Stabilities of alkenes can be measured by comparing
heats of hydrogenation.
Reaction: C=C + H2 → CH-CH
![Ranking of alkene stability based on enthalpy of hydrogenation](Alkene_stability.png)
Values (in kcal/mol) taken from the NIST Webbook and reflect more current values. To get values in kJ/mol, multiply by 4.19 J/cal.
Ethylene
|
|
Monosubstituted
|
Average ΔH°r: -30
|
![Ethylene](ethylene.png)
|
-32.4
|
Propene
![Propene](propene.png)
|
-29.5
|
|
|
1-Butene
![1-Butene](1butene.png)
|
-30.0
|
|
|
1-pentene
![1-pentene](1pentene.png)
|
-30.0
|
|
|
1-hexene
![1-hexene](1hexene.png)
|
-29.8
|
|
|
3-methyl-1-butene
![3-methyl-1-butene](3methyl1butene.png)
|
-30.1
|
|
|
3,3-dimethyl-1-butene
![3,3-dimethyl-1-butene](33dimethyl1butene.png)
|
-30.0
|
E-disubstituted
|
Average: -27.4
|
Z-disubstituted
|
Average: -28.2
|
E-2-butene
![E-2-butene](E2butene.png)
|
-27.4
|
Z-2-butene
![Z-2-butene](Z2butene.png)
|
-28.3
|
E-2-pentene
![E-2-pentene](E2pentene.png)
|
-27,2
|
Z-2-pentene
![Z-2-pentene](Z2pentene.png)
|
-28.1
|
E-2-hexene
![E-2-hexene](E2hexene.png)
|
-27.7
|
Z-2-hexene
![Z-2-hexene](Z2hexene.png)
|
-28.5
|
E-3-hexene
![E-3-hexene](E3hexene.png)
|
-28.1
|
Z-3-hexene
![Z-3-hexene](Z3hexene.png)
|
-29.0
|
E-4-methyl-2-pentene
![E-4-methyl-2-butene](E4methyl2pentene.png)
|
-27.3
|
Z-4-methyl-2-pentene
![Z-4-methyl-2-butene](Z4methyl2pentene.png)
|
-27.9
|
|
|
Cyclohexene
![cyclohexene](cyclohexene.png)
|
-28.3
|
|
|
Cyclopentene
![cyclopentene](cyclopentene.png)
|
-26.9
|
|
|
Cyclobutene
![cyclobutene](cyclobutene.png)
|
-31.5
|
1,1-Disubstituted
|
Average: -27.9
|
Trisubstituted
|
Average: -26.5
|
2-methylpropene
![2-methylpropene](2methylpropene.png)
|
-28.1
|
2-methyl-2-butene
![2-methyl-2-butene](2methyl2butene.png)
|
-26.6
|
2-methyl-1-butene
![2-methyl-1-butene](2methyl1butene.png)
|
-28.2
|
2-methyl-2-pentene
![2-methyl-2-pentene](2methyl2pentene.png)
|
-26.6
|
2-methyl-1-pentene
![2-methyl-1-pentene](2methyl1pentene.png)
|
-27.8
|
E-3-methyl-2-pentene
![E-3-methyl-2-pentene](E3methyl2pentene.png)
|
-26.3
|
2,3-dimethyl-1-butene
![2,3-dimethyl-1-butene](23dimethyl1butene.png)
|
-27.8
|
Z-3-methyl-2-pentene
![Z-3-methyl-2-pentene](Z3methyl2pentene.png)
|
-26.4
|
2-ethyl-1-butene
![2-ethyl-1-butene](2ethyl1butene.png)
|
-27.6
|
1-methylcyclohexene
![1-methylcyclohexene](1methylcyclohexene.png)
|
-26.6
|
Methylenecyclohexane
![Methylenecyclohexane](CH2cyclohexane.png)
|
-28.5
|
1-methylcyclopentene
![1-methylcyclopentene](1methylcyclopentene.png)
|
-24.0
|
Methylenecyclopentane
![Methylenecyclopentane](CH2cyclopentane.png)
|
-27.7
|
|
|
Tetrasubstituted
|
|
|
|
2,3-dimethyl-2-butene
![2,3-dimethyl-2-butene](23dimethyl2butene.png)
|
-26.3
|
|
|
|