Atmospheric chemistry of perfluorobutenes (CF3CFCFCF3 and CF3CF2CFCF2): Kinetics and mechanisms of reactions with OH radicals and chlorine atoms, IR spectra, global warming potentials, and oxidation to perfluorocarboxylic acids

Relative rate techniques were used to determine k(Cl + CF3CFCFCF3) = (7.27 ± 0.88) × 10−12, k(Cl + CF3CF2CFCF2) = (1.79 ± 0.41) × 10−11, k(OH + CF3CFCFCF3) = (4.82 ± 1.15) × 10−13, and k(OH + CF3CF2CFCF2) = (1.94 ± 0.27) × 10−12 cm3 molecule−1 s−1 in 700 Torr of air or N2 diluent at 296 K. The chlorine atom- and OH radical-initiated oxidation of CF3CFCFCF3 in 700 Torr of air gives CF3C(O)F in molar yields of 196 ± 11 and 218 ± 20%, respectively. Chlorine atom-initiated oxidation of CF3CF2CFCF2 gives molar yields of 97 ± 9% CF3CF2C(O)F and 97 ± 9% COF2. OH radical-initiated oxidation of CF3CF2CFCF2 gives molar yields of 110 ± 15% CF3CF2C(O)F and 99 ± 8% COF2. The atmospheric fate of CF3CF2C(O)F and CF3C(O)F is hydrolysis to give CF3CF2C(O)OH and CF3C(O)OH. The atmospheric lifetimes of CF3CFCFCF3 and CF3CF2CFCF2 are determined by reaction with OH radicals and are approximately 24 and 6 days, respectively. The contribution of CF3CFCFCF3 and CF3CF2CFCF2 to radiative forcing of climate change will be negligible.