The kinetics of the interaction of peroxy radicals. II. Primary and secondary alkyl peroxy

A chain mechanism is proposed to account for the very rapid termination reactions observed between alkyl peroxy radicals containing α‐C—H bonds which are from 10 4 to 10 6 faster than the termination of tertiary alkyl peroxy radicals. The new mechanism iswith termination by. \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm R}\overline {{\rm CHOO}} $\end{document} is the zwitterion originally postulated by Criegee to account for the chemistry of O 3 ‐olefin addition. Heats of formation are estimated for \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {{\rm CH}_2 {\rm OO,}} {\rm }\overline {{\rm RCHOO}} $\end{document} , and \documentclass{article}\pagestyle{empty}\begin{document}$ ({\rm C}\overline {{\rm H}_3 )_2 {\rm COO}} $\end{document} and it is shown that all steps in the mechanism are exothermic. The second step can account for ( 1 Δ)O 2 which has been observed. k 1 is estimated to be 10 9–2/θ liter/ M sec where θ = 2.303 RT in kcal/mole. The second and third steps constitute a chain termination process where chain length is estimated at from 2 to 10. This mechanism for the first time accounts for minor products such as acid and R OOH found in termination reactions. Trioxide (step 3) is shown to be important below 30°C or in very short time observations (<10 s at 30°C). Solvent effects are also shown to be compatible with the new mechanism.