Carbon dioxide as carbon source: Activation via electrogenerated O2•- in ionic liquids

The activation of carbon dioxide has been obtained in O-2/CO2 saturated ionic liquids, via electrochemically generated O-2(center dot-), at a less negative potential than the one of the direct cathodic reduction of CO2. This electrochemical activation has been applied to the C-N bond formation from amines and carbon dioxide in the synthesis of organic carbamates. A competitive reaction between electrogenerated superoxide ion and imidazolium cations yielding 2-imidazolones has been pointed out. This procedure allows to avoid the utilization of volatile and toxic organic solvents, supporting electrolytes and catalysts. (C) 2011 Elsevier Ltd. All rights reserved.