INTRAMOLECULAR HOMOLYTIC DISPLACEMENTS .2. POLAR EFFECTS IN THE HOMOLYTIC INDUCED DECOMPOSITIONS OF ALLYL PEROXIDES

The products of the decomposition of allyl peroxides 1-5, initiated by tert-butyl peracetate, in three solvents-cyclohexane, dimethyl malonate and benzene-were analysed. The formation of epoxides proved the existence of an homolytic induced decomposition of the unsaturated peroxides by a chain process involving a free radical addition to the double bond and an intramolecular homolytic substitution on the peroxide linkage. The balance of the reaction's products indicated a second way of degradation of the peroxides: allylic hydrogen abstraction followed by the breaking of the peroxide bond by beta-elimination. The relative ratios of the products generated by the eliminated alkoxy radicals YO. and of the different epoxides produced in these reactions showed the influence of the polar factors in the various steps of the homolytic induced decomposition: i.e. hydrogen abstraction to the solvent or to the peroxide and addition to the double bond.