but-2-ene

CAS No. 107-01-7

Formula: C4H8
Basic Info

2-Butene is an acyclic alkene with four carbon atoms. It is the simplest alkene exhibiting cis/trans-isomerism (also known as (E/Z)-isomerism); that is, it exists as two geometric isomers cis-2-butene ((Z)-2-butene) and trans-2-butene ((E)-2-butene).
It is a petrochemical, produced by the catalytic cracking of crude oil or the dimerization of ethylene. Its main uses are in the production of gasoline (petrol) and butadiene, although some 2-butene is also used to produce the solvent butanone via hydration to 2-butanol followed by oxidation.
The two isomers are extremely difficult to separate by distillation because of the proximity of their boiling points (~4 °C for cis and ~1 °C for trans). However, separation is unnecessary in most industrial settings, as both isomers behave similarly in most of the desired reactions. A typical industrial 2-butene mixture is 70% (Z)-2-butene (cis-isomer) and 30% (E)-2-butene (trans-isomer). Butane and 1-butene are common impurities, present at 1% or more in industrial mixtures, which also contain smaller amounts of isobutene, butadiene and butyne.

Formula
C4H8
Molecular Weight
56.1063
Exact Mass
56.0626
LogP
1.5824
PSA
0
Synonyms

butene-2

(2E)-2-Butene

butylene-2

CH3CH=CHCH3

2-Buten

2-BUTYLENE

2-BUTENE

E/Z-2-butene

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Properties
Density
0.636 g/cm3
Boiling Point
1ºC(lit.)
Melting Point
-140ºC(lit.)
Flash Point
<−30 °F
Refractive Index
1.384
Vapor Density
2 (vs air)
Vapor Pressure
2575 mm Hg ( 37.7 °C)
Safety Info
RTECS
EM2932000
Safety Statements
S9; S16; S33
WGK Germany
3
Risk Statements
R12
HS Code
2901232000
RIDADR
UN 1012 2
Hazard Class
2.1
Hazard Codes
Spectrum
NMR Spectrum 1H NMR : Predict
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Mass Spectrum Mass spectrum (electron ionization)
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