A diene is a molecule that has two double bonds. If the molecule is also a hydrocarbon, it is called an alkadiene. When the double bonds are separated from each other by two or more single bonds, they are called isolated double bonds. Isolated double bonds undergo normal alkene reactions, revealing that no interaction occurs between them. If, however, the double bonds are separated by only one single bond, atypical reactions occur. Such an arrangement is called a conjugated double‐bond system. The interaction between the two double bonds in conjugated dienes delocalizes the electron density and increases the stability of the molecule. The simplest conjugated diene is 1,3‐butadiene.