Swap Method for finding R and S Configurations Chirality

swap method for r and s stereochemistryChirality/Stereochemistry Video Series: Video 4
R and S configurations are pretty straight-forward when priority group #4 is conveniently in the back of the molecule. There’s even a quick trick for when group #4 is forward (as taught in this video).

But what happens when priority group #4 is in the plain of the page? Do you treat it as a rear group, forward group?

Many professors will teach you to build a model kit (hint: don’t rely on your model kit) or mentally rotate and redraw the molecule placing group #4 in the back

OUCH! Not only are these methods a waste of time, they introduce too much stress and confusion on exams. My swap method taught below is tricky to learn at first. BUT… once you get it I GUARANTEE you’ll find yourself saving 5, 10, even 15 minutes on your stereochemistry exam questions.

(Watch on YouTube: Swap. Click cc on bottom right for video transcription.)

<– Watch Previous VideoFinding R and S When Group #4 is Forward
–> Watch Next Video: R and S configuration for Lengthy Complex Substituents

This is Video 4 in the Chirality/Stereochemistry Video Series. Click HERE for the entire series.

Ready to test your stereochemistry skills? Try my FREE Chirality/Stereochemistry Practice Quiz and follow along with the Stereochemistry Cheat Sheet


  1. Your videos are very helpful. Plz make video on Meso compounds also.

  2. Devdatta Biswas says:

    Amazing! A great help to me !

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