Partial Reduction of Dinitroarenes to Nitroanilines with Hydrazine Hydrate

Dinitroarenes containing substituents such as hydroxyl and amine groups could be conveniently reduced with 3 molar equivalents of hydrazine hydrate in presence of Raney nickel catalyst in ethanol/1,2-dichloroethane solvent mixture to give a product wherein one of the two nitro groups was reduced to the amino group. The yields of the partial reduction products are good. Under similar conditions alkoxyl substituents in the o,p-position to the nitro groups were displaced by the hydrazino group to give 2,4-dinitrophenylhydrazine as the main product. The details of the reduction reaction are described.