| abstract |
Certain triarylphosphine rhodium carbonyl hydride complexes (Ar3P)3Rh(CO)H (I) and (Ar3P)2Rh(CO)2H (II) are selective and stable catalysts of high temperature olefin hydroformylation. The critical factors are the maintenance of a sufficient CO partial pressure, above 25 psia, and the provision of a high excess of triarylphosphine ligand concentration, at a minimum of 1 mole per kg. To provide a high ratio of n- to i-aldehyde products of 1-olefin hydroformylation, the concentration of the tris-phosphine complex (I) is maximized. In a continuous product flashoff operation of the present process, the major high boiling solvent components are the excess phosphine ligands and monoalcohol and monoester by-products. A combined isomerization-hydroformylation process is also disclosed for the selective conversion of internal linear olefins to terminal n-aldehydes. In this process, the concentration of the bis-phosphine complex (II) is minimized. In contrast, the concentration of the tris-phosphine complex is maximized in a process effectively converting linear internal olefins to the corresponding branched i-aldehydes. |