Study On Synthesis And Characterization Of Typical N, N'-dialkylimidazolium-based Ionic Liquids

The materials which are liquid state at a room temperature or near the room temperature are named room-temperature ionic liquids (RTILs) or room temperature molten salts. The RTILs is the perfect substitute of conventional solvents owing to its highly conductivity, wide electrochemical widow, neglectable vapor tension and adjustable acidity, amenable to diverse solutes, proper viscosity, ionic liquids have been widely used in many fields such as electrochemistry, organic synthesis, catalyst and separation. And it arouses great interest in industry for it does not pollute the environment. The study of RTILs accord with the development of green chemistry, and are paid great attention to by the researchers in world in recent years.At first, we have prepared 1-Butyl-3-methylimidazolium bromide ([BMIM]Br) using C₄H₉Br and 1-Methylimidazole. The monofactorial experiment and orthogonal experiment are applied to get the optimum processing conditions. Then, from [BMIM]Br, hydrophilic l-Butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) and hydrophobic 1-Butyl-3-methy-limidazolium hexafluorophosphate ([BMIM]PF₆) have been synthesized by replacement metathesis reaction, and the results were satisfying, and the process of synthesizing [BMIM]BF₄ has been optimized and the pure degree analyse of ionic liquids and the intermediate is studied. Then the difference between the reactions under nitrogen and the ones under air is obtained. All these compounds have been characterized and analyzed by IR and H-NMR spectra. Then, we have determined the physical properties about the bibulous ability and solubility of the RTILs.