Mode of Formation of 3,4-Benzopyrene at High Temperatures

3,4-BENZOPYRENE (III) and other polycyclic aromatic hydrocarbons have been identified in coal tar, in soot, in the atmospheric dust of cities, in the exhausts of petrol and Diesel engines, in shale oil, in carbon black, in processed rubber, in coffee soots, in human hair wax, in smoked food, in snuff, in tobacco, and in cigarette and tobacco smoke 1 . As 3,4-benzopyrene is a potent cancer-producing hydrocarbon, its mode of formation is clearly of importance. In 1958 2 it was suggested that 3,4-benzopyrene is formed by high-temperature reactions (incomplete combustion and the like) from simpler hydrocarbons, and that a C 6 –C 4 compound (such as butylbenzene or tetralin) may be the critical intermediate. Two such molecules would be expected to give (II) which would.suffer ready cyclo dehydrogenation to 3,4-benzopyrene