Radical Cation of Pyrazine-di-N-oxide as a Mediator in Electrocatalytic Oxidation of Organic Compounds

The mechanism of oxidation of cyclohexanol, methanol, diethyl ether, triethyl orthoformate, and cyclohexane in the presence of a mediator—electrochemically generated radical cation of pyrazine-di-N-oxide (PyrDNO)—is studied on glassy carbon and platinum in a 0.1 M LiClO₄ solution in acetonitrile employing cyclic voltammetry, ESR electrolysis, and gas chromatography. Effect of temperature, additives of acid and water, oxygen, and the nature of the substrate and solvent on the shape of cyclic voltammograms and intensity of ESR signal of PyrDNO is examined. ESR spectra for radical cations and anions of PyrDNO with g factors equal to, respectively, 2.0090 and 2.0031 are recorded. A mechanism for the overall two-electron catalytic oxidation of an organic substance, which involves a stage in which it complexes with the radical cation of PyrDNO, is suggested.