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Isobutylene

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Isobutylene
Skeletal formula
Skeletal formula
Space-filling model
Space-filling model
Ball-and-stick model
Names
IUPAC name 2-Methylpropene
Other names Isobutene
γ-Butylene
2-Methylpropylene
Methylpropene
2-Methylprop-2-ene
Identifiers
CAS Number
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.003.697 Edit this at Wikidata
EC Number
  • 204-066-3
PubChem CID
RTECS number
  • UD0890000
UNII
UN number 1055
In Liquefied petroleum gas: 1075
CompTox Dashboard (EPA)
InChI
  • InChI=1S/C4H8/c1-4(2)3/h1H2,2-3H3Key: VQTUBCCKSQIDNK-UHFFFAOYSA-N
  • InChI=1/C4H8/c1-4(2)3/h1H2,2-3H3
SMILES
  • CC(=C)C
Properties
Chemical formula C4H8
Molar mass 56.106 g/mol
Appearance Colorless gas
Density 0.5879 g/cm, liquid
Melting point −140.3 ºC
Boiling point −6.9 °C (19.6 °F; 266.2 K)
Solubility in water Insoluble
Hazards
GHS labelling:
Pictograms Flam. Gas 1Press. Gas
Signal word Danger
Hazard statements H220
Precautionary statements P210, P377, P381, P403
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g. propaneInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1 4 0
Flash point flammable gas
Explosive limits 1.8–9.6%
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). checkY verify (what is  ?) Infobox references
Chemical compound

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.

Uses

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.

Manufacture

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. Key manufacturers of this product are Texas Petrochemicals(TPC Group) and Lyondell in North America.

Safety

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.

See also

References

  1. The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals (11th ed.). Merck. 1989. ISBN 091191028X., 5024.
  2. ^ 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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