Abstract
The aminolysis reactions of thiophenyl phenylacetates with benzylamines are investigated in acetonitrile at 55.0℃. Relatively large selectivity parameters, βx≒ 1.5, βz = -1.5~-1.8 and βxz = 0.92 together with the valid reactivity-selectivity principle are consistent with stepwise acyl transfer mechanism with rate limiting expulsion of the leaving group, thiophenolate anion, from the tetrahedral intermediate, T ± . The first order kinetics with respect to the benzylamine concentration and the realtively large secondary kinetic isotope effect (kH / kD = 1.2-1.7) involving deuterated benzylamine nucleophiles suggest a four center type transition state in which concurrent leaving group departure and proton transfer are involved.