Estimation of rate constants for hydrogen atom abstraction by OH radicals using the C-H bond dissociation enthalpies: Haloalkanes and haloethers

We propose a semiempirical procedure for the estimation of the rate constants for hydrogen atom abstraction reactions of OH radicals with haloalkanes and haloethers. our procedure is derived from the collision theory based kinetic equation, which was originally proposed by Heicklen (Int. J. Chem. Kinet. 1981, 13, 65 1). This equation provides the estimates for the rate constants of hydrogen abstraction from the C-H bond dissociation enthalpy for each potential hydrogen atom abstraction site. We reparameterized the equation and then applied this procedure to a series of haloalkane and haloether molecules. The results obtained from the new equations are found to be quite satisfactory. In addition, we also report highly reliable calculated values of the C-H bond dissociation enthalpies for six environmentally important haloether molecules (CH2FOCH2F, CHF2CF2OCH2CF3, CF3CH2OCH2CF3, CF3CF2CH2OCHF2, CHF2OCF2CHFCl, and CHF2OCHClCF3). (C) 2002 Wiley Periodicals, Inc.