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{{chembox |
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{{Chembox |
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| verifiedrevid = 443634895 |
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| verifiedrevid = 445810807 |
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| ImageFileL1 = Dibromomethane.png |
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| ImageFile = Natta projection of dibromomethane.svg |
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| ImageSizeL1 = 120px |
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| ImageFile_Ref = {{chemboximage|correct|??}} |
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| ImageFileR1 = Dibromomethane 3D.png |
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| ImageSizeR1 = 120px |
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| ImageSize = 150 |
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| ImageName = |
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| IUPACName = Dibromomethane |
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| ImageFile1 = Dibromomethane 3D.png |
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| OtherNames = Methylene bromide, Methylene dibromide, Methyl dibromide, DBM, MDB, Refrigerant-30B2, UN 2664 |
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| ImageFile1_Ref = {{chemboximage|correct|??}} |
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| Section1 = {{Chembox Identifiers |
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| ImageSize1 = 100 |
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| InChIKey = FJBFPHVGVWTDIP-UHFFFAOYAK |
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| ImageName1 = Spacefill model for dibromomethane |
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| StdInChI_Ref = {{stdinchicite|correct|chemspider}} |
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| PIN = Dibromomethane<ref>{{Cite web|title=methylene bromide - Compound Summary|url=https://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=3024&loc=ec_rcs#x291|work=PubChem Compound|publisher=National Center for Biotechnology Information|access-date=18 June 2012|location=USA|date=25 March 2005|at=Identification}}</ref> |
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| StdInChI = 1S/CH2Br2/c2-1-3/h1H2 |
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| OtherNames = {{Unbulleted list|Methyl dibromide|Methylene bromide|Methylene dibromide|Refrigerant-30B2{{Citation needed|date=June 2012}} |
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| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} |
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}} |
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| StdInChIKey = FJBFPHVGVWTDIP-UHFFFAOYSA-N |
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|Section1={{Chembox Identifiers |
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| Abbreviations = {{Unbulleted list|DBM{{Citation needed|date=June 2012}}|MDB{{Citation needed|date=June 2012}}|UN 2664{{Citation needed|date=June 2012}}}} |
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| CASNo = 74-95-3 |
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| CASNo = 74-95-3 |
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| CASNo_Ref = {{cascite|correct|CAS}} |
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| CASNo_Ref = {{cascite|correct|CAS}} |
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| UNII_Ref = {{fdacite|correct|FDA}} |
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| EINECS = 200-824-2 |
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| UNII = V69B659W01 |
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| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |
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| PubChem = 3024 |
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| ChemSpiderID = 2916 |
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| ChemSpiderID = 2916 |
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| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |
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| PubChem = 3024 |
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| EINECS = 200-824-2 |
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| ChEBI_Ref = {{ebicite|correct|EBI}} |
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| UNNumber = 2664 |
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| MeSHName = methylene+bromide |
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| ChEBI = 47077 |
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| ChEBI = 47077 |
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| ChEBI_Ref = {{ebicite|correct|EBI}} |
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| RTECS = PA7350000 |
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| Beilstein = 969143 |
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| Gmelin = 25649 |
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| SMILES = BrCBr |
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| SMILES = BrCBr |
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| InChI = 1/CH2Br2/c2-1-3/h1H2 |
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| StdInChI = 1S/CH2Br2/c2-1-3/h1H2 |
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| StdInChI_Ref = {{stdinchicite|correct|chemspider}} |
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| RTECS = PA7350000 |
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| StdInChIKey = FJBFPHVGVWTDIP-UHFFFAOYSA-N |
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}} |
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| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} |
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| Section2 = {{Chembox Properties |
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}} |
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| Formula = CH<sub>2</sub>Br<sub>2</sub> |
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|Section2={{Chembox Properties |
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| MolarMass = 173.83 g/mol |
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| C=1 | H=2 | Br=2 |
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| Appearance = Clear colorless to yellowish heavy liquid of low viscosity |
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| Appearance = Colorless to yellow liquid |
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| Density = 2.4970 g/cm<sup>3</sup> at 20 °C |
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2.477 g/cm<sup>3</sup> at 25 °C |
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| Density = 2.477 g⋅mL<sup>−1</sup> |
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| MeltingPt = -52.7 °C |
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| MeltingPtK = 220.45 |
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| BoilingPtK = 369 to 371 |
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| BoilingPt = 96.95 °C |
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| Solubility = 12.5 g/l at 20 °C |
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| Solubility = 12.5 g⋅L<sup>−1</sup> (at 20 °C) |
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| VaporPressure = 60 hPa at 20 °C |
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| VaporPressure = 4.65 kPa (at 20.0 °C) |
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| HenryConstant = 9.3 μmol⋅Pa<sup>−1</sup>⋅kg<sup>−1</sup> |
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}} |
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| RefractIndex = 1.541 |
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| Section3 = {{Chembox Hazards |
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| MagSus = −65.10·10<sup>−6</sup>⋅cm<sup>3</sup>/mol |
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| EUClass = Harmful ('''Xn'''), Dangerous for the environment ('''N''') |
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}} |
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| MainHazards = |
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|Section3={{Chembox Thermochemistry |
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| FlashPt = None |
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| HeatCapacity = 104.1 J⋅K<sup>−1</sup>⋅mol<sup>−1</sup> |
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| Autoignition = |
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}} |
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| NFPA-H = 2 |
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|Section4={{Chembox Hazards |
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| NFPA-F = 0 |
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| GHSPictograms = {{GHS exclamation mark}} |
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| NFPA-R = 0 |
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| GHSSignalWord = '''WARNING''' |
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| NFPA-O = |
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| RPhrases = {{R20}} {{R52/53}} |
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| HPhrases = {{H-phrases|332|412}} |
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| SPhrases = {{S2}} {{S24}} {{S61}} |
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| PPhrases = {{P-phrases|273}} |
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| NFPA-H = 2 |
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}} |
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| NFPA-F = 0 |
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| NFPA-R = 0 |
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| LD50 = {{ubli |
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| 1 g⋅kg<sup>−1</sup> <small>(oral, rabbit)</small> |
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| 3.738 g⋅kg<sup>−1</sup> <small>(subcutaneous, mouse)</small> |
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| >4 g⋅kg<sup>−1</sup> <small>(dermal, rabbit)</small> |
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}} |
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}} |
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|Section5={{Chembox Related |
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| OtherFunction_label = alkanes |
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| OtherFunction = {{ubl |
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| ] |
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| ] |
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| ] |
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| ]}} |
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'''Dibromomethane''' or '''methylene bromide''', or '''methylene dibromide''' is a ] with the formula CH<sub>2</sub>Br<sub>2</sub>. It is slightly soluble in water but very soluble in ]. It is a colorless liquid. |
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==Physical properties== |
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'''Dibromomethane''' or '''methylene bromide''', or '''methylene dibromide''' is a ]. It is slightly soluble in water, but very soluble in ], ] and ]. |
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At ambient temperature, dibromomethane freezes around 0.61 ]. The crystal structure strongly suggests both interhalogen and hydrogen-halogen interactions.<ref name=Crystals /> |
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Its ] is 1.5419 (20 °C, D). |
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==Preparation== |
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==Preparation== |
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Dibromomethane can be prepared from ] by reaction |
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Dibromomethane is prepared commercially from dichloromethane via ]: |
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:6 CH<sub>2</sub>Cl<sub>2</sub> + 3 Br<sub>2</sub> + 2 Al → 6 CH<sub>2</sub>BrCl + 2 AlCl<sub>3</sub> |
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:CH<sub>2</sub>Cl<sub>2</sub> + HBr → CH<sub>2</sub>BrCl + HCl |
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The latter route requires ] as a catalyst.<ref name=Ullmann>{{ Ullmann | author = Dagani, M. J. | author2 = Barda, H. J. | author3 = Benya, T. J. | author4 = Sanders, D. C. | title = Bromine Compounds | doi = 10.1002/14356007.a04_405 }}</ref> |
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The bromochloromethane product from either reaction can further react in a similar manner: |
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:6 CH<sub>2</sub>BrCl + 3 Br<sub>2</sub> + 2 Al → 6 CH<sub>2</sub>Br<sub>2</sub> + 2 AlCl<sub>3</sub> |
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:CH<sub>2</sub>BrCl + HBr → CH<sub>2</sub>Br<sub>2</sub> + HCl |
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In the laboratory, it is prepared from ] using ] and ]:<ref>{{cite journal|title=Methylene bromide|journal=Org. Synth.|year=1929|volume=9|page=56|doi=10.15227/orgsyn.009.0056|author=W. W. Hartman, E. E. Dreger}}</ref> |
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:CHBr<sub>3</sub> + Na<sub>3</sub>AsO<sub>3</sub> + NaOH → CH<sub>2</sub>Br<sub>2</sub> + Na<sub>3</sub>AsO<sub>4</sub> + NaBr |
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:CHBr<sub>3</sub> + Na<sub>3</sub>AsO<sub>3</sub> + NaOH → CH<sub>2</sub>Br<sub>2</sub> + Na<sub>3</sub>AsO<sub>4</sub> + NaBr |
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using ] and ].<ref></ref> |
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Another way is to prepare it from ] and ]. |
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Another way is to prepare it from ] and ]. |
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==Uses== |
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==Uses== |
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Dibromomethane is used as a ], gauge fluid, and in ] (often as ] ]).<ref name=Ullmann/> It conviently converts ]s (such as ]) to their ] derivatives, and bromomethylenates ]s. It is a much cheaper precursor to a ]-type reagent than ].<ref>{{cite encyclopedia|doi=10.1002/047084289X.rd044|entry=Dibromomethane|first=Donald S.|last=Matteson|encyclopedia=]}}</ref> |
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Dibromomethane is used as a ], gage fluid, and in ]. |
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==Natural occurrence== |
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==Natural occurrence== |
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It is naturally produced by marine ] 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 ] 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 ] radicals. The estimated half life of this reaction is 213 days. |
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It is naturally produced by marine ] 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 ] 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 produced ] radicals. The estimated half life of this reaction is 213 days. |
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==References== |
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==References== |
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<references> |
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* {{cite journal | author = Podsiadlo M., Dziubek K., Szafranski M., Katrusiak A. | date = December 2006 | title = Molecular interactions in crystalline dibromomethane and diiodomethane, and the stabilities of their high-pressure and low-temperature phases | journal = Acta Cryst. | volume = B62 | issue = 6 | pages = 1090–1098(9) | pmid = 17108664| doi = 10.1107/S0108768106034963 | url = http://scripts.iucr.org/cgi-bin/paper?bk5037 | accessdate = 2007-06-29 }} |
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<ref name=Crystals>{{cite journal |author1=Podsiadlo M. |author2=Dziubek K. |author3=Szafranski M. |author4=Katrusiak A. | date = December 2006 | title = Molecular interactions in crystalline dibromomethane and diiodomethane, and the stabilities of their high-pressure and low-temperature phases | journal = Acta Crystallogr. B | volume = 62 | issue = 6 | pages = 1090–1098(9) | pmid = 17108664| doi = 10.1107/S0108768106034963 | url = https://www.researchgate.net/profile/Marek-Szafranski-2/publication/6688553_Molecular_interactions_in_crystalline_dibromomethane_and_diiodomethane_and_the_stabilities_of_their_high-pressure_and_low-temperature_phases/links/09e41510f72dc4ba1e000000/Molecular-interactions-in-crystalline-dibromomethane-and-diiodomethane-and-the-stabilities-of-their-high-pressure-and-low-temperature-phases.pdf | access-date = 2007-06-29 }}</ref> |
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<references/> |
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</references> |
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==External links== |
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==External links== |
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* {{ICSC|0354|03}} |
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* {{ICSC|0354|03}} |
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{{Halomethanes}} |
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{{Halomethanes}} |
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