Organic carbonates as green and sustainable complexing agents for double metal cyanide catalysts for the synthesis of polyether and poly (ether-carbonate) polyols

We investigated various linear carbonates, including dimethyl carbonate and diethyl carbonate, and cyclic carbonates such as ethylene carbonate, propylene carbonate (PC), butylene carbonate, and glycerol carbonate, as complexing agents (CAs) for the preparation of double metal cyanide (DMC) catalysts. The DMC catalysts bearing carbonate complexing agents exhibited good to excellent activities for the ring-opening polymerization of epoxides (turnover frequencies of up to 467 min-1) and the copolymerization of epoxides and CO2, producing polyether polyols with moderate molecular weights (1700-9700 g mol-1), narrow polydispersity indexes (1.1-1.2), very low unsaturation values (0.002-0.009), and low viscosities (438 -997 cP). The DMC catalyst bearing PC also afforded linear and branched polycarbonate polyols in high yields (up to 83%) and carbonate contents (up to 36 mol%). Density functional theory calculations were also performed to understand the effect of the CAs on the structural properties and activities of the corresponding DMC catalysts.