Aspects of the environmental chemistry of methoxychlor

Abstract

Preliminary investigations on the Environmental Chemistry of Methoxychlor [2,2-bis (p - methoxyphenyl)-1,1,1- trichloroethane], a potential DDT replacement, have been conducted with emphasis on its degradation by micro-organisms. Literature reports on the microbial degradation of methoxychlor are scarce, and in those reports the major emphasis is on the interaction of this pesticide with bacteria. Therefore, studies concerning the interaction of micro-organisms with methoxychlor were initiated. The micro-organisms used were the common soil fungi: Trichoderma viride, Mortierella isabellina, M,pusilla, and the aquatic fungus Saprolegnia parasitica. Also because of anomalous results reported in the literature on the possible biodegradation of methoxychlor by a bacterium, Klebsiella pneumoniae, this aspect of the environmental fate of methoxychlor was reinvestigated. Known metabolites of methoxychlor required for this study were synthesized. Some of the synthetic methods were slightly modified so as to improve yields or facilitate purification of the products. Also to facilitate the identification of possible degradation products, the spectroscopic properties (MS and NMR) of these various methoxychlor derivatives were studied. A gas chromatographic method was developed for the analyses of these compounds and included the silylation of the phenolic compounds. Little is known about the fungitoxicity of methoxychlor or its metabolites, thus such fungitoxicity studies were carried out. It was found that the dihydroxy methoxychlor derivatives were more toxic than the dimethoxy methoxychlor derivatives, towards the fungi used. In fungal metabolism studies with methoxychlor, M.isabellina, M.pusilla and S.parasitica were found to be capable of partially degrading methoxychlor, by effecting the ether cleavage of the methoxy groups in the molecule. T.viride did not effect a similar alteration of the methoxychlor molecule but appears to produce at least one metabolite of methoxychlor. It is suggested that this metabolite is a glycoside. No evidence was found to indicate that the fungi studied attacked the central part of the methoxychlor molecule. K,pneumoniae was found to be capable of the reductive dechlorination of methoxychlor and also its hydroxy derivative [2,2-bis (p - hydroxyphenyl) -1,1,1- trichloroethane]. It was also established that this bacterium does not effect the cleavage of the methoxy groups in methoxychlor. .