| Issue |
J. Chim. Phys.
Volume 93, 1996
|
|
|---|---|---|
| Page(s) | 253 - 273 | |
| DOI | https://doi.org/10.1051/jcp/1996930253 | |
| Published online | 29 May 2017 | |
Thermal reaction of (CH3)2C=C(CH3)2 in the presence of di-tert-butyl peroxide; reactions of the radicals ˙CH3, (CH3)3C˙C(CH3)2 and (CH3)2C=C(CH3)˙CH2
1
Institute of Physical Chemistry, AJ University, H-6701 Szeged, POB 105, Hungary.
2
Gy J Teacher's Training College, H-6701 Szeged, POB 396, Hungary.
A study of the thermal reaction of (CH3)2C=C(CH3)2 (23DMB2) in the presence of di-t-butyl peroxide (PODBT) at 389-451 K yielded kinetic data on some reactions of the radicals ˙CH3, (CH3)3C˙C(CH3)2 (1122TMP˙) and (CH3)2C=C(CH3)˙CH2 (112TMA˙).
The ratio of the cross-combination ratios of the radicals ϕ(112ΤΜΑ˙,1122ΤΜΡ˙)/ϕ(CΗ3,1122ΤΜΡ˙) and the rate constant for H-abstraction from 23DMB2 by ˙CH3 relative to that of the recombination reaction,
˙CH3 + (CH3)2C=C(CH3)2 → СН4 + (СН3)2С=С(СН3)˙СН2 (4)
2 ˙CH3 → C2H6 (7)
have been determined. The values are
ϕ(1122TMP˙, 112ΤΜΑ˙)/ϕ˙CΗ3,1122TMP˙) = 0.9 ± 0.3
log(k4/k71/2) = (3.74 ± 0.21) - (36.3 ± 2.2)/Θ
where Θ = RT ln 10 and the units are dm3/2 mol-1/2 s-1/2 for k4/k71/2, and kJ mol-1 for the energy of activation.
Résumé
Une étude de la réaction thermique du diméthyl-2,3-butene-2 (23DMB2) en présence de peroxyde de di-t-butyle (PODBT), entre 389 et 451 K, a permis d'obtenir des données cinétiques sur la réaction des radicaux ˙CH3, (СН3)3С˙С(СН3)2 (1122TMP˙) et (CH3)2C=C(CH3)˙CH2 (112TMA˙). On a determiné la valeur relative du rapport des combinaisons croisées aux combinaisons individuelles des radicaux ϕ(112ТМА˙, 1122ТМР˙)/ϕ(˙СН3, 1122ТМР˙) et le rapport de la constante de vitesse d'arrachement, par ˙CH3, d'un atome H de 23DMB2 a celle de combinaison de deux 3CH3:
˙CH3 + (CH3)2C=C(CH3)2 → СН4 + (СН3)2С=С(СН3)˙СН2 (4)
2 ˙CH3 → C2H6 (7)
Les valeurs obtenues sont:
ϕ(1122TMP˙, 112ΤΜΑ˙)/ϕ˙CΗ3,1122TMP˙) = 0.9 ± 0.3
log(k4/k71/2) = (3.74 ± 0.21) - (36.3 ± 2.2)/Θ
ou Θ = RT ln 10 et les unités sont en dm3/2 mol-1/2 s-1/2 pour k4/k71/2, et en kJ mol-1 pour les énergies d'activation.
Key words: ˙CH3 - (CH3)3C˙C(CH3)2 / 1,1,2-trimetbylallyl radical / 2,3-dimethylbut-2 -ene - gas-phase reaction
© Elsevier, Paris, 1996