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Investigation of carbon-2 substituted imidazoles and their corresponding ionic liquids
... As a continuation of our systematic research on the thermodynamic properties of ILs binary mixtures with molecular solvents, 1,2,3-trialkylimidazolium-based ionic liquids were studied both pure and in the mixtures with GBL. These ionic liquids are considered to be promising supporting electrolytes for electroplating and other electrochemical applications [22][23][24][25][26][27][28][29][30][31][32][33][34] due to the absence of an acidic proton in the C-2 position and their increased stability [22,23] compared to that of 1,3-dialkyl-substituted ILs [35]. Therefore, the main goal of this work were experimental density and viscosity measurements for selected 1,2,3trialkylimidazolium bis(trifluoromethylsulfonyl)imide ILs with GBL in the temperature range from (293. ...
... It can be observed that viscosity deviation values, ∆η, are negative at all temperatures and compositions becoming less negative at higher temperatures (Ttble 4, figure S6). This trend has been confirmed by the other authors [25,43,[67][68][69][70]. ...
... Excess molar volumes and other volumetric parameters, as well as transport properties were determined in order to discuss the interactions between GBL and 1,2,3- Relative standard uncertainties are: u(d) = 0.4%, u(η) = 1%, RSD (p) = 1.5% standard uncertainty: u(T) = 0.015 K a [43]; b [44]; c [45]; d [32]; e [46]; f [47]; g [48]; h [49]; i [50]; j [51]; k [52]; l [53]; m [54]; n [25]; o [55]; p [56]; q [57]; r [58]; s [59] * ionic liquid [emmim][NTf 2 ] was possibly supercooled liquid at T = 293.15 K Table 3. Partial molar volume at infinite dilution, (V i ∞ ), and partial molar excess volume at infinite dilution, (V i E ) ∞ , for the components of the mixtures at different temperatures. ...
Experimental densities and viscosities for γ-butyrolactone (GBL) binary mixtures with 1,2,3-trialkyl-substituted imidazolium bis(trifluoromethylsulfonyl)imide ionic liquids, namely: 1-ethyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide [emmim][NTf2], 1,2-dimethyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide [pmmim][NTf2] and 1-butyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide [bmmim][NTf2]) were measured at atmospheric pressure (p = 0.1 MPa) in the temperature range from T = (293.15 to 323.15) K over the whole composition range. From the experimental density data the related excess molar volumes were calculated and fitted using Redlich-Kister’s polynomial equation. The thermal expansion coefficients were also calculated from the acquired experimental density values. The influence of C-2 methyl group and effects of the alkyl side chain length of the 1,2,3-trialkylimidazolium ionic liquids on the nature of interactions and hydrogen bonding in the studied binary mixtures with GBL were discussed. Volumetric and transport properties of GBL binary mixtures with selected ILs are compared with available literature data for the corresponding 1,3-dialkyl-supstituted imidazolium based ionic liquids.
... These fluctuations might reflect the instability of the EMIm + cation against Li metal because of its acidic proton at the C-2 position, [54] which has inspired investigation of different C-2 substituted ILs. [55,56] The reaction of the acidic proton with lithium negative electrode will produce imidazole carbene that can form big dimers or result in dimer cations from the decomposed species, [54] which can diffuse to the carbon positive cathode and be reduced, with or without precipitation depending on a variety of factors such as solubility and accessibility of solvent washing. It is more evident from the C 1s spectra that the contribution from the EMIm + cation decomposition is significantly increased when the cell is fully discharged. ...
The formation of the solid electrolyte interphase (SEI) in an ionic liquid electrolyte of 0.5 m lithium bis(fluorosulfonyl)imide (LiFSI) in 1‐ethyl‐3‐methylimidazolium bis(fluorosulfonyl)imide at high cell voltages (1.7–1.9 V) is investigated in ordered mesoporous carbon (OMC) based Li metal cells using an operando small‐angle neutron scattering (SANS) technique coupled with electrochemical impedance spectroscopy and ex situ X‐ray photoelectron spectroscopy (XPS). It is demonstrated that discharging the OMC Li metal cells to ≈2 V and holding the cell voltage constant induces a rapid current increase with time, confirming extensive reduction and SEI formation. XPS analysis reveals that LiF is formed at open cell voltage (OCV), which is attributed to the carbenes generated at the lithium negative electrode because of its reaction with EMIm cation diffusing to and initiating the reaction with FSI⁻ anions at the carbon positive electrode. It is confirmed that the chemical reaction at OCV and electrochemical reduction at high cell voltage of the FSI⁻ anion plays a protective role against EMIm cation co‐intercalation into the carbon positive electrode during the initial discharge. Operando SANS studies also suggest that slight differences occur in the surface composition and reaction mechanism as a function of cell voltage.
... The preferential formation of the 1,3-alternate conformer of thiacalix[4]arene occurs in the presence of a cesium cation whose size is compatable with that of the thiacalix[4]arene cavity and thus contributes significantly to the cation-p interaction. [5] Receptor L1 could therefore be obtained in 55 % yield by the stereoselective O-alkylation of 1 [10] with 2-chloromethyl-1-methyl-1H-imidazole [9] in the presence of Cs 2 CO 3 in dry acetone (Scheme 1). Similarly, receptor L2 was obtained in 44 % yield by the stereoselective O-alkylation of 2 [11] with 2-chloromethyl-1-methyl-1H-imidazole in the presence of Cs 2 CO 3 in dry acetone (Scheme 1). ...
Two novel receptors 5,11,17,23-tetra-tert-butyl-25,27-bis[(ethoxy-carbonyl)methoxy]-26,28-bis-[1-methyl-(imidazole)meth-oxy]-2,8,14,20-tetra-thiacalix[4]arene (L1) and 5,11,17,23-tetra-tert-butyl-25,27-bis-[(benzyl)methoxy]-26,28-bis-[1-methyl-(imidazole)-methoxy]-2,8,14,20-tetrathiacalix[4]arene (L2) possessing imidazole moieties based on thia-calix[4]arene in the 1,3-alternate conformation have been synthesized and characterized. The crystal structures of L1 and L2 have been determined. The binding behaviour towards Li + , Na + , K + and Ag + ions has been examined by 1 HNMR titration experiments in (CDCl 3 /CD 3 CN; 10:1, v/v) solution. The exclusive formation of mononuclear complexes of L1 with metal cations is of particular interest revealing a negative allosteric effect in the thiacalix[4]arene family. Liquid-liquid extraction experiments indicate that synthesized L2 can be utilized as an efficient reusable extractant for dichromate anion by controlling the pH of the aqueous solution.
... The C-H cyanation of N-alkylimidazoles takes advantage of N-cyano-4-(N,N-dimethylamino)pyridinium bromide (CAP), which is generated in situ from BrCN and DMAP (eq 50). 110 The use of BrCN instead of CAP to synthesize similar compounds leads to both 2-bromoimidazole and N-cyanoimidazole, although nonselectively (see eq 26 in the first update). 86 Using a combination of ClCN and Et 3 N is also effective for producing 2-cyanoimidazole (see eq 7 in Original Commentary The direct cyanation of terminal alkynes is efficiently catalyzed by Cu 2 (OTf) 2 in the presence of a bulky secondary amine, such as 2,2,6,6-tetramethylpiperidine (TMP), to give alkynyl cyanides in good yields (eq 53). ...
Imidazole is a five-membered heterocyclic ring containing three carbon atoms, two nitrogen atoms, and two double bonds. Among two nitrogen atoms, one of which carries with a hydrogen atom is a pyrrole-type nitrogen atom, another is a pyridine type nitrogen atom. Hence, the imidazole ring belongs to the π electron-rich aromatic ring and can accept strong suction to the electronic group. Moreover, the nitrogen atom of the imidazole ring is coordinated with metal ions to form metal-organic frameworks. In recent years, because of imidazole compounds' unique optical properties, their applications have attracted more and more attention in optical analysis. Thus, this review has summarized the synthesis, characterization, and application with emphasis on the research progress of imidazole compounds in optical analysis, including fluorescence probe, colorimetric probe, electrochemiluminescence sensor, fiber optical sensor, surface plasmon resonance, etc. This paper will suggest the direction for the development of imidazole-containing sensors with high sensitivity and selectivity.
The development of materials with intrinsic synergistic properties has attracted great interest in the fields of chemistry and materials science. This article describes the design of and a concise two-step synthetic route to twenty N-alkyl pyrimidinium ionic liquids with the ability to be used as reaction media and antibacterial agents. These synergistic materials have been synthesized by the N-alkylation of pyrimidine, a precursor of nucleobases, with varied n-alkyl (C1-C10) halides followed by anion metathesis of the resulting pyrimidinium halides using the salt of the counter anions, tetrafluoroborate (BF4⁻) and bis(trifluoromethanesulfonyl)amide (NTf2⁻) in good to excellent yields. With these newly synthesized quaternized pyrimidinium ionic liquids (PyrILs), the studies of solubility/miscibility in common solvents, solute-solvent interactions using UV-visible spectroscopy, compatibility as a designed solvent for chemical reactions and evaluation of antimicrobial properties were conducted. The assessment of biological properties of all the PyrILs with BF4⁻ counteranion against several microorganisms revealed that the [C9Pyr]BF4 and [C10Pyr]BF4 containing longer alkyl chains are potential antibacterial agents showing excellent bioactivity against both Gram-positive S. aureus (MIC = 8 and 4 μg mL⁻¹, respectively), and Gram-negative E. coli bacteria (MIC = 8 and 4 μg mL⁻¹, respectively).
[Cu(L1)Cl2]∙3H2O (1) and [Cu(L2)Cl]∙2H2O (2) based on new unsymmetrical tripodal ligands (L1 = {(N-methyl-imidazolylmethyl)[N-methyl-N-(N-methyl-imidazolylmethyl)imidazolylmethyl]amino}ethanesulfonic acid, L2 = [bis(2-pyridylmethyl)amino]ethanesulfonic acid) have been synthesized and characterized by elemental analysis, IR and single-crystal X-ray diffraction. In the discrete mononuclear structures of 1 and 2, copper is five-coordinate in a distorted trigonal bipyramidal structure. Interaction of the complexes with CT-DNA was investigated by UV-Vis spectra, fluorescence spectra and viscosity; the data reveal that 1 and 2 bind to CT-DNA by partial intercalation. Gel electrophoresis assays demonstrate that these two complexes display efficient oxidative cleavage of supercoiled DNA in the presence of H2O2, and MTT assays indicated that both 1 and 2 showed significant cytotoxicity towards Human hepatoma cell HepG-2.
Novel poly(1-vinyl imidazole) p(VI) cryogels were synthesized via cryopolymerization technique where simultaneous polymerization and crosslinking occur around ice crystals under freezing conditions. The superporous p(VI) cryogels were modified with various alkyl bromides possessing different chain lengths such as 1.2-Dibromoethane (1,2-BE), 1.4-Dibromobutane (1,2-BB) and 1.6-Dibromohexane (1,6-BH), and used as template for in situ metal nanoparticle (M) synthesis (M: Co0 or Ni0). The prepared p(VI)-M cryogel composites were used in hydrogen (H2) generation from the hydrolysis of sodium borohydride (NaBH4). Very high turnover frequency (TOF) and H2 generation rate (HGR) values, of 34.4 (mol H2) (mol catalyst min)−1 and 14566.9 (mL H2) (min)−1 (g of M)−1, respectively, were obtained at 70 °C for 3rd time Co (II) loaded and reduced 1.2-BE modified p(VI)-Co composite catalyst system compared with other imidazole-based catalyst systems reported in the literature. Moreover, modified p(VI) cryogels possess inherently magnetic behavior even after a single Co(II) loading-reduction step. Due to their superior properties, such as being recoverable via external applied magnetic field, fast HGR, and reusability, 1.2-BE-p(VI)-Co metal composites were found to be a highly attractive catalyst system for catalytic hydrolysis of NaBH4.
Imidazolium cations with butyl groups at various substitution positions (N1-, C2-, and N3-), 1-butyl-2,3-dimethylimidazolium ([N1-BDMIm]+), 2-butyl-1,3-dimethylimidazolium ([C2-BDMIm]+), and 3-butyl-1,2-dimethyl- imidazolium ([N3-BDMIm]+) were synthesized. Quantitative 1H NMR spectra and density functional theory calculation were applied to investigate the chemical stability of the imidazolium cations in alkaline solutions. The results suggested that the alkaline stability of the imidazolium cations was drastically affected by the C2-substitution groups. The alkaline stability of imidazolium cations with various substitution groups at C2- position, including 2-ethyl-1-butyl-3-methylimidazolium ([C2-EBMIm]+), 1,2-dibutyl-3-methylimidazolium ([C2-BBMIm]+), and 2-hydroxymethyl-1-butyl-3- methylimidazolium ([C2-HMBMIm]+)) was further studied. The butyl groups substituted imidazolium cation ([C2-BBMIm]+) exhibited the highest alkaline stability at the elevated temperatures. The synthesized anion-exchange membranes based on [C2-BBMIm]+ cation showed promising alkaline stability. These observations should pave way to the practical application of imidazolium-based anion exchange membrane fuel cells.
Phosphine, palladacycle, and N-heterocyclic carbene palladium complexes are highly active homogeneous catalysts that can promote a wide range of CC and CN cross-coupling reactions. An evolution from homogeneous catalysis has been to anchor these complexes in a platform in such a way that the catalytic reaction still occurs in homogeneous phase, but the palladium complex can be recovered at the end of the reaction and reused to promote consecutive reactions. In the present review we describe those strategies to develop palladium complexes anchored to soluble polymers and ionic liquids showing the advantages and limitations of this approach to develop recyclable palladium catalysts.
Imidazolium cations, such as those commonly used in preparing
ionic liquids (ILs) can easily be derivatized to include task-specific
functionality, such as metal ligating groups that when used as part of the
solvent or doped into less expensive ILs, dramatically enhance the
partitioning of targeted metal ions into the IL phase from water; the
strategy of preparing task-specific ILs is applicable to a wide range of
designer solvent needs.
Ionic liquids are liquids composed completely of ions. In the past two decades, ionic liquids have been widely used as "green solvents" replacing traditional organic solvents for organic synthesis and catalysis. In addition, ionic liquids are playing an increasingly important role in separation science. In this Account, the application of ionic liquids in all areas of separation science including extractions, gas chromatography, and supported liquid membrane processes are highlighted.
Using imidazole as the starting material, the synthesis of a new bicyclic ionic liquid [b-3C-im][NTf2] is described. Except for the alkylation reaction in the second step (40% yield) of this four-step synthesis of [b-3C-im][NTf2], others were all high yielding reactions (85-94% isolated yields). We investigated intrinsic reactivity of this and other imidazolium-based ionic liquids and found that, under strongly basic conditions (KOD in CD3OD/D2O (1:1) solution), the new ionic liquid was stable to solvent deuterium isotope exchange while the previously reported [bdmim][NTf2] and [bdmim][PF6] ionic liquids were 50% deuterium exchanged at its C-2 methyl in 30 min at ambient temperature. At the same experimental condition, the most commonly employed [bmim][PF6] ionic liquid was deuterium exchanged instantaneously at its C-2 hydrogen. In the absence of bases (CD3OD/D2O = 1: 1), only [bmim][PF6] was deuterium exchanged (50% within I h) and other ionic liquids gave no detectable exchanges even after one week at ambient temperature. It is therefore concluded that the new [b-3C-im][NTf2] ionic liquid is far more chemically stable than previously reported [bmim][PF6], [bdmim][NTf2], and [bdmim][PF6] (c) 2006 Elsevier Ltd. All rights reserved.
Twelve main-chain-type polymerized ionic liquids that have alkylimidazolium cation units were prepared using simple synthetic processes. The polymers were prepared using the self-polymerization of a single monomer; no polymerization initiators were required. The thermal stability and solvent miscibility of these polymers were studied. Results show that the combined anions greatly influence the solubility and thermal stability of the polymers. Among these polymers, poly-alkylimidazolium bis(trifluoromethylsulfonyl)imide polymers exhibited the highest thermal stability (>400 °C), which makes them candidates for many applications.
A series of novel air and water stable low melting salts based upon the 1-ethyl-3-methylimidazolium cation (EtMeim+) have been prepared and characterized; two salts, [EtMeim]BF4 and [EtMeim]MeCO2, are liquids under ambient conditions.
Dimethylaminopyridine activates cyanogen bromide towards C-C bond formation by forming 1-cyano-4-dimethylaminopyridinium bromide. The latter serves as a convenient reagent for the synthesis of 2-cyanoimidazoles.
Low yields are obtained when the Baylis–Hillman reaction is conducted in the presence of an imidazolium-based ionic liquid due to direct addition of the deprotonated imidazolium salt to the aldehyde. Ionic liquids are evidently not inert.
We previously reported the use of imidazole as starting compound for preparing a bicyclic imidazolium ionic liquid, [b-3C-im][NTf2], with an overall 29% isolated yield in four synthetic steps. This new room temperature ionic liquid was shown to be far more chemically stable than commonly used [bmim][PF6], [bdmim][PF6], and [bdmim][NTf2]. Because of this intriguing chemical stability, it prompted us to develop a more generalized and high yielding synthesis so that molecular diversity of bicyclic ionic liquids may be explored. In this work, we amended the previous synthetic route by employing 4-chlorobutyronitrile or 5-chlorovaleronitrile as starting materials and successfully developed a five-step synthesis of a series of novel bicyclic imidazolium-based ionic liquids in 40–53% overall isolated yields. We investigated intrinsic reactivity of all bicyclic ionic liquids prepared and found that, under strongly basic conditions, among all tested ionic liquids the 5,5-membered [R-3C-im][NTf2] ionic liquids were most stable to solvent deuterium isotope exchange while the previously reported [bdmim][NTf2] ionic liquid was 50% deuterium exchanged at its C-2 methyl in 30min at ambient temperature. Under identical condition, the commonly used [bmim][NTf2] ionic liquid was deuterium exchanged instantaneously at its C-2 hydrogen. In the absence of bases, only [bmim][PF6] was deuterium exchanged (50% within 1h) and all other ionic liquids gave no detectable exchanges even after 25 days at ambient temperature. Moreover, both [bmim][NTf2] and [bdmim][NTf2] ionic liquids were readily methylated at C-2 position with methyl iodide under basic condition at room temperature. Under the same condition, [R-3C-im][NTf2] and [R-4C-im][NTf2] ionic liquids were completely stable and chemically inert. We envisioned that [R-3C-im][NTf2] should be well suited as solvents for organic synthesis.
The cathodic stability of the zwitterionic imidazolium compounds was significantly enhanced by the introduction of an ether group at 1 or 2-position on the imidazolium ring. The cycle performance tests showed that the initial cell capacity was maintained almost unchanged up to 100 cycles at 0.5 and 1 C when 2.5wt.% of 2-butoxymethyl-1-methylimidazolium-3-propylsulfonate or 2-butoxymethyl-1-butylimidazolium-3-propylsulfonate was added to the model electrolyte (1M LiPF6 in ethylene carbonate, dimethyl carbonate and ethylmethyl carbonate (1/1/1v/v/v)).Structures of zwitterionic compounds and their interactions with lithium ions were theoretically investigated.
The title N-containing aromatic heterocycles (1, 2, and 4, respectively) with a trimethylsilyl substituent at the 2-position hydrolyze relatively rapidly to form trimethylsilanol and the corresponding 2-H heterocycle. In the case of 2-((trimethylsilyl)methyl)-N-methylimidazole (4) the heterocyclic product is N,2-dimethylimidazole. pH vs. log kobsd profiles establish that the reaction proceeds faster at high than low pH and that above the pKa, of the heterocyclic base the reaction is independent of pH. 2-(Trimethylsilyl)-N-methylpyridinium iodide (6) and 2-(trimethylsilyl)-N-dimethylimidazolium iodide (5) salts hydrolyze with a first-order dependence on [OH-] above pH 6 with no evidence for a pH-independent region at high pH. F- accelerates the reactions of 1 and 2 markedly at low pH but has no effect at pH 12.5. The results indicate that the dominant mechanism for hydrolysis of the title compounds over most of the pH/rate profile involves nucleophilic attack of OH- on the trimethylsilyl unit of the N-protonated base, the leaving group being the zwitterion (ylide) of the heterocycle. The bimolecular constants for attack of OH- on protonated 1 and 2 are comparable to those observed for attack of OH- on 5 and 6, respectively. Compound 1 below pH 5 is attacked by H2O as is 4, but such is not observed for 2. Only compound 4 suffers nucleophilic attack of OH- on the deprotonated base. For 1 and 2 at low pH, P successfully competes with the intrinsically more nucleophilic OH- because the letter's concentration is so low, but at high pH the reaction proceeds entirely via OH- attack.
Four new stable nucleophilic carbenes have been synthesized and structurally characterized. The remarkable ability of the imidazole nucleus to stabilize a carbene center at the C-2 position is demonstrated by the isolation of 1,3,4,5-tetramethylimidazol-2-ylidene. The isolation of three imidazol-2-ylidenes that bear aryl substituents is counter to speculations based on previous reports.
A series of imidazolium-based zwitterionic compounds having both a propylsulfonate group at 3-position and an ester group at 1- or 2-position are synthesized and their interactions with LiPF6 are investigated. FT-IR study and theoretical calculation using density functional theory show that the interactions of the zwitterionic compound with LiPF6 varies significantly with the location of the ester group on the imidazolium ring. The electrochemical stability of the imidazolium-based zwitterionic compound is significantly improved by introducing an ester group at the C-2 position of the imidazolium ring. Cycle performance tests show that the initial cell capacity remains almost unchanged up to 100 cycles at 1/2 C when 2.5 wt.% of 2-(acetoxymethy)-1-butylimidazolium-3-propylsulfonate is added to the model electrolyte consisting of ethylene carbonate (EC), dimethyl carbonate (DMC), and ethylmethyl carbonate (EMC) (EC/DMC/EMC = 1/1/1 v/v/v), whereas the capacity of the cell containing an unsubstituted or methyl-substituted imidazolium compound at the C-2 position, 1-(acetoxymethyl)imidazolium-3-propylsulfonate or 1-(acetoxymethyl)-2-methylimidazolium-3-propylsulfonate as an additive, starts to decrease rapidly just after a few cycles.
Ionic liquids (ILs) are continuing as important media in which to effect various kinds of polymerizations, and it is particularly noteworthy that ionic polymerizations are being developed in IL solvents and that atom transfer radical polymerization (ATRP) catalysts are being attached to ILs to make them more easily recoverable in living polymerizations. In addition, the number of polymerizable ILs is steadily increasing, and ionic liquid polymers of polymerizable ionic liquid monomers have been produced as exotic polyelectrolytes. ILs are being used as plasticizers of various kinds of polymers and as key components in new classes of polymer gels. Polymers and inorganic substrates are being used to support ILs through covalent binding of the ILs, in which case the properties of the IL are modified to some extent, and polymer membranes and porous materials absorb ILs with concomitant changes in ionic conductivity and mobility. New applications of ILs include creating new classes of advanced materials, such as a new class of solvogels that are stimuli responsive and reversibly porate via pinned spinodal decomposition and the development of ILs derived from inorganic nanoparticle cores for use as new resin components for diverse materials and coatings applications.
In the present study, are reported investigations obtained with the room temperature molten salt (RTMS) ethyl-methyl-imidazolium bis-(trifluoromethanesulfonyl)-imide (EMI-TFSI) in order to use it as solvent in lithium battery. The thermal stability, viscosity, conductivity and electrochemical properties are presented. A solution of 1m lithium bis-(trifluoromethanesulfonyl)-imide (LiTFSI) in EMI-TFSI has been used to test the electrolyte in a battery with LiCoO2 and Li4Ti5O12 as respectively cathode and anode materials. Cycling and power measurements have been obtained. The results have been compared with those obtained with a molten salt formulated with a different anion, BF4− and with a conventional liquid organic solvent EC/DMC containing LiTFSI. The 1m LiTFSI/EMI-TFSI electrolyte provides the best cycling performance: a capacity up to 106 mAh g−1 is still delivered after 200 cycles, with 1C rate at 25 °C.
Salts having a low melting point are liquid at room temperature, or even below, and form a new class of liquids usually called room temperature ionic liquids (RTIL). Information about RTILs can be found in the literature with such key words as: room temperature molten salt, low-temperature molten salt, ambient-temperature molten salt, liquid organic salt or simply ionic liquid. Their physicochemical properties are the same as high temperature ionic liquids, but the practical aspects of their maintenance or handling are different enough to merit a distinction. The class of ionic liquids, based on tetraalkylammonium cation and chloroaluminate anion, has been extensively studied since late 1970s of the XX century, following the works of Osteryoung. Systematic research on the application of chloroaluminate ionic liquids as solvents was performed in 1980s. However, ionic liquids based on aluminium halides are moisture sensitive. During the last decade an increasing number of new ionic liquids have been prepared and used as solvents. The general aim of this paper was to review the physical and chemical properties of RTILs from the point of view of their possible application as electrolytes in electrochemical processes and devices. The following points are discussed: melting and freezing, conductivity, viscosity, temperature dependence of conductivity, transport and transference numbers, electrochemical stability, possible application in aluminium electroplating, lithium batteries and in electrochemical capacitors. (c) 2006 Elsevier Ltd. All rights reserved.
An expedient, template-free, high-yield, and solventless route to nitrogen-rich micro- and mesoporous carbons is reported based on direct, atmospheric-pressure carbonization of task-specific ionic liquids bearing one or more nitrile side chains. The resulting textural properties (pore regime, surface area) are highly dependent upon the structural motifs of the ions comprising the corresponding parent ionic liquid, and uniform carbon films are routinely deposited with this novel methodology, highlighting excited new opportunities in the development of advanced functional carbon composites.
A new class of imidazolium salts with appended aminodiacetic acid moieties as di-tert-butyl esters has been synthesized. An improved synthetic route compared to that previously reported is described. These task specific ionic liquids have been used for the formation of metal chelates with Cu(II), Ni(II) and Co(II) in aqueous solutions. The hydrophobicity and solubility of these metal complexes has been fine-tuned by changing the properties of the imidazolium salts from which they are derived through the introduction of alkyl chains onto the imidazolium core.
Ionic liquids are a new class of organic solvents with high polarity and a preorganized solvent structure. Very polar reactions can be carried out in these liquid in the absence of or with a controlled amount of water, and crystalline nanoparticles can be synthesized conveniently at ambient temperatures. The pronounced self-organization of the solvent is used in the synthesis of self-assembled, highly organized hybrid nanostructures with unparalleled quality. The extraordinary potential of ionic liquids in materials synthesis is described in this minireview and a physicochemical explanation is given.
(Chemical Equation Presented) The 2-position of imidazolium cations is known to be relatively acidic, leading to the useful Arduengo-type carbenes. At the same time, the acidity of this site can lead to undesired side reactions when using imidazolium-based ionic liquids as solvents. In this note, we describe the surprisingly facile deuterium exchange at this position and also the synthesis and exchange under modestly basic conditions (triethylamine) of a series of 2-methyl-substituted compounds.
Recent developments in task specifically functionalized imidazolium salts, which can be used for specific tasks ranging from catalysts recycling, supports for organic synthesis, catalysis, separation of specific metal ions from aqueous solution, and construction of nanostructures and ion conductive materials, have been reviewed.
Highly reversible, safe lithium secondary batteries that use imidazolium-cation-based room-temperature ionic liquid as an electrolyte and lithium metal as an anode material were realized by the molecular design. To achieve higher reduction stability, an electron-donating substituent was introduced to promote charge delocalization in the imidazolium cation of room-temperature ionic liquids.
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