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Dibromomethane

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Dibromomethane
Names
IUPAC name
Dibromomethane
Other names
Methylene bromide, Methylene dibromide, Methyl dibromide, DBM, MDB, Refrigerant-30B2, UN 2664
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.000.750 Edit this at Wikidata
EC Number
  • 200-824-2
RTECS number
  • PA7350000
  • InChI=1/CH2Br2/c2-1-3/h1H2
    Key: FJBFPHVGVWTDIP-UHFFFAOYAK
  • BrCBr
Properties
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
12.5 g/l at 20 °C
Vapor pressure 60 hPa at 20 °C
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2
0
0
Flash point None
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Dibromomethane or methylene bromide, or methylene dibromide is a halomethane. It is slightly soluble in water, but very soluble in carbon tetrachloride, diethyl ether and methanol. Its refractive index is 1.5419 (20 °C, D).

Preparation

Dibromomethane can be prepared from bromoform by reaction

CHBr3 + Na3AsO3 + NaOH → CH2Br2 + Na3AsO4 + NaBr

using sodium arsenite and sodium hydroxide.[1]

Another way is to prepare it from diiodomethane and bromine.

Uses

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

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 a 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. The estimated half life of this reaction is 213 days.

References

  • Podsiadlo M., Dziubek K., Szafranski M., Katrusiak A. (December 2006). "Molecular interactions in crystalline dibromomethane and diiodomethane, and the stabilities of their high-pressure and low-temperature phases". Acta Cryst. B62 (6): 1090–1098(9). doi:10.1107/S0108768106034963. PMID 17108664. Retrieved 2007-06-29.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  1. ^ Methylene bromide preparation
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