Strain energy
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Strain_energy".

In a molecule, strain energy is released when the constituent atoms are allowed to rearrange themselves in a chemical reaction or a change of chemical conformation in a way that:

• angle strain,
• torsional strain,
• ring strain and/or steric strain,
• Allylic strain, and
• pentane interference

are reduced ^[1] .

For example, the heat of combustion of cyclopropane (696 kJ/mol) is higher than that of propane (657 kJ/mol) per methylene unit.

Compounds with unusually large strain energy include tetrahedranes, propellanes, cubanes, fenestranes and cyclophanes.

References

1. ^ March's Advanced Organic Chemistry: Reactions, Mechanisms, and Structure Michael B. Smith, Jerry March Wiley-Interscience, 5th edition, 2001, ISBN 0-471-58589-0