The selective reduction of nitroarenes to N-arylhydroxylamines using Zn in a CO2/H2O system

Abstract

Nitroarenes are reduced to the corresponding N-arylhydroxylamines with high selectivity using Zn dust in a CO₂/H₂O system under mild conditions. The yield of N-phenylhydroxylamine from nitrobenzene is 88% when the reaction is carried out at 25 °C for 1.5 hours with a Zn to nitrobenzene molar ratio equal to 3 under 0.1 MPa CO₂. Other nitroarenes, which contain reducible functionality other than a nitro group, are also reduced to the corresponding N-arylhydroxylamines with yield from 88% to 99%. The process fully removes the need to use NH₄Cl and is environmentally benign.