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Available from: Joao A. P. Coutinho, Jul 29, 2015
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    • "ase in the anion facility to form hydrogen bonds does not always improve the solubility with PEG in the solutions with PEG2050 – in fact it may provide stronger cation – anion interactions . Secondly , spectroscopic evidences indicate that cation – anion interactions are stronger in [ C n mim ] [ OTf ] ionic liquids than in [ C n mim ] [ NTf 2 ] ( Fernandes et al . , 2011 ; Bini et al . , 2007 ) and high hydrogen bond basicity of 1 - ethyl - 3 - methylimidazolium [ C 2 mim ] [ EtSO 4 ] ( practically of its anion ) ( Table 1 ) suggests that it can be rea - sonably assumed that these interactions are even stronger in the case of this ionic liquid . Finally , strong inter - and intra - molecular hydrogen bo"
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    ABSTRACT: This article principally reviews our research related to liquid–liquid and solid–liquid phase behavior of imidazolium- and phosphonium-based ionic liquids, mainly having bistriflamide ([NTf2]−) or triflate ([OTf]−) anions, with several aliphatic and aromatic solutes (target molecules). The latter include: (i) diols and triols: 1,2-propanediol, 1,3-propanediol and glycerol; (ii) polymer poly(ethylene glycol) (PEG): average molecular mass 200, 400 and 2050 – PEG200 (liquid), PEG400 (liquid) and PEG2050 (solid), respectively; (iii) polar aromatic compounds: nicotine, aniline, phenolic acids (vanillic, ferulic and caffeic acid,), thymol and caffeine and (iv) non-polar aromatic compounds (benzene, toluene, p-xylene). In these studies, the effects of the cation and anion, cation alkyl chain and PEG chain lengths on the observed phase behaviors were scrutinized. Thus, one of the major observations is that the anion – bistriflamide/triflate – selection usually had strong, sometimes really remarkable effects on the solvent abilities of the studied ionic liquids. Namely, in the case of the hydrogen-bonding solutes, the ionic liquids with the triflate anion generally exhibited substantially higher solubility than those having the bistriflamide anion. Nevertheless, with the aromatic compounds the situation was the opposite – in most of the cases it was the bistriflamide anion that favoured solubility. Moreover, our other studies confirmed the ability of PEG to dissolve both polar and non-polar aromatic compounds. Therefore, two general possibilities of application of alternative, environmentally acceptable, solvents of tuneable solvent properties appeared. One is to use homogeneous mixtures of two ionic liquids having [NTf2]− and [OTf]− anions as mixed solvents. The other, however, envisages the application of homogeneous and heterogeneous (PEG + ionic liquid) solutions as tuneable solvents for aromatic solutes.
    Full-text · Article · Oct 2014 · Arabian Journal of Chemistry
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    ABSTRACT: Introduction: Nowadays room temperature Ionic Liquids (RTILs) becomes major class of attention due to its numerous industrial applications in various fields. [1-3]. Due to its high cost and demand of ionic liquids for various application studies it becomes necessary to synthesize them in lab. After synthesis, characterization of ionic liquid becomes important task before their use for particular type of application for purity concern and their structural elucidation. In the present study, an imidazolium based ionic liquid, 1-butyl-2-methyl imidazolium [BMIM][BF4] synthesized in our laboratory, was characterized by various spectroscopy technique (UV-Vis, FT-IR, Mass and NMR spectroscopy). Experimental: In the synthesis of ionic liquids the possibility of impurities remaining in the ionic liquid samples (chloride, water and/or other solvents) has been reported [4]. All imidazolium based RTILs shows significant absorption in entire ultraviolet (UV) region and long tail in visible region [5] due to extended hydrogen bonded. Long tail absorption of RTILs is due to presence of large number of varied size energetically different supramolucular aggregates which shows specific absorption maxima [6]. Also, RTILs show weak absorption at 300 nm and at longer wavelength due to imidazolium salt and not due to impurity [7]. Because of this, UV-vis spectroscopy becomes useful tool for absorption study of imidazolium based ionic liquids. Absorption spectra of [BMIM][BF4] is presented in this work using a 8453 UV-Visible Spectrophotometer. Fourier transform infrared spectroscopy (FT-IR) spectra of imidazolium based ionic liquids reveals information of interaction between imidazolium cation with different inorganic anions. Imidazolium based RTILs show different absorption in IR spectra due to relative position of anion with respect to imidazolium cation [8]. Structural factors like position of cation and anion determine the physical and chemical property of the RTILs. Therefore, in present study [BMIM][BF4] was carefully analysed with FT-IR spectroscopy for structure determination of the molecule. The equipment used is a Jasco FT/IR-600 Plus FT-IR spectrometer.
    Full-text · Conference Paper · Mar 2012
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    ABSTRACT: Many separation processes in petrochemical and refining industries are applied to close boiling point compounds and/or azeotropic mixtures which make difficult the application of simple distillation, requiring alternative separation processes. Ionic liquids, with their unique and tunable properties, may constitute an advantageous alternative as extractive solvents in separation processes that involve hydrocarbon systems. In this work, a review on the experimental data available for ternary systems composed of ionic liquids and hydrocarbons is reported. The gathered information was shown to be essential in the understanding of the molecular interactions and of the effect of the various structural features of both the ionic liquids and the hydrocarbons on their phase behavior, allowing the development of guidelines for the choice of the most suitable ionic liquid for hydrocarbon separation. To be able to carry out the design and selection of new and improved ionic liquids, the development of predictive models and their validation is required, since the experimental screening of the huge number of potential ionic liquids is not feasible. In this context, the ability of COSMO-RS (COnductor-like Screening MOdel for Real Solvents) as a predictive tool to describe the liquid–liquid equilibria of ternary systems composed of ionic liquids and hydrocarbons, is evaluated. The results obtained with COSMO-RS testify its ability for the qualitative, and in some cases the quantitative, description of the phase behavior of the systems studied.
    No preview · Article · Apr 2012 · ChemInform
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