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'Dienes' are hydrocarbons which contain two double bonds. Dienes are intermediate between alkenes and polyenes.

Contents

Classes

Reactions with dienes

Classes

Dienes can be divided into three classes:
#'Unconjugated dienes' have the double bonds separated by two or more single bonds.
#'Conjugated dienes' have conjugated double bonds separated by one single bond. They are also the most stable.
#'Cumulated dienes' have the double bonds sharing a common atom as in a group of compounds called allenes.

'Classes of Dienes'

1,5-Cyclooctadiene, an unconjugated diene. Notice that each double bond is two carbons away from the other.

Isoprene, also known as 2-methyl-1,3-butadiene, is one of the simplest conjugated dienes.

Propan-1,2-diene, also known as allene, is the simplest cumulated diene.

In organic chemistry a conjugated diene is also a functional group. With a general formula of C_nH_n. a classic organic reaction for the synthesis of dienes is the Whiting reaction.

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.