Final answer:
Dienes are classified based on the proximity of their double bonds: cumulated dienes (adjacent double bonds), conjugated dienes (alternate double and single bonds allowing electron delocalization), and isolated dienes (double bonds separated by two or more single bonds).
Step-by-step explanation:
The three classifications of dienes according to proximity are cumulated dienes, conjugated dienes, and isolated dienes.
- Cumulated dienes have two double bonds that share a common carbon atom, as seen in allenes.
- Conjugated dienes contain two double bonds separated by a single sigma bond, allowing for delocalization of electrons; an example is 1,3-butadiene.
- Isolated dienes feature two double bonds separated by two or more single bonds, which prevents delocalization between the double bonds; an example is 1,5-hexadiene.