Electrochemical oxidation of 6-thioxanthine at pyrolytic graphite electrode

6-Thioxanthine has been studied in phosphate buffers of pH 1.2 - 11.0 using linear and cyclic sweep voltammetry, coulometry, controlled potential electrolysis and spectral studies. Two well-defined oxidation peaks, I-a, (1(e), 1H(+), pH range 1.2-6.0) and IIa (8e, 8H(+), pH range 1.2-11.0) are observed. A reduction peak, IIIc, is noticed in the reverse sweep. Kinetic studies indicate that the decay of the UV-absorbing intermediate is a first order reaction. The studies show that in acidic medium, thio group of 6-thioxanthine exists as S-H, whereas in neutral and basic medium thio group is in the form of C=S. The products of electrooxidation have been characterized and a tentative EC mechanism has been suggested for the oxidation of 6-thioxanthine.