Water-insoluble Ionic Liquid Research Articles

C10MI·CF3SO3: a hydrophobic ionic liquid medium for the production of HMF from sugars avoiding the use of organic solvent

C10MI·CF3SO3, a water-insoluble ionic liquid (IL) associated to HCl, is shown as a highly efficient catalytic system for the production of 5-hydroxymethylfurfural (HMF) from fructose, 100% conversion with 90% of HMF selectivity after 1 h of reaction at 110 °C. As the IL is water-insoluble, HMF, which is soluble in water, is easily separated from the reaction solvent (IL) by water extraction in contrast to usual aqueous catalytic system that needs the use of organic solvent to extract HMF to proceed to its oxidation. The behavior of this catalytic system is evaluated and compared regarding the conversion of different sugars (fructose, glucose, and sucrose) by varying the reaction time.

Low fouling electrochemical sensing in complex biological media by using the ionic liquid-doped conducting polymer PEDOT: application to voltammetric determination of dopamine.

An electrochemical sensor that can resist biofouling even when operated in complex biological medium is developed for the determination of dopamine. It is based on the use of the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) that is doped with the water insoluble ionic liquid (IL), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. A glassy carbon electrode modified with PEDOT/IL is shown to enable accurate determination of dopamine, as a model analyte in the presence of high concentrations of proteins, and resist biological fouling even in native serum. It exhibited a low limit of detection of 33nM for the detection of dopamine, with a wide linear range from 0.2 to 328μM (at 0.2V vs. saturated calomel electrode). The PEDOT/IL modified glassy carbon electrode has a porous microstructure, high electrical conductivity and good stability. The sensor can be used to quantify dopamine in human urine samples with satisfying accuracy. Graphical abstract An antifouling electrochemical sensor capable of detecting target in complex biological samples was developed based on the use of a conducting polymer (PEDOT) that wasdoped with awater insoluble ionic liquid.

Electrical Response of a New Lipophilic Ionic Liquid and the Effect of CO2 on Its Conductivity Mechanism

Ionic liquids (ILs) have drawn sustained attention in the last twenty years due to their unique combination of intrinsic conductivity, very low vapour pressure and their ability to be tailored to an application via facile chemical modification [1]. As a consequence, the development of new ILs with improved properties and an in-depth understanding of the interplay existing between structures and properties are particularly active research fields. In this report preparation and study of a new lipophilic tetraoctyl-formamidinium bis(trifluoromethanesulfonyl) imide (TOFATFSI) ionic liquid [2], will be discussed. Tetraoctyl-formamidinium (TOFA) TFSI proved to be a water-insoluble IL that is completely miscible with the lower alkanes and the solutions are ionic conductors. Therefore, we were intrigued if conductivity could be induced in an even more demanding medium, i.e. supercritical carbon dioxide (scCO2) [3,4]. Following this, the conductivity and relaxation phenomena of this new IL are revealed through the analysis of the broadband electric spectra with a particular emphasis on the effect of temperature and CO2 pressure on the IL conductivity. It is found that temperature boosts the conductivity via an increase in the charge carrier mobility. Also, CO2 absorption affects both the conductivity and the permittivity of the material due to the presence of CO2–IL interactions that modulate the nanostructure and the size of the TOFATFSI aggregates, which increases both the mobility and the density of the charge carriers. Acknowledgements The authors wish to thank the Strategic Project of the University of Padova “Materials for Membrane-Electrode Assemblies to Electric Energy Conversion and Storage Devices (MAESTRA)” for funding. V.D.N. thanks the University Carlo III of Madrid for granting him the “Catedra de Excelentia” (Chair of Excellence).

Keys for Bioethanol Production Processes by Fermentation and Ionic Liquid Extraction

Bioethanol is produced by fermenting biomass. However, the main drawback of this process is the high purification costs involved, which are due to the energy-intensive distillation step and a drying step if high ethanol purity is required. This work evaluates an alternative separation–purification process for the production of ethanol, in which an ionic liquid is used to develop an integrated extraction–fermentation process. The capacity of ionic liquids to extract ethanol from an ethanol aqueous solution and their biocompatibility with Saccharomyces cerevisiae was analyzed. Ethanol extraction percentages ranging from 33% to 62% were obtained with the following water insoluble ionic liquids: [EPy+][NTf2–] < [MTOA+][NTf2–] < [OMIM+][BF4–] < [Hex3TDP+][dca–] < [Hex3TDP+][Br–] < [ Hex3TDP+][Cl–]. These ionic liquids could be used for in the postfermentation step of extraction. To evaluate the potential use of these ionic liquids as extraction phase in an integrated reaction/separation process, their biocompa...

Ionic liquids in enhancing the sensitivity of capillary electrophoresis: Off-line and on-line sample preconcentration techniques.

The popularity of ionic liquids (ILs) has grown during the last decade in enhancing the sensitivity of CE through different off-line or on-line sample preconcentration techniques. Water-insoluble ILs were commonly used in IL-based liquid phase microextraction, in all its variants, as off-line sample preconcentration techniques combined with CE. Water-soluble ILs were rarely used in IL-based aqueous two phase system (IL-ATPS) as an off-line sample preconcentration approach combined with CE in spite of IL-ATPS predicted features such as more compatibility with CE sample injection due to its relatively low viscosity and more compatibility with CE running buffers avoid, in some cases, anion exchange precipitation. Therefore, the attentions for the key parameters affecting the performance of IL-ATPSs were generally presented and discussed. On-line CE preconcentration techniques containing IL-based surfactants at nonmicellar or micellar concentrations have become another interesting area to improve CE sensitivity and it is likely to remain a focus of the field in the endeavor because of their numerous to create rapid, simple and sensitive systems. In this article, significant contributions of ILs in enhancing the sensitivity of CE are described, and a specific overview of the relevant examples of their applications is also given.

Ionic liquid based microextraction combined with derivatization for efficient enrichment/determination of asulam and sulfide

This study reports 2 new simple derivatization-based dispersive liquid-liquid microextraction (DLLME) methods for spectrophotometric ultratrace determination of asulam and sulfide. 1-Naphthol (in the presence of nitrite) and N,N-diethyl-p-phenylenediamine (in the presence of Fe(III)) were used to derivatize asulam and sulfide, respectively. In the enrichment methods, the formed derivatives were preconcentrated into microdroplets of the in situ formed water insoluble ionic liquid (IL), 1-hexyl-3-methylimidazolium hexafluorophosphate. Monitoring was performed at 526 nm for asulam and at 664 nm for sulfide, after dissolution of the IL-rich phases into the basic ethanolic solution and ethanol for asulam and sulfide, respectively. Beer's law was obeyed in the ranges of 1.0-80.0 and 0.1-5.0 ng mL$^{-1}$ for asulam and sulfide, respectively. Limits of detection for asulam and sulfide determination by the DLLME methods were 0.18 and 0.019 ng mL$^{-1}$, respectively. Various foreign cations, anions, organics, and pesticides were tested to evaluate the selectivity of the DLLME methods. The methods were successfully applied to the determination of asulam and sulfide in various environmental, wastewater, and urine samples.

Determination of triazine herbicides in fresh vegetables by dynamic microwave-assisted extraction coupled with homogeneous ionic liquid microextraction high performance liquid chromatography.

A novel extraction method, dynamic microwave-assisted extraction coupled with homogeneous ionic liquid microextraction, was developed for the determination of triazine herbicides, including desmetryn, terbumeton, propazine, terbuthylazine, dimethametryn, and dipropetryn in fresh vegetable samples by high performance liquid chromatography (HPLC). In the developed method, 120 μL of 1-butyl-3-methylimidazolium tetrafluoroborate ([C4MIM][BF4]) was added to 10 mL of aqueous solution containing 0.3 g of NaCl to obtained the extraction solvent. Six triazines could be extracted completely within 4 min by the present method. Then, [NH4][PF6] was added into the extract to form a water-insoluble ionic liquid [C4MIM][PF6] via a simple metathesis reaction, and the analytes were enriched into the ionic liquid phase. After centrifugation and dilution with acetonitrile, the resulting solution was analyzed directly by HPLC. The effects of some experimental parameters, including type and volume of ionic liquid, volume of extraction solvent, amount of ion-pairing agent [NH4][PF6], salt concentration, microwave power, and flow rate of extraction solvent on the extraction efficiency were investigated and optimized. Under the optimum experimental conditions, the linearity for determining the analytes was in the range of 2.50-250.00 μg kg(-1), with the correlation coefficients ranging from 0.9989 to 0.9999. When the present method was applied to the analysis of vegetable samples, satisfactory recoveries were obtained in the range of 76.8%-106.9%, and relative standard deviations were lower than 9.8%.

Ultrasound-assisted ionic liquid-based homogeneous liquid–liquid microextraction high-performance liquid chromatography for determination of tanshinones in Salvia miltiorrhiza Bge. root

The ultrasound-assisted ionic liquid-based homogeneous liquid–liquid microextraction has been developed and applied to the extraction of four tanshinones, including dihydrotanshinone, tanshinone I, cryptotanshinone and tanshinone IIA in Salvia miltiorrhiza Bge. root. High performance liquid chromatography was applied to the separation and determination of the analytes. The ionic liquid was used as extraction solvent and target analytes were extracted with help of ultrasound. Then, ion-pairing agent was added into the sample solution, which resulted in the formation of water-insoluble ionic liquid in the solution. The phase separation was performed by centrifugation. The extraction, concentration and purification of target analytes were performed simultaneously. The experimental parameters, including type and volume of ionic liquid, sample amount, the size of sample particle, pH value of extraction medium, extraction temperature, extraction time, amount of ion-pairing agent and centrifuging time, were investigated and optimized. The calibration curves showed good linear relationship (r>0.9997). The limits of detection and quantification were in the range of 0.052–0.093 and 0.17–0.31μgmL−1, respectively. The recoveries were between 70.45% and 94.23% with relative standard deviations lower than 5.31%. The present method is free of volatile organic solvents, and represents lower expenditures of sample, extraction time and solvent, compared with UAE and HRE. There was no obvious difference in the extraction yields of active constitutions obtained by the three extraction methods.

Indium(III) triflate — a catalyst for greener aromatic alkylation reactions

An environmentally friendly method for alkylating aromatic compounds with simple alcohols in the presence of a catalytic amount of indium(III) triflate is reported. Ionic liquids are used as solvents and energy-efficient heating is provided by microwave radiation. Good yields are obtained with benzyl, secondary, and tertiary alcohols. Simple primary alcohols are not effective alkylating agents under these conditions. With tertiary alcohols, activated aromatic compounds such as toluene and anisole must be used to obtain good yields. The catalyst, which is immobilized in a water-insoluble ionic liquid, can be easily recycled without significant loss of activity.

Synthesis and Esterification of 3‐Ferrocenyl Acrylic Acid in Ionic Liquid

Abstract3‐Ferrocenyl acrylic acid, synthesized from ferrocenecarboxaldehyde and propandioic acid in water‐insoluble ionic liquid (1‐butyl‐3‐methylimidazolium hexafluorophosphate, [BMIM]PF6) at 85 °C in high yield, was transformed to a series of 3‐ferrocenyl acrylate of alcohols and phenols in water‐soluble ionic liquid (1,3‐dimethylimidazolium dimethylphosphate, [DMIM]Me2PO4) at room temperature in the presence of dicyclohexylcarbodiimide (DCC) and 4‐dimethylaminopyridine (DMAP).

Ionic Liquid-Supported Pt Nanoparticles as Catalysts for Enantioselective Hydrogenation

Ionic liquid (IL)-supported metal nanoparticles (NPs) are under scrutiny as novel heterogeneous hydrogenation catalysts. Here we present a simple strategy to extend the scope of these catalysts from chemoselective hydrogenation reactions to enantioselective hydrogenations. Pt nanoparticles with a mean size of 2–3 nm and narrow size distribution were obtained by stabilization with water-insoluble ILs or both an IL and cinchonidine (CD) as chiral costabilizer. High reaction rates and enantioselectivities were achieved in the hydrogenation of methyl benzoylformate (MBF). This simple synthesis protocol opens the door to catalysts based on IL-supported chiral Pt group metal NPs.

Synthesis of Cinnamic Acid Derivatives in a Water-Insoluble Ionic Liquid

A number of cinnamic acid derivatives have been synthesised from commercially available aromatic aldehydes and propanedioic acid in a water-insoluble ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate, [bmim]PF6) in high yields in the presence of small catalytic amounts of piperidine. The ionic liquid can be reused at least five times.

Performance of d-amino acid oxidase in presence of ionic liquids

The activity and stability of free and immobilized D-amino acid oxidase (DAAO, EC 1.4.3.3) from Trigonopsis variabilis CBS 4095 in different water-soluble and water-insoluble ionic liquids (ILs) as well as in organic solvents were studied for comparison. The most promising ILs ([BMIM][BF(4)] and [MMIM][MMPO(4)]) were investigated in detail. The kinetic parameters (v(max) = 187 nkat/g dry weight, K(M) = 1.38 mM) with D-phenylalanine as substrate were calculated in 40% [BMIM][BF(4)]. Bioconversions of D/L-phenylalanine in 40% [BMIM][BF(4)] and 20% [MMIM][MMPO(4)] on a 3 ml scale using immobilized DAAO were performed by addition of free catalase from Micrococcus lysodeikticus. After total conversion of substrate in presence of 20% [MMIM][MMPO(4)] the residual activity of the immobilized DAAO was 79% and 100% of the free catalase.