3D model (Jmol)
|Molar mass||250.32 g·mol−1|
|Appearance||White or colorless crystals|
|Melting point||86 °C (187 °F; 359 K)|
|Boiling point||275 to 277 °C (527 to 531 °F; 548 to 550 K)|
|R-phrases (outdated)||R11 R22 R50/53|
|S-phrases (outdated)||(S2) S41 S46 S50 S60 S61|
|Lethal dose or concentration (LD, LC):|
LD50 (median dose)
|rat: 1080 mg/kg
mouse: 1175 mg/kg
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
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 pollutants (POP), classified among the "dirty dozen" and banned globally by the Stockholm Convention on Persistent Organic Pollutants as of 2011.
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.
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.
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.
- Pentachlorobenzene Safety Card, International Programme on Chemical Safety
- Shen, L., Wania, F., Lei, Y. D., Teixeira, C., Muir, D. C. G., Bidleman, T. F. (2005). "Compilation, evaluation, and selection of physical-chemical property data for organochlorine pesticides". J. Chem Eng. Data. 50 (3): 742–768. doi:10.1021/je049693f.
- Pentachlorobenzene Fact Sheet, U.S. Environmental Protection Agency
- Pentachlorobenzene – Sources, environmental fate and risk characterization, Robert E. Bailey, EuroChlor, July 2007
- Governments unite to step-up reduction on global DDT reliance and add nine new chemicals under international treaty, Stockholm Convention on Persistent Organic Pollutants, 9 May 2009
- Adding the 'Nasty Nine' to the 'Dirty Dozen', thedailygreen.com