Measurements of Radical Reactivity with an Imine, (CF3)2CNH: Rate Constants for Chlorine Atoms and Hydroxyl Radicals and the Global Warming Potential

The rate constant <i>k</i>_OH for the reaction of 1,1,1,3,3,3-hexafluoroprop-2-imine with OH radicals was measured relative to two reference compounds, CH₃F and CH₃CHF₂, to be <i>k</i>_OH = (4.2 ± 1.1) × 10^-14 cm³ molecule^-1 s^-1 at 295 K. This implies an atmospheric lifetime with respect to consumption by OH of 0.75 years. Reaction with Cl atoms yielded <i>k</i>_Cl = (7.9 ± 1.7) × 10^-16 cm³ molecule^-1 s^-1 at 295 K, and reaction with O₃ has an upper limit of <i>k</i>_O3 < 4 × 10^-23 cm³ molecule^-1 s^-1, so that the atmospheric consumption by Cl and O₃ is negligibly slow. Absolute infrared cross sections of the imine yield a radiative efficiency of 0.34 W m^-2 ppb^-1, which is corrected to 0.23 W m^-2 ppb^-1 for the effects of atmospheric lifetime. The imine's corresponding 100-year global warming potential is 64 ± 19. This value is an upper limit, given that heterogenous atmospheric removal paths, such as hydrolysis in water droplets, are not included.