Orientation and Structure of Ionic Liquid Cation at Air/[bmim][BF4] Aqueous Solution Interface

The watermiscible room temperature ionic liquid 1butyl3methylimidazolium tetrafluorob orate （[bmim] [BF4]） is a model system for studying the interactions between ionic liquid and water molecules. In this work the orientational structure of the low concentrated aqueous solution of [bmim] [BF4] at the air/liquid interface was investigated by sum frequency gener ation vibrational spectroscopy. It has been found that at very low concentrations, the butyl chain exhibited a significant gauche defect, indicating a disordered conformation; and the cation ring oriented with a fairly small tilting angle at the surface. When the concentration increased, the cation ring tended to lie flat at the surface, and the gauche defects of the butyl chain decreased due to the intermolecular chainchain interactions and the consequent more ordered interfacial molecular arrangement. Additionally, the antisymmetric stretching mode in the PPP and SPS spectra exhibited a peak shift, showing that there exists more than one kind of orientation or chemical environment for the butyl CH3 group. These results may shed new light on understanding the surface behavior of watermiscible ionic liquids as well as the imidazolium based surfactants.     

CsF/[bmim][BF4]: An efficient and reusable system for Henry reaction

Cesium fluorides in ionic liquid [bmim][BF₄] have been used to promote the Henry reaction effectively. These reactions proceed smoothly and afford an excellent yield of the products.     

Iron-catalyzed bromination of aryl azides by N-bromosuccinimide:Efficient method for the synthesis of brominated aryl azides

An efficient and mild protocol for bromination of aryl azides with N-bromosuccinimide（NBS） under FeCl₃ catalysis in 1,2- dichloroethane was developed.It is proved to be an efficient method for obtaining brominated aryl azides.     

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.     

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.     

离子液体[bmim][PF6]与[moemim][PF6]结构微不均匀性以及微粘度的光谱探测

室温离子液体由于其极低的蒸汽压、比较好的热稳定性和化学稳定性、良好的分子结构与性能的可设计性等优点,作为一种新型的环境友好溶剂在很多领域有着广泛的应用.对于离子液体的微观结构和微观性能的研究是设计新型离子液体以及扩展离子液体应用的关键.本文通过荧光探针分子香豆素153(C153)的转动动力学和对微观环境敏感的荧光探针分子1, 3-二(1-芘基)丙烷(BPP)的稳态荧光光谱,探测和表征了烷基取代的离子液体1-丁基-3-甲基咪唑六氟磷酸盐([bmim][PF₆])和与其具有相似结构的醚键官能化的离子液体1-甲氧基乙基-3-甲基咪唑六氟磷酸盐([moemim][PF₆])的微观结构和微粘度. C153探针分子在离子液体[bmim][PF₆]中的转动过程具有快、慢两个组分表明离子液体[bmim][PF₆]内部存在松散和紧密的两种结构微区;而C153探针分子在离子液体[moemim][PF₆]中的转动动力学只存在一种过程,说明醚键的引入使得[moemim][PF₆]内部趋于一种类型的微环境.通过C153探针分子的转动时间研究发现,醚键官能化的离子液体[moemim][PF₆]的微粘度小于烷基链取代的离子液体[bmim][PF₆],同时通过BPP探针分子的二聚体激基复合物(excimer)与单体(monomer)荧光发射强度的比值(I_E/I_M)研究也证明这一结果.醚键的引入使得离子液体[moemim][PF₆]相对于离子液体[bmim][PF₆],侧链的极性更大、柔顺性更好,同时醚键有可能作为氢键的受体与阳离子形成氢键从而削弱离子液体中阴、阳离子间的相互作用,使得离子液体[moemim][PF₆]的微观环境比离子液体[bmim][PF₆]更为均一,同时具有更小的微粘度.     

室温离子液体[bmim][BF_4]和水混合物的计算机模拟研究

针对室温离子液体[bmim][BF4]和水的混合物,用分子动力学模拟研究了溶液的微观组成与浓度的关系.模拟结果表明:该混合物中各组分间的径向分布函数随[bmim][BF4]摩尔分数的增加呈有规律的变化;在此基础上计算了溶液的局部组成以及组分间的缔合因子,进一步考察了各组分间的相互作用情况;另外基于Kirkwood-Buff理论估算了混合物的偏摩尔体积、等温压缩因子以及活度系数对浓度的偏导数,对于理解离子液体与水之间的交互作用具有一定的参考意义.     

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。     

室温离子液体[bmim][BF4]和水混合物的计算机模拟研究

针对室温离子液体[bmim][BF₄]和水的混合物, 用分子动力学模拟研究了溶液的微观组成与浓度的关系. 模拟结果表明：该混合物中各组分间的径向分布函数随[bmim][BF₄]摩尔分数的增加呈有规律的变化；在此基础上计算了溶液的局部组成以及组分间的缔合因子, 进一步考察了各组分间的相互作用情况；另外基于Kirkwood-Buff理论估算了混合物的偏摩尔体积、等温压缩因子以及活度系数对浓度的偏导数, 对于理解离子液体与水之间的交互作用具有一定的参考意义.     

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.     

Ionic liquids and deep eutectic mixtures as new solvents for the synthesis of vanadium fluorides and oxyfluorides

An exploratory study of the synthesis of vanadium (oxy)fluorides (VOFs) using ionic liquids (ILs) and deep eutectic mixtures (DESs) as a solvent yielded 10 different materials. The previously reported chain type: (NH(4))(2)VF(5) (1), (NH(4))(2)VOF(4) (2), NH(4)VO(3) (3) and (H(2)NH(2)(CH(2))(2)NH(2))VF(5) (9) have been successfully produced for the first time using ILs as the reaction media. The monomeric (HNH(2)CH(3))(2)VOF(4)(H(2)O) (4), the dimer (HNH(2)CH(3))(4)V(2)O(2)F(8) (5) and the 1D chains (HNH(2)CH(3))(2)VF(5) (6), (H(2)O)(2)VF(3) (7), α-(H(2)NH(2)(CH(2))(2)NH(2))VOF(4) (8) and β-(H(2)NH(2)(CH(2))(2)NH(2))VOF(4) (10) are novel materials. Template control has also been achieved by the selective choice of ILs or the appropriate deep eutectic mixture, where the expected template is delivered to the reaction by the partial breakdown of the urea derivative portion of the DES.     

离子液体[bmim][BF4]对联苯甲酰光化学反应影响的瞬态吸收光谱

利用纳秒级激光光解瞬态吸收光谱研究了联苯甲酰(BZ)在离子液体1-丁基-3-甲基咪唑四氟硼酸盐([bmim][BF₄])与乙腈(MeCN)混合体系中的光化学反应行为. 考察了探针分子BZ存在下[bmim][BF₄]/MeCN比例对体系中化学反应动力学的影响. 实验发现: 在N₂饱和条件下, BZ溶液经激光辐照后产生的激发三线态³BZ^*遵循一级反应动力学规律衰减. 离子液体(IL)相对比例增加对³BZ^*瞬态吸收峰的位置和强度没有产生明显影响. 但离子液体体积分数V_IL的变化对[bmim][BF₄]/MeCN混合溶剂中光诱导电子转移的影响却非常显著, 总体上电子转移产生的自由基的表观生成速率常数k_gr随[bmim][BF₄]的V_IL增大而减小. 在[bmim]BF₄]比例足够大的情况下, ³BZ^*与三乙胺或四甲基对苯二胺之间的电子转移被抑制.     

[bmim]Cl/FeCl3离子液体催化苯与乙烯烷基化的反应机理

 利用FT-IR和1H NMR对KOH无水乙醇溶液滴定前后的氯化1-正丁基-3-甲基咪唑(［bmim］Cl)无水乙醇溶液进行分析发现,［bmim］Cl咪唑环上的2-H具有显著的质子酸性,滴定后的NMR谱中化学位移为9.5处的2-H信号完全消失,且在滴定过程中有KCl生成. 通过［bmim］Cl/FeCl3离子液体的1H NMR分析发现,咪唑环上的氢质子尤其是2-H的化学位移与FeCl3含量密切相关,随着FeCl3与［bmim］Cl摩尔比的增大, 2-H的化学位移向低场移动,说明其去屏蔽作用增强, 2-H更容易脱离. 将合成的［bmim］Cl/FeCl3离子液体脱水,并采用同位素置换的方法研究了离子液体催化全氘代苯与乙烯的烷基化反应机理. 结果表明,脱水后的离子液体仍然可以催化烷基化反应. 通过对反应后液体产物的GC-MS分析,提出了离子液体催化的苯与乙烯烷基化反应的正碳离子机理. 反应前后离子液体的1H NMR分析表明,反应后离子液体中咪唑环上的2-H的信号强度较反应前降低了23%,说明引发反应所需要的H+一部分是由咪唑环上的2-H提供的.     

Addition of aryl cuprates to azides: a novel approach for the synthesis of unsymmetrical diaryl amines

Aryl and benzyl azides react smoothly with aryl cuprates, generated in situ from aryl magnesium bromide and CuCN in THF to furnish a variety of unsymmetrical diaryl amines in good yields. This is the first report on the synthesis of diarylamines from aryl azides and aryl bromides via an organometallic approach.     

Ionic liquids as recycling solvents for the synthesis of magnetic nanoparticles

This work describes an easy synthesis (one pot) of MFe(2)O(4) (M = Co, Fe, Mn, and Ni) magnetic nanoparticles MNPs by the thermal decomposition of Fe(Acac)(3)/M(Acac)(2) by using BMI·NTf(2) (1-n-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) or BMI·PF(6) (1-n-butyl-3-methylimidazolium hexafluorophosphate) ionic liquids (ILs) as recycling solvents and oleylamine as the reducing and surface modifier agent. The effects of reaction temperature and reaction time on the features of the magnetic nanomaterials (size and magnetic properties) were investigated. The growth of the MNPs is easily controlled in the IL by adjusting the reaction temperature and time, as inferred from Fe(3)O(4) MNPs obtained at 150 °C, 200 °C and 250 °C with mean diameters of 8, 10 and 15 nm, respectively. However, the thermal decomposition of Fe(Acac)(3) performed in a conventional high boiling point solvent (diphenyl ether, bp 259 °C), under a similar Fe to oleylamine molar ratio used in the IL synthesis, does not follow the same growth mechanism and rendered only smaller NPs of 5 nm mean diameter. All MNPs are covered by at least one monolayer of oleylamine making them readily dispersible in non-polar solvents. Besides the influence on the nanoparticles growth, which is important for the preparation of highly crystalline MNPs, the IL was easily recycled and has been used in at least 20 successive syntheses.     

One-Pot Synthesis of N2-Substituted 2-Amino-4-aryl-5,6,7,8-tetrahydroquinoline-3-carbonitrile in Basic Ionic Liquid [bmim]OH

N2-Methyl- or aryl-substituted 2-amino-4-aryl-5,6,7,8-tetrahydroquinoline-3-carbonitriles were synthesized via a four-component, one-pot reaction of aromatic aldehyde, cyclohexanone, malononitrile, and amines in basic ionic liquid [bmim]OH with good to excellent yields. During this transformation, at least 11 bonds were cleaved and 7 new bonds were constructed.      

Association of ionic liquids in solution: a combined dielectric and conductivity study of [bmim][Cl] in water and in acetonitrile

Ion association of the ionic liquid [bmim][Cl] in acetonitrile and in water was studied by dielectric spectroscopy for salt concentrations c ≤ 1.3 M at 298.15 K and by measurement of molar electrical conductivities, Λ, of dilute solutions (c ≤ 0.006 M) in the temperature range 273.15 ? T/K ≤ 313.15. Whilst acetonitrile solutions of [bmim][Cl] exhibit moderate ion pairing, with an association constant of K°(A) ≈ 60 M(-1) and increasing with temperature, [bmim][Cl] is only weakly associated in water (K°(A) ≈ 6 M(-1)) and ion pairing decreases with rising temperature. Only contact ion pairs were detected in both solvents. Standard-state enthalpy, entropy and heat capacity changes of ion association were derived, as well as the activation enthalpy of charge transport and the limiting conductivity of the cation, λ(∞)?([bmim](+)). These data, in conjunction with effective solvation numbers obtained from the dielectric spectra, suggest that the solvation of [bmim](+) is much weaker in water than in acetonitrile.     

ZrCl4/[bmim]BF4‐catalyzed condensation of salicylaldehydes and malononitrile: Single‐step synthesis of 3‐cyanocoumarin derivatives

A versatile and efficient single‐step route to 3‐cyanocoumarins via Knoevenagel condensation of salicylaldehydes and malononitrile using ZrCl₄ as the catalyst (15 mol %) in ionic liquid 1‐(n‐butyl)‐3‐methylimidazolium tetrafluoroborate as reaction medium and catalyst is described. The novel procedure features single step, short reaction time, good yields, and simple workup. J. Heterocyclic Chem., (2011).     

Uranyl complexation by chloride ions. Formation of a tetrachlorouranium(VI) complex in room temperature ionic liquids [Bmim][Tf2N] and [MeBu3N][Tf2N

The tetrachlorouranium(VI) complex is formed in [Bmim][Tf2N] and [MeBu3N][Tf2N] from a uranium(VI) solution in the presence of a stoichiometric quantity of chloride ions. The [UVIO2Cl4]2- absorption and emission spectra show bands splitting in comparison with the [UVIO2]2+ spectra, as observed in the solid state, organic solvents, and chloroaluminate-based ionic liquids. The fluorescence lifetime of [UO2Cl4]2- in [MeBu3N][Tf2N] is 0.7 +/- 0.1 mus. The reduction potential of this complex is -1.44 and -1.8 V vs Ag/Ag+ respectively in [Bmim][Tf2N] and [MeBu3N][Tf2N] and does not depend on the chloride concentration. The mechanism proposed for the redox process is a monoelectronic reduction to form [UVO2Cl4]3-, followed by a chemical reaction. The tetrachlorouranium(V) complex seems more stable in [Bmim][Tf2N] than in [MeBu3N][Tf2N]. The electrochemical analysis put in evidence specific interactions of the ionic liquid cation with the uranium anionic species.