In organic chemistry, alpha-olefins (or α-olefins) are a family of organic compounds which are alkenes (also known as olefins) with a chemical formula , distinguished by having a double bond at the primary or alpha (α) position.''Petrochemicals in Nontechnical Language'', 3rd Edition, Donald L. Burdick and William L. Leffler, This location of a double bond enhances the reactivity of the compound and makes it useful for a number of applications.

Classification

There are two types of alpha-olefins, branched and linear (or normal). The chemical properties of branched alpha-olefins with a branch at either the second (vinylidene) or the third carbon number are significantly different from the properties of linear alpha-olefins and those with branches on the fourth carbon number and further from the start of the chain. Examples of linear alpha-olefins are propene,

1-butene 1-Butene (or 1-Butylene) is the organic compound with the formula CH3CH2CH=CH2. It is a colorless gas that is easily condensed to give a colorless liquid. It is classified as a linear alpha-olefin. It is one of the isomers of butene (butylene). I ...

and

1-decene Decene is an organic compound with the chemical formula . Decene contains a chain of ten carbon atoms with one double bond, making it an alkene. There are many isomers of decene depending on the position and geometry of the double bond. Dec-1- ...

. An example of a branched alpha-olefin is isobutylene.

Production

A variety of methods are employed for production of alpha-olefins. One class of methods starts with ethylene which is either dimerized or oligomerized. These conversions are respectively effected by the

alphabutol In organic chemistry, hydrovinylation is the formal insertion of an alkene into the C-H bond of ethylene Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and mus ...

process, giving 1-butene, and the Shell Higher Olefin Process which gives a range of alpha-olefins. The former is based on titanium-based catalysts, and the latter relies on nickel-based catalysts. A whole other approach to alpha-olefins, especially long chain derivatives, involves cracking of waxes: :R-CH2-CH2-CH2-CH2-R' -> R-CH=CH2 + CH2=CH-R' + H2 In the Pacol process, linear alkanes are dehydrogenated over a platinum-based catalyst.

Applications

Alpha-olefins are valued building blocks for other industrial chemicals. A major portion of medium or long chain derivatives are converted to

detergent A detergent is a surfactant or a mixture of surfactants with cleansing properties when in dilute solutions. There are a large variety of detergents, a common family being the alkylbenzene sulfonates, which are soap-like compounds that are more ...

s and plasticizers. A common first step in making such products is hydroformylation followed by hydrogenation of the resulting aldehydes. Long chain alpha-olefins are also oligomerized to give medium molecular weight oils that serve a lubricants. Alkylation of benzene with alpha-olefins followed by ring- sulfonation gives linear alkylbenzene sulfonates (LABS) which are biodegradable detergents. Competing often with these petroleum-derived products are derivatives of fatty acids, such as

fatty alcohol Fatty alcohols (or long-chain alcohols) are usually high-molecular-weight, straight-chain primary alcohols, but can also range from as few as 4–6 carbons to as many as 22–26, derived from natural fats and oils. The precise chain length varies ...

s and fatty amines. Low molecular weight alpha-olefins (butenes, hexenes, etc) are used as comonomers, which are incorporated into polyethylene. Some are subjected to olefin metathesis as a route to propylene.

References

Alkenes {{organic-chemistry-stub

Classification

Production

Applications

See also

References