Organic Tetroxides and Mechanism of Peroxy Radical Recombination

The chemical properties of organic tetroxides, that is, compounds of a general formula ROOOOR (R = H or organic radical) are discussed. The following tetroxides are considered: hydrogen tetroxide HOOOOH, dialkyl tetroxides ROOOOR, hydrotetroxides ROOOOH, and five-membered cyclic tetroxides—tetroxolanes. Hydrogen tetroxide is formed via self-reaction of HOO· radicals on singlet PES; hydroperoxy radical interaction plays an important role in the chemistry of atmosphere. The formation and subsequent decay of tetroxides are discussed in detail. Similar self-reaction of alkylperoxy radicals leads to organic tetroxides. Its irreversible transformation occurs in two directions depending on the tetroxide structure: the facile homolysis of ROOOOR bond or the induced by αCH bond radical decomposition of tetroxide into hydroperoxy, alkoxy radicals, and carbonyl compound. The latter interaction is the key step in the new mechanism of peroxy radical recombination suggested on the base of extensive analysis of available literature. Hydrotetroxides show properties similar to both HOOOOH and dialkyl tetroxides. A possibility of tetroxolane generation in the reaction of ozone with carbonyl compounds is discussed. Keywords: free radicals; organic tetroxides; oxidation; ozone; reaction mechanism; singlet oxygen; tetroxolanes; thermal decomposition