A comparative study of triphenylamine,triphenylphosphine, triphenylarsine,triphenylantimony and triphenylbismuth as ligands in the rhodium-catal yzed hydroformylation of 1-dodecene

Triphenylarmine, triphenylphosphine, triphenylarsine, triphenylantimony and triphenylbismuth were evaluated on the basis of olefin to aldehyde conversion, and also on the basis of the normal/iso (n / i) product ratio, as ligands in the rhodium-catalyzed hydroformylation of 1-dodecene. Two series of reactions were conducted which differed only in total reaction time (120 minutes vs 135 minutes) and in the ligand/rhodium ratio (60:1 vs 300:1). Both reactions series employed 35 grams of 1-dodecene, a 176 ppm rhodium charge, 100 psig of 1:1 H₂ / CO, and a reaction temperature of 90° C. In the 60:1 vs 330:1 reaction series, triphenylamine gave olefin conversions and n / i ratios of 2.0%, 2.0 vs 5.8%, 1.8; triphenylphosphine gave 95%, 4.4 vs 86.9%, 8.7; triphenylarsine gave 58%, 3.1 vs 85.8%, 3.5; triphenylantimony gave 13.0%, 6.1 vs 3.5%, 9.1 respectively. Triphenylbismuth failed to promote hydroformylation in both reaction series. These data demonstrate that regiospecificity, as measured by the n / i product ratio, varies inversely to increased ligand basicity.