Catalytic applications of immobilized ionic liquids for synthesis of cyclic carbonates from carbon dioxide and epoxides

The catalytic applicability of ionic liquids immobilized on various support materials such as silica, polystyrene and biopolymers in the cycloaddition of carbon dioxide with epoxides is reviewed in this work. Comparisons of the catalytic efficiency of these various catalysts have been done from the aspect of turnover number and reusability. The studies revealed that ionic liquids or support materials possessing hydrogen bonding capable groups exhibited enhanced catalytic activity towards cyclic carbonate synthesis. Moreover, the increased quest towards environmentally benign materials has renewed the search for biocompatible materials as support for ionic liquids.     

Electrochemical synthesis of polypyrrole in ionic liquids

Electrochemical synthesis of inherently conducting polymers such as polypyrrole is traditionally performed in a molecular solvent/electrolyte system such acetonitrile/lithium perchlorate. We report the use of ionic liquids 1-butyl-3-methylimidazolium hexafluorophosphate, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl) amide and N,N-butylmethylpyrrolidinium bis(trifluoromethanesulfonyl) amide, both as the growth medium and as an electrolyte for the electrochemical cycling of polypyrrole films. Use of the ionic liquid as the growth medium results in significantly altered film morphologies and improved electrochemical activities.     

碳酸酯合成过程催化剂离子液体固载方式研究进展

有机碳酸酯是一类重要的化工原料,常被用在药物合成、绿色添加剂、锂电池电解液以及合成聚碳酸酯等领域,碳酸酯的合成是实现CO2碳资源化最有效的途径之一.固载化离子液体兼具均相催化剂的高活性和固相催化剂易于分离和回收等特点,在碳酸酯合成反应中具有广阔的工业应用前景.综述用于合成碳酸酯的固载化离子液体催化剂固载技术研究进展,总...     

An environment-friendly method for synthesis of 1,4-dibromo-naphthalene in aqueous solution of ionic liquids

An environment-friendly method was developed to synthesize 1,4-dibromonaphthalene (1,4-DBN) using 1,3-dialkylimidazolium and pyridinium ionic liquids as catalysts, over which the yields of 1,4-DBN were obtained as high as 100%. Through this method bromine atoms were able to totally transferred into product. As water was the only byproduct in this process, it was a completely ‘clean’ method for the preparation of 1,4-DBN.     

Implementation of ionic liquids as activating media for polycondensation processes

Ionic Liquids (ILs) have been used for polycondensation processes, especially for polyimide synthesis. The influence of various reaction parameters including IL's cations and anions nature, monomer structure and concentration, reaction temperature, upon polyimide molecular weight (η_inh) was investigated. The possibility of process activation by the application of IL's small additives in one step polyimide synthesis in common organic solvents was demonstrated. The peculiarities of C-H?Br contacts in solid state were carried out using single crystal X-ray diffraction data. Various high molecular weight polyimides including commercial and sulfonated ones have been obtained in quantitative yields with inherent viscosities ranging from 0.10 to 2.17 dl g⁻¹.     

Prediction and verification of heat capacities for pure ionic liquids

The heat capacity of ionic liquids is an important physical property,and experimental measuring is usually used as a common method to obtain them.Owing to the huge number of ionic liquids that can be potentially synthesized,it is desirable to acquire theoretical predictions.In this work,the Conductor-like Screening Model for Real Solvents(COSMO-RS) was used to predict the heat capacity of pure ionic liquids,and an intensive literature survey was conducted for providing a database to verify the prediction of COSMO-RS.The survey shows that the heat capacity is available for 117 ionic liquids at temperatures ranging 77.66-520 K since 2004,and the 4025 data points in total with the values from 76.37 to 1484 J·mol~(-1)·K~(-1) have been reported.The prediction of heat capacity with COSMO-RS can only be conducted at two temperatures(298 and 323 K).The comparison with the experimental data proves the prediction reliability of COSMO-RS,and the average relative deviation(ARD) is 8.54%.Based on the predictions at two temperatures,a linear equation was obtained for each ionic liquid,and the heat capacities at other temperatures were then estimated via interpolation and extrapolation.The acquired heat capacities at other temperatures were then compared with the experimental data,and the ARD is only 9.50%.This evidences that the heat capacity of a pure ionic liquid follows a linear equation within the temperature range of study,and COSMO-RS can be used to predict the heat capacity of ionic liquids reliably.     

Electromechanical behavior of fully plastic actuators based on bucky gel containing various internal ionic liquids

In the previous papers, we have reported the first dry actuator that can be fabricated simply by layer-by-layer casting, using ‘bucky gel’, a gelatinous room-temperature ionic liquid (IL) containing single-walled carbon nanotubes (SWNTs). In this paper, the electromechanical and electrochemical properties of the bucky-gel actuators composed of the bucky-gel electrode and the gel electrolyte layers containing seven kinds of internal ILs were studied for exploring the details of the actuation mechanism. We measured the frequency dependence of the displacement response of the bucky-gel actuator and it can be successfully simulated by the electrochemical kinetic model. From the simulated result for the frequency dependence of the electromechanical response of the bucky-gel actuators, we determined two parameters for the simulation, the generated strain at a limit of low frequency and the time constant. The time constant was represented by the equivalent circuit composed of series combination of the ionic resistance R, the double-layer capacitance C and the electrode resistance R_el. The IL-dependence of the time constant was determined by that of the ionic resistance R of the gel electrolyte layer. The generated strain at a limit of low frequency is considered to be related to the electromechanical mechanism of the bucky-gel actuator. From their dependence on the IL species and the theoretical modeling reported in the previous papers, we conclude that both the steric repulsion effect due to the transfer of ions to the electrode and ‘the charge injection’ give the bending motion of the bucky-gel actuator. The volume-changes of the cathode and anode change according to the sizes of the cation and anion, respectively. The ion size gives the dependence of the bending motion of the bucky-gel actuator on the internal ionic species.     

Highly selective synthesis of dimethyl carbonate from urea and methanol catalyzed by ionic liquids

Direct synthesis of dimethyl carbonate from methanol and urea using ionic liquids, such as Et₃NHCl–FeCl₃, Et₃NHCl–ZnCl₂, Et₃NHCl–CuCl₂, Et₃NHCl–SnCl₂ and emimBr–ZnCl₂, as catalysts were investigated. Among the ionic liquids, Et₃NHCl–ZnCl₂ or emimBr–ZnCl₂ exhibited higher activity for the synthetic reaction and surprisingly high selectivity to DMC. The effects of the various reaction conditions, i.e. reaction temperature, molar ratio of methanol to urea, and amount and composition of catalysts, on the synthesis of DMC were discussed in a systematic way. The reaction mechanism and the reasons why raised activity and high selectivity of the catalyst are maintained were explored.     

A method for the design of distillation systems aided by ionic liquids

Ionic liquids (ILs) have recently been considered for several applications in chemical processes. Particularly, as they promote an evident salting-out effect over vapor–liquid equilibrium properties and integrate the advantages of a liquid entrainer with the benefits of a solid salt, the use of ILs for the ethanol–water separation has gained wider interest. In this work, a design method for distillation systems aided by ILs is presented. The method is based on tray-by-tray calculations from the outside to the inside of the column, and the feed stage is determined by using a minimum distance concept. The method is illustrated with an ethanol dehydration design. An analysis on the effect of ILs on the column composition profiles is also carried out. The method is shown to provide an effective tool for the conceptual design of these types of systems.     

离子液体在燃料油脱硫中的应用

室温离子液体作为一类新型绿色介质,近年来在各个领域的应用得到了突飞猛进的发展。作者综述了离子液体用于燃料油和模型油脱硫技术方面的几种方法,包括萃取法、催化氧化法、氧化-萃取法、光化学氧化-萃取耦合法及烷基化法。离子液体由于可以循环使用,必将在燃料油脱硫技术领域发挥重要作用。     

离子液体在车用燃料油脱硫中的应用

综述了离子液体在燃料油脱硫中的应用情况,详细介绍了Lewis酸性离子液体和非Lewis酸性离子液体对各种烃类与含硫化合物的溶解性以及在汽、柴油萃取脱硫和氧化萃取组合脱硫工艺中的应用,并介绍了Lewis酸性离子液体作为催化剂在FCC汽油烷基化脱硫技术中的应用研究。最后,探讨了离子液体在今后燃料油脱硫中的研究方向和工业化前景。     

磁性介孔硅胶负载碱性离子液体催化剂的制备与性能

用巯丙基硅氧烷对磁性介孔硅胶改性,并通过烯丙基官能化离子液体的双键与巯基之间的自由基加成反应将具有不同侧链烷基的离子液体负载到磁性介孔硅胶表面,制备了磁性介孔硅胶负载碱性离子液体催化剂.采用红外光谱分析、X射线衍射、有机元素分析、氮气物理吸附/脱附分析和样品振动磁强计对催化剂的结构和磁性能进行了表征,最后通过催化三油酸甘油酯与甲醇酯交换反应对其催化性能进行了评价.结果表明,随着离子液体侧链烷基碳个数的增多,磁性介孔硅胶负载离子液体催化剂的离子液体负载量降低,比表面积和孔体积降低.当离子液体侧链烷基为辛基、十二烷基或十六烷基时,油酸甲酯产率均高于95%,并且反应3次后油酸甲酯产率依然高于90%.     

Mechanistic study on the cellulose dissolution in ionic liquids by density functional theory☆

Ionic liquids (ILs) have attracted many attentions in the dissolution of cellulose due to their unique physicochem-ical properties as green solvents. However, the mechanism of dissolution is stil under debate. In this work, com-putational investigation for the mechanisms of dissolution of cellulose in [Bmim]Cl, [Emim]Cl and [Emim]OAc ILs was performed, and it was focused on the process of breakage of cel ulose chain and ring opening using cel obiose as a model molecule. The detailed mechanism and reaction energy barriers were computed for various possible pathways by density functional theoretical method. The key finding was that ILs catalyze the dissolution process by synergistic effect of anion and cation, which led to the cleavage of cellulose chain and formation of derivatives of cel ulose. The investigation on ring opening process of cellobiose suggested that carbene formed in ILs played an important role in the side reaction of cellulose, and it facilitated the formation of a covalent bond between cel-lulose and imidazolium core. These computation results may provide new perspective to understand and apply ILs for pretreatment of cellulose.     

Immobilisation of chloroaluminate ionic liquids on silica materials

Two different possibilities for the preparation of immobilised ionic liquids are presented. Lewis acidic ionic liquids which have been shown to be highly active catalysts in alkylation reactions of the Friedel–Crafts type were supported on amorphous silica and MCM 41 materials. We describe the different methods used, as well as analytical data and some catalytical results achieved by these catalysts.     

Study of the conductivity behavior of pyridinium-based ionic liquids

In this work, ionic conductivity data as a function of temperature in the pyridinium-based ionic liquids 1-butylpyridinium tetrafluoroborate, 1-butylpyridinium triflate, 1-butyl-2-methylpyridinium tetrafluoroborate, 1-butyl-3-methylpyridinium tetrafluoroborate, 1-butyl-4-methylpyridinium tetrafluoroborate, 1-butyl-3-methylpyridinium dicyanamide, and 1-octyl-3-methylpyridinium tetrafluoroborate, are reported. A comparison of results for this series of ionic liquids has been used to evaluate the influence of the ionic structural characteristic in this transport property. Temperature dependence of experimental values has been fitted by means of the Vogel-Fulcher-Tammann equation, and from their parameters, maximum conductivity and activation energy for conduction have been derived. From conductivity parameters and the glass transition temperature, a detailed analysis has been performed in fragility terms. Finally, the classical Walden rule has been used to classify the ionic liquids depending on the relationship between conductivity and fluidity.     

Polymeric ionic liquids (PILs) with high acid density:Tunable catalytic performance for biodiesel production

A series of polymeric ionic liquids (PILs) used as effective heterogeneous catalysts for biodiesel produc-tion via esterification of free fatty acids (FFAs) were effectively prepared by the reaction of poly (ethylene imine) (PEI) polymers with different molecular weight and 1,3-propanesultone,followed by the further acidification with differential effective acids,i.e.H2SO4,CF3SO3H,CH3SO3H or p-toluenesulfonic acid(p-TSA).Ultrahigh acidity and catalytic performance were achieved and could be fine-tuned by simply adjusting the molecular weight of PEI and by further treatment of acids.Specifically,under the optimal conditions (i.e.reaction temperature was 70 ℃,reaction time was 2.0 h,catalyst dosage was 3.15％(mass),and alcohol/acid molar ratio was 14∶1) acquired through the Box-BEHNKEN response surface methodology,a high oleic acid conversion of 98.42％ could be obtained over the optimal PIL,PEI(70000)-PS-p-TSA.Additionally,our PILs also showed high generality for esterification of other FFAs,with general high conversion over 90％ noted in each case even under much milder reaction conditions com-pared to other conventional catalysts.     

Highly selective transport of transesterification reaction compounds through supported liquid membranes containing ionic liquids based on the tetrafluoroborate anion

We previously reported the selective simultaneous separation of the substrates and products of a transesterification reaction (vinyl butyrate, 1-butanol, butyl butyrate and butyric acid) through supported liquid membranes (SLMs) based on 1-n-alkyl-3-methylimidazolium cations combined with tetrafluoroborate, hexafluorophosphate and bis{(trifluoromethyl)sulfonyl}imide anions. The best results were obtained by the use of tetrafluoroborate based ionic liquids, which led us to further investigate the use of these new supported liquid membranes for the selective separation of different substrates and products of transesterification reactions. With this aim, the permeability of sixteen different organic compounds (vinyl esters, aliphatic esters, alcohols and carboxylic acids) through SLMs containing tetrafluoroborate based ionic liquids ([bmim⁺][BF₄⁻] and [omim⁺][BF₄⁻]) were evaluated. It was found that permeability increased as the alkyl chain length decreased for the same organic functional group. In addition, significant permeability differences were found between the different organic functional groups.As regards the operational stability of these SLMs, they were seen to be very stable when tested over eight continuous cycles of 48 h each.     

咪唑型室温离子液体的绿色合成研究

设计了无溶剂一锅法合成1-丁基-3-甲基咪唑四氟硼酸盐和1-丁基-3-甲基咪唑六氟磷酸盐室温离子液体的新的合成路线,反应原料在80℃下搅拌反应3 h,分离产率分别为97.8%和92.9%。用IR1、HNMR1、3CNMR对离子液体的结构进行了表征,热重分析法测试了其热稳定性能分别为340℃和360℃,探索了反应温度和反应时间对产率的影响。     

Catalytic performance of pyridinium salt ionic liquid in the synthesis of cyclic carbonate from carbon dioxide and butyl glycidyl ether

The catalytic performance of pyridinium salt ionic liquids in the reaction of butyl glycidyl ether and carbon dioxide was investigated in this study. The catalytic activity was studied in a batch reactor with different 1-alkylpyridinium salt ionic liquids at 60–140°C. The conversion of butyl glycidyl ether was affected by the structure of the ionic liquid; the one with the cation of bulkier alkyl chain length showed better reactivity. The effect of carbon dioxide pressure, reaction temperature and zinc bromide co-catalyst on this reaction was also discussed.