ABSTRACT
Photosensitizers may accelerate environmental photodecomposition, may lead to different products or make photodegradation possible. Compounds related to the chlorobiphenyls such as chlorodibenzodioxins and chlorodibenzofurans have shown to readily undergo photodecomposition in organic solvents. An identical spectrum of products was recently obtained when thin films of a number of chlorobiphenyls were irradiated with "blacklight" lamps and sunlight. Reductive dechlorination is the main initial photoreaction of chlorobiphenyls in organic solvents and the rate of dechlorination is faster in hydroxylic solvents such as methanol or iso-propanol than in nonpolar solvent, an observation which holds true also for other chloroaromatic compounds. The interactions of photosensitizers with pesticides have been studied but to date only one report deals with the effect of photosensitizers and quenchers on chlorobiphenyls. The mechanism of photoinduced isomerization of chlorobiphenyls may be different to the cases cited above and could proceed via phenyl-phenyl carbon bond or carbon chlorine bond breakage.
