Reaction of benzofurazan N-oxide with secondary aliphatic amines; preparation of NN-dialkyl-N′-(o-nitrophenyl)hydrazines

The interaction of benzofurazan N-oxide with a variety of secondary aliphatic amines in the cold gives NN-dialkyl-N′-(o-nitrophenyl)hydrazines by attack on the hetero-ring. At higher temperatures, dialkylaminobenzofurazans are obtained by attack on the benzene ring. Substituents in the benzofuran N-oxide exerting –I and –M effects slow down both processes. The interaction of various NN-dialkylhydrazines with chloronitrobenzenes and polynitrobenzenes give either nitrophenyldialkyl-amines or -hydrazines in a predictable manner, for which a mechanistic rationale is proposed, involving charge-transfer complex formation when polynitrobenzenes are used.