Light-induced transformations of methoxychlor in aquatic systems

Direct Electrochemical Reduction of 4,4′-(2,2,2-Trichloroethane-1,1-diyl)bis(methoxybenzene) (Methoxychlor) at Carbon and Silver Cathodes in Dimethylformamide

“…Cyclic voltammetric behavior of methoxychlor (2) and 4,4 -(ethene-1,1-diyl)bis(methoxybenzene) (7).-Shown in Figure 1 are cyclic voltammograms recorded at 100 mV s -1 for the reduction of 5.0 mM solutions of 2 at glassy carbon (dashed line) and silver (solid line) electrodes in DMF containing 0.050 M TBABF 4 . Cyclic voltammograms for reduction of 2 at glassy carbon exhibit a prominent cathodic peak at -1.14 V, followed by a small shoulder at -1.44 V, and two more irreversible cathodic peaks at -1.68 and -1.91 V. Similarly, voltammograms for reduction of 5.0 mM 2 at silver show an irreversible cathodic peak at -0.90 V, a shoulder at -1.40 V, and two additional prominent peaks at -1.66 and -1.94 V.…”

“…Solvent used in each experiment was dimethylformamide (DMF, EMD Chemicals, 99.9%). Tetra-n-butylammonium tetrafluoroborate (TBABF 4 , TCI Chemicals, 98%), employed as supporting electrolyte, was recrystallized from diethyl ether-ethyl acetate and stored in a vacuum oven at 80 o C. Zero-grade argon (Air Products) was used to remove oxygen from solutions prior to each experiment.…”

“…4 Biological degradation of methoxychlor results in the loss of one chlorine as well as demethylation of the hydroxylbenzene moieties.…”

“…3 Sunlight increases the photolysis rate, so that the half-life at the surface of distilled water is closer to 4.5 months, and even faster in natural waters where half-lives of only 2-5 h are seen. 4 Biological degradation of methoxychlor results in the loss of one chlorine as well as demethylation of the hydroxylbenzene moieties. 5 Uptake of methoxychlor in a model ecosystem has also been examined; whereas methoxychlor was found to be in a dynamic state in fish, it accumulated in snails.…”

Direct photolysis mechanism of pesticides in water

“…The 4-OH derivatives of diuron 137) and linuron 138) were mainly produced by irradiation at 365 nm, while the predominant formation of 3-OH derivatives was observed at 254 nm. Dicamba 141) and pentachlorophenol 140) mainly underwent the photosubstitution of Cl by OH, while the radical mechanism was most likely for methoxychlor 141) and DDE. 142) The LFP study with quenching by 3 O 2 showed T* as a key intermediate in the photolysis of chlorothalonil, and reductive dechlorination was the main reaction in water.…”