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

• Several eutectic-based ILs were facilely synthesized and thoroughly characterized.
• [Urea-Zn]I2 showed superior activity for CO2 cycloaddition to various epoxides.
• The catalytic reaction was performed under cocatalyst/solvent- free conditions.
• The catalyst was low cost, moisture-stable, environmentally benign and recyclable.

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.

Figure optionsDownload high-quality image (81 K)Download as PowerPoint slideLow cost, moisture-stable and environmentally benign eutectic-based ionic liquids were facilely synthesized and exhibited excellent synergetic effects on CO2 cycloaddition to epoxides under mild and solvent-free conditions without cocatalyst.