Benzyl bromide

Benzyl bromide is an organic compound with the formula C6H5CH2Br. The molecule consists of a benzene ring substituted with a bromomethyl group. It is a colorless liquid with lachrymatory properties. The compound is a reagent for introducing benzyl groups.[3][4]

Benzyl bromide[1]
Skeletal structure of the benzyl bromide molecule
3D structure of the benzyl bromide molecule
Names
Preferred IUPAC name
(Bromomethyl)benzene
Other names
α-Bromotoluene
Benzyl bromide
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.002.589
UNII
Properties
C7H7Br
Molar mass 171.037 g·mol−1
Appearance Colorless liquid
Odor Sharp and pungent
Density 1.438 g/cm3
Melting point −3.9 °C (25.0 °F; 269.2 K)
Boiling point 201 °C (394 °F; 474 K)
Solubility organic solvents
log P 2.92[2]
1.5752
Hazards
GHS pictograms
Flash point 70 °C (158 °F; 343 K)
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

Synthesis and structure

Benzyl bromide can be synthesized by the bromination of toluene under conditions suitable for a free radical halogenation:

The structure has been examined by electron diffraction.[5]

Applications

Benzyl bromide is used in organic synthesis for the introduction of the benzyl groups when the less expensive benzyl chloride is insufficiently reactive.[6] [7] Benzylations are often achieved in the presence of catalytic amounts of sodium iodide, which generates the more reactive benzyl iodide in situ.[3] In some cases, benzyl serves as protecting group for alcohols and carboxylic acids.[8]

Safety

Benzyl bromide is a strong lachrymator and is also intensely irritating to skin and mucous membranes. Because of these properties, it has been used in chemical warfare, both in combat and in training due to its irritating yet non-lethal nature.

See also

References
  1. Merck Index (11th ed.). p. 1142.
  2. "Benzyl bromide_msds".
  3. William E. Bauta (2001). "Benzyl Bromide". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rb047. ISBN 0471936235.
  4. "Benzyl bromide". Sigma Aldrich. sigmaaldrich.com. Retrieved 8 June 2017.
  5. Vilkov, L. V.; Sadova, N. I. (March 1976). "Electron diffraction study on the molecular structure of benzyl chloride and benzyl bromide in the vapour phase". Journal of Molecular Structure. 31 (1): 131–142. doi:10.1016/0022-2860(76)80124-X.
  6. Andrew G. Myers, Bryant H. Yang (2000). "Synthesis and Diastereoselective Alkylation of Pseudoephenedrine Amides". Org. Synth. 77: 22. doi:10.15227/orgsyn.077.0022.CS1 maint: uses authors parameter (link)
  7. Harry Heaney, Steven V. Ley (1974). "1-Benzylindole". Org. Synth. 54: 58. doi:10.15227/orgsyn.054.0058.CS1 maint: uses authors parameter (link)
  8. "Benzyl bromide". chemicalbook.com. Retrieved 8 June 2017.
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