Naphthodioxinone-1,3-benzodioxole as photochemically masked one-component type II photoinitiator for free radical polymerization

A 1,3-benzodioxole derivative of naphthodioxinone, namely 2-(benzo[d][1,3]dioxol-5-yl)-9-hydroxy-2-phenyl-4H-naphtho[2,3-d][1,3] dioxin-4-one was synthesized and characterized. Its capability to act as caged one-component Type II photoinitiator for free radical polymerization was examined. Upon irradiation, this photoinitiator releases 5-benzoyl-1,3- benzodioxole possessing both benzophenone and 1,3-dioxole groups in the structure as light absorbing and hydrogen donating sites, respectively. Subsequent photoexcitation of the benzophenone chromophore followed by hydrogen abstraction generates radicals capable of initiating free radical polymerization of appropriate monomers.