Atmospheric Chemistry of CF₃CF=CF₂: Kinetics and Mechanism of Its Reactions with OH Radicals, Cl Atoms, and Ozone

Abstract

Smog chamber/FTIR techniques were used to study the OH radical, the Cl atom, and ozone initiated oxidation of CF3CFCF2 in 700 Torr of air at 296 K. Relative rate methods were used to measure k(OH + CF3CFCF2) = (2.4 ± 0.3) × 10-12 and k(Cl + CF3CFCF2) = (2.7 ± 0.3) × 10-11; absolute techniques were used to derive an upper limit of k(O3 + CF3CFCF2) < 3 × 10-21 cm3 molecule-1 s-1. OH radical and Cl atom-initiated atmospheric oxidation of CF3CFCF2 gives COF2 and CF3C(O)F in molar yields of 100%. The atmospheric lifetime of CF3CFCF2 is approximately 9 days with degradation proceeding via reaction with OH radicals to give trifluoroacetic acid in a molar yield of 100%. Results are discussed with respect to previous measurements of k(OH + CF3CFCF2) and k(O3 + CF3CFCF2) and the potential importance of CF3CFCF2 as a source of trifluoroacetic acid.