HYDROGENATION OF CONJUGATED DOUBLE BONDS OF trans-1,3-PENTADIENE CATALYZED BY Rh2Cl2(CO)4 IN SOLUTION AND ANCHORED TO γ-Al2O3

Article abstract of DOI:10.1016/S0022-328X(00)84621-5

Hydrogenation under mild conditions (1 atm H2 and 60-80 deg C) of trans-1,3-pentadiene catalysed by Rh2Cl2(CO)4 in toluene solution and by Rh2Cl2(CO)4 anchored on γ-Al2O3 has been investigated.Both the homogeneous and the heterogenised catalysts display a good specificity towards hydrogenation of the external double bond of the conjugated diene system.A slow inactivation of the supported catalyst occurs during the hydrogenation, but it cannot be attributed to reaction of the catalyst with the substrate since it occurs also when Rh2Cl2(CO)4 is heated at 70 deg C under 1 atm H2.Partial substitution of CO ligands of Rh2Cl2(CO)4 by triphenylphosphine leads to a reduction of the activity of the homogeneous catalyst but does not alter its specificity.Triphenylphosphine can either increase or decrease the activity of the heterogenised catalyst depending on whether its introduction into the system precedes or follows the anchorage of Rh2Cl2(CO)4 on Al2O3.