Strain Energy for Alkanes |
||
|---|---|---|
| Interaction / Compound | kJ/mol | kcal/mol |
| H : H eclipsing | 4.0 | 1.0 |
| H : CH3 eclipsing | 5.8 | 1.4 |
| CH3 : CH3 eclipsing | 11.0 | 2.6 |
| gauche butane | 3.8 | 0.9 |
| cyclopropane | 115 | 27.5 |
| cyclobutane | 110 | 26.3 |
| cyclopentane | 26.0 | 6.2 |
| cycloheptane | 26.2 | 6.3 |
| cyclooctane | 40.5 | 9.7 |
Axial Strain Energies for Monosubstituted Cyclohexanesa,bThis table gives the sum of the values for the 1,3 diaxial interactions of the substituent with two hydrogen atoms. |
||
|---|---|---|
| Substituent(solvent) | kJ/mol | kcal/mol |
| -CH3 | 7.3 | 1.7 |
| -CH2CH3 | 7.5 | 1.8 |
| -CH(CH3)2 | 9.2 | 2.2 |
| -C(CH3)3 | 20 | 4.8 |
| phenyl | 11.7 | 2.8 |
| cyclohexyl | 9.2 | 2.2 |
| -CH=CH2 | 6.2 | 1.5 |
| -CCH, ethynyl | 2.1 | 0.5 |
| -CHO | 3.0 | 0.7 |
| -COCH3 | 5.1 | 1.2 |
| -CO2H | 5.9 | 1.4 |
| -CO2CH2CH3 | 5.0 | 1.2 |
| -Cl | 2.5 | 0.6 |
| -Br | 2.5 | 0.6 |
| -CN, cyano | 0.8 | 0.2 |
| -OH (cyclohexane) | 2.5 | 0.6 |
| -OH (isopropanol) | 4.0 | 1.0 |
| -OCH3 | 2.5 | 0.6 |
| -NH2 (toluene) | 5.2 | 1.2 |
| -NH2 (CH3OCH2CH2OH/H2O) | 7.1 | 1.7 |
| -NO2 | 4.8 | 1.1 |
a. Energy difference between axial and equatorial conformers.
b. Solvent specified when the increment is solvent dependent.
Data from Stereochemistry of Organic Compounds, E. L. Eliel and S. H. Wilen, John Wiley, New York, NY, 1994.