Basic Ionic Liquid Research Articles

Efficient synthesis of sec-butanol from sec-butyl acetate under mild conditions with the basic ionic liquid catalysts

Three kinds of imidazolide basic ionic liquids were prepared and employed as efficient catalysts for the synthesis of sec-butanol from the transesterification of sec-butyl acetate and methanol. The effect of anions and cations of basic ionic liquids on the catalytic activity were explored, and the relationship between their catalytic activities and basicities was established. Among various of basic ionic liquids, 1-butyl-3-methyl-imidazolium imidazolide ([Bmim]Im) performed better and was chosen for the further studying the influence of experimental conditions. The conversion of sec-butyl acetate reached 90.4% at 60 °C for 60 min under ambient pressure. In addition, the catalyst [Bmim]Im was repeatedly used for five times without noticeable drop in activity and obvious change in chemical structure. The reaction mechanism of the transesterification catalysed by [Bmim]Im was also proposed.

Ionic Liquids as Bifunctional Cosolvents Enhanced CO2 Conversion Catalysed by NADH-Dependent Formate Dehydrogenase

Efficient CO2 conversion by formate dehydrogenase is limited by the low CO2 concentrations that can be reached in traditional buffers. The use of ionic liquids was proposed as a manner to increase CO2 concentration in the reaction system. It has been found, however, that the required cofactor (NADH) heavily degraded during the enzymatic reaction and that acidity was the main reason. Acidity, indeed, resulted in reduction of the conversion of CO2 into formic acid and contributed to overestimate the amount of formic acid produced when the progression of the reaction was followed by a decrease in NADH absorbance (method N). Stability of NADH and the mechanism of NADH degradation was investigated by UV, NMR and by DFT calculations. It was found that by selecting neutral–basic ionic liquids and by adjusting the concentration of the ionic liquid in the buffer, the concentration of NADH can be maintained in the reaction system with little loss. Conversion of CO2 to methanol in BmimBF4 (67.1%) was more than twice as compared with the conversion attained by the enzymatic reaction in phosphate buffer (24.3%).

Transesterification of castor oil using benzimidazolium based Brønsted acid ionic liquid catalyst

In this work, two Brønsted acidic ionic liquid (IL) catalysts containing benzimidazolium and imidazolium cation and two basic IL catalysts, i.e. 3-(2,3-dihydroxypropyl)1-methyl-1H-imidazole-3-ium hydroxide (DFImIL-OH−) and poly(3-benzyl-1-(4-(sec-butyl)benzyl)-1H-benzimidazole-3-iumhydroxide) (PIL(OH−), have been prepared. Developed catalyst was then characterized by NMR and FT-IR spectroscopy, and the acidity of BBAIL and ImBAIL was measured by the Hammett method using 4-nitroaniline as an indicator. Among all synthesized catalysts, benzimidazolium based Brønsted acid ionic liquid catalyst (BBAIL) was found to be best for the transesterification of castor oil in terms of biodiesel yield. Biodiesel yield was found to have affected significantly by castor oil to methanol molar ratio, reaction temperature and catalyst amount. Maximum yield of the biodiesel (i.e. 96%) was obtained using 1:12 M ratio of castor oil to methanol at 40 °C and 5 mol% of the catalyst loading in 14 h. Obtained results indicated that BBAIL could be an efficient catalyst for the synthesis of much-desired biodiesel synthesis. Major highlights of this work are moderate reaction temperature, easy catalyst separation and catalyst recyclability up to 3 cycles with little loss of yield.

Significant effect of 5,10,15,20-meso-tetraarylporphyrinatoiron(III) chloride/triflate and acidic/neutral/basic imidazolium ionic liquids in catalytic oxidation of phenols

The influence of acidic, neutral and basic ionic liquids and their binary mixture with dichloromethane on the reactivity of iron(III)porphyrins was investigated during oxidation of phenols with hydrogen peroxide catalysed by 5,10,15,20-tetraarylporphyrinatoiron(III) chloride and 5,10,15,20-tetraarylporphyrinatoiron(III) triflate. The generation of different intermediates of iron(III) porphyrin in different ILs was studied through viscosity, density, UV–Vis and 1H NMR spectroscopy. The heterolytic cleavage efficiency of (TAP)FeIII-OOH and formation of quinone using iron(III)porphyrin (TAP)FeIIICl with Cl atom as an axial ligand, is influenced by the structure of imidazolium moiety and the counteranion following the order [(CH2)4SO3HMIm]CF3COO>[Hmim]CF3COO>[bmim]TFA»»negligible amount in [bmim]CF3SO3, [Hmim]CF3SO3, [bmim]BF4, [bmim]PF6 and [bmim]Cl. On the other hand, the heterolytic cleavage efficiency of (TAP)FeIII-OOH with iron(III)porphyrin (TAP)FeIIICF3SO3 with triflate as an axial ligand, was found in the following order [(CH2)4SO3HMIm]CF3SO3>[Hmim]CF3SO3>[(CH2)4SO3HMIm]CF3COO>[Hmim]CF3COO>[bmim] CF3COO>[bmim]PF6≈[bmim]BF4≈[bmim]CF3SO3, while epoxidation and polymerization were mainly observed in basic and neutral ILs. The reactive intermediates formed by the reaction of monooxygen donors with (TAP)FeIIICl varied with ILs, as (TAP)+∙FeIV=O intermediate was dominated in acidic ILs, while (TAP)FeIV=O was formed in neutral ILs and (TAP)FeIII-OO– was formed in basic ILs.

Modification of Activated Carbon by the Basic Ionic Liquid [Bmim]OH: A Feasibility Study

AbstractThe large amount of dye wastewater requires efficient techniques, e.g., adsorption by activated carbon (AC), for removal of dyes to decrease water pollution. AC was modified by the basic ionic liquid 1‐butyl‐3‐methylimidazolium hydroxide. The surface functional groups of AC changed evidently as detected by Fourier transform infrared spectroscopy and Boehm titration. To evaluate the influence of functional group change on adsorption performance, AC and modified activated carbon (MAC) were employed to remove methylene blue. The results indicated an increase of adsorbance with lapse of contact time. The adsorption capability of AC was distinctly higher than that of MAC. From kinetic studies it follows that the pseudo‐second‐order kinetic model can well describe the adsorption process.

Basic ionic liquid functionalized magnetically responsive Fe3O4@HKUST-1 composites used for biodiesel production

The main purpose of this present work is to fabricate a magnetically recyclable solid catalyst for the production of biodiesel to meet the demand of green and clean production. To accomplish this, the core–shell structured Fe3O4@HKUST-1 composites with a magnetic core and a porous metal-organic framework shell were fabricated by using a versatile Layer-by-Layer assembly method, and then basic ionic liquids were encapsulated within the core–shell magnetically responsive material, resulting in a solid hybrid base catalyst. Various techniques such as XRD, TEM, FT-IR, VSM and nitrogen adsorption–desorption were employed to characterize the as-prepared solid base catalyst. The characterization results revealed that Fe3O4 nanoparticles were well coated with metal-organic framework HKUST-1 with the formation of core–shell structured nanocomposites, and moreover the basic ionic liquid had been successfully encapsulated within the magnetic nanocomposites. Furthermore, the solid base catalysts possessed superparamagnetic behavior and high saturation magnetization, allowing them to be facilely separated from the reaction mixture by using an external magnetic filed. The solid base catalyst appeared to be an efficient and environmentally benign catalyst for the transesterification of soybean oil with methanol for the production of biodiesel, giving 92.3% oil conversion to methyl esters within 3 h with a catalyst loading of 1.2 wt% and a methanol/oil molar ratio of 30:1 at reflux temperature of methanol. The solid catalyst could be readily recovered by simple magnetic decantation and reused for several times without significant degradation in its catalytic activity.

A numerical approach in describing ionanofluids behavior in laminar and turbulent flow

Ionic liquids are a new class of fluids to be considered for heat transfer due to their remarkable thermophysical properties. Experimental researches on ionic liquids have increased over the last few years and, as an extension, a new class of heat transfer fluids, the ionanofluids were considered in some recent experimental studies. Ionanofluids consists in suspending little amounts of high conductive nanoparticles in ionic liquids. In spite of a lot of inconsistent reports—mainly due to the deficient understanding of the involved mechanisms—ionanofluids have been demonstrated as a new favorable heat transfer fluid. The enhanced thermal conductivity of ionanofluids over the basic ionic liquids is considered one of the driving factors for enhancing convection. Nonetheless, the thermal conductivity is the most studied parameter in spite of the important influence of viscosity variation on the convective flow. This numerical study employed Ansys Fluent commercial code and showed that a correct description of thermophysical properties may make ionanofluids a very promising new heat transfer fluid since the preliminary results are encouraging.

Synthesis of Cyclic Carbonate Catalyzed by DBU Derived Basic Ionic Liquids

In this work, 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU), 1,5‐diazabicyclo[4.3.0]‐5‐nonene (DBN), and imidazole (MIM)‐derived bromide ionic liquids (ILs) were synthesized and used to catalyze the cycloaddition reactions of carbon dioxide (CO2) with several kinds of epoxides to form cyclic carbonates. The DBU derived bromide ionic liquid system was found to have the best catalytic activity among all the tested ILs. The influences of reaction conditions (including temperature, pressure and reaction time) on the reaction of CO2 to propylene oxide (PO) were studied to show the best conditions of 120 °C, 1 MPa, 2.5 h catalyzed by 2 mol% DBU‐derived bromide ionic liquid, with the conversion of PO and the selectivity of propylene carbonate (PC) reaching 99% and 99%, respectively. Under the optimum reaction conditions, the ionic liquid system could be reused at least five times without decrease in selectivity and conversion. NMR spectroscopy and DFT calculations were used to reveal the hydrogen‐bond interaction between ionic liquids and reagent, based on which the reaction mechanism was proposed.

Carbon Dioxide Utilisation for the Synthesis of Unsymmetrical Dialkyl and Cyclic Carbonates Promoted by Basic Ionic Liquids

An efficient and greener synthesis of unsymmetrical organic carbonates mediated by Hünig’s base-appended basic ionic liquids, via carbon dioxide conversion, is described here. These ionic liquids were found to be effective bases for the fixation of carbon dioxide by various alcohols and benzyl bromide, at room temperature. When the alcohol and the halide functionalities are present within the same substrate, the reaction cleanly produces a cyclic carbonate. These functionalised basic ionic liquids were fully recyclable with no loss product yields.

Basic ionic liquid as catalyst and surfactant: green synthesis of quinazolinone in aqueous media.

Basic imidazolium-based ionic liquids not only possess the extraordinary physicochemical properties of ionic liquids, but also have excellent basicity and surfactivity. 1-Propyl-3-alkylimidazole hydroxide ionic liquids ([PRIm][OH]) were synthesized and their catalytic and surfactant behavior were studied in this work. [PRIm][OH] owned excellent surfactivity, and their alkyl chains and ion pairs benefit hydrophobicity and hydrophilicity respectively. The surfactivity of [PRIm][OH] increased with increasing alkyl chain length. [PRIm][OH] showed better catalytic performance than NaOH in the condensation of 2-aminobenzonitrile with cyclohexanone in aqueous medium, and the catalytic performance was well coincident with their surfactant behavior. [PRIm][OH] could decrease the interfacial tension of solvent effectively and form micelles in water. The formed micelles could solubilise more reactants into water and effectively increase the chance of contact between reactants and catalytic active sites. The catalyst dosage obviously affected catalytic performance. The catalytic system is a promising recyclable system.

Basic Ionic Liquid as Catalyst in Synthesis of Dimethyl 4-(2-(2,6-Bis(methoxycarbonyl)pyridine-4-yl)vinyl)pyridine-2,6-dicarboxylate

In the lanthanide complexes with some organic ligands, the use of pyridine-2,6-dicarboxylic acid derivatives as sensitizers was better than using others. In this paper, dimethyl 4-(2-(2,6-bis(methoxycarbonyl)pyridine-4-yl)vinyl)pyridine-2,6-dicarboxylate (DVDPA) was synthesized starting from dimethyl 4-(chloromethyl)pyridine-2,6-dicarboxylate (CMDPA) catalyzed by ionic liquid [bmim]OH. The results indicated that the catalytic system presented the highest catalytic activity in the case of 60°C and 40 min and DVDPA yield of 83% can be obtained when ionic liquid dosage is 10% of reactant. The ionic liquid [bmim]OH can be recycled five times without obviously decreasing the catalytic activity after vacuum drying dehydration and the stability of the yield of DVDPA can be maintained.

Basicity Characterization of Imidazolyl Ionic Liquids and Their Application for Biomass Dissolution

Alkalinity determination is of crucial significance for the applications of basic ionic liquids with imidazolyl. In this work, the ionization constantpKbvalue and acid functionH-values of ionic liquids synthesized were calculated by pH method and UV spectrum-Hammett method. The dissolution ratio of biomass in these ionic liquids was measured at different temperatures. Finally, the relationship between the alkalinity and structure of these ionic liquids was discussed, and the relationship between the alkalinity of ionic liquid and the dissolution mechanism biomass was also discussed. The results show that the basicity of carboxylate ionic liquids is determined mainly by their anions, whereas cations take some finely tuned roles. Furthermore, cations and anions are equally important and are involved in dissolution mechanisms.

Synthesis of gemini basic ionic liquids and their application in anion exchange membranes.

A gemini-type basic morpholine ionic liquid ([Nbmd][OH]) was synthesized via a two-step method with morpholine, bromododecane and 1,4-dibromobutane as raw materials, and its structure was characterized by 1H NMR and FT-IR spectroscopy. Meanwhile, a series of anion exchange membranes ([Nbmd][OH]x–QCS) were prepared with quaternized chitosan (QCS) as the polymer matrix and [Nbmd][OH] as the dopant owing to its strong alkalinity and good solubility. The structures of the [Nbmd][OH]x–QCS composite membranes were characterized in detail by FT-IR spectroscopy, the OH− conductivity by AC impedance spectroscopy, and the morphological features by scanning electron microscopy (SEM), thermal gravity analysis (TGA), etc. The results show that the [Nbmd][OH]x–QCS composite membranes have uniform surfaces and cross-section morphology. Increasing the content of [Nbmd][OH] not only enhances the thermal stability but also increases the OH− conductivity; the thermal decomposition temperature of the [Nbmd][OH]40–QCS membrane is nearly 20 °C higher than that of the pristine QCS membrane, and the maximum OH− conductivity is approximately 1.37 × 10−2 S cm−2 at 70 °C. The methanol permeability of the [Nbmd][OH]40–QCS membrane in 1 M methanol at room temperature is 2.21 × 10−6 cm−2 s−1, which is lower than that of Nafion®115, indicating a promising potential use in alkaline direct methanol fuel cells. Moreover, the [Nbmd][OH]40–QCS membrane exhibits the best alkaline stability of all the membranes prepared in this work, retaining approximately 81% of its initial conductivity after immersion in 3 M KOH solution for 120 h at 70 °C.

A convenient approach for the synthesis of various derivatives of pyrazolo[1,2-b]phthalazinediones in the presence of an efficient supported basic ionic liquid at ambient temperature and solvent-free media

A convenient procedure has been described for one-pot synthesis of various pyrazolo[1,2-b]phthalazinediones at ambient temperature and solvent-free media. First, a novel supported basic ionic liquid ([SiPMIM]OH@MNPs) was prepared and characterized by FT-IR, elemental analysis, VSM, SEM, TEM and XRD. This catalyst exhibits excellent catalytic activity in one-pot reaction of aromatic aldehydes, phthalhydrazide and malononitrile (or acyclic 1,3-dicarbonyl compounds) to offer cyano-, acetyl- or benzoyl-substituted pyrazolo[1,2-b]phthalazinediones in high yields. Moreover, selective synthesis of mono- and bis-pyrazolo[1,2-b]phthalazinediones from dialdehydes was investigated in this approach. The catalyst could be easily separated by an external magnet and reused seven times without any significant loss of activity. An efficient procedure is described for one-pot synthesis of various cyano-, acetyl- or benzoyl-substituted pyrazolo[1,2-b]phthalazinediones in the presence of [SiPMIM]OH@MNPs at ambient temperature and solvent-free media.

Bronsted Basic Ionic Liquid as Catalytic and Reusable Media for Conjugate Cyanation of CF3‐Substituted Alkylidenemalonates Using Acetone Cyanohydrin

AbstractA new class of CF3 substituted alkylidenemalonates were synthesized and used as a substrate for conjugate cyanation reaction. Ionic liquid has been used as an organocatalyst under solvent‐free and mild reaction conditions. The present protocol exhibited remarkable catalytic activity using a favourable cyanide source i. e. acetone cyanohydrin. Excellent yields were obtained for a wide range of substrates and the high reactivity is presumptively attributed to the basicity of an ionic liquid used. Mechanistic insights were studied using NMR spectroscopy and a probable catalytic cycle was proposed.

X-ray Absorption Spectroscopy of Nickel Oxide in 1-Ethyl-3-Methyl Imidazolium Chloride/Aluminum Chloride

Metal chlorides have been examined in situ in ionic liquids (ILs) but the oxides of these metals have not been significantly studied in those ILs. The structure of nickel oxide in the ionic liquid, 1-ethyl-3-methyl imidazolium chloride (EMIC) and aluminum chloride has been investigated in this study. The NiO in EMIC/AlCl3 IL was examined with Extended X-ray Absorption Fine Structure (EXAFS) in both Lewis acidic and basic IL solutions. The EXAFS data for the NiO and anhydrous NiCl2 in these IL solutions are similar, indicating that analogous molecular structures may have formed and these are discussed in detail.

BmIm]OH catalyzed coupling: Green and efficient synthesis of 2,8 dioxacyclopenta [a] inden-3-one derivatives in an aqua media

An efficient recyclable [bmIm]OH catalyzed and aqua mediated eco-compatible synthesis of biologically versatile 2,8 dioxacyclopenta [a] inden-3-one derivatives. Combination of ionic liquid and water has emerged out as a powerful synthetic tool for constructing C–C, C–S and C–O bonds. Disclosed methodology for introducing broad range of 2-iodophenols, 2-iodothiophenols and tetronic acid in basic ionic liquid with predictable high yield will catch the attention of synthetic chemists. This protocol has documented the notable advances and the applications of ionic liquid in heterocyclic synthesis. The chosen strategy illustrates important issues regarding scope, reactivity, product yield, reaction time, reuse and recyclability that will help in designing new synthetic routes for other heterocyclic synthesis.

Selective separation of H2S and CO2 from CH4 by supported ionic liquid membranes

Supported ionic liquid membranes (SILMs) are considered as promising media for the upgrading of natural gas. However, most research has focused on the selective separation of CO2 and CH4, paying little attention to the selective separation of H2S and CH4 or H2S and CO2 in SILMs. In this work, the permeability of CH4, CO2, and H2S in two different categories of ionic liquids (neutral and basic ionic liquids) were systemically investigated under dry conditions. The ideal selectivity of CO2/CH4, H2S/CH4, and H2S/CO2 were calculated. The effect of anion species, transmembrane pressure difference, and temperature on the permeability of single gas and ideal selectivity of gas pairs were studied. It is found that neutral ionic liquids (1-butyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium trifluoromethanesulfonate) show high permeability of CO2 and H2S, and competitive permselectivity of CO2/CH4 and H2S/CH4, and thus can be used for the simultaneous removal of H2S and CO2 from natural gas. Basic ionic liquids (1-butyl-3-methylimidazolium acetate) show not only high permeability of CO2 and H2S, but also superior permselectivity of CO2/CH4, H2S/CH4 and H2S/CO2, and thus can be potentially used for selective removal of H2S from natural gas. Moreover, facilitated transport of H2S and CO2 were observed in 1-butyl-3-methylimidazolium acetate. To the best of our knowledge, this is the first time that the facilitated transport of H2S in SILMs is reported.

Activation and Utilization of CO2 Using Ionic Liquid or Amine-Functionalized Basic Nanocrystalline Zeolites for the Synthesis of Cyclic Carbonates and Quinazoline-2,4(1H,3H)-dione

CO2 was activated and used as a reactant for the preparation of cyclic carbonates and quinazoline-2,4(1H,3H)-dione using functionalized basic nanocrystalline zeolite Nano-ZSM-5 as catalysts. Nano-ZSM-5 was treated with aqueous NH3 solution to prepare basic Nano-ZSM-5. The surface basicity of the basic Nano-ZSM-5 was systematically varied by the surface modification with various amines and basic ionic liquids. Powder X-ray diffraction, N2 adsorption–desorption, scanning/transmission electron microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, 29Si and 13C cross polarized-magic angle spin NMR, elemental analysis, and temperature-programmed desorption techniques were used to characterize the materials. Kinetic (rate constant, activation energy) and thermodynamic parameters (change in enthalpy, free energy, and entropy) were calculated for the cycloaddition reaction of CO2 to epichlorohydrin and 2-aminobenzonitrile by varying the reaction parameters. Basic Nano-ZSM-5 functionalize...

Efficient synthesis of pyrano[2,3-d]pyrimidinone and pyrido[2,3-d]pyrimidine derivatives in presence of novel basic ionic liquid catalyst

A basic ionic liquid, namely 1,1′-(butane-1,4-diyl)bis(1,4-diazabicyclo [2.2.2]octan-1-ium) hydroxide, was prepared and characterized using Fourier-transform infrared spectroscopy, 1 H nuclear magnetic resonance spectroscopy, and pH measurements. The ionic liquid was used for efficient promotion of the synthesis of pyrano[2,3- d ]pyrimidinone and pyrido[2,3- d ]pyrimidine derivatives at room temperature under grinding conditions. A simple procedure, short reaction time, high yields, non-column chromatographic separation, commercial availability of the starting materials, and recyclability of the catalyst are attractive features of this process. 1,1′-(Butane-1,4-diyl)bis(1,4-diazabicyclo[2.2.2]octan-1-ium) hydroxide, which is a basic ionic liquid, efficiently promoted the synthesis of pyrano[2,3- d ]pyrimidinones and pyrido[2,3- d ]pyrimidines at room temperature under grinding conditions.