ON THE MECHANISM OF THE Co2(CO)8 CATALYZED HYDROFORMYLATION OF OLEFINS IN HYDROCARBON SOLVENTS. A HIGH PRESSURE UV AND IR STUDY

Article abstract of DOI:10.1016/0022-328X(84)80075-3

High pressure IR and UV spectroscopic experiments confirm the Heck and Breslow mechanism of the hydroformylation of 1-octene and cyclohexene with Co2(CO)8 as the starting catalyst.The major repeating unit is HCo(CO)4, which is formed via the reaction of acylcobalt tetracarbonyl with H2.The rates are 6.7 x 10^-4 mol l^-1 min^-1 and 8.8 x 10^-5 mol l^-1 min^-1 for 1-octene and cyclohexene, respectively at 80 deg C and 95 bar CO/H2 = 1 in methylcyclohexane.The alternative reaction of RCOCo(CO)4 with HCo(CO)4 is only a minor pathway, with rates of 1.8 x 10^-5 mol l^-1 min^-1 and 1.1 x 10^-5 mol l^-1 min^-1 for 1-octene and cyclohexene, respectively.It represents an exit from the catalytic cycle.The activation of the catalyst precursor Co2(CO)8 is the slowest step of the reaction.