Ethenolysis

In

olefins are degraded using ethylene (H₂C=CH₂) as the reagent. 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 {A=B}}+{\color {red}{\ce {CH2=CH2}}}\longrightarrow {\ce {A=}}{\color {red}{\ce {CH2}}}+{\ce {B=}}{\color {red}{\ce {CH2}}}

Ethenolysis is a form of methylenation, i.e., the installation of methylene (−CH₂−) groups.

Applications

Using ethenolysis, higher molecular weight internal alkenes can be converted to more valuable terminal alkenes. The

alumina.^[1]

In one application, neohexene, a precursor to perfumes, is prepared by ethenolysis of diisobutene:^[2]

{\overset {\text{diisobutene}}{{\ce {(CH3)3C-CH=C(CH3)2}}}}+{\color {red}{\ce {CH2=CH2}}}\longrightarrow {\overset {\text{neohexane}}{{\ce {(CH3)3C-CH=}}{\color {red}{\ce {CH2}}}}}+{\ce {(CH3)2C=}}{\color {red}{\ce {CH2}}}

α,ω-Dienes, i.e., diolefins of the formula (CH₂)_n(CH=CH₂)₂, are prepared industrially by ethenolysis of cyclic alkenes. For example, 1,5-hexadiene, a useful crosslinking agent and synthetic intermediate, is produced from 1,5-cyclooctadiene: