△hydrogenation cumulated terminal diene alkyne =C 1,2-pentadiene 1-pentyne internal alkyne 69.8 2-pentyne kcal isolated K3ou 69.5 diene kcal isolated 65.8 1,4-pentadiene diene kcal trans-1.4-hexadiene conjugated 60.2 diene keal 入◇ 57.4 kcal trans-1,3-pentadiene 53.7 kcal alkane (pentane or hexane) DHhydrogenation