Electrochemical Oxidation of 3,4-Dihydroxycinnamic acid in the Presence of Barbituric Acids Derivatives

Electrochemistry provides a versatile means for the selective reduction and oxidation of organic compounds. The importance of an electrochemical synthesis lies not only in the selectivity of the reaction but also in the formation of electrons at the electrode surface. Since the electrons are reagent-free, pollution of the environment by spent reagents can be avoided [1]. Recently, we have dealt with the electrochemical oxidation of catechols and 1-(4-(4-hydroxyphenyl)piperazin-1- yl)ethanone in the presence of nucleophiles in aqueous solution. Our previous studies show that the electrochemically generated o-quinone and p-quinone imines are reactive intermediates and as a Michael acceptor, participate in different types of reactions [2,3]. On the other hand, barbituric acid derivatives are well known to possess antibacterial, sedatives, herbicides, fungicides and antiviral agents [3]. However, until now, no report has been published about the electrooxidation of 3,4- Dihydroxycinnamic acid (1) in the presence of barbituric acid derivatives. In this work electrochemical oxidation of 3,4-Dihydroxycinnamic acid (1) has been studied in the presence of barbituric acid (3a) 1,3-dimethylbarbituric acid (3b) and 2-thiobarbituric acid (3c) as nucleophiles (Fig. 1).Some electrochemical techniques such as: cyclic voltammetry using diagnostic criteria derived by Nicholson and Shain for various electrode mechanisms and controlled-potential coulometry were used. The results indicate that the electrochemically generated o-quinone participat in Michael-type addition reaction with barbituric acids (3a–c) via ECECE mechanism and convert to the different barbituric acid derivatives with good yield under controlled potential conditions, at carbon electrode.