The Electrochemical Oxidation of Aminopurines and Their Hydroxy Derivatives at the Glassy Carbon Electrode

Abstract

Abstract The electrochemical oxidation of aminopurines and their hydroxy derivatives, which gave a single voltammetric peak at the glassy carbon electrode, was investigated by means of linear-sweep voltammetry, cyclic voltammetry, coulometry, and macroscale control!ed-potential electrolysis. In general, the ease of oxidation of these compounds increased in proportion to the number of hydroxyl or amino groups on the molecule. The coulometric n-values for monosubstituted purines were 5.86–6.08, for disubstituted purines they were 3.90–4.20, and for trisubstituted purines they were 2.07–2.33. The electrochemical oxidation of the different aminopurines appeared to follow initially the same path as the enzymatic oxidation; i.e., the primary attack for the electrochemical oxidation occurred first at the C-8 position, and then the C-2 position. Thus, aminopurines were oxidized in two sequential two-electron processes to give first 8-hydroxy and then 2,8-dihydroxy(or 6,8-dihydroxy) intermediates. Then, this latter intermediate was further oxidized in a two-electron process to produce a diimine intermediate, which was unstable and which then broke down to the ultimate products, such as parabanic acid, oxaluric acid, urea, ammonia, allantoin, and guanidine.