Solvolysis of Substituted Benzyl Benzenesulfonates in MeOH-MeCN Mixtures

摘要

Methanolysis rates of benzylbenzenesulfonates, substituted both on the substrate (Y) and on the leaving group (Z), were determined in MeOH-MeCN mixtures. The results showed that the reaction proceeds via the dissociative SN2 mechanism, in which bond breaking proceeds in greater degree compared to bond formation at the transition state(TS). Multiple Hammett correlation analysis showed that the cross term, ￥?YZ, is very small and hence the cross interaction of two substituents, Y and Z, at the TS is not important, supporting the dissociative SN2 type mechanism. While transition state variations predicted by the quantum mechanical model is shown to agree in general with the experimental results, those predicted by the potential energy surface model failed to account for the leaving group effect properly.