Abstract
The photodegradation of 14C-fenothiocarb [S-(4-phenoxy-U-14C) butyl N, N-dimethylthiocarbamate] on a silica gel plate exposed to sunlight was studied. Radioactivity on the plate dissipated slowly with time. After 72hr exposure (Sept. to Oct.), 34% of fenothiocarb remained, and its half-life was estimated as approximately 45hr. Twelve photodegradation products were detected by two-dimensional thin-layer chromatography. Among twelve, products identified were S-4-phenoxybutyl N-formyl-N-methylthiocarbamate, S-4-phenoxybutyl N-methylthiocarbamate, bis(4-phenoxybutyl)thiolsulfinate, bis(4-phenoxybutyl)thiolsulfonate, fenothiocarb sulfoxide and 4-phenoxybutylsulfonic acid. A primary photochemical reaction seems to be the oxidation of sulfur to form fenothiocarb sulfoxide, followed by the cleavage of ester linkage and the oxidation or the dimerization of 4-phenoxy-butylsulfenic acid intermediate. Moreover, the oxidation of N-methyl moiety of fenothiocarb is suggested as the second photochemical reaction of fenothiocarb.
