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Nicotine: On the Potential Role of Ionic Liquids for Its Processing and Purification
Abstract
Marked solubility differences of nicotine in the ionic liquids [C(2)mim][NTf(2)], [C(2)mim][EtOSO(3)], and [C(n)mim]Cl, 6 <or= n <or= 10, are observed through the analysis of the corresponding phase diagrams. These show the potential of commonly used ionic liquids to extract and purify this important compound. From a fundamental standpoint, the generally enhanced solubility of nicotine in these ionic liquids as compared to that of aromatic and aliphatic hydrocarbons can be assigned to the presence of the aromatic pyridine ring and the large aliphatic N-methyl-pyrrolidine residue.
... The latter can be explained using the case of ionic liquids with [NTf 2 ] À anion and benzene (Łachwa et al., 2006a,b): (i) the anion-aromatic ring interactions are planar and occur mainly between the benzene hydrogen atoms and oxygen atoms in the anion sulfonyl groups while (ii) ionic liquid cations are situated above and below the aromatic rings and their interactions are mostly p-p interactions between the two aromatic rings or interactions between acidic hydrogen in the imidazolium cation and p electrons in the aromatic ring. This structure significantly supports the solubility of virtually non-polar aromatic compounds such as arenes (Łachwa et al., 2006a) but as well of the polar aromatics, for instance nicotine and aniline (Calado et al., 2013a;Visak et al., 2007) in ionic liquids. It was also found (Łachwa et al., 2006a,b) that the extension of the cation alkyl chains -non-polar domainssupports the formation of the cage-like structure and provides higher solubility of arenes. ...
... The aforementioned distinction stands as well in the case of the solutions of ionic liquids with polar aromatic compounds such as nicotine and aniline. Ionic liquids 1-ethyl-3-methylimidazolium bistriflamide [C 2 mim][NTf 2 ] and 1-butyl-3-methylimidazolium [C 4 mim][NTf 2 ] were found to be completely soluble with these aromatics (Calado et al., 2013a;Visak et al., 2007) Solutions of ionic liquids with diverse aliphatic and aromatic solutes 2004). The same stands for nicotine which is an emerging aqueous pollutant in discarded waters from tobacco industry (Sponza, 2002), ground waters (Stuart et al., 2012;Jurado et al., 2012) and urban waste waters (Benotti and Brownawell, 2007;Mun˜oz et al., 2008 ), in separation of aromatic compounds -both polar and non-polar -from their aqueous and non-aqueous solutions. ...
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.
... The goal is to use less volatile and less toxic solvent for nicotine removal as well as for its extraction and purification from natural resources. Many efforts have been undertaken to find environmentally friendly solvents which can be applied for nicotine processing [5][6][7]. ...
Bachground: Nicotine is highly addictive plant derived alkaloid and the most important species in humanuse today is Nicotianatabacum. There are direct health effects of chronic nicotine exposure. Even in lowdoses, nicotine causes vasoconstriction and other cardiovascular effects related to catecholamine release andpromote angiogenesis, neuroteratogenicity, and possibly some cancers. Methods: A preliminary investigationto analyze the nicotine contained in Iraqi tobacco leaves was carried out using gas chromatography-massspectrometry (GC-MS). Nicotine is an alkaloid, and alkali methanol and Lipophilic solventsystem methods(LSS) have been extracted and determined by GC-MS from tobacco leaves. Results: The detection limit fornicotine was for non-selective monitoring at the ppm level and for selective detection at the nanogram level.This is a simple method of thin layer chromatography (TLC) and chromatography mass spectrometry (GCMS)for the tobacco leave analysis of nicotine. The final purity of nicotine is 99%. Conclusion :the methodswhich used in this study gave very high purity of nicotineafter converting the crude nicotine to its esters.
Induction of somatic embryogenesis from shoot apex in pines
Ionic liquid (IL)-containing polymers garner attention for electrochemical applications. This article overviews recent experimental and theoretical studies of polymer electrolytes that would be likely to cultivate new theoretical and computational frameworks for IL-containing polymers. The first two sections outline the uniqueness of ILs that differentiates them from inorganic salts in polymers and explore deviation from the concept of the metaphor “room-temperature molten salt.” Such distinct properties include (1) large intrinsic dipole moment and electronic polarizability, (2) hydrogen bonding, (3) π-interactions, (4) a broad distribution of charges over the entire ion, and (5) the anisotropy of the ions. Moreover, the complexity of these properties substantially increases when the ions are polymerized. Indeed, their exceptional features would overcome the hurdle due to a trade-off between ionic conductivity and mechanical robustness in inorganic salt-doped polymers. Given these facts, the rest of the article focuses on emerging trends in the study of the dielectric response, phase separation, ion conductivity, and mechanical robustness of the polymer electrolytes, highlighting outstanding observations in experiments that may inspire existing theory and simulation. Our discussion also includes improving computational complexity for IL-containing polymers. To this end, recent machine learning studies that consider ILs and polymer liquids are presented.
Abstract
In this study, an acidic nicotine‐based ionic liquid supported on magnetic nanoparticles ([NicTC]HSO4@MNPs) was synthesized and characterized by different techniques. The activity of this catalyst was evaluated in a multi‐component reaction of 2‐aminobenzothiazole, aldehydes/dialdehydes and β‐ketoesters/1,3‐diketones to afford a series of novel mono‐ and bis‐4H‐pyrimido[2,1‐b]benzothiazole derivatives. In addition, mild reaction conditions, high yields, excellent selectivity as well as easy recovery and reusability of the catalyst, make this method an economic and environmentally‐benign process. A nicotine‐based ionic liquid supported on magnetic nanoparticles ([NicTC]HSO4@MNPs) was synthesized, characterized and used as an efficient and reusable catalyst for the one‐pot multi‐component synthesis of a series of novel mono‐ and bis‐4H‐pyrimido[2,1‐b]benzothiazole derivatives.
We study the phase behavior of a block copolymer and ionic liquid mixture using the Landau theory of Leibler and field-theoretic techniques in polymer physics. Our weak-segregation theory of microphase separation accounts for electrostatic screening, the excluded volume effect, and the dielectric contrast between the species. The results of the phase diagrams for ionic liquid-containing poly(styrene-block-2-vinylpyridine) and poly(ethylene oxide-block-styrene) qualitatively agree with the observed transitions between the ordered microstructures corresponding to lamellae, hexagonally packed cylinders, and body-centered cubic lattices. We show that moderate changes in the model parameters for molecular volumes and nonbonded interactions can qualitatively alter the trend of the phase boundaries. Specifically, our theory highlights the following features: (a) The effect of the dielectric contrast between the constituent blocks may cause a driving force for microphase separation, whereas the effect of electrostatic screening is likely minimal. (b) Reentrance into a lamellar phase, hexagonally packed cylinder phase, or disordered phase may occur when the volume fraction of an ionic liquid is increased. (c) Asymmetry in the molecular volumes and interactions between the cation and anion in an ionic liquid may cause substantial changes in the phase boundaries. The present results also suggest that despite its simplicity, the Born solvation energy of the ions can be used to consider the dissolution of an ionic liquid in block copolymers when the dielectric contrast is large.
A new nicotine-based organocatalyst supported on silica nanoparticles (Fe(III)-NicTC@nSiO2) was prepared and characterized by different techniques. A series of 1,5-benzodiazepines derivatives were smoothly synthesized via the tandem process, starting from o-phenylenediamine and dimedone (or 1,3-cyclohexanedione), followed by addition of aldehyde in the presence Fe(III)-NicTC@nSiO2 catalyst in water at room temperature. The Fe(III)-NicTC@nSiO2 was also applied as an efficient catalyst for the selective synthesis of mono- and bis-1,5-benzodiazepines. Excellent yields and selectivity, short reaction time, mild conditions, and reusability of the catalyst are valuable features of this method.
Graphical Abstract
A new supported nicotine-based organocatalyst was prepared, characterized and applied for the synthesis of 1,5-benzodiazepines in water at room temperature.
This work is a continuation of previous studies on phase demixing - salting-out effects in aqueous nicotine solutions. Thus, pH measurements were performed, allowing a brief analysis of the existing hydrogen bond interactions. Salting-out effects the related experimental cloud point shifts provoked by the addition of two inorganic salts, potassium nitrate and sodium sulfate, which have not hitherto been studied, were determined. Analysis of the current and previously reported salting-out/or salting-in phenomena in nicotine aqueous solutions was performed. In this respect, five studied salts were included: four inorganic salts (sodium chloride, potassium nitrate, sodium sulfate and trisodium phosphate (Na3PO4)), and ionic the liquid 1-ethyl-3-methylimidazolium ethyl sulfate ([C(2)mim][EtSO4], commercial name ECOENG212 (R)). Based on pH measurements, the effective Gibbs energies of hydration and the ionic strengths of the respective ternary solutions were calculated and plotted against the related cloud-point shifts caused by the addition of the salts. For the studied salts, the results and diagram obtained within this work may be used to predict the cloud-points shifts, based on the related quantities of the salts added and/or the molar Gibbs energies of hydration and/or ionic strengths requested in each case.
In this work, the performance of inorganic salt sodium chloride and ionic liquid (molten salt) ECOENG212 as salting-out media for the separation of nicotine from its aqueous solutions was examined. In this respect, liquid–liquid equilibria of the ternary solutions nicotine + water + NaCl and nicotine + water + ECOENG212 were determined at ambient pressure, 0.1 MPa, and humidity at three temperatures. The related phase diagrams were constructed by means of both cloud points and chemical analysis of phases in equilibrium (tie-line data). The latter were used to calculate two important separation parameters: partition coefficients of nicotine and separation factors. The effects of the initial compositions of the solutions and of the temperature on the phase behavior and partition coefficients were analyzed and discussed. The results obtained, particularly in the case of sodium chloride as a salt, clearly showed that both investigated salts provided good salting-out media for the efficient and sustainable separation of nicotine from solutions with water.
In this mini review several particular cases of ionic liquid solution behavior are discussed, namely solutions of ionic liquids with aliphatic alcohols, polyalcohols, arenes, chloromethanes and poly(ethyleneglycol) as well as salting-out and salting-in effects. The presented cases clearly expose ionic liquids as being diverse and versatile sustainable solvents that exhibit flexible phase behavior and, consequently, variable phase diagrams. These can be tuned either by changing the length of the alkyl chain(s) of the ionic liquid’s cation (and/or sometimes the anion), or by introducing a different aliphatic nature to the other solution constituent (e.g., by varying polymer chain length or the number of carbon atoms in chloromethanes). Sometimes, the evolution of the phase diagrams is fine and continuous, showing several consecutive stages, revealing both qualitative and quantitative changes. Finally, the diversity and versatility of ionic liquids are viewed as important features that contribute to their efficiency as tunable solvents or salting media.
Liquid–liquid equilibria (LLE) of the solutions of imidazolium ionic liquids having bistriflamide [NTf2]− and triflate [OTf]− anions with non-polar (benzene, toluene and p-xylene) and polar aromatic compounds (nicotine and aniline) were investigated. The respective temperature-composition phase diagrams were obtained at 0.1 MPa and in a temperature range 273.15 K–423.15 K. The diagrams posses the features already established for the systems of this type: (i) for the same anion, the mutual solubility continuously increases as the cation alkyl chain extends; (ii) the mutual solubility of the imidazolium ionic liquids having bistriflamide [NTf2]− anion is higher compared to that when the triflate [OTf]− anion is present; (iii) the solubility is reduced as the alkylation of the benzene ring increases. However, the LLE results for the solutions [Cnmim][OTf] + nicotine/or aniline) demonstrate a very sudden effect of the cation chain length on the liquid phase behavior. In particular, the addition of only two CH2 groups to the chain drastically increases the mutual solubility making the respective solutions always homogeneous.The experimental liquid–liquid equilibria (LLE) data for the [C2mim][OTf] + aniline, [C4mim][OTf] + aniline, and [C2mim][OTf] + nicotine systems were modeled using the UNIQUAC equation. The agreement of calculated compositions with experimental data is very satisfactory.
Liquid–liquid equilibria were measured for solutions containing: (1) nicotine, and one of the solvents PEG 200 or ethyl-lactate, and the ionic liquid 1-ethyl-3-methylimidazolium ethyl sulphate (ECOENG 212®); (2) a (nicotine+water) mixture of close to critical composition and one of the co-solvents PEG 200, or glycerol, or ethyl-lactate; and (3) a (nicotine+water) mixture and one of the salts ECOENG 212®, or sodium chloride, or sodium phosphate. The objective of these measurements was to assess the possibility of using environmentally friendly solvents for extraction/separation of nicotine from its (aqueous) solutions. PEG 200, glycerol and ethyl-lactate proved to be good co-solvents of nicotine in water. On the other hand, the inorganic salts Na3PO4 and NaCl showed remarkable salting-out effects in nicotine aqueous solutions, achieved using very small quantities of these salt. The effects of the ionic liquid (molten salt) ECOENG 212®, were, however, much more complex. Depending on its concentration in the solvent, it exhibited either a co-solvent (salting-in) effect or an anti-solvent one. This behaviour is very interesting both from the fundamental and the applications point of view.
The ionic liquid 1-ethyl-3-methylimidazolium ethylsulfate has been tested as solvent for the separation of thiophene from aliphatic hydrocarbons. Liquid–liquid equilibrium data have been determined for ternary systems containing the ionic liquid, thiophene and C6, C7, C12 or C16 alkanes at T=298.15K. The performance of the ionic liquid as solvent in such systems has been evaluated. The experimental data were correlated using the NRTL and UNIQUAC equations, and the binary interaction parameters have been reported. The phase diagrams for the ternary mixtures including both the experimental and calculated tie-lines have been presented.
The melting temperatures of [C n mpy]Cl (4 e even n e 18) were determined by a dynamic method and confirmed by differential scanning calorimetry. The latter technique was also used to measure the corresponding enthalpies of fusion. The temperatures marking the onset of decomposition of the eight ionic liquids were determined by thermogravimetry. The solidÀliquid and liquidÀliquid phase equilibria of binary mixtures of pyridine or nicotine with four ionic liquids of the 1-alkyl-3-methylpyridinium chloride family ([C n mpy]Cl with n = 4, 6, 10, 16) were investigated. The TÀx phase diagrams were measured at atmospheric pressure using turbidimetry in the (280 to 378) K temperature range. The diagrams show that pyridine is miscible in all proportions with the four studied ionic liquids while nicotine is only partially miscible with [C 4 mpy]Cl and [C 6 mpy]Cl. Data were interpreted using molecular dynamics simulations. The study illustrates, once again, the unique structural and solvent properties of ionic liquids.
The aim of this work is to test the potential of hydrophobic
phosphonium-based ionic liquids for the extraction of caffeine and
nicotine from aqueous phases through the determination of the alkaloids’
partition coefficients. It was found that the caffeine partitioning
for the ionic-liquid-rich phase increases with the ionic liquid
hydrogen-bonding accepting capability (or water content), while
for nicotine a nearly opposite behavior was observed. In addition,
both the influence of the ionic concentration of the aqueous solution
(ranging from 0.0 mol � kg�1 to 3.0 mol � kg�1), and the salt nature
(with K- and Na-based salts), in the partitioning of caffeine for
the ionic-liquid-rich phase were investigated. The influence of the
inorganic salt nature in the alkaloid partitioning for the ionic-liquidrich
phase closely follows the Hofmeister series.
In the last three years, our research follows two main issues, defined by the slogans: “green meets toxic” and “green meets green”. The first issue considers the potential use of ambient friendly solvents for toxic organic compounds of industrial and practical importance. The other is related to liquid phase behavior in solutions of ecologically sustainable substances. The “green” solvents studied are: ionic liquids, liquid poly(ethylene glycol), glycerol and 1,2- and 1,3-propanediol.
The solubility and phase behavior of linear polymethacrylate polymers, primarily poly(phenylalkyl methacrylate)s, in imidazolium-based ionic liquids (ILs) were systematically studied by changing the structure of each component. Solutions of polymethacrylates in 1-alkyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide ([C(n)mim] [NTf2]) showed lower critical solution temperature (LCST) phase behavior, and the phase separation temperature (T(c)) could be varied by selecting an appropriate combination of a polymer and an IL. An increase in alkyl chain length between the phenyl and ester groups in the polymer side chain decreased the T(c); alternatively, substitution of the imidazolium cation with a longer alkyl chain increased the T(c). When the same anion was used, the miscibility of the polymer/IL system was mainly determined by the alkyl chain length. T(c) could also be varied by mixing two ILs in an appropriate ratio. In addition, the kinetics of the reversible phase transition phenomena exhibited by these polymers were examined. Redissolution kinetics were largely controlled by the magnitude of the difference between T(c) and the glass transition temperature (T(g)) of the polymer (T(c) - T(g)), in addition to the mutual affinity between the polymer and the IL.
A review with 29 refs. analyzes effects of impurities and additives (e.g., water, chloride, and cosolvents) on the phys. properties of room-temp. ionic liqs. Remarkably, it was discovered that the viscosity of mixts. was dependent mainly on the mole fraction of added mol. solvents and only to a lesser extent upon their identity, allowing viscosity changes during the course of a reaction to be entirely predictable. While the addn. of such mol. solvents decreases the viscosity and d., chloride impurities, arising from the prepn. of the ionic liqs., increase viscosity dramatically. The commonly used methods of prepn. were validated with respect to chloride impurity.
Liquid–liquid equilibria in binary mixtures that contain a room-temperature ionic liquid and an organic solvent—namely, 1,3-dimethylimidazolium methylsulfate, [mmim][CH 3 SO 4 ], or 1-butyl-3-methylimidazolium methylsulfate, [bmim][CH 3 SO 4 ] with an aliphatic hydrocarbon (n-pentane, or n-hexane, or n-heptane, or n-octane, or n-decane), or a cyclohydrocarbon (cyclohexane, or cycloheptane), or an aromatic hydrocarbon (benzene, or toluene, or ethylbenzene, or propylbenzene, or o-xylene, or m-xylene, or p-xylene) have been measured at normal pressure by a dynamic method from 270 K to the boiling point of the solvent. Thermophysical basic characterization of pure ionic liquids are presented obtained via differential scanning calorimetry (TG/DSC), temperatures of decomposition and melting, enthalpies of fusion, and enthalpies of glass phase transition. The liquidus curves were predicted by the COSMO-RS method. For [bmim][CH 3 SO 4 ] the COSMO-RS results correspond much better with experiment than those for [mmim][CH 3 SO 4 ]. This can be explained partly by the stronger polarity of [mmim][CH 3 SO 4 ]. The solubilities of [mmim][CH 3 SO 4 ] and [bmim][CH 3 SO 4 ] in alkanes, cycloalkanes and aromatic hydrocarbons decrease with an increase of the molecular weight of the solvent. The differences of the solubilities in o-, m-, and p-xylene are not significant. By increasing the alkyl chain length on the cation, the upper critical solution temperature, UCST decreased in all solvents except in n-alkanes.
The solubility of 1-butyl-3-methylimidazolium octylsulfate, [BMIM][OcSO4], has been determined in hydrocarbon (n-hexane, n-heptane, n-octane or n-decane) solutions and alcohol (methanol, 1-butanol, 1-hexanol, 1-octanol or 1-decanol) solutions. Densities and excess molar volumes, V
Em, have been determined for 1-methyl-3-methylimidazolium methylsulfate, [MMIM][CH3SO4], solutions with an alcohol (methanol, ethanol or 1-butanol) and with water; for 1-butyl-3-methylimidazolium methylsulfate, [BMIM][CH3SO4], with an alcohol (methanol, ethanol, 1-butanol, 1-hexanol, 1-octanol or 1-decanol) and with water; and for 1-butyl-3-methylimidazolium octylsulfate, [BMIM][OcSO4], with an alcohol (methanol, 1-butanol, 1-hexanol, 1-octanol or 1-decanol) at 298.15 K and atmospheric pressure. The systems exhibit very negative or positive molar excess volumes, V
Em, and negative or positive excess molar enthalpies, H
Em, as predicted by the Flory–Benson–Treszczanowicz (FBT) model. Our experimental V
Em data were used for the description of H
Em for solutions of [MMIM][CH3SO4] with the alcohols under study. The simple Prigogine–Flory–Paterson (PFP) model, without including the association of the alcohol, gave slightly worse results. Negative molar excess volumes, V
Em, are attributed to hydrogen bonding between the short chain alcohols and ionic liquid and to efficient packing effects. The FBT model overestimates self-association of the alcohol in the solutions under study and shifts the calculated curves to higher alcohol mole fractions. The thermophysical characteristics of [BMIM][OcSO4] were also examined by differential scanning calorimetry (DSC).
The solid-liquid phase diagram of the (1-ethyl-3-methylimidazolium bis{(trifluoromethyl) sulfonyl} amide + benzene) system was determined and allowed us to identify and characterize an equimolar inclusion compound, [emim][NTf2].C6H6, with a congruent melting temperature: this type of behaviour, reported here for the first time, together with the X-ray structure of the inclusion compound lays emphasis upon the interactions that are responsible for the existence of liquid clathrates at higher benzene concentrations.
Upper critical solution temperature (UCST) combined with a high-temperature demixing type of phase diagrams are reported for binary liquid mixtures containing the ionic liquids, 1-alkyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}amide ([Cnmim][NTf2], where n = 2, 4, 6, 8, 10) and benzene, toluene, or α-methylstyrene (PhC(Me)CH2), at atmospheric and moderately high pressure. The phase diagrams were determined either using a dynamic method with visual detection of phase transitions or a laser light scattering technique. In our investigations, as the imidazolium alkyl chain length of the ionic liquid increases, the mixtures containing an arene evolve from a rarely found high-temperature demixing behaviour, to “hour-glass”, to the common phase splitting as temperature diminishes (UCST, whenever a critical point was found). For the three systems containing specifically [C10mim][NTf2] with benzene, toluene, or α-methylstyrene, data were also collected up to 5 MPa using a high-pressure laser light scattering apparatus. For all phase diagrams, the critical compositions correspond to low concentrations of the ionic liquid. This fact underlies the possibility that ionic liquids, even in relatively dilute solutions, tend to form multiple-ion aggregates. This was corroborated by electro-spray mass spectrometry.
Vapor–liquid equilibria (VLE) and excess enthalpies (HE) have been measured for the hydrocarbons hexane, 1-hexene, cyclohexane, cyclohexene, benzene and toluene with the ionic liquids 1-metyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide [MMIM]+ [(CF3SO2)2N]−, 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide [EMIM]+ [(CF3SO2)2N]−, 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide [BMIM]+ [(CF3SO2)2N]−, 1-metyl-3-methyl-imidazolium ethylsulfate [EMIM]+ [C2H5OSO3]− and pyridiniumethoxyethylsulfate [C5H5NH]+ [C2H5OC2H4OSO3]− at 353.15K, 303.15K and 333.15K, respectively. The experimental VLE and HE data were correlated together with available activity coefficients at infinite dilution γi∞ using the NRTL and UNIQUAC models and the relative van der Waals volume and surface area parameters r and q estimated by the Bondi method. The overall average errors using NRTL and UNIQUAC model are 4.6% and 4.8% for VLE, 1.7% and 1.9% for γi∞ and 3.6% and 3.2% for HE.
The liquid–liquid equilibrium data are presented for ternary mixtures {1-methyl-3-octyl-imidazoliumchloride (MeOctImCl)+benzene+an alkane} at T=298.2K. The alkanes used were heptane, dodecane, and hexadecane. The compositions of the ternary mixtures on the coexistence curve and the conjugate solutions were evaluated using densities and a standard density calibration curve. The solvent MeOctImCl is an ionic liquid, which has a very low vapour pressure and a very high boiling temperature, and is therefore, a potentially environmentally friendly solvent. This ‘neoteric’ solvent is soluble in water and stable in air. There are very few data in the literature on ternary mixtures involving ionic liquids. The NRTL equation was used to correlate the experimental tie-lines. The NRTL equation gave good correlation of the tie-line data. There are no data in the literature for the mixtures discussed in this paper. The effectiveness of the extraction of benzene from an alkane by MeOctImCl is reported as a ratio of solubilities in the two phases. This quantity, known as the ‘selectivity’, was found to increase with increasing carbon number of the alkane.
The liquid-liquid equilibrium for the ternary system formed by hexane, benzene and the ionic liquid 1-ethyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}amide, [C(2)mim][NTf2], has been experimentally determined at 25 degrees C and 40 degrees C. The results show that the [C(2)mim][NTf2] can selectively remove benzene from its mixtures with hexane, suggesting that this ionic liquid can be used as an alternative solvent in liquid extraction processes for the removal of aromatic compounds from their mixtures with alkanes.
We report experimental cloud-point and spinodal data on the solubility of (polystyrene + nitroethane) as a function of temperature (265 < T/K < 345), weight fraction of polystyrene (0 < w(ps) < 0.30), pressure (0 < p/MPa < 6.5), polystyrene (PS) molecular weight (13 000 < M(w)/a.m.u. < 130 000), and H/D isotope substitution on PS and/or nitroethane. A new high-precision apparatus based on a LASER light scattering technique was built and is described. Only phase transitions of the UCS type have been experimentally observed. Apparently, nitroethane degrades at high temperatures (T approximate to 420 K). Results show that the effects of increasing pressure or increasing the degree of deuteration on the polymer increase miscibility. In contrast, solvent deuteration decreases miscibility. Nitroethane stems to be a theta-solvent for polystyrene and therefore does not present any hypercritical temperature within the range of conditions of the experimental measurements, which have included the study of solutions slightly under tension. (C) 2000 Academic Press.
Cited By (since 1996): 134, Export Date: 4 May 2012, Source: Scopus
The liquid−liquid equilibria data for the ionic liquids 1-ethyl-3-methylimidazolium octyl sulfate and 1-methyl-3-octylimidazolium diethylenglycol monomethyl ether sulfate was investigated at T = 298.2 K and atmospheric pressure to determine their potential as solvents for extracting an aromatic compound from alkanes. The cloud point method was used to determine the binodal curve data. The effects of the increase in chain length of the alkane for the ternary mixtures [an ionic liquid + an aromatic compound + an alkane] are discussed. The liquid−liquid equilibria data obtained were also used to calculate the selectivity values.
Activity coefficients at infinite dilution of alkanes, alkenes, and alkylbenzenes as well as of the linear and branched C1−C6 alcohols, esters, and aldehydes in the ionic liquids 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide have been determined by gas chromatography using the ionic liquids as stationary phase. The measurements were carried out at different temperatures between 301 K and 396 K. From the temperature dependence of the limiting activity coefficients, partial molar excess enthalpies at infinite dilution of the solutes in the ionic liquids have been derived.
The design of safe and environmentally benign separation processes has an increasingly important role in the chemical industry. Room-temperature ionic liquids are promising solvents because they have no measurable vapor pressure, so atmospheric contamination is avoided. In this work, new liquid−liquid equilibrium data were determined to prove that 1-butyl-3-methylimidazolium trifluoromethanesulfonate ionic liquid can be an excellent extractant agent of ethanol from its mixtures with tert-amyl ethyl ether, thus allowing ether purification. The experimental technique is based on direct analysis of phases at equilibrium using 1H NMR, which allows quantitative analysis of the three chemicals and thus reduces the experimental error. The phase equilibrium data were satisfactorily correlated using the nonrandom two-liquid equation.
The solubility of 1-dodecyl-3-methylimidazolium chloride [C 12 mim][Cl] in hydrocarbons (benzene, n-octane, n-decane, n-dodecane), ethers {dipropyl ether, methyl 1,1-dimethylethyl ether (MTBE), methyl 1,1-dimethylpropyl ether (MTAE), tetrahydrofuran (THF)} has been measured by a dynamic method from 270 K to the melting point of the ionic liquid or to the boiling point of the solvent. The influence of the anion on the solubility of 1-butyl-3-methylimidazolium salts in dipropyl ether was tested. The solubility data were correlated by means of the Wilson, UNIQUAC and NRTL equations utilizing parameters derived from the solid–liquid equilibrium (SLE) data. The root-mean-square deviations of the solubility temperatures for all calculated data were higher than 1.5 K and depended on the particular equation used.
This research has been focused on a study of sulfolane and four ionic liquids as solvents in liquid–liquid extraction. Liquid–liquid equilibria data were obtained for mixtures of (sulfolane or 4-methyl-N-butylpyridinium tetrafluoroborate ([mebupy]BF4) or 1-ethyl-3-methylimidazolium ethylsulfate ([emim]C2H5SO4) or 1,3-dimethylimidazolium methylsulfate ([mmim]CH3SO4) or 1-butyl-3-methylimidazolium methylsulfate ([bmim]CH3SO4)) + toluene + n-heptane at T = 313.2 and 348.2 K and p = 0.1 MPa.The experimental data for the binary and ternary systems were well correlated with the NRTL model. The toluene/heptane selectivity values were higher with all four ionic liquids tested than with sulfolane, which is one of the most common solvents for extraction of aromatic hydrocarbons from mixtures of aromatic and aliphatic hydrocarbons used in industry. The ionic liquid [mebupy]BF4 showed an optimal combination of a high toluene distribution coefficient and a high toluene/n-heptane selectivity. These values were for the range of toluene concentrations below 55 mol% at 313.2 K and below 45 mol% at 348.2 K higher than those with sulfolane. The ionic liquid [mebupy]BF4 is, therefore, a suitable solvent to replace sulfolane for an industrial extraction process for the separation of aromatic and aliphatic hydrocarbons.
Molecular dynamics simulations of solutions of benzene in dimethylimidazolium chloride and dimethylimidazolium hexafluorophosphate have been performed with a view to answering the question posed in the title. The difference between the chemical potential of a normal model of benzene and one with no charges was found to depend on the solvent but is at least 4 kBT. This difference is sufficient to account for the observed solubility differences. There are substantial changes in the local structure around benzene with and without charges.
Ternary (liquid + liquid) equilibrium data are presented for mixtures of 1-hexyl-3-methylimidazolium (tetrafluoroborate or hexafluorophosphate) + benzene + (heptane or dodecane or hexadecane) at T=298.2 K. The tie line compositions of the conjugate solutions were obtained by means of density measurements and a standard density calibration curve. Large regions of immiscibility (increasing in the order of hexadecane > dodecane > heptane) and favourable skewing of the tie lines towards the solvent axis provide indications of the favourable use of the ionic liquids in solvent extraction. Selectivity values computed from the experimental data confirm this. Correlation of the experimental tie lines was conducted through the use of the NTRL equation, which provides good correlation of the experimental data.
Molecular dynamics simulations of binary mixtures of benzene, 1,3,5-trifluorobenzene and hexafluorobenzene with dimethylimidazolium hexafluorophosphate were carried out to examine their macroscopic and microscopic properties. The energies and volumes of mixing of these mixtures correlate well with observed microscopic properties including coordination number about the aromatic compound. The local ordering of the ions about an aromatic molecule was found to depend on the quadrupole moment of the aromatic species and to remain qualitatively the same on varying the mole fraction of the aromatic species. Interaction energies showed the most significant interactions to be between the aromatic molecule and the ions located about its equator. These findings have implications for the practical use of ionic liquids as solvents for chemical processes.
1-Alkyl-3-methylimidazolium containing ionic liquids with hexafluorophosphate, bis(trifyl)imide, tetrafluoroborate, and chloride anions form liquid clathrates when mixed with aromatic hydrocarbons; in the system 1,3-dimethylimidazolium hexafluorophosphate-benzene, the aromatic solute could be trapped in the solid state forming a crystalline 2:1 inclusion compound.
Lower critical solution temperatures (LCST)-type of phase diagrams, including the presence of closed loops, have been encountered for the first time in binary and quasi-binary liquid solutions of ionic liquids. Furthermore, the results constitute the first experimental support for the existence of a theoretically postulated, but never encountered, special kind of type VII phase diagram. Two distinct mechanisms are involved in the appearance of demixing upon temperature increase. These findings underlie the presence of specific, oriented interactions between the ionic liquid, 1-alkyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}amide, [Cnmim][NTf2], and trichloromethane, as well as aggregation phenomena.
A multiscale coarse-graining model for ionic liquids has been extended to investigate the unique aggregation of cations in ionic liquids through computer simulation. It has been found that, with sufficiently long side chains, the tail groups of cations aggregate to form spatially heterogeneous domains, while headgroups of the cations and the anions distribute as uniformly as possible. This is understood as the result of competition between the charged electrostatic interactions between headgroups and anions and the collective short-range interactions between the neutral tail groups. This aggregation can help to explain a number of experimentally observed physical phenomena in ionic liquids.
Nanometer-scale structuring in room-temperature ionic liquids is observed using molecular simulation. The ionic liquids studied belong to the 1-alkyl-3-methylimidazolium family with hexafluorophosphate or with bis(trifluoromethanesulfonyl)amide as the anions, [C(n)mim][PF(6)] or [C(n)mim][(CF(3)SO(2))(2)N], respectively. They were represented, for the first time in a simulation study focusing on long-range structures, by an all-atom force field of the AMBER/OPLS_AA family containing parameters developed specifically for these compounds. For ionic liquids with alkyl side chains longer than or equal to C(4), aggregation of the alkyl chains in nonpolar domains is observed. These domains permeate a tridimensional network of ionic channels formed by anions and by the imidazolium rings of the cations. The nanostructures can be visualized in a conspicuous way simply by color coding the two types of domains (in this work, we chose red = polar and green = nonpolar). As the length of the alkyl chain increases, the nonpolar domains become larger and more connected and cause swelling of the ionic network, in a manner analogous to systems exhibiting microphase separation. The consequences of these nanostructural features on the properties of the ionic liquids are analyzed.
Neutron diffraction has been used to investigate the structure of liquid mixtures of 1,3-dimethylimidazolium hexafluorophosphate with benzene. Two concentrations of benzene were investigated, namely, 33 mol % and 67 mol %, and show similar structures in each case. The presence of benzene significantly alters the ionic liquid structure, in particular, in the cation-cation interactions, in agreement with the single-crystal structure described recently (Holbrey, J. D.; Reichert, W. M.; Nieuwenhuyzen, M.; Sheppard, O.; Hardacre, C.; Rogers, R. D. Chem. Commun. 2003, 476). In each case, the data was analyzed using an empirical potential structure refinement process.
The existence of microphase segregation between polar and nonpolar domains in ionic liquids changes the way in which solvation can be understood in these media. Here, we perform a structural analysis on the solvation of nonpolar, polar, and associating solutes in imidazolium-based ionic liquids, where this novel way of understanding their nature as microsegregated solvents is correlated with their ability to interact with different species in diverse and complex ways.
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