Electrochemical oxidation of 4-aryl-1,4-dihydropyrimidines on a carbon electrode

Abstract Rotating risk—disk electrode ( rrde ) voltammetry has been used for studying the electrochemical oxidation processes of 4-aryl-1,4-dihydropyrimidines (1,4-DHPM) in acetonitrile. The two electron process of 1,4-DHPM electrochemical oxidation has shown to correspond to the multistage oxidation of both non-protonated and protonated forms. Surface protonation is due to rapid addition of protons formed during electrooxidation process of initial 1,4-DHPM molecules. It leads to the formation of extra molecules in the protonated form, which also oxidize to the end product. This also accounts for the absence of the free protons reduction wave on the ring electrode at potentials of the first oxidation wave. The electrochemical oxidation mechanism of 1,4-DHPM has been verified by mass-spectrometric and NMR analysis of products obtained during macroscale ECP.