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Diisobutene (also known as Diisobutylene and Isooctene) refers to a pair of organic compounds with the overall formula C₈H₁₆. The isomers have the same carbon skeleton but differ in the location of the C=C bond. Both are colorless liquids with very similar physical properties. These compounds arise via the acid catalyzed dimerization of isobutene, a reaction that proceeds via the carbocation (CH₃)₃C. The process also leads to some triisobutenes and tetraisobutenes.

Diisobutene isomers
Image			Mixed isomers
Structure	CH2=C(CH3)-CH2C(CH3)3	(CH3)2C=CHC(CH3)3
Systematic name	2,4,4-Trimethyl-1-pentene	2,4,4-Trimethyl-2-pentene	2,4,4-trimethylpentene
CAS number
Density	0.7150 g/mL	0.7218 g/mL	0.717 g/mL
Melting point	-93.5 °C	-106.3 °C	-50 °C
Boiling point	101.4 °C	104.9 °C	102 °C

Applications

Hydrogenation is performed at a significant scale to give isooctane, which is an important fuel additive. Diisobutene is used as precursors to isononylol and octylphenols by hydroformylation/hydrogenation and phenol alkylation, respectively. Both are precursors to plasticizers. The isononylol (3,5,5-trimethyl-hexan-1-ol) is a precursor to 3,5,5-trimethylhexyl acetate, a commercial fragrance. Diisobutenes were once of interest as components for automotive fuels.

See also

• 1-Octene - the corresponding linear alpha-olefin

References

1. Schmidt, Roland; Griesbaum, Karl; Behr, Arno; Biedenkapp, Dieter; Voges, Heinz-Werner; Garbe, Dorothea; Paetz, Christian; Collin, Gerd; Mayer, Dieter; Höke, Hartmut (2014). "Hydrocarbons". Ullmann's Encyclopedia of Industrial Chemistry. pp. 1–74. doi:10.1002/14356007.a13_227.pub3. ISBN 978-3-527-30673-2.
2. Geilen, Frank M.A.; Stochniol, Guido; Peitz, Stephan; Schulte-Koerne, Ekkehard (2014). "Butenes". Ullmann's Encyclopedia of Industrial Chemistry. pp. 1–13. doi:10.1002/14356007.a04_483.pub3. ISBN 978-3-527-30385-4.
3. Panten, Johannes; Surburg, Horst (2015). "Flavors and Fragrances, 2. Aliphatic Compounds". Ullmann's Encyclopedia of Industrial Chemistry. pp. 1–55. doi:10.1002/14356007.t11_t01. ISBN 978-3-527-30673-2.

• Alkenes