Rhodium Diphosphine Hydroformylation

J. J. Carbo, F. Maseras, and C. Bo, Rhodium Diphosphine Hydroformylation, in Computational Modeling of Homogeneous Catalysis, F. Maseras and A. Lledos, Eds., Kluwer Academic Dordrecht, The Netherlands, 2002, pp. 161-187. 

It is interesting to note that using the sol-gel procedure (I) the pre-formation of the rhodium diphosphine complex suppressed the formation of ligand free rhodium-cations on the silica surface. This approach gave rise to a well-defined, very selective hydroformylation catalyst. All immobilised catalysts were 10 to 40 times slower than the homogeneous catalyst under the same conditions, the sol-gel procedure yielding the fastest catalyst of this series. 

Electronic effects. To study the nature of the electronic effect in the rhodium diphosphine catalysed hydroformylation, a series of thixantphos 18 ligands with varying basicity was synthesized 25-30 (Figure 8.11). In this series of ligands, steric differences are minimal so purely electronic effects could be investigated. 

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... 

Figure 1.13 Generation of rhodium-based supramolecularcatalysts by assembly of pyridine/hydroxypyridine pairs (a) Self-assembly modes of pyridine-based phosphines, (b) Alkene hydroformylation with supramolecular rhodium-diphosphine catalysts (c) CAChe minimized 3D structure ofthe rhodium-diphosphine complex (other ligands from the metal omitted for clarity).

To study the effect of the assembly of monophosphines 33-38 into diphosphines 39-44 with zinc or titanium on the catalytic properties the rhodium-catalyzed hydroformylation of 1-octene was studied. Optimal phosphine to rhodium ratios (at 1 mM of Rh) are different for mono and diphosphines and average convenient... 

Escudero-Adan, E.C., Freixa, Z. and van Leeuwen. P.W.N.M. (2007) Catalysis by design Wide-bite-angle diphosphines by assembly of ditopic ligands for selective rhodium-catalyzed hydroformylation. Angeiv. Chem., Int. Ed., 46. 7247—4750. 

Kamer. P.C.J.. van Leeuwen, P.W.N.M., Goubitz, K. and Fraanje, J. (1995) New diphosphine ligands based on heterocychc aromatics inducing very high regioselectivity in rhodium-catalyzed hydroformylation - Effect of the bite angle. Organometallics, 14, 3081-3089. 

A. L. (2000) Origin of the bite angle effect on rhodium diphosphine catalyzed hydroformylation. Organometallics, 19, 872-883. 

Casey, C.P., Whiteker, G.T., Melville, M.G., Petrovich, L.M., Gavney, J.A., Jr. and Powell, D.R. (1992) Diphosphines with natural bite angles near 120 Deg increase selectivity for n-aldehyde formation in rhodium-catalyzed hydroformylation. J. Am. Chem. Soc.,... 

C. P. Casey, G. T. Whiteker, M. G. Melville, L. M. Petrovich, J. A. Gavney, and D. R. Powell, J. Am. Chem. Soc., 114, 5535 (1992). Diphosphines with Natural Bite Angles near 120° Increase Selectivity for -Aldehyde Formation in Rhodium-Catalyzed Hydroformylation. 

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