Ionic liquid media resulted in the first asymmetric aminohalogenation reaction of alkenes

[reaction: see text] The first asymmetric aminohalogenation of functionalized alkenes has been established. The ionic liquid [bmim][BF4] was found to be the only effective media for success as normal organic solvents failed to give any product for this reaction. The reaction is also very convenient to perform by simply mixing the three reactants, cinnamates, N,N-dichloro-p-toluenesulfonamide, and catalyst, together with 4 A molecular sieves at room temperature in [bmim][BF4] in any convenient vial of appropriate size without special protection from inert gases. Good chemical yields (60-72%) and diastereoselectivities (up to 75% de) have been obtained with a good scope of substrates. The resulting individual diastereomers have been cleanly separated via column chromatography. The absolute stereochemistry of the reaction was unambiguously determined by X-ray structural analysis.     

Ring opening reaction of furan with high regio- and diastereo-selectivity via controlled addition of isatin-derived diazoamides

Reaction of cyclic diazoamides with furan systems using rhodium(II) acetate as a catalyst afforded a variety of (3Z)-3-[(2E)-4-oxopent-2-en-1-ylidene]indol-2-ones in a regio- and diastereo-selective manner. The diastereoselectivity was based on the flow rate of cyclic diazoamides. The representative products were characterized by single-crystal X-ray analyses.     

Ionic liquid incorporated polystyrene resin for solid-phase peptide synthesis

Ionic liquid (IL) resins with an ionic liquid environment on solid support were prepared by immobilizing ionic liquid spacers on polystyrene (PS) resin. The properties of IL resins were dramatically changed as the anions of IL were exchanged. The performance of IL resins for solid-phase peptide synthesis (SPPS) was evaluated by measuring coupling kinetics of the first amino acid and synthesizing several peptides on IL resins.     

CuI/La(OTf)3 catalyzed, one-pot synthesis of isomeric ellipticine derivatives in ionic liquid

An efficient method for one-pot synthesis of isomeric ellipticine derivatives through CuI/La(OTf)₃ catalyzed sequential inter/intramolecular cyclization of substituted alkynes with imines followed by aromatization is reported in good to excellent yields.     

Multi-component, 1,3-dipolar cycloaddition reactions for the chemo-, regio- and stereoselective synthesis of novel hybrid spiroheterocycles in ionic liquid

A library of novel 1-methyl-4-arylpyrrolo-(spiro[2.2′]indan-1′,3′-dione)-spiro[3.3″]-1″-methyl/benzyl-5″-(arylmethylidene)piperidin-4″-ones and 1-methyl-4-arylpyrrolo-(spiro[2.11′]-11H-indeno[1,2-b]quinoxaline)-spiro[3.3″]-1″-methyl/benzyl-5″-(arylmethylidene)piperidin-4″-ones have been synthesized via 1,3-dipolar azomethine ylide cycloaddition in the ionic liquid, 1-butyl-3-methylimidazolium bromide ([BMIm]Br), in excellent yields.     

Ionic liquid mediated efficient reduction of nitroarenes using stannous chloride under sonication

Nitroarenes were rapidly reduced to the corresponding aromatic amines using stannous chloride in ionic liquid as a safe and recyclable reaction medium under sonication. The method is environmentally benign and sensitive functional groups remain unaffected.     

Synthesis and Crystal Structure of Hexakis(N—allylthiourea)tetracopper(I) Tetratrifluoromethanesulfonate, [Cu4{CH2=CHCH2NHC(S)NH2}6](SO3CF3)4

Hexakis(N—allylthiourea)tetracopper(I) Tetratrifluoromethanesulfonate, [Cu₄{CH₂=CHCH₂NHC(S)NH₂}₆](CF₃SO₃)₄ (sp.gr.P2₁/n, a = 13.5463(8), b = 24.129(2), c = 19.128(1)Å, β = 108.053(6)°, Z = 4, R = 0.0440 for 13548 unique reflections) was obtained by reduction of Cu(CF₃SO₃)₂ with excess of N—allylthiocarbamide in benzene medium. Four crystallographical independent Cu atoms possess trigonal environment of three S atoms of CH₂=CHCH₂NHC(S)NH₂ moiety and form Cu₄S₆⁴⁺ adamantane—like fragments. The latteres are connected with CF₃SO₃^— anions via (C)—H···F hydrogen bonds.     

Copper complex immobilized on imidazolium supported ionic liquid for ultrasound promoted ester synthesis

1-glycyl-3-methyl imidazolium chloride-copper (II) complex [[Gmim]Cl-Cu (II)] was found to be a heterogeneous catalyst for an efficient and greener solvent free synthesis of esters by condensation of carboxylic acids and alcohols with excellent yield with high turnover number (8.3 × 10² to 9.5 × 10²) using ultrasound irradiation. In addition, this method features reusability of catalyst, reduced waste, thus making new protocol more environmentally suitable whilst no catalyst leaching was observed.     

Ionic cyclodextrins in ionic liquid matrices as chiral stationary phases for gas chromatography

Ionic liquids (ILs) are used to dissolve ionic cyclodextrin (CD) derivatives to produce a new type of gas chromatographic chiral stationary phase. Compared to a previous study with neutral cyclodextrin chiral selectors, the new ionic liquid-based stationary phase exhibits broader enantioselectivities, up to seven times higher efficiencies, and greater thermal stabilities. When compared to the analogous commercial column with polysiloxane matrix, it exhibits different enantioselectivities, more symmetric peak shapes and some complementary enantioseparations. The most profound separation enhancements are usually found for more polar analytes.     

Solubilities of cinnamic acid esters in binary mixtures of ionic liquids and organic solvents

The solubilities of three cinnamic acid esters, namely, methyl ferulate, methyl p-coumarate, and methyl sinapate, have been measured in mixed solvent systems of tert-butanol with 1-butyl-3-methyl-imidazolium hexafluorophosphate ([BMIM][PF₆]), 1-butyl-3-methyl-imidazolium tetrafluoroborate ([BMIM][BF₄]) and 1-methyl-3-octyl-imidazolium tetrafluoroborate ([OMIM][BF₄]) at 303.15 and 321.15 K, and in mixed solvent systems of ethyl acetate with [BMIM][BF₄] and [OMIM][BF₄] at 303.15 K. In eight cases, out of the 22 data sets, an additive behaviour of the solubility was observed, positive deviations from additivity were observed in six cases, a positive synergistic effect in five cases, and, finally, negative deviations from additivity in the remaining three cases. Prediction of the solubilities of the solutes in the various ternary systems was performed with the NRTL and UNIQUAC activity coefficient models. The binary interaction parameters of the models between solute and solvent molecules were taken from the literature. When the parameters between the solvent molecules are fitted to literature data, satisfactory predictions are not always obtained. On the other hand, very good predictions are obtained when only one of the two interaction parameters between the two solvent molecules is fitted to one single point of the solubility isotherm and the other interaction parameter is set equal to zero.     

Ionic liquid based dispersive liquid-liquid microextraction of aromatic amines in water samples

In this work, a new microextraction method termed ionic liquid based dispersive liquid-liquid microextraction （IL-DLLME） was demonstrated for the extraction of 2-methylaniline, 4-chloroaniline, 1-naphthylamine and 4-aminobiphenyl in aqueous matrices. After extraction the ionic liquid （IL） phase was injected directly into the high performance liquid chromatography （HPLC） system for determination. Some parameters that might affect the extraction efficiency were optimized. Under the optimum conditions, good linear relationship, sensitivity and reproducibility were obtained. The limits of detection （LOD, S/N = 3） for the four analytes were in the range of 0.45-2.6 μg L^-1. The relative standard deviations （R.S.D., n = 6） were in the range of 6.2-9.8%. This method was applied for the analysis of the real water samples. The recoveries ranged from 93.4 to 106.4%. The main advantages of the method are high speed, high recovery, good repeatability and volatile organic solvent-free.     

Aerobic oxidation of phenol to quinone with copper chloride as catalyst in ionic liquid

Aerobic oxidation of 2,3,6-trimethyl-phenol to trimethyl-1,4-benzoquinone with 2.5 mol% copper(II) chloride as catalyst in ionic liquid 1-n-butyl-3-methyl-imidazolium chloride, [BMIm]Cl, with n-butanol as co-solvent affording 86% yield provides a new alternative to the copper(II) chloride catalysed aerobic oxidation. The advantage of this catalytic system is that only a catalytic amount of copper(II) chloride is necessary. This catalytic system is also applicable for oxidation of 2-methyl-1-naphthol to 2-methyl-1,4-naphthoquinone. This catalytic reaction was systematically investigated under different conditions.     

Ionic liquids as surfactants in micellar liquid chromatography

This paper is devoted to application of ionic liquids as surfactants in LC of organic compounds, derivatives of 1,4‐thiosemicarbazides. According to HPLC requirements the most advantageous conditions such as transparency for ultraviolet light, low CMC, additional inorganic salt additives, and appropriate organic solvent were established. The CMC was determined using conductivity measurements. Suitability of two different stationary phases: RP‐C18 and cyanopropyl bonded phase was examined under micellar conditions. Chosen ionic liquid surfactant was compared to common traditional amphiphilic reagent – SDS. Elaborated on chromatographic micellar conditions were tested as a pilot technique for prediction of distribution coefficients of organic analytes in ionic liquid‐based aqueous two‐phase system.     

Copper nanoparticles in an ionic liquid: an efficient catalyst for the synthesis of bis-(4-hydroxy-2-oxothiazolyl)methanes

Copper nanoparticles were synthesized and characterized by TEM, XRD and UV-vis techniques. The copper nanoparticles in an ionic liquid were employed as a recyclable catalyst for the synthesis of bis-(4-hydroxy-2-oxothiazolyl)methanes in excellent yields and in short reaction times.     

Chemo-, regio- and stereoselective addition of triorganoindium reagents to acetates of Baylis-Hillman adducts: a new strategy for the synthesis of (E)- and (Z)-trisubstituted alkenes

The addition of several trialkyl or triarylindium reagents to the acetates of Baylis-Hillman adducts proceeds readily under the catalysis of copper and palladium derivatives. The reactions of trialkylindiums are catalyzed efficiently by CuI whereas additions of triarylindiums produce better results with Pd(PPh₃)₄. The reactions with 3-acetoxy-2-methylenealkanoates provide (E)-alkenes, whereas similar reactions with 3-acetoxy-2-methylenealkanenitriles lead to (Z)-alkenes. All the reactions are highly regio- and stereoselective and high yielding.     

Extraction and determination of hormones in cosmetics by homogeneous ionic liquid microextraction high-performance liquid chromatography

The homogeneous ionic liquid microextraction was applied to the extraction of hormones from cosmetics and the hormones were determined by high-performance liquid chromatography. 1-Hexyl-3-methylimidazolium tetrafluoroborate was used as extraction solvent. Ammonium hexafluorophosphate as used as ion-pairing agent. Several experimental parameters, including the volume of 1-hexyl-3-methylimidazolium tetrafluoroborate, amount of ammonium hexafluorophosphate and sodium chloride, extraction and centrifuge time, and the pH value, were optimized. The limits of detection and quantification for the analytes ranged from 0.03 to 0.24 ng/mL and from 0.10 to 0.79 ng/mL, respectively. The precision for determining the hormones was lower than 5.2%. The proposed method was successfully developed for the determination of hormones in real cosmetic samples.     

Zn in ionic liquid: an efficient reaction media for the synthesis of diorganyl chalcogenides and chalcogenoesters

A straightforward and efficient methodology is described to synthesize structurally diverse diorganyl selenides, sulfides, seleno- and thioesters by using commercially available Zn dust in ionic liquid. Excellent yields were achieved under neutral conditions at room temperature in a short time. The solvent/ionic liquid is reusable and exhibited higher performance as compared with organic solvents.     

Ionic liquids extraction of Para Red and Sudan dyes from chilli powder, chilli oil and food additive combined with high performance liquid chromatography

A simple analytical method, based on the coupling of ionic liquid-based extraction with high performance liquid chromatography (HPLC), is developed for the determination of Sudan dyes (I, II, III and IV) and Para Red in chilli powder, chilli oil and food additive samples. Two ionic liquids (ILs), 1-butyl-3-methylimidazolium hexafluorophosphate ([C₄mim][PF₆]) and 1-octyl-3-methylimidazolium hexafluorophosphate ([C₈mim][PF₆]), were compared as extraction solvents; experiments indicated that the latter possesses higher recoveries for each analyte. Parameters related to extraction of Sudan dyes and Para Red were also optimized. Under the optimal conditions, good reproducibility of extraction performance was obtained, with the relative standard deviation (RSD) values ranging from 2.0% to 3.5%. The detection limits of Sudan dyes and Para Red (LOD, S/N = 3) were in the range of 7.0-8.2 μg kg⁻¹ for chilli powder and 11.2-13.2 μg L⁻¹ for chilli oil and food additive. The recoveries were in the range of 76.8-109.5% for chilli powder samples and 70.7-107.8% for chilli oil and food additive samples.