The Electrochemical Reduction of Purine in Nonaqueous Solvents

Abstract

Abstract The electrochemical reduction of purine, which is the model compound for the reduction of the biologically-important purine bases, has been investigated in nonaqueous solvents (acetonitrile and DMF) by polarography, cyclic voltammetry, controlled potential electrolysis, and the ESR technique. In neutral solutions, purine is initially reduced in a one-electron, diffusion-controlled process at a fairly negative potential to produce an unstable radical anion, which then abstracts a proton from the parent purine to produce a free radical and an electro-inactive purine anion. The free radical is quickly deactivated by fast dimerization to form a purine dimer and by a further one-electron reduction to produce, ultimately, 1,6-dihydropurine. The addition of various acids to purine solutions results in the appearance of a new, drawn-out wave at a more positive potential than the original purine reduction wave, which is attributed to the two-electron reduction of N-protonated purine species to produce 1,6-dihydropurine.