UV absorption spectrum, and kinetics and mechanism of the self reaction of CF3CF2O2 radicals in the gas phase at 295 K

Article abstract of DOI:10.1002/kin.550250903

The ultraviolet absorption spectrum, kinetics and mechanism of the self reaction of CF₃CF₂O₂ radicals have been studied in the gas phase at 295 K. Two techniques were used; pulse radiolysis UV absorption to measure the spectrum and kinetics, and long-path length FTIR spectroscopy to identify and quantify the reaction products. Absorption cross sections were quantified over the wavelength range 220-270 nm. At 230 nm, ΣCF₃CF₂O₂ =(2.74±0.46)×10^-18 cm₂ molecule^-1. The observed products following the self reaction of CF₃CF₂O₂ radicals were COF₂CF₃O₃CF₃, CF₃O₃C₂F₅, and CF₃OH. CF₃O₂CF₃ was tentatively identified as a product. The carbon balance was 90-100%. The self reaction of CF₃CF₂O₂ radicals was found to proceed via one channel to produce CF₃CF₂O radicals which then decompose to give CF₃ radicals and COF₂. In the presence of O₂, CF₃ radicals are converted into CF₃O radicals. CF₃O radicals have several fates; self reaction to give CF₃O₂CF₃; reaction with CF₃O₂ radicals to give CF₃O₃CF₃; reaction with C₂F₅O₂ radicals to give CF₃O₃C₂F₅; or reaction with CF₃CF₂H to give CF₃OH. As part of this work a rate constant (2.5±0.6)×10^-16 cm³ molecule^-s^- was measured for the reaction of Cl atoms with CF₃CHF₂ using a relative rate technique. Results are discussed with respect to the atmospheric chemistry of CF₃CF₂H(HFC-125).