Imidazolium Hydroxide Research Articles

CO2 absorption characteristics of amino group functionalized imidazolium-based amino acid ionic liquids

In this study, dual amino group functionalized imidazolium amino acid ionic liquids (AAILs) were synthesized from imidazole, bromoalkylamine, and amino acids. 1-(3-aminopropyl)-3-(2-aminoethyl)imidazolium hydroxide ([Apaeim][OH]), 1-propyl-3-(2-aminoethyl)imidazolium hydroxide ([Paeim][OH]), and 1-ethyl-3-(2-aminoethyl)imidazolium hydroxide ([Eaeim][OH]) were synthesized in two-steps, while [Apaeim][amino acid], [Paeim][amino acid], and [Eaeim][amino acid] were synthesized in three-steps. The structures of the synthesized AAILs were confirmed by 1H NMR analysis. Moreover, the CO2 absorption mechanism of [Apaeim][OH] was confirmed by FT-IR and 13C NMR analyses. Subsequently, CO2 absorption-desorption tests were conducted under at 15 vol% CO2, 313 K and atmospheric pressure. The cation and anion effects on the ionic liquid absorbents were also investigated. Among the tested ionic liquid solutions, 30 wt% [Apaeim][OH] and 30 wt% 1-(3-aminopropyl)-3-(2-aminoethyl)imidazolium alaninate ([Apaeim][ala]) displayed the best performances. Thus, both presented CO2 cyclic capacities 2.2-fold higher than that of the benchmark CO2 absorbent 30 wt% monoethanolamine (MEA), while their viscosities were comparable to that of 30 wt% MEA. Notably, 30 wt% [Apaeim][ala] show great potential as a CO2 absorbent due to its high CO2 cyclic capacity and low viscosity.

Mesomorphic glass-forming ionic complexes composed of a cholesterol phthalate and 1-Cn-3-methylimidazolium: phase transition and enthalpy relaxation behavior

Ionic complexes consisting of a mesogenic cholesterol derivative and 1-alkyl (Cn)-3-methylimidazolium (CnMim) (n = 6–18) were prepared from ethanol solutions containing an equimolar mixture of cholesterol hydrogen phthalate (CHP) and 1-Cn-3-methylimidazolium hydroxide; the imidazolium hydroxide was obtained by anion exchange of 1-Cn-3-methylimidazolium bromide. The complex samples, termed [CnMim][CHP], were examined to evaluate their thermal transition patterns. Excluding the two samples (n = 6, 8) that showed no definite ordered phase, the complexes with n ≥ 10 formed a cholesteric (n = 10, 12) or smectic (n = 14–18) mesophase in a considerably wide range of temperatures; this wide range reflects the additional thermotropic property of the salts of CnMim with longer alkyl chains. These fluid mesophases transformed into a mesomorphic vitreous solid without crystallization in a usual cooling process. For the glassy mesomorphic samples of selected complexes (n = 10, 18), the enthalpy relaxation behavior was followed as a function of the aging temperature and time, and the data were analyzed in terms of a Kohlrausch–Williams–Watts (KWW) type of stretched exponential equation. A very narrow distribution of relaxation times was observed for the “liquid crystalline glasses”, indicating the high uniformity of the relaxation mode. We prepared a series of ionic complexes, [CnMim][CHP] (n = 6–18), by neutralizing cholesterol hydrogen phthalate (CHP) with 1-alkyl (Cn)-3-methylimidazolium hydroxide ([CnMim][OH]) derived from [CnMim][Br]. The complexes of n ≥ 10 formed a thermotropic mesophase in each individual temperature range and solidified into a mesomorphic glass upon cooling, although two samples of n = 6 and 8 showed no ordered structure. Enthalpy relaxation behavior of the mesomorphic glasses (n = 10, 18) was also examined as a function of the aging temperature and time

An Improved Procedure for the Three-Component Synthesis of 1H-Pyrazolo[1,2-B]Phthalazine-5,10-Dione Derivatives Using Basic Ionic Liquid

An efficient and green method for the synthesis of 1 H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives has been achieved through the one-pot, three-component condensation of aromatic aldehydes, malononitrile or ethyl cyanoacetate, and phthalhydrazide in the presence of 1-butyl-3-methyl imidazolium hydroxide ([bmim]OH) as catalyst in EtOH. This reaction does not involve any hazardous organic solvent and toxic catalyst. The ionic liquid can be recovered and recycled for subsequent reactions. Moreover, this protocol has the advantages of easy work-up, short reaction time, mild reaction conditions and environmentally benign procedures compared with the reported methods.

Preparation and Characterization of Tetra-Imidazolium Hydroxide Polyphenylene Membranes via Nickel Catalyzed C–C Coupling Polymerization

Imidazolium hydroxide anion exchange membranes functionalized with conjugated tetraphenylethylene moieties were synthesized via Ni(0) catalyzed polymerization by sequential chloromethylation, substitution with imidazoliums and ion exchange. Moreover, with their pendant benzoyl groups the copolymers showed high molecular weight, durability, thermo-oxidative stability, high solubility in polar aprotic solvents and strong chemical and thermal stability in comparison to alkyl quaternary ammonium-functionalized polymers. The proposed polymer membranes, without ether linkages, demonstrated improved performance in ion exchange capacity, water uptake, ion conductivity, and thermal stability. The polymer membranes were studied by 1H-NMR (Nuclear Magnetic Resonance) spectroscopy, thermogravimetric analysis, water uptake, ion exchange capacity and ion conductivity. Surface morphologies were assessed by atomic force microscope (AFM). The synthesized polymers may have applications as fuel cell membranes because of their excellent ion conductivity.

Solvent-free, four-component synthesis of 3,4,7,8-tetrahydro-3,3-dimethyl-11-aryl-2H-pyridazino[1,2-a]indazole-1,6,9(11H)-triones; using 1-butyl-3-methylimidazolium hydroxide ([bmim]OH) as a green and reusable catalyst

A series of 3,4,7,8-tetrahydro-3,3-dimethyl-11-aryl-2H-pyridazino[1,2-a]indazole-1,6,9(11H)-trione derivatives have been synthesized via one-pot, four-component reaction in the presence of 3-methyl-1-butyl imidazolium hydroxide as an efficient catalyst. A broad range of structurally diverse aldehydes (aromatic aldehydes bearing electron withdrawing and electron releasing groups) was applied successfully, and corresponding products were obtained in good to excellent yields without any by-product. The catalyst was stable during the reaction process and could also be reused several times with consistent activity.

Bmim]OH: An efficient catalyst for the synthesis of mono and bis spirooxindole derivatives in ethanol at room temperature

A rapid and efficient, one pot synthesis of spirooxindole derivatives has been attempted by three-component reaction of isatin, malononitrile and carbonyl compound possessing a reactive α-methylene group by using task specific ionic liquid, 1-butyl-3-methyl imidazolium hydroxide [bmim]OH as a catalyst. The important features of this methodology are straight forward route in short reaction time at room temperature and avoid any hazardous organic solvent, toxic catalyst, tedious purification step. Interestingly, this protocol is not only limited to mono-systems but also to the synthesis of newer bis-spirooxindole system. The separation of the product and reusability of the catalyst are easy with excellent yield. The [bmim]OH catalyst system could be reused up to five recycles without appreciable loss of activity.

An efficient synthesis of quinazoline-2,4(1H,3H)-dione from CO2 and 2-aminobenzonitrile using [Hmim]OH/SiO2 as a base functionalized Supported Ionic Liquid Phase Catalyst

A simple base functionalized Supported Ionic Liquid Phase Catalyst using 1-hexyl-3-methyl imidazolium hydroxide ionic liquid supported on silica, ([Hmim]OH/SiO2) was used as an efficient, heterogeneous catalyst for the synthesis of quinazoline-2,4(1H,3H)-diones motif through the carboxylative coupling of CO2 with 2-aminobenzonitriles. The reactions give good to excellent yield under optimized reaction condition. The catalyst, [Hmim]OH/SiO2, was synthesized by physical adsorption phenomenon and was characterized by different techniques such as FT-IR and BET (Brunauer–Emmett–Teller) surface area analysis. The influences of different reaction parameters such as catalyst loading, reaction time, solvent, temperature and pressure on the reaction system were investigated. The developed methodology described a simple one step approach for the synthesis of a wide variety of substituted quinazoline-2,4(1H,3H)-diones with excellent yield of a desired products. Furthermore, the catalytic system was found to be recyclable up to four consecutive cycles with marginal decrease in yield after third recycle.

Novel and Efficient Route for the Synthesis of 2-(N,N-dimethyl)amino-4-amino-6-aryl-1,3,5-triazines and 2,4-diamino-6-aryl-1,3,5-triazines catalysed by ionic liquid (IL) 1-butyl-3-methyl imidazolium hydroxide [bmim][OH

Novel and Efficient Route for the Synthesis of 2-(<i>N</i>,<i>N</i>-dimethyl)amino-4-amino-6-aryl-1,3,5-triazines and 2,4-diamino-6-aryl-1,3,5-triazines catalysed by ionic liquid (IL) 1-butyl-3-methyl imidazolium hydroxide [bmim][OH

Self-Aggregation of New Alkylcarboxylate-Based Anionic Surface Active Ionic Liquids: Experimental and Theoretical Investigations

Halogen-free and low-cost alkylcarboxylate-based anionic surface active ionic liquids (SAILs), namely, 1-butyl-3-methylimidazolium alkylcarboxylates ([C4mim][C(n)H(2n-1)O2], n = 8, 10, 12), were first synthesized through the neutralization of imidazolium hydroxide by alkylcarboxylic acids. A systematic study of their self-aggregation behavior in water was investigated by surface tension, electrical conductivity, steady-state fluorescence quenching, and (1)H NMR. The micellar properties of this series of SAILs in ethylammonium nitrate (EAN) were also studied by surface tensiometry for comparison. A set of surface active parameters and thermodynamic parameters of these compounds in water and EAN was obtained. Surface tension results show that the surface activity of [C4mim][C(n)H(2n-1)O2] in EAN is inferior to that in water. They exhibit a higher ability to aggregate in water than the traditional anionic surfactants, sodium alkylcarboxylates (SAC), and anionic SAILs, 1-butyl-3-methylimidazolium alkylsulfates ([C4mim][C(n)H(2n+1)SO4]) with the same hydrocarbon chain length. This demonstrates that the incorporation of carboxylate group and [C4mim](+) cation favors micelle formation. To understand the discrepancy in the surface activity of alkylsulfate- and alkylcarboxylate-based SAILs, theoretical calculations were performed to give electrostatic potential of the corresponding anions. The higher surface activity of [C4mim][C12H23O2] mainly originates from the lower electronegativity of its anion. Density functional theory (DFT) calculations manifest that the interaction energy of binary combination SAILs-EAN is larger than that of SAILs-H2O, implying the stronger interaction of the former. Consequently, it is more difficult for [C4mim][C(n)H(2n-1)O2] to self-aggregate in EAN than in H2O. This work is expected to be of practical value for the environmentally friendly alkylcarboxylate-based SAILs in some potential applications, including nanomaterials synthesis and phase separation, among others.

Green Biodiesel Production Catalyzed by Basic Ionic Liquid

Transesterification were carried out under microwave irradiation conditions and the effects of imidazolium hydroxide with different branched alkyl side-chains ([Cnmim]OH, n = 2, 3, 4) were investigated. The results showed that less than conventional amount of NaOH, and the alkaline ionic liquids formed clearly biphasic systems immediately after the transesterification of soybean oil with methanol was finished. The method offers significant improvement over conventional techniques in terms of operational simplicity, processing time reduction and excellent yields. Among the imidazolium salts studied, [C2mim]OH proved to be the most efficient catalyst, affording 96 % yield.

Ion and water transport in functionalized PEEK membranes

Water sorption, water transport and ion transport are compared for polyether–ether ketone polymers functionalized with sulfonic acid, quaternary amine hydroxide, and imidazolium hydroxide. Water sorption in all three ionomers increases modestly with increasing water activity up to aw=0.6 and then increases more rapidly between 0.6<aw<1.0. Ionic conductivity in all three ionomers is negligible for aw<0.6; ionic conductivity increases exponentially with increasing water activity for aw>0.6. The increase in ion conductivity with increasing water activity is 10 times greater for the proton exchanged polymer compared to the hydroxide exchanged polymers. Water permeation from partially saturated vapor streams is primarily diffusion limited for all three ionomers and the permeation rates were approximately the same. Water pervaporation from liquid water appeared to be interfacial transport limited for membranes<120μm thick; the pervaporation rates at 40 and 60°C were independent of membrane thickness. Water sorption and transport show little dependence on the mobile ion while the ion transport appears to depend on both ion size and hydrophilicity of the fixed ion.

One-step synthesis of α,β-unsaturated arylsulfones by a novel multicomponent reaction of aromatic aldehydes, chloroacetonitrile, benzenesulfinic acid sodium salt

A new and green method for the synthesis of α,β-unsaturated arylsulfones had been achieved through the condensation of aromatic aldehydes, chloroacetonitrile, benzenesulfinic acid sodium salt in the presence of 1-butyl-3-methyl imidazolium hydroxide ([bmim]OH) in EtOH under reflux. The ionic liquid was recovered and recycled for subsequent reactions. The advantages of this protocol were non-toxic, easy work-up and good yields.

Efficient and Green Approaches for the Synthesis of 4H-Benzo[g]chromenes in Water, Under Neat Conditions, and Using Task-Specific Ionic Liquid

Facile and convenient procedures have been described for the synthesis of 4H-benzo[g]chromenes by one-pot condensation of aromatic aldehydes, malononitrile/ethyl cyanoacetate, and 2-hydroxy-1,4-naphthoquinone. The reaction has been accomplished using catalytic cetyltrimethylammonium bromide (CTAB) in water under reflux or under neat conditions at 110 °C. A task-specific ionic liquid, 1-butyl-3-methyl imidazolium hydroxide ([bmim]OH), has also been found to be an effective catalyst for this transformation. The protocols prove to be environmentally benign and offer advantages of good yields, short reaction times, and simple workup procedures. The ionic liquid could be recycled and reused for up to four runs without appreciable loss in the activity.

ChemInform Abstract: An Improved Procedure for the Three‐Component Synthesis of Benzo[g]chromene Derivatives Using Basic Ionic Liquid.

A basic ionic liquid, 1-butyl-3-methyl imidazolium hydroxide ([bmim]OH), efficiently promotes a one-pot, three-component condensation of aromatic aldehydes, malononitrile or ethyl cyanoacetate, and 2-hydroxy-1,4-naphthoquinone to produce 4-aryl-5,10-dihydro-4H-benzo[g]chromene-5,10-dione derivatives in high yields at room temperature. This reaction does not involve any hazardous organic solvent and toxic catalyst. The ionic liquid is recovered and recycled for subsequent reactions. Moreover, this protocol has the advantages of easy work-up, short reaction time, high yields, and environmentally benign procedure compared with the reported methods. J. Heterocyclic Chem., (2011).

Basic ionic liquid/FeCl3·6H2O as an efficient catalyst for AGET ATRP of methyl methacrylate

AbstractA basic ionic liquid, 1‐butyl‐3‐methyl imidazolium hydroxide ([Bmim]OH), was synthesized and used as the additives in an iron‐mediated atom transfer radical polymerization with activators generated by electron transfer (AGET ATRP) of methyl methacrylate in bulk and solution, using FeCl3·6H2O as the catalyst, ethyl 2‐bromoisobutyrate as the initiator, vitamin C (Vc) as the reducing agent, and tetrabutylammonium bromide or tetra‐n‐butylphosphonium bromide as the ligand. Catalytic amount of [Bmim]OH could enhance the polymerization rate and produce poly(methyl methacrylate) with controllable molecular weights and narrow molecular weight distributions (Mw/Mn = 1.3–1.4). The nature of controlled/“living” free radical polymerization in the presence of basic ionic liquid was further confirmed by chain‐extension experiments. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Basic ionic liquids: a new type of ligand and catalyst for the AGET ATRP of methyl methacrylate

Imidazolium-type basic ionic liquids (BILs), including 1-butyl-3-methyl imidazolium hydroxide ([Bmim][OH]), 1-butyl-3-methyl imidazolium phosphate ([Bmim][PO4]), 1-butyl-3-methyl imidazolium carbonate ([Bmim][CO3]), and 1-butyl-3-methyl imidazolium bicarbonate ([Bmim][HCO3]), coordinated by iron chloride (FeCl3·6H2O), were used as both the ligand and catalyst in activators generated by the electron transfer ATRP (AGET ATRP) of methyl methacrylate (MMA) in bulk and solution, without the use of traditional ligands (such as 2,2-bipyridine, tetrabutylammonium bromide, and tetra-n-butylphosphonium bromide). Catalytic amounts of BILs could enhance the initiator efficiency (0.87–0.91) and the polymerization rate, and produce PMMA with controllable molecular weights and narrow molecular weight distributions (Mw/Mn = 1.20–1.40). The nature of the controlled/“living” free radical polymerization in the presence of BILs was confirmed by chain-extension experiments. The ready solubility and availability of BILs enable them to be applied as a new type of ligand and catalyst in iron-mediated AGET ATRP.

A computational study on the chemical fixation of carbon dioxide with 2-aminobenzonitrile catalyzed by 1-butyl-3-methyl imidazolium hydroxide ionic liquids

The mechanism of chemical fixation of carbon dioxide with 2-aminobenzonitrile catalyzed by 1-butyl-3-methyl imidazolium hydroxide ([Bmim]OH) ionic liquid has been extensively investigated by the density functional theory (DFT) calculations. The purpose is to show the detailed reaction mechanism, and in particular to better understand the role of [Bmim]OH played in the reaction as a catalyst. Three mechanistic pathways are proposed and evaluated. Our calculations indicate that the real activate catalyst is the N-heterocyclic carbine (NHC). In the favored pathway, it is found that the attack of C3 atom of NHC to C1 atom, the C1–O2 bond cleavage, and the C1–N2 bond formation have close activation free energies. Therefore, each of them can determine the reaction rate with variation in the reaction conditions. Furthermore, it is shown that the scCO 2 solution does not change significantly the potential energy surface profile.

An improved procedure for the three‐component synthesis of benzo[g]chromene derivatives using basic ionic liquid

AbstractA basic ionic liquid, 1‐butyl‐3‐methyl imidazolium hydroxide ([bmim]OH), efficiently promotes a one‐pot, three‐component condensation of aromatic aldehydes, malononitrile or ethyl cyanoacetate, and 2‐hydroxy‐1,4‐naphthoquinone to produce 4‐aryl‐5,10‐dihydro‐4H‐benzo[g]chromene‐5,10‐dione derivatives in high yields at room temperature. This reaction does not involve any hazardous organic solvent and toxic catalyst. The ionic liquid is recovered and recycled for subsequent reactions. Moreover, this protocol has the advantages of easy work‐up, short reaction time, high yields, and environmentally benign procedure compared with the reported methods. J. Heterocyclic Chem., (2011).

ChemInform Abstract: A Fast, Highly Efficient and Green Protocol for Michael Addition of Active Methylene Compounds to Styrylisoxazoles Using Task‐Specific Basic Ionic Liquid [bmIm]OH as Catalyst and Green Solvent.

A fast, highly efficient and green protocol for the Michael addition of active methylene compounds to styrylisoxazoles at room temperature has been investigated using task-specific basic ionic liquid, 3-butyl-1-methyl imidazolium hydroxide, [bmIm]OH, as a catalyst and green reaction medium. The reactions proceeded with excellent yields in short reaction times. The strategy is quite general and works with a variety of active methylene compounds. The ionic liquid can be recycled for subsequent reactions with consistent activity. Keyword s: Active methylene compounds, styrylisoxazole, nitroisoxazole, Michael addition, task-specific basic ionic liquid [bmIm]OH

Solvent-Free &lt;i&gt;N&lt;/i&gt;-Alkylation of Phthalimide Catalyzed by Basic Ionic Liquids

Solvent-freeN-alkylation of phthalimide with alkyl halides catalyzed by basic ionic liquids was developed in this conmmunication. With a comparative study, [Bmim]OH (1-butyl-3-methyl imidazolium hydroxide) exhibited the highest catalytic activity among the selected basic ionic liquids, which afforded a convenient, efficient and general protocol forN-alkyl phthalimides exclusively.