Kinetics and Mechanism of the Aminolysis of Anilino Thioethers with Benzylamines in Acetonitrile

摘要

The aminolyses of anilinothioethers(C_6H_5N(CH_3)CH_2SC_6H_4Z)in acetonitrile with benzylamines(XC_6H_4CH_2NH_2)have been investigated.The rates are much lower in acetonitrile than in methanol(with aniline).The Bronsted beta_X values are similar but beta_z values are smaller compared to those for the reactions in MeOH with anilines.The large negative rho_xz(= -0.8,after correction for fall-off)value is interpreted to indicate a frontside attack S_N2 mechanism,in which the two oppositely changed reaction centers in the TS,-N~(delta+)...S~(delta-)-,are in close vicinity increasing the interaction between nucleophile and leaving group.The inverse secondary kinetic isotope effects < 1.0)are observed with deuterated benzylamines(XC_6H_4CH_2ND_2).