Selective hydroformylation of 1-hexene to branched aldehydes using rhodium complex of modified bulky phosphine and phosphite ligands

The selective hydroformylation of 1-hexene to branched aldehydes was investigated using rhodium complex of tri-1-naphthylphosphine PNp3 and tri-1-naphthylphosphite P(ONp)(3). The PNp3 and P(ONp)(3) ligands having more steric nature than PPh3 enhanced the formation of branched aldehydes at 110 degrees C and 4.0 MPa syngas pressure. The branched aldehyde selectivity increased remarkably (82%) by adding P(ONp)(3) as auxiliary ligand in Rh/PNp3 catalyzed hydroformylation of 1-hexene. The high selectivity for the branched aldehydes is due to rapid alkene isomerization producing internal alkenes followed by hydroformylation to yield branched aldehydes. (C) 2010 Elsevier B.V. All rights reserved.