Fact sheet: 1,2,4-trichlorobenzene

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


Molecular formula


Formula weight

181.5 g/mol



Properties (at room temperature where applicable)

Compound properties list
Melting/boiling point 17 °C / 213 °CLiquid or solid
Relative density1.45 g/cm3Sinks in water
Vapour pressure0.3 mm HgLow volatility
Vapour density6.3Much denser than air
Solubility in water40 mg/LLow solubility
Henry's law constant2 x 10-3atm·m3/molRapid volatilization when dissolved
log Koc (Depending on soil or sediment characteristics)2.8 - 3.9*Strong adsorption to organic matter

Environmental behaviour

At 20 0C, 1,2,4-trichlorobenzene can be found as either a liquid or solid. Denser than water, 1,2,4-trichlorobenzene has low volatility and solubility. Once dissolved, it rapidly volatilizes and adsorbs strongly to organic matter. As a solid, 1,2,4-trichlorobenzene in soil will slowly dissolve. In its liquid form, 1,2,4-trichlorobenzene will enter into the soil or drain towards a waterway before it volatilizes. Liquid 1,2,4-trichlorobenzene that accumulates in the saturated zone will dissolve slowly before a significant portion volatilizes. Once the source has been removed, 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

1,2,4-trichlorobenzene should be handled with care, as it is toxic.

Principal resources

1,2,4-trichlorobenzene is the most common trichlorobenzene isomer. Although there are currently no producers of trichlorobenzenes in Canada, an estimated 40 to 50 tonnes per year were imported during the mid-1990s. Of this amount, about 30 tonnes were used as solvents in textile manufacturing, and about 15 tonnes were used as intermediates in the production of other chemicals.

In the past, trichlorobenzenes were used in combination with polychlorinated biphenyls (PCBs) in dielectric fluids for transformers and capacitors until 1980 when regulations prohibited new uses of PCB-containing dielectric fluids. Approximately 2,600,000 tonnes of trichlorobenzenes are present in transformer dielectric fluids either in use or stored before disposal. In the United States, trichlorobenzenes are also used as degreasing agents and lubricants.

1,2,4-trichlorobenzene is used industrially as dye carrier, an intermediate in chemical production (especially herbicides), a degreasing agent, and a lubricant. Trichlorobenzene isomers have been identified in pulp and paper mill effluents. Effluents from iron and steel manufacturing contribute to the environmental load of trichlorobenzenes, while petroleum refinery effluents have been reported to contain trichlorobenzene isomers. The more highly chlorinated benzenes, particularly hexachlorobenzene, are subject to reductive dechlorination, which may contribute to the accumulation of the lower chlorinated homologues (example, dichlorobenzenes and trichlorobenzenes) in buried sediments.


Canadian Council of Ministers of the Environment (CCME). 1999. Canadian water quality guidelines for the protection of aquatic life: Chlorinated benzenes 1,2,3-Trichlorobenzene. In: Canadian environmental quality guidelines, 1999, Canadian Council of Ministers of the Environment, Winnipeg. Canada. (Viewed December 2013)

Government of Canada. 1993. Canadian Environmental Protection Act (CEPA). Priority Substances List Assessment Report: Trichlorobenzenes. Environment Canada and Health Canada Ottawa. (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.