Synthesis of Cyclic Carbonate Catalyzed by DBU Derived Basic Ionic Liquids1. Issue 4 (14th February 2018)

• Record Type: Journal Article
• Authors: Li, Wei; Cheng, Weiguo; Yang, Xia; Su, Qian; Dong, Lihui; Zhang, Pan; Yi, Yunan; Li, Bin; Zhang, Suojiang
• Is Part Of: Chinese journal of chemistry. Volume 36:Issue 4(2018)
• Page Start: 293
• Page End: 298
• Publication Date: 2018-02-14
• Subjects: CO2 -- epoxides -- cyclic carbonates -- DBU derived bromide ionic liquid; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/cjoc.201700747
• Languages: English
• ISSNs: 1001-604X

Abstract

Abstract : In this work, 1, 8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU), 1, 5‐diazabicyclo[4.3.0]‐5‐nonene (DBN), and imidazole (MIM)‐derived bromide ionic liquids (ILs) were synthesized and used to catalyze the cycloaddition reactions of carbon dioxide (CO2 ) with several kinds of epoxides to form cyclic carbonates. The DBU derived bromide ionic liquid system was found to have the best catalytic activity among all the tested ILs. The influences of reaction conditions (including temperature, pressure and reaction time) on the reaction of CO2 to propylene oxide (PO) were studied to show the best conditions of 120 °C, 1 MPa, 2.5 h catalyzed by 2 mol% DBU‐derived bromide ionic liquid, with the conversion of PO and the selectivity of propylene carbonate (PC) reaching 99% and 99%, respectively. Under the optimum reaction conditions, the ionic liquid system could be reused at least five times without decrease in selectivity and conversion. NMR spectroscopy and DFT calculations were used to reveal the hydrogen‐bond interaction between ionic liquids and reagent, based on which the reaction mechanism was proposed. Abstract : Hydrogen bond had been formed between ILs and epoxy compound which helped to open the ring of epoxy compounds. Then the ring‐opened epoxy compound reacted with CO2 to form a cyclic carbonate.