基于β-环糊精非均相仿酶的构筑及其应用研究

发布时间：2019-06-22 12:59

【摘要】：β-环糊精具有“内腔疏水,外壁亲水”的特殊结构和性质,且廉价易得可再生。根据其丰富的羟基官能团可进一步修饰的特点,可将修饰后的β-环糊精固载到活性载体上,应用于催化苯甲硫醚的不对称氧化反应。首先将FeCl3·6H2O和FeCl2·4H2O在碱性条件下结合制备Fe3O4纳米粒子,再利用3-氯丙基三乙氧基硅烷和正硅酸乙酯与Fe3O4纳米粒子结合制备核-壳结构的活性载体Si@Fe3O4载体。为了考察该载体固载β-环糊精的活性,实验采用乙二胺为连接基团将β-环糊精母体固载到Si@Fe3O4载体上,并利用其吸附水溶液中的p-硝基苯酚的性能来考察其相关性质。通过FT-IR、XPS、XRD、TGA、SEM、TEM、水接触角,表征分析证明载体的制备与环糊精的固载已成功。在对p-硝基苯酚的吸附试验中,考察了溶液pH值、吸附时间和吸附温度对吸附量的影响。研究表明该吸附剂对p-硝基苯酚的吸附在15 s内既能达到吸附平衡,且pH值为7.0时,饱和吸附量达到84.2 mg/g。证明该Si@Fe3O4载体性质优良。以此为基础,再借助实验室之前研究过的Cl@Si载体为环糊精的第二个载体,实现了环糊精的非均相化。实验首先采用乙醇胺和丙醇胺为修饰基团合成了6-乙醇胺-β-环糊精和6-丙醇胺-β-环糊精,再以1-氯-3-碘-丙烷为连接基团,分别将这两种β-环糊精衍生物成功固载到前两种载体上,再将其与Na2MoO4络合,成功构筑了β-环糊精非均相仿生催化剂。通过FT-IR、XPS、XRD、TGA、SEM、TEM、水接触角,表征分析证明该非均相仿生催化剂配体的制备已成功。并考察了该仿生催化剂对苯甲硫醚不对称氧化反应的调控性能。研究表明,载体的引入并未影响环糊精衍生物对苯甲硫醚不对称氧化反应的调控,底物转化率高达100.0%,产物收率也高达83.4%,ee%值最高达到55.3%。实验不仅使用了绿色环保的溶剂代替有机溶剂,而且催化剂可回收再利用,符合“绿色化学”理念。在筛选催化活性中心的过程中,我们发现质子酸是一类性质优良的催化剂。为了进一步研究质子酸对苯甲硫醚氧化反应的催化性能及其原理,我们系统性的探究了一系列质子酸催化H2O2氧化硫化物的催化性能,并揭露了其中共性问题。研究表明,对于所有的质子酸,其催化活性均与反应体系的pH值有关,只要反应体系的p H值达到1.30左右,所有的质子酸催化剂均可以使反应转化率和收率达到98.0%以上。我们首次提出在质子酸催化氧化硫化物的体系中,其催化活性是由反应体系的pH值所决定。
[Abstract]:尾-cyclodextrin has the special structure and properties of "inner cavity hydrophobic and outer wall hydrophilicity", and it is cheap and easy to regenerate. According to the rich hydroxyl functional groups which can be further modified, the modified 尾-cyclodextrin can be loaded on the active carrier and applied to the asymmetric oxidation of benzothioether. Firstly, FeCl3 路6H2O and FeCl2 路4H2O were combined to prepare Fe3O4 nanoparticles under alkaline conditions, and then the active carrier Si@Fe3O4 carrier with core-shell structure was prepared by the combination of 3-chloropropyl triethoxysilane and tetraethyl orthosilicate with Fe3O4 nanoparticles. In order to investigate the activity of 尾-cyclodextrin supported by the carrier, the matrix of 尾-cyclodextrin was loaded on Si@Fe3O4 carrier with ethylenediamine as the connecting group, and its related properties were investigated by using its adsorption properties of p-nitrophenol in aqueous solution. The preparation of the carrier and the loading of cyclodextrin were proved to be successful by FT-IR,XPS,XRD,TGA,SEM,TEM, water contact angle. In the adsorption test of p-nitrophenol, the effects of pH value, adsorption time and adsorption temperature on the adsorption capacity were investigated. The results show that the adsorption of p-nitrophenol by the adsorbents can reach the adsorption equilibrium in 15 s, and the saturated adsorption capacity reaches 84.2 mg/g. when the pH value is 7.0. It is proved that the Si@Fe3O4 carrier has excellent properties. On this basis, the heterogeneity of cyclodextrin was realized by using the Cl@Si carrier previously studied in the laboratory as the second carrier of cyclodextrin. In this experiment, 6-ethanolamine-尾-cyclodextrin and 6-propanolamine-尾-cyclodextrin were synthesized by using ethanolamine and propanolamine as modified groups, and then the 尾-cyclodextrin derivatives were successfully supported on the first two supports with 1-chloro-3-iodine-propane as the connecting group, and then the 尾-cyclodextrin heterogeneous bionic catalysts were successfully constructed by complexing them with Na2MoO4. The preparation of the heterogeneous bionic catalyst ligand was successfully prepared by FT-IR,XPS,XRD,TGA,SEM,TEM, water contact angle. The regulation performance of the biomimetic catalyst for asymmetric oxidation of benzothioether was investigated. The results showed that the introduction of the carrier did not affect the regulation of cyclodextrin derivatives on the asymmetric oxidation of benzothioether. The conversion of substrate was as high as 100.0%, the yield of the product was 83.4%, and the highest ee% value was 55.3%. The experiment not only uses green environmental protection solvent instead of organic solvent, but also the catalyst can be recycled and reused, which accords with the concept of "green chemistry". In the process of screening catalytic active sites, we found that protonic acid is a kind of catalyst with excellent properties. In order to further study the catalytic performance and principle of proton acid for the oxidation of benzothioether, we systematically investigated the catalytic performance of a series of protonic acids for the oxidation of sulfides by H2O2, and revealed the common problems. The results show that for all proton acids, the catalytic activity is related to the pH value of the reaction system. As long as the pH value of the reaction system is about 1.30, all protonic acid catalysts can make the conversion and yield of the reaction reach more than 98.0%. We propose for the first time that the catalytic activity of sulfides catalyzed by protonic acid is determined by the pH value of the reaction system.
【学位授予单位】：浙江工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O636.12;O643.36

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