Atmospheric fate of hydrofluoroolefins, CFCHCH (x = 1,2,3,4 and 6): Kinetics with Cl atoms and products.

Rate coefficients for the gas-phase reactions of CFCHCH (x = 1, 2, 3, 4 and 6) with Cl atoms were determined at (298 ± 2) K and (710 ± 5) Torr of air using a relative rate technique. Two experimental setups with simulation chambers were employed with Fourier Transform Infrared (FTIR) spectroscopy and Gas Chromatography coupled to Mass Spectrometry (GC-MS) as detection techniques. The Cl-rate coefficients obtained were (in 10 cm molecule s): (0.85 ± 0.11) for CFCHCH, (1.11 ± 0.08) for CFCHCH, (1.12 ± 0.18) for CFCHCH, (0.97 ± 0.09) for CFCHCH, and (0.99 ± 0.08) for CFCHCH. Additionally, the gas-phase products were identified and quantified, when possible, by FTIR spectroscopy or GC-MS. The main reaction product was reported to be CFC(O)CHCl. The fluorinated species, CFCHO and CFC(O)CHCl, were identified. CFC(O)CHCl and CFCHO were found to be formed with molar yield of (69 ± 5)% and (9 ± 1)%, respectively. The global lifetime of the investigated CFCHCH due to their Cl-reaction is more than 100 days so this route does not compete with the removal by OH radicals. This lifetime is long enough for CFCHCH to be transported to remote areas where they can be degraded. However, at a local scale, in marine regions at dawn the removal of CFCHCH is expected to occur in ca. 1 day. The atmospheric degradation of these hydrofluoroolefins by Cl atoms is not expected to be a source of bioaccumulative perfluorinated carboxylic acids, CFC(O)OH. Additionally, the UV absorption cross sections of CFC(O)CHCl were determined together with the rate coefficient of the OH reaction by an absolute kinetic method at room temperature.