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

Would a Model Kit help you? Watch How to Use Your Organic Chemistry Model Kit.


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

  2. Devdatta Biswas says

    Amazing! A great help to me !

Speak Your Mind