Study of the Mode of Action of Some Nitrodiphenyl Ethers

Abstract

Nitrosoderivatives of the nitrodiphenyl ether herbicides (nitrofen, bifenox) have been studied. UV irradiation in different organic solvents gives degradation products. In buffered aqueous media, in the presence of chloroplasts and spin traps such as DMPO, hydroxy and peroxy radicals have been characterized. In organic media and in the presence of spin traps such as DMPO, PBN, 4-POBN, solvent radicals (.CHCl2, .CCl3, .CH2 [symbol: see text]) have been formed. Nitro-derivatives have been studied under UV irradiation and in the presence of tetramethylethylene (TME), alkenylhydroxylamines are formed which autoxidize in nitroxide radicals. The formation of the stable nitroxide radical occurs in the dark process after continuous irradiation. The intensity of the signal decreases strongly when a new irradiation is applied. Radical species, with analogous ESR spectral characteristics are formed on reaction with nitrodiphenyl ethers and fatty acids. The reactivity of these herbicides in micellar media (SDS, Brij 35, and CTAB) has been investigated. The kinetics of formation of the ESR signal corresponding to the photoreduction of the nitrodiphenyl ether in the presence of TME behave differently in a micellar environment as compared to solution. The intensity of the formation of the nitroxide increases under irradiation and decreases in the dark; the rotational correlation time tau c has been determined for each type of micelle. Synthetic nitrosodiphenyl ether made by the reduction of nitrodiphenyl ether using hydrogen gas and PtO2 as a catalyst gives the corresponding amine, which is oxidized with meta-chloroperbenzoic acid (m.CPBA). The nitrosodiphenyl ether in the presence of soja azolectin liposome containing a fluorescent probe has been analysed.(ABSTRACT TRUNCATED AT 250 WORDS)