Kinetic investigation on the reactions of p‐toluenesulfonyl chloride with p‐substituted benzoic acid(s) in the presence of triethylamine in aprotic solvents

Second‐order rate constants of the reactions of p‐toluenesulfonyl chloride with p‐substituted benzoic acids in the presence of triethylamine in acetonitrile/acetone under equimolar and pseudo‐first‐order conditions have been determined by the conductometric method using the Guggenheim principle at 25, 30, 35, and 40°C. The reactions follow second order with respect to the whole and first order with respect to each of the reactants. The order of reactivity of the substituents in benzoic acid is rationalized. Activation parameters are obtained by applying the usual methods. The Hammett plot has been found nonlinear, whereas the Bronsted plot shows good correlation. This may be explained on the basis of electronic effects of substituents on the reaction center. Kinetic data and the product analyses indicate that the reaction proceeds through direct nucleophilic attack on the sulfur center. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 303–308, 2009