Topics in Organic Chemistry: How to Write Newman Projection and Fischer Projection in Organic Chemistry

Newman projection and Fischer projection formula are the way of writing structure of organic compounds to describe stereochemistry of molecule.

Key words: Newman projection, Fischer projection, Staggered conformer, Eclipsed conformer.

Hi Friends, in this article we will see how to convert Newman projection in to Fischer projection in organic chemistry.

First we will learn about Newman and Fischer projections.

What is Newman projection?

It is a way of writing the structure of molecule which represents conformation of chemical bond. In this structure front carbon is denoted by dot and back side carbon as circle. Newman projection is often used for representation of various conformers of molecule. The lowest energy conformer is known as staggered conformer. And highest energy conformer is called as eclipsed conformer.

What is Fischer Projection?

It is a symbolic method of writing organic molecules. It is developed by German chemist Emil Fischer in 1891. In Fischer projection all the bonds are denoted by horizontal and vertical lines. The carbon chain is shown vertically and first carbon (C-1) is written at the top of the structure. The Fischer projection used to represent three dimensional organic molecules in to two dimensional structures.

Let’s see how to convert Newman projection in to Fischer projection with examples.

Example 1: Consider compound A which is represented by Newman projection formula as shown below;

To convert Newman projection in to Fischer projection formula use following method:

Steps	Structures
Step 1: Covert the staggered conformation in to sawhorse projection.
Step 2: Give number to carbon atoms in longest chain. Then arrange the terminal carbon atoms at the top. For this we need to rotate carbon-2 in clock wise direction. Here C-1 and C-4 are terminal so arrange them at the top left and top right.
Step 3: Now view the molecule from top and write carbon chain vertically. Here the molecule has 4 carbon atoms in chain.
Step 4: Finally, add the substituting groups on left and right side of the vertical carbon chain. This is the Fischer projection of compound A

Example 2: Write the Fischer projection formula of compound B.

Steps	Structures
Step 1: Covert the staggered conformation in to sawhorse projection.
Step 2: Give number to carbon atoms in longest chain. Then arrange the terminal carbon atoms at the top. For this we need to rotate carbon-2 in 180° clock wise direction.
Step 3: Now view the molecule from top and write carbon chain vertically. Here the molecule has 4 carbon atoms in chain.
Step 4: Add the substituting groups on left and right side of the vertical carbon chain. This is the Fischer projection of compound B.

Now we will learn How to convert Fischer projection in to Newman projection.

Example 3: Write the Newman projection formula of compound C.

To convert Fischer projection formula in to Newman projection use following steps:

Steps	Structures
Step 1: Convert Fischer projection into Sawhorse Projection. Here write terminal groups at the top.
Step 2: Rotate the back side carbon in 180 ° clockwise direction.
Step 3: Hide the internal C-C bond and view the molecule from front side to write Newman projection.

Example 4: Write the Newman projection of compound D.

Steps	Structures
Step 1: Convert Fischer projection into Sawhorse Projection. Here write terminal groups at the top. Here both the CH₃ are terminal groups. Write them at the top.
Step 2: Rotate the back side carbon in 180 ° clockwise direction.
Step 3: Hide the internal C-C bond and view the molecule from front side to write Newman projection.