Hydrolysis and saponification of methyl benzoates

Abstract

We report a study of the hydrolysis and saponification of methyl benzoates, 1, in both water and slightly alkaline solution (2% KOH) at high temperature (200–300 °C). In this green, solvent-free procedure, we achieve partial hydrolysis or quantitative saponification of sterically hindered and p-substituted methyl benzoates in 30 min. In addition, methyl 2,4,6-trimethylbenzoate, 1a, and methyl p-aminobenzoate, 1g, can be selectively decarboxylated or hydrolyzed by changing the temperature and/or pH of the reaction medium. The enhancement of the nucleophilicity of diluted alkaline solution at high temperature is proved by the quantitative hydrolysis of the sterically hindered ester, 1a, and the partial hydrolysis of the trifluoromethyl group to a carboxylic acid in methyl p-trifluoromethylbenzoate, 1e.