Catalyzed Transfer Hydrogenation By 2-Propanol For Highly Selective Pahs Reduction

Catalytic hydrogenation of mono-, di- and trinuclear aromatic compounds has been studied under hydrogen transfer conditions at 150 degrees C and 82 degrees C in 2-PrOH as a hydrogen donor and with Raney (R) nickel as a catalyst. In contrast to conjugated or condensed aromatic rings, isolated ones demonstrated low reactivity in transfer hydrogenation (TH) that can be used to increase the hydrogenation selectivity of the reaction. So, naphthalene and biphenyl are partially hydrogenated into tetralin and cyclohexylbenzene, respectively, with excellent conversion (>= 96 %) and selectivity (>= 98 %) for 5-6 h at 82 degrees C. Increasing the reaction temperature to 150 degrees C results expectedly in the hydrogenation of second aromatic ring, which occurs slowly enough. Only 8 % of decaline and 42 % of dicyclohexyl, correspondingly, were obtained after 5 h at 150 degrees C. At the same time, TH of trinuclear anthracene and phenanthrene at 150 degrees C resulted in the formation of deeper hydrogenated octahydro-anthracenes and -phenanthrenes, respectively.