Description:
2,6-Dichlorobenzonitrile (dichlobenil) is an herbicide used primarily in non-agricultural areas. It is commercially available under names such as Prefix, Barrier, Casoron, Dyclomec and Norosac. Although dichlobenil does not readily leach to groundwater, it is quickly metabolized to 2,6-dichlorobenzamide (BAM). Due to high water solubility and low sorption affinity in soil ([http://www.ncbi.nlm.nih.gov/pubmed/11455813|Albrechtsen et al., 2001]), the very persistant BAM has been detected in groundwater samples at levels which exceed current regulations ([http://www.ncbi.nlm.nih.gov/pubmed/18970297|Porazzi et al., 2005]). The first step in the microbial degradation of dichlobenil in previously exposed soils involves hydrolysis of the nitrile group to the benzamide. Further hydrolysis of the amide to a carboxylate is found to be much slower. Reductive dechlorination occurs both prior to, and after amide hydrolysis resulting in ortho-chlorobenzoate ([http://www.ncbi.nlm.nih.gov/pubmed/17240021|Holtze et al., 2007]). This last compound has several known biodegradation pathways.