For each of the following pairs of compounds, determine which compound is more stable (you may find it helpful to draw out the chair conformations):
Alright guys. So, for this question what we need to do is figure out which one of these molecules is the more stable. Now, the way we can do that is by converting these first into chairs, so remember, what a chair looks like, right? what we would draw is first you could paste in one chair, right? It's going to look something like this and another one as well, what we're going to show is actually the number of carbons on our cyclohexane here, so this would be 1, 3 and 5, right? And again 1, 3 and 5. Now, find the 1, 3 and 5 on our cycle hex, on our chairs now. Well, one is going to be up here at the top then we're going to have 3 and 5, okay? So for both of these I want you guys to try and draw all these substituents on our chairs remembering that axial and equatorial are going to matter here and we can use up and down to represent system trans to each other. So, for the first one let's just show that we have one methyl here. Now at 3 it needs to be in the same direction, so let's actually show it right here and now at 5 notice that now it needs to be in a different direction, right? It needs to face down. So, at 5 which position is down? what 5 it looks like down is actually going to be equatorial. So, one has two axial and one equatorial. Now, let's take a look at the next one, here what we can show is that one, let's show it facing down, at 3 it needs to be facing down as well, which down is going to be equatorial. Now, I have five again, it needs to be facing down, right? And the down position is equatorial, so notice that we have all of our groups here equatorial, where here only one is equatorial, right? Go cis and trans to each other so we have two axial one equatorial, right? And then all three equatorial, so now let's think about cyclohexanes again, looking at the chairs which do you think is going to be the more stable one? Well, we know that stability has to do with our groups being in the equatorial position, right? Equatorial is favored over axial as far as stability goes, so that would mean that this molecule on the right is going to be the one that's more stable. Alright, so hopefully that makes sense and just let me know if you have any questions.