[phoenixdustlandfall]

Could someone explain to me why in regular alkenes the trans conformation is more stable but in cyclo it is the cis? The textbook really didn't explain this. This is not a homework question- just a conceptual one. Thank you=)

*I was thinking it may have something to do with equatorial vs axial but I am unclear because the examples in the book do not mention or specify.

[MissPhosgene]

It has to do with strain at the alkene and therefore the rest of the ring. Consider a 180 degree dihedral between trans olefin substituents and the 120 degree sp2 bond angle. When you try to connect the trans substituents together by four atoms, the alkene gets twisted, pi orbitals don't align properly, the four atom linker gets pulled into a disfavored conformation, etc. Not so much of a problem with cis. Do you see why? Try drawing it.

[phoenixdustlandfall]

Thank you I will do that- though I may have to look up some of the terms you used I am only in the first term of o-chem=)

Also, apologies for the typo in my original post. It should have read "the book *does* not mention or specify" no *do. The edit icon is no longer there and I am guessing it has been too long since I posted it to modify.

Thanks again.

[jake.n]

I've attached a picture to help you visualize this concept.  As MissPhogene mentioned, notice how twisted the pi orbital is in the trans isomer (left) compared to the cis (right) one.

[phoenixdustlandfall]

Thank you! that really helped=)