1,4-Dichlorobenzene
| 1,4-Dichlorobenzene | |
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1,4-Dichlorobenzene |
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Other names
para-Dichlorobenzene |
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| Identifiers | |
| CAS number | 106-46-7  |
| ChemSpider | 13866817  |
| UNII | D149TYB5MK |
| KEGG | C07092 |
| ChEMBL | CHEMBL190982 |
| RTECS number | CZ4550000 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | C6H4Cl2 |
| Molar mass | 147 g mol−1 |
| Density | 1.25 g/cm³, solid |
| Melting point |
53.5 °C, 327 K, 128 °F |
| Boiling point |
174 °C, 447 K, 345 °F |
| Solubility in water | 10.5 mg/100 mL (20 °C) |
| Hazards | |
| EU classification |  Xn NCarc. Cat. 3 |
| R-phrases | R36 R40 R50/53 |
| S-phrases | (S2) S36/37 S46 S60 S61 |
| NFPA 704 |
 2
2
0
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| Flash point | 66 °C |
| Related compounds | |
| Related compounds | 1,2-Dichlorobenzene 1,3-Dichlorobenzene |
 (verify) (what is:  / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
1,4-Dichlorobenzene (p-DCB, para-dichlorobenzene) 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 a pesticide and a deodorant, most familiarly in mothballs in which it is a replacement for the more traditional naphthalene. p-DCB is also used as a precursor in the production of the polymer poly(p-phenylene sulfide).[1]
Contents |
[edit] 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.[1]
[edit] Uses
[edit] Disinfectant, deodorant, and pesticide
p-DCB is used to control moths, moulds, and mildew.[2] It also finds use as a disinfectant[1] 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.[1]
[edit] Precursor to other chemicals
The chloride centres on p-DCB can be substituted with hydroxyl, amine, and sulfide groups. In a growing application, p-DCB is the precursor to the high performance polymer poly(p-phenylene sulfide):
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[edit] 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 US 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, although there is no direct evidence.[3] 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).[4] p-DCB is also an EPA-registered pesticide.[5] The US 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".[6]
[edit] See also
[edit] References
- ^ a b c d Manfred Rossberg, Wilhelm Lendle, Gerhard Pfleiderer, Adolf Tögel, Eberhard-Ludwig Dreher, Ernst Langer, Heinz Rassaerts, Peter Kleinschmidt, Heinz Strack, Richard Cook, Uwe Beck, Karl-August Lipper, Theodore R. Torkelson, Eckhard Löser, Klaus K. Beutel, “Chlorinated Hydrocarbons” in Ullmann’s Encyclopedia of Industrial Chemistry, 2006 John Wiley-VCH: Weinheim. doi:10.1002/14356007.a06 233.pub2
- ^ "National Pesticide Information Center – Mothballs Case Profile". http://npic.orst.edu/capro/Mothballs1.pdf. Retrieved 10 August 2009.
- ^ Preamble to the IARC Monographs definition of "Group 2B: Possibly carcinogenic to humans", the International Agency for Research on Cancer classification of this chemical
- ^ "Consumer Factsheet on: PARA-DICHLOROBENZENE (p-DCB)". 28 November 2006. Archived from the original on 6 October 2009. http://web.archive.org/web/20091006081817/http://www.epa.gov/ogwdw000/contaminants/dw_contamfs/p-dichlo.html. Retrieved 10 August 2009.
- ^ "Reregistration Eligibility Decision for Para-dichlorobenzene". December 2008. Archived from the original on 26 September 2009. http://web.archive.org/web/20090926200251/http://www.epa.gov/oppsrrd1/REDs/para-dichlorobenzene-red-revised.pdf. Retrieved 10 August 2009.
- ^ Proposition 65, Office of Environmental Health Hazard Assessment
[edit] External links
- International Chemical Safety Card 0037
- Mothball sniffing warning issued, BBC News, 27 July 2006
