共查询到20条相似文献,搜索用时 125 毫秒
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Wragg DS Fullerton GM Byrne PJ Slawin AM Warren JE Teat SJ Morris RE 《Dalton transactions (Cambridge, England : 2003)》2011,40(18):4926-4932
We have carried out a study of aluminophosphate framework synthesis using several amine based ionic liquids and their parent amines as solvent and template. The results suggest that in the presence of fluoride ions from hydrofluoric acid the ionic liquids and their parent amines produce the same frameworks, while in synthesis without fluoride ions the products are not related. The results include the synthesis and crystal structure of a novel extra-large pore material using 1-methylpyrrolidine as solvent and template. The relationship between this and sodalite, which can be synthesised in cobalt aluminophosphate form using an ionic liquid prepared from 1-methylpyrrolidine is described. The crystal structures of two other new layered materials are also presented. 相似文献
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《Tetrahedron letters》2013,54(35):4738-4741
Glucose-linked 1,2,3-triazolium ionic liquids have been synthesized as a new class of chiral solvents by copper(I) catalyzed regioselective cycloaddition of a glucose azide with a glucose alkyne followed by quaternization with methyl iodide. The tagging of glucose to triazolium core makes these molecules act as reusable ligand and solvent in copper(I) catalyzed amination of aryl halides with aqueous ammonia. While the free hydroxyl groups of sugar help in stabilizing copper(I) species during the reaction thus acting as a ligand, the triazolium salt which makes it a liquid at room temperature serves as a reusable solvent. These chiral ionic liquids derived from low-cost natural sources can find utility in various transition-metal catalyzed reactions, and can be explored for asymmetric synthesis in future. 相似文献
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AbstractThe viscosity of neat ionic liquids is very important for their application in organic synthesis as a solvent because most of the neat ionic liquids are very viscous, which would result in the less efficient mass transfer of reactants. In the present study, a series of novel dihydro-[1,2,4]triazolo[1,5-a]pyrimidines were prepared using a low viscous and acid-functionalized ionic liquid. Our results showed that new ionic liquid can act as a green solvent and acid catalyst due to low viscosity and acid functionality. The products were simply extracted and the ionic liquid was retrieved several times without reducing its catalytic efficiency. The current application of TMDPS in the one-pot multicomponent reactions as dual solvent-catalyst highlights the importance of low viscous acid-functionalized ionic liquids in organic synthesis, and we hope that further research will be conducted in the future to finding other applications of TMDPS with promising results. 相似文献
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Synthesis of New Lipid‐Inspired Ionic Liquids by Thiol‐ene Chemistry: Profound Solvent Effect on Reaction Pathway 下载免费PDF全文
Dr. Arsalan Mirjafari Dr. Richard A. O'Brien Dr. Kevin N. West Prof. James H. Davis Jr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(25):7576-7580
The synthesis of a series of new lipid‐inspired ionic liquids through thiol‐ene “click” reaction with a single‐step process. This synthesis offers considerable promise as an efficient and orthogonal method to construct structurally diverse imidazolium‐type ionic liquids with linear and branched cationic tails, as well as versatility in the placement of the sulfur heteroatom. Profound solvent effect in this ene reaction regioselectivity has been observed. 相似文献
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The synthesis of dimethyl carbonate (DMC) from methanol and ethylene carbonate (EC) without using any solvent was investigated
in the presence of ionic liquids as catalysts. The conversion of ethylene carbonate was affected by the structure of ionic
liquid. For a series of 1-alkyl-3-methylimidazolium ionic liquids, the one with shorter alkyl chain and the one with more
nucleophilic anion showed higher reactivity. The conversion of EC also increased with CO2 pressure and reaction temperature. Esterification of EC and methanol can be considered as a pseudo-first order reaction with
respect to EC concentration. The activation energy was estimated as 50.1 kJ/mol. 相似文献
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Massimo Fabris Dr. Vittorio Lucchini Prof. Marco Noè Dr. Alvise Perosa Dr. Maurizio Selva Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(45):12273-12282
This article describes 1) a methodology for the green synthesis of a class of methylammonium and methylphosphonium ionic liquids (ILs), 2) how to tune their acid–base properties by anion exchange, 3) complete neat‐phase NMR spectroscopic characterisation of these materials and 4) their application as active organocatalysts for base‐promoted carbon–carbon bond‐forming reactions. Methylation of tertiary amines or phosphines with dimethyl carbonate leads to the formation of the halogen‐free methyl‐onium methyl carbonate salts, and these can be easily anion‐exchanged to yield a range of derivatives with different melting points, solubility, acid–base properties, stability and viscosity. Treatment with water, in particular, yields bicarbonate‐exchanged liquid onium salts. These proved strongly basic, enough to efficiently catalyse the Michael reaction; experiments suggest that in these systems the bicarbonate basicity is boosted by two orders of magnitude with respect to inorganic bicarbonate salts. These basic ionic liquids used in catalytic amounts are better even than traditional strong organic bases. The present work also introduces neat NMR spectroscopy of the ionic liquids as a probe for solute–solvent interactions as well as a tool for characterisation. Our studies show that high catalytic efficacy of functional ionic liquids can be achieved by integrating their green synthesis, along with a fine‐tuning of their structure. Demonstrating that ionic liquid solvents can be made by a truly green procedure, and that their properties and reactivity can be tailored to the point of bridging the gap between their use as solvents and as catalysts. 相似文献
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MI Xue-Ling LUO San-Zhong HE Jia-Qi CHENG Jin-Pei 《有机化学》2003,23(Z1):176-176
Owing to their unique chemical and physical properties, ionic liquids (ILs) have received focus attention for application as solvent alternatives. ILs can be used in place of organic solvents in synthesis, catalysis, electrochem istry and liquid/liquid extractions. The commonly reported ILs have relied on pyridinium or imidazolium cations bearing simple alkyl groups. 相似文献
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2‐Substituted benzimidazoles have been synthesized in excellent yields under solvent‐free conditions using a series of acidic ionic liquids as catalysts. The results indicate that SO3H‐functionalized ionic liquids show higher catalytic activities than other acidic ionic liquids. The effects of reaction conditions such as the amounts of ionic liquids, the ratio of reactants were investigated. A Hammett method was used to determine the acidity order of these ionic liquids and the results were found to be relevant to the catalytic activities observed in the synthesis reaction. Besides, the reaction mechanism was stimulated using DFT method. 相似文献
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Ralf Giernoth Priv.‐Doz. Dr. 《Angewandte Chemie (International ed. in English)》2010,49(16):2834-2839
In recent years, ionic liquids have attracted the attention of many chemists as a result of their unique properties as solvents for chemical transformations. The focus of this Minireview is on applications of so‐called “task‐specific” ionic liquids, whereby the role of the ionic liquid goes beyond that of a solvent. Such ionic liquids find application in a wide range of areas, including catalysis, synthesis, gas absorption, and analysis. 相似文献
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Solvation and rotational dynamics of coumarin 153 in ionic liquids: comparisons to conventional solvents 总被引:1,自引:0,他引:1
Jin H Baker GA Arzhantsev S Dong J Maroncelli M 《The journal of physical chemistry. B》2007,111(25):7291-7302
Steady-state and time-resolved emission spectroscopy with 25 ps resolution are used to measure equilibrium and dynamic aspects of the solvation of coumarin 153 (C153) in a diverse collection of 21 room-temperature ionic liquids. The ionic liquids studied here include several phosphonium and imidazolium liquids previously reported as well as 12 new ionic liquids that incorporate two homologous series of ammonium and pyrrolidinium cations. Steady-state absorption and emission spectra are used to extract solvation free energies and reorganization energies associated with the S0 <--> S1 transition of C153. These quantities, especially the solvation free energy, vary relatively little in ionic liquids compared to conventional solvents. Some correlation is found between these quantities and the mean separation between ions (or molar volume). Time-resolved anisotropies are used to observe solute rotation. Rotation times measured in ionic liquids correlate with solvent viscosity in much the same way that they do in conventional polar solvents. No special frictional coupling between the C153 and the ionic liquid solvents is indicated by these times. But, in contrast to what is observed in most low-viscosity conventional solvents, rotational correlation functions in ionic liquids are nonexponential. Time-resolved Stokes shift measurements are used to characterize solvation dynamics. The solvation response functions in ionic liquids are also nonexponential and can be reasonably represented by stretched-exponential functions of time. The solvation times observed are correlated with the solvent viscosity, and the much slower solvation in ionic liquids compared to dipolar solvents can be attributed to their much larger viscosities. Solvation times of the majority of ionic liquids studied appear to follow a single correlation with solvent viscosity. Only liquids incorporating the largest phosphonium cation appear to follow a distinctly different correlation. 相似文献
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We describe an efficient synthesis of an ionic liquid-supported TEMPO which was used for the oxidation of alcohols to aldehydes and ketones. The predictable solubility of ionic liquids allows an easy separation of the oxidation products from reagents. Furthermore, the oxidation can be carried out using an ionic liquid as the solvent instead of dichloromethane; and the IL-supported TEMPO can be recycled and used several times without the loss of efficiency. 相似文献
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In recent years, the number of non-aqueous solvents which mediate hydrocarbon-solvent interactions and promote the self-assembly of amphiphiles has been markedly increased by the reporting of over 30 ionic liquids which possess this previously unusual solvent characteristic. This new situation allows a different exploration of the molecular "solvophobic effect" and tests the current understanding of amphiphile self-assembly. Interestingly, both protic and aprotic ionic liquids support amphiphile self-assembly, indicating that it is not required for the solvents to be able to form a hydrogen bonded network. Here, the use of ionic liquids as amphiphile self-assembly media is reviewed, including micelle and liquid crystalline mesophase formation, their use as a solvent phase in microemulsions and emulsions, and the emerging field of nanostructured inorganic materials synthesis. Surfactants, lipids and block co-polymers are the focus amphiphile classes in this critical review (174 references). 相似文献
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Second order rate constants, k2 have been determined for three bi-molecular Diels-Alder reactions to demonstrate that the high viscosity of ionic liquids can be a detrimental property in carrying out Diels-Alder reactions, if ionic liquids are employed as solvent media. It is possible to enhance the reaction rates of the reaction if a co-solvent is mixed in pure ionic liquid used as a solvent. 相似文献
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A. Elia P. Martín Aispuro N. Quaranta J.M. Martín-Martínez P. Vázquez 《Macromolecular Symposia》2011,301(1):136-145
Summary: Although titanium dioxide has a high surface area, it is not thermally stable and its surface area decreases strongly at high temperature due to phase transformation and crystal growth. To improve the thermal stability of titanium dioxide, the synthesis of mixed oxides can be an elegant approach. In this study different experimental variables for the synthesis and characterization of new titania-silica mixed oxides intended to be used as fillers have been proposed. To manufacture the mixed oxides, different tetraethylortosilicate (TEOS)/Tetrabutyl orthotitanate (TBTi) mixtures in different ratio, ethanol as solvent, and acetic acid as catalyst were used via sol-gel synthesis route. These oxides were characterized by transmission electron microscopy coupled with EDX analysis (TEM-EDX), optical microscopy, X-ray diffraction, textural properties, and pH measurements and wettability with liquids of different polarity. 相似文献
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Delannay E Toribio A Boudesocque L Nuzillard JM Zèches-Hanrot M Dardennes E Le Dour G Sapi J Renault JH 《Journal of chromatography. A》2006,1127(1-2):45-51
Nowadays, centrifugal partition chromatography (CPC) separations can be routinely achieved at the laboratory scale. The solvent system selection has been made easy, as generic sets of solvent systems are described in publications and books. This approach, however, generally reduces the scope of optimization strategies for two important parameters: selectivity and sample solubility. This can be very limiting for the preparative separation of structurally similar compounds. Multiple dual-mode (MDM) CPC has been developed to provide an easy-to-use alternative technique to circumvent this problem. A MDM separation consists of a succession of dual-mode runs (i.e. multiple inversion of stationary and mobile phase) that can only be achieved because both chromatographic phases are liquids. This original elution mode is thus a semi-continuous process with a classical sample injection and which only requires a single CPC column. Underlying mechanisms of MDM were studied using a model mixture of acenaphthylene and naphthalene. A mixture of two synthetic pairs of diastereomers was then successfully submitted to MDM CPC, in the framework of the synthesis of biologically active compounds. 相似文献
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MI Xue-Ling LUO San-Zhong HE Jia-Qi CHENG Jin-Pei 《有机化学》2003,23(Z1):177-177
The use of environmentally benign reaction media is very important in view of today' s environmentally con scious attitude. In connect with this, room temperature ionic liquids that are air and moisture stable have received a good deal of attention in recent years as novel solvent systems for organic synthesis. A number of reactions such as Friedel-Crafts reactions, Diels-Alder cycloadditions, hydrogenations, and Heck reactions have employed ionic liquids as solvents. Among them, the Friedel-Crafts reaction[1] is of great synthetic significance in view of laboratory synthesis and industrial production. Recent studies showed that Friedel-Crafts reaction of indole with carbonyl compounds proceeded readily in aqueous media. [2] However, the aqueous reactions suffer from some common problems,such as tedious work-up, reuse of catalyst and so on. 相似文献
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Peter Wasserscheid Dr. 《Chemie in Unserer Zeit》2003,37(1):52-63
Ionic liquids are low melting salts which represent a new class of non-molecular, ionic solvents. By combining different cations and anions a large number of liquids with very different physical and chemical properties can be obtained. It is possible to optimize the ionic medium for a specific application by the careful choice of the ion combination. Ionic liquids are interesting substitutes for organic solvent in catalytic reactions for many reasons: Besides their non-volatile nature offering significant engineering advantages, the unusual solubility properties of these liquids enable new multiphasic catalytic reactions. 相似文献