INFIQC   05475
INSTITUTO DE INVESTIGACIONES EN FISICO- QUIMICA DE CORDOBA
Unidad Ejecutora - UE
artículos
Título:
The gas phase reactions of O(3P) with perhalogenated butenes: absolute rate constants and temperature dependences
Autor/es:
PABLO M. COMETTO, RAÚL A. TACCONE AND SILVIA I. LANE
Revista:
CHEMICAL PHYSICS LETTERS
Editorial:
Elsevier
Referencias:
Año: 2007 vol. 442 p. 245 - 250
ISSN:
0009-2614
Resumen:
Abstract: Absolute rate coefficients for the gas-phase reactions of O(3P) atoms with CF3CF=CFCF3, CF3CF=CClCF3 and CF3CCl=CClCF3 have been measured using a discharge flow tube coupled to a chemiluminescence detection system. The experiments were carried out under pseudo-first-order conditions with [O(3P)]0 << [butene]0. The temperature dependences of the reactions were studied for the first time in the range 298-359 K. The Arrhenius expressions obtained (in units of cm3 molecule-1s-1) were: k1 = (0.32 ±1s-1) were: k1 = (0.32 ± 0.05) x 10-12 exp[-(8.1 ± 0.5)x103 / RT], k2 = (1.50 ± 0.74) x 10-11 exp[-(17.7 ± 1.4)x103 / RT] and k3 = (2.58 ± 1.10) x 10-11 exp[-(18.0 ± 1.2)x103 / RT]. All the rate constants display a positive temperature dependence pointing to the importance of the irreversibility of the addition channel for these reactions. Complete substitution of H by halogen atoms in propenes and butenes results in dramatic reduction of the rate constants. The reactivity trend with the ionization potential is also analyzed.10-12 exp[-(8.1 ± 0.5)x103 / RT], k2 = (1.50 ± 0.74) x 10-11 exp[-(17.7 ± 1.4)x103 / RT] and k3 = (2.58 ± 1.10) x 10-11 exp[-(18.0 ± 1.2)x103 / RT]. All the rate constants display a positive temperature dependence pointing to the importance of the irreversibility of the addition channel for these reactions. Complete substitution of H by halogen atoms in propenes and butenes results in dramatic reduction of the rate constants. The reactivity trend with the ionization potential is also analyzed.± 1.10) x 10-11 exp[-(18.0 ± 1.2)x103 / RT]. All the rate constants display a positive temperature dependence pointing to the importance of the irreversibility of the addition channel for these reactions. Complete substitution of H by halogen atoms in propenes and butenes results in dramatic reduction of the rate constants. The reactivity trend with the ionization potential is also analyzed.