Biphasic hydrogenation of olefins by functionalized ionic liquid-stabilized palladium nanoparticles

Palladium nanoparticles in the size range of 5-6 nm were prepared conveniently by reducing palladium(II) with atmospheric pressure hydrogen and stabilized by 2,2'-dipyridylamine-functionalized imidazolium cations according to our approach. The efficient catalytic conversion of cyclohexene into cyclohexane by the functionalized ionic liquid-stabilized palladium nanoparticles has been performed under very mild hydrogen pressure (0.1 MPa) and at 35 degrees C. It was found that the concentration of palladium and the reaction temperature considerably affected the size and degree of aggregation of Pd nanoparticles in ionic liquid, which further changed the performance of the catalyst activity. The synthesized nanocatalysts can be recycled at least five times without any loss of the activity. Finally, the scope of substrates was also investigated. The excellent catalytic activity of the present system can be attributed to good stabilization and high dispersion of palladium nanoparticles.