Kinetics of the thermal decomposition of substituted cyclic organic peroxides in toluene solution:: Substituent effects on the reaction rates and the activation parameters of the unimolecular reactions

Thermal decomposition reactions of substituted cyclic organic di- and triperoxides have been carried out in toluene solution in order to investigate substituent effects on homolytic scission of the O-O bond in those compounds. A comparative analysis of the reactivities at 145 degreesC and the activation parameters for unimolecular reactions of molecules of this type were interpreted in terms of substituent effects and ring size. An isokinetic relationship was established to validate the existence of a genuine substituent effect for the unimolecular homolysis reaction of the substances considered. Cyclic organic peroxides of very high reactivity and sterically hindered deviated from correlation's. It appears to be possible to determine whether a peroxy group is part of a six or nine membered ring on the basis of the activation parameters values.