Reactions of carbonyl compounds in basic solutions. Part VII. The mechanism of the alkaline hydrolysis of methyl pseudo-8-acyl-1-naphthoates and pseudo-5-formylphenanthrene-4-carboxylate

Abstract

Rate coefficients have been measured for the alkaline hydrolysis of a series of methyl pseudo-8-acyl-1-naphthoates and methyl pseudo-5-formylphenanthene-4-carboxylates in 70%(v/v) dioxan–water at several temperatures. The entropies and enthalpies of activation have been evaluated. The results are related to the effects of the substituents and ring size for the pseudo-esters. Solvent isotope effects have been studied for selected pseudo-ester hydrolyses. All the evidence indicates a hydrolysis mechanism with a rate-determining addition of hydroxide anion to the pseudo-ester carbonyl group, followed by rapid collapse of the tetrahedral intermediate to form the carboxylate anion of the corresponding acid as product.