Preparation Of Functionalized Ionic Liquids And Their Applications In The Synthesis Of Cyclic Carbonates

The increasing depletion of fossil energy and excessive carbon dioxide emissions caused by excessive use have already made the environment facing severe challenges.Although carbon dioxide is a greenhouse gas that easily causes global warming,it is also a non-toxic,abundant and sustainable C1 resource that can be used to synthesize high value-added organic products.Among many carbon dioxide fixation methods,the reaction of synthesizing cyclic carbonates using epoxides and carbon dioxide has attracted wide attention because of the high conversion rate of the reaction atoms and the cyclic carbonates as products are also widely used.It can be used as a polar aprotic solvent,electrolyte in lithium secondary batteries,pharmaceutical intermediates and fine and agricultural chemicals.However,due to the high inherent thermodynamic stability and kinetic inertness of carbon dioxide,the catalyst has become an important factor to promote the normal progress of this reaction.To synthesize cyclic carbonates more efficiently through cycloaddition reaction,a series of new hydroxyl and carboxyl functionalized benzotriazole ionic liquids were successfully synthesized.Synthesized 1-hydroxyethyl-3-butylbenzotriazole aspartic acid,1-hydroxyethyl-3-butylbenzotriazole glutamic acid,1-hydroxyethyl-3-butaneBenzotriazoleglycolicacid,1-carboxyethyl-3-butylbenzotriazoletartaricacid,1-carboxyethyl-3-butylbenzotriazolemalicacid,1-carboxyethyl-3-butylbenzotriazole citric acid has six functionalized benzotriazole ionic liquids.The structure was characterized ¹H NMR and ¹³C NMR and infrared spectroscopy（IR）.This experiment uses epichlorohydrin as the substrate to explore various conditions.The effects of reaction time,pressure,temperature and catalyst dosage on this reaction were explored and the possible reaction mechanism was proposed.The experimental results show that when the catalyst dosage is 0.5 mol%,the pressure is0.3 MPa,and the temperature is 95℃,after 12 h of catalytic reaction,the cyclic carbonate is 97.3%.At the same time,five hydroxy-functionalized pyrazole ionic liquids were synthesized.Synthesized 1-methyl-2-hydroxyethylpyrazole glutamic acid,1-methyl-2-hydroxyethylpyrazole aspartic acid,1-methyl-2-hydroxyethylpyrazole lactic acid,1-methyl-2-hydroxyethyl pyrazole p-hydroxybenzoic acid and1-methyl-2-hydroxyethyl pyrazole tartaric acid.The structure was characterized ¹H NMR and ¹³C NMR and infrared spectroscopy（IR）.This experiment uses epichlorohydrin as the substrate to explore various conditions.The effects of reaction time,pressure,temperature and catalyst dosage on this reaction were explored and the possible reaction mechanism was proposed.The experimental results show that the yield of cyclic carbonate is 98.3%after 12 hours of catalytic reaction at a catalyst dosage of 0.5 mol%,a pressure of 0.3 MPa,and a temperature of 105℃.These new hydroxyl and carboxyl functionalized ionic liquids can catalyze the synthesis of cyclic carbonates from carbon dioxide under the conditions of metal-free,solvent-free and cocatalyst,and are an environmentally friendly catalyst.