Laser photolysis/laser-induced fluorescence studies of the reaction of hydroxyl with 1,1,1,2- and 1,1,2,2-tetrachloroethane over an extended temperature range
作者:Zhen Jiang、Philip H. Taylor、Barry Dellinger
DOI:10.1021/j100121a033
日期:1993.5
Absolute rate coefficients are reported for the gas-phase reaction of OH radicals with 1,1,1,2-(k1) and 1,1,2,2-tetrachloroethane (k2) over an extended temperature range. Employing a laser photolysis/laser-induced fluorescence technique, experiments were conducted with a flow system at a total pressure of 740 +/- 10 Torr using He as diluent and carrier gas. The temperature dependence of the rate coefficients was best described by the modified Arrhenius expressions k1(293-882 K) = (3.36 +/- 0.52) X 10(-12)(T/300)1.21 exp[(-1553 +/- 92)/T] cm3 molecule-1 s-1 and k2(295-701 K) = (2.72 +/- 0.42) X 10(-12)(T/300)0.22 exp[(-915 +/- 62)/T] cm3 molec-1 s-1. The room temperature reactivity of k1 is nearly an order of magnitude less than k2. The difference in reactivity is discussed in terms of C-H bond dissociation energies and polarity changes in the transition state induced by the presence of beta Cl substitution. Revised substituent factors for Atkinson's structure-activity relationship model derived from our experimental measurements are shown to improve the predictions of this model.