Making plastics from carbon dioxide:: Salen metal complexes as catalysts for the production of polycarbonates from epoxides and CO2

A review focusing in a comprehensive chronicle of the coupling reactions of oxiranes and carbon dioxide catalyzed by salicylaldimine(salen)-metal derivatives in the presence of appropriate cocatalysts, with the emphasis on polycarbonate production is presented. Investigations include available epoxide monomers, cyclohexene oxide and propylene oxide. These studies have revealed that chromium and cobalt are the most effective catalysts for polycarbonate synthesis, with aluminum derivatives being the less active. The effectiveness is due to the fact that Cr and Co are substitutionally inert. Of importance, computational methods contributed to the understanding of the mechanistic aspects of the copolymerization reactions.