液液萃取作为一种重要的化工分离单元操作，广泛应用于多种体系中各组分的分离。近年来，随着绿色化工的兴起，选择可替代有机溶剂的绿色溶剂成为液液萃取的热点。离子液体作为一种结构可调的绿色溶剂越来越多地应用于萃取分离中。本论文针对C2/C4路线合成甲基丙烯酸甲酯（MMA）中甲基丙烯酸（MAA）/丙酸（PA）/乙酸（HAc）/乙酸乙酯（EA）/水（H2O）等混合体系的分离问题，设计了系列新型离子液体萃取剂用于MAA-H2O、MAA-HAc、PA-HAc和EA-H2O的分离。实验测定了离子液体萃取过程的基础数据，结合实验表征和量化计算，对离子液体萃取过程的微观机理进行了初步解析，以期对离子液体萃取剂的设计和应用提供参考和指导。本论文的主要研究内容和成果如下：（1）设计和合成了咪唑类和季铵盐离子液体作为萃取剂来回收低浓度水溶液中的MAA。考察了离子液体结构对MAA萃取的影响，发现阴离子对MAA萃取具有较大影响，萃取分配系数按如下顺序递减[BF4]－ > [NTf2]－ > [PF6]－。溶剂化显色研究表明，离子液体萃取MAA的分配系数与其氢键碱性值正相关。通过红外光谱和量化计算等方法对离子液体萃取MAA的主要影响因素及内在机理进行了分析，结果表明离子液体和MAA之间的氢键作用对酸的萃取起主要作用，并且以离子液体阴离子和MAA之间的氢键作用为主导。基于此，设计合成了具有强氢键碱性的[N8,8,8,1]Cl用以萃取回收水溶液中的MAA，分配系数达到了42.15，是常规工业溶剂正己烷的49倍。（2）设计了羧基功能化季铵盐类离子液体三辛基甲基丁二酸铵（[A336]Suc）、三辛基甲基天门冬氨酸铵（[A336]Asp）、三辛基甲基谷氨酸铵（[A336]Glu）、三辛基甲基三氟乙酸铵（[A336]TFA）和三辛基甲基邻苯二甲酸铵（[A336]Pha）用于MAA和HAc的选择性分离。阴离子上的羧基官能团使得离子液体具有较强的氢键碱性，其中[A336]Suc的氢键碱性最强，萃取得到MAA对HAc的选择性系数达到54.70，是三辛铵萃取剂的2倍。红外分析表明[A336]Suc与MAA或HAc之间形成了氢键作用。进一步通过量化计算对离子液体与羧酸之间的相互作用进行分析，结果表明，[A336]Suc与MAA之间强的氢键作用是选择性分离MAA和HAc的关键。（3）低粘度离子液体设计及选择性萃取分离PA-HAc混合物。针对离子液体高粘度的问题，设计了低粘度的三辛基甲基丙二酸铵（[A336]Mal）、三己基十四烷基丙二酸膦（[P6,6,6,14]Mal）和三己基十四烷基顺丁烯二酸膦（[P6,6,6,14]Male）离子液体用于水溶液中PA和HAc的萃取分离。由于[Male]－阴离子的内氢键作用削弱了阴阳离子之间和离子液体-离子液体之间的相互作用，使得[P6,6,6,14]Male离子液体的粘度最低，303.15K的粘度为292.82mPa·s，相较于[A336]Suc降低了75.89%。将[P6,6,6,14]Male应用于PA和HAc的选择性分离中，选择性系数为10.09，优于传统有机溶剂磷酸三丁酯。（4）亲水性离子液体设计及对EA-H2O体系的萃取分离。EA-H2O二元共沸物的存在导致EA-H2O混合物的脱水较为困难，利用亲水性离子液体作为萃取剂可以较好的将EA中的水分脱除掉。在设计的亲水性离子液体中，1-乙基-3-甲基咪唑醋酸盐（[C2mim]OAc）具有最好的脱除EA中水的能力，其萃取分离水的分配系数达到711.26，选择性系数达到26444.81，3级萃取后EA水含量可由2.75wt%降至0.0084wt%。通过量化计算发现[C2mim]OAc和水之间存在强的氢键作用，使得[C2mim]OAc-H2O之间的作用能大于EA-H2O以及[C2mim]OAc-EA之间的作用能，说明氢键作用是离子液体选择性分离EA中水的主要原因。 ;Liquid-liquid extraction is an important separation unit operation of chemical engineering. Nowadays, with the development of green chemical engineering, there is growing attention to search green solvents to replace the organic solvents for liquid-liquid extractions. Ionic liquids (ILs) as tunable green solvents are increasingly used in the extraction processes. The C2/C4 routes for methyl methacrylate (MAA) synthesis contain several typical separation systems, such as methacrylic acid (MAA)-water (H2O), MAA-acetic acid (HAc), propionic acid (PA)-HAc, ethyl acetate (EA)-H2O. In this work, a series of novel ILs were designed and synthesized to separate MAA-H2O, MAA-HAc, PA-HAc and EA-H2O systems. The basic data of the ILs extraction processes were obtained by experiments. Then the molecular mechanisms of the ILs extraction processes were revealed by combining experimental characterization analyses with quantum chemical calculations. The results are expected to provide the guidance for the molecular design and application of ILs as extractants. The main contents and the results of the dissertation are as follows:Firstly, the imidazolium-based ILs and quaternary ammonium salt ILs were designed and synthesized to recover MAA from dilute aqueous solution. The effects of the IL’s structure on the MAA extraction were evaluated. The results showed that the anion of IL has the higher effect on the extraction of MAA than the cation and the effect of the anion followed as [BF4]－ > [NTf2]－ > [PF6]－. In addition, the solvatochromic study showed that the partition coefficients of MAA are positive correlation with the hydrogen bond basicity of ILs. Moreover, the FT-IR and quantum chemical calculation results indicated the important role of hydrogen bond between IL and MAA, and the hydrogen bond between anion and MAA has the dominant position. Then, [N8,8,8,1]Cl with strong hydrogen bond basicity was used to extract MAA form dilute aqueous solution. At the optimal extraction conditions, the partition coefficient of MAA for [N8,8,8,1]Cl achieves 42.15, which is 49 times higher than the industrial solvent of hexane.Secondly, the carboxyl-functionalized quaternary ammonium ILs tricaprylmethylammonium succinate ([A336]Suc), tricaprylmethylammonium aspartate ([A336]Asp), tricaprylmethylammonium glutamate ([A336]Glu), tricaprylmethylammonium trifluoroacetate ([A336]TFA) and tricaprylmethylammonium phthalate ([A336]Pha) with strong hydrophobicity were designed and synthesized to separate MAA and HAc from an aqueous solution. The [A336]-based ILs has strong hydrogen bond basicity due to the carboxylate group in anion of ILs. [A336]Suc has shown the better extraction performance than the other ILs because of the stronger hydrogen bond basicity. Thus, [A336]Suc was selected as extractant to separate MAA and HAc. The selectivity of MAA to HAc achieves 54.70 at the optimized extraction conditions, which is two times higher than trioctylamine. The hydrogen bonding interaction was detected by FT-IR analysis. Moreover, the quantum chemical calculation was employed to analyze the interaction between [A336]Suc and MAA/HAc. The computational studies demonstrated that the stronger hydrogen bonding interaction between carboxylate group of [A336]Suc and MAA than HAc is the key of the selective separation of MAA and HAc.Third, low viscosity ILs for the selective separation of PA-HAc were designed and prepared. Three kinds of low viscosity ILs, tricaprylmethylammonium malonate ([A336]Mal), trihexyltetradecylphosphonium malonate ([P6,6,6,14]Mal) and trihexyltetradecylphosphonium maleate ([P6,6,6,14]Male) were used to separate PA and HAc from an aqueous solution. [P6,6,6,14]Male exhibited lower viscosity than the other ILs due to the weak interaction between cation and anion as well as the weak intermolecular interaction of IL. The viscosity of [P6,6,6,14]Male at 303.15K is 292.82mPa·s, which is 75.89% lower than [A336]Suc. Then [P6,6,6,14]Male was used to selective separate PA and HAc. The selectivity of PA to HAc achieves 10.09, which is higher than tributyl phosphate.Fourth, hydrophilic ILs for the separation of EA-H2O mixture were designed and prepared. The dehydration of EA-H2O mixtures is difficult due to the form EA-H2O binary azeotrope. H2O can be easily removed by hydrophilic ILs through liquid-liquid extraction. Among the ILs, 1-ethyl-3-methyl-imidazolium acetate ([C2mim]OAc) showed best extraction performance for the separation of EA-H2O mixtures. The partition coefficient of H2O is obtained 711.26 and selectivity of H2O to EA achieves 26444.81. After three stages extraction, the water content in EA is reduced to 0.0084wt%. Moreover, the quantum chemical calculation showed that the strong hydrogen bond is formed between [C2mim]OAc and H2O, which makes the stronger interaction than [C2mim]OAc with EA and H2O with EA. The results indicated the important role of hydrogen bond for the separation of EA-H2O mixtures.