Functionalized Imidazolium Ionic Liquids Research Articles

Vinyl-containing covalent organic frameworks co-polymerized with imidazolium ionic liquids for the efficient cycloaddition of CO2 with epoxides

The chemical fixation of CO2 into high value-added cyclic carbonates over metal- and cocatalyst-free heterogeneous catalyst has attracted considerable attention and is still a challenge. Rationally integrating multifunctional units into porous materials has been regarded as a promising strategy to enhance catalytic efficiency. In this study, the poly (ionic liquid)-hierarchical covalent organic framework (R-PIL-COF, R refers to CH2NH2/CH2OH/COOH/CH3) hybrids were successfully fabricated via in situ copolymerization of vinyl-containing covalent organic framework and hydrogen bond donors (HBDs)-functionalized imidazolium ionic liquids. Among, CH2NH2-PIL-COF hybrid bearing acidic and basic sites possess moderate CO2 adsorption ability and hierarchical pore structure which promoted the activation of CO2 and epichlorohydrin. Furthermore, the influence on the catalytic activity of various HBD groups and grafting amounts of poly (ionic liquid)s were systematically investigated, and CH2NH2-PIL-COF-45% exhibited an exceptional catalytic performance under mild conditions (100 °C and 1 MPa CO2 pressure). Additionally, CH2NH2-PIL-COF-45% had broad substrate tolerance and excellent stability. Finally, a synergistic catalytic mechanism was proposed based on the experimental and characterization results. The strategy of co-polymerizing ionic liquids to COF provides a new way to develop efficient COF-based hybrids by the integration of nucleophilic units into the COF skeleton for CO2 fixation under cocatalyst-free and mild conditions.

Ruthenium Nanoparticles Stabilized with Methoxy-Functionalized Ionic Liquids: Synthesis and Structure-Performance Relations in Styrene Hydrogenation.

A series of ruthenium nanoparticles (RuNPs) were synthesized by the organometallic approach in different functionalized imidazolium ionic liquids (FILs). Transmission electron microscopy (TEM) showed well-dispersed and narrow-sized RuNPs ranging from 1.3 to 2.2 nm, depending on the IL functionalization. Thermal gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) allowed the interaction between the RuNPs and the ILs to be studied. The RuNPs stabilized by methoxy-based FILs (MEM and MME) displayed a good balance between catalytic activity and stability when evaluated in the hydrogenation of styrene (S) under mild reaction conditions. Moreover, the catalysts showed total selectivity towards ethylbenzene (EB) under milder reaction conditions (5 bar, 30 °C) than reported in the literature for other RuNP catalysts.

Data on creation and description of mono and dicationic bi-functionalized ionic liquids derived from aldehydic functionalized imidazolium ionic liquids

Data on creation and description of mono and dicationic bi-functionalized ionic liquids derived from aldehydic functionalized imidazolium ionic liquids

Epoxidation of unsaturated fatty acid ester promoted by imidazolium acidic ionic liquids: An unexpected selectivity phenomena

AbstractEpoxidation of linseed oil fatty acid ethyl esters promoted by a series of functionalized imidazolium ionic liquids was studied. In this reaction acidic imidazolium ILs behave not only as an acid catalysts but also play an additional role as a specific activator for the reaction of epoxidation of unsaturated fatty derivatives in H2O2/formic acid oxidation system. The obtained results indicate that the hydrogen‐bonding interaction of imidazolium cation with epoxide group influences the selectivity of the epoxidation reaction. In particular, the presence of unprotected weak “acid” C2‐H proton significantly lowers the selectivity to hydroxyl derivatives. The obtained results also point to another example of specific polyfunctionality of ILs, especially imidazolium one, used as surfactants and process activators.

In‐situ Synthesis of Ionic Liquids on B‐doped Mesoporous SiO2 Catalyst for Epoxide‐CO2 Cycloaddition

AbstractA series of functionalized ionic liquids (ILs) immobilized on B‐doped mesoporous SiO2 catalysts were fabricated for effectively converting CO2 into cyclic carbonates under metal‐absent and cocatalyst‐free conditions. Functionalized imidazolium ILs were in‐situ synthesized by Debus‐Rdziszewski imidazole reaction. Among the prepared catalysts, 5B−SiO2−NH2−3−I catalyst owing to the synergistic effects of nucleophile, Lewis acid‐base and hydroxyl hydrogen bond donors in the catalyst, presented the better catalytic activity for propylene epoxide to the product of propylene carbonate with 99% yield and selectivity at 110 °C and 2 MPa CO2. The catalyst also displayed moderate yield for various mono‐substituent epoxides. Besides, the gradual decline in the product yield during consecutive runs could be easily refreshed by aqueous acidic solution washing.

Titanium Dioxide Nanoparticles Modified with Disulfonic Acid Functionalized Imidazolium Ionic Liquids for Use as Electrorheological Materials

A disulfonic acid functionalized ionic liquid, 1,3-disulfonic acid imidazolium chloride ([Dsim]Cl), was synthesized and utilized to prepare TiO2-based ionogel nanoparticles (TiO2-[Dsim]Cl) using a ...

Multifunctional periodic mesoporous organosilica supported dual imidazolium ionic liquids as novel and efficient catalysts for heterogeneous Knoevenagel condensation

A type of multifunctional periodic mesoporous organosilica supported dual imidazolium ionic liquids PMO-IL-anion have been designed and prepared, characterized and evaluated as heterogeneous catalysts for the Knoevenagel condensation. The as-fabricated supported ionic liquids show good catalytic performances in the Knoevenagel condensation at room temperature, especially the supported ionic liquids PMO-IL-NTf2 and PMO-IL-PF6, based on a synergetic effect between the Lewis-base-type sites of dual functionalized imidazolium ionic liquids and active sites of periodic mesoporous organosilica. The best catalytic performance over PMO-IL-NTf2 was observed with excellent yields of 93∼99% in a short time of 20∼30 min. In addition, the heterogeneous catalyst offers simple operation for recovery and the recycling test showed that it could be reused for five times without significant loss of catalytic activity, thus making this process economical and environmental-friendly.

Dual functionalized imidazolium ionic liquids as a green solvent for extractive desulfurization of fuel oil: Toxicology and mechanistic studies

Readily biodegradable and “practically non-toxic” dual functionalized imidazolium ionic liquids (ILs) carrying nitrile and varying number of ether group were developed to improve the extractive desulfurization performance and ecotoxicity of ILs. Dicyanamide (N(CN)2), trifluoroacetate (CF3COO) and bis(trifluoromethylsulfonyl)imide (NTf2) were selected as anions. Evaluation of thermophysical properties of the synthesized ILs revealed that bis(trifluoromethylsulfonyl)imide anion based ILs have lowest viscosity, which contributed to excellent mass transfer and enhanced desulfurization performance. The effect of temperature, time and mass ratio (ILs: model oil) were investigated for extractive desulfurization and the performance of ILs were in the anion order; dicyanamide < trifluoroacetate < bis(trifluoromethylsulfonyl)imide. Dibenzothiophene was more selectively extracted over 4,6- dimethyldibenzothiophene. Increasing alkoxy group on the cation side chain improved the desulfurization efficiency. More than 70% of dibenzothiophene was extracted in 15 min (single stage extraction) with a mass ratio of 1.5:1 at 25 °C by bis(trifluoromethylsulfonyl)imide anion based ILs with three ether groups on the imidazolium cation. Conductor like Screening Model for Real Solvents tool (COSMO-RS) and FTIR spectroscopy study revealed that interaction between dibenzothiophene and ILs were mainly dominated by π-π interaction and hydrogen bonding. The microbial toxicity and biodegradability assessment indicated that ILs were “practically harmless” and “readily biodegradable” through the incorporation of alkoxy groups on the cationic core of bis(trifluoromethylsulfonyl)imide anion based ILs. The ILs can be reused more than 8 cycles for the desulfurization process without regeneration.

Functionalized imidazolium ionic liquids promote seawater desalination through forward osmosis

Carboxylate-functionalized imidazolium ionic liquids (CFIMILs) were synthesized via a one-pot quaternization reaction and serve as draw solutes for the first time for forward osmosis (FO) desalination. It provides a solution to simultaneously overcome the problems plaguing the use of pressure-driven membrane technologies to extract water from saline water – low water recovery efficiency and high reverse solute diffusion. The CFIMILs contain a substituted 5-membered imidazole ring and fully ionize into ionic species in water. These characteristics endow CFIMILs with capability of high water recovery efficiency and minimal reverse diffusion in FO. Sodium salt of 1-acetate-2,3-dimethyl imidazole ionic liquid (IL-1) at 0.8 M produces water fluxes of 63.6 LMH (PRO mode) and 29.5 LMH (FO mode) against the DI water feed, greatly outperforming conventional NaCl draw solute and other synthetic draw solutes. Efficient water recovery is achieved using IL-1 for seawater desalination with a water flux 5 times higher than that of NaCl. Particularly, CFIMILs draw solutes have negligible reverse diffusion in FO and are recycled completely via an MD process with good reproducibility when reused to FO, demonstrating great potentials of CFIMILs as a new class of draw solutes for FO water treatment.

Reversed-phase ion-pair chromatography of hydroxyl functionalized imidazolium ionic liquid cations and its application in analysis of environmental water and measurement of hydrophobicity constants

A reversed-phase ion-pair chromatography with ultraviolet detection method for the determination of 1‑hydroxyethyl‑3‑methyl imidazolium cation ([HOEtMIm]+) and 1‑hydroxypropyl‑3‑methyl imidazolium cation ([HOPrMIm]+) was developed. The method has been applied to the analysis of hydroxyl functionalized imidazolium ionic liquid cations in Songhua River water samples and the determination of hydrophobicity constants. [HOEtMIm]+ and [HOPrMIm]+ were not completely separated in the reversed-phase chromatography, but complete separation was realized in the reversed-phase ion-pair chromatography. The effects of ion-pair reagents, organic solvents, column temperatures and ultraviolet detection wavelengths on the separation and detection of hydroxyl functionalized imidazolium ionic liquid cations in reversed-phase ion-pair chromatography were investigated. Ordinary imidazolium ionic liquids do not interfere with the determination of hydroxyl functionalized imidazolium ionic liquids. The suitable ion-pair reagent was sodium octanesulfonate. Using reversed-phase C18 chromatographic column, the mobile phase consisted of 0.5 mmol/L sodium octanesulfonate solution/methanol (85/15, v/v) with column temperature of 40 °C, ultraviolet detection wavelength of 210 nm and flow rate of 1.0 mL/min, [HOEtMIm]+ and [HOPrMIm]+ can be achieved baseline separation within 20 min. The detection limits were 0.36 and 0.50 mg/L, respectively. The relative standard deviations of peak area and retention time were less than 0.80%. Recoveries of sample addition were between 97.3% and100.5%. The method was simple, accurate, reliable, satisfying the requirement of quantitative analysis, and has good practicability.

Cross-Linked Poly(ethylene oxide) Ion Gels Containing Functionalized Imidazolium Ionic Liquids as Carbon Dioxide Separation Membranes

1,3-Substituted imidazolium bis(trifluoromethylsulfonyl)imide (Tf2N) ionic liquids (ILs) were incorporated at 40 and 60 vol % loading into a cross-linked poly(ethylene oxide) polymer network to cre...

Enhancing High‐Rate Capability by Introducing Phosphonate Functionalized Imidazolium Ionic Liquid into Organic Carbonate Electrolyte

AbstractA phosphonate functionalized imidazolium ionic liquid (PFIL) is synthesized and studied as an electrolyte additive for lithium ion batteries. The Li/LiFePO4 cells with addition of PFIL shows superior electrochemical performance, including an increased initial Coulombic efficiency, better capacity retention, and improved rate capability. The electrochemical mechanism of PFIL used in high‐performance batteries is investigated by using fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). Our experimental result reveals that the phosphonate groups are stronger donors than carbonate groups, thus change the solvation environment of lithium ions by competitive coordination, assisting the transferring of lithium ions. Therefore, an excellent cyclability and superior rate capability with PFIL‐based electrolyte could be explained by enhanced mobility lithium ions via coordination to phosphonate groups on imidazolium cations. This work displays that PFIL‐based electrolyte systems can be considerable potential candidates for the applications in high‐performance Li‐ion batteries.

Nafion® based hybrid composite membrane containing GO and dihydrogen phosphate functionalized ionic liquid for high temperature polymer electrolyte membrane fuel cell

A new hybrid composite proton exchange membrane has been synthesized from dihydrogen phosphate functionalized imidazolium ionic liquid (IL-H2PO4), graphene oxide, and Nafion 117 solution. The chemical structure and thermal stability of the dihydrogen phosphate functionalized imidazolium ionic liquid (IL-H2PO4) have been analyzed by 1H nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA). The structural, thermal, and surface properties of synthesized membranes have been confirmed by FTIR spectroscopy, X-ray diffraction, TGA, and scanning electron microscopy. The proton exchange membranes have been characterized by their ionic conductivity and unit cell performance. The incorporation of IL-H2PO4 and graphene oxide in the Nafion membrane increases its thermal stability. The ionic conductivity of the membranes increases with temperature and amount of IL-H2PO4. The highest ionic conductivity of 0.061 Scm−1 has been achieved at 110 °C under anhydrous conditions which is 1.3 times higher than that of commercial Nafion 117. The synthesized membrane, Nafion/IL/GO, shows the best unit cell performance with a power density of 0.02 W cm−2, which is 13 times higher than that of the commercial Nafion 117 membrane at 110 °C.

Palladium supported ionic liquid phase catalyst (Pd@SILP-PS) for room temperature Suzuki-Miyaura cross-coupling reaction

A new Pd-SILP based on amino functionalized imidazolium ionic liquid immobilized on Merrifield resin (Pd@SILP-PS) has been synthesized. The catalyst was characterized by different techniques like FT-IR, SEM-EDS, TEM, TGA-DTA and XPS. The catalyst has shown to be highly active in Suzuki-Miyaura cross-coupling reaction of various aryl halides and aryl boronic acids in ethanol at room temperature. The activity of catalyst and the nature of product were highly dependent on the type of the solvent used, as well as the substituents present on the aryl halides. The protic polar solvent ethanol gave desired cross-coupling product in good to excellent yields at room temperature. However the aprotic polar solvent THF gave homocoupling product. The catalyst showed at least five times recyclability without a decrease in product yield.

Extractive desulfurization of model fuel oil using ester functionalized imidazolium ionic liquids

Abstract A series of ester functionalized imidazolium ionic liquids (ILs) with varying alkyl chain length were synthesized and characterized. Dicyanamide was chosen as the anion for these series of ILs. NMR (1H and 13C) and elemental analysis were used to confirm the structure of ILs. Thermal analysis (TGA) revealed that the synthesized ILs have good thermal stability up to 180 °C. The ILs were screened by COSMO-RS to further investigate their σ surface, σ potential and σ profile to obtain better understanding on the nature of interaction of ILs with sulfur compounds. The effect of temperature, time and mass ratio (ILs: model oil) were studied for the extraction of dibenzothiophene (DBT) from model oil using the synthesized ILs. The extractive desulfurization of model oil containing DBT in n-dodecane revealed that the ester functionalized ILs with an alkyl length of six carbon atoms, [C2COOCH3ImC6H13][N(CN)2] is the most promising candidate. More than 80% of DBT was extracted in 15 min with a mass ratio (ILs: model oil) of 2:1 at 25 °C. This high efficiency was observed in a single stage extraction, which indicated that the ester based ILs are an ideal candidate for the removal of DBT in a short extraction period. The ILs had good reusability up to 10 cycles with high extraction efficiency. The toxicity profile of ILs were assessed to evaluate their impact on environment and living organisms. Microbial toxicity studies depicted that the ILs can be considered as “practically harmless”.

Composite Ionic Liquids Immobilized on MCM-22 as Efficient Catalysts for the Cycloaddition Reaction with CO2 and Propylene Oxide

Ionic liquids (ILs) have shown predominant catalytic activity in the field of catalytic conversion of CO2. Unfortunately, ILs catalysts can be only used in kettle catalysis as homogeneous systems, which suffered from the difficulty in product purification and catalysts recycling so affect their industrial application. In this work, a series of composite ILs were prepared by functionalized imidazolium ILs and lewis acid (ZnBr2). Then composite ILs immobilized on molecular sieve (MCM-22) with chemical bonding to obtain heterogeneous catalysts applied in the reaction of propylene oxide and carbon dioxide to synthesize propylene carbonate. The effects of catalytic temperature, pressure and cycle times on the conversion and yield were studied. The results showed that the optimal catalyst was MCM-22-[CeMIM]Cl/(ZnBr2)2, when the catalytic temperature is 120 °C, the pressure is 2.5 MPa and the dosage of catalyst is 2.0%, the conversion rate is 100%, and selectivity is 97.4%.

Physicochemical and thermodynamic properties of imidazolium ionic liquids with nitrile and ether dual functional groups

Synthesis of new dual functionalized imidazolium ionic liquids (ILs) containing nitrile functionality and ether group were synthesized and characterized. Bis(trifluoromethylsulfonyl)imide, trifluoroacetate and dicyanamide were used as the anion. The combination of two functional groups on an imidazolium cation was mainly developed to assess their potential in desulfurization of fuel oil. Although ILs based on this individual functional group has been reported to improve the desulfurization efficiency, no effort has been made to combine nitrile and ether functional groups on the same cation to enhance the desulphurization potential. In this report, we tailored both nitrile and ether functionality on imidazolium cation and studied their physicochemical properties in details. NMR (1H and 13C) spectroscopy and elemental analysis were used to characterize the synthesized ILs. Physical properties and optical properties of the ILs were investigated in a wide temperature range. The synthesized ILs showed good thermal stability. COSMO-RS was effectively utilized to discuss the σ surface, σ potential and σ profile of the synthesized ILs.

Studies on –SO3H functionalized Brønsted acidic imidazolium ionic liquids (ILs) for one-pot, two-step synthesis of 2-styrylquinolines

ABSTRACTFour task-specific –SO3H functionalized imidazolium ionic liquids (ILs) were investigated for Brønsted acidities by Hammett functions. After knowing their thermal stabilities, the catalytic activity was observed for the preparation of 2-styrylquinolines by following consecutive Friedländer and Knoevenagel reactions in solvent-free thermal energy. The acidity order ([Dsim][OOCCF3] > [Dsim][OTs] > [Dsim][OOCCl3] > [Msim][OOCCF3]) of three ILs was consistent with their activity order observed in the acid-catalyzed synthesis of 2-styrylquinolines under solvent-free conditions at 90° C, with the exception of [Dsim][OTs]. The best catalytic activity was shown by 25 mol% of [Dsim][OOCCF3] IL. The less acidic IL required 50 mol% to give good yield of 2-styrylquinolines under the optimized condition.

Characterization of Functionalized Imidazolium Ionic Liquids and Their Application in SO2Absorption

Two functionalized imidazolium ionic liquids (ILs) 1-(2-diethylaminoethyl)-3-methylimidazolium thiocyanate (Et2NEMImSCN) and 1-(2-hydroxyethyl)-3-methylimidazolium thiocyanate (HOEMImSCN) were synthesized, their thermal decomposition temperature, density, viscosity, and conductivity were determined, and their efficiency to absorb SO2 was studied. Results showed that both Et2NEMImSCN and HOEMImSCN had high thermal decomposition temperature as most of imidazolium-based ILs, the density and conductivity data of HOEMImSCN were higher than those of Et2NEMImSCN, while the viscosity data of HOEMImSCN were lower than those of Et2NEMImSCN. In the tested temperature range (from 303.15 to 343.15 K), the relationship of temperature and density is consistent with a linear equation, and temperature-dependent viscosity and conductivity was described by a Vogel–Tammann–Fulcher equation. Absorption processes proceeded smoothly in both ILs, and the solubility of SO2 in Et2NEMImSCN was 1.207 gSO2/gIL at 298.15 K and atmosphere pressure, which is the highest capacity reported to date under the similar conditions. Et2NEMImSCN IL could be easily regenerated and reused at least five times with comparable efficiency. A group contribution method based on the literature data was proposed, with an AAD% = 2.07, to assist researchers in predicting the solubility of SO2 in newly designed ILs.

More sustainable electricity generation in hot and dry fuel cells with a novel hybrid membrane of Nafion/nano-silica/hydroxyl ionic liquid

A new hybrid proton exchange membrane (PEM) has been prepared from hydroxyl functionalized imidazolium ionic liquid (IL-OH), Nafion and nano-SiO2. The IL-OH, with a hydroxyl group that acts as both a proton acceptor and donor, forms strong hydrogen bonds with both Nafion and nano-SiO2, resulting in an effective hydrogen bond network in the ternary membrane. Such an anhydrous hydrogen-bond network, which is unknown previously, endows the PEMs with higher proton conductivity, greater thermal stability and surprisingly a more robust mechanical performance than PEMs consisting of conventional ionic liquids. The resulting PEMs have a tensile strength that is more than twice as strong as recast Nafion and an anhydrous ionic conductivity of ∼55mScm−1 at temperatures above 160°C, with a proton transfer number of ∼0.9. A laboratory assembled H2–O2 fuel cell employing this new PEM delivered a power density of 340 and 420mWcm−2 at 160 and 180°C, respectively.