CONCERTED BIMOLECULAR SUBSTITUTION-REACTIONS OF ANILINO THIOETHERS

The anilino thioethers, 3-NO2-C6H4N(CH3)CH2SC6H4-2-COO- (1) and 4-NO2- C6H4N(CH3)CH2SC6H4-2-COO-(2) undergo concerted bimolecular nucleophili c substitution (A(N)D(N)) With nucleophilic reagents in aqueous soluti on at 25 degrees C that is enforced by the absence of a significant li fetime for the corresponding iminium ion .(SAr)-S-- intermediates. Ele ctron donation from the aniline nitrogen atom provides assistance to t he nucleophilic reaction and results in a dissociative character for t he transition state of the reaction. A. Swain-Scott correlation with s approximate to 0.4 indicates an early transition state for bond forma tion, with a low sensitivity of the nucleophilic reaction toward the a ttacking nucleophile.