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手性选择剂对氨基酸的包合作用及其用于固膜拆分的研究

Inclusion Phenomena between Chiral Selectors and Amino Acids and the Use on Chiral Solid Membranes

【作者】 李苏敏

【导师】 孟洪;

【作者基本信息】 北京化工大学 , 化学工程与技术, 2012, 硕士

【摘要】 手性物质的拆分在现在化工、生物领域有很重要的意义,高效低耗能的拆分方法是目前研究的热点。固膜手性拆分法与传统拆分方法相比,有很多优点:效性高、能耗低、便于连续操作等,已经成为极具发展潜力的方法。固膜拆分过程主要是根据膜上所接选择剂的手性基团对所拆分的两种对映体的选择性差距来实现,推动力包括压力、浓度或电势差等。手性选择剂的选择是关键技术之一。本实验旨在研究新型手性选择剂和固膜制备方法。本实验对β-环糊精(β-CD)进行改性,制备了β-环糊精类手性离子液体(β-CD-IL)单-6-脱氧基-6-(3-甲基咪唑)β-环糊精对甲苯磺酸盐作为手性选择剂。实验通过紫外分光光度法考察了β-CD以及β-CD-IL与氨基酸包合反应的包合比例和包合常数,得到酪氨酸与β-CD及β-CD-IL包合反应的比例为1:1,β-CD与D-酪氨酸的包合常数为214.42,β-CD与L-酪氨酸的包合常数为的220.40。色氨酸与β-CD的包合反应比例不确定。实验中用研磨法制备了β-CD类手性选择剂与氨基酸的包合物,通过XRD、FT-IR、NMR等手段检测了包合物的性状,证明包合物生成。用饱和溶液法研究了色氨酸与β-CD类手性选择剂的包合反应,得到了分离因子,两种手性选择剂对色氨酸均有手性识别能力,随着β-CD类手性选择剂浓度的增加,分离因子呈现增大的趋势。β-CD与D,L-色氨酸包合反应比例为5:1时分离因子可达1.402,β-CD-IL与D,L-色氨酸包合反应比例为20:1时分离因子可达1.558。在固膜拆分实验中,本实验分别选用PAN膜与N6膜为基膜,β-CD-IL与壳聚糖(CS)为手性选择剂,通过调节手性选择剂的浓度和比例制备了不同种类和层数的手性拆分固膜,通过红外光谱、扫描电镜的表征证明手性选择剂接在固膜上。用制备的固膜对D,L-色氨酸进行了拆分和吸附实验。以PAN膜为基膜的手性固膜得到的拆分因子最大为1.12,膜渗透通量随着时间的进行有所减少。以N6膜为基膜的手性拆分实验中,一层CS(1g)膜的拆分因子最大,为1.18。固膜对色氨酸的吸附量随着手性选择剂浓度的增大而增大,最大达到105.53mg/g膜。

【Abstract】 The separation of chiral compounds is very important for the chemicaland biological field, meanwhile, the method that shows high efficiencyand low energy consumption is the main point in current research. Thesolid membrane separation process, as a tremendous potential method,has some advantages including high efficiency, low energy consumptionand convenient continuous operation, compared with the traditionalmethods. The process is based on the selective difference of chiral groupof selector immobilized on membrane for the two isomers needed to beseparated, and the driving force of separation contains pressure,concentration and potential difference. Obviously, the selection of chiralselector is very crucial for the process mentioned above. Thus, the aim ofthis work is to explore some noval chiral selectors and preparationmethods of solid membrane.The mono-6-deoxy-6-(3-methylimidazolium)-β-cyclodextrin tosylate(β-CD-IL), a chiral selector, was synthesized by the modification ofβ-cyclodextrin (β-CD) in this work. The Inclusion phenomena of β-CD and β-CD-IL with different amino acids were investigated, and theinclusion ratio and inclusion constant were obtained by UVspectrophotometry method. The inclusion ratio between β-CD andD,L-Tyr was1:1, while the inclusion constant between β-CD and D-Tyror L-Tyr was214.42or220.40. The inclusion ratio between β-CD andD,L-Trp was still unknown.The inclusion compounds between β-CD chiral selectors with aminoacids were prepared using grinding method. The inclusion compoundsprepared were characterized by XRD, FT-IR and NMR, which verifiestheir formation. The saturated solution method was used to investigate theinclusion phenomena between Trp and β-CD based selectors (β-CD andβ-CD-IL), giving the split factor. It was evident that the two selectors hadchiral recognition ability for the enantiomers. Further, the split factorsincreased with the chiral agents concentration increasing. When thereactant ratio of β-CD and D,L-Trp was5:1, the split factor mounted to1.402, while the reactant ratio of β-CD-IL and D,L-Trp was20:1, the splitfactor reached1.558.In the solid membrane separation process, moreover, the PANmembrane and N6membrane were used as the basement membranes,while the β-CD-IL and CS were deemed as the chiral selectors. And aseries of the chiral solid membranes were prepared by immobilizingdifferent chrial selectors on different porous support bodies. The solid membranes prepared showed different species and layers by controlingdifferent concentration and proportion. The resulted membrane werecharacterized by FT-IR and SEM to verify the fact that the chiralcompounds were immobilized on the membranes. The membranesobtained were used to separate and adsorb tryptophan (D,L-Trp) racemate.The s highest split factor using PAN basement membranes was1.12, thepermeate flux reduced with the time proceeding. The highest split factorof N6membranes was1.18. The adsorption capacity of solid membranefor tryptophan increased with growing concentraction of the chiral agents.The maximum adsorption capacity mounted to105.53mg/g membrane.

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