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1.
Addition of a small amount of polar solvent (i.e., modifier) to CO2 in packed column supercritical fluid chromatography (SFC) has shown major improvements in both polar analyte solubility and interaction of the polar analyte with the stationary phase. Recently, the addition of an ionic component (i.e., additive) to the primary modifier by one of us has been shown to extend even further the application of SFC to polar analytes. In this work, the effect of various ionic additives on the elution of ionic compounds, such as sodium 4-dodecylbenzene sulfonate and sodium 4-octylbenene sulfonate, has been studied. The additives were lithium acetate, ammonium acetate, tetramethylammonium acetate, tetrabutylammonium acetate, and ammonium chloride dissolved in methanol. Three stationary phases with different degrees of deactivation were considered: conventional cyanopropyl, deltabond cyanopropyl, and bare silica. The effect of additive concentration and additive functionality on analyte retention was investigated. Sodium 4-dodecylbenzene sulfonate was successfully eluted using all the additives with good peak shape under isocratic/isobaric/isothermal conditions. Different additives, however, yielded different retention times and in some cases different peak shapes. 相似文献
2.
The low vapor pressure and the versatility of the physico-chemical properties of ionic liquids make them really attractive as an alternative for conventional molecular solvents. The knowledge of their physico-chemical properties (viscosity, conductivity, miscibility with organic solvents and anion-cation interactions) has appeared mandatory for better targeting their applications, although it is generally still lacking or incomplete.This work promotes capillary electrophoresis instrumentation as an integrated apparatus for measurement of viscosity, conductivity and absorbance of pure ionic liquids and ionic liquid-molecular solvent mixtures. Compared to current conventional techniques, the assets of this instrumentation for this purpose are the combined availability of a pressure delivery system, power supply, diode array absorbance detector and thermoregulation device, allowing unattended, automatic and easy operation, involving minimum sample handling. Most importantly, the required sample volume can be reduced to about 50 μL, making this protocol very cost-effective. A protocol was optimized with respect to time, sample consumption and data reliability for the determination of these physico-chemical parameters. Ionic liquids selected for method development and validation differed in the nature of their cation (butyl- and ethyl-methylimidazolium) and anion (trifluoromethanesulfonate and bis(trifluoromethanesulfonyl)imide). Various molecular solvents were mixed with these ionic liquids (acetonitrile, methanol, dimethylformamide and trifluoroethanol) and the same physico-chemical properties were determined by optimized methods. The knowledge of these data should be of great support in various application areas, including the development of new separation media for capillary electrophoresis and chromatographic techniques. 相似文献
3.
Jean-Claude Jacquesy 《Journal of fluorine chemistry》2006,127(11):1484-1487
This is a summary of a lecture presented at the 100th Anniversary, Moissan Symposium in Paris on Friday 10th November 2006.In HF/SbF5, Vinca alkaloids react selectively at the D’ring of the molecule. In the presence of CHCl3 (or CCl4), vinorelbine yields 20′,20′-difluoro-3′,4′-dihydrovinorelbine (vinflunine), presently in phase III experimentation for treatment of bladder cancer and non small cell lung cancer. 相似文献
4.
Hervé Clavier 《Journal of organometallic chemistry》2005,690(15):3585-3599
New recyclable imidazolium-tagged ruthenium catalysts have been developed to perform olefin metathesis in room temperature ionic liquids (RTILs). High level of recyclability combined with a high reactivity were obtained in the ring-closing metathesis (RCM) of a variety of di- or tri-substituted and/or oxygen-containing dienes. Extremely low residual ruthenium levels were detected in the RCM products (average of 7.3 ppm per run). Several examples of olefin cross-metathesis (CM) have been also studied. 相似文献
5.
F. Mauvy 《Journal of solid state chemistry》2005,178(6):2015-2023
The two hitherto unknown compounds Bi14P4O31 and Bi50V4O85 were prepared by the direct solid-state reaction of Bi2O3 and (NH4)H2PO4 or V2O5, respectively. Bi14P4O31 crystallizes in a C-centred monoclinic symmetry (C2/c space group) with the unit-cell parameters: , , and β=93.63(1)° (Z=16). The symmetry of Bi50V4O85 is also monoclinic (I2/m space group) with lattice parameters of , , and β=90.14(1)° (Z=2). Both structures correspond to a fluorite-type superstructure where the Bi and P or V atoms are ordered in the framework. An idealized structural model is proposed where the structures result of the stacking of mixed atomic layers of composition [Bi14M4O31] and [Bi18O27] respectively. This new family can be formulated Bi18−4mM4mO27+4m with M=P, V and where the parameter m (0?m?1) represents the ratio of the number of [Bi14M4O31] layers to the total number of layers in the sequence. Bi14P4O31 corresponds to m=1 when Bi50V8O85 corresponds to m=1/3. In this last case, the structural sequence is simply one [Bi14V4O31] layer to two [Bi18O27] layers. As predicted by the proposed structural building principle, Bi14P4O31 is not a good ionic conductor. The conductivity at 650 °C is 4 orders of magnitude lower from those found in Bi46M8O89 (M=P, V) (m=2/3) and Bi50V4O85 (m=1/3). 相似文献
6.
Protection of carbonyls as acetals or ketals using Brønsted acidic ionic liquid [Hmim]BF4 as catalyst as well as solvent was investigated. Satisfactory results were obtained for the protection of carbonyls as cycloacetals or ketals with diols. The product can be separated conveniently from the reaction system, and the ionic liquid can be reused after removal of water. 相似文献
7.
Shu-Liang Zang Qing-Guo Zhang Ming Huang Bin Wang Jia-Zhen Yang 《Fluid Phase Equilibria》2005,230(1-2):192-196
This paper reports that an ionic liquid (IL) has been prepared by directly mixing InCl3 and 1-methyl-3-ethylimidazolium chloride (EMIC) with molar ratio 1/1 under dry argon atmosphere. The densities, and surface tension of the pure IL were determined at temperature range of 293.15 to 343.15 ± 0.1 K. The volumetric properties and the properties of surface for ionic liquid based on group III were discussed by Glasser's theory and Yang's interstice model. 相似文献
8.
Mark P Scott 《European Polymer Journal》2003,39(10):1947-1953
Room temperature ionic liquids (ILs) based on imidazolium salts, were found to be excellent plasticizers for poly(methyl methacrylate), with improved thermal stability, and the ability to reduce glass transition temperatures to near 0 °C. Because ILs have environmentally benign properties, they can be used in place of traditional chemicals in numerous products and processes. In this work, PMMA was formulated using dioctyl phthalate, DOP, as a traditional plasticizer, and properties were compared to PMMA plasticized with two ILs: butyl methylimidazolium/hexafluorophosphate, [bmim+][PF6−], and hexyl methylimidazolium/hexafluorophosphate, [hmim+][PF6−]. Formulations incorporated up to 30 vol.% DOP and 50 vol.% ILs. Bulk and plasticized polymers were characterized for glass transition temperature, elastic modulus, and the thermal stability of the plasticizers. 相似文献
9.
《Comptes Rendus Physique》2013,14(7):531-541
This is a review of the wetting properties of solid helium on various solid substrates. Due to its extreme purity and to its very fast growth dynamics, solid helium 4 is often considered as a model system in materials science. Several wetting phenomena have been studied with helium 4 crystals, namely contact angles on solid substrates with variable roughness, wetting on graphite where epitaxial growth takes place, the roughening transition as a function of film thickness, the wetting of grain boundaries by the liquid phase. 相似文献
10.
A new and green method for the synthesis of α,β-unsaturated arylsulfones had been achieved through the condensation of aromatic aldehydes,chloroacetonitrile,benzenesulfinic acid sodium salt in the presence of l-butyl-3-methyl imidazolium hydroxide([bmim]OH) in EtOH under reflux.The ionic liquid was recovered and recycled for subsequent reactions.The advantages of this protocol were non-toxic,easy work-up and good yields. 相似文献