69737-96-8Relevant academic research and scientific papers
Kinetics and Mechanism of the Aminolysis of S-Phenyl Thiobenzoates
Lee, Ikchoon,Shim, Chang Sub,Lee, Hai Whang
, p. 769 - 793 (2007/10/02)
Kinetic studies on the nucleophilic substitution reaction of S-phenyl thiobenzoates with anilines have been carried out at 55.0 deg C.Effects of substituents in the nucleophile(X), substrate(Y) and leaving groups(Z) are analyzed in terms of Hammett's and Broensted's coefficients, ρi and βi and cross-interaction constants ρij and βij where i and j denote X, Y or Z.The sign of ρXZ (or βXZ) is positive, and accordingly, the transition state(TS) variations with the substituents are consistent with those predicted by the potential energy surface diagram; the magnitude of ρx(βx) and ρxy decreases with a better leaving group, and that of ρz and βz decreases with a stronger nucleophile leading to an earlier TS, in agreement with a normal Hammond effect.The larger magnitudes of ρXY, ρYZ and βXZ suggest that the reaction proceeds by an associative SN2 mechanism.A greater kH/kD value (1.0) is observed with deuterated aniline nucleophiles for a stronger nucleophile and a better leaving group, supporting the earlier TS proposed on the basis of the cross-interaction constants.The inverse secondary kinetic isotope effects obtained preclude involvement of any four-center TS or base catalysis by aniline.
