Temperature dependences of the reactions of O(³P) atoms with selected chlorofluoroethenes between 298 and 359 K

Abstract

The rate constants for the gas-phase reactions of ground-state oxygen atoms with CF 2 CFCl (1), (E/Z)-CFCl CFCl (2), CFCl CH 2 (3), and (E/Z)-CFH CHCl (4) have been measured directly using a discharge flow tube coupled to a chemiluminescence detection system. The experiments were carried out under pseudo-first-order conditions with [O( 3 P)] 0 [ethene] 0 . The temperature dependences of the reactions were studied for the first time in the range 298-359 K. The proposed Arrhenius expressions (in units of cm 3 molecule −1 s −1 ) were k 1 = (1.07 ± 0.32) × 10

Kinetics of the Reactions of O(3P) with CCl2CH2, (Z)-CHClCHCl, and CCl2CCl2: A Temperature Dependence Study

“…So The values of rate coefficients and activation energies obtained in the present work appear entirely consistent with the available literature data for the reactions of O( 3 P) atoms with other halogenated alkenes. 10,13,15,16 Kinetics and products analysis for the reactions of O( 3 P) with alkenes show that the initial step proceeds mainly via electrophilic addition of the O( 3 P) atoms the double bond to form an energy-rich biradical which may either collisionally stabilize or unimolecularly decompose to products. 25 The positive activation energies obtained in this work and the pressure independence of the reactions, suggest that the dissociation of the triplet biradical will be a fast process compared with the formation of the adduct.…”

“…Detailed descriptions of the apparatus and the experimental methods used to measure the rate coefficients for the reactions of chloroethenes with O( 3 P) are given in previous papers; , therefore, only a brief description is presented here.…”

“…The aim of this study was to extend our earlier work on the reactivity of chlorinated and fluorinated ethenes − and to determine the temperature dependences of these reactions, to predict the corresponding rate constants in the temperature range studied. Additionally, the reactivity of the chlorinated ethenes with O( 3 P) atoms was correlated with the reactivity of the chloroethenes toward OH radicals and with the complete interaction HOMO−SOMO of the frontier molecular orbital theory (FMOT).…”