Kinetics of alkaline hydrolysis of quaternary phosphonium salts. The influence of aprotic solvents on the hydrolysis of ethyl(phenyl)phosphonium iodides

Abstract

Third-order rate constants have been determined for the hydrolyses of the ethyl(phenyl)phosphonium iodides (1) in aqueous methanol and in aqueous tetrahydrofuran. The very large increase in the rate of hydrolysis of tetra- and tri-arylphosphonium salts which is induced by the addition of tetrahydrofuran to the medium drops to almost zero for tetra- and tri-alkylphosphonium salts. This is attributed to an increase in the delocalisation of the positive charge in phosphorus, which leads to less specific solvation of the alkylphosphonium ions.