Torsional strain V steric strain

[Evelin Escobedo]

When looking at the perspective formula, sawhorse projection, or Newman projections, how do you determine torsional or steric strain in each case?

Thanks

[ConnieDo3I]

Torsional strain has to do with a force that opposes a molecule's ability to rotate, whereas steric strain has to do with molecules/atoms occupying the same space, causing the charges on the molecules/atoms to interact unfavorably.

Torsional strain appears in eclipsed conformations because charged particles overlap, having a dihedral angle of 0, preventing it from being where the charges won't interact as much and cause as much "strain." You can kind of see where the steric strain is if you draw out the molecule in any way you listen; it typically looks like two molecules/atoms pointing toward each other or facing toward each other.

I apologize if this is kind of confusing, but I think looking at visuals while keeping the definitions of torsional strain and steric strain in mind will help greatly!

Hope this helps!

[SubparChemist]

My TA mentioned there were some interactive models online that can help if you just type "torsional strain interactive models" or "steric strain interactive models," though I haven't tried it.

We had some actual hands on models during discussion that I messed around with and it helped my conceptual understanding a bit, I think this might help you too if you are having the same difficulties I was.