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1-Alkyl-3-Methylimidazolium

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Ulrich S Schubert – One of the best experts on this subject based on the ideXlab platform.

  • cellulose molecular properties in 1 alkyl 3 methylimidazolium based ionic liquid mixtures with pyridine
    Carbohydrate Polymers, 2010
    Co-Authors: Jurgen Vitz, Ulrich S Schubert, N P Yevlampieva, Evgeny Rjumtsev

    Abstract:

    A study of the viscometric and dynamooptical (flow birefringence) properties of cellulose samples in mixtures of 1-Alkyl-3-Methylimidazolium-based ionic liquids with pyridine was carried out. It was established that the mixtures provide stable molecular dispersed cellulose solutions which are suitable for the determination of the characteristics of the dissolved macromolecules. The viscous and dynamooptical properties of cellulose in ionic liquid/pyridine mixtures, cadoxen (CdO/ethylenediamine), and in cadoxen/water at low solute concentrations were compared, and the behavior of cellulose in these solvents was discussed. It was found that the values of the refractive index of 1-alkyl-3methylimidazolium-based ionic liquid/pyridine mixtures are close to the refractive index of cellulose in their media. The extremely low refractive index increment (|dn/dc| = (0.004 ± 0.001) cm3 g−1) for cellulose in 1-ethyl-3-methylimidazolium diethylphosphate and pyridine ([EMIM]Et2PO4/pyridine (1:1)) allowed to confirm that the cellulose monomer unit is not optically isotropic and is characterized by a small in value and positive in sign anisotropy of polarizability (� a = +1.0 × 10 −25 cm 3

  • Cellulose molecular properties in 1-Alkyl-3-Methylimidazolium-based ionic liquid mixtures with pyridine
    Carbohydrate Polymers, 2010
    Co-Authors: Jurgen Vitz, N P Yevlampieva, Evgeny Rjumtsev, Ulrich S Schubert

    Abstract:

    A study of the viscometric and dynamooptical (flow birefringence) properties of cellulose samples in mixtures of 1-Alkyl-3-Methylimidazolium-based ionic liquids with pyridine was carried out. It was established that the mixtures provide stable molecular dispersed cellulose solutions which are suitable for the determination of the characteristics of the dissolved macromolecules. The viscous and dynamooptical properties of cellulose in ionic liquid/pyridine mixtures, cadoxen (CdO/ethylenediamine), and in cadoxen/water at low solute concentrations were compared, and the behavior of cellulose in these solvents was discussed. It was found that the values of the refractive index of 1-alkyl-3methylimidazolium-based ionic liquid/pyridine mixtures are close to the refractive index of cellulose in their media. The extremely low refractive index increment (|dn/dc| = (0.004 ± 0.001) cm3 g−1) for cellulose in 1-ethyl-3-methylimidazolium diethylphosphate and pyridine ([EMIM]Et2PO4/pyridine (1:1)) allowed to confirm that the cellulose monomer unit is not optically isotropic and is characterized by a small in value and positive in sign anisotropy of polarizability (� a = +1.0 × 10 −25 cm 3

  • homogeneous tritylation of cellulose in 1 butyl 3 methylimidazolium chloride
    Macromolecular Bioscience, 2007
    Co-Authors: Tina Erdmenger, Claudia Haensch, Richard Hoogenboom, Ulrich S Schubert

    Abstract:

    1-Alkyl-3-Methylimidazolium-based ionic liquids, having chloride as a counter ion, were studied for cellulose solubility; and the influence of different alkyl chain lengths was also investigated. The alkyl chain length was incrementally varied from ethyl to decyl to determine structure-dissolution properties; a distinct odd-even effect was observed for short chain lengths. In addition, the tritylation of cellulose was performed in 1-butyl-3-methylimidazolium chloride using pyridine as base. The influences of reaction time and the ratio of trityl chloride per cellulose monomer unit on the degree of substitution were investigated in detail by elemental analysis and 1H NMR spectroscopy. A DS of around 1 was obtained after 3 h reaction time using a six fold excess of trityl chloride.

Kenneth R. Seddon – One of the best experts on this subject based on the ideXlab platform.

  • Antibiofilm activities of 1-Alkyl-3-Methylimidazolium chloride ionic liquids
    Green Chemistry, 2009
    Co-Authors: Louise Carson, Peter K. W. Chau, Martyn J. Earle, Manuela A. Gîlea, Brendan Gilmore, Sean P. Gorman, Maureen T. Mccann, Kenneth R. Seddon

    Abstract:

    Microbial biofilms are ubiquitous in nature and represent the predominant mode of growth of microorganisms. A general characteristic of biofilm communities is that they tend to exhibit significant tolerance to antimicrobial challenge compared with planktonic bacteria of the same species The antibiofilm activity of a series of 1-Alkyl-3-Methylimidazolium chloride ionic liquids has been evaluated against a panel of clinically significant microbial pathogens, including MRSA. A comparison of antimicrobial activity against planktonic bacteria and established biofilms is presented. In general, these ionic liquids possess potent, broad spectrum antibiofilm activity.

  • Crystal and liquid crystalline polymorphism in 1-Alkyl-3-Methylimidazolium tetrachloropalladate(II) salts
    Journal of Materials Chemistry, 2001
    Co-Authors: Christopher Hardacre, John D. Holbrey, Paul B. Mccormac, S.e.j. Mcmath, Mark Nieuwenhuyzen, Kenneth R. Seddon

    Abstract:

    1-Alkyl-3-Methylimidazolium tetrachloropalladate(II) salts ([Cn-mim]2[PdCl4], n = 10, 12, 14, 16, 18) containing a single, linear alkyl-chain substituent on the cation have been synthesised and their behaviour characterised by differential scanning calorimetry, polarising optical microscopy and small-angle X-ray scattering. The salts display thermotropic polymorphism, exhibiting both crystal–crystal transitions and, for n = 14–18, the formation of a thermotropic smectic liquid crystalline phase.

  • polarity study of some 1 alkyl 3 methylimidazolium ambient temperature ionic liquids with the solvatochromic dye nile red
    Journal of Physical Organic Chemistry, 2000
    Co-Authors: Adrian J Carmichael, Kenneth R. Seddon

    Abstract:

    The polarity of ambient-temperature ionic liquids based on the 1-Alkyl-3-Methylimidazolium cation was probed using the solvatochromic dye Nile Red. The polarity of these liquids was shown to be comparable to that of the lower alcohols. The effects on polarity with changing anion and 1-alkyl group are reported. Copyright © 2000 John Wiley & Sons, Ltd.

Marek Kosmulski – One of the best experts on this subject based on the ideXlab platform.

  • Permittivities of 1-Alkyl-3-Methylimidazolium Tetrafluoroborates and Hexafluorophosphates
    Croatica Chemica Acta, 2007
    Co-Authors: Marek Kosmulski, Krystyna Marczewska-boczkowska, Pawel Zukowski, Jan Subocz, Czesław Saneluta

    Abstract:

    Permittivities of 1-Alkyl-3-Methylimidazolium tetrafluoroborates, hexafluorophosphates, and tetrafluoroborate-chloride mixtures (alkyl = butyl, hexyl, octyl or decyl) were determined from the capacitance of a specially designed capacitor, which was measured as the function of frequency over the range from 0.001 Hz to 5 MHz. The measurement setup was tested against molecular liquids. Water and methanol gave relatively stable results, which comply with the permittivities known from the literature over a frequency range from 30 kHz to 3 MHz. The apparent permittivity measured at lower frequencies was highly overestimated. With low-temperature ionic liquids, the plateau in the apparent permittivity as the function of frequency was narrower, and it was observed between 1 and 3 MHz. Yet, the apparent permittivities in the plateau region are still overestimated, at least for l-butyl-3-methylimidazolium salts.

  • Low-temperature ionic liquids immobilized in porous alumina.
    Journal of Colloid and Interface Science, 2005
    Co-Authors: Marek Kosmulski, Czesław Saneluta, Mikolaj Szafran, Krystyna Marczewska-boczkowska

    Abstract:

    The pores in an aluminum oxide matrix can be completely filled with 1-Alkyl-3-Methylimidazolium tetrafluoroborates, hexafluorophosphates, triflates, and bis(trifluoromethylsulfonyl)imides. This possibility can be utilized to produce solid electrolytes for batteries and fuel cells.

  • thermal stability of low temperature ionic liquids revisited
    Thermochimica Acta, 2004
    Co-Authors: Marek Kosmulski, Jan Gustafsson, Jarl B Rosenholm

    Abstract:

    Abstract The range of thermal stability of low temperature ionic liquids published in the literature (often >400 °C) is severely overrated. The decomposition temperature calculated from fast TGA scans in a protective atmosphere does not imply a long-term thermal stability below that temperature. Even at temperatures as low at 200 °C, 1-Alkyl-3-Methylimidazolium phosphates (alkyl = C4–C10) and 1-decyl-3-methylimidazolium triflate showed a slow, but appreciable mass loss. On the other hand, 1-butyl-3-methylimidazolium triflate was stable at 200 °C. The carbonization occurred in most studies salts irrespectively of the nature of the anion (hexafluorophosphate, triflate), but the salts with a shorter side chain (C4) did not show changes in their color after conditioning for 10 h at 200 °C in air. 1-Butyl-3-methylimidazolium triflate shows extremely good wettability against aluminum oxide and silver at elevated temperatures. Addition of silica (amorphous or quartz) accelerates the thermal decomposition of 1-Alkyl-3-Methylimidazolium phosphates and triflates at 200 °C, while the effect of other ceramic powders (titania, alumina) is less significant.