- Electrolytic properties of ethyl fluoroethyl carbonate and its application to lithium battery
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Monofluorination of solvents exerts the strong polar effect on various properties. We have investigated the electrolytic properties of ethyl fluoroethyl carbonate (EFEC) and its application to a lithium battery. Conductivities of EFEC solutions are higher than those of diethyl carbonate (DEC) counterparts above 25 °C or below 1 mol dm-3 of LiPF 6. The anodic stability of EFEC is also higher than that of DEC. The use of EFEC as a cosolvent improves the performance of a Li/LiCoO2 coin cell. Copyright
- Tsukimori, Naoko,Nanbu, Noritoshi,Takehara, Masahiro,Ue, Makoto,Sasaki, Yukio
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- Hydrogen bonding between solutes in solvents octan-1-ol and water
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The 1:1 equilibrium constants, K, for the association of hydrogen bond bases and hydrogen bond acids have been determined by using octan-1-ol solvent at 298 K for 30 acid-base combinations. The values of K are much smaller than those found for aprotic, rather nonpolar solvents. It is shown that the log K values can satisfactorily be correlated against αH 2?βH2, where αH 2 and βH2 are the 1:1 hydrogen bond acidities and basicities of solutes. The slope of the plot, 2.938, is much smaller than those for log K values in the nonpolar organic solvents previously studied. An analysis of literature data on 1:1 hydrogen bonding in water yields a negative slope for a plot of log K against αH 2?βH2, thus showing how the use of very strong hydrogen bond acids and bases does not lead to larger values of log K for 1:1 hydrogen bonding in water. It is suggested that for simple 1:1 association between monofunctional solutes in water, log K cannot be larger than about -0.1 log units. Descriptors have been obtained for the complex between 2,2,2-trifluoroethanol and propanone, and used to analyze solvent effects on the two reactants, the complex, and the complexation constant.
- Abraham, Michael H.,Gola, Joelle M. R.,Cometto-Muniz, J. Enrique,Acree, William E.
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experimental part
p. 7651 - 7658
(2011/02/25)
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- Spectrokinetic study of the reaction system of 2NO2?N 2O4 with some fluorinated derivatives of ethanol and propanols between 293-358 K in the gas phase
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The gas phase kinetics of the reversible reactions between nitrogen tetroxide and some fluorinated alcohols in the reaction system 2NO 2?N2O4 (1, 2) N2O4 + ROH?RONO+ + HNO3 (3, 4) have been studied by UV-Vis spectrophotometry to follow the NO2 decay. The products - RONO (R = CH2FCH2, CHF2CH2, CF 3CH2, CHF2CF2CH2, CF 3CF2CH2, CF3CHCF3) - were identified by their UV spectra and the values of the maxima UV absorption cross sections were determined in the range 320-400 nm. The rate constants for the forward reaction are 10-19k3av/cm 3molec-1s-1 9.7±1.5; 2.5±0.4; 1.8±0.3; 23±3.5, 2.3±0.3, 0.2±0.03 and for the reverse reaction 10-19k4av/cm 3molec-1s-1 4.6±0.7; 5.5±0.8; 4.9±0.7; 9.1±1.4; 7.7±1.2; 23±3.5 at 298 K for the reaction with 2-fluoroethanol, 2,2-difluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol, 2,2,3,3,3-pentafluoro-1-propanol and 1,1,1,3,3,3-hexafluoro-2-propanol, respectively, were derived by the computer simulation of monitored NO2 decay profiles. The temperature dependence of the bimolecular rate constants k3 and k4 were studied in the temperature range 293-358 K and the activation energy for the forward E3 and for the reverse E4 reaction were derived. From the observed temperature dependence of the equilibrium constants K3,4, expressed in terms of the van't Hoff equation, the thermochemical parameters for all reactions studied were estimated.
- Wojcik-Pastuszka,Golonka,Ratajczak
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p. 1559 - 1574
(2008/02/04)
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- Predominant role of basicity of leaving group in α-effect for nucleophilic ester cleavage
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It has been found that α-effects in nucleophilic reactions, unexpectedly large nucleophilicity due to adjacent unpaired electrons, are strongly dependent on the structure of substrate. The nucleophilic cleavages of 4-nitrobenzoate esters and 4-methylbenzo
- Nomura, Yasuo,Kubozono, Takayasu,Hidaka, Makoto,Horibe, Mineko,Mizushima, Naoki,Yamamoto, Nobuyuki,Takahashi, Toshio,Komiyama, Makoto
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- A semi-molten mixture of hexadecyltributylphosphonium bromide and potassium fluoride in the synthesis of organofluorine compounds
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A facile and effective reagent system comprising of a semi-molten mixture of hexadecyltributylphosphonium bromide and potassium fluoride has been developed and its scope has been investigated in nucleophilic fluoride exchange with various organohalides. This simple and convenient reagent system provides organofluorine compounds in high yields even with haloesters in which fluoride catalysed elimination is also feasible.
- Bhadury, Pinaki S.,Raza, Syed K.,Jaiswal, Devendra K.
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p. 115 - 117
(2007/10/03)
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- Models for Nuclease Catalysis: Mechanisms for General Acid Catalysis of the Rapid Intramolecular Displacement of Methoxide from a Phosphate Diester
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The dianion of the dialkyl phosphate diester 3 is hydrolysed in water at 50 deg C with a half-life of less than 2 min.The reaction involves highly efficient intramolecular nucleophilic catalysis (effective molarity 1010 mol dm-3) by the phenol OH over the whole pH range.The initial products are the cyclic phosphate diester and methanol: no phosphate migration is observed.General acid catalysis is observed for the reactions of all ionic species, and has been characterised in detail for the mono- and di-anion.An important electrostatic effect, observed for general acids with a suitably positioned second NH+ group, stabilises the transition state for the loss of methoxide from the dianion by up to 12.3 kJ mol-1, even in water.The data allow an estimate of 104-105 for the factor by which protonation to give the triester activates a phosphate diester towards attack by a neighbouring OH group. Mechanisms involving pentacovalent addition intermediates are proposed for the reactions of the neutral ester acid and the monoanion.The phosphorane dianion is considered to be an intermediate in the cyclisation of the substrate dianion, but with a lifetime too short for diffusional equilibration.
- Dalby, Kevin N.,Kirby, Anthony J.,Hollfelder, Florian
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p. 1269 - 1281
(2007/10/02)
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- REACTION OF HYDROXY AND CARBONYL COMPOUNDS WITH SULFUR TETRAFLUORIDE. XVI. REACTIONS OF VICINAL DIHYDRIC ALCOHOLS WITH SULFUR TETRAFLUORIDE
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During the action of sulfur tetrafluoride on ethanediol, d,l-1,2-propanediol, and d,l-3,3,3-trifluoro-1,2-propanediol regioselective substitution of one of the hydroxyl groups by a fluorine atom occurs, depending on the electronic nature of the groups present in the molecule.The second hydroxy group is converted into a fluorosulfite group.
- Burmakov, A. I.,Hassanein, Salah Mohamed,Kunshenko, B. V.,Alekseeva, L. A.,Yagupol'skii, L. M.
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p. 1146 - 1149
(2007/10/02)
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- The Steric Course of the Reaction of Ethylene Oxide with Hydrogen Halides in the Gas Phase
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The steric course of the gas-phase reaction of trans-ethylene oxide with HF, HCl, and HBr was investigated in order to test experimentally a mechanistic proposal based on ab initio calculations involving a concerted syn-opening mechanism.In contrast with this proposal the reactions with HCl and HBr take place entirely with anti-opening of the ring to give erythro-2-chloro- and 2-bromoethanol.The reaction of ethylene oxide with gaseous HF yields only 5percent 2-fluoroethanol, 37percent dioxan, oligomers and polymers being the main products.An inproved method for the conversion of cis- and trans-ethylene into the corresponding epoxides is described.
- Bellucci, Giuseppe,Berti, Giancarlo,Bianchini, Roberto,Ingrosso, Giovanni,Moroni, Antonio
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p. 1336 - 1340
(2007/10/02)
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