- The carbon material functionalized with NH2+ and SO3H groups catalyzed esterification with high activity and selectivity
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A novel carbon-based solid acid was conveniently prepared by heating a mixture of d-glucose, p-toluenesulfonic acid and diphenylammonium tosylate. Its structure was measured by XRD, FT-IR, XPS, 13C MAS NMR and EA to illustrate that the carbon material has been functionalized with NH2+ and SO3H groups and has a strong "hydrophobic effect". It can be used to catalyze the esterification reaction of carboxylic acids with equimolar amounts of sterically demanding and acid-sensitive alcohols with high reactivity (yield up to 90%) and selectivity (up to 95%) in heptane at 80 °C. It could be easily recovered and reused more than ten times without loss of activity.
- Zhan, Shaoqi,Tao, Xiaochun,Cai, Liangzhen,Liu, Xiaohui,Liu, Taoping
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supporting information
p. 4649 - 4653
(2015/02/19)
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- METHOD FOR THE PREPARATION OF TRIGLYCERIDES OF MEDIUM-CHAIN LENGTH FATTY ACIDS
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A method is disclosed for the preparation of glycerol esters (triglycerides) of medium-chain length monocarboxylic fatty acids which consists of the reaction of the precursor free fatty acid and glycerol in the presence of a catalyst under partial vacuum. The process preferably uses a metal catalyst such as an oxide or a chloride of tungsten, molybdenum, calcium, zinc, chromium or magnesium. The method of the invention allows the preparation in high yield and high purity (>99.5%) of the final triglyceride. The present method allows the formation of triglycerides without solvent. Are also contemplated, the triglyceride obtained by the method, and the pharmaceutical composition containing the triglyceride as an excipient or as an active ingredient.
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Paragraph 0043
(2013/09/12)
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- Preparation of glycerol carbonate esters by using hybrid nafion-silica catalyst
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Glycerol carbonate esters (GCEs), which are valuable biomass-derivative compounds, have been prepared through the direct esterification of glycerol carbonate and long organic acids with different chain lengths, in the absence of solvent, and with heterogeneous catalysts, including acidic-organic resins, zeolites, and hybrid organic-inorganic acids. The best results, in terms of activity and selectivity towards GCEs, were obtained using a Nafion-silica composite. A full reaction scheme has been established, and it has been demonstrated that an undesired competing reaction results in the generation of glycerol and esters derived from a secondary hydrolysis of the endocyclic ester group, which is attributed to water formed during the esterification reaction. The influence of temperature, substrate ratio, catalyst-to-substrate ratio, and the use of solvent has been studied and, under optimized reaction conditions and with the adequate catalyst, it was possible to achieve 95 % selectivity for the desired product at 98 % conversion. It was demonstrated that the reaction rate decreased as the number of carbon atoms in the linear alkyl chain of the carboxylic acid increased for both p-toluenesulfonic acid and Nafion-silica nanocomposite (Nafion SAC-13) catalysts. After fitting the experimental data to a mechanistically based kinetic model, the reaction kinetic parameters for Nafion SAC-13 catalysis were determined and compared for reactions involving different carboxylic acids. A kinetic study showed that the reduced reactivity of carboxylic acids with increasing chain lengths could be explained by inductive as well as steric effects. Chain reaction: The esterification of glycerol carbonate with carboxylic acids to produce glycerol carbonate esters, which are valuable biomass-derivative compounds, has been investigated. A Nafion-silica nanocomposite is shown to be an excellent catalyst, and after fitting the experimental data to a kinetic model, the kinetic parameters were determined and compared for reactions involving different carboxylic acids. Copyright
- Climent, Maria J.,Corma, Avelino,Iborra, Sara,Martinez-Silvestre, Sergio,Velty, Alexandra
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p. 1224 - 1234
(2013/07/26)
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- 1H-Nuclear magnetic resonance spectroscopic studies of saturated, acetylenic and ethylenic triacylglycerols
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The 1H-NMR spectroscopic properties of 15 synthetic homologous saturated triacylglycerols of type AAA and 16 mixed saturated triacylglycerols of type ABA and AAB have been studied. Triacylglycerols containing short-chain fatty acids (2:0-6:0) are readily identified. Triacylglycerols containing medium- and long-chain fatty acid components are not differentiated. From the analysis of 19 acetylenic triacylglycerols of type AAA, ABA and AAB (containing positional isomers of acetylenic fatty acids), it is only possible to characterize triacylglycerols with acyl groups containing the acetylenic bond at the Δ2-Δ5 position. 1H-NMR analysis could not confirm the positions (α- or β-acyl) of the acetylenic acids in mixed triacylglycerols. In the study of 22 ethylenic triacylglycerols of type AAA containing positional isomers of (Z)- or (E)-ethylenic acids, molecules containing an ethylenic bond in the Δ2 position of the acyl chains were readily characterized, as the ethylenic protons in the α- and β-acyl chains were fully resolved. Triacylglycerols containing an unsaturated center at the position were characterized by the shifts of the 2-H protons. The spectra of the remaining triacylglycerol molecules were very similar and the position of the ethylenic system could not be determined by this technique.
- Lie Ken Jie, Marcel S.F.,Lam
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p. 155 - 171
(2007/10/03)
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- Preparation of Carboxylate Esters of Polyhydric Alcohols by Using a Sulfonated Charcoal Catalyst
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Ethane-1,2-diol, propane-1,2-diol, butane-1,4-diol and propane-1,2,3-triol are readily esterified by carboxylic acids in near quantitative yields in the presence of a sulfonated charcoal catalyst.
- Prager, Rolf H.,Yurui, Zhang
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p. 1003 - 1005
(2007/10/02)
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