Cahn-Ingold-Prelog system for naming enantiomers | Organic chemistry | Khan Academy

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Cahn-Ingold-Prelog System for Naming Enantiomers. Created by Sal Khan.
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Organic Chemistry on Khan Academy: Carbon can form covalent bonds with itself and other elements to create a mind-boggling array of structures. In organic chemistry, we will learn about the reactions chemists use to synthesize crazy carbon based structures, as well as the analytical methods to characterize them. We will also think about how those reactions are occurring on a molecular level with reaction mechanisms. Simply put, organic chemistry is like building with molecular Legos. Let's make some beautiful organic molecules!
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Опубликовано:

26 июл 2010

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Комментарии : 95

@yeedoh 8 лет назад

"But its a different Cahn, its not me.." lol

@panmaru101 13 лет назад

You know what i like about you? you don't assume your students know everything. Where you noted the reason its 1-Bromo-1-Floroethane and not 1-Floro-1-Bromoethane, my Ochem professor would have just named the molecule and if you didnt know why then it just leaves the students confused. Everything is explained as you go when you teach. Its a great way to teach, I really appreciate it.

@oyeludejomiloju704 Год назад

My professor would have done the same. Like, just explain why.

@khanacademy 14 лет назад

@prolarka We're rotating 1/3 of the way around a circle so it would be 360/3 or 120 degrees.

@NiallBucks 9 лет назад

So is Sal a robot or how is he so good at everything?!

@saddamali666 9 лет назад

represent atk. that guy too

@sameerakkad2120 10 лет назад

you have no idea how much you've helped me, thanks a million khan :)

@jrbertot2010 10 лет назад

thank you the visualization clicked! helpful!

@aviramwolfstein4443 Год назад

As always, thank you khan.

@chrismartin1985 12 лет назад

I think your tagline should be "Khan Academy: Better (and cheaper) than any MCAT prep course out there!"

@darraghh6384 11 лет назад

this video is so well explained; good advice on how to reorient the molecule as well, which is the most difficult part.

@sirleeeros7583 10 лет назад

WOW!!! Thanks a lot Khan, you are of a good help

@F0A0Y0N0U0S 13 лет назад

@unknwn2312 Remember to think of these molecules as "tripods." It really helps when it comes to understanding the rotations. In this particular case think of the Bromine as the spot where the camera goes and the rest of the groups as the legs. No matter how many degrees you rotate the molecule the Bromine will always be on top. If you have a tripod get it out and give it a try.

@TomNEEG 11 лет назад

You've been a great help

@zahraaanas174 8 лет назад

thanks alot ,you explain the lessons very well , thanks from my heart❤

@muskankapoor5085 5 лет назад

thank you, this really helped

@Zay658 9 лет назад

THANK GOD for sal

@minivaans 9 лет назад

Omg, I should've watched this before before my midterm ): Thank you so much!!!

@tomaa_sh 9 лет назад

Thanks really very beneficial videos

@Melthornal 14 лет назад

Sweet video. Also, on a semi-related note, I believe the negative meaning of Sinister comes from Hebrew. In ancient Hebrew culture the left hand was a symbol of personal power and authority, which many leaders didn't like for obvious reasons. This meaning eventually traveled around the ancient world and went from a symbol of power to a symbol used to mock or otherwise threaten those in power. Christianity came along and associated it with disbelievers in God and His authority.

@canaliscarpi 13 лет назад

Really good video, you obviously have talent for explaining, you helped me a lot for my future exam, thanks for that.

@gunner199312 9 лет назад

Thank you so much!!!

@patrickcorcoran8183 8 лет назад

Rectus means "straight" not "right", dexter would be right

@curtpiazza1688 11 месяцев назад

Great! 👍

@keysaysassah 11 лет назад

KA, I wanna thank you for saving my life. Honestly, grades are my life and I actually because seriously depressed when I didn't understand my poorly written text book :'( KA, my heroes

@smuggecko 12 лет назад

Very enjoyable thank you

@keine031 10 лет назад

Thanks, No Bromo.

@DMMBX3 9 лет назад

keine031 lmao

@norwayte 14 лет назад

You said it here and there in this and the other videos... in subordinate clauses...WHY we are doing naming things "chiral" and more.... Could you gather the reasons and motivations for all the chiral "things"? Excellent video. Keep on going.

@MileyAshleyfan78 12 лет назад

OMB thxx a lot. U explained it soo well

@TheFischfreak 10 лет назад

thank you very much ;-) even for a german it is good to understand!

@tuberweba2052 8 лет назад

Thanks a lot !

@sinethembaneliswa8131 10 лет назад

thanks a lot I was really lost

@la-margriffiths2481 4 года назад

watching this 20 minutes before exam lets go!

@philster00700 11 лет назад

You are correct.

@s0m0c 12 лет назад

Gracias.

@arvindkumarm1927 11 лет назад

thank u khan

@RightCenterBack 11 лет назад

Thanks

@CitriReg 6 лет назад

Love u sal

@Airkilla09 11 лет назад

Hey Khan you should definately petition to have this system renamed to Khan-Ingold-Prelog System

@robertmz22 13 лет назад

Hi there, and may I congratulate you for your excellent teaching. Question, from min. 5:00 -> You say that we have to rotate the arrangement so that the lowest group "sits" behind the molecule, and you rotate it using the Br - Carbon bond as an axis... now, would it be possible to use the Methil - Carbon bond as an axis (so that CH3 stays fixed and Br, and H rotate) ? And if possible, would this implicate different results ? Thanks in advance for both your answer and videos!

@elvismesa7306 9 лет назад

In the past, to be left-handed was considered touched by the Devil. As Wikipedia notes: Historically, the left side, and subsequently left-handedness, was considered negative in many cultures. The Latin word sinistra originally meant "left" but took on meanings of "evil" or "unlucky" by the Classical Latin era, and this double meaning survives in European derivatives of Latin, and in the English word "sinister".

@MonkeyDLuffy-xr4fl 8 лет назад

Ooh, interesting. Thanks!

@ajaysalunke6288 6 лет назад

Will u please tell me configuration in reboxetine

@superfruit2 11 лет назад

my love for you is describable

@olisho7251 7 лет назад

How do you have stereoisomers for an alkAne, is the sigma bond not able to rotate, thus eliminating the possibility for an isomer for a 2 carbon molecule?

@ThePeterDislikeShow 9 лет назад

What happens if you have 2 different groups that have the same atom bonded to carbon?

@redhotpilgrim 11 лет назад

There is a shortcut! in this case the lowest priority was in front of the molecule-- skip any rotation steps, and go from 1st to 2nd to 3rd priority. What you get (S) or (R) is simply the opposite of whatever you get! ONLY if 4th priority starts in front though.

@jigabi2085 Год назад

So their tetrahedral orientation, determines how they will react. The r would react differently to the s orientation. Because of their ''atomic positions'' they would have different reaction. Maybe because of how these same molecules will react to each other based on how they were situated.

@TheMedhero 11 лет назад

they should have called it khan-alone system, because he is the only one who actually explained his stuff =P

@CHeh-wv1sx 10 лет назад

C-H-A-N / K-H-A-N -----> Enantiomer! LOL, why did i find this hilarious.

@SandFoxling 8 лет назад

+lone wanderer its a diastereomer sherlock

@MonkeyDLuffy-xr4fl 8 лет назад

Actually, neither, it's not even a stereoisomer.

@skittless3949 10 лет назад

wait question, when you first named the molecule, what about the hydrogen??

@FlashySenap 12 лет назад

In my chemistry book - the latin word for left and right is Laevus (left,) and Dexter (right). They put D and L in front of the names... It seems both names stand for the same thing. Is these used differently depending on country?

@gardening1049 3 года назад

Thought of giving up an exam ,my friend let me know abt your channel,I think i can ,lets see

@ramachandrasanna6917 3 года назад

Sir cahn - ingold - prelog priority rule Prelogs rule these two are same are not please tell me sir

@skinlessboy 13 лет назад

Use this saying to remember: R rolls forwards, S spins backwards.

@prolarka 14 лет назад

@khanacademy ture, 1st i thought fluorine is closer than the hidrogen, my fault

@davecampbell892 6 лет назад

Hey Sal! Great video as always :) I am a little confused about why this molecule is 1-bromo-1-fluoroethane though. Why cant we just call it bromofluoroethane?

@deatheth5039 5 лет назад

We can.

@TheMiiirna 12 лет назад

Prelog is from Croatia. Actually, my org. prof. knew him.

@norcoboy 12 лет назад

wait....so when rotating the molecule we can just rotate the "tripod" and ignore the top constituent?

@unknwn2312 13 лет назад

Okay, when we're rotating the molecule and are finished rotating the molecule at 6:44... shouldn't the methyl group be on top and the Bromine be coming out of the page?! OMG. I AM SO CONFUSED.

@otivaeey 13 лет назад

I use to remember (S)-Anticlockwise, so SANTI

@spectrum792 5 лет назад

How can you say CH3 is #3 just because of the C(12) is No.3 in serial? Cz It's just not the C rather CH3. Why didn't you count the 3 H? If H shouldn't be counted then why did you count H at #4? And then, how can you call the middle Carbon a chiral Carbon if it's connected to another just Carbon(as u didn't count those Hydrogens)? .. Or did you count as CH3(15) as a whole & then called it called it #3 as it's also #3?

@dugudwn 8 лет назад

Can we also say 1,1 - Bromo-Flouro Ethane?

@rcwcello5607 7 лет назад

Yes, but it would be written as 1,1-bromoflouroethane. You can also leave off the numbers and it would be assumed that it is bonded to the first carbon, making it bromoflouroethane.

@deedrablevins2362 9 лет назад

If you have to do a swap of groups doesn't that change the original (R) to a (S)?

@soneinspirit7 8 лет назад

+Deedra Blevins I thought the same thing, but he didn't swap the groups. He rotated the molecule. So it wouldn't change the R/S configuration.

@MonkeyDLuffy-xr4fl 8 лет назад

No... He just changed the conformation

@SuperAnju24 13 лет назад

@khanacademy

@prolarka 14 лет назад

6:30 not 120, its about 60

@corentinevezard4990 10 месяцев назад

For God's sake, thank you !!!

@ciao_abhi 7 лет назад

when you rank them by atomic mass why do you only consider carbon in CH3? Why dont you consider the entire group CH3?

@rcwcello5607 7 лет назад

The carbon in the methyl group is the only atom bonded to the chiral carbon. You only look the one atom that is the first point of difference from the chiral carbon.

@pujeetjha8265 2 года назад

i love you

@nihayaturrohmah4230 3 года назад

#21

@maitrithakur7130 6 лет назад

👍👍👍👍👍👍

@unknwn2312 13 лет назад

Actually, I think I get it now... haha.

@danielpersaud7161 10 лет назад

what if all the atoms are hydrogen? eg methane

@aggricor 7 лет назад

Daniel Persaud it ain't chiral...

@skembow 11 лет назад

I'm from Croatia and I was sad when I herd you say Prelog wrong. Please, check pronunciation before saying such names. Thank you very much for everything! :D

@Marinecorps1812 14 лет назад

Cahn-Ingold-Prelog System? Those silly chemists misspelled 'Khan"

@TeKNiQ50 12 лет назад

such a hot video.

@flirtatiousdisses 12 лет назад

sinister lol

@bonitachica786 12 лет назад

marry meeeeeee

@BlueUKLouis 8 лет назад

He takes too long to get o the point, it's so annoying.

@MonkeyDLuffy-xr4fl 8 лет назад

He's drawing it literally, and a lot of people tend to find his style useful apparently. Just increase the speed, that's what I do, and stop complaining. Instead thank him for being God-sent. Seriously.