The infrared multiphoton dissociation of hexafluoroethane

Abstract

. ' The infrared multiphoton dissociation of hexafluoroethane. Can. J. Chem. 66, 609 (1988). The infrared multiphoton dissociation (IRMPD) of "neat" hexafluoroethane has been investigated for the first time. The stable products of photolysis are CF4, C2F4, C3F8, and C4FI0. Product analysis involved tunable diode laser (TDL) and fourier transform infrared spectroscopy, as well as gas chromatography where applicable. The high sensitivity and resolution of the TDL allows for measurement of the stable products CF4 and C2F4 after irradiation by a single infrared laser pulse. The yield of .CF3 radicals produced by the IRMPD of C2F6 as a function of fluence was measured via the TDL high frequency modulation technique. The role of added H2, leading to elimination of CF4 and increase of C2F4 as products, is clarified. CARL E. BROWN et DONALD R. SMITH. The infrared multiphoton dissociation of hexafluoroethane. Can. J. Chem. 66, 609 (1988). On a CtudiC pour la premikre fois la dissociation multiphotonique infrarouge (DMPIR) de I'hexafluoroCthane 1'Ctat pur. Les produits stables de la photolyse sont le CF4, le C2F4, le C3F8 et le C4FI0. Dans les cas ou ces techniques pouvaient &tre appliqukes pour l'analyse des produits, on a utilisC un laser a diode ajustable (LDA), la spectroscopie infrarouge par transformation de fourier ainsi que la chromatographie en phase gazeuse. La sensibilitC ClevCe et la grande rCsolution du LDA permettent de mesurer les produits stables, comme le CF4 et le C2F4, aprks une irradiation par une seule pulsation du laser infrarouge. On a utilisC la technique de modulation de la haute frCquence du LDA pour mesurer le rendement en radicaux 'CF3 produits par DMPIR du C2F6, en fonction de la fluiditC. On a Cclairci le r81e du Hz ajoutC sur I'Climination de CF4 et l'augmentation du C2F4. comme produits de la rtaction.[Traduit par la revue] Introduction In earlier work Fisk (I) reported C2F4 and CHF3 as the products of the infrared multiphoton dissociation (IRMPD) of hexafluoroethane in the presence of Hz or C6H14. Several years later Arai et al. (2) studied the IRMPD of hexafluoroethane in the presence of Br2, the results of their experiments indicated that the major reaction products were CF3Br and CF2Br2. Our exploratory work on the IRMPD of "neat" hexafluoroethane showed that CF4 was the major photolysis product, with lesser amounts of C2F4, C3F8, and C4F10 Thermodynamically, the most favourable dissociation pathway of C2F6 leads to the production of CF4 and :CF2. However, shock tube studies (3) suggest that this pathway possesses a large energy barrier. The next most favourable pathway is the result of C 4 bond scission forming two 'CF3 radicals, reaction [2]. Presumably the pre-exponential factor favours reaction [2] as well, since it only involves C 4 bond breakage.

Treatment technologies for aqueous perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA)

“…The thermolysis of fluorochemicals has been documented experimentally under more controlled conditions to determine individual reaction kinetics and mechanisms [230][231][232][233][234][235][236][237][238][239][240][241], and under more industrial conditions to test incinerability [81,111,113] or other thermal degradation processes [242]. A comprehensive experimental and theoretical database of C 1 and C 2 fluorochemical pyrolytic and combustion mechanisms, thermochemistry, and kinetics has been reported [243].…”