NUCLEOPHILIC-SUBSTITUTION REACTION OF CUMYL ARENESULFONATES WITH ANILINES

The nucleophilic substitution reaction of cumyl arenesulfonate with an iline has been investigated. The reaction in acetonitrile proceeds by the S(N)2 mechanism with probable front.side nucleophilic attack. The large magnitude of rho(xz) (= -0.75) obtained results in an observable sign reversal of rho(z) at sigma(x) = 0.83, with a negative rho(z) va lue for sigma(x) > sigma(x). This rather unusual phenomenon can be rat ionalized by a strong interaction between the nucleophile and leaving group due to their close proximity in the transition state, which in t urn is a result of the frontside nucleophilic attack. The reactions in methanol indicate that the S(N)1 channel competes with the S(N)2 path way and ion-pair return is observed when the aniline nucleophile conce ntration is low.