Kinetics and reaction mechanism for the thermal decomposition of some even chain lead(II) carboxylates

The kinetics of the thermal decomposition of lead(II) dodecanoate, tetradecanoate and octadecanoate have been studied thermogravimetrically in the temperature range 298–1073 K by the modified method of Freeman and Carroll. The thermogravimetric curves show that while the octadecanoate decomposes in one single step to lead oxide, the dodecanoate and tetradecanoate decompose in two stages to lead oxide. The kinetic results show all the reactions, except the second step breakdown of dodecanoate (which is nearly unity), to be of zero order. Activation energy values are presented for the desorption of carbon dioxide and the diffusion controlled rate of formation of a degradative intermediate identified as a ketone. Tentative mechanisms are advanced to explain the degradative route of these compounds.