title: Shock wave studies of the pyrolysis of fluorocarbon oxygenates. I. The thermal dissociation of C3F6O and CF3COF.
abstract: The thermal decomposition of hexafluoropropylene oxide, C3F6O, to perfluoroacetyl fluoride, CF3COF, and CF2has been studied in shock waves highly diluted in Ar between 630 and 1000 K. The measured rate constant k1= 1.1 × 1014exp(-162(±4) kJ mol-1/RT) s-1agrees well with literature data and modelling results. Using the reaction as a precursor, equimolar mixtures of CF3COF and CF2were further heated. Combining experimental observations with theoretical modelling (on the CBS-QB3 and G4MP2 ab initio composite levels), CF3COF is shown to dissociate on two channels, either leading to CF2+ COF2or to CF3+ FCO. By monitoring the CF2signals, the branching ratio was determined between 1400 and 1900 K. The high pressure rate constants for the two channels were obtained from theoretical modelling as k5,∞(CF3COF → CF2+ COF2) = 7.1 × 1014exp(-320 kJ mol-1/RT) s-1and k6,∞(CF3COF → CF3+ FCO) = 3.9 × 1015exp(-355 kJ mol-1/RT) s-1. The experimental results obtained at [Ar] ≈ 5 × 10-6mol cm-3were consistent with modelling results, showing that the reaction is in the falloff range of the unimolecular dissociation. The mechanism of secondary reactions following CF3COF dissociation has been analysed as well.
authors.affiliation: INIFTA, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Argentina.
authors.forename: C J
authors.initials: CJ
authors.lastname: Cobos
authors.affiliation: Dyneon GmbH, Gendorf, D-84508 Burgkirchen, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Hintzer
authors.affiliation: Institut für Physikalische Chemie, Universität Göttingen, Tammannstrasse 6, D-37077 Göttingen, Germany. jtroe@gwdg.de.
authors.forename: L
authors.initials: L
authors.lastname: Sölter
authors.affiliation: Institut für Physikalische Chemie, Universität Göttingen, Tammannstrasse 6, D-37077 Göttingen, Germany. jtroe@gwdg.de.
authors.forename: E
authors.initials: E
authors.lastname: Tellbach
authors.affiliation: Dyneon GmbH, Gendorf, D-84508 Burgkirchen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Thaler
authors.affiliation: Institut für Physikalische Chemie, Universität Göttingen, Tammannstrasse 6, D-37077 Göttingen, Germany. jtroe@gwdg.de and Max-Planck-Institut für Biophysikalische Chemie, Am Fassberg 11, D-37077 Göttingen, Germany.
authors.forename: J
authors.identifier: http://orcid.org/0000-0002-4347-0307
authors.initials: J
authors.lastname: Troe