DIRECT SYNTHESIS OF ALCOHOLS FROM N-OLEFINS AND SYNGAS IN THE LIQUID-PHASE CATALYZED BY RHODIUM SUPPORTED ON CROSS-LINKED ACRYLIC RESINS

The [Rh(acac)(CO)2] complex undergoes facile coordination on macromolecular isocyanides to quantitatively give the macromolecular complex [(P℘NC)2Rh(acac)(CO)]. This material is the precursor of a heterogeneous, reusable catalyst able to promote the hydroformylation of 1-hexene in toluene at 120°C and 12 MPa, with subsequent quantitative hydrogenation of the aldehydes formed. No olefin hydrogenation is observed, and only minor amounts of internal hexenes are detected in the final reaction mixtures. The ratio of normal to branched products is usually close to one. Catalyst activation is accompanied by the hydrogenation of the isocyano ligand and by the reduction of Rh(I) to finely and evenly dispersed metal aggregates, with dimensions ranging from 1.6 to 7.2 nm (X-ray microprobe and TEM). It is likely that the hydroformylation reaction is catalyzed in the liquid phase by soluble rhodium hydridocarbonyl species, which form during every catalytic run. The selective reduction of the aldehydes is probably catalyzed by the polymer-supported rhodium crystallites, i.e., under real heterogeneous conditions.