Kinetics and mechanism of hydrolysis of O-aryl N-phenylthiocarbamates

Abstract

In kinetic studies of the hydrolysis ofaseries of O-aryl N-phenylthiocarbamates, evidence for the formation of phenyl isothiocyanate is a decisive argument for an E1cB mechanism. The high value of the Hammett parameter (ρ 3.0) and the positive value of the entropy of activation (ΔS‡+ 10.8 cal mol–1 K–1) are discussed as mechanistic criteria which can be used to establish the occurrence of an EIcB mechanism when the intermediate cannot be isolated.