Syntheses of Benzilic Acids through Electrochemical Reductive Carboxylation of Benzophenones in the Presence of Carbon Dioxide

Article abstract of DOI:10.1246/bcsj.58.1723

Reaction conditions for the electrochemical synthesis of benzilic acid (2a) under the atmosphere of carbon dioxide was investigated from the preparative points of view.The highest yield of 2a (86percent) was obtained under the following conditions; cathode: mercury, electricity passed: 2.3 F/mol, constant current density: 2.5 mA/cm², benzophenone (1a) (8.2*10^-3 mol), electrolyte(KI, 1.7*10^-2 mol) in DNF (50 ml).This method and conditions were applied to the syntheses of twelve benzilic acids (2b-2m) and yielded acids in the range of 10-92percent.The yields were strongly depended on the electronic effect of substituents and benzilic acids were not obtained when the ring substituent was NO2, OH, or Br group.