Elimination–addition. Part X. Rates of addition of amines to p-toly vinyl sulphone

Abstract

Reactivities of amines in additions to p-tolyl vinyl sulphone have been determined in competitive reactions (in benzene) and by individual rate measurements (in benzene and in alcohols).

Reactivities are much more sensitive to the steric requirements of the amine than to its basicity. In ethanol, primary amines are less reactive than secondary amines. This is shown to be due to the greater degree of solvation of the former.

Rates in benzene are much lower than in ethanol and while in both solvents the reaction order with respect to sulphone is unity, the order in amine is second and first, respectively.

A mechanism, which involves concerted formation of the new C–N and C–H bonds in the transition state, is suggested to account for these observations.