Enthalpies of transfer from methanol to protic and aprotic solvents of the transition state in the reaction of benzenesulphonyl chloride with imidazole

Abstract

Rates, activation parameters, and heats of solution of the reactants have been measured for the reaction of benzene-sulphonyl chloride with imidazole in water, three alcohols, and six dipolar aprotic solvents. Enthalpies and entropies of activation are considerably lower in aprotic than in protic solvents. The corresponding changes in free energies are relatively small. Variations in activation parameters within each solvent group are small. Enthalpies of transfer from protic to aprotic solvents of reactants and transition state are endo- and exo-thermic respectively. These enthalpies of transfer are approximately constant and independent of the particular aprotic solvent.