Photochemical Hydroformylation

UV irradiation favors the hydroformylation of alkenes in the presence of some cobalt or rhodium catalysts. For example, propene can be hydroformylated to butyraldehyde with CO/H 2 (1:1), 85 bar at 85 °C on Co(OAc) 2 /P( n Bu) 3 ‐catalysis in methanol; the selectivity is ⩾99%. Under these conditions the reaction proceeds thermally. A high stereoselectivity ( ≈ 90%) with respect to the linear chain products is also found photochemically in the case of 1‐octene.