The rate of CO uptake in the reaction of HCo(CO)4 with ethyloxirane, which gives (3-hydroxypentanoyl)cobalt
tetracarbonyl as the major product in an n-octane/methyl isobutyl ketone solvent mixture
at 15-degrees-C, is first order with respect to HCo(CO)4 and ethyloxirane, and independent
of the concentration of Co(CO)4- or CO. The reaction is faster with DCo(CO)4. A preequilibrium
ion pair formation and a subsequent rate-determining internal substitution, followed
by fast CO insertion, accounts for these results.