174501-64-5Relevant academic research and scientific papers
High performance asymmetric supercapacitor based on MnO2 electrode in ionic liquid electrolyte
Zhang, Xuan,Zhao, Dandan,Zhao, Yongqing,Tang, Pengyi,Shen, Yinglin,Xu, Cailing,Li, Hulin,Xiao, Yu
, p. 3706 - 3712 (2013)
In this work, the electrochemical properties of a MnO2 nanocomposite electrode were investigated in 1-butyl-3-methyl-imidazolium hexafluorophosphate ([Bmim]PF6)/N,N-dimethylformamide (DMF) electrolyte. The [Bmim]PF6/DMF electrolyte with different volume fractions exhibits significant influence on the electrochemical properties of the electrode. When the volume ratio of [Bmim]PF6 and DMF was 1:1, the electrode showed the best electrochemical performance. The operation potential window of the MnO2 nanocomposite electrode in ionic liquids was 2.1 V and the specific capacitance according to the mass of MnO2 was 523.3 F g-1 at 3 A g-1. Then, a high-voltage (3 V) MnO2 asymmetric supercapacitor was successfully fabricated, using the MnO2 nanocomposite electrode, activated carbon and [Bmim]PF 6/DMF as the positive electrode, negative electrode and electrolyte, respectively. The MnO2 asymmetric supercapacitor displayed a maximum specific energy of 67.5 W h kg-1 at a specific power of 593.8 W kg-1 and a maximum specific power of 20.4 kW kg-1 at a specific energy of 8.5 W h kg-1. The impressive results showed that [Bmim]PF6/DMF could be a promising electrolyte for MnO2 supercapacitors.
Examination of ionic liquids and their interaction with molecules, when used as stationary phases in gas chromatography
Armstrong, Daniel W.,He, Lingfeng,Liu, Yan-Song
, p. 3873 - 3876 (1999)
Stable room-temperature ionic liquids (RTILs) have been used as novel reaction solvents. They can solubilize complex polar molecules such as cyclodextrins and glycopeptides. Their wetting ability and viscosity allow them to be coated onto fused silica capillaries. Thus, 1-butyl-3- methylimidazolium hexafluorophosphate and the analogous chloride salt can be used as stationary phases for gas chromatography (GC). Using inverse GC, one can examine the nature of these ionic liquids via their interactions with a variety of compounds. The Rohrschneider-McReynolds constants were determined for both ionic liquids and a popular commercial polysiloxane stationary phase. Ionic liquid stationary phases seem to have a dual nature. They appear to act as a low-polarity stationary phase to nonpolar compounds. However, molecules with strong proton donor groups, in particular, are tenaciously retained. The nature of the anion can have a significant effect on both the solubilizing ability and the selectivity of ionic liquid stationary phases. It appears that the unusual properties of ionic liquids could make them beneficial in many areas of separation science.
One-pot and solventless synthesis of ionic liquids under ultrasonic irradiation
Estager, Julien,Lévêque, Jean-Marc,Cravotto, Giancarlo,Boffa, Luisa,Bonrath, Werner,Draye, Micheline
, p. 2065 - 2068 (2007)
A novel method is described for the one-pot synthesis of various ionic liquids in a competitive time. By using ultrasonic irradiation, different families of nitrogen-bearing ionic liquids can be obtained in a solvent-free or in aqueous medium, which gives a greener touch to the overall process. Georg Thieme Verlag Stuttgart.
Association of ionic liquids in solution: Conductivity studies of [BMIM][Cl] and [BMIM][PF6] in binary mixtures of acetonitrile + methanol: Ion association in ionic liquid solutions
Jan, Roohi,Rather, Ghulam Mohammad,Bhat, Mohsin Ahmad
, p. 738 - 745 (2013)
The concentration dependence of molar conductance for 1-butyl-3- methylimidazolium chloride and 1-butyl-3-methylimidazolium hexafluorophosphate in binary mixtures of acetonitrile + methanol was investigated to explore the ion association behavior of imidazolium based ionic liquids. The limiting molar conductance (Λm0), association constants (K a 0) and the maximal distance between the oppositely charged ions in ion pairs (R ij ) in the mixed solvent mixtures were evaluated following the framework of Barthel's low-concentration chemical model. The investigated ILs display opposing trends in ion association behavior with change in solvent composition of acetonitrile + methanol binary mixtures. The results are discussed in light of ionic liquid and solvent specific ion-solvent and ion-ion interactions in the mixed solvent systems.
Effect of temperature on the purity of product in the preparation of 1-butyl-3-methylimidazolium-based ionic liquids
K?rkk?inen, Johanna,Asikkala, Janne,Laitinen, Risto S.,Lajunen, Marja K.
, p. 763 - 770 (2004)
The preparation of room-temperature ionic liquids 1-butyl-3- methylimidazolium chloride, hexafluorophosphate, and dicyanamide by microwave-assisted reaction in non-solvent and solvent conditions has been studied in this contribution. A special emphasis is put on the effect of the reaction temperature on the purity of ionic liquids that was monitored by electrospray ionisation mass spectrometry and 1H NMR. The X-ray structure of 1-butyl-3-methylimidazolium chloride is presented.
Liquid-liquid equilibria of room-temperature ionic liquids and butan-1-ol
Wu,Marsh, Kenneth N.,Deev, Alexander V.,Boxall, John A.
, p. 486 - 491 (2003)
Room-temperature ionic liquids are salts that are liquid at room temperature. Their use as catalysts and catalytic support has been studied extensively. However, there are very few measurements on their solubility and phase equilibria in common organic solvents. In this work, the liquid-liquid phase equilibria of mixtures of room-temperature ionic liquids, 1-alkyl-3-methylimidazolium hexafluorophosphate, [Rnmim][PF6] (1) where Rn = butyl, pentyl, hexyl, heptyl, and octyl, with butan-1-ol (2) over a composition range have been measured. The binodal coexistence curves of the mixtures were found to have an upper critical solution temperature (USCT) at x2 ≈ 0.9. The UCST decreases with increase in the length of the alkyl chain of the ionic liquid, with the UCST of the butyl at 373 K and that of the octyl at 326 K. Both the UCST and the composition at the UCST as a function of the 1-alkyl group chain length can be reasonably well predicted from theory on the basis of unimolecular quantum chemical calculations.
Spectroscopic and photophysical properties of ZnTPP in a room temperature ionic liquid
Szmytkowski, Jedrzej,Bond, Toby,Paige, Matthew F.,Scott, Robert W. J.,Steer, Ronald P.
, p. 11471 - 11476 (2010)
The steady-state absorption and emission spectra and the time-resolved Soret- and Q-band excited fluorescence profiles of the model metalloporphyrin, ZnTPP, have been measured in a highly purified sample of the common room temperature ionic liquid, [bmim][PF6]. S2-S0 emission resulting from Soret-band excitation behaves in a manner completely consistent with that of molecular solvents of the same polarizability. The ionic nature of the solvent and its slow solvation relaxation times have no significant effect on the nature of the radiationless decay of the S2 state, which decays quantitatively to S1 at a population decay rate that is consistent with the weak coupling case of radiationless transition theory (energy gap law). The ratio of the intensities of the Qα:Qβ (0-0:1-0) bands is consistent with the solvatochromic shift correlation data obtained for molecular solvents. The temporal S1 fluorescence decay profiles measured at a single emission wavelength are biexponential; the longer-lived major component is similar to that observed for ZnTPP in molecular solvents, and the minor shorter-lived component is attributed to solvent relaxation processes on a nanosecond time scale.
A rationalization of the solvent effect on the Diels-Alder reaction in ionic liquids using multiparameter linear solvation energy relationships
Bini, Riccardo,Chiappe, Cinzia,Mestre, Veronica Llopsis,Pomelli, Christian Silvio,Welton, Thomas
, p. 2522 - 2529 (2008)
The Diels-Alder reaction between cyclopentadiene and three dienophiles (acrolein, methyl acrylate and acrylonitrile) having different hydrogen bond acceptor abilities has been carried out in several ionic liquids and molecular solvents in order to obtain information about the factors affecting reactivity and selectivity. The solvent effects on these reactions are examined using multiparameter linear solvation energy relationships. The collected data provide evidence that the solvent effects are a function of both the solvent and the solute. For a solvent effect to be seen, the solute must have a complimentary character; selectivities and rates are determined by the solvent hydrogen bond donation ability (α) in the reactions of acrolein and methyl acrylate, but not of acrylonitrile. The Royal Society of Chemistry 2008.
Preparation of second generation ionic liquids by efficient solvent-free alkylation of N-heterocycles with chloroalkanes
Cravotto, Giancarlo,Gaudino, Emanuela Calcio,Boffa, Luisa,Leveque, Jean-Marc,Estager, Julien,Bonrath, Werner
, p. 149 - 156 (2008)
Non-conventional techniques, such as microwave (MW) and power ultrasound (US) as well as combined MW/US irradiation, have been used to promote one-pot synthesis of second-generation ionic liquids (ILs), cutting down reaction times and improving yields. However, the use of chloroalkanes in the alkylation of N-heterocycles requires more drastic conditions if results are to match those obtained with more reactive alkyl halides. The present paper describes a series of MW- or MW/US-promoted IL preparations starting from chloroalkanes and classic heterocycles (1-methylimidazole, pyridine and 1-methylpyrrolidine). When reactions were carried out under conventional heating in an oil bath they required longer reaction times and gave poorer yields. 1H-NMR analysis and ion-exchange chromatography showed that the present solventless procedure afforded ILs of satisfactory purity. The observed high yields (usually 70-98% isolated), and short reaction times showed that a straightforward access to ILs can be also achieved with the use of alkyl chlorides, resulting in a considerable reduction of costs.
Effect of ionic liquids on the conformation of a porphyrin-based viscometer
Jameson, Laramie P.,Kimball, Joseph D.,Gryczynski, Zygmunt,Balaz, Milan,Dzyuba, Sergei V.
, p. 18300 - 18304 (2013)
Structure of the cationic and anionic counterparts of ionic liquids has a significant impact on the conformational bias of the porphyrin rotor; an apparent correlation between the conformation and the viscosity of ionic liquids was noted, albeit it was found to be distinct and more complex from that found in molecular solvents.
