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IUPAC name 2-Methylpropene
Other names Isobutene
CAS number 115-11-7
PubChem 8255
EINECS number 204-066-3
InChI InChI=1/C4H8/c1-4(2)3/h1H2,2-3H3
Molecular formula C4H8
Molar mass 56.11 g mol-1
Appearance Colorless gas
Density 0.5879 g/cm3
Boiling point

-6.9 °C, 266 K, 20 °F

Solubility in water Insoluble
Flash point < -10 °C
465 °C
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

Isobutylene is a hydrocarbon of significant industrial importance. It is a four-carbon branched alkene (olefin), one of the the four isomers of butylene. At standard temperature and pressure it is a colorless flammable gas.

Additional recommended knowledge



Isobutylene is used as an intermediate in the production of a variety of products. It is reacted with methanol and ethanol manufacture of gasoline oxygenates methyl tert-butyl ether (MTBE) and ethyl tert-butyl ether (ETBE), respectively. Alkylation with butane produces isooctane, another fuel additive. Isobutylene is also used in the production of methacrolein. Polymerization of isobutylene produces butyl rubber (polyisobutylene). Antioxidants such as butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) are produced by Friedel-Crafts alkylation of phenols using isobutylene.


Isobutylene can be isolated from refinery streams by reaction with sulfuric acid, but the most common industrial method for its production is by catalytic dehydrogenation of isobutane.[3] In the 1990s, the production of isobutylene increased dramatically as the demand for oxygenates such as MTBE grew. Key manufacturers of this product are Texas Petrochemicals and Lyondell in North America.


Isobutylene is a highly flammable gas and presents an explosion danger. Usually stored as a compressed gas, if released it may produce an oxygen-deficient atmosphere that presents an asphyxiation hazard.[2]


  1. ^ Merck Index, 11th Edition, 5024.
  2. ^ a b MSDS for isobutylene
  3. ^ Hydrocarbon Chemistry, George A. Olah and Árpád Molnár, Wiley-Interscience, ISBN 978-0471417828
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Isobutylene". A list of authors is available in Wikipedia.
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