Electrochemical synthesis of organic compounds:: 1.: Addition of sulfinic acids to electrochemically generated o- and p-benzoquinones

Electrochemical oxidation of catechol (1a) and 4-methylcatechol (1b) in the presence of p-toluenesulfinic acid (1) and 1,4-dihydroxybenzene (4) in the presence of p-toluenesulfinic acid and benzenesulfinic acid (II) has been studied using cyclic voltammetry and controlled potential coulometry. The results indicate that compounds 1a and 1b react with I, and 4 reacts with I and II via a Michael addition reaction leading to the sulfones 3a, 3b and 6, 7, respectively. Products were obtained in good yield and purity. The mechanism of oxidation was deduced from voltammetric data and by coulometry at controlled potential. The products have been characterized after purification by IR, H-1-NMR, and elemental analysis. (C) 2002 Elsevier Science B.V. All rights reserved.