Butene

1-butene

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1-Butene

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Cis-2-butene

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Butene, also known as butylene, refers to a group of alkenes with the chemical formula C₄H₈. It exists in several isomers, including 1-butene, cis-2-butene, trans-2-butene, and isobutene (2-methylpropene). Butenes are colourless gases that are important as feedstocks in the petrochemical industry, particularly in the production of polymers and other chemicals.

Isomers

Butene has four isomers, which differ in the position and geometry of the double bond or the branching of the carbon chain:

• 1-Butene: An alpha-olefin with the double bond between the first and second carbon atoms.
• cis-2-Butene: Features a double bond between the second and third carbon atoms, with the methyl groups on the same side.
• trans-2-Butene: Similar to cis-2-butene but with the methyl groups on opposite sides of the double bond, making it more stable.
• Isobutene (2-methylpropene): A branched isomer with a double bond between the second and third carbon atoms and a methyl group on the second carbon.

Production

Butenes are primarily produced through the cracking of long-chain hydrocarbons in naphtha, gas oil, and natural gas. Steam cracking is a common method, where hydrocarbons are heated in the presence of steam to produce a mixture of alkenes, including butenes. Catalytic cracking is another process used to convert heavy petroleum fractions into lighter, more valuable products like butenes.

Uses

Butenes are versatile compounds used in the synthesis of various chemicals and materials. Major applications include:

• Polymer production: Butenes are key monomers in the production of polybutene and other polymers. For example, 1-butene is polymerized to make polybutene, while isobutene is used to make butyl rubber.
• Alkylate production: Butenes are used in the alkylation process to produce high-octane gasoline components.
• Chemical synthesis: Butenes serve as intermediates in the manufacture of a wide range of chemicals, including butanone, sec-butyl alcohol, and tert-butyl alcohol.

Environmental and Health Aspects

Butenes, like other hydrocarbons, can have environmental and health impacts. They are volatile organic compounds (VOCs) that can contribute to the formation of ground-level ozone and smog. Exposure to butenes can cause respiratory issues and irritation of the eyes and skin. Proper handling and control measures are essential to minimize exposure and environmental release.

See Also

• Alkene
• Petrochemical industry
• Polymer
• Cracking (chemistry)