2757-83-7Relevant academic research and scientific papers
Oxidation chemistry of 3,7-dimethylxanthine - A central behavioural stimulant at solid electrodes
Goyal, Rajendra N.,Rastogi, Arshi
, p. 495 - 509 (2007/10/03)
The electrochemical oxidation of 3,7-dimethylxanthine has been studied in the pH range 2.1-10.7 at pyrolytic graphite, platinum and glassy carbon electrodes. The electrooxidation of 3,7-dimethylxanthine at solid electrodes proceeds in a single 4e, 4H+ pH dependent step to give a diimine species which decomposes in chemical followup steps. The UV absorbing intermediate generated during electrooxidation of 3,7-dimethylxanthine decayed approximately at the same rate as that of xanthine and followed the first order kinetics. The products of electrooxidation of 3,7-dimethylxanthine were characterized and a reaction scheme is suggested to explain their formation. The effect of introducing methyl groups into the electrooxidation of xanthine is also presented.
Cyclic voltammetry chronoamperometry of 1-methylxanthine: Evidence for an unstable para-quinonoid diimine intermediate
Goyal, Rajendra N.,Kumar, Neeraj
, p. 43 - 50 (2007/10/03)
The electrooxidation of the adenosine antagonist 1-methylxanthine has been studied in the pH range 2.5-10.7 at the pyrolytic graphite electrode. The initial 4e, 4H+ oxidation step leads to the formation of an unstable diimine, for which the half-life was found to be 1.8 s by chronoamperometry. The diimine is readily attacked by water to give a carbinolamine which decomposes in a pseudo first-order reaction to give, as the major products, 1-methylalloxan at pH 3.0 and 5-hydroxy-5-(methylcarbamoyl)hydantoin at pH 7.0. The oxidation products were identified. The diimine can also be reversibly reduced to the 2,6,8-trioxopurine anion derivative which is also formed by the 2e, 2H+ reduction of the carbinolamine. A tentative mechanism for the formation of the products has also been suggested.
Electrochemical and peroxidase catalysed oxidation of 1,7-dimethyluric acid and effect of methyl groups on the oxidation mechanism
Goyal, Rajendra N.,Jain, Ajay K.,Jain, Neena
, p. 1153 - 1160 (2007/10/03)
The electrochemical oxidation of 1,7-dimethyluric acid has been studied over a wide pH range of 2.2-10.3 at solid electrodes.Based on the results obtained from linear and cyclic sweep voltammetry, coulometry, spectroscopic studies and various analytical studies, a reaction mechanism has been proposed.The enzymatic oxidation of 1,7-dimethyluric acid has also been found to follow an identical pathway.The products of oxidation have been separated and characterized by using mp, 1H NMR and mass spectra.N-Methylation of the pyrimidine ring of purine causes protonation of nitrogen and affects the oxidation mechanism by not permitting the ring contraction of the diol intermediate.
Electrochemical oxidation of 3-methylxanthine at pyrolytic graphite electrode
Goyal, R. N.,Srivastava, Amit Kumar
, p. 212 - 218 (2007/10/02)
The electrochemical oxidation of 3-methylxanthine has been studied at pyrolytic graphite electrode (PGE) in the pH range 2.5-11.5.The oxidation has been found to proceed in a single well-defined 4c, 4H+ peak.The electrochemical studies coupled with spectral and kinetic studies clearly indicate that the initial oxidation of 3-methylxanthine in 2c,2H+ reaction gives 3-methyluric acid which on subsequent oxidation followed by hydrolysis gives 1-methylalloxan and urea at pH 3.2 and methylated allantoin and 5-hydroxyhydantoin-5-carboxamide at pH > 7.0.The decay of the UV absorbing intermediate generated during electrooxidation of 3-methylxanthine and 3-methyluric acid has been monitored at different pH and found identical.A plausible mechanism of electrooxidation has also been suggested.
Comparison of Electrochemical and Enzymic Oxidation of 3-Methyluric Acid
Goyal, Rajendra N.,Verma, Madhu Shri
, p. 1241 - 1248 (2007/10/02)
The electrochemical oxidation of 3-methyluric acid has been studied in the pH range 3.2-11.3 at pyrolytic graphite and glassy carbon electrodes.The conjugate base is the species oxidized over the whole pH range studied.Intermediates generated have been characterized in terms of their UV spectra and kinetics of decay, and products have been separated and characterized.The intermediates, formed and spectral and kinetics studies, during the peroxidase-catalysed oxidation of 3-methyluric acid indicated identical behaviour to that observed in electrochemical oxidation.It has thus been concluded that the electrochemical and enzymic oxidation of 3-methyluric acid proceed by an identical EC mechanism.
