2-Methylpropene
| 2-Methylpropene | |
|---|---|
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| IUPAC name | 2-Methylpropene |
| Other names | Isobutylene Isobutene γ-Butylene 2-Methylpropylene |
| Identifiers | |
| InChI | InChI=1/C4H8/c1-4(2)3/h1H2,2-3H3 |
| InChIKey | VQTUBCCKSQIDNK-UHFFFAOYAW |
| Standard InChI | InChI=1S/C4H8/c1-4(2)3/h1H2,2-3H3 |
| Standard InChIKey | VQTUBCCKSQIDNK-UHFFFAOYSA-N |
| CAS number | [] |
| EC number | |
| UN number | 1055 In Liquefied petroleum gas: 1075 |
| RTECS | UD0890000 |
| ChemSpider | |
| PubChem | |
| SMILES | |
| Properties[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 |
| Hazards[2][3] | |
| EU index number | 601-012-00-4 |
| GHS pictograms |  
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| GHS signal word | DANGER |
| GHS hazard statements | H220 |
| GHS precautionary statements | P210, P377, P381, P403 |
| Flash point | flammable gas |
| Autoignition temp. | 465 °C (869 ºF) |
| Explosive limits | 1.8–9.6% |
| Related compounds | |
| Other butenes | But-1-ene (E)-But-2-ene (Z)-But-2-ene |
| Other compounds | Isobutane |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) | |
2-Methylpropene (or isobutylene) 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
2-Methylpropene 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. 2-Methylpropene 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 2-methylpropene.
Manufacture
2-Methylpropene 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.[4] In the 1990s, the production of 2-methylpropene increased dramatically as the demand for oxygenates such as MTBE grew. Key manufacturers of this product are Texas Petrochemicals and Lyondell in North America.
Safety
2-Methylpropene 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.[3]
See also
References
- ↑ The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals, 11th ed.; Merck, 1989. ISBN 091191028X, 5024.
- ↑ Index no. 601-012-00-4 of Annex VI, Part 3, to Regulation (EC) No 1272/2008 of the European Parliament and of the Council of 16 December 2008 on classification, labelling and packaging of substances and mixtures, amending and repealing Directives 67/548/EEC and 1999/45/EC, and amending Regulation (EC) No 1907/2006. OJEU L353, 31.12.2008, pp 1–1355 at p 450.
- ↑ 3.0 3.1 Isobutene; International Chemical Safety Card 1027; International Labour Organization: Geneva, April 2000, <http://www.inchem.org/documents/icsc/icsc/eics1027.htm>
- ↑ Olah, George A.; Molnár, Árpád Hydrocarbon Chemistry; Wiley-Interscience. ISBN 978-0471417828.
External links
- International Chemical Safety Card 1027
- SIDS Initial Assessment Report for Isobutylene from the Organisation for Economic Co-operation and Development (OECD)
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