Diethyl ketone triperoxide: thermal decomposition reaction in chlorobenzene solution and its application as initiator of polymerization

Abstract

AbstractThe kinetics of the thermal decomposition reaction of diethyl ketone triperoxide (3,3,6,6,9,9‐hexaethyl‐1,2,4,5,7,8‐hexaoxacyclononane, DEKT) in chlorobenzene solution were studied in the temperature range 99.0–148.0°C and at initial concentrations of (1.65–4.97) × 10−2 M. The thermolysis of DEKT follows a first‐order kinetic law up to at least ca 80% triperoxide conversion. The activation parameter values for the initial O—O bond rupture in chlorobenzene (ΔH‡=134.6±1.7 kJ mol−1; ΔS‡ = 4.2 ± 3.8 J mol−1 K−1) and the reaction products observed support a stepwise reaction mechanism which includes as a first step the unimolecular homolytic cleavage of one peroxidic bond of the DEKT molecule giving rise to a biradical as intermediate. Additionally, the results obtained were compared with those obtained in toluene, toluene–styrene (50%, v/v) and chlorobenzene–styrene (50%, v/v) solution, showing that the decomposition reaction is strongly solvent dependant. Further, the biradical intermediate obtained in all cases was used to initiate styrene polymerization. It was demonstrated that DEKT can effectively act as initiator in styrene polymerization and its performance is similar to that presented by a multifunctional initiator giving rise to high molecular weight polystyrene at a high reaction rate. Copyright © 2004 John Wiley & Sons, Ltd.