2,4-Dichlorobenzoate is a key intermediate in the aerobic biodegradation of some of the 209 polychlorinated biphenyl (PCB) congeners. These are important environmental pollutants relatively resistance to biodegradation. This pathway includes 4-chlorobenzoate, an intermediate for preparation of dyes, fungicides, pharmaceuticals and other organic chemicals; and a preservative for adhesives and paints. It is based on [http://www.ncbi.nlm.nih.gov/pubmed/8626335|Romanov et al., 1996]; and [http://www.ncbi.nlm.nih.gov/pubmed/1853203|Scholten et al., 1991].