Converting a bond-line structure to a Newman projection

Challenge 1

Question:

Draw a Newman projection of the following molecule, as viewed from the angle indicated.

Ready? Let’s dive in!

Step 1: Identify the front and back carbon atoms based on the viewer’s angle.

The first thing we need to do is determine which carbon is the front and which is the back, based on the viewing angle given in the question.

We’ll label the front carbon as C1 and the back carbon as C2. Think of it like looking straight down the bond between these two carbons.

Step 2: Identify the three groups connected to the front carbon.

Next, focus on the groups connected to the front carbon (C1). Use the bond-line structure to figure out their orientation:

• Wedges → coming out of the plane, toward you.
• Dashes → going behind the plane, away from you.
• Straight lines → in the plane of the page.

💡 Tip: Don’t forget to add any hidden hydrogens!

In this example, the three groups connected to the front carbon are:

• H (hydrogen) on a dashed line → behind the plane
• Cl (chlorine) on a wedged line → coming out toward you
• CH₃ (methyl group) on a straight line → in the plane of the page

Here’s how we’ll place them in the Newman projection:

1. 1. Start with the group in the plane (CH₃). In the bond-line structure, it’s downward, so in the Newman projection, it’ll point straight down.
   2. The other two groups (H and Cl) must fill the upward positions:

• • • Cl (wedged) → points up and to the right.
    • H (dashed) → points up and to the left.

Now the front carbon is set!

Step 3: Identify the three groups connected to the back carbon.

Now let’s move to the back carbon (C2) and figure out the positions of its groups.

For this example, the groups attached to C2 are:

• CH₃ (methyl group) on a straight line → in the plane of the page
• OH (hydroxyl group) on a dashed line → behind the page
• H (hydrogen) on a wedged line → coming out toward you

We’ll place them following the same steps as before:

1. Start with the group in the plane (CH₃). In the bond-line structure, it’s upward, so in the Newman projection, it’ll point straight up.
2. The other two groups (OH and H) must fill the downward positions:

• • The dashed group (OH) → points down and to the left.
  • The wedged group (H) → points down and to the right.

Step 4: Combine the front and back carbons to form the Newman projection.

Now that we’ve determined the positions of the groups on both the front and back carbons, we can combine them into a complete Newman projection:

Putting it all together, this gives you the complete Newman projection, showing the 3D arrangement of the groups attached to both the front and back carbons.

Challenge 2

Question:

Draw a Newman projection of the following molecule, as viewed from the angle indicated.

We’ll follow the same steps as before!

Step 1: Identify the front and back carbon atoms based on the viewer’s angle.

Just like before, the first thing we need to figure out is which carbon is the front and which is the back, based on the viewing angle in the question. We’ll label the front carbon as C1 and the back carbon as C2.

Step 2: Identify the three groups connected to the front carbon.

Look at the groups attached to the front carbon (C1):

• Br is attached on a straight line → in the plane of the page.
• Two implicit hydrogens aren’t shown in the question but can be assumed:
  • One on a wedge → coming out toward you.
  • One on a dash → going behind the page.

Here’s how we place them in the Newman projection:

1. 1. Start with the group in the plane (Br). It’s downward in the bond-line structure, so in the Newman projection, it points straight down.
   2. The two hydrogens (H and H) will fill the upward positions:
      • The dashed H → points up and to the right.
      • The wedged H → points up and to the left.

The front carbon is now set!

Step 3: Identify the three groups connected to the back carbon.

Next, we look at the groups attached to the back carbon. In this case, they are:

• CH(CH₃)₂ on a straight line → in the plane of the page
• OH on a dashed line → behind the page
• H on a wedged line → coming out toward you

Here’s how we place them in the Newman projection:

1. Start with the group in the plane (CH(CH₃)₂ ). It’s downward in the bond-line structure, so in the Newman projection, it points straight down.
2. The other two groups (OH and H) must fill the upward positions:

• • The dashed group (OH) → points up and to the right.
  • The wedged group (H) → points up and to the left.

Step 4: Combine the front and back carbons to form the Newman projection.

Now that we’ve determined the positions of the groups on both the front and back carbons, we can combine them into a complete Newman projection:

You did it! 🎉

You’ve taken a big step in understanding 3D molecular structures and how to translate wedges, dashes, and straight lines into Newman projections. If you have any questions or want more practice, feel free to reach out—I’m happy to help! Keep up the amazing work, and don’t forget to celebrate your progress! 🚀