Converting Fischer Projections to Zig-zag Structures

Converting Fischer projections to Zig-zag structures can seem daunting at first. With a little practice, it gets much easier. A good general approach is to draw the side view of the Fischer projection and then convert it to the Zig-zag structure by rotating every other chiral center.

Take Action

The following Fischer projections are interactive. You can change:

  • Number of Stereocenters
  • Top and Bottom Substituent
  • Substituents on centers


Change the values and work through the example.

Step 1: Fischer Projection - Understanding the Orientation

Observe the initial Fischer projection. In this representation:

  • Horizontal bonds project out of the plane, towards you.
  • Vertical bonds project into the plane, away from you.
  • This specific orientation is crucial for visualizing the molecule's 3D structure.

Use the controls above to change the substituents and number of stereocenters, and observe how the Fischer projection changes.

Step 2: Side View - Visualizing the Extended Conformation

Now, let's translate the Fischer projection into a side view. This view helps us understand the spatial arrangement of the substituents:

  • Substituents on the left in the Fischer projection are in front (towards you) in the side view.
  • Substituents on the right in the Fischer projection are behind (away from you) in the side view.
  • Note that this extended conformation represents a high-energy state and is not typically observed in reality for extended periods.

Observe how the side view corresponds to the Fischer projection you have set using the controls above.

Step 3: Zig-zag Structure - Achieving a Stable Conformation

To obtain a more stable, realistic representation, we transform the side view into a zig-zag structure:

  • Starting from the second stereocenter, rotate every other stereocenter by 180 degrees.
  • This rotation causes the substituents to alternate between being in front and behind, creating the characteristic zig-zag pattern.
  • The zig-zag conformation represents a lower-energy, more favored arrangement.

Observe how the zig-zag structure is generated from the side view, and how it relates back to your initial Fischer projection.