Properties of Imidazolium Ionic Liquids with Glycerol-Derived Functional Groups

The selection of functional groups at the N(1) and N(3) sites of the imidazolium cation provides versatile opportunities for the design and synthesis of novel ionic liquids (ILs). Here, we show how glycerol-derived ethers provide new possibilities for the introduction of highly tailored, branched functional groups and how the selection of symmetric or asymmetric branches influences the properties of the resultant 1-R-3-methylimidazolium bistriflimide ILs. The densities and viscosities of these ILs were measured in the temperature range of 293.15-353.15 K and compared with those of the analogous 1-n-alkyl-3-methylimidazolium ILs. The temperature dependence of corresponding properties was elucidated using either linear or exponential models. Furthermore, CO2 absorption isotherms were obtained for one of the ILs, 1-(1-(2-methoxyethoxy)-3-(2,2,2-trifluoroethoxy)propan-2-yl)-3-methyl-imidazolium bistriflimide ([(ME, F)-mim][Tf2N]). This IL had a higher CO2 capacity than most physical solvents considered including its associated precursor, other imidazolium ILs, and DMPEG.