Torsional Strain

[Alexia_Vanegas_1G]

When a molecule's hydrogens are eclipsed, does that imply torsional strain on the bonds? Also, is torsional strain only prominent in planar conformations?

[Jenna Smith 3F]

Yes—torsional strain is a direct result of bonds on adjacent atoms being eclipsed. And yes, it is most prominent in planar conformations, as non planar conformations exist to reduce as much torsional strain as possible. Many non planar conformations can still experience torsional strain, but not nearly as much. Some conformations, like the chair conformation of cyclohexane, experience no torsional strain at all.

[Jonathan_Hu_2C]

When there is torsional strain, we relieve it by rotating the carbon atoms right? Does this completely remove the strain or is there still strain left? If so, how much is left?