Dimetallic aluminium(salen) complexes show exceptionally high catalytic activity for the synthesis of cyclic carbonates from terminal epoxides at ambient temperature and pressure. The process has the potential to contribute towards decreasing atmospheric carbon dioxide emissions from the burning of fossil fuels. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Homogeneous and immobilized one-component catalysts for the conversion of epoxides and carbon dioxide into cyclic carbonates at atmospheric pressure and room temperature have been developed.

The development of one-component, bimetallic μ-oxoaluminium(salen) complexes as highly active catalysts for the synthesis of cyclic carbonates from terminal epoxides is described. The resulting homogeneous catalysts are used in batch reactions at room temperature and one atmosphere pressure. The catalysts have also been immobilized onto various support materials and used in either batch reactions or gas-phase flow reactions with ethylene and propylene oxides. Catalyst lifetime, deactivation and reactivation have been studied in both batch and flow reactions, and it has been shown that of the impurities present in power station flue gas, only sulfur trioxide deactivates the catalyst and at the concentrations of sulfur trioxide present in flue gas, this deactivation would require more than one years exposure of the catalyst to flue gas.

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Exceptionally Active Aluminum(salen) Complexes as Catalysts. -A dimetallic aluminum-salen complex (DMAS) displays exceptionally high catalytic activity in the presence of a quaternary ammonium salt as cocatalyst for the insertion of carbon dioxide into epoxides (I). The reaction proceeds efficiently under mild conditions (atmospheric pressure of CO2, absence of solvent, room temperature or lower) for mono-substituted epoxides. Epoxides obtained from internal olefins, e.g. stilbene oxide or cyclohexene oxide, are not suitable as substrates. -(MELENDEZ, J.; NORTH*, M.; PASQUALE, R.; Eur.