Sulfate Ionic Liquid Research Articles

Frictional behaviour of imidazolium sulfate ionic liquid additives under mixed slide‐to‐roll conditions: Part 1 — Variation of mixtures with identical weight ratio of ionic liquid additive

AbstractIonic liquids are getting increased attention due to their potential use as additives or lubricants. One of parameters that influence their performance is anion alkyl chain length. Three chain lengths in imidazolium sulfate ionic liquids were varied in three different types of tests in order to study the friction performance in all lubrication regimes at different shear rates. Results show significant effect of alkyl chain length on friction behaviour and surface topography. The shortest chain length ionic liquid had the poorest friction performance whilst longer alkyl chain lengths performed significantly better, which was evidenced by the electrical contact resistance. Although friction behaviour was not generally reduced with ionic liquid mixtures, clear tribological improvement was observed in high shear conditions depending on alkyl chain length. Atomic force microscopy (AFM) analysis revealed correlation between ionic liquid chemistry and surface topography of samples after the experiments, with significantly increased roughness for short chain ionic liquid mixture. Copyright © 2014 John Wiley & Sons, Ltd.

1,1,3,3-Tetramethylguanidinium hydrogen sulphate (TMG·HSO4) ionic liquid in carbon dioxide enriched water: a highly efficient acidic catalytic system for the hydrolysis of cellulose

1,1,3,3-tetramethylguanidinium hydrogen sulphate (TMG·HSO4) ionic liquid was used for the hydrolysis of cellulose using water enriched with carbon dioxide as the reaction media. The addition of carbon dioxide enhanced the reaction rates significantly and afforded glucose and total reducing sugars in 26 and 72% yields, respectively. The addition of carbon dioxide might play a dual role, it reduces the viscosity of the medium for better mass transfer and also reacts with water to give carbonic acid which subsequently dissociates to the hydronium ion and enhances the acidity of the medium. The developed ionic liquid was easily recovered and reused for a subsequent four runs without any significant change in the catalytic efficiency.

An efficient approach for the synthesis of spirooxindole derivatives catalyzed by novel sulfated choline based heteropolyanion at room temperature

A new zwitterionic salt, sulfated choline based heteropolyanion, which was reported earlier by our group, has been found to be very effective for the synthesis of spirooxindole derivatives at room temperature. The heteropolyanion based on sulfated ionic liquid (HIL) showed promising features for the reaction, such as shorter reaction time, high product yields (about 90–95%), simple work up, easy removal, and reusability of the catalyst for several times without significant loss in its efficiency. This has made the protocol sustainable and economic.

3-Methyl-1-sulfonic acid imidazolium hydrogen sulfate-catalyzed three-component, one-pot synthesis of 13-aryl-12H-benzo[f]indeno[1,2-b]quinoline-12-one derivatives

3-Methyl-1-sulfonic acid imidazolium hydrogen sulfate, an efficient, halogen-free, and reusable Bronsted ionic liquid, catalyzed the synthesis of 13-aryl-12H-benzo[f]indeno[1,2-b]quinoline-12-one derivatives by one-pot condensation of 2-naphthylamine, aromatic aldehydes, and 2H-indene-1,3-dione under solvent-free conditions. This method has the advantages of high yields, clean reaction, simplicity, and short reaction time. The catalyst can be recycled and reused four times without significant loss of activity.

Heteropolyanion-based sulfated ionic liquid catalyzed formamides synthesis by grindstone chemistry

A novel heteropolyanion-based sulfated ionic liquid (HIL-[Ch-OSO3H]3W12PO40) was prepared by pairing sulfate functionalized cholinium cation [N,N,N-trimethyl-2-(sulfooxy)ethanaminium] with catalytically active phosphotungstic acid anion (W12PO403−). It was characterized by 1H NMR, FT-IR, EDX, XRD, TGA and elemental analysis. Catalytic activity of thus prepared HIL was studied in N-formylation of amines under solvent-free grinding condition. The methodology provided cleaner conversion over shorter reaction time with high turnover frequency (TOF) and chemoselectivity.

Efficient production of 5-hydroxymethylfurfural through the dehydration of sugars with caprolactam hydrogen sulfate ([CPL]HSO4) ionic liquid catalyst in a water/proprylene glycol monomethyl ether mixed solvent

Efficient production of 5-hydroxymethylfurfural (HMF) through the dehydration of sugars was achieved by developing a new catalyst caprolactam hydrogen sulfate ([CPL]HSO4) ionic liquid or using metal halide as the co-catalyst in a new water/proprylene glycol monomethyl ether solvent system. With an optimum synthesis condition, the yield of HMF derived from fructose dehydration at 105 °C for 90 min is as high as 80.5 % in the presence of [CPL]HSO4. The nature behind the attractive results was revealed by proposing the catalysis mechanism of the fructose dehydration. The yield of HMF is about 70 % using [CPL]HSO4 as the catalyst for fructose dehydration after being reused five times. The catalyst system [CPL]HSO4/metal halide was used for the dehydration of sucrose, and the optimum yield is as high as 64–68 %.

Electrochemical mechanism of Cr(iii) reduction for preparing crystalline chromium coatings based on 1-butyl-3-methylimidazolium hydrogen sulfate ionic liquid

We report a Cr(iii) electrochemical reduction mechanism and nucleation/growth process, and the direct electrodeposition of crystalline chromium coatings based on [BMIM]HSO4.

Analysis of flavonoids by non-aqueous capillary electrophoresis with 1-ethyl-3-methylimidazolium ionic-liquids as background electrolytes

The separation of three flavonoids, kaempferol, quercetin and luteolin, by capillary zone electrophoresis with three 1-ethyl-3-methylimidazolium ionic liquids (ILs), namely chloride, hydrogen sulfate and tetrafluoroborate salts, under non-aqueous conditions using acetonitrile as solvent was investigated. Depending on the IL, the three flavonoids can be separated under positive voltage with a low IL concentration and negative voltage with a high IL concentration. The separations are based on heteroconjungation between the IL anions and the analytes. The heteroconjungation between the anions of the ILs and the analytes is proton sensitive and only a very small amount of protic solvents, such as methanol, added into the electrolyte solution can harm the separation, but higher IL concentrations can overcome this higher amount of protic solvents. Using a high concentration of IL in the sample was used to enhance the flavonoid solubility by as much as 10, overcoming the problem of the low solubility during NACE analysis with ACN as the solvent. Finally, kaempferol, quercetin and luteolin in Semen Plantaginis were analysed by nonaqueous capillary electrophoresis with low concentration of the hydrogen sulfate ionic liquid with excellent results.

Optimization of oleic acid esterification catalyzed by ionic liquid for green biodiesel synthesis

In order to improve the efficiency of biodiesel production from esterification of free fatty acids, an alternative to sulfuric acid has been explored. In this study, esterification of oleic acid was performed using 1-butyl-3-methylimidazolium hydrogen sulfate ([BMIM][HSO4]) ionic liquid for green biodiesel production. Response surface methodology (RSM) based on central composite design (CCD) was employed to study the effect of independent parameters on the process and also for single-objective optimization, while artificial neural network–genetic algorithm (ANN–GA) was utilized to simultaneously optimize the responses of the reaction (methyl oleate yield and oleic acid conversion). From the results, the predicted mathematical models for both methyl oleate yield and oleic acid conversion covered more than 80% of the variability in the experimental data. Furthermore, the linear temperature coefficient was identified as the most influential coefficient towards both responses. Higher responses were predicted for multi-objective optimization using ANN–GA compared to single-objective optimization using RSM. The optimum responses predicted using multi-objective optimization were 81.2% and 80.6% for methyl oleate yield and oleic acid conversion, respectively. The conditions to achieve optimum response were methanol–oleic acid molar ratio of 9:1, catalyst loading (0.06mol), reaction temperature (87°C), and reaction time (5.2h). Furthermore, there was only small decrease in the catalytic activity of the IL after being recycled for five successive runs.

The comparative study on interactions between ionic liquid and CO2/SO2 by a hybrid density functional approach in the gas phase

By using hybrid density functional calculations, we have carried out theoretical studies of the interactions between 1-butyl-3-methylimidazolium methyl sulfate ([BMIM][MeSO4]) ionic liquid and CO2/SO2. The interacting structures between [BMIM][MeSO4] and CO2/SO2 are significantly different. The optimized structure of [BMIM][MeSO4]-CO2 demonstrates that the dominant interaction between CO2 and [BMIM][MeSO4] is LP(O29)→π*(C35O36). While the strong interactions between SO2 and [BMIM][MeSO4] are LP(O36)→σ*(C3H12), LP(O36)→σ*(C4H13), and LP(O28)→π*(S35O37). The most dominant interaction between SO2 and [BMIM][MeSO4] is LP(O28)→π*(S35O37), with the electrons mainly migration from the highest occupied molecular orbital (HOMO) of [MeSO4]− anion to the lowest unoccupied molecular orbital (LUMO) of SO2. The interaction energy between [BMIM][MeSO4] and SO2 is larger than that between [BMIM][MeSO4] and CO2. The imidazolium ring of [BMIM][MeSO4] is more aromatic than that of [BMIM][MeSO4]SO2, but less aromatic than that of [BMIM][MeSO4]CO2. CO2 acts as an electron donor when it interacts with [BMIM][MeSO4], while SO2 is an electron acceptor when it interacts with [BMIM][MeSO4].

Synergetic Activation of Lipase by an Amino Acid with Alkyl–PEG Sulfate Ionic Liquid

Abstract The synergetic effect of amino acids and an ionic liquid, 1-butyl-2,3-dimethylimidazolium α-cetylpolyoxyethylene(10) ether sulfate (IL1), as coating materials on lipase was discovered: coating on lipase PS using a certain amino acid with IL1 was found to be very effective for accelerating the lipase-catalyzed transesterification of secondary alcohols while maintaining perfect enantioselectivity.

Ionic Liquid Mediated Synthesis of Novel tetrahydroimidazo [1,2- a]pyrimidine-6-carboxylate Derivatives

Abstract: A novel route for the synthesis of tetrahydroimidazo [1,2-a] pyrimidine-6-carboxylate derivatives in presence of 1-ethyl-3-methyl imidazolium hydrogen sulphate ionic liquid at room temperature has been reported via Biginelli reac-tion. The process offer several advantages such as short reaction time, excellent yield of products, simple work up proce-dure etc. 1-ethyl-3-methyl imidazolium hydrogen sulphate ionic liquid is utilized as solvent system and catalyst to en-hance the rate of reactions. Keywords: Aromatic aldehydes, Biginelli reaction, Catalyst, Ionic liquid, 5-amino-4,5-dihydro-1 H -pyrazole-4-carbonitrile. INTRODUCTION 3, 4-Dihydropyrimidine-2-(1 H )-ones and their deriva-tives are pharmacologically important because of having several potential biological activities including, antiviral, antibacterial, antitumor and antihypertensive agents. Fur-thermore, these compounds have emerged as the integral backbone of certain calcium channel blockers [1 - 6]. Recently to improve and modify the process, various syn-thetic methodologies for the preparation of such compounds have been developed using microwave irradiation [7-11], by using Lewis and Bronsted acids FeCl

ChemInform Abstract: Facile One‐Pot Synthesis of 5‐Amino‐7‐aryl‐6‐cyano‐4H‐pyrano[3,2‐b]pyrroles Using Supported Hydrogen Sulfate Ionic Liquid.

Twelve new derivatives of 5-amino-7-aryl-6-cyano-4H-pyrano[3,2-b]pyrrole were prepared by one-pot acid-catalyzed cyclocondensation reaction of 3-hydroxypyrrole, malononitrile, and various aldehydes in the presence of the silica-supported ionic liquid 1-methyl-3-(triethoxysilylpropyl)imidazolium hydrogen sulfate as catalyst. The reaction efficiencies were enhanced by moderate electron-withdrawing groups, such Cl and Br, on benzaldehyde, but decreased as substituents became more electron-withdrawing. Among the solvents and catalysts screened for the model reaction, acetonitrile and the silica-supported hydrogen sulfate ionic liquid were found to be the best choices.

Electrical Conductivity of Seven Binary Systems Containing 1-Ethyl-3-methyl Imidazolium Alkyl Sulfate Ionic Liquids with Water or Ethanol at Four Temperatures

We present experimental measurements of specific electrical (or ionic) conductivity of seven binary systems of 1-ethyl-3-methyl imidazolium alkyl sulfate (EMIM-C(n)S) with water or ethanol. Electrical conductivity was measured at 298.15 K in all ranges of concentrations and selected mixtures also at 288.15, 308.15, and 318.15 K. The alkyl chains of the anions used are ethyl (EMIM-ES), butyl (EMIM-BS), hexyl (EMIM-HS), and, only for mixtures with ethanol, octyl (EMIM-OS). Let us note that the four ionic liquids (ILs) measured are miscible in water and ethanol at those temperatures and atmospheric pressure in all ranges of concentrations, but EMIM-OS jellifies for a given range of concentration with water. We compare the measured data in terms of the alkyl chain length and solvent nature. Data are compared with previously scarce results for these same systems and also for other aqueous and ethanol mixtures with ILs. In addition, we verify that our data fit the universal theoretical expression with no fitting parameters given by the pseudolattice-based Bahe-Varela model, except for IL concentrated mixtures. To fit well all ranges of concentrations, we add to the original equation two phenomenological terms with one fitting parameter each. Finally, we calculate the molar conductivity and fit it successfully with an expression derived from Onsager theory.

Solubility of gases in 1-alkyl-3methylimidazolium alkyl sulfate ionic liquids: Experimental determination and modeling

The solubility of different gases (carbon dioxide, methane, ethane, carbon monoxide and hydrogen) in ionic liquids with an alkyl sulfate anion has been modeled with the Group Contribution equation of state developed by Skjold-Jørgensen. New gas solubility measurements have been carried out with a high pressure magnetic suspension balance in order to cover pressure and temperature ranges not considered in previous studies and to obtain more experimental information for the correlation of parameters of the equation of state. New solubility measurements include the solubility of carbon dioxide in 1-ethyl 3-methyl imidazolium ethyl sulfate [emim][EtSO4] at temperatures of 298K and 348K and pressures ranging from 0.3MPa to 6.5MPa, the solubility of methane in [emim][EtSO4] at a temperature of 293K and pressures ranging from 0.2MPa to 10.2MPa, and the solubility of ethane in [emim][EtSO4] at temperatures of 323K and 350K and pressures ranging from 0.2MPa to 4MPa. Results show that the Group Contribution equation of state can be used to describe the solubility of gases in alkyl sulfate ionic liquids as well as infinite dilution coefficients of alkanes in the ionic liquids, with average deviations between experiments and calculations ranging from 1% to 10% in the case of mixtures with CO2, CO, CH4 and H2 with the alkyl sulfate ionic liquids to up to 34% in the case of the solubility of ethane in [emim][EtSO4].

Simple ionic-liquid assisted method for preparation of Cd1-x Zn x S nanoparticles with improved photocatalytic activity

Abstract Nanoparticles of Cd1-x Zn x S (x = 0–0.8) were prepared in neat 1-ethyl-3-methylimidazolium ethyl sulfate, a halide-free and low-cost room-temperature ionic liquid (RTIL) via a simple heating method. The nanoparticles were investigated by means of powder X-ray diffraction, scanning electron microscopy, and UV-Vis diffuse reflectance spectroscopy techniques. The diffraction patterns demonstrate that the prepared nanoparticles in the RTIL have smaller size relative to the samples prepared in water. The photocatalytic activities of the nanoparticles towards photodegradation of methylene blue were evaluated under UV and visible irradiation. The results indicate that the nanoparticles prepared in the RTIL have greater photocatalytic activity relative to the samples prepared in water. The reaction rate constant under visible light irradiation on the nanoparticles prepared in the RTIL is at least six times greater than for the samples prepared in water.

Design calculations of an extractor for aromatic and aliphatic hydrocarbons separation using ionic liquids

AbstractThe study concentrates on the separation of aromatic hydrocarbons from aliphatic hydrocarbon mixtures using ionic liquids as a new alternative of extraction solvents. Influence of the phase equilibrium description accuracy on the separation equipment design using different thermodynamic models was investigated. As a model system, a heptane-toluene binary mixture was chosen, employing 1-ethyl-3-methylimidazolium ethyl sulfate (EMIES) ionic liquid as an extractive solvent. Liquid-liquid equilibrium (LLE) data of the ternary system were calculated using NRTL equations with different quality model parameters. Model 1 corresponds to the NRTL equation with the original binary parameters evaluated independently from the respective binary equilibrium data. Model 2 is represented by an NRTL equation extended by the ternary correction term (with the original binary parameters and ternary correction term parameters evaluated from the ternary tie-lines). Model 3, i.e. the NRTL equation with binary model parameters determined via ternary LLE data regression using ASPEN Plus, was taken from Meindersma et al. (2006). Continuous-flow liquidphase extraction was simulated considering a cascade of mixer-settler type extractors according to the Hunter-Nash scheme (Hunter & Nash, 1934). Based on the simulation results, for a preset separation efficiency criterium, different accuracies of the equilibrium description caused serious discrepancies in the separation equipment design, e.g. in the number of theoretical stages, solvent to feed ratio, and product purity.

Water effect on physicochemical properties of 1-butyl-3-methylimidazolium based ionic liquids with inorganic anions

Room temperature ionic liquids of 1-butyl-3-methylimidazolium tetrafluoroborate, [bmim][BF4], nitrate, [NO3]−, phosphate, [PO4]3−, and hydrogen sulfate, [HSO4]−, have been synthesized and characterized by 1H-NMR, 13C-NMR, mass spectrometry and IR spectroscopy methods. The effect of nature of inorganic anion on hygroscopic property has been studied. Physicochemical properties such as density, viscosity, melting point, freezing point, glass transition, thermal decomposition temperature and specific electrical conductivity have been determined. The influence of temperature and water concentration on density, viscosity and specific electrical conductivity values has been investigated. The dependence of physicochemical properties against anion nature and water content has been explained according to cation–anion interactions. The anomalous behaviors of density or conductivity values for equimolecular aqueous solutions of 1-butyl-3-methylimidazolium hydrogen sulfate or tetrafluoroborate ionic liquids have been found and associated with significant restructuring. The formation of crystalline hydrates of the composition of [bmim][BF4]x0.5H2O was observed.

Densities, speeds of sound, and refractive indices for binary mixtures of 1-butyl-3-methylimidazolium methyl sulphate ionic liquid with alcohols at T = (298.15, 303.15, 308.15, and 313.15) K

Experimental densities, speeds of sound, and refractive indices of the binary mixtures {1-butyl-3-methylimidazolium methylsulphate ([BMIM]+[MeSO4]−)+methanol, or 1-propanol, or 2-propanol, or 1-butanol} were measured over the whole range of composition at T=(298.15, 303.15, 308.15, and 313.15)K. From the experimental data, excess molar volumes, excess isentropic compressibilities, deviation in refractive indices and molar refractions were calculated. The excess molar volumes, change in isentropic compressibilities, and deviation in refractive indices were fitted by the Redlich–Kister smoothing polynomial. The Lorentz–Lorenz equation was applied to correlate the volumetric properties and predict the density or the refractive index of the binary mixtures. Results for these quantities have been discussed in terms of intermolecular interactions between the components of the mixtures. For all the systems studied, the excess molar volume and excess isentropic compressibility are negative, while the change in refractive index on mixing is always positive over the entire composition range and at all temperatures.

Density and Derived Thermodynamic Properties of 1-Ethyl-3-methylimidazolium Alkyl Sulfate Ionic Liquid Binary Mixtures with Water and with Ethanol from 288 K to 318 K

We present in this paper experimental measurements of density for pure ionic liquids of the 1-ethyl-3-methylimidazolium alkyl sulfate family, with the alkyl group being ethyl ([EMIM][ES]), butyl ([EMIM][BS]), hexyl ([EMIM][HS]), and octyl ([EMIM][OS]), and their binary mixtures with water and with ethanol in the whole composition range, at 288 K, 298 K, 308 K, and 318 K and under atmospheric pressure. The IL family chosen allows us to analyze the influence of the alkyl chain length of the anion. We compare results with those previously published by us and by other research groups, where the influence of the alkyl chain length of the cation in volumetric properties is studied. We observed that the density for both kind of binary mixtures decreases with the increase of the alkyl chain length of the anion and with the decrease of the molar fraction of ionic liquid. From density data we extract molar volumes and excess molar volumes. Molar volumes can be adjusted to a straight line versus the molar fraction, and the excess molar volumes values are very small (less than 0.5 % of the molar volume value) for all of the measured systems. This fact allows us to state that these binary systems are quasi ideal from the molar volume point of view. Finally we study the influence of temperature on this property by means of isobaric expansivity, finding very different results depending on the solvent used.