Nitrogen-Doped Carbon Materials for the Metal-Free Reduction of Nitro Compounds

In this study, nitrogen-doped carbon materials (labeled as NC-T) were easily prepared by thermal treatment of the melamine-chitosan composite. NC-T catalysts demonstrated good activity toward the reduction of nitro compounds by using hydrazine hydrate (N2H4·H2O) as the reductant. The activity of NC-T enhanced with the rise of the pyrolysis temperature because of the enhanced ratio of graphitic-type nitrogen, which might be the active sites for the reduction of nitro compounds. NC-950 showed high activity for the selective reduction of nitro compounds in hexane to produce amines at yields from 87.5 to 100% at 90 °C using 2 equiv of N2H4·H2O. The NC-950 catalyst demonstrated comparable or even higher catalytic activity in comparison with the reported metal catalysts. The hydrogenation of nitro compounds with N2H4·H2O proceeded via the direct way involving hydroxylamine as the reaction intermediate.