Support and Size Effects of Ruthenium Catalysts with a Chiral Modifier for Asymmetric Hydrogenation of Aromatic Ketones YeLinmin LinHaiqiang ZhouHancheng YuanYouzhu 2010 A series of supported Ru catalysts with achiral modifier triphenylphosphine (TPP) and chiral modifier (1<i>R</i>,2<i>R</i>)-1,2-diphenylethylenediamine [(1<i>R</i>,2<i>R</i>)-DPEN] were employed for the asymmetric hydrogenation of aromatic ketones. The textural and structural properties of the catalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, N<sub>2</sub> physisorption, transmission electron microscopy, CO<sub>2</sub> and NH<sub>3</sub> temperature-programmed desorptions, inductively coupled plasma atomic emission spectrometry, and ultraviolet−visible spectroscopy. Studies revealed that the enantiomeric excess (ee) followed this order according to the oxide supports used: MgO > γ-Al<sub>2</sub>O<sub>3</sub> > CeO<sub>2</sub> ≫ ZnO > SiO<sub>2</sub>, which was correlated with their surface basicity. Moreover, the highest ee value and intrinsic activity for the asymmetric hydrogenation of acetophenone were attained over the catalyst with a mean Ru nanoparticle diameter of 4.4 nm, while those for the asymmetric hydrogenation of 1-acetonaphthone were obtained over a catalyst with 6.2 nm nanoparticle diameter. The catalyst system consisting of Ru/MgO, TPP, and (1<i>R</i>,2<i>R</i>)-DPEN did not show a significant decrease in ee value after several recycles. The results indicate that there is a size matching effect between the Ru particles and the substrates, besides the acid/base influence of the oxide supports on the reaction.