Selective Synthesis And Properties Research Of Mono-or Di-imidazolium Polyether Ionic Liquids

The synthesis of cyclic carbonates is a typical green chemical reaction for fixing and capturing CO2 efficiently,of which the products have widely application in textile,printing and dyeing,polymer synthesis and electrochemistry,etc.As a novel media with rapid development under green framework,ionic liquids(ILs)have a good stability and tunable properties of structure,which exhibits potential application prospect in catalytic synthesis of cyclic carbonates from CO2 and epoxides.In view of the defects of existing catalysts for synthesis of cyclic carbonates such as poor active stability and difficult separation of homogeneous catalysts,a designed polyethylene glycol(PEG)-supported imidazole ionic liquid with high catalytic activity,which containing many-OH group,was synthesized and used as catalyst.The major work and innovative results for this dissertation are as follows.1.PEG-supported mono-or di-imidazolium ionic liquids were synthetized by utilizing PEG with different molecular weights as carrier,of which the influence on CO2 adsorption capacities was analysis compared.The results shown that the low molecular weights' PEG supported mono-imidazolium ionic liquids were more dominant than di-imidazolium ionic liquids in terms of CO2 adsorption.The saturated adsorption capacities of PEG400 supported mono-imidazolium ionic liquid reached to 77.55 mg/g:Both hydrogen bond and ethoxy bond in molecular structure offer solubilization to CO2,which will have great utilization potentiality in enhancing efficient catalytic conversion of CO2.2.A series of PEG-supported imidazolium ionic liquids catalyst containing polyhydroxy structure were designed and synthesized,which were applied to catalyzing the cycloaddition.The catalytic activities were also tested.It was found that through using N-ethyl-N'-PEG400 imidazole bromine ionic liquid([PEG400EMIM]Br)as the catalyst under conditon of catalyst amount 1.0 mol%,2.0 MPa,130 ? and 1.5 h,the yield and selectivity of propylene carbonate could achieve 98%and more than 99%,respectively.The catalyst was also found to be extended to cycloaddition of other type epoxides.In addition,the catalyst can be recycled five times without any decrease in activity.3.The possible mechanism for the synergistic catalytic effect of-OH in PEG-supported imidazolium ionic liquids and halide anions was proposed.