酸功能化离子液体的合成及其结构分析
发布时间：2018-11-26 17:11
【摘要】：酸功能化离子液体作为一种能有效替代传统催化剂的新型材料,具有良好的应用前景。为探究阴离子功能基团相同的单、双核离子液体酸强度与分子结构间的基本规律,设计合成了四种酸功能化离子液体,测定并对比了单、双核离子液体的酸强度,对其构型进行了分析,从分子角度验证了实验结论。采用两步法制备出单核磺酸化离子液体[MIM(CH2)4HSO3][HSO4](IL1)与单核羧酸化离子液体[MIM(CH2)4COOH][HSO4](IL3);采用多步法制备出了双核磺酸化离子液体(CH2)4[IM(CH2)4HSO3]2[HSO4]2(IL2)与双核羧酸化离子液体(CH2)4[IM(CH2)4COOH]2[HSO4]2(IL4)。采用Hammett指示剂与紫外光谱联用法对不同浓度的单核离子液体与同浓度的双核离子液体进行了酸强度表征。结果表明,阳离子功能基团相同时,同浓度下的双核离子液体有更高的酸强度;HSO4-同摩尔量下的双核离子液体并未显现出强于单核离子液体的酸强度。阳离子功能基团的不同会对离子液体的酸强度产生一定影响;同浓度下磺酸化离子液体的酸强度更强。利用密度泛函理论(Density functional theory,DFT)中B3LYP/6-311++G(d,p)基组对单核离子液体的阳离子[MIM(CH2)4HSO3]+与[MIM(CH2)4COOH]+、双核离子液体的阳离子(CH2)4[IM(CH2)4HSO3]22+与(CH2)4[IM(CH2)4COOH]22+、单核离子液体构型MIM(CH2)4HSO3][HSO4]与[MIM(CH2)4COOH][HSO4]、双核离子液体构型(CH2)4[IM(CH2)4HSO3]2[HSO4]2与(CH2)4[IM(CH2)4COOH]2[HSO4]2的几种可能存在构型进行了结构优化、能量计算以及频率分析,并对各稳定构型的相互作用能与电荷分布进行分析。氢键是构型稳定与否的重要因素,氢键越多且其长度越短,构型越稳定。阴离子的引入,使阳离子内氢键在键数与键能上均被削弱,阳离子功能基团上的氢原子更倾向于脱落而与阴离子HSO4-中氧原子形成新键,以更稳定的两性离子同H2SO4分子相互作用的构型存在。电荷分析发现,单、双核离子液体中的阴、阳离子功能基团的氢原子显现出了强酸性,其次咪唑环上N-C-N中碳原子上所连接H也显示出较强的酸性;双核离子液体中双咪唑环的存在强化了吸电子诱导效应,使得电子随碳链偏移咪唑环的能力增强,阳离子功能基团-HSO3以及-COOH上的电负性降低,HSO4-上电负性增强,双核离子液体酸性减弱;所得结论具有与实验中单、双核离子液体酸强度强弱顺序一致的规律。
[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.
【学位授予单位】：河北工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O645.1
[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.
【学位授予单位】：河北工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O645.1
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