Picene, a polycyclic aromatic hydrocarbon (PAH) of environmental relevance has recently been predicted to be carcinogenic, based on quantum mechanical calculation, although in several animal studies no carcinogenicity could be detected.
Picene, a hydrocarbon found in the pitchy residue obtained in the distillation of peat-tar and of petroleum. This is distilled to dryness and the distillate repeatedly recrystallized from cymene It may be synthetically prepared by the action of anhydrous aluminium chloride on a mixture of naphthalene and ethylene dibromide, or by distilling α-dinaphthostilbene. It crystallizes in large colourless plates which possess a blue fluorescence It is soluble in concentrated sulphuric acid with a green colour. Chromic acid in glacial acetic acid solution oxidizes it to picene-quinone, picene-quinone carboxylic acid, and finally to phthalic acid. When heated with hy driodic acid and phosphorus it forms hydrides of composition C22H34 and C22H36.
