共查询到20条相似文献,搜索用时 31 毫秒
1.
Chloride based ionic liquids were used as chloride source in Meerwein reaction either in [bmim]X (bmim = 1-butyl-3-methylimidazolium, X = BF4, PF6) as solvents or in solventless conditions. Satisfactory yields (49-71%) with diversely substituted diazonium salts were achieved by using 1,3-dibutylimidazolium chloride in the presence of a bimetallic Zn/Cu catalyst. 相似文献
2.
Danette L. AstolfiFrancis C. Mayville Jr. 《Tetrahedron letters》2003,44(51):9223-9224
Two ionic liquids were synthesized, each system consisting of the 1-hexyl-3-methylimidazolium ion ([hmim]+) as the cation and either hexafluorophosphate ([PF6]−), or perchlorate ([ClO4]−) as the anions. This study involves the synthesis of methyl orange (4-[[(4-dimethylamino)phenyl]-azo] benzene sulfonic acid sodium salt) using the ionic liquids as replacement solvents for the reaction. The advantage of using ionic liquids as substitutes for organic solvents includes: recyclable/reclaimable solvents, stabilization of intermediates and higher product yields. The 1-hexyl-3-methylimidazolium derivatives can be used for syntheses conducted at low temperatures and are less toxic than typical organic solvents. 相似文献
3.
Hiroyuki MatsudaKatsumi Tochigi Vincent LiebertJürgen Gmehling 《Fluid Phase Equilibria》2011,307(2):197-201
Vapor-liquid equilibria (VLE) for two binary systems 1-propanol + water and methyl acetate + methanol, and the ternary mixtures with the ionic liquid 1-ethyl-3-methylimidazolium ethyl sulfate [EMIM]+[EtSO4]− as entrainer were measured by headspace gas chromatography. From the experimental VLE data, the influence of the ionic liquid on the separation factors was investigated. The experimental results for the ternary systems show that [EMIM]+[EtSO4]− has a great influence on the separation factors of the systems investigated. Furthermore, the experimental separation factors were compared with the predicted ones of other ionic liquids and conventional selective solvents using modified UNIFAC (Dortmund). 相似文献
4.
Yunchang Fan Meilan Chen Fawzi El-Sepai Yan Zhu Mingli Ye 《Analytica chimica acta》2009,650(1):65-654
A simple analytical method, based on the coupling of ionic liquid-based extraction with high performance liquid chromatography (HPLC), is developed for the determination of Sudan dyes (I, II, III and IV) and Para Red in chilli powder, chilli oil and food additive samples. Two ionic liquids (ILs), 1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim][PF6]) and 1-octyl-3-methylimidazolium hexafluorophosphate ([C8mim][PF6]), were compared as extraction solvents; experiments indicated that the latter possesses higher recoveries for each analyte. Parameters related to extraction of Sudan dyes and Para Red were also optimized. Under the optimal conditions, good reproducibility of extraction performance was obtained, with the relative standard deviation (RSD) values ranging from 2.0% to 3.5%. The detection limits of Sudan dyes and Para Red (LOD, S/N = 3) were in the range of 7.0-8.2 μg kg−1 for chilli powder and 11.2-13.2 μg L−1 for chilli oil and food additive. The recoveries were in the range of 76.8-109.5% for chilli powder samples and 70.7-107.8% for chilli oil and food additive samples. 相似文献
5.
Glycolysis of poly(ethylene terephthalate) (PET) using basic ionic liquids as catalysts 总被引:2,自引:0,他引:2
The glycolysis of poly(ethylene terephthalate) (PET) was studied using several ionic liquids and basic ionic liquids as catalysts. The basic ionic liquid, 1-butyl-3-methylimidazolium hydroxyl ([Bmim]OH), exhibits higher catalytic activity for the glycolysis of PET, compared with 1-butyl-3-methylimidazolium bicarbonate ([Bmim]HCO3), 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) and 1-butyl-3-methylimidazolium bromide ([Bmim]Br). FT-IR, 1H NMR and DSC were used to confirm the main product of glycolysis was bis(2-hydroxyethyl) terephthalate (BHET) monomer. The influences of experimental parameters, such as the amount of catalyst, glycolysis time, reaction temperature, and dosages of ethylene glycol on the conversion of PET, yield of BHET were investigated. The results showed a strong influence of the mixture evolution of temperature and reaction time on depolymerization of PET. Under the optimum conditions of m(PET):m(EG): 1:10, dosage of [Bmim]OH at 0.1 g (5 wt%), reaction temperature 190 °C and time 2 h, the conversion of PET and the yield of BHET were 100% and 71.2% respectively. Balance between the polymerization of BHET and depolymerization of PET could be changed when the reaction time was more than 2 h and contents of catalyst and EG were changed. 相似文献
6.
Sang Wook Kang Dong Hoon Lee Jong Hyuk Park Kookheon Char Jong Hak Kim Jongok Won Yong Soo Kang 《Journal of membrane science》2008
The effect of ionic liquids on the formation of a partial positive charge on the surface of silver nanoparticle and its subsequent effect on facilitated olefin transport were investigated. Three different ionic liquids of 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM+BF4−), 1-butyl-3-methylimidazolium triflate (BMIM+Tf−), and 1-butyl-3-methylimidazolium nitrate (BMIM+NO3−) were employed to control the positive charge density of the surface of silver nanoparticles. The positive charge density of the silver nanoparticles, as characterized by the binding energy of the silver atom, was in the following order: BMIM+BF4−/Ag ? BMIM+Tf−/Ag > BMIM+NO3−/Ag. This order was consistent with the tendency of ionic liquids to form free ions. The best separation performance for the propylene/propane mixtures was a mixed gas selectivity of 17 and a permeance of 7 GPU through a composite membrane consisting of BMIM+BF4−/Ag. A better separation performance for olefin/paraffin mixtures was observed with a higher positive charge density of the silver nanoparticles. It was therefore concluded that facilitated olefin transport was a direct consequence of the surface positive charge of the silver nanoparticles induced by ionic liquids. 相似文献
7.
Room temperature ionic liquids can be considered as environmentally benign solvents with unique physicochemical properties. Ionic liquids can be used as extractant phases in SDME, being compatible with chromatographic systems. A single-drop microextraction method was developed for separation and preconcentration of mercury species (MeHg+, EtHg+, PhHg+ and Hg2+), which relies on the formation of the corresponding dithizonates and microextraction of these neutral chelates onto a microdrop of an ionic liquid. Afterwards, the separation and determination were carried out by high-performance liquid chromatography with a photodiode array detector. Variables affecting the formation and extraction of mercury dithizonates were optimized. The optimum conditions found were: microextraction time, 20 min; stirring rate, 900 rpm; pH, 11; ionic liquid type, 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6MIM][PF6]); drop volume, 4 μL; and no sodium chloride addition. Limits of detection were between 1.0 and 22.8 μg L−1 for the four species of mercury, while the repeatability of the method, expressed as relative standard deviation, was between 3.7 and 11.6% (n = 8). The method was finally applied to the determination of mercury species in different water samples. 相似文献
8.
Anna Chrobok 《Tetrahedron》2010,66(16):2940-2943
A new and efficient method for the synthesis of lactones involving the application of an oxygen/benzaldehyde system as the oxidant and ionic liquids as solvents is reported. A significant rate enhancement was observed at 90 °C when the oxidation of ketones was carried out in the presence of a free radical initiator. The oxidation of model cyclic ketones, such as cyclopentanone, cyclohexanone, 2-methylcyclohexanone, 2-norbornone, 2-adamantanone and cycloheptanone gave lactones in high yields (84-90%) within relatively short periods of time, with the possibility of effective ionic liquids recycling. Additionally, discussion of the free radical mechanism of this reaction is proposed. 相似文献
9.
The amount of available accurate experimental data on the surface tension of ionic liquids is still limited; in many cases the data are rare or even absent. In the present study, air-liquid interfacial tension data were determined experimentally for five 1-Cn-3-methylimidazolium based ionic liquids (n = 2, 4, and 6), three with trifluoromethanesulfonate and two with tetrafluoroborate anion, at atmospheric pressure in the temperature range from 268 to 356 K. The resultant surface tension data are average values of the measurements repeated many times at each set point temperature. The accuracy of the results, was confirmed by employing the Wilhelmy plate and the du Noüy ring methods in parallel, using the Krüss K100MK2 tensiometer. For the Wilhelmy plate data the combined standard uncertainty is estimated to be about 0.05 mN m−1. The data obtained by du Noüy method show about up to seven times greater scatter than those obtained by the Wilhelmy plate method. To the 50 up to now published surface tension values for the five studied ionic liquids the present study adds further 175 data points. In contrast to that of n-alkanes, the surface tension of 1-alkyl-3-methylimidazolium based ionic liquids decreases and their surface entropy increases with the cation alkyl chain length. 相似文献
10.
《Comptes Rendus Chimie》2014,17(5):450-453
A task-specific ionic liquid as an environmentally eco-friendly green catalyst has been synthesized and used in the ring opening of epoxides under green conditions. In order to use protic ionic liquids (PIL), we decided to synthesize 1,2-azidoalcohols via a ring opening reaction of epoxides with 1-hydrogen-3-methylimidazolium azide ([Hmim]N3), which actually acts as a solvent, a reagent and an activator of the epoxide ring. The reaction was carried out in short times (50–70 min) at 70 °C to give 1,2-azidoalcohol in 80–94% isolated yields. 相似文献
11.
A series of acidic task-specific ionic liquids 1-R2-2-R1benzimidazolium tetrafluoroborate (R1 = Me, R2 = Me, Et, Pr-n, Bu-n, Pen-n) were prepared by simple acid-base neutralization of the corresponding 1-alkylbenzimidazole and tetrafluoroboric acid. The compounds were characterized by FTIR spectra, elemental analysis, 1HNMR spectra and thermogravimetric analysis. These new ionic liquids are nonvolatile, and have potential use as alternatives to conventional organic solvents due to their solubility and thermal stability. These novel tetrafluoroborate salts show good catalytic activity to esterification of carboxylic acids with alcohols under mild reaction conditions, which could maintain good catalytic performance after recycling at least six times. Furthermore, a crystal of one compound, [H-bmBim]BF4, was prepared, with the crystal structure determined by X-ray diffraction analysis. The molecular structure is formed by weak π-π interactions and intermolecular hydrogen bonds between the benzimidazole rings, yielding a three-dimensional net-like supramolecule. 相似文献
12.
Saeed Balalaie Ali Poursaeed Malihe Javan Khoshkholgh Hamid Reza Bijanzadeh Eckardt Wolf 《Comptes Rendus Chimie》2012,15(4):283-289
Immobilized ZrO2-nanopowder (NP) in ionic liquid and different organic solvents was used as a suitable Lewis-acid for the synthesis of polycyclic heterocycles which contains pyran-based skeletons. Reaction of O-propargylated salicylaldehyde with active methylene compounds in the presence of ZrO2-NP in ionic liquid proceeds via domino Knoevenagel hetero Diels-Alder reaction of unactivated alkynes to construct the pyran skeleton. Comparison with different ionic liquids and organic solvents showed that the best results were obtained with 1-butyl-3-methylimidazolium nitrate [bmim][NO3] because of short reaction times and high yields. Carrying out the reaction under these conditions has advantages such as: high yields, short reaction times and easy work-up. 相似文献
13.
Possible use of room temperature ionic liquids (RTILs) as chelate extraction solvent was evaluated by using 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]), 1-hexyl-3-methylimidazolium hexafluorophosphate ([hmim][PF6]) and 1-octyl-3-methylimidazolium hexafluorophosphate ([omim][PF6]). These RTILs showed high extraction performance for divalent metal cations with 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione (Htta). The extracted metals were back-extracted into 1 mol dm−3 nitric acid quantitatively. Furthermore, the extracted species were estimated as neutral hydrated complexes M(tta)2(H2O)n (n= 1 or 2) for M = Ni, Cu and Pb and anionic complexes M(tta)3− for M = Mn, Co, Zn and Cd. 相似文献
14.
Ana Serbanovic Manuel Nunes da Ponte Carlos A.M. Afonso 《Journal of organometallic chemistry》2005,690(15):3600-3608
In this work, osmium-catalyzed asymmetric dihydroxylation (AD) of methyl trans-cinnamate was studied. Osmium and chiral ligand catalysts were immobilized in ionic liquid only, without any other reaction solvents, while the recovery of the product was performed by extraction with supercritical CO2, and compared with results obtained by extractions with organic solvents such as hexane and diethyl ether. In supercritical CO2 extraction experiments, optimal extraction pressure was found and ionic liquid chosen, so that the highest reaction yields coupled with lowest osmium content in the crude product can be achieved. Finally, recycle experiments of the same (ionic liquid + catalytic system) mixture were successfully conducted. Application of ionic liquids and supercritical CO2 in osmium catalyzed AD allows for the isolation of the diol basically without contamination with osmium, in high yield and enantiomeric excess, and it makes possible the efficient reuse of ionic liquid solvent and the catalytic system. 相似文献
15.
Comparative Investigation of the Ionicity of Aprotic and Protic Ionic Liquids in Molecular Solvents by using Conductometry and NMR Spectroscopy
下载免费PDF全文
![点击此处可从《Chemphyschem》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Electrical conductivity (σ), viscosity (η), and self‐diffusion coefficient (D) measurements of binary mixtures of aprotic and protic imidazolium‐based ionic liquids with water, dimethyl sulfoxide, and ethylene glycol were measured from 293.15 to 323.15 K. The temperature dependence study reveals typical Arrhenius behavior. The ionicities of aprotic ionic liquids were observed to be higher than those of protic ionic liquids in these solvents. The aprotic ionic liquid, 1‐butyl‐3‐methylimidazolium tetrafluoroborate, [bmIm][BF4], displays 100 % ionicity in both water and ethylene glycol. The protic ionic liquids in both water and ethylene glycol are classed as good ionic candidates, whereas in DMSO they are classed as having a poor ionic nature. The solvation dynamics of the ionic species of the ionic liquids are illustrated on the basis of the 1H NMR chemical shifts of the ionic liquids. The self‐diffusion coefficients D of the cation and anion of [HmIm][CH3COO] in D2O and in [D6]DMSO are determined by using 1H nuclei with pulsed field gradient spin‐echo NMR spectroscopy. 相似文献
16.
Xiangai Yuan Yangjun Ding Lingjun Liu Min Sun Dongdong Dong 《Journal of organometallic chemistry》2010,695(4):552-3860
A DFT study was carried out to investigate the reaction mechanisms of a model μ-benzoquinone diruthenium complex {CpRu(μ-H)}2(μ-η2:η2-C6H4O2), derived from the experimental compound {Cp*Ru(μ-H)}2(μ-η2:η2-C6H3RO2) (R = H or R = Me, Cp* = η5-C5Me5), with acetylene both in aprotic and protic solvents. Results of calculations show that the influence of the solvent methanol on the reaction is mainly on the step of acetylene coordination. Enhanced hydrogen bonding is the reason for acceleration of the reaction in protic solvent, which is supported by NBO charge analysis. 相似文献
17.
Several imidazolium-based ionic liquids (ILs) with varying cation alkyl chain length (C4–C10) and anion type (tetrafluoroborate ([BF4]−), hexafluorophosphate ([PF6]−) and bis(trifluoromethylsulfonyl)imide ([Tf2N]−)) were used as reaction media in the microwave polymerization of methacrylate-based stationary phases. Scanning electron micrographs and backpressures of poly(butyl methacrylate-ethylene dimethacrylate) (poly(BMA-EDMA)) monoliths synthesized in the presence of these ionic liquids demonstrated that porosity and permeability decreased when cation alkyl chain length and anion hydrophobicity were increased. Performance of these monoliths was assessed for their ability to separate parabens by capillary electrochromatography (CEC). Intra-batch precision (n = 3 columns) for retention time and peak area ranged was 0.80–1.13% and 3.71–4.58%, respectively. In addition, a good repeatability of RSDRetention time = <0.30% and ∼1.0%, RSDPeak area = <1.30% and <4.3%, and RSDEfficiency = <0.6% and <11.5% for intra-day and inter-day, respectively exemplify monolith performance reliability for poly(BMA-EDMA) fabricated using 1-hexyl-3-methylimidazolium tetrafluoroborate ([C6mim][BF4]) porogen. This monolith was also tested for its potential in nanoLC to separate protein digests in gradient mode. ILs as porogens also fabricated different alkyl methacrylate (AMA) (C4–C18) monoliths. Furthermore, employing binary IL porogen mixture such as 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]) and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C4mim][Tf2N]) successfully decreased the denseness of the monolith, than when using [C4mim][Tf2N] IL alone, enabling a chromatographic run to be performed with 1:1 ratio produced baseline separation for the analytes. The combination of ILs and microwave irradiation made polymer synthesis very fast (∼10 min), entirely green (organic solvent-free) and energy saving process. 相似文献
18.
Rafał Bogel-Łukasik Dobrochna Matkowska Ewa Bogel-Łukasik Tadeusz Hofman 《Fluid Phase Equilibria》2010
Vapour–liquid equilibrium measurements for binary and ternary systems containing carbon dioxide, 1-propanol, and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide or 1-decyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide or 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ionic liquids are presented in this work. The binary CO2 + 1-decyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide system at 313.15 K at pressure range from 2 to 14.4 MPa was examined. The obtained phase envelop shows that even at low pressure of CO2 the solubility of the gas in the ionic liquid is high. The ternary phase equilibria were studied at 313.15 K and pressures in the range from 9 to 12 MPa. The ternary phase diagrams show that higher CO2 pressure diminishes the miscibility gap. 相似文献
19.
In this research, a novel microextraction technique based on ionic liquids (ILs) termed cold-induced aggregation microextraction (CIAME) is developed. In this method, very small amounts of 1-hexyl-3-methylimidazolium hexafluorophosphate [Hmim][PF6] and 1-hexyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide [Hmim][Tf2N] (as extractant solvents) were dissolved in a sample solution containing Triton X-114 (as an anti-sticking agent). Afterwards, the solution was cooled in the ice bath and a cloudy solution was formed. After centrifuging, the fine droplets of extractant phase were settled to the bottom of the conical-bottom glass centrifuge tube.CIAME is a simple and rapid method for extraction and preconcentration of metal ions from water samples and can be applied for the sample solutions containing high concentration of salt and water miscible organic solvents. Furthermore, this technique is much safer in comparison with the organic solvent extraction.Performance of the technique was evaluated by determination of the trace amounts of mercury as a test analyte in several real water samples. Michler thioketone (TMK) was chosen as a complexing agent. Analysis was carried out using spectrophotometric detection method. Type and amount of IL and the surfactant, temperature and the other parameters were optimized. Under the optimum conditions, the limit of detection (LOD) of the method was 0.3 ng mL−1 and the relative standard deviation (R.S.D.) was 1.32% for 30 ng mL−1 mercury. 相似文献
20.
Kazuhiko Matsumoto 《Journal of fluorine chemistry》2005,126(7):1095-1100
The first room temperature ionic liquid (room temperature molten salt) containing oxyfluorometallate anion, 1-ethyl-3-methylimidazolium oxypentafluorotungstate (EMImWOF5), has been synthesized and characterized compared to other known EMIm fluorocomplex salts. EMImWOF5 is synthesized by two routes: one is the hydrolysis of EMImWF7 and the other is the fluoroacid-base reaction of EMIm(HF)2.3F and WOF4. EMImWOF5 is a hydrophilic room temperature ionic liquid but is stable in aqueous solution. From the result of DSC analysis, EMImWOF5 exhibits a glass transition at 182 K and melts at 253 K. The density, conductivity and viscosity at 298 K are 2.25 g cm−3, 3.0 mS cm−1 and 105.1 cP, respectively. 相似文献