Kinetics and Mechanisms for the Reactions of CF₃OCH₃ and CF₃OC(O)H with OH Radicals Using an Environmental Reaction Chamber

Abstract

The atmospheric chemistry of CF3OCH3, a possible HCFCs/HFCs substitute was studied using a smog chamber/FTIR technique. The ether was reacted with OH radicals prepared by photolysis of ozone in 100 Torr of an H2O/O2/He gas mixture in a 1 m3 temperature-controlled chamber. Using a relative rate method, k(OH + CF3OCH3) = (4.22 ± 0.84) × 10-12 exp[(−1750 ± 350)/T] cm3 molecule-1 s-1 over the temperature range 268−308 K. The rate constant at 298 K was (1.19 ± 0.14) × 10-14 cm3 molecule-1 s-1. The products of the OH radical initiated degradation of CF3OCH3 were investigated in 100−230 Torr of an O2/He gas mixture at 298 K using in situ FTIR spectroscopy. k(OH + CF3OC(O)H) = (1.68 ± 0.20) × 10-14 cm3 molecule-1 s-1 at 298 K was determined. The major products of the oxidation of CF3OC(O)H were COF2 and CO2. These results are discussed with respect to the atmospheric chemistry of CF3OCH3 and CF3OC(O)H.