“…Reaction 21 indicates that photochemical processes occurring were ring hydroxylation, methyloxidation, N-demethylation, decWorination, dimerization, and trimerization. For instance, in the case of Rayonet Photoreactor (3 hr) exposure the yields of major products such as compounds 77, 78,80,83,85, and 87 from herbicide 76 were 0.6, trace ( < 0.05), 7.1, 1.5, 1.6, and 1.5%, respectively; while yields of these products were 1.0, 1.0, 2.0, 1.6, 0.4, and 0.3%, respectively, when aqueous solution of 76 was exposed to UV for 25 hr using a Hanovia lamp light source (see Reaction 21) (Tanaka et al 1977). Likewise, quantum yields for the photogeneration of products 77,80, 83,85, and 87 arising from monuron were 0.001,0.01,0.006,0.003, and 0.002, respectively; the starting material being irradiated for 45 min with a Rayonet Reactor.…”