Kinetic Study of the OH Radical Reactions with CF3CCl=CCl2 , CF3CCl=CClCF3 and CF3CF=CFCF3. Atmospheric Lifetimes, Ozone Depletion and Global Warming Potentials.

PABLO M. COMETTO, RAÚL A. TACCONE, JORGE D. NIETO, PABLO R. DALMASSO, SILVIA I. LANE

Chemphyschem

WILEY-V C H VERLAG GMBH

Año: 2010 p. 4053 - 4059

1439-4235

The relative rate technique has been used to determine the rate constants of the reactions of OH radicals with CF3CCl=CCl2 (k1), CF3CCl=CClCF3 (k2) and CF3CF=CFCF3 (k3). Experiments were carried out at (298±2) K and atmospheric pressure using ultrapure nitrogen as gas bath. The decay rates of the organic species were measured relative to those of ethane, methanol, acetone, chloroethane and 2-butanone. The following rate constants were derived in units of cm3 molecule-1 s-1: k1= (10±1) x10-13, k2= (2.1±0.2) x10-13 and  k3= (3.7±0.2) x10-13. This is the first experimental determination of k1 and k2. The rate constants obtained are compared with previous literature data to establish reactivity trends and used to estimate the atmospheric lifetimes for the studied perhaloalkenes. From the calculated lifetimes, using an average global concentrations of hydroxyl radicals, the atmospheric loss of these compounds by the OH-initiated oxidation was determined. Also, estimations have been made of the ozone depletion potential (ODP), radiative forcing efficiency (RE), the halocarbon global warming potential (HGWP) and global warming potential (GWP) of the perhaloalkenes. The approximate nature of these values is stressed considering that these are short-lived compounds for which these atmospheric parameters may vary according to latitude and season.