Resonance Energies of Benzene and Butadiene

The resonance energy of benzene based on an ethane‐ethylene‐like Kekule structure is 74.86 kcal. The similar quantity for butadiene is 17.28 kcal. These quantities are independent of the value of the heat of sublimation of carbon. They are obtained from the heats of atomization of the appropriate molecules or from the heats of hydrogenation of the pertinent related compounds. Both methods yield the same results if properly applied.