 Okay, so let's try one of these questions that says draw a ring flip isomer for the following compound and circle the most stable conformation. Indicate which is more stable by calculating the overall energy difference, okay? So the first thing we want to do is what? Draw the isomer. Okay? So draw the isomer. Did y'all do that already? Okay. So did y'all do it? Hopefully. So this methyl group is down where? Is it one or two? This one here? One or two? Two. Two. Right? You see that? Okay. Remember if I'm in equatorial, what is this? Equatorial what? Down. Down. Right? I go to what? I seal down. Right? Equatorial. Equatorial down. So it's going to go to? Equatorial down. Down. Yeah. Equatorial down. Okay. Do we see that? So now we're asked to determine which of these is the higher in energy or the lower in energy, right? Which one's the lower in energy? Okay. Can you tell just straight away or do we need to calculate? We're going to calculate anyways but can anybody tell? The one-three-diaxial one will have less energy because it's less stable. So maybe what we should do instead of guessing is start calculating, okay? So if we can't figure it out by just looking at it, we need to do the calculation, okay? It's a good guess but you're forgetting that that one has one-three-diaxial interactions too, okay? Where is this methyl group? It's in the what position? Axial. Axial, right? Are there hydrogens on the bottom of this ring in the axial position? Yes. Yes, so they're going to have one-three-diaxial interactions, okay? So axial hydrogens down, that's what I'm looking for on this one. Is there one on this carbon? No. Everybody, come on. Is there one on this one? No. No. This one? No. No. This one? Yes. Okay, so let's draw it in. Like that. Okay. One on this one? This one? Yes. Yes. Like that. One on this one? No. Okay, cool. Now let's go over here. Okay? Tell me where the one-three-diaxial is. I'll just point to the carbon so you say yes or no. Yes. Yes. Yes. Okay? And? No. No, right? Okay, so in this structure here, how many one-three-diaxial methyl-to-hydrogen interactions do I have? Two. Two, very good. They're right here and right there. Okay? What about in this structure here? How many do I have? Two. Two. They're right here, right there. Okay? So each one of those is how many K-cals per mole? 0.9. 0.9. So we got 0.9 there. 0.9 there. Okay? Do y'all see any other interactions? There's probably a gauche one there, right? It's all right. There's probably a gauche one since I wrote it up there for you, right? Where is it? What am I looking for? Where's the gauche? It's between these two methyl groups. If you can't see it, you're going to have to look at the Newman projection. Okay? So let's see if I have a look down that bond, right? Hopefully you can see there the 60 degree interaction. Okay? So that 60 degree space between those two methyl groups, that's called the gauche interaction. Okay? So we have one here and that's how many K-cals per mole? 0.9. 0.9. And then we also have one here. Okay? So what's the total energy in K-cals of this one? So how do I do it? Very good. You add them all up, right? 0.9 plus 0.9 is 1.8 plus 0.9 is 2.7. So what's the energy of this one? 2.7 K-cals per mole. Okay? So which one is more stable? They're equivalent, okay? So this is kind of a tricky question. So when we're going to put the arrows, we're going to do like that. Okay? Any questions on that one? The reason I wanted to do this one is to show you both the 1, 3 di-axials and to find that gauche interaction. Okay? Questions on this one? Okay, wonderful. So you're going to need the table to get those values. Don't memorize them. As you saw, you know I needed the table to do on this one. Okay? Kill. So the best way to memorize where the flip. So what I like to do is just say, this kind of is like an envelope, right? And it flips down like that. And this one flips up like that. So you see this? You flip it down? You're a method of groups there. Okay. That's not like the whole thing. It doesn't turn like that. Yeah, that's the way I used to, when I was an undergraduate, I used to be like, I could never always see this thing, you know? So I would always say, well, if that one's there, but when I flip it, it's going to go there, you know? So it's going to go there. That's not what really happens, okay? But it's kind of, yeah, because you're flipping it down. It's a chair flip, you know? It's not a rotation. Okay? Any other questions? Yes? Maybe told if it's a gauche interaction or is that something we have to infer? You got to figure it out? Yeah? 60 degrees. 60 degrees. So you can just look at your Newman projections. We've gone over Newman projections several problems, I think. So any other questions? Okay, wonderful. Good job.