In Liquefied petroleum gas: 1075
|Jmol-3D images||Image 1|
|Molar mass||56.11 g mol−1|
|Density||0.5879 g/cm3, liquid|
|Melting point||−140.3 °C|
|Boiling point||−6.9 °C (19.6 °F; 266.2 K)|
|Solubility in water||Insoluble|
|GHS signal word||DANGER|
|GHS hazard statements||H220|
|GHS precautionary statements||P210, P377, P381, P403|
|EU classification||Extremely flammable (F+)|
|S-phrases||(S2), S9, S16, S33|
|Flash point||flammable gas|
|Autoignition temperature||465 °C (869 °F)|
|Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)|
|(what is: / ?)|
Isobutylene (or 2-methylpropene) is a hydrocarbon of industrial significance. 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.
Occurrence in nature
Isobutylene is a component of natural gas and crude oil found in porous rock formations in the upper strata of some areas of the Earth's crust.
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. In the 1990s, the production of isobutylene increased dramatically as the demand for oxygenates such as MTBE grew.
Isobutylene is a highly flammable gas and presents an explosion danger. Usually stored as a compressed, liquefied gas, if released it may produce an oxygen-deficient atmosphere that presents an asphyxiation hazard.
- The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals (11th ed.), Merck, 1989, ISBN 091191028X, 5024.
- Isobutene, International Chemical Safety Card 1027, Geneva: International Programme on Chemical Safety, April 2000
- Olah, George A.; Molnár, Árpád, Hydrocarbon Chemistry, Wiley-Interscience, ISBN 978-0-471-41782-8.