Oxidation chemistry of 3,7-dimethylxanthine - a central behavioural stimulant at solid electrodes

The electrochemical oxidation of 3,7-dimethylxanthine has been studied in t he pH range 2.1-10.7 at pyrolytic graphite, platinum and glassy carbon elec trodes. The electrooxidation of 3,7-dimethylxanthine at solid electrodes pr oceeds in a single 4e, 4H(+) pH dependent step to give a diimine species wh ich decomposes in chemical followup steps. The UV absorbing intermediate ge nerated during electrooxidation of 3,7-dimethylxanthine decayed approximate ly at the same rate as that of xanthine and followed the first order kineti cs. The products of electrooxidation of 3,7-dimethylxanthine were character ized and a reaction scheme is suggested to explain their formation. The eff ect of introducing methyl groups into the electrooxidation of xanthine is a lso presented.