What is the Difference Between Newman and Sawhorse Projection

The key difference between Newman and Sawhorse projection is that Newman projection is the side-on appearance of a molecule, whereas Sawhorse projection is the angular appearance of a molecule.

The Newman projection and the Sawhorse projection are important in determining the conformations of alkanes. These projections are useful in alkane stereochemistry.

1. Overview and Key Difference
2. What is Newman Projection
3. What is Sawhorse Projection
4. Newman vs Sawhorse Projection in Tabular Form
5. Summary – Newman vs Sawhorse Projection

What is Newman Projection?

Newman projection is the visualization of a chemical bond from front to back, where the atom at the front is shown as a dot, and the atom at the back is shown as a circle. This type of projection is important in the stereochemistry of alkanes. In the Newman projection, we call the carbon atom at the front “proximal carbon” and the carbon atom at the back “distal carbon”.

Newman vs Sawhorse Projection in Tabular Form

Figure 01: A Newman Projection of Butane

A Newman projection is important in determining the dihedral angle of the proximal and distal carbon atoms. We can use this type of projection as an alternative to the Sawhorse projection and Natta projection. The sawhorse projection is described below. The Natta projection is a type of projection that we can use to depict molecules in a complete stereochemistry in 2D skeletal formula.

Newman projection was named after the American chemist Melvin Spencer Newman. He discovered this structure in 1952 as a partial replacement of the Fischer projection. The Fischer projection is unable to give conformational details. Nevertheless, Fischer projection is useful in the depiction of carbohydrates. It appears like a ladder showing chemical bonds and chemical groups at the sides, bottom and top. Moreover, we can use a Newman projection to display any sort of chemical bond, not only single bonds between the carbon atoms of the alkane. For example, we can even use it to study cyclic molecules.

What is Sawhorse Projection?

Sawhorse projection is the display of a molecule from an angle rather than the side-on projection. It is similar to a Newman projection, but this type of projection shows the carbon-carbon bond at the middle of the molecule, unlike a Newman projection. In other words, the C-C bond is hidden in the Newman projection. Moreover, we can draw this projection in the eclipsed or the staggered conformation.

Newman and Sawhorse Projection - Side by Side Comparison

Figure 02: Sawhorse Projection of Butane

A Sawhorse projection is a normal line structure of a molecule that we can draw without showing hydrogens. We can easily convert a Sawhorse projection into a Newman projection by placing the atoms properly.

Similarities Between Newman and Sawhorse Projection

Newman and Sawhorse projections show the structure of an organic molecule.
Both projections are important in getting the conformational details about the molecule.
These projections can display the eclipsed and staggered conformations.

Difference Between Newman and Sawhorse Projection

Newman and Sawhorse projections are important in displaying the conformation of the alkanes. Newman projection is the visualization of a chemical bond from front to back where the atom at the front is shown as a dot and the atom at the back is shown as a circle, while Sawhorse projection is the display of a molecule from an angle rather than the side-on projection. The key difference between Newman and Sawhorse projection is that Newman projection is the side-on appearance of a molecule, whereas Sawhorse projection is the angular appearance of a molecule.

The below infographic lists the differences between Newman and Sawhorse projection in tabular form for side by side comparison

Summary – Newman vs Sawhorse Projection

Newman projection is the visualization of a chemical bond from front to back where the atom at the front is shown as a dot, and the atom at the back is shown as a circle. Sawhorse projection is the display of a molecule from an angle rather than the side-on projection. Therefore, the key difference between Newman and Sawhorse projection is that Newman projection is the side-on appearance of a molecule, whereas Sawhorse projection is the angular appearance of a molecule.

Reference:

1. “Newman projections“. Chemistry LibreTexts. Retrieved October 6, 2021.

Image Courtesy:

1. “Newman projection butane -sc” By Charlesy – Own work, Public Domain) via Commons Wikimedia
2. “Sawhorse projection butane -sc” By Mykhal – (GFDL) via Commons Wikimedia