Dienophile
Activation Energy, kcal/mol
Reaction Energy, kcal/mol
Ethylene
+15.29
-55.18
Maleic anhydride
+2.18
-53.12
Cyclobutenone
+7.45
-56.15
Table 1:
Energetics of the Diels-Alder reactions of ethylene, maleic anhydride and cyclobutenone with 1,3-butadiene.