- Polarity of tetraalkylammonium-based ionic liquids and related low temperature molten salts
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Solvatochromic measurements and 1H NMR spectroscopy have been used to investigate the overall polarity of tetraalkylammonium (R3N+-CH3 with R = n-C4H9; n-C8H17) based ionic liquids (IL) and low temperature molten salts (LTMS), respectively, as function of the counter anion. Solvent acidity (SA), solvent basicity (SB), polarizability (SP) and dipolarity (SdP) parameters have been determined according to the Catalán scale. [FeII(1,10-phenanthroline)2(CN)2] (Fe), 3-(4-amino-3-methylphenyl)-7-phenylbenzol[1,2-b:4,5-b′]difuran-2,6-dione (ABF), 3-(4-N,N-dimethylaminophenyl)-7-phenylbenzol[1,2-b:4,5-b′]-difuran-2,6-dione (DMe-ABF), 4-tert-butyl-2-(dicyanomethylene)-5-[4-(dimethylamino)benzylidene]-Δ3-thiazoline (Th), and 2-[4-(N,N-dimethylamino)benzylidene]malononitrile (BMN) have been used as solvatochromic polarity indicators. Significant correlations of the SB parameter of anion X- as a function of the chemical shift of the H-atoms of R3N+-CH3X- are presented and discussed. Thus, IL solvent basicity (SB) of the anion determines the interaction strength towards those CH-bonds in the direct vicinity of the ammonium nitrogen atom.
- Thielemann, Gabi,Spange, Stefan
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p. 8561 - 8567
(2017/08/14)
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- The electrochemical synthesis of polycationic clusters
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As a new method for the synthesis of chalcogen polycationic clusters, the electrochemical dissolution of elemental tellurium in ionic liquids (IL) or in liquid SO2 is presented. ILs used are ethylmethylimidazolium triflate [OTf]- and tetraalkylammonium triflylimide [NTf2]-. Tristriflylmethanide [CTf3]- was used as [BuMeIm][CTf3] as the electrolyte in SO2. This allowed for the isolation of [Te4][CTf3]2, [Te6][OTf]4, and [Te8][NTf2]2 containing the square [Te4]2+, the prismatic [Te6]4+, and the novel barrelane-shaped [Te8]2+. The compounds are novel compositions as they do not contain the usual halometalate anions, but rather common weakly coordinating anions. The 125Te NMR spectrum of an IL solution containing [Te8]2+ features only one broad signal at 2700 ppm. DFT calculations show that slight concerted displacements within the [Te8]2+ cluster lead to a fluxional molecular structure and a fast valence isomerism with a very low activation barrier of about 8 kJ mol-1. Anodic oxidation of elemental tellurium in ionic liquids provides access to the polycationic clusters [Te4]2+, [Te6]4+, and the new cluster [Te8]2+ with a barrelane structure (see picture). The characterization of the [Te8]2+ ion by 125Te NMR spectroscopy in solution showed a dynamic molecule with fast valence isomerism.
- Schulz, Christopher,Daniels, J?rg,Bredow, Thomas,Beck, Johannes
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supporting information
p. 1173 - 1177
(2016/01/20)
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- Preparation method and application of ionic liquid
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The invention relates to a preparation method of ionic liquid. The preparation method comprises the following steps: dissolving a water-soluble compound of which negative ions are trifluoro-alkyl sulfimide ions in water to prepare a first aqueous solution; dissolving a water-soluble compound of which positive ions are quaternary ammonium ions or imidazole ions in water to prepare a second aqueous solution; mixing the first aqueous solution and the second aqueous solution together according to a mole ratio of the negative ions to the positive ions of 1:(0.9-1.1), and then performing separation to obtain a crude product; rinsing the crude product to obtain a high-purity product; and performing vacuum drying on the high-purity product to obtain the ionic liquid. The preparation scheme of the ionic liquid provided by the invention is simple and feasible, and is conducive to industrialization; the prepared ionic liquid is high in purity, low in water content, and low in foreign ion content; and the ionic liquid of this type is high in thermal decomposition temperature and low in chroma, and can be used as an antistatic agent with high optical transparence requirements for high-temperature molding plastics.
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Paragraph 0035; 0036; 0037; 0038; 0039; 0040
(2017/01/12)
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- New insight into the nanostructure of ionic liquids: A small angle X-ray scattering (SAXS) study on liquid tri-alkyl-methyl-ammonium bis(trifluoromethanesulfonyl)amides and their mixtures
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We report a small angle X-ray scattering study on the liquid phase of a series of room temperature ionic liquids and their binary mixtures. The ionic liquids studied belong to the tri-alkyl-methyl-ammonium family with bis(trifluoromethanesulfonyl)amide as
- Pott, Tanja,Meleard, Philippe
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experimental part
p. 5469 - 5475
(2010/04/29)
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- Reaction kinetics in ionic liquids as studied by pulse radiolysis: Redox reactions in the solvents methyltributylammonium bis(trifluoromethylsulfonyl)imide and N-butylpyridinium tetrafluoroborate
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Rate constants for several reduction and oxidation reactions were determined by pulse radiolysis in three ionic liquids and compared with rate constants in other solvents. Radiolysis of the ionic liquids methyltributylammonium bis(trifluoromethylsulfonyl)imide (R4NNTf2), N-butylpyridinium tetrafiuoroborate (BuPyBF4), and N-butyl-4-methylpyridinium hexafluorophosphate (BuPicPF6) leads to formation of solvated electrons and organic radicals. In R4NNTf2 the solvated electrons do not react rapidly with the solvent and were reacted with several solutes, including CCl4, benzophenone, and quinones. In the pyridinium ionic liquids the solvated electrons react with the pyridinium moiety to produce a pyridinyl radical, which, in turn, can transfer an electron to various acceptors. The rate constant for reduction of duroquinone by the benzophenone ketyl radical in R4NNTf2 (k = 2 × 107 L mol-1 s-1) is much lower than that measured in water (k = 2 × 109 L mol-1 s-1) due to the high viscosity of the ionic liquid. Rate constants for electron transfer from the solvent-derived butylpyridinyl radicals in BuPyBF4 and BuPicPF6 to several compounds (k of the order of 108 L mol-1 s-1) also are lower than those measured in water and in 2-PrOH but are significantly higher than the diffusion-controlled rate constants estimated from the viscosity, suggesting an electron hopping mechanism through solvent cations. Electron transfer between methyl viologen and quinones takes place 3 or 4 orders of magnitude more slowly in BuPyBF4 than in water or 2-PrOH and the direction of the electron transfer is solvent dependent. The driving force reverses direction on going from water to 2-PrOH and is intermediate in the ionic liquid. Radiolysis of ionic liquid solutions containing CCl4 and O2 leads to formation of CCl3O2. radicals, which oxidize chlorpromazine (ClPz) with rate constants near 1 × 107 L mol-1 s-1, i.e., much lower than in aqueous solutions and close to rate constants in alcohols. On the other hand, the experimental rate constants in the ionic liquids and in water are close to the respective diffusion-controlled limits while the values in alcohols are much slower than diffusion-controlled.
- Behar,Neta,Schultheisz, Carl
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p. 3139 - 3147
(2007/10/03)
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