Discharge flow reaction kinetic studies of O(P-3) with chloroethylenes CH2CCl2, CHClCCl2, CCl2CCl2

The reaction of oxygen atoms [O(P-3)] with chloroethylenes (RCl) viz. CH2CC l2, CHClCCl2, CCl2CCl2 was studied in a discharge flow set up in the pressu re range of 1.2-1.5 Torr, employing the O(P-3) chemiluminescence titration method. The bimolecular rate constant for the reactions O(P-3) + RCl produc ts, are determined at room temperature to be (6.6 +/- 1.1) X 10(-13), (5.9 +/- 0.8) X 10(-13) and(1.9 +/- 0.3) X 10(-13) cm(3) molecule(-1) s(-1) for CH2CCl2, CHClCCl2 and CCl2CCl2, respectively. Detailed ab initio calculatio ns with the MNDO parametrization method 3 (PM3) are used to evaluate the ki netic and thermodynamic parameters. Formation of a biradical involving addi tion of an oxygen atom to the double bend is proposed as the major channel for the reaction. Unimolecular decomposition of the biradical formed was st udied using RRKM theory. (C) 2000 Elsevier Science B.V. All rights reserved .