[NewtoAtoms]

Hello my dear Chemistry friends,

According to my textbook when comparing cyclopropane and cyclopentane, cyclopropane has more angle strain (which I understand) however cyclopentane has greater torsional strain.

Can anyone tell me why?

Thank you!!

New to Organic Chem

[ArchStanton]

Are you sure? I reckon torsional strain in a cyclopropanee has uber torsional strain compared to a cyclopropane!!!! I am ready to be proved wrong tho!! Great question!

[Ak]

well what i know is that planar cyclopentane has no angle strain and a lot of torsional strain...however it usually has a more stable conformation when it is puckered...so 4 carbons are on a plane and the 5th is slightly bent and relieves a lot of torsional strain but adds angle strain...so id have to agree with ArchStanton...im pretty sure cyclopropane has greater torsional strain...

also the total strain on cyclopentane is 26 kj/mol and it is nearly strain free...dont know wut cyclopropane is though

[sjb]

I think torsional strain here is related to dihedral angles and the like, so cyclopropane has none, because it's impossible to place 3 points such that they are not in one plane. However, the puckering of cyclopentane increases the torsional strain relative to the flat structure.

Nothing to do with eclipsing conformations per se as far as I know.