651
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Zhang Y, Tu X, Liu W, Wang H. Diffusion dynamics of ionic liquids during the coagulation of solution spinning for acrylic fibers. POLYM ENG SCI 2007. [DOI: 10.1002/pen.20951] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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652
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Izgorodina EI, Forsyth M, MacFarlane DR. Towards a Better Understanding of 'Delocalized Charge' in Ionic Liquid Anions. Aust J Chem 2007. [DOI: 10.1071/ch06304] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
One of the main characteristics that are attributed to ionic liquids (especially those with a low melting point) is that the anions comprising the ionic liquids possess a certain degree of charge delocalization as compared to anions in traditional molten salts. Based on the proton affinity equilibrium we proposed a new energetic criterion that can be used as a measure of charge delocalization. The proposed proton affinity comparison quantifies the extent to which ionic liquid anions are delocalized. Thus it should lead to a better understanding towards the design of task-specific ionic liquids. Therefore, this criterion can be applied to newly designed anions to assure that the extent of charge delocalization falls within the same range of values on the proton affinity scale as other commonly used ionic liquid anions.
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653
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López-Pastor M, Domínguez-Vidal A, Ayora-Cañada MJ, Laurell T, Valcárcel M, Lendl B. Containerless reaction monitoring in ionic liquids by means of Raman microspectroscopy. LAB ON A CHIP 2007; 7:126-32. [PMID: 17180215 DOI: 10.1039/b608618g] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Reaction monitoring by Raman microspectroscopy in levitated room temperature ionic liquid (RTIL) droplets is reported. Due to their non-volatility, RTIL droplets are well-suited to act as wall-less microreactors. The droplets were produced by a piezoelectric flow-through microdispenser connected to an automated flow injection system and were levitated by an acoustic trap. Taking advantage of the flow system versatility, the sequence of reagents was easily changed to study a model organic reaction: the Knoevenagel condensation. The reaction was followed by Raman microspectrometry and the obtained spectra were analysed using multivariate curve resolution to retrieve the concentration profiles and pure spectra of reactants, intermediates and products involved in the reaction. In addition, information about solvation interactions was obtained by monitoring the desolvation process taking place when a volatile co-solvent evaporated from the droplet.
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Affiliation(s)
- Mercedes López-Pastor
- Department of Analytical Chemistry, University of Cordoba, Campus de Rabanales, Marie Curie Annex Building, E-14071, Córdoba, Spain
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654
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D. Headley A, R. S. Saibabu Kotti S, Ni B. Solvation Effects on Imidazolium Salts That Contain Alkyl Side Chains. HETEROCYCLES 2007. [DOI: 10.3987/com-06-10960] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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655
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Ding Y, Xiong R, Wang S, Zhang X. Aggregative structure of the 1-octadecyl-3-methylimidazolium cation in the interlayer of montmorillonite and its effect on polypropylene melt intercalation. ACTA ACUST UNITED AC 2007. [DOI: 10.1002/polb.21145] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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656
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Wang YY, Li W, Xu CD, Dai LY. Preparation and Characterization of a Novel Benzimidazolium Brønsted Acid Ionic Liquid and Its Application in the Synthesis of Arylic Esters. CHINESE J CHEM 2007. [DOI: 10.1002/cjoc.200790019] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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657
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Bini R, Bortolini O, Chiappe C, Pieraccini D, Siciliano T. Development of Cation/Anion “Interaction” Scales for Ionic Liquids through ESI-MS Measurements. J Phys Chem B 2006; 111:598-604. [PMID: 17228918 DOI: 10.1021/jp0663199] [Citation(s) in RCA: 164] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Electrospray ionization mass spectrometry applied to ionic liquids allowed the study of loosely bonded supramolecules, originating from these organic salts. Based on the observation that ionic liquids formed cationic [C(q+1)X(q)](+) and anionic [C(q)X(q+1)](-) supramolecular aggregates, we have investigated mixed networks, formed by different cations coordinated to a selected anion or by different anions bonded to a given cation, i.e., [C1...X...C2](+) and [X1...C...X2](-), with the aim to build a scale of the cation-anion interaction strength. The qualitative order of intrinsic bond strength to Br- was found to be the following: [emim](+) > [bmim](+) > [mor1,2](+) > [hmim]+ > [omim](+) > [mor1,4](+) > [bupy](+) > [bpyrr](+) > [picol](+) > [bm(2)im](+) > [TBA](+). Similarly, the interaction energies to 1-butyl-3-methylimidazolium (bmim) species envisaged two classes of anions: species tightly coordinated to the cationic moiety that include CF3COO(-), Br(-), N(CN)2(-), and BF4(-) and anions loosely interacting with the alkylimidazolium species such as OTf(-), PF6(-), and Tf2N(-).
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Affiliation(s)
- Riccardo Bini
- Dipartimento di Chimica Bioorganica e Biofarmacia, via Bonanno 33, 56126 Pisa, Italy
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658
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Ni B, Zhang Q, Headley AD. Design and Synthesis of Pyridinium Chiral Ionic Liquids Tethered to a Urea Functionality. J Org Chem 2006; 71:9857-60. [PMID: 17168608 DOI: 10.1021/jo0613232] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nine chiral room-temperature ionic liquids (RTILs), which contain a chiral moiety and a urea functionality bonded to a pyridinium ring, have been designed and synthesized. The synthesis of these ionic liquids is concise and practical due to the commercial availability of the starting materials. These novel RTILs were readily prepared from 2-(aminomethyl)pyridine and amino acid ester derived isocyanates. We envision that these new chiral RTILs can serve as effective reaction media as well as chiral catalysts for asymmetric reactions, which are presently being investigated in our laboratory.
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Affiliation(s)
- Bukuo Ni
- Department of Chemistry, Texas A&M University-Commerce, Commerce, Texas 75429-3011, USA
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659
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Mikkola JP, Wärnå J, Virtanen P, Salmi T. Effect of Internal Diffusion in Supported Ionic Liquid Catalysts: Interaction with Kinetics. Ind Eng Chem Res 2006. [DOI: 10.1021/ie061082o] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jyri-Pekka Mikkola
- Laboratory of Industrial Chemistry, Process Chemistry Centre, Åbo Akademi University, Biskopsgatan 8, FI-20500 Åbo-Turku, Finland
| | - Johan Wärnå
- Laboratory of Industrial Chemistry, Process Chemistry Centre, Åbo Akademi University, Biskopsgatan 8, FI-20500 Åbo-Turku, Finland
| | - Pasi Virtanen
- Laboratory of Industrial Chemistry, Process Chemistry Centre, Åbo Akademi University, Biskopsgatan 8, FI-20500 Åbo-Turku, Finland
| | - Tapio Salmi
- Laboratory of Industrial Chemistry, Process Chemistry Centre, Åbo Akademi University, Biskopsgatan 8, FI-20500 Åbo-Turku, Finland
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660
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D'Anna F, Frenna V, Noto R, Pace V, Spinelli D. Room Temperature Ionic Liquids Structure and its Effect on the Mononuclear Rearrangement of Heterocycles: An Approach Using Thermodynamic Parameters. J Org Chem 2006; 71:9637-42. [PMID: 17168580 DOI: 10.1021/jo0615549] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The kinetics of the rearrangement of the Z-phenylhydrazone of 3-benzoyl-5-phenyl-1,2,4-oxadiazole (1) into the relevant 4-benzoylamino-2,5-diphenyl-1,2,3-triazole (2) induced by amines have been studied in five room-temperature ionic liquids (RTILs) at different temperatures. The kinetic data collected show that both cationic and anionic parts of RTILs significantly influence the reactivity of the title reaction. The calculated activation parameters allow us to advance hypotheses about the weak interactions operating in RTIL solutions.
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Affiliation(s)
- Francesca D'Anna
- Dipartimento di Chimica Organica E. Paterno, Università degli Studi di Palermo, Viale delle Scienze, Parco d'Orleans 2, 90128 Palermo, Italy.
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661
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Raman spectroscopic study of base catalyzed di- and trimerization of malononitrile in ionic liquids and water. J Mol Struct 2006. [DOI: 10.1016/j.molstruc.2006.03.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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662
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Daguenet C, Dyson PJ. Switching the Mechanism of Catalyst Activation by Ionic Liquids. Organometallics 2006. [DOI: 10.1021/om060728+] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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663
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Crowhurst L, Falcone R, Lancaster NL, Llopis-Mestre V, Welton T. Using Kamlet−Taft Solvent Descriptors To Explain the Reactivity of Anionic Nucleophiles in Ionic Liquids. J Org Chem 2006; 71:8847-53. [PMID: 17081015 DOI: 10.1021/jo0615302] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this paper, we report the effect of ionic liquids on substitution reactions using a variety of anionic nucleophiles. We have combined new studies of the reactivity of polyatomic anions, acetate, trifuoroacetate, cyanide, and thiocyanide, with our previous studies of the halides in [C4C1py][Tf2N], [C4C1py][TfO], and [C4C1im][Tf2N] (where [C4C1im]+ is 1-butyl-3-methylimidazolium and [C4C1py]+ is 1-butyl-1-methylpyrrolidinium) and compared their reactivities, k2, to the same reactions in the molecular solvents dichloromethane, dimethylsulfoxide, and methanol. The Kamlet-Taft solvent descriptors (alpha, beta, pi) have been used to analyze the rates of the reactions, which were found to have a strong inverse dependency on the alpha value of the solvent. This result is attributed to the ability of the solvent to hydrogen bond to the nucleophile, so reducing its reactivity. The Eyring activation parameters (DeltaH++ and DeltaS++), while confirming the reaction mechanism, do not offer obvious correlations with the Kamlet-Taft solvent descriptors.
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Affiliation(s)
- Lorna Crowhurst
- Department of Chemistry, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
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664
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Ni B, Headley AD. Novel imidazolium chiral ionic liquids that contain a urea functionality. Tetrahedron Lett 2006. [DOI: 10.1016/j.tetlet.2006.08.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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665
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Affiliation(s)
- Christian Reichardt
- Philipps-Universität, Fachbereich Chemie, Hans-Meerwein-Strasse, D-35032 Marburg, Germany
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666
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Liu W, Zhao T, Zhang Y, Wang H, Yu M. The Physical Properties of Aqueous Solutions of the Ionic Liquid [BMIM][BF4]. J SOLUTION CHEM 2006. [DOI: 10.1007/s10953-006-9064-7] [Citation(s) in RCA: 173] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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667
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Tiwari S, Kumar A. Diels–Alder Reactions Are Faster in Water than in Ionic Liquids at Room Temperature. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200600426] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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668
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Tiwari S, Kumar A. Diels–Alder Reactions Are Faster in Water than in Ionic Liquids at Room Temperature. Angew Chem Int Ed Engl 2006; 45:4824-5. [PMID: 16802390 DOI: 10.1002/anie.200600426] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Shraeddha Tiwari
- Physical Chemistry Division, National Chemical Laboratory, Pune 411008, India
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669
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Rey-Castro C, Vega LF. Transport Properties of the Ionic Liquid 1-Ethyl-3-Methylimidazolium Chloride from Equilibrium Molecular Dynamics Simulation. The Effect of Temperature. J Phys Chem B 2006; 110:14426-35. [PMID: 16854152 DOI: 10.1021/jp062885s] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We present here equilibrium molecular dynamics simulation results for self-diffusion coefficients, shear viscosity, and electrical conductivity in a model ionic liquid (1-ethyl-3-methylimidazolium chloride) at different temperatures. The Green-Kubo relations were employed to evaluate the transport coefficients. When compared with available experimental data, the model underestimates the conductivity and self-diffusion, whereas the viscosity is overpredicted, showing only a semiquantitative agreement with experimental data. These discrepancies are explained on the basis of the rigidity and lack of polarizability of the model. Despite this, the experimental trends with temperature are remarkably well reproduced, with a good agreement on the activation energies when available. No significant deviations from the Nernst-Einstein relation can be assessed on the basis of the statistical uncertainty of the simulations, although the comparison between the electric current and the velocity autocorrelation functions suggests some degree of cross-correlation among ions in a short time scale. The simulations reproduce remarkably well the slope of the Walden plots obtained from experimental data of 1-ethyl-3-methylimidazolium chloride, confirming that temperature does not alter appreciably the extent of ion pairing.
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Affiliation(s)
- Carlos Rey-Castro
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Consejo Superior de Investigaciones Científicas, Campus de la UAB, 08193 Bellaterra, Spain.
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670
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Bou Malham I, Letellier P, Turmine M. Evidence of a Phase Transition in Water−1-Butyl-3-methylimidazolium Tetrafluoroborate and Water−1-Butyl-2,3-dimethylimidazolium Tetrafluoroborate Mixtures at 298 K: Determination of the Surface Thermal Coefficient, bT,P. J Phys Chem B 2006; 110:14212-4. [PMID: 16854121 DOI: 10.1021/jp061392k] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We studied the aggregation behavior of two short-chain room-temperature ionic liquids. Previous surface tension studies have shown that 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF(4)) aggregates in water. We observed the same behavior for another ionic liquid, 1-butyl-2,3-dimethylimidazolium tetrafluoroborate (bdmimBF(4)). We carried out a thermodynamic study of the mixtures between water and the two butylimidazolium salts to investigate this unusual behavior for cations with short chains by determining the surface thermal coefficient, b(T,P). Plotting b(T,P) as a function of the molar fraction (X) of the two salts showed a clear discontinuity at X = 0.016 for bmimBF(4) and X = 0.004 for bdmimBF(4). This discontinuity could be attributed to a transition such as an aggregation.
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Affiliation(s)
- Ibrahim Bou Malham
- Université Pierre et Marie Curie-PARIS 6, UMR 7575, Paris F-75005, France
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671
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Daguenet C, Dyson PJ. A Metallacage Encapsulating Chloride as a Probe for a Solvation Scale in Ionic Liquids. Inorg Chem 2006; 46:403-8. [PMID: 17279818 DOI: 10.1021/ic060631f] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
With the purpose of assessing the reactivity of chloride ions dissolved in ionic liquids (ILs), a relative scale for the solvation of chloride is given for a series of ILs based on the bis(trifluoromethane)sulfonimide ([Tf(2)N]) anion and different cations, 1-butyl-3-methylimidazolium ([bmim]), 1-butyl-2,3-dimethylimidazolium ([bdmim]), 1-butyl-1-methylpyrrolidinium ([bmpy]), 1-butylpyridinium ([bpy]), 1-pentyl-1,1,1-triethylammonium ([C(5)e(3)am]), and 1-(2-hydroxy)ethyl-3-methylimidazolium ([mimeOH]). Insights into the solvation of chloride are achieved by the thermodynamic study of the reaction of dissociation of a chloride-templated nickel(II) metallacage performed at various temperatures by UV-visible spectroscopy in each IL. The order of chloride solvation [C(5)e(3)am][Tf(2)N] < [bmpy][Tf(2)N] < [bmim][Tf(2)N] <or= [bdmim][Tf(2)N] < [bpy][Tf(2)N] < [mimeOH][Tf(2)N] was ascertained from the reaction enthalpies determined in the different ILs. The reaction entropies display a concentration-dependent behavior, which has highlighted a correlated motion of the ions in these ILs.
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Affiliation(s)
- Corinne Daguenet
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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672
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Chiappe C, Neri L, Pieraccini D. Application of hydrophilic ionic liquids as co-solvents in chloroperoxidase catalyzed oxidations. Tetrahedron Lett 2006. [DOI: 10.1016/j.tetlet.2006.05.072] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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673
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D'Anna F, Frenna V, Noto R, Pace V, Spinelli D. Study of Aromatic Nucleophilic Substitution with Amines on Nitrothiophenes in Room-Temperature Ionic Liquids: Are the Different Effects on the Behavior of para-Like and ortho-Like Isomers on Going from Conventional Solvents to Room-Temperature Ionic Liquids Related to Solvation Effects? J Org Chem 2006; 71:5144-50. [PMID: 16808500 DOI: 10.1021/jo060435q] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The kinetics of the nucleophilic aromatic substitution of some 2-L-5-nitrothiophenes (para-like isomers) with three different amines (pyrrolidine, piperidine, and morpholine) were studied in three room-temperature ionic liquids ([bmim][BF4], [bmim][PF6], and [bm(2)im][BF4], where bmim = 1-butyl-3-methylimidazolium and bm(2)im = 1-butyl-2,3-dimethylimidazolium). To calculate thermodynamic parameters, a useful instrument to gain information concerning reagent-solvent interactions, the reaction was carried out over the temperature range 293-313 K. The reaction occurs faster in ionic liquids than in conventional solvents (methanol, benzene), a dependence of rate constants on amine concentration similar to that observed in methanol, suggesting a parallel behavior. The above reaction also was studied with 2-bromo-3-nitrothiophene, an ortho-like derivative able to give peculiar intramolecular interactions in the transition state, which are strongly affected by the reaction medium.
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Affiliation(s)
- Francesca D'Anna
- Dipartimento di Chimica Organica E. Paterno, Università degli Studi di Palermo, Viale delle Scienze-Parco d'Orleans II, 90128 Palermo, Italy.
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674
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Daguenet C, Dyson PJ, Krossing I, Oleinikova A, Slattery J, Wakai C, Weingärtner H. Dielectric Response of Imidazolium-Based Room-Temperature Ionic Liquids. J Phys Chem B 2006; 110:12682-8. [PMID: 16800602 DOI: 10.1021/jp0604903] [Citation(s) in RCA: 233] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have used microwave dielectric relaxation spectroscopy to study the picosecond dynamics of five low-viscosity, highly conductive room temperature ionic liquids based on 1-alkyl-3-methylimidazolium cations paired with the bis((trifluoromethyl)sulfonyl)imide anion. Up to 20 GHz the dielectric response is bimodal. The longest relaxation component at the time scale of several 100 ps reveals strongly nonexponential dynamics and correlates with the viscosity in a manner consistent with hydrodynamic predictions for the diffusive reorientation of dipolar ions. Methyl substitution at the C2 position destroys this correlation. The time constants of the weak second process at the 20 ps time scale are practically the same for each salt. This intermediate process seems to correlate with similar modes in optical Kerr effect spectra, but its physical origin is unclear. The missing high-frequency portion of the spectra indicates relaxation beyond the upper cutoff frequency of 20 GHz, presumably due to subpicosecond translational and librational displacements of ions in the cage of their counterions. There is no evidence for orientational relaxation of long-lived ion pairs.
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Affiliation(s)
- Corinne Daguenet
- Ecole Polytechnique Fédérale de Lausanne, Institut des Sciences et Ingénerie Chimiques, CH-1015 Lausanne, Switzerland
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675
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Samanta A. Dynamic Stokes Shift and Excitation Wavelength Dependent Fluorescence of Dipolar Molecules in Room Temperature Ionic Liquids. J Phys Chem B 2006; 110:13704-16. [PMID: 16836314 DOI: 10.1021/jp060441q] [Citation(s) in RCA: 328] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Room temperature ionic liquids (RTILs) are viscous media consisting entirely of ions. Because of the complex nature of various interactions in these media, the solvent properties of the RTILs are very little understood. Since the fluorescence response of molecules comprising conjugated electron donor and acceptor groups, referred to as dipolar molecules, is one of the most frequently exploited sources of information on complex media, whose properties are largely unknown, it is possible to obtain insight into the structure and dynamics of the RTILs by studying the fluorescence behavior of dipolar solutes in these complex media. The most commonly exploited utility of a fluorescent dipolar system is in the estimation of the polarity of the media from its steady state fluorescence response. While several dipolar systems do provide estimates of the polarity of various RTILs, there can be circumstances when the steady state emission frequency of a dipolar system may not truly reflect the equilibrium solvation energy and, hence, the polarity of the medium. The fluorescence response of a dipolar system can be dependent on the excitation wavelength, an observation not commonly encountered in conventional solvents of similar polarities. On the other hand, the time-resolved fluorescence behavior of a dipolar solute in polar medium is one of the primary sources of information on the time-scale of reorganization of the solvent molecules around the photoexcited species. As the RTILs are sufficiently polar media, the time-dependent fluorescence data of the dipolar systems provide insight into the dynamics and mechanism of solvation in these media, which differ considerably from the conventional solvents. These aspects have been discussed taking into consideration the inherent absorption and fluorescence behavior of the imidazolium ionic liquids.
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Affiliation(s)
- Anunay Samanta
- School of Chemistry, University of Hyderabad, Hyderabad 500 046, India.
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676
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Lindén AA, Johansson M, Hermanns N, Bäckvall JE. Efficient and Selective Sulfoxidation by Hydrogen Peroxide, Using a Recyclable Flavin−[BMIm]PF6 Catalytic System. J Org Chem 2006; 71:3849-53. [PMID: 16674058 DOI: 10.1021/jo060274q] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new flavin catalyst 2 immobilized in an ionic liquid ([BMIm]PF6) was used for the highly selective oxidation of sulfides to sulfoxides by hydrogen peroxide. The sulfoxides were obtained in good to high yields and high selectivity without any detectable overoxidation to sulfone. The catalyst in the ionic liquid was recycled up to seven times without loss of activity or selectivity.
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Affiliation(s)
- Auri A Lindén
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
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677
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Chiappe C, Pieraccini D. Determination of Ionic Liquids Solvent Properties Using an Unusual Probe: The Electron Donor−Acceptor Complex between 4,4‘-bis(Dimethylamino)-benzophenone and Tetracyanoethene. J Phys Chem A 2006; 110:4937-41. [PMID: 16599465 DOI: 10.1021/jp057236f] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Michler's ketone (MK) and tetracyanoethene (TCNE) may be used as a UV-vis probe to investigate the solvent properties of ionic liquids (ILs). In molecular solvents, MK and TCNE give an electron donor-acceptor (EDA) complex, a zwitterionic species or a radical ion pair, depending on the aprotic or protic nature of the solvent and on its ionizing power. In agreement with the behavior observed in aprotic solvents, only the EDA complex was detected in ILs bearing low donor anions (beta < 0.7). The formation constant determined in [bmim][Tf(2)N] (K(c) = 5.6 (0.5) M(-1)) is similar to that measured in 1,2-dichloroethane at 25 degrees C. The visible absorption maximum (nu(max,CTC)) of the EDA complex is quantitatively described by a multiple correlation using the Kamlet-Taft pi, beta, and alpha parameters of the solvents. The H-bond donating capacity of ILs is not sufficient to determine the transformation of the EDA complex into the zwitterionic species, but the Kamlet-Taft alpha parameter seems to affect the position of the absorption band. The high ionization power of ILs, moreover, favors the slow dissociation of the EDA complex into its corresponding radical ion pair; this behavior generally characterizes highly polar and highly ionizing protic solvents, such as TFE and HFI. Finally, since the formation of the EDA complex is strongly affected by the presence of impurities, traces of nucleophiles (chloride or amines) or water may be easily detected through the change of the solution color.
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Affiliation(s)
- Cinzia Chiappe
- Dipartimento di Chimica Bioorganica e Biofarmacia, via Bonanno 33, 56126 Pisa, Italy.
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678
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Youngs TGA, Del Pópolo MG, Kohanoff J. Development of Complex Classical Force Fields through Force Matching to ab Initio Data: Application to a Room-Temperature Ionic Liquid. J Phys Chem B 2006; 110:5697-707. [PMID: 16539515 DOI: 10.1021/jp056931k] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Recent experimental neutron diffraction data and ab initio molecular dynamics simulation of the ionic liquid dimethylimidazolium chloride ([dmim]Cl) have provided a structural description of the system at the molecular level. However, partial radial distribution functions calculated from the latter, when compared to previous classical simulation results, highlight some limitations in the structural description offered by force field-based simulations. With the availability of ab initio data it is possible to improve the classical description of [dmim]Cl by using the force matching approach, and the strategy for fitting complex force fields in their original functional form is discussed. A self-consistent optimization method for the generation of classical potentials of general functional form is presented and applied, and a force field that better reproduces the observed first principles forces is obtained. When used in simulation, it predicts structural data which reproduces more faithfully that observed in the ab initio studies. Some possible refinements to the technique, its application, and the general suitability of common potential energy functions used within many ionic liquid force fields are discussed.
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Affiliation(s)
- Tristan G A Youngs
- Atomistic Simulation Centre, School of Physics, Queen's University, Belfast BT7 1NN, UK.
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679
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François Y, Zhang K, Varenne A, Gareil P. New integrated measurement protocol using capillary electrophoresis instrumentation for the determination of viscosity, conductivity and absorbance of ionic liquid–molecular solvent mixtures. Anal Chim Acta 2006. [DOI: 10.1016/j.aca.2006.01.036] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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680
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Cheng JY, Chu YH. 1-Butyl-2,3-trimethyleneimidazolium bis(trifluoromethylsulfonyl)imide ([b-3C-im][NTf2]): a new, stable ionic liquid. Tetrahedron Lett 2006. [DOI: 10.1016/j.tetlet.2005.12.125] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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681
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Mele A, Romanò G, Giannone M, Ragg E, Fronza G, Raos G, Marcon V. The Local Structure of Ionic Liquids: Cation–Cation NOE Interactions and Internuclear Distances in Neat [BMIM][BF4] and [BDMIM][BF4]. Angew Chem Int Ed Engl 2006; 45:1123-6. [PMID: 16411265 DOI: 10.1002/anie.200503745] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Andrea Mele
- Dipartimento di Chimica, Materiali e Ingegneria Chimica Giulio Natta Politecnico di Milano, Via L. Mancinelli, 7, 20131 Milano, Italy.
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682
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The Local Structure of Ionic Liquids: Cation–Cation NOE Interactions and Internuclear Distances in Neat [BMIM][BF4] and [BDMIM][BF4]. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200503745] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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683
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Hunt PA, Gould IR. Structural Characterization of the 1-Butyl-3-methylimidazolium Chloride Ion Pair Using ab Initio Methods. J Phys Chem A 2006; 110:2269-82. [PMID: 16466265 DOI: 10.1021/jp0547865] [Citation(s) in RCA: 180] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Ab initio theoretical methods are used to investigate the gas-phase ion pairs of the ionic liquid 1-butyl-3-methylimidazolium chloride. Multiple stable conformers with the chloride anion positioned (in-plane) around the imidazolium ring or above the C2-H bond are determined. The relative energy ordering of the conformers is examined at the B3LYP, MP2, and CCSD(T) levels. Zero-point energies, BSSE, and basis set effects are examined. For accurate results, correlation (dispersion) effects must be included. The most stable conformers are essentially degenerate and have the chloride H-bonding to, or lying above, the C2-H bond. Other conformers are found to lie approximately 30 and approximately 60 kJ mol(-1) higher in energy. Results are compared with those from recent simulations and experimental studies. The effect of the chloride anion on rotation of the butyl chain is investigated and found to lower some rotational barriers while enhancing others. The origin of the rotational barriers is determined. The number and type of hydrogen bonds formed between the imidazolium cation and chloride anion is found to vary significantly among conformers. No evidence of a possible intra C(alkyl)-H...pi interaction is obtained; however, hints of a Cl...pi interaction are found. The vibrational spectrum of each conformer is examined, and the origin of multiple (H-bonding) features in the vibrational spectrum of the ionic liquid explained.
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Affiliation(s)
- Patricia A Hunt
- Chemistry Department, Imperial College London, London SW7 2AZ, United Kingdom.
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684
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Bini R, Chiappe C, Marmugi E, Pieraccini D. The “non-nucleophilic” anion [Tf2N]– competes with the nucleophilic Br–: an unexpected trapping in the dediazoniation reaction in ionic liquids. Chem Commun (Camb) 2006:897-9. [PMID: 16479304 DOI: 10.1039/b514988f] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Imidazolium ionic liquids containing [Tf2N]- anion are not as innocent as they are often considered; [Tf2N]- is more reactive than Br- in heterolytic dediazoniation reactions.
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Affiliation(s)
- Riccardo Bini
- Dipartimento di Chimica Bioorganica e Biofarmacia, via Bonanno 33, 56126, Pisa, Italy
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685
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Chiappe C, Pieraccini D, Zhao D, Fei Z, Dyson P. Remarkable Anion and Cation Effects on Stille Reactions in Functionalised Ionic Liquids. Adv Synth Catal 2006. [DOI: 10.1002/adsc.200505271] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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686
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Henderson WA, Young VG, Fox DM, De Long HC, Trulove PC. Alkyl vs. alkoxy chains on ionic liquid cations. Chem Commun (Camb) 2006:3708-10. [PMID: 17047819 DOI: 10.1039/b606381k] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The crystal structures and thermal behavior of the 1-(2-methoxyethyl)-2,3-dimethylimidazolium chloride and hexa-fluorophosphate salts are compared with the analogous 1-butyl-2,3-dimethylimidazolium salts to examine the influence of the ether oxygen on salt thermal properties for a typical constituent cation used in the preparation of ionic liquids.
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Affiliation(s)
- Wesley A Henderson
- U. S. Naval Academy, Department of Chemistry, 572 M Holloway Road, Annapolis, Maryland 21402, USA
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687
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Oehlke A, Hofmann K, Spange S. New aspects on polarity of 1-alkyl-3-methylimidazolium salts as measured by solvatochromic probes. NEW J CHEM 2006. [DOI: 10.1039/b516709d] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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688
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Bonnet LG, Kariuki BM. Ionic Liquids: Synthesis and Characterisation of Triphenylphosphonium Tosylates. Eur J Inorg Chem 2006. [DOI: 10.1002/ejic.200500769] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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689
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Wang R, Yuan L, Macartney DH. Inhibition of C(2)-H/D exchange of a bis(imidazolium) dication upon complexation with cucubit[7]uril. Chem Commun (Camb) 2006:2908-10. [PMID: 17007413 DOI: 10.1039/b605919h] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Inclusion of the alpha,alpha'-bis(3-(1-methylimidazolium))-p-xylene dication in cucurbit[7]uril (CB[7], K(CB[7]) = (4.3 x 10(9) M(-1)), with C-H...O=C hydrogen bonding between the guest C(2)-protons and the carbonyl oxygens of the host portals, inhibits the H/D exchange for the C(2)-proton with k(OD) (25 degrees C, D2O) decreasing from 1.2 x 10(3) M(-1) s(-1) (pKa = 22.3) in the absence of CB[7] to 0.9 M(-1) s(-1) (pKa = 25.4) in the presence of 1.1 equiv. CB[7].
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Affiliation(s)
- Ruibing Wang
- Department of Chemistry, Queen's University, Kingston, ON, Canada K7L 3N6
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690
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691
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Yoshida Y, Fujii J, Saito G, Hiramatsu T, Sato N. Dicyanoaurate(i) salts with 1-alkyl-3-methylimidazolium: luminescent properties and room-temperature liquid forming. ACTA ACUST UNITED AC 2006. [DOI: 10.1039/b515869a] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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692
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Yoshida Y, Saito G. Influence of structural variations in 1-alkyl-3-methylimidazolium cation and tetrahalogenoferrate(iii) anion on the physical properties of the paramagnetic ionic liquids. ACTA ACUST UNITED AC 2006. [DOI: 10.1039/b515391c] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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693
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Guo Z, Chen B, López Murillo R, Tan T, Xu X. Functional dependency of structures of ionic liquids: do substituents govern the selectivity of enzymatic glycerolysis? Org Biomol Chem 2006; 4:2772-6. [PMID: 16826302 DOI: 10.1039/b606900b] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The concept of regulating the preference of a reversible multi-step reaction by adjusting the substituents of ionic liquids (ILs) has been successfully exemplified with a group of tetraammonium-based ionic liquids as medium for the enzymatic glycerolysis. Simultaneous existence of long chain hydrophobic substituents and hydrophilic ethoxyl or hydroxyl moieties is found, respectively, to be essential for triglycerides (TG) dissolving and equilibrium shifting. The reactions in the ILs with cations consisting of long chain and free hydroxyl groups gave markedly higher conversion of TG and better preference to monoglyceride formation. Interestingly the predicted results from COSMO-RS (a quantum chemical model programme) achieved a good agreement with the experimental data, mapping out the specific solvation from the ILs as well as demonstrating the interaction between ILs, substrates and products being the intrinsic causes that govern reaction evolution and direct equilibrium shifting.
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Affiliation(s)
- Zheng Guo
- BioCentrum-DTU, Technical University of Denmark, Building 221, DK-2800, Lyngby, Denmark
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694
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Observing the complete solvation response of DCS in imidazolium ionic liquids, from the femtosecond to nanosecond regimes. Chem Phys Lett 2006. [DOI: 10.1016/j.cplett.2005.10.062] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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695
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696
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Lagrost C, Preda L, Volanschi E, Hapiot P. Heterogeneous electron-transfer kinetics of nitro compounds in room-temperature ionic liquids. J Electroanal Chem (Lausanne) 2005. [DOI: 10.1016/j.jelechem.2005.06.013] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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697
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Gerbec JA, Magana D, Washington A, Strouse GF. Microwave-Enhanced Reaction Rates for Nanoparticle Synthesis. J Am Chem Soc 2005; 127:15791-800. [PMID: 16277522 DOI: 10.1021/ja052463g] [Citation(s) in RCA: 426] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Microwave reactor methodologies are unique in their ability to be scaled-up without suffering thermal gradient effects, providing a potentially industrially important improvement in nanocrystal synthetic methodology over convective methods. Synthesis of high-quality, near monodispersity nanoscale InGaP, InP, and CdSe have been prepared via direct microwave heating of the molecular precursors rather than convective heating of the solvent. Microwave dielectric heating not only enhances the rate of formation, it also enhances the material quality and size distributions. The reaction rates are influenced by the microwave field and by additives. The final quality of the microwave-generated materials depends on the reactant choice, the applied power, the reaction time, and temperature. CdSe nanocrystals prepared in the presence of a strong microwave absorber exhibit sharp excitonic features and a QY of 68% for microwave-grown materials. InGaP and InP are rapidly formed at 280 degrees C in minutes, yielding clean reactions and monodisperse size distributions that require no size-selective precipitation and result in the highest out of batch quantum efficiency reported to date of 15% prior to chemical etching. The use of microwave (MW) methodology is readily scalable to larger reaction volumes, allows faster reaction times, removes the need for high-temperature injection, and suggests a specific microwave effect may be present in these reactions.
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Affiliation(s)
- Jeffrey A Gerbec
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, USA
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698
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Price BK, Hudson JL, Tour JM. Green Chemical Functionalization of Single-Walled Carbon Nanotubes in Ionic Liquids. J Am Chem Soc 2005; 127:14867-70. [PMID: 16231941 DOI: 10.1021/ja053998c] [Citation(s) in RCA: 166] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Single walled carbon nanotubes (SWNTs) are exfoliated and functionalized predominantly as individuals by grinding them for minutes at room temperature with aryldiazonium salts in the presence of ionic liquids (ILs) and K(2)CO(3). This constitutes an extremely rapid and mild green chemical functionalization process for obtaining the individualized nanotube structures. A number of ILs and various reaction conditions were surveyed. Raman, XPS, UV/vis/NIR spectroscopies, thermogravimetric analysis, and atomic force and transmission electron microscopies were used to characterize the products.
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Affiliation(s)
- B Katherine Price
- Department of Chemistry, Center for Nanoscale Science and Technology, Rice University, Houston, Texas 77005, USA
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699
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Bini R, Chiappe C, Pieraccini D, Piccioli P, Pomelli CS. Nucleophilic substitution of chlorobis(4-methoxyphenyl)methane: reactivity of carbenium ions in ILs-trifluoroethanol mixtures. Tetrahedron Lett 2005. [DOI: 10.1016/j.tetlet.2005.07.143] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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700
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Anderson JL, Armstrong DW. Immobilized Ionic Liquids as High-Selectivity/High-Temperature/High-Stability Gas Chromatography Stationary Phases. Anal Chem 2005; 77:6453-62. [PMID: 16194112 DOI: 10.1021/ac051006f] [Citation(s) in RCA: 300] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ionic liquids (ILs) are a class of nonmolecular solvents in which the cation/anion combination can be easily tuned to provide desired chemical and physical properties. When used as stationary phases in gas-liquid chromatography, ionic liquids exhibit dual nature retention selectivity. That is, they are able to separate polar molecules such as a polar stationary phase and nonpolar molecules such as a nonpolar stationary phase. However, issues such as optimization of the wetting ability of the ionic liquid on fused-silica capillaries, the maximum operating temperatures of the stationary phases, and nonuniform film thickness on the wall of the capillary at high temperatures have limited their use in gas chromatography. As described in this paper, these limitations are overcome by cross-linking a new class of ionic liquid monomers by free radical reactions to provide a more durable and robust stationary phase. By lightly cross-linking the ionic liquid stationary phase using a small amount of free radical initiator, high-efficiency capillary columns were produced that are able to endure high temperatures with little column bleed. Two types of cross-linked IL stationary phases are developed. A partially cross-linked stationary phase allows for high-efficiency separations up to temperatures of approximately 280 degrees C. However, by creating a more highly cross-linked stationary phase of geminal dicationic ILs, exclusively, an increase in efficiency is observed at high temperatures allowing for its use over 350 degrees C. In addition, through the use of solvation thermodynamics and interaction parameters, it was shown that the cross-linking/immobilization of the ionic liquid does not affect the selectivity of the stationary phase thereby preserving its dual nature retention behavior.
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Affiliation(s)
- Jared L Anderson
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA
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