Dibromomethane

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Dibromomethane
Stereo skeletal formula of dibromomethane eith all explicit hydrogens added
Spacefill model for dibromomethane
Identifiers
Abbreviations
CAS number 74-95-3 YesY
PubChem 3024
ChemSpider 2916 YesY
EC number 200-824-2
UN number 2664
MeSH methylene+bromide
ChEBI CHEBI:47077 YesY
RTECS number PA7350000
Beilstein Reference 969143
Gmelin Reference 25649
Jmol-3D images Image 1
Properties
Molecular formula CH2Br2
Molar mass 173.83 g mol−1
Appearance Colorless liquid
Density 2.477 g mL−1
Melting point −52.70 °C; −62.86 °F; 220.45 K
Boiling point 96 to 98 °C; 205 to 208 °F; 369 to 371 K
Solubility in water 12.5 g L−1 (at 20 °C)
Vapor pressure 4.65 kPa (at 20.0 °C)
kH 9.3 μmol Pa−1 kg−1
Refractive index (nD) 1.541
Thermochemistry
Specific
heat capacity
C
104.1 J K−1 mol−1
Hazards
GHS pictograms The exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word WARNING
GHS hazard statements H332, H412
GHS precautionary statements P273
EU Index 602-003-00-8
EU classification Harmful Xn
R-phrases R20, R52/53
S-phrases (S2), S24
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
LD50
  • 1 g kg−1 (oral, rabbit)
  • 3.738 g kg−1 (subcutaneous, mouse)
  • >4 g kg−1 (dermal, rabbit)
Related compounds
Related alkanes
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

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[edit]

Dibromomethane can be prepared from bromoform by reaction

CHBr3 + Na3AsO3 + NaOH → CH2Br2 + Na3AsO4 + NaBr

using sodium arsenite and sodium hydroxide.[2]

Another way is to prepare it from diiodomethane and bromine.

Uses[edit]

Dibromomethane is used as a solvent, gauge fluid, and in organic synthesis. It is a convenient agent for converting catechols to their methylenedioxy- derivatives.

Natural occurrence[edit]

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[edit]

  1. ^ "methylene bromide - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 25 March 2005. Identification. Retrieved 18 June 2012. 
  2. ^ Methylene bromide preparation

External links[edit]