Catalytic oxidation of cyclohexanone to adipic acid using phosphotungstic acid as catalyst

By using 30% H2O2 as oxidant,NaHSO4·H2O or KHSO4 as acidic ligand,adipic acid was synthesized with cyclohexanone as raw material and phosphotungstic acid as the catalyst.The effects of catalyst dosage,hydrogen peroxide dosage,acidic ligands,reaction time and reusability of the catalyst on yield of adipic acid were all investigated.The results indicated that the catalyst had high catalytic activity.Optimal reaction conditions were as follows:n(cyclohexanone)∶n(phosphotungstic acid) =1∶0.002,30% H2O2 45 mL,NaHSO4·H2O 0.1 g,refluxing 6 h,the yield of adipic acid reached 66.7%.When KHSO4 as acidic ligand,the yield could reach 71.2%.