Study on the oxidation of vanillymandelic acid to vanillin over mesoporous copper oxide

Mesoporous CuO synthesized by the hydrothermal method was used as a catalyst for the oxidation of vanillymandelic acid to vanillin with molecular oxygen as the terminal oxidant for the first time. The effects of reaction conditions on the catalytic performances have been investigated in detail, almost 100 % conversion of vanillymandelic acid and 88.3 % yield of goal product were achieved under the best conditions of reaction time 6 h, oxygen pressure 0.45 MPa, 85 °C and pH 12.5. In addition, the mesoporous CuO revealed outstanding recyclability and exhibited several pivotal advantages, including mild reaction conditions, environmentally friendly oxidant, as well as greatly reduced the amount of catalyst. A plausible mechanism for the liquid-phase oxidation of vanillymandelic acid on CuO was proposed.