CHEMICAL AND PHOTOCHEMICAL TRANSFORMATION OF CHLOROTHALONIL

Photolysis of chlorothalonil (2,4,5,6-tetrachloro isophthalonitrile) i n dichloromethane by ultra violet light (>290 nm) was investigated. It gave 2,5,6-trichloro-1,4-dicyanobenzene and 5,6-dichloro-1,4-dicyanob enzene as the major photoproducts. Photolysis was followed by a steady decrease in chlorothalonil and monodehalogenated product concentratio n with a concomitant increase in the didehalogenated product. When thi n films are exposed to sunlight, chlorothalonil has a half life of 9 h rs on a glass surface.