Singlet oxygen Russell mechanism

Termination of the autoxidation chain process occurs as peroxyl radicals couple to yield non-radical products. This reaction takes place through an unstable tetroxide intermediate. Primary and secondary tetroxides decompose rapidly by the Russell termination mechanism to yield three non-radical products via a six-membered cyclic transition state (Fig. 95). The decomposition yields the corresponding alcohol, carbonyl compound, and molecular oxygen (often in the higher energy singlet oxygen state) three... 

Peroxy radicals can react by yet other competing routes. For example, evidence for lipid peroxy radical combination through a tetraoxide has been reported recently (8). Such tetraoxides could generate singlet oxygen and nonradical products by the Russell mechanism (9) as shown in Reaction D. 

The termination step occurs by the Russell mechanism [1] via the unstable tetraoxide (5). The products are a ketone, oxygen and an alcohol as shown. The conservation of spin in this assumed concerted reaction, as previously discussed, leads, to formation of the ketone in the triplet excited state. Although singlet oxygen may be found in low yield, the carbonyl excited state certainly predominates. 

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