The first synthesis of a cyclic carbonate from a ketal in SC-CO2

In this paper the synthesis of a cyclic organic carbonate by a halogen-free route is described. The ketal formed from cyclohexanone and 1,2-ethanediol was reacted with carbon dioxide, either in SC-CO2 or in organic solvents under CO2 pressure. Transition-metal complexes with functionalized fluorinated di-ketone ligands were used as catalyst. The synthetic methodology based on SC-CO2 is effective for the synthesis of ethylene carbonate. The use of methanol as co-solvent in SC-CO2 prevents the formation of the ethylene carbonate and only the alcoholysis of the ketal is observed. In organic solvents, no reaction takes place. (C) 2002 Elsevier Science B.V. All rights reserved.