Lewis Acidic Ionic Liquid Research Articles

Brønsted-Lewis acidic ionic liquid for the “one-pot” synthesis of biodiesel from waste oil

Brønsted–Lewis acidic ionic liquids were employed for the preparation of biodiesel using waste oil as the feedstock. It was found that (3–sulfonic acid)–propyltriethylammonium chloroironinate [HO3S–(CH2)3–NEt3]Cl–FeCl3 (molar fraction of FeCl3 x = 0.67) was an efficient catalyst for the reaction, and a synergetic effect of Brønsted and Lewis acid sites enhanced the catalytic performance of ionic liquid (IL). Using the waste oil with 34.6 mg KOH/g acidic value, the yield of biodiesel was even more than 95% at 120 °C for 4 h. The reusability of IL was good after it was used seven times. Therefore, an efficient and environmentally friendly catalyst is provided for the synthesis of biodiesel from waste oil with high acid value by “one-pot” method.

Highly Efficient Oxidative Desulfurization of Fuels by Lewis Acidic Ionic Liquids Based on Iron Chloride

AbstractAcidic ionic liquids (ILs) have been employed as extractant and catalyst in the oxidative desulfurization (ODS) process of fuels in recent years. Several Lewis acidic ionic liquids [C63MPy]Cl/nFeCl3 (molar fraction n = 0.5, 1, 2, 3) and [C6MIM]Cl/FeCl3 were prepared and used to remove the aromatic sulfur compounds dibenzothiophene and benzothiophene from fuels. In the ODS process, the used ILs acted as both extractant and catalyst with 30 wt % hydrogen peroxide aqueous solution as oxidant. The effects of Lewis acidity of ILs, IL's cation structure, molar ratio of O/S, reaction temperature, and different sulfur compounds on the sulfur removal of model oil were investigated. The results indicated that the sulfur removal for dibenzothiophene was affected by Lewis acidity of ILs and nearly reached 100 % by [C63MPy]Cl/FeCl3 at conditions of 298 K, IL/oil mass ratio of 1/3, O/S molar ratio of 4/1, in 20 min. The sulfur removal of real gasoline reached 99.7 % after seven ODS runs in the [C63MPy]Cl/FeCl3‐H2O2 system.

Synthesis and Characterization of Novel Brønsted-Lewis Acidic Ionic Liquids

To meet the demands of some kinds of reactions catalyzed simultaneously by Br?nsted acid and Lewis acid catalyst, two novel Br?nsted-Lewis acidic ionic liquids, 1-carboxyethylene-3-(4-zinc acetate sulfobutyl) imidazolium chloride ([CH3COO-Zn-O3S-bim-CH2CH2COOH]Cl) and 1-(1,2-dicarboxy) ethylene-3-(4-zinc acetate sulfobutyl) imidazolium chloride ([CH3COO-Zn-O3S-bim-C4H5O4]Cl) were synthesized, in which both Br?nsted and Lewis acidic sites existed in the cation. The structures of the ionic liquids were determined by means of FT-IR, 1H NMR and elemental analysis. The results of Py-IR analysis indicated that the two novel ionic liquids have both Br?nsted and Lewis acid properties. The acid strength values (H0) of the ionic liquids were measured utilizing the UV-visible spectroscopy combined with Hammett indicator method, and the acid amount of them was determined by acid-base titration.

Buffered chlorogallate(iii) ionic liquids and electrodeposition of gallium films

Buffering of Lewis acidic chlorometallate ionic liquids is a useful tool to modify their properties for electrochemical and catalytic applications. Lewis acidic chlorogallate(iii) ionic liquids containing the 1-octyl-3-methylimidazolium cation, buffered with sodium chloride, were studied using (71)Ga NMR spectroscopy and cyclic voltammetry. All the studied Lewis acidic compositions (0.50 < χGaCl3 ≤ 0.75) could be buffered to mild or moderate acidity, but not to neutrality. Electrodeposition of gallium from such buffered systems was possible, yielding deposits of improved morphology over the unbuffered ionic liquids, due to the constant melt composition maintained by the buffer. These findings were in a stark contrast with older studies on chloroaluminate(iii) ionic liquids buffered with sodium chloride.

Lewis Acid Ionic Liquid Immobilized on Chitosan for Synthesis of Dichlorophenylphosphine

Lewis Acid Ionic Liquid Immobilized on Chitosan for Synthesis of Dichlorophenylphosphine

Material Characteristics and Corrosion Performance of Heat-Treated Al-Zn Coatings Electrodeposited on AZ91D Magnesium Alloy from an Ionic Liquid

This study examined co-deposition of Al and Zn on active AZ91D magnesium alloy using ionic liquid electrodeposition. A room temperature Lewis acidic ionic liquid made of aluminum chloride (AlCl3) and 1-ethyl-3-methylimidazolium chloride (EMIC) with a mole ratio of 60:40 was used as the bath for pure Al electrodeposition, while the addition of 1 wt% ZnCl2 to this electrolyte was used for co-deposition of Al-Zn on AZ91D magnesium alloy. The material characteristics and corrosion performance of the as-deposited films formed under various deposition charges and those annealed at 200 and 300°C were investigated. The experimental results showed that both pure Al and Al-Zn coatings provided adequate passivity for the AZ91D magnesium alloy. The re-distribution of the chemical composition after heat-treatment, including the formation of intermetallic compounds, gave rise to an increased microhardness and improved passivation behavior of the Al-Zn coated AZ91D magnesium alloy.

Dissolution Process of an Aluminum Anode in Acidic AlCl&lt;sub&gt;3&lt;/sub&gt;-BMIC Ionic Liquid

The dissolution process of an aluminum electrode in Lewis acidic ionic liquid aluminum chloride (AlCl3 )-1-butyl-3-methylimidazolium chloride (BMIC) was studied using linear sweep voltammetry. Passivation was observed upon anodic polarization of the aluminum electrode that was caused by formation of a solid AlCl3 layer on the surface of the aluminum electrode. The electrochemical dissolution process of aluminum can be divided into electrochemically-controlled, transition, and passivation regimes. In the electrochemically-controlled regime, the dissolution rate of aluminum increased with increasing potential. In the transition regime, the dissolution rate of aluminum decreased as the potential increased because of the formation of solid AlCl3 caused by changes in the concentration of AlCl4-and Al2Cl7- . After a passivation layer formed, the dissolution rate of aluminum depended on the diffusion of AlCl4-was independent of potential; that is, the electrochemical dissolution process entered the passivation regime. The anodic limiting current density increased with agitation, increasing temperature, and decreasing mole fraction of AlCl3 in the ionic liquid.

Extractive Deep Desulfurization of Liquid Fuels Using Lewis-Based Ionic Liquids

A new class of green solvents, known as ionic liquids (ILs), has recently been the subject of intensive research on the extractive desulfurization of liquid fuels because of the limitation of traditional hydrodesulfurization method. In present work, eleven Lewis acid ionic liquids were synthesized and employed as promising extractants for deep desulfurization of the liquid fuel containing dibenzothiophene (DBT) to test the desulfurization efficiency. [Bmim]Cl/FeCl3was the most promising ionic liquid and performed the best among studied ionic liquids under the same operating conditions. It can remove dibenzothiophene from the model liquid fuel in the single-stage extraction process with the maximum desulfurization efficiency of 75.6%. It was also found that [Bmim]Cl/FeCl3may be reused without regeneration with considerable extraction efficiency of 47.3%. Huge saving on energy can be achieved if we make use of this ionic liquids behavior in process design, instead of regenerating ionic liquids after every time of extraction.

Density, Viscosity, and Conductivity of Lewis Acidic 1-Butyl- and 1-Hydrogen-3-methylimidazolium Chloroaluminate Ionic Liquids

To promote the development of Lewis acidic chloroaluminate ionic liquids, it is necessary to get a deeper insight into their physicochemical properties and molecular structure. In this work, the densities, viscosities, and conductivities of acidic 1-butyl- and 1-hydrogen-3-methylimidazolium chloroaluminate with different mole fractions of AlCl3 were measured in the temperature range from (293.15 to 343.15) K. Meanwhile, excess molar volume and viscosity deviation values for the binary mixtures of 1-butyl-3-methylimidazolium chloroaluminate ionic liquids were also obtained. All of the experimental data were well-fitted by the empirical equations. Based on the results of density functional theory calculations, the differences in these properties are attributed to the molecular structure, cation–anion interaction, and hydrogen bonds of ionic liquids. It is expected that the present study may be deemed useful for the application of Lewis acidic chloroaluminate ionic liquids in electrochemistry and catalysis.

Epoxy ether cleaving reactions catalyzed by supporting Lewis acidic ionic liquid

Abstract Lewis acidic ionic liquids were used to catalyze the reaction of epoxypropane with POCl 3 . Considering the lower cost and catalytic activities, we concluded that [Et 3 NH]Cl/AlCl 3 was the most attractive ionic liquid from an economical point of view. But it would be easily inactivated because of sensitive to water and air. Moreover, it could not be reused easily because of difficulty recovery in the reaction. However, supporting [Et 3 NH]Cl/AlCl 3 catalyst could resolve above problems. Supporting [Et 3 NH]Cl/AlCl 3 catalyst could be separated by filter easily and reused 5 times in 98% yield. Furthermore, the catalyst was applicable to other epoxy ether cleaving reactions.

Fast oxidative desulfurization of fuel oil using dialkylpyridinium tetrachloroferrates ionic liquids

In this work, a series of Lewis acidic ionic liquids (ILs), dialkylpyridinium tetrachloroferrates [C43MPy] FeCl4,[C83MPy] FeCl4, and [C83MPy] FeCl4), was synthesized and utilized as extractant and catalyst to investigate the oxidative removal of dibenzothiophene (DBT) from model oil, with 30wt% hydrogen peroxide (H2O2) solution as oxidant. The effects of reaction time, temperature, H2O2/DBT molar ratio, initial sulfur content, IL/oil mass ratio, and alkyl chain length of IL cation ring on the DBT removal of model oil were investigated in detail. Dialkylpyridinium tetrachloroferrates ILs presented good catalytic activity and high extraction performance on the desulfurization of model oil, with the advantages of fast reaction equilibrium, high sulfur removal of 100%, low temperature, and low mass ratio of IL/oil. The desulfurization system could be recycled twice without a significant decrease in desulfurization activity. Kinetics of oxidative desulfurization of DBT by H2O2 and [C43MPy] FeCl4 is first-order with an apparent rate constant of 0.9951min−1 at 1/3 IL/oil mass ratio and 298K. [C83MPy] FeCl4 can reduce sulfur content in actual gasoline from 468ppm to 261ppm with a sulfur removal of 44% at IL/gasoline mass ratio of 1/3. The present work shows that fuel oil can be purified into ultralow sulfur fuels through further deep oxidative desulfurization using acidic ILs after hydrodesulfurization.

Ru2Bi14Br4](AlCl4)4by Mobilization and Reorganization of Complex Clusters in Ionic Liquids

Two polymorphs of the new cluster compound [Ru(2)Bi(14)Br(4)](AlCl(4))(4) have been synthesized from Bi(24)Ru(3)Br(20) in the Lewis acidic ionic liquid [BMIM]Cl/AlCl(3) ([BMIM](+) : 1-n-butyl-3-methylimidazolium) at 140 °C. A large fragment of the precursor's structure, namely the [(Bi(8))Ru(Bi(4)Br(4))Ru(Bi(5))](5+) cluster, dissolved as a whole and transformed into a closely related symmetrical [(Bi(5))Ru(Bi(4)Br(4))Ru(Bi(5))](4+) cluster through structural conversion of a coordinating Bi(8)(2+) to a Bi(5)(+) polycation, while the remainder was left intact. Both modifications have monoclinic unit cells that comprise two formula units (α form: P2(1)/n, a=982.8(2), b=1793.2(4), c=1472.0(3) pm, β=109.05(3)°; β form: P2(1)/n, a=1163.8(2), b=1442.7(3), c=1500.7(3), β=97.73(3)°). The [Ru(2)Bi(14)Br(4)](4+) cluster can be regarded as a binuclear inorganic complex of two ruthenium(I) cations that are coordinated by terminal Bi(5)(+) square pyramids and a central Bi(4)Br(4) ring. The presence of a covalent Ru-Ru bond was established by molecular quantum chemical calculations utilizing real-space bonding indicator ELI-D. Structural similarity of the new and parent cluster suggests a structural reorganization or an exchange of the bismuth polycations as mechanisms of cluster formation. In this top-down approach a complex-structured unit formed at high temperature was made available for low-temperature use.

Polystyrene-supported chloroaluminate ionic liquid as a new heterogeneous Lewis acid catalyst for Knoevenagel condensation

Abstract Non-hygroscopic polystyrene-supported chloroaluminate ionic liquid was prepared from the reaction of Merrifield resin with 1-methylimidazole followed by reaction with aluminum chloride. This Lewis acidic ionic liquid is environmentally friendly heterogeneous catalyst for the Knoevenagel condensation of aromatic and aliphatic aldehydes with ethyl cyanoacetate. The catalyst is stable (as a bench top catalyst) and reusable.

Polystyrene-Supported Pyridinium Chloroaluminate Ionic Liquid as a New Heterogeneous Lewis Acid Catalyst for Knoevenagel Condensation

Non-hygroscopic polystyrene-supported chloroaluminate ionic liquid was prepared from the reaction of Merrifield resin with pyridine followed by reaction with aluminium chloride. This Lewis acidic ionic liquid is an environmentally friendly heterogeneous catalyst for the Knoevenagel condensation of aromatic and aliphatic aldehydes with ethyl cyanoacetate. The catalyst is stable (as a bench top catalyst) and can be easily recovered and reused without appreciable change in its efficiency.

Enhanced activity and selectivity in n-octane isomerization using a bifunctional SCILL catalyst

Bifunctional Solid Catalyst with Ionic Liquid Layer (SCILL) systems are presented and applied in the skeleton isomerization of n-octane in a slurry-phase reaction mode. It is demonstrated that Pt on silica, coated with a thin film of acidic chloroaluminate ionic liquid exhibits remarkable catalytic performance under mild conditions in the presence of hydrogen. Interestingly, both selectivity and activity of n-octane isomerization increase in these systems as a function of hydrogen pressure. This does not only suggest a hydrogenation activity of the catalytic Pt-centers embedded in the strongly Lewis acidic ionic liquid but also a significant increase in the proton acidity in this system as a function of the hydrogen pressure.

Electronic Absorption and Voltammetric Analysis of Ni(II) Coordination in the Room Temperature Ionic Liquid: 1-Ethyl-3-Methylimidizolium Chloride/Aluminum Chloride

The coordination chemistry of Ni(II) in the ionic liquid aluminum chloride : 1-ethyl-3-methyl imidazolium chloride (EMIC) has been determined using visible absorption spectrophotometry. By dissolving nickel chloride (NiCl2) in Lewis acidic and basic ionic liquids and observing the resultant spectra and voltammetric information, one can determine the coordination and electron-transfer properties of Ni(II) at the various acidities. The optical data indicate the formation of tetrahedral NiCl42- in the ionic liquid with excess EMIC (basic melt, NAlCl3 < 0.5) with absorption maxima at 659 and 707 nm. In acidic melts (NAlCl3 > 0.5), the wavelength of maximum absorbance shifts to 462 nm. This dramatic change in the visible spectrum is indicative of a change in the coordination of Ni(II) from tetrahedral (basic) to octahedral (acidic) geometry, changes which are mirrored in the cyclic voltammetry data of the same samples. Studies in the neutral melt are also presented here.

Tandem isomerization–lactonization of olefinic fatty acids using the Lewis acidic ionic liquid, choline chloride·2ZnCl2

The tandem isomerization–lactonization of unsaturated fatty acids to their corresponding γ-lactones was carried out for the first time in the presence of a Lewis acidic ionic liquid, choline chloride·2ZnCl2. The ionic liquid initially catalyzes the stepwise migration of the double bond along the carbon chain toward the carboxyl group at the Δ4 position, which subsequently undergoes lactonization resulting in the formation of γ-lactones. This one step process allows the formation of γ-lactone in good yield with little or no formation of δ-lactones. The studied ionic liquid plays the dual role of solvent as well as catalyst.

Deep oxidative desulfurization of diesel fuels by Lewis acidic ionic liquids based on 1-n-butyl-3-methylimidazolium metal chloride

A series of Lewis acidic ionic liquids (ILs) based on 1-n-butyl-3-methylimidazolium metal chloride, i.e., [C4mim]Cl/MCl2 (M=Zn, Fe, Cu, Mg, Sn, Co), are synthesized and used to investigate the oxidative removal of sulfur compounds (S-compounds) from diesel fuels, with ILs serving as both extractant and catalyst and 30wt% H2O2 solution as oxidant. It is observed that metal chloride species affect S-removal, as S-removal efficiency follows the order: [C4mim]Cl/ZnCl2>[C4mim]Cl/FeCl2>[C4mim]Cl/CoCl2>[C4mim]Cl/MgCl2>[C4mim]Cl/CuCl2>[C4mim]Cl/SnCl2. The highly efficient [C4mim]Cl/ZnCl2 is selected to investigate the effects of ZnCl2 content on desulfurization. It is interesting to find out that ZnCl2 content has a significant influence on desulfurization; specifically, 99.9% S-removal is observed for [C4mim]Cl/3ZnCl2 after 3h at 45°C, O/S molar ratio of 8, IL/oil mass ratio of 1/2. [C4mim]Cl/3ZnCl2 then undergoes series of parallel experiments to systematically investigate the influence of factors such as temperature, molar ratio of O/S, mass ratio of IL/oil, and ILs recycling. The incorporation of real diesel fuel into this study demonstrates the efficacy of this IL in desulfurization. This work shows that oxidative desulfurization using Lewis acidic ILs may be a new option for producing cleaner diesel fuels.

Preparation of polystyrene-supported Lewis acidic Fe(III) ionic liquid and its application in catalytic conversion of carbon dioxide

A polystyrene-supported Lewis acidic iron-containing ionic liquid was proved to be recyclable and efficient heterogeneous catalyst for converting CO2 into cyclic carbonate without utilization of any organic solvent or additive. Excellent yields and selectivity were obtained under mild reaction conditions. Notably, the catalyst could be readily recovered and reused over five times without appreciable loss of catalytic activity. A possible catalytic cycle was proposed. The present protocol has successfully been applied to reactions of aziridines/propargyl amines with CO2. This kind of the catalyst presented herein would have great potential in industrial application thanks to its featured advantages.

Facile Synthesis of New Cationic Triphenylphosphine Derivatives and their Use for Propene Dimerization Reactions in Buffered Chloroaluminate Ionic Liquids

AbstractWe describe the facile synthesis of new, cationic triphenylphosphine derivatives containing para‐trimethylammonium substituents. The ionic phosphines were successfully employed in nickel‐catalyzed propene dimerization reactions in highly Lewis acidic chloroaluminate ionic liquids. Buffering of such liquids is achieved by an interaction of the Lewis basic phosphine with the Lewis acidic aluminum centers. The PAl interaction of triarylphosphines and tri‐tert‐butylphosphine with the highly acidic ionic liquid [1‐butyl‐3‐methylimidazolium]+ [Al2Cl7]− was monitored by 31P and 27Al NMR spectroscopy. Coupling of tri‐tert‐butylphosphine with 27Al resulted in an expected but unusual sextet in the 31P NMR spectrum and a doublet in the 27Al NMR spectrum.