Molten Salt Catalyzed Transfer Hydrogenation of Polycyclic Aromatic Hydrocarbons. Selective Hydrogenation of Anthracene and Naphthacene by Tetralin in Molten Antimony Trichloride

Article abstract of DOI:10.1021/jo00343a001

Anthracene and naphthacene are selectively hydrogenated by tetralin to 9,10-dihydroanthracene and 5,12-dihydronaphthacene, respectively, in a reaction that is catalyzed by molten SbCl3 at 80 deg C.In situ 1H NMR studies indicate that under similar conditions, phenanthrene and pyrene do not react, while perylene is partially oxidized to a persistent radical cation.For the tetralin transfer hydrogenation of anthracene and naphthacene, product analysis shows that no naphthalene is formed, but that the dehydrogenated tetralin reacts with itself and unreacted arene to givealkylated products.These transfer hydrogenation reactions can best be explained by a redox initiated ionic mechanism involving the arene radical cation and the 1-tetralyl cation (1,2,3,4-tetrahydro-1-naphthalenylium ion) as key intermediates.