Allyl bromide

Allyl bromide (3-bromopropene) is an organic halide. It is an alkylating agent used in synthesis of polymers, pharmaceuticals,[2] synthetic perfumes[3] and other organic compounds. Physically, allyl bromide is a colorless liquid with an irritating and persistent smell, however, commercial samples are yellow or brown.[4] Allyl bromide is more reactive but more expensive than allyl chloride, and these considerations guide its use.[5]

Allyl bromide
Skeletal formula
Ball-and-stick model
Names
Preferred IUPAC name
3-Bromoprop-1-ene
Other names
Allyl bromide
3-Bromopropene
3-Bromopropylene
3-Bromo-1-propene
Bromoallylene
2-Propenyl bromide
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.003.134
EC Number
  • 203-446-6
RTECS number
  • UC7090000
UNII
UN number 1099
  • InChI=1S/C3H5Br/c1-2-3-4/h2H,1,3H2 checkY
    Key: BHELZAPQIKSEDF-UHFFFAOYSA-N checkY
  • InChI=1/C3H5Br/c1-2-3-4/h2H,1,3H2
    Key: BHELZAPQIKSEDF-UHFFFAOYAI
  • BrCC=C
  • C=CCBr
Properties
C3H5Br
Molar mass 120.977 g·mol−1
Appearance Clear to light yellow liquid
Odor Unpleasant, irritating, pungent
Density 1.398 g/cm3
Melting point −119 °C (−182 °F; 154 K)
Boiling point 71 °C (160 °F; 344 K)
0.38 g/100 g H2O [1]
log P 1.79[1]
Vapor pressure 18.6 kPa
−58.6·10−6 cm3·mol−1[1]
1.4697 (20 °C, 589.2 nm)
Viscosity 0.471 cP[1]
≈1.9 D[1]
Thermochemistry
12.2 kJ·mol−1 (liquid)
45.2 kJ·mol−1 (gas)[1]
32.73 kJ·mol−1[1]
Hazards
GHS labelling:
GHS02: FlammableGHS05: CorrosiveGHS06: ToxicGHS08: Health hazardGHS09: Environmental hazard
Danger
H225, H301, H314, H330, H331, H340, H350, H400
P201, P202, P210, P233, P240, P241, P242, P243, P260, P261, P264, P270, P271, P273, P280, P281, P284, P301+P310, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P308+P313, P310, P311, P320, P321, P330, P363, P370+P378, P391, P403+P233, P403+P235, P405, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamond
3
3
1
Flash point −2 to −1 °C
280 °C (536 °F; 553 K)
Explosive limits 4.3–7.3 %
0.1 ppm[1] (TWA), 0.2 ppm[1] (STEL)
Safety data sheet (SDS) MSDS at Oxford University
Related compounds
Related compounds
 Allyl chloride
Allyl iodide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Preparation

Allyl bromide is produced commercially from allyl alcohol and hydrobromic acid:[5]

CH2=CHCH2OH + HBr → CH2=CHCH2Br + H2O

It can also be prepared by the halogen-exchange reaction between allyl chloride and hydrobromic acid or by the allylic bromination of propene.[5]

Reactions and uses

Electrophilic properties

Allyl bromide is an electrophilic alkylating agent.[4] It reacts with nucleophiles, such as amines, carbanions, alkoxides, etc., to introduce the allyl group:

CH2=CHCH2Br + Nu− → CH2=CHCH2Nu + Br− (Nu− is a nucleophile)

It is used in the synthesis of compounds containing the allyl functionality, such as the pharmaceuticals methohexital, secobarbital and thiamylal.[2]

Preparation of Grignard reagent

Allyl bromide reacts with magnesium metal in dry ether to form allylmagnesium bromide, a Grignard reagent:[6]

CH2=CHCH2Br + Mg → CH2=CHCH2MgBr

References
  1. CRC handbook of chemistry and physics : a ready-reference book of chemical and physical data. William M. Haynes, David R. Lide, Thomas J. Bruno (2016-2017, 97th ed.). Boca Raton, Florida. 2016. ISBN 978-1-4987-5428-6. OCLC 930681942.{{cite book}}: CS1 maint: location missing publisher (link) CS1 maint: others (link)
  2. Yoffe, David; Frim, Ron; Ukeles, Shmuel D.; Dagani, Michael J.; Barda, Henry J.; Benya, Theodore J.; Sanders, David C. (2013-10-09), "Bromine Compounds", in Wiley-VCH Verlag GmbH & Co. KGaA (ed.), Ullmann's Encyclopedia of Industrial Chemistry, Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, pp. 1–31, doi:10.1002/14356007.a04_405.pub2, ISBN 978-3-527-30673-2, retrieved 2022-03-04
  3. PubChem. "Hazardous Substances Data Bank (HSDB) : 622". pubchem.ncbi.nlm.nih.gov. Retrieved 2022-03-04.
  4. Bolton, Roger (2001-04-15), "Allyl Bromide", in John Wiley & Sons, Ltd (ed.), Encyclopedia of Reagents for Organic Synthesis, Chichester, UK: John Wiley & Sons, Ltd, pp. ra045, doi:10.1002/047084289x.ra045, ISBN 978-0-471-93623-7, retrieved 2022-03-04
  5. 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.
  6. "6-Chloro-1-Hexene and 8-Chloro-1-Octene". Organic Syntheses. 76: 221. 1999. doi:10.15227/orgsyn.076.0221.
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