- Understanding the behavior of mixtures of protic-aprotic and protic-protic ionic liquids: Conductivity, viscosity, diffusion coefficient and ionicity
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We have investigated the physicochemical properties such as electrical conductivity, viscosity and diffusion coefficient for the binary mixtures of protic ionic liquids with aprotic ionic liquids and of protic with protic ionic liquids at 298.15 K. A significant enhancement in the electrical conductivity is observed for the binary mixtures of ionic liquids, as compared to those of the constituent pure ionic liquids and varied with the composition of the mixtures. The viscosity of binary mixtures of protic with aprotic ionic liquids, 1?butyl?3?methylimidazoliumbis(trifluoromethylsulfonyl)imide [bmIm][NTf2], 1?butyl?1?methylpyrrolidiumbis(trifluoromethylsulfonyl)imide [bmPyrr][NTf2] and 1,3-dimethylimidazolium methyl sulfate, [mmIm][CH3SO4] decreases with an increase in the composition of the [HmIm][CH3COO]. On the contrary, the viscosity for binary mixtures of protic with protic ionic liquid, 1?methylpyrrolidium acetate [HmPyrr][CH3COO] and 4?methylmorpholine acetate [HmMorph][CH3COO] increases upon the addition of 1?methylimidazolium acetate [HmIm][CH3COO]. The self diffusion coefficients were determined for all the binary mixtures of ionic liquids by using Pulsed Gradient Spin Echo (PGSE) NMR method. Self diffusion coefficients of [bmIm][NTf2]-[HmIm][CH3COO], [bmPyrr][NTf2]-[HmIm][CH3COO], [mmIm][CH3SO4]-[HmIm][CH3COO] are enhanced, while those of [HmPyrr][CH3COO]-[HmIm][CH3COO] and [HmMorph][CH3COO]-[HmIm][CH3COO] decreases on addition of [HmIm][CH3COO]. This is converse in the case of viscosity. Furthermore, the above correlations were interpreted with the help of NMR spectroscopy on the basis of interactions of ions in the binary mixtures of ionic liquids. Finally, we have quantified the ionicity through the Nernst–Einstein equation and have confirmed the validity of the Walden rule for the binary mixture of ionic liquids.
- Thawarkar, Sachin,Khupse, Nageshwar D.,Shinde, Dinesh R.,Kumar, Anil
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- Transition-state effects of ionic liquids in substitution reactions of PtII complexes
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When normal is a surprise: Studies of a ligand-substitution reaction of a PtII complex (see picture; apa: 2,6-bis(aminomethyl) pyridine) in water, methanol, and the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide reveal that the ionic liquid behaves normally , that is, as any other solvent. In the ionic liquid, changes in the polarity of the transition state only play a minor role. (Chemical Equation Presented)
- Weber, Christian F.,Puchta, Ralph,Van Eikema Hommes, Nico J. R.,Wasserscheid, Peter,Van Eldik, Rudi
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- First observation for dynamic solvent effect in ionic liquids
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We observed pressure effects on the rate of thermal fading of colored chromene 1 photochemically generated from 2 in ionic liquids. The reaction rates were retarded with increasing pressure in [C4-mim][CS], [bzl-mim][Tf2N], and [mnp-mim][Tf2N], whereas the reaction rate increased with pressures in [C4- mim][Tf2N]. These pressure-induced retardations, so-called dynamic solvent effects, result from the slow thermal fluctuations of solvents.
- Kitaoka, Satoshi,Nobuoka, Kaoru,Miura, Junji,Ohga, Yasushi,Ishikawa, Yuichi
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- The effects of an ionic liquid on unimolecular substitution processes: The importance of the extent of transition state solvation
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The reaction of bromodiphenylmethane and 3-chloropyridine, which proceeds concurrently through both unimolecular and bimolecular mechanisms, was examined in mixtures of acetonitrile and an ionic liquid. As predicted, the bimolecular rate constant (k2) gradually increased as the amount of ionic liquid in the reaction mixture increased, as a result of a minor enthalpic cost offset by a more significant entropic benefit. Addition of an ionic liquid had a substantial effect on the unimolecular rate constant (k1) of the reaction, with at least a 5-fold rate enhancement relative to acetonitrile, which was found to be due to a significant decrease in the enthalpy of activation, partially offset by the associated decrease in the entropy of activation. This is in contrast to the effects seen previously for aliphatic carbocation formation, where the entropic cost dominated reaction outcome. This change is attributed to a lessened ionic liquid-transition state interaction, as the incipient charges in the transition state were delocalized across the neighbouring π systems. By varying the mole fraction of ionic liquid in the reaction mixture the ratio between k1and k2could be altered, highlighting the potential to use ionic liquids to control which pathway a reaction proceeds through.
- Keaveney, Sinead T.,White, Benjamin P.,Haines, Ronald S.,Harper, Jason B.
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- Extraction of uranium from aqueous solutions by using ionic liquid and supercritical carbon dioxide in conjunction
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Uranyl ions [UO2]2+ in aqueous nitric acid can be extracted into supercritical CO2 (sc-CO2) by using an imidazolium-based ionic liquid with tri-n-butyl phosphate (TBP) as a complex-ing agent. The transfer of ura
- Wang, Joanna Shaofen,Sheaff, Chrystal N.,Yoon, Byunghoon,Addleman, R. Shane,Wai, Chien M.
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- Europium-based ionic liquids as luminescent soft materials
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Low melting, highly luminescent: [C3mim] [Eu(Tf 2N)4] (1), [C4mim][Eu(Tf2N) 4], and [C4mpyr]2[Eu(Tf2N) 5] are the first lanthanide ionic liquids that do not need stabilization of the liquid state by neutral coligands. They show excellent photophysical properties, such as long lifetimes of luminescence at large EuIII concentration, small line width, and high color purity (see emission spectrum of 1 and photograph of a sample under UV light).
- Tang, Sifu,Babai, Arash,Mudring, Anja-Verena
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- Synthesis of CoPt nanorods in ionic liquids
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Cobalt platinum nanorods, hyperbranched nanorods, and nanoparticles were synthesized in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [BMIM][Tf2N], ionic liquid though the thermal reduction of platinum acetylacetonate, and coba
- Wang, Yong,Yang, Hong
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- Binary Mixtures of Aprotic and Protic Ionic Liquids Demonstrate Synergistic Polarity Effect: An Unusual Observation
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In this communication, we demonstrate the solute–solvent and solvent–solvent interactions in the binary mixtures of two aprotic ionic liquids, namely 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide and 1-butyl-1-methylpyrrolidinium bis(trifl
- Thawarkar, Sachin,Khupse, Nageshwar D.,Kumar, Anil
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- Evaluation of ionic liquids as electrolytes for vanadium redox flow batteries
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Non-aqueous redox flow batteries (NARFBs) are promising electrochemical energy storage devices due to their wide electrochemical potential windows, generally >2 V of organic solvents. This study aims to investigate the suitability of ionic liquids (ILs) as electrolytes for NARFBs containing a vanadium metal complex. The electrochemistry of a single-component NARFBs employing vanadium (III) acetylacetonate (V(acac)3) was studied in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C4mim][NTF2], and 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide, [C4mpyr][NTF2], electrolytes. The electrochemical kinetics of the anodic and cathodic reactions was measured using cyclic voltammetry. The VII/VIII and VIII/VIV couples were quasi-reversible and together yielded a cell potential of 2.2 V in both ILs. Charge/discharge characteristics show that a coulombic efficiency for cycles 1–50 ranged from 88 to 92% using a V(acac)3/[C4mpyr][NTF2] cell.
- Bahadori, L.,Boyd, R.,Nockemann, P.,Shafeeyan, M. S.,Warrington, A.
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- Notes on the asymmetric hydrogenation of methyl acetoacetate in neoteric solvents
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Asymmetric hydrogenation of methyl acetoacetate to methyl (R)-3-hydroxybutyrate by [(R)- RuCl(binap)( p-cymen)]Cl has been studied in methanol-ionic liquid and methanol- dense CO2 solvent systems. The ionic pairs triethylhexylammonium and 1-methylimidazolium with bis(trifluoromethane sulfonyl) imide and hexafluorophosphates were used. The role of ionic pairs on the kinetic parameters and (enantio)selectivity has been demonstrated. Although the CO2 expanded methanol system suffered from a reduction in both reaction rate and product selectivity, this changed in the presence of water. The high selectivity of the optimized methanol-CO 2-water-halide system was designed as a consequence of observed additive effects.
- Floris, Tomas,Kluson, Petr,Muldoon, Mark J.,Pelantova, Helena
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- Ambient lithium-SO2 batteries with ionic liquids as electrolytes
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Li-SO2 batteries have a high energy density but bear serious safety problems that are associated with pressurized SO2 and flammable solvents in the system. Herein, a novel ambient Li-SO2 battery was developed through the introduction of ionic liquid (IL) electrolytes with tailored basicities to solvate SO2 by reversible chemical absorption. By tuning the interactions of ILs with SO2, a high energy density and good discharge performance with operating voltages above 2.8V were obtained. This strategy based on reversible chemical absorption of SO 2 in IL electrolytes enables the development of the next generation of ambient Li-SO2 batteries. Copyright
- Xing, Huabin,Liao, Chen,Yang, Qiwei,Veith, Gabriel M.,Guo, Bingkun,Sun, Xiao-Guang,Ren, Qilong,Hu, Yong-Sheng,Dai, Sheng
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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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- Facile and scalable synthesis of nanoporous materials based on poly(ionic liquid)s
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A simple, fast, sustainable, and scalable strategy to prepare nanoporous materials based on poly(ionic liquid)s (PILs) is presented. The synthetic strategy relies on the radical polymerization of crosslinker-type ionic liquid (IL) monomers in the presence of an analogous IL, which acts as a porogenic solvent. This IL can be extracted easily after polymerization and recycled for further use. The great advantages of this synthetic approach are the atom-efficiency and lack of waste. The effects of different monomer/porogen ratios on the specific surface area, porosity, and pore size have been investigated. Finally, the potential of the materials as CO2 sorbents has been evaluated.
- Azcune, Itxaso,Garca, Ignacio,Carrasco, Pedro M.,Genua, Aratz,Tanczyk, Marek,Jaschik, Manfred,Warmuzinski, Krzysztof,Cabaero, Germn,Odriozola, Ibon
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- Physico-chemical properties of binary and ternary mixtures of ethyl acetate + ethanol + 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide at 298.15 K and atmospheric pressure
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Densities, viscosities and refractive indices have been measured at 298.15 K and atmospheric pressure for binary and ternary mixtures of ethanol, ethyl acetate and 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl) imide [C4mim][NTF2]. From these experimental properties, the corresponding excess properties have been calculated and adequately fitted with the Redlich-Kister polynomial equation. The adjustable parameters and standard deviations between experimental and calculated values are reported. Interest of this mixture is due to the possibility of using [C4mim][NTF 2] as an entrainer in the extractive distillation of ethanol + ethyl acetate. These results are compared with previously determined experimental data for mixtures of ethyl acetate and/or ethanol with the ionic liquid 1-octyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide, [C 8mim][NTF2].
- Andreatta, Alfonsina E.,Arce, Alberto,Rodil, Eva,Soto, Ana
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- Electrochemical and spectroscopic study of vanadyl acetylacetonate–ionic liquids interactions
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A panel of ionic liquids has been synthesized and their effect on the vanadyl acetylacetonate solubility in acetonitrile has been firstly assessed. 1-Butyl-3-methylimidazolium acetate showed an unprecedented result, increasing the VO(acac)2 solubility in acetonitrile of more than one magnitude order (from 0.06 M to 1.1 M) opening new interesting horizons for the possible applications of this vanadium complex. The electrochemical effect of the considered ionic liquids has been subsequently investigated through cyclic voltammetry and linear sweep voltammetry with rotating disk electrode, determining diffusion coefficient and kinetic current of VO(acac)2 in the considered media. In order to achieve a deeper understanding on the examined systems, VO(acac)2 solutions in acetonitrile ILs were eventually studied through IR, UV–vis, and EPR spectroscopies, finding evidences, corroborated by DFT studies, of the formation of strong adducts between VO(acac)2 and ILs.
- Guglielmero,Langroudi, Mo. Meskinfam,Khatib, M. Al,de Oliveira, M. Aysla Costa,Mecheri,De Leo,Mezzetta,Guazzelli,Giglioli,Epifanio, A. D',Pogni,Chiappe,Pomelli
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- Dissolution of the Rare-Earth Mineral Bastnaesite by Acidic Amide Ionic Liquid for Recovery of Critical Materials
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Rare-earth elements provide the cornerstones to clean sustainable energy and modern technologies such as computers, communications, and transportation. As such, the recovery of rare earths (REs) from minerals such as bastnaesite remains important for modern times. As the light lanthanides (La-Nd) constitute the majority (typically >98.7 %) of the REs in bastnaesite with the heavy REs (Sm-Lu) contributing the remainder (approximately 1.3 %), an enrichment of heavier REs may serve as an effective means of assisting rare-earth recovery. Such an extractive metallurgy process involving ionic liquids (ILs) leads to an enrichment of heavy REs by nearly an order of magnitude. The acidic IL N,N-dimethylacetamidium bis(trifluoromethylsulfonyl)imide (DMAH+NTf2-) in the IL 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMIM+NTf2-) dissolves froth flotation bastnaesite, synthetic bastnaesite analogues (RECO3F), RE2O3, and RE2(CO3)3 minerals. An overall reaction for the dissolution of bastnaesite is proposed for this IL system. This IL system may provide the initial stages of a greater RE separation scheme for bastnaesite froth flotation concentrates.
- Freiderich, John W.,Stankovich, Joseph J.,Luo, Huimin,Dai, Sheng,Moyer, Bruce A.
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- Synthesis of efficient SBA-15 immobilized ionic liquid catalyst and its performance for Friedel–Crafts reaction
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Friedel–Crafts alkylation of benzene with 1-dodecene, which is an important reaction of synthetic detergent, was studied via ionic liquid [bmim][TFSI]/AlCl3 (1-butyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imide/AlCl3) immobilized on SBA-15 catalysts. XRD, BET, TEM, TG, ammonia TPD investigations were used to search insight into catalyst characteristic. The immobilized catalysts preserved ordered structure and presented high specific surface areas. The utilization of active sites was significantly improved by immobilization. Based on ammonia TPD, immobilized catalysts exhibited higher Lewis acidity than aluminum chloride grafted SBA-15. TG indicated that thermal stability of ionic liquid has been improved by immobilization. The influences of various reaction conditions including reaction time, benzene/1-dodecene ratio were studied. Immobilized ionic liquids have better performance of no matter 1-dodecene conversion or 2-linear alkyl benzene (2-LAB) selectivity, than bulk ionic liquid catalysts or aluminum chloride grafted mesoporous materials. 2-LAB selectivity can be increased from about 35% with bulk ionic liquid to more than 60% with immobilized catalysts. Under optimal condition, 2-LAB selectivity reached as high as 80%. The immobilized catalysts could be reused. And at 3th cycle of catalysts, 1-dodecene conversion could still reach more than 50%. The role of deactivation was proposed based on TEM, BET and TG investigations. By-products as oligomer, produced by oligomerization of olefin, blocked or covered the pores, led to deactivation of catalysts.
- He, Yibo,Zhang, Qinghua,Zhan, Xiaoli,Cheng, Dang-guo,Chen, Fengqiu
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- Rationalising the effects of ionic liquids on a nucleophilic aromatic substitution reaction
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The nucleophilic aromatic substitution reaction between 1-fluoro-2,4-dinitrobenzene and ethanol was examined in a series of ionic liquids across a range of mole fractions. Temperature-dependent kinetic analyses were undertaken to determine the activation parameters for this reaction at the highest mole fraction. As the mole fraction of ionic liquid was increased, the rate constant of the reaction also increased, however the microscopic origin of the rate enhancement was shown to be different between different ionic liquids and also between different solvent compositions. These results indicate a balance between microscopic interactions that result in the observed solvent effects and a qualitative method for analysing such interactions is introduced.
- Hawker, Rebecca R.,Wong, Michaela J.,Haines, Ronald S.,Harper, Jason B.
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- Gluing Ionic Liquids to Oxide Surfaces: Chemical Anchoring of Functionalized Ionic Liquids by Vapor Deposition onto Cobalt(II) Oxide
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Ionic liquids (IL) hold a great potential as novel electrolytes for applications in electronic materials and energy technology. The functionality of ILs in these applications relies on their interface to semiconducting nanomaterials. Therefore, methods to control the chemistry and structure of this interface are the key to assemble new IL-based electronic and electrochemical materials. Here, we present a new method to prepare a chemically well-defined interface between an oxide and an IL film. An imidazolium-based IL, which is carrying an ester group, is deposited onto cobalt oxide surface by evaporation. The IL binds covalently to the surface by thermally activated cleavage of the ester group and formation of a bridging carboxylate. The anchoring reaction shows high structure sensitivity, which implies that the IL film can be adhered selectively to specific oxide surfaces.
- Xu, Tao,Waehler, Tobias,Vecchietti, Julia,Bonivardi, Adrian,Bauer, Tanja,Schwegler, Johannes,Schulz, Peter S.,Wasserscheid, Peter,Libuda, Joerg
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- Crystallization in ionic liquids: Synthesis, properties, and polymorphs of uranyl salts
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Crystallizations in uranyl-containing ionic liquids yielding crystals {X}a{[UO2]b[Y]c} with selected anions and cations (X = [Bmim]+ for Y = Cl-, NO3-, and SCN-; Y = Cl- for X = [Emim]+, [Emmim]+, [Bmim]+, and [Bmmim]+; Emim = l-ethyl-3-methyl-imidazolium, Emmim = l-ethyl-2,3-dimethylimidazolium, Bmim = l-butyl-3-methylimidazolium, and Bmmim = l-butyl-2,3-dimethylimidazolium) were performed herein. Through standard crystallographic analyses, Hirshfeld surface analyses, and multiple characterization techniques, compounds with common cations/anions were investigated. For compounds [Bmim]2[(UO2)2(μ-OH)2(NO3)4] (1), [Bmim]3[UO2(NCS)5] (2), and [Bmim]2[UO2Cl4] (3TT and 3TG), common [Bmim]+ cations with different conformations were studied with respect to packing and interactions (for 1). The coordinated [(UO2)2(μ-OH)2(NO3)4]2-, [UO2(NCS)5]3-, and [UO2Cl4]2- anions that have historically been related to nuclear fuel cycles were demonstrated with respect to geometry and distortion. For compounds with common [UO2Cl4]2- anions [Emim]2[UO2Cl4] (4), [Emmim]2[UO2Cl4] (5), [Bmmim]2[UO2Cl4] (6), 3TT, and 3TG, observed interionic interactions that have been previously impeded by limited structural information were discussed fully in relation to different cations and temperatures. Moreover, multistep phase transformations of 2, which have been undefined in solution studies, have been identified through differential scanning calorimetry analyses and polarizing optical microscopy. The polymorph transformations between 3TT and 3TG in solution, as controlled by uranyl concentration, were studied using optical microscopy and powder X-ray diffraction. The thermal stability, IR/Raman, and UV-vis/luminescence spectra of these compounds were also investigated.
- Qu, Feng,Zhu, Qian-Qian,Liu, Chun-Li
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- The effects of using an ionic liquid as a solvent for a reaction that proceeds through a phenonium ion
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A unimolecular reaction that proceeds predominantly through a phenonium ion intermediate was investigated in mixtures of an ionic liquid and methanol. Varying the proportion of the ionic liquid in the reaction mixture led to an increase in the rate constant compared with methanol when very small amounts of ionic liquid were present in the reaction mixture and a decrease when higher proportions of the salt were present. Activation parameters determined for the process showed that the effect of changing the solvent composition on the rate constant was due to a key interaction between the ionic liquid and the transition state of the process, similar to other unimolecular processes. Analysis of the stereochemistry of the products demonstrated that the ionic liquid had no effect on either the ratio of the stereochemistry of the substitution products, or the ratio of the substitution and eliminations mechanisms occurring in solution.
- Gilbert, Alyssa,Haines, Ronald S.,Harper, Jason B.
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- Temperature dependence of interactions between stable piperidine-1-yloxyl derivatives and a semicrystalline ionic liquid
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The stable 2,2,6,6-tetramethylpiperidine-1-yloxyl and its derivatives with hydrogen-bond-forming (-OH, -OSO3H), anionic (-OSO3 bearing K+ or [K(18-crown-6)]+ as counter ion), or cationic (-N+(CH3)3 bearing I-, BF-4, PF-6 or N- (SO2CF3)2 as counter ion) substituents are investigated in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide over a wide temperature range. The temperature dependence of the viscosity of the ionic liquid is well described by the Vogel-Fulcher-Tammann equation. Interestingly, the temperature dependence of the rotational correlation time of the spin probes substituted with either a hydrogen-bond-forming group or an ionic substituent can be described using the Stokes-Einstein equation. In contrast, the temperature dependence of the rotational correlation time of the spin probe without an additional substituent at the 4-position to the nitroxyl group does not follow this trend. The activation energy for the mobility of the unsubstituted spin probe, determined from an Arrhenius plot of the spin-probe mobility in the ionic liquid above the melting temperature, is comparable with the activation energy for the viscous flow of the ionic liquid, but is higher for spin probes bearing an additional substituent at the 4-position. Quantum chemical calculations of the spin probes using the 6-31G+d method give information about the rotational volume of the spin probes and the spin density at the nitrogen atom of the radical structure as a function of the substituent at the spin probes in the presence and absence of a counter ion. The results of these calculations help in understanding the effect of the additional substituent on the experimentally determined isotropic hyperfine coupling constant.
- Strehmel, Veronika,Rexhausen, Hans,Strauch, Peter,Strehmel, Bernd
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- EuIII luminescence in a hygroscopic ionic liquid: Effect of water and evidence for a complexation process
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The spectroscopic characteristics (excitation, emission and lifetime) of EuIII dissolved in 1-methyl-3-butylimidazolium bis(trifluoromethanesulfon)imide (BumimTf2N) are reported. In a first series of experiments, the effect of the presence of water in BumimTf 2N was examined. It appears that non-degassed solutions are most probably inhomogeneous, displaying large water clusters leading to an intense diffusion of the red light of an He:Ne laser. In these samples, the Eu emission spectrum is close to that observed in slightly acidic aqueous solutions. In contrast, when the samples were degassed the solution appeared homogeneous and water can be considered as a competitive ligand for the first coordination sphere of Eu. In a subsequent series of experiments, tetrabutylammonium chloride (TBACl) was added to the solution and the resultant species investigated. The ensuing enhancement in the metal-centered luminescence has been interpreted in terms of changes in the inner coordination sphere of the EuIII ion and possible structures are discussed. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Billard, Isabelle,Mekki, Soufiane,Gaillard, Clotilde,Hesemann, Peter,Moutiers, Gilles,Mariet, Clarisse,Labet, Alexandre,Buenzli, Jean-Claude G.
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- Surface tension of binary mixtures of 1-alkyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide ionic liquids with alcohols
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New experimental surface tension data have been provided at 283.15, 298.15, 313.15 K and atmospheric pressure for binary mixtures of 1-butyl-3-methyl- imidazolium bis(trifluoromethylsulfonyl)imide and 1-octyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide ionic liquids with the alcohols: methanol, ethanol, 1-propanol, 2-propanol, l-butanol and 1-pentanol. The experimental results show that the surface tensions of these mixtures depend systematically on the alkyl chain length of the ionic liquid and alcohol, composition and temperature. Surface tension changes on mixing have been calculated and adequately fitted by the Redlich-Kister polynomial equation. The adjustable parameters and the standard deviations between experimental and calculated values are reported.
- Andreatta, Alfonsina E.,Rodil, Eva,Arce, Alberto,Soto, Ana
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- ZIF-8-porous ionic liquids for the extraction of 2,2,3,3-tetrafluoro-1-propanol and water mixture
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The design of stable ionic liquids (ILs) has become crucial for efficient liquid-liquid extraction (LLE) of alcohol and water. Porous ionic liquids (PILs), as a special class of ILs, have attracted attention by virtue of their unique porous structure and IL characteristics. In this research, a series of zeolitic imidazolate framework-8 based porous ionic liquids (ZIF-8-PILs) were synthesized by simply mixing a solution of zeolitic imidazolate framework-8 (ZIF-8) and rationally designed ILs. The introduction of ZIF-8 resulted in a unique liquid porous structure and molecular sieve for ZIF-8-PILs. The improved extraction properties endowed ZIF-8/[Bpy][NTf2] with more efficiency for the separation of 2,2,3,3-tetrafluoro-1-propanol (TFP) and water with 88.1% TFP extraction rate and steady reuse. The excellent extraction performance of ZIF-8-PILs is discussed in relation to their textural property and unique intermolecular interaction.
- Wang, Zenghui,Zhao, Pingping,Wu, Jimin,Gao, Jun,Zhang, Lianzheng,Xu, Dongmei
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supporting information
p. 8557 - 8562
(2021/05/26)
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- Controlling the reactions of 1-bromogalactose acetate in methanol using ionic liquids as co-solvents
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The reactions of an acetobromogalactose in mixtures of methanol and one of seven different ionic liquids with varying constituent ions were studied. In general, small amounts of ionic liquid in the reaction mixture led to increases in the rate constant compared to methanol, whilst large amounts of ionic liquid led to decreases in the rate constant; this outcome differs significantly from previous reactions proceeding through this mechansim. Temperature dependent kinetic studies indicated that the dominant interaction driving these changes was between the ionic liquid and the transition state of the process. Through considering solvent parameters of ionic liquids, a relationship was found between the changes in the rate constant and both the hydrogen bond accepting ability and polarisability of the solvent, indicating that the interactions affecting reaction outcome are both specific and non-specific in nature; once more, these interactions were different to those observed in previous similar reactions. By changing the amount of ionic liquid in the reaction mixture, additional products not seen in the molecular solvent case were observed, the ratios of which are dependent on the anion of the ionic liquid and the proportion of ionic liquid in the reaction mixture. This demonstrates the importance of considering solvent effects on both the rate and product determining steps and the potential application of such changes is discussed.
- Gilbert, Alyssa,Haines, Ronald S.,Harper, Jason B.
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supporting information
p. 5442 - 5452
(2020/09/09)
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- Probing CO2 Reduction Pathways for Copper Catalysis Using an Ionic Liquid as a Chemical Trapping Agent
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The key to fully leveraging the potential of the electrochemical CO2 reduction reaction (CO2RR) to achieve a sustainable solar-power-based economy is the development of high-performance electrocatalysts. The development process relies heavily on trial and error methods due to poor mechanistic understanding of the reaction. Demonstrated here is that ionic liquids (ILs) can be employed as a chemical trapping agent to probe CO2RR mechanistic pathways. This method is implemented by introducing a small amount of an IL ([BMIm][NTf2]) to a copper foam catalyst, on which a wide range of CO2RR products, including formate, CO, alcohols, and hydrocarbons, can be produced. The IL can selectively suppress the formation of ethylene, ethanol and n-propanol while having little impact on others. Thus, reaction networks leading to various products can be disentangled. The results shed new light on the mechanistic understanding of the CO2RR, and provide guidelines for modulating the CO2RR properties. Chemical trapping using an IL adds to the toolbox to deduce the mechanistic understanding of electrocatalysis and could be applied to other reactions as well.
- Etzold, Bastian J. M.,Hermans, Yannick,Hofmann, Jan P.,Katsounaros, Ioannis,Reichert, Andreas M.,Schmatz, Patrick,Shen, Liu-Liu,Straub, Sascha-Dominic,Zhang, Gui-Rong
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supporting information
p. 18095 - 18102
(2020/09/09)
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- A Robust Fungal Allomelanin Mimic: An Antioxidant and Potent π-Electron Donor with Free-Radical Properties that can be Tuned by Ionic Liquids
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Developing effective strategies to increase the chemical stability and to fine-tune the physico-chemical properties of melanin biopolymers by rational control of π-electron conjugation is an important goal in materials science for biomedical and technological applications. Herein we report that poly-1,8-dihydroxynaphthalene (pDHN), a non-nitrogenous, catechol-free fungal melanin mimic, displays a high degree of structural integrity (from MALDI-MS and CP/MAS 13C NMR analysis), a strong radical scavenging capacity (DPPH and FRAP assays), and an unusually intense EPR signal (g=2.0030). Morphological and spectral characterization of pDHN, along with deassembly experiments in ionic liquids, indicated amorphous aggregates of small globular structures with an estimated stacking distance of 3.9 ? and broadband absorption throughout the visible range. These results indicate that DHN-based melanins exhibit a high structural integrity and enhanced antioxidant and free-radical properties of potentially greater biomedical and technological relevance than for typical indole-based eumelanins.
- Manini, Paola,Lino, Valeria,Franchi, Paola,Gentile, Gennaro,Sibillano, Teresa,Giannini, Cinzia,Picardi, Emanuela,Napolitano, Alessandra,Valgimigli, Luca,Chiappe, Cinzia,d'Ischia, Marco
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p. 1331 - 1337
(2019/06/24)
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- Correlating ionic liquid solvent effects with solvent parameters for a reaction that proceeds through a xanthylium intermediate
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A unimolecular nucleophilic substitution reaction that proceeds through a xanthylium carbocation was studied in seven ionic liquid solvents. It was found that the general trend in the rate constant with changing proportion of ionic liquid in the reaction mixture was different to that seen for other unimolecular processes, with the rate constant increasing as more ionic liquid was added to the reaction mixture. A significant correlation was found between the natural logarithm of the rate constant and a combination of the Kamlet-Taft solvent parameters. This relationship indicated that the principal interaction involved hydrogen bonding between the ionic liquid and some species along the reaction coordinate. Further, this correlation enables prediction of the effects that other ionic liquids will have on this, and other, reactions that proceed through a similar intermediate.
- Gilbert, Alyssa,Bucher, G?tz,Haines, Ronald S.,Harper, Jason B.
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supporting information
p. 9336 - 9342
(2019/11/13)
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- Stability of the zwitterionic liquid butyl-methyl-imidazol-2-ylidene borane
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Modification of the C2 position of the standard 1-butyl-3-methyl imidazolium cation by a borohydride group leads to a zwitterionic liquid (ZIL). The resulting imidazol-2-ylidene borane ZIL is liquid at room temperature. Dynamic viscosity as well as thermal and electrochemical stability are investigated. Thermal decomposition follows a similar pathway as in comparable imidazolium ionic liquids. The surprisingly low viscosity and good reductive stability make it a promising candidate for electrochemical applications.
- Tr?ger-Müller, Steffen,Antonietti, Markus,Liedel, Clemens
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p. 11437 - 11443
(2018/05/14)
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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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- Thermodynamic properties of selenoether-functionalized ionic liquids and their use for the synthesis of zinc selenide nanoparticles
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Three selenoether-functionalized ionic liquids (ILs) of N-[(phenylseleno)methylene]pyridinium (1), N-(methyl)- (2) and N-(butyl)-N'-[(phenylseleno)methylene]imidazolium (3) with bis(trifluoromethanesulfonyl)imide anions ([NTf2]) were prepared from pyridine, N-methylimidazole and N-butylimidazole with in situ obtained phenylselenomethyl chloride, followed by ion exchange to give the desired compounds. The crystal structures of the bromide and tetraphenylborate salts of the above cations (1-Br, 2-BPh4 and 3-BPh4) confirm the formation of the desired cations and indicate a multitude of different supramolecular interactions besides the dominating Coulomb interactions between the cations and anions. The vaporization enthalpies of the synthesized [NTf2]-containing ILs were determined by means of a quartz-crystal microbalance method (QCM) and their densities were measured with an oscillating U-tube. These thermodynamic data have been used to develop a method for assessment of miscibility of conventional solvents in the selenium-containing ILs by using Hildebrandt solubility parameters, as well as for modeling with the electrolyte perturbed-chain statistical associating fluid theory (ePC-SAFT) method. Furthermore, structure-property relations between selenoether-functionalized and similarly shaped corresponding aryl-substituted imidazolium- and pyridinium-based ILs were analyzed and showed that the contribution of the selenium moiety to the enthalpy of vaporization of an IL is equal to the contribution of a methylene (CH2) group. An incremental approach to predict vaporization enthalpies of ILs by a group contribution method has been developed. The reaction of these ILs with zinc acetate dihydrate under microwave irradiation led to ZnSe nanoparticles of an average diameter between 4 and 10 nm, depending on the reaction conditions.
- Klauke, Karsten,Zaitsau, Dzmitry H.,Bülow, Mark,He, Li,Klopotowski, Maximilian,Knedel, Tim-Oliver,Barthel, Juri,Held, Christoph,Verevkin, Sergey P.,Janiak, Christoph
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p. 5083 - 5097
(2018/04/11)
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- Excess Molar Volume and Viscosity Deviation of [C2mim][NTf2]/[C4mim][NTf2] + DMC/DEC
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Two hydrophobic ionic liquids (ILs) 1-alkyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C2mim][NTf2] and [C4mim][NTf2]) were synthesized. The binary mixtures of the two ILs were prepared with dimethyl carbonate (DMC) or diethyl carbonate (DEC) over the entire mole fraction range, respectively. The density and viscosity of the binary mixtures were determined by an automated DMA 5000 M and a Lovis 2000 ME Anton Paar Rotational Stabinger Viscometer at temperatures ranging from 288.15 to 328.15 K. The uncertainties of the density and viscosity are ur(δ) = 0.00120 and ur(δ) = 0.01. The excess molar volumes and viscosity deviations were calculated for the four binary mixtures by the measurement values. The effects of the extension of the alkyl chain of the cation and anion on the above properties are discussed. The effects of the methyl introduction on the cation was also discussed with the literature. The excess molar volumes and viscosity deviations were fitted versus mole fraction according to the Redlich-Kister equation. The thermal expansion coefficients of the systems were calculated according to the density values.
- Liu, Qingshan,Zhao, Liwei,Zheng, Qige,Mou, Lin,Zhang, Pengfei
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p. 4484 - 4496
(2019/01/03)
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- Anion Analysis of Ionic Liquids and Ionic Liquid Purity Assessment by Ion Chromatography
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The simultaneous determination of halide impurities (fluoride, chloride, bromide, and iodide) and ionic liquid (IL) anions (tetrafluoroborate, hexafluorophosphate, and triflimide) using ion chromatography was developed with a basic, non-gradient ion chromatography system. The non-gradient method uses the eluent Na2CO3/NaHCO3in water/acetonitrile (70:30 v:v) on the AS 22 column to enable a rapid and simultaneous analysis of different IL and halide anions within an acceptable run-time (22 min) and with good resolution R of larger than 2.4, a capacity k′ between 0.4 and 5.1, selectivities α between 1.3 and 2.1, and peak asymmetries Asof less than 1.5. Halide impurities below 1 ppm (1 mg·L–1of prepared sample solution) could be quantified. A range of ionic liquids with tetrafluoroborate [BF4]–, hexafluorophosphate [PF6]–, and bis(trifluoromethylsulfonyl)imide (triflimide) [NTf2]–anions combined with cations based on imidazole, pyridine, and tetrahydrothiophene could be analyzed for their anion purity. The IL-cations do not influence the chromatographic results. With the analysis of 18 ILs differing in their cation-anion combination we could prove the general applicability of the described method for the anion purity analysis of ionic liquids with respect to halide ions. The IL-anion purity of most ILs was above 98 wt %. The highest IL-anion purity was 99.8 wt %, implying anion impurities of only 0.2 wt %. The used halide anion from the synthesis route was the major anion impurity, yet with chloride also bromide and fluoride (potentially from hydrolysis of [BF4]–) were often detected. When iodide was used, at least chloride but sometimes also bromide and fluoride was present. However, even if the IL-anion content is above 99 wt %, it does not necessarily indicate an ionic liquid devoid of other impurities. From the IC analysis, one can also deduce a possible cation impurity if one takes into account the expected (calculated) IL-anion content. A matching experimental and theoretical IL-anion content excludes, a higher experimental content indicates the presence of residual KBF4, NH4PF6, or LiNTf2salt from the halide to IL-anion exchange.
- Rutz, Christina,Schmolke, Laura,Gvilava, Vasily,Janiak, Christoph
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supporting information
p. 130 - 135
(2017/02/05)
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- Determination of residual chloride content in ionic liquids using LA-ICP-MS
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Nowadays, ionic liquids (ILs) are used in a wide range of applications. Their exceptional chemical and physical properties, sustainability of use and the possibility of easy recycling are attractive aspects promoting the acceptance of ILs also for commercial applications. While synthesis is in most cases simple and straightforward, purification of the reaction products might pose a number of problems. Due to the major influence of inorganic contaminations from the synthesis process, thorough monitoring of impurities is required. However, the unusual properties of ILs create some problems for conventional chemical analysis. In this work, a dried droplet approach with subsequent LA-ICP-MS sampling will be used for the analysis of chloride in ILs-a by-product from the synthesis procedure. Dried droplet application onto pre-cut filter paper disks allows the analysis of hydrophilic as well as hydrophobic ILs with calibration from dried aqueous standards for signal quantification. The approach is applied on two types of alkylimidazolium ILs, underlining the versatility of the sample preparation and measurement approach. Compared to commonly used analysis techniques for chloride in ILs, the presented approach is simple, fast, and does not require harmful reagents. Different internal standardization strategies were investigated during this study. With a reproducibility of below 2% relative standard deviation and limits of detection of 0.09 mg g-1 for chloride in ILs, the presented approach was showed to be fit for the purpose of routine analyses and reaction monitoring. If necessary, the approach can be extended to other analytes of interest in the field of the synthetic chemistry of ILs.
- Bonta, Maximilian,Anderl, Thomas,Cognigni, Alice,Hejazifar, Mahtab,Bica, Katharina,Limbeck, Andreas
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p. 90273 - 90279
(2016/10/07)
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- Impregnation of different ionic liquids onto cationic starch and their comparison in the extraction of Th(IV)
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Cationic starch (CS) was prepared by using epichlorohydrin (EPI) and 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTMA) and ionic liquids (ILs) having different anionic groups [1-butyl-3-methyl imidazolium tetrafluoroborate (BMI+ BF-4), ),lyhtem-3-lytub-1imidazolium (BMIIMB(+ Br Br-), 1-butyl-3-methyl imidazolium hexafluorophosphate (BMI+ PF-6 ), and 1-butyl-3-methyl imidazolium bis-[(trifluoromethyl)sulfonyl]imide (BMI+ [(TF)2 N]-)] were impregnated onto CS. Thorium(IV) ions were preconcentrated by using IL impregnated CS. The effects of ILs were investigated for extraction of Th(IV) by CS and the results were compared. Th(IV) was preconcentrated with approximately 73% sorption capacity by CS and increased up to 98%-100% for IL impregnated sorbents at pH 7.0. The sorption capacities of Th(IV) were 0.453 mmol g-1 , 0.399 mmol g-1 , 0.281 mmol g-1 , and 0.183 mmol g-1 CS-BMI+ Br- , CS-BMI+ [(TF)2 N], CS-BMI+ PF-6 andCS-BMI+ BF-4 , respectively. The elution occurred with HCl and NaOH solutions at pH 7.0. for.
- Bursali, Elif Ant,Bozkurt, Serap Seyhan,Yurdako?, Mürüvvet
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p. 364 - 372
(2016/05/24)
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- Liquid-Crystalline Ionic Liquids as Ordered Reaction Media for the Diels–Alder Reaction
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Liquid-crystalline ionic liquids (LCILs) are ordered materials that have untapped potential to be used as reaction media for synthetic chemistry. This paper investigates the potential for the ordered structures of LCILs to influence the stereochemical outcome of the Diels–Alder reaction between cyclopentadiene and methyl acrylate. The ratio of endo- to exo-product from this reaction was monitored for a range of ionic liquids (ILs) and LCILs. Comparison of the endo:exo ratios in these reactions as a function of cation, anion and liquid crystallinity of the reaction media, allowed for the effects of liquid crystallinity to be distinguished from anion effects or cation alkyl chain length effects. These data strongly suggest that the proportion of exo-product increases as the reaction media is changed from an isotropic IL to a LCIL. A detailed molecular dynamics (MD) study suggests that this effect is related to different hydrogen bonding interactions between the reaction media and the exo- and endo-transition states in solvents with layered, smectic ordering compared to those that are isotropic.
- Bruce, Duncan W.,Gao, Yanan,Canongia Lopes, José Nuno,Shimizu, Karina,Slattery, John M.
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supporting information
p. 16113 - 16123
(2016/10/26)
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- Nitrogen: Versus phosphorus nucleophiles-how changing the nucleophilic heteroatom affects ionic liquid solvent effects in bimolecular nucleophilic substitution processes
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A series of nitrogen and phosphorus nucleophiles have been investigated to determine whether the previously established ionic liquid solvent effects on a bimolecular nucleophilic substitution (SN2) reaction vary with the nature of the nucleophilic centre. Reaction of group 15 triphenyl nucleophiles with benzyl bromide showed a different trend in the rate constant with increasing proportions of ionic liquid in the reaction mixture than was observed with pyridine. This result suggests additional interactions are important; a supposition supported by differences in reaction outcome observed when the electrophile was varied in reactions with triphenylphosphine. A novel ionic liquid solvent effect was observed in the reaction of tributylamine with benzyl bromide, with the position of equilibrium varying with the proportions of the ionic liquid present in the reaction mixture. Overall, the work presented demonstrates the importance of considering all possible interactions between an ionic liquid solvent and species along the reaction coordinate and has expanded upon our current predictive framework for ionic liquid solvent effects. Such understanding is important as it allows further development of a predictive framework for the application of ionic liquids in preparative chemistry.
- Schaffarczyk McHale, Karin S.,Hawker, Rebecca R.,Harper, Jason B.
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supporting information
p. 7437 - 7444
(2016/09/12)
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- A neutral ionic liquid catalytic conversion of glycerol carbonate green synthetic method (by machine translation)
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The invention discloses a glycerol carbonate green synthetic method, the synthetic method is using glycerol and urea as the substrate, in the neutral ion liquid in the catalytic system 140-160 °C fully under the conditions of the reaction, the resulting mixture through the extraction and separation, purification, dried to obtain the glycerin carbonate compound. The preparation process of the present invention is simple, mild reaction conditions, to replace metal as a traditional method of the catalyst, catalytic reaction system using ionic liquid, environment-friendly, good repeatability, ion liquid preparation process green and have very good atom economy. (by machine translation)
- -
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Paragraph 0037-0038
(2017/03/17)
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- One-pot water-free ionic liquids synthesis using trialkyl orthoesters
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The present invention relates to a manufacturing method of an ionic liquid, including a step of manufacturing an amine based compound or a heterocyclic compound including alkylated nitrogen made by making a negative ion salt compound and trialkyl ortho esters react with at least one among heterocyclic compounds with nitrogen and amine based compounds.COPYRIGHT KIPO 2015
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Paragraph 0066-0069
(2016/10/10)
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- Durability enhanced ionic liquid catalyst for Friedel-Crafts reaction between benzene and 1-dodecene: Insight into catalyst deactivation
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Friedel-Crafts alkylation of benzene with 1-dodecene, which is an important reaction of synthetic detergent, was studied using the catalyst [bmim][TFSI]/AlCl3 (1-butyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imide/AlCl3). These ionic liquid catalysts show biphasic behaviors at a specific condition. Active site species and Lewis acidity were determined by NMR and acetonitrile probe FT-IR. NMR spectroscopy investigations indicated that coordinated and uncoordinated [TFSI]- existed in the ionic liquid catalyst system simultaneously, while tetrahedral 4-coordinate Al2Cl7- was the main active species for Friedel-Crafts alkylation. The complex [AlClx(TFSI)y]- tends to decompose and release 4-coordinated Al2Cl7- and [TFSI]-. The phase behavior study of the ionic liquid [bmim][TFSI]/AlCl3 demonstrated that the upper phase could be used as an efficient heterogeneous catalyst when AlCl3/IL ≥ 1.5. Due to the presence of the anion [TFSI]- around the active sites, especially [TFSI]- at the uncoordinated state, the ionic liquid formed a stable and hydrophobic chemical environment, which enhanced catalyst durability. The influence of various reaction conditions including catalyst reusability on the alkylation reaction was studied, and the potential reasons for catalyst deactivation were discussed. The highest 2-LAB selectivity was more than 50% when 1-dodecene conversion was nearly 100%. Compared with liquid or solid acid catalyst, ionic liquid catalysts have many advantages concerning energy and the environment.
- He, Yibo,Wan, Chao,Zhang, Qinghua,Zhan, Xiaoli,Cheng, Dang-Guo,Chen, Fengqiu
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p. 62241 - 62247
(2015/08/03)
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- Combined effect of ether and siloxane substituents on imidazolium ionic liquids
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Ionic liquids (ILs) in combination with ether and siloxane substituents on the imidazolium cation, comprising of bis(trifluoromethylsulfonyl)imide (NTf2) anions, have been synthesized due to their low viscosities, high thermal stabilities and low melting or glass transition temperatures(Tg). The structural flexibility of the ether and siloxane substituents on the imidazolium center overcomes the effect of van der Waals forces and gives them desirable and unique physical properties. These novel ILs show low viscosities (～72 mPa s at 25 °C), high thermal stabilities up to 430°C, and a wide liquid range over 500°C. In addition, these ILs exhibit only an amorphous glassy state on cooling at Tg below -74°C and cannot order properly to afford crystallization. The detailed thermal stability, phase transitions and heat capacity were studied by TGA, DSC and temperature-modulated DSC analysis. More importantly, we have also reported the large-scale (one kilogram) microwave-assisted synthesis of ILs [BMIM]Br and [1O2O2-Im-2O1]I as efficient and greener processes.
- Chavan, Santosh N.,Mandal, Debaprasad
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p. 64821 - 64831
(2015/08/18)
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- Insights into water coordination associated with the CuII/ CuI electron transfer at a biomimetic Cu centre
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The coordination properties of the biomimetic complex [Cu(TMPA)(H 2O)](CF3SO3)2 (TMPA = tris(2-pyridylmethyl)amine) have been investigated by electrochemistry combined with UV-Vis and EPR spectroscopy in different non-coordinating media including imidazolium-based room-temperature ionic liquids, for different water contents. The solid-state X-ray diffraction analysis of the complex shows that the cupric centre lies in a N4O coordination environment with a nearly perfect trigonal bipyramidal geometry (TBP), the water ligand being axially coordinated to CuII. In solution, the coordination geometry of the complex remains TBP in all media. Neither the triflate ion nor the anions of the ionic liquids were found to coordinate the copper centre. Cyclic voltammetry in all media shows that the decoordination of the water molecule occurs upon monoelectronic reduction of the CuII complex. Back-coordination of the water ligand at the cuprous state can be detected by increasing the water content and/or decreasing the timescale of the experiment. Numerical simulations of the voltammograms allow the determination of kinetics and thermodynamics for the water association-dissociation mechanism. The resulting data suggest that (i) the binding/unbinding of water at the CuI redox state is relatively slow and equilibrated in all media, and (ii) the binding of water at CuI is somewhat faster in the ionic liquids than in the non-coordinating solvents, while the decoordination process is weakly sensitive to the nature of the solvents. These results suggest that ionic liquids favour water exchange without interfering with the coordination sphere of the metal centre. This makes them promising media for studying host-guest reactions with biomimetic complexes. This journal is the Partner Organisations 2014.
- Porras Gutierrez, Ana Gabriela,Zeitouny, Joceline,Gomila, Antoine,Douziech, Benedicte,Cosquer, Nathalie,Conan, Francoise,Reinaud, Olivia,Hapiot, Philippe,Le Mest, Yves,Lagrost, Corinne,Le Poul, Nicolas
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p. 6436 - 6445
(2014/04/17)
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- A general and direct synthesis of imidazolium ionic liquids using orthoesters
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A general method to synthesize halide and halide-free ionic liquids was developed. Direct alkylation of imidazole and pyridine derivatives was performed in the presence of an acid using an orthoester as the alkyl donor yielding ionic liquid products. Residual Cl and water contents of the ionic liquids were determined by ion chromatography and a Karl-Fisher test. the Partner Organisations 2014.
- Kim, Do Joong,Oh, Kyung Hwan,Park, Jin Kyoon
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supporting information
p. 4098 - 4101
(2014/11/07)
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- Determination of halide impurities in ionic liquids by total reflection X-ray fluorescence spectrometry
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The determination and quantification of halide impurities in ionic liquids is highly important because halide ions can significantly influence the chemical and physical properties of ionic liquids. The use of impure ionic liquids in fundamental studies on solvent extraction or catalytic reactions can lead to incorrect experimental data. The detection of halide ions in solution by total reflection X-ray fluorescence (TXRF) has been problematic because volatile hydrogen halide (HX) compounds are formed when the sample is mixed with the acidic metal standard solution. The loss of HX during the drying step of the sample preparation procedure gives imprecise and inaccurate results. A new method based on an alkaline copper standard Cu(NH3) 4(NO3)2 is presented for the determination of chloride, bromide, and iodide impurities in ionic liquids. The 1-butyl-3-methylimidazolium ([C4mim]) ionic liquids with the anions acetate ([C4mim][OAc]), nitrate ([C4mim][NO3]), trifluoromethanesulfonate ([C4mim][OTf]), and bis(trifluoromethylsulfonyl)imide ([C4mim][Tf2N]) were synthesized via a halide-free route and contaminated on purpose with known amounts of [C4mim]Cl, [C4mim]Br, [C4mim]I, or potassium halide salts in order to validate the new method and standard.
- Vander Hoogerstraete, Tom,Jamar, Steven,Wellens, Sil,Binnemans, Koen
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p. 3931 - 3938
(2014/05/06)
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- Eu3 + as a dual probe for the determination of IL anion donor power: A combined luminescence spectroscopic and electrochemical approach
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This work is aimed at giving proof that Eu(Tf2N)3 (Tf2N = bis(trifluoromethanesulfonyl)amide) can act as both an optical and electrochemical probe for the determination of the Lewis acidity of an ionic liquid anion. For that reason the luminescence spectra and cyclic voltammograms of dilute solutions of Eu(Tf2N)3 in various ionic liquids were investigated. The Eu2 +/3 + redox potential in the investigated ILs can be related to the Lewis basicity of the IL anion. The IL cation had little influence. The lower the determined halfwave potential, the higher the IL anion basicity. The obtained ranking can be confirmed by luminescence spectroscopy where a bathochromic shift of the 5D 0 → 7F4 transition indicates a stronger Lewis basicity of the IL anion.
- Babai, Arash,Kopiec, Gabriel,Lackmann, Anastasia,Mallick, Bert,Pitula, Slawomir,Tang, Sifu,Mudring, Anja-Verena
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p. 191 - 198
(2014/05/20)
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- A silver and water free metathesis reaction: A route to ionic liquids
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A versatile, cheaper, silver and water-free metathesis reaction was developed for imidazolium, phosphonium and pyrrolidinium based ionic liquids (ILs) associated with different anions such as dicyanamide, thiocyanate, tetrafluoroborate and bis(trifluoromethylsulfonyl)imide. This route, using the melt of amine chloride as a solvent and reagent, favours the ion exchange reaction using anion salts of Na or Li, yielding ionic liquids in high purity (≥99.5%) and high yields (≥90%). This route is particularly well adapted for water miscible ILs preparation.
- Srour, Hassan,Rouault, Helene,Santini, Catherine C.,Chauvin, Yves
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supporting information
p. 1341 - 1347
(2013/06/05)
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- Lower critical solution temperature phase behavior of poly(n -butyl methacrylate) in ionic liquid mixtures
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Ionic liquids feature a combination of properties that make them very interesting solvents for polymers, but many questions remain regarding the thermodynamics of polymer/ionic liquid solutions. In this work, the lower-critical-solution-temperature (LCST) phase behavior of poly(n-butyl methacrylate) (PnBMA) in mixtures of the ionic liquids 1-butyl-3- methylimidazolium:bis(trifluoromethylsulfonyl)imide ([BMIm][TFSI]) and 1-ethyl-3-methylimidazolium:TFSI ([EMIm][TFSI]) is characterized by transmittance, light scattering, and small-angle neutron scattering measurements. Several relevant thermodynamic parameters are easily tuned by varying the ionic liquid composition. In particular, the cloud point, spinodal, and Θ temperatures are all found to increase linearly with [BMIm] content. The interaction parameters, χ, are determined as a function of temperature and concentration using three different methods, and the results from each method are compared. The entropic and enthalpic components of the interaction parameter, χ, are also found to vary linearly with [BMIm] content in the ionic liquid, increasing and decreasing, respectively. The increase in the enthalpic driving force for mixing with increasing [BMIm] content dominates over the decrease in the entropic penalty for mixing, leading to improved solubility. This result is discussed in terms of molecular interactions and oriented solvation. This work characterizes the solution thermodynamics of one representative system in a very interesting class of polymer solutions, and provides insight into the molecular mechanisms underlying its LCST phase behavior.
- Hoarfrost, Megan L.,He, Yanpu,Lodge, Timothy P.
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p. 9464 - 9472
(2014/01/06)
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- Steric, hydrogen-bonding and structural heterogeneity effects on the nucleophilic substitution of N-(p-fluorophenyldiphenylmethyl)-4-picolinium chloride in ionic liquids
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The nucleophilic substitution of N-(p-fluorophenyldiphenylmethyl)-4- picolinium chloride was investigated using water and a range of alcoholic nucleophiles in ionic liquid solvents. The reactivity patterns across the nucleophiles examined could be attributed to steric factors, which mediated the relative nucleophilicities. Reducing the hydrogen-bond acidity of the ionic liquid cation was found to generally increase the rate of reaction, however, the magnitude of this rate effect could be influenced by the steric bulk of the nucleophile and the structural heterogeneity of the ionic liquid. Preferential solvation phenomena in binary mixtures of ionic liquids were examined and suggest that the mechanism behind the hydrogen-bond solvation phenomenon arises from direct cation-mediated, rather than indirect anion-mediated, effects. The Royal Society of Chemistry 2013.
- Weber, Cameron C.,Masters, Anthony F.,Maschmeyer, Thomas
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supporting information
p. 2534 - 2542
(2013/06/05)
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- Effect of ionic liquids on the conformation of a porphyrin-based viscometer
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Structure of the cationic and anionic counterparts of ionic liquids has a significant impact on the conformational bias of the porphyrin rotor; an apparent correlation between the conformation and the viscosity of ionic liquids was noted, albeit it was found to be distinct and more complex from that found in molecular solvents.
- Jameson, Laramie P.,Kimball, Joseph D.,Gryczynski, Zygmunt,Balaz, Milan,Dzyuba, Sergei V.
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p. 18300 - 18304
(2013/10/21)
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- Various metal nanoparticles produced by accelerated electron beam irradiation of room-temperature ionic liquid
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Various metal nanoparticles including base metal were produced by a brief accelerated electron beam irradiation of 1-alkyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)amide room-temperature ionic liquid without a stabilizing agent, which is usually employed so as to prevent aggregation.
- Tsuda, Tetsuya,Sakamoto, Taiki,Nishimura, Yoshitomo,Seino, Satoshi,Imanishi, Akihito,Kuwabata, Susumu
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supporting information; experimental part
p. 1925 - 1927
(2012/03/13)
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- Standard pKa scales of carbon-centered indicator acids in ionic liquids: Effect of media and structural implication
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Energetics of bond dissociation, especially the R-H bond heterolysis free energy (pKa), has played a central role in promoting chemistry to become a rational science. Despite the oceans of acidity studies in the literature, the current knowledge is limited to that in the classical molecular solvents and is unable to be extended to anticipate the acidity changes in ionic media. As the latter is now very popular for replacing volatile organic solvents, it becomes highly desirable to know how the driving force of bond cleavage is varied as the medium composition is switched from neutral molecules to the charged ions. Here we describe a general approach to measure absolute pKa's in pure ionic liquid (IL). The standard conditions warranting accurate measurement were outlined. The pKa's of the selected 18 C-H type indicator acids in four ILs were determined and a convenient indicator platform was constructed for easy expansion of acidity scales. These absolute pKa's make possible, for the first time, direct comparisons of bond energies in IL with those in molecular solvent and in the gas phase and should be able to serve as the standard parameters for calibrating computational methods suitable for the studies in ionic media. The effect of cation and anion in IL in relation to structure was analyzed.
- Deng, Hui,Li, Xin,Chu, Yuan,He, Jiaqi,Cheng, Jin-Pei
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p. 7291 - 7298
(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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- Distinct influence of the anion and ether group on the polarity of ammonium and imidazolium ionic liquids
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The polarity of ionic liquids (ILs), usually denoted as ET(30) by the solvatochromic probe Reichardt's dye, is one of the most fundamental properties that remarkably affect the solvation and chemical reaction in ILs. It was generally accepted that the ET(30) of ILs was dominated by the nature of the cation. However, in this work, it was found that the common ammonium-based ILs showed strongly anion-dependent ET(30). For example, the ET(30) value for [N1124][DCA] and [N 1124][NTf2] is 49.0 and 59.0 kcal mol-1, respectively, while the corresponding imidazolium ILs bearing the same anions possess nearly identical ET(30), the ET(30) value for [BMIm][DCA] and [BMIm][NTf2] is 51.4 and 51.6 kcal mol-1, respectively. Moreover, introduction of an ether group was found to increase the ET(30) of imidazolium ILs while having no obvious effect on that of ammonium-based ILs. The Kamlet-Taft parameters and density functional theory (DFT) calculations indicated that the distinct result is related to different stabilization of the ground state of Reichardt's dye 30. In imidazolium ILs, the main interactions between ILs and zwitterionic dye involve both coulombic interaction (between the cation and the phenolate oxygen atom) and H-bonding interaction (between the acidic hydrogen on imidazolium ring and the phenolate oxygen atom). However, with the ammonium ILs lack of active hydrogen, the dye is only stabilized by the coulombic interaction between the cation and the phenolate oxygen atom. Interestingly, in both imidazolium and ammonium-based ILs, the spiropyran-merocyanine equilibrium exhibit obvious anion-dependent photochromism, solvatochromism, and thermal relaxation. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2012.
- Zhang, Shiguo,Chen, Zhengjian,Qi, Xiujuan,Deng, Youquan
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supporting information; experimental part
p. 1043 - 1050
(2012/07/14)
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- Addition of suitably-designed zwitterions improves the saturated water content of hydrophobic ionic liquids
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The saturated water content in a hydrophobic ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)-imide, was improved from 0.4 wt% to 17.8 wt% by adding a 3-(1-butyl-3-imidazolio)propanesulfonate- type zwitterion in appropriate amounts. The mixture containing 17.8 wt% water successfully dissolved horse heart cytochrome c without significant change of the higher ordered structure.
- Ito, Yoritsugu,Kohno, Yuki,Nakamura, Nobuhumi,Ohno, Hiroyuki
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supporting information
p. 11220 - 11222
(2013/01/15)
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- Microwave-assisted synthesis and spectral identification of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [Bmim]NTf 2 ionic liquid
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In this work, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide ([Bmim]NTf2), a room-temperature ionic liquid, was synthesized by two-step method. Firstly, the ionic liquid intermediate, alkylimidazolium containing bromo anion ([Bmim]Br) was synthesized from 1-methylimidazole (C 4H6N2) and 1-butyl bromide under microwave irradiation. Then [Bmim]Br reacted with lithium bis(trifluoromethanesulfony) imide (Li(CF3SO2)2N)to be [Bmim]NTf 2. The structure of [Bmim]NTf2 was characterized and analyzed by 1H NMR, infrared spectrum and UV-VIS spectrum.
- Wang, Ping,Yang, Mingdi,Su, Yongqing,Li, Cong
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experimental part
p. 4355 - 4357
(2012/02/04)
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- Phase behavior and crystalline phases of ionic liquid-lithium salt mixtures with 1-alkyl-3-methylimidazolium salts
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The thermal phase behavior of 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (IM10 RTFSI where R = 1, 2, or 4 for methyl, ethyl or butyl, respectively) ionic liquid binary mixtures with LiTFSI have been investigated as models for electrolytes for lithium batteries. Diverse phase behavior is found with significant variations noted from similar mixtures in which the imidazolium cations are replaced with N-alkyl-N- methylpyrrolidinium cations. The crystal structure for a (1-x) IM 101TFSI-(x) LiTFSI (x = 0.50) (or 1/1 IM101TFSI/LiTFSI) phase is reported to further clarify the molecular level interactions occurring in these binary salt mixtures.
- Zhou, Qian,Fitzgerald, Kendall,Boyle, Paul D.,Henderson, Wesley A.
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experimental part
p. 1203 - 1208
(2011/10/09)
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