Reaction paths in the titanium dioxide photocatalysed degradation of dodecane and some of its derivatives

The photocatalytic oxidation of dodecane and some of its derivatives (C12H26, ; C10H21CHCH2, ; C12H25SH, ; C12H25OH, ; C12H25NH2, ; C11H23CHO, ) has been studied in air-equilibrated aqueous TiO2 suspensions. The distribution of the intermediate products has been monitored during the degradation. C1–C12 Monocarboxylic acids are formed in all cases, though in a low yield with substrates . With compounds , acids are formed in a higher yield (>45%), initially including a large proportion of dodecanoic acid and are accompanied by significant amounts of aldehydes and alcohols. Relative efficiencies vary over a factor of 300 from to and a lower limit for the quantum yield is 1.18 for the latter compound, suggesting participation of a chain process. The data suggest that alkylperoxyl radicals are formed through initial hydrogen abstraction on the photocatalyst surface and oxygen addition and their reactivity with the starting reagent determines the course of the reaction. Activated substrates such as compounds and , and to a lesser degree , easily transfer a hydrogen from position 1.