氯化钽在离子液体1-丁基-3-甲基咪唑六氟磷酸盐中电化学行为

采用循环伏安法,研究了0.25 mol/L TaCl₅在离子液体1-丁基-3-甲基咪唑六氟磷酸盐([Bmim]PF₆)中的电化学行为。 实验结果表明,电沉积钽是受扩散控制、两步骤的不可逆电极反应过程,首先是Ta(Ⅴ)还原为Ta(Ⅲ),其次是Ta(Ⅲ)还原为金属钽和形成其它低价钽氯化物。 Ta(Ⅴ)/Ta(Ⅲ)和Ta(Ⅲ)/Ta在离子液体[Bmim]PF₆中的阴极传递系数分别为0.155和0.406。 Ta(Ⅴ)在离子液体[Bmim]PF₆中的扩散系数为1.629×10^-9 cm²/s。 在100 ℃和-1.25 V条件下,采用恒电势法在铂片上电沉积钽,扫描电子显微镜照片和EDS分析表明,沉积物为钽和钽的低价氯化物。     

基于离子液体的硫酸根离子选择电极的研究

将离子液体BMIMPF6应用于传感膜中制备硫酸根选择性电极,研究发现离子液体在电极中不仅能够提高传感膜的介电常数和传导速率,还与硫酸根离子发生相互作用,起到载体的功能。利用离子液体和硫脲的协同作用制备的电位传感器,对硫酸根离子在10-5～10-2 mol/L范围内有能斯特响应,同时具有pH干扰小,重复性好,响应时间快等特点,能够用于环境和生物医疗检测。     

DFT Study on the Structure of Ionic Liquid 1-Ethyl-3-methylimidazolium Hexafluorophosphate

1 INTRODUCTION Ionic compounds generally have high melting points and always exist in solid state since they are main- tained by electrovalent bonds. Ionic Liquids (ILs), which are liquids at or near ambient temperature, have been a class of ionic compounds extensively studied experimentally and theoretically in recent years[1, 2]. ILs consist exclusively of anions and ca- tions and do not contain any neutral molecule. They have many attractive properties, such as low vapor pressure, no…     

1-丁基-3-甲基咪唑六氟磷酸盐+水+醇体系的相行为

在298.15 K, 常压下研究了1-丁基-3-甲基咪唑六氟磷酸盐([bmim][PF₆])+水+甲醇、[bmim][PF₆]+水+乙醇、[bmim][PF₆]+水+2-丙醇、[bmim][PF₆]+水+1-丙醇三元体系的相行为. 结果表明, 对于含甲醇、乙醇和2-丙醇的体系, 醇在水+醇溶液中摩尔分数分别为0.55-1.00、0.40-0.75 和0.35-0.50 时, 醇的水溶液与[bmim][PF₆]可以互溶. 而水+1-丙醇体系没有此类现象. 这说明, 这类三元系的相行为不但取决于醇分子的大小, 而且取决于其结构.     

反气相色谱法测定有机溶剂在离子液体1-丁基-3-甲基咪唑六氟磷酸盐中的热力学参数

在343.15~373.15 K温度范围内,采用反气相色谱法(IGC)测试了18种有机溶剂在离子液体1-丁基-3-甲基咪唑六氟磷酸盐([BMIM]PF₆)中的热力学参数。在测试温度范围内计算了有机溶剂与[BMIM]PF₆之间的摩尔吸收焓、质量分数活度系数、Flory-Huggins相互作用参数、偏摩尔混合焓和无限稀释活度系数等热力学参数。结果表明,所选的有机溶剂中,正构烷烃、环己烷、四氢呋喃、乙醚和四氯化碳为[BMIM]PF₆的不良溶剂。 相比之下,苯、甲苯、间二甲苯、二氯甲烷、丙酮、氯仿、乙酸乙酯、乙酸甲酯、乙醇和甲醇是[BMIM]PF₆的良溶剂。     

离子液体1-丁基-3-三甲基硅咪唑六氟磷酸盐萃取细胞色素C

建立了疏水性离子液体1-丁基-3-三甲基硅咪唑六氟磷酸盐(BtmsimPF6)萃取细胞色素C(Cyt-c)的新方法.在萃取条件为pH 1.0,Cyt-c溶液体积3 mL,BtmsimPF6体积400 μL,萃取时间30 min时,5 mg/L Cyt-c的萃取效率为85%.萃取机理研究表明:在酸性条件下,Cyt-c发生构型转变,肽链伸展,使疏水性基团外露,增加了Cyt-c在疏水性离子液体中的溶解性;同时,当pH＜2.0时,血红素基团中的Fe与Met-80的配位断裂,空出第六个配位空间,离子液体咪唑阳离子进入到肽链孔穴与Fe发生配位,形成新的配位键,从而被萃取到离子液体中.     

甲醇对1-丁基-3-甲基咪唑四氟硼酸离子液体结构与性质影响的模拟研究

采用分子动力学模拟方法研究了298.15 K、0.1 MPa下摩尔分数为0.1-0.9 的甲醇对1-丁基-3-甲基咪唑四氟硼酸盐([BMIM][BF₄])结构与性质的影响. 获得了体系的密度、径向分布函数、配位数、自扩散系数、粘度和电导率, 模拟得到的密度值与实验值符合较好. 结果显示: 体系各组分之间的径向分布函数随甲醇摩尔分数的增加呈规律性变化; 体系内阴阳离子的自扩散系数随着甲醇摩尔分数的增加不断增大; 甲醇的加入削弱了阴阳离子之间的相互作用, 体系粘度随着甲醇摩尔分数的增加逐渐减小, 电导率不断增大. 分析空间分布函数得到体系中各组分的三维空间分布情况.     

负载1-丁基-3-甲基咪唑氯的固体炭磺酸催化水解纤维素

纤维素作为可再生资源,其催化水解得到的平台化合物对缓解能源压力具有重要的意义。 本文以生物质竹子为原料选择700 ℃预碳化、150 ℃磺化得到的固体炭磺酸为基体,负载1-丁基-3-甲基咪唑氯后得到离子液体功能化固体炭磺酸催化剂。 结果表明,催化剂最优条件下水解纤维素得到的总还原糖产率相对于固体炭磺酸提升了15.2%,循环使用后,依然表现出良好的催化性能。     

Study on the Morphology Feature of 1-Butyl-3-methylimidazolium Tetrafluoroborate Based Ionic Liquid Reverse Microemulsions

The micromorphology of 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF₄)-in-cyclohexane and bmimBF₄-in-triethylamine ionic liquid microemulsions was investigated by two-dimensional NMR and freeze-fracture transmission electron microscopy. The reverse micelles of Triton X-100/cyclohexane were destroyed by adding bmimBF₄ and reverse microemulsions were induced to form by successively adding bmimBF₄. However, no micelles appeared in triethylamine. But if adding bmimBF₄ to a certain extent, a reverse microemulsion was also formed. The driving force of such aggregations could be attributed to the presence of different types of interactions between Triton X-100 and bmimBF₄. A staggered arrangement of surfactant led to the irregular droplet structure and large aggregate size.     

Extraction Mechanism of Metal Ion from Aqueous Solution to the Hydrophobic Ionic Liquid, 1-Butyl-3-methylimidazolium Nonafluorobutanesulfonate

Summary. We studied the extraction behavior of metal ionic species in aqueous solutions into the hydrophobic ionic liquid, 1-butyl-3-methylimidazolium nonafluorobutanesulfonate ([bmi][NfO]). The extraction ratios (E/%) of Li(I), Na(I), Cs(I), Ca(II), Sr(II), and La(III) species were found to be 39, 24, 5.0, 81, 79, and 98. This result is similar to the phenomena that the metal ions with larger charge are more easily adsorbed onto cation exchange resins. In order to examine the extraction mechanism, we studied the extraction behavior of La(III) species from the aqueous to the [bmi][NfO] phase. As a result, it was found that the E values of La(III) decrease remarkably with an increase in concentrations of HNO₃ (0–1 M) in the aqueous phase and that the amount of La(III) transferred into [bmi][NfO] phase increases linearly with an increase in the amount of [bmi] transferred into the aqueous phase. Furthermore, we investigated the extraction behavior of La(III) species using 1-pentyl- and 1-hexyl-3-methylimidazolium nonafluorobutansulfonate ([pmi][NfO], [hmi][NfO]), which are more hydrophobic than [bmi][NfO], and found out that the E values of La(III) decrease in order of [bmi][NfO] > [pmi][NfO] > [hmi][NfO]. From these results, it was proposed that the extraction of metal ionic species from the aqueous to the [bmi][NfO], [pmi][NfO], or [hmi][NfO] phase is mainly ascribed to the cation exchanges between two phases.     

Extraction Mechanism of Metal Ion from Aqueous Solution to the Hydrophobic Ionic Liquid, 1-Butyl-3-methylimidazolium Nonafluorobutanesulfonate

We studied the extraction behavior of metal ionic species in aqueous solutions into the hydrophobic ionic liquid, 1-butyl-3-methylimidazolium nonafluorobutanesulfonate ([bmi][NfO]). The extraction ratios (E/%) of Li(I), Na(I), Cs(I), Ca(II), Sr(II), and La(III) species were found to be 39, 24, 5.0, 81, 79, and 98. This result is similar to the phenomena that the metal ions with larger charge are more easily adsorbed onto cation exchange resins. In order to examine the extraction mechanism, we studied the extraction behavior of La(III) species from the aqueous to the [bmi][NfO] phase. As a result, it was found that the E values of La(III) decrease remarkably with an increase in concentrations of HNO₃ (0–1 M) in the aqueous phase and that the amount of La(III) transferred into [bmi][NfO] phase increases linearly with an increase in the amount of [bmi] transferred into the aqueous phase. Furthermore, we investigated the extraction behavior of La(III) species using 1-pentyl- and 1-hexyl-3-methylimidazolium nonafluorobutansulfonate ([pmi][NfO], [hmi][NfO]), which are more hydrophobic than [bmi][NfO], and found out that the E values of La(III) decrease in order of [bmi][NfO] > [pmi][NfO] > [hmi][NfO]. From these results, it was proposed that the extraction of metal ionic species from the aqueous to the [bmi][NfO], [pmi][NfO], or [hmi][NfO] phase is mainly ascribed to the cation exchanges between two phases.     

Solvent Effect on the Enthalpy of Solution and Partial Molar Volume of the Ionic Liquid 1-Butyl-3-methylimidazolium Tetrafluoroborate

Enthalpies of solution and partial molar volumes of the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate were determined in 15 solvents of different polarity. Very large differences of the enthalpies of solution (????_sol H _IL=38.9?kJ?mol^?1) and partial molar volumes (??V _IL=43 cm³?mol^?1) are nearly the same as observed for lithium perchlorate solutions. These results clearly indicate that the low values of the macroscopic polarity parameters of [bmim]BF₄ do not correspond with the large differences of the intermolecular interactions in IL solutions. The values of the partial molar volume of the cation, $V_{[\mathrm{bmim}]^{+}}$ , were estimated for the first time. The changes of the partial molar volumes, V _IL, reflect mainly the changes of anion volume, $V_{\mathrm{BF}_{4}^{-}}$ . The rate of the Diels?CAlder reaction of 9,10-dimethylanthracene with maleic anhydride in the [bmim]BF₄ medium was nearly the same as in common molecular solvents.     

Formation of 1-Butyl-3-methylimidazolium Bis(2-ethyl-1-hexyl)sulfosuccinate Stabilized Water-in-1-Butyl-3-methylimidazolium Bis(trifluoromethanesulfonyl)imide Microemulsion and the Effects of Additives

A new strategy is proposed here to formulate a bis(2-ethyl-1-hexyl)sulfosuccinate (AOT^?) stabilized water-in-ionic liquid microemulsion without any additives. Replacing the inorganic counter ion Na⁺ by the organic 1-butyl-3-methylimidazolium ([Bmim]⁺) ion greatly improves the solubility of AOT^? in hydrophobic 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([Bmim]Tf₂N) (IL) and favors the formation of water-in-IL (W/IL) microdroplets. The existence of the W/IL microdroplets has been confirmed by dynamic light scattering, Fourier transform infrared absorption spectroscopy and ultraviolet–visible absorption spectroscopy. Also, presented for the first time are the effects of salts and alcohols on the microstructure and water solubilization capacity of the ternary H₂O/[Bmim]AOT/[Bmim]Tf₂N system. For inorganic salts, larger concentrations of the salt and higher charge density of the cation result in smaller microdroplet size and weak water solubilization capacity. For 1-hexanol, a high concentration of this alcohol results in small microdroplet size but high water solubilization capacity. Analyses indicate that the salts compress the electric double layers of W/IL microemulsions, decrease the size of the microdroplets and consequently reduce the water solubilization capacity; the alcohol, however, facilitates the aggregation of AOT^?, increases the number of W/IL microdroplets, and therefore improves the water solubilization capacity of the system.     

Synthesis of Cellulose Long-Chain Esters in 1-Butyl-3-methylimidazolium Acetate: Structure-Property Relations

In this study, we prepared cellulose long-chain esters homogeneously in 1-butyl-3-methylimidazolium acetate, using cotton linter as the raw material, long-chain fatty acid as the esterification agent and paratoluensulfonyl chloride as the co-reactant. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction were used to characterize the product. The maximum degree of substitution was found to be 1.53 when the molar ratio of cellulose, lauric acid and paratoluensulfonyl chloride was 1 : 6 : 6, provided that the reaction temperature was 60°C and the reaction time was 24 h. The mechanical property of the free-film made of cellulose laurate was also tested. It was found that the toughness of cellulose laurate was much better than that of cellulose acetate.     

Effect of Amino Acids on the Phase Behavior of Aqueous Biphasic Systems Composed of 1-Butyl-3-methylimidazolium Tetrafluoroborate and Sodium Citrate

Ionic liquids (ILs) based aqueous biphasic systems (ABSs) have been successfully applied to the extraction and purification of biomolecules. Although much research has focused on the effect of ILs on the phase formation, there are few reports that describe the phase behavior of quaternary IL-based ABS systems using amino acids (AAs) as additives. Here, 1-butyl-3-methylimidazolium tetrafluoroborate ([C₄mim]BF₄) formed an ABS with sodium citrate (Na₃C₆H₅O₇) with the aid of AAs. The phase behavior and physical properties of the ABS were investigated at 298 K. The capacity of the AA to create the ABS (area of biphasic region) increases with increasing in solubility and decrease with the molecular weight of the ILs and follows the trend glycine?>?l-alanine?≈?l-lysine?>?l-threonine?>?l-proline?≈?l-arginine?>?none. Moreover, the pH of the top and bottom phases containing l-proline as additive are nearly neutral; l-threonine, glycine, and l-alanine result in mildly acidic environments, while l-arginine and l-lysine provide basic pH conditions. The results show that the effects of the addition of the AAs can be considerable and important in the simulation, design calculation and pH control of ABS for efficient separation and extraction processes.     

Three-Component,One-Pot Synthesis of Benzo[b][1,4]oxazines in Ionic Liquid 1-Butyl-3-methylimidazolium Bromide

Benzo[b][1,4]oxazines have been synthesized in good to excellent yields in the presence of the ionic liquid 1-butyl-3-methylimidazolium bromide [bmim]Br under relatively mild conditions without any added catalyst, The method offers the advantages of good yields and short reaction times, and the ionic liquid can be easily separated from the product and reused.     

由四氟硼酸1-丁基-3-甲基咪唑鎓/十二烷基苯磺酸钠/水形成的双水相体系的热力学研究

在298.15 K下使用目测法和浊度法绘制了四氟硼酸1-丁基-3-甲基咪唑鎓([Bmim]BF4)/十二烷基苯磺酸钠(SDBS)/水组成的三元体系相图,得到了一个靠近离子液体和水一侧的狭窄双水相(ATPS)区域。从双水相区域周围选择不同组成的样品,用等温滴定微量热(ITC)方法测定了这些样品中逐滴加入纯水后体系热量的变化,发现随样品中水含量的增加,量热曲线上分别出现了较弱的吸热和放热过程,而且这两个过程的位置与三元相图中双水相的形成和消失的位置基本吻合,这说明ITC对于双水相体系的热力学研究是一种可行有效的方法。实验结果表明,双水相的形成是一个吸热过程(ΔH0),而消失是放热过程(ΔH0)。由于双水相的形成是等温等压下的热力学自发过程(ΔG0),因此可以判断该体系中双水相的形成是一个熵驱动过程,而消失是一个熵-焓共驱过程。     

Thermophysical and Spectroscopic Studies of Pure 1-Butyl-3-methylimidazolium Tetrafluoroborate and Its Aqueous Mixtures

Intermolecular interactions in the aqueous mixtures of the room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF₄]), have been studied. The thermophysical properties: density ρ, speed of sound u, specific conductivity κ and refractive index n _D have been measured over the whole composition range at different temperatures (293.15–323.15 K) and are discussed. The results from thermophysical measurements are explained with the help of spectroscopy. In order to interpret the nature of molecular interactions occurring between [BMIM][BF₄] and water molecules, as well as to identify the moieties in which interactions are taking place, ¹H, ¹³C NMR and FT-IR spectra of the solutions have been studied. Excess molar volume V ^E, excess molar isentropic compressibility $ K_{S}^{\text{E}} $ , partial molar excess volume $ V_{i}^{\text{E}} $ , partial molar excess isentropic compressibility $ K_{S,i}^{\text{E}} $ , deviation in specific conductivity ?κ, and deviation in refractive index ?R have also been determined and analyzed to have a better understanding of the interactions taking place between the different components. Additionally, the excess ultrasonic speed u ^E and excess isentropic compressibility $ k_{S}^{\text{E}} $ , in terms of volume fractions, have been calculated and analyzed. It has been observed that temperature has a significant effect on the thermophysical properties of the studied system. Spectroscopic measurements confirm the disruption of ion-pair interactions of [BMIM][BF₄] and hydrogen-bonded network of water in the aqueous mixture of [BMIM][BF₄].     

1-Butyl-3-methylimidazolium Hydrogen Sulfate [bmim]HSO4: An Efficient Reusable Acidic Ionic Liquid for the Formylation of Alcohols

1-Butyl-3-methylimidazolium hydrogen sulfate [bmim]HSO4 as an acidic ionic liquid was prepared and used as a catalyst for the formylation of alcohols with ethyl formate at room temperature with good to excellent yields. A good selectivity was observed for the formylation of primary alcohols in the presence of tertiary alcohols.