Theoretical Study On The Oxidation Of Cyclohexanol By Nitric Acid

Adipic acid (AA) is important aliphatic dicarboxylic acid. It is mainly used for the synthesis of nylon 66 (salt), polyurethanes and plasticizers. At present, the main process for the production of adipic acid is in the presence of V(?), Cu(?) catalysts, nitric acid oxides cyclohexanone or a mixture of cyclohexanol and cyclohexanone. In this case the yield of AA is 90-95%. Although the process has been applied for many years, its reaction mechanism and the role of V(?) and Cu(?) are still lack of complete theoretical research and explanation. The aim of this paper is to study the mechanism of the oxidation of nitric acid or KA oil and the role of catalysts V(?) and Cu(?) by using quantum chemistry calculation method.Firstly, we calculated the generation paths of adipic acid and its by-products of glutaric acid, succinic acid in the absence of catalysts. We obtained the main generation route of adipic acid and its by-products of glutaric acid, succinic acid. The main path of the production of adipic acid without catalyst as follows. The activation energy of rate-determing step in this route to AA is 43.8 kcal/mol,which is lower than that to GA 47.7 kcal/mol and SA 55.2 kcal/mol.Research results about the catalytic effect of V(?) show that, V(?) can catalysis the oxidation of intermediates which produced in the reaction process with hydroxyl, oximido and aldehyde. And then change the reaction route and improve the selectivity of the objective product adipic acid and inhibit the formation of by-products. Research results about the catalytic effect of Cu(?) show that, Cu(?) mainly affected the nitration reaction. The activation energy of the reaction is reduced, the reaction path is changed and the generation of the by-product is inhibited by the react of Cu(?) with the intermediates formed in the reaction process. The main rout of the production of adipic acid with V(?) and Cu(?) as follows:...