Fact sheet: Chloromethane

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

50.5 g/mol


Chlorinated aliphatic hydrocarbons (CAH)

Properties (at room temperature where applicable)

Compound properties list
Melting/boiling point -97 °C / -24 °CGas
Relative density0.92 g/cm3Liquid form floats on water
Vapour pressure3,800 mm HgExtremely volatile
Vapour density1.7Denser than air
Solubility in water6,000 mg/LModerately soluble
Henry's law constant8 x 10-3 atm·m3/molRapid volatilization when dissolved
log Koc (Depending on soil or sediment characteristics)Weak adsorption to organic matter

Environmental behaviour

At 20 0C, chloromethane is a gas that is easily liquefied under pressure and is both stored and transported by industry in its liquid form. Liquefied chloromethane it floats on water and is extremely volatile. Moderately soluble, it volatilizes rapidly when dissolved and binds weakly to organic matter. During a spill of liquefied chloromethane, the majority of the product will volatilize but can also enter into the soil or migrate into a waterway. Once it encounters water (surface or subsurface), chloromethane will mainly volatilize or dissolve before volatilizing. The adsorbed product resulting from a spill will disappear very rapidly in its gaseous state. The resulting gaseous plume in the soil will be significant while any dissolved plume will be relatively small in size.

Health and safety

Chloromethane should be handled with care as it is flammable and toxic.

Principal resources

Chloromethane is a natural and ubiquitous constituent of the oceans and atmosphere (it is the dominant organochlorine species in the atmosphere). Chloromethane has also been detected in surface waters, drinking water, groundwater and soils. It is both an anthropogenic and naturally occurring chemical. Anthropogenic sources include industrial production, burning of polyvinyl and wood. Natural sources are important and include the oceans, microbial fermentation and biomass fires.

Chloromethane is produced industrially by the reaction of methanol with hydrogen chloride or by the chlorination of methane. It is used mainly in the production of silicones, but also in the production of higher chlorinated methanes (dichloromethane, chloroform and carbon tetrachloride), agricultural chemicals, methyl cellulose, quaternary amines, medicinal drugs and synthetic rubber. In the past, chloromethane was widely used as a refrigerant, foam-blowing agent, fumigant, component in industrial solvents, and propellant in some cleansers. Chloromethane is no longer present in these products because of its toxic effects. Typically, manufacturing plants that produce chloromethane consume almost all their output internally as a feedstock for the production of other chemicals.


Agency for Toxic Substances and Disease Registry (ATSDR), 1998. Toxicological Profile for chloromethane, updated 2009. U.S. Department of Health and Human Services, Public Health Service, Georgia, USA. (Viewed December 2013).

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