The Preparation and Selectivity of a Polymer-Attached Rhodium(l) Olefin Hydrogenation Catalyst

Abstract

A homogeneous hydrogenation catalyst [tris(triphenyl-phosphine)chlororhodium(I)] was attached to a polystyrene support by phosphine links. The attached catalysts were easily removed from the reaction mixture and could be used many times with little loss of activity. A study of the relative rate of reduction vs. olefin size indicated that the attached catalysts showed a selectivity for smaller molecules. A model based on the random sizes of the pores in the polymer was developed. The effective pore size was found to be only 5-10% that of the size measured by other techniques. Suspension of the polymer attached catalyst in polar solvents allowed the reduction of non-polar hydrocarbons in the presence of polar olefins.