Use of 8-sulfonamidoquinoline derivatives as chelate extraction reagents in ionic liquid extraction system

Possible use of 8-sulfonamidoquinoline derivatives as chelate extraction reagents for solvent extraction of several divalent metal cations using an ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF(6)]) as extraction phase was investigated as fundamental approach to develop novel extraction reagents for ionic liquid extraction system. The studied reagents were able to be used as extractants for the metal cations in the [bmim][PF(6)] extraction system. Furthermore, their extractability in the [bmim][PF(6)] system was superior to that in chloroform system. Most of the extracted species were (hydrated) neutral complexes, whereas, in use of the derivative having trifluoromethyl group, Cd(2+) was extracted as anionic complex accompanied with anion-exchange process.     

An imidazolium tosylate salt as efficient and recyclable catalyst for acetylation in an ionic liquid

A novel non-metallic salt, 1-butyl-3-methylimidazolium tosylate ([bmim][OTs]) dissolved in the ambient temperature ionic liquid of 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF₄]), was found to be the efficient catalyst for acetylation with the advantages of good recyclability, avoidance of metal contamination, mild reaction conditions, and wide availability for substrates (alcohols, phenols, and amines), could completely replace organic bases, metal Lewis acids, or metallic triflates to fulfill acetylation by a nucleophilic catalytic mechanism, which was supported by ¹³C NMR analysis. Correspondence: Ye Liu, Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Chemistry Department of East China Normal University, Shanghai 200062, China.     

Indirect ultraviolet detection of alkaline earth metal ions using an imidazolium ionic liquid as an ultraviolet absorption reagent in ion chromatography

A convenient and versatile method was developed for the separation and detection of alkaline earth metal ions by ion chromatography with indirect UV detection. The chromatographic separation of Mg²⁺, Ca²⁺, and Sr²⁺ was performed on a carboxylic acid base cation exchange column using imidazolium ionic liquid/acid as the mobile phase, in which the imidazolium ionic liquid acted as an UV‐absorption reagent. The effects of imidazolium ionic liquids, detection wavelength, acids in the mobile phase, and column temperature on the retention of Mg²⁺, Ca²⁺, and Sr²⁺ were investigated. The main factors influencing the separation and detection were the background UV absorption reagent and the concentration of hydrogen ion in ion chromatography with indirect UV detection. The successful separation and detection of Mg²⁺, Ca²⁺, and Sr²⁺ within 14 min were achieved using the selected chromatographic conditions, and the detection limits (S /N = 3) were 0.06, 0.12, and 0.23 mg/L, respectively. A new separation and detection method of alkaline earth metal ions by ion chromatography with indirect UV detection was developed, and the application range of ionic liquids was expanded.     

Supported imidazolium ionic liquid phases: A new material for solid-phase extraction

This study reports a material that is based on the concept of ionic liquid analogue: a slightly crosslinked polymer-supported imidazolium trifluoroacetate salt (IL-CF₃COO⁻) that favorably combines the properties of ionic liquids (ILs) and the advantages of a solid support.The ionic liquid-supported material was evaluated for the first time as a solid-phase extraction (SPE) sorbent for selectively and quantitatively extracting pharmaceuticals from aqueous samples.The novel IL-CF₃COO⁻ was evaluated under reversed-phase (RP), weak anion exchange (WAX), strong anion exchange (SAX) and strong cation exchange (SCX) SPE procedures, and we found that SAX conditions are the most suitable for investigating the behaviour of the IL-CF₃COO⁻ material. Under SAX conditions, the IL-CF₃COO⁻ material was capable of selectively and quantitatively extracting a group of acidic compounds from aqueous samples, while washing basic analytes that were also present in the sample.The SPE method using IL-CF₃COO⁻ material was used to analyse 1000 ml of different aqueous samples (ultrapure, tap and river) with complete recovery of the acidic compounds studied. Moreover, the method provided clean chromatogram and high recoveries when percolating complex real samples, such as 1000 ml of river water and 250 ml of effluent wastewater from a sewage treatment plant spiked at low levels with the analytes studied.     

Comparison of uranyl extraction mechanisms in an ionic liquid by use of malonamide or malonamide-functionalized ionic liquid

The extraction of uranyl from acidic (HNO(3)) aqueous solutions toward an ionic liquid phase, C(1)-C(4)-imTf(2)N (1-methyl,3-butylimidazolium Tf(2)N), has been investigated as a function of initial acid concentration and ligand concentration for two different extracting moieties: a classical malonamide, N,N'-dimethyl-N,N'-dibutylmalonamide (DMDBMA) and a functionalized IL composed of the Tf(2)N(-) anion and an imidazolium cation on which a malonamide pattern has been grafted (FIL-MA). The extraction mechanism, as demonstrated through the influence of added C(1)-C(4)-imCl or added LiTf(2)N in the aqueous phase, is slightly different between the DMDBMA and FIL-MA extracting agents. Modeling of the extraction data evidences a double extraction mechanism, with cation exchange of UO(2)(2+)versus 2 H(+) for DMDBMA or versus C(1)-C(4) -im(+) and H(+) for FIL-MA at low acidic values, and through anion exchange of [UO(2)(NO(3))(3)](-)versus Tf(2)N(-) for both ligands at high HNO(3) concentrations. The FIL-MA molecule is more efficient than its classical DMDBMA parent.     

Room temperature imidazolium ionic liquid: a solvent for extraction of carbamates prior to liquid chromatographic analysis

A simple and rapid method for preconcentration of carbamate insecticides, including methomyl, propoxur, carbofuran, carbaryl, isoprocarb, methiocarb and promecarb, has been developed. It was based on a liquid-liquid microextraction using a [C₄MIM][PF₆] room temperature ionic liquid as an extraction solvent prior to analysis by high performance liquid chromatography with UV detection. Experimental parameters affecting the extraction performance, such as the volumes of sample, extractant and dissolving solvent, and extraction time, were studied. Under the selected conditions, the enrichment factors in the range between 10 and 25 could be achieved with the limit of detection in the range of 2-40 μg L⁻¹, and with the relative standard deviations of lower than 0.6 and 10.2% for retention time and peak area, respectively. The proposed method offers advantages in reduction of the exposure danger to toxic solvents used in the conventional liquid-liquid extraction, simplicity of the extraction processes, rapidity, and sensitivity enhancement. The method was demonstrated to apply to the analysis of fruit and natural surface water samples.     

An imidazolium ionic liquid having covalently attached an oxime carbapalladacycle complex as ionophilic heterogeneous catalysts for the Heck and Suzuki-Miyaura cross-coupling

An oxime carbapalladacycle, analogous to that used as catalyst in homogeneous phase, has been derivatized to increase its ionophilicity by introducing an imidazolium group covalently attached through a chain at the complex. The resulting complex is soluble in 1-butyl-3-methylimidazolium ionic liquid (bmimPF₆) and not extractable by ether. The catalytic activity of this palladium complex in bmimPF₆ is, however, unsatisfactory and only increases marginally in bmimPF₆/supercritical CO₂. This limitation has been overcome by supporting this imidazolium palladium complex on high surface area Al/MCM-41 aluminosilicate, whereby a solid active catalyst for the Suzuki cross-coupling has been obtained. Reusability and stability over reuse for this Al/MCM-41-supported catalyst have been studied.     

Ion chromatography with the indirect ultraviolet detection of alkali metal ions and ammonium using imidazolium ionic liquid as ultraviolet absorption reagent and eluent

Indirect ultraviolet detection was conducted in ultraviolet‐absorption‐agent‐added mobile phase to complete the detection of the absence of ultraviolet absorption functional group in analytes. Compared with precolumn derivatization or postcolumn derivatization, this method can be widely used, has the advantages of simple operation and good linear relationship. Chromatographic separation of Li⁺, Na⁺, K⁺, and NH₄⁺ was performed on a carboxylic acid base cation exchange column using imidazolium ionic liquid/acid/organic solvent as the mobile phase, in which imidazolium ionic liquids acted as ultraviolet absorption reagent and eluting agent. The retention behaviors of four kinds of cations are discussed, and the mechanism of separation and detection are described. The main factors influencing the separation and detection were the background ultraviolet absorption reagent and the concentration of hydrogen ion in the ion chromatography‐indirect ultraviolet detection. The successful separation and detection of Li⁺, Na⁺, K⁺, and NH₄⁺ within 13 min was achieved using the selected chromatographic conditions, and the detection limits (S/N = 3) were 0.02, 0.11, 0.30, and 0.06 mg/L, respectively. A new separation and analysis method of alkali metal ions and ammonium by ion chromatography with indirect ultraviolet detection method was developed, and the application range of ionic liquid was expanded.     

A supercooled imidazolium iodide ionic liquid as a low-viscosity electrolyte for dye-sensitized solar cells

A series of allyl-functionalized imidazolium salts are reported, including 1-allyl-3-ethylimidazolium iodide and 1-allyl-3-propylimidazolium iodide, which have melting points close to room temperature and show typical properties of supercooled fluids if heated above their melting points. Their viscosities in the liquid state are considerably lower than the benchmark ionic liquid used in solar cells, viz., 1-propyl-3-methylimidazolium iodide. Electrolytes containing these new liquids provide excellent efficiencies and good stability in dye-sensitized solar cells when subjected to an accelerated-light soaking test at 60 degrees C. The structures of three of the new salts have been established in the solid state by single-crystal X-ray analysis.     

Catalytic properties of Pd-containing systems based on SBA-15 molecular sieve modified with imidazolium ionic liquid

Palladium(II) ions were incorporated in SBA-15 molecular sieve modified with imidazolium-based ionic liquids. The synthesized materials were characterized using differential thermic analysis, low-temperature nitrogen adsorption, transmission electron spectroscopy and elemental analysis. The materials obtained basing on a grafted ion liquid, in 1-hexene hydrogenetion were shown to exhibit the catalytic activity significanly higher than those prepared via ion liquid adsorption on supports.     

Preparation and evaluation of a novel bonded imidazolium ionic liquid as stationary phase for gas chromatography

1‐Butyl‐3‐[(3‐trimethoxysilyl)propyl]imidazolium chloride ionic liquid was synthesized and chemically modified onto the inner wall of a fused capillary column as a stationary phase for gas chromatography. The 1‐butyl‐3‐[(3‐trimethoxysilyl)propyl]imidazolium chloride ionic liquid bonded capillary column was evaluated in detail. The results revealed that the ionic liquid bonded capillary column exhibited high column efficiency of 1.08 × 10⁴ plates/m, and good chromatographic separation selectivity (α ) for polar and non‐polar substances, and a good thermal stability between room temperature and 400°C. Moreover, the determination of thermodynamic parameters and the linear solvation energy relationship were further carried out. The results indicated that the chromatographic retention of each probe molecule on the ionic liquid bonded stationary phase was an enthalpy‐driven process, and the system constants of the linear solvation energy relationship signified that the dispersion interaction, the hydrogen bonding acidity and hydrogen bonding basicity were dominant interactions between probes and stationary phase among five interactions during the chromatographic separation. However, the contribution of each specific interaction for the stationary phase is ranked as the dispersion interaction > the hydrogen bonding basicity > the hydrogen bonding acidity.     

Room temperature ionic liquid as a novel medium for liquid/liquid extraction of metal ions

Room temperature ionic liquids (RTILs) have been used as novel solvents to replace traditional volatile organic solvents in organic synthesis, solvent extraction, and electrochemistry. The hydrophobic character and water immiscibility of certain ionic liquids allow their use in solvent extraction of hydrophobic compounds. In this work, a typical room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate [C₄mim][PF₆], was used as an alternative solvent to study liquid/liquid extraction of heavy metal ions. Dithizone was employed as a metal chelator to form neutral metal-dithizone complexes with heavy metal ions to extract metal ions from aqueous solution into [C₄mim][PF₆]. This extraction is possible due to the high distribution ratios of the metal complexes between [C₄mim][PF₆] and aqueous phase. Since the distribution ratios of metal dithiozonates between [C₄mim][PF₆] and aqueous phase are strongly pH dependent, the extraction efficiencies of metal complexes can be manipulated by tailoring the pH value of the extraction system. Hence, the extraction, separation, and preconcentraction of heavy metal ions with the biphasic system of [C₄mim][PF₆] and aqueous phase can be achieved by controlling the pH value of the extraction system. Preliminary results indicate that the use of [C₄mim][PF₆] as an alternate solvent to replace traditional organic solvents in liquid/liquid extraction of heavy metal ions is very promising.     

Polymethacrylate microparticles covalently functionalized with an ionic liquid for solid-phase extraction of fluoroquinolone antibiotics

Microparticles were synthesized by suspension copolymerization of the synthetic ionic liquid (IL) 1-allyl-3-methyl-imidazolium bromide with ethylene glycol dimethacrylate. The particles have a regular spherical shape and an average diameter of 65 ± 24 μm. Their affinity for the fluoroquinolone antibiotics ofloxacin (OFL), lomefloxacin (LOM) and ciprofloxacin (CIP) is much higher than that of the blank polymer (not containing an IL), of polymers using methacrylic acid as functional monomer, of hydrophilic-lipophilic balanced sorbents, and of C₁₈ sorbents. The microparticles were applied to the solid-phase extraction and rapid preconcentration of the fluoroquinolones from urine which then were quantified by HPLC. The calibration plot covers the 0.05 to 20 μg mL⁻¹ concentration range, and the average recoveries at three spiking levels range from 93.6 to 103.7 %, with RSD of ≤5.7 %. The method was successfully applied to the determination of fluoroquinolones in spiked urine.

Microparticles covalently functionalized with an ionic liquid ([Amim][Br]) were synthesized by suspension copolymerization and show higher affinity for fluoroquinolones than other sorbents. The microparticles were used as a sorbent for solid-phase extraction and preconcentration of three fluoroquinolones from urine.

     

Enantioseparation of mandelic acid enantiomers in ionic liquid aqueous two-phase extraction systems

In the past decade, ionic liquids have received great attention owing to their potential as green solvent alternatives to conventional organic solvents. In this work, hydrophobic achiral ionic liquids (1-butyl-3-methylimidazolium-hexafluorophosphate([bmim][PF₆]), 1-octyl-3-methylimidazolium tetrafluoroborate([omim][BF₄])) were used as solvents in chiral liquid-liquid extraction separation of mandelic acid (MA) enantiomers with β-cyclodextrin (β-CD) derivatives as hydrophilic chiral selectors preferentially forming complexes with (R)-enantiomers. Factors affecting the separation efficiency were optimised, namely the type of the extraction solvents and β-CD derivatives, concentrations of the β-CD derivatives and MA enantiomers, pH, and temperature. Excellent enantioseparation of MA enantiomers was achieved in the ionic liquid aqueous two-phase extraction systems under the optimal conditions of pH 2.5 and temperature of 5°C with the maximum enantioselectivity (α) of 1.74. The experimental results demonstrated that the ionic liquid aqueous two-phase extraction systems with a β-CD derivative as the chiral selector have a strong chiral recognition ability, which might extend the application of ionic liquids in chiral separation.     

Task-specific ionic liquid trioctylmethylammonium salicylate as extraction solvent for transition metal ions

A quaternary ammonium-based room temperature ionic liquid trioctylmethylammonium salicylate (TOMAS) has been studied as an extractant of transition metal ions (Fe³⁺, Cu²⁺, Ni²⁺, Mn²⁺) in aqueous solutions. The effect of pH value on the recovery of metal ions has been investigated. The mechanism of extraction into the ionic liquid has been proposed. The possibility of stripping voltammetric determination of transition metals in aqueous solutions using TOMAS-modified electrodes has been demonstrated.     

Effect of nonpolar solvents on the solute rotation and solvation dynamics in an imidazolium ionic liquid

Recognizing the potential of the mixed solvent systems comprising ionic liquid as one of the constituents in real applications, the steady-state and time-resolved fluorescence behavior of C153 has been studied in neat 1-butyl-3-methylimidazolium hexafluorophosphate and its mixtures with nonpolar solvents, namely, toluene and 1,4-dioxane. No significant effect of the cosolvent on the steady-state absorption or fluorescence spectra of C153 in ionic liquid has been observed. Time-resolved fluorescence anisotropy measurements show a decrease of the rotational correlation time of C153 with gradual addition of the cosolvent. Solvation dynamics in ionic liquid-cosolvent mixtures is found to be biphasic, and a decrease of the average solvation time is observed with increasing amount of the cosolvent in solution. The time-zero spectrum of C153 is found to shift toward higher energy with gradual addition of the nonpolar solvent, suggesting that the probe molecule experiences a more nonpolar environment at the early stage of the dynamics in mixed solvents. The blue shift of the time-zero spectrum caused by the addition of the nonpolar solvent results in a larger Stokes shift of the time-dependent spectra due to solvent relaxation in mixed solvents. A comparison of the time-dependent spectral data of the ionic liquid-toluene and ionic liquid-dioxane systems shows that, while a small amount of toluene can significantly affect the dynamics, comparatively, a larger amount of dioxane is required to bring about the same effect. This is explained in terms of favorable interactions between toluene and the imidazolium ring system leading to a more effective solubilization of toluene in the cybotactic region of the probe.     

A "by-productless" cellulose foaming agent for use in imidazolium ionic liquids

Cellulose foams, or sponges, are produced from solutions in ionic liquids by the aqueous acid mediated decomposition of 1-alkyl-3-methylimidazolium-2-carboxylates, where the alkyl group and acid may be selected such that the by-product is the ionic liquid solvent: a by-productless foaming.     

Comparison of different imidazolium supported ionic liquid polymeric phases with strong anion-exchange character for the extraction of acidic pharmaceuticals from complex environmental samples

Two imidazolium supported ionic liquid phases (SILPs) containing different anions, trifluoromethanesulphonate [CF(3) SO(3) (-) ], and tetrafluoroborate [BF(4) (-) ], were synthesized and evaluated as solid-phase extraction sorbents for extracting acidic pharmaceuticals from aqueous samples under strong anion-exchange conditions, which include an effective cleanup of the sample. The best SILP material [MI(+) ][CF(3) SO(3) (-) ] was selected and successfully applied to the determination of acidic pharmaceuticals in different types of water samples (river water and effluent wastewater). The results were then compared to the previously synthesized SILP material based on [MI(+) ][CF(3) COO(-) ] and the commercially available Oasis MAX sorbent.     

1-Cyanoisoindole derivative as a highly sensitive fluorescence labelling reagent for steroidal primary alcohols in liquid chromatography

A sensitive and reactive labelling reagent for steroidal primary alcohols, m-(1-cyano-2-isoindole)benzoyl azide, was prepared from the corresponding carboxylic acid, which was synthesized from o-phthalaldehyde and m-aminobenzoic acid in the presence of potassium cyanide in one step. A hydroxysteroid, such as cortisol, can react with the reagent, when kept in benzene at 80 °C for 40 min, resulting in the formation of a urethane derivative which shows a single peak on the chromatogram and provides high sensitivity. The detection limit of the cortisol in reversed-phase chromatography is 80 fmol.