Abstract
The hydroformylation of olefins over rhodium catalysts, with phosphorus ligands added in situ, has been studied under atmospheric pressure. In the case of the Rh~4~(CO)~12~ cluster, the phosphine‐modified catalyst exhibits very high activity, but there is a decay of catalyst activity with time. The deactivation mechanism of this catalyst has been discussed. In the case of rhodium complexes, Rh(LL′)(CO)~2~, containing chelate ligands with oxygen and nitrogen as coordinate atoms, the phosphine‐modified catalysts exhibit fairly active activity and very good stability. All these catalysts afford almost 100% chemoselectivity to aldehydes. The regioselectivity is strongly dependent on the nature of the substrate used. The choice of a suitable phosphorus ligand for the catalytic hydrofor‐mylation is dependent on the nature of the rhodium complex used. The effect of phosphorus ligands on the hydroformylation of olefins over rhodium catalysts under normal pressure displays some special features in comparison with that performed under a higher pressure.