1- Ethyl-3-methylimidazolium salt

Matsumoto K, Hagiwara R, Yoshida R, et al. Syntheses, structures and properties of 1-ethyl-3-methylimidazolium salts of fluorocomplex anions. Dalton Trans. 2004. 144-149. 

Matsumoto, K., Hagiwara, R., Yoshida, R., Ito, Y, Maze], Z., Benkic, R, Zemva, B., Tamada, O., Yoshino, H., and Matsubara, S., Syntheses, structures and properties of l-ethyl-3-methylimidazolium salts of fluorocomplex anions, /. Chem. Soc. Dalton Trans., 144-149, 2004. 

Water soluble Rh/tppts and Rh/tppms complexes dissolved in nonaqueous media such as the ionic liquids, l-ethyl-3-methylimidazolium or l-n-butyl-3-methylimidazolium salt have also been used as catalysts in the hydroformylation of 1-pentene employing a two phase system.15,16 The yields obtained were 16-33% (TOF=59-103 h 1) without any leaching of the rhodium from the ionic liquid to the aldehydes/feedstock phase. Rh/PPh3 catalysts exhibited higher rates (TOF=333 h 1) for the same biphasic reaction albeit with leaching of rhodium due to the uncharged nature of the catalytic system.15... 

Symmetry is another factor to affect Tm. The salts with symmetric ions generally show higher Tm than those with asymmetric ones. For example, 1,3-dimethylimidazolium tetrafluoroborate showed higher Tm than 1-methylimi-dazolium or l-ethyl-3-methylimidazolium salts, as shown in Figure 3.1. In the case of tetraalkylammonium salts, their Tm also increased with increasing symmetry of the cation structure [18]. This tendency is understood to relate to the structural effect on crystallinity [19], i.e., highly symmetric ions are more efficiently packed into the crystalline structure than unsymmetric ones. Other kinds of chain structures such as polyether [20], perfluorocarbon [21], etc. [22] are obviously also effective in influencing thermal properties. 

The IL polymers were prepared from polymerizable anions and free imidazolium cations. To investigate the effect of the anion structure on the properties, four kinds of IL monomers were synthesized by neutralizing A-ethylimidazole with acryhc acid, -styrenesulfonic acid, vinylsulfonic acid, and vinylphosphonic acid, respectively, as shown in Figure 29.6 [32]. Table 29.1 summarizes the properties of IL monomers composed of the polymerizable anion and an ethylimidazolium cation. They are liquid at room temperature and show quite low Tg s in the range of —100 to —60°C. EImVS showed the lowest Tg of 95°C among these four IL monomers. In addition it showed the highest ionic conductivity of about 10 S cm at 30°C, which is comparable to that of the best ILs such as the l-ethyl-3-methylimidazolium salts. 

The fluorescent probe 4-aminophthalimide (63) as well as its /V,/V-diethyl homomorph (89) were used by Samanta and coworkers148 149 to study the polarity and fluorescence dynamics in l-alkyl-3-methylimidazolium salts. The alkyl groups were variously ethyl, butyl and octyl and the anions were nitrate, tetrafluoroborate, hexafluorophosphate and bis(triflyl)imide. Similar conclusions were reached concerning the effects of alkyl chain length and anion as those obtained by Carmichael and Seddon142 using Nile Red. The solvation dynamics were found to depend on the viscosity of the media. Further use of 63 in l-butyl-3-methylimidazolium hexafluorophosphate was reported by Ingram and... 

Recently, there has been considerable interest in developing molten salts that are less air and moisture sensitive. Melts such as l-methyl-3-butylimidazolium hexa-fluorophosphate [211], l-ethyl-3-methylimidazolium trifluoromethanesulfonate [212], and l-ethyl-3-methylimidazolium tetrafluoroborate [213] are reported to be hydro-phobic and stable under environmental conditions. In some cases, metal deposition from these electrolytes has been explored [214]. They possess a wide potential window and sufficient ionic conductivity to be considered for many electrochemical applications. Of course if one wishes to take advantage of their potential air stability, one loses the opportunity to work with the alkali and reactive metals. Further, since these ionic liquids are neutral and lack the adjustable Lewis acidity common to the chloroaluminates, the solubility of transition metal salts into these electrolytes may be limited. On a positive note, these electrolytes are significantly different from the chloroaluminates in that the supporting electrolyte is not intended to be electroactive. 

Table 4.5 A comparison of the melting points of l-ethyl-3-methylimidazolium and 1 -ethyl-2,3-dimethylimidazolium salts...

The electrochemical reduction of TiCU and ZrCl4, in chloroaluminate melts and other molten salt systems, to lower valent halides has been fairly widely studied [4-7]. This has also been extended to studies of centered hexanuclear Zr halide clusters. Thus, ambient temperature AICI3 -1 -ethyl-3-methylimidazolium chloride (ImCl) molten salts, both basic (40/60 mol% AlCls/ImCl) and acidic (60/40 mol% AICI3 /ImCl), were used in an electrochemical investigation of clusters... 

The combination of quaternary ammonium chloride salt, such as l-ethyl-3-methylimidazolium chloride (EMIC), with... 

The electrochemistry of Cd(II) was investigated at different electrodes (GC, polycrystalline tungsten, Pt, Ni) in a basic l-ethyl-3-methylimidazolium chloride/tet-rafluoroborate, at room temperature molten salt [312], and in acidic zinc chloride-l-ethyl-3-methylimidazolium [284]. 

Formation of several successive layers of bulk intermetallic compounds has been shown. Also, Lee et al. [480] have detected, during Al UPD, the formation of two alloys on polycrystalline Au electrodes from acidic l-ethyl-3-methylimidazolium chloroaluminate that melt at room temperature. Moreover, in the Al UPD region, fast phase transition between these two intermetallic compounds has been evidenced. Later, the same group of researchers [481] has performed EQCM studies on Al deposition and alloy formation on Au(lll) in ambient temperature molten salts/benzene mixtures. 

Fuller, J., Carlin, R. T., DeLong, H. C., and Haworth, D., Structure of 1-ethyl-3-methylimidazolium hexafluorophosphate Model for room temperature molten salts, Chem. Commun., 299-300, 1994. 

Carper, W. R., Pflug, J. L., and Wilkes, J. S., Dual spin probe NMR relaxation studies of ionic structure in l-ethyl-3-methylimidazolium chloride-AlClg molten-salts, Inorg. Chim. Acta, 202,89,1992. 

The field of I Ls as we know it today only really blossomed after Wilkes and Zaworotko reported air- and moisture-stable l-ethyl-3-methylimidazolium nitrate, nitrite, sulfate, and acetate salts in 1992 [35]. These provided early examples of the more stable and structurally well-defined second generation of ILs, that can be used in air for a wide variety of reactions, and for which many examples are commercially available. Second-generation ILs are now the most widely used members of the IL family (Figure 6.3), although most of the common examples contain halogenated counteranions, such as BF4, PF6 , and SbF6 [36]. 

Another type of room temperature ionic liquids are typically the salts between cations like 1-butyl-3-methylimidazolium (BMI+), l-ethyl-3-methylimidazolium, and 1-butyl-pyridinium (see Scheme) and anions like BF7, PFq, CF3COO , CF3S03 and (CF3S02)2] T [29, 30]. By suitably selecting the cation and the anion, we can design ionic liquids that are nonvolatile, nonflammable, chemically stable, highly... 

Excision reactions are sometimes accompanied by redox chemistry. For example, dissolution of the 2D solid Na4Zr6BeCli6 in acetonitrile in the presence of an alkylammonium chloride salt results in simultaneous reduction of the cluster cores (144). Here, the oxidation product remains unidentified, but is presumably the solvent itself. As a means of preventing such redox activity, Hughbanks (6) developed the use of some room temperature molten salts as excision media, specifically with application to centered zirconium-halide cluster phases. A number of these solids have been shown to dissolve in l-ethyl-2-methylimidazolium chloride-aluminum chloride ionic liquids, providing an efficient route to molecular clusters with a full compliments of terminal chloride ligands. Such molten salts are also well suited for electrochemical studies. 

The reactivity of haloalkanes in alkylation reactions also decreases with increasing chain length. In general, syntheses of salts with short alkyl substituents are more complex due to the low boiling points of the haloalkanes. The most frequently used halide salt in this field, l-ethyl-3-methylimidazolium chloride ([EMIM] Cl), is typically synthesized in an autoclave with the chloroethane cooled to below its boiling point (12 °C) before addition. 

Treatment of a quaternary halide salt Q+X with a Lewis acid MX results in the formation of a salt with the composition Q+MX +i . In general, more than just one anion species is formed, depending on the relative proportions of MX and the halide salt Q X. A representative example is the reaction of l-ethyl-3-methylimidazolium chloride [EMIMJC1 with AICI3 (Scheme 2.3). 

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