Polystyrene resin has been widely employed as carriers of transition metals due to its excellent physical and chemical properties. The obtained polystyrene-immobilized transition metal complexes generally exhibit high catalytic activity, enhanced reaction selectivity and good reusability, and thus have been attracting great attention for improving the efficiency of hydrosilylation and hydrogenation reactions in recent years. In addition, modifying polystyrene by coordinating-group-containing compounds could significantly enhance the coordination ability to metal ions. Consequently, the resultant catalysts usually provide better catalytic performance. In view of this, the current review summarizes the novel progress for the synthesis and application of polystyrene-immobilized transition metal complexes as catalysts in hydrosilylation and hydrogenation. The preparation method, catalytic performance and the related mechanism are introduced. Firstly, the amine-, phosphine-, mercapto groups-, and unsaturated hydrocarbon-modified polystyrene immobilized transition metals for catalytic hydrosilylation are described. Secondly, polystyrene immobilized transition metals (including Pt, Pd, Rh, Ru, Au nanoparticles, Cr, etc.) for catalytic hydrogenation are described, with the emphasis on the complexes of Pd and Rh. At last, the development trend of this kind of catalysts is suggested. Contents
1 Introduction
2 Application of polystyrene immobilized transition metals as catalysts for hydrosilylation
2.1 Polystyrene immobilized transition metal catalysts modified by amine
2.2 Polystyrene immobilized transition metal catalysts modified by phosphine
2.3 Polystyrene immobilized transition metal catalysts modified by mercapto groups
2.4 Polystyrene immobilized transition metal catalysts modified by unsaturated hydrocarbon
2.5 Others
3 Application of polystyrene immobilized transition metals as catalysts for hydrogenation
3.1 Polystyrene-Pt catalysts
3.2 Polystyrene-Pd catalysts
3.3 Polystyrene-Rh catalysts
3.4 Polystyrene-Ru catalysts
3.5 Polystyrene-Au catalysts
3.6 Polystyrene-Cr catalysts
3.7 Polystyrene-Au/Pd catalysts
4 Conclusion and outlook