Polymer-anchored platinum complexes as catalysts for the Baeyer-Villiger oxidation of ketones: preparation and catalytic properties

The preparation of a variety of catalysts obtained by ion exchange of the complex [(dppb)Pt(mu - OH)](2)(2+) with sulfonated styrene-divinylbenzene copolymers is reported. Copolymers used are commercial ion exchange resins containing either 4% or 20% DVB and they were loaded with either Li+ or NBu4+ prior to exchange with the Pt complex. Metal loading in the heterogenized catalysts is in the range 2-8% by weight. Their catalytic properties in the Baeyer-Villiger oxidation of methylcyclohexanone with hydrogen peroxide appear to be best in terms of activity and productivity either in neat ketone or in EtOH as the solvent. The use of commercial resins with high exchange capacity prevents the use of DCE as the solvent, i.e., the optimum conditions for the homogeneous system, thereby leading to activities and productivities that are generally lower than their homogeneous counterpart. A discussion on the influence of the philicity properties of the support with respect to the performance of the catalyst is reported. (C) 2000 Elsevier Science B.V. All rights reserved.