Solvent effects in the reaction of 2-Thiophenesulfonyl chloride with aniline

The second order rate constants and the activation parameters for the reaction of 2-thiophenesulfonyl chloride with aniline together with solution enthalpies of the reactants have been measured in methanol,ethanol, 2-propanol,acetonitrile and acetone. The reaction rates are slower in dipolar aprotic solvents than in protic ones due to a remarkable negative activation entropy. The rate constants are correlated with empirical solvent polarity parameters.The data seem in accord with a SAN reaction mechanism.