The effect of pressure on the rate of the benzidine rearrangement IV : 2,2'-dimethoxyhydrazobenzene

Abstract

The effect of pressure on the rate of acid-catalyzed rearrangement of 2, 2'-dimethoxyhydrazobenzene in 85 vol% aqueous-ethanolic solution was studied under the conditions of 5～25℃, 1～2, 000kg/cm^2. As a result, it was confirmed that the rearrangement and the disproportionation reactions concurred and both were of first order with respect to the concentration of hydrogen ion. It was found that the rearrangement reaction was strongly accelerated but the disproportionation retarded by pressure, so it was thought that each reaction of rearrangement and of disproportionation passed through the different transition state. Considering the activation parameters, i.e. E_1≠10.0 kcal/mole, ΔS_1≠=-24 e.u., ΔV_1≠=-12 cc/mole far rearrangement and E_2≠=14.4 kcal/mole, ΔS_2≠=-11 e.u., ΔV_2≠=5 cc/mole for disproportionation reaction, the reaction schemes were discussed.