Reactions of carbonyl compounds in basic solutions. Part III. The mechanism of the alkaline hydrolysis of methyl 2-aroyl- and 2-acylbenzoates and related esters

Abstract

Rate coefficients have been measured for the alkaline hydrolysis of a comprehensive series of methyl 2-acyl- and 2-aroyl-benzoates and closely related esters in 70%(v/v) dioxan–water at several temperatures. The entropies and enthalpies of activation have been evaluated. The effect of substitution in the 2-acyl system has been correlated with the steric substituent parameter, Es. The relative rates of hydrolysis, activation parameters, substituent effects, solvent isotope, and solvent effects have been used to delineate the importance and extent of neighbouring-group participation by the keto- or formyl-carbonyl groups in the alkaline hydrolysis of the esters under study.