The formation of glutaric and succinic acids in the oxidation of cyclohexanol by nitric acid
The yields of the dibasic acid products from the oxidation of 2,2-dimethylcyclohexanol, 4-methylcyclohexanol and a mixture of cyclohexanol and [1-14C]cyclohexanone by nitric acid at 73 °C have been measured. The influence of copper(II) and of vanadium(V) catalysts on the product distributions has also been investigated. The data show that in the oxidation of cyclohexanol to adipic acid the by-product glutaric acid arises predominantly by the loss of C-2 rather than C-1 and succinic acid from the loss of C-2 with C-3. The results are used to identify possible mechanisms leading to the lower dicarboxylic acids. These are investigated further by examining the oxidation products from probable intermediates and from related compounds. These studies lead to the conclusion that the intermediate 2-nitrosocyclohexanone undergoes competing reactions that lead to adipic acid or glutaric and succinic acid.