substituents
Activation energies, Ea (kcal/mol)
Enthalpy changes, ΔH (kcal/mol)
Endo
Exo
Endo
Exo
-CH
3
+9.82
+9.25
-38.49
-35.30
-OH
+3.85
+3.31
-40.57
-38.25
-CN
+0.42
+0.55
-42.19
-40.20
-Cl
+4.62
+3.99
-39.81
-37.21
Table 5:
Energetics of the reactions of 4,4-disubstituted cyclobutenones with cyclopentadiene.
