Axial/Equatorial

[DrRoyal Pains]

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If you have two substituents, I know the structure with the largest/bulkiest group equatorial is the most stable, but would placing them both equatorial be more stable, or would this also lead to torsional strain?

 

[cadat]

it depends whether they are 1,2 or 1,3 substituted.

if they are 1,3 you can put the bulkiest groups both equatorial provided that the compound is cis.

if in 1,3 they are trans, usually bulkier methyl groups, tert-butyl, ethyl groups are given preference for equatorial positions over halogens, hydroxyl groups.

in 1,2 situations, the cis situation forces you to put one substituent equatorial one axial. if they are trans you can put the bulky/nonhydrogen groups both equatorial.

 

[MuskieMan33]

I'm not an expert in Organic chemistry, but from what I know, its different for different situations. Like you said, larger groups on equatorial for sure. But as for stability. Boat, chair, half chair, and twist boat could all be stable, depending on the circumstances. If I'm wrong please feel free to correct me! As I need to get everything hammered out for the DAT too!

 

[DrRoyal Pains]

Boats are a big no-no.

 

[MuskieMan33]

At all times they are a no!? If so, I don't really get the point of learning about them. lol. Unless they only happen in intermediate parts of a rxn, or are only unstable (which could be the case). But I thought It just depended on the circumstances.