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Skeletal formula of 2-bromobutane
CAS number 78-76-2 YesY
PubChem 6554, 637147 R, 12236140 S
ChemSpider 6306 YesY, 552796 R YesY
EC number 201-140-7
UN number 2339
MeSH 2-bromobutane
RTECS number EJ6228000
Beilstein Reference 505949
Jmol-3D images Image 1
Molecular formula C4H9Br
Molar mass 137.02 g mol−1
Appearance Colourless liquid
Density 1.255 g mL−1
Melting point −112.65 °C; −170.77 °F; 160.50 K
Boiling point 91 °C; 196 °F; 364 K
log P 2.672
Refractive index (nD) 1.437
Std enthalpy of
−156 kJ mol−1
Std enthalpy of
−2.706–−2.704 MJ mol−1
GHS pictograms The flame pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word DANGER
GHS hazard statements H225
GHS precautionary statements P210
EU classification Highly Flammable F
R-phrases R11
S-phrases S16, S24/25
Flash point 21 °C (70 °F; 294 K)
Related compounds
Related alkanes
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

2-Bromobutane is an isomer of 1-bromobutane. Both compounds share the molecular formula C4H9Br. 2-Bromobutane is also known as sec-butyl bromide or methylethylbromomethane. Because it contains bromine, a halogen, it is part of a larger class of compounds known as alkyl halides. It is a colorless liquid with a pleasant odor. Because the carbon atom connected to the bromine is connected to two other carbons the molecule is referred to as a secondary alkyl halide.

2-Bromobutane is relatively stable, but is toxic and flammable. It is prone to undergo an E2 reaction if treated with a strong base, which is a bimolecular elimination which results in an alkene (double bond) product. 2-Bromobutane is an irritant, and harmful if ingested. It can irritate and burn skin and eyes.


  1. ^ "2-bromobutane - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 26 March 2005. Retrieved 17 June 2012.