Photosensitized oxidation of pristane in sea water: effect of photochemical reactions on tertiary carbons

In the presence of a photosensitizer (anthraquinone) a surface film of pristane on synthetic sea water was photo-oxidized by sunlight. The photochemical processes are affected not only by the secondary carbons (producing different 2,6,10,14-tetramethylpentadecanones), but also, and more strongly, by the tertiary carbons. This photo-oxidation leads on the one hand to the formation of tertiary alcohols and on the other hand, after α-cleavage reactions, to different fragmentations of the pristane molecule into alkanes and ketones. These very important results provide new information that must be taken into account when considering the degradation of branched alkanes in a marine environment.