What is the Difference Between Fischer Projection and Haworth Projection

The key difference between Fischer projection and Haworth projection is that the Fischer projection shows the open chain structure of organic molecules, whereas the Haworth projection shows the closed-cyclic structure of organic molecules.

Fischer projection and Haworth projection are two ways of showing the molecular structure of organic molecules.

CONTENTS

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

What is Fischer Projection?

Fischer projection is a 2D representation of an organic molecule by projection.  These structures were introduced by Emil Fischer in 1891. This type of projection was useful for the depiction of carbohydrates. Therefore, these structures are mainly used in organic chemistry and biochemistry. However, Fischer projections of non-organic compounds are uncommon because these structures can be confusing with other structures.

When drawing a Fischer projection, we can give all the non-terminal bonds as horizontal or vertical lines. We have to indicate the carbon chain vertically, but we usually do not show the carbon atoms. Therefore, we can represent carbon atoms by the center of crossing lines, as shown in the above image. This makes the orientation of the first carbon atom at the top. On the other hand, the horizontal bonds of the projection show the other bonds between carbon atoms and other atoms in the molecule.

If we are creating a Fischer projection for a monosaccharide (containing more than three carbon atoms), there is no specific orient of the molecule in the space, so all the horizontal bonds at the second carbon position are slanted toward the viewer. Furthermore, rotations of the molecule are required in completing the drawing of the Fischer projection of the molecule.

In most cases, Fischer projection is not the accurate representation of the actual 3D structure of the molecule. Therefore, we can say this is a modified version of the molecule, which is ideally twisted at multiple levels along the backbone of the molecule.

What is Haworth Projection?

Haworth projection is a way of drawing the structure of an organic molecule representing the cyclic structure of monosaccharides in a 3D perspective. We can use this projection to give the structural formula of the molecule. The major areas using this type of projections are biochemistry and chemistry.

This projection was named after the chemist Norman Haworth. The characteristics of a Haworth projection include the use of carbon as the implicit type of atom, the use of hydrogen atoms implicit on the carbon atom, and the use of a thicker line to indicate atoms that are located closer to the observer. In addition, the atoms at the right side of the Fischer projection are given by the groups below the plane of the ring in the Haworth projection.

What is the Difference Between Fischer Projection and Haworth Projection?

Fischer projection is a 2D representation of an organic molecule by projection. Haworth projection is a way of drawing the structure of an organic molecule representing the cyclic structure of monosaccharides in a 3D perspective. The key difference between Fischer projection and Haworth projection is that the Fischer projection shows the open chain structure of organic molecules, whereas the Haworth projection shows the closed-cyclic structure of organic molecules.

The below infographic lists the differences between Fischer projection and Haworth projection in tabular form for side by side comparison.

Summary – Fischer Projection vs Haworth Projection

Fischer projection is a 2D representation of an organic molecule by projection, while Haworth projection is a way of drawing the structure of an organic molecule representing the cyclic structure of monosaccharides in a 3D perspective. The key difference between Fischer projection and Haworth projection is that the Fischer projection shows the open chain structure of organic molecules, whereas the Haworth projection shows the closed-cyclic structure of organic molecules.

Reference:

1. “Fischer Projection.” Chemistry LibreTexts, 24 July 2020.

Image Courtesy:

1. “D-Glyceraldehyde 2D Fischer” By Master Uegly – Own work (Public Domain) via Commons Wikimedia
2. “Haworth projection of α-D- and α-L-Glucopyranose” By Vaccinationist – Own work (Public Domain) via Commons Wikimedia