Editing Butene (section)

{{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>