How to Understand the Merits and Demerits of Different Projections of a Molecule – Part 1

Projection is a two-dimensional (2D) representation of a three-dimensional (3D) organic molecule.


The Fischer projection is a 2D representation of a 3D organic molecule by projection.

The Natta projection (wedge-dash) is a way to project 3D organic molecules with complete stereochemistry in 2D in a skeletal formula.

There are more types of projections, viz., sawhorse projection, Newman projection, & Haworth projection. Each projection in stereochemistry has their own pros and cons.

The following is a synopsis of the comparison between the Fischer and Natta projections of D-Erythrose and D-Threose:



Click/tap to enlarge the image

For example, for the Fischer projection formula for (S)-2-Chlorobutane, a 180º rotation in the plane of the paper (or screen) does not convert the structure to the (R)-enantiomer, but flipping the structure over (a 180º rotation out of the plane), or exchanging the two vertical substituents (i.e., top and bottom), or exchanging the two horizontal substituents (i.e., right and left) does.

NOTE: Post updated since published

Phenomenal projections❓ Let Chemaficionado know in the comments below or at mychemistryhomework@gmail.com❗

References:

(1)    Graham, T. W.; Fryhle, C. B.; Snyder, S. A. Organic Chemistry.; Hoboken, Nj John Wiley Et Sons, Inc, 2016.

(2)    Reusch, W. Virtual Textbook of Organic Chemistry. Msu.edu. https://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/intro1.htm.

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