A novel procedure for acid-catalysed K2FeO4 oxidation of benzyl alcohol in organic phase

Recent investigations have shown that ferrate(VI) salts oxidize organic compounds in aqueous phases with fast reaction from seconds to minutes and poor selectivity. Few studies have used ferrate(VI) in organic phases. The main issues are the poor solubility of K₂FeO₄ in common organic solvents and the low reaction rate. Therefore the interests to date are focused on finding a more effective catalyst in the organic oxidation. Up to now no work has been reported on acids as catalysis for the oxidative abilities of K₂FeO₄ in organic phases. Here we present a novel procedure for oxidizing benzyl alcohol to benzaldehyde without an overoxidation to benzoic acid by K₂FeO₄ in an organic phase. Using benzyl alcohol as a model, the catalytic activity of various acid solutions was measured. We found that the reactivity of K₂FeO₄ to the oxidation of benzyl alcohol can be highly enhanced by addition of a small amount of acid solution at room temperature. The catalytic ability of acid solutions follows the order acetic acid < oxalic acid < phosphomolybdic acid < phosphotungstic acid. On the basis of a theoretical analysis, a reaction mechanism is proposed. This method provides a new green way for oxidizing organic substances by K₂FeO₄ in nonaqueous media_.