Dibromomethane

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Dibromomethane

IUPAC name	Dibromomethane
Other names	Methylene bromide, Methylene dibromide, Methyl dibromide, DBM, MDB, Refrigerant-30B2, UN 2664
Identifiers
CAS number	[74-95-3]
PubChem	3024
EINECS number	200-824-2
RTECS number	PA7350000
SMILES	C(Br)Br
InChI	1/CH2Br2/c2-1-3/h1H2
Properties
Molecular formula	CH₂Br₂
Molar mass	173.83 g/mol
Appearance	Clear colorless to yellowish heavy liquid of low viscosity
Density	2.4970 g/cm³ at 20 °C 2.477 g/cm³ at 25 °C
Melting point	-52.7 °C
Boiling point	96.95 °C
Solubility in water	12.5 g/l at 20 °C
Vapor pressure	60 hPa at 20 °C
Hazards
EU classification	Harmful (Xn), Dangerous for the environment (N)
NFPA 704	0 2 0
R-phrases	R20 R52/53
S-phrases	(S2) S24 S61
Flash point	None
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Dibromomethane or methylene bromide, or methylene dibromide is a halomethane. It is slightly soluble in water, but very soluble in carbon tetrachloride, ether and methanol. Its refractive index is 1.5419 (20 °C, D).

1 Preparation
2 Uses
3 Natural occurrence
4 References
5 See also
6 External links

[edit] Preparation

Dibromomethane can be prepared from bromoform by reaction

CHBr₃ + Na₃AsO₃ + NaOH → CH₂Br₂ + Na₃AsO₄ + NaBr

using sodium arsenite and sodium hydroxide.^[1]

Other way is to prepare it from diiodomethane and bromine.

[edit] Uses

Methylene bromide is used as a solvent, gage fluid and in organic synthesis.

[edit] Natural occurrence

It is naturally produced by marine algae and liberated to the oceans. Releasing on soil causes it to evaporate and leach into the ground. Releasing in water causes it to be lost mainly by volatilisation with half life of 5.2 hours. It has no significant degradating biological or abiological effects. In the atmosphere it will be lost because of reaction with photochemically produced hydroxyl radicals. Estimate half life of this reaction is 213 days.