Stereochemistry - A Simple Trick for Determining R and S

Simple trick to figure R and S when number 4 substituent is not in the back.

If you found this video on stereochemistry and determining R and S helpful, MOC members get access to over 1500 quizzes on Stereochemistry and other topics, plus Flashcards, the Reaction Guide, and more. Understand 180+ organic chemistry reactions & mechanisms inside and out, eliminate exam-day surprises, and confidently pass (or ace) your next organic chemistry exam.

Thank you for watching, please don't forget to like and subscribe to our YouTube Channel.

[caryllabja]

thank you sooo much! just saved 4 hours of sleep bc of this vid

[yesha]

Please can you show an example of one where H is in the plane of the pledge. I read your comment below about it, but didn't quite understand.

[steved]

You're saving my chemistry exam, thanks!

[MasterOrganicChem]

Best trick is this: switch H with whatever is in the back ("wedged") then determine R/S. The "true" R/S will be the opposite of that.

[lailasamadi]

You are the best. All ur videos help so much, I dont know how to thank great tutors like you!!

[nicktumsampra]

So so helpful! I wish I'd found your page sooner!

[anizeer]

Literally...very helpful. Thank you is a small word to say.

[duncsv]

dude you're the GOAT, literally made this concept so much easier. Thanks man!

[Anzhela]

Thank This looks so much simpler now that I'm not under pressure to learn this! I'm still retaking my Chem 112 class to hopefully boost my GPA by bettering my Chem grade. I get this now! Yayay! I've struggled with Chem for a year now and am just now breaking through. Whew!

[natopal]

Thank you! But what if H is in the plane of the molecule? Is there like a more general approach to this trick?

[MakeupNFashionDiva]

You deserve a medal seriously amazing!

[MagiRaz]

Man, I missed one day of class to have a wisdom tooth pulled and it gives me hours of trouble. You have saved me.

[kingo]

Please answer whoever know!!

Will this trick work even if the number 4 atom is not wedged but rather on a line ( on the plane of paper?)

Usually i see people use this trick when the number 4 atom is on a wedge but what if it was on a straight planar line?

Thank you in advance!

[abhishekparsi]

What if the H is in the plane of the page?! Plz help I have an exam in 2 days

[mw]

Thank you so much! :) So you can really just redraw the skeleton of the bonds and rotate the substituents around until the lowest priority is in the back? That seems too good to be true lol.

[novaop]

Thank you this helped me a lot, much appreciated!

[emely]

Thank you so much for this! I was confused for hours and now I understand! :)

[rnd]

he already answered to Kaustubh Tandon : Best trick is this: switch H with whatever is in the back ("wedged") then determine R/S. The "true" R/S will be the opposite of that.

[panizshafi]

Omg most useful Ochem video I have so far seen :) great job, thank youuu

[ajaypatha]

Could you please explain why Cl-C bond stayed the same during rotation?