Novel Polyurethane-Catalyzed Cyclic Carbonate Synthesis Using CO2 and Epoxide

The conversion of industrially produced greenhouse gases, like CO2, into value-added chemicals is economically beneficial to industry and vital for environmental conservation. However, the conditions for these conversions must themselves be sustainable. In this work, polyurethane (PU) was used to catalyze the formation of five-membered cyclic carbonates (5CCs) via cycloaddition of epoxides and CO2. Using optimized conditions, the representative epoxide, phenyl glycidyl ether, afforded the corresponding 5CC (PGE-5CC) in a quantitative yield with remarkable selectivity (>99%). The PU catalyst does not degrade during the reaction and is separable by simple filtration. In addition, PU could catalyze the 5CC synthesis at least 10 times without loss of catalytic activity and is applicable to a wide range of substituted epoxides. This study pioneers the utilization of polyurethane as an easily recycled catalyst in halogen-free and metal-free reactions for the repurposing of CO2 waste.