Additives ionic liquids

Ionic liquid Additional component(s) Coated electrode Enzyme(s) Analyte(s) detected Detection range (M) LOD (M) Method Ref. ... 

Zhang C., and Malhotra, S.V., Increased paraoxon detection by acetylcholinesterase inactivation with ionic liquid additives, Talanta, 67, 560-565, 2005. 

The results demonstrate that hydrogensulfate and tetrakis(hydrogensulfato)borate ionic liquids are highly interesting additives to mineral acids to form new, highly Bronsted-acidic catalysts. For example, it was found that a mixtures of sulphuric acid with only 2.2 mol% of [0MIM][B(HS04)4] ionic liquid yielded 90% more monoalkylbenzene product than the neat sulphuric acid catalyst under identical reaction conditions. This and related results are explained by an interplay of solubility and acidity effects caused by the ionic liquid additive. 

MNPs in Ionic Liquid/Additive Ligands or Polymeric Stabilizers... 

Suleman, M., Y. Kumar, and S. A. Hashmi. 2013. Structural and electrochemical properties of succinonitrile-based gel polymer electrolytes Role of ionic liquid addition. Journal of Physical Chemistry B 117 7436-7443. 

Figure 5 illustrates the stress relaxation of methylvinylsilicone vulcanizates containing ionic liquids. Addition of ionic liquids to the rubber caused the lower stress during the relaxation process. However, those stresses decreased more significantly for ionic liquids containing samples, which was reflected by relaxations rates (Table 3). The... 

Trzaska, M. Moszczynski P. On Influences Of Ionic Liquid Additives To Watts Bath On The Corrosion Resistance of Electrodeposited Nickel Surface Layers. Journal of Corrosion Measurements (JCM), Vol. 6, 2008... 

Furthermore, N-butyl-N -(4-pyridylheptyl)imidazolium bromide cells show a better long-term stability than that of 4-terf-butyl pyridine-based devices. These results indicate that the dye-sensitized solar cell devices based on the pyridinyl-functionalized ionic liquid additive can overcome the drawbacks of the volatile organic additive, and offer a feasible method to fabricate dye-sensitized solar cells in future practical applications (129). 

As explained in previous chapters (see Chaps. 1 and 2), an electrode of the first kind is one based on atoms or molecules and their corresponding cation or anion in solution. This type of electrode is most commonly used within the ionic liquids fields. Requirements for this class of reference electrode are that the atom or molecule used does not react with the ionic liquids. Additionally the corresponding cation or anion should be stable in the solvated form within the IL and should not have any corresponding undesirable chemical reactions with the IL components. If the reference electrode is based on a metal MImetal ion M" electrode system, and assuming the activity of the metal is 1 (which may not be true for specific cases), then the corresponding potential of the half-ceU is given by ... 

An ionic liquid-assisted solvothermal method is employed to prepare singlephase, oxygen-free, hexagonal NaGdF4 Eu nanorods with a visible quantum efficiency of 187 %, where l-ethyl-3-methylimidazolium bromide (CiinimBr) was used as template (Fig. 9.45). Most importantly, the presence of the ionic liquid additive is mandatory as only in that case phase pure hexagonal material is obtained that shows the exceptionally high quantum yields [64]. 

Fig. 11. Peak profile of pindolol obtained on Zorbax SB-Phenyl by the use of 10% ACN / 20 mM phosphate buffer pH = 2.9 mobile phase without any ionic liquid additives (0 mM ILs) and with addition of 10 mM BMIM Cl and 10 mM BMIM PFe. (Flieger Czajkowska-Zelazko, 2011b).

FIGURE 6.7 Effect of adding dioctyl phthalate (DOP) (a plasticizer), squares, or imidazoliuiii ionic liquid additives (bmimPF6 or hmimPF6), circles, to PMMA on Tg [5]. Reproduced by permission of the Royal Society of Chemistry. 

Bioreduction of para-bromo-2 -trifiuoroaceloplienone using ionic liquid additives. 

Suleman M, Kumar Y, Hashmi SA (2013) Structural and electrochemical properties of succinonitiile-based gel polymer electrolytes role of ionic liquid addition. J Phys Chem B 117(24) 7436-7443. doi 10.1021/jp312358x... 

From discussions with many people now worldng with ionic liquids, we know that, at least for the start of their work, the ability to buy an ionic liquid was important. In fact, a synthetic chemist searching for the ideal solvent for his or her specific application usually takes solvents that are ready for use on the shelf of the laboratory. The additional effort of synthesizing a new special solvent can rarely be justified, especially in industrial research. Of course, this is not only true for ionic liquids. Very probably, nobody would use acetonitrile as a solvent in the laboratory if they had to synthesize it before use. 

The choice of the anion ultimately intended to be an element of the ionic liquid is of particular importance. Perhaps more than any other single factor, it appears that the anion of the ionic liquid exercises a significant degree of control over the molecular solvents (water, ether, etc.) with which the IL will form two-phase systems. Nitrate salts, for example, are typically water-miscible while those of hexaflu-orophosphate are not those of tetrafluoroborate may or may not be, depending on the nature of the cation. Certain anions such as hexafluorophosphate are subject to hydrolysis at higher temperatures, while those such as bis(trifluoromethane)sulfonamide are not, but are extremely expensive. Additionally, the cation of the salt used to perform any anion metathesis is important. While salts of potassium, sodium, and silver are routinely used for this purpose, the use of ammonium salts in acetone is frequently the most convenient and least expensive approach. 

All three methods discussed above appear to provide equally high quality ionic liquid viscosity data. However, the rotational viscometer could potentially provide additional information concerning the Newtonian behavior of the ionic liquids. The capillary method has been by far the most commonly used to generate the ionic liquid viscosity data found in the literature. This is probably due to its low cost and relative ease of use. 

The size of the cation in the chloroaluminate ionic liquids also appears to have an impact on the viscosity. For ionic liquids with the same anion(s) and compositions, the trend is for greater viscosity with larger cation size (Table 3.2-2). An additional contributing factor to the effect of the cation on viscosity is the asymmetry of the alkyl substitution. Highly asymmetric substitution has been identified as important for obtaining low viscosities [17]. 

The addition of co-solvents to ionic liquids can result in dramatic reductions in the viscosity without alteration of the cations or anions in the system. The haloaluminate ionic liquids present a challenge, due to the reactivity of the ionic liquid. Nonetheless, several compatible co-solvents including benzene, dichloromethane, and acetonitrile have been investigated [33-37]. The addition of as little as 5 wt. % acetonitrile or 15 wt. % benzene or methylene chloride was able to reduce the... 

The reported densities of ionic liquids vary between 1.12 g cm for [(n-QHi7)(C4H9)3N][(CF3S02)2N] and 2.4 g cm for a 34-66 mol% [(CH3)3S]Br/AlBr3 ionic liquid [21, 23]. The densities of ionic liquid appear to be the physical property least sensitive to variations in temperature. For example, a 5 degree change in temperature from 298 to 303 K results in only a 0.3 % decrease in the density for a 50.0 50.0 mol % [EMIM]C1/A1C13 [17]. In addition, the impact of impurities appears to be far less dramatic than in the case of viscosity. Recent work indicates that the densities of ionic liquids vary linearly with wt. % of impurities. For example, 20 wt. % water (75 mol %) in [BMIM][BF4] results in only a 4 % decrease in density [33]. 

The solubility of water vapor in ionic liquids is of interest because ionic liquids are extremely hygroscopic. In addition, the solubility of water vapor in ILs is an excellent test of the strength of molecular interactions in these fluids. By using the gravi-... 

The early history of ionic liquid research was dominated by their application as electrochemical solvents. One of the first recognized uses of ionic liquids was as a solvent system for the room-temperature electrodeposition of aluminium [1]. In addition, much of the initial development of ionic liquids was focused on their use as electrolytes for battery and capacitor applications. Electrochemical studies in the ionic liquids have until recently been dominated by work in the room-temperature haloaluminate molten salts. This work has been extensively reviewed [2-9]. Development of non-haloaluminate ionic liquids over the past ten years has resulted in an explosion of research in these systems. However, recent reviews have provided only a cursory look at the application of these new ionic liquids as electrochemical solvents [10, 11]. 

A key criterion for selection of a solvent for electrochemical studies is the electrochemical stability of the solvent [12]. This is most clearly manifested by the range of voltages over which the solvent is electrochemically inert. This useful electrochemical potential window depends on the oxidative and reductive stability of the solvent. In the case of ionic liquids, the potential window depends primarily on the resistance of the cation to reduction and the resistance of the anion to oxidation. (A notable exception to this is in the acidic chloroaluminate ionic liquids, where the reduction of the heptachloroaluminate species [Al2Cl7] is the limiting cathodic process). In addition, the presence of impurities can play an important role in limiting the potential windows of ionic liquids. 

It must be noted that impurities in the ionic liquids can have a profound impact on the potential limits and the corresponding electrochemical window. During the synthesis of many of the non-haloaluminate ionic liquids, residual halide and water may remain in the final product [13]. Halide ions (Cl , Br , I ) are more easily oxidized than the fluorine-containing anions used in most non-haloaluminate ionic liquids. Consequently, the observed anodic potential limit can be appreciably reduced if significant concentrations of halide ions are present. Contamination of an ionic liquid with significant amounts of water can affect both the anodic and the cathodic potential limits, as water can be both reduced and oxidized in the potential limits of many ionic liquids. Recent work by Schroder et al. demonstrated considerable reduction in both the anodic and cathodic limits of several ionic liquids upon the addition of 3 % water (by weight) [14]. For example, the electrochemical window of dry [BMIM][BF4] was found to be 4.10 V, while that for the ionic liquid with 3 % water by weight was reduced to 1.95 V. In addition to its electrochemistry, water can react with the ionic liquid components (especially anions) to produce products... 

The physical properties of ionic liquids can often be considerably improved through the judicious addition of co-solvents [55-58]. Flowever, surprisingly, this approach has been relatively underutilized. Flussey and co-workers investigated the effect of co-solvents on the physical properties of [EMIM]C1/A1C13 ionic liquids [55, 56]. They found significant increases in ionic conductivity upon the addition of a variety of co-solvents. Figure 3.6-5 displays representative data from this work. The magnitude of the conductivity increase depends both on the type and amount of the co-solvent [55, 56]. 

The measurement of transport numbers by the above electrochemical methods entails a significant amount of experimental effort to generate high-quality data. In addition, the methods do not appear applicable to many of the newer non-haloalu-minate ionic liquid systems. An interesting alternative to the above method utilizes the NMR-generated self-diffusion coefficient data discussed above. If both the cation (Dr+) and anion (Dx ) self-diffusion coefficients are measured, then both the cation (tR+) and anion (tx ) transport numbers can be determined by using the following Equations (3.6-6) and (3.6-7) [41, 44] ... 

In addition to the obvious structural information, vibrational spectra can also be obtained from both semi-empirical and ab initio calculations. Computer-generated IR and Raman spectra from ab initio calculations have already proved useful in the analysis of chloroaluminate ionic liquids [19]. Other useful information derived from quantum mechanical calculations include and chemical shifts, quadru-pole coupling constants, thermochemical properties, electron densities, bond energies, ionization potentials and electron affinities. As semiempirical and ab initio methods are improved over time, it is likely that investigators will come to consider theoretical calculations to be a routine procedure. 

The field of reaction chemistry in ionic liquids was initially confined to the use of chloroaluminate(III) ionic liquids. With the development of neutral ionic liquids in the mid-1990s, the range of reactions that can be performed has expanded rapidly. In this chapter, reactions in both chloroaluminate(III) ionic liquids and in similar Lewis acidic media are described. In addition, stoichiometric reactions, mostly in neutral ionic liquids, are discussed. Review articles by several authors are available, including Welton [1] (reaction chemistry in ionic liquids), Holbrey [2] (properties and phase behavior), Earle [3] (reaction chemistry in ionic liquids), Pagni [4] (reaction chemistry in molten salts), Rooney [5] (physical properties of ionic liquids), Seddon [6, 7] (chloroaluminate(III) ionic liquids and industrial applications), Wasserscheid [8] (catalysis in ionic liquids), Dupont [9] (catalysis in ionic liquids) and Sheldon [10] (catalysis in ionic liquids). 

In the reaction between isoprene (IP) and methyl vinyl ketone (MVK), the selectivities between the two isomers produced in this reaction can be improved from 4 1 to 20 1 by the addition of a mild Eewis acid such as 2inc(II) iodide (5 mol %) to the ionic liquid [BMIM][PE(3] (Scheme 5.1-18). One of the key benefits of this is that the... 

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