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Showing papers on "Ether published in 2009"


Journal ArticleDOI
TL;DR: In this article, a one-pot procedure for synthesis of 1,2,3-triazole derivatives via the three-component coupling (TCC) reaction between terminal alkynes, benzyl or alkyl halides, and sodium azide in the presences of 1'mol% nanoparticles copper/carbon (Cu/C) catalyst has been developed.
Abstract: A one-pot procedure for synthesis of 1,2,3-triazole derivatives via the three-component coupling (TCC) reaction between terminal alkynes, benzyl or alkyl halides, and sodium azide in the presences of 1 mol% nanoparticles copper/carbon (Cu/C) catalyst has been developed. The catalyst showed high catalytic activity and 1,4-regioselectivity for the [3+2] Huisgen cycloaddition in water as a “green” solvent and good to excellent yields were obtained in all cases. This procedure eliminates the need to handle organic azides, and they are generated in situ. The reaction has a broad scope and is especially practical for the synthesis of new azacrown ether and anthraquinone derivatives of triazole. The heterogeneous catalysts were fully characterized by scanning electron microscopy (SEM), atomic forced microscopy (AFM), X-ray diffraction (XRD), inductively coupled plasma (ICP) analysis and FT-IR experimental techniques. The catalyst was recycled ten times without significant loss of activity.

274 citations


Journal ArticleDOI
Junhua Wang1, Zhuo Zhao1, Feixiang Gong1, Shenghai Li1, Suobo Zhang1 
TL;DR: In this article, a new bisphenol monomer, 2,2′-dimethylaminemethylene-4,4′-biphenol (DABP), was easily prepared by Mannich reaction of dimethylamine and formaldehyde with 4, 4′-, biphenols, followed by reaction with iodomethane.
Abstract: A new bisphenol monomer, 2,2′-dimethylaminemethylene-4,4′-biphenol (DABP), was easily prepared by Mannich reaction of dimethylamine and formaldehyde with 4,4′-biphenol. Novel partially fluorinated poly(arylene ether sulfone)s with pendant quaternary ammonium groups were prepared by copolymerization of DABP, 4,4′-biphenol, and 3,3′,4,4′-tetrafluorodiphenylsulfone, followed by reaction with iodomethane. The resulting copolymers PSQNI-x (where x represents the molar fraction of DABP in the feed) with high molecular weight exhibited outstanding solubility in polar aprotic solvents; thus, the flexible and tough membranes of PSQNI-x with varying ionic content could be prepared by casting from the DMAc solution. Novel anion exchange membranes, PSQNOH-x, were obtained by an anion exchange of PSQNI-x with 1 N NaOH. All PSQNOH-x membranes showed conductivities above 10−2 S cm−1 at room temperature, for example, the hydroxide conductivity of PSQNOH-90 achieved to 8.4 × 10−2 S cm−1, which was thus comparable to the p...

211 citations


Journal ArticleDOI
TL;DR: In this article, the authors exploited ionic liquids as media for depolymerization of lignin, and obtained up to 11.6% molar yield of the dealkylation product 2-methoxyphenol from the model compound 2methoxy-4-(2-propenyl)phenol and cleaved 2-phenylethyl phenyl ether.
Abstract: Lignin, a readily available form of biomass, is a potential source of renewable aromatic chemicals through catalytic conversion. Recent work has demonstrated that ionic liquids are excellent solvents for processing woody biomass and lignin. Seeking to exploit ionic liquids as media for depolymerization of lignin, we investigated reactions of lignin model compounds in these solvents. Using Bronsted acid catalysts in 1-ethyl-3-methylimidazolium triflate at moderate temperatures below 200 °C, we obtained up to 11.6% molar yield of the dealkylation product 2-methoxyphenol from the model compound 2-methoxy-4-(2-propenyl)phenol and cleaved 2-phenylethyl phenyl ether, a model for lignin ethers. Despite these successes, acid catalysis failed in dealkylation of the saturated-chain model compound 4-ethyl-2-methoxyphenol and did not produce monomeric products from organosolv lignin, demonstrating that further work is required to understand the complex chemistry of lignin depolymerization.

208 citations


Journal ArticleDOI
TL;DR: In this paper, locally and densely sulfonated poly(ether sulfone)s were successfully prepared for fuel cell applications by the nucleophilic substitution of 4,4′-dichlorodiphenylsulfone with 1,2,4,5-tetrakis([1,1′-biphexafluoropropane]-2-oxy)-3,6-bis(4-hydroxyphenoxy)benzene and 2,2-bis (4,hydroxymhenyl)hexafloor
Abstract: New locally and densely sulfonated poly(ether sulfone)s were successfully prepared for fuel cell applications by the nucleophilic substitution of 4,4′-dichlorodiphenylsulfone with 1,2,4,5-tetrakis([1,1′-biphenyl]-2-oxy)-3,6-bis(4-hydroxyphenoxy)benzene and 2,2-bis(4-hydroxyphenyl)hexafluoropropane, followed by sulfonation using chlorosulfonic acid. The polymers gave tough, flexible, and transparent membranes by solvent casting. The large difference in polarity between the locally and densely sulfonated units and hydrophobic units of the polymers resulted in the formation of well-defined phase-separated structures, which induced efficient proton conduction in a wide range of 30−95% RH at 80 °C.

202 citations


Journal ArticleDOI
TL;DR: Ni-catalyzed Sonogashira coupling of nonactivated, beta-H-containing alkyl halides, including chlorides, is reported and allows for orthogonal functionalization of alkyal halides with multiple reactive sites.
Abstract: Ni-catalyzed Sonogashira coupling of nonactivated, β-H-containing alkyl halides, including chlorides, is reported. The coupling is tolerant to a wide range of functional groups, including ether, ester, amide, nitrile, keto, heterocycle, acetal, and aryl halide, in both coupling partners. The coupling can be selective for a specific C−X bond (X = I, Br, Cl) and allows for orthogonal functionalization of alkyl halides with multiple reactive sites.

201 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigated the catalytic etherification of glycerol with tert-butyl alcohol in the presence of lab-made silica supported acid catalysts.
Abstract: The heterogeneous catalytic etherification of glycerol with tert- butyl alcohol was investigated in presence of lab-made silica supported acid catalysts. As reference, two commercial acid ion-exchange resins were also used. Experiments were carried out in batch mode at T R ranging from 303 to 363 K. An increase in reaction temperature favors the formation of di -substituted ethers. The etherification reaction proceeds according to a consecutive path and the surface reaction between adsorbed glycerol and protonated tert -butanol (tertiary carbocation) can be considered as the rate determining step. Steric hindrance phenomena and water hinder the formation of tri -substituted ether (TBGE). As expected, water removal was necessary to allow the higher ethers formation. The specific activity (turnover frequency, TOF ) of A-15 catalyst is significantly higher than that of the other studied acid systems, due to the wide pore diameter that allows an easier accessibility of the reagent molecules.

195 citations


Journal ArticleDOI
TL;DR: Alkyl halides containing ester, amide, ether, thioether, alcohol, pyrrole, indole, furan, nitrile, conjugated enone, and aryl halide moieties were coupled to give high isolated yields of products in which these units stay intact and O-TMEDA is a better additive than TMEDA.
Abstract: A nickel(II) pincer complex [(MeNN2)NiCl] (1) catalyzes Kumada−Corriu−Tamao cross coupling of nonactivated alkyl halides with aryl and heteroaryl Grignard reagents. The coupling of octyl bromide with phenylmagnesium chloride was used as a test reaction. Using 3 mol % of 1 as the precatalyst and THF as the solvent, and in the presence of a catalytic amount of TMEDA, the coupling product was obtained in a high yield. The reaction conditions could be applied to cross coupling of other primary and secondary alkyl bromides and iodides. The coupling is tolerant to a wide range of functional groups. Therefore, alkyl halides containing ester, amide, ether, thioether, alcohol, pyrrole, indole, furan, nitrile, conjugated enone, and aryl halide moieties were coupled to give high isolated yields of products in which these units stay intact. For the coupling of ester-containing substrates, O-TMEDA is a better additive than TMEDA. The reaction protocol proves to be efficient for the coupling of Knochel-type functionali...

194 citations


Journal ArticleDOI
TL;DR: 2-Octynoic acid and phenylpropiolic acid were employed for the palladium-catalyzed decarboxylative coupling reaction and with a variety of aryl halides and showed high reactivities and tolerance of functional groups such as vinyl, ester, ether, ketone, and amine.
Abstract: 2-Octynoic acid and phenylpropiolic acid were employed for the palladium-catalyzed decarboxylative coupling reaction and with a variety of aryl halides. The former needed 1,4-bis(diphenylphosphino)butane (dppb) as a ligand and the latter tri-tert-butylphosphine (P(t)Bu(3)), and both required 2 equiv of tetra-n-butylammonium fluoride (TBAF) for full conversion. These reactions showed high reactivities and tolerance of functional groups such as vinyl, ester, ether, ketone, and amine.

167 citations



Journal ArticleDOI
TL;DR: It is found that the oxygen-carbon bond dissociation enthalpy is substantially lowered by oxygen substituents situated at the phenyl ring adjacent to the ether oxygen, which could be a competitive initial reaction under high-temperature pyrolysis conditions.
Abstract: Lignin is an abundant natural resource that is a potential source of valuable chemicals. Improved understanding of the pyrolysis of lignin occurs through the study of model compounds for which phenethyl phenyl ether (PhCH2CH2OPh, PPE) is the simplest example representing the dominant β-O-4 ether linkage. The initial step in the thermal decomposition of PPE is the homolytic cleavage of the oxygen−carbon bond. The rate of this key step will depend on the bond dissociation enthalpy, which in turn will depend on the nature and location of relevant substituents. We used modern density functional methods to calculate the oxygen−carbon bond dissociation enthalpies for PPE and several oxygen-substituted derivatives. Since carbon−carbon bond cleavage in PPE could be a competitive initial reaction under high-temperature pyrolysis conditions, we also calculated substituent effects on these bond dissociation enthalpies. We found that the oxygen−carbon bond dissociation enthalpy is substantially lowered by oxygen subs...

158 citations


Journal ArticleDOI
TL;DR: The incorporation of ether groups into the ester side-chain significantly reduced the toxicity compared with alkyl ester derivatives, and 6 examples which can be classed as readily biodegradable are presented.

Journal ArticleDOI
TL;DR: In this paper, a poly(arylene ether) (PAE) with high fluorine content and a poly (arylene e ether nitrile), each containing pendant phenyl sulfonic acids were synthesized.
Abstract: A poly(arylene ether) (PAE) with high fluorine content and a poly(arylene ether nitrile) (PAEN) with high nitrile content, each containing pendant phenyl sulfonic acids were synthesized. The PAE and PAEN were prepared from decafluorobiphenyl (DFBP) and difluorobenzonitrile (DFBN) respectively, by polycondensation with 2-phenylhydroquinone (PHQ) by conventional aromatic nucleophilic substitution reactions. The sulfonic acid groups were introduced by mild postsulfonation exclusively on the para-position of the pendant phenyl ring in PHQ. The membrane properties of the resulting sulfonated copolymers sPAE and sPAEN were compared for fuel cell applications. The copolymers sPAE and sPAEN, each having a degree of sulfonation (DS) of 1.0 had high ion exchange capacities (IECv(wet) (volume-based, wet state)) of 1.77 and 2.55 mequiv/cm3, high proton conductivities of 135.4 and 140.1 mS/cm at 80 °C, and acceptable volume-based water uptake of 44.5−51.9 vol % at 80 °C, respectively, compared to Nafion. The data poin...

Journal ArticleDOI
TL;DR: The consecutive hydrogenolysis and hydrogenation of the lignin model compound dihydrobenzofuran was studied in supercritical methanolic solutions using porous metal oxide catalysts, leading principally to a mixture of cyclohexanols.
Abstract: A (super)critical transfer: The consecutive hydrogenolysis and hydrogenation of the lignin model compound dihydrobenzofuran was studied in supercritical methanolic solutions using porous metal oxide catalysts. These catalysts promote H(2) production from methanol followed by hydrogenolysis of the ether linkages and reduction of the aromatic rings, leading principally to a mixture of cyclohexanols.

Journal ArticleDOI
TL;DR: Employing CuI nanoparticles as an efficient catalyst for the cross-coupling reactions of various N/O nucleophilic reagents with aryl chlorides could be successfully carried out under mild conditions in the absence of both the ligands and strong bases.
Abstract: Employing CuI nanoparticles as an efficient catalyst for the cross-coupling reactions of various N/O nucleophilic reagents with aryl chlorides could be successfully carried out under mild conditions in the absence of both the ligands and strong bases. A variety of products including N-arylimidazoles and aryl ethers were synthesized in good to excellent yields.

Journal ArticleDOI
TL;DR: When arylmethyl 4-butynyl ether and a catalytic amount of Rh(2)(tfa)(4) (tfa = CF(3)CO(2)-) were heated in toluene, 2-aryl-3-(sulfonyl)-5,6-dihydro-2H-pyran was produced in good yield.
Abstract: When arylmethyl 4-(sulfonyl)-3-butynyl ether and a catalytic amount of Rh2(tfa)4 (tfa = CF3CO2−) were heated in toluene, 2-aryl-3-(sulfonyl)-5,6-dihydro-2H-pyran was produced in good yield. Ring cl...

Journal ArticleDOI
30 Oct 2009-Science
TL;DR: It is shown that the use of a bimetallic base can overcome instability through a cooperative combination of zinc-carbon and sodium-oxygen bonding, and deprotonation of alkyl and vinyl carbon-hydrogen bonds for synthetic purposes is overcome.
Abstract: Deprotonation of alkyl and vinyl carbon-hydrogen bonds for synthetic purposes is often hindered not merely by the need for an exceptionally strong base, but by the inherent instability of the resultant anion. Metalation of cyclic ethers adjacent to oxygen, for example, has invariably initiated a ring-opening decomposition pathway. Here, we show that the use of a bimetallic base can overcome such instability through a cooperative combination of zinc-carbon and sodium-oxygen bonding. Both tetrahydrofuran and tetrahydropyran reacted cleanly over days at room temperature to yield alpha-zinc-substituted products that were sufficiently stable to be isolated and crystallographically characterized. A related zincation-anion trapping strategy, with sodium replaced by potassium, induced clean deprotonation of ethene to yield a stable product. Preliminary electrophilic quenching experiments with the alpha-zinc-substituted cyclic ethers and benzoyl chloride gave satisfactory yields of the tetrahydrofuran-derived ketone but only trace amounts of the tetrahydropyran-derived ketone.

Journal ArticleDOI
TL;DR: In this article, a method for the difluoromethylation of phenols and thiophenols, using diethyl bromodifluorsophosphonate (1) as a diffluorocarbene precursor, is described.

Journal ArticleDOI
TL;DR: The reactions of indoles with ethers give a variety of symmetric and unsymmetric 1,1-bis-indolylmethane derivatives via iron-catalyzed C-H bond oxidation and C-O bond cleavage.
Abstract: The reactions of indoles with ethers give a variety of symmetric and unsymmetric 1,1-bis-indolylmethane derivatives via iron-catalyzed C-H bond oxidation and C-O bond cleavage.

Journal ArticleDOI
Kailiang Wang1, Maoyun Lü1, Ao Yu1, Xiao-Qing Zhu1, Qingmin Wang1 
TL;DR: The mechanistic investigations show that FeCl(3)-catalyzed coupling proceeds through the heterolytic coupling (A(+) + B), which has been applied to intermolecular biaryl coupling of 2-naphthols and phenol ether.
Abstract: Easily available and nontoxic FeCl3 catalyzes intramolecular oxidative coupling for the direct construction of the phenanthrene ring using meta-chloroperbenzoic acid as sole oxidant at room temperature in excellent yields. The mechanistic investigations show that FeCl3-catalyzed coupling proceeds through the heterolytic coupling (A+ + B). The catalytic approach has been applied to intermolecular biaryl coupling of 2-naphthols and phenol ether.

Journal ArticleDOI
TL;DR: In this article, Nb and Ta solid Lewis acids able to work in the presence of water have been prepared by incorporating these elements in the framework of zeolite Beta by a direct synthesis procedure.
Abstract: Nb and Ta solid Lewis acids able to work in the presence of water have been prepared by incorporating these elements in the framework of zeolite Beta by a direct synthesis procedure. Characterization of the samples by extended X-ray absorption fine structure and X-ray absorption near edge structure indicate that the calcined samples contain tetracoordinated Nb5+ (or Ta5+) with three siloxane bridges and one Nb═O (or Ta═O) bonds. The presence of Lewis acidity has been characterized by IR of adsorbed pyridine and cyclohexanone. The Nb- and Ta-Beta samples are catalytically active for the Meerwein−Ponndorf−Verley reduction of cyclohexanone with 2-butanol and the etherification of 2-butanol with p-methoxybenzalcohol. Both reactions can be successfully combined in a domino reaction to obtain the ether starting with p-methoxybenzaldehyde. The catalytic activity of Nb- and Ta-Beta has been compared with that of the homogeneous counterparts (NbCl5 and TaCl5) reported in the literature for the intramolecular carbo...

Journal ArticleDOI
TL;DR: The catalytic system not only is capable of coupling hindered substrate but also tolerates a broad range of a series of functional groups.
Abstract: A wide range of diaryl ethers and alkyl aryl ethers are synthesized through intermolecular C(aryl)−O bond formation from the corresponding aryl iodides/aryl bromides and phenols/alcohols through Ullmann-type coupling reaction in the presence of a catalytic amount of easily available (±)-diol L3-CuI complex under very mild reaction conditions. Less reactive aryl bromides can also be used for O-arylation of phenols under the same reaction conditions without increasing the reaction temperature, catalyst loading, and time. The catalytic system not only is capable of coupling hindered substrate but also tolerates a broad range of a series of functional groups.

Journal ArticleDOI
TL;DR: Water uptake measured at different relative humidity values or by full immersion in water between 25 and 145 degrees C was found to depend very strongly on previous thermal treatment and casting solvent, which is of significant importance for the improvement of proton-exchange membrane fuel cells.
Abstract: Sulfonated poly(ether ether ketone) (SPEEK) membranes were thermally treated at temperatures between 120 and 160 °C. Water uptake measured at different relative humidity values or by full immersion in water between 25 and 145 °C was found to depend very strongly on previous thermal treatment and casting solvent. Water-uptake coefficient values as low as 10−15 even upon immersion in water at 100 °C were obtained with membranes treated at 160 °C. This effect is related to cross-linking by SO2 bridges between macromolecular chains. An important role is also played by the casting solvent: among the investigated solvents, dimethylsulfoxide (DMSO) gave the best results. A chemical kinetics model is outlined that permits the estimation of the relevant kinetic parameters, especially the activation energy of the cross-linking reaction, which was found to be about 60 kJ/mol. These results are of significant importance for the improvement of proton-exchange membrane fuel cells.

Journal ArticleDOI
TL;DR: In this paper, four kinds of sulfonated poly(arylene ether sulfone)s containing hydrophobic component of different size was synthesized by the copolymerization of disodium 3,3′-disulfo-4,4′-difluorophenyl sulfone and 4, 4′-dimethyl sulfone with 2,2-bis(2-hydroxy-5-biphenylyl)propane (SPE1), 4,4-dihydroxytetraphenylmethane (
Abstract: Four kinds of sulfonated poly(arylene ether sulfone)s containing hydrophobic component of different size was synthesized by the copolymerization of disodium 3,3′-disulfo-4,4′-difluorophenyl sulfone and 4,4′-difluorophenyl sulfone with 2,2-bis(2-hydroxy-5-biphenylyl)propane (SPE1), 4,4′-dihydroxytetraphenylmethane (SPE2), 9,9-bis(4-hydroxyphenyl)fluorene (SPE3), or 2,7-dihydroxynaphthalene (SPE4) under nucleophilic aromatic substitution conditions. The copolymer composition was set at 45−70 mol % of 3,3′-disulfo-4,4′-difluorophenyl sulfone in order to achieve similar ion exchange capacity (ca. 2.0 mequiv/g) for all the sulfonated copolymers SPE1−4. The copolymers were of high molecular weight (Mn = 150−220 kDa, Mw = 310−695 kDa) to give tough and flexible membranes by solution casting. STEM observation revealed that small hydrophobic components (SPE3 and SPE4) induced larger water cluster than bulky hydrophobic ones (SPE1 and SPE2). The small hydrophobic components induced high proton conductivities and pr...

PatentDOI
04 Sep 2009-ACS Nano
TL;DR: This work reports on the chemical and biological functionalization of a variety of semiconductor nanoparticle systems using novel carbodiimide reagents that do not cause precipitation even at high loading levels and can be used to efficiently functionalize carboxylic acid coated NPs.
Abstract: Reagents and methods for synthesizing water-soluble nanoparticles have been developed. In an aspect, poly(ethylene glycol) methyl ether carbodiimide is used as a coupling reagent for the biological and chemical functionalization of water-soluble nanoparticles.

Journal ArticleDOI
TL;DR: Pd(II)(15-crown-5-phen)Cl(2)-H(5)PV(2)Mo(10)O(40) was used as a catalyst for the Wacker type oxidation of 1-alkenes to yield the corresponding methylketones in essentially quantitative yields using nitrous oxide as the terminal oxidant.
Abstract: A 1,10-phenanthroline ligand decorated at the 5,6-position by a 15-crown-5 ether moiety was prepared. Ligation of Pd(II) at the nitrogen atom positions followed by complexation at the crown ether group of a redox active H(5)PV(2)Mo(10)O(40) polyoxometalate yielded a hybrid metallorganic-polyoxometalate complex, Pd(II)(15-crown-5-phen)Cl(2)-H(5)PV(2)Mo(10)O(40). This complex was characterized by IR, UV-vis, ESI-MS, and NMR spectroscopy and elemental analysis that all confirmed the hybrid nature of the complex. Pd(II)(15-crown-5-phen)Cl(2)-H(5)PV(2)Mo(10)O(40) was used as a catalyst for the Wacker type oxidation of 1-alkenes to yield the corresponding methylketones in essentially quantitative yields using nitrous oxide as the terminal oxidant.

Journal ArticleDOI
TL;DR: The poly(MPC)-grafted PEEK surface fabricated by a novel and simple polymerization system exhibited unique characteristics such as high wettability and high antiprotein adsorption, which makes it highly suitable for medical applications.
Abstract: In the present paper, we reported the fabrication of a highly hydrophilic nanometer-scale modified surface on a poly(ether ether ketone) (PEEK) substrate by photoinduced graft polymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC) in the absence of photoinitiators. Photoirradiation results in the generation of semibenzopinacol-containing radicals of benzophenone units in the PEEK molecular structure, which acts as a photoinitiator during graft polymerization. The poly(MPC)-grafted PEEK surface fabricated by a novel and simple polymerization system exhibited unique characteristics such as high wettability and high antiprotein adsorption, which makes it highly suitable for medical applications.

Journal ArticleDOI
TL;DR: In this article, a facile and efficient strategy for the syntheses of novel hyperbranched poly(ether amide)s (HPEA) from multihydroxyl primary amines and (meth)acryloyl chloride has been developed.
Abstract: A facile and efficient strategy for the syntheses of novel hyperbranched poly(ether amide)s (HPEA) from multihydroxyl primary amines and (meth)acryloyl chloride has been developed. The chemical structures of the HPEAs were confirmed by IR and NMR spectra. Analyses of SEC (size exclusion chromatography) and viscosity characterizations revealed the highly branched structures of the polymers obtained. The resultant hyperbranched polymers contain abundant hydroxyl groups. The thermoresponsive property was obtained from in situ surface modification of abundant OH end groups with N-isopropylacrylamide (NIPAAm). The study oil temperature-dependent characteristics has revealed that NIPAAm-g-HPEA exhibits an adjustable lower critical solution temperature (LCST) of about 34-42 degrees C depending on the grafting degree. More interestingly, the work provided an interesting phenomenon where the HPEA backbones exhibited strong blue photoluminescence.

Journal ArticleDOI
TL;DR: A theoretical study of the mechanism and kinetics of the OH radical reactions with aliphatic ethers is presented, and a stepwise mechanism involving the formation of H bonded complexes in the entrance and exit channels is suggested for the first time.
Abstract: A theoretical study of the mechanism and kinetics of the OH radical reactions with aliphatic ethers is presented. Several methods were evaluated using the 6-311++G(d,p) basis set, with dimethyl ether as a test molecule. On the basis of the dimethyl ether results, the M05−2X functional was selected for the rest of the calculations. All the possible H abstraction paths have been modeled, and the importance of differentiating among H atoms bonded to the same C atom, according to their orientation with respect to the O atom in the ether, is analyzed. The rate coefficients are calculated using interpolated variational transition-state theory by mapping (IVTST-M), within the IVTST-M-4/4 scheme, in conjunction with small-curvature tunneling (SCT) corrections. The discussion is focused on the 280−400 K temperature range, but additional information is provided for an extended range (280−2000 K). Our analysis suggests a stepwise mechanism involving the formation of H bonded complexes in the entrance and exit channe...

Journal ArticleDOI
TL;DR: A novel series of heterocyclic o/m/p substituted diphenyl ether derivatives appear to have a novel mechanism of action against M. tuberculosis, and their structural features should be studied further for their potential use as new antitubercular drugs.

Journal ArticleDOI
TL;DR: The MD simulations indicate that the less effective assembly between the more flexible alkoxy chains, in comparison to alkyl chains, is the structural reason for higher ionic mobility in MOENM(2)E TFSI.
Abstract: The viscosity of ionic liquids based on quaternary ammonium cations is reduced when one of the alkyl chains is replaced by an alkoxy chain (Zhou et al. Chem. Eur. J. 2005, 11, 752.). A microscopic picture of the role played by the ether function in decreasing the viscosity of quaternary ammonium ionic liquids is provided here by molecular dynamics (MD) simulations. A model for the ionic liquid N-ethyl-N,N-dimethyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide, MOENM2E TFSI, is compared to the tetraalkylammonium counterpart. The alkoxy derivative has lower viscosity, higher ionic diffusion coefficients, and higher conductivity than the tetraalkyl system at the same density and temperature. A clear signature of the ether function on the liquid structure is observed in cation−cation correlations, but not in anion−anion or anion−cation correlations. In both the alkyl and the alkoxy ionic liquids, there is aggregation of long chains of neighboring cations within micelle-like structures. The MD ...