Solubility of erythromycin in ionic liquids

(Solid + liquid) and (liquid + liquid) phase equilibria of binary mixtures containing various ionic liquid and erythromycin were studied. The solubility of erythromycin in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, or 1-decyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, or trihexiltertadecilphosphonium chloride, or butyltrimethylammonium bis(trifluoromethylsulfonyl)imide, or methyltrioctylammonium bis(trifluoromethylsulfonyl)imide, or 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide has been measured by a dynamic method, in a wide range of temperatures from (284 to 358) K, at atmospheric pressure. The activity coefficients of erythromycin in ionic liquids were calculated and their comparison with ideal solution was discussed. The experimental data were correlated successfully by means of the semi-empirical Grant equation.     

Triaminocyclopropenium salts as ionic liquids

Salts of the charge-delocalised cations of the triaminocyclopropenium (tac) family bearing alkyl substituents have been prepared and shown to be air- and water-stable ionic liquids.     

Energetic nitrogen-rich salts and ionic liquids

Energetic salts offer many advantages over conventional energetic molecular compounds. The use of nitrogen containing anions and cations contributes to high heats of formations and high densities. Their low carbon and hydrogen content gives rise to a good oxygen balance. The decomposition of these compounds is predominantly through the generation of dinitrogen which makes them very promising candidates for highly energetic materials for industrial or military applications.     

Solubility and aggregation of charged surfactants in ionic liquids

Room-temperature ionic liquids (ILs) exhibit a unique set of properties, leading to opportunities for numerous applications. To obtain a better understanding of IL interfaces at a molecular level, we combined charged surfactants with ILs and studied their interfacial behavior. The critical micelle concentration (cmc) of each surfactant-IL pair was determined from both solubility phase diagrams and isotherms. Because the cmc is equivalent to the solubility at the Krafft temperature, a connection between the solubility of the surfactant and the physical properties of the underlying ionic liquid was established. Interfacial energy was found to be the major factor affecting the surfactant aggregation process, although its magnitude depends strongly on the IL structure. The results here give insight into explaining the nature of self-assembly of surfactants at IL interfaces and the interaction between solutes and IL solvents.     

Triggering phase disengagement of 1-alkyl-3-methylimidazolium chloride ionic liquids by using inorganic and organic salts

This study deals with the influence of different inorganic and organic salts made up with sodium, potassium and ammonium cations to induce phase segregation in aqueous solutions of C₈C₁imCl and C₁₀C₁imCl at T = 298.15 K. The experimental solubility values are described by means of four empirical equations and the suitability of the models was analysed in the light of the standard deviation. The capability of the above mentioned salts to further phase de-mixing is discussed on the basis of their different molar Gibbs free energy of hydration (Δ_hydG), molar entropy of hydration (Δ_hydS) and pH. The efficiency of the separation was evaluated by determining the tie-lines, and these experimental values were fitted to three known models such as Bancroft, Othmer–Tobias and modified Setschenow equations.     

New chiral ionic liquids based on imidazolinium salts

The preparation and application of a new series of chiral ionic liquids are described. The salts are based on imidazolinium cations. Some of the cations also incorporated an axial chirality at the C(2) position next to the central chirality. These cations display a very high rotational barrier along the arene–imidazolinium axis. Furthermore, an analogue with a chiral anion was prepared. The salts have low melting points. Their potential as solvents and as chiral shift reagents was explored, resulting for the first time in an example of a chiral ionic liquid as a shift reagent for a neutral compound.     

Functionalization of glassy carbon with diazonium salts in ionic liquids

The paper reports on the chemical functionalization of glassy carbon electrodes with 4-bromobenzene (4-BBDT) and 4-(4'-nitrophenylazo)benzene diazonium tetrafluoroborate (4-NAB) salts in ionic liquids. The reaction was carried out at room temperature in air without any external electrical bias in either hydrophobic (1-butyl-3-methylimidazolium hexafluorophosphate) or hydrophilic (1-butyl-3-methylimidazolium methyl sulfate) ionic liquids. The resulting surfaces were characterized using X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and electrochemical measurements. Electrochemical reduction of the terminal nitro groups allowed the determination of surface coverage and formation of an amine-terminated carbon surfaces. The results were compared to glassy carbon chemically modified in an aqueous solution in the presence of 1% sodium dodecyl sulfate (SDS) with the same diazonium salt. Furthermore, Raman spectroscopy coupled with electrochemical measurements allowed to distinguish between the reduction of -NO2 to -NH2 group and the -N=N- to -NH-NH- bond.     

Thermophysical properties of pure and water-saturated tetradecyltrihexylphosphonium-based ionic liquids

In this work, the solubility of water in several tetradecyltrihexylphosphonium-based ionic liquids at 298.15 K, and densities and viscosities of both pure and water-saturated ionic liquids in a broad temperature range were measured. The selected ionic liquids comprise the common tetradecyltrihexylphosphonium cation combined with the following anions: bromide, chloride, bis(trifluoromethylsulfonyl)imide, decanoate, methanesulfonate, dicyanamide and bis(2,4,4-trimethylpentyl)phosphinate. The isobaric thermal expansion coefficients for pure and water-saturated ionic liquids were determined based on the density dependence with temperature. Taking into account that the excess molar volumes of the current hydrophobic water-saturated ionic liquids are negligible, the solubility of water was additionally estimated from the gathered density data and compared with the experimental solubilities obtained. Moreover, the experimental densities were compared with those predicted by the Gardas and Coutinho model while viscosity data were correlated using the Vogel–Tammann–Fulcher method.     

Alkene metathesis catalysis in ionic liquids with ruthenium allenylidene salts

Ring closing metathesis of dienes in 1-butyl-3-methylimidazolium salts in the presence of ruthenium allenylidene salts as catalyst is described.     

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.     

Solubility of small molecule in ionic liquids: a model study on the ionic size effect

Recently, the solvent power of ionic liquid (IL) has been described based on Flory-Huggins (FH) theory assuming that the volumes of the components are the same (J. Phys. Chem. B, 2006, 110, 16205). Here, we extended the FH theory to derive the solvent power in the case of different sizes (molar volumes) of the IL's components based on "polymer-like" model. Applying this model, the effect of ionic size on the solvent power of ionic liquids has been investigated. It was found that the effect of size can be characterized by introducing the effective volume (V+ and V-) of each site of the ion, and for the equivalent ionic liquid, the larger effective volume of the ionic liquid has the larger solvent power. Our results are in excellent agreement with the experimental solubility data in various ionic liquids.     

Synthesis of novel spiro imidazolium salts as chiral ionic liquids

A library of 13 novel chiral spiro imidazolium salts has been synthesized. The effects of N-substituents and counteranions on the melting point of spiro bis(imidazolium) salts are studied in efforts toward the development of room temperature chiral ionic liquids.     

Functionalized imidazolium salts for task-specific ionic liquids and their applications

Recent developments in task specifically functionalized imidazolium salts, which can be used for specific tasks ranging from catalysts recycling, supports for organic synthesis, catalysis, separation of specific metal ions from aqueous solution, and construction of nanostructures and ion conductive materials, have been reviewed.     

Solubility and rate of dissolution for Miscanthus in hydrophilic ionic liquids

Miscanthus is a potential feedstock for the production of biofuels. Lignocellulosic biomass is not soluble in conventional solvents, but Miscanthus and other lignocellulosic biomass have reasonable solubilities in some ionic liquids. The solubility of Miscanthus in a variety of hydrophilic ionic liquids was measured as a function of particle size, temperature and time for dissolution. In addition to temperature and time, the ionic liquid anion has a significant effect on solubility and rate of dissolution. The moisture content of Miscanthus lowers its solubility in certain ionic liquids. Chloride, acetate, and phosphate-based ionic liquids favor solubility. A tentative correlation for the solubility of Miscanthus is proposed in terms of Abraham solvation parameters obtained from quantum-chemical model COSMO-RS (Conductor like Screening Model-Real Solvents).     

A simple halide-to-anion exchange method for heteroaromatic salts and ionic liquids

A broad and simple method permitted halide ions in quaternary heteroaromatic and ammonium salts to be exchanged for a variety of anions using an anion exchange resin (A(-) form) in non-aqueous media. The anion loading of the AER (OH(-) form) was examined using two different anion sources, acids or ammonium salts, and changing the polarity of the solvents. The AER (A(-) form) method in organic solvents was then applied to several quaternary heteroaromatic salts and ILs, and the anion exchange proceeded in excellent to quantitative yields, concomitantly removing halide impurities. Relying on the hydrophobicity of the targeted ion pair for the counteranion swap, organic solvents with variable polarity were used, such as CH(3)OH, CH(3)CN and the dipolar nonhydroxylic solvent mixture CH(3)CN:CH(2)Cl(2) (3:7) and the anion exchange was equally successful with both lipophilic cations and anions.     

Rapid and accurate estimation of densities of room-temperature ionic liquids and salts

Volume parameters for room-temperature ionic liquids (RTILs) and salts were developed. For 59 of the most common imidazolium, pyridinium, pyrrolidinium, tetralkylammonium, and phosphonium-based RTILs, the mean absolute deviation (MAD) of the densities is 0.007 g cm-3; for 35 imidazolium-based room-temperature salts, the MAD is 0.020 g cm-3; and for 150 energetic salts, the MAD is 0.035 g cm-3. The experimental density (Y) for an alkylated imidazolium or pyridinium-based room-temperature ionic liquid is approximately proportional to its calculated density (X) in the solid state: Y = 0.948X - 0.110 (correlation coefficient: R2 = 0.998, for BF4-, PF6-, NTf2- -containing ionic liquids); Y = 0.934X - 0.070 (correlation coefficient: R2 = 0.999, for OTf-, CF3CO2-, N(CN)2- -containing ionic liquids).     

Convenient synthesis of various ionic liquids from onium hydroxides and ammonium salts

Hydroxide ionic liquids, such as 1-alkyl-3-methylimidazolium hydroxides, undergo smooth anion metathesis with ammonium salts to produce a variety of ionic liquids in excellent yields. It is a practical supplement of traditional neutralization method due to the broader range of starting materials containing desired anions.     

Chloroalkylsulfonate ionic liquids by ring opening of sultones with organic chloride salts

An efficient route to prepare ionic liquids with chloroalkylsulfonate anions is presented; the synthesis proceeds in a one-step ring-opening reaction of sultones with an organic chloride salt and provides a very attractive access to new anion functionalised ionic liquids.     

Surface tension and refractive index of pure and water-saturated tetradecyltrihexylphosphonium-based ionic liquids

Experimental data on the surface tension and refractive index of tetradecyltrihexylphosphonium-based ionic liquids with bromide, chloride, decanoate, methanesulfonate, dicyanimide, bis(2,4,4-trimethylpentyl)phosphinate and bis(trifluoromethylsulfonyl)imide anions are reported. The data were obtained for pure and water saturated samples at temperatures from 283 K to 353 K and at atmospheric pressure. The refractive index of the investigated ionic liquids decreases with increasing the water content in the sample. On the other hand, no clearly dependence of the surface tension with the water content up to a weight fraction of 16% was found. The prediction of the refractive index for the studied ionic liquids was also accomplished by a group contribution method and new values for the cation and diverse anions were estimated and proposed. The studied ionic liquids show lower surface tension in comparison with imidazolium-, pyridinium- or pyrrolidinium-based ionic liquids with a similar anion; also they show higher surface entropy than cyclic nitrogen-based fluids which indicates a lower surface organization. The anion dependence of the surface tension and surface entropy for the investigated ionic liquids is weaker than that for short-chain imidazolium-based ionic liquids. Their critical temperatures evaluated from Eötvos and Guggenheim equations are also lower than those of N-heterocyclic ionic fluids.     

Palladate salts from chiral pyridinium ionic liquids: synthesis and crystal structures

This paper reports the preparation, characterization and the crystal X-ray structures of metal-containing ionic liquid complexes based on chiral pyridinium cations and tetrachloropalladate (II) [PdCl4]2-.