Fine Tuning of Pd0 Nanoparticle Formation on Hydroxyapatite and Its Application for Regioselective Quinoline Hydrogenation

Abstract Fine control of the formation of Pd0 nanoparticles with diameters between 1 and 1.5 nm on hydroxyapatite (HAP) was achieved by adjusting the temperature at which the PdII species on the HAP surface (PdIIHAP) was reduced in the presence of 1 atm of molecular hydrogen. The HAP-supported Pd0 nanoparticles (Pd0HAP) having an average diameter of 1.5 nm exhibited significantly high catalytic activity for the regioselective hydrogenation of quinolines to the corresponding 1,2,3,4-tetrahydroquinolines under mild reaction conditions. Moreover, the Pd0HAP catalyst was reusable without appreciable loss of its high catalytic activity or selectivity.