Acyloxy radicals Initiator efficiency

The high rate of decarboxylation of aliphatic acyloxy radicals is also the prime reason behind low initiator efficiencies (see 3.3.2.1.3). Decarboxylation occurs within the solvent cage and recombination gives alkane or ester byproducts. Cage return for LPO is 18-35% at 80 °C in -octane as compared to only 4% for BPO under similar conditions.144... 

Diacetoxyiodo)benzene and [bis(trifluoroacetoxy)iodo]benzene generate radicals under photochemical conditions. These [bis(acyloxy)iodo]benzenes are efficient radical initiators for the polymerization of 2-[2-((dimethylamino)ethyl)methacrylate, methyl methacrylate, and styrene. Under photochemical conditions, [bis(acyloxy)iodo]benzenes readily produce free radicals that, in the presence of a hydrogen donor such as 1,4-cyclohexadiene, react with electron-deficient alkenes to give reductive addition products, as shown in Scheme 6. 

Bis(acyloxy)iodo]arenes are commonly used as efficient initiators of radical processes. Under photochemical conditions or heating these reagents undergo decarboxylative decomposition generating alkyl... 

---