Atom transfer radical polymerization using activators regenerated by electron transfer of acrylonitrile in 1‐(1‐ethoxycarbonylethyl)‐3‐methylimidazolium hexafluorophospate

Atom transfer radical polymerization using activators regenerated by electron transfer (ARGET ATRP) of acrylonitrile (AN) was first approached with 1‐(1‐ethoxycarbonylethyl)‐3‐methylimidazolium tetrafluoroborate ([ecemim][BF₄]) as reaction medium and tin(II) bis(2‐ethylhexanoate) (Sn(EH)₂) as reducing agent in the presence of air. When compared with in bulk, an obvious increase of polymer isotacticity was observed for ARGET ATRP of AN in 1‐(1‐ethoxycarbonylethyl)‐3‐methylimidazolium hexafluorophospate ([ecemim][PF₆]), the reaction rate of ARGET ATRP of AN in [ecemim][PF₆] was higher and the polymerization process was better controlled. The block copolymer polyacrylonitrile‐block‐poly(methyl methacrylate) with molecular weight at 69,750, distribution at 1.34, and isotacticity at 0.36 was successfully obtained in [ecemim][PF₆]. [Ecemim][PF₆] and the catalyst system were recycled and reused and had no effect on the living nature of polymerization. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Bimodal molecular weight distribution of poly(styrene‐co‐acrylonitrile) formed by conventional free‐radical copolymerization of acrylonitrile and styrene in room temperature ionic liquids

Conventional free‐radical copolymerization of acrylonitrile (AN) and styrene (St) was realized in room temperature ionic liquids (RTILs), 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([Bmim][BF₄]) and 1‐butyl‐3‐methylimidazolium hexafluorophosphate ([Bmim][PF₆]), under mild conditions. The copolymerization in RTILs was more rapid than that in traditional solvent DMF. Poly(styrene‐co‐acrylonitrile) (SAN) prepared in RTILs had higher molecular weight than that prepared in DMF or by bulk copolymerization. SAN with bimodal molecular weight distribution (MWD) were obtained in most of the reaction conditions in [Bmim][BF₄] and some conditions in [Bmim][PF₆]. By the analysis of reaction phenomena and fluorescence behavior, the reason of the difference in MWD could be attributed to the difference of reaction system compatibility mainly caused by the immiscibility of macromolecule with RTIL. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4420–4427, 2006     

Green Synthesis of Pyrano[2,3‐d]‐pyrimidine Derivatives in Ionic Liquids

Pyrano[2,3‐d]pyrimidine derivatives were synthesized in high yields by a condensation reaction between arylmethylidenemalononitrile and barbituric acid using room‐temperature ionic liquids such as 1‐n‐butyl‐3‐methylimidazolium tetrafluoroborate ([BMIm]BF₄) or 1‐butylpyridinium tetrafluoroborate ([BPy]BF₄) as solvents under neutral conditions.     

The performance of 1‐ethyl‐3‐methylimidazolium tetrafluoroborate ionic liquid as mobile phase additive in HPLC‐based lipophilicity assessment

Ionic liquids have been widely used as green alternative mobile phase additives to shield the residuals silanols groups and modify the stationary/mobile phase HPLC systems. The present study aimed to evaluate the performance of the ionic liquid 1‐ethyl‐3‐methylimidazolium tetrafluoroborate ([EMIM][BF4]) in producing extrapolated logk_w indices suitable to substitute for octanol–water logP or logD values. The effect of [EMIM][BF4] was investigated for a set of basic and neutral drugs using two different columns, BDS and ABZ⁺. [EMIM][BF4] was added simply alone or in combination with n‐octanol and was compared with the conventional masking agent n‐decylamine. [EMIM][BF4] reduced the retention by suppressing silanophilic interactions, althoug to a lower extent than n‐decylamine. Addition of n‐octanol further decreased the retention by shielding silanol sites on BDS and/or interacting with polar groups through hydrogen bonding on ABZ⁺. Logk_w/logD_7.4 relationships proved moderate compared with those derived upon addition of n‐decylamine. They were considerably improved upon the introduction of protonated fraction F⁺ in the correlation, reflecting ion pair formation between the chaotropic anion [BF4]^‐ and the protonated basic compounds. In this aspect, the ionic liquid [EMIM][BF4], although efficient as a masking agent, cannot be recommended as mobile phase additive to reproduce octanol–water partitioning. Copyright © 2010 John Wiley & Sons, Ltd.     

The physicochemical properties of some imidazolium-based ionic liquids and their binary mixtures

The density, viscosity and conductivity of ionic liquids (ILs), 1-octyl-3-methylimidazolium tetrafluoroborate ([omim][BF4]), 1-octyl-3-methylimidazolium chloride ([omim][Cl]), 1-hexyl-3-methylimidazolium tetrafluoroborate ([hmim] BF4]), 1-hexyl- 3-methylimidazolium chloride ([hmim][Cl]), 1-hexyl-3-methylimidazolium hexafluorophosphate ([hmim][PF6]), and the [omim][BF4] + [omim][Cl], [hmim][BF4] + [hmim][Cl], and [hmim][PF6] + [hmim][Cl] binary mixtures were studied at dif- ferent temperatures. It was demonstrated that the densities of both the neat ILs and their mixtures varied linearly with temper- ature. The density sensitivity of a binary mixture is between those of the two components. The excess molar volumes (VE) of [hmim][BF4] + [hmim][Cl] and [hmim][PF6] + [hmim][Cl] mixtures are positive in the whole composition range. For [omim][BF4] + [omim][Cl], the VE is also positive in the [omim][Cl]-rich region, but is negative in the [omim][BF4]-rich re- gion. The viscosity or conductivity of a mixture is in the intermediate of those of the two neat ILs. For all the neat ILs and the binary mixtures studied, the order of conductivity is opposite to that of the viscosity. The Vogel-Tammann-Fulcher (VTF) equations can be used to fit the viscosity and conductivity of all the neat ILs and the binary mixtures. The neat ILs and their mixtures obey the Fractional Walden Rule very well, and the values of the Walden slopes are all smaller than unit, indicating obvious ion associations in the neat ILs and the binary mixtures.     

Synthesis and application of a chiral ionic liquid functionalized β‐cyclodextrin as a chiral selector in capillary electrophoresis

A novel chiral ionic liquid functionalized β‐cyclodextrin, 6‐O‐2‐hydroxpropyltrimethylammonium‐β‐cyclodextrin tetrafluoroborate ([HPTMA‐β‐CD][BF₄]), was synthesized and used as a chiral selector in capillary electrophoresis. [HPTMA‐β‐CD][BF₄] not only increased the solubility in aqueous buffer in comparison with the parent compound, but also provided a stable reversal electroosmotic flow, and the enantioseparation of eight chiral drugs was examined in phosphate buffer containing [HPTMA‐β‐CD][BF₄] as the chiral selector. The effects of the [HPTMA‐β‐CD][BF₄] concentration and the background electrolyte pH were studied. Moreover, the chiral separation abilities of β‐CD and [HPTMA‐β‐CD][BF₄] were compared and possible mechanisms for the chiral recognition of [HPTMA‐β‐CD][BF₄] are discussed. Copyright © 2013 John Wiley & Sons, Ltd.     

Supramolecular Ionic‐Liquid Gels with High Ionic Conductivity

Supramolecular ionogels were prepared by the gelation of room‐temperature ionic liquid 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([BMIm][BF₄]) with (S,S)‐bis(leucinol)oxalamide. Remarkably, the ionic conductivity of solutions and ionogels with low gelator concentrations is higher than that of neat [BMIm][BF₄]. On the basis of molecular dynamics simulations and quantum mechanical calculations, the origin of this phenomenon is attributed to the higher affinity of gelator molecules towards [BF₄]^? ions, which reduces the electrostatic attraction between [BMIm]⁺ and [BF₄]^? and thus increases their mobility. With increasing gelator concentration, the ionic conductivity decreases due to the formation of a denser gelator matrix, which hinders the pathways for ionic transport. However, even for very dense ionogels, this decrease is less than one order of magnitude relative to neat [BMIm][BF₄], and thus they can be classified as highly conductive materials with strong potential for application as functional electrolytes.     

离子液体型表面活性剂研究

以1-甲基咪唑为原料, 制备了6个常规离子液体: 1-正丁基-3-甲基咪唑四氟硼酸盐及六氟磷酸盐(简称[bmim][BF₄]及[bmim][PF₆])、1-正己基-3-甲基咪唑四氟硼酸盐及六氟磷酸盐(简称[hmim][BF₄]及[hmim][PF₆])、1-正十六烷基-3-甲基咪唑四氟硼酸盐及六氟磷酸盐(简称[C₁₆mim][BF₄]及[C₁₆mim][PF₆])和4个功能化离子液体: 1-(2-羟乙基)-3-甲基咪唑四氟硼酸盐及六氟磷酸盐(简称[2-hemim][BF₄]及[2-hemim][PF₆])、1-乙氧羰基甲基-3-甲基咪唑四氟硼酸盐及六氟磷酸盐(简称[eocmmim][BF₄]及[eocmmim][PF₆]). 研究了这两类离子液体的一些物理性能, 旨在挖掘离子液体在香料香精化妆品工业中的应用价值. 分别检测了它们与一般溶剂的互溶性, 并测定了它们的表面张力和发泡性能, 实验结果表明, 仅[C₁₆mim][BF₄]和[C₁₆mim][PF₆]具有发泡性能, 发泡力分别为68和120 mm.     

The Effect of C4H and C5H on the Microstructure of Aqueous Solutions of 1‐Alkyl‐3‐methylimidazolium Tetrafluoroborate Ionic Liquids

As is well‐known, the C2?H proton of 1‐ethyl‐3‐methylimidazolium tetrafluoroborate ([Emim]BF₄) and 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([Bmim]BF₄) has a strong ability to form hydrogen bonds. The purpose of this work is to evaluate the effect of the interactions of the C4?H and C5?H protons on the microstructure of [Emim]BF₄ and [Bmim]BF₄ with water by using ¹H NMR spectroscopy. The differences between the relative ¹H NMR chemical shifts of C2?H, C4?H, and C5?H and between the interaction‐energy parameters obtained from these chemical shifts are minor, thus suggesting that the interactions of C4?H and C5?H may have a considerable effect on the microstructure. To confirm this, the viscosities of the systems are estimated by using the interaction‐energy parameters obtained from the ¹H NMR chemical shifts of the three studied aromatic protons and water, showing that the interactions of C4?H and C5?H also play an important role in the microstructure.     

Measurement and Correlation of the Ionic Conductivity of Ionic Liauid-Molecular Solvent Solutions

The ionic conductivity of the solutions formed from 1-n-butyl-3-methylimidazolium tetrafluoroborate （[Bmim][BF4]） or 1-n-butyl-3-methylimidazolium hexafluorophosphate （[Bmim][PF6]） and different molecular solvents （MSs） were measured at 298.15 K. The molar conductivity of the ionic liquids （ILs） increased dramatically with increasing concentration of the MSs. It was found that the molar conductivity of the IL in the solutions studied in this work could be well correlated by the molar conductivity of the neat ILs and the dielectric constant and molar volume of the MSs.     

Aerobic and Electrochemical Oxidative Cross‐Dehydrogenative‐Coupling (CDC) Reaction in an Imidazolium‐Based Ionic Liquid

The ionic liquid 1‐butyl‐3‐methylimidazolium tetrafluoroborate [BMIm][BF₄] has demonstrated high efficiency when applied as a solvent in the oxidative nitro‐Mannich carbon? carbon bond formation. The copper‐catalyzed cross‐dehydrogenative coupling (CDC) between N‐phenyltetrahydroisoquinoline and nitromethane in [BMIm][BF₄] occurred with high yield under the described reaction conditions. Both the ionic liquid and copper catalyst were recycled nine times with almost no lost of activity. The electrochemical behavior of the tertiary amine substrate and β‐nitroamine product was investigated employing [BMIm][BF₄] as electrolyte solvent. The potentiostatic electrolysis in ionic liquid afforded the desired product with a high yield. This result and the cyclic voltammetric investigation provide a better understanding of the reaction mechanism, which involves radical and iminium cation intermediates.     

SET‐LRP of acrylonitrile in ionic liquids without any ligand

Use of ionic liquids as reaction media was investigated in the design of an environmentally friendly single electron transfer‐living radical polymerization (SET‐LRP) for acrylonitrile (AN) without any ligand by using Fe(0) wire as catalyst and 2‐bromopropionitrile as initiator. 1‐Methylimidazolium acetate ([mim][AT]), 1‐methylimidazolium propionate ([mim][PT]), and 1‐methylimidazolium valerate ([mim][VT]) were applied in this study. First‐order kinetics of polymerization with respect to the monomer concentration, linear increase of the molecular weight, and narrow polydispersity with monomer conversion showed the controlled/living radical polymerization characters. The sequence of the apparent polymerization rate constant of SET‐LRP of AN was k_app ([mim][AT]) > k_app ([mim][PT]) > k_app ([mim][VT]). The living feature of the polymerization was also confirmed by chain extensions of polyacrylonitrile with methyl methacrylate. All three ionic liquids were recycled and reused and had no obvious effect on the controlled/living nature of SET‐LRP of AN. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Reverse ATRP process of acrylonitrile in the presence of ionic liquids

An ionic liquid, 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([C₄mim] [BF₄]), was first used as the solvent in azobisisobutyronitrile (AIBN)‐initiated reverse atom transfer radical polymerization (RATRP) of acrylonitrile with FeCl₃/succinic acid (SA) as the catalyst system. The polymerization in [C₄mim][BF₄] proceeded in a well‐controlled manner as evidenced by kinetic studies. Compared with the polymerization in bulk, the polymerization in [C₄mim][BF₄] not only showed the best control of molecular weight and its distribution but also provided rather rapid reaction rate with the ratio of [C₄mim][BF₄] at 200:1:2:4. The polymerization apparent activation energies in [C₄mim][BF₄] and bulk were calculated to be 48.2 and 55.7 kJ mol^?1, respectively. Polyacrylonitrile obtained was successfully used as a macroinitiator to proceed the chain extension polymerization in [C₄mim][BF₄] via a conventional ATRP process. [C₄mim][BF₄] and the catalyst system could be easily recycled and reused after simple purification and had no effect on the living nature of polymerization. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2701–2707, 2008     

Synthesis of Unsymmetrical Ureas and S‐Thiocarbamates under Catalyst‐free Conditions in a [BMIM]BF4 Ionic Liquid

Unsymmetrical ureas and S‐thiocarbamates were prepared in good to excellent yields by direct condensation of phenylurea with amines and thiols in 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([BMIM]BF₄) without the addition of any additives. The [BMIM]BF₄ ionic liquid is a mild medium and can be recycled and reused several times.     

An Efficient and Green One‐pot Synthesis of 12‐Aryl‐8,9,10,12‐tetrahydrobenzo[a]xanthen‐11‐one Derivatives Promoted by Sulfamic Acid in [BMIM]BF4 Ionic Liquid

An efficient and green procedure for the synthesis of novel 12‐aryl‐8,9,10,12‐tetrahydrobenzo[a]xanthen‐11‐one derivatives has been described through one‐pot condensation of 2‐naphthol, arylaldehyde and 5,5‐dimethyl‐cyclohexane‐1,3‐dione in the presence of sulfamic acid (NH₂SO₃H) in ionic liquid 1‐n‐butyl‐3‐methylimidazolium tetrafluoroborate ([BMIM]BF₄). These reactions proceed with good yields under short reaction time. Furthermore, the green catalytic system can be recycled specific times with no decreases in yields and reaction rates.     

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.     

Direct electrochemistry and electrocatalysis of myoglobin immobilized in hyaluronic acid and room temperature ionic liquids composite film

A novel biocomposite film based on hyaluronic acid (HA) and hydrophilic room temperature ionic liquid 1-ethyl-3-methyl-imidazolium tetrafluoroborate ([EMIM][BF₄]) was explored. Here, HA was used as a binder to form [EMIM][BF₄]-HA composite film and help [EMIM][BF₄] to attaching on glass carbon electrode (GCE) surface, while doping [EMIM][BF₄] in HA can effectively reduce the electron transfer resistance of HA. The composite film can be readily used as an immobilization matrix to entrap myoglobin (Mb). A pair of well-defined and quasi-reversible redox peaks of Mb was obtained at the Mb-[EMIM][BF₄]-HA composite film modified GCE (Mb-[EMIM][BF₄]-HA/GCE) through direct electron transfer between Mb and the underlying electrode. The Mb-[EMIM][BF₄]-HA/GCE showed an excellent electrocatalytic activity toward the reduction of H₂O₂. Based on the [EMIM][BF₄]-HA biocomposite film, a third-generation reagentless biosensor could be constructed for the determination of H₂O₂.     

Effects of additives and post‐treatment on the thermoelectric performance of vapor‐phase polymerized PEDOT films

Vapor‐phase polymerization (VPP) is an important method for the fabrication of high‐quality conducting polymers, especially poly(3,4‐ethylenedioxythiophene) (PEDOT). In this work, the effects of additives and post‐treatment solvents on the thermoelectric (TE) performance of VPP‐PEDOT films were systematically investigated. The use of 1‐butyl‐3‐menthylinidazolium tetrafluoroborate ([BMIm][BF₄], an ionic liquid) was shown to significantly enhance the electrical conductivity of VPP‐PEDOT films compared with other additives. The VPP‐PEDOT film post‐treated with mixed ethylene glycol (EG)/[BMIm][BF₄] solvent displayed the high power factor of 45.3 μW m^?1 K^?2 which is 122% higher than that prepared without any additive or post‐treatment solvent, along with enhanced electrical conductivity and Seebeck coefficient. This work highlighted the superior effect of the [BMIm][BF₄] additive and the EG/[BMIm][BF₄] solvent post‐treatment on the TE performance of the VPP‐PEDOT film. These results should help with developing the VPP method to fabricate high‐performance PEDOT films. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55 , 1738–1744     

Solubility of CO2 in imidazolium-based tetrafluoroborate ionic liquids

The solubility of CO₂ in imidazolium ionic liquids (ILs), 1-butyl-3-methyl imidazolium tetrafluoroborate ([bmim][BF₄]), 1-hexyl-3-methyl imidazolium tetrafluoroborate ([hmim][BF₄]) and 1-octyl-3-methyl imidazolium tetrtafluoroborate ([omim][BF₄]) was determined at 305-25 K and pressures from 1 to 9 MPa. The influence of chain length of alkyl substituents on the imidazolium cation on the solubility of CO₂ was investigated. The differences in solubility with chain length are in the sequence [omim][BF₄] > [hmim][BF₄] > [bmim][BF₄]. The solubility data were correlated by the extended Henry's law, and enthalpy, Gibbs free energy and entropy changes were obtained.     

Isolation and purification of alkaloids from the fruits of Macleaya cordata by ionic‐liquid‐modified high‐speed counter‐current chromatography

Macleaya cordata (Willd) R. Br. is a medicinal plant. The most important bioactive compounds of M. cordata are alkaloids that have many biological activities including antifungal, anti‐inflammatory, and antitumor. In this study, an ionic‐liquid‐modified high‐speed counter‐current chromatography method was established to obtain alkaloids from the fruits of M. cordata. The conditions of ionic‐liquid‐modified high‐speed counter‐current chromatography, including solvent systems, the content of ionic liquid (1‐butyl‐3‐methylimidazolium tetrafluoroborate [C₄mim][BF₄]), and the posttreatment of the ionic liquid, were investigated. Five alkaloids protopine, allocryptopine, sanguinarine, 8‐O‐demethylchelerythrine, and chelerythrine were separated from the extract of the fruits using a high speed counter‐current chromatography with two‐phase solvent system composed of dichloromethane/methanol/0.3 mol/L hydrochloric acid aqueous solution/[C₄mim][BF₄] (4:2:2:0.015, v/v). Their purities were 96.33, 95.56, 97.94, 96.22, and 97.90%, respectively. The results indicated that a small amount of ionic liquids as modifier of the two‐phase solvent system could shorten the separation time and improve the separation efficiency of the alkaloids from the fruits. The ionic‐liquid‐modified high‐speed counter‐current chromatography would provide a feasible way for highly effective separation of alkaloids from natural products.