[dahy-een, dahy-een]
Dienes or diolefins are hydrocarbons which contain two double bonds. Dienes are intermediate between alkenes and polyenes.


Dienes can be divided into three classes:

  1. Unconjugated dienes have the double bonds separated by two or more single bonds.
  2. Conjugated dienes have conjugated double bonds separated by one single bond. They are also the most stable.
  3. Cumulated dienes have the double bonds sharing a common atom as in a group of compounds called allenes.
  4. Heterodienes have one or more of the unsaturated carbon atoms replaced with a heteroatom.

Classes of Dienes

In organic chemistry a conjugated diene is also a functional group. With a general formula of CnH2n-2. a classic organic reaction for the synthesis of dienes is the Whitening reaction.

1,3-butadiene undergoes 1,2-addition and 1,4-addition.

Reactions with dienes

The 1,3 configuration of double bonds found in 1,3-butadiene (conjugated double bonds) make these types of dienes capable of participating in more reaction types than is the case for molecules with either just a single alkene functional group or with multiple, but non-alternating, alkene groups. One possible reaction for such dienes is the Diels-Alder reaction for example Danishefsky’s diene.

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