Kinetics and mechanism of the thermal decomposition reaction of acetone cyclic diperoxide in methyl tert‐butyl ether solution

Abstract

AbstractThe 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 initial concentrations range of 0.4–3.1 × 10−2 mol kg−1 has been studied in methyl t‐butyl ether solution. The thermolysis follows first‐order kinetic laws up to at least ca 60% ACDP conversion. Under the experimental conditions, the activation parameters of the initial step of the reaction (ΔH# = 33.6 ± 1.1 kcal mol−1; ΔS# = −4.1 ± 0.7 cal mol−1 K−1; ΔG# = 35.0 ± 1.1 kcal mol−1) and acetone, as the only organic product, support a stepwise reaction mechanism with the homolytic rupture of one of its peroxidic bond. Also, participation of solvent molecules in the reaction is postulated given an intermediate diradical, which further decomposes by CO bond ruptures, yielding a stoichiometric amount of acetone (2 mol per mole of ACDP decomposed). The results are compared with those obtained for the above diperoxide thermolysis in other solvents. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 302–307, 2004