Group 4 complexes as catalysts for the transformation of CO2 into polycarbonates and cyclic carbonates

Group 4 complexes, especially titanium, are soil compostable and nontoxic to the soil environment. Hence, group 4 complexes as catalysts are the perfect alternative for the copolymerization and coupling of epoxides and CO2. This review reports the use of group 4 metals as Lewis acid catalysts for the synthesis of polycarbonates (PCs) and cyclic carbonates (CCs) by the copolymerization and cycloaddition of epoxides and CO2 respectively. A comparison between numerous group 4 catalysts has been drawn for their catalytic activities using diverse ligand systems. The catalysts reactivity in terms of molecular weight (M-n) of copolymers, carbonate linkages, the selectivity of PCs over CCs, turn over frequency (TOF) have been discussed in detail. The effect of using additives (nucleophilic cocatalysts) for the copolymerization and coupling reactions has also been investigated. Published by Elsevier B.V.