ACYLOXYL RADICAL PAIR INTERMEDIATE FOR THE INITIAL-STAGE OF THE THERMAL-DECOMPOSITION OF DIACYL PEROXIDE - A DENSITY-FUNCTIONAL STUDY

To examine the reaction mechanism for the thermal reorganization, or m ore specifically the oxygen scrambling, in diacyl peroxide, we have ca rried out a hybrid density functional study using formyl peroxide as a model compound. The B3LYP calculations suggest that the oxygen scramb ling in diacyl peroxide is most likely to occur via a sigma-acyloxyl r adical pair species: the competitive pathways of the [3,3]- and [1,3]- sigmatropic shifts are highly improbable. Thus, the mechanism for the thermal oxygen scrambling in diacyl peroxide should be completely diff erent from those for the carbon counterparts of diacyl peroxide (the C ope and Claisen rearrangement).