Xantphos family

Another important highly selective and stable hydroformylation sol gel catalyst is made of silica-supported rhodium covalently bound to supported Xantphos family of ligands.36 By incorporating monoliths of the sol-gel doped material into the paddles of an autoclave stirrer, the catalyst (Rotacat) can be used in a continuous liquid flow process. A single sample of this catalyst was used for a variety of different hydroformylation reactions under widely varying conditions over a period of more than a year, still retaining its selective activity. 

By incorporation of both phosphine groups in a rigid scaffold, less conformational freedom results, which may be beneficial to achieve -regioselective hydroformylation. One of the most prominent examples in this regard is represented by the Xantphos family. Xantphos is the generic name of a class... 

Figure 10. Xantphos diphosphine family. Natural bite angles indicated.

A family of wide bite angle diphosphine ligands based upon xantphos (8) has been developed and tested in rhodium catalysed hydroformylation. van Leeuwen and co-workers conducted HP IR measurements on a range of Rh/thixantphos... 

---