Reactions between aromatic nitro-compounds and hydroxylamines in alkaline solution. Part II. Product studies

Abstract

The initial reaction under nitrogen between ArNO₂ and an alkaline solution of a hydroxylamine corresponds to ArNO₂+ RNHOH → ArNO + RNO + H₂O but these compounds cannot be isolated. With hydroxylamine itself the reaction proceeds further to give an azide ArN₃. From N-alkylhydroxylamines, R₂CHNHOH, the intermediate aliphatic nitroso-compounds in part tautomerise to the oximes R₂C:NOH which can be isolated.

The aromatic nitroso-compound is in part reduced to the radical-anion (ArNO·)^– which dimerises to the azoxy-compound ArN:N(O)Ar and in part condenses with the hydroxylamine RCH₂NHOH to give an unsymmetrical azoxy-compound, RCH₂N:N(O)Ar, and eventually a formazan ArN:NCR:NNHAr.

Formazans have been isolated in good yield from the reactions of nitrobenzene and of nitrosobenzene with both N-methyl- and N-benzyl-hydroxylamines and from the reaction of N-benzylhydroxylamine with p-nitrotoluene.