Showing papers on "Ionic liquid published in 1997"
TL;DR: The use of room-temperature chloroaluminate(III) ionic liquids as solvents for clean synthesis and catalytic processes, particularly those applicable to clean technology, is becoming widely recognised and accepted as mentioned in this paper.
Abstract: The use of room-temperature chloroaluminate(III) ionic liquids, specifically 1-butylpyridinium chloride–aluminium(III) chloride and 1-ethyl-3-methylimidazolium chloride–aluminium(III) chloride, as solvents for clean synthesis and catalytic processes, particularly those applicable to clean technology, is becoming widely recognised and accepted. The design principles for room-temperature ionic liquids, some of their properties, and the rationale for using these neoteric solvents, are discussed here, and an indication of the scope of these solvents for future industrial processes is given. © 1997 SCI.
1,952 citations
TL;DR: In this paper, the room temperature ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF{sub 4}) was demonstrated as a versatile electrolyte by examining three representative electrochemical couples: ferrocene and tetrathiafulvalene oxidations and lithium ion reduction.
Abstract: Room temperature molten salts composed of the 1-ethyl-3-methylimidazolium cation and a chloroaluminate anion have received much attention for use in a variety of commercial applications such as batteries, photovoltaics, metal deposition, and capacitors. The room temperature ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF{sub 4}) was demonstrated as a versatile electrolyte by examining three representative electrochemical couples: ferrocene and tetrathiafulvalene oxidations and lithium ion reduction. Square-wave voltammetric data for ferrocene oxidation were fit to a reversible one-electron process using the COOL algorithm to give a half-wave potential of 0.490 V vs. Al/Al(III) and a diffusion coefficient of 5.1 {times} 10{sup {minus}7} cm{sup 2}/s. The two-electron oxidation of tetrathiafulvalene was reversible and proceeded through two consecutive one-electron steps; although data collected at lower square-wave frequencies indicated a slow precipitation of the TTF{sup +} species. Lithium ion was reduced to lithium metal at a Pt electrode following the addition of water to the EMIBF{sub 4} electrolyte, whereas lithium ion reduction at an Al wire produced the {beta}-LiAl alloy. Conductivities and kinematic viscosities of EMIBF{sub 4} were measured from 20 to 100 C and had values of 14 mS/cm and 0.275 cm{sup 2}/s, respectively, at 25 C.
568 citations
TL;DR: In this article, a triflate ionic liquid and polyvinylidene fluoride (PVdF) copolymer were used to produce flexible films with room temperature conductivities ranging from 1.1 to.
Abstract: New rubbery gel electrolytes have been prepared from room temperature ionic liquids and poly(vinylidene fluoride)‐hexafluoropropylene copolymer [PVdF(HFP)]. The ionic liquids employed in these preparations were 1‐ethyl‐3‐methylimidazolium salts of triflate and . When properly processed, the ionic liquid‐PVdF(HFP) gels are freestanding, flexible films with room temperature conductivities ranging from 1.1 to . Because both the ionic liquids and the PVdF(HFP) are nonvolatile and are thermally stable, the gels can be operated at elevated temperatures without performance degradation. An ionic conductivity of was measured for a triflate ionic liquid‐PVdF(HFP) gel at 205°C.
300 citations
TL;DR: In this article, the authors used solvent-free ionic liquids where the source of anodic oxidation may be ascribed to the anion alone, and found that when used in practical capacitors comprising high-surface-area carbon cloth electrodes, a much lower capacitance (compared to smooth electrodes) was achieved.
Abstract: Series-stacked, double-layer carbon capacitors are slated to be used in electric vehicles for power management as well as in consumer electronics for memory backup and burst power. Nonaqueous electrolytes are preferred over aqueous electrolytes, since a wider voltage window can be accessed in the former electrolytes, thereby requiring fewer cells in the series stack. However, it has historically been difficult to assess whether the organic solvent and/or the supporting electrolyte determine the anodic limit. We have eliminated this ambiguity by using solvent-free ionic liquids where the source of anodic oxidation may be ascribed to the anion alone. Even though the new ionic liquids manifested high oxidation limits, we found that when used in practical capacitors comprising high-surface-area carbon cloth electrodes, a much lower capacitance (compared to smooth electrodes) was achieved. To understand whether the observed decrease in capacitance might be due to the microporosity of the carbon cloth electrode or to practical limitation of the device itself. we first measured the differential capacitance (C dl ) at a Hg/1-ethyl-3-methyl imidazolium imide. The integral capacitance at the Hg interface was then calculated and compared with that of a smooth glassy carbon electrode, a carbon yarn, and a cloth electrode. In addition, the effect of (CF 3 SO 2 ) 3 C - , (CF 3 SO 2 ) 2 N - , CF 3 SO 3 - , an BF 4 - on C dl were interpreted based on existing theories of double-layer structure.
279 citations
TL;DR: In this paper, the electrochemical windows of the ionic liquids 1-n-butyl-3-methyl imidazolium tetrafluoroborate (BMI+)(BF4−) and 1 -butyl 3-methylimidazolate hexafluorophosphate (PF6−) have been investigated at platinum, vitreous carbon, tungsten and gold electrodes.
233 citations
TL;DR: The [RuCl2-(S)-BINAP]2NEt3 catalyst precursor dissolved in 1-n-butyl-3-methylimidazolium tetrafluoroborate molten salt is able to hydrogenate 2-arylacrylic acids (aryl=Ph or 6-MeO-naphthyl) with enantioselectivities similar or higher than those obtained in homogeneous media as mentioned in this paper.
Abstract: The [RuCl2-(S)-BINAP]2NEt3 catalyst precursor dissolved in 1-n-butyl-3-methylimidazolium tetrafluoroborate molten salt is able to hydrogenate 2-arylacrylic acids (aryl=Ph or 6-MeO-naphthyl) with enantioselectivities similar or higher than those obtained in homogeneous media Moreover, the hydrogenated products can be quantitatively separated from the reaction mixture and the recovered ionic liquid catalyst solution can be reused several times without any significant changes in the catalytic activity or selectivity
151 citations
TL;DR: In this paper, a novel catalytic membrane for heterogeneous hydrogenation was fabricated by incorporating palladium into a gas-permeable ionic liquid polymer gel composed of======1-n-butyl-3-methylimidazolium hexafluorophosphate and======poly(vinylidene fluoride) copolymer.
133 citations
TL;DR: In this article, the use of 1-butyl-3-methylimidazolium chloro-ethyl-aluminate ionic liquids as solvents for butene oligomerization catalyzed by nickel complexes in a two-phase system is described.
115 citations
TL;DR: In this article, the X-ray crystal structure analysis of [Fe(η5-C5H5)(η6-C6H5C6h4Br)][PF6] is also reported.
Abstract: The ambient temperature ionic liquid system [bmim]Cl–AlCl3 (where [bmim]+ = 1-butyl-3-methylimidazolium cation) has been used to prepare a number of arene(cyclopentadienyl)iron(II) complexes of the type [Fe(C5H5)(arene)]+ from ferrocene. The ionic liquid acts as both solvent and Lewis acid source ([Al2Cl7]–). The products were only formed on addition of a proton source, [bmim][HCl2], confirming mechanistic formulations involving a combination of Lewis and Bronsted acid activity. The X-ray crystal structure analysis of [Fe(η5-C5H5)(η6-C6H5C6H4Br)][PF6] is also reported. The structure clearly shows both π–π stacking interactions between neighbouring cations and hydrogen bonds between the cations and anions.
92 citations
TL;DR: The interaction of RuCl 2 (PPh 3 ) 3 and 1-n-butyl-3-methylimidazolium tetrafluoroborate molten salt yields an air and water stable solution that is able to hydrogenate olefins with turnover frequencies up to 537 h −1 in a typical two-phase catalytic reaction.
78 citations
Patent•
25 Mar 1997
TL;DR: In this article, the problem of obtaining a polymer compound composite material as a slide electrolyte being noncorrosive and stable for a long time and having high ionic conductivity by converting an ionic liquid being a polymeric compound and being an onium salt of a cyclic amidine or pyridine into a solid.
Abstract: PROBLEM TO BE SOLVED: To obtain a polymer compound composite material as a slide electrolyte being noncorrosive and stable for a long time and having high ionic conductivity by converting an ionic liquid being a polymer compound and being an onium salt of a cyclic amidine or pyridine into a solid. SOLUTION: The polymer compound used is desirably a synthetic polymeric compound being an ionic liquid convertible into a solid film or casting. It is exemplified by a polymethacrylate polymer, polyacrylonitrile, polyethylene oxide or an ionene polymer compound. The components of the ionic liquid include a cation of a cyclic amidine of formula I (R 1 and R 3 are each a 1-5C alkyl; R 2 is H or a 1-5C alkyl; and Q is a 2-5C alkylene, an arylene or an alkenylene) or a cation of a pyridine of formula II (R 4 is a 1-6C alkyl; and R 5 is methyl or ethyl) and an anion being at least one organic carboxylic acid such as bis(trifluoromethylsulfonyl)imide acid or perchloric acid. COPYRIGHT: (C)1998,JPO
TL;DR: In this article, the authors studied columnar mesophases of Dithiolium salts with a branched chain and showed that they exhibit the same properties as inverted micelles.
Abstract: Dithiolium salts, with amphipathic character, are compounds of choice for investigations of the influence of an ionic feature upon mesomorphic properties. In this way, salts bearing a branched chain have been studied by SAXS. In spite of their rod-like shape, they exhibit only columnar mesophases, the supramolecular organization of which is close to that of cylindrical inverted micelles. Moreover, the nematic columnar phase, characterized by the loss of lateral positional correlations of the columns themselves, is one of the first examples of such behaviour in the case of thermotropic liquid crystals.
Patent•
27 Mar 1997TL;DR: A low temperature molten ionic liquid composition comprising a mixture of a metal halide and an alkyl-containing amine hydrohalide salt can be used in linear alkbenzene formation as mentioned in this paper.
Abstract: A low temperature molten ionic liquid composition comprising a mixture of a metal halide and an alkyl-containing amine hydrohalide salt can be used in linear alkylbenzene formation. The metal halide is a covalently bonded metal halide which can contain a metal selected from the group comprised of aluminum, gallium, iron, copper, zinc, and indium, and is most preferably aluminum trichloride. The alkyl-containing amine hydrohalide salt may contain up to three alkyl groups, which are preferably lower alkyl, such as methyl and ethyl.
31 Jan 1997
TL;DR: In this paper, a new high temperature NMR probe was utilized for the measurements of the compositional and temperature dependence of the 23Na NMR chemical shift at temperatures up to 1600°C.
Abstract: The coordination environment of the sodium ion in the melts of several simple ionic liquids and an Na2O–Al2O3–SiO2 mixture has been investigated by high temperature 23Na NMR measurements. A new high temperature NMR probe was utilized for the measurements of the compositional and temperature dependence of the 23Na NMR chemical shift at temperatures up to 1600 °C.
23Na NMR spectra of ionic liquids, NaCl, NaBr and NaNO3, show two peaks at their solid to liquid transition, corresponding to the solid and liquid state, respectively. The 23Na NMR peak shift in passing from the liquid to the solid is positive. This suggests a decrease in the coordination number for the molten state compared to the crystalline state. The 23Na peak position for the Na2O–Al2O3–SiO2 melts of the composition range Na/Al≥1 shifted almost linearly in the positive direction as a function of both the increased degree of depolymerization, NBO/T, and [Al]/([Al]+[Si]). 23Na MAS-NMR measurement for crystalline silicate compounds of known structure provided a revised relationship between the mean Na–O distances and 23Na chemical shifts. Comparison of the 23Na chemical shift of the melts with that of crystalline silicate compounds suggests that the coordination number of Na in those melts is around 6–8 with little compositional dependence. The 23Na peak position shifted in the negative direction with increasing temperature for sodium silicates, whereas that of aluminosilicates did not show any temperature dependence. The activation energy from the temperature dependence of the 23Na line width shows little compositional dependence, and the value (51∼58 kJ/mol) was close to that of the trace Na ion diffusion in NaAlSi3O8 glass.
Patent•
01 Aug 1997
TL;DR: In this article, a method of dissolving in an ionic liquid a metal in an initial oxidation state below its maximum oxidation state, characterised in that the Ionic liquid reacts with the metal and oxidises it to a higher oxidation state.
Abstract: A method of dissolving in an ionic liquid a metal in an initial oxidation state below its maximum oxidation state, characterised in that the ionic liquid reacts with the metal and oxidises it to a higher oxidation state. The initial metal may be in the form of a compound thereof and may be irradiated nuclear fuel comprising UO2 and/or PuO2 as well as fission products. The ionic liquid typically is nitrate-based, for example a pyridinium or substituted imidazolium nitrate, and contains a Bronstead or Franklin acid to increase the oxidising power of the nitrate. Suitable acids are HNO3, H2SO4 and [NO+]. Imidazolium nitrates and certain pyridinium nitrates form one aspect of the invention.
TL;DR: In this paper, the synthesis of polyphenylene in a new ionic liquid based on butylpyridinium chloride and mixed alkoxy aluminum chloride AlCl 2 (OC 2 H 5 ) is described.
Patent•
22 Dec 1997TL;DR: In this paper, a method for the purification of ionic polymers was proposed, which can effectively remove low-molecular-weight impurities carrying the same electrostatic charge as that of the ionic polymer, for example, residual ionic monomers.
Abstract: A method for the purification of ionic polymers by which ionic polymers can effectively be freed from low-molecular-weight impurities carrying the same electrostatic charge as that of the ionic polymer, for example, residual ionic monomers. This process is characterized by treating an aqueous solution containing an ionic polymer and low-molecular-weight impurities carrying the same electrostatic charge as that of the ionic polymer, for example, residual ionic monomers by the use of an ultrafiltration membrane or a reverse osmosis membrane under the conditions of an ionic polymer concentration of 7 to 20 % by weight and a charge of the ionic polymer in the aqueous solution of 0.30 gram equivalent/l or above to thereby remove the impurities.
Patent•
21 Jul 1997
TL;DR: In this paper, a novel ionic liquid, which is also useful in other reactions normally catalyzed by previously known ionic liquids, comprises the reaction product of a metal halide, such as aluminum trichloride, and an alkyl-containing amine hydro-halide salt selected from the group consisting of a monoalkyl-, a dialkyl-, a trialkyl-containing AMH salt (such as trimethylamine hydrochloride), and mixtures thereof.
Abstract: Linear alkylbenzene compositions can be made by using, as a catalyst, a low temperature molten ionic liquid composition comprising a mixture of a metal halide and a base and, as the alkylating agent for the benzene reagent, a chloroalkane having an average carbon atom content of more than six, an olefin having an average carbon atom content of more than ten, or a mixture of the chloroalkane and the olefin. A novel ionic liquid, which is also useful in other reactions normally catalyzed by previously known ionic liquids, comprises the reaction product of a metal halide, such as aluminum trichloride, and an alkyl-containing amine hydrohalide salt selected from the group consisting of a monoalkyl-, a dialkyl-, a trialkyl-containing amine hydrohalide salt (such as trimethylamine hydrochloride), and mixtures thereof.
TL;DR: Gutmann acceptor numbers have been determined using (31)P nuclear magnetic resonance (NMR) for AlCl(3)/EMIC melts as well as LiCl, NaCl, and KCl neutral buffered melts.
Abstract: Gutmann acceptor numbers have been determined using 31P nuclear magnetic resonance (NMR) for AlCl3/EMIC melts as well as LiCl, NaCl, and KCl neutral buffered melts. In AlCl3/EMIC melts, where EMIC is 1-ethyl-3-methylimidazolium chloride, the change in Gutmann acceptor number as a function of the AlCl3:EMIC melt ratio is attributed to an equilibrium between a monoadduct of triethylphosphine oxide·AlCl3 and a diadduct of triethylphosphine oxide·2AlCl3. Observed acceptor numbers for the neutral buffered melts appear linear with respect to the melt's initial mole ratio of AlCl3:EMIC prior to buffering. The lithium cation appears to be the most Lewis acidic alkali metal cation followed by the sodium and potassium cations. Possible reasons for the change in acceptor number as a function of changing alkali metal cation concentration are presented.
TL;DR: The use of room-temperature chloroaluminate (III) ionic liquids as solvents for catalytic processes, particularly those applicable to clean technology, is becoming widely recognized and accepted as mentioned in this paper.
Abstract: The use of room-temperature chloroaluminate (III) ionic liquids, specifically 1-butylpyridinium chloride-aluminium (III) chloride and 1-ethyl-3-methylimidazoliurn chloride-aluminium (III) chloride, as solvents for catalytic processes, particularly those applicable to clean technology, is becoming widely recognized and accepted. The rationale for using these solvents is discussed here, and an indication of the scope of these solvents for future industrial processes is given.
TL;DR: In this paper, a room temperature chloroaluminate molten salt, or ionic liquid, has been employed as an effective medium for the reduction carbonylation of Cp 2 TiCl 2.
01 Jan 1997
TL;DR: In this article, the electrochemical windows of the ionic liquids I-n-butyl-3-methyl imidazolium tetrafluoroborate (BMI+)(BF;) and Ibutyl 3-methyl IMidazolate hexafluorophosphate (BHI+)(PF;) have been investigated at platinum, vitreous carbon, tungsten and gold electrodes.
Abstract: The electrochemical windows of the ionic liquids I-n-butyl-3-methyl imidazolium tetrafluoroborate (BMI+)(BF;) and I-butyl-3-methyl imidazolium hexafluorophosphate (BMI+)(PF;) have been investigated at platinum, vitreous carbon, tungsten and gold electrodes. The lowest current densities and widest electrochemical windows were found on tungsten and vitreous carbon 6.10 and 5.45 V for (BMI + )(BF; ) and >7.10 and 6.35 V for (BMI+)(PF;), respectively.
TL;DR: Ionic liquid mediated Friedel-Crafts acylation of the organometallic complex ferrocene can be performed in 1-ethyl-3-methylimidazolium halogenoaluminate melts, as well as in the liquid clathrate formed upon addition of an excess of toluene to EtMeimI-AlCl3 affording solely the monoacylated product acetylcyclopentadienyl (cyclo- pentadienymyl)iron(II) in good to excellent yields under the appropriate conditions as mentioned in this paper.
Abstract: Ionic liquid mediated Friedel–Crafts acylation of the organometallic complex ferrocene can be performed in 1-ethyl-3-methylimidazolium halogenoaluminate melts, EtMeimI–AlCl3, as well as in the liquid clathrate formed upon addition of an excess of toluene to EtMeimI–AlCl3 affording solely the monoacylated product acetylcyclopentadienyl (cyclo- pentadienyl)iron(II) in good to excellent yields under the appropriate conditions.
14 Jan 1997
TL;DR: In this article, the chemical and electrochemical properties of room-temperature molten salt electrolytes are investigated and compared to rechargeable electrodes, including graphite-intercalation electrodes in neutral chloroaluminate and non-chloroaluminate melts, and silane-imidazole polymeric cathodes in acidic chloro-alumininate melts.
Abstract: Room-temperature molten salts possess a number of unique properties that make them ideal battery electrolytes. In particular, they are nonflammable, nonvolatile and chemically inert, and they display wide electrochemical windows, high inherent conductivities and wide thermal operating ranges. Although these ionic liquids have excellent characteristics, the chemical and electrochemical properties of desirable battery electrode materials are not well understood in these electrolytes. The authors research has focused on rechargeable electrodes and has included work on metallic lithium and sodium anodes in buffered neutral chloroaluminate melts, graphite-intercalation electrodes in neutral chloroaluminate and nonchloroaluminate melts and silane-imidazole polymeric cathodes in acidic chloroaluminate melts. This paper provides an overview of their research in these areas.