Densities and viscosities for ionic liquids mixtures containing [eOHmim][BF4], [bmim][BF4] and [bpy][BF4]

Densities and viscosities of binary ionic liquids mixtures, 1-(2-hydroxyethyl)-3-methylimidazolium tetrafluoroborate ([eOHmim][BF₄]) + 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF₄]), 1-(2-hydroxyethyl)-3-methylimidazolium tetrafluoroborate ([eOHmim][BF₄]) + N-butylpyridinium tetrafluoroborate ([bpy][BF₄]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF₄]) + N-butylpyridinium tetrafluoroborate ([bpy][BF₄]) were measured over the entire mole fraction from T = (298.15 to 343.15) K. The excess molar volumes were calculated and correlated by Redlich–Kiser polynomial expansions. The viscosities for pure ionic liquids were analyzed by means of the Vogel–Tammann–Fulcher equation and ideal mixing rules were applied for the ILs mixtures.     

A comparative study on the ionic liquid [bmim][BF4] and its solution with transient absorption spectroscopy

A detailed study was explored to compare the transient absorption spectra of the neat 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF₄]) with its solution in water or acetonitrile. It was concluded that the excited triplet state ³[bmim]^+* was produced after 266 nm laser irradiation, and then the neutral radical [bmim] and the cation radical [bmim] ²⁺ were formed through two possible paths. The transient absorption spectra of the neat [bmim][BF₄] and its solution were similar but the reaction kinetics were different due to their different local structures such as dimeric or cluster. The energy transfer between excited [bmim][BF₄] and β-carotene further affirmed the existence of ³[bmim]^+*. And the reaction that the hydrated electron captured by [bmim]⁺ to produce [bmim] in solution was observed.     

Molecular dynamics simulation of room-temperature ionic liquid mixture of [bmim][BF4] and acetonitrile by a refined force field

1-Butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) is one of the promising room-temperature ionic liquids. To test the refined force field for [bmim][BF4] proposed in our previously work (J. Phys. Chem. B, 2004, 108, 12978-12989), thermodynamic properties of mixtures of [bmim][BF4](1)+ acetonitrile (2) are presented by using molecular dynamics over the whole concentration range. The calculated densities are in good agreement with the experimental data with deviations less than 2%, indicating the force field is applicable to the mixtures. In addition, the diffusion constants, viscosities, heats of vaporization, cohesive energy densities and excess properties of the mixtures are reported. The microscopic structures are discussed in detail, corresponding to the thermodynamic properties.     

Refined potential model for atomistic simulations of ionic liquid [bmim][PF6

Refined parameters of an atomistic interaction potential model for the room temperature ionic liquid 1-n-butyl,3-methylimidazolium hexafluorophosphate are presented. Classical molecular dynamics simulations have been carried out to validate this fully flexible all-atom model. It predicts the density of the liquid at different temperatures between 300 and 500 K within 1.4% of the experimental value. Intermolecular radial distribution functions and the spatial distribution functions obtained from the new model are in close agreement with ab initio simulations. The calculated diffusion coefficients of ions and the surface tension of the liquid agree well with experiment.     

Ordering layers of [bmim][PF6] ionic liquid on graphite surfaces: molecular dynamics simulation

Microscopic structures of room temperature ionic liquid (IL) [bmim][PF6] on hydrophobic graphite surfaces have been studied in detail by molecular dynamics simulation. It is clearly shown that both the mass and electron densities of the surface adsorbed ionic liquid are oscillatory, and the first peak adjacent to the graphite surface is considerably higher than others, corresponding to a solidlike IL bottom layer of 6 angstroms thick. Three IL layers are indicated between the graphite surface and the inner bulk IL liquid. The individually simulated properties of single-, double-, and triple-IL layers on the graphite surface are very similar to those of the layers between the graphite surface and the bulk liquid, indicating an insignificant effect of vapor-IL interface on the ordered IL layers. The simulation also indicates that the imidazolium ring and butyl tail of the cation (bmim+) of the IL bottom layer lie flat on the graphite surface.     

Interaction between room temperature ionic liquid [bmim]BF4 and DNA investigated by electrochemical micromethod

Ionic liquids (ILs) as a kind of novel green solvent are being widely used in various researches related to the life sciences and chemistry, which demands the knowledge of interaction between ILs and biomacromolecules. However, the almost completely inert optical, electric, thermal properties of ILs make it difficult to directly obtain information about the interactions. Herein, by using a hydrophilic ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF4) as a model, the electrostatic interaction between ILs and calf thymus DNA (ctDNA) was investigated by a surface electrochemical micromethod. A convenient and simple method was established to obtain the thermodynamic and kinetic information about the DNA-IL interaction only with microscale sample consumption. The quantitative thermodynamic and kinetic parameters about the interaction of [bmim]BF4 and ctDNA, such as the binding constant (K), the Gibbs energy of surface binding (DeltaGb), and the dissociation rate constant (k), were obtained for the first time.     

Efficient, green and regioselective synthesis of 1,4,5-trisubstituted-1,2,3-triazoles in ionic liquid [bmim]BF4 and in task-specific basic ionic liquid [bmim]OH

Convenient and environmentally benign procedures have been reported for the synthesis of 1,4,5-trisubstituted-1,2,3-triazoles by the reaction of aryl azides with active methylene compounds in ionic liquid [bmim]BF₄ in the presence of l-proline as a catalyst and also in task-specific basic ionic liquid [bmim]OH. The methodologies defined herein avoid the severe conditions as posed by earlier existing methods and proved to be efficient in terms of good yields, operational simplicity, easy workup and short reaction time.     

Inhibition ability of ionic liquid [Bmim][NO3], [Bmim][BF4], and [Emim][BF4] on spontaneous coal combustion

Journal of Thermal Analysis and Calorimetry - From TG result, [Bmim][BF4] has the best inhibition ability of spontaneous coal combustion to delay the initial temperature, maximum temperature, and...     

Nonaqueous microemulsion-containing ionic liquid [bmim][PF6] as polar microenvironment

The phase behavior of toluene/Triton X-100 (TX-100)/1-butyl-3-methylimidazolium hexafluorophosphate([bmim][PF6]) was studied. It was demonstrated that the single-phase microemulsion area covered about 75% of the phase diagram at 25 °C. Electrical conductivities of the system with different w ([bmim][PF6]-to-TX-100 molar ratio) values were determined, and the results were used to locate the sub-regions of the single-phase microemulsion. The results showed that a transform from [bmim][PF6]-in-oil ([bmim][PF6]/O) microstructure via a bicontinuous region to an oil-in-[bmim][PF6] (O/[bmim][PF6]) microstructure occurred with the increase of Φ (weight fraction of TX-100 and [bmim][PF6] in the system). The aggregate size of the reverse microemulsions of [bmim][PF6]/O was determined using small-angle X-ray scattering. The results showed that the size of the reverse microemulsions depended markedly on the w values.     

Ionic liquid [bmim][BF4] acts as solvent and promoter for synthesis of halo-containing N-arylphthalimides

A new synthetic process of N-arylphthalimide and halo-containing N-arylphthalimides through the reaction between phthalic anhydride and aromatic amines bearing halo groups in[bmim][BF_4]was described,ionic liquid[bmim][BF_4]acted as the dual role of solvent and promoter.     

Shear viscosity of the ionic liquid 1-n-butyl 3-methylimidazolium hexafluorophosphate [bmim][pf6] computed by reverse nonequilibrium molecular dynamics

Reverse nonequilibrium molecular dynamics and equilibrium molecular dynamics simulations were carried out to compute the shear viscosity of the pure ionic liquid system [bmim][PF 6] at 300 K. The two methods yielded consistent results which were also compared to experiments. The results showed that the reverse nonequilibrium molecular dynamics (RNEMD) methodology can successfully be applied to computation of highly viscous ionic liquids. Moreover, this study provides a validation of the atomistic force-field developed by Bhargava and Balasubramanian ( J. Chem. Phys. 2007, 127, 114510 ) for dynamic properties.     

Coexistence curves of ionic liquid in oil microemulsions of {[bmim][BF4] + T-X100 + cyclohexane} with various molar ratio of [bmim][BF4] to T-X100 in the critical region

The coexistence curves (T, n), (T, Φ), and (T, Ψ) (n, Φ, and Ψ are the refractive index, volume fraction, and effective volume fraction, respectively) for the ionic liquid microemulsion systems of {polyoxyethylene tert-octylphenyl ether (T-X100) + 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF₄]) + cyclohexane} with various molar ratio (ω) of [bmim][BF₄] to T-X100 have been determined by measuring refractive indices at a constant pressure in the critical region. The critical temperatures (T_c) and critical volume fraction (Φ_c) were obtained for the ionic liquid microemulsions. The critical exponents were deduced precisely from the coexistence curves within about 1 K below T_c and the values were consistent with the 3D Ising value.     

Insights into the structure and dynamics of a room-temperature ionic liquid: ab initio molecular dynamics simulation studies of 1-n-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) and the [bmim][PF6]-CO2 mixture

Ab initio molecular dynamics (AIMD) studies have been carried out on liquid 1-n-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) and its mixture with CO2 using the Car-Parrinello molecular dynamics (CPMD) method. Results from AIMD and empirical potential molecular dynamics (MD) have been compared and were found to differ in some respects. With a strong resemblance to the crystal, the AIMD simulated neat liquid exhibits many cation-anion hydrogen bonds, a feature that is almost absent in the MD results. The anions were observed to be strongly polarized in the condensed phase. The addition of CO2 increased the probability of this hydrogen bond formation. CO2 molecules in the vicinity of the ions of [bmim][PF6] exhibit larger deviations from linearity in their instantaneous configurations. The polar environment of the liquid induces a dipole moment in CO2, lifting the degeneracy of its bending mode. The calculated splitting in the vibrational mode compares well with infrared spectroscopic data. The solvation of CO2 in [bmim][PF6] is primarily facilitated by the anion, as seen from the radial and spatial distribution functions. CO2 molecules were found to be aligned tangential to the PF6 spheres with their most probable location being the octahedral voids of the anion. The structural data obtained from AIMD simulations can serve as a benchmark to refine interaction potentials for this important room-temperature ionic liquid.     

Ionic Liquid [bmim][BF4] as a Green Medium for Passerini Reaction

The Passerini reaction, a three-component condensation reaction of carboxylic acid, aldehyde and isocyanide constructing an α-acyloxycarboxamide in a single step, was first discovered by Passerini about 80 years ago1. Since then, this reaction has been w…     

Vapor-liquid-liquid equilibria of pentafluoroethane and ionic liquid [bmim][PF6] mixtures studied with the volumetric method

In this article, we investigate vapor-liquid-liquid equilibria (VLLE) of binary systems using a simple volumetric method. Being different from the usual cloud-point method for the determination of liquid-liquid separation boundaries, the present volumetric method is able to determine the direct VLLE properties, such as equilibrium compositions, as well as molar volumes of the two liquid phases, by measuring only weights and volumes of liquid samples. The theory behind this method is described, and detailed error analyses for our simple apparatus are discussed by using well-established systems in the literature: water + 2-butanol and 1-butanol + 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF(6)]). Then, results for mixtures of [bmim][PF(6)] and pentafluoroethane (R-125) are provided, as well as those of the test systems above. As predicted in our earlier work, this binary system shows liquid-liquid separations in the R-125-rich side solutions with a lower critical solution temperature. In addition, we have found very large negative excess molar volumes in this system.     

离子液体[bmim]PTSA的微波合成

近年来,随着绿色化学的兴起,离子液体作为一种新型的绿色溶剂已成为国内外科研工作者的研究热点之一.离子液体是由有机阳离子和无机阴离子组成的盐,可以根据需要控制阴阳离子的组成和结构,设计合成出不同特性的离子液体[1].     

Layering at an ionic liquid-vapor interface: a molecular dynamics simulation study of [bmim][PF6

The structure of the planar liquid-vapor interface of a room-temperature ionic liquid, 1-n-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]), is studied using atomistic molecular dynamics simulations. Layering of the ions at the interface is observed as oscillations in the corresponding number density profiles. These oscillations, however, are diminished in amplitude in the electron density profile, due to a near cancellation in the contributions from the anions and the cations. An enhancement by 12% in the electron density at the interface over its value in the bulk liquid is observed, in excellent agreement with X-ray reflectivity experiments. The anions are found to predominantly contribute to this increase in the interfacial electron density. The cations present at the interface are oriented anisotropically. Their butyl chains are observed to be preferentially oriented along the interface normal and to project outside the liquid surface, thus imparting a hydrophobic character. In the densest region of the interface, the imidazolium ring plane is found to lie parallel to the surface normal, in agreement with direct recoil spectroscopy experiments.     

A new type of microemulsion containing task-special ionic liquid [NH2ebim][BF4]

The formation of microemulsions in the presence of cyclohexane, Triton X-100, n-butanol, water, and task-special ionic liquid (TSIL) (1-2-aminoethyl-3-butylimidazolium tetrafluoroborate) was studied at 25°C. The phase behavior of this ternary system was investigated. Three subregions (namely, water-in-oil phase, bicontinuous phase, and oil-in-water phase) were identified in the single-phase region by dynamic light scattering (DLS) technique and electrical conductivity measurement. Microstructures of microemulsions with different water contents have been predicted by using dissipative particle dynamics (DPD) simulation. It was found that the DPD simulations successfully reproduce the experimental results in the article. The location of TSIL in the microemulsions was predicted by DPD simulation further. The result indicates that TSIL is more easy to locate in the surfactant and cosurfactant layer and has amphiphilicity, which provides us new insights into the potential applications of TSIL-based microemulsions in separation and new nano-scale material preparation because of the interaction of TSIL with some special components at the interface of oil and water.     

离子液体[bmim][dca]的微波辅助合成及其对几种糖的溶解性能

以N-甲基咪唑为母体,在微波辐射下经两步法合成了一种功能化离子液体溴化1-正丁基-3-甲基咪唑双氰胺盐([bmim][dca])。采用单因素试验法优化了合成条件:[bmim]Br与Na[N(CN)2]的摩尔比1∶1.1,丙酮作溶剂,微波功率800W,微波反应温度50℃,反应时间1h。在此条件下,[bmim][dca]收率可达85.2%。并通过IR对目标产物进行了分析和表征。通过溶解度测试得知,离子液体[bmim][dca]对蔗糖、葡萄糖和β-环糊精有良好的溶解能力,其中对β-环糊精的溶解效果最好。