VARIATION OF TRANSITION STATE IN REACTIONS OF BENZENSULFONYL CHLORIDES WITH ANILINES IN MeOH-MeCN SOLVENTS

Article abstract of DOI:10.1016/S0040-4020(01)88691-9

Kinetic studies of nucleophilic substitution reactions of substituted benzenesulfonyl chlorides with anilines were conducted at 35 deg C in a range of methanol-acetonitril solvent mixtures.Results showed that (i) the magnitudes of ρ_N and β associated with a change of substituent in the nucleophile are large and indicate a relatively advanced bond-formation in the transition state, (ii) maximum size of ρ_N, ρ_S and β at the solvent composition of the maximum ionizing power, together with a positive cross-interaction coefficient, suggest S_N2 transition state of a "synchronous push-pull" type, and (iii) the potential energy surface model is unstable to predict the transition state variation to a more product-like transition state, where bond formation is much more progressed and bond-breaking is slightly more advanced, upon changing the solvent to a more ionizing one enhancing leaving ability.In this respect the quantum mechanical model is superior to the potential energy surface model.