potassium-borohydride and fenazox

The synthesis of the azoxybenzenes by the reduction of nitroarenes with reducing agent potassium borohydride in water was reported for the first time. PEG-400 was used as a phase transfer catalyst and could effectively catalyze the reduction. The electronic effects of substituent groups play an important role in determining the reduction efficiencies. Electron-withdrawing substituents promote the formation of the azoxybenzene products, while electron-releasing groups retard the reductions to various degrees depending on the extent of their electron-donating ability.

Topics: Azo Compounds; Borohydrides; Catalysis; Molecular Structure; Nitro Compounds; Oxidation-Reduction; Polyethylene Glycols; Structure-Activity Relationship; Water