- 學位論文
咪唑型離子液體的研究與應用 聚集行為及二氧化碳固化反應
Characters and Applications of imidazolium ionic liquid Mesoscopic Aggregation and Carbon dioxide fixation
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摘要
近年來離子液體的可設計性引入替代溶劑相關研究中，頗受到重 視。利用離子液體的特殊性質改良反應，以對環境更加友善。本研究 分別合成了單核、雙核和多核咪唑陽離子型離子液體。以1H-NMR 探 討單核咪唑離子液體離子間作用力的關係，發現聚集(Mesoscopic Aggregation)的現象，且以奈米金屬粒子呈色觀察確認。 我們應用單核咪唑離子液體於選擇性催化鹵素取代羥基反應中， 顯示離子液體可重覆使用6 次且維持反應性。在重水中pH = 7 環境下， 雙核咪唑離子液體，在動力學轉換中會形成碳烯物種，研究結果顯示 碳烯物種的反應機構為自發性。此特性可應用在己內酯開環聚合上， 以雙咪唑離子液體為起始劑，合成生物可分解的聚己內酯。 另外我們發展碳烯衍生物(Masked Carbene)，合成了N,N-雙甲基咪 唑2-碳酸酯，簡稱1-1-CO2，其TGA 的結果(恆溫實驗)，顯示130℃的 熱重損失為會昇華而非熱解現象。以此碳烯衍生物催化二氧化碳環氧 化物的加成反應，可重覆使用10 次，幾乎均為量產。多核咪唑型離子 液體，同樣也可應用於二氧化碳對環氧化物的加成反應，除了可重覆 使用8 次外，其高分子量固定化的特性，同時發展出非常容易分離純 化產物的系統，只需經SiO2 過濾，即可得到產物。 綜合上述，本研究探討離子液體的性質，應用於催化取代反應、 III 己內酯的開環聚合反應和二氧化碳對環氧化合物的加成反應，證實離 子液體確實改良反應，對環境更加友善。
並列摘要
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.
參考文獻
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