Competitive Reaction Pathways in the Nucleophilic Substitution Reaction of Aryl Benzenesuefonate with Benzylamines in Acetonitrile

초록

The reaction of aryl benzylsulfonates (YC6H4SO2OC6H4Z) with benzylamines (XC6H4CH2NH2) in acetonitrile at 65'C. have been studied. The reactions proceed competitively by the S-O (ks-o) and C-O (kc-o) bond scission, but the former provides the major reaction pathway. Based on analyses of the Hammett and Brnsted coefficients together with the cross interaction constants, ρxy, ρyz, and ρxz, stepwise mechanisms are proposed in which the S-O bond cleavage proceeds by rate-limiting formation of a trigonal-bipyramidal five-coordinate (TBP-5C) intermediate, whereas the C-O bond scission takes place by rate-limiting expulsion of the sulfonate anion (YC6H4SO3-) from a Meisenheimer type complex.