Hydroformylation of mixture of isomeric octenes to C-9-aldehydes catalyzedby Rh-phosphine oxide complexes

The hydroformylation of mixture of isomeric octenes to C-9-aldehydes has be en studied using rhodium complex catalysts in an autoclave (100 ml). Phosph ine oxide ligands showed high activities in the hydroformylation. The yield of Cg-aldehydes was about 90% by using [Rh(CH3COO)(2)](2)-Ph3PO as the cat alyst at 140 degreesC and 10.5MPa. Triphenyl phosphine ligand was found to be inactive in the synthesis of Cg-aldehydes from mixture of isomeric octen es. Different rhodium precursors ([Rh(CH3COO)(2)](2), Rh-6(CO)(16), and Rh( CO)(PPh3)(acac)) showed similar performance in the Rh-Ph3PO system. The yie ld of C-9-aldehydes was influenced by the reaction conditions. The suitable reaction temperatures were in the range of 120-140 degreesC for the Rh-pho sphine oxide systems. High pressures were favorable for the formation C-6-a ldehydes. The yield of C-9-aldehydes increased with the increase of P/Rh ra tio when the ratio of P/Rh was below 20, while no significant changes were found in the yield of C-9-aldehydes when P/Rh ratio was larger than 20. In situ IR spectroscopy demonstrated the presence of Rh-H bond in the intermed iate species in Rh-Ph3PO catalyzed hydroformylation. (C) 2001 Elsevier Scie nce B.V. All rights reserved.