Biphasic and phase-transfer-catalyzed N-monoacylation and N,N'-diacylation of azobenzenes by cobalt carbonyl

Azobenzenes react with a stoichiometric amount of cobalt carbonyl and excess methyl iodide under phase-transfer conditions (benzene, water, and benzyltriethylammonium chloride as the phase-transfer agent) to give acetic acid 1,2-diaryl-2-acetylhydrazides in reasonable yields. Byproducts arising from nitrogen-nitrogen bond cleavage were formed in several of the reactions. Reductive monoacylation of azobenzenes occurs on reaction with Co2(CO)8, methyl iodide, and a catalytic amount of p-toluenesulfonic acid under biphasic conditions.