On the structure of thioamides and their derivatives. Part XXXIII. Kinetics of the acid-catalysed E→Z-isomerisation of N-neopentylthioformamide in o-dichlorobenzene

Abstract

The isomerisation of the E-form of N-neopentylthioformamide has been studied in the presence of dilute acids in o-dichlorobenzene. The reaction is first order in thioamide and in acid, the rate increasing with increasing acid concentration. These results as well as the dependence of the rate on acid strength, the kinetic isotope effect, and the activation entropy are discussed as indicating an N-protonated species as being responsible for the catalysis of the isomerisation in dilute acid solutions.