ES342761A1 - Process for the Production of Carboxylic Acid GLycidyl Esters - Google Patents

Abstract

Carboxylic acid glycidyl esters are prepared by a process wherein in the first stage a carboxylic acid is reacted with at least 2 moles of [alpha]-epichlorohydrin per equivalent of carboxyl groups at 60-165 C. and in the presence of a tertiary amine, quaternary ammonium base or quaternary ammonium salt as catalyst such that the carboxyl groups are converted to chlorohydrin ester groups, which groups are then, in part, trans-epoxidized to glycidyl ester groups with the excess chlorohydrin present, the reaction being arrested when the first process step is substantially complete, and in a second process step the chlorohydrin ester left unchanged and the glycerin chlorohydrin formed are dehydrochlorinated with a 5-40% stoichiometric excess of concentrated aqueous alkali hydroxide which is added in small portions while simultaneously the water formed or added in the reaction is distilled off as an azeotrope with epichlorohydrin and finally the catalyst is removed by washing the reaction mixture with water. The carboxylic acid is preferably an aliphatic, cycloaliphatic or aromatic dicarboxylic acid. Tetramethyl ammonium chloride is the preferred catalyst. The first stage of the reaction may be monitored by measuring the pH of the reaction mixture, the reaction being discontinued at the final point of quantitative addition of epichlorohydrin to the acid when a rapid rise in pH occurs. The alkali hydroxide may be KOH or NaOH and a further portion of catalyst is preferably added before or during the dehydrohalogenation step. In the examples, the diglycidyl esters of #4-tetrahydrophthalic, hexahydrophthalic, sebacic, 1,10-decane dicarboxylio and phthalic acids, and others are prepared. Further examples include the allylglycidyl esters of phthalic, #4-tetrahydrophthalic, leocahydrophthalic and succinic acids and the triglycidyl ester of trimellitic acid.