L-Hexyl-3-methylimidazolium

Davis and co-workers have carried out the first examples of the Knoevenagel condensation and Robinson annulation reactions [61] in the ionic liquid [HMIM][PFg] (HMIM = l-hexyl-3-methylimidazolium) (Scheme 5.1-33). The Knoevenagel condensation involved the treatment of propane-1,3-dinitrile with a base (glycine) to generate an anion. This anion added to benzaldehyde and, after loss of a water molecule, gave l,l-dicyano-2-phenylethene. The product was separated from the ionic liquid by extraction with toluene. 

Whereas, Goharshadi et al. [16] have synthesized the ZnO nanoparticles of 60 nm (Fig. 8.4.) using a room temperature ionic liquid, l-hexyl-3-methylimidazolium bis (trifluoromethylsulfonyl)imide, Formation of ZnO was not observed when the ionic liquid was replaced by water. Also, in the absence of ultrasound, formation of ZnO was not observed which is very similar to the one as proposed in the previous case of ZnO dendritic nanostructures. 

Letcher, T.M. and Reddy, R, Ternary liquid-liquid equilibria for mixtures of l-hexyl-3-methylimidazolium (tetrafluoroborate or hexafluoroborate) + benzene + an alkane at T = 298.2 K and 1 atm, /. Chem. Thermodyn., 37, 415,2005. 

Letcher, T.M. et al.. Determination of activity coefficients at infinite dilution of solutes in the ionic liquid l-hexyl-3-methylimidazolium tetrafluoroborate using gas-liquid chromatography at the temperatures 298.15 K and 323.15 K, /. Chem. Eng. Data, 48, 1587, 2003. 

Figure 12.1 Numbering scheme in the l-hexyl-3-methylimidazolium cation, [CjCjImjL showing the three ring protons H2, H4, and H5.

We have shown [46] that the same situation as for [C4Cilm]+ exisfs for longer alkyl chain systems, at least for the l-hexyl-3-methylimidazolium cation. Raman spectra for [CgCjIm]+ cation systems have bands at 698, 623, and 601 cm (but no distinct band at -498 cm i). A comparison between typical experimental spectra is shown in Figure 12.15. 

PC propylene carbonate NMO 3-methyl-2-oxazolidinone TBAI tetrabutylammonium iodide AN acetonitrile PN propionitrile GN glutaronitrile MAN methoxyacetonitrile MPN 3-methoxypropionitrile TBP tert-butylpyridine HMIml l-hexyl-3-methylimidazolium iodide DMPIml 1,2- dimethyl-3-propy-limidazolium iodide SOC Sumitomo Osaka Cement Co. Ltd. 

HMIM]+ l-hexyl-3-methylimidazolium, [OMIM]+ l-octyl-3-methylimidazolium. 

Endres et al. [82] have demonstrated the suitability of an air- and water-stable ionic liquid for the electropolymerization of benzene. This synthesis is normally restricted to media such as concentrated sulfuric acid, liquid SO2 or liquid HF as the solution must be completely anhydrous. The ionic liquid used, l-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate, can be dried to below 3 ppm water, and this ionic liquid is also exceptionally stable, particularly in the anodic regime. Using this ionic liquid, poly(para-phenylene) was successfully deposited onto platinum as a coherent, electroactive film. Electrochemical quartz crystal microbalance techniques were also used to study the deposition and redox behavior of the polymer from this ionic liquid (Section 7.4.1) [83]. 

Our study of the relation between the solubility temperature and anion structure showed that the l-hexyl-3-methylimidazolium cation coupled with the anions, namely Cl, Br, BF4, and CIO4. Roughly, the ILs having smaller anions showed... 

Papageorgiou et al. reported the first example of an RTIL-based dye-sensitized solar cell system (Gratzel ceU). They found that l-hexyl-3-methylimidazolium iodide, denoted as HMI-I, melts at room temperature [8]. However, the viscosity of HMI-I is very high, at over 1000 mPas at room temperature. Therefore the /sc of DSSC when HMI-I is used (0.75 mA cm at the irradiation of 120,000 Lux [= 1 sun]) is much lower than that when an organic solvent is used (over 15 mA cm at 1 sun). This indicates that the slow diffusion of the iodide/triiodide redox... 

A study on lignin solubility in ionic liquids has shown that up to 20 wt% kraft wood lignin can be dissolved in 1,3-dimethylimidazolium methylsulfate, l-butyl-3-methylimidazolium methylsulfate and l-hexyl-3-methylimidazolium... 

Harris KR, Kanakubo M, Woolf LA (2007) Temperature and pressure dependence of the viscosity of the ionic liquids l-hexyl-3-methylimidazolium hexafluorophosphate and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. J Chem Eng Data 52 1080-1085... 

Our initial investigation of glycosylations in an ionic liquid suffered from a lack of reproducibility. We ultimately realized that chloride anions, which are the most likely expected impurity, are detrimental to the glycosylation reaction [14]. In order to prepare a chloride-free ionic liquid, we adopted the procedure shown in Scheme 3.1, with l-hexyl-3-methylimidazolium trifluoromethanesulfonimidide (C mim[NTf2]) as an example. 

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