【作者】 徐丹；

【导师】 邢华斌； 杨启炜；

【作者基本信息】 浙江大学 ， 制药工程， 2014， 硕士

【摘要】 离子液体在酸性物质分离、生物质转化等领域显示了良好的应用前景,离子液体的氢键碱性在上述应用中起到关键作用,但离子液体结构-碱性关系及调控机制尚未得到系统阐明。此外,现有碱性离子液体极性较强,不利于有机分子的萃取分离。为此,本文研究了离子液体的碱性调控机制,并设计合成一系列强碱、亲脂、低粘的新型长链脂肪酸离子液体。基于量子化学计算方法,从电子水平上系统研究了离子液体结构与碱性的关系。采用分子表面最小静电势和最小平均局部离子化能两个量化参数分别描述了离子液体的静电碱性和共价碱性,并用实验方法验证了计算结果的合理性。首次研究发现,随着离子液体阴阳离子间相互作用能的降低,离子液体阴离子的静电碱性和共价碱性均明显增强；此外,键合位置也显著影响同一基团的碱性强度,当基团键合在阴离子侧时其碱性显著增强。在此基础上,提出了两种增强离子液体碱性的方法：一是削弱阴阳离子间的相互作用,二是采用阴离子键合策略。通过向离子液体阴离子部分引入具有柔性结构的长链饱和或不饱和脂肪酸根(碳链长度为8-20),合成了13种新型强碱亲脂性长链脂肪酸离子液体(LCFA-ILs).并对其氢键碱性β、偶极性/可极化性π*、粘度、熔点或玻璃化温度、热分解温度等性质进行了表征,探讨了结构与性质的关系。结果显示,LCFA-ILs具有很强的氢键碱性(β1.55～1.65,60℃),是目前已报道的氢键碱性最强的离子液体。同时LCFA-ILs的偶极性/可极化性较低(π*0.76～0.86,60℃),说明有较好的亲脂性,LCFA-ILs的粘度较低(381.00～488.57cP,25℃),热分解温度高于210℃。初步考察了所合成的LCFA-ILs对代表性酸性有机分子的萃取性能。研究表明,通过改变阳离子结构,LCFA-ILs可形成离子液体-水、离子液体／稀释剂-正己烷两类两相体系,并显示了较强的有机分子萃取能力,例如其对苯酚的分配系数高达736.6,是现有离子液体的42倍。更多还原

【Abstract】 Ionic liquids (ILs) show a good application prospect in the fields of acidic materials absorption and biomass transformation. Hydrogen-bond basicity of IL plays an important role in the application mentioned above. However, the relationship of ILs’structure-basicity and mechanism of basicity regulation haven’t been revealed systematically, which limits the molecure design and development for basic ILs. In addition, basic ILs reported generally have relatively strong polarity, which is negative to extractive separation of organic molecures. For these reasons, the mechanism of basicity regulation was investigated and a novel series of long chain fatty acid ionic liquids (LCFA-ILs) with strong basicity, good lipotropy and low viscosity were synthesized in this dissertation.The relationship of ILs’cation-anion interaction and basicity systematically as well as or group-tethered position was investigated by adopting quantum chemical calculation methods at the electronic level. Two quantum-chemical parameters, the most negative surface electrostatic potential and the lowest surface average local ionization energy, were uesd as powerful tools to demonstrate the electrostatic and covalent aspects of basicity, respectively. It was found that when the cation-anion interaction engery of ILs was decreased, both of the electrostatic and covalent basicity of anion in ILs enhanced remarkly. Furthermore, when the amino group was tethered to the anion, the basicity of group was much stronger than that of the cation-tethered ILs. Hence, two ways to enhance the ILs’basicity were proposed:by weakening the cation-anion interaction and by employing the anion-tethered strategy.13kinds of novel ILs with strong basicity and good lipotropy (named LCFA-ILs) were synthesized for the first time, by introducing long chain fatty acid (carbon number:8～20) with flexible structure to anion part of ILs. And their properties, including the hydrogen-bond basicity/β, dipolarity π﹡, viscosity, melting point, glass transition temperature and thermal decomposition temperature were characterize. The results demonstrated that the LCFA-ILs achieved one of the highest β values (β=1.55～1.65,60℃) ever reported. In addition, LCFA-ILs showed a lower π*(0.76～0.86,℃), also good lipotropy, lower viscosity (381.00～488.57cP,25℃) and good thermal stability (TD>210℃). The separation performance of the LCFA-ILs synthesized was preliminarily studied in the process of extraction of representative acdic organic molecules. By cation structure changed, LCFA-ILs could form two kinds of two-phase system: ILs-water, ILs/diluent-hexane. Moreover, LCFA-ILs showed relatively strong ability to extraction of organic molecules. For instance, the distrubition coefficient of LCFA-ILs to phenol was up to736.6, which was42times of the [Omim][PF6].更多还原