Environmental-Friendly Synthesis of Adipic Acid by Catalytic Oxidation

Adipic acid is a most important organic synthetic intermediate, and much attention has been paid for its green synthesis process because of disadvantages in current technology. In this paper, recent developments on catalytic oxidation systems of environmental-friendly synthesis of adipic acid are reviewed, in which hydrogen peroxide, oxygen or ozone is used as clean oxidant and cyclohexene, cyclohexone and/or cyclohexanol as substrate. The focus is especially on the catalytic system of tungstate-H2O2, and several other new synthetic methods of adipic acid are also summarized. At the same time, advantages and disadvantages of each catalytic system are discussed on the aspects of solvent, yield and post-processing. Based on the discussions for these systems, the supported catalyst-hydrogen peroxide system will be a perfect one for the industrialization in the future.