Solvent Effects on the Alkaline Hydrolyses of 4-Nitrophenyl N-Aroyl

Abstract

Second-order rate constants have been determined for the alkaline hydrolyses of N-aroyl-p-toluenesulfonimidic esters in aqueous organic solvents. Rate minima were observed with decreasing water concentration in aqueous acetonitrile, dioxane and t-butanol mixtures whereas rates of hydrolysis decrease continuously in MeOH-H<inf>2</inf>O and increase in DMSO-H<inf>2</inf>O. Solvent effects, Arrhenius parameters, and substituent effects are consistent with either an addition-elimination or a concerted S<inf>N</inf>2-type mechanism.