Kinetics and mechanism of the thermal decomposition reaction of acetone cyclic diperoxide in the gas phase

The kinetics of the thermal decomposition reaction of gaseous 3,3,6,6‐tetramethyl‐1,2,4,5‐tetroxane (ACDP) in the presence of n‐octane was studied in the 403.2–523.2 K temperature range. This reaction yields acetone as the organic product. Under optimum conditions, first‐order kinetics were observed, included when the S/V ratio of the Pyrex reaction vessel was increased by a nearly six‐fold factor. In the range 443.2–488.2 K the temperature dependence of the rate constants for the unimolecular reaction in conditioned vessels is given by In k1/(s−1) = (31.8 ± 2.5) − [(39.0 ± 2.5)/RT]. The value of the energy of activation in kcal/mol correspond to one OO bond homolysis of the ACDP molecule in a stepwise biradical initiated decomposition mechanism. At the lower reaction temperatures as well in preliminary experiments participation of a surface catalyzed ACDP decomposition process could be detected.