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Dichloromethane
General
Systematic name	dichloromethane
Other names	methylene chloride
Molecular formula	CH2Cl2
SMILES	C(Cl)Cl
Molar mass	84.93 g/mol
Appearance	colorless liquid
CAS number	*
Properties
Density and phase	1.325 g/cm3, liquid
Solubility in water	1.3 g/100 ml (20 °C)
Solubility in acetone, ethanol, diethyl ether	10 g/100 ml
Melting point	−97 °C (176 K)
Boiling point	40 °C (313 K)
Viscosity	0.44 cP at 20 °C
Hazards
MSDS	External MSDS
Main hazards	Harmful (Xn)
NFPA 704
Flash point	None
R/S statement	R: 40 S: 23/24/25/36/37
RTECS number	PA8050000
Supplementary data page
Structure and properties	n, εr, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Related Haloforms	Difluoromethane
Related Chloromethanes	Chloromethane Chloroform Carbon tetrachloride
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Chemical infobox

Dichloromethane or methylene chloride is a chemical compound widely used as a solvent for organic materials, with the chemical formula of CH₂Cl₂. It is a colorless, volatile liquid with a moderately strong aroma, which is sweet in some sense but which makes some people feel very uncomfortable.

Methylene chloride was first prepared in 1840 by the French chemist Henri Victor Regnault, who isolated it from a mixture of chloromethane and chlorine that had been exposed to sunlight.

Production

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Industrially, methylene chloride is produced by reacting either methyl chloride or methane with chlorine gas at 400-500°C. At these temperatures, both methane and methyl chloride undergo a series of reactions producing progressively more chlorinated products.

CH₄ + Cl₂ → CH₃Cl + HCl

CH₃Cl + Cl₂ → CH₂Cl₂ + HCl

CH₂Cl₂ + Cl₂ → CHCl₃ + HCl

CHCl₃ + Cl₂ → CCl₄ + HCl

The output of these processes is a mixture of methyl chloride, methylene choride, chloroform, and carbon tetrachloride. These compounds are then separated by distillation.

Uses

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Methylene chloride's volatility and ability to dissolve a wide range of organic compounds makes it an ideal solvent for many chemical processes. It is mainly used as a paint stripper and a degreaser. In the food industry, it is used to decaffeinate coffee and to prepare extracts of hops and other flavorings. Its volatility has led to its use as an aerosol spray propellant and as a blowing agent for polyurethane foams. It is also used as a fumigant pesticide for stored strawberries and grains. It is also the most common "active" component in Drinking Birds. However, concerns about its health effects have led to a search for alternatives to it in many of these applications.

It is used in Christmas lights called bubble lights, in a sealed vial which bubbles when the incandescent light bulb below it is lit. Wurlitzer also used it in their 1940's "bubbler" style jukeboxes. The bubble tubes were up to 30 inches long and used resistors to provide the heat to boil the liquid in a small constricted chamber that had bits of rock and a special glass valve to concentrate the small bubbles into larger ones. It is still used today in their reproduction machines.

Safety

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Methylene chloride is the least toxic of the simple chlorohydrocarbons, but it is not without its health risks. Chronic exposure to methylene chloride may be carcinogenic, as it has been linked to cancer of the lungs, liver, and pancreas in laboratory animals. It is a mutagen and teratogen, causing birth defects if women are exposed to it during pregnancy. Prolonged skin contact can result in the methylene chloride dissolving some of the fatty tissues in skin, resulting in skin irritation or chemical burns.

In many countries, products containing methylene chloride must carry labels warning of its health risks.

External links

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• National Pollutant Inventory - Dichloromethane Fact Sheet

Aerosol propellants | Organochlorides | Solvents

Metylenklorid | Cloruro de metileno | Dichlorométhane | Diclorometano | Dichloormethaan | ジクロロメタン