2-Butene

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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
Identifiers
CAS number 107-01-7 YesY, 590-18-1 (cis) YesY, 624-64-6 (trans) YesY
ChemSpider 11719 YesY
UNII S1SK37516R YesY
EC-number 203-452-9
ChEBI CHEBI:48363 YesY
RTECS number EM2932000
Jmol-3D images Image 1
Properties
Molecular formula 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 3.7 ºC (cis)[1]
0.9 °C (trans)[2]
Hazards[3]
GHS pictograms Flam. Gas 1Press. Gas
GHS signal word DANGER
GHS hazard statements H220
GHS precautionary statements P210, P377, P381, P403
EU Index 601-012-00-4
EU classification Extremely flammable (F+)
R-phrases R12
S-phrases (S2) S9 S16 S33
NFPA 704
Flammability code 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g., propane Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point −72 °C (−98 °F)[1][2]
Autoignition temperature 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 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-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[edit]

  1. ^ a b c d e Record in the GESTIS Substance Database from the IFA
  2. ^ a b c d e Record in the GESTIS Substance Database from the IFA
  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, SIDS Initial Assessment Report, Geneva: United Nations Environment Programme, February 1995 .
  5. ^ Chemical Safety Information from Intergovernmental Organizations[dead link]

External links[edit]