Ionic Liquids ILs

Over the past ten years, ILs have moved out of the realm of academic study and are being used in a diverse range of industrial processes [44]. It is true to say that the apphcation of ILs in the synthesis of pharmaceuticals and fine chemicals has been hampered by much green wash and focus on single-issue sustainability claims such as that ILs are better than all other solvents because they have essentially no vapor pressure and are not classified as volatile organic compounds (VOCs). Other factors hmiting take-up have been the lack of ecotoxicity and life 

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Interest in using ionic liquid (IL) media as alternatives to traditional organic solvents in synthesis [1 ], in liquid/liquid separations from aqueous solutions [5-9], and as liquid electrolytes for electrochemical processes, including electrosynthesis, primarily focus on the unique combination of properties exhibited by ILs that differentiate them from molecular solvents. 

A wide variety of physical properties are important in the evaluation of ionic liquids (ILs) for potential use in industrial processes. These include pure component properties such as density, isothermal compressibility, volume expansivity, viscosity, heat capacity, and thermal conductivity. However, a wide variety of mixture properties are also important, the most vital of these being the phase behavior of ionic liquids with other compounds. Knowledge of the phase behavior of ionic liquids with gases, liquids, and solids is necessary to assess the feasibility of their use for reactions, separations, and materials processing. Even from the limited data currently available, it is clear that the cation, the substituents on the cation, and the anion can be chosen to enhance or suppress the solubility of ionic liquids in other compounds and the solubility of other compounds in the ionic liquids. For instance, an increase in allcyl chain length decreases the mutual solubility with water, but some anions ([BFJ , for example) can increase mutual solubility with water (compared to [PFg] , for instance) [1-3]. While many mixture properties and many types of phase behavior are important, we focus here on the solubility of gases in room temperature IFs. 

The use of ionic liquids (ILs) to replace organic or aqueous solvents in biocatalysis processes has recently gained much attention and great progress has been accomplished in this area lipase-catalyzed reactions in an IL solvent system have now been established and several examples of biotransformation in this novel reaction medium have also been reported. Recent developments in the application of ILs as solvents in enzymatic reactions are reviewed. 

When the same [NiI (NHC)2] complexes are employed as alkene dimerisation catalysts in ionic liquid (IL) solvent [l-butyl-3-methylimidazolium chloride, AICI3, A-methylpyrrole (0.45 0.55 0.1)] rather than toluene, the catalysts were found to be highly active, with no evidence of decomposition. Furthermore, product distributions for each of the catalyst systems studied was surprisingly similar, indicating a common active species may have been formed in each case. It was proposed that reductive elimination of the NHC-Ni did indeed occur, as outlined in Scheme 13.8, however, the IL solvent oxidatively adds to the Ni(0) thus formed to yield a new Ni-NHC complex, 15, stabilised by the IL solvent, and able to effectively catalyse the dimerisation process (Scheme 13.9) [25-27],... 

Ionic liquid solvents are non-volatile and non-toxic and are liquids at ambient temperature. Originally, work was concerned with battery electrolytes. These ionic liquids (IL) show excellent extraction capabilities and allow catalysts to be used in a biphasic system for convenient recycling (Holbrey and Seddon, 1999). IFP France has commercialized a dimerization process for butenes using (LNiCH2R ) (AlCU) (where L is PRj) as an IL and here the products of the reaction are not soluble in IL and hence separate out. The catalyst is very active and gives high selectivity for the dimers. 

Significant progress has been made in the application of ionic liquids (ILs) as alternative solvents to C02 capture because of their unique properties such as very low vapour pressure, a broad range of liquid temperatures, excellent thermal and chemical stabilities and selective dissolution of certain organic and inorganic materials. ILs are liquid organic salts at ambient conditions with a cationic part and an anionic part. 

Table 5. Electrochemical stability window of ionic liquids (IL) at the glassy carbon (potentials [V/ expressed versus Ag/Agf 0.01M in DMSO reference) [26 /.

Table 4.3 Microwave heating effects of doping organic solvents with ionic liquids (IL) A and B (data from [63]). a ...

The very first report on the use of ionic liquids as soluble supports was presented by Fraga-Dubreuil and Bazureau in 2001 [102]. The efficacy of a microwave-induced solvent-free Knoevenagel condensation of a formyl group on the ionic liquid (IL) phase with malonate derivatives (E1CH2E2) catalyzed by 2 mol% of piperidine was studied (Scheme 7.89). The progress of the reaction could be easily monitored by 1H and 13C NMR spectroscopy, and the final products could be cleaved from the IL... 

The term ionic liquid (IL) refers to a class of liquids that are composed solely of ions. It is a synonym of molten salt. Although molten salt imphcitly means a high-temperature hquid that is prepared by melting a crystalline salt, IL includes a new class of ionic compounds that are liquids at the ambient temperature [1]. Thus, IL in a narrow sense often stands for room-temperature ionic liquid (RIL). In the present chapter, IL is used in a broader sense and, if necessary, RIL is used to clarify that it is liquid at the ambient temperature. The history of ILs has aheady been reviewed [2]. 

Imidazolium-based ionic liquids (ILs) have been used extensively as media for the formation and stabilization of transition-metal nanoparticles [14—17]. These 1,3-dialkylimidazolium salts (Figure 15.3) possess very interesting properhes they have a very low vapor pressure, they are nonflammable, have high thermal and electrochemical stabilities, and display different solubilities in organic solvents [18-20]. 

According to the nature of their counter anion, ionic liquids (ILs) can dissolve a large amount of carbohydrates. In 2003, Moreau and co-workers reported the acid-catalyzed dehydration of fructose in a microbatch reactor at 80°C using l-butyl-3-methyl imidazolium tetrafluoroborate (BM1M BF4 ) (hydrophilic), and l-butyl-3-methyl imidazolium hexafluorophosphate (BMIM Fe (hydrophobic) (Scheme 10) [95]. 

Ionic liquids (ILs) are, together with water and supercritical fluids, one of the few alternative media for environmentally friendly processes, which seem to have more possibility of industrial application in the next 10 years. The range of demonstrated or proposed applications of ILs is extraordinary, going from their use as nonvolatile, non-flammable solvents in organic synthesis to catalysts, materials for aiding separations and gas capture, advanced heat transfer fluids, lubricants, antistatics, and so on [2 ]. Surpassing in magnitude the number of potential uses is the number of possible IL compositions, estimated to be in the billions [5]. The term ionic liquids includes all compounds composed exclusively by ions that are liquid... 

An ionic liquid (IL) is a substance that is composed entirely of ions, and is a liquid at room temperature. Frequently the ionic liquid consists of organic cations and inorganic anions, although it is not limited to these combinations. While some people have said that the ionic liquid can have a high melting temperature such as in the case of the molten salt form of NaCl, the most commonly held understanding of this term is one that has a melting point of less than 100 °C, more preferably less than 50 °C. For example, many preferred ionic liquids are liquid at room temperature, or less. 

Countercurrent chromatography (CCC) is a separation technique that uses a support-free liquid stationary phase [1]. Since the mobile phase is also liquid, biphasic liquid systems are used. Ionic liquids (ILs), as a new class of solvenfs, should be evaluafed in CCC. 

Separation of metal ions based on solvent extraction is widely used in hydrometallurgy, environmental cleanup, and advanced fuel cycles. The focus of this chapter will be on the use of ionic liquids (ILs) as advanced and... 

Pure ionic liquids (ILs) are solvents that remain colorless and transparent throughout almost the whole visible and near-infrared (NIR) spectral regions. This property coupled with excellent stability makes ILs very attractive optical solvents that may be used for the absorption and fluorescence studies of dissolved substances, as well as for monitoring the reactions... 

Generally room-temperature ionic liquids (ILs) consist mostly of ions [1]. In these liquids the Coulomb interaction plays a major role, in contrast to the situation in ordinary molecular liquids where only dipolar and... 

Keeping these facts in mind, there is an obvious interest in being able to apply NMR to the chemistry of and in ionic liquids (ILs). This chapter focuses on the main achievements in the field, giving a tutorial-like approach to NMR spectroscopy in ILs. If you prefer a more review-like source of information that aims at completeness and a more historical style, please refer to the recent literature [2]. 

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