17598-92-4Relevant articles and documents
Preparation of glycerol carbonate esters by using hybrid nafion-silica catalyst
Climent, Maria J.,Corma, Avelino,Iborra, Sara,Martinez-Silvestre, Sergio,Velty, Alexandra
, p. 1224 - 1234 (2013/07/26)
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
Glyceryl valproates
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, (2008/06/13)
Glycerides esterified with one or two moles of valproic acid and optionally esterified with fatty acids at the remaining hydroxy position(s) have been found to have the same useful therapeutic effect as valproic acid alone but without causing gastric irritation.