Study of the electrochemical behaviour of alloxan and dialluric acid at a platinized platinum electrode

Abstract

The electrochemical behaviour of alloxan and dialluric acid at platinum electrodes was studied in the presence of a 1 M H 2SO 4 supporting electrolyte. On the potentiostatic polarization curve of dialluric acid taken at positive potentials with respect to RHE, both oxidation and reduction branches were observed. Oxidation of dialluric acid results in alloxan, and in the course of its reduction the transformation of C-OH and C=O groups into -CH 2- should occur. As a consequence of this situation the polarization curve obtained transformation of alloxan into dialluric acid, and the second reflects the further reduction of dialluric acid. The alloxan-dialluric acid conversion proved to be a reversible process, not differing from that observed in the case of other non-catalytic electrodes. In contrast to this the reduction of dialluric acid at the potentials considered may be explained only by the catalytic action of platinum. This view was supported by catalytic hydrogenation studies, comparing the results obtained in the presence of tungsten carbide and platinum catalysts.