Hydroformylation of 1-Octene Mediated by the Cobalt Complex [CoH(dchpf)(CO)(2)]

Hydroformylation of 1-octene with the heterodinuclear (Fe, Co) complex [CoH(dchpf)(CO)2] (1) was investigated (dchpf = 1,10-bis(dicyclohexylphosphino)ferrocene). In agreement with this cobalt complex possessing a preformed hydride as well as carbonyl ligands, the preactivated catalyst does not require any induction process or activation treatment to become reactive in hydroformylation. The catalyst activity and (chemo-)selectivity proved to be strongly dependent on the applied reaction conditions. Higher syngas pressures suppress alkene isomerization and favor the hydroformylation reaction. The overall regio-selectivity remains very similar within the investigated reaction space, with the C1-selectivity varying between 48 and 69 %. An increase of the reaction temperature at 40 bars results in a progressive decrease of the C1-selectivity and an increase in the C2- and C3-selectivity due to a higher isomerization activity at elevated temperatures. Furthermore, at high temperatures (170 ^oC) and low syngas pressures (10–20 bar) the main oxygenated products are the alcohols, resulting from reduction of the aldehydes. However, when using a combination of higher syngas pressures and intermediate temperatures, the reaction could be optimized towards the formation of aldehydes. At 140 ^oC and 40 bars syngas pressure quite selective hydroformylation of 1-octene could be achieved, yielding 57 % aldehydes and only 1.3 % over-reduction to the corresponding alcohol.