Protonated triethanolamine as multi-hydrogen bond donors catalyst for efficient cycloaddition of CO2 to epoxides under mild and cocatalyst-free conditions. (December 2016)

• Record Type: Journal Article
• Authors: Liu, Mengshuai; Li, Xin; Liang, Lin; Sun, Jianmin
• Is Part Of: Journal of CO₂ utilization. Volume 16(2016)
• Page Start: 384
• Page End: 390
• Publication Date: 2016-12
• Subjects: Triethanolamine -- Protonation -- CO2 conversion -- Epoxide -- Cyclic carbonate; 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.2016.10.004
• Languages: English
• ISSNs: 2212-9820

Abstract

Graphical abstract: Facilely prepared and environmentally benign [HTEA]I catalyst exhibited excellently synergetic effects on CO2 cycloaddition to epoxides under metal- and cocatalyst-free conditions. Highlights: Protonated triethanolamine [HTEA]I was one-step prepared, low cost and environmentally benign. [HTEA]I showed superior catalytic activity for CO2 coupling with various epoxides. The catalytic reaction was performed under mild conditions without additional solvent and cocatalyst. The multi hydrogen bond donors replaced the participation of toxic transition metals for epoxide activation. The catalyst was easily recycled and showed excellent chemical and structural stability. Abstract: The protonated triethanolamine salts with multiple hydrogen bond donor groups were one-step prepared and demonstrated to be simple, environmentally benign and highly efficient catalyst for the chemical fixation of carbon dioxide to cyclic carbonates under mild reaction conditions without additional cocatalyst and organic solvent participation. Hydrogen-bonding activation towards epoxide is a special class of mimetic alternative to Lewis acid activation for favor of opening the epoxy ring, which was recognized as the rate-determining step for the CO2 cycloaddition reaction. Here the effects of reaction parameters on catalytic activity for propylene carbonate (PC) synthesis from propylene oxide (PO) and CO2 were investigated thoroughly. With 0.65 mmol (1.88 mol%) catalyst loading, 91% PC yield with 99% selectivity were obtained at 110 °C and 2.0 MPa for 6.0 h. The [HTEA]I catalyst could be easily separated and regenerated from the reaction products for subsequent reuse, also displayed versatility to CO2 cycloaddition with other epoxides. Additionally, the possible synergistic catalytic mechanism deriving from cation and anion of protonated triethanolamine catalyst was proposed.