1,4-Dichlorobenzene
From Wikipedia, the free encyclopedia
| 1,4-Dichlorobenzene | |
|---|---|
 |
 |
| IUPAC name | 1,4-Dichlorobenzene |
| Other names | para-Dichlorobenzene p-Dichlorobenzene p-DCB PDB Paramoth Para crystals Paracide |
| Identifiers | |
| CAS number | [106-46-7] |
| RTECS number | CZ4550000 |
| SMILES | ClC1=CC=C(Cl)C=C1 |
| Properties | |
| Molecular formula | C6H4Cl2 |
| Molar mass | 147.00 g/mol |
| Density | 1.25 g/cm³, solid |
| Melting point |
53 °C |
| Boiling point |
174 °C |
| Solubility in water | 8 mg/100 ml (20 °C) |
| Hazards | |
| EU classification | Harmful (Xn) Carc. Cat. 3 Dangerous for the environment (N) |
| NFPA 704 |
 2
2
0
|
| R-phrases | R36, R40, R50/53 |
| S-phrases | (S2), S36/37, S46, S60, S61 |
| Flash point | 66 °C |
| Related compounds | |
| Related compounds | 1,2-Dichlorobenzene 1,3-Dichlorobenzene |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
|
1,4-Dichlorobenzene (para-dichlorobenzene, p-DCB, PDB) is the organic compound with the formula ClC6H4Cl. This colourless solid has an odor akin to that of camphor. It consists of two chlorine atoms substituted at opposing sites on a benzene ring. p-DCB is used a pesticide and a deodorant, most famously 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.[1]
[edit] Uses
[edit] Disinfectant, deodorant, and pesticide
p-DCB is used to control moths, moulds, and mildew. It finds use as a disinfectant in waste containers and restrooms and is the characteristic smell associated with urinal cakes. Its usefulness in these arises from p-DCB's low solubility in water and its relatively high volatility: it sublimes readily near room temperature.
[edit] Precursor to other chemicals
The chlorides on p-DCB can be substituted with oxygen, amine, and sulfide groups. A fast-growing application is in the synthesis of the high performance polymer poly(p-phenylene sulfide):
- ClC6H4Cl + Na2S → 1/n [C6H4S]n + 2 NaCl
[edit] Environmental effects
In air, 1,4-dichlorobenzene breaks down to harmless products in about one month. 1,4-Dichlorobenzene does not dissolve easily in water, and is not easily broken down by soil organisms. Like many hydrocarbons p-DCB is lipophilic and would accumulate in the fatty tissues.
[edit] Health effects
The US Department of Health and Human Services (DHHS) has determined that p-DCB may reasonably be anticipated to be a carcinogen, although there is no direct evidence. Animals given very high levels in water developed liver and kidney tumors. The United States Environmental Protection Agency (EPA) has set a maximum contaminant level of 75 micrograms of p-DCB per liter of drinking water (75 μg/L). p-DCB is also an EPA-registered pesticide. 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.
Little information is available on how children react to p-DCB exposure.
[edit] References
- ^ a b 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
