Bio-based polyesters synthesized by ring-opening copolymerizations of eugenyl glycidyl ether and cyclic anhydrides using a binuclear [OSSO]CrCl complex†
A novel binuclear chromium complex of dianionic [OSSO]-type ligand has been synthesized and employed toward the ring-opening copolymerization of renewable eugenyl glycidyl ether (EGE) and cyclic anhydrides (CAs) (succinic anhydride (SA), phthalic anhydride (PA), maleic anhydride (MA), itaconic anhydride (IA), endo-norbornene anhydride (NA), and tetrahydrophthalic anhydride (THPA)), showing high activity in conjunction with bis(triphenylphosphine)iminium chloride (PPNCl). Most of the resultant polyesters show perfect alternating microstructures except polyesters derived from IA/EGE and MA/EGE copolymerimerization, where 14% and 11% of ether units are observed, respectively. Among the CAs tested, renewable SA shows the highest reactivity as a highly regioselective model, providing a facile route to prepare the fully biomass-based polyester bearing a dominant head-to-tail structure. The results of ESI-MS indicate that the maximum coordination number of PPNCl in the dinuclear [OSSO]CrCl complex is only one. The pendant allyl groups onto the resultant polyesters backbone provide an additional versatility for further functionalizations.