87897-69-6Relevant academic research and scientific papers
Further insights into the electrooxidation of N-methyluric acids and correlation of oxidation potentials with frontier MO energies
Goyal, Rajendra N.,Thankachan,Jain, Neena
, p. 1515 - 1524 (2000)
The electrochemical oxidation of various N-methylated uric acids has been studied at a pyrolytic graphite electrode at physiological pH 7.2. The observed behavior was compared with uric acid to evaluate the effect of a methyl group. The E(p) value was found to shift to less positive potentials when a methyl group is present at the N-1 position and to more positive potentials when substitution is at the N-3 position or at nitrogens of the imidazole ring. The values of ΔE(p) followed the additivity of the substituents effect only when two methyl groups are present in different rings. The methyl groups were also found to increase the electron density at N atoms of uric acids, and an excellent correlation between the oxidation potential and energy of the highest occupied molecular orbital was observed. On the basis of these studies it is concluded that the presence of a methyl group in the pyrimidine ring restricts the formation of allantoin. The peroxidase-catalysed oxidation of the N-methylated derivatives of uric acid was found to follow a pathway similar to that observed during electrochemical oxidation.
Comparison of electrochemical and enzymic oxidation of 7,9-dimethyluric acid
Goyal, Rajendra N.,Singhal, Naveen
, p. 276 - 282 (2007/10/03)
The oxidation of 7,9-dimethyluric acid has been studied in aqueous phosphate buffers in the pH range 2.3-10.0 at a variety of solid electrodes. The conjugate base is found as the electroactive species which on 2e, H+ oxidation gives an unstable diimine. The attack of water molecule on the diimine in a follow up chemical reaction gives a UV-absorbing intermediate which decomposes in a pseudo-first order reaction to give alloxan and 1,3-dimethylurea at pH 3.0 and 1,3-dimethylallantoin and 1,3-dimethyl-5-hydroxyhydantoin-5-carboxamide at pH 7.2. The electrochemical behaviour of dimethyluric acid at PGE, GCE and Ft electrodes is the same. A comparison of electrochemical behaviour with unsubstituted uric acid indicates that methyl groups at positions 7 and 9 shift the Ep towards less positive potential. However, the overall course of electrode reaction remains unchanged. The peroxidase catalysed oxidation of 7,9-dimethyluric acid also exhibites the same spectral and kinetic behaviour and hence it is concluded that electrochemical and enzymic oxidation proceed by an identical EC mechanism.
