ELECTROCHEMICAL OXIDATION OF 3-METHYLXANTHINE AT PYROLYTIC-GRAPHITE ELECTRODE

The electrochemical oxidation of 3-methylxanthine has been studied at pyrolytic graphite electrode (PGE) in the pH range 2.5-11.5. The oxidation has been found to proceed in a single well-defined 4e, 4H+ peak. The electrochemical studies coupled with spectral and kinetic studies clearly indicate that the initial oxidation of 3-methylxanthine in 2e, 2H+ reaction gives 3-methyluric acid which on subsequent oxidation followed by hydrolysis gives 1-methylalloxan and urea at pH 3.2 and methylated allantoin and 5-hydroxyhydantoin-5-carboxamide at pH greater-than-or-equal-to 7.0. The decay of the UV absorbing intermediate generated during electrooxidation of 3-methylxanthine and 3-methyluric acid has been monitored at different pH and found identical. A plausible mechanism of electrooxidation has also been suggested.