Studies on the kinetics of decomposition of diacyl peroxides: III. Kinetics and mechanism of decomposition of 3, 5, 5-trimethylhexanoyl peroxide in benzene

Abstract

The kinetics of decomposition of 3,5,5-trimethylhexanoyl peroxide (1) in benzene at 30, 40, and 50°C respectively have been studied and the cage effect, main products and the products obtained in scavenging experiment with galvinoxyl determined and characterized. The results show that the decomposition of 1, with initial concentration between 0.04 to 0.43 mol. L−1, followed first plus three halves order kinetics with cage effect of 0.6, and the mechanism of decomposition is basically the same as previously proposed for lauroyl peroxide (2).4 In comparison with 2, the decomposition of 1 at the same temperature showed a faster rate for spontaneous decomposition, a larger cage effect and lesser induced decomposition, which is attributed to the branching in molecule of 1, especially to the presence of β-methyl group, which caused a larger entropy increase between the peroxide molecule and the transition state for decomposition.