The indirect anodic oxidation of 2-methylnaphthalene Part II. Oxidation in presence of dichromate

Tetrabutylammonium dichromate and ammonium dichromate enhance the electrooxidation of naphthalene and 2-methylnaphthalene (I) to 1,4-naphthoquinone and 2-methyl-1,4-naphthoquinone (II) and the oxidation is further improved by co-catalysis of RuCl₃·3H₂O. The present results imply that the role of Cr₂O^-2₇ anion in solution is mainly as a bulk oxidation agent which under the applied cell potential forms a concentration excess at the anode. It can therefore be used in low concentrations compared to those usually required for oxidation and low potentials are sufficient to give maximum effect. Selectivity for II is improved to & > 60% and is obtained in an undivided cell.