Azo bond hydrogenation with hydrazine, R-NHNH2, and hydrazobenzene

Hydrogenation of azo bonds with hydrazine, mono-substituted hydrazine, and hydrazobenzene was studied with selected diazene compounds under oxygen-free conditions. The reactions proceed rapidly and in high yield in several solvents, utilizing all N-H protons. While the reduction process is accompanied by the evolution of nitrogen gas in the case of N2H4, the intermediacy of diimide could not be confirmed by standard trapping experiments.