Phototransformation of some pesticides

The photochemical transformation of two fungicides, viz. fenarimol (1) and chlorothalonil (6), two herbicides, viz., metsulfuron methyl (15) and fluch loralin (20), and one insecticide, imidacloprid (26) has been carried out, the results of which form the subject-matter of the present review article. The degradation products are characterized on the basis of spectroscopic e vidence. The use of sensitizers like TiO2, KNO3, H2O2 is observed to enhanc e the photolytic rate. The results indicate that some of the photometabolit es could also be formed through biotic processes. It also reveals that phot ochemical transformation leads to detoxification of the pesticidal molecule s. The phototransformation processes involve N-dealkylation, nitro group re duction, cyclization, dimerization, oxidative cleavage, homolytic cleavage, dechlorination, decarboxylation and dehydration types of reactions.