2-Butene
| 2-Butene | |
|---|---|
 cis
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 trans
|
 cis
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 trans
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But-2-ene |
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Other names
β-Butylene |
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| Identifiers | |
| CAS number | 107-01-7  , 590-18-1 (cis) , 624-64-6 (trans) |
| ChemSpider | 11719 |
| UNII | S1SK37516R |
| EC-number | 203-452-9 |
| ChEBI | CHEBI:48363 |
| RTECS number | EM2932000 |
| Jmol-3D images | Image 1 |
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| 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 | |
| Boiling point | |
| Hazards[3] | |
| GHS pictograms |  Template:GHS04 |
| 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 |
 4
1
0
|
| Flash point | −72 °C (−98 °F)[1][2] |
| Autoignition temperature |
325 °C (617 °F)[1][2] |
| Related compounds | |
| Related butenes | 1-Butene cis-2-Butene trans-2-Butene Isobutene |
| Related compounds | Butane Butyne |
 (verify) (what is:  / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 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 geometrical 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. 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]). The more elongated trans-molecule which has a tougher job to get its tail free from the liquid has the higher boiling point, the more rounded cis isomer escapes easier, thus having a lower boiling point. 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]
[edit] References
- ^ a b c d e Record in the GESTIS Substance Database from the IFA
- ^ a b c d e Record in the GESTIS Substance Database from the IFA
- ^ cis-2-Butene, International Chemical Safety Card 0397, Geneva: International Programme on Chemical Safety, March 1996, http://www.inchem.org/documents/icsc/icsc/eics0397.htm. trans-2-Butene, International Chemical Safety Card 0398, Geneva: International Programme on Chemical Safety, March 1996, http://www.inchem.org/documents/icsc/icsc/eics0398.htm.
- ^ a b 2-Butene, SIDS Initial Assessment Report, Geneva: United Nations Environment Programme, February 1995, http://www.inchem.org/documents/sids/sids/107017.pdf.
- ^ Chemical Safety Information from Intergovernmental Organizations
