ABSTRACT
In photooxidized polymers, hindered phenols yield hydroperoxycyclohexadienones (e.g., 98). Singlet oxygen and excited sensitizers are considered as active coreactants in their formation (42,48,58).
Some primary transformation products, such as structures 89, 92, 93, or 95 are unstable and are usually formed only transiently. Other products, with general structures, 86, 88, 90, 91, 96-98, derived from different mono-and polynuclear phenols were isolated. The C-C-coupling dimer of type 88 and quinone methide 86 rank among the most stable products (42-57,58).
