有机小分子催化剂在硝基烯类化合物与醛酮的不对称Michael加成反应中的应用探究

有机小分子催化剂以其相对廉价易得、无金属参与、对环境污染小、催化活性良好的优势,受到许多化学家的关注。在醛、酮与硝基烯类的不对称Michael加成反应中也得到成功的应用。本文综述近几年来,硝基烯类化合物参与的与醛、酮不对称Michael加成反应的各类α,β-不饱和有机底物以及所用到的有机小分子催化剂。总结其优缺点,以期待能够更加广泛的催化剂被研制出来。     

以L-脯氨酸为手性源的手性离子液体的合成、表征及光学活性

以L-脯氨酸为手性源,通过还原、氨基保护、酯化等反应,合成了L-脯氨酸衍生物3,研究了反应条件对产物收率的影响。将化合物3分别与具有不同取代基的烷基咪唑反应,合成五种氨基酸衍生物为阳离子的手性离子液体4a～4e。对所合成的产物4a～4e进行了结构表征,测定了旋光度,并对其溶解性以及热稳性进行了初步探讨。     

季铵盐离子液体的合成及表征

以三乙胺和苄氯为原料,通过中间体氯化苄基三乙胺盐([Nbz222]Cl)的阴离子交换反应合成了5种目标产物:苄基三乙胺四氟硼酸盐([Nbz222]BF4),苄基三乙胺六氟磷酸盐([Nbz222]PF6),苄基三乙胺硫酸氢盐([Nbz222]HSO4),苄基三乙胺磷酸二氢盐([Nbz222]H2PO4)和苄基三乙胺咪唑盐([Nbz222]Im),产物的结构通过FTIR、1HNMR、13CNMR、ESI-MS、元素分析得以确认。除[Nbz222]PF6之外,其余4种目标产物的熔点均低于100℃。热分析表明,目标离子液体的热稳定性顺序为:[Nbz222]HSO4>[Nbz222]BF4>[Nbz222]Im>[Nbz222]H2PO4,其中[Nbz222]HSO4具有较好的热稳定性,热分解温度在260℃左右。目标离子液体均有一定的吸水性并在极性溶剂中有较好的溶解性。     

Chiral Ionic Liquid/ESI-MS Methodology as an Efficient Tool for the Study of Transformations of Supported Organocatalysts

An efficient approach to the study of deactivation pathways of chiral organocatalysts in asymmetric Michael reactions by modifying original catalysts with ionic-liquid fragments followed by the electrospray ionization mass spectrometry analysis of recovered catalyst samples has been proposed.     

手性离子液体在毛细管电泳手性分离中的应用

手性离子液体作为一种新型的绿色功能性材料,近年来深受国内外研究者的亲睐。手性离子液体因其独特的性质在色谱领域得到了成功应用,本文综述了手性离子液体在毛细管电泳手性分离领域应用的最新进展,并对今后的发展方向进行了展望。     

Influence of Small Quantities of Water on the Physical Properties of Alkylammonium Nitrate Ionic Liquids

This paper presents a comprehensive study of two alkylammonium nitrate ionic liquids. As part of this family of materials, mainly ethylammonium nitrate (EAN) and also propylammonium nitrate (PAN) have attracted a great deal of attention during the last decades due to their potential applications in many fields. Although there have been numerous publications focused on the measurement of their physical properties, a great dispersion can be observed in the results obtained for the same magnitude. One of the critical points to be taken into account in their physical characterization is their water content. Thus, the main objective of this work was to determine the degree of influence of the presence of small quantities of water in EAN and PAN on the measurement of density, viscosity, electrical conductivity, refractive index and surface tension. For this purpose, the first three properties were determined in samples of EAN and PAN with water contents below 30,000 ppm in a wide range of temperatures, between 5 and 95 °C, while the last two were obtained at 25 °C. As a result of this study, it has been concluded that the presence of water is critical in those physical properties that involve mass or charge transport processes, resulting in the finding that the absolute value of the average percentage change in both viscosity and electrical conductivity is above 40%. Meanwhile, refractive index (≤0.3%), density (≤0.5%) and surface tension (≤2%) present much less significant changes.     

Highly Efficient Amine Organocatalysts Based on Bispidine for the Asymmetric Michael Addition of Ketones to Nitroolefins

A highly diastereoselective and enantioselective Michael addition of cyclohexanone, acetone and other ketones to nitroolefins was developed by the use of an amine organocatalyst based on bispidine. Additionally, a theoretical study of transition structures revealed that this bispidine‐based primary‐secondary amine catalyst could serve through an enamine intermediate and H‐bond interaction, which was important for the reactivity and selectivity of this reaction.     

AlCl3型季铵盐离子液体的微波法合成

在微波辅助条件下,研究了氯铝酸三乙胺盐酸盐离子液体（TECIL）、氯铝酸三甲胺盐酸盐离子液体（TMCIL）的合成。此法与文献报道中离子液体合成的常规法相比,具有加热均匀、反应速度快、操作方便、产率高等特点。实验中探讨了合成这两种离子液体的反应时间、微波功率以及原料加料方式对收率的影响。通过对实验结果的比较与分析,得出微波法合成此两种离子液体的最佳工艺条件。TECIL的最佳合成工艺条件是：D方式加料,320W的微波功率,加热时间为10s＋10s＋10s×4=60s。TMCIL的最佳合成工艺条件是：D方式加料,320W的微波功率,反应时间为10s＋10s＋10s×4=60s。     

季铵盐离子液体催化苯胺选择性烷基化反应

对离子液体介质中苯胺与卤代烃的N-单烷基化反应,考察了9种不同结构的季铵盐、季鏻盐对反应的影响。结果表明,在60℃,用四丁基氯化铵作催化剂、三乙胺作缚酸剂,n(三乙胺)∶n(苯胺)∶n(卤代烃)∶n(四丁基氯化铵)=2∶1∶1∶0.05,苯胺能快速有效地与卤代烃发生N-烷基化反应,高选择性制备仲胺化合物,苯胺转化率达到86%,仲胺选择性达到87%,通过简单的乙醚萃取就可实现产物分离。季铵盐离子液体对邻位或对位有取代基的苯胺烷基化反应,也具有高的苯胺转化率和仲胺选择性,可以代替咪唑鎓盐离子液体用于苯胺选择性单烷基化反应。     

Ionic Liquids as Extracting Agents for Heavy Metals

The development of applications of ionic liquids in extraction processes stretches back to the mid-1960s when the first studies on ionic liquid- based extractions were published. Since then, the interest of both academics and the industrial community on the development of ionic liquids-based technologies is continuously growing. The main driving force of ionic liquid engineering is to combine their “environmentally friendly” properties (e.g., extremely low vapor pressure) and their unique reactivity and miscibility behavior in order to improve the current “state of the art” technologies. The focus of this review is on the application of ionic liquid in heavy metal extraction processes. The critical aspects of their journey from academic curiosity towards industrial application are highlighted.     

季铵盐型离子液体合成与应用的研究进展

总结了离子液体的通用合成方法,归纳了季铵盐型离子液体在Friedel-Crafts烷基化反应、Heck反应、酯化反应和电化学及萃取等领域的应用。     

离子液体与重组工程菌的生物相容性研究及在手性合成中的应用

对不同阳离子的亲水性及疏水性离子液体的糖代谢能力及细胞膜通透性研究发现,季胺型阳离子[N2,2,2,2]+具有较好的生物相容性,咪唑类离子液体生物相容性最差。基于离子液体介质生物催化不对称还原反应可知,季铵盐离子液体较咪唑、吡啶、吗啉等离子液体具有更高的催化效率。     

离子液体中酵母细胞催化的不对称还原反应

以咪唑类离子液体/水两相为反应体系,考察了咪唑类离子液体的不同咪唑环取代烷基链、离子液体与水相的体积比、反应温度、摇床转速和水相pH对酵母Candida Pseudotropicalis催化还原2'-氯-苯乙酮制备S-2'-氯-苯乙醇反应的影响。结果表明,随着离子液体咪唑环上取代烷基的增大,S-2'-氯-苯乙醇的收率呈下降趋势。以1-己基-3-甲基咪唑六氟磷酸盐/水两相为反应体系,在2'-氯-苯乙酮初始浓度为3 g/L,辅助底物葡萄糖浓度为50 g/L的条件下,较合适的反应条件为离子液体与水的体积比1:50,水相pH值6.8,反应温度30℃,摇床转速200 r/min,反应24 h,产物S-2'-氯-苯乙醇产率可达85.9%,ee值大于99.9%。酵母细胞催化剂的重复使用实验表明,随着使用次数增加,离子液体/水两相体系中酵母细胞的催化作用明显下降。     

Asymmetric Thioethers as Building Blocks for Chiral Monolayers

There is a growing interest in chirality at surfaces from both a fundamental and an enantioselective reactions/separations viewpoint. We report on the homochiral self-assembly of asymmetric thioethers that become chiral upon binding to a surface. We focus on the adsorption of butyl methyl sulfide and a fluorinated analogue on Au(111) surfaces.     

SO3H-功能化季铵盐离子液体催化酯交换制备生物柴油

采用两步合成法制备了4种SO3H-功能化季铵盐离子液体,红外与核磁共振光谱表征结果表明,其结构符合理论结构特点. 热稳定性分析表明,其分解温度都在200℃以上,均可作为制备生物柴油的催化剂. 将这4种离子液体用于催化制备生物柴油,其催化活性主要与其阴离子的结构有关,[n-But3N(CH2)3SO3H][CH3SO3]的催化活性最好. 甲醇:三油酸甘油酯摩尔比为12:1、催化剂用量7%(w)、在65℃下反应24 h时,油酸甲酯产率最高(89.65%). 催化剂重复使用性能良好.     

N-硝基苯基脯氨酰胺小分子催化剂的合成及其在环己酮与硝基烯烃不对称Michael加成中的应用

以苄氧羰基保护的L-脯氨酸和硝基苯胺类化合物为起始原料,通过酰胺化反应和脱苄氧羰基反应,合成了两个结构新颖的N-硝基苯基脯氨酰胺类催化剂,其结构经~~1HNMR、~(13)CNMR和HR-ESI-MS确证。该类催化剂用于环己酮与硝基烯烃的不对称Michael加成反应,其中化合物(S)-N-(2-甲氧基-4-硝基苯基)脯氨酰胺催化所得产物具有优异的收率(82%)、较高的非对映体比例(94∶6 dr)和一定的对映选择性(21%e.e.)。     

Recycling Chiral Imidazolidin‐4‐one Catalyst for Asymmetric Diels–Alder Reactions: Screening of Various Ionic Liquids

Various imidazolium ionic liquids such as [Bmim]PF₆, [Bmim]SbF₆, [Bmim]OTf and [Bmim]BF₄ were screened for recycling an organic catalyst [(5S)‐5‐benzyl‐2,2,3‐trimethylimidazolidin‐4‐one ( 1 )] for asymmetric Diels–Alder reactions. Good yields and enantioselectivies (up to 85% yield and 93% ee) were obtained from reactions in [Bmim]PF₆ or [Bmim]SbF₆. However, reactions in [Bmim]OTf or [Bmim]BF₄ gave racemic products in low yields. Isolation of the products by simple extraction using diethyl ether allowed recycling of the ionic liquid containing the immobilized catalyst in subsequent reactions without significant decrease of yields and enantioselectivities.