Dichlobenil (Casoron) [2 ,6-Dichlorobenzonitrile] 
Prefix [2,6-Dichlorobenzenethioacetamide ] Chlorthiamid 
Dogs (beagles) and rats (Portan strain) did not show species differences 
in the patterns of elimination of metabolites of either Prefix or Dichlobenil. 
Single labeled doses of either compound were almost entirely eliminated in 
four days. Less than one-half of 1% of the dose was present in the carcass 
and viscera after removal of the gut. Most of the metabolites, upwards of 
60%, appeared in the urine. In the unhydrolyzed urine of rats dosed with 
either Prefix or Dichlobenil, free and conjugated metabolites were found: 
2 ,6-dichloro-3-hydroxyenzmitrile and 2,6-dichloro-4-hydroxybenzonitrile and 
their glucuronides and sulfate, and the ester glucuronides of 2,6-dichloro- 
benzoic acid and 2,6-Cl5-3-hydroxybenzoic acid. An unknown aromatic acid 
and two sulfur containing metabolites-—-possibly mercapturic compounds-—-were 
also observed (564). 
Examination of the collected urine of rabbits and rats fed dichlobenil 
showed the presence of residues in the amount of 2% and 6%, respectively, for 
these animals in the form of the 4-hydroxy analog; and 23% and 22%, respec- 
tively, in the form of 3-hydroxy analog, The hippurate conjugate was also 
observed (1517). 
2,6-dichlorobenzonitrile was found to be the main metabolite of Prefix 
in plants and unsterilized soil. There was slight evidence that Prefix 
also gave rise to a limited extent to the corresponding amide and thence 
to 2,6-dichlorobenzoic acid (564). 
Exposure to labeled dichlobenil showed that this compound can be 
absorbed from the atomosphere as well as from an aqueous solution. 
Alligatorweed [Alternanthera philoxeroides (Mart.) (Griseb.)], bean 
(Phaseolus vulgaris L.), fungi (Fusarium sp., Geotrichum sp., Penicillium 
sp., and Trichoderma sp.) and a mematode (Rhabditis sp.) were used to 
study dichlobenil metabolism. From water extracts, 2,6-dichlorobenzoic 
acid was isolated and identified by autoradiographs of thin-layer chroma- 
tograms and gas chromatography (932, 1133, 1134, 1135, 1136). 
When exposed to ultraviolet light, dichlobenil underwent dechlorination 
(1170). 
150 

