Hydroformylation of 1,5‐Hexadiene Catalyzed by Rhodium Complexes in Supercritical Carbon Dioxide and in Toluene: Effects of Fluorinated Phosphane Ligands and Reaction Conditions
Rhodium-catalyzed hydroformylation of 1,5-hexadiene to dialdehydes was investigated in compressed CO2 and in toluene using different fluorinated phosphane compounds as ligands at a temperature of 60 °C. Product yields depend greatly on the ligand used and, of the ligands examined, tris[3,5-bis(trifluoromethyl)phenyl]phosphane is the most effective for the production of dialdehydes both in supercritical CO2 (scCO2) and in toluene. The total yield of the dialdehydes passes through a minimum at about 9 MPa as the CO2 pressure is increased and increases appreciably as the H2 pressure in scCO2 increases. The effect of the syngas (H2/CO) and H2 pressures on the reaction in scCO2 is different from that in toluene. It has been suggested that scCO2 promotes the hydroformylation reaction. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)