TRANSFORMATION OF 2,6-DIETHYLANILIE IN SOIL1

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Abstract
We investigated the fate in soil of 2,6-diethylaniline (2,6-DEA), an intermediate in the microbial metabolism of certain acetanilide herbicides. At a concentration of 100 ppm in a soil-water slurry (10 g moist soil in citrate-phosphate buffer, pH 5.2), 2,6-DEA was converted to a number of products. These products were extracted with acetone from the soil fraction of the slurry. The two major products isolated with HPLC were identified as a dimer of 2,6-DEA,N-(2,6-diethylphenyl)-2,6-diethyl-p-benzoquinone monoimine (M-1), and a tetramer (M-2). Varying the pH values of the citrate-phosphate buffers used in the preparation of the soil slurries had a significant effect on the quantity of the products. The highest yields of both H-1 and M-2 were obtained at pH 3.8. The yield of the two products decreased with rising pH values. Sterilization of the soil by gamma irradiation did not inhibit the formation of products M-1 and M-2. However, 1-h autoclaving for 3 consecutive days completely destroyed the ability of the soil to catalyze the transformation of 2,6-DEA. Addition of EDTA to the incubation mixture for a final concentration of 0.6% (wt/vol) decreased the formation of M-1 and M-2, and the addition of the same concentration of NaN3 or Na2S2O4 completely inhibited the transformation of 2,6-DEA. Our results support the assumption that physicochemical factors play a significant role in the oligomerization reaction of an aniline in the soil.