PHOTOTRANSFORMATION OF LINURON AND CHLORBROMURON IN AQUEOUS-SOLUTION

The main photoproducts initially formed in the phototransformation of linuron and chlorbromuron in aqueous solution result from photohydroly sis, i.e. hydroxylation with release of halide ion, and from eliminati on of a methoxy group. Reductive debromination was also observed with chlorbromuron. The transformation is less specific than with diuron. T he orientation of the reaction depends on the wavelength: short wavele ngths (254 nm) favour demethoxylation and photohydrolysis in the meta position whereas, with 'black light', i.e. wavelengths longer than 330 nm, photohydrolysis in the para position is the main reaction observe d.