(Z)-but-2-ene

2-Butene
Cis-2-Buten.svg
cis
Trans-2-Buten.svg
trans
Cis-but-2-ene-3D-balls.png
cis
Trans-but-2-ene-3D-balls.png
trans
Names
Preferred IUPAC name
But-2-ene
Other names
β-Butylene
Identifiers
  • 107-01-7 checkY
  • (cis): 590-18-1 checkY
  • (trans): 624-64-6 checkY
3D model (JSmol)
1718755 1361341
ChEBI
ChemSpider
ECHA InfoCard 100.003.140 Edit this at Wikidata
EC Number
  • 203-452-9
25196 1140 1141
RTECS number
  • EM2932000 1718756
UNII
  • InChI=1S/C4H8/c1-3-4-2/h3-4H,1-2H3 checkY
    Key: IAQRGUVFOMOMEM-UHFFFAOYSA-N checkY
  • InChI=1/C4H8/c1-3-4-2/h3-4H,1-2H3
    Key: IAQRGUVFOMOMEM-UHFFFAOYAW
  • (cis): InChI=1S/C4H8/c1-3-4-2/h3-4H,1-2H3/b4-3-
    Key: IAQRGUVFOMOMEM-ARJAWSKDSA-N
  • (trans): InChI=1S/C4H8/c1-3-4-2/h3-4H,1-2H3/b4-3+
    Key: IAQRGUVFOMOMEM-ONEGZZNKSA-N
  • C(=CC)C
  • (cis): C/C=C\C
  • (trans): C/C=C/C
Properties
C4H8
Molar mass 56.106 g/mol
Density 0.641 g/mL (cis, at 3.7 °C)[1]
0.626 g/mL (trans, at 0.9 °C)[2]
Melting point −138.9 °C (−218.0 °F; 134.2 K) (cis)[1]
-105.5 °C (trans)[2]
Boiling point 0.8 to 3.7 °C (33.4 to 38.7 °F; 273.9 to 276.8 K) (Z = 3.7 °C)[1]
(E = 0.8 °C)[2]
  • -42.6·10−6 cm3/mol (cis)
  • -43.3·10−6 cm3/mol (trans)
Hazards[3]
GHS pictograms Flam. Gas 1Press. Gas
GHS Signal word Danger
H220
P210, P377, P381, P403
NFPA 704 (fire diamond)
1
4
0
Flash point −72 °C (−98 °F)[1][2]
325 °C (617 °F; 598 K)[1][2]
Related compounds
Related butenes
1-Butene
cis-2-Butene
trans-2-Butene
Isobutene
Related compounds
Butane
Butyne
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)
Infobox references

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,[4] 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[5]). 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.[4]

References[]

  1. ^ a b c d e Record in the GESTIS Substance Database of the Institute for Occupational Safety and Health
  2. ^ a b c d e Record in the GESTIS Substance Database of the Institute for Occupational Safety and Health
  3. ^ cis-2-Butene, International Chemical Safety Card 0397, Geneva: International Programme on Chemical Safety, March 1996. trans-2-Butene, International Chemical Safety Card 0398, Geneva: International Programme on Chemical Safety, March 1996.
  4. ^ a b 2-Butene (PDF), SIDS Initial Assessment Report, Geneva: United Nations Environment Programme, February 1995.
  5. ^ Chemical Safety Information from Intergovernmental Organizations Archived December 9, 2009, at the Wayback Machine

External links[]