Electrocatalytic carboxylation of aromatic ketones with carbon dioxide in ionic liquid 1-butyl-3-methylimidazoliumtetrafluoborate to α-hydroxy-carboxylic acid methyl ester

A new electrochemical procedure for the electrocatalytic carboxylation of aromatic ketones with carbon dioxide in ionic liquid, 1-butyl-3-methylimidazolium tetrafluoborate(BMIMBF4), to alpha-hydroxycarboxylic acid methyl ester was investigated for the first time. The electrochemical behavior of acetophenone in BMIMBF4 was studied by cyclic voltammetry with a reduction peak at -1.9V (vs. Ag). The electrolyses experiments were carried out in an undivided cell under mild conditions without any toxic solvents, catalysts and supporting electrolytes, followed by addition of an alkylating agent, affording the alpha-hydroxycarboxylic acid methyl ester in a moderate yield (62%). The results showed that the yields were strongly affected by various factors: temperature, current density, charge passed, electrode material and substrate concentration. Moreover, the ionic liquid was successfully recycled for this reaction. (C) 2011 Elsevier Ltd. All rights reserved.