Characters and Applications of imidazolium ionic liquidMesoscopic Aggregation and Carbon dioxide fixation

• Main Authors: Tsao-Dong Wu, 吳朝棟
• Other Authors: 劉陵崗
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/56317214828874376798

博士 === 國立臺灣大學 === 化學研究所 === 98 === Recently, the topics of substituting volatile organic solvents with ionic-liquids takes advantages of the flexibility in designed functionalities. Ionic-liquids improves the reaction capabilities with specific functionalities and also becomes more eco friendly. We have synthesized ionic liquids built-in with mononuclear, binuclear and multinuclear imidazolium cations and have probed the molecular interactions of monoimidazolium ionic liquids with 1H-NMR and TEM. We have found that the property of mesoscopic aggregation of ionic liquids are with two dominant forces, the hydrogen bonding (Brønsted acid-base pair) and the π-acid (Lewis acid-base pair) besides the charge attraction and repellence. The application on catalytic conversion of ROH to RBr with mononuclear ionic-liquids have been shown that the ionic-liquid catalysts could be recovered and reused for six times without loss of reactivity. In D2O at pH 7, we have found that the binuclear ionic liquids spontaneously form carbene species as an important intermeatiale on dynamic H-D exchange phenomena and are employed as initially agents for the caprolactone ring-open polymerization to synthesis the bio-degradation polycaprolactone. We have also developed a carbene derivative, N,N’-dimethylimidiazolium-2 -carboxylate (1-1-CO2, a masked carbene). According the TGA results, 1-1-CO2 would be sublimed instead of thermally decomposed at 130℃. Hence 1-1-CO2 was used in the CO2 fixation reaction, to catalyze the conversion of propylene epoxide into propylene carbonate, 1-1-CO2 being reused as catalyst for 10 times. Multinuclear imidazolium ionic-liquids could also be the catalyst for cycloaddition reaction of carbon dioxide and epoxy species, and have been reused for 8 times. Furthermore, this catalyst system fixed at high molecular weight skeleton is easy for the V separation of products by simple filtration utilizing SiO2. In conclusion, this exploratory work was being devoted to the capability of ionic-liquids, on catalytic halide substitution reaction for hydroxyl group of an alcohol, ring-open polymerization of caprolactone, and cycloaddition reaction with carbon dioxide and epoxide. The reactions are all improved to more friendly towards the environments.