Applications of ionic liquids

Ionic liquids have recently gained popularity in the scientific community owing to their special properties and characteristics. One of the reasons why ionic liquids have been termed “green solvents” is due to their negligible vapour pressure. Their use in electrochemical, biological and metal extraction applications is discussed. Wide research has been carried out for their use in batteries, solar panels, fuel cells, drug deliveries and biomass pretreatments. This work aims to consolidate the various findings from previous works in these areas. DOI 10.1002/tcr.201100036     

Synthesis and properties of trigeminal tricationic ionic liquids

Novel trigeminal tricationic ionic liquids (TTILs) have been successfully synthesized in high yields by means of Menschutkin quaternization via an S(N)1 mechanism. This reaction presents a new convenient method for transforming glycerol into multifunctional compounds. The physical properties of a series of TTILs were characterized by using a variety of techniques. The prepared salts were tested for antimicrobial activity. Electrochemical characterization of TTILs was also performed, which allowed the estimation of the conductivity of these new compounds, to establish their electrochemical stability window and capacitance properties over a wide range of temperatures. A good correlation of the physical properties of TTILs with capacitance values was observed.     

Long-alkyl-chain quaternary ammonium lactate based ionic liquids

A new group of quaternary ammonium lactate based ionic liquids have been prepared and characterized. Didecyldimethylammonium (DDA) and benzalkonium (BA) D,L- and L-lactates are air-stable, hydrophilic, surface-active salts. They are very effective antibacterial and antifungal agents, especially the DDA lactates, against Streptococcus mutants and Candida albicans. Their activities are comparable or more effective than the original benzalkonium chloride. In addition, they have been shown to be good insect-feeding deterrents. However, they are poor antifungal agents for wood preservation. The toxicity of the DDA and BA lactates has also been studied and the results are presented in this paper.     

离子液体体系催化甲酸分解制氢研究(英文)

研究了离子液体作为介质对在有机胺存在时甲酸分解制氢的影响。结果表明,离子液体的引入能明显促进甲酸分解反应,特别是BMImCl的引入。基于此同时为了取代挥发性有机胺、发展具有实用价值的甲酸分解制氢体系,设计和制备了一系列胺基功能化离子液体,并作为反应介质和助剂应用于甲酸均相分解反应中。其中钌-胺基功能化离子液体-甲酸钠(Ru-i-Pr2NEMImCl-HCOONa)甲酸分解制氢体系具有优良的催化性能,相应的TOF600 mol/mol/h。可以使用非挥发性的离子液体取代传统的挥发性胺,从而为发展具有实际应用价值、高效而清洁的甲酸分解制氢体系打下基础。     

Synthesis and properties of chiral ammonium-based ionic liquids

New chiral ammonium-based ionic liquids containing the (1R,2S,5R)-(-)-menthyl group can be easily and efficiently prepared under ambient conditions. The preparation and characterization of trialkyl[(1R,2S,5R)-(-)-menthoxymethyl]ammonium salts is reported. The salts have been demonstrated to be air- and moisture-stable under ambient conditions and can be readily used in a variety of standard experimental procedures. The single-crystal X-ray structure of butyldimethyl[(1R,2S,5R)-(-)-menthoxymethyl]ammonium chloride has been determined. The chiral, room-temperature ionic liquids have been characterized by physical properties such as specific rotation, density, viscosity, thermal degradation, and glass transition temperature. Trialkyl[(1R,2S,5R)-(-)-menthoxymethyl]ammonium chloride prototype ionic liquids have also been found to exhibit strong antimicrobial and high antielectrostatic activities.     

Task-specific ionic liquids bearing 2-hydroxybenzylamine units: synthesis and americium-extraction studies

The synthesis of two task-specific ionic liquids (TSILs) bearing 2-hydroxybenzylamine entities is described. These compounds are based on an imidazolium substructure onto which one hydrobenzylamine-complexing moiety is grafted. We have demonstrated that, whether pure or diluted, TSIL is able to extract americium ions. Furthermore, recovery of americium from the IL phase into a receiving phase can be achieved under acidic conditions. A possible mechanism for the metal-ion partitioning is presented, in which the extraction system is driven by an ion-exchange mechanism.     

Water-soluble ionic liquids as novel stabilizers in suspension polymerization reactions: engineering polymer beads

Aqueous solutions of ionic liquids have been used as novel and environmentally friendly reaction media to synthesize and "control" the size of different cross-linked polymer beads by suspension polymerization reactions. It was found that the investigated ionic liquids can act as novel stabilizing agents of the suspensions as a result of their surface-active properties. The results have demonstrated that the average size of polymer beads can be varied from the macro- to the nanoscale and their surface area can also be "adjusted" by this synthetic approach. Furthermore, the use of a combination of ionic liquids and water for the synthesis of polymers, the simple isolation of the products formed in this polymerization procedure, as well as the recycling of the continuous medium for further reactions open up possibilities for the development of "new and green" polymerization processes.     

Recent developments of task-specific ionic liquids in organic synthesis

Abstract

Task-specific ionic liquids (TSILs) have received increased attention over the past few years as it is possible to form any specific ionic liquid (IL) composition depending upon user's need of the desired physical, chemical, and biological properties. These fascinating materials have shown promising results in various areas such as organic synthesis, catalysis, and specially recent emerging trend of use as functionalized ILs for chiral and nanoparticle synthesis. Present review gives an update of recent developments in the field of TSILs with emphasis on their applications in organic synthesis.     

室温离子液体在分离科学研究中的新进展

室温离子液体作为一种重要的绿色溶剂,由于在金属离子、小分子有机物的萃取分离,气体吸附分离以及作为液相和气相色谱固定相等许多分离过程中体现出高分离效率和高选择性的特点,正在成为分离科学研究的前沿领域.着重总结了从2003—2006年的室温离子液体在分离科学领域中的新进展,并对其应用领域和发展前景做了展望.提出进一步加强离子液体的功能化和固定化技术及其在分离科学中的应用基础研究,探索离子液体有效的回收和再循环利用的新方法,是离子液体今后在分离科学研究中的一系列重要内容.     

Applications of functionalized ionic liquids

Recent developments of the synthesis and applications of functionalized ionic liquids (including dual-functionalized ionic liquids) have been highlighted in this review. Ionic liquids are at-tracting attention as alternative solvents in green chemistry, but as more functionalized ILs are pre-pared, a greater number of applications in increasingly diverse fields are found.     

Comparison of physicochemical properties of new ionic liquids based on imidazolium, quaternary ammonium, and guanidinium cations

More than 50 ionic liquids were prepared by using imidazolium, quaternary ammonium, and guanidinium cations and various anions. In these series, different cationic structures such as 1-benzyl-3-methylimidazolium [Bzmim]+, 1,3-dibenzylimidazolium [BzmiBz]+, 1-octyl-3-methylimidazolium [C8mim]+, 1-decyl-3-methylimidazolium [C10mim]+, tricapryl-methylammonium [Aliquat]+, benzyltriethylammonium [BzTEA]+, phenyltrimethylammonium [PhTMA]+, and dimethyldihexylguanidinium [DMG]+ were combined with anions, p-toluenesulfonate [TSA](-), dicyanoamide [DCA]-, saccharine (2-sulfobenzoic acid imide sodium salt) [SAC]-, trifluoroacetate [TFA]-, bis(trifluoromethanesulfonyl)imide [Tf2N]-, trifluoromethanesulfonate [TfO]-, and thiocyanate [SCN]-. Important physical data for these ionic liquids are collated, namely solubility in common solvents, viscosity, density, melting point and water content. Apart from the viscosity, the Newtonian and non-Newtonian behavior of these ionic liquids is also disclosed. Stability of these ionic liquids under thermal, basic, acidic, nucleophilic, and oxidative conditions was also studied. The features of the solid-liquid phase transition were analyzed, namely the glass transition temperature and the heat capacity jump associated with the transition from the non-equilibrium glass to the metastable supercooled liquid. A degradation temperature of each ionic liquid was also determined. Comparisons of the properties of various ionic liquids were made.     

Catalytic applications of metal nanoparticles in imidazolium ionic liquids

Metal nanoparticles (MNPs) with a small diameter and narrow size distribution can be prepared by H(2) reduction of metal compounds or decomposition of organometallic species dissolved in ionic liquids (ILs). MNPs dispersed in ILs are catalysts for reactions under multiphase conditions. These soluble MNPs possess a pronounced surfacelike rather than single-site like catalytic properties. In other cases the MNPs are not stable and tend to aggregate or serve as reservoirs of mononuclear catalytically active species.     

Tetraalkylphosphonium-based ionic liquids

Ionic liquids are salts that are liquid at or near room temperature. Their wide liquid range, good thermal stability, and very low vapor pressure make them attractive for numerous applications. The general approach to creating ionic liquids is to employ a large, unreactive, low symmetry cation with and an anion that largely controls the physical and chemical properties. The most common cations used in ionic liquids are N-alkylpyridinium and N,N′-dialkylimidazolium. Another very effective cation for the creation of ionic liquids is tetraalkylphosphonium, [PR₁R₂R₃R₄]⁺. The alkyl groups, R_n, generally are large and not all the same. The halide salts of several phosphonium cations are available as starting materials for metathesis reactions used to prepare ionic liquids. The large phosphonium cations can combine with relatively large anions to make viscous but free flowing liquids with formula mass greater than 1000 g mol⁻¹. Some other more massive salts are waxes and glasses. The synthesis and the physical, chemical, and optical properties of phosphonium-ionic liquids having anions with a wide range of masses were measured and are reported here.     

Recent advances in ionic liquids: green unconventional solvents of this century: part I

Abstract

The present overview describes ionic liquids as alternate, attractive solvents of today and tomorrow in organic synthesis. Since this subject is too wide and developments have been too fast, only a recent account is presented on indispensable carbon-carbon bond forming named reactions such as Knoevenagel, Michael Aldol, Biginelli Reaction, and so on, which has never been done before exclusively.     

离子液体中的不对称催化反应*

对价格昂贵的手性催化剂进行回收和重复利用是目前不对称催化领域面临的难题之一,受到学术界和工业界的共同关注。化学家们已经尝试了许多方法,其中使用离子液体来替代常规有机溶剂使催化剂得到分离和重新使用已经引起他们极大的兴趣。本文综述了近年来在离子液体中进行不对称催化反应的研究进展,对离子液体中过渡金属和有机小分子催化的各种反应进行重点介绍,强调了离子液体不但在催化剂回收方面有独特优势,而且在许多反应中能够提高催化效率。