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The Fischer Projection

The Fischer Projection

Drawing of the stereochemistry of a molecule using the Fischer projection

The stereochemistry of a molecule with a single asymmetric carbon can simply be illustrated with perspective formulas (flying wedge formulas). However, this mode of illustration becomes rather labor-intensive and complicated if a molecule contains several chirality centers. The German chemist Emil Fischer therefore introduced a simpler method of drawing such molecules in 1891. This is based on the projection of the tetrahedral chirality centers onto a plane. Today, the Fischer projection, which still provides a standard method for the illustration of the stereochemistry of molecules with several asymmetric carbons, is particularly used for carbohydrates and amino acids.

In a Fischer projection (5) the two bonds of each asymmetric carbon that are drawn with unbroken vertical lines point to the rear of the plane. The remaining two bonds that are drawn with unbroken horizontal lines point to the viewer (1,2,4) in front of the plane. The asymmetric carbon lies on the intersection of the vertical and horiontal bonds. This carbon is not specially drawn (5). The Fischer projection comes in useful particularly for molecules in which several asymmetric carbons are continuously combined into a chain, such as carbohydrates done with. This chain, normally the longest of the molecule, is arranged in the overall eclipsed conformation, which is then vertically aligned in the plane.Try to align the interactive molecular model (3) with your mouse, so that you can see the Fischer projection. Or have it shown automatically.

Fischer projection
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