Synthesis Of Ionic Liquids And Their Application In Acid Catalytic Reactions

Room temperature ionic liquids (RTILs) are materials that are composed entirely of ions, which totally remain liquid state at room temperature and below. They have a number of unique properties such as highly conductivity, wide electrochemical window, negligible vapor tension and special solubility. The properties enable their use as alternative solvents and may speed the introduction of these potentially "green" solvent into sustainable industrial processes. RTILs are gaining worldwide academic and industrial attention as replacements of traditional organic solvents in catalysis and separations, in addition to their establish use in electrochemistry.At first, five kinds of N,N'-dialkylimidazolium-based RTILs were synthesized including 1-butyl-3- methylimidazolium tetrafluoborate ([BMIM]BF₄), 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF₆), l-butyl-3-methylimidazolium hexafluoroantimonate ([BMIM]SbF₆), 1-butyl-3- methyl - imidazolium p-toluene sulfonate ([BMIM]ToS) and 1-methylimidazolium tetrafluoborate([HMIM]BF₄). These samples were characterized by IR spectroscopy.Then, Beckmann rearrangement of cyclohexanone oxime has been studied in catalytic medium composed of ionic liquids and catalysts. The product selectivity and yield were not enhanced largely in ionic liquids medium without the presence of any other organic solvent. But high conversion and selectivity were obtained when using phosphorous pentachloride (PCl₅) in the biphasic systems composed of ionic liquids and toluene. The effects such as reaction temperature, reaction time, the amount of RTILs, the amount of catalyst, kind of catalysts and kind of ionic liquids was also investigated. The optimized conditions were 1.5ml [BMIM]BF₄, 5ml toluene, 1.14g PCl₅, 10ml 1mol/L cyclohexanone oxime/toluene at 80℃ reacting 30min. At above conditions, the conversion of cyclohexanone oxime and the selectivity of caprolactam reached 97.74% and 87.29% , respectively.At last, the alkylation of phenol with tert-butyl alcohol was carried out in ionic liquids. Comparative studies on the catalytic properties of different catalysts in different ionic liquids...