Mechanism of benzidine and semidine rearrangements. Part XXIII. Kinetics and products of acid-catalysed conversion of 4-phenyl-; 4-nitro-; 2,2′-diphenyl-; and 4,4′-difluoro-substituted hydrazobenzenes

Abstract

4-Phenyl-, 4-nitro-, and 2,2′-diphenyl-substituted hydrazobenzenes underwent rearrangements and concurrent disproportionations that were first order in substrate and second order in acid. The 4,4′-difluoro-compound also reacted first order in substrate but the order in acid rose from one to two with increasing acidity. These kinetic forms, the relative rates, and the nature of products could be rationalised by a polar transition-state mechanism that had been previously proposed.