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In organic chemistry, terminal alkenes (alpha-olefins, α-olefins, or 1-alkenes) are a family of organic compounds which are alkenes (also known as olefins) with a chemical formula C x H 2x, distinguished by having a double bond at the primary, alpha (α), or 1-position. [1]
Straight-chain terminal alkenes, also called linear alpha olefins (LAO) or normal alpha olefins (NAO), are alkenes (olefins) having a chemical formula C n H 2n, distinguished from other alkenes with a similar molecular formula by being terminal alkenes, in which the double bond occurs at the alpha (α-, 1-or primary) position, and by having a linear (unbranched) hydrocarbon chain.
A 3D model of ethylene, the simplest alkene. In organic chemistry, an alkene, or olefin, is a hydrocarbon containing a carbon–carbon double bond. [1] The double bond may be internal or in the terminal position. Terminal alkenes are also known as α-olefins.
In addition to terminal alkenes, tri- and tetrasubstituted alkenes have been used in RCM reactions to afford substituted cyclic olefin products. [32] Ring-closing metathesis has also been used to cyclize rings containing an alkyne to produce a new terminal alkene , or even undergo a second cyclization to form bicycles.
In organic chemistry, hydrovinylation is the formal insertion of an alkene into the C-H bond of ethylene (H 2 C=CH 2): CH 2 =CHR + CH 2 =CH 2 → CH 3 −CHR−CH=CH 2. The more general reaction, hydroalkenylation, is the formal insertion of an alkene into the C-H bond of any terminal alkene. The reaction is catalyzed by metal complexes.
Terminal alkynes, like acetylene itself, are mildly acidic, with pK a values of around 25. They are far more acidic than alkenes and alkanes, which have pK a values of around 40 and 50, respectively. The acidic hydrogen on terminal alkynes can be replaced by a variety of groups resulting in halo-, silyl-, and alkoxoalkynes.
The alkyne zipper reaction is an organic reaction that involves isomerization of a non terminal alkyne into a terminal alkyne. This reaction was first reported by Alexey Favorsky in 1887 (J. Russ. Phys.-Chem. Soc., 19, 414 (1887)).
Metalation of terminal alkynes is a significant side reaction that occurs under these conditions. If metalation is desired, tertiary amine complexes of DIBAL-H are useful. [13] (5) The use of silyl acetylenes avoids the problem of competitive metalation of terminal alkenes.