- A green protocol for chemoselective O-acylation in the presence of zinc oxide as a heterogeneous, reusable and eco-friendly catalyst
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The solvent-free acylation of alcohols and phenols with acyl chlorides using ZnO as a catalyst is described. The remarkable selectivity under mild and neutral conditions, and recyclability of the catalyst, are advantages.
- Tamaddon, Fatemeh,Amrollahi, Mohammad Ali,Sharafat, Leily
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- Continuous flow Fischer esterifications harnessing vibrational-coupled thin film fluidics
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Rapid Fischer esterification reactions occur under solventless, continuous flow conditions in dynamic thin films. This methodology uses limited catalyst, require no additional heat input and occurs within the confinements of an inexpensive vortex fluidic device (VFD). The associated mechanoenergy is primarily delivered from two types of vibration, which are manifested in sharp increases in the yield of the reactions. These vibrations promote the existence of Faraday waves that alter the instantaneous shear rates of the reactants within the rotating tube. Tuning the rotational speed of the device allows harmonic vibrations to be utilized in the synthesis of alkyl-based esters within both a high and low contact angle NMR tube. This journal is
- Britton, Joshua,Dalziel, Stuart B.,Raston, Colin L.
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- Enantiomeric two-fold interpenetrated 3D zinc(ii) coordination networks as a catalytic platform: significant difference between water within the cage and trace water in transesterification
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Self-assembly of Zn(ClO4)2 with 1,1,2,2-tetramethyl-1,2-di(pyridin-3-yl)disilane (L) as a bidentate N-donor gives rise to 3D coordination networks, [Zn(μ-OH)(L)]3(ClO4)3·5H2O (1·5H2O), of unique, 103-a srs net topology. An important feature is that two enantiomeric 3D frameworks, 41- and 43-[Zn(μ-OH)(L)]3(ClO4)3·5H2O, are interpenetrated to form a racemic two-fold 3D network with cages occupied by two water molecules. Another structural characteristic is a C3-symmetric planar Zn3(μ-OH)3 6-membered ring with tetrahedral Zn(ii) ions. The steric hindrance of substrates and trace water effects on transesterification catalysis using the network have been scrutinized. The coordination network acts as a remarkable heterogeneous transesterification catalytic system that shows both the significant steric effects of substrate alcohols and momentous water effects. The substrate activity is in the order ethanol > n-propanol > n-butanol > iso-propanol > 2-butanol > tert-butanol. For the reaction system, solvate water molecules within the cages of the interpenetrated 3D frameworks do not decrease the transesterification activity, whereas the trace water molecules in the substrate alcohols act as obvious obstacles to the reaction.
- Choi, Eunkyung,Ryu, Minjoo,Lee, Haeri,Jung, Ok-Sang
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- (S)-2-pentyl (R)-3-hydroxyhexanoate, a banana volatile and its olfactory recognition by the common fruit fly, Drosophila melanogaster
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The volatile organic compounds emitted from ripening bananas that elicit an antennal response from the common fruit fly, Drosophila melanogaster, were analyzed by a combination of gas chromatographic-electroantennographic detection, mass spectrometry, and 1H NMR spectroscopy. These analyses revealed that the headspace of ripening bananas contains a number of EAD-active components including the new ester (S)-2-pentyl (R)-3-hydroxyhexanoate, the structural assignment of which was confirmed by chemical synthesis.
- Mowat, Jeffrey,Gries, Regine,Khaskin, Grigori,Gries, Gerhard,Britton, Robert
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- Baeyer-Villiger oxidation of ketones with hydrogen peroxide catalyzed by Sn-palygorskite
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Palygorskite-supported Sn complexes were prepared by a simple procedure. Cyclic ketones and acyclic ketones were oxidized by hydrogen peroxide in a reaction catalyzed by palygorskite-supported Sn complexes, affording corresponding lactones or esters with selectivity for the product of 90-100%. The catalysts can be recycled for several times without significant decline in catalytic activity.
- Lei, Ziqiang,Zhang, Qinghua,Luo, Jujie,He, Xiaoyan
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- A method for the acetylation of alcohols catalyzed by heteropolyoxometallates
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Esterifications of acetic acid with some linear, secondary, tertiary, and benzylic alcohols mediated by catalytic amounts of Keggin, Wells-Dawson, and Preyssler type heteropolyacids were carried out under reflux at mild reaction conditions with good to excellent yields. Among the examined catalysts, H 3PW12O40 and H14NaP 5W30O110 revealed better results than other heteropolyacids. This work was performed with the aim of simplifying the esterification process by omitting any solvents and mineral acid catalysts. Easy work-up, low cost, and acidic waste reduction, which are all important features from the environmental and economical points of view, are distinct aspects of this protocol. Heteropolyacid catalysts could be separated after a simple work-up and reused for several times.
- Alizadeh, Mohammad H.,Kermani, Toktam,Tayebee, Reza
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- Vanadyl sulfate (VOSO4.3H2O). An efficient catalyst for acylation of alcohols and phenols under solvent free condition
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Alcohols and phenols were efficiently acylated with acetic anhydride in the presence of vanadyl sulfate (VOSO4.3H2O) at room temperature in high yields.
- Oskooie, Hossein A.,Baghernezhad, Bita,Heravi, Majid M.,Beheshtiha
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- Acid-catalyzed oxidation of levulinate derivatives to succinates under mild conditions
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Levulinate derivatives are an attractive platform for the production of renewable chemicals. Here we report on the oxidation of methyl levulinate into dimethyl succinate with peroxides under mild conditions using Br?nsted and Lewis acid catalysts. Selectivities to succinate and acetate derivatives of approximately 60 and 40 %, respectively, were obtained with strong Br?nsted acids in methanol. Although the molecular structure (i.e., carbon-chain length and branching around the C=O group) and the oxidant type affect the product distribution, solvent choice has the strongest impact on changing the location of oxygen insertion into the carbon backbone. Specifically, switching the solvent from methanol to heptane resulted in a decrease in the succinate/acetate ratio from 1.6 to 0.3. In contrast to Br?nsted acids, we demonstrate that the nature of the metal cation is responsible for changing the reaction selectivity of water-tolerant Lewis acidic triflate salts.
- Wang, Yuran,Vogelgsang, Ferdinand,Román-Leshkov, Yuriy
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- Synthesis, characterization, and crystal structure of several novel acidic ionic liquids based on the corresponding 1-alkylbenzimidazole with tetrafluoroboric acid
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A series of acidic task-specific ionic liquids 1-R2-2-R 1benzimidazolium tetrafluoroborate (R1 = Me, R2 = Me, Et, Pr-n, Bu-n, Pen-n) were prepared by simple acid-base neutralization of the corresponding 1-alkylbenzimidazole and tetrafluoroboric acid. The compounds were characterized by FTIR spectra, elemental analysis, 1HNMR spectra and thermogravimetric analysis. These new ionic liquids are nonvolatile, and have potential use as alternatives to conventional organic solvents due to their solubility and thermal stability. These novel tetrafluoroborate salts show good catalytic activity to esterification of carboxylic acids with alcohols under mild reaction conditions, which could maintain good catalytic performance after recycling at least six times. Furthermore, a crystal of one compound, [H-bmBim]BF4, was prepared, with the crystal structure determined by X-ray diffraction analysis. The molecular structure is formed by weak π-π interactions and intermolecular hydrogen bonds between the benzimidazole rings, yielding a three-dimensional net-like supramolecule.
- Chen, Shuan-Hu,Yang, Fen-Rong,Wang, Ming-Tian,Wang, Na-Ni
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- Carboxylic acids to butyl esters over dealuminated-realuminated beta zeolites for removing organic acids from bio-oils
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This article describes a novel method to dealuminate and realuminate H-beta zeolites as catalysts for removing organic acids from bio-oils via their esterification reactions with alcohols. Modified H-beta zeolites were prepared by leaching with solutions of oxalic acid, dl-malic acid, and dl-tartaric acid that have different numbers of hydroxyl groups. The results showed that, while all three organic acids can dealuminate the parent H-beta zeolite, with Al(vi)a atoms and Al(iv)c ones being preferentially removed, they show quite different realumination abilities, with tartaric acid with two hydroxyl groups having the highest realumination ability. The concomitance of dealumination and realumination and their dependence on the hydroxyl group numbers of the organic acids provide the possibility of finely tuning the Al and acidity distributions of the resulting zeolites. Among the three acid treated H-beta zeolites, the one obtained from malic acid leaching exhibited the best performance in catalyzing the esterification reaction between acetic acid and sec-butyl alcohol, attributed to its suitable quantity and density of medium and strong Br?nsted acid sites and enhanced aluminum gradient. The catalytic results obtained in a fixed-bed microreactor revealed that the malic acid leached H-beta exhibited dramatically enhanced catalytic performance compared to the commercial ion-exchange resin Amberlyst 15, demonstrating great potential for industrial application.
- Li, Jianhua,Liu, Haiyan,An, Tingting,Yue, Yuanyuan,Bao, Xiaojun
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- Keggin-type mono lacunary silicotungstate supported onto zirconia: Synthesis, characterization, and esterification reaction
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A solid acid catalyst comprising of lacunary silicotungstate and zirconia was synthesized and characterized by physicochemical techniques. Surface morphologies of support and catalyst were studied by scanning electron microscopy. Catalytic properties were evaluated for the esterification of n-butanol with acetic acid. Esterifications of sec-butanol and isobutanol with acetic acid as well as the esterification of n-butanol with different acids such as formic acid and propionic acid were carried out under optimized conditions. Catalytic activities for calcined as well as recycled catalysts were also evaluated for the esterification under optimized condition.
- Pathan, Soyeb,Patel, Anjali
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- Effective management of polyethers through depolymerization to symmetric and unsymmetric glycol diesters using a proton-exchanged montmorillonite catalyst
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From the standpoint of green sustainable chemistry, it is very important to build a resource recycling system. Herein, an efficient and practical method for catalytic depolymerization of polyethers to glycol diesters was developed using proton-exchanged montmorillonite (H-mont). H-mont uniquely exhibited high catalytic activity for the depolymerization of polyethers with benzoic anhydride to symmetric glycol dibenzoates under mild reaction conditions. Various symmetric and unsymmetric glycol diesters were obtained from the reaction of diverse polyethers with carboxylic acid derivatives. The high catalytic efficiency for this depolymerization of H-mont is interpreted by its character, in which the montmorillonite layers act as an effective two-dimensional macroligand to form the intercalated complex with polyethers. Furthermore, a new protocol for the utilization of waste polyethers in water was developed based on the catalytic and adsorption abilities of H-mont.
- Maeno, Zen,Yamada, Shota,Mitsudome, Takato,Mizugaki, Tomoo,Jitsukawa, Koichiro
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- Measurement of equilibrium constants for the formation of esters from aliphatic carboxylic acids and alcohols
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A method for assessing the magnitude of esterification equilibrium constants for a series of alkyl acetates is described. The constants are quite sensitive to electronic effects, with the largest values being obtained for those in which the alkyl groups are electron donating.
- Lee, Donald G.,Yan, Yongfel,Chandler, W. David
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- Heteropoly acid supported modified Montmorillonite clay: An effective catalyst for the esterification of acetic acid with sec-butanol
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Esterifications of acetic acid with sec-butanol catalysed by supported dodecatungstophosphoric acid, H3PW12O40 (DTP) on acid modified Montmorillonite clay (AT-Mont) matrix have been carried out. A series of catalysts having 5%, 10%, 20% and 30% loading of DTP on different AT-Mont (15 min to 4 h) were synthesized and evaluated as catalysts; 20% DTP loaded on acid activated (15 min) clay showed the highest catalytic activity with about 80% conversion, having nearly 100% selectivity towards sec-butyl acetate. The high catalytic activity may be due to a high dispersion of the DTP on AT-Mont, providing more surface area (120 m2/g) and active sites than pure HPA. The variation of different reaction parameters, such as reaction temperature, reaction time, mole ratio of acid and alcohol and catalyst amount, on the conversion of acetic acid were studied. The samples were characterized by surface area, cation exchange capacity (CEC) measurements, TGA-DTA and FTIR spectroscopy.
- Bhorodwaj, Siddhartha Kumar,Dutta, Dipak Kumar
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- Clean and selective Baeyer-Villiger oxidation of ketones with hydrogen peroxide catalyzed by Sn-palygorskite
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An environmentally benign and selective Baeyer-Villiger oxidation system is introduced. Palygorskite-supported Sn complexes were prepared by a simple procedure. Cyclic ketones and acyclic ketones were oxidized by hydrogen peroxide in a reaction catalyzed by palygorskite-supported Sn complexes, affording corresponding lactones or esters with selectivity for the product of 90-99%. The influence of the solvents, reaction temperature, the amount of catalyst used and the reaction time on the catalytic activity and product selectivity were investigated in detail. The catalyst is cheap, easy to be prepared in large scale and can be recycled.
- Lei, Ziqiang,Zhang, Qinghua,Wang, Rongmin,Ma, Guofu,Jia, Chengguo
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- High pressure mechanistic diagnosis in Baeyer-Villiger oxidation of aliphatic ketones
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The pressure effect is examined in Baeyer-Villiger oxidation of aliphatic ketones. This effect is small, reflected in slightly negative activation volumes (-2 to -8 cm3 mol-1). These values allow the picturing of the volume profile. They refer to a late transition step and give support for a rate-determining migration step experiencing full concertedness.
- Jenner, Gérard
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- Fabricating nickel phyllosilicate-like nanosheets to prepare a defect-rich catalyst for the one-pot conversion of lignin into hydrocarbons under mild conditions
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The one-pot conversion of lignin biomass into high-grade hydrocarbon biofuels via catalytic hydrodeoxygenation (HDO) holds significant promise for renewable energy. A great challenge for this route involves developing efficient non-noble metal catalysts to obtain a high yield of hydrocarbons under relatively mild conditions. Herein, a high-performance catalyst has been prepared via the in situ reduction of Ni phyllosilicate-like nanosheets (Ni-PS) synthesized by a reduction-oxidation strategy at room temperature. The Ni-PS precursors are partly converted into Ni0 nanoparticles by in situ reduction and the rest remain as supports. The Si-containing supports are found to have strong interactions with the nickel species, hindering the aggregation of Ni0 particles and minimizing the Ni0 particle size. The catalyst contains abundant surface defects, weak Lewis acid sites and highly dispersed Ni0 particles. The catalyst exhibits excellent catalytic activity towards the depolymerization and HDO of the lignin model compound, 2-phenylethyl phenyl ether (PPE), and the enzymatic hydrolysis of lignin under mild conditions, with 98.3% cycloalkane yield for the HDO of PPE under 3 MPa H2 pressure at 160 °C and 40.4% hydrocarbon yield for that of lignin under 3 MPa H2 pressure at 240 °C, and its catalytic activity can compete with reported noble metal catalysts.
- Cao, Meifang,Chen, Bo,He, Chengzhi,Ouyang, Xinping,Qian, Yong,Qiu, Xueqing
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supporting information
p. 846 - 857
(2022/02/09)
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- Molybdenum-modified mesoporous SiO2as an efficient Lewis acid catalyst for the acetylation of alcohols
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A suitable, expeditious and well-organized approach for the acetylation of alcohols with acetic anhydride in the presence of 5%MoO3-SiO2 as an optimum environmentally benign heterogeneous catalyst was developed. The high surface area obtained for 5%MoO3-SiO2, 101 m2 g-1 compared to other catalysts, 22, 23, and 44 m2 g-1 for 5%WO3-ZrO2, 5%WO3-SiO2, and 5%MoO3-ZrO2, respectively, appears to be the driving force for better catalytic activity. Amongst the two dopants used, molybdenum oxide is the better dopant compared to its tungsten oxide counterpart. High yields of up to 86% were obtained with MoO3 doping while WO3 containing catalysts did not show any activity. Other reaction parameters such as reactor stirring speed, and solvent variation were studied and revealed that the optimum stirring speed is 400 rpm and cyclohexane is the best solvent. Thus, the utilization of affordable and nontoxic materials, short reaction times, reusability, and producibility of excellent yields of the desired products are the advantages of this procedure.
- Hlatshwayo, Xolani S.,Ndolomingo, Matumuene Joe,Bingwa, Ndzondelelo,Meijboom, Reinout
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p. 16468 - 16477
(2021/05/19)
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- Application of Yttrium Iron Garnet as a Powerful and Recyclable Nanocatalyst for One-Pot Synthesis of Pyrano[2,3-c]pyrazole Derivatives under Solvent-Free Conditions
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The application of yttrium iron garnet (YIG) superparamagnetic nanoparticles as a new recyclable and highly efficient heterogeneous magnetic catalyst for one-pot synthesis of pyrano[2,3-c]pyrazole derivatives under solvent-free conditions, as well as etherification and esterification reactions are described. The advantages of the proposed method include the lack of organic solvents, clean reaction, rapid removal of the catalyst, short reaction times, excellent yields, and recyclability of the catalyst.
- Sedighinia,Badri,Kiasat
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p. 1755 - 1763
(2020/01/11)
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- METHOD FOR PRODUCING FLUORINATED HYDROCARBON
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PROBLEM TO BE SOLVED: To provide a method for industrially advantageously producing a fluorinated hydrocarbon. SOLUTION: The method for producing a fluorinated hydrocarbon represented by formula (3) comprises bringing a secondary or tertiary ether compound represented by formula (1) into contact with an acid fluoride represented by formula (2) in the presence of a compound having an N-X bond (X is a halogen atom selected from a chlorine atom, a bromine atom, and an iodine atom) in a halogenated hydrocarbon-based solvent. (R1 and R2 are each independently a C1-C3 alkyl group; R3 is H, a methyl group, or an ethyl group; R4 and R5 are each a methyl group or an ethyl group; and R1 and R2 may be bonded together to form a ring structure.) SELECTED DRAWING: None COPYRIGHT: (C)2018,JPOandINPIT
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Paragraph 0062; 0072
(2018/03/09)
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- METHOD FOR PRODUCING FLUORINATED HYDROCARBON
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PROBLEM TO BE SOLVED: To provide an industrially advantageous method for producing a fluorinated hydrocarbon such as 2-fluorobutane useful as etching gas for a dry etching process. SOLUTION: There is provided a method for producing a fluorinated hydrocarbon represented by formula (3) by bringing an ether compound represented by formula (1) into contact with an acid fluoride represented by formula (2) in a halogenated hydrocarbon solvent in the presence of a metal halide represented by formula (4): MX3 (M represents a metal atom; X represents a chlorine atom or a bromine atom) (R1 and R2 each independently represent an alkyl group having 1-3 carbon atoms; R1 and R2 may be bonded to form a ring structure; R3 represents H, a methyl group or an ethyl group; R4 and R5 each independently represent a methyl group or an ethyl group.) SELECTED DRAWING: None COPYRIGHT: (C)2017,JPOandINPIT
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Paragraph 0054; 0073; 0077
(2017/10/31)
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- Template-free sol–gel synthesis of high surface area mesoporous silica based catalysts for esterification of di-carboxylic acids
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High surface area mesoporous silica based catalysts have been prepared by a simple hydrolysis/sol–gel process without using any organic template and hydrothermal treatment. A controlled hydrolysis of ethyl silicate-40, an industrial bulk chemical, as a silica precursor, resulted in the formation of very high surface area (719?m2/g) mesoporous (pore size 67?? and pore volume 1.19?cc/g) silica. The formation of mesoporous silica has been correlated with the polymeric nature of the ethyl silicate-40 silica precursor which on hydrolysis and further condensation forms long chain silica species which hinders the formation of a close condensed structure thus creating larger pores resulting in the formation of high surface mesoporous silica. Ethyl silicate-40 was used further for preparing a solid acid catalyst by supporting molybdenum oxide nanoparticles on mesoporous silica by a simple hydrolysis sol–gel synthesis procedure. The catalysts showed very high acidity as determined by NH3-TPD with the presence of Lewis as well as Br?nsted acidity. These catalysts showed very high catalytic activity for esterification; a typical acid catalyzed organic transformation of various mono- and di-carboxylic acids with a range of alcohols. The in situ formed silicomolybdic acid heteropoly-anion species during the catalytic reactions were found to be catalytically active species for these reactions. Ethyl silicate-40, an industrial bulk silica precursor, has shown a good potential for its use as a silica precursor for the preparation of mesoporous silica based heterogeneous catalysts on a larger scale at a lower cost.
- More, Pavan M.,Umbarkar, Shubhangi B.,Dongare, Mohan K.
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p. 1247 - 1253
(2016/10/13)
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- Production method for low-carbon acetate
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The invention relates to a production method for low-carbon acetate. In the method, a catalyst based on an ionic liquid is employed to catalyze low-carbon olefin and acetic acid to be directly subjected to an additive polymerization reaction to produce the low-carbon acetate, wherein the cation in the ionic liquid is represented as the following structure formula, and the anions include: HSO4, CF3SO3, NTf2, H2PO4, PW12O40, p-CH3-(C6H4)SO3, PMo12O40, H2PW12O40, X, PF6 or SbF6. The ionic liquid catalyst can convert mixed butene into sec-butyl acetate at high selectivity. The catalyst is stable in structure and is easy to separate. The production method is simple in follow-up operations, is less in side products, is low in corrosion and is low in environment pollution.
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Paragraph 0047; 0048; 0049; 0050
(2016/10/27)
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- A process for the preparation of acetic acid-butyl
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The invention discloses a preparation method of alcohol sec-butyl acetate. According to the method, acetic acid and butylene are used as raw materials, ion-exchange resin is used as a catalyzer, reaction is performed under the action of nitrogen and hydrogen mixture, the mol ratio of hydrogen to nitrogen in the nitrogen and hydrogen mixture is 1:1 to 10:1, and the hydrogen partial pressure of the hydrogen in a reaction system is 0.4 to 2.4 MPa. The method can not only reduce the generation of C8 olefin which is difficult to separate, but also be operated stably during a long period.
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Paragraph 0038-0040; 0045; 0046
(2017/01/12)
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- A catalytic conversion method for preparing pyruvate ester of lactic acid (by machine translation)
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A method for preparing pyruvate through catalytic conversion of lactic acid is provided; according to the method, with oxygen or air as an oxidant, alcohol as a solvent, and molybdovanadophosphoric heteropoly acid and/or tungstovanadophosphoric heteropoly acid as a catalyst, and by coupling of a catalytic oxidation reaction and an esterification reaction, lactic acid is converted into pyruvate by one step. The method directly adopts oxygen or air as the oxidant and is green and safe; the used raw material lactic acid is obtained directly from conversion of biomass resources, moreover, the reaction conditions are mild, and the method has important application prospects.
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Paragraph 0020
(2016/10/10)
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- Biocatalytic Characterization of Human FMO5: Unearthing Baeyer-Villiger Reactions in Humans
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Flavin-containing mono-oxygenases are known as potent drug-metabolizing enzymes, providing complementary functions to the well-investigated cytochrome P450 mono-oxygenases. While human FMO isoforms are typically involved in the oxidation of soft nucleophiles, the biocatalytic activity of human FMO5 (along its physiological role) has long remained unexplored. In this study, we demonstrate the atypical in vitro activity of human FMO5 as a Baeyer-Villiger mono-oxygenase on a broad range of substrates, revealing the first example to date of a human protein catalyzing such reactions. The isolated and purified protein was active on diverse carbonyl compounds, whereas soft nucleophiles were mostly non- or poorly reactive. The absence of the typical characteristic sequence motifs sets human FMO5 apart from all characterized Baeyer-Villiger mono-oxygenases so far. These findings open new perspectives in human oxidative metabolism.
- Fiorentini, Filippo,Geier, Martina,Binda, Claudia,Winkler, Margit,Faber, Kurt,Hall, Mélanie,Mattevi, Andrea
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p. 1039 - 1048
(2016/05/19)
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- CAL-B-Catalyzed Enantioselective Deacetylation of Some Benzylic Acetate Derivatives Via Alcoholysis in Non-aqueous Media
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Enantioselective deacetylation of a set of benzylic acetates via alcoholysis catalyzed by Lipase B from Candida antarctica (CAL-B), under mild conditions is described. A systematic study allows to determine the appropriate combination nucleophile/organic solvent and also to explain the influence of these parameters on the enzymatic catalytic reaction. In all cases, (R)-alcohols are obtained with high ee (up to >99 %) at conversion 36 % 500. The enzymatic reactivity is influenced by the hydrophobicity of solvent and the structure/nature of the nucleophile. Furthermore, CAL-B allows enantio-complementary between transesterifications in non-aqueous media: alcoholysis and acetylation.
- Zadi, Amna,Merabet-Khelassi, Mounia,Aribi-Zouioueche, Louisa
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p. 1054 - 1061
(2015/02/05)
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- Stereoselectivity of additions to N-methyl acetonitrilium fluorosulfonate
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Alkoxy-N-methyl-acetiminium salts were prepared by addition of CH 3OH and C2H5OH to N-methyl acetonitrilium fluorosulfonate at low temperature. Analysis of the 5JHH and 3J13C-H coupling constants in the NMR spectra showed an anti addition with a diastereoselectivity of >95%. Deprotonation of these salts with (Z)-configuration gave the corresponding N-methyl-alkoxyacetimines with very high (E)-configuration. Upon protonation at -78 °C, these iminoesters gave the corresponding alkoxy-N-methyl-acetiminium salts with (E)-configuration. Computational analyses of the iminoesters and the corresponding iminium cations including the conformations give insight into the relative stability. Nitrilium salts can be used as reagents, exemplified by some esterifications between simple acids and alcohols.
- Keese, Reinhart,Berdat, Fran?ois,MacChi, Piero
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p. 1965 - 1970
(2013/03/28)
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- Solvent free, highly chemoselective N and O-acylation on silica and silica magnesium oxide: A recyclable solid surface
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Silica or silica/magnesium oxide mixed surface mediates the N and O-acylation, benzoylation or sulfonylation of hosts of substrates under solvent free conditions at ambient temperature with high chemoselectivity.
- Ghosh, Pranab,Mandal, Amitava
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p. 261 - 268
(2012/10/29)
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- Sonochemical synthesis of silica and silica sulfuric acid nanoparticles from rice husk ash: A new and recyclable catalyst for the acetylation of alcohols and phenols under heterogeneous conditions
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Silica nanoparticles were synthesized from rice husk ash at room temperature by sonochemical method. The feeding rate of percipiteting agent and time of sonication were investigated. The nanostructure of the synthesized powder was realized by the FE-SEM photomicrograph, FT-IR spectroscopy, XRD and XRF analyses. These analytical observations have revealed that the nano-sized amorphous silica particles are formed and they are spheroidal in shape. The average particle size of the silica powders is found to be around 50 nm. The as-synthesized silica nanoparticles were subsequently modified with chlorosulfonic acid and prepared silica sulfuric acid nanoparticles, which were employed as an efficient catalyst for the acylation of alcohols and phenols with acetic anhydride in excellent yields under solvent-free conditions at room temperature. This reported method is simple, mild, and environmentally viable and catalyst can be simply recovered and reused over 9 times without any significant loss of its catalytic activity.
- Salavati-Niasari, Masoud,Javidi, Jaber
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p. 705 - 712
(2013/02/22)
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- Process for preparing esters and organic halides
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A process for preparing esters and organic halides, which comprises reacting - a salt having a melting point of less than 100°C (at 1 bar) and of the formula ???????? (K+)n X (COO-)n, in which K+ is an organic cation, X (COO-)n is an organic anion having an n-valent organic group X which is substituted by n carboxylate groups COO-, and n is 1, 2 or 3, - with an organic halogen compound (Hal)mY, in which Hal is a halogen atom, Y is an m-valent organic group, and m is 1, 2 or 3, to give an ester and a halide K+ Hal-.
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Page/Page column 5-7
(2013/02/27)
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- Silica chloride and boron sulfonic acid as solid acid catalysts in preparation of ethers and esters under solvent-free condition
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Boron sulfonic acid was easily prepared from the reaction of boric acid and chlorosulfonic acid under solvent free condition. The prepared solid acid was supported on silica gel by simple grinding and used as efficient solid acid catalyst in the preparation of ethers from the aliphatic and aromatic alcohols. The ethers were prepared in high isolated yields and in lesser times. Silica chloride was prepared by refluxing of silica gel in thionyl chloride. The obtained solid acid was efficiently used for the conditions of alcohols to the corresponding ethers and acetyl esters in less reaction time and in high isolated yields.
- Elham, Sedighinia,Mozhgan, Zahed Sargoli
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experimental part
p. 1456 - 1458
(2012/01/06)
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- Iron (III) phosphate as a green and reusable catalyst promoted chemo selective acetylation of alcohols and phenols with acetic anhydride under solvent free conditions at room temperature
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Iron (III) phosphate was employed as an efficient catalyst for the chemo selective acetylation of alcohols and phenols under solvent free condition at room temperature and with high yields. Iron (III) phosphate is also a potential green catalyst due to solid intrinsically, reusable and with high catalytic activity.
- Behbahani,Farahani,Oskooie
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experimental part
p. 633 - 637
(2011/10/08)
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- Comparative study of acetylation of alcohols and phenols with different acetylating agents using zinc chloride as catalyst under solvent free conditions at room temperature
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Efficient acetylation of 1°, 2° and 3°, benzylic alcohols and phenols under solvent free conditions at room temperature in presence of less toxic, easily available and in-expensive catalyst ZnCl2, using acetic anhydride or acetyl chloride as an acetylating agent. On comparative study of these two acetylating agents, the acetyl chloride seemed to be better acetylating agent.
- Yadav, Prakrati,Lagarkha, Rekha,Balla, Zahoor Ahmad
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experimental part
p. 5155 - 5158
(2012/07/28)
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- Air-stable titanocene bis(perfluorooctanesulfonate) as a new catalyst for acylation of alcohols, phenols, thiols, and amines under solvent-free condition
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Air-stable titanocene bis(perfluorooctanesulfonate) [Cp2Ti(OSO2C8F17)2] that shows high Lewis acidity was prepared from Cp2TiCl2 and AgOSO2C8F17. The compound was characterized by different techniques, and examined as a catalyst for acylation reactions. It was found that using equimolar acetic anhydride as acetylating agent and under solvent-free condition, Cp2Ti(OSO2C8F17)2 exhibits high activity and selectivity in the acetylation of various alcohols, phenols, thiols, and amines. Also, good catalytic efficiency is observed in the acylation of 2-phenylethanol across various acylating reagents. The catalyst can be reused without loss of activity in a test of ten cycles. The Cp2Ti(OSO2C8F17)2 catalyst affords a simple, efficient and general method for the acylation of alcohols, phenols, thiols, and amines.
- Qiu, Renhua,Zhang, Guoping,Ren, Xiaofang,Xu, Xinhua,Yang, Ronghua,Luo, Shenglian,Yin, Shuangfeng
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experimental part
p. 1182 - 1188
(2010/06/13)
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- Microwave-assisted synthesis of nano-sized cadmium oxide as a new and highly efficient catalyst for solvent free acylation of amines and alcohols
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In present studies, a new and efficient method for synthesis of cadmium oxide nanoparticles by using microwave (MW) activation is reported. To ensure the specific efficiency of microwave irradiation versus conventional heating, the synthesis of Cd(OH)2 as precursor of CdO was carried out under similar temperature (80 °C), time and reaction conditions without microwave irradiation. The formation of CdO was characterized by XRD, TEM, FT-IR analysis. Catalytic activity of CdO nanopowder for acylation of alcohols, phenols and amines has been investigated. The results show that the reaction times and yields of desired products were improved by using CdO.
- Mazaheritehrani,Asghari,Orimi, R. Lotfi,Pahlavan
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experimental part
p. 2554 - 2564
(2010/10/21)
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- Zirconia supported undecatungstophosphate: Synthesis and characterization of a bifunctional catalyst
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The synthesized supported undecatungstophosphate has been proven to be successful for acid catalyzed as well as oxidation reactions, especially, in obtaining 98.5% conversion of styrene and 100% selectivity for benzaldehyde.
- Shringarpure, Pragati,Patel, Anjali
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scheme or table
p. 3953 - 3955
(2009/02/03)
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- SbCl3 as a highly efficient catalyst for the acetylation of alcohols, phenols, and amines under solvent-free conditions
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Antimony trichloride has been found to be an efficient and expedient catalyst for the acylation of alcohols, phenols, amines, and sugars with acetic anhydride in high yields and in a short reaction time under solvent-free conditions at room temperature. Also, racemization of chiral alcohols and epimerization of sugars were not observed in any of the substrates. Copyright Taylor & Francis Group, LLC.
- Bhattacharya, Asish K.,Diallo, Mamadou A.,Ganesh, Krishna N.
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p. 1518 - 1526
(2008/09/20)
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- A highly selective, high-speed, and hydrolysis-free O-acylation in subcritical water in the absence of a catalyst
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(Chemical Equation Presented) Fast and furious: A wide range of alcohols are acylated by acetic anhydride, in the absence of catalyst, in subcritical water in a flow-type microreaction system. The esters are selectively produced in high yields at temperatures of 200 to 250°C. Varying the amount of acetic anhydride added with respect to the alcohols allows the regioselective acylation of one or both hydroxy groups of various dihydroxy compounds (see picture).
- Sato, Masahiro,Matsushima, Keiichiro,Kawanami, Hajime,Ikuhsima, Yutaka
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p. 6284 - 6288
(2008/04/05)
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- Practical preparation of esters and thioacetates from alkyl halides and carboxylates or thioacetate catalyzed by PEG400 without solvent
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Carboxylic esters and thioacetates were conveniently prepared in good to excellent yields under mild conditions by the reaction of alkyl halides with sodium carboxylates or sodium thioacetate catalyzed by PEG400 in the absence of solvents. Copyright Taylor & Francis Group, LLC.
- Cao, Yu-Qing,Wu, Guo-Qiang,Li, Ya-Bin,Dai, Zhi,Chen, Bao-Hua
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p. 3353 - 3358
(2007/10/03)
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- Cobalt(II)-catalyzed direct acetylation of alcohols with acetic acid
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Cobalt(II) chloride hexahydrate (CoCl2·6H2O) efficiently catalyzes the acetylation of alcohols with AcOH in high yields. This protocol is also effective with other carboxylic acids, trifluoroacetic acid, propanoic acid, phenylacetic acid and benzoic acid, affording the corresponding acylated products in moderate to good yields. Removal of water is not necessary in these reactions. The catalyst can be filtered and recycled without loss of activity.
- Velusamy, Subbarayan,Borpuzari, Sarbani,Punniyamurthy
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p. 2011 - 2015
(2007/10/03)
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- Lanthanide(III) tosylates as new acylation catalysts
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Lanthanide(III) complexes of p-toluenesulfonic acid (Ln(TOS)3) were prepared, characterized, and examined as catalysts for the acetylation of various alcohols in acetic acid solution. Examination of a series of Ln(TOS)3 catalysts in the acetylation of 2-phenylethanol revealed a clear correlation between the ionic radius of the lanthanide(III) ion and the yield of the reaction, with the heavier lanthanides being more effective. In the presence of 5 mol-% of Yb(TOS)3, a quantitative conversion of phenethyl alcohol to phenethyl acetate was achieved within 18 hours at 50°C. Faster reaction was obtained under reflux conditions, in which case acetylation was complete within 30 minutes and in the presence of only 2 mol-% of the Yb(TOS)3 catalyst. The Yb(TOS)3 catalyst was effective for acetylation of a range of primary, secondary, and tertiary alcohols. The Yb(TOS)3 catalyst was also effective for acylation of phenethyl alcohol with propionic acid and cyclohexanecarboxylic acid. The catalysts could be easily recovered and reused for further acetylation, with no apparent change in selectivity or efficiency. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.
- Parac-Vogt, Tatjana N.,Deleersnyder, Karen,Binnemans, Koen
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p. 1810 - 1815
(2007/10/03)
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- Zinc oxide (ZnO) as a new, highly efficient, and reusable catalyst for acylation of alcohols, phenols and amines under solvent free conditions
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Zinc oxide (ZnO) is a highly efficient catalyst for the acylation of a variety of alcohols, phenols and amines with acid chlorides or acid anhydrides under solvent free conditions. Primary, secondary, tertiary, allylic and benzylic alcohols, diols and phenols with electron donating or withdrawing substituents can be easily acylated in good to excellent yield.
- Hosseini Sarvari, Mona,Sharghi, Hashem
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p. 10903 - 10907
(2007/10/03)
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- Effects of polymer architecture and nanoenvironment in acylation reactions employing dendritic (Dialkylamino)pyridine catalysts
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The role of architecture and nanoenvironment in the catalytic properties of dendritic polymers containing 4-(dialkylamino)pyridines was investigated in the context of acylation reactions employing sterically demanding tertiary alcohols as substrates. Frechet-type benzyl ether and aliphatic ester dendrimers were prepared in a convergent manner from a common trivalent core containing three DMAP groups while a linear polymer was dendronized with aliphatic esters using a divergent growth scheme. Catalysis experiments clearly indicate that nanoenvironment plays the dominant role in determining the activity of the polymer catalysts, with the polyester platform being superior to the benzyl ether. Polymer architecture played little or no role in affecting catalysis. With respect to molecular transport and catalysis, this represents the first comparative study of the effect of architecture and nanoenvironment using structurally similar dendritic materials.
- Helms, Brett,Liang, Catherine O.,Hawker, Craig J.,Frechet, Jean M. J.
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p. 5411 - 5415
(2008/02/01)
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- Asymmetric transesterification of secondary alcohols catalyzed by feruloyl esterase from Humicola insolens
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A new asymmetric transesterification of secondary alcohols catalyzed by feruloyl esterase from Humicola insolens has been found. Although alcohols are not the natural substrates for this enzyme, a high R enantioselectivity was observed. Stereochemical studies showed that variations in substrate structure lead to strong variations in enantioselectivity. The highest enantioselectivities are obtained when the β-carbon of the secondary alcohol is tertiary or quaternary.
- Hatzakis, Nikos S.,Smonou, Ioulia
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p. 325 - 337
(2007/10/03)
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- Catalytic ketonisation over oxide catalysts. Part XI*. Cross-ketonisation of esters of aliphatic and aromatic acids
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The cross-ketonisation of a mixture of ethyl acetate and ethyl benzoate under flow conditions has been studied over 20wt%MO2/Al 2O3 (M = Mn, Ce or Zr) catalysts, at 673-723 K. High conversions of aromatic ester up to 98% and moderate yields of acetophenone (2/Al2O3 catalyst was the least selective. In its presence, the yield of styrene (34%) exceeded that of acetophenone (31%). Unexpectedly, pure Al2O3 support exhibited the highest selectivity and moderate activity, at 723 K the yield as high as 51% of acetophenone was noted. The transformations of mixtures of various ethyl alkanoates with ethyl benzoate over alumina have been studied. In the case of straight-chain aliphatic esters, the yields of the corresponding 1-phenyl-1-alkanones were in the range of 41-51%. The presence of a methyl group in the α position of the ester (isobutyrate) reduced the yield of ketone strongly (11%); two methyl groups (pivalate) completely inhibited the reaction. The reactivity of a series of alkyl acetates was also studied in the cross-ketonisation reaction with ethyl benzoate over alumina. It has been found that secondary and tertiary alkyl acetates were slightly more selective than their primary counterparts due to the absence of products of transesterification. For these esters at 723 K the yields of acetophenone were in the range of 64-67%. The cross-ketonisation of a mixture of ethyl acetate with substituted ethyl benzoates led to the corresponding derivatives of acetophenone. It has been found that the position of the substituent in the benzene ring plays a crucial role in the reactivity of the ester and determines the extent of yield of the product. The highest yield of ketone (62%) was observed at 723 K for 3-methylacetophenone. 2-Methylacetophenone was formed with low yields (10%) in the whole range of reaction temperatures, probably due to steric effect in the ortho position. At 698 K the maximum yield of 4-methylacetophenone (27%) was attained. The ketonisation of ethyl acetate with ethyl esters of 4-t-butyl- and 4-chlorobenzoic acids led to moderate yields (24-27%) of 4-t-butyl- and 4-chloroacetophenone, respectively.
- Glinski,Koscik,Jerzak,Synoradzki
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p. 995 - 1001
(2007/10/03)
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- Efficient transesterification/acylation reactions mediated by N-heterocyclic carbene catalysts
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Imidazol-2-ylidenes, a family of N-heterocyclic carbenes (NHC), are efficient catalysts in the transesterification involving numerous esters and alcohols. Low catalyst loadings of aryl- or alkyl-substituted NHC catalysts mediate the acylation of alcohols with enol acetates in short reaction times at room temperature. Commercially available and more difficult to cleave methyl esters react with primary alcohols in the presence of alkyl-substituted NHC to efficiently form the corresponding esters. While primary alcohols are selectively acylated over secondary alcohols with use of enol esters as acylating agents, methyl and ethyl esters can be employed as protective agents for secondary alcohols in the presence of the more active alkyl-substituted NHC catalysts. The NHC-catalyzed transesterification protocol was simplified by generating the imidazol-2-ylidene catalysts in situ.
- Grasa, Gabriela A.,Gueveli, Tatyana,Singh, Rohit,Nolan, Steven P.
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p. 2812 - 2819
(2007/10/03)
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- Structure-function correlation in lipase catalysed esterification reactions of short and medium carbon chain length alcohols and acids
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An attempt has been made to correlate the carbon chain lengths of acids and alcohols to the extent of esterification in the Rhizomucor miehei lipase catalyzed esterification reactions involving acids of carbon chain length C2-C5 and alcohols of carbon chain length C1-C8.
- Divakar, Soundar
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p. 1919 - 1922
(2007/10/03)
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- An efficient and simple procedure for preparation of esters and anhydrides from acid chlorides in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) under solvent-free conditions
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A manipulatively one-pot and rapid method for the synthesis of aliphatic and aromatic ester and anhydride from acid chloride and alcohol or potassium salt of carboxylic acid under solvent-free conditions is reported. The reaction has been carried out in excellent yield and short reaction time in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) under solvent-free conditions.
- Hajipour,Mazloumi
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