Facile synthesis of [urea-Zn]I₂ eutectic-based ionic liquid for efficient conversion of carbon dioxide to cyclic carbonates

Several environmentally benign eutectic-based ionic liquids (ILs) were developed as novel homogeneous catalysts for efficient conversion of carbon dioxide to cyclic carbonates. Propylene oxide (PO) was selected as a benchmark substrate to optimize the catalytic activity, and on account of the catalytic cooperativity between the cation and anion in the [urea-Zn]I₂ catalyst, excellent yield (95%) and selectivity (98%) to propylene carbonate (PC) was obtained under the optimized reaction conditions of 120°C and 1.5 MPa for 3.0 h in the absence of cocatalyst and solvent. Also [urea-Zn]I₂ was proved to be an efficient and versatile catalyst, and could realize catalytic conversion of CO₂ with various epoxides. Moreover, the synergistic reaction mechanism involving cation structure and halogen anion for CO₂ conversion was proposed, and the eutectic-based ILs were easily recyclable with high activity. The eutectic-based ILs that possessing low cost, moisture-stability, facile synthesis and efficiently bifunctional properties reported herein displayed the exceptionally outstanding features for efficient conversion of CO₂ to cyclic carbonates. 2015 Elsevier B.V.