CAS number 115-11-7 YesY
PubChem 8255
ChemSpider 7957 YesY
EC number 204-066-3
UN number 1055
In Liquefied petroleum gas: 1075
RTECS number UD0890000
Jmol-3D images Image 1
Molecular formula C4H8
Molar mass 56.11 g mol−1
Appearance Colorless gas
Density 0.5879 g/cm3, liquid
Melting point

−140.3 ºC

Boiling point

-6.9 °C, 266 K, 20 °F

Solubility in water Insoluble
GHS pictograms Flam. Gas 1Template:GHS04
GHS signal word DANGER
GHS hazard statements H220
GHS precautionary statements P210, P377, P381, P403
EU Index 601-012-00-4
EU classification Extremely flammable (F+)
R-phrases R12
S-phrases (S2), S9, S16, S33
NFPA 704
NFPA 704.svg
Flash point flammable gas
465 °C (869 ºF)
Explosive limits 1.8–9.6%
Related compounds
Related butenes 1-Butene
Related compounds Isobutane
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Isobutylene (or 2-methylpropene) is a hydrocarbon of significant industrial importance. It is a four-carbon branched alkene (olefin), one of the four isomers of butylene. At standard temperature and pressure it is a colorless flammable gas.



Isobutylene is used as an intermediate in the production of a variety of products. It is reacted with methanol and ethanol in the manufacture of the 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(TPC Group) 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]

See also


  1. ^ The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals (11th ed.), Merck, 1989, ISBN 091191028X , 5024.
  2. ^ a b Isobutene, International Chemical Safety Card 1027, Geneva: International Programme on Chemical Safety, April 2000, 
  3. ^ Olah, George A.; Molnár, Árpád, Hydrocarbon Chemistry, Wiley-Interscience, ISBN 978-0471417828 .

External links

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Look at other dictionaries:

  • isobutylene — [i΄sobyo͞o′tēn΄ī΄sōbyo͞ot′ l ēn΄] n. a colorless, volatile liquid, (CH3) 2C:CH2, obtained from gases in petroleum cracking: it polymerizes readily and is used in making synthetic rubber and resins: also isobutene [i΄sobyo͞o′tēn΄] …   English World dictionary

  • Isobutylène — Méthylpropène Méthylpropène …   Wikipédia en Français

  • isobutylène — ● isobutène ou isobutylène nom masculin Hydrocarbure éthylénique (CH3)2C≅CH2. (Gaz produit lors du craquage du pétrole, l isobutène est employé pour la synthèse de nombreux polymères.) isobutylène [izobytilɛn] n. m. ÉTYM. 1880, Wurtz, Premier… …   Encyclopédie Universelle

  • isobutylene — metilpropenas statusas T sritis chemija formulė CH₂=C(CH₃)₂ atitikmenys: angl. asymmetric dimethylethylene; isobutene; isobutylene; methylpropene rus. изобутен; изобутилен; метилпропен; несимметрический диметилэтилен …   Chemijos terminų aiškinamasis žodynas

  • isobutylene — noun Etymology: International Scientific Vocabulary Date: 1872 a gaseous butylene C4H8 used especially in making butyl rubber and gasoline components …   New Collegiate Dictionary

  • isobutylene — /uy seuh byooht l een /, n. Chem. a colorless, very volatile liquid or flammable gas, C4H8, used chiefly in the manufacture of butyl rubber. Also, isobutene /uy seuh byooh teen/. [1870 75; ISO + BUTYLENE] * * * …   Universalium

  • isobutylene — noun methylpropene; isobutene …   Wiktionary

  • isobutylene — n. colorless and extremely very volatile liquid or combustible gas (used in the production of gasoline components) …   English contemporary dictionary

  • Isobutylene — (C4H8)   An olefinic hydrocarbon recovered from refinery processes or petrochemical processes.   U.S. Dept. of Energy, Energy Information Administration s Energy Glossary …   Energy terms

  • isobutylene — noun Chemistry an easily liquefied hydrocarbon gas used in the making of butyl rubber. [C4H8.] …   English new terms dictionary

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