Asymmetric Hydrogenations of Acetophenone and Its Derivatives over Ir/HAP Modified by (1S,2S)-DPEN

A novel catalyst was prepared for the first time by supporting iridium on porous hydroxyapatite (Ir/HAP). The catalyst was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) equipped with an energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller (BET) surface area analysis. In the presence of (1S,2S)-1,2-diphenyl-1,2-ethylenediamine ((1S,2S)-DPEN), the catalytic properties of the catalyst were investigated by the asymmetric hydrogenation of aromatic ketones. Under optimum reaction conditions of temperature T=303 K, pressure p=3.0 MPa, and reaction time t=3 h, the conversion of aromatic alcohols that were produced from the hydrogenation of acetophenone and its derivatives reached 94.7%. The enantiomeric excess (ee) value for the 2'-(trifluoromethyl) phenethyl alcohol was 81.5%. Without using other ligands as stabilizers, the enantiomeric excess value was found to be higher than that reported in literature. As a catalyst carrier, hydroxyapatite is superior to SiO2 and other inorganic carriers. The catalyst is reusable with no sign of Ir leaching.