Theoretical Study Of Mechanisms Of Carbon Dioxide Reacting With Epoxides Catalyzed By Ionic Liquids

In recent years,the global"Greenhouse Effect"has been intensified,and the situation is grim and unoptimistic.Therefore,catalytic transformation of the main component gas,carbon dioxide?CO₂?,has become the focus of many research groups.As more and more catalyst systems are reported,chemicals developed from CO₂ have emerged continuously,and ionic liquid catalysts have also played an important role in this field.Ionic liquids usually exhibit brilliant characteristics of low melting point,lowsaturatedvaporpressure,highthermalstability,andtunable structure-modification.They are widely used in the study of catalytic conversion of CO₂.On the other hand,the progress of science and technology has greatly promoted the development of various chemical computing softwares.Obviously,the combination between theoretical calculations and experiments not only supplemented microdata,but also supported experimental results.Therefore,as for the two experimental systems on“CO₂”catalysis,we have carried out two calculation tasks on CO₂ conversion:We used DFT methods to investigate how the one-pot conversion of CO₂,ethylene oxide and amines to oxazolidinones catalyzed by the binary ionic liquids of BmimBr and BmimOAc resulted in different yields of products.The calculated results showed the key elementary reaction having great impact on the cycloaddition reaction between N from amino group and C from ring-opening structure.The NBO charge of N from amino group and hydrogen-bonding mutually played critical roles on energy barriers.Base on aniline,the calculated energy barriers following the order of electron-withdrawing substituting amine,electron-donating substituting amine and aliphatic amine growed up,so that the yields of the corresponding types declined down.As for the reaction from CO₂ and epichlorohydrin to acrylic carbonate catalyzed by amino-functionalized imidazole ionic liquid Intra-IL1,we mainly conducted a test on how catalytic amount of water behaved when side chain amino group activated CO₂.DFT results reflected that C2-H of imidazole in Intra-IL1 activated O from epoxide via hydrogen-bonding.CO₂ was activated by water to form H₂CO₃,and then in the form of HCO₃^-reacted with side chain amino group of Intra-IL1 to generate amino cation,driving reaction forward.Amines acting as catalysts regulate the condensation of HCO₃^-,and it's helpful for promotion of product yields.