1,4-Dichlorobenzene

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1,4-Dichlorobenzene
Names
IUPAC name
1,4-Dichlorobenzene
Other names
para-Dichlorobenzene
p-Dichlorobenzene
p-DCB
PDB
PDCB
Paramoth
Para crystals
Paracide
Dichlorocide
Properties
C6H4Cl2
Molar mass 147.00 g/mol
Appearance White solid
Odor Mothball-like
Density 1.2475 g/cm3 (20 °C)
Melting point 53.5 °C (128.3 °F; 326.6 K)
Boiling point 174 °C (345 °F; 447 K)
0.0105 g/100 ml (20 °C)
Solubility Soluble in acetone, benzene, chloroform, carbon disulfide, diethyl ether, ethanol
Vapor pressure 1.3 mmHg (20 °C)
Hazards
Safety data sheet Sigma-Aldrich
Flash point 66 °C
Lethal dose or concentration (LD, LC):
500 mg/kg (oral, rat)
2950 mg/kg (oral, mouse)
2512 mg/kg (oral, rat)
2830 mg/kg (oral, rabbit)
Related compounds
Related compounds
Benzene
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

1,4-Dichlorobenzene or p-dichlorobenzene, p-DCB is an organic compound with the formula C6H4Cl2.

Properties

Chemical

p-Dichlorobenzene reacts with strong bases to give hydroquinone. Reaction needs a catalyst.

Physical

1,4-Dichlorobenzene is a white solid, with a strong odor, insoluble in water.

Availability

1,4-Dichlorobenzene is available as naphthalene-free moth balls. Neither compounds can be used safely as moth repellent when mixed, meaning p-DCB mothballs should be relative pure.

Higher purity p-DCB can be bought from chemical suppliers.

Preparation

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, which can be purified by fractional crystallization, taking advantage of its relatively high melting point of 53.5 °C; the isomeric dichlorobenzenes and chlorobenzene melt well below room temperature.

Projects

  • Make hydroquinone
  • Make 1,4-dichloro-2-nitrobenzene

Handling

Safety

1,4-Dichlorobenzene is irritant and a suspected carcinogen. It is also classified as neurotoxin. Like many hydrocarbons, p-DCB is lipophilic and will accumulate in the fatty tissues.

Storage

Due to its strong smell and volatility, it's best to keep p-DCB is air-tight containers. Zipper bags are a good choice, but if you want better storage, an all-metal can with a lid, similar to those used for instant coffee or paint are better. If you worry about corrosion, check the interior of the can for any corrosion and then coat it in a protective polymer.

Disposal

p-DCB can be neutralized by slowly adding it in an oxidizing solution, such as chromic acid, piranha solution or Fenton's reagent. Do this outside and make sure you don't add too much to limit splashing and aerosolization of p-DCB.

References

Relevant Sciencemadness threads