pentachlorobenzene pentachlorobenzene pentachlorobenzene (pecb) is a chemical compound with the molecular formula c6hcl5 which is a chlorinated aromatic hydrocarbon. it consists of a benzene ring substituted with five chlorine atoms. pecb was once used industrially for a variety of uses, but because of environmental concerns there are currently no large scale uses of pecb. pentachlorobenzene is a known persistent organic pollutant (pop) and banned globally by the stockholm convention on persistent organic pollutants in 2009. pentachlorobenzene names preferred iupac name pentachlorobenzene other names pecb identifiers cas number 608-93-5 y 3d model (jsmol) interactive image beilstein reference 1911550 chebi chebi:47136 y chembl chembl44628 y chemspider 21106570 y echa infocard 100.009.248 ec number 602-074-00-5 gmelin reference 51144 kegg c18141 pubchem cid 11855 rtecs number da6640000 unii d62gwo6832 y comptox dashboard (epa) dtxsid7024247 inchi inchi=1s/c6hcl5/c7-2-1-3(8)5(10)6(11)4(2)9/h1h nkey: ceocdnvzraioqz-uhfffaoysa-n ninchi=1/c6hcl5/c7-2-1-3(8)5(10)6(11)4(2)9/h1hkey: ceocdnvzraioqz-uhfffaoyav smiles c1c(cl)c(cl)c(cl)c(cl)c1cl properties chemical formula c6hcl5 molar mass 250.32 g·mol−1 appearance white or colorless crystals density 1.8 g/cm3 melting point 86 °c (187 °f; 359 k) boiling point 275 to 277 °c (527 to 531 °f; 548 to 550 k) solubility in water 0.68 mg/l hazards ghs labelling: pictograms signal word danger hazard statements h228, h302, h410 precautionary statements p210, p240, p241, p264, p270, p273, p280, p301+p312, p330, p370+p378, p391, p501 lethal dose or concentration (ld, lc): ld50 (median dose) rat: 1080 mg/kgmouse: 1175 mg/kg except where otherwise noted, data are given for materials in their standard state (at 25 °c , 100 kpa). n verify (what is yn ?) infobox references production pecb can be produced as a byproduct of the manufacture of carbon tetrachloride and benzene. it is extracted by distillation and crystallization. the direct production of pure pecb is not practical because of the simultaneous production of other chlorinated compounds. since pecb is generally produced in small quantities in the chlorination of benzene, it is also contained in other chlorobenzenes (dichlorobenzenes, trichlorobenzenes etc.) today, a majority of the pecb released into the environment is a result of backyard trash burning and municipal waste incineration. uses pecb was used as an intermediate in the manufacture of pesticides, particularly the fungicide pentachloronitrobenzene. pentachloronitrobenzene is now made by the chlorination of nitrobenzene in order to avoid the use of pecb. pecb was a component of a mixture of chlorobenzenes added to products containing polychlorinated biphenyls in order to reduce viscosity. pecb has also been used as a fire retardant. safety and regulation pecb is a persistent organic pollutant, allowing an accumulation in the food chain. consequently, pentachlorobenzene was added in 2009 to the list of chemical compounds covered by the stockholm convention, an international treaty which restricts the production and use of persistent organic pollutants. pecb has been banned in the european union since 2002. pecb is very toxic to aquatic organisms, and decomposes on heating or on burning with the formation of toxic, corrosive fumes including hydrogen chloride. combustion of pecb may also result in the formation of polychlorinated dibenzodioxins ("dioxins") and polychlorinated dibenzofurans.