24981-14-4Relevant articles and documents
The effect of collisions in the multiphoton decomposition of 1-bromo-2-fluoroethane
McRae, Glenn A.,Evans, D. K.,Goodale, J. W.
, p. 1689 - 1694 (1990)
The multiphoton decomposition (MPD) of 1-bromo 2-fluoroethane, CH2BrCH2F, with a pulsed CO2 infrared laser is reported.The decompsition study was done at constant fluence and at pressures up to 2 kPa.Empirical representations of the pressure dependence of the MPD are reported.A collision-dependent reaction scheme is presented to explain the pressure dependence of the up-pumping through the vibrational manifold.
The translational energy dependence of the F + C2H4 -> H + C2H3F reaction cross section near threshold
Robinson, Gary N.,Continetti, Robert E.,Lee, Yuan T.
, p. 275 - 284 (1990)
We have carried out crossed molecular beam studies of the substitution reaction F + C2H4 -> H + C2H3F in the collision energy range 0.8-2.5 kcal/mol using a velocity selected F atom beam.The relative substitution cross section is found to decrease with increasing collision energy indicating that if there is a potential energy barrier to F atom addition to C2H4 it is much less than 0.8 kcal/mol and that the transition state for addition occurs early along the reaction coordinate.These results agree well with ab initio calculations.Although the product translational energy distributions are similar to those obtained from earlier work at higher collision energies, the C2H3F angular distributions suggest that a wider range of rectant approach geometries lead to products at lower energies.
Infrared Multiphoton Decomposition of 1-Chloro-1-fluoroethene
Ogura, Hiroo
, p. 1358 - 1366 (1985)
Unimolecular dissociation and subsequent reactions of CH2=CFCl subjected to the infrared multiphoton excitation were studied with a focused geometry using the P(10) line of the 10.6 μm CO2 band at 952.9 cm-1.The final products of the photolysis observed were CH=CCl, CH=CF, CH=CH, CH2CHF, and CH2=CF2.A series of diagnostic experiments shows that the primary processes of photolysis involve the molecular elimation of HF and HCl, to minor extend C-Cl bond rupture.The relative importance of the primary steps is tentatively estimated to be approximately 100:65:25, respectively.Primarily formed CH=CCl and CH=CF suffer from secondary photolysis absorbing additional photons.More fraction of CH=CF primary yield is decomposed than that of CH=CCl, due to the accidental resonance with the laser excitation line.CH=CH and CH2=CHF are concluded to be formed by the H atom abstraction reaction of CH2=C. and CH=CF. radicals generated during the photolysis respectively, CH2=CF2 beging formed by the recombination reaction between CH2=CF. radical and F atom.In the shock tube pyrolysis the formation of CH=CF predominates over that of CH=CCl.A mechanistic change to form CH=CF in the shock tube pyrolysis is suggested.
Infrared Laser-induced Chemistry of Chlorodifluoromethane-Silane Mixtures at Two Irradiating Wavelengths
Diaz, L.,Santos, M.,Sigueenza, C. L.,Simeonov, S. A.,Gonzalez-Diaz, P. F.,et al.
, p. 3907 - 3912 (1993)
Chemical reactions induced by single- and two-wavelenght CO2 laser radiation in a mixture of silane and chlorodifluoromethane are initiated by the reaction between: CF2 and SiH4 and afford volatile carbonaceous products with C-H bonds, together with a solid deposit consisting of silicon carbide and highly reactive Si/C/H/F polymeric material.The results are in line with the reduction of the strong C-F bond of difluorocarbene and with the production of H2Si=CF2 silene as intermediate which undergoes dehydrofluorination and polymerization.
Vibrational Energy Transfer Probabilities of Highly Vibrationally Excited Fluoroethane and 1,2-Difluoroethane Molecules
Richmond, G.,Setser, D. W.
, p. 2699 - 2705 (1980)
The collisional loss of vibrational energy from chemically activated CH3CH2F and CH2FCH2F formed with average energies of 91 and 92.5 kcal mol-1, respectively, has been studied at 300 K with four bath gases, SF6, CO2, N2, and He.These chemically activated molecules were formed by combination of CH3 with CH2F and of CH2F with CH2F.The data cover an extensive range of pressure and permit the assignment of the mean energy transfer per collision and the form of the transition probability distribution.For He the (ΔEd) values were 1.0 kcal mol-1 with an exponential distribution for both C2H5F and C2H4F2.The (ΔEd) values for C2H5F or C2H4F2 were virtually the same and ranged from 2.0 to 5.0 kcal mol-1 for N2, CO2, and SF6; these transition probability distributions were of the Gaussian type (represented here by a stepladder model).The results for CH3CH2F and CH2FCH2F are compared to previous findings for CH3CF3 and CH2ClCH2Cl from this laboratory.The deactivation efficiency for SF6 is similar for all four molecules.However, the deactivation of CH3CF3 by N2 and CO2 is less efficient than for the other three molecules.The He deactivation efficiencies for the fluoroethanes are all similar, but substantially smaller than for C2H4Cl2.
Two-color multiphoton decomposition of 1-bromo 2-fluoroethane
Mcrae,Ivanco,Goodale
, p. 147 - 158 (1994)
Multiphoton decomposition of 1-bromo 2-fluoroethane (CH2BrCH2F, BFE) with a two-color CO2 infrared laser is reported as a function of number of laser pulses. For single color irradiation at a wavelength chosen to excite BFE, the decomposition product, vinyl fluoride, which accumulates during the many-pulse MPD experiment, is found to deactivate BFE decomposition. When a second laser, tuned to a vinyl flouride absorption is introduced, coincident with the first, the vinyl fluoride is found to activate further BFE decomposition. These results are accounted for in terms of a pressure-dependent model. Changes in model parameters, upon addition of the second laser, are shown to be consistent with interpretations in terms of collision-dependent reaction schemes.
Thermally conductive SiC as support of aluminum fluoride for the catalytic dehydrofluorination reaction
Han, Wenfeng,Li, Ying,Liu, Bing,Liu, Yongnan,Lu, Jiaqin,Tang, Haodong,Yang, Hong,Yu, Wei
, (2020)
Aluminum fluoride (AlF3) is a typical catalyst for dehydrofluorination of hydrofluorocarbons (HFCs) to fluoroolefins with high heat of reaction. Consequently, heat supply and sintering are the key challenges for AlF3-based catalysts. Herein, SiC with high thermal conductivity and resistance to HF corrosion is suggested as a candidate support of AlF3 catalyst. The interaction between AlF3 and SiC leads to uniform distribution of the catalytic phase, and as a result of this, AlF3/SiC exhibits high catalytic activity and stability for the dehydrofluorination of 1,1-difluoroethane to vinyl fluoride. This study proposes a novel catalyst support (SiC) for strong endothermic catalytic reactions involving HFCs for the first time to the best of our knowledge.
Extent of the Displacement Route in the Reactions of Fluorine Atoms with Ethylene. Vinyl Chloride, and Vinyl Bromide
Slagle, Irene R.,Gutman, David
, p. 1818 - 1821 (1983)
The chemical branching of three fluorine-atom reactions, those with C2H4, C2H3Cl, and C2H3Br, was studied in real-time experiments using a tubular reactor coupled to a photoionization mass spectrometer.The fluorine atoms were generated by the CO2-laser-induced secondary photolysis of C6F5Cl which also appears to produce tetrafluorobenzene (c-C6F4).The measured fractional extents that the three reactions studied proceed by a displacement route at 295 K (to yield C2H3F + X) are 0.65 (+/-0.06), 0.72 (+/-0.14), and 0.72(+/-0.14) for C2H4, C2H3Cl, and C2H3Br, respectively.
Thermal Decomposition of 2-Fluoroethanol: Single Pulse Shock Tube and ab Initio Studies
Rajakumar,Reddy,Arunan
, p. 9782 - 9793 (2003)
The thermal decomposition of 2-fluoroethanol (FEOH) was studied at 1000-1200 K behind reflected shock waves in a single pulse shock tube. The total pressures behind the reflected shocks varied between 13 and 23 atm. The products were CH3CHO, C2H3F, CH4, CO, C2H4, and C2H6. The unimolecular eliminations of HF and H2O were the major channels through which FEOH decomposed under these conditions. The rate constants for HF and H2O elimination were presented. The CH3CHO produced by HF elimination through the vinyl alcohol intermediate was chemically active and decomposed leading to CH4 and CH3CH3 products. Ethylene formation could be explained by considering C-O bond dissociation equally well. Direct real-time spectroscopic observation of HOF would be needed to choose between the two pathways. Ab initio (Hartree-Fock [HF] and second-order Moller-Plesset perturbation theory) and density functional theory [DFT] computations overestimated the barrier by 18 kcal/mole for HF elimination and 22 kcal/mole for H2O elimination, and including electron correlation improved the agreement. DFT predictions for activation energies for HF and H2O elimination reactions were within 1 kcal/mole of the experimental values.
Reactions of Fluoromethyl Radicals
Cadman, Philip,Owen, Howell L.
, p. 3087 - 3106 (1981)
1,3-difluoroacetone was photolysed by itself and in the presence of either diethylketone or di-isopropylketone and the rates of the following reactions of fluoromethyl radicals were measured: (i) CH2F + CH2FCOCH2F, log10 (k/cm3 mol-1 s-1) = 11.10 -40000/2.303RT, (ii) CH2F + C2H5COC2H5, log10 (k/cm3 mol-1 s-1) = 10.71 -34050/2.303RT, (iii) CH2F + i-C3H7CO-i-C3H7, log10 (k/cm3 mol-1 s-1) = 11.18 -31550/2.303RT where R= 8.314 J mol-1 K-1.The disproportionation-combination ratios (Δ) for the following pairs of radicals were found to be Δ(CH2F, C2H5) = 0.047, Δ(CH2F, i-C3H7) = 0.210, Δ(i-C3H7, i-C3H7) = 0.55, Δ(C2H5, C2H5) = 0.146.
