Phenol oxidation mechanisms. A search for phenoxylium intermediates
Results which point to the occurrence of an ionic intramolecular coupling process in the oxidation of certain diphenyl ether and diphenylmethane derivatives are described. This process is in contrast to the usual free-radical coupling route encountered under different conditions. An attempt to induce a related heterolytic intramolecular coupling during the oxidation of some bis-hydroxynaphthylmethane monoethers was unsuccessful.