1493-11-4Relevant academic research and scientific papers
Temperature dependence of the gas phase reactions of CF3O with CH4 and NO
Jensen,Hanson,Howard
, p. 8574 - 8579 (1994)
A temperature-regulated flow tube reactor coupled to a chemical ionization mass spectrometer (CIMS) was used to investigate reactions of CF3O with CH4 and NO. The reaction rate for the CF3O + CH4 reaction was measured in the temperature range 231-385 K and found to be k3(T) = (3.1 ± 0.5) × 10-12 exp[(-1470 ± 250) K/T]cm3 molecule-1 s-1, with k3(298 K) = (2.2 ± 0.4) × 10-14 cm3 moleculeMIN1 (where the uncertainties represents our estimated accuracy at the 95 % confidence level). The latter is in good agreement with recently reported measurements at room temperature. The reaction rate constant for the CF3O + NO reaction was measured in the temperature range 231-393 K and found to be k4(T) = (4.1 ± 0.6) × 10-11 disagrees with two previously reported values by a factor of about 2.5 but is in good agreement with three recently reported values. The results reported in this study are important in establishing the fate of the CF3Ox radicals produced as degradation products from hydroflurocarbons (HFC's) in the atmosphere.
Atmospheric chemistry of C2F5CHO: mechanism of the C2F5C(O)O2 + HO2 reaction
Andersen, M. P. Sulbaek,Hurley, M. D.,Wallington, T. J.,Ball, J. C.,Martin, J. W.,Ellis, D. A.,Mabury, S. A.
, p. 14 - 21 (2003)
Smog chamber/FTIR techniques were used to study the gas-phase reaction of C2F5C(O)O2 with HO2 radicals in 100-700 Torr of air, or O2, diluted at 296 K. The reaction proceeds by two pathways leading to formation of C2F5C(O)OH and O3 in a yield of 24+/-4 percent and C2F5C(O)O radicals, OH radicals and O2 in a yield of 75+/-4 percent. The gas phase reaction of CnF(2n+1)C(O)O2 with HO2 radicals offers a potential explanation for at least part of the observed environmental burden of fluorinated carboxylic acids, CnF(2n+1)C(O)OH. As part of this work an upper limit for the rate constant of reaction of Cl atoms with C2F5C(O)OH at 296 K was determined; k(Cl + C2F5C(O)OH) -17 cm3 molecule-1 s-1.
Proton affinity and absolute heat of formation of trifluoromethanol
Chyall,Squires
, p. 16435 - 16440 (1996)
The proton affinity and absolute heat of formation of trifluoromethanol have been derived from translational energy threshold measurements for reactions involving oxygen-protonated trifluoromethanol. The reaction of ionized iodotrifluoromethane with water was used to prepare CF3OH2+ in the flow tube of a flowing afterglow triple-quadrupole instrument. The isomeric cluster ion, (HF)CF2OH+, was shown to be more stable than CF3OH2+ by the base-catalyzed conversion of CF3 OH2+ to (HF)CF2OH+ using either SO2 or OCS as the catalyst. The proton affinity of CF3OH at oxygen was determined from the enthalpy change for the endothermic proton transfer reaction CF3OH2+ + CO → CF3OH + HCO+. The measured enthalpy change, was combined with the known value for the proton affinity of CO (141.9 kcal mol-1) to yield a value for the oxygen proton affinity of CF3OH. The dissociation energy for the loss of water from CF3OH2+ was measured by energy-resolved collision-induced dissociation. This value was used in a thermochemical cycle along with the measured proton affinity of CF3OH to derive the gas-phase heat of formation of CF3OH. This experimental value is slightly lower than, but in good agreement with, the 298 K heat of formation of CF3OH that is predicted by high-level molecular orbital calculations.
Long Path FTIR Spectroscopic Study of the Reactions of CF3O Radicals with Alkenes
Chen, J.,Zhu, T.,Young, V.,Niki, H.
, p. 7174 - 7177 (1993)
The reactions of CF3O radicals with alkenes have been studied using the long path FTIR method in the visible (λ >/= 400 nm) photolysis of mixtures containing CF3NO, NO, and alkene (in milliTorr range) in 700 Torr of O2/N2 at 297 +/- 2 K.Kinetic and spectroscopic evidence has been obtained for the occurrence of the addition reaction (a) CF3O* + >C=C adduct, and the subsequent reactions involving the adducts, for several alkenes.Using the reaction (b) CF3O* + NO -> CF2O + FNO as the reference reaction, values for the relative rate constants, ka/kb have been determined to be 0.7 +/- 0.2(?), 0.9 +/- 0.2(?), 1.1 +/- 0.3(?), and 1.7 +/- 0.4(?) for CH2=CH2, CH3CH=CH2, trans-CH3CH=CHCH3, and (CH3)2C=C(CH3)2, respectively.Using the value of the rate constant for reaction b recently reported by Bavilacqua et al. (kb = (2 +/- 1) x 10-11 cm3 molecule-1 s-1), the values of the rate constant ka have been calculated to be (1.4 +/- 0.8) x 10-11, (1.8 +/- 1.0) x 10-11, (2.2 +/- 1.3) x 10-11, and (3.4 +/- 1.9) x 19-11 cm3 molecule-1 s-1 for CH2=CH2, CH3CH=CH2, trans-CH3CH=CHCH3, and (CH3)2C=C(CH3)2, respectively.
UV absorption spectrum, and kinetics and mechanism of the self reaction of CF3CF2O2 radicals in the gas phase at 295 K
Sehested,Ellermann,Nielsen
, p. 701 - 717 (1993)
The ultraviolet absorption spectrum, kinetics and mechanism of the self reaction of CF3CF2O2 radicals have been studied in the gas phase at 295 K. Two techniques were used; pulse radiolysis UV absorption to measure the spectrum and kinetics, and long-path length FTIR spectroscopy to identify and quantify the reaction products. Absorption cross sections were quantified over the wavelength range 220-270 nm. At 230 nm, ΣCF3CF2O2 =(2.74±0.46)×10-18 cm2 molecule-1. The observed products following the self reaction of CF3CF2O2 radicals were COF2CF3O3CF3, CF3O3C2F5, and CF3OH. CF3O2CF3 was tentatively identified as a product. The carbon balance was 90-100%. The self reaction of CF3CF2O2 radicals was found to proceed via one channel to produce CF3CF2O radicals which then decompose to give CF3 radicals and COF2. In the presence of O2, CF3 radicals are converted into CF3O radicals. CF3O radicals have several fates; self reaction to give CF3O2CF3; reaction with CF3O2 radicals to give CF3O3CF3; reaction with C2F5O2 radicals to give CF3O3C2F5; or reaction with CF3CF2H to give CF3OH. As part of this work a rate constant (2.5±0.6)×10-16 cm3 molecule-s- was measured for the reaction of Cl atoms with CF3CHF2 using a relative rate technique. Results are discussed with respect to the atmospheric chemistry of CF3CF2H(HFC-125).
Convenient access to trifluoromethanol
Christe, Karl O.,Hegge, Joachim,Hoge, Berthold,Haiges, Ralf
, p. 6155 - 6158 (2007)
From chimera to useful reagent: Easy access to trifluoromethanol in a one-step reaction from readily available inexpensive bulk chemicals opens the door for CF3OH to become a useful general reagent in synthetic chemistry and industrial applications. (Graph Presented).
A photoionization study of trifluoromethanol, CF3OH, trifluoromethyl hypofluorite, CF3OF, and trifluoromethyl hypochlorite, CF3OCl
Asher, Robert L.,Appelman, Evan H.,Tilson, Jeffrey L.,Litorja, Maritoni,Berkowitz, Joseph,Ruscic, Branko
, p. 9111 - 9121 (1997)
CF3OH, an important and controversial by-product of atmospheric decomposition of CF3CFH2 (HFC-134a) and other hydrofluorocarbons, has been examined by photoionization mass spectrometry. The ionization onset is characterized by a broad Franck-Condon distribution, arising primarily from a substantial elongation of the C-O bond upon ionization. An upper limit to the adiabatic ionization potential (IP) of ≤ 13.08 ± 0.05 eV has been established. The appearance potentials (APs) of the first two fragments have been accurately determined by fitting with appropriate model functions as AP0(CF2OH+/CF 3OH)≤13.830±0.005 eV and AP0(CF+3/CF 3OH)≤13.996±0.005 eV. While the exact nature of the lowest-energy fragment (nominally CF2OH+) is not clear, the CF+3 fragment threshold leads unambiguously to ΔH°f 298(CF3OH)≥-217.2±0.9 kcal/mol and D298(CF3-OH)≤115.2±0.3 kcal/mol. With previously derived ΔH°f 298(CF3O)=-151.8+1.7-1.1 kcal/mol, this yields D298(CF3O-H) =117.5+1.9-1.4 kcal/mol, very close to, or only slightly weaker than the O-H bond energy in water: D298(CF3O-H)-D298(HO-H)=-1.8 +1.9-1.4 kcal/mol≈0 kcal/mol. Similarly, with the recently redetermined value for ΔH°f(CF2O), this implies a 298 K reaction enthalpy for the 1,2-elimination of HF from CF3OH of 2.81+1.7-1.1 kcal/mol. CF3OF and CF3OCl have also been examined by photoionization. CF3OF produces a very weak parent, with an apparent adiabatic IP(CF3OF) ≤12.710±0.007 eV. An analysis of the CF+3 and CF2O+ fragments from CF3OF, when combined with literature data, suggests ΔH°f 298(CF3OF)=-176.9+1.8-1.3 kcal/mol. The fitted value for the appearance potential of CF+3 from CF3OCl, AP0(CF+3/CF 3OCl)≤12.85±0.01 eV, leads to ΔH°f 298(CF3OCl)≥-175.6±1.0 kcal/mol, D298(CF3-OCl)≤88.4±0.3 kcal/mol, and D298(CF3O-Cl)≤52.8+2.0-1.5 is kcal/mol.
Reactions of CF3O- with atmospheric trace gases
Huey, L. Gregory,Villalta, Peter W.,Dunlea, Edward J.,Hanson, David R.,Howard, Carleton J.
, p. 190 - 194 (1996)
The rate coefficients and product yields for the reactions of CF3O- with ClONO2, HNO3, HCl, N2O5, SO2, HI, and H2O were measured at 295 K and ~～.4 Torr using the flowing afterglow technique. The reactions of CF3O- with HO2NO2 and H2SO4 were also studied qualitatively. CF3O- reacts rapidly with ClONO2, HO2NO2, SO2, and HCl by only fluoride transfer and with HNO3, HI, and H2SO4 by both fluoride and proton transfer. CF3O- also reacts with HI to form IF2- and with N2O5 to produce NO3-. CF3O- undergoes a slow clustering reaction with H2O and is transformed within water clusters into F-·HF and F-·(HF)2. CF3O- is unreactive with CH3NO3, CH3C(O)O2NO2, O3, NO2, CO2, and O2. These results demonstrate that CF3O- is an excellent candidate as a reagent ion for the selective detection of ClONO2, HCl, and HNO3 in the upper troposphere and stratosphere with a chemical ionization mass spectrometer. The observed reaction of CF3O- with H2O within water clusters indicates that CF3O- will hydrolyze in aqueous solution to form F-, HF, and CO2. This provides insight into the mechanism for the heterogeneous loss of CF3OH in the atmosphere.
Atmospheric Chemistry of CF3O Radicals: Reaction with CH4, CD4, CH3F, CF3H, (13)CO, C2H5F, C2D6, C2H6, CH3OH, i-C4H8, and C2H2
Wallington, Timothy J.,Ball, James C.
, p. 3201 - 3205 (1995)
A relative rate technique has been used to study the title reactions at 296 +/- 2 K.Using a reference rate constant of k(CF3O + CH4) = (2.2 +/- 0.2) x 1E-14 cm3 molecule-1 s-1, rate constants (in 700 Torr of air diluent) for the reactions of CF3O radicals with the following reactants were established; CD4, (5.1 +/- 1.6) x 1E-15; CH3F, (2.4 +/- 0.3) x 1E-14; CF3H, 3 molecule-1 s-1.The rate of the reaction of CF3O radicals with (13)CO was observed to be dependent on the total pressure.In 100 Torr of total pressure of air diluent, k(CF3O + (13)CO) = (4.6 +/- 0.5) x 1E-14 cm3 molecule-1 s-1.The reaction of CF3O with (13)CO gives (13)CO2 in a yield of 96 +/- 8percent.Implications for the atmospheric chemistry of CF3O radicals are discussed.
Kinetics of the Reactions of CF3O Radicals with CO and H2O
Turnipseed, Andrew A.,Barone, Stephen B.,Jensen, Niels R.,Hanson, D. R.,Howard, Carleton J.,Ravishankara, A. R.
, p. 6000 - 6009 (1995)
The techniques of pulsed laser photolysis/pulsed laser-induced fluorescence and discharge flow/chemical ionization mass spectroscopy have been employed to study the reactions CF3O + H2O -> CF3OH + OH and CF3O + CO (+M) -> products (+M).No reaction could be observed between CF3O and H2O at both 298 and 381 K, yielding upper limits of k3(298 K) 3(381 K) 3 molecule-1 s-1.The rate coefficient, k4, for the reaction of CF3O with CO was observed to be dependent upon pressure, analogous to the OH + CO reaction.The high-pressure limiting rate coefficient was found to exhibit a weak positive temperature dependence with k4infinite(298 K) = (6.8 +/- 1.2) x 1E-14 cm3 molecule-1 s-1.A limit of 3 molecule-1 s-1 for the pressure independent pathway was also obtained and a limit of 3 molecule-1 s-1 was determined for the bimolecular path yielding CF3 and CO2 as products, both at 298 K.Information on the OH + CF3OOCF3, OH + CF3O, and CF3OO + CO reactions and on the products of the 248 nm photolysis of CF3OOCF3 was also obtained.The atmospheric implications of the results are discussed.
