Chirality/Stereochemistry Video Series: Video 5
R and S configurations are found by ranking substituents on a chiral carbon. This is relatively straight-forward when substituents contain 1-3 atoms.
This gets more confusing when the substituents are long, complex, and contain many of the same atoms. This orgo tutorial video shows you how to approach lengthy and complex substituents so that you can quickly and easily determine R and S configurations.
(Watch on YouTube: Substituents. Click cc on bottom right for video transcription.)
Links & Resources Mentioned In This Video:
- Fischer Projection Tutorial Video Series
-
Pencil Trick For Classifying Primary Secondary and Tertiary Carbon Atoms
<– Watch Previous Video: Finding R and S When Group #4 is Forward
–> Watch Next Video: Fischer Projection Chirality
This is Video 5 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.
leah your method of priority assigning in which we have doule aur triple bond in which you simply put 2 or 3 bonds per carbon in a molecule have some problem i mean this is good for some molecules but not for all because i have kind of question in which it’s not applicable by that method
I am not getting the answers sent to my email.
You saved me . really great. Your students should be honor of you .
how to know R and S for bicyclic bridge
SUPERB/………………******
Hey Leah! In one of your practice questions for chirality. Specifically, stereochemistry Part 7, qs d) I still don’t understand what the order of the ranking would be for that molecule. Hope you can help. Thank you!
How do you assign R/S when an epoxide is present? Do lone pairs rank above or below a H?
I love the nuts and bolts of stereo chemistry, pushing all the nonsense to the side and just getting to the heart of it. I re-entered college after 38 years, and I thought I wasn’t going to make it in my O-chem class until another student recommended your videos. I now am able to understand and follow in class, and at times I can be a little ahead. Forever grateful. Thanks so much! Eve
What happened to video #4 when group 4 is in the plane of the page?? Thats the one I have the most trouble with?!
best explanation for reversing the direction when #4 is forward !
Thanks Anna! Glad to help
what if there is a triple bond?
Triple bonds count like 3 carbon atoms, 1 per bond
Hello Leah,
I have a very important question! What if the CH3 would be “fat-lined”, meaning looking straight at us! Would the chirality then turn from R to S like it does when a H is looking directly at us, or does it stay how it is and that rule only applies to H.
Help would be very much needed!
A.B. See the video explaining how to rank when group #4 is forward