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KINETIC STUDIES OF THE REACTION OF HYDROXYL RADICALS WITH TRICHLOROETHYLENE AND TETRACHLOROETHYLENE. (R826169)
Tichenor, L. B., A. El-Sinawi, T. Yamada, P. H. Taylor, J. Peng, X. Hu, AND P. Marshall. KINETIC STUDIES OF THE REACTION OF HYDROXYL RADICALS WITH TRICHLOROETHYLENE AND TETRACHLOROETHYLENE. (R826169). CHEMOSPHERE. Elsevier Science Ltd, New York, NY, 42(5-7):571-577, (2001).
Rate coefficients are reported for the gas-phase reaction of the hydroxyl radical (OH) with C2HCl3 (k1) and C2Cl4 (k2) over an extended temperature range at 740±10 Torr in a He bath gas. These absolute rate measurements were accomplished using a laser photolysis/laser-induced fluorescence (LP/LIF) technique under slow flow conditions. The simple Arrhenius equation adequately describes the low temperature data for k1 (<650 K) and the entire data set for k2 and is given by (in units of cm3 molecule-1 s-1):
Error limits are 2 values. The room temperature values for k1 and k2 are within ±2 of previous data using different techniques. The Arrhenius activation energies for k1 and k2 are a factor of 2¯3 lower than previously reported values. The experimental measurements for both k1 and k2 in conjunction with transition state and variation transition state theory calculations infer an OH addition mechanism. The lack of a measurable kinetic isotope effect for k1 is consistent with this mechanism. Insight into the subsequent reactions of the chemically activated intermediate are presented in the form of potential energy diagrams derived from ab initio calculations.
Author Keywords: Chlorinated hydrocarbons; Hydroxyl; Kinetics; Oxidation, reaction mechanisms
Record Details:Record Type: DOCUMENT (JOURNAL/PEER REVIEWED JOURNAL)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL CENTER FOR ENVIRONMENTAL RESEARCH