- Using a Chromatographic Pseudophase Model to Elucidate the Mechanism of Olefin Separation by Silver(I) Ions in Ionic Liquids
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Silver(I) ions undergo selective olefin complexation and have been utilized in various olefin/paraffin separation techniques such as argentation chromatography and facilitated transport membranes. Ionic liquids (ILs) are solvents known for their low vapor pressure, high thermal stability, low melting points, and ability to promote a favorable solvation environment for silver(I) ion-olefin interactions. To develop highly selective separation systems, a fundamental understanding of analyte partitioning to the stationary phase and the thermodynamic driving forces behind solvation is required. In this study, a chromatographic model treating silver(I) ions as a pseudophase is constructed and employed for the first time to investigate the olefin separation mechanism in silver(I) salt/IL mixtures. Stationary phases containing varying amounts of noncoordinated silver(I) salt ([Ag+][NTf2-]) dissolved in the 1-decyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C10MIM+][NTf2-]) IL are utilized to determine the partition coefficients of various analytes including alkanes, alkenes, alkynes, aromatics, aldehyde, esters, and ketones. As ligand coordination to silver(I) ions is known to lower its olefin complexation capability, this study also examines two different types of coordinated silver(I) ion pseudophases, namely, monocoordinated silver(I) salt ([Ag+(1-decyl-2-methylimidazole, DMIM)][NTf2-]) and dicoordinated silver(I) salt ([Ag+(1-methylimidazole, MIM)(DMIM)][NTf2-]). The extent of olefin partitioning to the coordinated silver(I) ion pseudophases over the carrier gas and IL decreased by up to two orders of magnitude. Values for enthalpy, entropy, and free energy of solvation were determined for the three silver(I) ion-containing systems. Olefin retention was observed to be enthalpically dominated, while ligand coordination to the silver(I) ion pseudophase resulted in variations for both enthalpic and entropic contributions to the free energy of solvation. The developed model can be used to study chemical changes that occur in silver(I) ions over time as well as identify optimal silver(I) salt/IL mixtures that yield high olefin selectivity.
- Anderson, Jared L.,Eor, Philip
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p. 13284 - 13292
(2021/10/12)
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- Nanoreactors stable up to 200 °c: A class of high temperature microemulsions composed solely of ionic liquids
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It is a challenge to develop microemulsions which can serve as nanoreactors for the synthesis of nanoparticles and chemical reactions at high temperature. In this work, a class of novel high temperature microemulsions consisting solely of ionic liquids have been designed and prepared for the first time. It is found that nanoscale droplets formed in the ionic liquid microemulsions can be maintained up to 200 °C, and the size distribution of the droplets can be easily tuned by selection of the ionic liquids and varying compositions of the systems. By using such microemulsions as nanoreactors, porous metals such as Pt have been prepared at 180 °C without using any purposely added reductant.
- Pei, Yuanchao,Ru, Jie,Yao, Kaisheng,Hao, Lihui,Li, Zhiyong,Wang, Huiyong,Zhu, Xingqi,Wang, Jianji
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supporting information
p. 6260 - 6263
(2018/06/22)
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- Physicochemical Properties of Long Chain Alkylated Imidazolium Based Chloride and Bis(trifluoromethanesulfonyl)imide Ionic Liquids
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In this research synthesis, purification and characterization of six long-chain imidazolium based ionic liquids (ILs) including C10, C12, and C14 alkyl chain with chloride and NTf2 anions was investigated. All of these studied ILs were characterized using NMR, CHNSO, and DSC, and some impurities such as water, chloride, and metal contents were reported. The temperature dependence of some physicochemical properties such as density, dynamic and kinematic viscosity, refractive index, surface tension, and thermal stability of the synthesized ILs were also studied in the range 283.15 to 363.15 K, and the results were compared with those from the literature. Moreover, using the measured data, the thermal expansion coefficient and molar polarizability of the ILs were calculated. On the other hand the effects of alkyl chain length and anion were explained. The results revealed that although the refractive indices and viscosities increased as alkyl chain length increased, the density and surface tension results were reciprocally decreased. Besides, the results suggest that the synthesized ILs were the best choice as fuel additives.
- Hazrati, Nastaran,Abdouss, Majid,Miran Beigi, Ali Akbar,Pasban, Ali Asghar,Rezaei, Mahmoud
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p. 3084 - 3094
(2017/10/19)
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- Liquid-liquid interfacial tension of equilibrated mixtures of ionic liquids and hydrocarbons
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Ionic liquids are possible alternative solvents for the separation of aromatic and aliphatic hydrocarbons by liquid-liquid extraction. Interfacial tension is an important property to consider in the design of liquid-liquid extraction processes. In this work, the liquid-liquid interfacial tension and the mutual solubility at 25 °C have been measured for a series of biphasic, equilibrated mixtures of an ionic liquid and a hydrocarbon. In particular, the ionic liquids 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide (with the alkyl substituent being ethyl, hexyl or decyl), 1-ethyl-3- methylimidazolium ethylsulfate, and 1-ethyl-3-methylimidazolium methanesulfonate have been selected, as well as the hydrocarbons benzene, hexane, ethylbenzene, and octane. The selected sets of ionic liquids and hydrocarbons allow the analysis of the influence of a series of effects on the interfacial tension. For example, the interfacial tension decreases with an increase in the length of the alkyl substituent chain of the cation or with an increase of the degree of charge delocalisation in the anion of the ionic liquid. Also, the interfacial tension with the aromatic hydrocarbons is markedly lower than that with the aliphatic hydrocarbons. A smaller effect is caused by variation of the size of the hydrocarbon. Some of the observed trends can be explained from the mutual solubility of the hydrocarbon and the ionic liquid. Science China Press and Springer-Verlag Berlin Heidelberg 2012.
- Rodriguez, Hector,Arce, Alberto,Soto, Ana
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p. 1519 - 1524
(2012/11/07)
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- Pseudo-encapsulation-nanodomains for enhanced reactivity in ionic liquids
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Domain constrained: Polar and nonpolar domains within 1-alkyl-3- methylimidazolium ionic liquids can affect reaction outcomes by pseudo-encapsulation of reactants and this has been explored for a nucleophilic substitution reaction using a cationic substrate and a range of nucleophiles. The significant rate enhancements observed correlate with the concentration of the polar reactants within the ionic liquid's polar domain. ([C nMIM]=1-alkyl-3-methylimidazolium). Copyright
- Weber, Cameron C.,Masters, Anthony F.,Maschmeyer, Thomas
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supporting information
p. 11483 - 11486
(2013/01/15)
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- Sonochemical synthesis of 0D, 1D, and 2D zinc oxide nanostructures in ionic liquids and their photocatalytic activity
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Ultrasound synthesis of zinc oxide from zinc acetate and sodium hydroxide in ionic liquids (ILs) is a fast, facile, and effective, yet highly morphology- and size-selective route to zinc oxide nanostructures of various dimensionalities. No additional organic solvents, water, surfactants, or templating agents are required. Depending on the synthetic conditions, the selective manufacturing of 0D, 1D, and 2D ZnO nanostructures is possible: Whereas the formation of rodlike structures is typically favored, ZnO nanoparticles can be obtained either under strongly basic conditions or by use of ILs with a long alkyl chain, such as 1-n-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([Cnmim][Tf2N]; n>8). A short ultrasound irradiation time favors the formation of ZnO nanosheets. Prolonged irradiation leads to the conversion of the ZnO nanosheets into nanorods. In contrast, ionothermal synthesis (conventional heating) does not allow for morphology tuning by variation of the IL or other synthesis conditions, as the longer reaction times required lead always to the formation of well-developed hexagonal nanocrystals with prismatic tips. The ZnO nanostructures synthesized by using ultrasound were efficient photocatalysts in the photodegradation of methyl orange. The photoactivity was observed to be as high as 95 % for ZnO nanoparticles obtained in [C10mim][Tf 2N].
- Alammar, Tarek,Mudring, Anja-Verena
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p. 1796 - 1804
(2012/04/04)
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- The fluid-mosaic model, homeoviscous adaptation, and ionic liquids: Dramatic lowering of the melting point by side-chain unsaturation
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(Figure Presented) Defying conventional wisdom: Ionic liquids (ILs) with long, unsaturated alkyl appendages (see top structure) defy established trends that link long ion-bound alkyl groups to higher melting points. The new ILs are also less viscous than a saturated standard (see bottom structure) at the same temperature. These features parallel those that underpin homeoviscous adaptation in certain organisms and are indirectly supportive of a fluid-mosaiclike nanoscale character.
- Murray, Samuel M.,O'Brien, Richard A.,Mattson, Kaila M.,Ceccarelli, Christopher,Sykora, Richard E.,West, Kevin N.,Davis Jr., James H.
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body text
p. 2755 - 2758
(2010/07/06)
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- Synthesis of imidazolium and pyridinium-based ionic liquids and application of 1-alkyl-3-methylimidazolium salts as pre-catalysts for the benzoin condensation using solvent-free and microwave activation
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An efficient one-pot procedure for the synthesis of ionic liquids based on nitrogen-containing heterocycles, imidazolium or pyridinium under 'green chemistry' conditions has been described. Imidazolium salts and DBU have been found to catalyze efficiently the benzoin condensation giving good yields within very short reaction time using solvent-free microwave activation conditions.
- Aupoix, Audrey,Pégot, Bruce,Vo-Thanh, Giang
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scheme or table
p. 1352 - 1356
(2010/04/02)
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- Expanding the polarity range of ionic liquids
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The polarity of several [X-mim]NTf2 ionic liquids, as measured with solvatochromic dyes, Reichardt's dye and Nile Red, may be varied over a wide range by attachment of functional group-containing substituents (X) to the imidazolium cation.
- Dzyuba, Sergei V.,Bartsch, Richard A.
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p. 4657 - 4659
(2007/10/03)
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