ELECTROCHEMICAL OXIDATION OF URIC-ACID AND XANTHINE AT PYROLYTIC-GRAPHITE ELECTRODE - MECHANISTIC INTERPRETATION OF ELECTROCHEMISTRY

Xanthine undergoes oxidation that proceeds by two stages. The first involves oxidation of the - C//8 equals N//9-bond to give uric acid which, being more easily oxidized than xanthine, is immediately further oxidized (2e-2H** plus ) to the uric acid bisimine. This then hydrates and fragments in essentially the same way as described for uric acid, the same products being observed. Mechanisms are developed which explain the observed electrochemistry and over-all formation of products from this reaction. The nature and yields of products formed electrochemically and the effect of pH on the reaction parallels the biological (enzymatic) oxidation of these compounds.