Thermal decomposition and autoxidation of cobalt acetylacetonates

The thermal decomposition and oxidation of Co(acac)3 and Co(acac)2 have been investigated. It was established that in the absence of oxygen between 100 and 130 °C Co(acac)3 was reduced to Co(acac)2, while Co(acac)2 did not undergo decomposition under similar conditions. The corresponding rate constants and activation energies were determined. Both Co(acac)3 and Co(acac)2 are oxidized stepwise to Co(OAc)2,xH2O in the presence of oxygen. The intermediate of the oxidation process is presumably Co(acac)(OAc)2. It was experimentally proved that RO2·-type radicals generated in the system can interact with both acetylacetonates. The rate constant of the interaction between peroxy-radicals and Co(acac)3 has been calculated. Mechanisms for both the decomposition and oxidation reactions have been suggested.