, Volume 16, Issue 2, pp 157-167

Determination of rate constants for reactions of some hydrohaloalkanes with OH radicals and their atmospheric lifetimes

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Abstract

Rate constants have been measured for the gas-phase reactions of hydroxyl radical with partly halogenated alkanes using the discharge-flow-EPR technique over the temperature range 298–460 K. The following Arrhenius expressions have been derived (units 10−13 cm3 molecule−1 s−1): (8.1 −1.2 +1.5 ) exp{−(1516±53)/T} for CHF2Cl (HCFC-22); (10.3 −1.5 +1.8 ) exp{−(1588±52)/T} for CH2FCF3 (HFC-134a); (11.3 −1.6 +2.1 ) exp{−(918±52)/T} for CHCl2CF2Cl (HCFC-122); (9.2 −2.0 +2.5 ) exp{−(1281±85)/T} for CHFClCF2Cl (HCFC-123a).

The atmospheric lifetimes for the substances have been estimated to be 12.6, 12.9, 1.05, and 4.8 years, respectively, and the accuracy of the estimates is discussed.