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.