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 chiral and thus can be obtained as either of two enantiomers designated as (R)-(−)-2-bromobutane and (S)-(+)-2-bromobutane.

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2-Bromobutane

Names
Preferred IUPAC name 2-Bromobutane[1]
Other names sec-Butylbromide
Identifiers
CAS Number	78-76-2 Y
3D model (JSmol)	Interactive image
Beilstein Reference	505949
ChEMBL	ChEMBL156276 Y
ChemSpider	6306 Y 552796 R N
ECHA InfoCard	100.001.037
EC Number	201-140-7
MeSH	2-bromobutane
PubChem CID	6554 637147 R 12236140 S
RTECS number	EJ6228000
UNII	SSI829JO4W Y
UN number	2339
CompTox Dashboard (EPA)	DTXSID7021499
InChI InChI=1S/C4H9Br/c1-3-4(2)5/h4H,3H2,1-2H3 Y Key: UPSXAPQYNGXVBF-UHFFFAOYSA-N Y
SMILES CCC(C)Br
Properties
Chemical formula	C4H9Br
Molar mass	137.020 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
Thermochemistry
Std enthalpy of formation (ΔfH⦵298)	−156 kJ mol−1
Std enthalpy of combustion (ΔcH⦵298)	−2.706–−2.704 MJ mol−1
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H225
Precautionary statements	P210
Flash point	21 °C (70 °F; 294 K)
Related compounds
Related alkanes	n-Propyl bromide 2-Bromopropane tert-Butyl bromide 1-Bromobutane 1-Bromohexane 2-Bromohexane
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

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