Pentachlorobenzene

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. 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.

References

References

1. [http://www.inchem.org/documents/icsc/icsc/eics0531.htm Pentachlorobenzene Safety Card], [[International Programme on Chemical Safety]]
2. 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.
3. [https://web.archive.org/web/20110206155632/http://www.epa.gov/waste/hazard/wastemin/minimize/factshts/pentchlb.pdf Pentachlorobenzene Fact Sheet], [[U.S. Environmental Protection Agency]]{{dead link. (November 2024)
4. [http://www.eurochlor.org/upload/documents/document260.pdf Pentachlorobenzene – Sources, environmental fate and risk characterization] {{webarchive. link. (2008-12-27 , Robert E. Bailey, EuroChlor, July 2007)
5. [http://chm.pops.int/Convention/Pressrelease/COP4Geneva8May2009/tabid/542/ Press Release – COP4 – Geneva, 8 May 2009: Governments unite to step-up reduction on global DDT reliance and add nine new chemicals under international treaty], 2009.
6. 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.[http://chm.pops.int/Convention/Media/Pressreleases/COP4Geneva9May2009/tabid/542/language/en-US/Default.aspx 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
7. [http://www.thedailygreen.com/environmental-news/latest/toxic-chemicals-47101403 Adding the 'Nasty Nine' to the 'Dirty Dozen'] {{Webarchive. link. (2013-12-06 , thedailygreen.com)