Efficient Electrocarboxylation of p-Methylpropiophenone in the Presence of Carbon Dioxide

In the one compartment electrochemical cell 2-hydroxy-2-p-tolyl-butyric acid methyl ester was electrosynthesized by electrochemical carboxylation of p-methylpropiophenone in the presence of carbon dioxide. Under galvanostatic conditions, the electrocarboxylation was influenced by supporting electrolytes, cathode materials, the current density, passed charge and temperatures. Application scope of the eletrocarboxylation system was then examined, and an excellent yield of 97% was obtained when the electrolysis was carried out in DMF-0.1 mol.L(-1) TEABr solution using cheap and environmentally benign nickel as the cathode under a controlled current density of 5.0 mA.cm(-2) until 2.8 F.mo1(-1) charge passed through the cell at -10 degrees C. The electrochemical behavior of p-methoxylacetophenone has been studied on the glassy carbon electrode by cyclic voltammetry and the probable mechanism was proposed accordingly.