【摘要】：酸功能化離子液體作為一種能有效替代傳統(tǒng)催化劑的新型材料,具有良好的應(yīng)用前景。為探究陰離子功能基團(tuán)相同的單、雙核離子液體酸強度與分子結(jié)構(gòu)間的基本規(guī)律,設(shè)計合成了四種酸功能化離子液體,測定并對比了單、雙核離子液體的酸強度,對其構(gòu)型進(jìn)行了分析,從分子角度驗證了實驗結(jié)論。采用兩步法制備出單核磺酸化離子液體[MIM(CH2)4HSO3][HSO4](IL1)與單核羧酸化離子液體[MIM(CH2)4COOH][HSO4](IL3);采用多步法制備出了雙核磺酸化離子液體(CH2)4[IM(CH2)4HSO3]2[HSO4]2(IL2)與雙核羧酸化離子液體(CH2)4[IM(CH2)4COOH]2[HSO4]2(IL4)。采用Hammett指示劑與紫外光譜聯(lián)用法對不同濃度的單核離子液體與同濃度的雙核離子液體進(jìn)行了酸強度表征。結(jié)果表明,陽離子功能基團(tuán)相同時,同濃度下的雙核離子液體有更高的酸強度;HSO4-同摩爾量下的雙核離子液體并未顯現(xiàn)出強于單核離子液體的酸強度。陽離子功能基團(tuán)的不同會對離子液體的酸強度產(chǎn)生一定影響;同濃度下磺酸化離子液體的酸強度更強。利用密度泛函理論(Density functional theory,DFT)中B3LYP/6-311++G(d,p)基組對單核離子液體的陽離子[MIM(CH2)4HSO3]+與[MIM(CH2)4COOH]+、雙核離子液體的陽離子(CH2)4[IM(CH2)4HSO3]22+與(CH2)4[IM(CH2)4COOH]22+、單核離子液體構(gòu)型MIM(CH2)4HSO3][HSO4]與[MIM(CH2)4COOH][HSO4]、雙核離子液體構(gòu)型(CH2)4[IM(CH2)4HSO3]2[HSO4]2與(CH2)4[IM(CH2)4COOH]2[HSO4]2的幾種可能存在構(gòu)型進(jìn)行了結(jié)構(gòu)優(yōu)化、能量計算以及頻率分析,并對各穩(wěn)定構(gòu)型的相互作用能與電荷分布進(jìn)行分析。氫鍵是構(gòu)型穩(wěn)定與否的重要因素,氫鍵越多且其長度越短,構(gòu)型越穩(wěn)定。陰離子的引入,使陽離子內(nèi)氫鍵在鍵數(shù)與鍵能上均被削弱,陽離子功能基團(tuán)上的氫原子更傾向于脫落而與陰離子HSO4-中氧原子形成新鍵,以更穩(wěn)定的兩性離子同H2SO4分子相互作用的構(gòu)型存在。電荷分析發(fā)現(xiàn),單、雙核離子液體中的陰、陽離子功能基團(tuán)的氫原子顯現(xiàn)出了強酸性,其次咪唑環(huán)上N-C-N中碳原子上所連接H也顯示出較強的酸性;雙核離子液體中雙咪唑環(huán)的存在強化了吸電子誘導(dǎo)效應(yīng),使得電子隨碳鏈偏移咪唑環(huán)的能力增強,陽離子功能基團(tuán)-HSO3以及-COOH上的電負(fù)性降低,HSO4-上電負(fù)性增強,雙核離子液體酸性減弱;所得結(jié)論具有與實驗中單、雙核離子液體酸強度強弱順序一致的規(guī)律。
[Abstract]:Acid-functionalized ionic liquids, as a new material which can effectively replace traditional catalysts, have a good prospect of application. In order to explore the basic law between the acid strength and molecular structure of mononuclear ionic liquids with the same anionic functional groups, four kinds of acid-functionalized ionic liquids were designed and synthesized, and the acid strength of mononuclear ionic liquids and binuclear ionic liquids were measured and compared. The configuration was analyzed and the experimental results were verified from the molecular point of view. [MIM (CH2) 4HSO3] [HSO4] (IL1) and [MIM (CH2) 4COOH] [HSO4] (IL3) were prepared by two-step method. Binuclear sulfonated ionic liquids (CH2) 4 [IM (CH2) 4HSO3] 2 [HSO4] 2 (IL2) and binuclear carboxylate ionic liquids (CH2) 4 [IM (CH2) 4COOH] 2 [HSO4] 2 (IL4) were prepared by multistep method. The acid strength of mononuclear ionic liquids and binuclear ionic liquids of the same concentration were characterized by Hammett indicator and UV spectroscopy. The results show that the binuclear ionic liquids of the same concentration have higher acid strength when the cationic functional groups are the same, while the binuclear ionic liquids with the same HSO4- molar amount do not show stronger acid strength than mononuclear ionic liquids. The difference of cationic functional groups will affect the acid strength of ionic liquids to some extent, and the acid strength of sulfonic ionic liquids is stronger at the same concentration. MIM (CH2) 4HSO3 and [MIM (CH2) 4COOH] of mononuclear ionic liquids based on B3LYP/6-311 G (dapp) basis group in density functional theory (Density functional theory,DFT) are used. The binuclear ionic liquids (CH2) 4 [IM (CH2) 4HSO3] 22 and (CH2) 4 [IM (CH2) 4COOH] 22, mononuclear ionic liquids MIM (CH2) 4HSO3] [HSO4] and MIM (CH2) 4COOH] [HSO4], Several possible configurations of binuclear ionic liquids (CH2) 4 [IM (CH2) 4HSO3] 2 [HSO4] 2 and (CH2) 4 [IM (CH2) 4COOH] 2 [HSO4] 2 have been optimized for structural optimization, energy calculation and frequency analysis. The interaction energy and charge distribution of each stable configuration are analyzed. Hydrogen bond is an important factor in the stability of configuration. The longer the hydrogen bond is, the more stable the configuration is. With the introduction of anions, hydrogen bonds in cations are weakened in both bond number and bond energy. Hydrogen atoms in cationic functional groups tend to fall off and form new bonds with oxygen atoms in anionic HSO4-. A more stable configuration of amphoteric ions interacting with H2SO4 molecules exists. Charge analysis showed that the hydrogen atoms of anion and cationic functional groups in mononuclear and binuclear ionic liquids showed strong acidity, and the hydrogen atoms attached to carbon atoms in N-C-N on the imidazole ring also showed strong acidity. The existence of biimidazole ring in binuclear ionic liquids enhances the ability of electron to shift the imidazole ring with carbon chain, decreases the electronegativity of cationic functional group-HSO3 and-COOH, and enhances the electronegativity of HSO4-. The acidity of binuclear ionic liquids was weakened; The results are consistent with the order of acid strength of mononuclear ionic liquids and binuclear ionic liquids.
【學(xué)位授予單位】：河北工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：O645.1

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