The effect of pressure on the rate of the benzidine rearrangement : II. O, o'-hydrazotoluene

Abstract

The rates of the acid-catalysed rearrangement and of the oxidation of o, o'-hydrazotoluene in aqueous ethanol (96vol. % EtOH) have been measured at pressures up to 3000kg/cm^2. The rates of the rearrangements of one-proton and two-proton mechanisms were increased by pressure. In the two-proton mechanism, as a small negative volume of activation and a positive entropy of activation are observed, it seems likely that the second proton transfer is a pre-equilibrium. The oxidation accompanied with the rearrangement in acidic solution includes two concurrent reactions : one is independent of [H^+] and the other is inversely proportional to [H^+], both being strongly accelerated by pressure. Because of the large negative volumes of activation, it is implied that each reaction goes through an ionic activated complex.