1 - Alkyl-3-methylimidazolium tetrafluoroborates

Figure 3.1-4 Changes in liquefaction points for 1 -alkyl-3-methylimidazolium tetrafluoroborate and bis(trifyl)imide ionic liquids as a function of chain length, showing true melting points (solid fill) and glass transitions (open symbols).

Effect of Side Chain Length. The side chain bound to the cation also affects the Tm due to flexibility and excluded volume effects. To discuss the relation between side chain structure and Tm, the onium cation structure was fixed. The relation between the side chain structure and the thermal properties of imidazolium salts has already been reported by Seddon et al. [16, 17]. The effect of alkyl chain length of 1-alkyl-3-methylimidazolium tetrafluoroborate on the phase transition temperatures is... 

Both the melting point and viscosity of an ionic liquid are highly dependent on their purity and values in the literature differ accordingly. In the 1-alkyl-3-methylimidazolium tetrafluoroborate and hexafluorophosphate ionic liquids, which are the ones most widely used in catalysis thus far, halide impurities are usually present to varying degrees, due to the metathesis route commonly used for their preparation (see Section 2.3). The effect of different chloride concentrations present on the viscosity of [C4Ciim][BF4] is shown in Figure 2.5.1161... 

Fig. 9.3 Phase diagram for 1 -alkyl-3-methylimidazolium tetrafluoroborate ILs and liquid crystals showing the melting closed square) glass open square), and clearing circle) transitions as measured by differential scanning calorimetry (DSC) (Reproduced from Ref. [15] with kind permission of The Royal Society of Chemistry)...

JD Holbrey, KR Seddon. The phase behaviour of 1 -alkyl-3-methylimidazolium tetrafluoroborates ionic liquids and ionic liquid crystals, J Chem Soc, Dalton Trans 2133-2139, 1999. 

Hatakeyama, Y., Okamoto, M, Torimoto, T., Kuwabata, S. Nishikawa, K. (2009). Small-Angle X-ray Scattering Study of Au Nanoparticles Dispersed in the Ionic Liquids 1-Alkyl-3-methylimidazolium Tetrafluoroborate, J. Phys. Ghem. G113 3917-3922. 

Alkylation at nitrogen has been achieved by treating indole or pyrrole with alkyl halides in ionic solutions of potassium carbonate in l- -butyl-3-methylimidazolium tetrafluoroborate [bmim][BFJ <06TL2435>. Bis-protection of 3,3 -diiodo-2,2 -biindoles with Me, Boc, C02Et, or S02Ph has been described by Roy and Gribble <06SC3487>. 

One of the important new directions in the study of addition reactions of organozinc compounds to aldehydes is the use of ionic liquids. Usually, application of these compounds in reactions with common organometallic reagents has a serious problem ionic solvents are usually reactive toward them, particularly Grignard and organolithium derivatives. It has been recently reported that carbonyl compounds react with allylzinc bromide formed in situ from allyl bromide and zinc in the ionic liquid 3-butyl-l-methylimidazolium tetrafluoroborate, [bmim][BF4].285 Another important finding is that the more reactive ZnEt2 alkylates aldehydes in a number of ionic liquids at room temperature.286 The best yields (up to 96%) were obtained in A-butylpyridinium tetrafluoroborate, [bpy][BF4] (Scheme 107). 

Nishida, T., Tashiro, Y., and Yamamoto, M., Physical and electrochemical properties of l-alkyl-3-methylimidazolium tetrafluoroborate for electrolyte. Fluorine Chem., 120,135,2003. 

Figure 12.17 Raman spectra of l-alkyl-3-methylimidazolium tetrafluoroborate liquids, [C CiIm][Bp4] for n = 10, 8, 7, 6, 5, 4, 3, and 2. (Adapted from Hamaguchi, H., and Ozawa, R., Adv. Chem. Phys., 131,85-104, 2005. With permission.)...

A mixed reaction medium, composed of scC02 and ILs, has been defined as a new biphasic system by Advanced Industrial Science and Technology (AIST), and used for selective and efficient CC synthesis. For example, 1-alkyl-3-methylimidazolium salts represent a suitable system when used under supercritical conditions for the synthesis of CCs [156] from epoxides and C02. Kanawami et al. [159] have reported that the use of 1-octyl-3-methylimidazolium tetrafluoroborate under supercritical conditions resulted in a 100% conversion into PC, with 100% selectivity, within only a few minutes (Equation 7.15). 

Table 2.1 Melting points of l-alkyl-3-methylimidazolium tetrafluoroborate salts...

Alam, M. T., J. Masud, M. M. Islam, T. Okajima, and T. Ohsaka. 2011. Differential capacitance at Au(lll) in l-alkyl-3-methylimidazolium tetrafluoroborate based room-temperature ionic liquids. Journal of Physical Chemistry C 115 19797-19804. 

Figure 5 Separation of poly(phenols) using (A) 1-ethyl-3-methyl-imidazolium tetrafluoroborate, (B) 1-butyl-3-methylimidazolium tetrafluoroborate, and (C) 1-ethyl-3-methylimidazolium hexafluoro-phosphate. The electrolyte solution was a 150mmoll concentration of the ionic liquid in water. The fused-silica capillary column was 50cm x 50 m ID, operating voltage 16kV, and absorbance detection at the anode end at 240nm. (Reprinted with permission from Yanes EG, Gratz SR, Baldwin MJ, Robison SE, and Stalcup AM (2001) Capillary electrophoretic application of 1-alkyl-3-methyl-imidazolium-based ionic liquids. Analytical Chemistry 73 3838-3844 American Chemical Society.)...

Zhang D, Okajima T, Matsumoto F, Ohsaka T (2004) Electroreductirai of dioxygen in l-n-alkyl-3-methylimidazolium tetrafluoroborate room-temperature ionic liquids. J Electrochem Soc 151(4) D31-D37... 

However, when [RuCl2(p-cymene)(dppm)] (dppm = diphenylphosphinome-thane) was used as catalyst, a pronounced difference was established in the mechanism of arene hydrogenations in water compared to l-alkyl-3-methylimidazolium tetrafluoroborate ionic liquids. While in water the activation of the catalyst took place with chloride dissociation, in the ILs it was the arene ligand that was lost, furnishing the catalytically active dimeric Ru-species [Ru2(/u-Cl)3(dppm)2] (272). 

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