Conjugated dienes

A conjugated diene, such as 1,3-butadiene, has p orbitals located on at least three adjacent atoms, and is more stable than an unconjugated diene, such as 1,4-pentadiene, because its alternating single and double bonds create a partial double-bond character as a result of resonance. Although 1,4-pentadiene has 2 double bonds, these double bonds are separated by more than one σ bond, making them too far apart to be conjugated and stabilized via resonance.