A kinetic study of the reaction between ĊH 3 radicals and azoisopropane; reactions of the radicals ĊH 3, (CH3)2 N = NCH(CH3)2 and (CH3)2CH ṄN(CH3)CH(CH3)2

Z. Király; M. Görgényi; L. Seres

doi:10.1051/jcp:1999160

All issues

Volume 96 / No 4 (April 1999)

J. Chim. Phys., 96 4 (1999) 591-609

Abstract

Issue		J. Chim. Phys. Volume 96, Number 4, April 1999


Page(s)		591 - 609
DOI		https://doi.org/10.1051/jcp:1999160

J. Chim. Phys. Vol. 96, N°4, 1999, p. 591-609

A kinetic study of the reaction between ĊH₃ radicals and azoisopropane; reactions of the radicals ĊH₃, (CH₃)₂ N = NCH(CH₃)₂ and (CH₃)₂CH ṄN(CH₃)CH(CH₃)₂

Z. Király¹, M. Görgényi¹ and L. Seres²

¹ Institute of Physical Chemistry, University of Szeged, P.O. Box 105, H-6701 Szeged, Hungary
² Department of Chemistry, J.Gy. Teachers Training College, P.O. Box 396, H-6701 Szeged, Hungary

Abstract

The reaction of ĊH₃ generated from di-tert-butyl peroxide with azoisopropane (AIP) in the temperature range 395-450 K was investigated by product analysis. The regioselectivity of ĊH₃ with the carbon and nitrogen radical centres of (CH₃)₂ N = NCH(CH₃)₂ was determined: $\rm \dot{C}H_3+(CH_3)_2\dot{C}N=NCH(CH_3)_2\to (CH_3)_3CN=NCH(CH_3)_2$ ↦(CH₃)₂C=NN(CH₃)CH(CH₃)₂ k₁₈/k₁₉=1.95±0.24. The Arrhenius parameters of the H-abstraction and decomposition reactions $\rm \dot{C}H_3+AIP\to CH_4+(CH_3)_2\dot{C}N=NCH(CH_3)_2$ $\rm (CH_3)_2CH\dot{N}N(CH_3)CH(CH_3)_2\to 2-\dot{C}_3H_7+(CH_3)_2CHN=NCH_3$ relative to the combinations $\rm 2\dot{C}H_3\to C_2H_6$ $\rm 2\,(CH_3)_2CH\dot{N}N(CH_3)CH(CH_3)_2\to$ (CH₃)₂CHN(CH₃)N(CH(CH₃)₂)N(CH(CH₃)₂)N(CH₃)CH(CH₃)₂ were determined: log[ (k₃/k₁₃^1/2)/mol^-1/2dm^3/2s^-1/2] = (3.1±0.3)-(30.6±2.4) kJ mol^-1/θ log[ k₂₃(φk₂₆^1/2)^-1/mol^1/2dm^-3/2s^-1/2] = (8.8±0.5)-(110.0± 6.5) kJ mol^-1/θ  where θ=RT ln 10 and φ is the cross-combination ratio of ĊH₃ and (CH₃)₂CHṄN(CH₃)CH(CH₃)₂. 

Résumé

Nous avons étudié la réaction des radicaux ĊH₃ générés à partir du péroxyde de ditertiobutyle avec l'azoisopropane (AIP) par analyse des produits. Nous avons déterminé la régioselectivité des radicaux ĊH₃ avec les centres radicalaires du carbone et d'azote de (CH₃)₂ N = NCH(CH₃)₂: $\rm \dot{C}H_3+(CH_3)_2\dot{C}N=NCH(CH_3)_2\to (CH_3)_3CN=NCH(CH_3)_2$ ↦(CH₃)₂C=NN(CH₃)CH(CH₃)₂ k₁₈/k₁₉=1.95±0.24. Nous avons déterminé les paramètres d'Arrhénius des réactions d'abstraction d'hydrogène et de décomposition suivantes: $\rm \dot{C}H_3+AIP\to CH_4+(CH_3)_2\dot{C}N=NCH(CH_3)_2$ $\rm (CH_3)_2CH\dot{N}N(CH_3)CH(CH_3)_2\to 2-\dot{C}_3H_7+(CH_3)_2CHN=NCH_3$ par rapport à ceux des réactions de recombinaison suivantes: $\rm 2\dot{C}H_3\to C_2H_6$ $\rm 2\,(CH_3)_2CH\dot{N}N(CH_3)CH(CH_3)_2\to$ (CH₃)₂CHN(CH₃)N(CH(CH₃)₂)N(CH(CH₃)₂)N(CH₃)CH(CH₃)₂ Les expressions obtenues sont: log[ (k₃/k₁₃^1/2)/mol^-1/2dm^3/2s^-1/2] = (3.1±0.3)-(30.6±2.4) kJ mol^-1/θ log[ k₂₃(φk₂₆^1/2)^-1/mol^1/2dm^-3/2s^-1/2] = (8.8±0.5)-(110.0±6.5) kJ mol^-1/θ où θ=RT ln 10 et φ est la proportion de recombinaison croisée ĊH₃ and (CH₃)₂CHṄN(CH₃)CH(CH₃)₂.

Key words: Gas-phase reaction / methyl radical / H-abstraction / decomposition / azoisopropane / di-tert-butyl peroxide / initiated reaction