离子液与氧化反应

氧化反应是合成药物和精细化学品中常用的单元反应，但是传统的氧化反应通常存在选择性差，反应时间长，催化剂不能回收利用等问题。离子液用作反应介质在氧化反应中显示出反应速率高、选择好、催化剂可回收重复使用等优点；文章介绍了最近几年与离子液相关的氧化反应的研究成果。     

离子液体；石油沥青质的新型溶剂

The dissolution of petroleum asphaltenes with ionic liquids is studied for the first time. The results show that the ionic liquids could be used as novel solvents for asphaltenes. The important parameters governing the ability of ionic liquids for dissolution of asphaltenes are discussed. It is found that, the ionic liquids based on the cations containing a conjugated aromatic core or the anions which are strong hydrogen bond acceptors are most effective, whereas the ionic liquids containing ＇non coordinating＇ anions such as [BF4]^- and [PF6]^- are nonsolvents for asphaltenes. Increase in the effective anion charge density enhances the ability of ionic liquids to break the extensive asphaltene associations and thus enhances the solubility of asphaltenes in the ionic liquid. The dissolution ability of ionic liquid decreases apparently with increasing the substituted alkyl chain length of its cationic head ring. Temperature is found to play an important role on dissolution of asphaltenes, and the dissolution can be significantly imoroved bv microwave heatinz.     

Thermal Properties of Macrocyclic Polyethers: Implications for the Design of Crown Ether-Based Ionic Liquids

The most commonly studied classes of ionic liquids (ILs) comprise relatively large and asymmetric heterocyclic cations (e.g., diakylimidazolium or N-alkylpyridinium) in combination with any of a wide variety of inorganic (e.g., BF₄^?, Cl^?) or organic (e.g., bis[(trifluoromethyl- sulfonyl)imide], Tf₂N^?) anions. Recently it has been shown that ILs can also be formed by complexation reactions of metal cations (e.g., Li⁺, as its Tf₂N^? salt) with various neutral ligands (e.g., cyclohexano-15-crown-5 or alkylamines). Because the upper limit of the useful temperature range of any IL is governed by its thermal stability, and because the thermal stability of a neutral ligand (i.e., its propensity to either volatilize or decompose) is of obvious importance in determining that of an IL prepared from it, a systematic examination of the thermal properties of a series of macrocyclic polyethers of potential utility in the synthesis of new ILs has been undertaken. The results show that the temperature corresponding to the onset of mass loss upon heating (i.e., evaporation and/or decomposition) varies with the ring size, substitution, nature of the donor atoms, and stereochemistry of the macrocycle, but is most strongly influenced by the molecular weight and aromatic content of the compound.     

新型绿色分离体系——离子液体双水相及其在生物分离中的应用

近几年来,离子液体双水相作为一种新型绿色分离体系越来越受到关注。离子液体双水相具有粘度低、分相快、不易乳化以及对生物物质萃取率高等优点。介绍了离子液体双水相的机理以及它在生物分离中的一些应用。     

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.     

Antitumor Activity of Ionic Liquids Based on Ampicillin

Significant antiproliferative effects against various tumor cell lines were observed with novel ampicillin salts as ionic liquids. The combination of anionic ampicillin with appropriate ammonium, imidazolium, phosphonium, and pyridinium cations yielded active pharmaceutical ingredient ionic liquids (API‐ILs) that show potent antiproliferative activities against five different human cancer cell lines: T47D (breast), PC3 (prostate), HepG2 (liver), MG63 (osteosarcoma), and RKO (colon). Some API‐ILs showed IC₅₀ values between 5 and 42 nM , activities that stand in dramatic contrast to the negligible cytotoxic activity level shown by the ampicillin sodium salt. Moreover, very low cytotoxicity against two primary cell lines—skin (SF) and gingival fibroblasts (GF)—indicates that the majority of these API‐ILs are nontoxic to normal human cell lines. The most promising combination of antitumor activity and low toxicity toward healthy cells was observed for the 1‐hydroxyethyl‐3‐methylimidazolium–ampicillin pair ([C₂OHMIM][Amp]), making this the most suitable lead API‐IL for future studies.     

Aerobic Oxidation Catalysis with Air or Molecular Oxygen and Ionic Liquids

Selective aerobic oxidation reactions are most important and challenging transformations in both academic research and the chemical industry. Over the past decade, ionic liquids have gained recognition in the context of green organic synthesis as they are not only possible environmentally benign solvents but also serve as a liquid support or catalyst in various chemical processes. Hence, in recent years, there has been a growing interest in the development of aerobic oxidation reactions combined with ionic liquids and molecular oxygen or air which has led to the improvement of green catalytic systems capable of achieving high selectivity and yields. Thus, this review aims to give an overview of the most important advances made by in the field of aerobic oxidation reactions in combination with either molecular oxygen or air as oxidant and ionic liquids as solvent, liquid support or catalyst.

     

Ionic Liquids for Clean Technology

The use of room-temperature chloroaluminate(III) ionic liquids, specifically 1-butylpyridinium chloride–aluminium(III) chloride and 1-ethyl-3-methylimidazolium chloride–aluminium(III) chloride, as solvents for clean synthesis and catalytic processes, particularly those applicable to clean technology, is becoming widely recognised and accepted. The design principles for room-temperature ionic liquids, some of their properties, and the rationale for using these neoteric solvents, are discussed here, and an indication of the scope of these solvents for future industrial processes is given. © 1997 SCI.     

Molecular dynamics simulation for the binary mixtures of high pressure carbon dioxide and ionic liquids简

Molecular dynamics simulation with an all-atom force field has been carded out on the two binary sys- tems of [bmim][PF6]-CO2 and [bmim][NO3]-CO2 to study the transport properties, volume expansion and micro- structures. It was found that addition of CO2 in the liquid phase can greatly decrease the viscosity of ionic liquids （ILs） and increase their diffusion coefficient obviously. Furthermore, the volume expansion of ionic liquids was found to increase with the increase of the mole fraction of CO2 in the liquid phase but less than 35% for the two simulated systems, which had a significant difference with CO2 expanded organic solvents. The main reason was that there were some void spaces inter and intra the molecules of ionic liquids. Finally, site to site radial distribution functions and corresponding number integrals were investigated and it was found that the change of microstructures of ILs bv addition CO2 had a great influence on the orooerties of ILs.     

含氟离子液体与功能材料

氟元素的引入促进了离子液体的快速发展。含氟离子液体具有较低的熔点和黏度、更好的耐水性和环境友好性,成为目前离子液体的主流品种,并实现了从耐水体系向功能体系的发展,凭借良好的可设计性和绿色环保的特点在绿色化工进程中显示出巨大的潜力和广阔的应用前景。简要总结了含氟离子液体的分类和物理化学性质,并重点介绍了含全氟烷基链的离子液体、含氟功能离子液体、含氟聚离子液体以及含氟离子液体改性膜材料等方面的研究与应用情况。     

L-脯氨酸为阴离子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,合成了四种烷基咪唑手性离子液体,并进行了结构表征。烷基咪唑溴化物离子液体经与氢氧化钾碱化后再与氨基酸中和反应制得产物,探索了合适的反应条件。测定了产物的比旋光度,考察了各产物的光学纯度。     

氯化胆碱·xZnCl_2离子液体在生物柴油制备中的应用(英文)

The inexpensive and moisture-stable Lewis-acidic ionic liquids were prepared and applied for transesterification of soybean oil to biodiesel.The influences of molar ratio of methanol to soybean oil,reaction temperature and amount of ionic liquids were investigated.The transesterification of soybean oil to biodiesel catalyzed by choline chloride·xZnCl2 ionic liquids showed many advantages such as mild conditions and lower cost.On the other hand,the non-ideal yield and complicated separation between biodiesel and soybean oil were also investigated and analyzed.The improvement on the systems of choline chloride·xZnCl2 was proposed for further investigation.     

Highly Efficient Oxidative Desulfurization of Fuels by Lewis Acidic Ionic Liquids Based on Iron Chloride

Acidic ionic liquids (ILs) have been employed as extractant and catalyst in the oxidative desulfurization (ODS) process of fuels in recent years. Several Lewis acidic ionic liquids [C₆³MPy]Cl/nFeCl₃ (molar fraction n = 0.5, 1, 2, 3) and [C₆MIM]Cl/FeCl₃ were prepared and used to remove the aromatic sulfur compounds dibenzothiophene and benzothiophene from fuels. In the ODS process, the used ILs acted as both extractant and catalyst with 30 wt % hydrogen peroxide aqueous solution as oxidant. The effects of Lewis acidity of ILs, IL's cation structure, molar ratio of O/S, reaction temperature, and different sulfur compounds on the sulfur removal of model oil were investigated. The results indicated that the sulfur removal for dibenzothiophene was affected by Lewis acidity of ILs and nearly reached 100 % by [C₆³MPy]Cl/FeCl₃ at conditions of 298 K, IL/oil mass ratio of 1/3, O/S molar ratio of 4/1, in 20 min. The sulfur removal of real gasoline reached 99.7 % after seven ODS runs in the [C₆³MPy]Cl/FeCl₃‐H₂O₂ system.     

Ionic Liquids as New Solvents for Textile Fiber Formation and Modification

Ionic liquids (ILs) with their special characteristics such as low melting point, high thermal stability, electrical conductivity, and good solubility in different chemical liquids, are widely used as new solvents for a large range of inorganic, organic, and polymeric materials. The development of ILs created a great untapped potential for commercial and academic applications to increase operating efficiencies of many chemical processes, including the processing of textiles. A summarizing introduction about ILs, their characterization, the general applications, and the major challenges is presented, followed by previous researches on using ILs for textile fiber formation and modification of their properties.     

Pechmann Reaction in Non-Chloroaluminate Acidic Ionic Liquids under Solvent-Free Conditions

Four non-chloroaluminate acidic ionic liquids have been used as catalysts for Pechmann condensations of phenols under solvent-free conditions. SO₃H-functionalized trifluoromethanesulfonate imidazolium ionic liquid has proved to be the most active catalyst. Ionic liquid loads as low as 5 mol % can be used leading to high yields with activated phenols at an oil bath temperature of 80 °C. The acidities of the four ionic liquids have also been tested using the Hammett method in dichloromethane. The results are consistent with their catalytic activities as observed in the Pechmann reaction of resorcinol. This methodology offers significant improvements for the synthesis of coumarins with regard to yield of products, simplicity in operation, and green aspects by avoiding toxic catalysts and solvents.     

Deep Probabilistic Learning Model for Prediction of Ionic Liquids Toxicity

Identification of ionic liquids with low toxicity is paramount for applications in various domains. Traditional approaches used for determining the toxicity of ionic liquids are often expensive, and can be labor intensive and time consuming. In order to mitigate these limitations, researchers have resorted to using computational models. This work presents a probabilistic model built from deep kernel learning with the aim of predicting the toxicity of ionic liquids in the leukemia rat cell line (IPC-81). Only open source tools, namely, RDKit and Mol2vec, are required to generate predictors for this model; as such, its predictions are solely based on chemical structure of the ionic liquids and no manual extraction of features is needed. The model recorded an RMSE of 0.228 and R2 of 0.943. These results indicate that the model is both reliable and accurate. Furthermore, this model provides an accompanying uncertainty level for every prediction it makes. This is important because discrepancies in experimental measurements that generated the dataset used herein are inevitable, and ought to be modeled. A user-friendly web server was developed as well, enabling researchers and practitioners ti make predictions using this model.     

Sulfonic Acid‐Functionalized Ionic Liquids as Metal‐Free,Efficient and Reusable Catalysts for Direct Amination of Alcohols

A series of sulfonic acid‐functionalized (SO₃H‐functionalized) ionic liquids was synthesized and used as metal‐free, highly selective and efficient catalysts for the direct amination of alcohols. Notably, the activities of the series of SO₃H‐functionalized ionic liquids were compared and a 92% isolated yield was obtained using 3‐tetradecyl‐1‐(butyl‐4‐ sulfonyl)imidazolium trifluoromethanesulfonate ([BsTdIM][OTf]) as the catalyst. Importantly, the catalytic system has wide substrate scope including benzylic, allyl, propargylic, aliphatic alcohols with sulfonamide, amide, carbamate, aromatic amine and N‐heterocyclic compounds. Interestingly, the system was also suitable for a multi‐gram scale direct amination of alcohols. Additionally, the reusable nature of [BsTdIM][OTf] makes this protocol more attractive and avoids the disposal and neutralization of acidic catalysts. Moreover, preliminary experiments indicated that this reaction should proceed via an S_N1 pathway.