F:Flammable;2154-59-8Relevant articles and documents
Simons, J. P.,Yarwood, A. J.
, p. 943 - 944 (1961)
Pritchard,Perona
, p. 2944,2947,2948 (1969)
Saunders,Heicklen
, p. 2088 (1965)
Competition between unimolecular C-Br-bond fission and Br2 elimination in vibrationally highly excited CF2Br2
Abel, B.,Hippler, H.,Lange, N.,Schuppe, J.,Troe, J.
, p. 9681 - 9690 (1994)
The competition between C-Br-bond fission and three-center elimination of molecular bromine (Br2) in highly excited CF2Br2 molecules has been studied under collision-free conditions.Transient resonantly enhanced multiphoton ionization (REMPI) was used to monitor Br(2P1/2) and Br(2P3/2) formation during and after infrared (IR) mutiphoton excitation of CF2Br2; time-resolved laser-induced fluorescence (LIF) spectroscopy was employed for the detection of transient CF2 after Br2 elimination.Direct time-resolved measurements of the sum of afterpulse reaction rates, absolute product yields for the CF2 and Br(2P3/2) channels as well as absorbed energies per excitation pulse were used to characterize parts of the vibrational energy distribution P(E) established after IR multiphoton excitation and to determine rate coefficients and branching ratios for the elimination and dissociation reaction as a function of the average internal energy .The existence of both channels, the dissociation and the elimination channel, has been confirmed.A comparison of the experimental data with statistical adiabatic channel model calculations (SACM) enabled us to determine the threshold energies E0(J=0) for the unimolecular Br2 elimination 0(J=0) = 19 070+/-500 cm-1> and the C-Br bond fission 0(J=0) = 20 700+/-500 cm-1>, the two possible pathways of the reaction.
Bowles et al.
, p. 1541 (1962)
Halomethylenes: Effects of Halogen Substitution on Absolute Heats of Formation
Lias, Sharon G.,Karpas, Zeev,Liebman, Joel F.
, p. 6089 - 6096 (1985)
New values for the heats of formation of CF2, CCl2, CClF, CFH, and CClH have been derived from estimations of the thermochemistry of the reaction(s) CXYH+ + B -> CXY + BH+ where X and Y are F and/or Cl and B is a molecule for which an absolute value of the gas-phase basicity (or proton affinity) is available.The experiments, carried out in an ion cyclotron resonance spectrometer, lead to the following values for the heats of formation (in kcal/mol) of the ground-state singlet carbenes: CF2, -49 +/- 3; CCl2, 39 +/- 3; CFCl, -2 +/- 7; CFH, 26 +/-3; CClH, 71 +/-5.The value for CF2 is lower by about 5 kcal/mol than the previously accepted value, but in good agreement with values derived from previous "bracketing" results and also in agreement with values derived from the observed threshold energies for ionic dissociation processes.The value for CCl2 is significantly lower than the 1976 value of 47 +/-3 kcal/mol recommended by S.W.Benson, but in good agreement with an earlier value (40 +/- 5 kcal/mol) recommended by this author with more recent experimental results on the onset energy of formation of Cl2- from CCl4.The values for CFH, CClH, and CFCl are all approximately equal to the averages of the heats of formation of the corresponding CX2 and CY2 species, in agreement with assumptions made in previous estimates of these quantities.Values for the C-X bond energies in the halomethylenes, the heats of formation of the corresponding CXY+ ions, and the ionization potentials of the CXY species are derived from the results.From the most recent calculations of the energy differences between the ground-state singlet halomethylenes and the first triplet state, values for the heats of formation of the triplet halomethylenes are obtained; an analysis of trends in these values indicates that 3CF2 is substantially destabilized.
Giles et al.
, p. 662 (1967)
Kolb,Kaufman
, p. 947 (1972)
Shock wave studies of the pyrolysis of fluorocarbon oxygenates. I. The thermal dissociation of C3F6O and CF3COF
Cobos,Hintzer,S?lter,Tellbach,Thaler,Troe
, p. 3151 - 3158 (2017/08/17)
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.
Rate measurement of the reaction of CF2Cl radicals with O 2
Codnia, Jorge,Azcarate, Maria Laura
, p. 755 - 762 (2008/02/11)
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.
