Butene


Butene

Butene, also known as butylene, is an alkene with the formula C4H8. It is a colourless gas that is present in crude oil as a minor constituent in quantities that are too small for viable extraction. It is therefore obtained by catalytic cracking of long chain hydrocarbons left during refining of crude oil. Cracking produces a mixture of products and the butene is extracted from this by fractional distillation.

Butene can be used as the monomer for polybutene but this polymer is more expensive than alternatives with shorter carbon chains such as polypropylene. Polybutene is therefore commonly used as a co-polymer (mixed with another polymer, either during or after reaction), such as in hot-melt adhesives.

Isomers

Among the molecules which have the chemical formula C4H8 four isomers are alkenes. All four of these hydrocarbons have four carbon atoms and one double bond in their molecules, but have different chemical structures. The IUPAC and common names, respectively, of these chemical compounds are:


IUPAC name
common name
structure
skeletal formula
3D model
but-1-ene
α-butylene
1-butene.svg
But-1-ene-2D-skeletal.png
But-1-ene-3D-balls.png
cis-2-butene
Z-β-butylene
Cis-2-butene.svg
Cis-but-2-ene-2D-skeletal.png
Cis-but-2-ene-3D-balls.png
trans-2-butene
E-β-butylene
Trans-2-butene.svg
Trans-but-2-ene-2D-skeletal.png
Trans-but-2-ene-3D-balls.png
2-methylpropene
isobutylene
Methylpropene.svg
Isobutylene-2D-skeletal.png
Isobutylene-3D-balls.png

In the chemical structures above, the small blue numbers in the structure images are the numbering of the atoms in the main backbone chain of the molecules. Other organic compounds have the formula C4H8, namely cyclobutane and methylcyclopropane, but are not alkenes and are not discussed here. There are also cyclic alkenes with four carbon atoms overall such as cyclobutene and two isomers of methylcyclopropene, but they do not have the formula C4H8 and are not discussed here.

All four of these isomers are gases at room temperature and pressure, but can be liquefied by lowering the temperature or raising the pressure on them, in a manner similar to pressurised butane. These gases are colourless, but do have distinct odours, and are highly flammable. Although not naturally present in petroleum in high percentages, they can be produced from petrochemicals or by catalytic cracking of petroleum. Although they are stable compounds, the carbon-carbon double bonds make them more reactive than similar alkanes, which are more inert compounds in various ways.

Because of the double bonds, these 4-carbon alkenes can act as monomers in the formation of polymers, as well as having other uses as petrochemical intermediates. They are used in the production of synthetic rubber. But-1-ene is a linear or normal alpha-olefin and isobutylene is a branched alpha-olefin. In a rather low percentage, but-1-ene is used as one of the comonomers, along with other alpha-olefins, in the production of high density polyethylene and linear low density polyethylene. Butyl rubber is made by cationic polymerisation of isobutylene with about 2 - 7% isoprene. Isobutylene is also used for the production of methyl tert-butyl ether (MTBE) and isooctane, both of which improve the combustion of gasoline.

See also

External links


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Look at other dictionaries:

  • Butene — (auch Butylene) sind eine Gruppe von vier isomeren Kohlenwasserstoffen mit der allgemeinen Summenformel C4H8, die über eine C–C Doppelbindung verfügen. Sie zählen damit zu den Alkenen. Zwei der Isomere unterscheiden sich durch cis trans Isomerie …   Deutsch Wikipedia

  • Butene — Butène Le butène (ou butylène) C4H8 est un gaz incolore et sans odeur, deux fois plus lourd que l air, soluble dans les solvants organiques polaires (hydrocarbures). Il s enflamme à 440 °C. Sommaire 1 Isoméres 2 Obtention 3 Utilisations …   Wikipédia en Français

  • butène — [ bytɛn ] n. m. • 1845; du rad. de but(ylique) et suff. chim. ène ♦ Chim. Hydrocarbure éthylénique C4 H8. ⇒vieilli butylène. ● butène nom masculin Hydrocarbure éthylénique, C4H8, dont il existe trois isomères, le butène 1 et les butènes 2 cis et… …   Encyclopédie Universelle

  • Butene — Butene,   Singular Buten das, s, Butylene, ungesättigte Kohlenwasserstoffe aus der Gruppe der Alkene, die sich von den Butanen ableiten. Sie treten meist als Gemisch der drei Isomeren 1 Buten, 2 Buten und Isobuten …   Universal-Lexikon

  • butene — utene n. any of three isomeric singly unsaturated hydrocarbons {C4H8}; all are used in making synthetic rubbers; called also {butylene}. [WordNet 1.5] …   The Collaborative International Dictionary of English

  • butene — [byo͞o′tēn΄] n. BUTYLENE …   English World dictionary

  • Butène — Le butène (ou butylène) C4H8 est un gaz incolore et sans odeur, deux fois plus lourd que l air, soluble dans les solvants organiques polaires (hydrocarbures). Il s enflamme à 440 °C. Sommaire 1 Isomères 2 Obtention 3 Utilisations …   Wikipédia en Français

  • butene — /byooh teen/, n. Chem. butylene (def. 1). [BUT(YL) + ENE] * * * ▪ chemical compound also called  Butylene,         any of four isomeric compounds belonging to the series of olefinic hydrocarbons. The chemical formula is C4H8. The isomeric forms… …   Universalium

  • butene — noun any of three isomeric hydrocarbons C4H8; all used in making synthetic rubbers • Syn: ↑butylene • Hypernyms: ↑gas • Hyponyms: ↑isobutylene, ↑polybutylene, ↑polybutene * * * ˈbyüd.ēn …   Useful english dictionary

  • butene — Butylene Bu ty*lene, n. [From {Butyl}.] 1. (Chem.) Any one of three metameric hydrocarbons, {C4H8}, of the ethylene series. They are gaseous or easily liquefiable; called also {butene}. [1913 Webster] 2. the hypothetical divalent radical { (CH2)4 …   The Collaborative International Dictionary of English