The formation of aromatic hydrocarbons at high temperatures. XX. The pyrolysis of [1-¹⁴C]naphthalene

Abstract

The pyrolysis of [1-¹⁴C]naphthalene at 700° has given a tar from which 1,1'-, 1,2'-, 2,2'-binaphthyls, and 10,11-, 11,12-benzofluoranthenes were isolated in sufficient quantity and purity for radiochemical analysis. All were found to have activity corresponding, within experimental error, to two labelled carbon atoms. It is concluded that carbon-hydrogen fission gives naphthyl radicals, which react with naphthalene to yield binaphthyls, and that cyclodehydrogenation of the binaphthyls leads to the benzofluoranthenes. A small amount of perylene was also identified; this was probably formed in the same way. Some 3,4-benzopyrene was detected; it is suggested that some hydrogenation of the naphthalene occurs, and that the 3,4-benzopyrene is formed following cleavage of a saturated carbon-carbon bond in this hydrocarbon.