Electro-oxidation of Catechol in the presence of L-Glutamine at Different pH and Concentrations

The electro-oxidation of Catechol in presence of L-Glutamine has been investigated in aqueous solution with various pH values, different electrodes and different concentration of L-Glutamine by using cyclic voltammetry, differential pulse voltammetry and controlled potential coulometry. Electrochemically generated o-benzoquinone (Michael acceptor) from oxidation of Catechol reacts with lower concentration of L-Glutamine as nucleophiles in the second scan of potential. The products obtained from the reaction are assumed to be 2-amino-5-((3,4-dihydroxoyphenyl)amino)-5-oxopentanoic acid that undergo electron transfer at more negative potentials than the Catechol. The effect of pH of Catechol in presence of L-Glutamine has been studied by varying pH from 5 to 11. The slope of the plots of anodic peak current, Ep against pH of Catechol-Glutamine adduct is 25.6 mV, indicates that the oxidation proceeded via the 2e−/2H processes. The concentration effect of L-Glutamine with the fixed concentration of Catechol (2 mM) was measured from 10 mM to 100 mM. The reaction was strongly influenced by the pH as well as concentration of LGlutamine and electrode materials. The reaction is mostly favorable in 50 mM of LGlutamine and 2 mM of Catechol at pH 7. The behavior of the reaction is diffusion controlled followed by ECE mechanism.