Infrared multiphoton dissociation of two perfluorobutenes

Photofragment translational spectroscopy was used to examine the infrared multiphotondissociation of octafluoro-1-butene and octafluoro-2-butene. The predominant unimolecular reaction in octafluoro-1-butene at moderate laser fluences is cleavage of a carbon–carbon single bond to give the products CF3 and C3F5. The two other reactions that take place are CF2 elimination and the formation of equal weight fragments with the chemical compositionC2F4; both reactions take place via a diradical intermediate. Dissociation of octafluoro-1-butene to the resonance stabilized perfluoroallyl radical is suggested to account for the favoring of simple bond rupture. These three reaction pathways were also observed in octafluoro-2-butene dissociation, however, the branching fraction is different than from octafluoro-1-butene. In octafluoro-2-butene all three channels occur with roughly equal probability. The reactions involving CF2 loss and C2F4 formation in octafluoro-2-butene are thought to proceed through the same diradical intermediate as in octafluoro-1-butene, necessitating a 1,2-fluorine migration

An experimental and kinetic modeling study of the reaction of CHF₃ with methane

The gas-phase reaction of CHF₃ with CH₄ has been studied experimentally and computationally. The motivation behind the study is that reaction of CHF₃ with CH₄ provides a possible route for synthesis of CH₂=CF₂ (C₂H₂F₂). Experiments are carried out in a plug flow, isothermal α-alumina reactor at atmospheric pressure over the temperature range of 973-1173 K. To assist in understanding the reaction mechanism and the role of the reactor material involved in the reaction of CHF₃ with CH₄, the reaction of CHF₃ with CH₄, pyrolysis of CH₄, and pyrolysis of CHCIF₂ have been studied in the presence of α-alumina or α-AIF₃ particles under various conditions. Under all conditions studied for the reaction of CHF₃ and CH₄, the major products are C₂F₄, C₂H₂F₂, and HF. Minor products include C₂H₂, C₂H₄, C₂H₃F, C₂HF₃, C₃F₆, CO₂, and H₂. C₂H₆, CH₂F₂, and CHF₂CHF₂ are detected in trace amounts. The initial step is the gas-phase unimolecular decomposition of CHF₃, producing CF₂ and HF. It is proposed that CF₂ decomposes on the surface of α-alumina, producing F radicals that are responsible for the activation of CH₄. A reaction scheme developed on the basis of the existing NIST HFC and GRI-Mech 3.0 mechanisms is used to model the reaction of CHF₃ with CH₄. Generally satisfactory agreement between experimental and modeling results is obtained on the conversion levels of CHF₃ and CH₄ and rates of formation of major products. Using the software package AURORA, the reaction pathways leading to the formation of major products are elucidated