Study of clear oxidation of cyclohexanone to adipic acid using hydrogen peroxide

The oxidation of cyclohexanone to adipic acid by 30% aqueous hydrogen peroxide catalyzed by coordination compound system formed in situ between sodium tungstate and didentate ligands containing N or 0 atom such as oxalic acid without phase transfer agent and organic solvent was investigated. It was found that the optimal condition of reaction is reactant molar ratio of sodium tungstate dihydrate/oxalic acid/cyclohexanone/30% aqueous hydrogen peroxide= 2.0/3.3/100/350, the reaction time of 12 h and temperature of 92 degrees C with 80.6% yield of adipic acid. According to the identification of the products by the GC-MS in the progress of reaction, the mechanism was proposed. In the reaction cyclohexanone is firstly oxidized to c-caprolactone through Beayer-Villiger reaction and then the intermediate soon oxidated to adipic acid.