Electrochemical Oxidation of Catechol in the Presence of L-Lysine at Different pH

Abstract

The reaction of electrochemically produced o-benzoquinone from oxidation of catechol as Michael acceptor with L-lysine as nucleophiles has been studied in aqueous solution with various pH values, different electrodes and different concentration of L-lysine using cyclic voltammetry, controlled potential coulometry and differential pulse voltammetry. The participation of reaction of o-benzoquinone with L-lysine at higher concentration of nucleophiles in the second scan of potential was observed. The products generated from the reaction are assumed to be 2-amino-6-((3,4-dihydroxyphenyl)amino)hexanoic acid that undergo electron transfer at more negative potentials than the catechol. The effect of pH of catechol in presence of L-lysine was studied by varying pH from 5 to 11. The reaction was strongly influenced by the pH as well as concentration of L-lysine. The reaction was mostly favorable in 2 mM of catechol and 70 mM of L-lysine at pH 7. The behavior of the reaction mechanism was of electron transfer, chemical reaction and electron transfer (ECE) type.