Editing Isoprene (section)

==Industrial production==
Isoprene is most readily available industrially as a byproduct of the thermal [[cracking (chemistry)|cracking]] of [[petroleum naphtha]] or oil, as a side product in the production of [[ethylene]]. Where thermal cracking of oil is less common, isoprene can be produced by dehydrogenation of [[isopentane]].  Isoprene can be synthesized in two steps from [[isobutylene]], starting with its [[ene reaction]] with [[formaldehyde]] to give isopentenol, which can be dehydrated to isoprene:<ref>{{cite book |doi=10.1002/14356007.a14_627 |chapter=Isoprene |title=Ullmann's Encyclopedia of Industrial Chemistry |date=2000 |last1=Weitz |first1=Hans Martin |last2=Loser |first2=Eckhard |isbn=3-527-30673-0 }}</ref> 
[[File:EneIsoprene.svg|thumb|left|400px|Production of isoprene from isobutene via [[ene reaction]].]]

Where cheap [[acetylene]] is produced from coal-derived [[calcium carbide]], it may be combined with [[acetone]] to make 3-methylbutynol which is then hydrogenated and dehydrated to isoprene.<ref>{{Cite web |date=2024-03-25 |title=Isoprene: Properties, Production And Uses |url=https://chemcess.com/isoprene-properties-production-and-uses/ |access-date=2024-11-03 |language=en-US}}</ref>

About 800,000 metric tons are produced annually. About 95% of isoprene production is used to produce cis-1,4-polyisoprene—a [[synthetic rubber|synthetic]] version of [[natural rubber]].<ref name="Ullmann" />

Natural rubber consists mainly of poly-cis-isoprene with a molecular mass of 100,000 to 1,000,000 g/mol. Typically natural rubber contains a few percent of other materials, such as proteins, fatty acids, resins, and inorganic materials. Some natural rubber sources, called [[gutta percha]], are composed of trans-1,4-polyisoprene, a structural [[isomer]] that has similar, but not identical, properties.<ref name=Ullmann />