- Anion Analysis of Ionic Liquids and Ionic Liquid Purity Assessment by Ion Chromatography
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The simultaneous determination of halide impurities (fluoride, chloride, bromide, and iodide) and ionic liquid (IL) anions (tetrafluoroborate, hexafluorophosphate, and triflimide) using ion chromatography was developed with a basic, non-gradient ion chromatography system. The non-gradient method uses the eluent Na2CO3/NaHCO3in water/acetonitrile (70:30 v:v) on the AS 22 column to enable a rapid and simultaneous analysis of different IL and halide anions within an acceptable run-time (22 min) and with good resolution R of larger than 2.4, a capacity k′ between 0.4 and 5.1, selectivities α between 1.3 and 2.1, and peak asymmetries Asof less than 1.5. Halide impurities below 1 ppm (1 mg·L–1of prepared sample solution) could be quantified. A range of ionic liquids with tetrafluoroborate [BF4]–, hexafluorophosphate [PF6]–, and bis(trifluoromethylsulfonyl)imide (triflimide) [NTf2]–anions combined with cations based on imidazole, pyridine, and tetrahydrothiophene could be analyzed for their anion purity. The IL-cations do not influence the chromatographic results. With the analysis of 18 ILs differing in their cation-anion combination we could prove the general applicability of the described method for the anion purity analysis of ionic liquids with respect to halide ions. The IL-anion purity of most ILs was above 98 wt %. The highest IL-anion purity was 99.8 wt %, implying anion impurities of only 0.2 wt %. The used halide anion from the synthesis route was the major anion impurity, yet with chloride also bromide and fluoride (potentially from hydrolysis of [BF4]–) were often detected. When iodide was used, at least chloride but sometimes also bromide and fluoride was present. However, even if the IL-anion content is above 99 wt %, it does not necessarily indicate an ionic liquid devoid of other impurities. From the IC analysis, one can also deduce a possible cation impurity if one takes into account the expected (calculated) IL-anion content. A matching experimental and theoretical IL-anion content excludes, a higher experimental content indicates the presence of residual KBF4, NH4PF6, or LiNTf2salt from the halide to IL-anion exchange.
- Rutz, Christina,Schmolke, Laura,Gvilava, Vasily,Janiak, Christoph
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p. 130 - 135
(2017/02/05)
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- Ultrafast dynamics in aromatic cation based ionic liquids: A femtosecond raman-induced kerr effect spectroscopic study
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We studied the ultrafast dynamics of 40 aromatic cation based ionic liquids (ILs) by means of femtosecond Ramaninduced Kerr effect spectroscopy. The low-frequency Kerr spectra (ca. 0.3700 cm1) of the ILs were obtained from the Kerr transients by Fourier-Transform deconvolution analysis. The low-frequency Kerr spectra in the frequency range less than 200 cm-1 coming mainly from the intermolecular vibrations for the ILs were discussed in terms of (i) anion dependence, (ii) imidazolium cations vs. pyridinium cations, (iii) alkyl group dependence, and (iv) effect of methylation in aromatic cations. Several liquid properties, such as density, viscosity, electrical conductivity, and surface tension, of the present sample ILs at 293K were also estimated in this study. We clarified that the aromatic cation based ILs show a different relation of the first moment of the low-frequency spectral band to the bulk liquid parameter, which is the square root of surface tension divided by liquid density, from aprotic molecular liquids. The slope of the first moment to the bulk parameter for the aromatic cation based ILs is gentler than that for aprotic molecular liquids.
- Shirota, Hideaki,Kakinuma, Shohei,Takahashi, Kotaro,Tago, Akito,Jeong, Hocheon,Fujisawa, Tomotsumi
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supporting information
p. 1106 - 1128
(2016/10/11)
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- Octanol/water partition coefficients of pyridinium-based ionic liquids
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Nine pyridinium-based ionic liquids were synthesised, which include 1-butylpyridinium bromide ([BPYR] [Br]), 1-hexylpyridinium bromide ([HPYR][Br]), 1-octylpyridinium bromide ([OPYR][Br]), 1-hexylpyridinium bis(trifluoromethylsulfonyl)imide ([HPYR] [NTf2]), 1-octylpyridinium bis(trifluoromethylsulfonyl)imide ([OPYR][NTf2]), 1-hexylpyridinium trifluoromethanesulfonate ([HPYR] [TFO]), 1-octylpyridinium trifluoromethanesulfonate ([OPYR][TFO]), 1-hexylpyridinium tetrafluoroborate ([HPYR] [BF4]), 1-octylpyridinium I tetrafluoroborate ([OPYR][BF4]). The octanol/water partition coefficients (KOWs) of these pyridinium-based ionic liquids were determined by shake-flask method. It is found that the pyridinium-based ionic liquids measured in this work are extremely hydrophilic except for [OPYR] [NTf2]. It is also found that KOWs of [NTf2] ionic liquids were dependent on the concentration and high ionic liquids concentration in water leads to big KOW.
- Zhang, Teng,Wang, Yaquan
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p. 2819 - 2822
(2015/12/11)
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- H2O2/NaHCO3-mediated enantioselective epoxidation of olefins in NTf2-based ionic liquids and under ultrasound
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The bicarbonate-activated peroxide (BAP) system has been shown to constitute an excellent and versatile combination for the epoxidation of olefins. Herein, we demonstrate that the benign H2O 2/NaHCO3 oxidative combination can be used for the enantioselective epoxidation of olefins using a chiral manganese porphyrin as a catalyst. This unprecedented result was made possible by the use of an ionic liquid with ultrasound, which leads to the activation of Mn-porphyrin catalysis.
- Chatel, Gregory,Goux-Henry, Catherine,Mirabaud, Anais,Rossi, Thomas,Kardos, Nathalie,Andrioletti, Bruno,Draye, Micheline
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experimental part
p. 127 - 132
(2012/08/13)
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- A speedy one-pot synthesis of second-generation ionic liquids under ultrasound and/or microwave irradiation
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The present work describes an efficient one-pot synthesis of second-generation ionic liquids (ILs), combining in one step the Menshutkin reaction and anion metathesis. Working in a closed vessel under microwaves, or better still under simultaneous ultrasound and/or microwave irradiation, in a few minutes a series of ILs with 1-methylimidazole or pyridine cores were obtained in high yields (80?97% isolated). Under conventional heating, ILs could not be prepared in one pot in acceptable times and yields, whereas our protocol, carried out with commercially available equipment, was highly effective and reproducible. Moreover, 1H NMR analysis and ion-exchange chromatography showed that the present solventless procedure afforded satisfyingly pure ILs. CSIRO 2007.
- Cravotto, Giancarlo,Boffa, Luisa,L'Eveque, Jean-Marc,Estager, Julien,Draye, Micheline,Bonrath, Werner
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p. 946 - 950
(2008/03/17)
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