En Route Toward Sustainable Polycarbonates via Large Cyclic Carbonates

This review reports an up-to-date overview of the synthetic methodologies developed for the preparation of large cyclic organic carbonates with ≥6-membered rings (6M-CCs and above), highlighting the most sustainable synthetic pathways employing diols (including renewable-based ones) and nonhazardous carbonyl sources, e.g., linear organic carbonates, in mild operating conditions. The lower thermodynamic stability of 6M-CCs compared to 5-membered ones allows for a straightforward preparation of biocompatible aliphatic polycarbonates (APCs), occurring via ring-opening polymerization (ROP), in the presence of various active organo- and/or biocatalysts. Moreover, ROP processes can be tuned for the selective preparation of copolymers with different thermomechanical properties and can be further applied to structurally complex, larger cyclic carbonate derivatives. Finally, the end-of-life fate of APCs, particularly the recently reported controlled depolymerization strategies, is critically discussed focusing on chemoselectivity toward cyclic carbonate or epoxide monomers. This timely overview highlights the open challenges as well as the opportunities associated with the synthesis of APCs and chemical recycling and highlights their potential as circular and sustainable plastics.