Fact sheet: Dichloromethane

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

75-09-2

Molecular formula

CH2Cl2

Formula weight

84.9 g/mol

Family

Chlorinated aliphatic hydrocarbons (CAH)

Properties (at room temperature where applicable)

Compound properties list
ParameterValueComment
Melting/boiling point -96 0C / -40 0CLiquid
Relative density1.33Sinks in water
Vapour pressure375 mm HgVery volatile
Vapour density2.9Denser than air
Solubility in water15,000 mg/LVery soluble
Henry's law constant2 x 10-3 atm·m3/molRapid volatilization when dissolved
log Koc (Depending on soil or sediment characteristics)1.0 - 2.3*Weak adsorption to organic matter

Environmental behaviour

At 20 0C, dichloromethane is a liquid denser than water and very volatile. Characterized as very soluble, it will volatilize rapidly once dissolved and adsorbs weakly to organic matter. During a spill, the majority of this compound will evaporate but may also enter into the soil or migrate into a waterway. Once it encounters water (surface or subsurface), dichloromethane will primarily dissolve or will sink until it reaches an impermeable surface. The liquid dichloromethane that accumulates in a saturated zone will rapidly dissolve before significant volatilization occurs. The adsorbed dichloromethane in the vadose and saturated zones will rapidly disappear, liberating contamination in either the gaseous or dissolved state. The resulting plumes (gaseous or dissolved) will be relatively large in size.

Health and safety

Dichloromethane should be handled with care as it is toxic.

Principal resources

Dichloromethane is produced industrially by a two step process: methane or methanol is chlorinated followed by the chlorination of the resulting chloromethane. Production of dichloromethane grew steadily through the 1970s and early 1980s, but has since declined as more manufacturers move towards water-based aerosol systems in anticipation of more stringent regulations. Canada imports, rather than produces, dichloromethane.

Dichloromethane has been widely used as a solvent in paint strippers and varnish removers, as a propellant in aerosols, as a solvent in the manufacturing of drugs, pharmaceuticals and film coatings, as a metal cleaning and finishing solvent, in electronics manufacturing, and as an agent in urethane foam blowing. Aerosol products in which dichloromethane may be found include paints, automotive products, and insect sprays. Dichloromethane is also approved in Canada for use as a post-harvest insecticidal fumigant for stored grains. It is also a common by-product of pulp and paper bleaching.

References

Agency for Toxic Substances and Disease Registry (ATSDR). 2000. Toxicological Profile for Methylene Chloride. U.S. Department of Health and Human Services, Public Health Service, Georgia, USA. (Viewed December 2013)

Canadian Council of Ministers of the Environment, 1999. Canadian Water Quality Guidelines for the Protection of Aquatic Life: Halogenated Methanes (dichloromethane). In: Canadian Environmental Quality Guidelines. Canadian Council of Ministers of the Environment, Manitoba, Canada. (Viewed March 2010)

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

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