Reduction of Aromatic Nitro Compounds by Ethylenediamine. A New Selective Reagent for the Synthesis of Symmetric Azo Compounds

Article abstract of DOI:10.1021/jo00181a015

Ethylenediamine selectively reduces aromatic nitro compounds RC6H4NO2 (R = H, m-CH3, p-CH3, and m-Ph) at 150 deg C to symmetric azo compounds RC6H4N=NC6H4R in good yield but does not reduce their ortho-substituted analogues.The diamine does not react with o- or p-nitroanilines but reduces the meta isomer to 1,3-diaminobenzene and 3,3'-diaminoazobenzene.Its reaction with o- and p-halonitrobenzenes gives substitution products H2NCH2CH2NHC6H4NO2.Nitrosobenzene is reduced to aniline and azobenzene, while α-nitroso-β-naphthol is converted to 1,4-phenanthroline.Among a variety of other amines tested, only 1,3-propylenediamine reduces nitrobenzene to azobenzene.A mechanism for the reaction is proposed.