Kinetics and mechanism of reaction of m-nitrobenzhydrazide and other hydrazines with acetic acid.

A comprehensive kinetic study was conducted of the reactions of m-nitrobenzhydrazide and some other hydrazines with acetic acid. The overall reaction rate for all of the compounds studied followed pseudo-first-order kinetics. The temperature dependence of the m-nitrobenzhydrazide degradation reaction was determined. The reaction rate dependence on the acetic acid concentration was found to be close to first order. High-pressure liquid chromatography was used extensively in identifying and measuring the appearance or disappearance rates of m-nitrobenzhydrazide degradation products in acetous solution. With m-nitrobenzhydrazide, the major degradation products were N,N'-bis(m-nitrobenzoyl)hydrazine, N-acetyl-N'-m-nitrobenzoylhydrazine, diacetylhydrazine, and hydrazine. The concentration profiles of these products in solution suggested a complex mechanism by which hydrazides react with acetic acid. All eight rate constants at 61 degrees in the suggested mechanism were calculated by an approximation method based on experimental data. The findings in the present study indicate that acetic acid is to be avoided as a solvent for hydrazine derivatives.