<unk>  (HCCPD), also known as C-56, Graphlox, and HRS 1655, is an organochlorine compound with the formula C5Cl6. It is a precursor to pesticides, flame retardants, and dyes. It is a colourless liquid, although commercial samples appear lemon-yellow liquid sometimes with a bluish vapour. Many of its derivatives proved to be highly controversial, as studies showed them to be persistent organic pollutants. An estimated 270,000 tons were produced until 1976, and smaller amounts continue to be produced today. Two prominent manufacturers are Velsicol Chemical Corporation in the US and by Jiangsu Anpon Electrochemicals Co. in China.
Hexachlorocyclopentadiene
Butylated hydroxytoluene
Triphenylchloroethylene
Beta-Hexachlorocyclohexane
Triphenylbromoethylene
Alpha-Hexachlorocyclohexane
Desmethylchlorotrianisene
Vinyl chloride