1,4-Dichlorobenzene
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Names | |||
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IUPAC name
1,4-Dichlorobenzene
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Other names
para-Dichlorobenzene
p-Dichlorobenzene p-DCB PDB Paramoth Para crystals Paracide Dichlorocide |
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Identifiers | |||
106-46-7 ![]() |
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ChEBI | CHEBI:28618 ![]() |
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ChEMBL | ChEMBL190982 ![]() |
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ChemSpider | 13866817 ![]() |
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Jmol 3D model | Interactive image | ||
KEGG | C07092 ![]() |
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RTECS number | CZ4550000 | ||
UNII | D149TYB5MK ![]() |
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Properties | |||
C6H4Cl2 | |||
Molar mass | 147.00 g·mol−1 | ||
Appearance | Colorless/white crystals[1] | ||
Odor | mothball-like[1] | ||
Density | 1.25 g/cm3, solid | ||
Melting point | 53.5 °C (128.3 °F; 326.6 K) | ||
Boiling point | 174 °C (345 °F; 447 K) | ||
10.5 mg/100 mL (20 °C) | |||
Vapor pressure | 1.3 mmHg (20°C)[1] | ||
Vapor pressure | {{{value}}} | ||
Related compounds | |||
Related compounds
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1,2-Dichlorobenzene 1,3-Dichlorobenzene |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references | |||
1,4-Dichlorobenzene (p-DCB or para-dichlorobenzene, sometimes abbreviated as PDB or para) is an organic compound with the formula C6H4Cl2. This colorless solid has a strong odor. In terms of its structure, the molecule consists of two chlorine atoms substituted for hydrogen at opposing sites on a benzene ring. p-DCB is used as a pesticide and a deodorant, most familiarly in mothballs in which it is a replacement for the more traditional naphthalene due to its flammability. p-DCB is also used as a precursor in the production of the polymer poly(p-phenylene sulfide).[2]
Contents
Production
p-DCB is produced by chlorination of benzene using ferric chloride as a catalyst:
- C6H6 + 2 Cl2 → C6H4Cl2 + 2 HCl
The chief impurity is the 1,2 isomer. The compound can be purified by fractional crystallisation, taking advantage of its relatively high melting point of 53.5 °C; the isomeric dichlorobenzenes and chlorobenzene melt well below room temperature.[2]
Uses
Disinfectant, deodorant, and pesticide
p-DCB is used to control moths, moulds, and mildew.[3] It also finds use as a disinfectant[2] in waste containers and restrooms and is the characteristic smell associated with urinal cakes. Its usefulness for these applications arises from p-DCB's low solubility in water and its relatively high volatility: it sublimes readily near room temperature.[2]
Precursor to other chemicals
Nitration gives 1,4-dichloronitrobenzene, a precursor to commercial dyes and pigments.[4] The chloride centres on p-DCB can be substituted with hydroxylamine, and sulfide groups. In a growing application, p-DCB is the precursor to the high performance polymer poly(p-phenylene sulfide):[5]
Environmental and health effects
p-DCB is poorly soluble in water and is not easily broken down by soil organisms. Like many hydrocarbons, p-DCB is lipophilic and will accumulate in the fatty tissues.
The United States Department of Health and Human Services (DHHS) and the International Agency for Research on Cancer (IARC) have determined that p-DCB may reasonably be anticipated to be a carcinogen.[6] This has been indicated by animal studies, although a full-scale human study has not been done.[7] Animals given very high levels in water developed liver and kidney tumors.[citation needed]
The United States Environmental Protection Agency (EPA) has set a target maximum contaminant level of 75 micrograms of p-DCB per liter of drinking water (75 μg/L).[8] p-DCB is also an EPA-registered pesticide.[9] The United States Occupational Safety and Health Administration (OSHA) has set a maximum level of 75 parts of p-DCB per million parts air in the workplace (75 ppm) for an 8-hour day, 40-hour workweek.[citation needed]
Under California's Proposition 65, p-DCB is listed as "known to the State to cause cancer".[10] A probable mechanism for the carcinogenic effects of mothballs and some types of air fresheners containing p-DCB has been identified.[11][12]
See also
References
- ↑ 1.0 1.1 1.2 Cite error: Invalid
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- ↑ K. Hunger. W. Herbst "Pigments, Organic" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2012. doi:10.1002/14356007.a20_371
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Preamble to the IARC Monographs definition of "Group 2B: Possibly carcinogenic to humans", the International Agency for Research on Cancer classification of this chemical
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- ↑ Proposition 65, Office of Environmental Health Hazard Assessment
- ↑ "Scientists May Have Solved Mystery Of Carcinogenic Mothballs", Physorg.com, 20 June 2006.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
External links
- International Chemical Safety Card 0037
- Mothball sniffing warning issued, BBC News, 27 July 2006
- NIOSH Pocket Guide to Chemical Hazards, Centers for Disease Control and Prevention
- Pages with reference errors
- Use dmy dates from February 2012
- Articles without InChI source
- Pages using collapsible list with both background and text-align in titlestyle
- Articles with unsourced statements from August 2009
- Articles with unsourced statements from June 2008
- Organochloride insecticides
- IARC Group 2B carcinogens
- Chloroarenes