Photodissociation of iodoaromatics in solution

Deiodination and isotopic-exchange processes are employed for determining the photodissociation yields of various iodoaromatic molecules in solution as a function of temperature and excitation wavelength. In the case of 1-iodonaphthalene the direct-excitation yields are compared with those obtained by photosensitization with benzophenone. The data indicate that dissociation takes place after thermal relaxation from either singlet or lowest triplet states. Photodissociation of these two excited states exhibits a different temperature dependence. Rate constants for the reaction of phenyl radicals with aromatic scavengers are determined and discussed along with the possibility of H-atom migration within the radical ring.