Conversion of CO2 with epoxides to cyclic carbonates catalyzed by amino acid ionic liquids at room temperature. (February 2022)

• Record Type: Journal Article
• Authors: Qu, Ye; Chen, Yanglin; Sun, Jianmin
• Is Part Of: Journal of CO₂ utilization. Volume 56(2022)
• Publication Date: 2022-02
• Subjects: CO2 conversion -- Cycloaddition reaction -- Amino acid ionic liquid -- Cyclic carbonate -- Room temperature -- Atmospheric pressure; Carbon dioxide -- Periodicals; Carbon dioxide -- Environmental aspects -- Periodicals; Carbon dioxide mitigation -- Periodicals; Carbon dioxide; Carbon dioxide -- Environmental aspects; Carbon dioxide mitigation; Periodicals; 628.53205
• DOI: 10.1016/j.jcou.2021.101840
• Languages: English
• ISSNs: 2212-9820

Abstract

Graphical abstract: Highlights: Amino acid ionic liquids (AAILs) composed of 1, 1, 3, 3-tetramethylguanidine cation with amino acid and halogen anions, were simply synthesized. The AAIL of [HTMG][His][I] showed excellent CO2 cycloaddition activity due to synergetic effect of [HTMG] +, [His] 2– and [I] – . The CO2 cycloaddition reaction proceeded under room temperature and atmospheric pressure conditions without solvent and cocatalyst. This work provided green and sustainable AAILs candidates for efficient CO2 utilization with low-energy input. Abstract: CO2 utilization plays an important role in rational use of carbon resources and reduction of carbon emissions. It is still a challenge to achieve efficient CO2 utilization by amino acid ionic liquids (AAILs) under room temperature and atmospheric pressure with cocatalyst- and solvent-free conditions. Herein, the newly developed AAILs including 1, 1, 3, 3-tetramethylguanidine cation ([HTMG] + ) together with both amino acid and halogen as anions, were simply synthesized by neutralization reaction. Under mild conditions (30 °C, 20 h and 1 MPa CO2 ), the cycloaddition reaction of CO2 and propylene oxide could be efficiently catalyzed by [HTMG][His][I] with 99 % propylene carbonate yield and selectivity in the absence of additional solvent and cocatalyst. Notably, even at room temperature and atmospheric pressure for 72 h, [HTMG][His][I] also displayed 96 % yield and 99 % selectivity due to the cooperation of [HTMG] +, [His] 2– and [I] – . Meanwhile, [HTMG][His][I] performed excellent universality of various epoxides and reusability. Based on the characterization results of 1 H and 13 C NMR, it was verified that propylene oxide and CO2 were simultaneously activated by the functional groups in [HTMG][His][I]. Hence, the reaction mechanism for CO2 cycloaddition with epoxide catalyzed by [HTMG][His][I] was proposed. This work provided a simple strategy to prepare sustainable AAILs for efficient CO2 utilization under very mild conditions of room temperature and atmospheric pressure (even the low CO2 concentration at simulated flue gases).