Selective transfer dehydrogenation of aromatic alcohols on supported palladium

Transfer dehydrogenation of various alcohols has been investigated over het erogeneous palladium catalysts using olefins as hydrogen acceptors. Pd/Al2O 3 together with cyclohexene is the most active and selective system, afford ing a simple and convenient laboratory synthesis of aromatic ketones in ref luxing cyclohexane. Hydrogenolysis-type side reactions can be suppressed by minute amounts of a tertiary amine (selective poisoning of Pd). Aliphatic and cycloaliphatic alcohols are barely reactive under these conditions, a d ifference which offers the possibility of the selective transformation of a romatic alcohols even in the presence of an aliphatic OH group.