Dibromomethane or methylene bromide, or methylene dibromide is a halomethane with the formula CH2Br2. It is slightly soluble in water but very soluble in organic solvents. It is a colorless liquid.
Dibromomethane is prepared commercially from dichloromethane via bromochloromethane:
6 CH2Cl2 + 3 Br2 + 2 Al → 6 CH2BrCl + 2 AlCl3
CH2Cl2 + HBr → CH2BrCl + HCl
The latter route requires aluminium trichloride as a catalyst.[2] The bromochloromethane product from either reaction can further react in a similar manner:
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 degradation 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.
Referencesedit
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 Crystallogr. B. 62 (6): 1090–1098(9). doi:10.1107/S0108768106034963. PMID 17108664. Retrieved 2007-06-29.
^"methylene bromide - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 25 March 2005. Identification. Retrieved 18 June 2012.
^W. W. Hartman, E. E. Dreger (1929). "Methylene bromide". Org. Synth. 9: 56. doi:10.15227/orgsyn.009.0056.
External linksedit
International Chemical Safety Card 0354
January 01, 1970
dibromomethane, methylene, bromide, methylene, dibromide, halomethane, with, formula, ch2br2, slightly, soluble, water, very, soluble, organic, solvents, colorless, liquid, names, preferred, iupac, name, other, names, methyl, dibromidemethylene, bromidemethyle. Dibromomethane or methylene bromide or methylene dibromide is a halomethane with the formula CH2Br2 It is slightly soluble in water but very soluble in organic solvents It is a colorless liquid Dibromomethane Names Preferred IUPAC name Dibromomethane 1 Other names Methyl dibromideMethylene bromideMethylene dibromideRefrigerant 30B2 citation needed Identifiers CAS Number 74 95 3 Y 3D model JSmol Interactive image Abbreviations DBM citation needed MDB citation needed UN 2664 citation needed Beilstein Reference 969143 ChEBI CHEBI 47077 Y ChemSpider 2916 Y ECHA InfoCard 100 000 750 EC Number 200 824 2 Gmelin Reference 25649 MeSH methylene bromide PubChem CID 3024 RTECS number PA7350000 UNII V69B659W01 Y UN number 2664 CompTox Dashboard EPA DTXSID4021557 InChI InChI 1S CH2Br2 c2 1 3 h1H2 YKey FJBFPHVGVWTDIP UHFFFAOYSA N Y SMILES BrCBr Properties Chemical formula C H 2Br 2 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 Solubility in water 12 5 g L 1 at 20 C Vapor pressure 4 65 kPa at 20 0 C Henry s lawconstant kH 9 3 mmol Pa 1 kg 1 Magnetic susceptibility x 65 10 10 6 cm3 mol Refractive index nD 1 541 Thermochemistry Heat capacity C 104 1 J K 1 mol 1 Hazards GHS labelling Pictograms Signal word Warning Hazard statements H332 H412 Precautionary statements P273 NFPA 704 fire diamond 200 Lethal dose or concentration LD LC LD50 median dose 1 g kg 1 oral rabbit 3 738 g kg 1 subcutaneous mouse gt 4 g kg 1 dermal rabbit Related compounds Related alkanes BromoformTetrabromomethane1 1 Dibromoethane1 2 Dibromoethane Except where otherwise noted data are given for materials in their standard state at 25 C 77 F 100 kPa Y verify what is Y N Infobox references Contents 1 Preparation 2 Uses 3 Natural occurrence 4 References 5 External linksPreparation editDibromomethane is prepared commercially from dichloromethane via bromochloromethane 6 CH2Cl2 3 Br2 2 Al 6 CH2BrCl 2 AlCl3 CH2Cl2 HBr CH2BrCl HCl The latter route requires aluminium trichloride as a catalyst 2 The bromochloromethane product from either reaction can further react in a similar manner 6 CH2BrCl 3 Br2 2 Al 6 CH2Br2 2 AlCl3 CH2BrCl HBr CH2Br2 HCl In the laboratory it is prepared from bromoform using sodium arsenite and sodium hydroxide 3 CHBr3 Na3AsO3 NaOH CH2Br2 Na3AsO4 NaBr Another way is to prepare it from diiodomethane and bromine Uses editDibromomethane is used as a solvent gauge fluid and in organic synthesis often as 1H NMR internal standard 2 It is a convenient agent for converting catechols to their methylenedioxy derivatives Natural occurrence editIt 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 degradation 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 editPodsiadlo 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 Crystallogr B 62 6 1090 1098 9 doi 10 1107 S0108768106034963 PMID 17108664 Retrieved 2007 06 29 methylene bromide Compound Summary PubChem Compound USA National Center for Biotechnology Information 25 March 2005 Identification Retrieved 18 June 2012 a b Dagani M J Barda H J Benya T J Sanders D C Bromine Compounds Ullmann s Encyclopedia of Industrial Chemistry Weinheim Wiley VCH doi 10 1002 14356007 a04 405 ISBN 978 3527306732 W W Hartman E E Dreger 1929 Methylene bromide Org Synth 9 56 doi 10 15227 orgsyn 009 0056 External links editInternational Chemical Safety Card 0354 Retrieved from https en wikipedia org w index php title Dibromomethane amp oldid 1212518091, wikipedia, wiki, book, books, library,
