Free Access
Issue
J. Chim. Phys.
Volume 96, Number 4, April 1999
Page(s) 591 - 609
DOI https://doi.org/10.1051/jcp:1999160
DOI: 10.1051/jcp:1999160


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

A kinetic study of the reaction between CH 3 radicals and azoisopropane; reactions of the radicals CH 3, (CH 3) 2 N = NCH(CH 3) 2 and (CH 3) 2CH NN(CH 3)CH(CH 3) 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 CH 3 generated from di-tert-butyl peroxide with azoisopropane (AIP) in the temperature range 395-450 K was investigated by product analysis. The regioselectivity of CH 3 with the carbon and nitrogen radical centres of (CH 3) 2 N = NCH(CH 3) 2 was determined:

\begin{displaymath}\rm\dot{C}H_3+(CH_3)_2\dot{C}N=NCH(CH_3)_2\to (CH_3)_3CN=NCH(CH_3)_2
\end{displaymath}


\begin{displaymath}\rm\to (CH_3)_2C=NN(CH_3)CH(CH_3)_2
\end{displaymath}

$k_{18}/k_{19}=1.95\pm0.24$. The Arrhenius parameters of the H-abstraction and decomposition reactions

\begin{displaymath}\rm\dot{C}H_3+AIP\to CH_4+(CH_3)_2\dot{C}N=NCH(CH_3)_2
\end{displaymath}


\begin{displaymath}\rm (CH_3)_2CH\dot{N}N(CH_3)CH(CH_3)_2\to 2-\dot{C}_3H_7+(CH_3)_2CHN=NCH_3
\end{displaymath}

relative to the combinations

\begin{displaymath}\rm 2\dot{C}H_3\to C_2H_6
\end{displaymath}


\begin{displaymath}\rm 2\,(CH_3)_2CH\dot{N}N(CH_3)CH(CH_3)_2\to
\end{displaymath}


\begin{displaymath}\rm (CH_3)_2CHN(CH_3)N(CH(CH_3)_2)N(CH(CH_3)_2)N(CH_3)CH(CH_3)_2
\end{displaymath}

were determined: log[ ( k3/k131/2)/mol -1/2dm 3/2s -1/2] = $(3.1\pm0.3)-(30.6\pm2.4)$ kJ mol $^{-1}/\theta$

log[ $k_{23}(\phi k_{26}^{1/2})^{-1}$/mol 1/2dm -3/2s -1/2] = $(8.8\pm 0.5)-(110.0\pm$ 6.5) kJ mol $^{-1}/\theta$

where $\theta=RT$ ln 10 and $\phi$ is the cross-combination ratio of CH 3 and (CH 3) 2CHNN(CH 3)CH(CH 3) 2.

Résumé
Nous avons étudié la réaction des radicaux CH 3 générés à partir du péroxyde de ditertiobutyle avec l'azoisopropane (AIP) par analyse des produits. Nous avons déterminé la régioselectivité des radicaux CH 3 avec les centres radicalaires du carbone et d'azote de (CH 3) 2 N = NCH(CH 3) 2:

\begin{displaymath}\rm\dot{C}H_3+(CH_3)_2\dot{C}N=NCH(CH_3)_2\to (CH_3)_3CN=NCH(CH_3)_2
\end{displaymath}


\begin{displaymath}\rm\to (CH_3)_2C=NN(CH_3)CH(CH_3)_2
\end{displaymath}

$k_{18}/k_{19}=1.95\pm0.24$. Nous avons déterminé les paramètres d'Arrhénius des réactions d'abstraction d'hydrogène et de décomposition suivantes:

\begin{displaymath}\rm\dot{C}H_3+AIP\to CH_4+(CH_3)_2\dot{C}N=NCH(CH_3)_2
\end{displaymath}


\begin{displaymath}\rm (CH_3)_2CH\dot{N}N(CH_3)CH(CH_3)_2\to 2-\dot{C}_3H_7+(CH_3)_2CHN=NCH_3
\end{displaymath}

par rapport à ceux des réactions de recombinaison suivantes:

\begin{displaymath}\rm 2\dot{C}H_3\to C_2H_6
\end{displaymath}


\begin{displaymath}\rm 2\,(CH_3)_2CH\dot{N}N(CH_3)CH(CH_3)_2\to
\end{displaymath}


\begin{displaymath}\rm (CH_3)_2CHN(CH_3)N(CH(CH_3)_2)N(CH(CH_3)_2)N(CH_3)CH(CH_3)_2
\end{displaymath}

Les expressions obtenues sont: log[ ( k3/k131/2)/mol -1/2dm 3/2s -1/2] = $(3.1\pm0.3)-(30.6\pm2.4)$ kJ mol $^{-1}/\theta$ log[ $k_{23}(\phi k_{26}^{1/2})^{-1}$/mol 1/2dm -3/2s -1/2] = $(8.8\pm 0.5)-(110.0\pm6.5)$ kJ mol $^{-1}/\theta$$\theta=RT$ ln 10 et $\phi$ est la proportion de recombinaison croisée CH 3 and (CH 3) 2CHNN(CH 3)CH(CH 3) 2.


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

© EDP Sciences 1999

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