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A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Green Chemistry".

Deadline for manuscript submissions: closed (31 December 2007)

Special Issue Editor

Guest Editor
Prof. Dr. Jairton Dupont (Website)

School of Chemistry, University of Nottingham, University Park, Nottingham, UK
Fax: +55 51 33087304
Interests: ionic liquids; organometallic chemistry applied to organic synthesis and two-phase catalysis; synthesis and asymmetric catalysis

Published Papers (18 papers)

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Research

Jump to: Review

Open AccessArticle Synthesis and Characterization of Novel Dimeric Ionic Liquids by Conventional Approaches
Int. J. Mol. Sci. 2008, 9(7), 1207-1213; doi:10.3390/ijms9071207
Received: 3 June 2008 / Revised: 25 June 2008 / Accepted: 27 June 2008 / Published: 14 July 2008
Cited by 10 | PDF Full-text (249 KB) | HTML Full-text | XML Full-text
Abstract
The 1H-NMR shifts of the imidazolium protons of some novel dimeric ionic liquids were examined in various deuterated solvents. Interactions between the solvent and the imidazolium salt of butyl substituted ionic liquids were observed to give higher chemical shifts than methyl [...] Read more.
The 1H-NMR shifts of the imidazolium protons of some novel dimeric ionic liquids were examined in various deuterated solvents. Interactions between the solvent and the imidazolium salt of butyl substituted ionic liquids were observed to give higher chemical shifts than methyl substitution. Full article
(This article belongs to the Special Issue Ionic Liquids)
Open AccessArticle Synthesis of Silver Nanoparticles Using Hydroxyl Functionalized Ionic Liquids and Their Antimicrobial Activity
Int. J. Mol. Sci. 2008, 9(5), 807-820; doi:10.3390/ijms9050807
Received: 5 February 2008 / Revised: 21 February 2008 / Accepted: 3 March 2008 / Published: 20 May 2008
Cited by 71 | PDF Full-text (1044 KB) | HTML Full-text | XML Full-text
Abstract
We report a new one phase method for the synthesis of uniform monodisperse crystalline Ag nanoparticles in aqueous systems that has been developed by using newly synthesized mono and dihydroxylated ionic liquids and cationic surfactants based on 1,3-disubstituted imidazolium cations and halogens [...] Read more.
We report a new one phase method for the synthesis of uniform monodisperse crystalline Ag nanoparticles in aqueous systems that has been developed by using newly synthesized mono and dihydroxylated ionic liquids and cationic surfactants based on 1,3-disubstituted imidazolium cations and halogens anions. The hydroxyl functionalized ionic liquids (HFILs) and hydroxyl functionalized cationic surfactants (HFCSs) also simultaneously acts both as the reductant and protective agent. By changing the carbon chain length, alcohol structure and anion of the 1,3-imidazolium based HFILs and HFCSs the particle size, uniform and dispersibility of nanoparticles in aqueous solvents could be controlled. Transmission electron microscopy (TEM), electron diffraction, UV-Vis and NMR, were used for characterization of HFILs, HFCSs and silver nanoparticles. TEM studies on the solution showed representative spherical silver nanoparticles with average sizes 2-8 nm, particularly 2.2 nm and 4.5 nm in size range and reasonable narrow particle size distributions (SD-standard distribution) 0.2 nm and 0.5 nm respectively. The all metal nanoparticles are single crystals with face centered cubic (fcc) structure. The silver nanoparticles surface of plasmon resonance band (λmax) around 420 nm broadened and little moved to the long wavelength region that indicating the formation of silver nanoparticles dispersion with broad absorption around infrared (IR) region. Silver complexes of these HFILs as well as different silver nanoparticles dispersions have been tested in vitro against several gram positive and gram negative bacteria and fungus. The silver nanoparticles providing environmentally friendly and high antimicrobial activity agents. Full article
(This article belongs to the Special Issue Ionic Liquids)
Open AccessArticle Supported Phospholipid Bilayer Interaction with Components Found in Typical Room-Temperature Ionic Liquids – a QCM-D and AFM Study
Int. J. Mol. Sci. 2008, 9(4), 498-511; doi:10.3390/ijms9040498
Received: 16 October 2007 / Revised: 26 February 2007 / Accepted: 14 March 2008 / Published: 4 April 2008
Cited by 25 | PDF Full-text (713 KB) | HTML Full-text | XML Full-text
Abstract
Quartz crystal microbalance with dissipation (QCM-D) monitoring and atomic force microscopy (AFM) were combined to evaluate the defects created by an ionic liquid anion and a cation in a supported phospholipid bilayer composed of zwitterionic lipids on a silica surface. The cation [...] Read more.
Quartz crystal microbalance with dissipation (QCM-D) monitoring and atomic force microscopy (AFM) were combined to evaluate the defects created by an ionic liquid anion and a cation in a supported phospholipid bilayer composed of zwitterionic lipids on a silica surface. The cation 1-octyl-3-methyl imidazolium (OMIM+) was shown to remove lipids from the bilayer, increase the roughness to approximately 2.8 nm (~0.2 for stable supported bilayer) and possibly redeposit lipids with entrapped water. The anion bis(trifluoromethylsulfonyl)imide (Tf2N-) was found to leave distinct defects within the bilayer that had large pore-like interiors which left the surrounding bilayer intact. However, the ionic liquid 1-butyl-1-methyl pyrrolidinium bis(trifluoromethylsulfonyl)imide (BMP-Tf2N) formed a film over the supported bilayer. This work demonstrates, for the first time, the direct effects common components of ionic liquids have on a supported phospholipids bilayer. Full article
(This article belongs to the Special Issue Ionic Liquids)
Open AccessArticle Microwave-Assisted Esterification of N-Acetyl-L-Phenylalanine Using Modified Mukaiyama’s Reagents: A New Approach Involving Ionic Liquids
Int. J. Mol. Sci. 2008, 9(1), 33-44; doi:10.3390/ijms9010033
Received: 30 November 2007 / Accepted: 10 January 2008 / Published: 16 January 2008
Cited by 10 | PDF Full-text (237 KB) | HTML Full-text | XML Full-text
Abstract
Inspired by the concept of ionic liquids (ILs), this study modified the original Mukaiyama’s reagent, 2-chloro-1-methylpyridinium iodide (m.p. 200-dec), from ionic solid into liquids by changing its anion. The esterification of N-acetyl-L-phenylalanine was investigated as a model reaction. The microwave irradiation was [...] Read more.
Inspired by the concept of ionic liquids (ILs), this study modified the original Mukaiyama’s reagent, 2-chloro-1-methylpyridinium iodide (m.p. 200-dec), from ionic solid into liquids by changing its anion. The esterification of N-acetyl-L-phenylalanine was investigated as a model reaction. The microwave irradiation was more effective in esterifying N-acetyl-L-phenylalanine than the conventional reflux method. The original Mukaiyama’s reagent was modified into ILs through manipulating its anion. However, only non-nucleophilic anions (such as EtSO4- and Tf2N-) were favorable since nucleophilic ones (such as CF3COO- and CH3COO-) could exchange with chlorine resulting in non-reactive coupling reagents. Two modified Mukaiyama’s compounds (i.e. hydrophilic [2- ClMePy][EtSO4] and hydrophobic [2-ClMePy][Tf2N]) have been identified as the best ILtype coupling reagents. The esterification reaction was greatly enhanced by using 1- methylimidazole as the base instead of conventional toxic tertiary amines, and by using excess amount of alcohols as solvents instead of dichloromethane. Overall, the method reported is effective and ‘greener’. Full article
(This article belongs to the Special Issue Ionic Liquids)
Open AccessArticle A Spectral-SAR Model for the Anionic-Cationic Interaction in Ionic Liquids: Application to Vibrio fischeri Ecotoxicity
Int. J. Mol. Sci. 2007, 8(8), 842-863; doi:10.3390/i8080842
Received: 25 July 2007 / Revised: 15 August 2007 / Accepted: 17 August 2007 / Published: 23 August 2007
Cited by 35 | PDF Full-text (335 KB) | HTML Full-text | XML Full-text
Abstract
Within the recently launched the spectral-structure activity relationship (S-SAR)analysis, the vectorial anionic-cationic model of a generic ionic liquid is proposed, alongwith the associated algebraic correlation factor in terms of the measured and predictedactivity norms. The reliability of the present scheme is tested [...] Read more.
Within the recently launched the spectral-structure activity relationship (S-SAR)analysis, the vectorial anionic-cationic model of a generic ionic liquid is proposed, alongwith the associated algebraic correlation factor in terms of the measured and predictedactivity norms. The reliability of the present scheme is tested by assessing the Hanschfactors, i.e. lipophylicity, polarizability and total energy, to predict the ecotoxicityendpoints of wide types of ionic liquids with ammonium, pyridinium, phosphonium,choline and imidazolium cations on the aquatic bacteria Vibrio fischeri. The results, whileconfirming the cationic dominant influence when only lipophylicity is considered,demonstrate that the anionic effect dominates all other more specific interactions. It wasalso proved that the S-SAR vectorial model predicts considerably higher activity for theionic liquids than for its anionic and cationic subsystems separately, in all consideredcases. Moreover, through applying the least norm-correlation path principle, the completetoxicological hierarchies are presented, unfolding the ecological rules of combined cationicand anionic influences in ionic liquid toxicity. Full article
(This article belongs to the Special Issue Ionic Liquids)
Open AccessArticle Salting-out in Aqueous Solutions of Ionic Liquids and K3PO4: Aqueous Biphasic Systems and Salt Precipitation
Int. J. Mol. Sci. 2007, 8(8), 736-748; doi:10.3390/i8080736
Received: 18 June 2007 / Revised: 25 July 2007 / Accepted: 27 July 2007 / Published: 31 July 2007
Cited by 54 | PDF Full-text (2913 KB) | HTML Full-text | XML Full-text
Abstract
The salting-out effect produced by the addition of potassium phosphate, K3PO4to aqueous solutions of water-miscible ionic liquids, viz. 1-ethyl-3-methylimidazoliumethyl sulfate, 1-butyl-3-methylimidazolium methyl sulfate, or 1-alkyl-3-methylimidazolium chloride (alkyl = butyl, octyl or decyl) is investigated. The effects areanalyzed using [...] Read more.
The salting-out effect produced by the addition of potassium phosphate, K3PO4to aqueous solutions of water-miscible ionic liquids, viz. 1-ethyl-3-methylimidazoliumethyl sulfate, 1-butyl-3-methylimidazolium methyl sulfate, or 1-alkyl-3-methylimidazolium chloride (alkyl = butyl, octyl or decyl) is investigated. The effects areanalyzed using both the corresponding temperature–composition pseudo-binary andcomposition ternary phase diagrams. Different regions of liquid-liquid and solid-liquidphase demixing are mapped. The phase behavior is interpreted taking into account thecomplex and competing nature of the interactions between the ionic liquid, the inorganicsalt and water. In the case of solutions containing 1-octyl- or 1-decyl-3-methylimidazoliumchloride, the smaller magnitude of the salting-out effects is explained in terms of thepossibility of self-aggregation of the ionic liquid. Full article
(This article belongs to the Special Issue Ionic Liquids)
Open AccessArticle The Preparation and Characterization of Poly(m-phenylene- isophthalamide) Fibers Using Ionic Liquids
Int. J. Mol. Sci. 2007, 8(7), 680-685; doi:10.3390/i8070680
Received: 12 March 2007 / Revised: 14 May 2007 / Accepted: 20 June 2007 / Published: 17 July 2007
Cited by 10 | PDF Full-text (3357 KB) | HTML Full-text | XML Full-text
Abstract
A process to produce fibers from Poly(m-phenyleneisophthalamide)(PMIA)solution in an ionic liquid via wet-spinning technology are described. The spinning processwas investigated on a small laboratory scale. Ionic liquid spinning solutions were firstprepared for PMIA fibers, followed by wet spinning. In the course of [...] Read more.
A process to produce fibers from Poly(m-phenyleneisophthalamide)(PMIA)solution in an ionic liquid via wet-spinning technology are described. The spinning processwas investigated on a small laboratory scale. Ionic liquid spinning solutions were firstprepared for PMIA fibers, followed by wet spinning. In the course of this research, thephysical properties of the PMIA fibers were estimated. We studied the dependence of themechanical properties of the obtained PMIA fibers on the composition of the coagulationbath, and on the choice of solvent in spinning solution. The morphology of the fibers fromionic liquid and traditional DMAc solvents via wet-spinning process were observed byscanning electrical microscopy(SEM). The differences of morphologies and properties ofthe PMIA fibers obtained from two different solvents are discussed. Full article
(This article belongs to the Special Issue Ionic Liquids)
Open AccessArticle On the Extraction of Aromatic Compounds from Hydrocarbons by Imidazolium Ionic Liquids
Int. J. Mol. Sci. 2007, 8(7), 593-605; doi:10.3390/i8070593
Received: 12 June 2007 / Revised: 22 June 2007 / Accepted: 22 June 2007 / Published: 2 July 2007
Cited by 90 | PDF Full-text (280 KB) | HTML Full-text | XML Full-text
Abstract
The liquid-liquid equilibrium for the ternary system formed by n-octane andaromatic (alkylbenzenes) and heteroaromatic compounds (nitrogen and sulfur containingheterocyles) and 1-alkyl-3-methylimidazolium ionic liquids (ILs) associated with variousanions has been investigated. The selectivity on the extraction of a specific aromaticcompound is influenced by [...] Read more.
The liquid-liquid equilibrium for the ternary system formed by n-octane andaromatic (alkylbenzenes) and heteroaromatic compounds (nitrogen and sulfur containingheterocyles) and 1-alkyl-3-methylimidazolium ionic liquids (ILs) associated with variousanions has been investigated. The selectivity on the extraction of a specific aromaticcompound is influenced by anion volume, hydrogen bond strength between the anion andthe imidazolium cation and the length of the 1-methyl-3-alkylimidazolium alkyl side chain.The interaction of alkylbenzenes and sulfur heterocyles with the IL is preferentially throughCH-π hydrogen bonds and the quantity of these aromatics in the IL phase decreases withthe increase of the steric hindrance imposed by the substituents on the aromatic nucleus. Inthe case of nitrogen heterocycles the interaction occurs preferentially throughN(heteroaromatic)-H(imidazolium) hydrogen bonds and the extraction process is largelycontrolled by the nitrogen heterocycle pKa. Competitive extraction experiments suggestthat benzene, pyridine and dibenzothiophene do not compete for the same hydrogen bondsites of the IL. Full article
(This article belongs to the Special Issue Ionic Liquids)
Open AccessArticle Asymmetric Glyoxylate-Ene Reactions Catalyzed by Chiral Pd(II) Complexes in the Ionic Liquid [bmim][PF6]
Int. J. Mol. Sci. 2007, 8(6), 553-563; doi:10.3390/i8060553
Received: 11 May 2007 / Accepted: 15 June 2007 / Published: 22 June 2007
Cited by 5 | PDF Full-text (256 KB) | HTML Full-text | XML Full-text
Abstract
The room temperature ionic liquid [bmim][PF6] was employed as the reactionmedium in the asymmetric glyoxylate-ene reaction of α-methyl styrene (4a) with ethylglyoxylate using chiral palladium(II) complexes as the catalysts. [Pd(S-BINAP)(3,5-CF3-PhCN)2](SbF6)2 (1b) showed the [...] Read more.
The room temperature ionic liquid [bmim][PF6] was employed as the reactionmedium in the asymmetric glyoxylate-ene reaction of α-methyl styrene (4a) with ethylglyoxylate using chiral palladium(II) complexes as the catalysts. [Pd(S-BINAP)(3,5-CF3-PhCN)2](SbF6)2 (1b) showed the highest catalytic activity. Under the reaction conditionsof 40 oC, 0.5 h, and 1b/4a molar ratio of 0.05, ethyl α-hydroxy-4-phenyl-4-pentenoate wasobtained in excellent chemical yield (94 %) with high enantioselectivity (70 %). Otherα-hydroxy esters can also be obtained in high chemical yields and enantioselectitiesthrough the glyoxylate-ene reactions of alkenes with glyoxylates catalyzed by 1b in[bmim][PF6]. Moreover, the ionic liquid [bmim][PF6] which contained the palladium(II)complex could be recycled and reused several times without significant loss of the catalyticactivity. Full article
(This article belongs to the Special Issue Ionic Liquids)
Open AccessArticle Efficient Copper-bisisoquinoline-based Catalysts for Selective Aerobic Oxidation of Alcohols to Aldehydes and Ketones
Int. J. Mol. Sci. 2007, 8(6), 505-512; doi:10.3390/i8060505
Received: 14 December 2006 / Revised: 23 April 2007 / Accepted: 25 May 2007 / Published: 6 June 2007
Cited by 15 | PDF Full-text (203 KB) | HTML Full-text | XML Full-text
Abstract
The selective oxidation of alcohols with molecular oxygen was efficientlycompleted in high conversion and selectivity using copper-bisisoquinoline-based catalystsunder mild reaction condition. The effects of various parameters such as reactiontemperature, reaction time, oxidant, ligands, etc, were studied. Solvent effect has been aswell studied [...] Read more.
The selective oxidation of alcohols with molecular oxygen was efficientlycompleted in high conversion and selectivity using copper-bisisoquinoline-based catalystsunder mild reaction condition. The effects of various parameters such as reactiontemperature, reaction time, oxidant, ligands, etc, were studied. Solvent effect has been aswell studied in ionic liquids [bmim]PF6, [omim]BF4 and [hmim]BF4, comparing totraditional volatile organic solvent. The use of ionic liquids was found to enhance thecatalytic properties of the catalysts used. Full article
(This article belongs to the Special Issue Ionic Liquids)
Open AccessArticle Hydrolysis and Partial Recycling of a Chloroaluminate Ionic Liquid
Int. J. Mol. Sci. 2007, 8(6), 470-477; doi:10.3390/i8060470
Received: 14 March 2007 / Revised: 11 May 2007 / Accepted: 22 May 2007 / Published: 4 June 2007
Cited by 6 | PDF Full-text (184 KB) | HTML Full-text | XML Full-text
Abstract
Hydrolysis of the ionic liquid Et3NHCl-2AlCl3 and a process for recycling thetriethylamine were studied. When the hydrolysis was carried out at a relatively hightemperature, the released HCl could be absorbed more easily. With addition of sodiumhydroxide to the aqueous hydrolysis solution, a [...] Read more.
Hydrolysis of the ionic liquid Et3NHCl-2AlCl3 and a process for recycling thetriethylamine were studied. When the hydrolysis was carried out at a relatively hightemperature, the released HCl could be absorbed more easily. With addition of sodiumhydroxide to the aqueous hydrolysis solution, a feasible process for recycling triethylaminewas developed, involving first distillation of triethylamine, followed by filtration of thealuminium hydroxide. The yield of recovered triethylamine was about 95%. Thetriethylhydrogenammonium chloride prepared from the recycled triethylamine was of goodpurity and could be reused to synthesize new chloroaluminate ionic liquids. Full article
(This article belongs to the Special Issue Ionic Liquids)
Open AccessArticle Organo-niobate Ionic Liquids: Synthesis, Characterization and Application as Acid Catalyst in Pechmann Reactions
Int. J. Mol. Sci. 2007, 8(5), 392-398; doi:10.3390/i8050392
Received: 27 March 2007 / Accepted: 5 May 2007 / Published: 11 May 2007
Cited by 11 | PDF Full-text (60 KB) | HTML Full-text | XML Full-text
Abstract
The combinations of 1-butyl-3-methylimidazolium chloride with NbCl5 yieldedionic mixtures with different melting point temperatures and acidity depending on theniobium molar fraction. The mixtures were characterized by thermal (DSC) andspectroscopic (FT-IR and 1H NMR) analysis. The Pechmann reactions of different phenolswith [...] Read more.
The combinations of 1-butyl-3-methylimidazolium chloride with NbCl5 yieldedionic mixtures with different melting point temperatures and acidity depending on theniobium molar fraction. The mixtures were characterized by thermal (DSC) andspectroscopic (FT-IR and 1H NMR) analysis. The Pechmann reactions of different phenolswith ethylacetoacetate, producing coumarins, was used as model to evaluate the catalyticbehavior of these mixtures as acid Lewis catalyst. These reactions were carried out usingacidic mixtures of 60 mol%. Full article
(This article belongs to the Special Issue Ionic Liquids)
Open AccessArticle Sulfonium-based Ionic Liquids Incorporating the Allyl Functionality
Int. J. Mol. Sci. 2007, 8(4), 304-315; doi:10.3390/i8040304
Received: 23 March 2007 / Accepted: 10 April 2007 / Published: 16 April 2007
Cited by 16 | PDF Full-text (3387 KB) | HTML Full-text | XML Full-text
Abstract
A series of sulfonium halides bearing allyl groups have been prepared andcharacterized. Anion metathesis with Li[Tf2N] and Ag[N(CN)2] resulted in sulfonium-basedionic liquids which exhibit low viscosities at room temperature. The solid state structure ofone of the halide salts [...] Read more.
A series of sulfonium halides bearing allyl groups have been prepared andcharacterized. Anion metathesis with Li[Tf2N] and Ag[N(CN)2] resulted in sulfonium-basedionic liquids which exhibit low viscosities at room temperature. The solid state structure ofone of the halide salts was determined by single crystal X-ray diffraction. Full article
(This article belongs to the Special Issue Ionic Liquids)
Open AccessArticle Rheological Behaviors of Polyacrylonitrile/1-Butyl-3- Methylimidazolium Chloride Concentrated Solutions
Int. J. Mol. Sci. 2007, 8(3), 180-188; doi:10.3390/i8030180
Received: 30 April 2006 / Revised: 8 February 2007 / Accepted: 12 February 2007 / Published: 7 March 2007
Cited by 26 | PDF Full-text (144 KB) | HTML Full-text | XML Full-text
Abstract
One of the room temperature ionic liquids (RTILs), 1-butyl-3-methylimidazoliumchloride ([BMIM]Cl) was chosen to prepare the concentrated solutions of Polyacrylonitrile(PAN). The rheological behaviors of the solutions were measured with rotational rheometryunder different conditions, including temperatures, concentration, and molecular weight ofPAN. The solutions exhibited [...] Read more.
One of the room temperature ionic liquids (RTILs), 1-butyl-3-methylimidazoliumchloride ([BMIM]Cl) was chosen to prepare the concentrated solutions of Polyacrylonitrile(PAN). The rheological behaviors of the solutions were measured with rotational rheometryunder different conditions, including temperatures, concentration, and molecular weight ofPAN. The solutions exhibited shear-thinning behaviors, similar to that of PAN/DMFsolutions. The viscosities decreased with the increasing of shear rates. However, theviscosity decreased sharply at high shear rates when the concentration was up to 16wt%. Thedependence of the viscosity on temperature was analyzed through the determination of theapparent activation energy. Unusually, the viscosity of solutions of higher concentration islower than that of lower concentration. Similarly, the viscosity of low molecular weightPAN was higher than high molecular weight PAN at high shear rates. The dynamicrheological measurement indicates the loss modulus is much higher than storage modulus.The trend of complex viscosity is similar with the result of static rheological measurement.The interaction between PAN and ionic liquid [BMIM]Cl was discussed. Full article
(This article belongs to the Special Issue Ionic Liquids)
Open AccessArticle Laser photolysis study of anthraquinone in binary mixtures ofionic liquid [bmim][PF6] and organic solvent
Int. J. Mol. Sci. 2006, 7(12), 590-600; doi:10.3390/i7120590
Received: 14 September 2006 / Accepted: 14 November 2006 / Published: 19 December 2006
Cited by 11 | PDF Full-text (173 KB)
Abstract
Photochemical properties of the ionic liquid (RTIL) 1-butyl-3-methylimidazoliumhexafluorophosphate [bmim][PF6] and its binary mixed solutions with organic solvent(DMF and MeCN) were investigated by laser photolysis at an excitation wavelength of 355nm, using anthraquinone (AQ) as a probe molecule. It was indicated [...] Read more.
Photochemical properties of the ionic liquid (RTIL) 1-butyl-3-methylimidazoliumhexafluorophosphate [bmim][PF6] and its binary mixed solutions with organic solvent(DMF and MeCN) were investigated by laser photolysis at an excitation wavelength of 355nm, using anthraquinone (AQ) as a probe molecule. It was indicated that the triplet excitedstate of AQ (3AQ*) can abstract hydrogen from [bmim][PF6]. Moreover, along with thechange of the ratio of RTIL and organic solvent, the reaction rate constant changes regularly.Critical points were observed at volume fraction VRTIL = 0.2 for RTIL/MeCN and VRTIL =0.05 for RTIL/DMF. For both systems, before the critical point, the rate constant increasesrapidly with increasing VRTIL; however, it decreases obviously with VRTIL after the criticalpoint. We conclude that the concentration dependence is dominant at lower VRTIL, while theviscosity and phase transformation are dominant at higher VRTIL for the effect of ionic liquidon the decay of rate constant. Full article
(This article belongs to the Special Issue Ionic Liquids)
Open AccessArticle Preparation of Cyclic Urethanes from Amino Alcohols and Carbon Dioxide Using Ionic Liquid Catalysts with Alkali Metal Promoters
Int. J. Mol. Sci. 2006, 7(10), 438-450; doi:10.3390/i7100438
Received: 21 September 2006 / Accepted: 16 October 2006 / Published: 27 October 2006
Cited by 23 | PDF Full-text (117 KB) | HTML Full-text | XML Full-text
Abstract
Several ionic liquids were applied as catalysts for the synthesis of cyclicurethanes from amino alcohols and pressurized CO2 in the presence of alkali metalcompounds as promoters. A comparative study was made for the catalytic performanceusing different ionic liquids, substrates, promoters, and pressures. [...] Read more.
Several ionic liquids were applied as catalysts for the synthesis of cyclicurethanes from amino alcohols and pressurized CO2 in the presence of alkali metalcompounds as promoters. A comparative study was made for the catalytic performanceusing different ionic liquids, substrates, promoters, and pressures. The optimum catalyticsystem was BMIM-Br promoted by K2CO3, which, for 1-amino-2-propanol, produced cyclicurethane in 40% yield with a smaller yield of substituted cyclic urea and no oligomericbyproducts. For other amino alcohols, cyclic urethanes, cyclic ureas, and/or undesiredbyproducts were produced in different yields depending on the substrates used. Possiblereaction mechanisms are proposed. Full article
(This article belongs to the Special Issue Ionic Liquids)
Open AccessArticle Conformations of 1-Butyl-3-methylimidazolium Chloride Probed by High Pressure Raman Spectroscopy
Int. J. Mol. Sci. 2006, 7(10), 417-424; doi:10.3390/i7100417
Received: 7 September 2006 / Revised: 29 September 2006 / Accepted: 16 October 2006 / Published: 25 October 2006
Cited by 19 | PDF Full-text (80 KB) | HTML Full-text | XML Full-text
Abstract
The behavior of 1-butyl-3-methylimidazolium chloride has been investigated byRaman spectroscopy as a function of hydrostatic pressure. Under ambient pressure tworotational isomers (GA and AA forms) of the 1-butyl-3-methylimidazolium cation coexist inthe ionic liquid state. As the supercooled liquid was compressed from ambient [...] Read more.
The behavior of 1-butyl-3-methylimidazolium chloride has been investigated byRaman spectroscopy as a function of hydrostatic pressure. Under ambient pressure tworotational isomers (GA and AA forms) of the 1-butyl-3-methylimidazolium cation coexist inthe ionic liquid state. As the supercooled liquid was compressed from ambient to 0.9 GPa,the contribution of the GA conformer decreases in intensity as the pressure was elevated. Anew high pressure phase is formed above the pressure of 1.5 GPa. This new high pressurephase of 1-butyl-3-methylimidazolium chloride arises from perturbed GA conformer, i.e.,distorted Crystal 2. Crystal 1 form (AA form) is known as a thermodynamically stable formunder ambient pressure. Nevertheless, crystal 1 form is switched to a metastable state underthe condition of high pressure. Full article
(This article belongs to the Special Issue Ionic Liquids)

Review

Jump to: Research

Open AccessReview Application of Chromatographic and Electrophoretic Methods for the Analysis of Imidazolium and Pyridinium Cations as Used in Ionic Liquids
Int. J. Mol. Sci. 2006, 7(11), 497-509; doi:10.3390/i7110497
Received: 30 August 2006 / Accepted: 16 November 2006 / Published: 17 November 2006
Cited by 29 | PDF Full-text (102 KB) | HTML Full-text | XML Full-text
Abstract
Interest in ionic liquids for their potential in different chemical processes isconstantly increasing, as they are claimed to be environmentally benign – excellent, non-volatile solvents for a wide range of applications. The wide applicability of thesecompounds also demands reliable, relatively simple and [...] Read more.
Interest in ionic liquids for their potential in different chemical processes isconstantly increasing, as they are claimed to be environmentally benign – excellent, non-volatile solvents for a wide range of applications. The wide applicability of thesecompounds also demands reliable, relatively simple and reproducible analytical techniques.These methods must be applicable not only to different technical or natural matrices but alsoto the very low concentrations that are likely to be present in biological and environmentalsystems. In this review, therefore, methods for separating and analysing imidazolium- andpyridinium-type ionic liquids in aqueous matrices using high performance liquidchromatography (HPLC) and capillary electrophoresis (CE) are examined. The techniquesfor identifying ionic liquids are meant primarily to track the concentrations of ionic liquidsas residues not only in products and wastes but also in biological or environmental samples.The application of hyphenated techniques in this field is intended to selectively separate thequaternary entity from other cationic and non-ionic species present in the matrix, and toenable its fine-scale quantification. Nowadays, methods developed for cation analysis arebased mostly on reversed-phase high-performance liquid chromatography, ionchromatography, ion-pair chromatography and capillary electrophoresis, where variousbuffered mobile phases are used. Full article
(This article belongs to the Special Issue Ionic Liquids)

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