共查询到18条相似文献,搜索用时 93 毫秒
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研究目的:帮助学立体化学的同学更好地理解与掌握分子手性相关的知识点,其中包括分子手性判断的方法。研究方法:查阅用过的教材,深入理解分子的手性性质,同时结合一些熟悉的物质来理解分子的结构及其对称性。研究结果:通过仔细的研究,容易发现其中存在许多有规律的知识,最后将其归纳总结。研究结论:饱和碳原子可以通过4个共价键与4个原子或基团相连,当相连的原子或基团不同,它会形成两种分子结构。除了旋光方向相反之外,这两种分子拥有完全一样的物理性质和化学性质。二者就像左手和右手那样,互为对应。立体化学将这种结构上镜像对称而又不能完全重合的分子称为手性分子。这两种分子互为同分异构体,这种异构的形式称为手性异构,有R型和S型两类。 相似文献
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文章介绍了几种纤维素类手性拆分剂以及其制备方法相关分离机理,综述了纤维素手性拆分剂的分离机理及其应用,重点地介绍纤维素手性固定相和纤维素膜的应用。 相似文献
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手性离子液体同时具有离子液体和手性物质的特点。它可以作为手性溶剂或手性诱导剂,在手性合成、手性分离、手性催化等诸多方面具有很大的发展空间。本文解决了传统手性试剂合成困难、价格昂贵的问题,以天然氨基酸为手性源合成了新的手性离子液体,对手性离子液体的发展具有重要意义。 相似文献
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综述了基于芯片电泳技术的手性分离进展。分别介绍了这一领域的进样、检测技术,所采用的手性选择剂,芯片制作材料及用于提高分离度的方法等,展望了手性分离在芯片电泳领域今后的发展方向。 相似文献
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以手性多糖中的β-环糊精为原料,将其与异氰酸酯反应,合成β-环糊精类衍生物,用红外光谱和核磁共振氢谱和碳谱对β-环糊精类衍生物的分子结构与糖单元取代度进行表征与分析。结果表明,β-环糊精衍生物对于某个对映体显示出手性拆分能力。 相似文献
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本文通过紫外、红外和圆二色(CD)光谱表征考察了外在离心力场对非手性化合物异佛尔酮不对称氧化生成光学活性产物的影响。结果表明离心力场能够诱导产物的对映体过量,在顺时针和逆时针旋转力场中得到的产物CD230信号相反并随转速的增大而增大。作者推测,顺时针和逆时针圆周离心运动(轴矢量)结合地球在时空上的天然线性运动(极矢量)形成的左、右手螺旋运动的不对称作用可能是诱导反应对映体过量的力学原因。 相似文献
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《国家科学评论(英文版)》2015,(2)
The expression of chirality in 2D molecular assemblies on solid surfaces has unique features compared to the analogous process in 1D and 3D supramolecular assemblies. Understanding the formation of chiral molecular assemblies on surfaces not only provides insight into the origin and transfer of chirality in many enantioselective processes, but also aids rational design and construction of chiral architectures and materials. his present contribution reviews recent studies on how chirality is induced and expressed on the surface at diferent levels, both from intrinsically chiral and achiral molecules. Furthermore, we discuss the regulation efect of some pivotal factors, for example, the chemical structure, the chiral auxiliary molecules,and the assembled environments, on the expression of chirality in molecular assembly. 相似文献
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Roger A. Grey Author Vitae 《Journal of The Franklin Institute》2006,343(3):214-222
The scientific theme for the 2005 Bower Award was Chemistry, specifically the field of Catalysis. The Franklin Institute, Philadelphia, Pennsylvania, awarded the 2005 Bower Award and Prize for achievement in Science to Henri B. Kagan for his seminal discovery of fundamental chemical principles that explain the impact of catalyst shape on its effectiveness in controlling chemical reactions, thus greatly simplifying the manufacture of pharmaceutically important compounds. Henri Kagan is widely recognized as a pioneer in the field of asymmetric catalysis. Starting in the early 1970s, his reports of the synthesis of the chiral bidentate diphosphine ligand and the demonstration of its use with soluble rhodium compounds to catalyze the efficient production of large enantiomeric excesses of chiral molecules in asymmetric hydrogenations has had far reaching effects on research in the field asymmetric catalysis. The concept of using chiral bidentate ligands of C2 symmetry has led the way for numerous developments in asymmetric catalysis. Later in 1986 his introduction of the concept and investigations into “nonlinear effects in asymmetric synthesis” using catalysts with chiral ligands that were not optically pure challenged the widely accepted assumption that the enantiomeric excess which is possible correlates linearly with the optical purity of the chiral ligands. He reported the first example in asymmetric catalysis where the optical purity of the product significantly exceeded the optical purity of the chiral ligand. 相似文献
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主要研究了硫、碲叶立德环丙烷化和环氧化反应的立体化学控制。通过添加剂、手性辅基、手性试剂等 3种策略,分别控制反应的非对映选择性和对映选择性。对烯丙基硫叶立德的不对称环氧化反应也进行了初步研究 相似文献
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运用螺旋理论推断秋水仙碱的构型 总被引:1,自引:0,他引:1
秋水仙碱是医治癌症的重要药物 ,其结构中不仅存在手性碳原子的构型问题 ,也存在类似于联苯衍生物的构型和构象问题 .确定了手性碳原子的构型 ,还必须确定两个芳环间的构型和构象 .运用笔者提出的螺旋理论 ,通过其旋光方向和旋光度可以方便地确定秋水仙碱两个芳环间的构型和构象 . 相似文献
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尹玉英 《中国科学院研究生院学报》1999,(2)
论文作者在合成思路和技巧方面有独到之处,具有一定价值.但在探讨旋光性与结构关系的思路和逻辑上有较多问题.有关螺旋结构和光学活性关系的分析,任意性太大.从该文得不出所述的5 条结论.5 条结论中存在不确切、不全面甚至错误 相似文献
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Since organic solid state reactions must take place within the organised medium of the crystal lattice, their course and outcome can often be controlled and exploited. Although their major application is not in the area of organic synthesis, they are far from being academic curiosities. They have been involved in situations as diverse as observing the approach of reacting molecules, determining the absolute configurations of chiral molecules, and establishing crystallisation patterns for organic solids. 相似文献