Amphoteric, water-soluble polymer-bound hydrogenation catalysts

The synthesis of a water soluble polymer-bound hydrogenation catalyst that is homogeneous and active in basic aqueous media but insoluble and inactive in weakly acidic media is described. This catalyst is also active in organic solvents. In water, the catalyst can be recovered by acidifying the solution to a pH <5. In aceronitrile, the catalyst can be recovered by solvent (ether) precipitation. Activities of the catalyst are comparable to but in every case slightly lower than those of a structurally similar low molecular weight catalyst. Recovery and reuse of the polymeric catalyst is simpler and more efficient. (C) 1997 Elsevier Science Ltd.