酸性离子液体催化制备生物柴油的研究进展

主要总结了国内外利用酸性离子液体催化合成生物柴油的进展,介绍了离子液体特性及其催化制备生物柴油的优点。简述了酸性离子液体在酯化和制备生物柴油反应中的应用,对酸性离子液体催化制备生物柴油的研究方向进行了展望。     

液体酸耦合体系催化C4烷基化研究进展

综述了近十年来液体酸耦合体系催化C₄烃烷基化反应的最新进展，包括液体超强酸、有机酸-杂多酸、离子液体-酸耦合体系，对比了不同催化体系催化C₄烃烷基化反应过程中的烯烃转化率、三甲基戊烷的选择性和烷基化汽油的研究法辛烷值，总结了不同催化体系的优缺点。重点论述了离子液体-酸耦合体系催化剂中组成离子液体的阴阳离子以及耦合酸类型对C₄烃烷基化反应的影响：有机胺类离子液体较咪唑类有着更为优异的烷基化效果，阴离子和改性离子液体通过形成特定的结构来维持反应体系的酸强度、减少副反应，从而延长催化剂的使用寿命，耦合酸为反应提供酸性位点并与离子液体协同催化。离子液体-酸耦合催化体系具有酸耗低、稳定性好、不易失活且可循环使用等优点，是C₄烷基化催化剂未来的发展方向之一。     

室温离子液体酸催化剂研究进展

综述了室温离子液体酸的组成、结构性质及其在催化酯化反应、Friedel-Crafts反应、烷基化反应、催化裂解、亲电反应及缩合反应等方面的应用进展.同传统酸催化剂体系相比,使用室温离子液体酸催化剂的反应体系的选择性、活性及催化剂循环次数均可得到改善,并能有效地抑制副反应,缩短反应时间并简化产物与体系的分离过程.探索室温离子液体酸对于特定反应的催化性能,是现今国内外相关研究领域的一个热点.     

离子液体/CF3SO3H耦合催化1-丁烯/异丁烷烷基化反应

采用季胺化反应-复分解或质子化两步法设计合成了系列阴离子为BF4-或CF3SO3-的咪唑类、吡啶类的功能化离子液体. 系列功能化离子液体与三氟甲磺酸耦合催化1-丁烯/异丁烷的烷基化反应,并获得了C8选择性81.1%,TMP/DMH=8.36及RON值为95.3的良好催化效果,耦合催化剂在不降低催化活性的条件下可循环使用6次.     

固定化离子液体在催化与分离方面的应用进展

目前离子液体的成本高、粘度大限制了离子液体的工业应用. 固定化离子液体是将离子液体填充入多孔有机或无机载体的空隙形成的液体膜，固定化过程可以通过物理吸附、包埋或通过化学键合的方法实现. 将离子液体固定化可以增大离子液体的比表面积，从而提高离子液体的利用效率和稳定性. 固定的离子液体宏观呈固相，更有利于回收. 本工作介绍了离子液体的固定化方法以及固定化离子液体在催化、分离方面的应用进展.     

离子液体支撑液膜的研究及应用进展

回顾了目前为止离子液体支撑液膜的制备方法,离子液体结构,支撑膜结构对离子液体支撑液膜稳定性的影响因素,介绍了其在有机物分离,气体分离、分离反应耦合方面的应用.由于传统的单元操作很难满足污染和对过程集成的要求,对离子液体支撑液膜在未来实现清洁生产的发展方向进行了展望.     

无溶剂下负载离子液体催化合成碳酸丙烯酯

研究了在无溶剂条件下,利用负载型离子液体催化二氧化碳和环氧丙烷合成碳酸丙烯酯的反应.在4 MPa、130℃反应2 h后,BMImBF4离子液体催化活性要远大于Ⅺ的催化活性.BMImBF4/SiO2负载型离子液体的催化活性要略低于BMImBF4离子液体,但负载后更有利于反应产物的分离.并研究了反应时间、反应压力和反应温度对碳酸丙烯酯产率和选择性的影响.     

离子液体在脂肪酶催化合成生物柴油中的应用发展趋势

从固定化和非水介质两方面介绍了脂肪酶催化合成生物柴油的现状。简述了离子液体作为绿色溶剂的特性及对脂肪酶催化反应的影响,明确使用离子液体可提高酶的稳定性,维持酶的催化活性。综述了离子液体作为潜在的反应介质应用于脂肪酶催化高产生物柴油的前景。     

离子液体催化异丁烷与丁烯烷基化反应的研究

以三氯化铝、吡啶和HCl为基本原料,合成出一种离子液体,并在高压釜中考察了这种离子液体对异丁烷与丁烯烷基化反应的催化效果以及相关反应条什的影响.实验结果表明,所合成的离子液体对异丁烷与丁烯的烷基化反应具有较好的催化性能,在催化反应过程中,离子液体可重复使用,稳定性较好;失活后的离子液体可以用AlCl3进行再生:而且,离子液体与烷基化产物很容易分离.     

离子液体在萃取分离中的研究应用

阐述了离子液体在萃取分离中的应用进展。重点介绍了离子液体在萃取分离有机物、金属离子和生物分子方面的应用研究,并对离子液体与超临界CO2相结合的萃取分离方法的研究作了简单介绍。     

Insight into the behavior at the hygroscopicity and interface of the hydrophobic imidazolium-based ionic liquids

How to completely remove the water from ionic liquids(ILs) is difficult for researchers because of the hygroscopicity of ILs. In order to study the hygroscopicity of ILs, two kinds of ILs, 1-Butyl-3-methylimidazolium hexafluorophosphate([Bmim][PF_6]) and 1-Butyl-3-methylimidazolium Bis(trifluoromethanesulfonyl)([Bmim][NTf_2]) were investigated by molecular dynamics simulations. Although[Bmim][PF_6] and [Bmim][NTf_2] are hydrophobic, both of the ILs could absorb water molecules from the vapor. In this work, the process of absorbing water from the vapor phase was studied, and the water molecules could disperse into the IL. Aggregation was observed with increasing the water concentration.Although the absorbed water increases obviously, the amount of free water and small cluster in the ILs does not change significantly and always stays at a certain level. The amount of free water and small cluster in [Bmim][PF_6] is more than that in [Bmim][NTf_2], which is consistent with their hydrophobicity. In addition, the liquid-vacuum and liquid–liquid interfaces of the ILs were simulated and analyzed in detail.The number density distribution and angle distribution indicated that [Bmim]+cations arrangement regularly at the IL-vacuum interface. The butyl chain point to the vacuum, while the imidazlium ring is close to the IL phase region and perpendicular to the interface. While at the IL-water interface, the cations and anions are disordered.     

Protein stabilization and enzyme activation in ionic liquids: specific ion effects

There are still debates on whether the hydration of ions perturbs the water structure, and what is the degree of such disturbance; therefore, the origin of the Hofmeister effect on protein stabilization continues to be questioned. For this reason, it is suggested to use the ‘specific ion effect’ instead of other misleading terms such as Hofmeister effect, Hofmeister series, lyotropic effect, and lyotropic series. This review first discusses the controversial aspect of inorganic ion effects on water structures, and several possible contributors to the specific ion effect of protein stability. Due to recent overwhelming attraction of ionic liquids (ILs) as benign solvents in many enzymatic reactions, this paper further evaluates the structural properties of ILs and molecular‐level interactions in neat ILs and their aqueous solutions. Next, the specific ion effects of ILs on enzyme stability and activity are systematically compared and it is concluded that (a) the specificity of many enzymatic systems in diluted aqueous IL solutions is roughly in line with the traditional Hofmeister series albeit some exceptions; (b) however, the specificity follows a different track in concentrated or neat ILs because other factors (such as hydrogen‐bond basicity, nucelophilicity, and hydrophobicity, etc.) are playing leading roles. In addition, some examples of biocatalytic reactions in IL systems that are guided by the empirical specificity rule are demonstrated. © 2015 Society of Chemical Industry     

Methods for stabilizing and activating enzymes in ionic liquids—a review

Ionic liquids (ILs) have evolved as a new type of non‐aqueous solvents for biocatalysis, mainly due to their unique and tunable physical properties. A number of recent review papers have described a variety of enzymatic reactions conducted in IL solutions; on the other hand, it is important to systematically analyze methods that have been developed for stabilizing and activating enzymes in ILs. This review discusses the biocatalysis in ILs from two unique aspects (1) factors that impact the enzyme's activity and stability, (2) methods that have been adopted or developed to activate and/or stabilize enzymes in ionic media. Factors that may influence the catalytic performance of enzymes include IL polarity, hydrogen‐bond basicity/anion nucleophilicity, IL network, ion kosmotropicity, viscosity, hydrophobicity, the enzyme dissolution, and surfactant effect. To improve the enzyme's activity and stability in ILs, major methods being explored include the enzyme immobilization (on solid support, sol–gel, or CLEA), physical or covalent attachment to PEG, rinsing with n‐propanol methods (PREP and EPRP), water‐in‐IL microemulsions, IL coating, and the design of enzyme‐compatible ionic solvents. It is exciting to notice that new ILs are being synthesized to be more compatible with enzymes. To utilize the full potential of ILs, it is necessary to further improve these methods for better enzyme compatibility. This is what has been accomplished in the field of biocatalysis in conventional organic solvents. Copyright © 2010 Society of Chemical Industry     

Research progress in ionic liquids catalyzed isobutane/butene alkylation

The complicated reaction mechanism and the character of competitive reactions lead to a stringent requirement for the catalyst of C4 alkylation process. Due to their unique properties, ionic liquids (ILs) are thought to be new potential acid catalysts for C4 alkylation. An analysis of the regular and modified chloroaluminate ILs, novel Br?nsted ILs and composite ILs used in isobutane/butene alkylation shows that the use of either ILs or ILs coupled with mineral acid as homogeneous catalysts can help to greatly adjust the acid strength. By modifying the struc-tural parameters of the cations and anions of the ILs, the solubility of the reactants could also be adjusted, which in turn displays a positive effect on improving the activity of ILs. Immobilization of ILs is an effective way to mod-ulate the surface adsorption/desorption properties and acid strength distribution of the solid acid catalysts. Such a process has a tremendous potential to reduce the deactivation of catalyst and enhance the activity of the solid acid catalyst. The development of novel acid catalysts for C4 alkylation is a comprehensive consideration of acid strength and its distribution, interfacial properties and transport characteristics.     

Photoinitiated polymerization in ionic liquids and its application

Ionic liquids (ILs) are low‐melting organic salts often liquid at room temperature, whose unique properties are the reason of increasing interest for their applications as solvents, reaction media and functional additives. The exceptional properties of ILs have proved to be particularly useful in polymer science giving the potential to produce polymeric materials with improved properties or to immobilize ILs in polymer matrices while keeping their special characteristics. One of the possibilities is polymerization in ILs which can also affect positively polymerization reactions. An especially attractive technique is photopolymerization due to the ease of process control, short reaction time and ambient working temperature. This review gives a literature survey of developments in photopolymerization processes carried out in ILs as well as applications of these processes. It covers both the photopolymerization in ILs as well as photopolymerization of IL monomers. The first part presents a short overview of physicochemical and photochemical properties of ILs; it includes also photochemical reactions and photoinitiation of polymerization in ILs. The second part covers both the basic research (kinetics of photopolymerization including polymerization rate coefficients and polymerization of IL monomers) as well as applications of UV‐induced polymerization in ILs. © 2016 Society of Chemical Industry     

Effect of Ionic Liquids on Organic Reactions Based on Activity Coefficients at Infinite Dilution

It is important to know how ILs（ionic liquids） influence organic reaction. In this paper, activity coefficients at infinite dilution of more than 80 organic compounds in ILs are collected and analyzed systematically. Through the study on typical organic reactions happened in ILs, such as Diels-Alder, esterification and Friedel-Crafts reaction, the ratio of activity coefficients at infinite dilution of products and reactants is employed to estimate different effects of different structural ILs on the rate and selectivity of reactions.     

COSMO-RS:An ionic liquid prescreening tool for gas hydrate mitigation

Recently ionic liquids(ILs) are introduced as novel dual function gas hydrate inhibitors. However, no desired gas hydrate inhibition has been reported due to poor IL selection and/or tuning method. Trial error as well as selection based on existing literature are the methods currently employed for selecting and/or tuning ILs. These methods are probabilistic, time consuming, expensive and may not result in selecting high performance ILs for gas hydrate mitigation. In this work, COSMO-RS is considered as a prescreening tool of ILs for gas hydrate mitigation by predicting the hydrogen bonding energies(E_(HB)) of studied IL inhibitors and comparing the predicted E_(HB) to the depression temperature(?) and induction time. Results show that, predicted EHBand chain length of ILs strongly relate and significantly affect the gas hydrate inhibition depression temperature but correlate moderately(R = 0.70) with average induction time in literature. It is deduced from the results that, ? increases with increasing IL EHBand/or decreases with increasing chain length. However, the cation–anion pairing of ILs also affects IL gas hydrate inhibition performance. Furthermore, a visual and better understanding of IL/water behavior for gas hydrate inhibition in terms of hydrogen bond donor and acceptor interaction analysis is also presented by determining the sigma profile and sigma potential of studied IL cations and anions used for gas hydrate mitigation for easy IL selection.     

离子液体气体干燥技术的研究进展

离子液体（ionic liquids, ILs）被视为化工中传统溶剂的优良替代物，使用它们作为溶剂吸收可凝性气体时，具有溶剂损失少、无腐蚀和稳定性强等优点。一些ILs具有很强的吸水性，所以在气体干燥领域ILs受到了广泛关注。本文介绍了用于预测气体在ILs中溶解度的预测型分子热力学模型和气体在ILs中的实验测量方法，具体分析了ILs对CH₄、CO₂等气体的干燥机理和工艺，最后对ILs用于气体干燥的基础研究作出展望。     

RETRACTED ARTICLE: Enzyme performance in ionic liquids

Ionic liquids (ILs) having unique properties such as no measurable vapor pressure, nonflammability and a wide temperature range of liquid phase have been recognized as potential green solvents. As a result, ILs have been extensively explored as reaction media for various biocatalytic reactions over a decade. Enzyme activities in ILs are generally comparable with or higher than those observed in conventional organic solvents. Furthermore, enhanced thermal and operational stabilities and regio- or enantioselectivities have been observed in many cases. Thus, ILs offer new possibilities for the application of solvent engineering to biocatalytic reactions. This review discusses the effect of physicochemical properties of ILs on biocatalysis with respect to enzyme activity, stability and selectivity by systematizing literature data on enzyme-catalyzed reaction in ILs.     

Octanol/water partition coefficients of ionic liquids

BACKGROUND: Room temperature ionic liquids (ILs) are attractive alternatives to environmentally unfriendly volatile organic solvents. Partitioning is one of the most important and fundamental properties of a chemical, and the octanol/water partition coefficient is widely used to measure the tendency of a chemical to cross biological membranes. However, there is very limited information on the concentration dependence of the partition coefficients of ILs. This study investigated the octanol/water partitioning of 1‐butyl‐3‐methylimidazolium ([bmim]) ILs containing either hexafluorophosphate ([PF₆]) or bis[(trifluoromethyl)sulfonyl]amide ([Tf₂N]) over a wide range of IL concentrations of three to five orders of magnitude. RESULTS: It was found that the apparent partition coefficients of the ILs increased with increasing IL concentration. A model based on the ionic nature of ILs was proposed to explain this behaviour, and the results showed a good fit with the experimental data. The intrinsic partition coefficients and dissociation constants of the ILs were determined using the equations from the proposed model. The differences in the intrinsic partition parameter values between the two ILs showed a good correlation with other physicochemical properties. CONCLUSIONS: The present study clearly shows that the octanol/water partition coefficients of ILs increase with increasing IL concentration owing to the formation of ion pairs. By using the proposed partition model, it was possible to determine the intrinsic partition coefficients of ILs, and it was found that the apparent partition coefficients of ILs converge to the intrinsic partition coefficients of the ionic species and ion pairs of ILs with decreasing and increasing IL concentration respectively. Copyright © 2008 Society of Chemical Industry