The synthesis of cyclic carbonates by the 100% atom economical reaction between epoxides and CO₂ is reviewed in the context of reducing global emissions of waste CO₂ and converting waste CO₂ into industrially useful chemical feedstocks.

Three interconnected catalytic cycles account for the title reaction catalyzed by a bimetallic aluminum(salen) complex and Bu₄NBr. In the first, Bu₄NBr acts as a nucleophile to activate the epoxide. In the second, Bu₃N generated in situ serves to activate CO₂. In the third, the aluminum(salen) complex brings the two activated species together so that the key bonds can be formed intramolecularly. magnified image

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.