1,2-Dibromoethane

1,2-Dibromoethane, also known as ethylene dibromide (EDB), is an organobromine compound with the chemical formula (CH2Br2). Although trace amounts occur naturally in the ocean, where it is formed probably by algae and kelp, it is mainly synthetic. It is a dense colorless liquid with a faint sweet odor, detectable at 10 ppm, is a widely used and sometimes-controversial fumigant.[4] The combustion of 1,2-dibromoethane produces hydrogen bromide gas that is significantly corrosive.[5]

1,2-Dibromoethane
Names
IUPAC name
1,2-Dibromoethane[1]
Other names
  • Ethylene dibromide[1]
  • Ethylene bromide[2]
  • Glycol bromide[2]
Identifiers
3D model (JSmol)
Abbreviations EDB
605266
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.003.132
EC Number
  • 203-444-5
KEGG
MeSH Ethylene+Dibromide
RTECS number
  • KH9275000
UNII
UN number 1605
Properties
C2H4Br2
Molar mass 187.862 g·mol−1
Appearance Colorless liquid
Odor faintly sweet[2]
Density 2.18 g mL−1
Melting point 9.4 to 10.2 °C; 48.8 to 50.3 °F; 282.5 to 283.3 K
Boiling point 129 to 133 °C; 264 to 271 °F; 402 to 406 K
0.4% (20 °C)[2]
log P 2.024
Vapor pressure 1.56 kPa
14 μmol Pa kg−1
1.539
Thermochemistry
134.7 J K−1 mol−1
223.30 J K−1 mol−1
−1.2419–−1.2387 MJ mol−1
Hazards
Main hazards carcinogen[2]
GHS pictograms
GHS Signal word Danger
H301, H311, H315, H319, H331, H335, H350, H411
P261, P273, P280, P301+310, P305+351+338
NFPA 704 (fire diamond)
0
3
0
Flash point 104 °C (219 °F; 377 K)
Lethal dose or concentration (LD, LC):
  • 55.0 mg kg−1 (oral, rabbit)
  • 79.0 mg kg−1 (oral, chicken)
  • 110.0 mg kg−1 (oral, guinea pig)
  • 130.0 mg kg−1 (oral, quail)
  • 300.0 mg kg−1 (dermal, rabbit)
1831 ppm (rat, 30 min)
691 ppm (rat, 1 hr)[3]
200 ppm (rat, 8 hr)
400 ppm (guinea pig, 3 hr)[3]
NIOSH (US health exposure limits):
PEL (Permissible)
TWA 20 ppm C 30 ppm 50 ppm [5-minute maximum peak][2]
REL (Recommended)
Ca TWA 0.045 ppm C 0.13 ppm [15-minute][2]
IDLH (Immediate danger)
Ca [100 ppm][2]
Related compounds
Related alkanes
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Preparation and use

It is produced by the reaction of ethylene gas with bromine,[6] in a classic halogen addition reaction:

CH2=CH2 + Br2 → BrCH2–CH2Br

Historically, 1,2-dibromoethane was used as a component in anti-knock additives in leaded fuels. It reacts with lead residues to generate volatile lead bromides, thereby preventing fouling of the engine with lead deposits.[7]

Pesticide

It has been used as a pesticide in soil and on various crops. The applications were initiated after the forced retirement of 1,2-dibromo-3-chloropropane (DBCP).[4] Most of these uses have been stopped in the U.S. It continues to be used as a fumigant for treatment of logs for termites and beetles, for control of moths in beehives.[8]

Reagent

1,2-Dibromoethane has wider applications in the preparation of other organic compounds including those carrying modified diazocine rings[9] and vinyl bromide that is a precursor to some fire retardants.[4]

In organic synthesis, 1,2-dibromoethane is used as a source of bromine to brominate carbanions and to activate magnesium for certain Grignard reagents. In the latter process, 1,2-dibromoethane reacts with magnesium, producing ethylene and magnesium bromide, and exposes a freshly etched portion of magnesium to the substrate.[10]

Health effects

1,2-Dibromoethane causes changes in the metabolism and severe destruction of living tissues.[5] The known empirical LD50 values for 1,2-dibromoethane are 140 mg kg−1 (oral, rat), and 300.0 mg kg−1 (dermal, rabbit).[5] 1,2-Dibromoethane is a known carcinogen, with pre-1977 exposure levels ranking it as the most carcinogenic substance on the HERP Index.[11]

The effects on people of breathing high levels are not known, but animal studies with short-term exposures to high levels caused depression and collapse, indicating effects on the brain. Changes in the brain and behavior were also seen in young rats whose male parents had breathed 1,2-dibromoethane, and birth defects were observed in the young of animals that were exposed while pregnant.[12] 1,2-Dibromoethane is not known to cause birth defects in humans. Swallowing has caused death at 40 mL doses.[8]

References

  1. "Front Matter". Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 657. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4.
  2. NIOSH Pocket Guide to Chemical Hazards. "#0270". National Institute for Occupational Safety and Health (NIOSH).
  3. "Ethylene dibromide". Immediately Dangerous to Life and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  4. 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.
  5. "Safety Data Sheet for CAS-No.:106-93-4 Ethylene dibromide".
  6. "Preparation and purification of 1,2-dibromoethane" (PDF). Synlett. 28: 49–51. 2017.
  7. Seyferth, D. (2003). "The Rise and Fall of Tetraethyllead. 2". Organometallics. 22 (25): 5154–5178. doi:10.1021/om030621b.
  8. "Toxicological Profile for 1,2-Dibromoethane" (PDF). Archived from the original (PDF) on 2009-11-22. Retrieved 2009-11-22.
  9. [1] Hamada Y., Mukai S. (1996). "Synthesis of ethano-Tröger's base using 1,2-dibromoethane". Tetrahedron Asymmetry. 7: 2671. doi:10.1016/0957-4166(96)00343-6.
  10. Maynard, G. D. (2004). "1,2-Dibromoethane". In L. Paquette (ed.). Encyclopedia of Reagents for Organic Synthesis. New York: J. Wiley & Sons. doi:10.1002/047084289 (inactive 2019-12-02).
  11. "Ranking Possible Cancer Hazards from Rodent Carcinogens" (PDF).
  12. "Toxic Substances Portal – 1,2-Dibromoethane".
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