Thermal decomposition and autoxidation of cobalt acetylacetonates

Abstract

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.