REACTIONS OF SULPHONIC ESTERS: I. A KINETIC STUDY OF THE EFFECT OF SUBSTITUENTS FOR A SERIES OF SULPHONIC ESTERS

Abstract

Kinetic data for the solvolysis of parasubstituted methyl, ethyl, and isopropyl benzenesulphonates in ethanol, methanol, methanol–water, and dioxane–water mixtures have been determined. It has been shown that the effect of the ionizing properties of the solvent of α-methylation, and of the addition of a strong base show the same general characteristics which for the halides have been considered diagnostic of a change in mechanism from a bimolecular solvolysis to a reaction in which ionization is rate controlling. The changes in the relative effect of para-substituents which accompany the apparent change of mechanism are examined. The greater effect of the para-NO2 substituent over the meta-NO2 substituent for the isopropyl esters under ionizing conditions is attributed to the contribution of resonance stabilization in forming ion.