Diene

In organic chemistry, a diene (/ˈdaɪiːn/ DY-een); also diolefin, /daɪˈoʊləfɪn/ dy-OH-lə-fin) or alkadiene) is a covalent compound that contains two double bonds, usually among carbon atoms.

[1] They thus contain two alkene units, with the standard prefix di of systematic nomenclature.

Dienes can be divided into three classes, depending on the relative location of the double bonds:[1] According to the Gold Book definition, a "diene" could include one or more heteroatoms which replace unsaturated carbon atoms, giving structures that could more specifically be called heterodienes.

Addition of polar reagents can generate complex architectures:[3] Nonconjugated dienes are substrates for ring-closing metathesis reactions.

These reactions require a metal catalyst:c The position adjacent to a double bond is acidic because the resulting allyl anion is stabilized by resonance.

In some cases they serve as placeholder ligands, being removed during a catalytic cycle.

In some cases, dienes are spectator ligands, remaining coordinated throughout a catalytic cycle and influencing the product distributions.

1,3-butadiene
Structure of various alkadienes (also called dienes or diolefins)
Some dienes: A : 1,2-Propadiene, also known as allene , is the simplest cumulated diene. B : Isoprene , also known as 2-methyl-1,3-butadiene, the precursor to natural rubber. C : 1,3-Butadiene , a precursor to synthetic polymers. D : 1,5-Cyclooctadiene , an unconjugated diene (notice that each double bond is two carbons away from the other). E : Norbornadiene , a strained bicyclic and unconjugated diene. F : Dicyclopentadiene .
C 2 -symmetric diene ligand used in asymmetric catalysis . [ 4 ]