Question

Can a trans cyclohexane be in a boat conformation or are those two ideas mutually exclusive?

Answer 1

Well, from what I know, a boat conformation, a twisted boat conformation, are less stable because they have eclipsing interactions, and a chair form is the most stable probably due to like bond angles and the fact that the previous aspects are minimized to a degree.

Answer 2

Isn't a twisted boat conformation just a chair conformation? And how do those ideas relate to cis-trans isomerism?

Answer 3

I guess we would have to take a look at this for ourselves. the boat and twisted boat conformations are in a higher energy than the chair form, yes that's true they are all technically the same compound compound, just different orientations I guess. and have angle strain and general strain due to sterics. so I guess you would have to work these out. When I learned this, we never talked about the twisted boat and boat conformations much. probably because of the reasons stated above.

Answer 4

usually molecules spend more time in conformations that are more stable and minimize things like ring strain. you've got things like eclipsing and ring strain in the boat form too. the larger the groups the less likely you'll have the boat conformation more likely you'll have the chair form.

Answer 5

I guess I meant to ask if all boat conformations are cis and all chair conformations are trans?

Answer 6

@sabribri it depends on your starting molecule

if a molecule is cis that means both groups relative to each other are either both dashes or wedges, or in other words both groups are either facing towards you or away from you.

In a trans molecule one substituent is facing towards you the other away from you. so they are opposite one is a dash the other is a wedge. or the other way.



We can translate both these figures to a chair and twisted boat conformation if this properly answers your question. so we can have chair forms that are cis or trans, same thing with the twisted boat conforamation. the idea however is the type of groups that you have at these positions and or how large they are. this is important because large bulky groups may interact with other groups on your molecule, especially depending on what carbon they are and in what position.

If a molecule can adopt a more stable conformation than it will do so.

but the idea is that the most stable structure, which is the chair form, will predominate because it minimizes steric and eclipising reactions. that's not to say that chair forms don't have steric interactions but they are less than the ones encountered in the boat and twisted boat conformations.