One-step aerobic oxidation of cyclohexane to adipic acid using an Anderson-type catalyst [(C18H37)2N(CH3)2]6Mo7O24

Aerobic oxidation of cyclohexane to adipic acid (AA) was performed using a series of environmentally benign Anderson-type as catalysts. It is found that the Anderson-type catalyst with metal molybdenum as the central ion, [(C18H37)2N(CH3)2]6Mo7O24, showed the highest catalytic activity and selectivity among the prepared catalysts. The effect of several reaction parameters (the amount of catalyst, oxygen pressure, reaction temperature and time) on the oxidation process was investigated and optimized. The catalyzed system (catalyst concentration: 1 ppm, 160 °C, 6 h) demonstrated excellent reactivity that 87.1% selectivity for AA can be achieved at good conversion (10.2%) and the turnover number (TON) can reach 3.3 × 107. The oxidative mechanism was observed to be involved in a free radical process.

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► One step oxidation cyclohexane to AA was attempted without additives and solvent.
► [(C18H37)2N(CH3)2]6Mo7O24 was an effective catalyst for oxidation of cyclohexane.
► The high selectivity (87.1%) at good conversion (10.2%) can be achieved.
► The TOF can reach 3.3 × 107.