Liquid‐phase oxidation of isobutane—a reanalysis of the data

Data on the liquid‐phase oxidation of isobutane at 50 and 100°C have been reexamined, using a modified mechanism to take into account the termination by isobutylperoxy radicals. Algebraic expressions are derived from steady‐state methods. Using Arrhenius parameters fitted by transition‐state A factors and activation energies derived from observed “best” rate constants, new sets of parameters are derived for the rate constants for propagation by t BuO 2 + t BuH → t ‐BuO 2 H + t Bu ⋅ :\documentclass{article}\pagestyle{empty}\begin{document}$$ k_4 \, = \,1 \times 10^{8 - 14.5/{\rm \theta }} {\rm M}^{{\rm - 1}} \sec ^{ - 1} $$\end{document}where θ = 2.303 RT in kcal/mol. This, together with new values for the termination parameters and rates of i ‐butyl production by k 4B , is shown to give good agreement with the published data. An important reaction:\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm R}'{\rm O}_{2}^{.} + {\rm RO}_{2} {\rm H}\mathop{{\buildrel{-\!\!\longrightarrow}\over{\longleftarrow}}}\limits^{{\rm 12}}{\rm R'O}_{\rm 2} {\rm H} + {\rm RO}_{2}^{.} $$\end{document}is shown to quench the possible contributions to termination of adventitious radicals such as CH 3 O ⋅ 2 .