Hydroperoxide chain scission, quantum yields

To perform the dissociation of the hydrocarbon to alkyl radicals with C—C bond scission, a hydrocarbon molecule should absorb light with the wavelength 270-370 nm. However, alkanes do not absorb light with such wavelength. Therefore, photosensitizers are used for free radical initiation in hydrocarbons. Mercury vapor has been used as a sensitizer for the generation of free radicals in the oxidized hydrocarbon [206-212], Nalbandyan [212-214] was the first to study the photooxidation of methane, ethane, and propane using Hg vapor as photosensitizer. Hydroperoxide was isolated as the product of propane oxidation at room temperature. The quantum yield of hydroperoxide was found to be >2, that is, oxidation occurs with short chains. The following scheme of propane photoxidation was proposed [117] ... 

Determination of the quantum yield of the different processes involved in the photo-oxidation of poly(vinyl chloride) indicates that for each scission of the polymer backbone 11 molecules of HCl are evolved, whilst 3 carbonyl groups, 2 hydroperoxides and 0.4 intermolecular crosslinks appear on the polymer chain [552, 559]. 

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