The Reaction of Cobalt Hydrocarbonyls Substituted by Tertiary Phosphines with an Olefin

The carbonylation reaction of ethyl vinyl ether with various cobalt hydrocarbonyls, HCo(CO)4, HCo(CO)3PR3, HCo(CO)3P(OR)3, and HCo(CO)2[P(OR)3]2 was studied. Almost all of the cobalt hydrocarbonyls react with ethyl vinyl ether to form the branched chain acyl complexes, CH3CH(OC2H5)COCo(CO)4-nLn (L; CO, PR3 and P(OR)3), regardless of the character of the ligands at 0∼25°C, while HCo(CO)2[P(OEt)3]2 does not react even at 65°C. The order of the reactivities is parallel to that of the electron-accepting character of the ligand. The addition of an excess of the ligand retards the reaction. The activation parameters of the reaction of HCo(CO)3PPh3 with ethyl vinyl ether were estimated to be ΔH≠=9.88kcal/mol, ΔS≠=-41.0e.u.