Search results for "ionic liquids"
showing 10 items of 186 documents
Gelled Electrolyte Containing Phosphonium Ionic Liquids for Lithium-Ion Batteries
2018
In this work, new gelled electrolytes were prepared based on a mixture containing phosphonium ionic liquid (IL) composed of trihexyl(tetradecyl)phosphonium cation combined with bis(trifluoromethane)sulfonimide [TFSI] counter anions and lithium salt, confined in a host network made from an epoxy prepolymer and amine hardener. We have demonstrated that the addition of electrolyte plays a key role on the kinetics of polymerization but also on the final properties of epoxy networks, especially thermal, thermo-mechanical, transport, and electrochemical properties. Thus, polymer electrolytes with excellent thermal stability (>
Task-specific ionic liquid for the depolymerisation of starch-based industrial waste into high reducing sugars
2014
Development of a simple route for the catalytic conversion of starch-based industrial waste (potato peels) and potato starch into reducing sugars was investigated in two ionic liquids for comparison – 1-allyl-3-methylimidazolium chloride [AMIM]Cl and 1-(4-sulfobutyl)-3-methylimidazolium chloride [SBMIM]Cl. Over a two hour period, a 20 wt% solution containing up to 43% and 98% of reducing sugars at low temperature in aqueous [SBMIM]Cl was achieved for the starch-based waste and the potato starch, respectively. In addition, the use of microwave and low frequency ultrasound to perform the depolymerisation of the raw starch-based material was explored and compared with conventional heating proc…
Effect of buffer nature and concentration on the chromatographic performance of basic compounds in the absence and presence of 1-hexyl-3-methylimidaz…
2019
Abstract In reversed-phase liquid chromatography, the performance for basic compounds is affected by the interaction of the protonated (cationic) species with the anionic free silanols on the alkyl-bonded stationary phases. Using aqueous-organic mobile phases in the absence of additives, the retention may be too high, and the peaks be broad and asymmetric. The performance is improved by addition to the mobile phase of ionic liquids, from which 1-hexyl-3-methylimidazolium chloride ([C6MIm][Cl]) has especially good characteristics. A recent report has also revealed that the use of the phosphate system as buffer, at varying concentration and pH, may have a significant role in the chromatograph…
Water-Tolerant Trifloaluminate Ionic Liquids: New and Unique Lewis Acidic Catalysts for the Synthesis of Chromane
2018
The first example of triflometallate ionic liquids, named in analogy to chlorometallate ionic liquids, is reported. Trifloaluminate ionic liquids, synthesised from 1-alkyl-3-methylimidazolium triflates and aluminium triflate, were characterised by multinuclear NMR spectroscopy and FT-IR spectroscopy, revealing the existence of oligonuclear, multiply-charged trifloaluminate anions, with multiple bridging triflate modes. Acceptor numbers were determined to quantify their Lewis acidity, rendering trifloaluminate ionic liquids as medium-strength Lewis acids (AN = ca. 65). Used as acidic catalysts in the cycloaddition of 2,4-dimethylphenol and isoprene (molar ratio 2:1) to prepare chromane, trif…
Influence of Anion and Cation Structure of Ionic Liquids on Carboxylic Acids Extraction
2019
A recently proposed new mechanism and a model of reactive extraction of carboxylic acids by hydrophobic ionic liquids (ILs) was tested on five systems from published as well as from new equilibrium data on liquid-liquid extraction of butyric and lactic acids (BA and LA) from aqueous solutions. Two phosphonium and one ammonium ILs were used. The model describes experimental data for all systems with a good fit. The mechanism of acid extraction by ILs is very similar for all tested systems. This indicates a more general validity of the developed model. The model allows deeper understanding of regularities in carboxylic acid extraction by hydrophobic ILs. Stability constants of the first acid-…
Silanol suppressing potency of alkyl-imidazolium ionic liquids on C18 stationary phases
2011
Residual silanols on C18 columns yield undesirable slow-kinetics ion-exchange interactions with positively charged basic compounds that result in asymmetrical peaks, low efficiencies and long retention times. The purity of the silica employed as supporting material, and the technique used to form the bonded phase, which varies with the brand and manufacturer, give rise to different amounts of residual silanols in the packings, and consequently, different chromatographic performance. One of the most efficient and widespread strategies to reduce or even eliminate the different performance among columns is the addition of a reagent to the mobile phase to block the silanol sites. However, the i…
The ultrasounds-ionic liquids synergy on the copper catalyzed azide-alkyne cycloaddition between phenyl acetylene and 4-azidoquinoline
2015
Abstract The effect of ultrasound irradiation on the copper catalyzed azide–alkyne cycloaddition between phenylacetylene and 4-azidoquinoline has been studied in solution of different ionic liquids. In particular, we used ionic liquids featuring both aliphatic and aromatic mono- and dications, as well as anions differing in size, symmetry and coordination ability. We also examined the influence of the ionic liquids structural features on the reaction outcomes, finding that under magnetic stirring reactivity is favorably affected by the solvent structural organization, while under sonochemical conditions an opposite trend was observed. In all cases examined, sonochemical activation leads to …
p-Nitrophenolate: A Probe for Determining Acid Strength in Ionic Liquids
2009
In order to obtain an acidity scale in room-temperature ionic liquid solutions, the protonation equilibrium of sodium p-nitrophenolate in [bm(2)im][NTf(2)] and in [bmpyrr][NTf(2)], at 298 K, has been studied by means of spectrophotometric titration. Carboxylic acids differing in both structure and in water solution strength have been used. Data collected indicate that in the analyzed ionic liquid solutions carboxylic acids are less dissociated than in water solution. Furthermore, by virtue of a mutual interaction, the studied equilibrium seems to be affected by both the nature of the ionic liquids and the carboxylic acids.
Viologen-based ionic liquid crystals: induction of a smectic A phase by dimerisation.
2014
The stability of thermotropic ionic liquid crystals is essentially due to micro-phase segregation between the ionic heads and the long alkyl chains. Here we show, using newly synthesized viologen dimers, that the structure of the central core is another key parameter to play with in order to tune the mesomorphic behaviour. © 2014 the Owner Societies.
Insights into the Formation and Structures of Molecular Gels by Diimidazolium Salt Gelators in Ionic Liquids or “Normal” Solvents
2016
Insights are provided into the properties of molecular gels formed by diimidazolium salts both in “normal” solvents and ionic liquids. These materials can be interesting for applications in green and sustainable chemistry in which ionic liquids play a significant role, like catalysis and energy. In particular, two positional isomers of a diimidazolium cation have been examined with a wide range of anions for their ability to form gel phases. In particular, di-, tri-, and tetravalent anions bearing aliphatic or aromatic spacers were paired with the divalent cations. The properties of the organo- and ionogels formed have been analyzed by means of several different techniques, including calori…