- Kinetics of the Reactions of CF3Ox Radicals with NO, O3, and O2
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The technique of pulsed laser photolysis/pulsed laser-induced fluorescence detection of CF3O was used to study the stratospherically important reactions of CF3O radicals with NO (k5), O3 (k4), and O2 (k6) and that of CF3OO
- Turnipseed, Andrew A.,Barone, Stephen B.,Ravishankara, A. R.
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- Atmospheric degradation mechanism of CF3OCF2H
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Smog chamber/FTIR techniques were used to study the Cl atom initiated oxidation of CF3OCF2H in 700 Torr of N2/O2 at 295±2K. Atmospheric oxidation of CF3OCF2H proceeds via the formation of C
- Inoue,Kawasaki,Wallington,Hurley
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- Tropospheric degradation products of novel hydrofluoropolyethers
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The Cl atom-initiated photooxidations of the hydrofluoropolyethers (HFPEs) HCF2OCF2OCF2CF2OCF2H, HCF2OCF2CF2OCF2H, and HCF2OCF2OCF2H in air produced C(O)F2 as the only carbon-containing product, with observed average C(O)F2 molar formation yields of 4.73, 3.77, and 2.82, respectively. The C(O)F2 molar formation yields during the early stages of the reactions were observed to be closer to the number of C atoms in each parent HFPE. On the basis of current knowledge concerning the degradation pathways of hydrofluorocarbons and hydrochlorofluorocarbons, it is expected that C(O)F2 will also be produced with near unit yield per C atom from the above HFPEs in the troposphere, where loss processes would be initiated primarily by reaction with OH radicals. The rate constants for reaction with the Cl atom at 298 ± 2 K were determined for the HFPEs by a relative rate method that employed CF3CF2H as the reference compound [κ(Cl + CF3CF2H) = (2.4 ± 0.5) x 10-16 cm3 molecule-1 S-1], with measured values of (in units of 10-17 cm3 molecule-1 s-1) HCF2OCF2OCF2CF2OCF2H, 3.6 ± 0.8; HCF2OCF2CF2OCF2H, 4.5 ± 1.0; and HCF2OCF2OCF2H, 5.0 ± 1.1.
- Tuazon, Ernesto C.
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- Reaction Modulation Spectroscopy: A New Approach to Quantifying Reaction Mechanisms
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We report a new experimental method, reaction modulation spectroscopy, (RMS) that, shows great promise in enabling the systematic analysis of complicated oxidation mechanisms over the full range of atmospheric pressures and temperatures.The method is a form of difference spectroscopy in which we employ FTIR absorption spectroscopy in a high-pressure flow system (HPFS) where a plume of reacting species is examined before any significant fraction reaches the tube wall.The onest of the reaction is modulated by modulating the flow of an initiating radical species over a period that is short compared to any associated with experimental drifts.Spectra obtained with the radical source on and off are ratioed, giving a transmittance spectrum showing only the effects of the reaction modulation.The system is in a steady state, so signal averaging over long periods (up to several days) may be employed, if necessary, to obtain a high signal-to-noise ratio.Because no bulk reagents are disturbed in the process, we observe extremaly precise conservation of mass in the reaction plume.We illustrate the technique for the system OH + C3F6 (+O2, NOx,...) -> -> CF2O + CF3CFO, where we observe nearly 100percent conservatioin of odd-nitrogen species and roughly 90percent conservation of carbon under conditions chosen to force the reaction to completion, with residual spectra consistent with unidentified minor products having cross sections similar to the observed aldehydes.
- Donahue, Neil M.,Demerjian, Kenneth L.,Anderson, James G.
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- Halogen perchlorates. Reactions with fluorocarbon halides
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The reactions of chlorine perchlorate and bromine perchlorate with numerous fluoroalkyl halides were examined. In the case of fluorocarbon iodides, these reactions were generally found to produce high yields of the novel fluorocarbon perchlorates CF3
- Schack, Carl J.,Pilipovich, Don,Christe, Karl O.
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- Thermal Decomposition of CF3O2NO2
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The unimolecular decomposition rate constant of CF3O2NO2 has been measured in detail as a function of temperature, pressure, and collision partner (M = N2, O2, NO).Temperatures were between 264 and 297 K, and total pressures ranged from 3 to 1013 mbar.The first-order decay of CF3O2NO2 in the presence of excess NO was followed in a temperature-controlled DURAN glass chamber by long-path IR absorption, using the absorption bands at 1768 and 1303 cm-1.At 1013 mbar, the first-order decomposition rate constants are best represented by the Arrhenius expression k3 = 5.7E15exp-1/RT> s-1 (2?).The temperature and pressure dependencies of k3 are well reproduced by the equation log(k3/k3,infinite) = log3,0/k3,infinite)/(1 + k3,0/k3,infinite)> + log(Fc)3,0/k3,infinite)/Nc>2>-1, Nc = 0.75-1.27 log(Fc) with the parameters k3,0/ = 2.4E-5exp(-78.4 kJ mol-1/RT) cm3 molecule-1 s-1, k3,infinite = 1.49E16exp-1/RT> s-1, Fc = 0.31, and k3,0(M=O2) ca. k3,0(M=N2).By combining the present decomposition rate constants with recombination rate constants k-3 from Caralp et al., the following thermochemical data for the equilibrium CF3O2NO2 CF3O2 + NO2 (k3,k-3) are derived from second- and third-law evaluations: ΔH0r,298 = 102.7 +/- 2.0 kJ mol-1, ΔS0r,298 = 163 +/- 7 J mol-1 K-1.The temperature dependence of the equilibrium constant between 200 and 300 K is described by the expression Kc = k3/k-3 = 3.80E27exp molecules cm-3.Consistency of the data on k3 (this work) and k-3 is shown by comparing experimental and theoretical limiting low-pressure rate constants, which lead to the reasonable value βc = 0.17 for the collision efficiency of N2.The present data confirm that CF3O2NO2 is thermally quite stable in the upper troposphere and lower stratosphere and that its lifetime is probably limited by photolysis in these regions of the atmosphere.
- Mayer-Figge, A.,Zabel, F.,Becker, K. H.
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- Thermal gas-phase reaction of perfluorobuta-1,3-diene with NO2
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The reaction of NO2 with perfluorobuta-1,3-diene, CF2{double bond, long}CFCF{double bond, long}CF2 (C4F6), has been studied at 312.9, 323.0, 333.4, 396.0 and 418.0 K, using a conventional static system. The products formed in the temperature range 312.9-333.4 K were CF2{double bond, long}CFCF(NO2)CF2(NO2) (I), CF2(NO2)CF{double bond, long}CFCF2(NO2) (II), CF2{double bond, long}CFCF(NO2)C(O)F (III) and CF2(NO2)CF{double bond, long}CFC(O)F (IV) and FNO. The formation of these compounds was detected performing infrared and Raman spectra. The infrared spectrum shows a band at 1785 cm-1, characteristic to the terminal -CF{double bond, long}CF2 group and the Raman spectrum shows a band located at 1733 cm-1, corresponding to -CF{double bond, long}CF- group. It indicates, that in this temperature range, NO2 attacks initially only one double bound of CF2{double bond, long}CFCF{double bond, long}CF2. Since the intermediate radical CF2{double bond, long}CFC{radical dot}FCF2(NO2) formed in this process is allylic in nature, so there is no isomerization involved in this process, but rather the allylic radical is able to add the second NO2 either to CF2 or CFCF2(NO2) end, forming the corresponding products. At 396.0 and 418.0 K different products were observed: CF2(NO2)CF(NO2)C(O)F (V), NO, CF3C(O)F, C(O)F2 and traces of epoxide of tetrafluoroethene, showing that, at these temperatures, both double bonds are attacked by NO2 and detachment of CF2 group is produced. The mechanisms consistent with experimental results in the temperature range 312.9-333.4 and at 396.0 and 418 K are proposed.
- Czarnowski, Joanna
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- Kinetics and mechanism of gas-phase reactions of n-C4F 9OCH3, i-C4F9OCH3, n-C4F9OC(O)H, and i-C4F9OC(O)H with OH radicals in an environmental reaction chamber at 253-328 K
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The rate constants of the reactions of n-C4F9OCH 3 (k1), i-C4F9OCH3 (k2), n-C4F9OC(O)H (k3), and i-C4F9OC(O)H (k4) with OH radicals were studied in an 11.5-dm3 environmental reaction chamber. k1 and k2 were determined to be (1.44 ± 0.33) × 10 -12 exp[-(1450 ± 70)/T] and (1.59 ± 0.41) × 10-12 exp[-(1470 ± 80)/T] cm3 molecule-1 s-1 at 253-328 K. At 298 K, k3 and k4 were deduced to be (1.71 ± 0.32) × 10-14 and (1.67 ± 0.19) × 10-14 cm3 molecule-1 s -1. The observed products of the reaction of n-C4F 9OCH3 with OH radicals were n-C4F 9OC(O)H, CF3CF2CF2C(O)F, and COF2, and those for the reaction of i-C4F 9OCH3 were i-C4F9OC(O)H, (CF 3)2CFC(O)F, CF3C(O)F, and COF2.
- Chen,Uchimaru,Kutsuna,Tokuhashi,Sekiya
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- Atmospheric Chemistry of (CF3)2CHOCH3, (CF3)2CHOCHO, and CF3C(O)OCH3
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Smog chambers with in situ FTIR detection were used to measure rate coefficients in 700 Torr of air and 296 ± 2 K of: k(Cl+(CF3)2CHOCH3) = (5.41 ± 1.63) × 10-12, k(Cl+(CF3)2CHOCHO) = (9.44 ± 1.81) × 10-15, k(Cl+CF3C(O)OCH3) = (6.28 ± 0.98) × 10-14, k(OH+(CF3)2CHOCH3) = (1.86 ± 0.41) × 10-13, and k(OH+(CF3)2CHOCHO) = (2.08 ± 0.63) × 10-14 cm3 molecule-1 s-1. The Cl atom initiated oxidation of (CF3)2CHOCH3 gives (CF3)2CHOCHO in a yield indistinguishable from 100%. The OH radical initiated oxidation of (CF3)2CHOCH3 gives the following products (molar yields): (CF3)2CHOCHO (76 ± 8)%, CF3C(O)OCH3 (16 ± 2)%, CF3C(O)CF3 (4 ± 1)%, and C(O)F2 (45 ± 5)%. The primary oxidation product (CF3)2CHOCHO reacts with Cl atoms to give secondary products (molar yields): CF3C(O)CF3 (67 ± 7)%, CF3C(O)OCHO (28 ± 3)%, and C(O)F2 (118 ± 12)%. CF3C(O)OCH3 reacts with Cl atoms to give: CF3C(O)OCHO (80 ± 8)% and C(O)F2 (6 ± 1)%. Atmospheric lifetimes of (CF3)2CHOCH3, (CF3)2CHOCHO, and CF3C(O)OCH3 were estimated to be 62 days, 1.5 years, and 220 days, respectively. The 100-year global warming potentials (GWPs) for (CF3)2CHOCH3, (CF3)2CHOCHO, and CF3C(O)OCH3 are estimated to be 6, 121, and 46, respectively. A comprehensive description of the atmospheric fate of (CF3)2CHOCH3 is presented.
- ?sterstr?m, Freja From,Wallington, Timothy J.,Sulbaek Andersen, Mads P.,Nielsen, Ole John
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- Kinetics study of the gas-phase reactions of C2F 5OC(O)H and n-C3F7OC(O)H with OH radicals at 253-328 K
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The rate constants, k1 and k2 for the reactions of C2F5OC(O)H and n-C3F7OC(O)H with OH radicals were measured using an FT-IR technique at 253-328 K. k1 and k2 were det
- Chen,Kutsuna,Tokuhashi,Sekiya
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- UEBER TRISHYDROFLUORIDE TERTIAERER AMINE UND IHREN EINSATZ ALS FLUORIERUNGSMITTEL
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Tertiary amine trishydrofluorides are stable complexes which are distillable in vacuo.They can be handled without hazard and do not corrode borosilicate glass.They are convenient agents therfore, in nucleophilic replacement reactions of chlorine or bromine atoms by fluorine forming homogeneous reaction mixtures often leading to higher yield under very mild conditions.Examples are given for the preparation of fluoroacetone, cyanuric fluoride, difluorophosgene, oxalyl fluoride and sulfur tetrafluoride.
- Franz, R.
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- INFRARED FLUORESCENCE OF HYDROGEN FLUORIDE DURING MULTIQUANTUM DISSOCIATION OF A MIXTURE OF CF3OF WITH H2.
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The dissociation of molecules of trifluoromethyl hypofluoride CF//3OF in a mixture with hydrogen H//2 in the pulsed CO//2 laser emission field is discussed. This compound attracted attention because carbon-13 and oxygen-18 isotopes could possibly be obtained by laser excitation.
- Aslanidi,Aslanidi,Zaburin,Zainullin,Turishchev
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- AN IMPROVED SYNTHESIS OF DICHLOROFLUORAMINE, FNCl2
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Low-temperature fluorination of N,N-dichloro-1-fluoroformamide, FC(O)NCl2, has provided a more convenient, high-yield (75percent) synthesis of dichlorofluoramine, FNCl2, than was previously available.In an attempt to further expand the novel metal fluoride promted conversion of N-Cl bonds to N-Br bonds, both FC(O)NCl2 and FNCl2 were reacted with bromine in the presence of various alkali metal fluorides.No evidence was found for the formation of either FC(O)NBrCl and FC(O)NBr2 or FNBrCl and FNBr2 in these reactions.In fact, FC(O)NCl2 was found to decompose to C(O)F2, N2, and Cl2 in the presence of alkal metal fluorides.
- Thrasher, Joseph S.,Desmarteau, Darryl D.
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- Photolysis of CO2 with 158 nm (F2) Laser. Reactivity of O (1D) with CH4, CF3H, and CF3CH3
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Electronically excited oxygen atom O(1D), generated by photolysis of CO2 with a 158 nm (F2) laser, react with CH4, CF3H, and CF3CH3 to give corresponding vibrationally excited alcohols (ROH*) by insertion into the C-H bonds, which collapse to vibrationally relaxed alcohols or alkyl and hydroxy radical pairs depending on the stability and lifetime of ROH*.
- Kojima, Masanobu,Ojima, Yuichi,Nakashima, Nobuaki,Izawa, Yasukazu,Akano, Toru,Yamanaka, Chiyoe
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- Synthesis of Hexafluoroacetone by Catalytic Oxidation of Hexafluoropropylene
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Oxidation of hexafluoropropylene with molecular oxygen in a fixed bed of a catalyst (activated carbon promoted with alkali metal fluorides) was studied.
- Igumnov,Lekontseva,Shipigusev,Gomzyakova,Soshin
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- Absolute rate constants for the gas-phase reactions of O(3P) atoms with CF2=CFC1 and (E/Z)-CFC1=CFC1 at 298 K. Reactivity trends of the halogen-substituted ethenes series
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Absolute rate coefficients for the gas-phase reactions of CF2=CFC1 and (E/Z)-CFC1=CFC1 with O(3P) atoms have been measured at 298 K using a discharge flow tube coupled to a chemiluminescence detection system. The observed rate constant values are (4.5 ± 0.4) × 10-13 and (1.5 ± 0.3 × 10-13 cm3 molecule-1 s-1, respectively. The experiments were carried out under pseudo-first-order conditions with [O(3P)]0 ? [alkene]0. These results are compared to those of O atom reactions with other chlorine- and fluorine-substituted ethenes. Different factors that affect the rate of addition to the double bond are considered. The O(3P)/chloroethenes reactions do not obey the reactivity trend with the ionization potential, as is the case in the alkene and methyl-substituted alkene reactions.
- Teruel, Mariano A.,Taccone, Raul A.,Lane, Silvia I.
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- Kinetic studies on the reactions of CF3 with O(3P) and H atoms at high temperatures
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The kinetics of the high-temperature reactions of CF3 radicals with O(3P) and H atoms has been investigated experimentally and theoretically. The product channels of the CF3 + O(3P) and CF3 + H reactions were examined by calculating their branching fractions with the multichannel Rice-Ramsperger-Kassel-Marcus (RRKM) theory. Structural parameters, vibrational frequencies, and threshold energy required for the RRKM calculation were obtained from an ab initio MO calculation. The theoretical calculation showed that the productions of CF2O + F and CF2(1A1) + HF were the unique possible channels for the CF3 + O(3P) and CF3 + H reactions, respectively, and that the other channels such as deactivation were negligible for both the reactions. The rate coefficients for these reactions were experimentally determined by using a shock tube-atomic resonance absorption spectroscopy technique over the temperature ranges of 1900-2330 and 1150-1380 K and the total density ranges of 8.2 × 1018-1.2 × 1019 and 6.1 × 1018-9.8 × 1018 molecules·cm-3. Nitrous oxide and ethyl iodide were used as precursors of electronically ground-state oxygen and hydrogen atoms, respectively. Trifluoromethyl radicals were produced through the thermal dissociation of CF3I. The rate coefficients for the reactions CF3 + O(3P) → CF2O + F (1b) and CF3 + H → CF2(1A1) + HF (2c) were obtained from the decay profiles of O- and H-atom concentrations as k1b = (2.55±0.23) × 10-11 and k2c = (8.86±0.32) ×10-11 cm3 molecule-1 s-1 (error limits at the one standard deviation level). Neither rate coefficient had any temperature or pressure dependence under the present experimental conditions; the values were in good agreement with some room-temperature data reported previously.
- Takahashi, Kazuo,Sekiuji, Yoshinobu,Yamamori, Yasuyuki,Inomata, Tadaaki,Yokoyama, Keiichi
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- ELECTROCHEMICAL FLUORINATION OF ACETAMIDE AND FORMAMIDE IN MOLTEN KH2F3
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The electrofluorination of acetamide (CH3CONH2) and formamide (HCONH2) on the anode was studied in molten KH2F3 at 120 deg C.Amorphous carbon was used as the anode and Pt-rod as the reference electrode.Anodic products were analyzed by both gas chromatogra
- Tasaka, A.,Sakaguchi, H.,Aki, R.,Ihara, H.,Saka, K.,Yamamoto, T.
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- A kinetic and mechanistic study of the reactions of OH radicals and Cl atoms with 3,3,3-trifluoropropanol under atmospheric conditions
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Product distribution studies of the OH radical and Cl atom initiated oxidation of CF3CH2CH2OH in air at 1 atm and 298 ± 5 K have been carried out in laboratory and outdoor atmospheric simulation chambers in the presence and absence of NOx. The results show that CF3CH2CHO is the only primary product and that the aldehyde is fairly rapidly removed from the system. In the absence of NOx the major degradation product of CF3CH2CHO is CF3CHO, and the combined yields of the two aldehydes formed from CF3CH2CH2OH are close to unity (0.95 ± 0.05). In the presence of NOx small amounts of CF3CH 2C(O)O2NO2 were also observed (3CHO is removed from the system to give mainly CF2O. The laser photolysis-laser induced fluorescence technique was used to determine values of k(OH + CF3CH 2CH2OH) = (0.89 ± 0.03) × 10-12 and k(OH + CF3CH2HO) = (2.96 ± 0.04) × 10-12 cm3 molecule-1 s-1. A relative rate method has been employed to measure the rate coefficients k(OH + CF3CH2CH2OH) = (1.08 ± 0.05) × 10-12, k(OH + C6F13CH2CH 2OH) = (0.79 ± 0.08) × 10-12, k(Cl + CF 3CH2CH2OH) = (22.4 ± 0.4) × 10-12, and k(Cl + CF3CH2CHO) = (25.7 ± 0.4) × 10-12 cm3 molecule-1 s -1. The results from this investigation are discussed in terms of the possible importance of emissions of fluorinated alcohols as a source of fluorinated carboxylic acids in the environment.
- Kelly, Tanya,Bossoutrot, Valerie,Magneron, Isabelle,Wirtz, Klaus,Treacy, Jack,Mellouki, Abdelwahid,Sidebottom, Howard,Bras, Georges Le
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- REACTIONS OF TRIFLUORONITROSOMETHANE WITH BISTRIFLUOROMETHYLPHOSPHORUS COMPOUNDS, (CF3)2PX (WHERE X = H, Cl, CF3)
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Trifluoronitrosomethane reacts with bis(trifluoromethyl)phosphine to give (CF3)P(O)N(OH)CF3 and a small amount of (CF3)2NOH.On the other hand, the reactions with tris(trifluoromethyl)phosphine and bis(trifluoromethyl)chlorophosphine afford (CF3)2NOP(O)CF3N(CF3)2 and (CF3)2NP(O)(CF3)Cl respectively.Isomerisation of =N-O-P= to =N-P(O)= may be involved as found for the isomerisation of the phosphine, (CF3)2NOP(CF3)2, to the phosphoryl compound, (CF3)2NP(O)(CF3)2.Mechanisms for the above reactions are discussed.
- ANG, H. G.,SO, K. K.
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- Elementary reaction of CF2(X) with O3: Primary products
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The reaction of CF2(X) with O3 has been investigated in a discharge flow reactor at room temperature and low pressure (p = 2.5 mbar). CF2(X) was produced by a microwave discharge of a mixture of CF2Br2/He. The reactants and products were detected by mass spectrometers (MS), which were connected to the flow systems via a continuous molecular beam sampling system. The following primary products were observed (CF2O3 (m/z = 98); CF2O (m/z = 47, 66); O2 (m/z = 32)). The reaction mechanism: CF2(X) + O3 ? CF2O3# → CF2O3 → CF2O+O2 (1) explains the observed primary products. The molecule with the empirical formula CF2O3 has been observed directly by MS; the structure is discussed. by Oldenbourg Wissenschaftsverlag, Muenchen.
- Beiderhase,Hoyermann,Hack
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- Catalytic microreactor with electrodeposited hierarchically nanostructured nickel coatings for gas-phase fluorination reactions
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The fabrication of a catalytic microreactor for the reaction of undiluted carbonyl difluoride and elemental fluorine to synthesize trifluoromethyl hypofluorite, CF3OF, on CsF catalyst supported on F2-passivated nanosctructured Ni coating was studied. The nanosctructured Ni support for catalyst immobilization was electrodeposited by a two-step procedure, consisting of a low current density step followed by a brief high current density one, for a hierarchical differentiation of structural features. An aqueous solution of NiCl2 with diethanolamine, as crystal modifier, and sodium lauryl sulphate, as anti-pitting agent, was used as electrolyte. Constant-pH Ni electrocrystallization was performed on H2SO4-etched Cu substrates in a range of pH from 1 to 4 via a HCl/H3BO3 based buffer. Passivation was carried out under up to 300 mbar of undiluted F2. XRD, XPS, SEM, AFM, and static contact angle measurements were performed. Ni coatings obtained from pH 3 electrolytes were selected for microreactor fabrication on the basis of characterization data, due to the reproducibility and homogeneity of the structured Ni layers. The catalytic microreactor allowed the quantitative production of CF3OF from pure reactants, on demand, and removing any criticality relative to thermal and safety control of the synthesis. The CF3O-group selective transfer ability of the synthetized hypofluorite has raised interest in pharmaceutical and agrochemical industries in recent years.
- Sansotera, Maurizio,Baggioli, Alberto,Ieffa, Simona,Tedesco, Mariella,Sacchi, Benedetta,Bianchi, Claudia L.,Navarrini, Michele,Migliori, Massimo,Magagnin, Luca,Navarrini, Walter
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- Product distribution in the Cl-initiated photooxidation of CF 3C(O)OCH2CF3
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The product distribution and the mechanism of the reaction of Cl atoms with 2,2,2-trifluoroethyl 2,2,2-trifluoroacetate (TFETFA; CF3C(O)OCH 2CF3) were investigated using a 1080 L environmental chamber with in situ Fourier transform infrared (FTIR) spectroscopy detection. The experiments were performed at (296±2) K and atmospheric pressure (760±10) Torr of synthetic air free of NOx. A yield of (45W3)% was obtained for the CF3C(O)OC(O)CF3 formation. CF2O and CO were produced with estimated yields of 35 and 28%, respectively. No trifluoroacetic acid (TFA; CF3C(O)OH) was observed. The yields determined are rationalized in terms of the competitive reaction channels for the fluoroalcoxy radicals formed in the H-abstraction process: (a) reaction with O2, (b) C-C, C-O, C-H decomposition, and (c) a possible a-ester rearrangement pathway. The negligible importance of the a-ester channel, to produce TFA, was explained by the reduction of the stability of the five-membered transition state of the a-ester rearrangement. Atmospheric implications, particularly regarding the fluorocarboxylic acid formation, are discussed. Copyright
- Blanco,Barnes,Teruel, Mariano A.
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- Ultraviolet Absorption Spectrum and Kinetics and Mechanism of the Self-Reaction of CHF2CF2O2 Radicals in the Gas Phase at 298 K
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The ultraviolet absorption spectrum and kinetics and mechanism of the self-reaction of CHF2CF2O2 radicals have been studied in the gas phase at 298 K.Two techniques were used: pulse radiolysis UV absorption to measure the spectrum and kinetics and long-path-length Fourier transform infrared spectroscopy (FTIR) to identify and quantify the reaction products.Absorption cross sections were quantified over the wavelength range 220-270 nm.At 230 nm, ?CHF2CF2O2 = (3.2 +/- 0.5) * 10-18 cm2 molecule-1.Errors are statistical (2 standard deviations) plus our estimate of potential systematic uncertainty (15percent).This absorption cross section was used to derive the observed self-reaction rate constant for the reaction CHF2CF2O2 + CHF2CF2O2 -> products (1), defined as -d/dt = 2kl,obs2. kl,obs = (2.7 +/- 0.6) * 10-12 cm3 molecule-1 s-1 (errors are 2 standard deviations).Measured UV transients were not corrected for possible complications caused by formation of CHF2O2 and HO2 radicals.Hence, kl,obs may not be the true bimolecular rate constant for reaction 1.The only carbon-containing product observed by FTIR spectroscopy was COF2.The carbon balance was, within our experimental uncertainty, 100percent.As part of this work, a rate constant of (1.9 +/- 0.2) * 10-15 cm3 molecule-1 s-1 was measured for the reaction of Cl atoms with CHF2CHF2 using a relative rate technique.Results are discussed with respect to the atmospheric chemistry of haloalkanes.
- Nielsen, Ole J.,Ellermann, Thomas,Sehested, Jens,Wallington, Timothy J.
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- Evidence for the unimolecular decomposition of CF3OCF 3 to COF2 and CF4 by high energy irradiation
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The decomposition of CF3OCF3 via electron beam irradiation in the gas phase and isolated in an argon matrix at T = 10 K is investigated via infrared spectroscopy. CF3OCF3 produces only COF2 and CF4. In the gas phase irradiation, the G value for CF3OCF3 decomposition is 5.9, and the G values for formation of COF2 and CF4 are 5.0 and 4.9, respectively. In the low temperature matrix isolated irradiation, CF 3OCF3 decomposition and COF2 evolution occur in a 1:1 ratio. The results strongly suggest that a unimolecular mechanism for the formation of COF2 is operative because the product yields in the gas phase and matrix exposures are similar.
- Waltman
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- Zur thermischen Zersetzung von Fluorsulfonyldifluoracetylfluorid
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The thermal instability of (fluorosulfonyl)difluoroacetyl fluoride in the presence of CsF and anhydrous HF has been demonstrated.In the presence of CsF CF2=C=O and SO2F2 are formed, whereas in the presence of anhydrous HF the reaction leads to formation o
- Hass, Dieter,Holfter, Hagen,Schoenherr, Martin,Zahm, Evelyn
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- Migration of translationally excited fluorine atoms in solid argon and their reactions with small guest molecules
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Solid state reactions of photogenerated F atoms with CO and O2 molecules were studied in dilute mixtures of F2 + CO and F2 + O2 in solid argon by infrared spectroscopy. UV laser photolysis of F2 at 16
- Misochko, Eugenii Ya.,Akimov, Alexander V.,Wight, Charles A.
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- Temperature dependence of the gas-phase reactions F + CHFO, CFO + F, and CFO + CFO
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The rate coefficients for the reactions CHFO + F, CFO + F and the self-reaction of CFO were determined over the temperature range of 222-298 K A computer controlled discharge-flow system with mass spectrometric detection was used. The results are expressed in the Arrhenius form (with energies in J) CHFO + F → CFO + HF: k1,(T) = (9.7 ± 0.7) · 10-12 exp[-(5940 ± 150)/RT] cm3 molecule cm-1 s-1 CFO + F + M → CF2O + M: k2(T) = (260 ± 1.17)·10-10 exp[-(10110 ± 1250)/RT cm3 molecule-1 s-1 CFO + CFO → CF2O + CO: k3(T) = (3.77 ± 2.7)·10-10 exp[-(8350 ± 28001/RT] cm3 molecule-1 s-1
- Behr, Peter,Kaupert, Cornelia,Shafranovski, Eduard,Heydtmann, Horst
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- Gaseous ion-molecule reactions of F(-), CF3(-), C2F5(-), CF3(+) and C2F5(+) with hexafluoropropene oxide
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The gas-phase reactions of F(1-), CF3(1-), C2F5(1-), CF3(1+) and C2F5(1+) with hexafluoropropene oxide (HFPO, C3F6O) have been studied using a selected ion flow tube (SIFT) instrument at 300 K.Reactions of C4F9(1-) and C3F7(1+) with HFPO have also been studied as secondary reactions.Reaction rate constants and product branching fractions were measured.The F(1-), CF3(1-) and C2F5(1-) ions react rapidly with HFPO.The major reaction process is the formation of CF2O and the corresponding negative products ions.A minor pathway is the production of the ion CF3O(1-).Another reaction channel of F(1-) and CF3(1-) with HFPO is the formation of C2F4 and the corresponding ions.C4F9(1-) ion reacts with HFPO by F(1-) transfer to produce C3F7O(1-).The C3F7(1+) ion is the only product observed for the reaction of CF3(1+) with HFPO.The C2F5(1+) ion reacts rapidly with HFPO.The major product is C3F7(1+) which, in turn, reacts with HFPO to regenerate C2F5(1+), forming a cationic catalytic cycle for the formation of the inferred neutrals C2F4O and C4F8O from HFPO.Both C2F5(1+) and C3F7(1+) react with HFPO to produce neutral C3F8 and the corresponding positive ions.A rather rapid association reaction was observed between C3F7(1+) and HFPO, forming the adduct C6F13O(1+).A systematic estimation for the enthalpies of formation for a series of perfluorinated neutrals and ionic species is also presented. - Keywords: Ion-molecule reactions; Hexafluoropropene oxide; Fluorine ion; Trifluoromethyl ion; F-ethyl ion; Reaction kinetics
- Su, Timothy,Hammond, Gerald B.,Morris, Robert A.,Viggiano, A. A.,Paulson, John F.,et al.
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- Atmospheric Chemistry of HFC-272ca: Spectrokinetic Investigation of the CH3CF2CH2O2 Radical, Its Reactions with NO and NO2, and the Fate of the CH3CF2CH2O Radical
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A pulse radiolysis technique has been used to investigate the UV absorption spectrum of the CH3CF2CH2O2 radical from HFC-272ca, CH3CF2CH3.The absorption cross sections were quantified in the wavelength range 220-320 nm; at 250 nm the absorption cross section for CH3CF3CH2O2 was δ=(451+/-59) x 1E-20 cm2 molecule-1.By following the increase in NO2 at 400 nm, the rate constant for the reaction of CH3CF2CH2O2 with NO was determined to be (8.5+/-1.9) x 1E-12 cm3 molecule-1 s-1.The reaction of CH3CF2CH2O2 with NO2 was found to have a reaction rate constant of (6.8+/-0.5) x 1E-12 cm3 molecule-1 s-1.The kinetics of the reaction of CH3CF2CH3 with F atoms and CH3CF2CH2 with O2 were studied.The rate constants were (2.8+/-0.9) x 1E-11 and (1.10+/-0.03) x 1E-12 cm3 molecule-1 s-1, respectively.The observed rate constant for the self-reaction of CH3CF2CH2O2 radicals was (8.6+/-)0.4) x 1E-12 cm3 molecule-1 s-1.The reaction of CH3CF2CH2O2 radicals with NO gives CH3CF2CH2O radicals; the dominant atmospheric fate of CH3CF2CH2O radicals is reaction with O2 to give CH3CF2CHO.As part of the present work, relative rate techniques were used to measure rate constant at 296+/-2 K for reactions of Cl and F atoms with CH3CF2CH3, with the values being (1.7+/-0.2) x 1E-14 and (3.3+/-0.8) x 1E-11 cm3 molecule-1 s-1, respectively.
- Moegelberg, Trine E.,Nielsen, Ole J.,Sehested, Jens,Wallington, Timothy J.,Hurley, Michael D.
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- A new approach to the synthesis of 2,2-difluoro-1,3-dioxolanes
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A direct and versatile way to prepare halogenated 2,2-difluoro-1,3-dioxolanes through the addition of bis(fluoroxy)difluoromethane (BDM) to halogenated alkenes (CF2=CFCF3, CF2=CFOCF2CF3, CF2=CHCF3, CF3CF=CFCF3, CFCl=CFCl, CFBr=CFBr, CCl2=CCl2, CHCl=CCl2, CHCl=CHCl, CH2=CHCl, CF2=CFCl, (CF3)2CFCF=CFCF3, CF2=CFBr, CF2=CF2) has been discovered. - Keywords: Synthesis; Difluorodioxolanes; NMR spectroscopy; IR spectroscopy; Mass spectrometry
- Navarrini, W.,Bragante, L.,Fontana, S.,Tortelli, V.,Zedda, A.
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- FTIR Studies of the Reaction of O(1D)-Atoms with CF3Br in Solid Argon Matrices
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The reaction O(1D)+CF3Br has been investigated in solid Ar-matrices at T=14K.Codeposition of O3/CF3Br/Ar mixtures and irradiation at 250 nm yielded F2CO as dominant reaction product.Experiments with 18O3 indicate that CF3OBr was formed during the course of the reaction.Our observations were interpreted with the formation of an excited CF3OBr molecule which can be stabilized in the matrix cage or decompose rapidly into two different F2CO*HF complexes.
- Lorenzen-Schmidt, Heike,Weller, Rolf,Schrems, Otto
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- A new perfluorinated peroxynitrate, CF3CF2CF2CF2OONO2. Synthesis, characterization and atmospheric implications
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CF3CF2CF2CF2OONO2 was synthesized from the photolysis of CF3CF2CF2CF2I, in presence of NO2 and O2. Alkyl peroxynitrates (CxF2x+1OONO2) could be formed in the atmospheric degradation of chlorofluorocarbons, hydrofluorocarbons and hydrofluoroethers. We present here the synthesis and characterization (IR and UV absorption cross sections) of CF3CF2CF2CF2OONO2 and its comparison with those corresponding to other perfluoro alkyl peroxynitrates. The thermal stability was studied as a function of total pressure (from 9.0 to 417 mbar) and temperature (from 283 to 293 K) using infrared spectroscopy. Kinetic parameters measured for the thermal dissociation were Ea = (81 ± 4) kJ/mol and A = 4.8 × 1012. DFT calculations at the B3LYP/6-311+Ga.
- Bossolasco, Adriana G.,Vila, Jesús A.,Burgos Paci, Maxi A.,Malanca, Fabio E.,Argüello, Gustavo A.
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- The reaction of difluorodioxirane with caesium trifluoromethoxide
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The reaction of difluorodioxirane with caesium trifluoromethoxide in the presence of CsF forms CF3OOC(O)F and the new compounds CF3O(OCF2O)(n)OC(O)F (n = 1~3); 13C labeling shows that the dioxirane undergoes ring opening at the O-O bond.
- Huang, Qun,DesMarteau, Darryl D.
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- LASER PHOTOSENSITIZED OXIDATION OF TETRAFLUOROETHENE BY MOLECULAR OXYGEN
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Surface-less conditions of CO2 laser photosensitized (SF6) oxidation of tetrafluoroethene with molecular O2 (3Σ) oxygen reveal that the true gas-phase reaction is accompanied with chemiluminiscence and proceeds via intermediary dioxetane to yield solely carbonyl fluoride.
- Pola, Josef,Ludvik, Jiri
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- Atmospheric chemistry of HCF2O(CF2CF 2O)xCF2H (x=2-4): Kinetics and mechanisms of the chlorine-atom-initiated oxidation
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Smog chamber/FTIR techniques were used to measure k(Cl+HCF 2O(CF2CF2O)xCF2H)=(5. 3±1.5)× 10-17 cm3 molecule-1 s-1 in 700 Torr of N2/O2 diluent at 296±1 K. The Cl-initiated atmospheric oxidation of HCF 2O(CF2CF2O)xCF2H, x=2,3 and 4, gave COF2 in molar yields of (593±41) %, (758±71) % and (939±73) %, respectively, with no other observable carbon-containing products (i.e., essentially complete conversion of the hydrofluoropolyethers into COF2). Quantitative infrared spectra for HCF2O(CF2CF2O)xCF2H (x=2-4) were recorded and used to estimate the radiative efficiencies of the title compounds (1.07, 1.33, and 1.36 W m-2 ppb-1). Global warming potentials (100 year time horizon) of 3870, 4730 and 5060 were estimated for HCF2O(CF2CF2O)xCF 2H, x=2, 3 and 4, respectively. The results are discussed with respect to the atmospheric chemistry and environmental impact of hydrofluoropolyethers.
- Sulbaek Andersen, Mads P.,Andersen, Vibeke F.,Nielsen, Ole J.,Sander, Stanley P.,Wallington, Timothy J.
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- Direct Trifluoromethoxylation without OCF3-Carrier through In Situ Generation of Fluorophosgene
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Owing to the high interest in the OCF3 group for pharmaceutical and agrochemical applications, trifluoromethoxylation received great attention in the last years with several new methods for this approach towards OCF3-comprising compounds. Yet, it most often requires the beforehand preparation of specific F3CO? transfer reagents, which can be toxic, expensive, unstable, and/or generate undesired side-products upon consumption. To circumvent this, the in-situ generation of gaseous fluorophosgene from triphosgene, its conversion by fluoride into the OCF3 anion, and the direct use of the latter in nucleophilic substitutions is an appealing strategy, which, although recently approached, has not been fully exploited. We disclose herein our efforts towards this aim.
- Donnard, Morgan,Guérin, Thomas,Hanquet, Gilles,Leroux, Frédéric R.,Panossian, Armen,Saiter, Jérémy
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supporting information
p. 3139 - 3147
(2021/06/26)
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- Kinetics and mechanism of ozone addition to tetrafluoroethylene and hexafluoropropylene
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The DSC method was used to study the low-temperature (77–280 K) ozonolysis of perfluoroleflns, tetrafluoroethylene (TFE) and hexafluoropropylene (HFP), in the direct interaction with ozone in the absence of solvents and oxygen. The values of activation en
- Kiryukhin,Krisyuk,Maiorov
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p. 132 - 139
(2021/03/02)
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- Improved Access to Organo-Soluble Di- and Tetrafluoridochlorate(I)/(III) Salts
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A facile one-pot gram-scale synthesis of tetraalkylammonium tetrafluoridochlorate(III) [cat][ClF4] ([cat]=[NEt3Me]+, [NEt4]+) is described. An acetonitrile solution of the corresponding alkylammonium chloride salt is fluorinated with diluted fluorine at low temperatures. The reaction proceeds via the [ClF2]? anion which is structurally characterized for the first time. The potential application of [ClF4]? salts as fluorinating agents is evaluated by the reaction with diphenyl disulfide, Ph2S2, to pentafluorosulfanyl benzene, PhSF5. The CN moieties in acetonitrile and [B(CN)4]? are transferred in CF3 groups. Exposure of carbon monoxide, CO, leads to the formation of carbonyl fluoride, COF2, and elemental gold is dissolved under the formation of tetrafluoridoaurate [AuF4]?.
- Kaupp, M.,Müller, R.,Pr?hm, P.,Riedel, S.,Schattenberg, C. J.,Schmid, J. R.,Sonnenberg, K.,Steinhauer, S.,Vo?nacker, P.
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supporting information
p. 16002 - 16006
(2020/07/20)
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- A Series of Deoxyfluorination Reagents Featuring OCF2Functional Groups
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Research on perfluoroalkyl ether carboxylic acids (PFECAs) as alternatives for perfluoroalkyl substances continues with the goal of protecting the environment. However, very little is known about the utilization of decomposition products of PFECAs. We report herein a new series of deoxyfluorination reagents featuring OCF2 functional groups derived from certain PFECAs. Alkyl fluorides were generated from various alcohols in ≤97% yield by these novel reagents. The mechanistic experiment verified in situ generation of carbonic difluoride (COF2).
- Cao, Wei,Chen, Qing-Yun,Guo, Yong,Su, Zhaoben,Wu, Chengying,Zhao, Shiyu
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supporting information
(2020/11/03)
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- Structures and Properties of trans-1,3,3,3-Tetrafluoro- propene (HFO-1234ze) and 2,3,3,3-Tetrafluoropropene (HFO-1234yf) Refrigerants
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The refrigerant trans-1,3,3,3-tetrafluoropropene (HFO-1234ze) is used as a replacement for former cooling agents that have been phased-out due to their global warming potential or ozone depleting potential. Although it is used on a large scale, only a few vibrational data and no structural data of HFO-1234ze are known. We report structure determinations based on low-temperature single-crystal X-ray diffraction data as well as gas-phase diffraction data of HFO-1234ze and HFO-1234yf (2,3,3,3-tetrafluoropropene). Furthermore, vibrational spectra of HFO-1234ze in all phases are described. The results are discussed together with quantum-chemical calculations on the PBE0/cc-pVTZ level of theory. Combustion experiments of HFO-1234ze show carbonyl difluoride, carbon dioxide and hydrogen fluoride to be the main combustion products.
- Flierl, Lukas,Glodde, Timo,Kornath, Andreas J.,Mitzel, Norbert W.,Schwabedissen, Jan,Stammler, Hans-Georg,Vishnevskiy, Yury V.
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p. 921 - 928
(2020/10/06)
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- Reductive photo-chemical separation of the hexafluorides of uranium and molybdenum
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Two new techniques are described for the separation of molybdenum hexafluoride (MoF6) from uranium hexafluoride (UF6). Both separation techniques utilize the differences displayed by the hexafluorides in their ability to absorb light in the near UV region. Because UF6 absorbs light in the near UV region and MoF6 does not, this observation was used to selectively reduce UF6 to uranium pentafluoride (UF5) through irradiation with 395 nm light in the presence of a suitable reducing agent. Two reducing agents were chosen for this study: gaseous, liquid, or super-critical carbon monoxide (CO) and liquid sulfur dioxide (SO2). Since MoF6 is not reduced under the reaction conditions described here, it may be removed via distillation from the uranium-containing sample after complete reduction of UF6 to solid UF5. The molybdenum- and uranium-containing samples were measured for purity through elemental analysis using microwave plasma atomic emission spectroscopy (MP-AES). Elemental analysis showed more than 98.8 % of the Mo had been removed from the U-containing samples. Further analyses of the samples were performed by X-ray powder diffraction and IR spectroscopy.
- Chemnitz, Tobias,Kraus, Florian,Petry, Winfried,Stene, Riane E.
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supporting information
(2020/10/18)
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- Trifluoromethyl Benzoate: A Versatile Trifluoromethoxylation Reagent
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Trifluoromethyl benzoate (TFBz) is developed as a new shelf-stable trifluoromethoxylation reagent, which can be easily prepared from inexpensive starting materials using KF as the only fluorine source. The synthetic potency of TFBz is demonstrated by trifluoromethoxylation-halogenation of arynes, nucleophilic substitution of alkyl (pseudo)halides, cross-coupling with aryl stannanes, and asymmetric difunctionalization of alkenes. The unprecedented trifluoromethoxylation-halogenation of arynes proceeds smoothly at room temperature with the aid of a crown ether-complexed potassium cation, which significantly stabilizes the trifluoromethoxide anion derived from TFBz.
- Zhou, Min,Ni, Chuanfa,Zeng, Yuwen,Hu, Jinbo
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supporting information
p. 6801 - 6805
(2018/05/31)
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- Photoinduced Sulfur-Nitrogen Bond Rotation and Thermal Nitrogen Inversion in Heterocumulene OSNSO
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An exotic ternary S, N, O heterocumulene OSNSO in syn-syn (A) and syn-anti (B) conformations has been generated in the gas phase through flash vacuum pyrolysis of CF3S(O)NSO at 700 K. Upon visible light irradiation (570 ± 20 or 532 nm), both A and B, isolated in cryogenic matrices (N2, Ne, Ar, and Kr, a higher-energy anti-anti conformer (C). The reverse conformational transformation occurs either through S=N bond rotation (C to A and B) under visible light irradiation (400 ± 20 nm) at 2.8 K or through thermal nitrogen inversion (C to A) in the temperature range of 20-30 K, for which an exceptionally low activation barrier of 1.18 ± 0.07 kcal mol-1 has been experimentally determined.
- Wu, Zhuang,Feng, Ruijuan,Xu, Jian,Lu, Yan,Lu, Bo,Yang, Tao,Frenking, Gernot,Trabelsi, Tarek,Francisco, Joseph S.,Zeng, Xiaoqing
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p. 1231 - 1234
(2018/02/09)
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- Decomposition characteristics of C5F10O/air mixture as substitutes for SF6 to reduce global warming
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Sulfur hexafluoride (SF6) is widely used in the power industry but is a serious greenhouse gas. Many researchers committed to achieving sustainable development of the power industry are finding alternatives to SF6 gas. C5F10O performs well in terms of environmental protection, insulation, and safety and is a potential environment-friendly alternative gas. In this paper, the insulation and decomposition characteristics of C5F10O/air gas mixture were examined using gas-insulation performance test platform, and decomposition products were detected by gas chromatography–mass spectrometry. The formation mechanism and distribution of C5F10O decomposition products were analyzed through reactive molecular dynamics method and density functional theory. The influence of air on the decomposition of C5F10O was also evaluated. Results showed that the decomposition of C5F10O/air gas mixture mainly produces CF3[rad], C3F7[rad], C4F7O[rad], CO, CF2[rad], CF[rad], F[rad] and CF4. The breakdown voltage of C5F10O/air gas mixture decreased slightly after repeated breakdown tests, and CF4, C2F6, C3F8, C3F6, C4F10, CF2O were detected. These results can serve as a reference for the systematic comprehension of the decomposition characteristics of C5F10O/air gas mixture and for related engineering applications.
- Li, Yi,Zhang, Xiaoxing,Xiao, Song,Chen, Qi,Wang, Dibo
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- Catalytic C?H Trifluoromethoxylation of Arenes and Heteroarenes
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The intermolecular C?H trifluoromethoxylation of arenes remains a long-standing and unsolved problem in organic synthesis. Herein, we report the first catalytic protocol employing a novel trifluoromethoxylating reagent and redox-active catalysts for the direct (hetero)aryl C?H trifluoromethoxylation. Our approach is operationally simple, proceeds at room temperature, uses easy-to-handle reagents, requires only 0.03 mol % of redox-active catalysts, does not need specialized reaction apparatus, and tolerates a wide variety of functional groups and complex structures such as sugars and natural product derivatives. Importantly, both ground-state and photoexcited redox-active catalysts are effective. Detailed computational and experimental studies suggest a unique reaction pathway where photoexcitation of the trifluoromethoxylating reagent releases the OCF3 radical that is trapped by (hetero)arenes. The resulting cyclohexadienyl radicals are oxidized by redox-active catalysts and deprotonated to form the desired products of trifluoromethoxylation.
- Zheng, Weijia,Morales-Rivera, Cristian A.,Lee, Johnny W.,Liu, Peng,Ngai, Ming-Yu
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supporting information
p. 9645 - 9649
(2018/03/21)
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- Novel synthetic route to perfluoroallyl cyanide (PFACN) reacting perfluoroallyl fluorosulfonate with cyanide
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A novel synthetic method for the preparation of perfluoroallyl cyanide CF2[dbnd]CFCF2CN (PFACN) is presented. This includes the addition – elimination reaction of cyanide anion with perfluoroallyl fluorosulfate CF2[dbnd]CF
- Tverdomed, Sergey N.,Hirschberg, Markus E.,Pajkert, Romana,Hintzer, Klaus,R?schenthaler, Gerd-Volker
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- Shock wave studies of the pyrolysis of fluorocarbon oxygenates. I. The thermal dissociation of C3F6O and CF3COF
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The thermal decomposition of hexafluoropropylene oxide, C3F6O, to perfluoroacetyl fluoride, CF3COF, and CF2 has been studied in shock waves highly diluted in Ar between 630 and 1000 K. The measured rate constant k1 = 1.1 × 1014exp(-162(±4) kJ mol-1/RT) s-1 agrees well with literature data and modelling results. Using the reaction as a precursor, equimolar mixtures of CF3COF and CF2 were further heated. Combining experimental observations with theoretical modelling (on the CBS-QB3 and G4MP2 ab initio composite levels), CF3COF is shown to dissociate on two channels, either leading to CF2 + COF2 or to CF3 + FCO. By monitoring the CF2 signals, the branching ratio was determined between 1400 and 1900 K. The high pressure rate constants for the two channels were obtained from theoretical modelling as k5,∞(CF3COF → CF2 + COF2) = 7.1 × 1014exp(-320 kJ mol-1/RT) s-1 and k6,∞(CF3COF → CF3 + FCO) = 3.9 × 1015exp(-355 kJ mol-1/RT) s-1. The experimental results obtained at [Ar] ≈ 5 × 10-6 mol cm-3 were consistent with modelling results, showing that the reaction is in the falloff range of the unimolecular dissociation. The mechanism of secondary reactions following CF3COF dissociation has been analysed as well.
- Cobos,Hintzer,S?lter,Tellbach,Thaler,Troe
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p. 3151 - 3158
(2017/08/17)
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- Shock wave studies of the pyrolysis of fluorocarbon oxygenates. II. the thermal dissociation of C4F8O
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The thermal decomposition of octafluorooxalane, C4F8O, to C2F4 + CF2 + COF2 has been studied in shock waves highly diluted in Ar between 1300 and 2200 K. The primary dissociation was shown to be followed by secondary dissociation of C2F4 and dimerization of CF2. The primary dissociation was found to be in its falloff range and falloff curves were constructed. The limiting low and high pressure rate constants were estimated and compared with modelling results. Quantum-chemical calculations identified possible reaction pathways, either leading directly to the final products of the reaction or passing through an open-chain CF2CF2CF2 intermediate which dissociates in a second step.
- Cobos,Hintzer,S?lter,Tellbach,Thaler,Troe
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p. 3159 - 3164
(2017/08/17)
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- Gas-phase photodissociation of CF3C(O)Cl between 193 and 280 nm
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Product yields were measured in the 296 K photolysis of CF3C(O)Cl at 193, 248, 254, and 280 nm. Br2 was used as a radical scavenger to convert the primary CF3 and CF3CO radical photofragments into stable bromides, CF3Br and CF3C(O)Br, which were quantified along with CO and CF2O using infrared absorption. The stabilized CF3CO radical yield increased with increasing photolysis wavelength from 3Cl quantum yield was determined to be 0.001 at all wavelengths.
- McGillen, Max R.,Burkholder, James B.
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p. 189 - 194
(2015/10/12)
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- Photochemistry of matrix isolated (Trifluoromethyl)sulfonyl azide, CF3SO2N3
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The photochemistry of matrix isolated (trifluoromethylsulfonyl) azide, CF3SO2N3, has been studied at low temperatures. Upon ArF laser irradiation (λ = 193 nm), the azide eliminates N2 and furnishes triplet [(trifluoromethyl)sulfonyl]nitrene, CF3SO2N, which has been characterized by IR and EPR spectroscopy. Upon subsequent UV light irradiation (λ = 260-400 nm) the nitrene converts to CF3N=SO2 and CF3S(O)NO through a Curtius-type rearrangement. Further two new species CF2N=SO2F and FSNO were identified together with CF2NF, SO2, F2CO, CF3NO, and SO as side products. In addition, triplet nitrene CF3N was detected by its EPR and IR spectra. The complex stepwise photodecomposition of matrix isolated CF3SO2N3 is discussed in terms of the observed photolysis products and quantum chemical calculations.
- Zeng, Xiaoqing,Beckers, Helmut,Willner, Helge,Neuhaus, Patrik,Grote, Dirk,Sander, Wolfram
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p. 2281 - 2288
(2015/03/30)
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- The effect of oxygen in the photocatalytic oxidation pathways of perfluorooctanoic acid
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The influence of oxygen in the photocatalytic oxidation of perfluorooctanoic acid (PFOA) promoted by a commercial nano-sized titanium dioxide was studied by testing the reaction in different conditions: static air, oxygen flux, nitrogen flux and pre-saturated nitrogen flux. The reaction was monitored by Total Organic Carbon (TOC) analysis and Ionic Chromatography (IC). Shorter chain perfluorocarboxylic acids (PFCAs; Cn, n = 1-7) intermediate degradation products were quantitatively determined by High-Performance Liquid Chromatography combined with Mass Spectrometry (HPLC-MS) analysis. The presence of shorter chain PFCAs in solution was also monitored by 19F NMR. The experimental findings are in agreement with two major oxidative pathways: Cn → Cn-1 photo-redox and β-scissions routes mediated by COF2 elimination. Depending on the experimental conditions, the mutually operating mechanisms could be unbalanced up to the complete predominance of one pathway over the other. In particular, the existence of the β-scissions route with COF2 elimination was corroborated by the isolation and characterization of carbonyl difluoride, a predicted fluorinated decomposition by-product.
- Sansotera, Maurizio,Persico, Federico,Rizzi, Valentina,Panzeri, Walter,Pirola, Carlo,Bianchi, Claudia L.,Mele, Andrea,Navarrini, Walter
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p. 159 - 168
(2015/11/10)
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- Atmospheric chemistry of CF3CF2CHO: Absorption cross sections in the UV and IR regions, photolysis at 308 nm, and gas-phase reaction with OH radicals (T = 263-358 K)
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The relative importance in the atmosphere of UV photolysis of perfluoropropionaldehyde, CF3CF2CHO, and reaction with hydroxyl (OH) radicals has been investigated in this work. First, the forbidden n → π* transition of the carbonyl chromophore was characterized between 230 and 380 nm as a function of temperature (269-298 K) and UV absorption cross sections, σλ, were determined in those ranges. In addition, IR absorption cross sections were determined between 4000 and 500 cm-1. Pulsed laser photolysis (PLP) of CF3CF 2CHO coupled to Fourier transform infrared (FTIR) was employed to determine the overall photolysis quantum yield, Φλ, at 308 nm and 298 K. Φλ=308 nm was pressure dependent, ranging from (0.94 ± 0.14) at 75 Torr to (0.30 ± 0.01) at 760 Torr. This dependence is characterized by the Stern-Volmer parameters Φλ=308 nm0 = (1.19 ± 0.34) and KSV = (1.22 ± 0.52) × 10-19 cm3 molecule-1. End products of the photodissociation of CF3CF2CHO were measured and quantified by FTIR spectroscopy. Furthermore, the rate coefficients for the OH + CF3CF2CHO reaction, k1, were determined as a function of temperature (T = 263-358 K) by PLP-LIF. At room temperature the rate coefficient is k1(T = 298 K) = (5.57 ± 0.07) × 10 -13 cm3 molecule-1 s-1, whereas the temperature dependence is described by k1(T) = (2.56 ± 0.32) × 10-12 exp{-(458 ± 36)/T} cm3 molecule -1 s-1. On the basis of our results, photolysis of CF 3CF2CHO in the actinic region could be an important removal process for CF3CF2CHO in the atmosphere. The formation of the primary products in the UV photolysis of CF3CF 2CHO is also discussed.
- Antinolo, Maria,Jimenez, Elena,Gonzalez, Sergio,Albaladejo, Jose
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p. 178 - 186
(2014/02/14)
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- FLUORINE-CONTAINING COMPOUND PURIFICATION METHOD
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There is provided a fluorine-containing compound purification method for obtaining a high-purity fluorine-containing compound by efficiently separating and removing hydrogen chloride from a fluorine-containing compound that contains hydrogen chloride, i.e., from a crude fluorine-containing compound. The fluorine-containing compound purification method of the present invention comprises the following steps (1) and (2) in this order: step (1): a step of adding dimethyl ether to a crude fluorine-containing compound that contains a fluorine-containing compound and hydrogen chloride in a molar ratio (dimethyl ether (mol)/hydrogen chloride (mol)) of dimethyl ether to hydrogen chloride being 1.3 or more to prepare a mixture (1) of the crude fluorine-containing compound and dimethyl ether; andstep (2): a step of separating and removing a mixture (2) of hydrogen chloride and dimethyl ether from the mixture (1).
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Page/Page column 5-6
(2012/09/05)
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- Direct fluorination of carbon monoxide in microreactors
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Many attempts to obtain a clean stream of COF2 have been carried out in the past by means of the direct fluorination of carbon monoxide with elemental fluorine or by electrochemical fluorination. The reaction is highly exothermic, therefore dif
- Navarrini, Walter,Venturini, Francesco,Tortelli, Vito,Basak, Soubir,Pimparkar, Ketan P.,Adamo, Andrea,Jensen, Klavs F.
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- Atmospheric chemistry of CF3CH2OCH3: Reaction with chlorine atoms and OH radicals, kinetics, degradation mechanism and global warming potential
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FTIR smog chamber techniques were used to measure k(Cl + CF 3CH2OCH3) = (2.28 ± 0.44) × 10-11 and k(OH + CF3CH2OCH3) = (4.9 ± 1.3) × 10-13 cm3 molecule-1 s-1 in 700 Torr total pressure of air at 296 ± 2 K. The atmospheric lifetime of CF3CH2OCH3 is estimated at 25 days. Reaction of Cl atoms with CF3CH2OCH 3 proceeds 79 ± 4% at the CH3 group and 22 ± 2% at the CH2 group. Reaction with OH radicals proceeds 55 ± 5% at the CH3 group yielding CF3CH2OCHO and 45 ± 5% at the CH2 group yielding COF2 and CH 3OCHO as primary oxidation products. The infrared spectrum of CF 3CH(O)OCH3 was measured and a global warming potential GWP100 = 8 was estimated. The atmospheric chemistry and environmental impact of CF3CH2OCH3 is discussed in context of the use of hydrofluoroethers as CFC substitutes.
- ?sterstr?m, Freja From,Nielsen, Ole John,Sulbaek Andersen, Mads P.,Wallington, Timothy J.
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scheme or table
p. 32 - 37
(2012/03/09)
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- Synthesis and properties of trifluoromethoxyl fluoroformyl anhydride, CF3OC(O)OC(O)F
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In the present work the synthesis of the trifluoromethoxyl fluoroformyl anhydride is presented for the first time. Two strategies were employed to obtain CF3OC(O)OC(O)F: the thermal decomposition of CF 3OC(O)OOOC(O)F in excess of CO, and the reaction between CF 3OC(O)OOC(O)F, FC(O)OOC(O)F and CO. A mechanism was proposed taking into account reaction rates and thermal stability of the intermediates. DFT calculations at B3LYP/6-311+G* level were used to explore the conformational space of this molecule and the relative populations of conformers at room temperature, and to simulate the experimental vibrational spectrum. This molecule completes the family of the asymmetric oxygen bonded acyl compounds CF3OC(O)OxC(O)F with x = 1-3.
- Manetti, Martín M.,Argüello, Gustavo A.,Paci, Maxi A. Burgos
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experimental part
p. 16 - 20
(2012/10/08)
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- Mechanism of photo-oxidation of heptafluorobutyric anhydride in the presence of NO2. Synthesis and characterization of heptafluoropropyl peroxynitrate, CF3CF2CF2OONO2
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The photolysis of heptafluorobutyric anhydride at 254 nm in the presence of NO2 and O2 has been studied. It leads to the formation of CF3CF2CF2OONO2, CF 3CF2OONO2, and CF2O as the only fluorine-containing carbonaceous products. The formation of the new heptafluoropropyl peroxynitrate (HFPN, CF3CF2CF 2OONO2), as one of the main products, is a consequence of the formation of CF3CF2CF2OO radicals followed by the reaction with NO2. To characterize HFPN, the UV absorption cross sections and their temperature dependence between 245 and 300 K have been measured over the wavelength range 200-300 nm as well as the infrared absorption cross sections. Kinetic parameters for its thermal decomposition are also presented in the temperature range between 281 and 300 K. The Rice-Ramsperger-Kassel-Marcus calculation reveals that the rate coefficient for the thermal decomposition at 285 K is almost independent of total pressure. The mechanism for the decomposition of CF3CF2CF 2OONO2 in the presence of NO was adjusted by a kinetic model, which enabled the calculation of important rate coefficients.
- Bossolasco, Adriana G.,Malanca, Fabio E.,Paci, Maxi A. Burgos,Argüello, Gustavo A.
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p. 9904 - 9910
(2013/01/15)
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- PROCESS FOR PRODUCING CARBONYL DIFLUORIDE
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An object of the invention is to provide efficient, simple and inexpensive processes for the production of carbonyl difluoride, which is an attractive and important compound as a semiconductor etching gas or a semiconductor cleaning gas. A process for producing carbonyl difluoride of the invention includes a step of reacting phosgene and hydrogen fluoride in a gas phase in the presence of a fluorination catalyst to produce carbonyl difluoride and hydrogen chloride, and a step of mixing a mixture containing the carbonyl difluoride and the hydrogen chloride with an organic solvent that is azeotropic with hydrogen chloride but zeotropic with carbonyl difluoride, and distilling the resultant mixture to separate the carbonyl difluoride.
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Page/Page column 6
(2011/08/06)
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- UV absorption cross sections between 230 and 350 nm and pressure dependence of the photolysis quantum yield at 308 nm of CF3CH2CHO
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Ultraviolet (UV) absorption cross sections of CF3CH 2CHO were determined between 230 and 350 nm by gas-phase UV spectroscopy. The forbidden n → π* transition was characterized as a function of temperature (269-323 K). In addition, the photochemical degradation of CF3CH2CHO was investigated at 308 nm. The possible photolysis channels are: CF3CH2 + HCO (R1a), CF3CH3 + CO (R1b), and CF3CH2CO + H (R1c). Photolysis quantum yields of CF3CH2CHO at 308 nm, Φλ=308nm, were measured as a function of pressure (25-760 Torr of synthetic air). The pressure dependence of Φ λ=308nm can be expressed as the following Stern-Volmer equation: 1/Φλ=308nm = (4.65 ± 0.56) + (1.51 ± 0.04) × 10-18 [M] ([M] in molecule cm-3). Using the absorption cross sections and the photolysis quantum yields reported here, the photolysis rate coefficient of this fluorinated aldehyde throughout the troposphere was estimated. This calculation shows that tropospheric photolysis of CF3CH2CHO is competitive with the removal initiated by OH radicals at low altitudes, but it can be the major degradation route at higher altitudes. Photodegradation products (CO, HC(O)OH, CF 3CHO, CF3CH2OH, and F2CO) were identified and also quantified by Fourier transform infrared spectroscopy. CF3CH2C(O)OH was identified as an end-product as a result of the chemistry involving CF3CH2CO radicals formed in the OH + CF3CH2CHO reaction. In the presence of an OH-scavenger (cyclohexane), CF3CH2C(O)OH was not detected, indicating that channel (R1c) is negligible. Based on a proposed mechanism, our results provide strong evidences of the significant participation of the radical-forming channel (R1a).
- Antinolo, Maria,Jimenez, Elena,Albaladejo, Jose
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experimental part
p. 15936 - 15946
(2012/02/02)
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- PROCESS FOR PRODUCTION OF CARBONYL FLUORIDE
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The present invention provides a method for inexpensively, efficiently, safely, and continuously producing COF2, without using highly toxic raw materials such as phosgene or difficult-to-get raw materials, with no risk of explosion or the like. Tetrafluoroethylene gas and oxygen gas are introduced into a reactor, and they are then heated in a gas phase in the absence of nitrogen gas for reaction, so as to produce carbonyl fluoride. The reactor is preferably a tubular reaction tube. As such tetrafluoroethylene gas, unpurified or purified tetrafluoroethylene gas obtained by heating HCFC-22 gas for thermal decomposition can be used. According to the present invention, COF2 that is useful as cleaning gas for CVD devices (chemical vapor deposition method) can be inexpensively, efficiently, and safely produced.
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Page/Page column 9; 10
(2010/08/07)
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- Decomposition of pentafluoroallyl fluorosulfate oxide
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Decomposition of pentafluoroallyl fluorosulfate oxide under nucleophilic catalysis is studied. The possible reaction mechanism is considered.
- Lebedev,Berenblit,Troichanskaya,Gubanov
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experimental part
p. 449 - 455
(2009/07/10)
-
- A novel synthesis of trifluoromethyl fluoroformate from trifluoromethyl hypofluorite and carbon monoxide in the presence of fluorine gas
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Trifluoromethyl fluoroformate is prepared through a radical reaction between CF3OF and CO initiated by elemental fluorine. The reaction could be integrated into a continuous synthesis process. This method represents a convenient synthesis of the title compound under mild condition.
- Du, Libin,DesMarteau, Darryl D.
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experimental part
p. 1044 - 1046
(2009/04/06)
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- Kinetics and products of chlorine atom initiated oxidation of HCF 2OCF2OCF2CF2OCF2H and HCF20(CF20)n(CF2CF20)mCF 2H
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Smog chamber/FTIR techniques were used to measure κ(Cl + HCF 2OCF2OCF2-CF2OCF2H) = κ(Cl + HCF20(CF20)n(CF2CF 20)mCF2H) = (5.0 ± 1.4) × 10-17 cm3 molecule-1 s-l in 700 Torr of N 2/02 diluent at 296 ± 1 K. The Cl-initiated atmospheric oxidation of HCF2OCF2OCF2CF 2OCF2H and the sample of HCF20(CF 20)n(CF2CF20)MCF2H used in this work gave COF2 in molar yields of (476 ± 36)% and (859 ± 63)%, respectively, with no other observable carbon containing products (i.e., essentially complete conversion of both hydrofluoropolyethers into COF 2). The results are discussed with respect to the atmospheric chemistry and environmental impact of hydrofluoropolyethers of the general formula HCF20(CF20)n(CF2CF20) mCF2H.
- Wallington,Hurley,Javadi,Nielsen
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body text
p. 819 - 825
(2009/04/06)
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- Method For Producing Carbonyl Difluoride
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The present invention relates to a method for producing carbonyl difluoride comprising a step of reacting trifluoromethane with oxygen or an oxygen-containing gas while heating.
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Page/Page column 4-5
(2008/06/13)
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- Process for preparing fluorohalogenethers
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A process for preparing fluorovinylethers having general formula: [in-line-formulae]RfO—CF═CF2 ??(IA)[/in-line-formulae]wherein Rf is a fluorinated or perfluorinated alkyl or cycloalkyl substituent; comprising the following reaction steps:1) reaction of a hypofluorite of formula RfOF, wherein Rf is as above, with an olefin of formula: [in-line-formulae]CY″Y═CY′CI ??(II)[/in-line-formulae]wherein Y, Y′ and Y″, equal to or different from each other, are H, Cl, Br, with the proviso that Y, Y′ and Y″ are not contemporaneously hydrogen;2) dehalogenation or dehydrohalogenation of the fluorohalogenethers obtained in step 1) and obtainment of vinyl ethers of formula: [in-line-formulae]RfO—CYI═CYIIF ??(IV)[/in-line-formulae]wherein YI and YII, equal to or different from each other, have the meaning of H, Cl, Br with the proviso that YI and YII are not both H;3) fluorination with fluorine of the vinyl ethers (IV) and obtainment of fluorohalogenethers of formula: [in-line-formulae]RfO—CFYI—CF2YII ??(I)[/in-line-formulae]wherein YI, YII, equal to or different from each other, are Cl, Br, H with the proviso that YI and YII cannot be contemporaneously equal to H;4) dehalogenation or dehydrohalogenation of the fluorohalogenethers (I) and obtainment of the fluorovinylethers (IA).
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Page/Page column 4
(2008/06/13)
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- Process for preparing fluorohalogenethers
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A process for preparing perfluorovinylethers having general formula: [in-line-formulae]RfO—CF═CF2 ??(IA)[/in-line-formulae] wherein Rf is a C1-C3 alkyl perfluorinated substituent; comprising the following steps: 1a) fluorination with fluorine of olefins of formula: [in-line-formulae]CY″Y═CY′Cl ??(II)[/in-line-formulae]wherein Y, Y′ and Y″, equal to or different from each other, are H, Cl, Br, with the proviso that Y, Y′ and Y″ are not contemporaneously hydrogen; and obtainment of fluorohalogencarbons of formula: [in-line-formulae]FCY″Y—CY′ClF ??(III)[/in-line-formulae]wherein Y, Y′ and Y″ are as above; 2a) dehalogenation or dehydrohalogenation of the fluorohalogencarbons (III) and obtainment of fluorohalogen olefins of formula: [in-line-formulae]FCYI═CYIIF ??(IV)[/in-line-formulae]wherein YI and YII, equal to or different from each other, have the meaning of H, Cl, Br with the proviso that YI and YII are not both H; 3a) reaction between a hypofluorite of formula RfOF and a fluorohalogenolefin (IV), obtaining the fluorohalogenethers of formula: [in-line-formulae]RfO—CFYI—CF2YII ??(I)[/in-line-formulae]wherein YI, YII, equal to or different from each other, are Cl, Br, H with the proviso that YI and YII cannot be contemporaneously equal to H; 4a) dehalogenation or dehydrohalogenation of the compounds (I) and obtainment of the perfluorovinylethers (IA).
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Page/Page column 4
(2008/06/13)
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- METHOD FOR PRODUCING CARBONYL FLUORIDE
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To provide a method for producing carbonyl fluoride by employing carbon monoxide and fluorine as starting materials, without such a problem as vigorous heat generation or a decrease in the reaction yield due to a side reaction. A method for producing carbonyl fluoride, which comprises introducing carbon monoxide gas and fluorine gas into a liquid, and letting carbon monoxide and fluorine react with each other to obtain carbonyl fluoride.
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Page/Page column 5-6
(2008/06/13)
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- Process for preparing fluorohalogenethers
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A process for preparing fluorovinylethers having general formula: ???????? RfO-CF=CF2,?????(IA) wherein Rf is a fluorinated or perfluorinated alkyl or cycloalkyl substituent; comprising the following reaction steps: 1) reaction of a hypofluorite of formula RfOF, wherein Rf is as above, with an olefin of formula: ???????? CY"Y=CY'Cl?????(II) wherein Y, Y' and Y", equal to or different from each other, are H, Cl, Br, with the proviso that Y, Y' and Y" are not contemporaneously hydrogen; 2) dehalogenation or dehydrohalogenation of the fluorohalogenethers obtained in step 1) and obtainment of vinyl ethers of formula: ???????? RfO-CYI=CYIIF?????(IV) wherein YI and YII, equal to or different from each other, have the meaning of H, Cl, Br with the proviso that YI and YII are not both H; 3) fluorination with fluorine of the vinyl ethers (IV) and obtainment of fluorohalogenethers of formula: ???????? RfO-CFYI-CF2YII?????(I) wherein YI, YII, equal to or different from each other, are Cl, Br, H with the proviso that YI and YII cannot be contemporaneously equal to H; 4) dehalogenation or dehydrohalogenation of the fluorohalogenethers (I) and obtainment of the fluorovinylethers (IA).
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Page/Page column 7
(2008/06/13)
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- Process for preparing fluorohalogenethers
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A process for preparing perfluorovinylethers having general formula: ???????? RfO-CF=CF2?????(IA) wherein Rf is a C1-C3 alkyl perfluorinated substituent; comprising the following steps: 1a) fluorination with fluorine of olefins of formula: ???????? CY"Y=CY'Cl?????(II) wherein Y, Y' and Y", equal to or different from each other, are H, Cl, Br, with the proviso that Y, Y' and Y" are not contemporaneously hydrogen; and obtainment of fluorohalogencarbons of formula: ???????? FCY"Y-CY'ClF?????(III) wherein Y, Y' and Y" are as above; 2a) dehalogenation or dehydrohalogenation of the fluorohalogencarbons (III) and obtainment of fluorohalogen olefins of formula: ???????? FCYI=CYIIF?????(IV) wherein YI and YII, equal to or different from each other, have the meaning of H, Cl, Br with the proviso that YI and YII are not both H; 3a) reaction between a hypofluorite of formula RfOF and a fluorohalogenolefin (IV), obtaining the fluorohalogenethers of formula: ???????? RfO-CFYI-CF2YII?????(I) wherein YI, YII, equal to or different from each other, are Cl, Br, H with the proviso that YI and YII cannot be contemporaneously equal to H; 4a) dehalogenation or dehydrohalogenation of the compounds (I) and obtainment of the perfluorovinylethers (IA).
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Page/Page column 8-9
(2008/06/13)
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- Production of carbonyl fluoride
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Carbonyl fluoride, which can also be used as an etching gas, can be prepared by photochemical oxidation of chlorodifluoromethane or trifluoromethane with light, for example with light of a wavelength >=280 nm in the presence of chlorine.
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Page/Page column 3; 4
(2008/06/13)
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- Reaction between carbon dioxide and elementary fluorine
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Reactions between carbon dioxide and fluorine were examined at temperatures of 303-523 K under various pressure and mixture ratios of both gases. Reactions were carried out similarly under the existence of NaF, CsF and EuF3. After the reaction, fluorine was removed and the reaction products were analyzed using FT-IR, GC/FT-IR and GC/MS. The major products were CF3OF, COF2, CF4 and CF2(OF)2. The best yield of COF2 was 11.1% under the reaction condition of CO2/F2 = 76 kPa/76 kPa with temperature of 498 K for 72 h in a direct reaction. The formation rate of COF2 in the direct reaction was estimated as 0.232 dm3 mol-1 h-1 under the reaction conditions of CO2/F2 = 76 kPa/76 kPa, at 498 K. In the presence of CsF, it was estimated as 1.88 dm3 mol-1 h-1 at CO2/F2 = 76 kPa/76 kPa at 498 K. The activation energy of the COF2 formation in the direct reaction was estimated as 45.7 kJ mol-1 at CO2/F2 = 76 kPa/76 kPa at 498 K. In addition, 24.2 and 38.9 kJ mol-1 were evaluated at CO2/F2 = 76 kPa/76 kPa at 498 K, respectively, in the presence of CsF and EuF3.
- Hasegawa, Yasuo,Otani, Reiko,Yonezawa, Susumu,Takashima, Masayuki
-
-
- Bromodifluoroacetyl fluoride, CF2BrC(O)F: Experimental and theoretical studies
-
Bromodifluoroacetyl fluoride, CF2BrC(O)F, was prepared through the gas-phase reaction of bromotrifluoroethene, CF2CFBr, with molecular oxygen initiated either by NO2 or CF3OF. The compound was experimentally studied by FTIR spectroscopy of the gas phase and also isolated in Ar and N2 matrices at low temperature. The energy differences between the possible conformers were theoretically studied, as well as the vibrational spectra of the conformers.
- Arce, Valeria B.,Czarnowski, Joanna,Romano, Rosana M.
-
-
- Methods for producing carbonyl fluoride and apparatus for production
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To provide a method for industrially producing COF2 in good yield. A method for producing carbonyl fluoride, which comprises continuously supplying carbon monoxide A and fluorine B together with a diluent gas into a reaction chamber 1 and letting them react with each other and which is characterized in that hydrogen fluoride or carbonyl fluoride is used as the diluent gas. An apparatus for producing carbonyl fluoride wherein carbon monoxide A and fluorine B are reacted to form carbonyl fluoride, which is characterized by comprising a means to supply carbon monoxide A, a means to supply fluorine B, a means to supply a diluent gas being hydrogen fluoride or carbonyl fluoride, and a reaction chamber.
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Page/Page column 3
(2008/06/13)
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- TFE-based thermoprocessable copolymers
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TFE-based thermoprocessable copolymers having the following composition, expressed in percentage by moles on the total of the monomers: A) from 0.01 to 15% of the monomer of formula: [in-line-formulae]CF2═CFOCF2OCF3??(a); [/in-line-formulae] A1) tetrafluoroethylene from 99.99 to 85%; optionally B) one or more (per)fluorinated comonomers having at least one unsaturation of ethylene type, different from TFE; the sum of the molar percentages A)+B) being such as to give polymers showing at least one melting peak at the thermogravimetric analysis (DSC).
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Page/Page column 4
(2008/06/13)
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- Process for producing carbonyl fluoride
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The process for producing carbonyl fluoride according to the invention is a process for safely and easily producing high-purity carbonyl fluoride having a low content of carbon tetrafluoride, and comprises feeding carbon monoxide and fluorine to a reactor and allowing carbon monoxide to react with fluorine under the conditions of a reactor internal pressure of less than atmospheric pressure.
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Page/Page column 5-6
(2008/06/13)
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- Rate measurement of the reaction of CF2Cl radicals with O 2
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We have studied the association reaction of the CF2Cl radicals with O2 in presence of N2. The infrared multiple photon dissociation (IRMPD) technique with a homemade TEA CO2 laser was used for the CF2Cl radical generation and the vibrational chemiluminiscence technique was set up for the study of the reaction kinetics. The time-resolved IR fluorescence of the vibrationally excited CF2O photoproduct was used to measure the disappearance rate of these radicals. A kinetic mechanism is presented to account for the rate of production of CF 2O*. The CF2Cl radical association reaction rate with O2, evidence of a direct channel of photoproduct formation and its reaction rate, and the CF2O* collisional deactivation rate have been obtained.
- Codnia, Jorge,Azcarate, Maria Laura
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p. 755 - 762
(2008/02/11)
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- Formation of bromodifluoroacetyl fluoride, CF2BrC(O)F, in the thermal gas-phase oxidation of bromotrifluoroethene, CF2CFBr, initiated by trifluoromethylhypofluorite, CF3OF
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The oxidation of CF2CFBr by molecular O2, initiated by CF3OF, has been studied at 273, 253.5, 239 and 218 K. The initial pressure of CF3OF was varied between 0.9 and 2.4 Torr, that of CF2CFBr between 11.5 and 30.7 Torr and that of O2 between 42.5 and 100.7 Torr. The main product was CF2BrC(O)F (yields 81-95% based on the CF2CFBr consumed). Minor amounts of C(O)F2 and C(O)FBr and traces of bromotrifluoroethene epoxide were also formed. The reaction is a chain reaction with bromine atoms as chain carriers. Its basic steps are: the thermal generation of CF3O{radical dot} radical by abstraction of fluorine atom from CF3OF, chain initiation by addition of CF3O{radical dot} to the double bond of alkene, leading, in presence of O2, to the formation of bromine atom and chain propagation by the reaction of bromine atom with CF2CFBr, originating CF2BrCFBrO{radical dot} radical. The predominant fate of the latter is the bromine atom extrusion with C{single bond}C bond scission playing the minor role. The full mechanism is postulated.
- Czarnowski, Joanna
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p. 736 - 739
(2008/09/16)
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