28761-00-4Relevant academic research and scientific papers
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 (2007/10/03)
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)*.
Computational Studies of the Bimolecular Reaction Dynamics of the C2H4 + F2 System
Raff, Lionel M.
, p. 141 - 147 (2007/10/02)
The bimolecular reaction dynamics of C2H4 + F2 on a previously described potential energy surface have been investigated by using quasi-classical trajectory methods.All important reaction channels are open on this potential surface, and the calculated equilibrium geometries, reaction exothermicities and fundamental vibration frequencies are in fair-to-good accord with measured values.The major reaction products are found to be either CH2CH2F + F or CH2=CHF + HF. 1,2-Difluoroethane is found as a reaction intermediate leading to CH2=CHF + HF but is never observed as a final product.The calculated reaction cross sections are all less than 5 Angstroem2 even for translational energies more than 1 eV in excess of the reaction threshold.Almost all of the reaction exothermicity is partitioned into the internal modes of CH2CH2F or CH2=CHF.Very little of this energy appears as relative translational motion of the products.HF is usually formed in the ν = 0, 1, or 2 vibrational state.The calculated center-of-mass differential cross section for fluorine atom scattering shows a strong backward component along with an isotropic component.The first of these is shown to arise from a direct reaction mechanism; the second is the result of complex formation.Formation of fluoroethylene is shown to occur via a complex mechanism involving formation of 1,2-difluoroethane as an intermediate.The calculated thermal rate coefficients for CH2CH2F and CH2=CHF formation are 1.38E14*exp and 1.90E13*exp cm3/(mol*s), respectively.There is some suggestion of mode-specific rate enhancement for the reaction leading to CH2CH2F but not for the formation of CH2=CHF.In the first case, the C-H stretching modes are found to be the most effective in enhancing the rate.The results are compared and contrasted with gas-phase data reported by Kapralova et al. and with the matrix isolation results obtained by Frei et al.
