STABLE SILICA-GRAFTED POLYMER-BOUND BULKY-PHOSPHITE MODIFIED RHODIUM HYDROFORMYLATION CATALYSTS

The present study demonstrates that silica-grafted polymer-bound phosphite modified rhodium complexes can be used in continuous flow reactors. The hydroformylation of styrene was carried out at moderate pressure (p(CO/H-2) = 30 bar) and temperature (T = 100-degrees-C), yielding constant conversions over a period of at least ten days. Leakage of rhodium is prevented totally and no decay in catalyst activity was observed. These positive results were obtained in benzene as a solvent and for a ligand to rhodium ratio of only 4. When toluene was used as solvent, considerable rhodium leaching was observed. This could be attributed to contraction of the grafted polymer coils in this solvent, leading to incomplete coordination of rhodium.