Esmail Tammari

Electrochemical oxidation of acetaminophen (1) in the presence of barbituric acid (2a), 1,3-dimethyl barbituric acid (2b), 2- thiobarbituric acid (2c) and 1,3-diethyl-2-thiobarbituric acid (2d) as nucleophiles in aqueous solution has been studied using cyclic voltammetry and controlled-potential coulometry. The results indicate that the p-quinone imine derived from electrooxidation of acetaminophen (1) participates in a Michael addition reaction with 2a-d to form the corresponding barbituric acid derivatives (7a-d). In addition, the homogeneous rate constants were estimated by comparing the experimental cyclic voltammetric responses with the digital simulated results. The electrochemical synthesis of 7a-d has been successfully performed in an undivided cell in good yields and purity at biological pH.