Equilibrium and kinetic acidities of carbon acids

Abstract

Bnomalous Brönsted coefficients observed for nitroalkanes are rationalized in terms of a mechanism involving an intermediate anion. The results of measurements of equilibrium acidities of carbon acids in dimethyl sulphoxide (DMSO) solution are presented and compared with similar measurements made in solvents of low dielectric constant and in water. A linear correlation between gas-phase acidities and DMSO solution acidities for a series of ketones and for a series of nitriles is presented. Equilibrium measurements indicate the presence of a high degree of strain in the anion derived from trifluoromethylsulphonylcyclopropane. This result shows that the sulphur atom in the trifluoromethylsulphonyl group is entering into strong conjugation with the carbanion.