Kinetics and Byproducts of the Liquid-Phase Oxidation of Phenol to p-Benzoquinone Catalyzed by CuCl2

Oxidation of phenol was effected by O//2 at 35 kg/cm**2 in dimethylformamide (DMF), dimethyl sulfoxide (Me//2SO), and other solvents, containing variable amounts of CuCl//2 (0. 20-0. 50 mol/L), at temperatures in the range from 50 to 1110 degree C. Besides p-benzoquinone, considerable amounts of o- and p-chlorophenol were identified in the products, their yield strongly depending on the solvent. On the basis of overall conversion of phenol and of selectivity for p-benzoquinone, solvents of dipolar aprotic character, particularly DMF, were found convenient; ethylene glycol gave the poorest results. Kinetic coefficients were evaluated, within the pseudo-first-order approximation, for reactions in DMF and in Me//2SO. The steel surface of the autoclave was found to interfere with the reaction. After PTFE-lining, both rate and selectivity changes are observed.