Editing Butene

{{Short description|Family of chemical compounds}}
{{More citations needed|date=March 2024}}
'''Butene''', also known as '''butylene''', is an [[alkene]] with the formula {{chem2|auto=1|C4H8}}.  The word ''butene'' may refer to any of the individual compounds.  They are colourless gases that are present in [[crude oil]] as a minor constituent in quantities that are too small for viable extraction.  Butene is therefore obtained by [[Fluid catalytic cracking|catalytic cracking]] of long-chain hydrocarbons left during refining of crude oil. Cracking produces a mixture of products, and the butene is extracted from this by [[fractional distillation]].<ref>{{Ullmann|last1=Geilen|first1=Frank M.A.|last2=Stochniol|first2=Guido|last3=Peitz|first3=Stephan|last4=Schulte-Koerne|first4=Ekkehard|title=Butenes|year=2014|doi=10.1002/14356007.a04_483.pub3}}</ref>

Butene can be used as the [[monomer]] for [[polybutene]], but this [[polymer]] is more expensive than alternatives with shorter carbon chains such as [[polypropylene]]. Polybutene is therefore used in more specialized applications.  Butenes are more commonly used to make copolymer (mixed with another monomer such as ethylene).

Butenes are major constituents of [[raffinate]]s, the C4 fractions in oil processing. The raffinates containing butadiene are considered carcinogenic and mutagenic.<ref>[https://www.pcs.com.sg/wp-content/uploads/2017/04/PCS-01001-C4-Raffinate-SDS-Mar-2019-Rev2-PCS-Pte-Ltd.pdf Safety Data Sheet] pcs.com.sg April 2017</ref> They can be used as [[feedstock]]s for further processing (e. g., on [[Alkylation unit|alkylation units]]), or used as industrial fuel. Their mixing into [[liquefied petroleum gas|LPG]] for nonindustrial uses sometimes occurs but is generally prohibited.<ref>{{Cite web|url=https://nasregion.cz/karcinogenni-plyn-na-ceskem-trhu-neni-sdelila-asociace-zjisteni-inspekce-se-nemeni-360261/|title=Karcinogenní plyn na českém trhu není, sdělila asociace. Inspekce zmírnila své zjištění &#124; Náš REGION}}</ref>

==Isomers==
Among the molecules which have the [[chemical formula]] {{chem2|C4H8}} four [[isomers]] are [[alkenes]]. All four of these [[hydrocarbons]] have four [[carbon]] [[atom]]s and one [[double bond]] in their [[molecule]]s, but have different [[chemical structure]]s. The [[IUPAC]] and common names, respectively, of these [[chemical compound]]s are:
{| class="wikitable" style="text-align:center;"
! Common name(s)
! IUPAC name
! Structure
! Skeletal formula
! 3D model
|-
| [[1-butene]], α-butylene
| But-1-ene
| [[Image:1-butene.svg|class=skin-invert|210px]]
| [[Image:1-Butene.svg|class=skin-invert|150px]]
| [[Image:But-1-ene-3D-balls.png|150px]]
|-
| [[cis-2-butene]], ''cis''-β-butylene
| (2''Z'')-but-2-ene
| [[Image:Cis-2-butene.svg|class=skin-invert|170px]]
| [[Image:Cis-but-2-ene-2D-skeletal.png|class=skin-invert|120px]]
| [[Image:Cis-but-2-ene-3D-balls.png|150px]]
|-
| [[trans-2-butene]], ''trans''-β-butylene
| (2''E'')-but-2-ene
| [[Image:Trans-2-butene.svg|class=skin-invert|170px]]
| [[Image:Trans-but-2-ene-2D-skeletal.png|class=skin-invert|120px]]
| [[Image:Trans-but-2-ene-3D-balls.png|150px]]
|-
| [[isobutene]], isobutylene
| 2-methylprop-1-ene
| [[Image:Methylpropene.svg|class=skin-invert|145px]]
| [[Image:Isobutylene.svg|class=skin-invert|100px]]
| [[Image:Isobutylene-3D-balls.png|120px]]
|}

In the chemical structures above, the small blue numbers in the structure images are the numbering of the atoms in the main backbone chain of the molecules. Other organic compounds have the formula C<sub>4</sub>H<sub>8</sub>, namely [[cyclobutane]] and [[methylcyclopropane]], but are not alkenes and do not fall under the name ''butene''. There are also cyclic alkenes with four carbon atoms overall such as [[cyclobutene]] and two isomers of [[methylcyclopropene]], but they do not have the formula C<sub>4</sub>H<sub>8</sub> and are not discussed here.

==See also==
* [[1,3-Butadiene]]

==References==
{{Reflist}}

==External links==
* [https://web.archive.org/web/20070311090600/http://www2.siri.org/msds/f2/clc/clcvz.html MSDS for isobutylene]


{{Alkenes}}
{{GABAAR PAMs}}

{{Authority control}}
[[Category:Alkenes]]
[[Category:Monomers]]
[[Category:GABAA receptor positive allosteric modulators]]