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 L-Glutamine and electrode materials. The reaction is mostly favorable in 50 mM of L-Glutamine and 2 mM of Catechol at pH 7. The behavior of the reaction is diffusion controlled followed by ECE mechanism.