recovered from the reaction mixture, regenerated, and reused at least four times without significant loss in the catalytic activity.

  12. 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.


    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

  13. Synthesis of Isocoumarins from Cyclic 2-Diazo-1,3-diketones and Benzoic Acids via Rh(III)-Catalyzed C-H Activation and Esterification. (United States)

    Yang, Cheng; He, Xinwei; Zhang, Lanlan; Han, Guang; Zuo, Youpeng; Shang, Yongjia


    A mild and efficient Rh(III)-catalyzed C-H activation/esterification reaction for the synthesis of isocoumarins has been developed. This procedure uses readily available benzoic acids and cyclic diazo-1,3-diketones as starting materials and involves domino intermolecular C-H activation in combination with intramolecular esterification to give the corresponding isocoumarins in moderate to excellent yields. This process provides a facile approach for the construction of isocoumarins containing various functional groups that does not require any additives.

  14. Palladium-catalyzed air-based oxidative coupling of arylboronic acids with H-phosphine oxides leading to aryl phosphine oxides. (United States)

    Fu, Tingting; Qiao, Hongwei; Peng, Zhimin; Hu, Gaobo; Wu, Xueji; Gao, Yuxing; Zhao, Yufen


    We present a novel and highly efficient methodology that allows for the construction of C-P bonds via the palladium-catalyzed air-based oxidative coupling of various commercially available arylboronic acids with easily oxidized H-phosphine oxides leading to valuable aryl phosphine oxides, particularly triarylphosphine oxides, with the use of air as the green oxidant, broad substrate applicability and good to excellent yields. The described catalytic system should be an efficient complement to the Chan-Lam type reaction and be useful in synthetic programs.

  15. Copper-catalyzed α-amination of phosphonates and phosphine oxides: a direct approach to α-amino phosphonic acids and derivatives. (United States)

    McDonald, Stacey L; Wang, Qiu


    A direct approach to important α-amino phosphonic acids and its derivatives has been developed by using copper-catalyzed electrophilic amination of α-phosphonate zincates with O-acyl hydroxylamines. This amination provides the first example of CN bond formation which directly introduces acyclic and cyclic amines to the α-position of phosphonates in one step. The reaction is readily promoted at room temperature with as little as 0.5 mol % of catalyst, and demonstrates high efficiency on a broad substrate scope.

  16. 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;


    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...

  17. cis-Diastereoselective synthesis of chroman-fused tetralins as B-ring-modified analogues of brazilin. (United States)

    Gogoi, Dimpee; Devi, Runjun; Pahari, Pallab; Sarma, Bipul; Das, Sajal Kumar


    We have synthesized a series of cis-6a,7,8,12b-tetrahydro-6H-naphtho[2,1-c]chromen-6a-ols as B-ring-modified analogues of (±)-brazilin. A completely regio- and cis-diastereoselective intramolecular Friedel-Crafts epoxy-arene cyclization of 1-tetralone-derived glycidyl ethers catalyzed by Brønsted acids was used as the key step. Our worries concerning the formation of cis-trans product mixtures and their probable conversion to naphthopyran derivatives via dehydration of the tertiary hydroxy group were laid to rest. Additionally, the angular hydroxy group of one of the synthesized products has been reductively removed by a diastereoselective method which should be useful in future for preparing libraries of chroman-fused tetralins with trans-stereochemistry at the ring junction.

  18. 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


    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。

  19. Transesterification catalyzed by polystyrene-supported chymotrypsin in toluene: the effect of neutralization of basic or acidic groups attaching to polystyrene resins. (United States)

    Ohtani, N; Inoue, Y; Kobayashi, A; Sugawara, T


    Crosslinked polystyrene resins containing a low level of either basic or acidic groups were used for supports of alpha-chymotrypsin (CT), which catalyzed the transesterification of N-acetyl-L-phenylalanine ethyl ester (AcPheOEt) with propanol in toluene. With a minimal amount of water, CT was sorbed to the resins, basic or acidic groups of which were partly or fully neutralized by several soluble acids or bases. With an increasing degree of neutralization of basic resins by free acids, the rate of disappearance of AcPheOEt was decreased, whereas the by-product formation of AcPheOH, due to hydrolysis, was considerably suppressed, compared with the ester-exchange product, AcPheOPr. The pK(a) value of the neutralizing acid was also important for both CT activity and reaction selectivity. AcPheOPr was selectively produced at a certain range of pK(a) values. On the other hand, the neutralization of acidic resins with free amines enhanced the CT activity but a strong base promoted the formation of hydrolysis product.

  20. CYP703 is an ancient cytochrome P450 in land plants catalyzing in-chain hydroxylation of lauric acid to provide building blocks for sporopollenin synthesis in pollen. (United States)

    Morant, Marc; Jørgensen, Kirsten; Schaller, Hubert; Pinot, Franck; Møller, Birger Lindberg; Werck-Reichhart, Danièle; Bak, Søren


    CYP703 is a cytochrome P450 family specific to land plants. Typically, each plant species contains a single CYP703. Arabidopsis thaliana CYP703A2 is expressed in the anthers of developing flowers. Expression is initiated at the tetrad stage and restricted to microspores and to the tapetum cell layer. Arabidopsis CYP703A2 knockout lines showed impaired pollen development and a partial male-sterile phenotype. Scanning electron and transmission electron microscopy of pollen from the knockout plants showed impaired pollen wall development with absence of exine. The fluorescent layer around the pollen grains ascribed to the presence of phenylpropanoid units in sporopollenin was absent in the CYP703A2 knockout lines. Heterologous expression of CYP703A2 in yeast cells demonstrated that CYP703 catalyzes the conversion of medium-chain saturated fatty acids to the corresponding monohydroxylated fatty acids, with a preferential hydroxylation of lauric acid at the C-7 position. Incubation of recombinant CYP703 with methanol extracts from developing flowers confirmed that lauric acid and in-chain hydroxy lauric acids are the in planta substrate and product, respectively. These data demonstrate that in-chain hydroxy lauric acids are essential building blocks in sporopollenin synthesis and enable the formation of ester and ether linkages with phenylpropanoid units. This study identifies CYP703 as a P450 family specifically involved in pollen development.

  1. 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


    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.

  2. 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


    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.

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

    Institute of Scientific and Technical Information of China (English)

    凌晨; 黄志军


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

  4. Mechanism of cooperative catalysis in a Lewis acid promoted nickel-catalyzed dual C-H activation reaction. (United States)

    Anand, Megha; Sunoj, Raghavan B


    The mechanism of cooperativity offered by AlMe(3) in a Ni-catalyzed dehydrogenative cycloaddition between substituted formamides and an alkyne is investigated by using DFT(SMD(toluene)/M06/6-31G**) methods. The preferred pathway is identified to involve dual C-H activation, with first a higher barrier formyl C(sp(2))-H oxidative insertion followed by benzylic methyl C(sp(3))-H activation. The cooperativity is traced to be of kinetic origin as evidenced by stabilized transition states when AlMe(3) is bound to the formyl group, particularly in the oxidative insertion step.

  5. Difference analysis of the enzymatic hydrolysis performance of acid-catalyzed steam-exploded corn stover before and after washing with water. (United States)

    Zhu, Junjun; Shi, Linli; Zhang, Lingling; Xu, Yong; Yong, Qiang; Ouyang, Jia; Yu, Shiyuan


    The difference in the enzymatic hydrolysis yield of acid-catalyzed steam-exploded corn stover (ASC) before and after washing with water reached approximately 15 % under the same conditions. The reasons for the difference in the yield between ASC and washed ASC (wASC) were determined through the analysis of the composition of ASC prehydrolyzate and sugar concentration of enzymatic hydrolyzate. Salts produced by neutralization (CaSO4, Na2SO4, K2SO4, and (NH4)2SO4), sugars (polysaccharides, oligosaccharides, and monosaccharides), sugar-degradation products (weak acids and furans), and lignin-degradation products (ethyl acetate extracts and nine main lignin-degradation products) were back-added to wASC. Results showed that these products, except furans, exerted negative effect on enzymatic hydrolysis. According to the characteristics of acid-catalyzed steam explosion pretreatment, the five sugar-degradation products' mixture and salts [Na2SO4, (NH4)2SO4] showed minimal negative inhibition effect on enzymatic hydrolysis. By contrast, furans demonstrated a promotion effect. Moreover, soluble sugars, such as 13 g/L xylose (decreased by 6.38 %), 5 g/L cellobiose (5.36 %), 10 g/L glucose (3.67 %), as well as lignin-degradation products, and ethyl acetate extracts (4.87 %), exhibited evident inhibition effect on enzymatic hydrolysis. Therefore, removal of soluble sugars and lignin-degradation products could effectively promote the enzymatic hydrolysis performance.

  6. Determination of CYP4A11-catalyzed lauric acid 12-hydroxylation by high-performance liquid chromatography with radiometric detection. (United States)

    Crespi, Charles L; Chang, Thomas K H; Waxman, David J


    Lauric acid serves as an endogenous substrate for the cytochrome P450 enzyme CYP4A11. A reverse-phase, high-performance liquid chromatography method is described for the quantification of 12-hydroxylauric acid formed enzymatically by incubation of 14C-labeled lauric acid with cDNA-expressed CYP4A11 or human liver microsomes. Analytical separation is achieved using a C18 column and a gradient of 30% acetonitrile and 2 mM perchloric acid to 100% methanol, using a detection scintillation counter. This method is applicable to enzymatic studies for determination of lauric acid 12-hydroxylation activity.

  7. Preparation of stearoyl lactic acid ester catalyzed by lipases from Rhizomucor miehei and porcine pancreas optimization using response surface methodology. (United States)

    Kiran, K R; Karanth, N G; Divakar, S


    The esterification reaction between stearic acid and lactic acid using Rhizomucor miehei lipase and porcine pancreas lipase was optimized for maximum esterification using response surface methodology. The formation of the ester was found to depend on three parameters namely enzyme/substrate ratio, lactic acid (stearic acid) concentration and incubation period. The maximum esterification predicted by theoretical equations for both lipases matched well with the observed experimental values. In the case of R. miehei lipase, stearoyl lactic acid ester formation was found to increase with incubation period and lactic acid (stearic acid) concentrations with maximum esterification of 26.9% at an enzyme/substrate (E/S) ratio of 125 g mol-1. In the case of porcine pancreas lipase, esterification showed a steady increase with increase in incubation period and lactic acid (stearic acid) concentration independent of the E/S ratios employed. In the case of PPL, a maximum esterification of 18.9% was observed at an E/S ratio of 25 g mol-1 at a lactic acid (stearic acid) concentration of 0.09 M after an incubation period of 72 h.

  8. 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.


    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.

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

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


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

  10. Reusable and Ligand-Free Palladium-Catalyzed Suzuki- Miyaura Cross-Couplings of Aryl Halides with Arylboronic Acids in Tetra-n-butylammonium Bromide

    Institute of Scientific and Technical Information of China (English)

    XIE,Ye-Xiang; WANG,Jian; LI,Jin-Heng; LIANG,Yun


    Ligand-free and reusable palladium-catalyzed Suzuki-Miyaura cross-coupling reaction performed in TBAB (tetra-n-butylammonium bromide) was presented. It was found that the amount of water affected these reactions. Excellent results were obtained when there was w= 1% of water in TBAB. In the presence of 3 mol% of Pd(Oac)2 and 1.5 g of TBAB (containing w= 1% of water), a number of aryl halides were coupled with arylboronic acids smoothly in moderate to excellent yields. Moreover, the Pd(Oac)2/TBAB system among the couplings of aryl bro-mides and activated chlorides could be recovered and reused three times without a loss of catalytic efficiency.

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

    Miyazawa, Toshifumi; Iguchi, Wakana


    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. Cause analysis of the effects of acid-catalyzed steam-exploded corn stover prehydrolyzate on ethanol fermentation by Pichia stipitis CBS 5776. (United States)

    Zhu, Junjun; Yang, Jinlong; Zhu, Yuanyuan; Zhang, Lingling; Yong, Qiang; Xu, Yong; Li, Xin; Yu, Shiyuan


    The prehydrolyzate obtained from acid-catalyzed steam-exploded corn stover (ASC) mainly contains xylose and a number of inhibitory compounds that inhibit ethanol fermentation by Pichia stipitis. In this study, the effects of the ASC prehydrolyzate, specifically those of the carbohydrate-degradation products, lignin-degradation products (which were extracted from ASC prehydrolyzate using ethyl acetate), and six major phenolic compounds (added to pure-sugar media individually or in combination), on ethanol fermentation were investigated. Results indicate that the effects of the carbohydrate-degradation products were negligible (10 h delayed) compared with those of pure-sugar fermentation, whereas the effects of the lignin-degradation products were significant (52 h delayed). Meanwhile, the inhibitory effects of the major phenolic compounds were not caused by certain types of inhibitors, but were due to the synergistic effects of various inhibitors.

  13. 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


    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.

  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: [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)


    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. Solvent effects in acid-catalyzed dehydration of the Diels-Alder cycloadduct between 2,5-dimethylfuran and maleic anhydride (United States)

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


    Dehydration of the cycloadduct produced from the Diels-Alder reaction between 2,5-dimethylfuran and maleic anhydride to 3,6-dimethylphthalic anhydride exemplifies an important step in producing platform chemicals from biomass. The mechanisms of dehydration and catalytic effects of Lewis and Brønsted acids are investigated with density functional theory. The uncatalyzed reaction has a very high activation barrier (68.7 kcal/mol) in the gas phase and it is not significantly affected by solvation. With a Lewis acid catalyst, modeled as an alkali ion, the activation barriers are reduced, but intermediates are also stabilized. The net effect in vacuum is that the energetic span, or apparent activation energy of the catalytic cycle, is 77.9 kcal/mol, even higher than the barrier in the uncatalyzed case. In solution, however, the energetic span is reduced by as much as 20 kcal/mol, due to differences in the solvation energy of the transition states and intermediates. In the case of a Brønsted acid catalyst, modeled as a proton, the gas phase transition state energies are reduced even more than in the Lewis acid case, and there is no strong stabilization of the intermediates. The energetic span in vacuum is only 13.8 kcal/mol and is reduced even further in solution. Brønsted acid catalysis appears to be the preferred mechanism for dehydration of this cycloadduct. Since the Diels-Alder reaction that produced the molecule has previously been shown to be catalyzed by Brønsted acids, this suggests that a single catalyst could be used to accelerate both steps.

  16. One-step production of biodiesel from rice bran oil catalyzed by chlorosulfonic acid modified zirconia via simultaneous esterification and transesterification. (United States)

    Zhang, Yue; Wong, Wing-Tak; Yung, Ka-Fu


    Due to the high content (25-50%) of free fatty acid (FFA), crude rice bran oil usually requires a two steps conversion or one step conversion with very harsh condition for simultaneous esterification and transesterification. In this study, chlorosulfonic acid modified zirconia (HClSO3-ZrO2) with strong acidity and durability is prepared and it shows excellent catalytic activity toward simultaneous esterification and transesterification. Under a relative low reaction temperature of 120 °C, HClSO3-ZrO2 catalyzes a complete conversion of simulated crude rice bran oil (refined oil with 40 wt% FFA) into biodiesel and the conversion yield keep at above 92% for at least three cycles. Further investigation on the tolerance towards FFA and water reveals that it maintains high activity even with the presence of 40 wt% FFA and 3 wt% water. It shows that HClSO3-ZrO2 is a robust and durable catalyst which shows high potential to be commercial catalyst for biodiesel production from low grade feedstock.

  17. 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


    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


    Institute of Scientific and Technical Information of China (English)

    ZHANGYuehua; HUANGWenqiang; 等


    An improved method is developed by using strongly acidic cation exchange resin(001×1,H+ form) as a catalyst for the synthesis of diphenyl 1-(N-benzyloxycarbonyl-amino) alkanephosphonates and 1-(N-benzyloxycarbonylamino) alkanephenyl phosphinic acids in high yields.

  19. 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;


    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...

  20. 对氨基苯磺酸催化合成水杨酸正丁酯%Synthesis of butyl salicylate catalyzed by p-aminobenzene sulfonic acid

    Institute of Scientific and Technical Information of China (English)

    赵卫星; 姜红波


    以正丁醇与水杨酸为原料,采用对氨基苯磺酸为催化剂,通过酯化反应合成了水杨酸正丁酯.考察了酸醇物质的量比、催化剂用量、反应时间对水杨酸正丁酯化收率的影响.结果表明,在回流条件下,当水杨酸的加入量0.20 mol,正丁醇的加入量0.32 mol,即酸与醇物质的量比为1∶1.6,催化剂对氨基苯磺酸用量为0.70 g(相当于5%的酸),反应4.0h时,水杨酸正丁酯收率可达到72.90%.%Synthesis of butyl salicylate from 2-hydroxybenzoic acid and n-butanol catalyzed by p-aminobenzene sulfonic acid was studied.The effects of the molar ratio of 2-hydroxybenzoic acid to n-butanol,the amount of catalyst and the reaction time on the yield was discussed.The results show that when the molar ratio of 2-hydroxybenzoic acid (0.20 mol) to n-butanol (0.32 mol) was 1 ∶ 1.6;the amount of catalyst was 0.70 g (5%,with respect to 2-hydroxybenzoic acid) and the reaction time was 4.0 h under reflux,the yield of butyl salicylate reached 72.90%.

  1. 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


    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%。

  2. 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


    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.

  3. Mass spectrometric identification of an azobenzene derivative produced by smectite-catalyzed conversion of 3-amino-4-hydroxyphenylarsonic acid (United States)

    Wershaw, R. L.; Rutherford, D.W.; Rostad, C.E.; Garbarino, J.R.; Ferrer, I.; Kennedy, K.R.; Momplaisir, G.-M.; Grange, A.


    The compound 3-amino-4-hydroxyphenylarsonic acid (3-amino-HPAA) reacts with smectite to form a soluble azobenzene arsonic acid compound. This reaction is of particular interest because it provides a possible mechanism for the formation of a new type of arsenic compound in natural water systems. 3-Amino-HPAA is a degradation product excreted by chickens that are fed rations amended with roxarsone. Roxarsone is used to control coccidial intestinal parasites in most of the broiler chickens grown in the United States. The structure of the azobenzene arsonic acid compound was first inferred from negative-ion and positive-ion low-resolution mass-spectrometric analyses of the supernatant of the smectite suspension. Elemental composition of the parent ion determined by high-resolution positive-ion mass spectrometric measurements was consistent with the proposed structure of the azobenzene arsonic acid compound. Published by Elsevier Science B.V.

  4. Enzyme-catalyzed Transesterification of Unusual Substrate: Synthesis of Acyclovir and L-ascorbic Acid (Vitamin C) Vinyl Esters

    Institute of Scientific and Technical Information of China (English)


    The synthesis of acyclovir and L-ascorbic acid with divinyladipate was performed with alkaline protease from Bacillus subtilis and lipase from Lipozyme (immobilized from Mucor miehei) in different anhydrous organic solvents. Two corresponding derivatives were obtained.

  5. 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


    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.

  6. 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


    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.

  7. Evolution of Diterpene Metabolism: Sitka Spruce CYP720B4 Catalyzes Multiple Oxidations in Resin Acid Biosynthesis of Conifer Defense against Insects1[C][W][OA (United States)

    Hamberger, Björn; Ohnishi, Toshiyuki; Hamberger, Britta; Séguin, Armand; Bohlmann, Jörg


    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. Rh(I)-Catalyzed 1,4-Conjugate Addition of Alkenylboronic Acids to a Cyclopentenone Useful for the Synthesis of Prostaglandins. (United States)

    Syu, Jin-Fong; Wang, Yun-Ting; Liu, Kung-Cheng; Wu, Ping-Yu; Henschke, Julian P; Wu, Hsyueh-Liang


    An efficient and trans-diastereoselective Rh(I)-catalyzed 1,4-conjugate addition reaction of alkenylboronic acids and a homochiral (R)-4-silyloxycyclopentenone useful for the synthesis of derivatives of prostaglandins E and F is described for the first time. The reaction functions under mild conditions and is particularly rapid (≤6 h) under low power (50 W) microwave irradiation at 30 °C in MeOH in the presence of a catalytic amount of KOH. Under these conditions, 3 mol % of [RhCl(COD)]2 is typically required to produce high yields. The method also functions without microwave irradiation at 3 °C in the presence of a stoichiometric amount of KOH. Under these conditions, only 1.5 mol % of [RhCl(COD)]2 is needed, but the reaction is considerably slower. The method accepts a range of aryl- and alkyl-substituted alkenylboronic acids, and its utility has been demonstrated by the synthesis of PGF2α (dinoprost) and tafluprost.

  9. Lipase-catalyzed preparation of diacylglycerol-enriched oil from high-acid rice bran oil in solvent-free system. (United States)

    Song, Zhihua; Liu, Yuanfa; Jin, Qingzhe; Li, Lei; Wang, Xingguo; Huang, Jianhua; Liu, Ruijie


    The ability of immobilized lipase from Rhizomucor miehei (Lipozyme RM IM) to catalyze the reaction of high-acid rice bran oil (RBO) and monoglyceride (MG) for diacylglycerol-enriched rice bran oil (RBO-DG) preparation was investigated. The effects of substrate ratio, reaction temperature, time, and enzyme load on the respective content of free fatty acid (FFA) and DG in the final RBO-DG products was investigated. Enzyme screening on the reaction was also investigated. Response surface methodology (RSM) was used to optimize the effects of the reaction temperature (50-70 °C), the enzyme load (2-6 %; relative to the weight of total substrates), and the reaction time (4-8 h) on the respective content of FFA and DG. Validation of the RSM model was verified by the good agreement between the experimental and the predicted values. The optimum preparation conditions were as follows: MG/RBO, 0.25; temperature, 56 °C; enzyme load, 4.77 %; and reaction time, 5.75 h. Under the suggested conditions, the respective content of FFA and DG was 0.28 and 27.98 %, respectively. Repeated reaction tests indicated that Lipozyme RM IM could be used nine times under the optimum conditions with 90 % of its original catalytic activity still retained.

  10. 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


    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.

  11. Studies of manufacturing controlled-release graphene acid and catalyzing synthesis of chalcone with Claisen-Schmidt condensation reaction (United States)

    Li, Jihui; Feng, Jia; Li, Mei; Wang, Qiaolian; Su, Yumin; Jia, Zhixin


    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.

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

  13. Molecular cloning of CYP76B9, a cytochrome P450 from Petunia hybrida, catalyzing the omega-hydroxylation of capric acid and lauric acid. (United States)

    Imaishi, Hiromasa; Petkova-Andonova, Mariana


    A cDNA encoding a cytochrome P450 (CYP76B9) was isolated from Petunia hybrida. Northern blot analysis revealed preferential expression of the gene in flowers and leaves. The recombinant yeast microsomes expressing CYP76B9 was allowed to react with capric acid and lauric acid as substrates. One major metabolite was produced from each fatty acid after incubation with yeast microsomes expressing CYP76B9. The metabolites were identified by gas chromatography-mass spectrometry (GC-MS) as omega-hydroxy capric acid and omega-hydroxy lauric acid. The kinetic parameters of the reactions were Km=9.4 microM and Vmax=13.6 mol min(-1) per mol of P450 for capric acid, and Km=5.7 microM and Vmax=19.1 mol min(-1) per mol of P450 for lauric acid. We found that the omega-hydroxy metabolites of capric acid and lauric acid can affect the plant growth of Arabidopsis thaliana. Plants grown in the presence of omega-hydroxy fatty acids exhibited shorter root length than control plants with the corresponding non-hydroxylated fatty acids.


    NARCIS (Netherlands)



    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

  15. Polycondensation of dicarboxylic acids and diols in water catalyzed by surfactant-combined catalysts and successive chain extension. (United States)

    Takasu, Akinori; Takemoto, Aki; Hirabayashi, Tadamichi


    Direct dehydration polycondensation of dicarboxylic acids and alcohols was carried out by surfactant-combined Brønsted and Lewis acids. This procedure did not require the removal of water, because the esterification was established at the interface of the emulsion in water. Emulsion polycondensations of 1,9-nonanediol (1,9-ND) and dodecanedioic acid (DDA) (the molar ratio of dicarboxylic acid to diol = 1:1) were carried out at 80 degrees C for 48 h in the presence of 16 wt % DBSA. The corresponding polyester (M(w) = 10.1 x 10(3)) was obtained in an excellent yield (99%). Chain extension in the emulsion was carried out using hexamethylene diisocyanate as the chain extender. SEC measurements indicated the expected shift to higher molecular weight region (M(w) = 11.4 x 10(3), M(w)/M(n) = 3.4) compared with parent polyester (M(w) = 4.5 x 10(3), M(w)/M(n) = 2.2).

  16. 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;


    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...

  17. 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)


    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.

  18. 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;


    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...

  19. Synthesis of structured triacylglycerols containing caproic acid by lipase-catalyzed acidolysis: Optimization by response surface methodology

    DEFF Research Database (Denmark)

    Zhou, D.Q.; Xu, Xuebing; Mu, Huiling;


    -r = 2-6 mol/mol; and W-c = 2-12 wt %. The biocatalyst was Lipozyme RM IM, in which Rhizomucor miehei lipase is immobilized on a resin. The incorporation of caproic acid into rapeseed oil was the main monitoring response. In addition, the contents of mono-incorporated structured triacylglycerols and di...

  20. Horseradish peroxidase-catalyzed oligomerization of ferulic acid on a template of a tyrosine-containing tripeptide

    NARCIS (Netherlands)

    Oudgenoeg, G.; Dirksen, E.; Ingemann, S.; Hilhorst, R.; Gruppen, H.; Boeriu, C.G.; Piersma, S.R.; Berkel, W.J.H. van; Laane, C.; Voragen, A.G.J.


    Ferulic acid (FA) is an abundantly present phenolic constituent of plant cell walls. Kinetically controlled incubation of FA and the tripeptide Gly-Tyr-Gly (GYG) with horseradish peroxidase and H2O2 yielded a range of new cross-linked products. Two predominant series of hetero-oligomers of FA linked

  1. Highly enantioselective aza-Diels-Alder reaction of 1-azadienes with enecarbamates catalyzed by chiral phosphoric acids. (United States)

    He, Long; Laurent, Gregory; Retailleau, Pascal; Folléas, Benoît; Brayer, Jean-Louis; Masson, Géraldine


    On demand: A highly enantio- and diastereoselective synthesis of 6-amino- trisubstituted tetrahydropyridine compounds has been developed through the inverse-electron-demand aza-Diels-Alder reaction of N-aryl α,β-unsaturated ketimines with enecarbamates (E)-1. Chiral phosphoric acid catalysts achieve simultaneous activation of both the 1-azadiene and dienophile partners.

  2. Br(o)nsted acidic ionic liquid catalyzed highly efficient synthesis of chromeno pyrimidinone derivatives and their antimicrobial activity

    Institute of Scientific and Technical Information of China (English)

    Janardhan Banothu; Rajitha Bavanthula


    A series of 8,9-dihydro-2-(2-oxo-2H-chromen-3-yl)-5-aryl-3H-chromeno[2,3-d]pyrimidine-4,6(5H,7H)-diones (5a-j)have been synthesized by the reaction of 2-amino-5,6,7,8-tetrahydro-5-oxo-4-aryl-4H-chromene-3-carbonitrile (4a-j) with coumarin-3-catboxylic acid under neat conditions employing Brφnsted acidic ionic liquid (4-sulfobutyl)tris(4-sulfophenyl)phosphonium hydrogen sulfate as catalyst.Structures of all the compounds were established on the basis of analytical and spectroscopic data.All the compounds were evaluated for their in vitro antimicrobial activity against different bacterial and fungal strains.

  3. Polyene Formation Catalyzed by Phosphotungstic Acid and Aluminum Chloride in Thin Films of Poly(Vinyl Alcohol) (United States)

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


    Formation of linear polyenes -(CH=CH) n - during thermal dehydration of thin layers (9-20 μm) of poly(vinyl alcohol) containing phosphotungstic-acid and aluminum-chloride catalysts was investigated. It was found that the concentration of long-chain ( n ≥ 8) polyenes in films containing phosphotungstic acid increased smoothly with increasing annealing time although the kinetics of the dehydration were independent of the film thickness. The polyene ( n ≥ 8) formation rate in films containing aluminum chloride dropped quickly with decreasing film thickness and increasing annealing time. As a result, long-chain polyenes practically did not form regardless of the annealing time for a film thickness of 11 μm.

  4. Lipase-Catalyzed Production of 6-O-cinnamoyl-sorbitol from D-sorbitol and Cinnamic Acid Esters. (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


    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.

  5. Rh(I)-Catalyzed Coupling of Conjugated Enynones with Arylboronic Acids: Synthesis of Furyl-Containing Triarylmethanes. (United States)

    Xia, Ying; Chen, Li; Qu, Peiyuan; Ji, Guojing; Feng, Sheng; Xiao, Qing; Zhang, Yan; Wang, Jianbo


    Conjugated enynones can be used as carbene precursors to couple with arylboronic acids in the presence of Rh(I) catalyst. This reaction shows good functional compatibility, and a range of furyl-containing triarylmethanes can be smoothly synthesized from easily available starting materials under mild reaction conditions. Mechanistically, the formation of Rh(I) (2-furyl)carbene species and the subsequent carbene migratory insertion are proposed as the key steps in this reaction.

  6. A Facile Aqueous Synthesis of Bis(indol-3-yl)alkanes Cata-lyzed by Dodecylbenzenesulfonic Acid

    Institute of Scientific and Technical Information of China (English)

    PENG,Yi-Yuan; ZHANG,Qiu-Lan; YUAN,Jian-Jun; CHENG,Jin-Pei


    An environmentally friendly synthetic method for bis(indol-3-yl)alkane derivatives has been developed. In the presence of 10 mol% of dodecylbenzenesulfonic acid (DBSA), electrophilic substitution reaction of indoles with aldehydes or ketones proceeded smoothly in water, giving rise to the corresponding bis(indol-3-yl)alkanes in good to excellent yields. The use of inexpensive and easily available catalyst, mild reaction conditions and simple work-up procedure made this protocol practical and economically attractive.

  7. 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


    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.

  8. Arabidopsis cytochrome P450s that catalyze the first step of tryptophan-dependent indole-3-acetic acid biosynthesis


    Hull, Anna K.; Vij, Rekha; Celenza, John L.


    Plants synthesize numerous secondary metabolites that are used as developmental signals or as defense against pathogens. Tryptophan (Trp)-derived secondary metabolites include camalexin, indole glucosinolates, and indole-3-acetic acid (IAA); however, the steps in their synthesis from Trp or its precursors remain unclear. We have identified two Arabidopsis cytochrome P450s (CYP79B2 and CYP79B3) that can convert Trp to indole-3-acetaldoxime (IAOx), a precursor to IAA and indole glucosinolates.

  9. Cu(I)-catalyzed (11)C carboxylation of boronic acid esters: a rapid and convenient entry to (11)C-labeled carboxylic acids, esters, and amides. (United States)

    Riss, Patrick J; Lu, Shuiyu; Telu, Sanjay; Aigbirhio, Franklin I; Pike, Victor W


    Rapid and direct: the carboxylation of boronic acid esters with (11)CO(2) provides [(11)C]carboxylic acids as a convenient entry into [(11)C]esters and [(11)C]amides. This conversion of boronates is tolerant to diverse functional groups (e.g., halo, nitro, or carbonyl).

  10. 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.


    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

  11. Microwave-Assisted Resolution of α-Lipoic Acid Catalyzed by an Ionic Liquid Co-Lyophilized Lipase

    Directory of Open Access Journals (Sweden)

    Ning Liu


    Full Text Available The combination of the ionic liquid co-lyophilized lipase and microwave irradiation was used to improve enzyme performance in enantioselective esterification of α-lipoic acid. Effects of various reaction conditions on enzyme activity and enantioselectivity were investigated. Under optimal condition, the highest enantioselectivity (E = 41.2 was observed with a high enzyme activity (178.1 μmol/h/mg when using the ionic liquid co-lyophilized lipase with microwave assistance. Furthermore, the ionic liquid co-lyophilized lipase exhibited excellent reusability under low power microwave.

  12. Enantioselective Cycloaddition Reactions Catalyzed by BINOL-Derived Phosphoric Acids and N-Triflyl Phosphoramides: Recent Advances. (United States)

    Held, Felix E; Grau, Dominik; Tsogoeva, Svetlana B


    Over the last several years there has been a huge increase in the development and applications of new efficient organocatalysts for enantioselective pericyclic reactions, which represent one of the most powerful types of organic transformations. Among these processes are cycloaddition reactions (e.g., [3+2]; formal [3+3]; [4+2]; vinylogous [4+2] and 1,3-dipolar cycloadditions), which belong to the most utilized reactions in organic synthesis of complex nitrogen- and oxygen-containing heterocyclic molecules. This review presents the breakthrough realized in this field using chiral BINOL-derived phosphoric acids and N-triflyl phosphoramide organocatalysts.

  13. 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


    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.

  14. Lipase-catalyzed esterification of ferulic acid with lauryl alcohol in ionic liquids and antibacterial properties in vitro against three food-related bacteria. (United States)

    Shi, Yu-Gang; Wu, Yu; Lu, Xu-Yang; Ren, Yue-Ping; Wang, Qi; Zhu, Chen-Min; Yu, Di; Wang, He


    Lauryl ferulate (LF) was synthesized through lipase-catalyzed esterification of ferulic acid (FA) with lauryl alcohol in a novel ionic liquid ([(EO)-3C-im][NTf2]), and its antibacterial activities was evaluated in vitro against three food-related bacteria. [(EO)-3C-im][NTf2] was first synthesized through incorporating alkyl ether moiety into the double imidazolium ring. [(EO)-3C-im][NTf2] containing hexane was found to be the most suitable for this reaction. The effects of various parameters were studied, and the maximum yield of LF (90.1%) was obtained in the optimum reaction conditions, in [(EO)-3C-im][NTf2]/hexane (VILs:Vhexane=1:1) system, 0.08mmol/mL of FA concentration, 50mg/mL Novozym 435, 60°C. LF exhibited a stronger antibacterial activity against Gram-negative (25 mm) than Gram-positive (21.5-23.2 mm) bacteria. The lowest MIC value was seen for E. coli (1.25mM), followed by L. Monocytogenes (2.5mM) and S.aureus (5mM). The MBCs for L. Monocytogenes, S.aureus and E. coli were 10, 20 and 5mM.

  15. The effect of metal ions as co-catalysts on acidic ionic liquid catalyzed single-step saccharification of corn stover in water. (United States)

    Wiredu, Bernard; Amarasekara, Ananda S


    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.

  16. Characteristics of structured lipid prepared by lipase-catalyzed acidolysis of roasted sesame oil and caprylic acid in a bench-scale continuous packed bed reactor. (United States)

    Kim, Byung Hee; Akoh, Casimir C


    Structured lipid (SL) was prepared from roasted sesame oil and caprylic acid (CA) by Rhizomucor miehei lipase-catalyzed acidolysis in a bench-scale continuous packed bed reactor. Total incorporation and acyl migration of CA in the SL were 42.5 and 3.1 mol %, respectively, and the half-life of the lipase was 19.2 days. The SL displayed different physical and chemical properties, less saturated dark brown color, lower viscosity, lower melting and crystallization temperature ranges, higher melting and crystallization enthalpies, higher smoke point, higher saponification value, and lower iodine value, in comparison to those of unmodified sesame oil. The oxidative stability of purified SL was lower than that of sesame oil. There were no differences in the contents of unsaponifiables including tocopherols and phytosterols. However, total sesame lignans content was decreased in SL due to the loss of sesamol when compared to sesame oil. Most of the 70 volatiles present in roasted sesame oil were removed from SL during short-path distillation of SL. These results indicate that the characteristics of SL are different from those of original sesame oil in several aspects except for the contents of tocopherols and phytosterols.

  17. Kinetics of an acid-base catalyzed reaction (aspartame degradation) as affected by polyol-induced changes in buffer pH and pK values. (United States)

    Chuy, S; Bell, L N


    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.

  18. 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


    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.

  19. Synthesis of styrenes by palladium(II)-catalyzed vinylation of arylboronic acids and aryltrifluoroborates by using vinyl acetate. (United States)

    Lindh, Jonas; Sävmarker, Jonas; Nilsson, Peter; Sjöberg, Per J R; Larhed, Mats


    One Heck of a reaction: Treatment of arylboronic acids or aryltrifluoroborates with vinyl acetate by using a palladium(II) catalyst gives the corresponding styrenes (see scheme). No palladium reoxidant is needed and the vinylation is performed under non-inert conditionsReactions of aromatic and heteroaromatic boronic acids or aryltrifluoroborate salts with vinyl acetate in the presence of a palladium(II) catalyst give the corresponding styrenes in good yields. This Heck reaction proceeds with microwave heating in less than 30 min at 140 degrees C in the absence of base and tolerates a variety of substituents. No palladium reoxidant is needed and the vinylation is performed under non-inert conditions. Mass spectrometry (electrospray ionization mass spectrometry (ESIMS) and tandem mass spectrometry (MS/MS)) was used to identify cationic palladium-containing complexes in ongoing reactions. The key intermediates that have been detected, together with experiments that used deuterated vinyl acetate, support the existence of catalytically active palladium hydride species, and that it is the arylation of ethylene, not vinyl acetate, which generates the styrene product. The mechanism of the reaction is discussed in terms of the palladium(II) intermediates mentioned above.

  20. Studies of reaction variables for lipase-catalyzed production of alpha-linolenic acid enriched structured lipid and oxidative stability with antioxidants. (United States)

    Mitra, Kanika; Shin, Jung-Ah; Lee, Jeung-Hee; Kim, Seong-Ai; Hong, Soon-Taek; Sung, Chang-Keun; Xue, Cheng Lian; Lee, Ki-Teak


    Alpha-linolenic acid (ALA) enriched structured lipid (SL) was produced by lipase-catalyzed interesterification from perilla oil (PO) and corn oil (CO). The effects of different reaction conditions (substrate molar ratio [PO/CO 1:1 to 1:3], reaction time [0 to 24 h], and reaction temperature [55 to 65 °C]) were studied. Lipozyme RM IM from Rhizomucor miehei was used as biocatalyst. We obtained 32.39% of ALA in SL obtained under the optimized conditions (molar ratio-1:1 [PO:CO], temperature-60 °C, reaction time-15 h). In SL, the major triacylglycerol (TAG) species (linolenoyl-linolenoyl-linolenoyl glycerol [LnLnLn], linolenoyl-linolenoyl-linoleoyl glycerol [LnLnL]) mainly from PO and linoleoyl-linoleoyl-oleoyl glycerol (LLO), linoleoyl-oleoyl-oleoyl glycerol (LOO), palmitoyl-linoleoyl-oleoyl glycerol (PLO) from CO decreased while linolenoyl-linolenoyl-oleoyl glycerol (LnLnO) (18.41%), trilinolein (LLL) (9.06%), LLO (16.66%), palmitoyl-linoleoyl-linoleoyl glycerol (PLL) (9.69%) were increased compared to that of physical blend. Total tocopherol content (28.01 mg/100 g), saponification value (SV) (192.2), and iodine value (IV) (161.9) were obtained. Furthermore, oxidative stability of the SL was also investigated by addition of 3 different antioxidants (each 200 ppm of rosemary extract [SL-ROS], BHT [SL-BHT], catechin [SL-CAT]) was added into SL and stored in 60 °C oven for 30 d. 2-Thiobabituric acid-reactive substances (TBARS) value was 0.16 mg/kg in SL-CAT and 0.18 mg/kg in SL-ROS as compared with 0.22 mg/kg in control (SL) after oxidation. The lowest peroxide value (POV, 200.9 meq/kg) and longest induction time (29.88 h) was also observed in SL-CAT.

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

    Directory of Open Access Journals (Sweden)

    Baeza-Jiménez, R.


    Full Text Available Structured phosphatidylcholine (SPC was successfully produced via immobilized phospholipase A1 (PLA1catalyzed 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 into PC. The maximum incorporation of CLA achieved was ca. 90% for 24 h of reaction at 50 °C and 200 rpm, using a 1:4 substrate molar ratio and an enzyme loading of 15%.

    Fosfatidilcolina estructurada (SPC fue producida por acidólisis de fosfatidilcolina (PC y ácido linoleico conjugado (CLA usando fosfolipasa A1 (PLA1 inmovilizada. Los efectos de carga de enzima (2, 5, 10, 15 y 20%, respecto al peso de los sustratos, temperatura (20, 30, 40, 50 y 60 °C y la relación molar de sustratos (1:2, 1:4, 1:6, 1:8 y 1:10, PC/CLA fueron evaluados para alcanzar la más elevada incorporación de CLA en PC. La máxima incorporación de CLA obtenida fue de 90% a 50 °C y 200 rpm, para una relación molar 1:4 con una carga de enzima de 15% después de 24 h.

  2. 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


    @@ 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.

  3. 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


    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.

  4. 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


    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.

  5. Horseradish peroxidase-catalyzed synthesis of poly(thiophene-3-boronic acid) biocomposites for mono-/bi-enzyme immobilization and amperometric biosensing. (United States)

    Huang, Yi; Wang, Wen; Li, Zou; Qin, Xiaoli; Bu, Lijuan; Tang, Zhiyong; Fu, Yingchun; Ma, Ming; Xie, Qingji; Yao, Shouzhuo; Hu, Jiming


    We report here on a facile enzymatic polymerization protocol to prepare enzyme-poly(thiophene-3-boronic acid) (PTBA) polymeric biocomposites (PBCs) for high-performance mono-/bi-enzyme amperometric biosensing. Horseradish peroxidase (HRP)-catalyzed polymerization of thiophene-3-boronic acid (TBA) monomer was conducted in aqueous solution containing HRP (or plus glucose oxidase (GOx)) by either directly added or GOx-glucose generated oxidant H2O2. The mono-/bi-enzyme amperometric biosensors were prepared simply by casting the dialysis-isolated PBCs on Au-plated Au electrode (Auplate/Au), followed by coating with an outer-layer chitosan (CS) film. The boronic acid residues are capable of covalent bonding with enzyme at the glycosyl sites (boronic acid-diols interaction), which should less affect the enzymatic activity as compared with the common cases of covalent bonding at the peptide chains, and UV-vis spectrophotometric tests confirmed that the encapsulated HRP almost possesses its pristine enzymatic specific activity. The enzyme electrodes were studied by cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry in the presence of Fe(CN)6(4-) mediator. The CS/HRP-PTBA/Auplate/Au electrode responded linearly to H2O2 concentration from 1 to 300 μM with a sensitivity of 390 μA mM(-1)cm(-2) and a limit of detection (LOD) of 0.1 μM. The bienzyme CS/GOx-HRP-PTBA(H2O2)/Auplate/Au electrode responded linearly to glucose concentration from 5 μM to 0.83 mM with a sensitivity of 75.1 μA mM(-1)cm(-2) and a LOD of 1 μM, and it is found here that the use of Fe(CN)6(4-) that can only efficiently mediate HRP favorably avoids the "unusual amperometric responses" observed when other mediators that can efficiently turn over both HRP and GOx are used.

  6. Advanced Model Compounds for Understanding Acid-Catalyzed Lignin Depolymerization: Identification of Renewable Aromatics and a Lignin-Derived Solvent. (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


    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.

  7. 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.


    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.

  8. A kinetic study on the Novozyme 435-catalyzed esterification of free fatty acids with octanol to produce octyl esters. (United States)

    Chowdhury, Avisha; Mitra, Debarati


    Octyl esters can serve as an important class of biolubricant components replacing their mineral oil counterparts. The purpose of the current work was to investigate the enzymatic esterification reaction of free fatty acids (FFA, from waste cooking oil) with octanol in a solvent-free system using a commercial lipase Novozyme 435. It was found that the esterificaton reaction followed the Ping-pong bi-bi kinetics with no inhibition by substrates or products within the studied concentration range. The maximum reaction rate was estimated to be 0.041 mol L(-1) g(-1) h(-1) . Additionally, the stability of Novozyme 435 in the current reaction system was studied by determining its activity and final conversion of FFA to esters after 12 successive utilizations. Novozyme 435 exhibited almost 100% enzyme activity up to 7 cycles of reaction and gradually decreased (by 5%) thereafter. The kinetic parameters evaluated from the study shall assist in the design of reactors for large-scale production of octyl esters from a cheap biomass source. The enzyme reusability data can further facilitate mass production by curtailing the cost of expensive enzyme consumption.

  9. Lipozyme RM IM-catalyzed acidolysis of Cinnamomum camphora seed oil with oleic acid to produce human milk fat substitutes enriched in medium-chain fatty acids. (United States)

    Zou, Xian-Guo; Hu, Jiang-Ning; Zhao, Man-Li; Zhu, Xue-Mei; Li, Hong-Yan; Liu, Xiao-Ru; Liu, Rong; Deng, Ze-Yuan


    In the present study, a human milk fat substitute (HMFS) enriched in medium-chain fatty acids (MCFAs) was synthesized through acidolysis reaction from Cinnamomum camphora seed oil (CCSO) with oleic acid in a solvent-free system. A commercial immobilized lipase, Lipozyme RM IM, from Rhizomucor miehei, was facilitated as a biocatalyst. Effects of different reaction conditions, including substrate molar ratio, enzyme concentration, reaction temperature, and reaction time were investigated using response surface methodology (RSM) to obtain the optimal oleic acid incorporation. After optimization, results showed that the maximal incorporation of oleic acid into HMFS was 59.68%. Compared with CCSO, medium-chain fatty acids at the sn-2 position of HMFS accounted for >70%, whereas oleic acid was occupied predominantly at the sn-1,3 position (78.69%). Meanwhile, triacylglycerol (TAG) components of OCO (23.93%), CCO (14.94%), LaCO (13.58%), OLaO (12.66%), and OOO (11.13%) were determined as the major TAG species in HMFS. The final optimal reaction conditions were carried out as follows: substrate molar ratio (oleic acid/CCSO), 5:1; enzyme concentration, 12.5% (w/w total reactants); reaction temperature, 60 °C; and reaction time, 28 h. The reusability of Lipozyme RM IM in the acidolysis reaction was also evaluated, and it was found that it could be reused up to 9 times without significant loss of activities. Urea inclusion method was used to separate and purify the synthetic product. As the ratio of HMFS/urea increased to 1:2, the acid value lowered to the minimum. In a scale-up experiment, the contents of TAG and total tocopherols in HMFS (modified CCSO) were 77.28% and 12.27 mg/100 g, respectively. All of the physicochemical indices of purified product were within food standards. Therefore, such a MCFA-enriched HMFS produced by using the acidolysis method might have potential application in the infant formula industry.

  10. 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


    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。

  11. 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


    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%.

  12. Effect of acid-catalyzed formation rates of benzimidazole-linked polymers on porosity and selective CO2 capture from gas mixtures. (United States)

    Altarawneh, Suha; İslamoğlu, Timur; Sekizkardes, Ali Kemal; El-Kaderi, Hani M


    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.

  13. An alternative reaction for heme degradation catalyzed by the Escherichia coli O157:H7 ChuS protein: Release of hematinic acid, tripyrrole and Fe(III). (United States)

    Ouellet, Yannick H; Ndiaye, Cheikh Tidiane; Gagné, Stéphane M; Sebilo, Anne; Suits, Michael D L; Jubinville, Éric; Jia, Zongchao; Ivancich, Anabella; Couture, Manon


    As part of the machinery to acquire, internalize and utilize heme as a source of iron from the host, some bacteria possess a canonical heme oxygenase, where heme plays the dual role of substrate and cofactor, the later catalyzing the cleavage of the heme moiety using O2 and electrons, and resulting in biliverdin, carbon monoxide and ferrous non-heme iron. We have previously reported that the Escherichia coli O157:H7 ChuS protein, which is not homologous to heme oxygenases, can bind and degrade heme in a reaction that releases carbon monoxide. Here, we have pursued a detailed characterization of such heme degradation reaction using stopped-flow UV-visible absorption spectrometry, the characterization of the intermediate species formed in such reaction by EPR spectroscopy and the identification of reaction products by NMR spectroscopy and Mass spectrometry. We show that hydrogen peroxide (in molar equivalent) is the key player in the degradation reaction, at variance to canonical heme oxygenases. While the initial intermediates of the reaction of ChuS with hydrogen peroxide (a ferrous keto π neutral radical and ferric verdoheme, both identified by EPR spectroscopy) are in common with heme oxygenases, a further and unprecedented reaction step, involving the cleavage of the porphyrin ring at adjacent meso-carbons, results in the release of hematinic acid (a monopyrrole moiety identified by NMR spectroscopy), a tripyrrole product (identified by Mass spectrometry) and non-heme iron in the ferric oxidation state (identified by EPR spectroscopy). Overall, the unprecedented reaction of E. coli O157:H7 ChuS provides evidence for a novel heme degradation activity in a Gram-negative bacterium.

  14. Horseradish peroxidase-catalyzed polymerization of L-DOPA for mono-/bi-enzyme immobilization and amperometric biosensing of H2O2 and uric acid. (United States)

    Dai, Mengzhen; Huang, Ting; Chao, Long; Xie, Qingji; Tan, Yueming; Chen, Chao; Meng, Wenhua


    Horseradish peroxidase (HRP)-catalyzed polymerization of L-DOPA (vs. dopamine) in the presence of H2O2 (and uricase (UOx)) was exploited to immobilize mono-/bi-enzymes for hydroquinone-mediated amperometric biosensing of H2O2 and uric acid (UA). The relevant polymeric biocomposites (PBCs) were prepared in phosphate buffer solution containing HRP and L-DOPA (or plus UOx) after adding H2O2. The mono-/bi-enzyme amperometric biosensors were prepared simply by casting some of the PBCs on Au-plated Au (Au(plate)/Au) electrodes, followed by coating with an outer-layer chitosan (CS) film for each. UV-vis spectrophotometry, scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy were used for film characterization and/or process monitoring. The HRP immobilized by enzyme catalysis well preserved its bioactivity, as confirmed by UV-vis spectrophotometry. Under optimized conditions, the monoenzyme CS/HRP-poly(L-DOPA) (PD)/Au(plate)/Au electrode potentiostated at -0.1V responded linearly to H2O2 concentration from 0.001 to 1.25mM with a sensitivity of 700μA mM(-1)cm(-2) and a limit of detection (LOD) of 0.1μM, and the bienzyme CS/UOx-HRP-PD/Au(plate)/Au electrode at -0.1V responded linearly to UA concentration from 0.001 to 0.4mM with a sensitivity of 349μA mM(-1)cm(-2) and a LOD of 0.1μM. The mono-/bi-enzyme biosensors based on biosynthesized PD performed better than many reported analogues and those based on similarly biosynthesized polydopamine.

  15. 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 (United States)

    Socki, Richard A.; Fu, Qi; Niles, Paul B.; Gibson, Everett K., Jr.


    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.

  16. Inhibition of lactoperoxidase-catalyzed 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) and tyrosine oxidation by tyrosine-containing random amino acid copolymers. (United States)

    Clausen, Morten R; Skibsted, Leif H; Stagsted, Jan


    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.

  17. 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


    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.

  18. Palladium-phosphinous acid complexes catalyzed Suzuki cross-coupling reaction of heteroaryl bromides with phenylboronic acid in water/alcoholic solvents. (United States)

    Li, Ben; Wang, Cuiping; Chen, Guang; Zhang, Zhiqiang


    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 POPd1 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.

  19. 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


    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.

  20. Catalytic Conversion of Bio-Oil to Oxygen-Containing Fuels by Acid-Catalyzed Reaction with Olefins and Alcohols over Silica Sulfuric Acid

    Directory of Open Access Journals (Sweden)

    Qingwen Wang


    Full Text Available Crude bio-oil from pine chip fast pyrolysis was upgraded with olefins (1-octene, cyclohexene, 1,7-octadiene, and 2,4,4-trimethylpentene plus 1-butanol (iso-butanol, t-butanol and ethanol at 120 °C using a silica sulfuric acid (SSA catalyst that possesses a good catalytic activity and stability. Gas chromatography-mass spectrometry (GC-MS, Fourier transform infrared spectroscopy (FT-IR and proton nuclear magnetic resonance (1H-NMR analysis showed that upgrading sharply increased ester content and decreased the amounts of levoglucosan, phenols, polyhydric alcohols and carboxylic acids. Upgrading lowered acidity (pH value rose from 2.5 to >3.5, removed the unpleasant odor and increased hydrocarbon solubility. Water content dramatically decreased from 37.2% to about 7.0% and the heating value increased from 12.6 MJ·kg−1 to about 31.9 MJ·kg−1. This work has proved that bio-oil upgrading with a primary olefin plus 1-butanol is a feasible route where all the original heating value of the bio-oil plus the added olefin and alcohol are present in the resulting fuel.

  1. 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.


    ,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...

  2. Un-catalyzed peptide bond formation between two monomers of glycine, alanine, serine, threonine, and aspartic acid in gas phase: a density functional theory study (United States)

    Bhunia, Snehasis; Singh, Ajeet; Ojha, Animesh K.


    In the present report, un-catalyzed peptide bond formation between two monomers of glycine (Gly), alanine (Ala), serine (Ser), threonine (Thr), and aspartic acid (Asp) has been investigated in gas phase via two steps reaction mechanism and concerted mechanism at B3LYP/6-31G(d,p) and M062X/6-31G(d,p) level of theories. The peptide bond is formed through a nucleophilic reaction via transition states, TS1 and TS2 in stepwise mechanism. The TS1 reveals formation of a new C-N bond while TS2 illustrate the formation of C=O bond. In case of concerted mechanism, C-N bond is formed by a single four-centre transition state (TS3). The energy barrier is used to explain the involvement of energy at each step of the reaction. The energy barrier (20-48 kcal/mol) is required for the transformation of reactant state R1 to TS1 state and intermediate state I1 to TS2 state. The large value of energy barrier is explained in terms of distortion and interaction energies for stepwise mechanism. The energy barrier of TS3 in concerted mechanism is very close to the energy barrier of the first transition state (TS1) of the stepwise mechanism for the formation of Gly-Gly and Ala-Ala di- peptide. However, in case of Ser-Ser, Thr-Thr and Asp-Asp di-peptide, the energy barrier of TS3 is relatively high than that of the energy barrier of TS1 calculated at B3LYP/6-31G(d,p) and M062X/6-31G(d,p) level of theories. In both the mechanisms, the value of energy barrier calculated at B3LYP/6-31G(d,p) level of theory is greater than that of the value calculated at M062X/6-31G(d,p) level of theory.

  3. 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. (United States)

    Suardíaz, Reynier; Jambrina, Pablo G; Masgrau, Laura; González-Lafont, Àngels; Rosta, Edina; Lluch, José M


    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

  4. 玉米秸秆稀酸蒸汽爆破协同作用机制研究%Research on Synergism of Acid-catalyzed Steam Explosion of Corn Stalk

    Institute of Scientific and Technical Information of China (English)

    贾天宇; 廖克俭; 佟名友; 王鑫; 李秀铭


    以玉米秸秆原料,进行蒸汽爆破处理,比较了水蒸气蒸爆、稀酸和稀酸蒸爆3种预处理方法,通过对3种预处理过程中米秸秆纤维组分变化、纤维素和半纤维素降解产物和玉米秸秆结构分析以及酶解试验,探讨稀酸蒸汽爆破的协同作用机制.结果表明,稀酸蒸爆协同作用包括稀酸的软化和蒸汽爆破的活化两种机制:一是通过稀酸脱除大部分的半纤维素破坏了半纤维素与木质素间的相互作用,软化了纤维组织;二是软化的纤维通过蒸汽爆破冻结其活性纤维素超分子结构,增加了纤维素与纤维素酶的接触面积.%Using corn stalk as raw material, three pretreatments including water vapor steam explosion, dilute acid catalysis and dilute acid-catalyzed steam explosion were carried out in order to investigate.synergy effect of steam explosion and dilute acid catalysis. For the purpose, effects of acid-catalyzed steam explosion on corn stalk were analyzed and characterized, such as composition, structure, property of the matter, forming degradable products after pretreatments and enzymatic hydrolysis. The results show that the positive effect of acid-catalyzed steam explosion attributes to,the synergistic interactions of acid-softening and steam activation. First, the hemicellulose removal with acid can break the interaction between cellulose and ligin, and soften lignocellulosic structure. Second, steam explosion of acid- softened matter can lead to the forming of an active supramolecular structure, which can increase the accessibility of cellulase to celluloses.

  5. 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; LIN WenQin; HE Zhe; JIN Yi; JIANG YaoZhong


    @@ (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

  6. 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


    (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]……

  7. 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 (United States)

    Zhang, Yanzhou; Li, Xunhang; Hao, Zhikui; Xi, Ruchun; Cai, Yujie; Liao, Xiangru


    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

  8. 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.

  9. Catalyzing RE Project Development

    Energy Technology Data Exchange (ETDEWEB)

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


    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.

  10. Muon Catalyzed Fusion (United States)

    Armour, Edward A.G.


    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.

  11. Interconversion of ketoprofen recognition in firefly luciferase-catalyzed enantioselective thioesterification reaction using from Pylocoeria miyako (PmL) and Hotaria parvura (HpL) just by mutating two amino acid residues. (United States)

    Kato, Dai-ichiro; Hiraishi, Yoshihiro; Maenaka, Mika; Yokoyama, Keisuke; Niwa, Kazuki; Ohmiya, Yoshihiro; Takeo, Masahiro; Negoro, Seiji


    We identified the critical amino acid residues for substrate recognition using two firefly luciferases from Pylocoeria miyako (PmL) and Hotaria parvura (HpL), as these two luciferase enzymes exhibit different activities toward ketoprofen. Specifically, PmL can catalyze the apparent enantioselective thioesterification reaction, while HpL cannot. By comparing the amino acid sequences around the active site, we identified two residues (I350 and M397 in PmL and F351 and S398 in HpL) that were different between the two enzymes, and the replacement of these amino acids resulted in changing the ketoprofen recognition pattern. The inactive HpL was converted to the active enzyme toward ketoprofen and vice versa for PmL. These residues also affected the enantioselectivity toward ketoprofen; however, the bioluminescent color was not affected. In addition, using molecular dynamics calculations, the replacement of these two amino acids induced changes in the state of hydrogen bonding between ketoprofen and the S349 side chain through the active site water. As S349 is not considered to influence color tuning, these changes specifically caused the differences in ketoprofen recognition in the enzyme.

  12. A Novel poly {(2,5-diyl thiophene) (2-Thiophenyl Methine)} from the Acid-Catalyzed Polycondensation of thiophene and thiophene-2-carbanaldehyde (United States)

    Belmokhtar, A.; Yahiaoui, A.; Hachemaoui, A.; Sahli, N.; Benyoucef, A.; Belfedal, A.; Belbachir, M.


    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.

  13. Lewis acid catalyzed cyclization of glycals/2-deoxy-D-ribose with arylamines: additional findings on product structure and reaction diastereoselectivity. (United States)

    Du, Chengtang; Li, Fulong; Zhang, Xuefeng; Hu, Wenxiang; Yao, Qizheng; Zhang, Ao


    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.


    Institute of Scientific and Technical Information of China (English)

    佟春雨; 陈群; 孙富安; 陈亮; 何明阳


    A catalyst of cation exchange resin was selected to catalyze propylene oligomerization. The relationship between resin properties and catalytic activities were studied and the optimal reaction conditions of the typical resin LC001 were investigated. The propylene oligomerization was catalyzed by cation resin LC001 with macroporous and high exchange capacity. The once through conversion of propylene kept at about 64.7%, and the selectivity of nonene and dodecene in liquid products were about 58% under the optimized conditions of reaction temperature 150℃, reaction pressure 4.0MPa and the LHSV 1.5h'\\ This catalyst displayed good stability, high activity and simple process. It showed a good prospect in industrial production.%筛选了可用于丙烯齐聚的阳离子交换树脂催化剂,研究了树脂性质与催化性能间的关系,并考察了自制LC001树脂催化丙烯齐聚的工艺条件.结果发现,采用大孔、高交换量的LC001树脂在150℃、4.0MPa、液时空速为1.5h-1条件下反应,丙烯单程转化率达到64.7%,C9和C12烯烃的选择性能达到58%.催化剂性能稳定,催化活性高,工艺流程简单,有很好的工业应用前景.

  15. Effect of low-molecular-weight organic acids on photo-degradation of phenanthrene catalyzed by Fe(III)-smectite under visible light. (United States)

    Jia, Hanzhong; Chen, Hongxia; Nulaji, Gulimire; Li, Xiyou; Wang, Chuanyi


    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.

  16. Gold-Catalyzed Regioselective Dimerization of Aliphatic Terminal Alkynes. (United States)

    Sun, Sheng; Kroll, Julien; Luo, Yingdong; Zhang, Liming


    A gold-catalyzed regioselective homodimerization of aliphatic terminal alkynes is described. Bulky and less Lewis acidic tBuXPhosAuNTf(2) is the preferred catalyst, and the additive, anhydrous NaOAc, substantially facilitates the reaction.

  17. Enantioselective, iridium-catalyzed monoallylation of ammonia. (United States)

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


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

  18. 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


    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.


    Institute of Scientific and Technical Information of China (English)



    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.

  20. 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.


    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

  1. Chiral Pd aqua complex-catalyzed asymmetric C-C bond-forming reactions: a Brønsted acid-base cooperative system. (United States)

    Sodeoka, Mikiko; Hamashima, Yoshitaka


    Chiral cationic Pd aqua complexes can function as acid-base catalysts, effectively activating active methylene and methine compounds to give chiral Pd enolates. It is noteworthy that such enolate formation occurs with concomitant formation of a strong protic acid. Although the reactivity of the Pd enolate itself is not sufficient for reactions with carbon-based electrophiles, its cooperative action with the protic acid to activate the electrophiles allows the desired C-C bond-forming reactions to proceed smoothly in a highly enantioselective manner. Based on this mechanistic feature, reactions with acetals have been developed; these are difficult to achieve using conventional basic enolate chemistry.

  2. 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


    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.

  3. CuO and Ag2O/CuO Catalyzed Oxidation of Aldehydes to the Corresponding Carboxylic Acids by Molecular Oxygen

    Directory of Open Access Journals (Sweden)

    Yaowu Sha


    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.

  4. 氮杂冠醚化双Schiff碱配合物催化羧酸酯水解的研究%Study on aza crown ether substituted bis-Schiff base complexes catalyze carboxylic acid esters hydrolysis

    Institute of Scientific and Technical Information of China (English)

    程杰; 李建章; 何锡阳; 曾俊; 肖正华; 胡伟


    将4种氮杂冠醚取代的双Schiff碱钴(H)、锰(m)配合物作为仿水解酶模型催化羧酸酯(PNPP)水解.考察了Schiff碱配合物中氮杂冠醚取代的位置、氮杂冠醚的数目对其仿水解酶性能的影响;探讨了Schiff配合物催化PNPP水解的动力学和机理;提出了配合物催化PNPP水解的动力学模型.结果表明,在25℃条件下随着缓冲溶液pH值的增大,配合物催化PNPP水解速率提高;四种氮杂冠醚取代的双Schiff碱配合物在催化PNPP水解反应中表现出良好的催化活性;氮杂冠醚3-取代的Schiff碱配合物CoL2的催化活性高于5-取代的Schiff碱配合物CoL1,含有2个氮杂冠醚的配合物CoL3的催化活性高于含有1个氮杂冠醚的配合物CoL2.%Four aza crown ether substituted bis-Schiff base transition-mental complexes have been used as mimic hydrolytic enzyme model catalyzing carboxylic acid esters ( PNPP) hydrolysis. The effects of substituted position of aza-crown and amount of aza-crown of Schiff base complexes were studied. The kinetics on PNPP hydrolysis catalyzed by these complexes was investigated. The kinetic mathematical model of PNPP cleavage catalyzed by these complexes was proposed. The results showed that the rate for the catalytic PNPP hydrolysis was increased following the increase of pH of the buffer solution; four complexes exhibited high activity in the catalytic PNPP hydrolysis, The catalytic activity of unsymmetrical Schiff base complexes of 3-substitute benzo-10-aza-crown groups ( CoL2 ) is larger than that of 5 -substitute benzo-10-aza-crown groups ( CoL1) , and the catalytic activity of Schiff base complexes with two benzo-10-aza-crown ether pendants (CoL3) is larger than that of Schiff base complexes with one benzo-10-aza-crown ether pendants (CoL2).

  5. Synthesis and Characterization of Sulfonated Poly(Phenylene Containing a Non-Planar Structure and Dibenzoyl Groups

    Directory of Open Access Journals (Sweden)

    Hohyoun Jang


    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.

  6. 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


    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.

  7. Cytochrome P450 family member CYP704B2 catalyzes the {omega}-hydroxylation of fatty acids and is required for anther cutin biosynthesis and pollen exine formation in rice. (United States)

    Li, Hui; Pinot, Franck; Sauveplane, Vincent; Werck-Reichhart, Danièle; Diehl, Patrik; Schreiber, Lukas; Franke, Rochus; Zhang, Ping; Chen, Liang; Gao, Yawei; Liang, Wanqi; Zhang, Dabing


    The anther cuticle and microspore exine act as protective barriers for the male gametophyte and pollen grain, but relatively little is known about the mechanisms underlying the biosynthesis of the monomers of which they are composed. We report here the isolation and characterization of a rice (Oryza sativa) male sterile mutant, cyp704B2, which exhibits a swollen sporophytic tapetal layer, aborted pollen grains without detectable exine, and undeveloped anther cuticle. In addition, chemical composition analysis indicated that cutin monomers were hardly detectable in the cyp704B2 anthers. These defects are caused by a mutation in a cytochrome P450 family gene, CYP704B2. The CYP704B2 transcript is specifically detected in the tapetum and the microspore from stage 8 of anther development to stage 10. Heterologous expression of CYP704B2 in yeast demonstrated that CYP704B2 catalyzes the production of omega -hydroxylated fatty acids with 16 and 18 carbon chains. Our results provide insights into the biosynthesis of the two biopolymers sporopollenin and cutin. Specifically, our study indicates that the omega -hydroxylation pathway of fatty acids relying on this ancient CYP704B family, conserved from moss to angiosperms, is essential for the formation of both cuticle and exine during plant male reproductive and spore development.

  8. Hydroxylation of aspartic acid in domains homologous to the epidermal growth factor precursor is catalyzed by a 2-oxoglutarate-dependent dioxygenase. (United States)

    Stenflo, J; Holme, E; Lindstedt, S; Chandramouli, N; Huang, L H; Tam, J P; Merrifield, R B


    3-Hydroxyaspartic acid and 3-hydroxyasparagine are two rare amino acids that are present in domains homologous to the epidermal growth factor precursor in vitamin K-dependent plasma proteins as well as in proteins that do not require vitamin K for normal biosynthesis. They are formed by posttranslational hydroxylation of aspartic acid and asparagine, respectively. The first epidermal growth factor-like domain in factor IX (residues 45-87) was synthesized with aspartic acid in position 64, replacing 3-hydroxyaspartic acid. It was used as substrate in a hydroxylase assay with rat liver microsomes as the source of enzyme and reaction conditions that satisfy the requirements of 2-oxoglutarate-dependent dioxygenases. The synthetic peptide stimulated the 2-oxoglutarate decarboxylation in contrast to synthetic, modified epidermal growth factor (Met-21 and His-22 deleted and Glu-24 replaced by Asp) and synthetic peptides corresponding to residues 60-71 in human factor IX. This indicates that the hydroxylase is a 2-oxoglutarate-dependent dioxygenase with a selective substrate requirement. Images PMID:2492106

  9. 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)


    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.

  10. 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


    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%.

  11. Synthesis of α-Amino Acids via Asymmetric Phase Transfer-Catalyzed Alkylation of Achiral Nickel(II) Complexes of Glycine-Derived Schiff Bases

    NARCIS (Netherlands)

    Belokon, Yuri N.; Bespalova, Natalia B.; Churkina, Tatiana D.; Císařová, Ivana; Ezernitskaya, Marina G.; Harutyunyan, Syuzanna R.; Hrdina, Radim; Kagan, Henri B.; Kočovský, Pavel; Kochetkov, Konstantin A.; Larionov, Oleg V.; Lyssenko, Konstantin A.; North, Michael; Polášek, Miroslav; Peregudov, Alexander S.; Prisyazhnyuk, Vladimir V.; Vyskočil, Štěpán


    Achiral, diamagnetic Ni(II) complexes 1 and 3 have been synthesized from Ni(II) salts and the Schiff bases, generated from glycine and PBP and PBA, respectively, in MeONa/MeOH solutions. The requisite carbonyl-derivatizing agents pyridine-2-carboxylic acid(2-benzoyl-phenyl)-amide (PBP) and pyridine-

  12. Nickel-catalyzed cross-coupling of phenols and arylboronic acids through an in situ phenol activation mediated by PyBroP. (United States)

    Chen, Guo-Jun; Huang, Jie; Gao, Lian-Xun; Han, Fu-She


    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.

  13. 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.


    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

  14. Stereocontrolled Synthesis of (E)-β, γ-Unsaturated Esters via Palladium-Catalyzed Cross-Coupling of (E)-Alkenylboronic Acids with a-Bromoacetic Esters

    Institute of Scientific and Technical Information of China (English)

    DUAN Yazhen; ZHANG Jianshe; YANG Jun; DENG Minzhi


    The cross-coupling reaction of trans-alkenylboronic acids with α-bromoacetic esters was firstly studied. It was found that using Pd(OAc)2 as catalyst, a bulky electron-rich phospine, (2-dicyclohexylphospino-biphenyl) as ligand, the reaction can be readily accomplished to give specific (E)-β,γ-unsaturated esters in high yields.

  15. Aldehyde-alcohol reactions catalyzed under mild conditions by chromium(III) terephthalate metal organic framework (MIL-101) and phosphotungstic acid composites. (United States)

    Bromberg, Lev; Hatton, T Alan


    Porous materials based on chromium(III) terephthalate metal organic frameworks (MIL-101) and their composites with phosphotungstic acid (PTA) were studied as heterogeneous acid catalysts in aldehyde-alcohol reactions exemplified by acetaldehyde-phenol (A-P) condensation and dimethylacetal formation from benzaldehyde and methanol (B-M reaction). The MIL-101 was synthesized solvothermically in water, and the MIL101/PTA composite materials were obtained by either impregnation of the already prepared MIL-101 porous matrix with phosphotungstic acid solution or by solvothermic treatment of aqueous mixtures of Cr(NO(3))(3), and terephthalic and phosphotungstic acids. The MIL101/PTA materials appeared to be effective catalysts for both A-P and B-M reactions occurring at room temperature, with half-lives ranging from 0.5 h (A-P) to 1.5-2 h (B-M) and turnover numbers over 600 for A-P and over 2900 for the B-M reaction, respectively. A synergistic effect of the strong acidic moieties (PTA) addition to mildly acidic Brønsted and Lewis acid cites of the MIL-101 was observed with the MIL101/PTA composites. The ability of the PTA and MIL101/PTA materials to strongly absorb and condense acetaldehyde vapors was discovered, with the MIL101/PTA absorbing over 10-fold its dry weight of acetaldehyde condensate at room temperature. The acetaldehyde was converted rapidly to crotonaldehyde and higher-molecular-weight compounds while in contact with MIL-101 and MIL101/PTA materials. The stability of the MIL-101 and MIL101/PTA catalysts was assessed within four cycles of the 1-day alcohol-aldehyde reactions in terms of the overall catalyst recovery, PTA or Cr content, and reaction rate constants in each cycle. The loss of the catalyst over 4 cycles was approximately 10 wt % for all tested catalysts due to the incomplete recovery and minute dissolution of the components. The reaction rates in all cycles remained unchanged and the catalyst losses stopped after the third cycle. The developed

  16. 酸性催化剂催化异丙醇脱水制丙烯反应%Dehydration of isopropanol to propylene catalyzed by acid catalysts

    Institute of Scientific and Technical Information of China (English)

    刘春燕; 段永超; 伍艳辉


    HZSM-5 and Zn modified HZSM-5,a series of SAPO-34 with different mass ratio of SAPO-34 to Al2O3, MCM-4l and phosphotungstic acid supported MCM-4l were prepared and characterized by BET, XRD and FT-IR. The catalysts for isopropanol dehydration to propylene were investigated in a fixed bed reactor. The results indicated that the acidity of Zn modified HZSM-5 was adjusted effectively and the selectivity to propylene was enhanced;SAPO-34 catalyst (with mass ratio of SAPO-34 to Al2O3 of 5:1) and MCM-4l had weak acid site and exhibited higher selectivity to propylene;the acidity of phosphotungstie acid supported MCM41 was stronger than that of MCM-41, and isopropanol conversion increased and the selectivity to propylene decreased obviously.%对HZSM-5及Zn改性HZSM-5、SAPO-34、MCM-41和磷钨酸负载MCM-41分子筛催化剂进行表征,评价固定床反应器中催化异丙醇脱水反应.Zn改性HZSM-5可有效调节催化剂的酸性,提高催化剂选择性,酸性较弱的SAPO-34与Al2O3质量比为5:1混合组成的SAPO-34催化剂和MCM-41分子筛也表现出较高的丙烯选择性,在MCM-41上负载磷钨酸后,催化剂酸性较强,提高了异丙醇反应的转化率,但同时降低生成丙烯的选择性.

  17. 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


    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.

  18. Optimization of lipase-catalyzed synthesis of fatty acid ethyl ester from corn oil%脂肪酶催化玉米油合成脂肪酸乙酯工艺研究

    Institute of Scientific and Technical Information of China (English)

    康建波; 胡士恒; 王亚男; 周亚军


    为研制食药两用的功能性原料亚油酸乙酯,以玉米油和乙醇为原料,经固定化脂肪酶催化合成脂肪酸乙酯.通过单因素试验和响应面分析法(RSM)研究醇油摩尔比、脂肪酶用量、反应温度、反应时间对玉米油脂肪酸乙酯合成的影响.研究结果表明,玉米油脂肪酸乙酯合成的最佳工艺条件为醇油摩尔比为4∶1,脂肪酶质量分数为30.82%,反应温度为50.39℃,反应时间为24.15 h,在此工艺条件下脂肪酸乙酯转化率为90.20%.%In order to develop the functional raw material linoleic acid ethylester which can be used as both food and medicine, the fatty acid ethyl esters are synthesized by immobilized lipase-catalyzed reaction with corn oil and alcohol as raw material in this study. Based on the single factor experiments and response surface methodology ( RSM ) , the influences of molar ratio ethanol and corn oil, the amount of enzyme, the reaction temperature and reaction time on the synthesis of fatty acid ethyl ester from corn oil are investigated. The obtained optimal parameters are shown as follows -A-1 molar ratio of ethanol to oil,30 % of amount of enzyme,50. 39℃ of reaction temperature and 24 hours of reaction time. The rate of conversion of corn oil can reach 90. 20% .


    Institute of Scientific and Technical Information of China (English)

    Yu-sheng Qin; Xian-hong Wang; Xiao-jiang Zhao; Fo-song Wang


    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.

  20. Thermally Stable Forms of Pure Polyaniline Catalyzed by an Acid-Exchanged Montmorillonite Clay Called Maghnite- H + as an Effective Catalyst


    Rahmouni Abdelkader; Harrane Amine; Belbachir Mohammed


    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 ...

  1. 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


    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.

  2. Sol-Gel固定磷钨酸催化合成乙酸丁酯%Synthesis of Butyl Acetate Catalyzed by Phosphotungstic Acid Immobilized on Sol-Gel

    Institute of Scientific and Technical Information of China (English)

    成凤桂; 欧知义


    制备了正硅酸乙酯凝胶(Sol-Gel)固定磷钨酸催化剂,催化合成乙酸丁酯.实验表明:Sol-Gel与磷钨酸的质量比为15∶1时催化性能最高,在催化剂用量为总反应物质量的5 %、酸醇比为1.5∶1、反应温度为105 °C、反应时间3.5 h的条件下,酯产率可达87 %以上.催化剂易与产物分离,重复使用8次催化效果仍然较好.%The phosphotungstic acid immobilized on Sol-Gel were prepared and used for synthesising butyl acetate from n-butyl alcohol and acetic acid.The catalysis activity was highest when mass ratio of tetraethoxysilane(TEOS) to phosphotungstic acid was 15∶1. The optimum condition of the reaction were determined: the moiar ratio of acetic acid to n-butyl alcohol was 1.3∶1, the amount of catalyst was about 5 % of the mass of reactants, reaction temperature is 105 °C for 3.5 h. Under the optimum condition the yieid of esters is above 87 %. The catalyst could be easily separated from the products. Reusing of its catalysis activity is still well used for 8 times.

  3. Iodine Catalyzed One-pot Synthesis of 3,4-Dihydroquinazolin-4-ones from Anthranilic Acids, Ortho Esters and Amines under Solvent-free Conditions

    Institute of Scientific and Technical Information of China (English)

    WANG,Hong-She; ZENG,Jun-E


    A simple and efficient procedure has been developed for the one-pot synthesis of 3,4-dihydroquinazolin-4-ones from anthranilic acids, ortho esters and amines using a catalytic amount of iodine under solvent-free conditions to afford the corresponding products in excellent yields. The direct use of commercially available catalyst, mild and solvent-free reaction conditions, short reaction time, easy workup and excellent yields are the advantages of the present protocol.

  4. Copper-catalyzed tandem phosphination-decarboxylation-oxidation of alkynyl acids with H-phosphine oxides: a facile synthesis of β-ketophosphine oxides. (United States)

    Zhang, Pengbo; Zhang, Liangliang; Gao, Yuzhen; Xu, Jian; Fang, Hua; Tang, Guo; Zhao, Yufen


    The general method for the tandem phosphination-decarboxylation-oxidation of alkynyl acids under aerobic conditions has been developed. In the presence of CuSO4·5H2O and TBHP, the reactions provide a novel access to β-ketophosphine oxides in good to excellent yields. This transformation allows the direct formation of a P-C bond and the construction of a keto group in one reaction.

  5. Efficient C-N bond formations catalyzed by a proton-exchanged montmorillonite as a heterogeneous Brønsted acid. (United States)

    Motokura, Ken; Nakagiri, Nobuaki; Mori, Kohsuke; Mizugaki, Tomoo; Ebitani, Kohki; Jitsukawa, Koichiro; Kaneda, Kiyotomi


    Nucleophilic addition of sulfonamides and carboxamides to simple alkenes proceeded smoothly using a proton-exchanged montmorillonite catalyst. The spent catalyst was recovered easily from the reaction mixture and was reusable at least five times without any loss of activity. The unique acidity of the proton-exchanged montmorillonite (H-mont) catalyst was found to be applicable to additional reactions: substitution of hydroxyl groups of alcohols with amides and anilines.

  6. 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.


    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.

  7. High-yield preparation of wax esters via lipase-catalyzed esterification using fatty acids and alcohols from crambe and camelina oils. (United States)

    Steinke, G; Weitkamp, P; Klein, E; Mukherjee, K D


    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.

  8. Lipase-catalyzed synthesis of cocoa butter equivalent from palm olein and saturated fatty acid distillate from palm oil physical refinery. (United States)

    Mohamed, Ibrahim O


    Cocoa butter equivalent was prepared by enzymatic acidolysis reaction of substrate consisting of refined palm olein oil and palmitic-stearic fatty acid mixture. The reactions were performed in a batch reactor at a temperature of 60 °C in an orbital shaker operated at 160 RPM. Different mass ratios of substrates were explored and the compositions of the five major triacylglycerol (TAG) of the structured lipids were identified and quantified using cocoa butter-certified reference material IRMM-801. The reaction resulted in production of cococa butter equivent with TAG compostion (POP 26.6 %, POS 42.1, POO 7.5, SOS 18.0 %, and SOO 5.8 %) and melting temperature between 34.7 and 39.6 °C which is close to that of the cocoa butter. The result of this research demonstrated the potential use of saturated fatty acid distillate (palmitic and stearic fatty acids) obtained from palm oil physical refining process into a value-added product.

  9. 氨基酸离子液体清洁催化合成阿司匹林%Clean Catalyzed Synthesis of Aspirin by Amino Acid Ionic Liquids

    Institute of Scientific and Technical Information of China (English)

    王晓丹; 范洪涛; 崔天放; 邓伟荣


    以氨基酸为原料采用一步法合成了3种氨基酸离子液体,将其代替浓H2SO4用于催化乙酸酐和水杨酸的乙酰化反应,清洁合成阿司匹林.考察了离子液体种类及用量、原料配比、反应温度、时间等因素对合成阿司匹林的影响.结果表明,该离子液体对于合成阿司匹林具有良好的催化效果,在水杨酸20mmol、乙酸酐40mmol、谷氨酸硫酸盐离子液体([Glu] HSO4) 2mmol、反应温度70℃、反应时间30min的条件下,阿司匹林分离产率可达84.8%.增大投料量,产率还会进一步升高,并且离子液体可重复使用.%Three kinds of amino acid-ionic liquids were synthesized by one step method and clean synthesis of aspirin by these ionic liquids instead of concentrated sulfuric acid with acetylation about acetic anhydride and salicylic acid. The effects abqut synthesis of aspirin were studied,such as amount of the ionic liquids,ratio of raw materials, reaction temperature and reaction time etc. The results show that amino acid ionic liquids are excellent catalysts for synthesis of aspirin. Under the conditions that salicylic acid is 20mmol, acetic anhydride is 40mmol, [Glu]HSO4 is 2mmol, reaction temperature is 70℃ and reaction time is 30min, isolated yield of aspirin can reach 84. 8%. Increase the raw materials, the yield will be increase,and the catalyst can be recycled.

  10. Mechanistic Insights on C-O and C-C Bond Activation and Hydrogen Insertion during Acetic Acid Hydrogenation Catalyzed by Ruthenium Clusters in Aqueous Medium

    Energy Technology Data Exchange (ETDEWEB)

    Shangguan, Junnan; Olarte, Mariefel V.; Chin, Ya-Huei [Cathy


    Catalytic pathways for acetic acid (CH3COOH) and hydrogen (H2) reactions on dispersed Ru clusters in the aqueous medium and the associated kinetic requirements for C-O and C-C bond cleavages and hydrogen insertion are established from rate and isotopic assessments. CH3COOH reacts with H2 in steps that either retain its carbon backbone and lead to ethanol, ethyl acetate, and ethane (47-95 %, 1-23 %, and 2-17 % carbon selectivities, respectively) or break its C-C bond and form methane (1-43 % carbon selectivities) at moderate temperatures (413-523 K) and H2 pressures (10-60 bar, 298 K). Initial CH3COOH activation is the kinetically relevant step, during which CH3C(O)-OH bond cleaves on a metal site pair at Ru cluster surfaces nearly saturated with adsorbed hydroxyl (OH*) and acetate (CH3COO*) intermediates, forming an adsorbed acetyl (CH3CO*) and hydroxyl (OH*) species. Acetic acid turnover rates increase proportionally with both H2 (10-60 bar) and CH3COOH concentrations at low CH3COOH concentrations (<0.83 M), but decrease from first to zero order as the CH3COOH concentration and the CH3COO* coverages increase and the vacant Ru sites concomitantly decrease. Beyond the initial CH3C(O)-OH bond activation, sequential H-insertions on the surface acetyl species (CH3CO*) lead to C2 products and their derivative (ethanol, ethane, and ethyl acetate) and the competitive C-C bond cleavage of CH3CO* causes the eventual methane formation. The instantaneous carbon selectivities towards C2 species (ethanol, ethane, and ethyl acetate) increase linearly with the concentration of proton-type Hδ+ (derived from carboxylic acid dissociation) and chemisorbed H*. The selectivities towards C2 products decrease with increasing temperature, because of higher observed barriers for C-C bond cleavage than H-insertion. This study offers an interpretation of mechanism and energetics and provides kinetic evidence of carboxylic acid assisted proton-type hydrogen (Hδ+) shuffling during H

  11. 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


    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%.

  12. 三氯乙酸催化合成β-烯胺酮类化合物%Catalyzed Synthesis ofβ-enamine Ketones Compounds by Trichloroacetic Acid

    Institute of Scientific and Technical Information of China (English)

    袁慰; 李江飞; 肖兰; 王永秋


    Using trichloroacetic acid catalyst and ethanol as solvent,aromatic amine compounds reacted withβ-diketone compounds to synthesize β-enamine ketones compounds.This method is efficient,green and safe, and enjoys convenient operation and high yields.%在三氯乙酸催化剂的作用下,以乙醇为溶剂,将芳香胺类化合物和β-二酮一锅反应合成β-烯胺酮类化合物。此法高效、安全,操作便捷,且产率高。

  13. Lipase catalyzed synthesis of L-alanyl, L-leucyl and L-phenylalanyl esters of D-glucose using unprotected amino acids. (United States)

    Vijayakumar, Giriyapura R; Lohith, Kenchaiah; Somashekar, Bhandya R; Divakar, Soundar


    Enzymatic synthesis of l-alanyl, l-leucyl and l-phenylalanyl esters of D-glucose was carried out in a non-polar solvent using lipases from Rhizomucor miehei and porcine pancreas. The unprotected amino acids at millimolar concentrations were used in presence of 10 to 50% (w/w) glucose of the lipases to give ester yields up to >99%. The reaction mixture on analysis by 2-D NMR showed that the product is a mixture of 6-O-, 3-O- and 2-O-monoesters and 2,6-di-O- and 3,6- di-O-esters.

  14. Acid and base catalyzed Davis-Beirut reaction: experimental and theoretical mechanistic studies and synthesis of novel 3-amino-2H-indazoles. (United States)

    Avila, Belem; El-Dakdouki, Mohammad H; Nazer, Musa Z; Harrison, Jason G; Tantillo, Dean J; Haddadin, Makhluf J; Kurth, Mark J


    The Davis-Beirut reaction, which provides an efficient synthesis of 2H-indazoles and, subsequently, indazolones, is shown to proceed rapidly from o-nitrosobenzaldehyde and primary amines under both acid or base catalysis. Experimental and theoretical evidence in support of a reaction mechanism is provided in which o-nitrosobenzylidine imine is a pivotal intermediate in this N,N-bond forming heterocyclization reaction. The Davis-Beirut reaction is also shown to effectively synthesize a number of novel 3-amino-2H-indazole derivatives.

  15. A facile, green, one-pot synthesis of amidoalkyl naphthols under solvent-free conditions catalyzed by a carbon-based solid acid

    Institute of Scientific and Technical Information of China (English)

    Abolghasem Davoodnia; Rahil Mahjoobin; Niloofar Tavakoli-Hoseini


    An efficient, environmentally friendly procedure for the synthesis of amidoalkyl naphthols through the one-pot, three-component reaction of β-naphthol, aryl aldehydes, and acetamide in the presence of a carbon-based solid acid under thermal solvent-free conditions is described. The beneficial fea-tures of this new synthetic approach include short reaction time, high yields, clean reaction profiles, and a simple work-up procedure. Furthermore, the catalyst can be readily recycled and reused four times without obvious significant loss of activity. The structure of the catalyst was confirmed by Fourier transform infrared spectroscopy, N2 adsorption/desorption analysis, and X-ray diffraction.

  16. 硫酸溶液中胶束催化Ce(IV)氧化D-甘露糖%Micelle Catalyzed Oxidation of D-Mannose by Cerium (Ⅳ) in Sulfuric Acid

    Institute of Scientific and Technical Information of China (English)

    KABIR-UD-DIN; ALI Mohd. Sajid; KHAN Zaheer


    Kinetics of D-mannose oxidation by cerium (IV) was studied in a sulfuric acid medium at 40℃ both in absence and presence of ionic micelles. In both cases, the rate of the reaction was first-order in D-mannose and in cerium(Ⅳ), which decreased with increasing [H2SO4]. This suggested that the redox reaction followed the same mechanism. The reaction proceeded through formation of an intermediate complex, which was proved by kinetic method. The complex underwent slow unimolecular decomposition to a free radical that reacted with cerium (Ⅳ) to afford the product. The catalytic role of cationic cetyltrimethylammonium bromide (CTAB) micelles was best explained by the Menger-Portnoy model. The study of the effect of CTAB also indicated that a negatively charged species was reactive form of cerium (Ⅳ). From the kinetic data, micelle-cerium (Ⅳ) binding and rate constants in micellar medium were evaluated.The anionic micelle of sodium dodecyl sulfate plays no catalytic role. The oxidation has the rate expression: --d[Ce(Ⅳ)]= k1Kcl[D-mannose] [Ce(Ⅳ)]dt Different activation parameters for micelle catalyzed and uncatalyzed paths were also calculated and discussed.

  17. 酸性离子液体[bmim]HSO4催化纤维素水解的研究%Hydrolysis of Cellulose Catalyzed by Acidic Ionic Liquid [bmim] HSO4

    Institute of Scientific and Technical Information of China (English)

    芦天亮; 秦志芳; 唐思; 周利鹏; 苏运来; 杨晓梅


    Hydrolysis of cellulose was carried out in l-n-butyl-3-methylimidazolium chloride catalyzed by acidic ionic liquid l-n-butyl-3-methylimidazolium hydrogen sulfate ( [ bmim] HSO4 ) . Reaction results showed that these parameters including the pre-dissolving time for cellulose, the reaction temperature, the amount of catalyst and water remarkably affected the hydrolysis of cellulose to the reduced sugar. Ninety two percent yield of reduced sugar was obtained by 1.5 g of catalyst and 0. 1 mL of water at 90℃ with 80 min of reaction time.%以1-正丁基-3-甲基氯代咪唑为溶剂,酸性离子液体1-正丁基-3-甲基硫酸氢根代咪唑([bmim] HSO4)为催化剂,考察了溶解时间、反应温度、催化剂用量、水量等因素对纤维素水解的影响.结果表明,[bmim] HSO4具有良好的催化效果,当催化剂用量为1.5 g,水量为0.1 mL,反应温度为90℃时,反应80 min,还原糖收率可以达到92%.

  18. 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


    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%.

  19. 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


    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.

  20. The mechanism of Fe (Ⅲ)-catalyzed ozonation of phenol

    Institute of Scientific and Technical Information of China (English)

    竹湘锋; 徐新华


    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.

  1. 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


    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.

  2. 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


    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.

  3. The continuous acid-catalyzed dehydration of alcohols in supercritical fluids: A new approach to the cleaner synthesis of acetals, ketals, and ethers with high selectivity

    Energy Technology Data Exchange (ETDEWEB)

    Gray, W.K.; Smail, F.R.; Hitzler, M.G.; Ross, S.K.; Poliakoff, M.


    This report describes a new a continuous method for forming ethers, acetals and ketals using solid acid catalysts, DELOXAN ASP or AMBERLYST 15, and supercritical fluid solvents. In the case of ether formation, the authors observe a high selectivity for linear alkyl ethers with little rearrangement to give branches ethers. Such rearrangement is common in conventional synthesis. The approach is effective for a range of n-alcohols up to n-octanol and also for the secondary alcohol 2-propanol. In the reaction of phenol with an alkylating agent, the continuous reaction can be tuned to give preferential O- or C-alkylation with up to 49% O-alkylation with supercritical propene. The authors also investigate the synthesis of a range of cyclic ethers and show an improved method for the synthesis of THF from 1,4-butandiol under very mild conditions.

  4. Visbreaking of heavy petroleum oil catalyzed by SO42-/ZrO2 solid super-acid doped with Ni2+ or Sn2+

    Institute of Scientific and Technical Information of China (English)


    SO42-/ZrO2 solid super-acid catalysts (SZ)doped with Ni2+ or Sn2+ (Ni2+/SZ,Sn2+/SZ) were prepared for catalytic visbreaking of heavy petroleum oil from Shengli oil field.The visbreaking reactions were carried out at 240℃ and 3-4 MPa for 24 h using a heavy petroleum oil to catalyst mass ratio of 100 :0.05.The effect of water content on viscosity of heavy petroleum oil was also investigated.Both catalysts can promote thermolysis of heavy petroleum oil and the viscosity was reduced for (Sn2+/SZ) with visbreaking rates of 57.7% and 48.9%,respectively.After visbreaking,the saturated hydrocarbon content increased while aromatics,resin,asphaltene,sulfur and nitrogen content decreased.The presence of water was disadvantageous to visbreaking of heavy petroleum oil.

  5. Highly efficient epoxidation of alkenes with m-chloroperbenzoic acid catalyzed by nanomagnetic Co(III)@Fe₃O₄/SiO₂ salen complex

    Indian Academy of Sciences (India)



    A new type of heterogeneous Co(III) complex was synthesized by covalent grafting of homogeneous Co(III) salen complex onto the surface of Fe₃O₄/SiO₂ nanoparticle (NP). The heterogeneous nanocatalyst was characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), Fourier transform infrared spectra (FT-IR), atomic absorption spectroscopy (AAS), vibrating sample magnetometer (VSM) and nitrogen adsorption–desorption isotherm (BET). The catalytic activitywas investigated for the epoxidation of alkenes using m-chloroperbenzoic acid as oxidant at room temperature and the corresponding epoxide was achieved with excellent yields and selectivity. In addition, the effect of axial ligand was studied on the epoxidation reaction and pyridine N-oxide (PNO) was chosen as an excellent axial ligand in dichloromethane. Furthermore, the heterogeneous catalyst showed good stability and the magnetic properties (which made possible the easy recovery of catalyst with external magnet) without significant decrease in the activity in the epoxidation reaction.

  6. Review of HxPyOz-Catalyzed H + OH Recombination in Scramjet Nozzle Expansions; and Possible Phosphoric Acid Enhancement of Scramjet Flameholding, from Extinction of H3PO4 + H2 - Air Counterflow Diffusion Flames (United States)

    Pellett, Gerald


    Recent detailed articles by Twarowski indicate that small quantities of phosphorus oxides and acids in the fuel-rich combustion products of H2 + phosphine (PH3) + air should significantly catalyze H, OH and O recombination kinetics during high-speed nozzle expansions -- to reform H2O, release heat, and approach equilibrium more rapidly and closely than uncatalyzed kinetics. This paper is an initial feasibility study to determine (a) if addition of phosphoric acid vapor (H3PO4) to a H2 fuel jet -- which is much safer than using PH3 -- will allow combustion in a high-speed scramjet engine test without adverse effects on localized flameholding, and (b) if phosphorus-containing exhaust emissions are environmentally acceptable. A well-characterized axisymmetric straight-tube opposed jet burner (OJB) tool is used to evaluate H3PO4 addition effects on the air velocity extinction limit (flame strength) of a H2 versus air counterflow diffusion flame. Addition of nitric oxide (NO), also believed to promote catalytic H-atom recombination, was evaluated for comparison. Two to five mass percent H3PO4 in the H2 jet increased flame strength 4.2%, whereas airside addition decreased it 1%. Adding 5% NO to the H2 caused a 2% decrease. Products of H-atom attack on H3PO4 produced an intense green chemiluminescence near the stagnation point. The resultant exothermic production of phosphorus oxides and acids, with accelerated H-atom recombination, released sufficient heat near the stagnation point to increase flame strength. In conclusion, the addition of H3PO4 vapor (or more reactive P sources) to hydrogen in scramjet engine tests may positively affect flameholding stability in the combustor and thrust production during supersonic expansion -- a possible dual benefit with system design / performance implications. Finally, a preliminary assessment of possible environmental effects indicates that scramjet exhaust emissions should consist of phosphoric acid aerosol, with gradual

  7. 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


    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 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.

  8. Lipase-catalyzed acidolysis of palm mid fraction oil with palmitic and stearic Fatty Acid mixture for production of cocoa butter equivalent. (United States)

    Mohamed, Ibrahim O


    Cocoa butter equivalent (CBE) was prepared by enzymatic acidolysis reaction of substrate consisting of refined palm mid fraction oil and palmitic-stearic fatty acid mixture. The reactions were performed in a batch reactor at a temperature of 60 °C in an orbital shaker operated at 160 RPM. Different mass ratios of substrates were explored, and the composition of the five major triacylglycerols (TAGs) of the structured lipids was identified and quantified using cocoa butter certified reference material IRMM-801. The reaction resulted in production of cocoa butter equivalent with the TAGs' composition (1,3-dipalmitoyl-2-oleoyl-glycerol 30.7%, 1-palmitoyl-2-oleoyl-3-stearoyl-rac-glycerol 40.1%, 1-palmitoy-2,3- dioleoyl glycerol 9.0%, 1,3-distearoyl-2-oleoyl-glycerol 14.5 %, and 1-stearoyl-2,3-dioleoyl glycerol 5.7%) and with onset melting temperature of 31.6 °C and peak temperature of 40.4 °C which are close to those of cocoa butter. The proposed kinetics model for the acidolysis reaction presented the experimental data very well. The results of this research showed that palm mid fraction oil TAGs could be restructured to produce value added product such as CBE.

  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)


    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


    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. Mechanisms of Enzyme-Catalyzed Reduction of Two Carcinogenic Nitro-Aromatics, 3-Nitrobenzanthrone and Aristolochic Acid I: Experimental and Theoretical Approaches

    Directory of Open Access Journals (Sweden)

    Marie Stiborová


    Full Text Available This review summarizes the results found in studies investigating the enzymatic activation of two genotoxic nitro-aromatics, an environmental pollutant and carcinogen 3-nitrobenzanthrone (3-NBA and a natural plant nephrotoxin and carcinogen aristolochic acid I (AAI, to reactive species forming covalent DNA adducts. Experimental and theoretical approaches determined the reasons why human NAD(PH:quinone oxidoreductase (NQO1 and cytochromes P450 (CYP 1A1 and 1A2 have the potential to reductively activate both nitro-aromatics. The results also contributed to the elucidation of the molecular mechanisms of these reactions. The contribution of conjugation enzymes such as N,O-acetyltransferases (NATs and sulfotransferases (SULTs to the activation of 3-NBA and AAI was also examined. The results indicated differences in the abilities of 3-NBA and AAI metabolites to be further activated by these conjugation enzymes. The formation of DNA adducts generated by both carcinogens during their reductive activation by the NOQ1 and CYP1A1/2 enzymes was investigated with pure enzymes, enzymes present in subcellular cytosolic and microsomal fractions, selective inhibitors, and animal models (including knock-out and humanized animals. For the theoretical approaches, flexible in silico docking methods as well as ab initio calculations were employed. The results summarized in this review demonstrate that a combination of experimental and theoretical approaches is a useful tool to study the enzyme-mediated reaction mechanisms of 3-NBA and AAI reduction.

  12. 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


    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.*

  13. Rhodotorula glutinis Phenylalanine/Tyrosine Ammonia Lyase Enzyme Catalyzed Synthesis of the Methyl Ester of para-Hydroxycinnamic Acid and its Potential Antibacterial Activity. (United States)

    MacDonald, Marybeth C; Arivalagan, Pugazhendhi; Barre, Douglas E; MacInnis, Judith A; D'Cunha, Godwin B


    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 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.


    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. Structural Fluctuations in Enzyme-Catalyzed Reactions: Determinants of Reactivity in Fatty Acid Amide Hydrolase from Multivariate Statistical Analysis of Quantum Mechanics/Molecular Mechanics Paths. (United States)

    Lodola, Alessio; Sirirak, Jitnapa; Fey, Natalie; Rivara, Silvia; Mor, Marco; Mulholland, Adrian J


    The effects of structural fluctuations, due to protein dynamics, on enzyme activity are at the heart of current debates on enzyme catalysis. There is evidence that fatty acid amide hydrolase (FAAH) is an enzyme for which reaction proceeds via a high-energy, reactive conformation, distinct from the predominant enzyme-substrate complex (Lodola et al. Biophys. J. 2007, 92, L20-22). Identifying the structural causes of differences in reactivity between conformations in such complex systems is not trivial. Here, we show that multivariate analysis of key structural parameters can identify structural determinants of barrier height by analysis of multiple reaction paths. We apply a well-tested quantum mechanics/molecular mechanics (QM/MM) method to the first step of the acylation reaction between FAAH and oleamide substrate for 36 different starting structures. Geometrical parameters (consisting of the key bond distances that change during the reaction) were collected and used for principal component analysis (PCA), partial least-squares (PLS) regression analysis, and multiple linear regression (MLR) analysis. PCA indicates that different "families" of enzyme-substrate conformations arise from QM/MM molecular dynamics simulation and that rarely sampled, catalytically significant conformational states can be identified. PLS and MLR analyses allowed the construction of linear regression models, correlating the calculated activation barriers with simple geometrical descriptors. These analyses reveal the presence of two fully independent geometrical effects, explaining 78% of the variation in the activation barrier, which are directly correlated with transition-state stabilization (playing a major role in catalysis) and substrate binding. These results highlight the power of statistical approaches of this type in identifying crucial structural features that contribute to enzyme reactivity.

  16. Study on the synthesis of methyl glucoside catalyzed by supported super acid catalyst%负载型超强酸催化剂催化合成甲基葡萄糖苷的研究

    Institute of Scientific and Technical Information of China (English)

    魏风勇; 司西强; 王中华; 邵广兴; 王庆军; 邱正松


    针对常规质子酸催化合成出的甲基葡萄糖苷色泽深、收率低的问题,采用自制的负载型固体超强酸催化合成甲基葡萄糖苷。通过在活性炭上负载对甲苯磺酸、浓硫酸、磷钨酸等强酸,得到负载型超强酸催化剂CBSL。用CBSL催化剂催化合成甲基葡萄糖苷,得到的优化反应条件为:葡萄糖与甲醇物质的量之比为1∶8,催化剂加量为葡萄糖质量的5%,在140℃温度下反应4.0 h。自制产品和市售产品性能对比结果表明,自制甲基葡萄糖苷的岩心回收率明显高于市售产品,浓度为40%时,自制产品岩心回收率93.12%,市售产品岩心回收率90.13%;自制产品的润滑性能优于市售产品,当浓度为30%时,自制产品润滑系数0.08,市售产品润滑系数0.09,随着浓度的升高,市售产品的润滑系数均高于自制产品。自制产品的合成工艺及所用催化剂具有较好的工业放大前景。%In response of the problems of methyl glucoside has deep color and low yield which was synthe-sized by conventional proton catalyst,methyl glucoside was synthesized by supported super acid catalyst which was self-made. Supported super acid catalyst CBSL was got through some acid supported on activa-ted carbon, the acid including p-toluene sulfonic acid, concentrated sulfuric acid and phosphotungstic acid. The optimum reaction conditions for the synthesis of methyl glucoside catalyzed by CBSL catalyst were shown as follows:molar ratio of glucose and methanol was 1∶8 , catalyst dosage was 5% of glucose quality,reacted at the temperature of 140 ℃ for 4 h. Comparison performance results of self made and marketed products were shown that,the cutting recovery of homemade methyl glucoside was significantly higher than that of marketed products,at the concentration of 40%,home-made products cutting recovery rate is 93. 12%,the marketed products cutting recovery rate is 90. 13%; the lubrication performance of homemade products is

  17. 脂肪酶催化大豆卵磷脂和亚油酸酯交换反应的研究%Lipase catalyzed transesterification of soybean phosphatidylcholine and linoleic acid

    Institute of Scientific and Technical Information of China (English)

    凌文慧; 曹栋; 陈国安; 张显久


    Immobilized lipase Lipozyme TL IM -catalyzed transesterification of soybean phosphatidylcholine( PC, 90% ) with linoleic acid( LA, 95% ) was carried out in toluene. The six major factors of phosphatidylcholine concentration ( toluene as a solvent), substrate ratio ( molar ratio of LA to PC), lipase dosage (based on the mass of substrates), water addition (based on the mass of lipase), reaction time and reaction temperature were discussed. The optimum reaction conditions were as follows: PC concentration 0. 25 g/mL, molar ratio of LA to PC 6∶1, lipase dosage 20%, water addition 3%, 65℃ and 60 h. Under the optimum conditions, the maximum content of LA in the prouduct was 82.85%.%采用Lipozyme TL IM酶催化大豆卵磷脂(90%)和亚油酸(95%)进行酯交换反应,以制备富含亚油酸的卵磷脂.探讨了大豆卵磷脂质量浓度(甲苯为溶剂)、底物摩尔比(n(亚油酸):n(大豆卵磷脂))、酶添加量(以底物总质量为基准)、水分添加量(以酶质量为基准)、反应时间、反应温度对酯交换反应的影响.优化后的反应条件为:大豆卵磷脂质量浓度0.25g/ml,底物摩尔比6:1,酶添加量20%,水分添加量3%,反应时间60h,反应温度65℃.在最优反应条件下最终获得82.85%亚油酸含量的卵磷脂产品.

  18. Synthesis of Palm Acide Polyol Esters Catalyzed by Acidic Ionic Liquid%酸性离子液体催化合成棕榈油酸多元醇酯

    Institute of Scientific and Technical Information of China (English)

    牛玉莲; 邢宝妹; 陆杨; 李在均; 刘俊康; 黄路


    将5种酸性离子液体分别应用于棕榈油酸多元醇酯的合成反应,结果发现硫酸三乙基铵离子液体催化活性最大.利用硫酸三乙基铵盐的温控特点,设计出一种“高温反应”和“低温分离”相结合的棕榈油酸多元醇酯的合成方法,得到了合成棕榈油酸季戊四醇酯的最佳反应条件:油酸与季戊四醇的物质的量比为6:1,离子液体质量分数为5%,210℃的反应温度和3.5h的反应时间.在相应的最佳条件下,棕榈油酸季戊四醇酯、棕榈油酸三羟甲基丙烷酯、棕榈油酸二羟甲基新戊烷酯、棕榈油酸山梨醇酯和棕榈油酸1,3-丁二醇酯的转化率分别达94.6%,94.5%,97.0%,98.5%和99.2%.反应完成后,离子液体沉淀析出,可直接用于下一次的合成反应.对5种酯化产品理化性质的研究结果表明,棕榈油酸多元醇酯具有良好的流动及低温特性,其黏度指数和倾点范围分别在184~388和- 23~-40℃之间,可作为生物润滑剂基础油.%Five acidic ionic liquids were investigated to synthesize palm acide polyol esters, the results indicated triethylammonium sulfate offers best catalytic activity. Based on temperature-controlled characteristics of triethylammonium sulfate, we designed a novel method for preparation of palm acide polyol esters, in which the reaction under relatively high temperature combined with the separation of the ionic liquid under relatively low temperature. The optimal conditions to produce palm acide pentaerythritol esters were obtained, these include a6'l of palm acide/pentaerythritol, 5% of the ionic liquid, 210 ℃ of the reaction temperature and 3.5 h of reaction time. Under corresponding optimal conditions, five palm acide pentaerythritol esters, which includes palm acide pentaerythritol ester, palm acide trimethylolpropane ester, palm acide dihydroxymethylneopentane ester, palm acide sorbitol ester and palm acide 1,3-butanediol ester, were synthesized in the

  19. Catalyzing alignment processes

    DEFF Research Database (Denmark)

    Lauridsen, Erik Hagelskjær; Jørgensen, Ulrik


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

  20. 强酸性离子交换树脂催化大豆油脱臭馏出物连续酯化反应%Continuous esterification of soybean oil deodorizer distillate catalyzed by strong acidic ion exchange resin

    Institute of Scientific and Technical Information of China (English)

    曹玉平; 汪宝和; 陈学兵


    Free fatty acid esterification is the key step in the preparation of vitamin E and phytosterols from oil deodorizer distillate ( DD) , but the traditional esterification method has disadvantages, such as batch operation and easy equipment corrosion. Continuous esterification of soybean oil DD catalyzed by strong acidic ion exchange resin was studied. The influences of reaction temperature,feed flow rate,water content of raw material and volume ratio of methanol to soybean oil DD on the esterification reaction were investigated. The results showed that reducing the water content of raw material could promote the esterification reaction;the esterifcation rate of soybean oil DD could reach above 98% by two -step esterification under the conditions of reaction temperature 70 ℃ , volume ratio of methanol to soybean oil DD 1: 1 , feed flow rate 1 BV/h and water content of soybean oil DD 0. 05%%游离脂肪酸酯化是以油脂脱臭馏出物为原料,制备天然维生素E和植物甾醇的关键步骤,而传统酯化方法存在间歇操作、设备易腐蚀等缺点.以强酸性离子交换树脂为催化剂,对大豆油脱臭馏出物(DD油)的连续酯化反应进行了研究.考察了反应温度、进料流速、原料含水量以及醇油体积比对酯化反应的影响.结果表明:减少原料DD油中的含水量可促进酯化反应的进行,在反应温度70℃、醇油体积比1∶1、流速1 BV/h、DD油含水量0.05%的条件,通过二次酯化DD油酯化率可达到98%以上.

  1. 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


    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

  2. 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


    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。

  3. 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


    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.

  4. 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


    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.

  5. Study of Effect of Variation of Ionic Strength of the Medium on Velocity Constant of Ru(Iii Catalyzed Oxidation of Hydroxy Benzoic Acids by Chloramine-T in Acidic Medium

    Directory of Open Access Journals (Sweden)

    Dr. Parmod Kumar


    Full Text Available In the present study the effect of variation of ionic strength of the medium on rate of oxidation of hydroxy benzoic acids as its effect provides some clues regarding the nature of reactive species involved in the rate determining step. In order to realize the above aim the experiments has been carried out which ultimately concluded that ionic strength variation does not change the reaction velocity constant significantly.

  6. Production of Chemoenzymatic Catalyzed Monoepoxide Biolubricant: Optimization and Physicochemical Characteristics


    Jumat Salimon; Nadia Salih; Bashar Mudhaffar Abdullah


    Linoleic acid (LA) is converted to per-carboxylic acid catalyzed by an immobilized lipase from Candida antarctica (Novozym 435). This per-carboxylic acid is only intermediate and epoxidized itself in good yields and almost without consecutive reactions. Monoepoxide linoleic acid 9(12)-10(13)-monoepoxy 12(9)-octadecanoic acid (MEOA) was optimized using D-optimal design. At optimum conditions, higher yield% (82.14) and medium oxirane oxygen content (OOC) (4.91%) of MEOA were predicted at 15 μL ...

  7. Solvent-free lipase-catalyzed preparation of diacylglycerols. (United States)

    Weber, Nikolaus; Mukherjee, Kumar D


    Various methods have been applied for the enzymatic preparation of diacylglycerols that are used as dietary oils for weight reduction in obesity and related disorders. Interesterification of rapeseed oil triacylglycerols with commercial preparations of monoacylglycerols, such as Monomuls 90-O18, Mulgaprime 90, and Nutrisoft 55, catalyzed by immobilized lipase from Rhizomucor miehei (Lipozyme RM IM) in vacuo at 60 degrees C led to extensive (from 60 to 75%) formation of diacylglycerols. Esterification of rapeseed oil fatty acids with Nutrisoft, catalyzed by Lipozyme RM in vacuo at 60 degrees C, also led to extensive (from 60 to 70%) formation of diacylglycerols. Esterification of rapeseed oil fatty acids with glycerol in vacuo at 60 degrees C, catalyzed by Lipozyme RM and lipases from Thermomyces lanuginosus (Lipozyme TL IM) and Candida antarctica (lipase B, Novozym 435), also provided diacylglycerols, however, to a lower extent (40-45%). Glycerolysis of rapeseed oil triacylglycerols with glycerol in vacuo at 60 degrees C, catalyzed by Lipozyme TL and Novozym 435, led to diacylglycerols to the extent of acids with Monomuls resulted in minor reduction of its activity. The products of esterification of rapeseed oil fatty acids with Monomuls and glycerol yielded upon short-path vacuum distillation residues (diacylglycerol oils) containing 66-70% diacylglycerols.

  8. Study of In-Situ Compatibilization of PS/EPDM Blends Using Friedel-Crafts Alkylation%Friedel-Crafts烷基化反应就地增容PS/EPDM合金

    Institute of Scientific and Technical Information of China (English)

    焦淑瑞; 徐建平


    PS/EPDM melting blends were in—situ compatibilized by Friedel—crafts alkylation reaction.Effects of the amount of anhydrous aluminum chloride (AlCl3) on Friedel—Crafts alkylation between polystyrene (PS) and EPDM and properties of PS/EPDM blends were examined.The results showed that a copolymer of PS—g—EPDM can be formed during melting of blends via a Friedel—Crafts benzene ring alkylation with moderate catalyst amount.The grafting co—polymer behaved as a compatilizer of PS/EPDM blends and improved mechanical property and Thermal stability.Graft copolymerization reaction and degradation reaction are competitive in the reaction system, when the amount of AlCl3 was increased, the properties of blends became worse due to the chain scission of PS and EPDM and Properties of blends decreased.%利用Friel-Crafts烷基化反应就地增容PS/EPDM合金,考察了无水AlCl3用量对PS与EPDM间Friedel-Crafts烷基化反应及合金性能的影响.结果显示:加入适量的无水AlCl3可以引发PS、EPDM间产生Friedel-Crafts烷基化反应,生成PS-g-EPDM接枝共聚物;该接枝物起到相容剂作用,使PS/EPDM合金的力学性能、热稳定性等得到显著提高;反应体系存在接枝和降解两种竞争反应;加大A1Cl3用量后,由于PS、EPDM分子链的降解反应起主导作用,合金的性能降低.

  9. Regioselective Palladium-Catalyzed Cross-Coupling Reactions of 2,4,7-Trichloroquinazoline. (United States)

    Wipf, Peter; George, Kara M


    The regioselective palladium-catalyzed cross-coupling reactions of 2,4,7-trichloroquinazoline with various aryl- and heteroarylboronic acids are reported. An efficient, sequential strategy was developed that provides access to novel, functionalized heterocycles.

  10. Lipase-catalyzed synthesis of monoacylglycerol in a homogeneous system. (United States)

    Monteiro, Julieta B; Nascimento, Maria G; Ninow, Jorge L


    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.

  11. Gas Chromatographic Analysis of Medium Chain Fatty Acids in Coconut Oil

    Directory of Open Access Journals (Sweden)

    Julius Pontoh


    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.

  12. 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


    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

  13. One-pot green synthesis of 1,3,5-triarylpentane-1,5-dione and triarylmethane derivatives as a new class of tyrosinase inhibitors. (United States)

    Zheng, Zong-Ping; Zhang, Yi-Nan; Zhang, Shuang; Chen, Jie


    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.

  14. 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.


    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.

  15. Gold-Catalyzed Synthesis of Heterocycles (United States)

    Arcadi, Antonio


    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

  16. 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


    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.

  17. Efficient synthesis of β-chlorovinylketones from acetylene in chloroaluminate ionic liquids. (United States)

    Snelders, Dennis J M; Dyson, Paul J


    A method for the Friedel-Crafts-type insertion reaction of acetylene with acid chlorides in chloroaluminate ionic liquids is presented. The use of ionic liquids not only serves to avoid the use of carbon tetrachloride or 1,2-dichloroethane but also suppresses side reactions, notably the polymerization of acetylene, which occurs in these chlorinated solvents. Consequently, the products can be isolated using a simpler purification procedure, giving a range of aromatic and aliphatic β-chlorovinyl ketones in high yield and purity.

  18. 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


    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

  19. 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


    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.

  20. 固体超强酸TiO2/SO4 2-催化合成水杨酸异辛酯%The Synthesis of Iso-Octyl Salicylate Catalyzed by Solid Super Acid TiO2/SO4 2-

    Institute of Scientific and Technical Information of China (English)

    范平; 葛春华; 唐宪达; 毕琪; 唐慧婷; 李鸿图


    In this paper,the synthesis of iso-octyl salicylate was catalyzed by the solid super acid TiO2/SO4 2-taking the place of conc.H2SO4.According to experimental results,the optimum condition of esterfication were:salicylic acid/iso-octyl alcohol = 1/3(molar ratio),catalyst 9%(based on the weight of salicylic acid),reacting time 3.5h and the conversion rate of salicylic acid 98.2%.%报告了以固体超强酸TiO2/SO4 2-为催化剂催化合成水杨酸异辛酯.当水杨酸:异辛醇=1:3(摩尔比),催化剂用量为水杨酸的9%(重量比),反应温度185~195℃,反应3.5h,水杨酸转化率达98.2%.

  1. Asymmetric Stetter reactions catalyzed by thiamine diphosphate-dependent enzymes. (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


    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.

  2. Palladium-Catalyzed Nucleophilic Substitution of Alcohols : Mechanistic Studies and Synthetic Applications


    Sawadjoon, Supaporn


    This thesis deals with the palladium-catalyzed nucleophilic substitution of π-activated alcohols in which the C–O bond of a non-manipulated hydroxyl group is cleaved. The thesis is divided in two chapters describing two different catalytic systems. Chapter 2 describes a heterogeneous palladium-catalyzed transfer hydrogenolysis of primary, secondary, and tertiary benzylic alcohols to generate the corresponding aromatic hydrocarbons using formic acid as the hydrogen donor. A detailed mechanisti...

  3. Use of a palladium(II)-catalyzed oxidative kinetic resolution in synthetic efforts toward bielschowskysin. (United States)

    Meyer, Michael E; Phillips, John H; Ferreira, Eric M; Stoltz, Brian M


    Progress toward the cyclobutane core of bielshowskysin is reported. The core was thought to arise from a cyclopropane intermediate via a furan-mediated cyclopropane fragmentation, followed by a 1,4-Michael addition. The synthesis of the cyclopropane intermediate utilizes a Suzuki coupling reaction, an esterification with 2-diazoacetoacetic acid, and a copper catalyzed cyclopropanation. An alcohol intermediate within the synthetic route was obtained in high enantiopurity via a highly selective palladium(II)-catalyzed oxidative kinetic resolution (OKR).

  4. 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.;


    to ortho in homopyrimidine TINAs. Thus, for para-TINAs the bulge insertion of an intercalator led to high thermal stability of Hoogsteen-type parallel triplexes and duplexes, whereas Watson-Cricktype duplexes were destabilized. In the case of ortho-TINA, both Hoogsteen and Watson-Crick-type complexes were...... 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......,3-dichloro-5,6-dicyanoACHTUNGTRENUNG-1,4-benzoquinone, and a Vilsmeier-Haack-Arnold transformation followed by a Bodendorf fragmentation. Significant alterations in thermal stability of parallel triplexes and antiparallel duplexes were observed upon changing the attachment of ethynylpyrenes from para...

  5. The mechanism of Fe (Ⅲ)-catalyzed ozonation of phenol

    Institute of Scientific and Technical Information of China (English)

    竹湘锋; 徐新华


    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.

  6. Rhodium(III)-Catalyzed C-H Activation Mediated Synthesis of Isoquinolones from Amides and Cyclopropenes. (United States)

    Hyster, Todd K; Rovis, Tomislav


    We have developed a synthesis of 4-substituted isoquinolones from the Rh(III)-catalyzed, C-H activation mediated, coupling of O-pivaloyl benzhydroxamic acids and 3,3-disubstituted cyclopropenes. Experiments suggest the formation of a [4.1.0] bicyclic-system, which can open under acidic conditions to generate the desired isoquinolone.

  7. Rhodium(III)-Catalyzed C–H Activation Mediated Synthesis of Isoquinolones from Amides and Cyclopropenes (United States)

    Hyster, Todd K.; Rovis, Tomislav


    We have developed a synthesis of 4-substituted isoquinolones from the Rh(III)-catalyzed, C–H activation mediated, coupling of O-pivaloyl benzhydroxamic acids and 3,3-disubstituted cyclopropenes. Experiments suggest the formation of a [4.1.0] bicyclic-system, which can open under acidic conditions to generate the desired isoquinolone. PMID:25346576

  8. An efficient synthesis of isocoumarins via a CuI catalyzed cascade reaction process

    Institute of Scientific and Technical Information of China (English)


    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.


    Institute of Scientific and Technical Information of China (English)

    张俊琪; 樊金红; 马鲁铭; 戴海润


    绍兴市工业园区某污水处理厂二期工程接收的主要是印染废水,以及部分酸性化工废水.由于化工废水的pH低,成分复杂,色度高,可生化性差,对生物处理系统冲击较大,为此,开展了催化铁内电解法处理酸性化工废水,出水与印染废水混合后进行混凝的研究.结果表明,pH是影响催化铁内电解体系对化工废水pH的调节能力、Fe2+产生浓度、COD去除率以及B/C的主要因素.催化铁内电解法处理酸性化工废水2h后反应出水的铁离子质量浓度在800~2500mg/L,将其与印染废水混合后进行混凝,混凝的最适反应条件为pH≥8,Fe2+质量浓度120mg/L.其处理效果与投加亚铁盐混凝相当,既充分利用了催化铁预处理所产生的高浓度铁离子,并且提高了化工废水的B/C,减小了其所含难降解污染物对生化系统的不利影响,又减少了碱的用量,同时亦实现了化工与印染废水的综合预处理.%Shaoxin Industrial Park sewage treatment plant phase II received mostly printing and dyeing wastewater, as well as some acidic wastewater. the low pH, complex components, high chroma, poor biodegradability of the chemical wastewater led to a strong impact on the biological treatment system, therefore, research of catalyzed iron internal electrolysis process acidic chemical wastewater, effluent water mixed with printing and dyeing wastewater and coagulation was carried out. The results showed that: pH was the main factor that influence of catalyzed iron internal electrolysis method for treating chemical industry wastewater in pH regulation ability, Fe2+ concentration, the removal rate of COD and B/C. The acidic chemical wastewater treated by catalyzed iron internal electrolysis for 2 h, concentration of iron ions was 800~2 500 mg/L, mixed it with printing and dyeing wastewater and coagulation, the optimum reaction conditions were pH≧8, Fe2+ concentration 120 mg/L. The treatment effect was the same compared

  10. Thermodynamics of Enzyme-Catalyzed Reactions Database (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.

  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)


    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. Mechanism of Intramolecular Rhodium- and Palladium-Catalyzed Alkene Alkoxyfunctionalizations

    KAUST Repository

    Vummaleti, Sai V. C.


    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.

  13. Iridium-Catalyzed Allylic Substitution (United States)

    Hartwig, John F.; Pouy, Mark J.

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

  14. Route to Renewable PET: Reaction Pathways and Energetics of Diels–Alder and Dehydrative Aromatization Reactions Between Ethylene and Biomass-Derived Furans Catalyzed by Lewis Acid Molecular Sieves



    Silica molecular sieves that have the zeolite beta topology and contain framework Lewis acid centers (e.g., Zr-β, Sn-β) are useful catalysts in the Diels–Alder and dehydrative aromatization reactions between ethylene and various renewable furans for the production of biobased terephthalic acid precursors. Here, the main side products in the synthesis of methyl 4-(methoxymethyl)benzene carboxylate that are obtained by reacting ethylene with methyl 5-(methoxymethyl)-furan-2-carboxylate are iden...

  15. Quantitation of acyl migration during lipase-catalyzed acidolysis, and of the regioisomers of structured triacylglycerols formed

    DEFF Research Database (Denmark)

    Mu, Huiling; Kurvinen, J.P.; Kallio, H.;


    Various MLM-type (M, medium-chain fatty acids; L, long-chain fatty acids) structured triacylglycerols were produced in pilot- or small-scale packed-bed reactors by lipase-catalyzed acidolysis. The incorporation and acyl migration of octanoic acid were measured by gas chromatography and Grignard d...

  16. 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


    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.

  17. Production ofα-linoleic acid enriched soy phospholipids catalyzed by phospholipase A1(Lecitase® Ultra)%磷脂酶A1(Lecitase® Ultra)催化合成富含α-亚油酸结构磷脂研究

    Institute of Scientific and Technical Information of China (English)

    邹玲; 汪勇; 姚胜文; 张震; 李爱军


      Structured phospholipids were successfully produced by lipase–catalyzed transesterification between soybean phospholipids and linoleic acid in hexane. Three commercially available immobilized lipases,one liquid lipase and one liquid phospholipases were screened and Phospholipase A1(Lecitase® Ultra)was finally selected for further optimization. By an orthogonal experiment,the optimal conditions were obtained as follows:phospholipids concentration(phospholipids/hexane)0.20 g/mL, molar ratio of linoleic acid to soybean phospholipids 4∶1,lipase dosage(based on phospholipids, v/w)18%,reaction temperature 53℃,and reaction time 24 h. Under such conditions,α–linoleic acid content reached 77.09%in the fatty acid profile of the structured phospholipids.%  在正己烷体系中,酶催化亚油酸与大豆粉末磷脂进行酯交换反应,制备富含α–亚油酸结构磷脂.从三种常用固定化脂肪酶,一种液态脂肪酶和一种液态磷脂酶中筛选出其中最优磷脂酶A1(Lecitase® Ultra)催化合成结构磷脂.通过单因素和正交优化试验得出最优反应条件为:大豆磷脂质量浓度0.20 g/mL、底物物质量比(亚油酸/磷脂)为4∶1、酶添加量(以磷脂质量计,v/w)18%、反应时间24 h、反应温度53℃;在此条件下,获得结构磷脂产品α–亚油酸含量可达77.09%.

  18. Gold(I)-catalyzed Claisen rearrangement of allenyl vinyl ethers: missing transition states revealed through evolution of aromaticity, Au(I) as an oxophilic Lewis acid, and lower energy barriers from a high energy complex. (United States)

    Vidhani, Dinesh V; Cran, John W; Krafft, Marie E; Manoharan, Mariappan; Alabugin, Igor V


    Curtin-Hammett analysis of four alternative mechanisms of the gold(I)-catalyzed [3,3] sigmatropic rearrangement of allenyl vinyl ethers by density functional theory calculations reveals that the lowest energy pathway (cation-accelerated oxonia Claisen rearrangement) originates from the second most stable of the four Au(I)-substrate complexes in which gold(I) coordinates to the lone pair of oxygen. This pathway proceeds via a dissociative transition state where the C-O bond cleavage precedes C1-C6 bond formation. The alternative Au(I) coordination at the vinyl π-system produces a more stable but less reactive complex. The two least stable modes of coordination at the allenyl π-system display reactivity that is intermediate between that of the Au(I)-oxygen and the Au(I)-vinyl ether complexes. The unusual electronic features of the four potential energy surfaces (PESs) associated with the four possible mechanisms were probed with intrinsic reaction coordinate calculations in conjunction with nucleus independent chemical shift (NICS(0)) evaluation of aromaticity of the transient structures. The development of aromatic character along the "6-endo" reaction path is modulated via Au-complexation to the extent where both the cyclic intermediate and the associated fragmentation transition state do not correspond to stationary points at the reaction potential energy surface. This analysis explains why the calculated PES for cyclization promoted by coordination of gold(I) to allenyl moiety lacks a discernible intermediate despite proceeding via a highly asynchronous transition state with characteristics of a stepwise "cyclization-mediated" process. Although reaction barriers can be strongly modified by aryl substituents of varying electronic demand, direct comparison of experimental and computational substituent effects is complicated by formation of Au-complexes with the Lewis-basic sites of the substrates.

  19. Glycerol Dehydration to Acrolein Catalyzed by ZSM‐5 Zeolite in Supercritical Carbon Dioxide Medium (United States)

    Zou, Bin; Ren, Shoujie


    Abstract Supercritical carbon dioxide (SC‐CO2) has been used for the first time as a reaction medium for the dehydration of glycerol to acrolein catalyzed by a solid acid. Unprecedented catalyst stability over 528 hours of time‐on‐stream was achieved and the rate of coke deposition on the zeolite catalyst was the lowest among extensive previous studies, showing potential for industrial application. Coking pathways in SC‐CO2 were also elucidated for future development. The results have potential implications for other dehydration reactions catalyzed by solid acids. PMID:27796088

  20. Transition metal-catalyzed functionalization of pyrazines

    NARCIS (Netherlands)

    Nikishkin, Nicolai I.; Huskens, Jurriaan; Verboom, Willem


    Transition metal-catalyzed reactions are generally used for carbon–carbon bond formation on pyrazines and include, but are not limited to, classical palladium-catalyzed reactions like Sonogashira, Heck, Suzuki, and Stille reactions. Also a few examples of carbon–heteroatom bond formation in pyrazine