Fact sheet: 1,4-dichlorobenzene

From: Public Services and Procurement Canada

Discover a list of a contaminant's important chemical properties, how it will react in the environment, main sources of contamination related, and a brief overview of health and safety issues.

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General information

CAS number

106-46-7

Molecular formula

C6H4Cl2

Formula weight

147 g/mol

Family

Chlorobenzenes

Properties (at room temperature where applicable)

Compound properties list
ParameterValueComment
Melting/boiling point25 0CSolid
Relative density1.24Sinks in water
Vapour pressure1 mm HgLow to moderate volatility
Vapour density5.1Much denser than air
Solubility in water70 mg/LLow solubility
Henry's law constant2 x 10-3atm·m3/molRapid volatilization once dissolved
log Koc (Depending on soil or sediment characteristics)2.5 - 3.3*Strong adsorption to organic matter

Environmental behaviour

At 20 0C, 1,4-dichlorobenzene is a solid with low to moderate volatility and low solubility. Once it is dissolved, it volatilizes rapidly and adsorbs strongly to organic matter. When present in the soil, it volatilizes and dissolves slowly. Once dissolved, 1,4-dichlorobenzene can reach the water table or drain into a waterway where it will be diluted before volatilizing. Fragments of 1,4-dichlorobenzene can also be carried into waterways where they will be deposited at the bottom and slowly dissolve. Once the source is gone, the adsorbed phase will take a long time to disappear, liberating contamination in either the gaseous or dissolved state. The resulting plumes (gaseous and dissolved) are generally small in size.

Health and safety

1,4-dichlorobenzene should be handled with care as it is flammable and toxic.

Principal resources

1,4-dichlorobenzene does not occur naturally. Chlorinated benzenes are typically produced by reacting liquid benzene with gaseous chlorine in the presence of a catalyst at moderate temperatures and atmospheric pressures. This reaction yields a mixture of chlorobenzene isomers with varying degrees of chlorination. 1,4-dichlorobenzene is the most important of the three dichlorobenzene isomers.

1,4-dichlorobenzene is used industrially as a disinfectant, a deodorizer and air freshener, an insect and bird repellent, and in the synthesis of polyethylene sulphide resin. Domestic uses are primarily as a moth repellent (moth balls), as an air freshener, and as a toilet block. 1,4-dichlorobenzene is also used as an intermediate in the production of other chemicals such as 1,2,4-trichlorobenzene. Minor uses of 1,4- dichlorobenzene include the control of certain tree-boring insects and ants, and in the control of blue mold in tobacco seed beds. There is also evidence of dichlorobenzene production from the dehalogenation of more highly chlorinated benzenes and during incineration of organic matter containing chlorine.

References

Agency for Toxic Substances and Disease Registry (ATSDR). 2006. Toxicological profile for dichlorobenzenes. U.S. Department of Health and Human Services, Public Health Service. Georgia, U.S.A. (Viewed December 2013)

Canadian Council of Ministers of the Environment. 1999. Canadian water quality guidelines for the protection of aquatic life: Chlorinated benzenes-1,4-Dichlorobenzene. In: Canadian environmental quality guidelines, 1999. Canadian Council of Ministers of the Environment, Winnipeg. Canada. (Viewed December 2013)

Environment Canada. 2009. CEPA Environmental Registry: Toxic Substances List-Updated Schedule 1 as of December 27, 2006. Environment Canada. (Viewed December 2013)

Environment Canada. 2003. Follow-up report on five PSL1 substances for which there was insufficient information to conclude whether the substances constitute a danger to the environment. Government of Canada. (Viewed December 2013)

Montgomery, John H. 2007. Groundwater Chemicals, Desk Reference, Fourth Edition, CRC Press, Taylor and Francis Group, Florida, U.S.A.

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