[Biomimetic oxidation of diphenyl sulfide with electrochemical P-450 model system in CH2Cl2 treated with alkaline...

Dichloromethane containing metalloporphyrins [meso-tetraphenylporphyrinatomanganese(III) chloride (1) or meso-tetraphenylporphyrinatoiron(III) chloride (2)] and Bu4NClO4 was treated with an aqueous solution of NaOH (5%), and subjected to controlled potential electrolysis at -1.0 V (vs. S.C.E. (saturated calomel electrode)) in a divided cell after addition of diphenyl sulfide (3). Diphenyl sulfoxide (4) and diphenyl sulfone (5) were found in an electrolyzed solution as the reaction products. Results obtained from cyclic voltammetry and visible spectrometry suggested that the treatment of dichloromethane containing metalloporphyrins with the aqueous solution of NaOH did not change the fifth ligand of metalloporphyrins from Cl to OH. On the electrode, dissolved dioxygen was reduced to hydrogen peroxide. Compounds 1 and 2 catalyze the oxidation of 3 by hydrogen peroxide without imidazole. Compound 2 showed higher selectivity than compound 1.