Sequential Multistep Reactions Catalyzed by Polymer-Bound Homogeneous Ni, Rh, and Ru Catalysts

Abstract

Homogeneous catalytic reactions employing transition metal complexes have become increasingly important in recent years, as exemplified by the production of acetaldehyde from ethylene and air by the Wacker process.1 In many cases, however, homogeneous catalysts are very expensive and must be separated from the products by costly separation steps. These two factors have in part, limited the scope of practical application of homogeneously catalyzed reactions. One way to achieve easy recovery of the catalyst from product, while simplifying the purification of products, is to anchor the catalyst to immobile supports such as silica, ceramic, or polymeric materials. Such studies of “heterogenized” homogeneous catalysts are beginning to receive increased attention.2 Industrial groups at Mobile,3 ESSO,4 Monsato,5 and ICI6 as well as the academic groups of Bailer,7 Grubbs,8,9 Pittman,10,11,12 and Collman13 have anchored several organotransition metal complexes to substrates, via phosphine and nitrogen complexation, and studied their catalytic reactivity.