Ethenolysis is a chemical process in which internal olefins are degraded using ethylene 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 the selectivity with which it forms compounds containing a terminal alkene functional group (α-olefins). The general reaction equation is:
A=B + CH2=CH2 → A=CH2 + B=CH2Applications
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. Rhenium(VII) oxide on alumina serves as the metathesis catalyst.
In an application directed at using renewable feedstocks, methyl oleate, derived from natural seed oils, can be converted to 1-decene and methyl 9-decenoate:
CH3(CH2)7CH=CH(CH2)7CO2Me + CH2=CH2 → CH3(CH2)7CH=CH2 + MeO2C(CH2)7CH=CH2In another application, natural rubber can be degraded to lower molecular weight polyisoprenes using a Grubbs catalyst.