Tetrachlorobenzene is any of three isomeric chlorobenzenes with the molecular formula . They differ by the positions of the chlorine atoms around the ring. Tetrachlorobenzenes are colorless crystalline compounds.
1,2,4,5-Tetrachlorobenzene can be produced by electrophilic halogenation of benzenes and some chlorobenzenes. 1,2,3,4-Tetrachlorobenzene can only be produced by chlorination of 1,3,5-trichlorobenzene.
1,2,4,5-Tetrachlorobenzene once was used in the production of the herbicide 2,4,5-trichlorophenoxyacetic acid. This method has been discontinued because it produced highly toxic 2,3,7,8-tetrachlorodibenzo-p-dioxin as a waste product.