 | |
 | |
| Names | |
|---|---|
| Preferred IUPAC name Dibromomethane[1] | |
Other names
| |
| Identifiers | |
| |
3D model (JSmol) | |
| Abbreviations |
|
| 969143 | |
| ChEBI | |
| ChemSpider |
|
| ECHA InfoCard | 100.000.750 |
| EC Number |
|
| 25649 | |
| MeSH | methylene+bromide |
| RTECS number |
|
| UNII | |
| UN number | 2664 |
| |
| |
| Properties | |
| CH2Br2 | |
| Molar mass | 173.835 g·mol−1 |
| Appearance | Colorless to yellow 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 |
| 12.5 g⋅L−1 (at 20 °C) | |
| Vapor pressure | 4.65 kPa (at 20.0 °C) |
Henry's law constant (kH) | 9.3 μmol⋅Pa−1⋅kg−1 |
| −65.10·10−6⋅cm3/mol | |
Refractive index (nD) | 1.541 |
| Thermochemistry | |
| 104.1 J⋅K−1⋅mol−1 | |
| Hazards | |
| GHS labelling: | |
 | |
| Warning | |
| H332,H412 | |
| P273 | |
| NFPA 704 (fire diamond) | |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose) |
|
| Related compounds | |
Related alkanes | |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Dibromomethane ormethylene bromide, ormethylene dibromide is ahalomethane with the formula CH2Br2. It is slightly soluble in water but very soluble inorganic solvents. It is a colorless liquid.
At ambient temperature, dibromomethane solidifies around 0.61 GPa. The crystal structure strongly suggests both interhalogen and hydrogen-halogen interactions.[2]
Dibromomethane is prepared commercially from dichloromethane viabromochloromethane:
The latter route requiresaluminium trichloride as a catalyst.[3]The bromochloromethane product from either reaction can further react in a similar manner:
In the laboratory, it is prepared frombromoform usingsodium arsenite andsodium hydroxide:[4]
Another way is to prepare it fromdiiodomethane andbromine.
Dibromomethane is used as asolvent, gauge fluid, and inorganic synthesis (often as1H-NMRinternal standard).[3] It conviently convertspolyols (such ascatechols) to theirmethylenedioxy derivatives, and bromomethylenatesenolates. It is a much cheaper precursor to aSimmons-Smith-type reagent thandiiodomethane.[5]
It is naturally produced by marinealgae 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 byvolatilisation with a half life of 5.2 hours. It has no significant degradation biological or abiological effects. In the atmosphere it will be lost because of reaction with photochemically producedhydroxyl radicals. The estimated half life of this reaction is 213 days.
