Hydrogen peroxide allylic hydroperoxide formation

Risk labels, lATA/ICAO, 751-3 Risk phrases, 621, 748, 749 River water, peroxide determination, 642 RNA, ozone disinfection, 616 ROS see Reactive oxygen species Rose Bengal sensitized photooxidation, 890 Rotational barriers, regioselective allylic hydroperoxide formation, 836, 847-9 Rotational isomers, peroxynitrous add, 8-9 Rotational spectra, ozonides, 721, 722-3 RP-HPLC, hydrogen peroxide determination, 627... 

As in the case of linear peroxidation products, the initiation step of the formation of isoprostanes is the abstraction of a hydrogen atom from unsaturated acids by a radical of initiator. Initiation is followed by the addition of oxygen to allylic radicals and the cyclization of peroxyl radicals into bicyclic endoperoxide radicals, which form hydroperoxides reacting with hydrogen donors. 

Hydrogen atoms in allylic position are favorite sites for hydroperoxidation of chains. So, this mechanism proceeds in the formation of lateral hydroperoxides, and not like for other polymers, in intramolecular peroxides. Rearrangement of chemical structures coming from ozonides are rapidly observed (Scheme 33). 

Photosensitized addition of singlet oxygen to adamantylideneadamantane gives the peroxide (203). The more usual reaction of formation of a hydroperoxide by the ene reaction is not possible because of the absence of allylic hydrogens in the olefin. Typically the peroxide is thermally unstable and gives adamantanone with chemiluminescent emission. Synthesis and pyrolysis of 1,3-diadamantylallene (204) are described. 

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