Electrochemical oxidation of uracil and 5-halouracils at pyrolytic graphite electrode

Abstract

Electrochemical oxidation of uracil and 5-halogenated uracils has been investigated in phosphate buffers of <i>p</i>H range 1.2-11.0 using linear and cyclic sweep voltammetry, coulometry, controlled potential electrolysis and spectral studies. A single well-defined 6e, 4H⁺ oxidation peak (I_a) has been observed for uracil whereas halogenated uracils get oxidized in 4e, 3H⁺ step. The presence of halogen group at 5-position of uracil decreases the electron density at the π-bond and the Ep values also shift to less positive potential. The values of the first order rate constant for the disappearance of UV absorbing intermediate have been calculated. The product of electrooxidation has been characterized as alloxan. ECE mechanism has been proposed to account for the formation of alloxan.