H Resonance Energy wT H Heat of hydrogenation for trans-1, 3 pentadiene is less than expected AH for 1-pentene is 30.0 kcal/mol and for trans-2-pentene is 27.4 kcal/mol, so expect 57. 4 kcal for trans-1, 3-pentadiene Actual AH is 53.7 kcal, so the conjugated diene is more stable Difference, (574-53.7)3.7 kcal/mol, is the esonance energy > Chaper 15Chaper 15 3 Resonance Energy • Heat of hydrogenation for trans-1,3- pentadiene is less than expected. • H for 1-pentene is 30.0 kcal/mol and for trans-2-pentene is 27.4 kcal/mol, so expect 57.4 kcal for trans-1,3-pentadiene. • Actual H is 53.7 kcal, so the conjugated diene is more stable. • Difference, (57.4 – 53.7) 3.7 kcal/mol, is the resonance energy. =>