Elimination and addition reactions. Part 33. Formation and behaviour of carbanions derived from sulphones and nitriles bearing β-′onium substituents

Abstract

Kinetics of elimination reactions of β-arylsulphonylethyl- and β-cyanoethyl-ammonium and -sulphonium salts have been measured in ethanolic triethylamine buffers. The reactions show buffer saturation kinetics; at low buffer base concentrations ionisation to form the intermediate carbanion is rate-determining, but at higher buffer base concentrations the intermediate carbanion is formed in a rapidly established pre-equilibrium step and the observed rate constant does not change with increasing base concentration at constant buffer ratio.