CH3OCF2CHFCl and CHF2OCF2CHCFCl: Reaction with Cl atoms, atmospheric lifetimes, ozone depletion and global warming potentials

P. DALMASSO, R. TACCONE, J. NIETO, M. TERUEL AND S. LANE.

ATMOSPHERIC ENVIRONMENT

Año: 2006 vol. 40 p. 7298 - 7307

1352-2310

  Haloethers are expected to be an acceptable alternative to decrease the harmful effects of chlorofluorocarbons (CFCs) and their derivates in the atmosphere. The relative rate technique has been used to determine the rate constants of the reactions of Cl atoms with 2-chloro-1,1,2-trifluoroethyl-methyl-ether (CH3OCF2CHFCl) and 2-chloro-1,1,2-trifluoroethyl-difluoromethyl-ether (CHF2OCF2CHFCl). Experiments were carried out at 296 ± 2 K and atmospheric pressure using nitrogen or synthetic air as bath gases. The decay rates of the organic species were measured relative to those of 1,2-dichloroethane, dichloromethane and 1,1,1,2-tetrafluoroethane. The following rate coefficients were derived for the reaction of Cl atoms (in units of cm3 molecule-1s-1) with CH3OCF2CHFCl, k = (3.24 ± 0.49) x 10-13 and CHF2OCF2CHFCl, k = (3.20 ± 0.32) x 10-15. The rate constants obtained are compared with previous literature data to establish reactivity trends and used to estimate the atmospheric lifetimes for the studied ethers. From the calculated lifetimes, using average global concentrations of Cl atoms and OH radicals, the atmospheric loss of CH3OCF2CHFCl and CHF2OCF2CHFCl is determined by the OH initiated oxidation. The atmospheric implications of these reactions are discussed based on the calculated ozone depletion potential (ODP) and global warming potential (GWP) of the ethers.