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 materials, i.e., matter in its various forms that contain carbon atoms.Clay ...

, ethenolysis is a chemical process in which internal

olefin In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond. Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, an ...

s are degraded using

ethylene Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon-carbon double bonds). Ethylene i ...

() as the

reagent In chemistry, a reagent ( ) or analytical reagent is a substance or compound added to a system to cause a chemical reaction, or test if one occurs. The terms ''reactant'' and ''reagent'' are often used interchangeably, but reactant specifies a ...

. The reaction is an example of cross metathesis. The utility of the reaction is driven by the low cost of ethylene as a reagent and its selectivity. It produces compounds with terminal alkene functional groups (α-olefins), which are more amenable to other reactions such as polymerization and hydroformylation. The general reaction equation is: :

\ce +  \longrightarrow \ce + \ce

Ethenolysis is a form of methylenation, i.e., the installation of methylene () groups.

Applications

Using ethenolysis, higher molecular weight internal alkenes can be converted to more valuable terminal alkenes. The Shell higher olefin process (SHOP process) uses ethenolysis on an industrial scale. The SHOP α-olefin mixtures are separated by distillation, the higher molecular weight fractions are isomerized by alkaline alumina catalysts in the liquid phase. The resulting internal olefins are reacted with ethylene to regenerate α-olefins. The large excess of ethylene moves the reaction equilibrium to the terminal α-olefins. Catalysts are often prepared from Rhenium(VII) oxide () supported on alumina. In one application, neohexene, a precursor to perfumes, is prepared by ethenolysis of diisobutene: :

\overset +  \longrightarrow \overset +  \ce

α,ω-Dienes, i.e., diolefins of the formula , are prepared industrially by ethenolysis of cyclic alkenes. For example,

1,5-hexadiene 1,5-Hexadiene is the organic compound with the formula (CH)(CH=CH). It is a colorless, volatile liquid. It is used as a crosslinking agent and precursor to a variety of other compounds. Synthesis 1,5-Hexadiene is produced commercially by the eth ...

, a useful crosslinking agent and synthetic intermediate, is produced from 1,5-cyclooctadiene: :

\ce + 2 \longrightarrow  \ce\ce

The catalyst is derived from rhenium(VII) oxide supported on alumina. 1,9-Decadiene, a related species, is produced similarly from cyclooctene. In an application directed at using renewable feedstocks, methyl oleate, derived from natural seed oils, can be converted to

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- ...

and methyl 9- decenoate: :

\ce  +    \longrightarrow \ce  +  \ce{\color{red}\ce{CH2

References

Carbon-carbon bond forming reactions Organometallic chemistry Homogeneous catalysis