Drawing Newman Projections

We use Newman projections to visualize the rotations of conformers. Some are more stable than others. 

Example: Introduction to Drawing Newman Projections

1m

Six Steps to Drawing Newman Projections

Worked Example: Draw the most energetically favorable Newman Projection for CH3CH2CH2CH2CH3 down the C2 – C3 bond.

1. Convert problem into bondline structure

Concept: Step 1

1m
Video Transcript

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. 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 I'm going to do. Five carbons right there, so this is pentane.

Concept: Step 2

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Video Transcript

The second thing I'm going to do is I'm going to highlight the bond of interest. What is the bond of interest? What? It's this, C2-C3. That's your professor telling you that he wants you to focus on a certain bond that's going to rotate.
Just like when I was talking to you about conformers, that you could have sigma with s-cis or s-trans, he's picking out which sigma you're going to use, which sigma bond you're going to rotate and that's going to 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 C2-C3 means, C2-C3.
Now, it could have also been, just letting you know, it could have also been this one because if you were counting your 1 from over here, then this would have been your 2 and your 3. But I'll just go ahead and use this other one. This is my 2. This is my 3. Perfect. So I highlighted the bond of interest. You don't need to necessarily write the numbers as long as you just know what bond it is. 

2. Highlight the bond of interest

3. Draw an eyeball glaring down the length of the bond

Concept: Step 3

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Video Transcript

Then what we want to 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. I want you to draw an eyeball and make it look straight at that carbon, so pretend that's you squinting your eyes at it. And you're going to try to figure out what is this thing going to look like if I was looking straight at it. 

4. Surround only the bond of interest with ALL implied hydrogens

Concept: Step 4

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Video Transcript

Now the way you're going to do that is that you surround only the bond of interest with all implied hydrogens. That means if there's any implied hydrogens on that carbon or on that carbon, I need to add them.
How about the hydrogens on that carbon, do I add those as well? No, because that's not the bond of interest. The bond of interest is only going to be from two to three. What that means is that I'm going to add two H's here and I'm also going to add two H's here. But I'm not going to add H's anywhere else because that's not the bond of interest. 

5. Draw a front carbon with 3 groups in the front and a back carbon with 3 groups in the back

Concept: Step 5

2m
Video Transcript

Now what we're going to do is we're going to draw a front carbon with three groups on the front and then a back carbon with three groups on the back like I was doing when I told you guys about the way 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. So my red carbon I would just draw with a little dot. And I would draw that it has three things coming off of it. You can draw your little triangle thing, whatever that's called, however you want. You can start with it with a point up or you can start with a point down. It doesn't matter as long as the other one is consistent.
Basically, what I would say is then what are the three things that that red carbon is attached to. Well, it seems to be attached to an H on the top, an H on the top and then a CH3 at the bottom. That is this CH3 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 going to be a circle behind and then I'm going to draw the three groups that the blue one is on, that the blue one has
So the blue one seems to have two H's, 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 you could just write as CH2, CH3. Does that make sense? Another way to write that would have been to write Et, which stands for ethyl.
Another way to write CH3 would be to write Me, which stands for methyl. There's abbreviations for a bunch of these different ones. And your professor might use those more than he uses the actual letters. 

6. Determine which dihedral angle would correspond

Concept: Step 6

2m
Video Transcript

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 gauche. 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.
Then determine which dihedral 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 that says favorable, that's a good thing. That means stable. So we're looking for the most stable conformation.
What is the most stable conformation? That's going to be anti. Remember anti is the most stable. Let's go down and see if that's what I drew. And what's the bond angle, the dihedral angle, by the way, for anti? 180. Let's go down and see if that's what I drew.
What I have is a large group in the back and 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. This would be what would get you the points on the exam.
So even if I drew it wrong, let's say I drew the wrong conformation at the beginning, you could still rotate it into the right conformation. The important part is that you're following all these steps. 

Hint: This question asked for the most energetically favorable = most stable. Which conformation is most stable?  

The right answer was anti. You got it. So it turns out this time we drew it correctly on the first try. But there will be other examples where we will have to rotate the Newman Projection into the correct position. 

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

6m

Hint: Not all Newman Projections can form an anti, gauche and eclipsed conformation. If you have no clear large group on one side of the projection, you’ll just be stuck with projections called staggered (not overlapping) and eclipsed (overlapping).

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

3m

Drawing Newman Projections Additional Practice Problems

Conformational analysis is one method to determine which conformers are more stable and compare the transition states that interconvert them. 

a. Draw the exact Newman projection of the molecule below looking down indicated bond.

b. Draw the highest and lowest energy conformations. Assume halogens are smaller than methyl groups.

Watch Solution

Assume a methyl group is larger than a chloro group and draw the lowest energy conformation of 2-chlorohexane as a Newman projection viewed down the C2-C3 bond. Use the alkyl group abbreviations Me, Et, Pr, etc for the alkyl substituents on C2 and C3.

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One possible stereoisomer of 2-bromopentane is pictured below. Assuming that sterically a CH3 is bigger than a Br, provide the following:

a. A sawhorse representation, with C2 in the front and C3 in the back, with the Br on C2 and the CH2CH3 on C3 pointing UP.
b. The Newman projection of the most stable conformer of this molecule with the CH2CH3 on C3 pointing UP on the back carbon.
c. The Newman projection of the least stable conformer of this molecule with the CH2CH3 on C3 pointing UP on the back carbon.
d. The Newman projection having the Br and Ha antiperiplanar.
e. The sawhorse representation of what you drew in d.

Watch Solution

Looking along the C2–C3 bond of 3-isopropyl-2,4-dimethylpentane (shown below), carefully draw the Newman projections of all three staggered conformations. Circle the most stable form.

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Complete the Newman projections for the most and least stable conformations looking along α to β.

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Consider (1R, 3R)-1,3-dimethylcyclohexane. Draw its Newman projection. Paying attention to stereochemistry, draw an acceptable regular 3D structure.

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Provide a structural formula for the compound below. Be sure to identify stereoisomers properly.

Viewing down the C3-C4 bond of 3,4-dimethylhexane, give a sawhorse formula for the highest energy conformation

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Draw the Newman projection through C1-C2 for the least stable conformation of 2-methyl-1-butanol.

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Draw the lowest and the highest energy Newman projections for 2,2- dimethylbutane looking down the C2-C3 bond as shown.

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For the line angle drawing: give the IUPAC name for the compound AND draw the most stable Newman projection, looking down the bond indicated with the thick line. (E.G. the first compound, draw the Newman projection looking down the #1 C. The circle of the Newman projection represents the C facing us.)

Watch Solution

For the line angle drawing: give the IUPAC name for the compound AND draw the most stable Newman projection, looking down the bond indicated with the thick line. (E.G. the first compound, draw the Newman projection looking down the #1 C. The circle of the Newman projection represents the C facing us.)

Watch Solution

For the line angle drawing: give the IUPAC name for the compound AND draw the most stable Newman projection, looking down the bond indicated with the thick line. (E.G. the first compound, draw the Newman projection looking down the #1 C. The circle of the Newman projection represents the C facing us.)

Watch Solution

For the line angle drawing: give the IUPAC name for the compound AND draw the most stable Newman projection, looking down the bond indicated with the thick line. (E.G. the first compound, draw the Newman projection looking down the #1 C. The circle of the Newman projection represents the C facing us.)

Watch Solution

For the line angle drawing: give the IUPAC name for the compound AND draw the most stable Newman projection, looking down the bond indicated with the thick line. (E.G. the first compound, draw the Newman projection looking down the #1 C. The circle of the Newman projection represents the C facing us.)

Watch Solution

Draw the lowest and the highest energy Newman projections for 2,3- dimethylbutane looking down the C2-C3 bond.

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On the template provided, draw the Newman projection for the most stable conformation of the molecule shown. Draw the Newman viewing from Carbon #3 to Carbon #2 (IUPAC numbering). The hydrogen on carbon #3 has been added to get you started.

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Using the numbering from your IUPAC name for the following molecule (ketone group has the priority), find the correct the Newman projection from C3 to C4.

 

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Find the correct Newman projection of Molecule A from C3 to C4.

 

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Draw a Newman projection for the following compound as viewed down the indicated bond.

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Name the following molecule. 

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Provide the Newman projection of the following compound

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