Aryl C-glycosylation using an ionic liquid containing a protic acid

Aryl C-glycosylation of several glycosyl donors, including unprotected sugars, with phenol and naphthol derivatives in an ionic liquid containing a protic acid proceeded effectively and stereoselectively to give the corresponding aryl C-glycosides in good to high yields. Because the ionic liquid was nonvolatile, the reaction could be carried out under reduced pressure; in addition, the ionic liquid could be reused without loss of effectiveness. These features contribute to the significant advantages of this novel aryl C-glycosylation reaction.     

Efficient synthesis of chlorohydrins: ionic liquid promoted ring-opening reaction of epoxides and TMSCl

The environmentally benign, highly efficient synthesis of chlorohydrins by cleavage of epoxides using TMSCl in ionic liquid, bmimPF₆, has been studied.     

甲基丁基咪唑四羰基钴离子液体的改进合成与表征

对新型甲基丁基咪唑四羰基钴离子液体的合成方法进行了有效的改进, 克服了文献方法中的某些不足, 并因而能够首次稳定地以更高的纯度获得该种离子液体.对其进行了全面的谱学表征证明了产物的结构和纯度.     

A mild ring opening fluorination of epoxide with ionic liquid 1-ethyl-3-methylimidazorium oligo hydrogenfluoride (EMIMF(HF)2.3)

Ring opening fluorination of epoxides with hydrogen fluoride in ionic liquid 1-ethyl-3-methylimidazorium oligo hydrogenfluoride EMIMF(HF)_2.3 was demonstrated. This ionic liquid released hydrogen fluoride graduately to make mild conditions without oligomerization of epoxides.     

Task specific ionic liquid as solvent,catalyst and reagent for regioselective ring opening of epoxides in water

Task specific ionic liquid as a novel and environmental eco-friendly green catalyst has been synthesized and used in the ring opening of epoxides under green conditions. This ionic liquids as solvent, catalyst and reagent afforded the corresponding thiocyanohydrins and azidohydrines with good regioselectivity and very short reaction times. The desired thiocyanohydrins and azidohydrines in 83–93% isolated yields.     

1-烷基-3-甲基咪唑溴化盐离子液体的晶体结构及性能

以不同链长溴代烷烃和N-甲基咪唑反应得到1-烷基-3-甲基咪唑溴化盐,用元素分析和核磁共振对化合物进行了表征.室温下用溶剂蒸发法得到了单晶,并用X射线单晶衍射法测定了晶体结构,该晶体属于三斜晶系,空间群为P-1.化合物采用双分子层结构,水分子参与结构的形成,整个化合物由交叉的线性烷基链、咪唑头基、溴离子和水分子组成,溴离子和水分子之间较强的氢键作用在(010)方向上形成了一个无限的O-H···Br氢键链.用偏光显微镜、差示扫描量热(DSC)技术研究了其液晶行为,证明其一水合物为近晶相热致液晶.液晶区域的温度范围较宽说明水分子起到稳定作用.     

Regio-selective synthesis of 1,2-aminoalcohols from epoxides and chlorohydrins

A simple and efficient procedure for the regio-selective synthesis of 1,2-aminoalcohols from terminal epoxides and chlorohydrins by using NaHMDS as the source of amine is reported. The wider scope and utility of this method is demonstrated.     

Synthesis,thermal and lyotropic liquid crystalline properties of protic ionic salts

A series of protic ionic salts were synthesised by a simple acid–base reaction from various pyridine derivatives and dodecylbenzenesulfonic acid in a common organic solvent and characterised in terms of their thermal and lyotropic liquid crystalline properties using various experimental techniques. All of them exhibited lyotropic liquid crystalline phases in toluene, methanol, acetonitrile, dimethyl sulfoxide and water. Their critical concentrations for the formation of biphasic solutions and concentrations for the formation of lyotropic solutions were quite broad depending on the dielectric constants of the solvents. Their lyotropic phases were identified as lamellar phases, since their textures exhibited bâtonnets, oily streaks and mosaic textures. They can potentially be used for many organic transformations, which may have implications in green chemistry.     

Anodic oxidation of silver in 1-butyl-3-methylimidazolium bromide ionic liquid

Electrochemical oxidation of silver in the 1-butyl-3-methylimidazolium bromide ([BMIm]Br) ionic liquid is studied by cyclic voltammetry, chronopotentiometry, chronoammetry, and gravimetry. Two electrode processes irreversibly proceed on the silver electrode in the potential range studied: the formation of compound [BMIm]⁺[AgBr₂]^?, which is soluble in [BMIm]Br, and difficultly soluble AgBr.     

Essential oil deterpenation by solvent extraction using 1-ethyl-3-methylimidazolium 2-(2-methoxyethoxy) ethylsulfate ionic liquid

Taking into account that heat application can have undesirable effects in essential oil properties, liquid extraction comes up as a promising process instead of distillation for citrus oil deterpenation. In this work the suitability of using the ionic liquid 1-ethyl-3-methylimidazolium 2-(2-methoxyethoxy) ethylsulfate as a solvent for the extraction of linalool from citrus essential oil (which has been simulated as a mixture of limonene and linalool) has been analyzed. Liquid–liquid equilibrium data at three different temperatures (298.15 K, 308.15 K and 318.15 K) have been reported and successfully correlated using NRTL model. The best results were achieved using α = 0.1 for the systems at 298.15 K and 308.15 K and α = 0.2 at 318.15 K. The solute distribution ratio has showed values close to one and high values of selectivity have been achieved.     

1-烷基-3-甲基咪唑l-乳酸盐的合成及其物理性质

离子液体;手性离子液体;烷基甲基咪唑l-乳酸盐     

Transport properties of protic ionic liquids,pure and in aqueous solutions: Effects of the anion and cation structure

Ionic conductivities of twelve protic ionic liquids (PILs) and their mixtures with water over the whole composition range are reported at 298.15 K and atmospheric pressure. The selected PILs are the pyrrolidinium-based PILs containing nitrate, acetate or formate anions; the formate-based PILs containing diisopropylethylammonium, amilaminium, quinolinium, lutidinium or collidinium cations; and the pyrrolidinium alkylcarboxylates, [Pyrr][C_nH_2n+1COO] with n = 5–8. This study was performed in order to investigate the influence of molecular structures of the ions on the ionic conductivities in aqueous solutions. The ionic conductivities of the aqueous solutions are 2–30 times higher than the conductivities of pure PILs. The maximum in conductivity varies from ww=0.41 ??to ??0.74$w_w=0.41\text{\hspace{0.17em}??}\text{to}\text{\hspace{0.17em}??}0.74$ and is related to the nature of cations and anions. The molar conductance and the molar conductance at infinite dilution for (PIL + water) solutions are then determined. Self-diffusion coefficients of the twelve protic ionic liquids in water at infinite dilution and at 298.15 K are calculated by using the Nernst–Haskell, the original and the modified Wilke–Chang equations. These calculations show that similar values are obtained using the modified Wilke–Chang and the Nernst–Haskell equations. Finally, the effective hydrodynamic (or Stokes) radius of the PILs was determined by using the Stokes–Einstein equation. A linear relationship was established in order to predict this radius as a function of the anion alkyl chain length in the case of the pyrrolidinium alkylcarboxylates PILs.     

Use of the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate in countercurrent chromatography

Room temperature ionic liquids (RTIL) are molten salts that are liquids at room temperature. Their liquid state makes them possible candidates as solvents in countercurrent chromatography (CCC), which uses solvents as both the mobile and stationary phases. The study focuses on 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM PF₆), an easy to synthesize and purify RTIL whose melting point is –8°C. It is shown that BMIM PF₆ behaves like a solvent of significant polarity (comparable with that of ethanol). The ternary phase diagram water–acetonitrile–BMIM PF₆ is given, because it was necessary to add acetonitrile to reduce the ionic liquid viscosity. The 40:20:40% w/w water–acetonitrile–BMIM PF₆ biphasic liquid system was found to be appropriate as a biphasic liquid system for CCC. Different aromatic solutes, including bases, acids, and neutral compounds, were injected into the CCC column to estimate their distribution constants between the ionic liquid-rich phase and the aqueous phase. The resulting K_il/w constants were compared with the corresponding literature octanol–water partition coefficients, K_o/w. The important drawbacks in the use of RTIL in CCC are clearly pointed out: high viscosity producing pressure build-up, UV absorbance limiting the use of the convenient UV detector, and non-volatility precluding the use of the evaporative light-scattering detector for continuous detection.     

Monitor adsorption of acetone vapor to a room temperature ionic liquid 1-octyl-3-methylimidazolium bromide by a langasite crystal resonator

In this work, the responses of a Y-cut langasite crystal resonator (LCR) in liquid phases were investigated by an impedance analysis method. The resonant frequency (f_S) of the LCR decreases with increasing mass loading on the active surface of the resonator. The LCR can be operated at the resonant frequency that is down to about 60% of the fundamental frequency (f₀) under foreign mass loading. The frequency-mass coefficient of the Y-cut LCR is theoretically derived to be −1.282 × 10⁻⁶, which is supported by the experimental results. The resonant frequency of the LCR decreases linearly while its motional resistance (R_m) increases linearly with increasing (ρη)^1/2, where η and ρ are the viscosity and density of the liquid phase, respectively. The slopes of the plots of f_S versus (ρη)^1/2 and R_m versus (ρη)^1/2 are related to the region of (ρη)^1/2 because of the influence of surface roughness of the LCR. The changes in viscodensity of a room temperature ionic liquid (RTIL), 1-octyl-3-methylimidazolium bromide ([C₈MIM][Br]), were investigated in acetone vapor adsorption and ascending temperature processes by the LCR. The adsorption of acetone into [C₈MIM][Br] causes a significantly drop in viscosity of the [C₈MIM][Br] film, which induces an increase in f_S and a decrease in R_m for the RTIL modified LCR. When the thickness of [C₈MIM][Br] film is less than the decay distance of the thickness-shear wave, a mass effect model is observed in the early adsorption process. Based on the responses of the LCR, the viscodensity of the [C₈MIM][Br] film as well as the adsorbed amounts of acetone into film were monitored in real time during the adsorption or desorption processes.     

Effects of alkyl chain length on properties of 1-alkyl-3-methylimidazolium fluorohydrogenate ionic liquid crystals

A series of 1‐alkyl‐3‐methylimidazolium fluorohydrogenate salts (C_xMIm(FH)₂F, x=8, 10, 12, 14, 16, and 18) have been characterized by thermal analysis, polarized optical microscopy, IR spectroscopy, X‐ray diffraction, and anisotropic ionic conductivity measurements. Liquid crystalline mesophases with a smectic A interdigitated bilayer structure are observed from C₁₀ to C₁₈, showing a fan‐like or focal conic texture. The temperature range of the mesophase increases with the increase in the alkyl chain length (from 10.1 °C for C₁₀MIm(FH)₂F to 123.1 °C for C₁₈MIm(FH)₂F). The distance between the two layers in the smectic structure gradually increases with increasing alkyl chain length and decreases with increasing temperature. Conductivity parallel to the smectic layers is around 10 mS cm^?1 regardless of the alkyl chain length, whereas that perpendicular to the smectic layers decreases with increasing alkyl chain length because of the thicker insulating sheet with the longer alkyl chain.     

Synthesis and preliminary use of novel acrylic ester-derived task-specific ionic liquids

Novel electrophilic alkenes bearing an ionic liquid-type appendage have been prepared and used in Diels-Alder cycloadditions, 1,4-additions, Heck couplings and Stetter reactions; this new type of support allows easy monitoring of the reactions by NMR and MS as well as simple and efficient work-up and isolation procedures.     

1-(1-Alkylsulfonic)-3-methylimidazolium chloride as a reusable Brønsted acid catalyst for the regioselective azidolysis of epoxides under solvent-free conditions

In this study, 1-(1-alkylsulfonic)-3-methylimidazolium chloride as a new, green, and reusable Brønsted acid catalyst was prepared. In this protocol, we used for the regioselective ring-opening reactions of various epoxiodes with sodium azide to afford the corresponding β-azido alcohols in excellent yields and short reaction time under mild and neutral reaction conditions. This method offers several advantages including excellent regioselectivity, clean reactions, simple work-up procedure, a recyclable catalyst, and use of an eco-friendly catalyst.     

Rapid and efficient ring opening of epoxides catalyzed by a new electron deficient tin(IV) porphyrin

The new electron deficient tin(IV) tetraphenylporphyrinato trifluoromethanesulfonate, [Sn^IV(tpp)(OTf)₂], was used as an efficient catalyst for the alcoholysis, hydrolysis and acetolysis of epoxides. Conversion of epoxides to thiiranes and acetonides were also performed efficiently in the presence of this catalyst.     

Buoyancy density measurements for 1-alkyl-3-methylimidazolium based ionic liquids with tetrafluoroborate anion

Density measurements are reported performed on three 1-alkyl-3-methylimidazolium-based ([C_n-mim], n=2,4,6$n=2\text{,}4\text{,}6$) ionic liquids with tetrafluoroborate anion at atmospheric pressure at 15 temperatures from 281 to 353 K. The buoyancy method was employed, using the microbalance of the Krüss K100MK2 tensiometer. At each temperature from 33 to 55 individual buoyancy readings were taken in most cases. The density average values at particular temperatures are presented with estimated total standard uncertainty less than ±0.4$\pm 0.4$ kg m⁻³ (3.3 ×10⁻⁴?$\times 10^{-4}?$). An empirical density–temperature equations have been developed describing the temperature dependence of each ionic liquid density. The 58 new experimental data points on the density–temperature relation of the three ionic liquids of interest are means calculated from about 3000 individual density readings, which have been altogether taken in the present study.