基于离子液体电解液的有机电化学反应

室温离子液体(RTILs) 作为一类在室温时呈液态且具有良好导电性的新型绿色溶剂, 在有机电化学反应体系中的应用前景广阔。本文介绍了近年报道过的新型离子液体及离子液体电解液的特性,阐述了基于离子液体电解液的电化学实验方法,重点综述了离子液体中的各种有机电化学反应,包括电化学还原反应、CO₂在离子液体中的电化学固定、电化学氧化反应、烯烃的环氧化、选择性氟化反应、偶联反应、功能化有机硅氧烷的合成、电化学氟化脱硫反应、电化学聚合反应等,并展望了发展趋势。     

微波辅助离子液体合成法在亲核氟化中的应用

采用微波辅助合成法快捷、高效地制备了系列咪唑类和吡啶类离子液体,并对其在亲核氟化中的应用进行了研究.结果表明,N-苄基吡啶四氟硼酸盐([bepy]BF4)是一种稳定性高、使用效果好的离子液体.在微波作用下,以N-苄基吡啶四氟硼酸盐和乙腈为共溶剂,以氟化铯为氟化试剂,高效合成了系列含氟化合物.在优化反应条件下,其收率为54.1%～76.3%,反应时间较常规油浴加热最好时可缩短50%以上.     

三乙胺三(氟化氢)在有机合成中的应用

氟化反应在有机合成中有着广泛的应用, 三乙胺三(氟化氢)作为氟化试剂有着其它氟化试剂所无法比拟的优越性. 对近年来三乙胺三(氟化氢)在有机合成中的应用进行了总结和概述, 重点介绍了亲核取代、环氧开环反应、亲电加成反应和脱硅保护基等反应.     

离子液体在生物柴油合成中的应用进展

介绍了合成生物柴油常用的酯交换方法以及离子液体的定义、结构、性质和制备方法, 简单描述了酸性离子液体作为催化剂在酯化反应中的应用, 综述了离子液体在生物柴油合成中的应用进展并展望了其应用前景.     

亲核性氟源在碳碳不饱和键选择性氟化官能化反应中的应用

含氟化合物表现出的特殊理化和生物活性使得其在药物、农用化学品和材料科学等领域有着广泛而重要的应用,因此,含氟化合物的高效制备不仅成为了合成化学的研究热点之一,而且极大地推动了相关领域的蓬勃发展.其中,在有机分子内直接引入氟原子的方法主要有亲电氟化和亲核氟化.相较于亲电氟化,亲核氟化反应所用的氟化试剂通常廉价易得,所需的反应条件也比较温和.作者课题组借助过渡金属催化、可见光氧化还原催化和可见光促进策略,拓展了亲核性氟源在碳碳不饱和键选择性氟化官能化反应中的应用,合成了一系列结构新颖的含氟化合物.在该研究评论中将对此做出小结,并对该领域值得关注的研究方向进行简要的展望.     

离子液体微乳液研究进展

离子液体参与构筑的微乳液体系兼顾了离子液体和微乳液的优点,如热稳定范围宽、增溶能力强、结构/性质可调控等.根据离子液体的结构特点,它可以替代经典微乳液中的任意一个组分形成离子液体微乳液,并在材料制备、酶活性和生物催化、药物增溶与传输等领域展示了良好的应用前景.本文系统地总结了离子液体替代经典微乳液中的一个组分、两个组分和三个组分所形成的离子液体微乳液,综述了这类体系的结构、性质、应用等方面的研究进展,并对其未来发展趋势和需要解决的主要问题进行了分析讨论.     

离子液体在羰基化反应中的应用

离子液体由于具有良好的溶解能力、配位能力、热及化学稳定性、结构及性质可调、环境友好等特点,被认为是传统非环保型、有毒、污染严重的溶剂和催化剂潜在的替代品,已被广泛应用于有机合成及催化领域。本文综述了近年来离子液体在羰基化反应中的应用及催化反应机理研究进展,包括烯烃、醇类化合物、芳烃、胺/胺醇、卤代芳烃及甲醛的羰基化反应,羰基源主要包括CO、CO₂和碳酸二甲酯,涉及到了酸性离子液体、碱性离子液体、金属类离子液体、负载型离子液体等多种类型的功能化及非功能化离子液体。在上述反应中离子液体不仅可以提高反应活性和选择性,而且简化了催化剂分离过程,在部分反应中实现了回收和循环使用。并对羰基化反应的发展及应用前景进行了展望。     

环境友好型离子液体催化环氧丙烷反应合成丙二醇醚

丙二醇醚类化合物是性能优良的精细化学品,也是环保型高级溶剂.该类化合物具有两个强溶解性功能基团—醚键和羟基,前者具有亲油性,可溶解疏水性物质,后者具有亲水性,可溶解亲水性物质,因而丙二醇醚具有很强的溶解能力,素有"万能溶剂"之称,可广泛应用于涂料、油墨、油漆、印刷、电子化学品、染料、净洗和纺织等行业.丙二醇醚类化合物目前主要由环氧丙烷和低级脂肪醇反应合成,然而,由于环氧丙烷的位阻效应,使其在酸或碱的条件下开环的位置会不同,从而得到不同的醇醚产物.由于碱催化的醇醚产物更加环境友好,因而越来越被人们所关注.工业上丙二醇醚合成多采用传统的强碱性催化剂醇钠以及氢氧化钠,腐蚀性强,产生的废液量大.本文采用环境友好的非卤素离子液体作为催化剂,研究了其催化环氧丙烷醚化合成丙二醇醚的反应特性.本文采用两步法合成了一系列环境友好的醋酸类碱性功能化离子液体,并在温和的条件下将其用于催化环氧丙烷与醇反应合成丙二醇醚.结果表明,该类离子液体可以高效催化该反应的进行.利用紫外-可见光谱测定Hammett指数来表征实验中所用离子液体的碱强度,并构建了离子液体碱性与催化活性之间的关系.结果表明,离子液体的催化性能和其碱性密切相关,随着离子液体碱性的增加,催化活性增强,其中咪唑醋酸类离子液体碱性强于季胺类,表现出优异的催化性能.离子液体的碱性明显弱于NaOH,但却呈现出更优异的催化性能.相同反应条件下,EmimOAc离子液体作为催化剂,PO的转化率分别较NaOH高出20%–30%,选择性略高于NaOH,这可能是由于二者催化机理不同造成的.传统NaOH催化机理的关键步骤是醇在碱性催化剂的作用下去质子化形成电子供体烷氧根离子,促进环氧丙烷的开环加成.而本文提出了离子液体亲电亲核双活化作用机理,即离子液体在阴阳离子之间的氢键和电荷相互作用的共同作用下,促进环氧丙烷开环和醇的去质子化,形成相应的反应中间体.通过电喷雾质谱分析手段检测到了阴阳离子通过协同作用亲电亲核催化过程中的反应中间体,证明了该假设机理的可行性.此外,还考察了催化剂浓度、醇比、反应温度以及醇的空间位阻效应对反应的影响.以EmimOAc催化合成丙二醇丁醚为例,反应的转化率随催化剂浓度的增加而增大,在催化剂添加量1%(催化剂与PO的摩尔比)时,PO转化率达到最大值为98.2%,1-丁氧基-2-丙醇的选择性为86.4%.当正丁醇与环氧丙烷的摩尔比为3时,转化率最高为88.6%,选择性高达94%.该反应为放热反应,最适反应温度约为140 oC,此时转化率高达96.5%.在环氧丙烷和不同的低碳醇合成丙二醇醚的反应中,反应物醇的碳链越短,支链越少,催化反应效率越高.     

Brønsted酸性离子液体在醛醇缩合反应中的应用

合成了一系列Brønsted酸性离子液体并将其应用在醛醇缩合反应中.醛醇缩合产物由于极好的溶剂性质等被广泛用作溶剂和试剂.离子液体[BSmim][OTf]在甲醛和乙二醇缩合生成1,3-二氧五环的反应中表现出了极好的催化活性,甲醛转化率和主产物1,3-二氧五环选择性分别可以达到96.1%和92.4%.对影响离子液体催化性能的因素进行了探索,并对催化反应中的离子液体的用量、反应温度、反应时间以及反应物料比进行了考察.通过Hammett酸度函数法测定了所用到离子液体的酸性,结果表明离子液体酸性与其在缩合反应中的催化活性顺序完全一致,酸性越强催化性能越好.结合实验给出了离子液体[BSmim][OTf]催化甲醛和乙二醇缩合反应的可能的反应机理.该催化剂体系具有良好的催化性能,反应可以在较温和的条件下进行,实现了高活性和高选择性的目标,产物易分离,催化剂重复使用7次,其催化活性基本不变.并将该Brønsted酸性离子液体进一步应用到其他醛（酮）醇缩合反应中.     

Br(o)nsted酸性离子液体在醛醇缩合反应中的应用

合成了一系列Br(o)nsted酸性离子液体并将其应用在醛醇缩合反应中.醛醇缩合产物由于极好的溶剂性质等被广泛用作溶剂和试剂.离子液体[BSmim][OTf]在甲醛和乙二醇缩合生成1,3-二氧五环的反应中表现出了极好的催化活性,甲醛转化率和主产物1,3-二氧五环选择性分别可以达到96.1％和92.4％.对影响离子液体催化性能的因素进行了探索,并对催化反应中的离子液体的用量、反应温度、反应时间以及反应物料比进行了考察.通过Hammett酸度函数法测定了所用到离子液体的酸性,结果表明离子液体酸性与其在缩合反应中的催化活性顺序完全一致,酸性越强催化性能越好.结合实验给出了离子液体[BSmim][OTf]催化甲醛和乙二醇缩合反应的可能的反应机理.该催化剂体系具有良好的催化性能,反应可以在较温和的条件下进行,实现了高活性和高选择性的目标,产物易分离,催化剂重复使用7次,其催化活性基本不变.并将该Br(o)nsted酸性离子液体进一步应用到其他醛(酮)醇缩合反应中.     

Ionic liquid assisted synthesis of S-heterocycles

Some organic solvents are highly toxic, flammable, and even explosive. In particular, high vapor pressures and toxicity of certain volatile organic solvents may cause significant environmental problems. Therefore, alternative solvents or media with tunable and versatile solvation properties for conducting chemical reactions and materials synthesis have been actively sought. Ionic liquids have numerous applications not only as environmentally benign reaction media, but also as catalysts and reagents. Due to the increase of environmental consciousness in chemical research and industry, the challenge for a sustainable environment calls for clean procedures that avoid the use of harmful organic solvents. Due to the special properties of ILs (ionic liquids) such as wide liquid range, good solvating ability, negligible vapor pressure, non-inflammability, non-volatility, environment friendly medium, high thermal stability, good stability in air and moisture, easy recycling and rate promoters etc. they are used in organic synthesis. Therefore, ionic liquids have attracted the attention of chemists and act as catalyst and reaction medium in organic reactions with high activity. Highly efficient methods are explored for the preparation of S-heterocycles with the application of ILs as catalyst and reaction medium.     

离子液体在有机反应中的应用

室温离子液体，由含氮的有机阳离子和无机阴离子组成，可溶解各种有机、无 机、金属有机化合物。它们没有蒸气压、不易燃、容易循环使用。近年已发现，离 子液体可广泛地用于许多过渡金属化合物和酶催化的反应。着重讨论这方面的发展 状况。     

Selective chemical reactions in supercritical carbon dioxide,water, and ionic liquids

Abstract

Alternative solvents such as supercritical carbon dioxide, water, and ionic liquids are receiving an increase of interest as better replacements for conventional solvents in chemical reactions. They have been called sustainable green solvents because they are highly promising reaction mediums for organic synthesis. This review presents an overview of some selected chemical reactions that have been developed in these green solvents with a particular emphasis on metal-catalyzed reactions.     

DESs: Green solvents for transition metal catalyzed organic reactions

The recent development about using DESs as green solvents in transition metal catalyzed organic reactions was highlighted, and Au, Metal impregnated on magnetite, Pd, Ru catalyzed organic reactions proceeded smoothly in DESs and gave corresponding products in reasonable yields. And in some cases, the catalytic systems could be recycled up to several times.     

DESs: Green solvents for transition metal catalyzed organic reactions

In this review, the recent development about using DESs as green solvents in transition metal catalyzed organic reactions was highlighted. Firstly, the development of DESs was simply introduced. After presenting the advantages of DESs, transition metals catalyzed organic reactions using DESs as green solvents were classified and introduced in detail. Different transition metals such as Au, metal impregnated on magnetite, Pd and Ru catalyzed organic reactions proceeded smoothly in DESs and gave corresponding products in good yields. And in some cases, the catalytic systems could be recycled up to several times without any decrease in activity.     

CO2膨胀液体热力学特性及在化学反应中的应用

二氧化碳膨胀液体被认为是环境友好的绿色溶剂,具有良好的气体溶解度、传质特性、低黏度、条件温和以及有机溶剂用量少等突出特点,受到化学家和化学工程学家们越来越多的重视。本文详细介绍了二氧化碳膨胀液体的体积膨胀度、相平衡热力学、传递特性、酸性以及导电性等理论研究成果;在此基础上,分析讨论了这些性质变化的内在原因;总结了目前为止利用二氧化碳膨胀液体所开发的化学反应研究现状,包括加氢、醛化、氧化及其它反应等;对存在的问题和今后应该致力于解决的技术性难题进行了讨论,指出了今后重点发展的方向。     

Synthesis, characterization, and applications of dendrimer-encapsulated nanoparticles

In this article we describe the synthesis, characterization, and applications of dendrimer-encapsulated nanoparticles (DENs). These materials are synthesized by a template approach in which metal ions are extracted into the interior of dendrimers and then subsequently chemically reduced to yield nearly size-monodisperse particles having dimensions of less than 3 nm. Monometallic, bimetallic (including core/shell), and semiconductor nanoparticles have been prepared by this route. The dendrimer component of these composites serves not only as a template for preparing the nanoparticle replica but also to stabilize the nanoparticle, makes it possible to tune solubility, and provides a means for immobilization of the nanoparticle on solid supports. These materials have a number of potential applications, but the focus here is on catalysis. Homogeneous catalytic reactions, including hydrogenations, Heck coupling, and Suzuki reactions, in water, organic solvents, biphasic fluorous/organic solvents, and liquid and supercritical CO2 are discussed. In many cases it is easy to recycle catalytic DENs. DENs can also be immobilized on supports, such as silica and titania, and used for heterogeneous catalysis. Bimetallic DENs are shown to have particularly interesting catalytic properties. In addition to a discussion of current progress in this field, a number of intriguing questions related to the properties and potential applications of these materials are examined.     

Reactions in Water – A Greener Approach Using Ruthenium Catalysts

Reactions using transition metals as catalysts have emerged as an efficient method in the recent times. However, the selection of solvent plays a crucial role in this regard. Several solvents used traditionally suffer majorly with problems of toxicity; high boiling point etc. leading to drastic reaction conditions. Water being a non‐toxic, non‐inflammable and environmentally benign can replace the hazardous organic solvents in laboratory as well as industry. Maintaining a minimum catalyst loading percentage we can advantageously avail high levels of selectivity. Water was found to be a good solvent medium for several metal catalysed reactions. An intramolecular deprotonation mechanism is followed by the ruthenium (II) catalysts in water; thereby, facilitating the catalytic action of the metal. These studies can help the industrial chemists to utilize water as a solvent for their reactions towards improvement of their waste management procedure. This review mainly focuses on the several recent developments in the above direction.     

Development of Microdroplet Generation Method for Organic Solvents Used in Chemical Synthesis

Recently, chemical operations with microfluidic devices, especially droplet-based operations, have attracted considerable attention because they can provide an isolated small-volume reaction field. However, analysis of these operations has been limited mostly to aqueous-phase reactions in water droplets due to device material restrictions. In this study, we have successfully demonstrated droplet formation of five common organic solvents frequently used in chemical synthesis by using a simple silicon/glass-based microfluidic device. When an immiscible liquid with surfactant was used as the continuous phase, the organic solvent formed droplets similar to water-in-oil droplets in the device. In contrast to conventional microfluidic devices composed of resins, which are susceptible to swelling in organic solvents, the developed microfluidic device did not undergo swelling owing to the high chemical resistance of the constituent materials. Therefore, the device has potential applications for various chemical reactions involving organic solvents. Furthermore, this droplet generation device enabled control of droplet size by adjusting the liquid flow rate. The droplet generation method proposed in this work will contribute to the study of organic reactions in microdroplets and will be useful for evaluating scaling effects in various chemical reactions.     

Green solvents from ionic liquids and deep eutectic solvents to natural deep eutectic solvents

Natural deep eutectic solvents (NADESs) are defined as mixtures of certain molar ratios of natural compounds such as sugars, organic acids, amino acids, and organic bases that are abundant in organisms. The melting points of these mixtures are considerably lower than those of their individual ingredients and far below ambient temperature. The first publications on the NADES concept in 2011 created a great expectation regarding their potential as green solvents that could replace conventional organic solvents in a wide range of applications. This was largely because many of the drawbacks of conventional synthetic ionic liquids (ILs) and deep eutectic solvents (DESs), particularly their toxicity and environmental hazards, could be solved using NADESs. Throughout the last 7 years, the interest in NADESs has increased enormously as reflected by the exponential growth of the number of related publications. The research on NADESs has rapidly expanded particularly into the evaluation of the feasibility of their application in diverse fields such as the extraction of (targeted) bioactive compounds from natural sources, as media for enzymatic or chemical reactions, preservatives of labile compounds, or as vehicles of non–water-soluble compounds for pharmaceutical purposes. Along with the exploration of these potential applications, there have been a large number of other studies related to their physicochemical features, the search for new NADESs, the research into the interactions between NADES components or with solutes, the recovery of solutes from NADES solutions, and the ways of circumventing inherent problems of NADESs such as their high viscosity and the consequent difficulties in handling them. This article contains a review of the applications of NADESs as extraction solvents, reaction media, and preservative, providing also a perspective of their future.