ON THE ELECTROCHEMICAL OXIDATION OF 5-HYDROXY BARBITURIC-ACID

The electrochemical behavior of 5-hydroxy barbituric acid (HB) has bee n investigated in aqueous and nonaqueous media. In aqueous medium, the re is only one anodic peak at -50 mV (at upsilon = 20 mV/s), and no ca thodic peak is observed indicating an irreversible reaction under the conditions of this study. The cyclic voltammograms indicate a two-elec tron transfer reaction corresponding to the oxidation of HB to alloxan monohydrate (AM). In nonaqueous medium, voltammetric response is obse rved both in the anodic as well as the cathodic directions. The anodic peak occurs at +140 mV and the cathodic peak occurs at -320 mV at ups ilon = 20 mV/s. At high scan rates (upsilon > 200 mV/s) there are two cathodic peaks. The mechanism of oxidation of HB is discussed, and the rate constants of the reaction are calculated.