Catalytic hydrogenation of alkenes has been a great importance in both homogenous and heterogeneous catalysis. The use of nanomaterials as well-defined catalysts has been attracting more interest especially for developing catalysts with high activity and superior selectivity. Metal nanoparticles (MNPs) in heterogeneous system have been the most studied catalytic

nanomaterials. However, the catalytic selectivity of various supported metal nanoparticles that are reported in literatures have been somewhat unsatisfactory for practical applications compared to that of homogeneous organometallic catalysts. Colloidal metal nanoparticle catalysts can be considered as semi-heterogeneous because of their homogeneous kinetic traits and heterogeneous

surface properties. These characteristics of colloidal nanoparticles make them an excellent candidate for highly selective transformations of organic substrates.

This thesis presents the preparation and catalysis of octanethiolate-capped palladium nanoparticles (C8 PdNP) and phenylethanethiolate-capped palladium nanoparticles (PhC2 PdNP) for chemoselective catalytic hydrogenation reactions of alkene groups in the presence of other reducible functionalities. Kinetic studies are performed and analyzed by ¹H NMR spectroscopy

to obtain clearer understandings of the catalytic activity. The noncovalent interactions between surface phenyl ligands and aromatic substrates are found to hinder the hydrogenation activity of PhC2 PdNP. In comparison, the C8 PdNP is discovered to be highly active and selective for hydrogenating alkene and alkyne groups without the reduction of other reactive functional

groups such as nitro, halo, carbonyls, etc. under the mild reaction condition (room temperature and atmospheric pressure).