Oxidation of 1,2-cyclohexanediol as a step for adipic acid synthesis

Adipic acid is the most important of the commercially available aliphatic dicarboxylic acids. It is obtained industrially from cyclohexanone and/or cyclohexanol by oxidation with nitric acid(V). One of the by-products of the process is nitrous oxide, which is difficult to utilize. In this paper we propose an alternative method of adipic acid synthesis. In the first stage, cyclohexene is oxidized with hydrogen peroxide to epoxide, which hydrolyses to 1,2-cyclohexanediol that in the second stage is then oxidized with oxygen. From an environmental point of view, this two-stage method can offer a significant and attractive reduction of N₂O production compared to the industrial methods. We apply a simple catalytic system composed of transition metal compounds and HNO₃ or organic nitrites, to the second stage of adipic acid synthesis synthesis, namely 1,2-cyclohexenediol oxidation using oxygen.