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.
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.
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.
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.
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.
Vapor phase hydrofluorination of acetylene to vinyl fluoride over La2O3-Al2O3 catalysts
Bi, Qing-Yuan,Qian, Lin,Xing, Li-Qiong,Tao, Li-Ping,Zhou, Qiang,Lu, Ji-Qing,Luo, Meng-Fei
, p. 528 - 533 (2009)
A series of La-doped Al2O3 catalysts were prepared and tested for the vapor phase hydrofluorination of C2H2 to vinyl fluoride (CH2CHF, VF). It was found that the La-doped catalyst gave a stable cataly
A Photoelectron Spectroscopic Study of the Ground States of CH2F+ and CD2F+
Andrews, Lester,Dyke, John M.,Jonathan, Neville,Keddar, Noureddine,Morris, Alan,Ridha, Abed
, p. 2364 - 2368 (1984)
The fluorine atom/methyl fluoride reaction has been studied by photoelectron spectroscopy.A new product band with vibrational components at 9.04 +/- 0.01 eV adiabatic and 9.22 +/- 0.01 eV vertical ionization energies is assigned to the CH2F free radical.The ν'= 0-1 vibronic separation measured as 1450 +/- 30 cm-1 is due to the C-F stretching fundamental of the ground state of CH2F+; this vibronic interval was 1530 +/- 30 cm-1 for CD2F+.The positive deuterium shift for CH2F+ is due to interaction with the H-C-H bending mode, which shifts below the C-F stretching mode on deuteration.The substantial increase in the C-F stretching modes for CH2F+ and CD2F+, as compared to 1163- and 1193-cm-1 values for the CH2F and CD2F free radicals in solid argon, respectively, is due to increased net C-F bonding in the cations.
Hauge et al.
, p. 6950,6951,6953 (1979)
Formation of β-Fluoroethyl Radical and Closed-Shell Products in Reactions of Photogenerated Fluorine Atoms with Ethene in Solid Argon
Misochko, Eugenii Ya.,Benderskii, Alexander V.,Wight, Charles A.
, p. 4496 - 4502 (1996)
Solid-state reactions of F atoms with ethene molecules were initiated by UV photolysis of dilute solutions of F2 and C2H4 in solid Ar.Products stabilized in the matrix were detected by infrared spectroscopy.Experiments were conducted at different temperatures in order to distinguish reactions in matrix-isolated F2-C2H4 complexes (at 16 K) from reactions of diffusing thermal F atoms (at 26 K).Comparison with the kinetic EPR data (Benderskii, V.A. et al.Mendeleev Commun. 1995, 6, 245) permitted the identification of the infrared spectrum of the β-fluoroethyl radical, which is the main product of the F + C2H4 reaction.Frequencies and absolute absorption intensities of the eight strongest infrared bands of β-C2H4F are reported.Photolysis of isolated F2-C2H4 complexes forms the closed-shell products C2H3F-HF and trans- and gauche-1,2-C2H4F2 with relative yields 0.6:0.2:0.2.Successive addition of two thermal F atoms to an isolated C2H4 molecule forms only the two conformers of 1,2-C2H4F2.The difference between product branching ratios of the latter reaction and the direct photoinduced reaction of F2-C2H4 complexes is qualitatively explained by the difference in size of the reaction cages and excess energies of the vibrationally excited intermediate (C2H4F2)*.
Selective Copper Complex-Catalyzed Hydrodefluorination of Fluoroalkenes and Allyl Fluorides: A Tale of Two Mechanisms
Andrella, Nicholas O.,Xu, Nancy,Gabidullin, Bulat M.,Ehm, Christian,Baker, R. Tom
supporting information, p. 11506 - 11521 (2019/08/20)
The transition to more economically friendly small-chain fluorinated groups is leading to a resurgence in the synthesis and reactivity of fluoroalkenes. One versatile method to obtain a variety of commercially relevant hydrofluoroalkenes involves the catalytic hydrodefluorination (HDF) of fluoroalkenes using silanes. In this work it is shown that copper hydride complexes of tertiary phosphorus ligands (L) can be tuned to achieve selective multiple HDF of fluoroalkenes. In one example, HDF of the hexafluoropropene dimer affords a single isomer of heptafluoro-2-methylpentene in which five fluorines have been selectively replaced with hydrogens. DFT computational studies suggest a distinct HDF mechanisms for L2CuH (bidentate or bulky monodentate phosphines) and L3CuH (small cone angle monodentate phosphines) catalysts, allowing for stereocontrol of the HDF of trifluoroethylene.
