3,3'-Dichloro-4,5-dimethoxy-biphenyl is a derivative of PCB 11 (3,3'-dichlorobiphenyl) and was synthesized as an analytical standard to study the metabolism of PCB 11, a polychlorinated biphenyl (PCB) congener that is not present in technical PCB mixtures. This compound was synthesized via Suzuki cross coupling of 5-bromo-3-chloro-1,2-dimethoybenzene and 3-chlorophenylboronic acid.