Ionic Conjugated Polymers as Heterogeneous Catalysts for the Cycloaddition of Carbon Dioxide to Epoxides to Form Carbonates under Solvent‐ and Cocatalyst‐Free Conditions. Issue 11 (24th November 2022)

• Record Type: Journal Article
• Authors: Xiao, Longqiang; Lai, Yiming; Zhao, Rui; Song, Qianyu; Cai, Jingyu; Yin, Xiangyu; Zhao, Yulai; Hou, Linxi
• Is Part Of: ChemPlusChem. Volume 87:Issue 11(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-11-24
• Subjects: carbon dioxide -- conjugated polymers -- cycloaddition -- epoxides -- heterogeneous catalysts; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/cplu.202200324
• Languages: English
• ISSNs: 2192-6506

Abstract

Abstract: The generation of cyclic carbonates by the cycloaddition of CO2 with epoxides is attractive in the industry, by which CO2 is efficiently used as C1 source. Herein, a series of catalysts were developed to efficient mediate the cycloaddition of CO2 with epoxides to generate carbonates. The catalysts were easily synthesized via the amine‐formaldehyde condensation of ethidium bromide with a variety of linkers. The newly prepared heterogeneous catalysts have high thermal stability and degradation temperatures. The surface of the catalysts is smooth and spherical in shape. The effect of temperature, pressure, reaction time and catalyst dosage on the cycloaddition of CO2 with epoxide were investigated. The results show that the catalyst with 1, 3, 5‐tris(4‐formylphenyl)benzene as the linker can achieve 97.4 % conversion efficiency at the conditions of 100 °C, reaction time of 12 h, and the reaction pressure of 1.2 MPa in a solvent‐free environment. Notably, the polymers serve as homogeneous catalysts during the reaction (reaction temperature above Tg ) and can be separated and recovered easily as homogeneous catalysts at room temperature. In addition, the catalyst is not only suitable for a wide range of epoxide substrates, but also can be recycled many times. Furthermore, DFT calculations show that the coordination between the electrophilic center of the catalyst and the epoxide reduces the energy barrier, and the reaction mechanism is proposed based on the reaction kinetic studies and DFT calculations. Abstract : Ionic conjugated polymers were synthesized by amine‐formaldehyde condensation reactions of ethidium bromide with various linkers. The obtained polymers have smooth spherical surfaces and can effectively catalyze the reaction of epoxides with carbon dioxide under mild conditions to form cyclic carbonates.