Dehydrogenation of 4,5-Disubstitued 9,10-Dihydrophenanthrenes

Abstract

Dehydrogenation rates of four 4,5-disubstituted 9,l0-dihydrophenanthrenes to the corresponding phenanthrenes by 10% palladium on charcoal for the substituents, H, OCH₃, F and CH₃, appear to be related to the size of the substituents.

The preparation of three new phenanthrenes, viz. 4,5-dichlorophenanthrene, 4,5-difluoro-phenanthrene and 4,5-bis( trifluoromethyl ) phenanthrene, is described.

Treatment of mesitylene with either 10% palladium on charcoal at reflux or 2,3-dichloro-5,6- dicyano-1,4-benzoquinone gives an appreciable yield of mesityl(3',5'-xylyl)methane.