Imidazolium ionic liquids/organic bases: Efficient intermolecular synergistic catalysts for the cycloaddition of CO2 and epoxides under atmospheric pressure

Mechanistic Studies of CO2 Cycloaddition Reaction Catalyzed by Amine-Functionalized Ionic Liquids

“…The previous studies (Elageed et al, 2016; Luo et al, 2016; Huang et al, 2017; Ji et al, 2018) supported that the imidazolium rings of ionic liquids could form hydrogen bonding interaction with epoxides. In AFIL, the moiety of 2-buthylimidazole can assist the ring-opening process of epoxides through hydrogen-bonding interaction with them.…”

“…The previous experimental and theoretical studies (Elageed et al, 2016; Ji et al, 2018) have revealed that the ionic liquids having imidazolium rings could assist the reaction of ring-opening of epoxides by forming hydrogen bonding interaction with epoxides. On the other hand, it has been reported that the yields of products for CO 2 conversion catalyzed by the tertiary amines such as DBU (Heldebrant et al, 2005) and DABCO (Ji et al, 2018) increased remarkably in the presence of water. In the reactions of CO 2 and epoxides catalyzed by ionic liquids, the appropriate amount of water would facilitate the formation of bicarbonate salts effectively.…”

“…1 H NMR (400 MHz, DMSO-d6, TMS): δ 9.37 (s, 1H), 7.85 (s, 2H), 7.37–7.26 (m, 4H), 5.43 (s, 2H), 4.20 (t, J = 6.0 Hz, 2H), 3.51 (s, 2H), 2.46–2.40 (m, 4H), 1.81–1.74 (m, 2H), 1.27–1.22 (m, 2H), 0.97–0.88 (m, 9H). The ionic liquid 1-benzyl-3-butylimidazolium bromide (BnBimBr) was synthesized by a reported method (Ji et al, 2018).…”

“…Luo et al (2016) and Huang et al (2017) performed detailed DFT calculations on the reaction mechanisms of amines, CO 2 and EO catalyzed by the binary ionic liquids BmimBr and BmimOAc. Further, Ji et al (2018) researched an efficient catalyst that was composed of imidazolium ionic liquids and organic bases for catalyzing the cycloaddition of CO 2 and epoxides under atmospheric pressure. The mixed system of ionic liquid and organic base exhibits distinctly higher catalytic activity than using single component alone.…”

Highly efficient conversion of CO2 to cyclic carbonates with a binary catalyst system in a microreactor: intensification of “electrophile–nucleophile” synergistic effect

“…In the past decades, various catalysts have been developed for the coupling reaction of CO 2 with epoxides, such as metal oxides, 20,21 alkali metal salts, 22,23 organic bases, 24,25 ionic liquids, [26][27][28] metal complexes, [29][30][31] and so on. Prominent among these are the homogeneous catalyst systems based on well-dened metal complexes.…”