New palladium(II) complexes with ferrocenyl Schiff bases in the hydrogenation of aromatic ketones

Two new palladium complexes with chelating phosphorus-free ferrocenyl-imine ligands derived from 1,2-diami-nocyclohexane and 1,2-diphenylethylenediamine were investigated in the hydrogenation of aromatic ketones. It was found that these catalysts are active in reactions performed with H2 as well as in transfer hydrogenation using 2-propanol/NaOH as a hydrogen donor. In the hydrogenation of acetophenone (APh), two products could be formed, 1-phenylethanol (PhE) and ethylbenzene (EtB), and the reaction selectivity in the studied system was controlled by the kind of solvent and the amount of free ligand excess. In the hydrogenation of acetophenone derivatives, higher selectivity to 1-arylethanol was achieved under hydrogen transfer conditions than under 10 bars of H2 and some ketones were hydrogenated only using this method.