The Mechanism of the Thermal Decomposition Reaction of Acetone Cyclic Diperoxide in Methyl -Butyl Ether Solution

Abstract

The thermal decomposition reaction of acetone cyclic diperoxide (3,3,6,6-tetramethyl- 1,2,4,5-tetroxane, ACDP) in the temperature range of 130.0 - 166.0 C and an initial concentration range of 0.4 - 3.1 × 10 mol kg has been studied in methyl -butyl ether solution. The thermolysis follows first-order kinetic laws up to at least 60% acetone diperoxide conversion. Under the experimental conditions, the activation parameters of the initial step of the reaction (ΔH= 33.6 ±1.1 kcal mol; ΔS# = - 4.1 ±0.7 cal mol K; DG# = 35.0 ±1.1 kcal mol) and acetone as the only organic product observed support a stepwise reaction mechanism with homolytic rupture of one peroxidic bond of ACDP molecule. Participation of solvent molecules is postulated. A biradical is postulated as an internal intermediate, which further decomposes only their C-0 bond ruptures, yielding a stoichiometric amont of acetone (2 mole per mole of ACDP decomposed) in the ractor. The results are compared with those obtained for the above diperoxide thermolysis in other solvents.

Keywords: Tetroxane, Diperoxide, Thermolysis, Reaction Mechanism