Drawing Newman Projections

Now that we understand the differences in energy between the different rotations of a Newman projection, I want to really go in depth on how to draw and interpret a Newman projection. All right, so there is a method to the madness, and it's just a series of steps that I want to teach you. All right, so let's say that you have the following example. This is a very common problem that you could see on your exam. Draw the most energetically favorable noon projection for that five carbon chain down the C two C three bond. Okay, so how do we even begin to approach this? We need to use steps.

So the first thing that I always do is if you're given a condensed structure, which is often the case, you need to convert the problem into a bond line structure. Okay, So what that means is that I want to take this five carbon chain or whatever I'm given and turn it into bond line. So that's the first thing going to do. Five carbons right there. So this is painting.

The second thing I'm gonna do is I'm gonna highlight the bond of interest. What is the bond of interest? What? It's this C two C three. That's your professor telling you that he wants you to focus on a certain bond that's gonna rotate. Okay. Just like when I was talking to ball conformers that you could have, uh, Sigma with s sister s Trans. He's picking out which sigma you're gonna use which signal on you're gonna rotate. And that's gonna be this Sigma bond right there. Because basically what you want to do is you want to go from the second carbon to the third carbon, That's what C two c three means C two C three. All right, now, it could have also been just letting you know. It could have also been this one. Because if you were counting your one from over here, then this would have been your two in your three. Okay, but I'll just go ahead and use this other one. So this is my two. This is my three. Perfect. So I highlighted the bond of interest. You don't need toe unnecessarily, right? The numbers as long as you just know which bond it ISS

then what we wanna do is this part sounds silly. I'm going to redraw this, but I actually want you to do the eyeball thing. I want you to draw an eyeball looking down the length of that bond. Okay, So I want you to draw an eyeball and make it look straight at that carbon. Okay, so pretend that's you, squinting your eyes at it and you're going to try to figure out what is this thing gonna look like if I was looking straight at it?

Now, the way you're going to do that is that you surround on Lee the bond of interest with all implied hydrogen. That means if there's any implied hydrogen on that carbon or on that carbon, I need to add them. Okay, How about the hydrants on that car window? I add those as well. No, because that's not the bond of interest. The bond of interest is only gonna be from 2 to 3. So what that means is that I'm gonna add to h is here, and I'm also gonna add to each is here. Okay, But I'm not gonna add HS anywhere else because that's not the bond of interest.

now we're going to do is we're going to draw a front carbon with three groups in the front and then a back carbon with three groups in the back like I was doing when I told you guys about the way the Newman projection works. So I'm going to say that, for example, the front one is my red carbon and the back one is my blue carbon. Okay, so my red carbon, I would just draw with a little dot okay? And I would draw that. It has three things coming off of it. Okay, You can draw your little triangle thing. Whatever that's called, however you want, you could start with it with a point up. Or you could start with a point down. It doesn't matter as long as the other one is consistent. So basically, what I would say is then Okay, what are the three things that that red carbon is attached to? Well, it seems to be attached to an H on the top and h on the top. And then a ch three at the bottom. That is this ch three right here. Get that, Then I look back at the blue one, the blue one. Imagine that. It's kind of peeking out from behind the red one. So the blue one is gonna be a circle behind. And then I'm gonna draw the three groups that the blue one is on. Okay, that the blue one has. So the blue one has what it seems to have two ages, h and H. And then what else does it have? Well, it has a two carbon chain coming off of it, so that would be what I would. You could just write a ch two ch three. Does that make sense? Okay, another way to write that would have been too, right. E t. Which stands for ethic. Okay, Another way to write ch three would be too right m e, which stands for method. Okay. And there's there's abbreviations for a bunch of these different ones. All right. And your professor might use those more than he actually is. Is the letters

So now that we've drawn that Newman projection, that is a valid Newman projection. That could be right. The only thing is that I don't know if it's the energy state that the professor was asking for because the professor could ask for any energy state. He could ask for anti. He could ask for Gosh, he could ask for eclipse, maybe even something in the middle. So I have to make sure that this is the exact one that he wants. Okay, so then determine which decayed roll angle would correspond. I have to go up here and see what he said. Well, he specifically said, Draw the most energetically favorable. What does energetically favorable mean? Well, I'll just tell you right now, if you see something as this favorable, that's a good thing. That means stable. Okay, so we're looking for the most stable confirmation. What is the most stable confirmation that's gonna be anti remember? Anti is the most stable, so let's go down and see if that's what I drew. And what's the bond angle? The diarrhea angle, by the way for anti 1 80 Let's go down and see if that's what I drew. What I have is a large group in the back. On a large group in the front, they appear to be 180 degrees away from each other. So this would be anti so this would be your right answer. And this would be what would get you the points on the exam. Okay. So even if I drew it wrong, let's say I drew the wrong confirmation at the beginning, you could still rotate it into the right confirmation. The important part is that you're following all these steps.

Draw the most energetic Newman Projection of CH₃CH(C₆H₅)CH₃

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Draw the most stable Newman Projection of CH₃CH₂ CH₂OH through the C2 – C1 bond. 

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