- Ionic liquids as advantageous solvents for headspace gas chromatography of compounds with low vapor pressure
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The potential of ionic liquids as solvents for headspace gas chromatography was investigated. Three compounds with boiling points above 200 °C were selected to demonstrate the feasibility of the concept described. 2-Ethylhexanoic acid, formamide, and tri-
- Andre,Loidl,Laus,Schottenberger,Bentivoglio,Wurst,Ongania
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- Molecular states of water in room temperature ionic liquids
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ATR and transmission IR spectroscopy have been used to investigate the state of water in room temperature ionic liquids (RTILs) based on the 1-alkyl-3-methylimidazolium cation with the anions: [PF6]-, [SbF6]-, [
- Cammarata,Kazarian,Salter,Welton
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Read Online
- First ring-opening metathesis polymerization in an ionic liquid. Efficient recycling of a catalyst generated from a cationic ruthenium allenylidene complex
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Ring-opening metathesis polymerization (ROMP) of norbornene was carried out in a biphasic medium (consisting of the ionic liquid [bdmim][PF6] and toluene with a cationic ruthenium allenylidene precatalyst. The ionic liquid contained the rutheni
- Csihony, Szilard,Fischmeister, Cedric,Bruneau, Christian,Horvath, Istvan T.,Dixneuf, Pierre H.
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- Determination of an acidic scale in room temperature ionic liquids
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The acidity scale of different Bronsted acids in ionic liquids such as [BMIM][NTf2], [BMIM][BF4], and [BMMIM][BF4] has been investigated by determination of Hammett functions, using a spectrophotometric indicator method. This scale should permit one to correlate the acidity strength of ionic liquid systems with their ability to achieve acid-catalyzed reactions. Copyright
- Thomazeau, Cecile,Olivier-Bourbigou, Helene,Magna, Lionel,Luts, Stephane,Gilbert, Bernard
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Read Online
- Controlling the reactions of 1-bromogalactose acetate in methanol using ionic liquids as co-solvents
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The reactions of an acetobromogalactose in mixtures of methanol and one of seven different ionic liquids with varying constituent ions were studied. In general, small amounts of ionic liquid in the reaction mixture led to increases in the rate constant compared to methanol, whilst large amounts of ionic liquid led to decreases in the rate constant; this outcome differs significantly from previous reactions proceeding through this mechansim. Temperature dependent kinetic studies indicated that the dominant interaction driving these changes was between the ionic liquid and the transition state of the process. Through considering solvent parameters of ionic liquids, a relationship was found between the changes in the rate constant and both the hydrogen bond accepting ability and polarisability of the solvent, indicating that the interactions affecting reaction outcome are both specific and non-specific in nature; once more, these interactions were different to those observed in previous similar reactions. By changing the amount of ionic liquid in the reaction mixture, additional products not seen in the molecular solvent case were observed, the ratios of which are dependent on the anion of the ionic liquid and the proportion of ionic liquid in the reaction mixture. This demonstrates the importance of considering solvent effects on both the rate and product determining steps and the potential application of such changes is discussed.
- Gilbert, Alyssa,Haines, Ronald S.,Harper, Jason B.
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supporting information
p. 5442 - 5452
(2020/09/09)
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- Correlating ionic liquid solvent effects with solvent parameters for a reaction that proceeds through a xanthylium intermediate
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A unimolecular nucleophilic substitution reaction that proceeds through a xanthylium carbocation was studied in seven ionic liquid solvents. It was found that the general trend in the rate constant with changing proportion of ionic liquid in the reaction mixture was different to that seen for other unimolecular processes, with the rate constant increasing as more ionic liquid was added to the reaction mixture. A significant correlation was found between the natural logarithm of the rate constant and a combination of the Kamlet-Taft solvent parameters. This relationship indicated that the principal interaction involved hydrogen bonding between the ionic liquid and some species along the reaction coordinate. Further, this correlation enables prediction of the effects that other ionic liquids will have on this, and other, reactions that proceed through a similar intermediate.
- Gilbert, Alyssa,Bucher, G?tz,Haines, Ronald S.,Harper, Jason B.
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supporting information
p. 9336 - 9342
(2019/11/13)
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- Binary mixtures of ionic liquids-DMSO as solvents for the dissolution and derivatization of cellulose: Effects of alkyl and alkoxy side chains
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The efficiency of mixtures of ionic liquids (ILs) and molecular solvents in cellulose dissolution and derivatization depends on the structures of both components. We investigated the ILs 1-(1-butyl)-3-methylimidazolium acetate (C4MeImAc) and 1-(2-methoxyethyl)-3-methylimidazolium acetate (C3OMeImAc) and their solutions in dimethyl sulfoxide, DMSO, to assess the effect of presence of an ether linkage in the IL side-chain. Surprisingly, C4MeImAc-DMSO was more efficient than C3OMeImAc-DMSO for the dissolution and acylation of cellulose. We investigated both solvents using rheology, NMR spectroscopy, and solvatochromism. Mixtures of C3OMeImAc-DMSO are more viscous, less basic, and form weaker hydrogen bonds with cellobiose than C4MeImAc-DMSO. We attribute the lower efficiency of C3OMeImAc to “deactivation” of the ether oxygen and C2–H of the imidazolium ring due to intramolecular hydrogen bonding. Using the corresponding ILs with C2–CH3 instead of C2–H, namely, 1-butyl-2,3-dimethylimidazolium acetate (C4Me2ImAc) and 1-(2-methoxyethyl)-2,3-dimethylimidazolium acetate (C3OMe2ImAc) increased the concentration of dissolved cellulose; without noticeable effect on biopolymer reactivity.
- Ferreira, Daniela C.,Oliveira, Mayara L.,Bioni, Thais A.,Nawaz, Haq,King, Alistair W.T.,Kilpel?inen, Ilkka,Hummel, Michael,Sixta, Herbert,El Seoud, Omar A.
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p. 206 - 214
(2019/02/25)
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- Effect of Hydroxyl Groups in a Cation Structure on the Properties of Ionic Liquids
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Two series of imidazolium ionic liquids with the bis(trifluoromethylsulfonyl)imide anion were synthesized, which differ by the presence of a hydroxyl group at the ω-position of the alkyl substituent in the cation structure (nC = 2–8). The properties of the liquids were studied by DSC, TGA, and IR and NMR spectroscopy. Their thermal stability was studied, and the melting points, viscosity, and volatility in vacuum were measured. The effect of OH groups in the structure of the ionic liquid on its properties was evaluated.
- Krasovskiy,Chernikova,Glukhov,Kapustin,Koroteev
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p. 2379 - 2385
(2019/01/03)
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- The impact of ionic liquids on the coordination of anions with solvatochromic copper complexes
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Solvatochromic transition metal (TM)-complexes with weakly associating counter-anions are often used to evaluate traditional neutral solvent and anion coordination ability. However, when employed in ionic liquids (IL) many of the common assumptions made are no longer reliable. This study investigates the coordinating ability of weakly coordinating IL anions in traditional solvents and within IL solvents employing a range of solvatochromic copper complexes. Complexes of the form [Cu(acac)(tmen)][X] (acac = acetylacetonate, tmen = tetramethylethylenediamine) where [X]- = [ClO4]-, Cl-, [NO3]-, [SCN]-, [OTf]-, [NTf2]- and [PF6]- have been synthesised and characterised both experimentally and computationally. ILs based on these anions and imidazolium and pyrrolidinium cations, some of which are functionalised with hydroxyl and nitrile groups, have been examined. IL-anion coordination has been investigated and compared to typical weakly coordinating anions. We have found there is potential for competition at the Cu-centre and cases of anions traditionally assigned as weakly associating that demonstrate a stronger than expected level of coordinating ability within ILs. [Cu(acac)(tmen)][PF6] is shown to contain the least coordinating anion and is established as the most sensitive probe studied here. Using this probe, the donor numbers (DNs) of ILs have been determined. Relative donor ability is further confirmed based on the UV-Vis of a neutral complex, [Cu(sacsac)2] (sacsac = dithioacetylacetone), and DNs evaluated via23Na NMR spectroscopy. We demonstrate that ILs can span a wide donor range, similar in breadth to conventional solvents.
- Kuzmina,Hassan,Patel,Ashworth,Bakis,White,Hunt,Welton
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supporting information
p. 12185 - 12200
(2017/09/25)
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- Rationalising the effects of ionic liquids on a nucleophilic aromatic substitution reaction
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The nucleophilic aromatic substitution reaction between 1-fluoro-2,4-dinitrobenzene and ethanol was examined in a series of ionic liquids across a range of mole fractions. Temperature-dependent kinetic analyses were undertaken to determine the activation parameters for this reaction at the highest mole fraction. As the mole fraction of ionic liquid was increased, the rate constant of the reaction also increased, however the microscopic origin of the rate enhancement was shown to be different between different ionic liquids and also between different solvent compositions. These results indicate a balance between microscopic interactions that result in the observed solvent effects and a qualitative method for analysing such interactions is introduced.
- Hawker, Rebecca R.,Wong, Michaela J.,Haines, Ronald S.,Harper, Jason B.
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supporting information
p. 6433 - 6440
(2017/08/10)
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- Oxidative desulfurization-fluorination reaction promoted by [bdmim][F] for the synthesis of difluorinated methyl ethers
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A new ionic liquid [bdmim][F] has been prepared and fully characterized. Its potential as a fluoride source for the desulfurization-fluorination process has been evaluated with success. The carbon-sulfur double bond of xanthates and thiocarbonates has bee
- Bouvet, Sébastien,Pégot, Bruce,Diter, Patrick,Marrot, Jér?me,Magnier, Emmanuel
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p. 1682 - 1686
(2015/03/14)
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- Desulfurization of hydrocarbons by ionic liquids and preparation of ionic liquids
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The present invention relates to an improved desulfurization process using an ionic liquid compound of general formula C+A?, where C+ represents an organic cation such as alkyl-pyridinium, di-alkyl imidazolium and tri-alkyl imidazolium; and A? is an anion of halides of iron (III), such as, for example, FeCl4?. The desulfurization process is also improved when producing the ionic liquid compound by heating the reactants using microwave energy. The ionic liquids can be used to desulfurize hydrocarbon mixtures by a liquid-liquid extraction.
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Page/Page column
(2014/09/16)
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- Does the cation really matter? the effect of modifying an ionic liquid cation on an SN2 process
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The rate of reaction of a Menschutkin process in a range of ionic liquids with different cations was investigated, with temperature-dependent kinetic data giving access to activation parameters for the process in each solvent. These data, along with molecular dynamics simulations, demonstrate the importance of accessibility of the charged centre on the cation and that the key interactions are of a generalised electrostatic nature. The Royal Society of Chemistry.
- Tanner, Eden E. L.,Yau, Hon Man,Hawker, Rebecca R.,Croft, Anna K.,Harper, Jason B.
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supporting information
p. 6170 - 6175
(2013/09/12)
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- Probing the importance of ionic liquid structure: A general ionic liquid effect on an SNAr process
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The effect of a range of ionic liquids, with systematic variations in the cation and anion, on the rate constant of an aromatic substitution process was investigated. Temperature-dependent kinetic data allowed calculation of activation parameters for the process in each solvent. These data demonstrate a generalised ionic liquid effect, with an increase in rate constant observed in each ionic solvent, though the microscopic origins of the rate constant enhancement differ with the nature of the ionic liquid.
- Tanner, Eden E. L.,Hawker, Rebecca R.,Yau, Hon Man,Croft, Anna K.,Harper, Jason B.
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p. 7516 - 7521
(2013/11/06)
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- Ionic liquid-catalyzed internal redox esterification reaction
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The internal redox esterification of α,β-unsaturated aldehydes and alcohols was carried out using different ionic liquids (ILs) as catalysts and reaction solvents. The basic ionic liquid, 1-butyl-3-methylimidazolium acetate ([bmim]OAc), exhibited the best activity for this reaction. The influences of the amount of ionic liquid catalyst and reaction time on yield of saturated ester have been investigated. The results showed that ionic liquid anions have a crucial effect on the redox esterification of α,β- unsaturated aldehydes and alcohols. The nucleophilic carbenes generated in situ from the ionic liquid cation were believed to be actual active species for this reactions.
- Yu, Yinyin,Hua, Li,Zhu, Wenwen,Shi, Yu,Cao, Ting,Qiao, Yunxiang,Hou, Zhenshan
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p. 1287 - 1298
(2013/03/29)
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- Exploring physicochemical aspects of N-alkylimidazolium based ionic liquids
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Physicochemical aspects (structural, thermodynamic and transport) of 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]), 1-butyl-2,3-dimethylimidazolium tetrafluoroborate ([BDMIM][BF4]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) room temperature ionic liquids (RTILs) are reported. The results based on temperature dependence of surface tension, conductivity, photoluminescence and spectroscopic measurements on RTILs and their mixtures with acetonitrile (ACN) as cosolvent are interpreted in-terms of structure-composition-property relations. The presented observations clearly indicate that a highly structured and organized arrangement of constituents prevails in the investigated RTILs, which is sensitive to temperature variations and cosolvent addition. Thermodynamic and structural parameters estimated from temperature dependency of interfacial tension demonstrate that surface characteristics are dominated by covalent interactions in imidazolium based RTILs. From composition dependence of measured parameters in RTIL-cosolvent mixtures it is shown that ACN mixes nonideally with RTIL, and interestingly the investigated RTILs retain their inherent structural order up to high dilution limits (0.3 volume fraction of RTIL), beyond which these behave as associated electrolytes. The presented findings seem useful for arriving at molecular basis of physicochemical aspects and future applications of RTILs and their binary mixtures especially with cosolvents for biphasic catalysis and heterogeneous electron transfer reactions, wherein temperature elevation and cosolvent addition are currently advocated as operationally simple means to speed up the mass transport.
- Bhat, Mohsin Ahmad,Dutta, Chanmeet K.,Rather, Ghulam Mohammad
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p. 142 - 151
(2013/06/26)
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- Parallel microwave-assisted synthesis of ionic liquids and screening for denitrogenation of straight-run diesel feed by liquid-liquid extraction
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Fifty-six ionic liquids were efficiently synthesized in parallel format under one-pot, solvent-free microwaveassisted synthesis. These compounds were evaluated as extracting agents of nitrogen-containing compounds from a real Diesel feed before being submitted to the hydrodesulfurization process to obtain ultralow sulfur Diesel. Our results showed that halogenated ionic liquids are an excellent alternative due to these ionic liquids are relatively inexpensive, presenting a high selectivity for the extraction of nitrogen-containing compounds and can be regenerated and recycled.
- Ceron, Miguel A.,Guzman-Lucero, Diego J.,Palomeque, Jorge F.,Martinez-Palou, Rafael
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experimental part
p. 427 - 432
(2012/07/01)
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- Ionic liquid-promoted oxidant-free dehydrogenation of alcohols with water-soluble ruthenium nanoparticles in aqueous phase
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An oxidant-free dehydrogenation of alcohols in the aqueous phase was developed for the first time using water-soluble poly(N-vinyl-2-pyrrolidone) (PVP)-stabilized ruthenium nanoparticles with an ionic liquid as a promoter. The present catalytic system was highly efficient and stable for the catalytic dehydrogenation of various alcohols. It was found that the basic ionic liquid 1-n-butyl-2,3-dimethylimidazolium acetate ([BMMIM] OAc) additive played a crucial role in enhancing the catalytic activity and stability of ruthenium(0) nanoparticles. A reaction kinetics study and 1H NMR analysis demonstrated that the basic ionic liquid and ruthenium nanoparticles exerted a synergetic effect for the dehydrogenation reaction. Copyright
- Feng, Bo,Chen, Chen,Yang, Hanmin,Zhao, Xiuge,Hua, Li,Yu, Yinyin,Cao, Ting,Shi, Yu,Hou, Zhenshan
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experimental part
p. 1559 - 1565
(2012/07/17)
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- Hydrophobic Ionic Liquids
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The subject of the invention at hand are novel, a little basic, fluorinated pentafluorophenyl imide anions, which can be used as anions in ionic liquids. Methods for producing ionic liquids are described, which contain these novel pentafluorophenyl imide
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(2009/12/23)
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- Esterification in ionic liquids: The influence of solvent basicity
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(Chemical Equation Presented) The second-order rate constant (k 2) for the esterification of methoxyacetic acid with benzyl alcohol is reported in a range of ionic and molecular solvents. The solvent effects on esterification rate are examined by using a linear solvation energy relationship based on the Kamlet-Taft solvent scales (α, β, and π*). It is shown that the hydrogen bond basicity of the solvent is the dominant parameter in determining the esterification rate and that the best rates are achieved in low basicity solvents.
- Wells, Thomas P.,Hallett, Jason P.,Williams, Charlotte K.,Welton, Tom
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p. 5585 - 5588
(2008/12/20)
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- A rationalization of the solvent effect on the Diels-Alder reaction in ionic liquids using multiparameter linear solvation energy relationships
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The Diels-Alder reaction between cyclopentadiene and three dienophiles (acrolein, methyl acrylate and acrylonitrile) having different hydrogen bond acceptor abilities has been carried out in several ionic liquids and molecular solvents in order to obtain information about the factors affecting reactivity and selectivity. The solvent effects on these reactions are examined using multiparameter linear solvation energy relationships. The collected data provide evidence that the solvent effects are a function of both the solvent and the solute. For a solvent effect to be seen, the solute must have a complimentary character; selectivities and rates are determined by the solvent hydrogen bond donation ability (α) in the reactions of acrolein and methyl acrylate, but not of acrylonitrile. The Royal Society of Chemistry 2008.
- Bini, Riccardo,Chiappe, Cinzia,Mestre, Veronica Llopsis,Pomelli, Christian Silvio,Welton, Thomas
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supporting information; experimental part
p. 2522 - 2529
(2009/02/02)
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- Decolorization of ionic liquids for spectroscopy
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It has been widely recognized that although ionic liquids should be colorless, they are frequently not. Colored samples appear to be pure by most analytical techniques (e.g., NMR spectroscopy, mass spectrometry, HPLC, and ion chromatography), and there have been many attempts to identify the source of color in our own laboratories and others-after 20 years the best that can be said is that the impurities are at a very low level (probably parts per billion) with very high molar extinction coefficients. In this paper, we do not identify these impurities but describe a practical method for removing them for spectrochemical applications. We clearly note that the method is not "green", but we anticipate that it will only be applied to the small volumes of ionic liquids required for fundamental spectroscopic studies in academia but not in industrial processes.
- Earle, Martyn J.,Gordon, Charles M.,Plechkova, Natalia V.,Seddon, Kenneth R.,Welton, Thomas
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p. 758 - 764
(2007/10/03)
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- Increased enantioselectivity and remarkable acceleration of lipase-catalyzed transesterification by using an imidazolium PEG-Alkyl sulfate ionic liquid
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Several types of imidazolium salt ionic liquids were prepared derived from poly(oxyethylene)alkyl sulfate and used as an additive or coating material for lipase-catalyzed transesterification in an organic solvent. A remarkably increased enantioselectivity was obtained when the salt was added at 3-10 mol % versus substrate in the Burkholderia cepacia lipase (lipase PS-C)-catalyzed transesterification of 1-phe nylethanol by using vinyl acetate in diisopropyl ether or a hexane solvent system. In particular, a remarkable acceleration was accomplished by the ionic liquid coating with lipase PS in an iPr2O solvent system while maintaining excellent enantioselectivity; it reached approximately 500- to 1000-fold acceleration for some substrates with excellent enantioselectivity. A similar acceleration was also observed for IL1-coated Candida rugosa lipase. MALDITOF mass spectrometry experiments of the ionic-liquid-coated lipase PS suggest that ionic liquid binds with lipase protein.
- Itoh, Toshiyuki,Matsushita, Yuichi,Abe, Yoshikazu,Han, Shi-Hui,Wada, Shohei,Hayase, Shuichi,Kawatsura, Motoi,Takai, Shigeomi,Morimoto, Minoru,Hirose, Yoshihiko
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p. 9228 - 9237
(2007/10/03)
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- Solvent-solute interactions in ionic liquids
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A range of ionic liquids was studied utilizing the Kamlet-Taft parameters hydrogen bond acidity (α), hydrogen bond basicity (β), and dipolarity/polarizability effects (π*). Some of the ionic liquids studied were methanol, acetonitrile, acetone, dichloromethane, toluene, hexane, and water. π* was high for all the ionic liquids investigated and varied with both anion and cation. α was generally moderate and depended chiefly on the cation. β was also moderate and depended mainly on the anion. Comparison was made with other polarity measurements in ionic liquids.
- Crowhurst, Lorna,Mawdsley, Philip R.,Perez-Arlandis, Juan M.,Salter, Paul A.,Welton, Tom
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p. 2790 - 2794
(2007/10/03)
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- Continuous Flow Hydroformylation of Alkenes in Supercritical Fluid-Ionic Liquid Biphasic Systems
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A process for the hydroformylation of relatively low volatility alkenes (demonstrated for 1-dodecene) in a continuous flow system is described. The catalyst is dissolved in an ionic liquid while the substrate and gaseous reagents are transported into the reactor dissolved in supercritical CO 2, which simultaneously acts as a transport vector for aldehyde products. Decompression of the fluid mixture downstream yields products which are free of both reaction solvent and catalyst. The use of rhodium complexes of triaryl phosphites leads to ligand degradation through reaction of the ionic liquid with water and subsequent attack of the released HF on the phosphite. Sodium salts of sulfonated phosphines are insufficiently soluble in the ionic liquids to obtain acceptable rates, but replacing the sodium by a cation similar to that derived from the ionic liquid, allows good solubility and activity to be obtained. The nature of the ionic liquid is very important in achieving high rates, with 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amides giving the best activity if the alkyl chain is at least C8. Catalyst turnover frequencies as high as 500 h -1 have been observed, with the better rates at higher substrate flow rates. Rhodium leaching into the product stream can be as low as 0.012 ppm, except at low partial pressures of CO/H2, when it is significantly higher. Oxygen impurities in the CO2 feed can lead to oxidation of the phosphine giving higher rates, lower selectivities to the linear aldehyde, increased alkene isomerization and greater leaching of rhodium. However, it is found that under certain process conditions, the supercritical fluid-ionic liquid (SCF-IL) system can be operated continuously for several weeks without any visible sign of catalyst degradation. Comparisons with commercial hydroformylation processes are provided.
- Webb, Paul B.,Sellin, Murielle F.,Kunene, Thulani E.,Williamson, Sylvia,Slawin, Alexandra M. Z.,Cole-Hamilton, David J.
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p. 15577 - 15588
(2007/10/03)
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- Process of telomerizing conjugated dienes
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The present invention is related to a process for telomerizing a conjugated diene which comprises reacting said conjugated diene with a compound containing active hydrogen in the presence of a catalyst system comprising at least one transition metal compound, at least one phosphorus-containing compound, and at least one salt which forms a liquid under the conditions of the telomerization process.
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- Imidazolium salts and the use of these ionic liquids as a solvent and as a catalyst
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New 1,2,3- or 1,2,3,4- or 1,2,3,4,5- substituted imidazolium salts and their uses as solvent in catalyzed organic reactions, as well as compositions containing them and a transition metal compound. They can be used in the following reactions : the telomerisation of conjugated dienes, the dimerisation of olefins, the oligomerisation of olefins, the polymerization of olefins, the alkylation of olefins, the hydrogenation of olefins, the olefin metathesis, the hydroformylation of olefins, the ring-closing metathesis of olefins, the ring-opening metathesis polymerisation of olefins, the symetric or asymetric epoxidation of olefins (including heteroatom substituted olefins) and the cyclopropanation of olefins, the condensation reaction, the hydrogenation reaction, the isomerization reaction, the Suzuki cross-coupling reactions, the amination reaction, the partial oxidation of alkancs, the kinetic resolution of racemic mixtures, the hydrogenation of imines, the hydrogenation of ketones, the transfer hydrogenation and the hydroxylation of aromatic organic compounds.
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- Process of telomerizing conjugated dienes
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The present invention is related to a process for telomerizing a conjugated diene which comprises reacting said conjugated diene with a compound containing active hydrogen in the presence of a catalyst system comprising at least one transition metal compound, at least one phosphorus-containing compound, and at least one salt which forms a liquid under the conditions of the telomerization process.
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