An Effective and Reusable Hyperbranched Polymer Immobilized Rhodium Catalyst for the Hydroformylation of Olefins

Hydroformylation remains the most applied industrial process to produce aldehydes. Much research has been devoted to developing new catalyst systems since aldehydes are highly desired. Supported metal catalyst complexes have drawn renewed attention due to an increased interest in benign and environmental processes. In this paper, NiXantphos has been immobilized on hyperbranched poly(arylene oxindole) supports, different in linker, via a one-step postfunctionalization. Two heterogeneous hyperbranched poly(arylene oxindole) supported NiXantphos ligands were evaluated in the microwave-assisted rhodium-catalyzed hydroformylation of olefins. After selection of the best reaction conditions, a variety of functionalized olefins were successfully converted into the desired linear aldehydes working under milder conditions compared to known processes, in terms of syngas pressure (4.8 bar), temperature (75 degrees C), and reaction times (20 min). The increased activity might emanate from a positive dendritic effect unique to the dendritic nature of the support. Furthermore, the catalyst system was successfully recovered and reused without a decrease in activity or regioselectivity, thus demonstrating to be a valid alternative to classical homogeneous procedures.