Study On Preparation And Physical-Thermodynamic Properties Of Ionic Liquids

Room-temperature ionic liquids (ILs) are organic salts composed of cations and anions, which are usually in the liquid at room temperature. Ionic liquid has aroused increasing interests in both industry and academia for its unique chemical and physical properties, for example, its good solubility for a wide spectrum of compounds, non-detectable vapor pressure, wide liquid temperature range, good thermal and electric conductivity and good thermal stability. Ionic liquid was initially utilized in electroplating and electrolysis due to its wide electronic windows, however its application has been expanded greatly, e.g. used as a green solvent, as a catalyst for some reactions, and as a solvent in a separation process. Although it is widely recognized as a promising next generation green solvent after water and supercritical fluid, there is a long way to go to be commercialized in industry before its production cost can be reduced to be comparable with common organic solvents. Therefore, it is imperative to reduce the production cost of ionic liquid by exploring new type of ionic liquids or renovating the present production routes.The thesis is composed of three sections. Firstly, optimization of synthesisprocess for ionic liquids with 1-alkyl-3-methylimidazolium [Rmim]+ cations. Secondly, exploitation of new ionic liquids composed of [Rmim]+. Thirdly, measurement of physical and thermodynamic properties for the new ionic liquids prepared.The majority of ionic liquids are composed of complex inorganic anions and nitrogen- or phosphorus-containing organic cations with different kind and length of substitutes. Typical cations include 1-alkyl-3-alkylimidazolium [RR'im]+, N-alkylpyridinium [Rpy]+, quaternary amine [R4N]+, quaternary phosphor [R4P]+ etc., and the typical inorganic anions are [AlxXy]n-(X are halogen), [BF4]-, [PF6]-, [CH3COO]-, [CF3SO3]- and so on. The synthesis of above mentioned ionic liquids generally need two steps. Firstly, objective cations are formed in a halide form e.g. [Rmim]X, [RPy]X, [R4N]X, and [R4P]X by reacting tertiary amines or tertiary phosphorus with alkyl halide. Then the target ionic liquids are prepared via metathetical reaction between a quaternary amine halide and a salt containing the objective anion. Therefore, it is of great significance for the industrial application of ionic liquid to optimize [Rmim]X technical process, simplify reaction conditions, facilitate separation and purification process. We have optimized the preparation process for a series of 1-alkyl-3-methylimidazolium halide, and products were made with mild conditions and simple experiment equipment. This research helps the industrial production and application of ionic liquid.Traditional ionic liquids are produced with extremely high cost. And some ionic liquids with BF4 and PF6 anions are apt to be decomposed to some corrosive materials such as HF in the present of water. Some ionic liquids with...