organic chemistry Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic matter, organic materials, i.e., matter in its various forms that contain ...

, terminal alkenes (alpha-olefins, α-olefins, or 1-alkenes) are a family of

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

s which are

alkenes In organic chemistry, an alkene, or olefin, is a hydrocarbon containing a carbon–carbon double bond. The double bond may be internal or at the terminal position. Terminal alkenes are also known as Alpha-olefin, α-olefins. The Internationa ...

(also known as olefins) with a

chemical formula A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as pare ...

, distinguished by having a

double bond In chemistry, a double bond is a covalent bond between two atoms involving four bonding electrons as opposed to two in a single bond. Double bonds occur most commonly between two carbon atoms, for example in alkenes. Many double bonds exist betw ...

at the primary, alpha (α), or 1- 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 In mathematics, the term ''linear'' is used in two distinct senses for two different properties: * linearity of a '' function'' (or '' mapping''); * linearity of a '' polynomial''. An example of a linear function is the function defined by f(x) ...

(or normal). The chemical properties of branched alpha-olefins with a branch at either the second (vinylidene) or the third

carbon Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 ...

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 Propylene, also known as propene, is an unsaturated organic compound with the chemical formula . It has one double bond, and is the second simplest member of the alkene class of hydrocarbons. It is a colorless gas with a faint petroleum-like od ...

, but-1-ene and dec-1-ene. An example of a branched alpha-olefin is

isobutylene Isobutylene (or 2-methylpropene) is a hydrocarbon with the chemical formula . It is a four-carbon branched alkene (olefin), one of the four isomers of butylene. It is a colorless flammable gas, and is of considerable industrial value. Product ...

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 process, giving 1-butene, and the

Shell higher olefin process The Shell higher olefin process (SHOP) is a chemical process for the production of linear alpha olefins via ethylene oligomerization and olefin metathesis invented and exploited by Shell plc.''Industrial Organic Chemistry'', Klaus Weissermel, Hans ...

which gives a range of alpha-olefins. The former is based on

titanium Titanium is a chemical element; it has symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resistant to corrosion in ...

-based catalysts, and the latter relies on nickel-based

catalyst Catalysis () is the increase in rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quick ...

s. A whole other approach to alpha-olefins, especially long chain derivatives, involves cracking of

wax Waxes are a diverse class of organic compounds that are lipophilic, malleable solids near ambient temperatures. They include higher alkanes and lipids, typically with melting points above about 40 °C (104 °F), melting to give lo ...

es: : In the PACOL process (paraffin conversion to olefins), 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 Cleanliness, cleansing properties when in Concentration, dilute Solution (chemistry), solutions. There are a large variety of detergents. A common family is the alkylbenzene sulfonate ...

s and

plasticizer A plasticizer ( UK: plasticiser) is a substance that is added to a material to make it softer and more flexible, to increase its plasticity, to decrease its viscosity, and/or to decrease friction during its handling in manufacture. Plasticizer ...

s. A common first step in making such products is

hydroformylation In organic chemistry, hydroformylation, also known as oxo synthesis or oxo process, is an industrial process for the production of aldehydes () from alkenes (). This chemical reaction entails the net addition of a formyl group () and a hydrogen ...

followed by hydrogenation of the resulting

aldehyde In organic chemistry, an aldehyde () (lat. ''al''cohol ''dehyd''rogenatum, dehydrogenated alcohol) is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred ...

s. Long chain alpha-olefins are also oligomerized to give medium molecular weight oils that serve as lubricants. Alkylation of benzene with alpha-olefins followed by ring-

sulfonation In organic chemistry, aromatic sulfonation is a reaction in which a hydrogen atom on an arene is replaced by a sulfonic acid () group. Together with nitration and chlorination, aromatic sulfonation is a widely used electrophilic aromatic substi ...

gives

linear alkylbenzene sulfonate Alkylbenzene sulfonates are a class of anionic surfactants, consisting of a hydrophilic sulfonate head-group and a hydrophobic alkylbenzene tail-group. Along with sodium laureth sulfate, they are one of the oldest and most widely used synthetic ...

s (LABS) which are biodegradable detergents. Competing often with these petroleum-derived products are derivatives of

fatty acid In chemistry, in particular in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated and unsaturated compounds#Organic chemistry, saturated or unsaturated. Most naturally occurring fatty acids have an ...

s, such as

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

s and fatty amines. Low molecular weight alpha-olefins (butenes, hexenes, etc.) are used as

comonomer In polymer chemistry, a comonomer refers to a polymerizable precursor to a copolymer aside from the principal monomer. In some cases, only small amounts of a comonomer are employed, in other cases substantial amounts of comonomers are used. Furt ...

s, which are incorporated into

polyethylene Polyethylene or polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most commonly produced plastic. It is a polymer, primarily used for packaging (plastic bags, plastic films, geomembranes and containers including bott ...

. Some are subjected to

olefin metathesis In organic chemistry, Olefin Metathesis or Alkene Metathesis is an organic reaction that entails the redistribution of fragments of alkenes (olefins) by the Bond cleavage, scission and regeneration of carbon-carbon double bonds. Because of the ...

as a route to

propylene Propylene, also known as propene, is an unsaturated organic compound with the chemical formula . It has one double bond, and is the second simplest member of the alkene class of hydrocarbons. It is a colorless gas with a faint petroleum-like o ...

References

{{reflist Alkenes

Classification

Production

Applications

See also

References