Showing papers on "Ionic liquid published in 2002"
TL;DR: In this paper, the authors demonstrate that cellulose can be dissolved without activation or pretreatment in, and regenerated from, 1-butyl-3-methylimidazolium chloride and other hydrophilic ionic liquids.
Abstract: We report here initial results that demonstrate that cellulose can be dissolved without activation or pretreatment in, and regenerated from, 1-butyl-3-methylimidazolium chloride and other hydrophilic ionic liquids. This may enable the application of ionic liquids as alternatives to environmentally undesirable solvents currently used for dissolution of this important bioresource.
4,276 citations
TL;DR: The advent of water-soluble organometallic complexes, especially those based on sulfonated phosphorus-containing ligands, has enabled various biphasic catalytic reactions to be conducted on an industrial scale and might combine the advantages of both homogeneous and heterogeneous catalysis.
Abstract: For economical and ecological reasons, synthetic chemists are confronted with the increasing obligation of optimizing their synthetic methods. Maximizing efficiency and minimizing costs in the production of molecules and macromolecules constitutes, therefore, one of the most exciting challenges of synthetic chemistry.1-3 The ideal synthesis should produce the desired product in 100% yield and selectivity, in a safe and environmentally acceptable process.4 It is now well recognized that organometallic homogeneous catalysis offers one of the most promising approaches for solving this basic problem.2 Indeed, many of these homogeneous processes occur in high yields and selectivities and under mild reaction conditions. Most importantly, the steric and electronic properties of these catalysts can be tuned by varying the metal center and/or the ligands, thus rendering tailor-made molecular and macromolecular structures accessible.5,6 Despite the fact that various efficient methods, based on organometallic homogeneous catalysis, have been developed over the last 30 years on the laboratory scale, the industrial use of homogeneous catalytic processes is relatively limited.7 The separation of the products from the reaction mixture, the recovery of the catalysts, and the need for organic solvents are the major disadvantages in the homogeneous catalytic process. For these reasons, many homogeneous processes are not used on an industrial scale despite their benefits. Among the various approaches to address these problems, liquidliquid biphasic catalysis (“biphasic catalysis”) has emerged as one of the most important alternatives.6-11 The concept of this system implies that the molecular catalyst is soluble in only one phase whereas the substrates/products remain in the other phase. The reaction can take place in one (or both) of the phases or at the interface. In most cases, the catalyst phase can be reused and the products/substrates are simply removed from the reaction mixture by decantation. Moreover, in these biphasic systems it is possible to extract the primary products during the reaction and thus modulate the product selectivity.12 For a detailed discussion about this and other concepts of homogeneous catalyst immobilization, the reader is referred elsewhere.6,7 These biphasic systems might combine the advantages of both homogeneous (greater catalyst efficiency and mild reaction conditions) and heterogeneous (ease of catalyst recycling and separation of the products) catalysis. The advent of water-soluble organometallic complexes, especially those based on sulfonated phosphorus-containing ligands, has enabled various biphasic catalytic reactions to be conducted on an industrial scale.13-15 However, the use of water as a * Corresponding author. Fax: ++ 55 51 3316 73 04. E-mail: dupont@iq.ufrgs.br. 3667 Chem. Rev. 2002, 102, 3667−3692
3,483 citations
Book•
01 Jan 2002
TL;DR: The early years of Ionic liquid production were covered in this article, where a new generation of soluble supports for Supported Organic Synthesis (SPOS) was proposed. But this support was not applied to the task-specific Ionic liquids.
Abstract: Preface A Note From The Editors THE EARLY YEARS OF IONIC LIQUIDS SYNTHESIS AND PURIFICATION Synthesis Quality Aspects and other Questions Related to Commercial Ionic Liquid Production Synthesis of Task-specific Ionic Liquids PHYSICO-CHEMICAL PROPERTIES Melting Points Viscosity and Density Solubility and Solvation in Ionic Liquids Gas Solubilities Polarity Electrochemistry STRUCTURE AND DYNAMICS Order in the Liquid State and Structure Computational Modelling of Ionic Liquids Translational Diffusion Molecular Reorientational Dynamics ORGANIC SYNTHESIS Ionic Liquids in Organic Synthesis: Effects on Rate and Selectivity Stoicheiometric Organic Reactions and Acid-catalysed Reactions in Ionic Liquids Transition Metal Catalysis in Ionic Liquids Ionic Liquids in Multiphasic Reactions Task Specific Ionic Liquids (TSILs): A New Generation of Soluble Supports for Supported Organic Synthesis (SPOS) Supported Ionic Liquid Phase Catalysts Multiphasic Catalysis Using Ionic Liquids in Combination with Compressed CO2 INORGANIC SYNTHESIS Directed Inorganic and Organometallic Synthesis Making of Inorganic Materials by Electrochemical Methods Ionic Liquids in Material Synthesis: Functional Nanoparticles and Other Inorganic Nanostructures POLYMER SYNTHESIS IN IONIC LIQUIDS BIOCATALYTIC REACTIONS IN IONIC LIQUIDS INDUSTRIAL APPLICATIONS OF IONIC LIQUIDS CONLUDING REMARKS AND OUTLOOK
3,423 citations
TL;DR: A new room temperature ionic liquid incorporating a cation with an appended amine group is produced, comparable in efficiency for CO2 capture to commercial amine sequestering reagents, and yet is nonvolatile and does not require water to function.
Abstract: Reaction of 1-butyl imidazole with 3-bromopropylamine hydrobromide, followed by workup and anion exchange, yields a new room temperature ionic liquid incorporating a cation with an appended amine group. The new ionic liquid reacts reversibly with CO2, reversibly sequestering the gas as a carbamate salt. The new ionic liquid, which can be repeatedly recycled in this role, is comparable in efficiency for CO2 capture to commercial amine sequestering reagents, and yet is nonvolatile and does not require water to function.
2,050 citations
TL;DR: Ionic liquids, defined here as salts with melting temperatures below 100 °C, evolved from traditional high temperature molten salts and were observed as far back as the mid 19th century.
1,456 citations
TL;DR: The new ionic liquids combine the low volatility and ease of separation from product normally associated with solid acid catalysts, with the higher activity and yields normally found using conventional liquid acids.
Abstract: The reaction of triphenylphosphine or N-butylimidazole with cyclic sultones gives zwitterions that are subsequently converted into ionic liquids by reaction with trifluoromethane sulfonic acid or p-toluenesulfonic acid. The resulting ionic liquids have cations to which are tethered alkane sulfonic acid groups. These Bronsted acidic ionic liquids are useful solvent/catalysts for several organic reactions, including Fischer esterification, alcohol dehydrodimerization and the pinacol rearrangement. The new ionic liquids combine the low volatility and ease of separation from product normally associated with solid acid catalysts, with the higher activity and yields normally found using conventional liquid acids.
1,120 citations
TL;DR: π-Conjugated polymers that are electrochemically cycled in ionic liquids have enhanced lifetimes without failure and fast cycle switching speeds and anions such as tetrafluoroborate or hexafluorophosphate showed negligible loss in electroactivity.
Abstract: π-Conjugated polymers that are electrochemically cycled in ionic liquids have enhanced lifetimes without failure (up to 1 million cycles) and fast cycle switching speeds (100 ms). We report results for electrochemical mechanical actuators, electrochromic windows, and numeric displays made from three types of π-conjugated polymers: polyaniline, polypyrrole, and polythiophene. Experiments were performed under ambient conditions, yet the polymers showed negligible loss in electroactivity. These performance advantages were obtained by using environmentally stable, room-temperature ionic liquids composed of 1-butyl-3-methyl imidazolium cations together with anions such as tetrafluoroborate or hexafluorophosphate.
1,092 citations
TL;DR: A review of the potential applications of these unique liquid materials in industrial catalysis can be found in this paper, where the use of room temperature ionic liquids as either solvents or catalysts has been the subject of considerable recent attention.
983 citations
TL;DR: In this paper, the solubility of nine different gases in 1-n-butyl-3-methylimidazolium hexafluorophosphate was investigated.
Abstract: This work presents the solubility of nine different gases in 1-n-butyl-3-methylimidazolium hexafluorophosphate. The gases considered include carbon dioxide, ethylene, ethane, methane, argon, oxygen, carbon monoxide, hydrogen, and nitrogen. We also report the associated Henry's constants and enthalpies and entropies of absorption. We found carbon dioxide to have the highest solubility and strongest interactions with the ionic liquid, followed by ethylene and ethane. Argon and oxygen had very low solubilities and immeasurably weak interactions. Carbon monoxide, hydrogen, and nitrogen all had solubilities below the detection limit of our apparatus. Our results suggest that the mass transfer of gases into ionic liquids likely will be an important issue for reactions involving these gases. We also determined that ionic liquids show good potential for use as a gas-separation medium.
896 citations
TL;DR: The first book devoted to room-temperature ionic liquids is as mentioned in this paper, which is a must for chemists interested in environmental protection, synthesis, catalysis, or the modern chemical industry.
Abstract: The first book devoted to room-temperature ionic liquids, and it is a must for chemists interested in environmental protection, synthesis, catalysis, or the modern chemical industry
882 citations
TL;DR: Ionic liquids have attracted a great deal of attention as possible replacement for conventional molecular solvents for catalytic and organic reactions as discussed by the authors, including acid catalyzed reactions and transition metal catalyzed transformations.
Abstract: Ionic liquids are attracting a great deal of attention as possible replacement for conventional molecular solvents for catalytic and organic reactions. They complete the use of environmentally friendly water, supercritical fluids or perfluorinated solvents. Features that make ionic liquids attractive include their lack of vapor pressure and the great versatility of their chemical and physical properties. By a judicious combination of cations and anions, it is possible to adjust the solvent properties to the requirement of the reactions, thus creating an almost indefinitely set of “designer solvents”. Besides the possibility of recycling the catalytic system, one main potential interest in using ionic liquids results in the unique interactions of these media with the active species and in the possibility to modify the reaction activity and selectivity. Their successful use as solvents has been demonstrated for a wide range of organic reactions including acid catalyzed reactions and transition metal catalyzed transformations.
TL;DR: The new concept of supported ionic liquid catalysis involves the surface of a support material that is modified with a monolayer of covalently attached ionicLiquid fragments that serves as the reaction phase in which a homogeneous hydroformylation catalyst was dissolved.
Abstract: The new concept of supported ionic liquid catalysis involves the surface of a support material that is modified with a monolayer of covalently attached ionic liquid fragments. Treatment of this surface with additional ionic liquid results in the formation of a multiple layer of free ionic liquid on the support. These layers serve as the reaction phase in which a homogeneous hydroformylation catalyst was dissolved. Supported ionic liquid catalysis combines the advantages of ionic liquid media with solid support materials which enables the application of fixed-bed technology and the usage of significantly reduced amounts of the ionic liquid. The concept of supported ionic liquid catalysis has successfully been used for hydroformylation reactions and can be further expanded into other areas of catalysis.
TL;DR: Ir(0) nanoparticles with a mean diameter of 2 nm have been prepared by reduction of Ir(I) dissolved in the ionic liquid with H2 so that this catalytic solution can be reused several times for the biphasic hydrogenation of olefins under mild reaction conditions.
Abstract: 1-n-Butyl-3-methylimidazolium hexafluorophosphate room-temperature ionic liquid is not only suitable as a medium for the preparation and stabilization of iridium nanoparticles but also ideal for the generation of recyclable biphasic catalytic systems for hydrogenation reactions. Thus, Ir(0) nanoparticles with a mean diameter of 2 nm have been prepared by reduction of Ir(I) dissolved in the ionic liquid with H2. This catalytic solution can be reused several times for the biphasic hydrogenation of olefins under mild reaction conditions.
TL;DR: Several ionic liquids appear as an alternative to conventional organic solvents, providing comparable or higher rates and, in some cases, improved enantioselectivity.
TL;DR: In this paper, an all-atom force field is developed using a combination of density functional theory calculations and CHARMM 22 parameter values for the ionic liquid 1-n-butyl-3-methylimidazolium hexafluorophosphate.
Abstract: We report the results of a molecular dynamics study of the ionic liquid 1-n-butyl-3-methylimidazolium hexafluorophosphate [bmim][PF6], a widely studied ionic liquid. An all-atom force field is developed using a combination of density functional theory calculations and CHARMM 22 parameter values. Molecular dynamics simulations are carried out in the isothermal−isobaric ensemble at three different temperatures. Quantities computed include infrared frequencies, molar volumes, volume expansivities, isothermal compressibililties, self-diffusivities, cation−anion exchange rates, rotational dynamics, and radial distribution functions. Computed thermodynamic properties are in good agreement with available experimental values.
TL;DR: In a wider sense, ionic liquids are molten salts that melt below 100 degrees C and give access to a number of elements that cannot be electrodeposited from aqueous solutions, such as the light and refractory metals, as well as elemental and compound semiconductors.
Abstract: In a wider sense, ionic liquids are molten salts that melt below 100 °C. As their name suggests, they are solely composed of ions and many combinations of organic and/or inorganic cations and anions exist. Depending on the systems they can reach electrochemical windows of more than 4 V and thus they give access to a number of elements that cannot be electrodeposited from aqueous solutions, such as the light and refractory metals, as well as elemental and compound semiconductors. Presumably, ionic liquids will become important for electrochemical nanotechnology.
Patent•
03 Jan 2002
TL;DR: The use of conjugated polymers for the fabrication of electrochromic devices incorporating ionic liquids as electrolytes is described in this paper, where the achievement of electroactivity and electrochroism of conjugs in ionic liquid is discussed.
Abstract: Electrochemical synthesis of conjugated polymers in ionic liquids, achievement of electroactivity and electrochroism of conjugated polymers in ionic liquids, and the use of the resulting conjugated polymers for the fabrication of electrochromic devices incorporating ionic liquids (28) as electrolytes are described.
TL;DR: Ionic liquids offer new possibilities for the application of solvent engineering to biocatalytic reactions, and in some cases, remarkable results with respect to yield, (enantio)selectivity or enzyme stability were observed.
TL;DR: While the density and solid-liquid phase transition properties are similar for both series, the new RTILs present a considerably lower viscosity and an increased ability to dissolve HgCl(2) and LaCl(3) (up to 16 times higher).
Abstract: A new series [CnOm mim][X] of imidazolium cation-based room temperature ionic liquids (RTILs), with ether and alcohol functional groups on the alkyl side-chain has been prepared. Some physical properties of these RTILs were measured, namely solubility in common solvents, viscosity and density. The solubility of LiCl, HgCl2 and LaCl3 in room temperature ionic liquids was also determined. The features of the solid–liquid phase transition were analysed, namely the glass transition temperature and the heat capacity jump associated with the transition from the non-equilibrium glass to the metastable supercooled liquid. These properties were compared with those reported for the 1-n-alkyl-3-methylimidazolium [Cn mim][X] series. While the density and solid–liquid phase transition properties are similar for both series, the new RTILs present a considerably lower viscosity and an increased ability to dissolve HgCl2 and LaCl3 (up to 16 times higher).
TL;DR: In this paper, a series of low-cost ionic liquids containing methyl and ethyl-sulfate anions can be easily and efficiently prepared under ambient conditions by the reaction of 1-alkylimidazoles with dimethyl sulfate and diethyl sulfate.
TL;DR: An ionic liquid polymer gel containing 1-methyl-3-propylimidazolium iodide (MPII) and poly(vinylidenefluoride-cohexafluoropropylene) (PVDF-HFP) has been employed as quasi-solid state electrolyte in dye-sensitized nanocrystalline TiO2 solar cells with an overall conversion efficiency of 5.3% at AM 1.5 illumination as mentioned in this paper.
TL;DR: Overall, the thiourea- and urea-derivatized cations yielded the highest distribution ratios, and those for Hg2+ were higher than those for Cd2+; however, a change in aqueous-phase pH does not promote the stripping of metal ions from the extracting phase.
Abstract: A series of hydrophobic task-specific ionic liquids designed to extract Hg2+ and Cd2+ from water were prepared by appending urea-, thiourea-, and thioether-substituted alkyl groups to imidazoles and combining the resulting cationic species with PF6-. The new ionic liquids were characterized and investigated for their metal ion extraction capabilities. When used in liquid/liquid extraction of Hg2+ and Cd2+ from aqueous solutions, the metal ion distribution ratios increased several orders of magnitude, regardless of whether the ionic liquids were used as the sole extracting phase or doped into a series of [1-alkyl-3-methylimidazolium][PF6] (alkyl = n-C4-C8) ionic liquids to form a 1:1 solution. In the 1:1 mixtures, as the length of the alkyl chain increased from butyl to hexyl to octyl, the metal ion distribution ratios increased. Increasing the ratio TSIL/[C4mim][PF6] resulted in higher distribution ratios for both Hg2+ and Cd2+. Overall, the thiourea- and urea-derivatized cations yielded the highest distribution ratios, and those for Hg2+ were higher than those for Cd2+; however, a change in aqueous-phase pH does not promote the stripping of metal ions from the extracting phase. The combination of these imidazolium cations and PF6- produced ionic liquids with decreased thermal stability in comparison to [C(n)mim]-[PF6]. Gaussian98 restricted Hartree-Fock geometry optimizations for one of the thiourea-appended cations shows the charge delocalization around the ring and suggests that the thiourea group may aid in deprotonating the imidazolium ring and may be responsible for the lowered thermal stability of these cations.
TL;DR: In this paper, a series of twenty four 1-alkyl(aralkyl)-3-methylimidazolium hexafluorophosphates and bis(trifluoromethyl-sulfonyl)imides are prepared and the influence of structural variations in the imidazolate cation and the identity of the anion on physical properties (phase transition, density, viscosity, and surface tension) of the ionic liquids is determined.
Abstract: A series of twenty four 1-alkyl(aralkyl)-3-methylimidazolium hexafluorophosphates and bis(trifluoromethyl-sulfonyl)imides are prepared and the influence of structural variations in the imidazolium cation and the identity of the anion on physical properties (phase transition, density, viscosity, and surface tension) of the ionic liquids is determined.
TL;DR: New families of quaternary ammonium, 1-methyl-3-alkylimidazolium dicyanamide (dca, N(CN)2−) anion are reported in this paper.
TL;DR: In this article, the volume expansivities and isothermal compressibilities of four room-temperature ionic liquids and 1-methylimidazole at temperatures between 298.2 and 343.2 K and pressures to 206.9 MPa were reported.
Abstract: From ambient- and high-pressure density measurements, we report the volume expansivities and isothermal compressibilities of four room-temperature ionic liquids and 1-methylimidazole at temperatures between 298.2 and 343.2 K and pressures to 206.9 MPa. The compounds studied are 1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim][PF6]), 1-octyl-3-methylimidazolium hexafluorophosphate ([C8mim][PF6]), 1-octyl-3-methylimidazolium tetrafluoroborate ([C8mim][BF4]), and N-butylpyridinium tetrafluoroborate ([NBuPy][BF4]). The density is affected by the natures of the anion, cation, and substituents on the cation, with lower densities observed for longer alkyl chains. Density decreases fairly linearly with increasing temperature but at a rate less than that for molecular organic compounds. In addition, the high-pressure measurements reveal that ionic liquids are significantly less compressible than organic solvents, with isothermal compressibility values similar to that of water. The high-pressure density dat...
TL;DR: In this paper, the authors present a halogen-free and relatively hydrolysis-stable ionic liquid, 1-n-butyl-3-methylimidazolium ([bmim]) [n-C8H17OSO3].
TL;DR: A short summary of possible methods for the preparation of immobilised ionic liquids (ILs) is presented in this article, where the differences in the resulting heterogeneous catalysts are discussed and examples for the use of these catalysts in organic reactions are given.
TL;DR: In this article, the selectivities at infinite dilution ( = / ) for the separation of aliphatics from aromatics and n-hexane from 1-hexene are presented and discussed.
Abstract: Activity coefficients at infinite dilution have been measured with the dilutor technique for 20 solutes (alkanes, alkenes, cyclic hydrocarbons, aromatic hydrocarbons, ketones, alcohols, and water) in the ionic liquids 1-methyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, and 1-ethyl-3-methylimidazolium ethylsulfate. The measurements were carried out in the temperature range between 293.15 K and 333.15 K. The selectivities at infinite dilution ( = / ) for the separation of aliphatics from aromatics and n-hexane from 1-hexene are presented and discussed. From the results it can be concluded that the ionic liquids investigated show different advantages compared to those of the entrainers actually used for the separation of aliphatic from aromatic hydrocarbons by extractive distillation or extraction.
Journal Article•