疏水性咪唑类离子液体的水浴微波合成

以溴代烷烃、N-甲基咪唑和六氟磷酸铵为原料,采用水浴微波法合成了3种疏水性咪唑类离子液体:[bmim]PF6、[hmim]PF6和[omim]PF6.结果表明,与传统方法相比,水浴微波法产率较高,且反应时间由传统的36 h缩短至50 min.通过正交试验对离子液体[bmim]PF6的水浴微波合成反应条件进行了优化,得到了适宜的合成条件:反应时间50 min,n(1-溴正丁烷)∶n(N-甲基咪唑)∶n(六氟磷酸铵)为1.1∶1.0∶1.0,微波功率385 W,产率可达到94.54%.结合反应机理对优化结果进行了分析,并通过红外光谱验证了3种疏水性离子液体的结构.     

Functional thiol ionic liquids as novel interfacial modifiers in SBR/HNTs composites

Two kinds of thiol ionic liquids (ILs), 1-methylimidazolium mercaptopropionate (MimMP) and bis (1-methylimidazolium) mercaptosuccinate (BMimMS), were investigated as novel interfacial modifiers for styrene butadiene rubber/halloysite nanotubes (SBR/HNTs) composites. According to model compounds, it was found that their affinities toward HNTs were originated from hydrogen bonding and that they could be grafted onto SBR chains via thiol-ene reactions. The ILs addition could promote vulcanization and effectively facilitate HNTs dispersion in rubber matrix. The interfacial interaction, quantitatively evaluated by a proposed equation based on rubber elasticity and reinforcement theory, was consistently increased. Mechanical properties of SBR/HNTs vulcanizates were largely improved and better than those of the 3-mercaptopropyl trimethoxysilane modified system. The BMimMS’s efficiency on modifying SBR/HNTs vulcanizates was higher than the other for its Gemini structure. Significantly mechanical improvements and lowered mechanical loss in the range of 50-80 °C were correlated to the improved HNTs dispersion and strengthened interfacial interactions.     

Effects of imidazolium-based ionic liquids on the isobaric vapor–liquid equilibria of methanol + dimethyl carbonate azeotropic systems

The separation of methanol(MeOH) and dimethyl carbonate(DMC) is important but difficult due to the formation of an azeotropic mixture. In this work, isobaric vapor–liquid equilibrium(VLE) data for the ternary systems containing different imidazolium–based ionic liquids(ILs), i.e. MeOH + DMC + 1-butyl-3-methy-limidazolium bis[(trifluoromethyl)sulfonyl]imide([Bmim][Tf_2N]), MeOH + DMC + 1-ethyl-3-methyl-imidazolium bis[(trifluoromethyl)sulfonyl]imide([Emim][Tf_2N]), and MeOH + DMC + 1-ethyl-3-methylimidazolium hexafluorophosphate([Emim][PF6])) were measured at 101.3 kPa. The mole fraction of IL was varied from0.05 to 0.20. The experimental data were correlated with the NRTL and Wilson equations, respectively. The results show that imidazolium-based ILs were beneficial to improve the relative volatility of MeOH to DMC,and [Bmim][Tf_2 N] showed a much more excellent performance on the activity coefficient of MeOH. The interaction energies of system components were calculated using Gaussian program, and the effects of cation and anion on the separation coefficient of the azeotropic system were discussed.     

Comparative study on the extraction of trivalent americium and europium by CMPO in imidazolium-based ionic liquids and dodecane

The extraction of Am³⁺ and Eu³⁺ by octyl(phenyl)-N,N-diisobutyl carbamoylmethylphosphine oxide (CMPO) in eight imidazolium-based ionic liquids and in n-dodecane was studied and compared. Slope analysis indicates that the ligand/metal ratio in the extracted complexes in ionic liquids is much larger than that in n-dodecane. Nitric acid has different impacts on the extraction, depending greatly on the nature of the ionic liquids. A mixed-extraction mechanism, namely cation exchange plus the formation of neutral complexes (solvation), was proposed for the extraction in the ionic liquid systems. In addition, temperature was found to have a remarkable influence on the extraction. Highly exothermic enthalpy changes were obtained for the extraction in ionic liquid systems. This work provides further insight into the particular role played by the unique properties of ionic liquids in the extraction of metal ions from nitric acid media.     

咪唑类离子液体的合成与表征

采用溴丁烷与N-甲基咪唑为原料合成了中间体溴化1-丁基-3-甲基咪唑，并通过离子交换反应制备离子液体1-丁基-3-甲基咪唑六氟磷酸盐以及1-丁基-3-甲基咪唑四氟鹏酸盐。产物结构经FT-IR和1^HNMR确认，其纯度通过HPLC分析均达到99．0％以上。     

Electrochemical behavior of several iron complexes in hydrophobic room-temperature ionic liquids

The electrochemical behavior of FeCp₂⁺/FeCp₂ (Cp⁻, cyclopentadienyl), FeCl₄⁻/FeCl₄²⁻, FeBr₄⁻/FeBr₄²⁻ and Fe(CN)₆³⁻/Fe(CN)₆⁴⁻ couples was studied in the hydrophobic room-temperature ionic liquids based on bis(trifluoromethylsulfonyl)imide (TFSI⁻) with 1-n-butyl-1-methylpyrrolidinium (BMP⁺) and other quaternary ammonium cations. The cyclic voltammetric data indicated that these complexes were stable in BMPTFSI and that the redox reactions between trivalent and divalent iron species of these complexes are electrochemically reversible. The diffusion coefficients of these complexes were found to be affected mainly by the size of the species. On the other hand, the redox potential of Fe(CN)₆³⁻/Fe(CN)₆⁴⁻ couple depended on organic cations reflecting the difference in the acceptor properties of the organic cations.     

Covalent modification of boron-doped diamond electrodes with an imidazolium-based ionic liquid

An ionic liquid (IL, 1-(methylcarboxylic acid)-3-octylimidazolium-bis (trifluoromethylsulfonyl)imide) was covalently coupled onto a boron-doped diamond (BDD) surface through an esterification reaction. The resulting surface was characterized by X-ray photoelectron spectroscopy, water contact angle and electrochemical measurements. Selective electron transfer towards positively and negatively charged redox species was recorded. While the presence of Fe(CN)₆⁴⁻ could be detected on the IL-modified BDD interface, no surface-immobilized Ru(NH₃)₆³⁺ was recorded. The IL-modified BDD electrode showed in addition changes in surface wettability when immersed into aqueous solution containing different anions.     

Prediction of viscosity of imidazolium-based ionic liquids using MLR and SVM algorithms

In this work, two models, one integrating the fragment contribution-corresponding states (FC-CS) method with multiple linear regression (MLR) algorithm and another. With support vector machine (SVM) algorithm, are proposed to predict the viscosity of imidazolium-based ionic liquids (ILs). The FC-CS method is applied to calculate the pseudo-critical volume and compressibility factor (V_c and Z_c) as well as the boiling point temperature (T_b) which are employed to predict the viscosity with the MLR and SVM algorithms. A large data set of 1079 experimental data points of 45 imidazolium-based ILs covering a wide range of pressure and temperature is applied to validate the two models. The average absolute relative deviation (AARD) of the entire data set of the MLR and SVM is 24.2% and 3.95%, respectively. The nonlinear model developed by the SVM algorithm is much better than the linear model built by the MLR, which indicates the SVM algorithm is more reliable in the prediction of the viscosity of imidazolium-based ILs.     

疏水性离子液体萃取氯酚类物质

为了研究离子液体对环境水体中氯酚类物质的萃取性能, 以治理氯酚类污染物。制备了1-辛基-3-甲基咪唑六氟磷酸盐([Omim]PF₆) 和1-辛基-3-甲基咪唑氟硼酸盐([Omim]BF₄)两种疏水性离子液体。以超声波辅助萃取的方法, 研究了离子液体对2-氯苯酚(2-CP)、4-氯苯酚(4-CP)、2, 4-二氯苯酚(2, 4-DCP)和2, 4, 6-三氯苯酚(2, 4, 6-TCP)等化合物的萃取性能。考察了温度、时间、相比(V_IL:V_CP)以及溶液 pH 等因素对萃取效果的影响, 并对离子液体的重复使用性能进行了探讨。结果表明, 温度与相比对萃取效果影响显著。两种离子液体对氯酚均显示出良好的萃取性能。在308 K, 当相比(V_IL:V_CP)为1:3, 溶液pH=3, 萃取10 min的条件下, [Omim]BF₄对2-CP、4-CP、2, 4-DCP和2, 4, 6-TCP的萃取率分别为97.60%、95.20%、99.40%和87.20%;而以[Omim]PF₆为溶剂, 对氯酚的萃取率依次为95.80%、92.20%、98.20%和85.40%。研究发现, 与磁力搅拌萃取方法不同, 超声波辅助萃取的方法, 随温度升高离子液体对氯酚类物质的萃取率增大。     

Molecular insight into the effect of ion structure and interface behavior on the ammonia absorption by ionic liquids

Molecular dynamics simulations were performed to elucidate the roles of ion structure and interface behavior in absorption of gases (NH₃, N₂, H₂) by ILs (protic IL [Bim][Tf₂N] and conventional IL [Bmim][Tf₂N]). The results indicated that NH₃ compete with [Tf₂N]⁻ to interact with N3-H site of [Bim]⁺ cation, forming a strong N3 H∙∙∙N(NH₃) hydrogen bond with the energy of −79 kJ/mol, which is twice as much as the energy of the hydrogen bond between C2 H of [Bmim]⁺ and NH₃ (−33.2 kJ/mol). Moreover, there is a dramatic increase in the number density of cations near the IL-gas interface, resulting in the NH₃ molecules permeate into the bulk rapidly and effectively and achieving the high selective absorption of NH₃ to H₂ and N₂. Considering the inevitable trace water in the raw gases, the influence of water was studied and it was shown that trace water can enhance the absorption of NH₃ by [Bim][Tf₂N].     

Ionothermal synthesis of gallophosphate molecular sieves in 1-alkyl-3-methyl imidazolium bromide ionic liquids

Gallophosphate (GaPO₄) molecular sieves were ionothermally prepared in 1-alkyl-3-methyl imidazolium bromide ionic liquids (ILs) with alkyl chain length varying from 2 to 6 carbons for the first time. Three kinds of GaPO₄ materials such as GaPO₄-a, cloverite (denoted as CLO below) and GaPO₄-LTA were obtained, and their structures and morphologies were characterized by powder and single crystal XRD, SEM and multi-nuclear NMR. In the case of 1-ethyl-3-methyl imidazolium bromide ionic liquid, large single crystals of GaPO₄-LTA with well-defined octahedral morphology was obtained in both sealed (ca. 400 μm in size) and open vessels (ca. 300 μm in size). Ionothermal synthesis is an effective method for the preparation of large single crystal of molecular sieves. With the alkyl chain length of the ionic liquids increasing from 2 carbons to 6 carbons, the size of GaPO₄-LTA decreased sharply. The organic template cations in the as-synthesized GaPO₄-LTA crystals may have two different kinds of conformational structures. Fluorine plays a role of co-template along with organic cations of ILs in the synthesis of GaPO₄-LTA and CLO, while only GaPO₄-a was obtained in the absence of fluorine. The reaction temperature can also affect the structure of the final structure. In the reaction medium of 1-ethyl-3-methyl imidazolium bromide IL, GaPO₄-LTA was obtained at 180 °C, while CLO was obtained at 150 °C.     

Study of the conductivity behavior of pyridinium-based ionic liquids

In this work, ionic conductivity data as a function of temperature in the pyridinium-based ionic liquids 1-butylpyridinium tetrafluoroborate, 1-butylpyridinium triflate, 1-butyl-2-methylpyridinium tetrafluoroborate, 1-butyl-3-methylpyridinium tetrafluoroborate, 1-butyl-4-methylpyridinium tetrafluoroborate, 1-butyl-3-methylpyridinium dicyanamide, and 1-octyl-3-methylpyridinium tetrafluoroborate, are reported. A comparison of results for this series of ionic liquids has been used to evaluate the influence of the ionic structural characteristic in this transport property. Temperature dependence of experimental values has been fitted by means of the Vogel-Fulcher-Tammann equation, and from their parameters, maximum conductivity and activation energy for conduction have been derived. From conductivity parameters and the glass transition temperature, a detailed analysis has been performed in fragility terms. Finally, the classical Walden rule has been used to classify the ionic liquids depending on the relationship between conductivity and fluidity.     

离子液体的制备及其酸性研究

采用乙腈探针法和吡啶探针法测定了离子液体的酸性,研究了离子液体的分子结构与酸类型、酸强度的相关性。结果表明,乙腈探针法和吡啶探针法均能很好地区分离子液体的酸类型(Brnsted酸或Lewis酸),并可以粗略地指示离子液体的Lewis酸强度。     

Ab initio calculations of the interaction between thiophene and ionic liquids

The fundamental natures of the interaction between thiophene and ionic liquids of 1-n-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]⁺[PF₆]⁻) and 1-n-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]⁺[BF₄]⁻) were investigated using ab initio calculations and correlated with previous experimental results. The optimized structures show that the anions of the ionic liquids are situated outside the ring plane of the thiophene, with the fluorine atoms interacting with the hydrogen atoms of the thiophene, and the cation of the ionic liquids approaches the thiophene with its positively charged atoms approaching the negatively charged atoms of TS. It is concluded that thiophene molecules interact with the ionic liquids mainly via Coulombian attraction. Further analysis explained the results obtained from an absorption experiment that the molar ratios of the absorbed thiophene to the ionic liquids were approximately 3.5/1 and 2.4/1 for [BMIM]⁺[PF₆]⁻ and [BMIM]⁺[BF₄]⁻, respectively. The strong electron donation of the phosphorus atom to the fluorine atoms in the PF₆⁻ cluster is believed to be the major factor resulting in the higher molar ratio of thiophene/[BMIM]⁺[PF₆]⁻. The other factor is the difference of the compactness between the cation and the anion in the two ionic liquids.     

Ionic conductivity of polymer gels deriving from alkali metal ionic liquids and negatively charged polyelectrolytes

We have prepared polymer gel electrolytes with alkali metal ionic liquids (AMILs) that inherently contain alkali metal ions. The AMIL consisted of sulfate anion, imidazolium cation, and alkali metal cation. AMILs were mixed directly with poly(3-sulfopropyl acrylate) lithium salt or poly(2-acrylamido-2-methylpropanesulfonic acid) lithium salt to form polymer gels. The ionic conductivity of these gels decreased with increasing polymer fraction, as in general ionic liquid/polymer mixed systems. At low polymer concentrations, these gels displayed excellent ionic conductivity of 10⁻⁴ to 10⁻³ S cm⁻¹ at room temperature. Gelation was found to cause little change in the diffusion coefficient of the ionic liquid, as measured by pulse-field-gradient NMR. These data strongly suggest that the lithium cation migrates in successive pathways provided by the ionic liquids.     

Nanostructuration of ionic liquids in fluorinated matrix: Influence on the mechanical properties

In this work, a new method to prepare fluorinated coatings with mechanical properties enhanced has been developed. Pyridinium, imidazolium, and phosphonium ionic liquids have been synthesized and used as new synthetic building blocks in a polytetrafluoroethylene matrix. The strategy demonstrated using long alkyl chain cations provides an opportunity to prepare nanomaterials with a nanoscale structuration. The design of these new ionic and nanostructured materials is very dependent on the cation-anion combination of ILs. The morphology analyzed by transmission electronic microscopy (TEM) shows that it is clearly tuned by the chemical nature of ILs. The finest structuration leads to a dramatic compromise between stiffness and deformation of material. The small-angle X-Ray scattering (SAXS) shows the evolution of the ionic networks during the mechanical sollicitation.     

Comparative investigation on electrochemical behavior of hydroquinone at carbon ionic liquid electrode, ionic liquid modified carbon paste electrode and carbon paste electrode

Ionic liquid, 1-heptyl-3-methylimidazolium hexafluorophosphate (HMIMPF₆), has been used to fabricate two new electrodes, carbon ionic liquid electrode (CILE) and ionic liquid modified carbon paste electrode (IL/CPE), using graphite powder mixed with HMIMPF₆ or the mixture of HMIMPF₆/paraffin liquid as the binder, respectively. The electrochemical behaviors of hydroquinone at the CILE, the IL/CPE and the CPE were investigated in phosphate buffer solution. At all these electrodes, hydroquinone showed a pair of redox peaks. The order of the current response and the standard rate constant of hydroquinone at these electrodes were as follows: CILE > IL/CPE > CPE, while the peak-to-peak potential separation was in an opposite sequence: CILE < IL/CPE < CPE. The results show the superiority of CILE to IL/CPE and CPE, and IL/CPE to CPE in terms of promoting electron transfer, improving reversibility and enhancing sensitivity. The CILE was chosen as working electrode to determine hydroquinone by differential pulse voltammetry, which can be used for sensitive, simple and rapid determination of hydroquinone in medicated skin cosmetic cream.     

Imidazolium-based alkylphosphate ionic liquids - A potential solvent for extractive desulfurization of fuel

N-ethyl-imidazolium-based alkylphosphate ionic liquid (IL), viz. N-ethyl-N-methyl-imidazolium dimethylphosphate ([EMIM][DMP]), N-ethyl-N-ethyl-imidazolium diethylphosphate ([EEIM][DEP]) and N-butyl-N-ethyl-imidazolium dibutylphosphate ([BEIM][DBP]) were demonstrated to be effective for the removal of aromatic sulfur compounds (S-compound) 3-methylthiophene (3-MT), benzothiophene (BT) and dibenzothiophene (DBT) from fuel oils in terms of sulfur partition coefficients (K_N) at 298.15 K. It was shown that the extractive ability of the alkylphosphate ILs was dominated by the structure of the cation and followed the order [BEIM][DBP] > [EEIM][DEP] > [EMIM][DMP] for each S-compound studied with their K_N-value being 1.72, 1.61 and 1.17, respectively for DBT. For a specified IL the sulfur selectivity followed the order DBT > BT > 3-MT with their K_N-value being 1.61, 1.39 and 0.78, respectively for [EEIM][DEP]. The alkylphosphate ILs are insoluble in fuel while the fuel solubility in ILs varies from 20.6 mg(fuel)/g(IL) for [EMIM][DMP] to 266.9 mg(fuel)/g(IL) for [BEIM][DBP]. The results suggest that [EEIM][DEP] might be used as a promising solvent for the extractive desulfurization of fuel, considering its higher sulfur extractive ability, lower solubility for fuel and thus negligible influence on the constituent of fuel, and the ease of regeneration for the spent IL via water dilution process.     

Nanoscale electrodeposition of metals and compound semiconductors from ionic liquids

Employing ionic liquid electrolytes we succeeded to electrodeposit light and transition metals as well as compound semiconductors on metal and semiconductor substrates at room temperature with nanometer or atomic resolution. For this aim in situ scanning tunnelling microscopy (STM) and scanning tunnelling spectroscopy (STS) have been applied. In this article we present new and recent results of 2D phase formation and growth of Ga underpotential deposition (UPD) and of surface alloying of Cd on Au(1 1 1), as well as 3D overpotential deposition (OPD) of Ni nanocrystals and ZnSb semiconductor clusters. Particular attention is given to the respective nucleation and growth mechanisms of the selected examples. Aspects of technological applications are briefly discussed.     

离子液体的分类、合成及在氟化工艺中的应用

离子液体不挥发,无污染,无臭味,具有高选择性和催化作用,且易于循环回收利用,作为一种新型的高效绿色溶剂,以其突出的优势已成为绿色化学研究的热点之一。简要介绍了离子液体的分类、合成及其在氟化工艺中的应用。