Stereoisomers, Enantiomers, Diastereomers, Constitutional Isomers and Meso Compounds

[MrJas1991]

So when you're superimposing a molecule on its mirror image, you're rotating it 180 degrees, not flipping it? Because that would alleviate my confusion, I think.

[tdn1991]

At 5:58 when he draws the mirror image in white I think he's doing it completely wrong? But im not sure cuz he seems so sure of it. In the mirror image the hydrogen would still be in the back and the fluor would still come out the page

[tdn1991]

@tdn1991 nvm

[canadianmb9]

I used to teach like him until i took an arrow to my knee.

[herpderpmonkey]

What's the difference between meso and achiral molecules then? Is meso a subset of achiral (since achiral can be perfectly symmetrical)?

[MrUnladenswallow]

the people who disliked this are achiral

[felixthemaster1]

sorry but you CANNOT draw the links to a H. it HAS to be to teh C atom you cant just draw your lines to anywhere. I would get zero marks for this

[abclol3kid]

Hey can someone help me im sooooooo confused...its my first year of A level and its my first time doing organic chemistry. so heres the thing by teacher taught the class stereoismerism and structural isomerism and under those came position, branched, and functional but what Sal is teaching it has nothing to do with what i have learnt? so whats going on is he teaching something totally different ?

[xghoulxx]

@abclol3kid you will get to enantiomers, diastereomers, meso compounds when you get to chirality which is the later half of the course or near the end of the 1st ochem class, dont panic :)

[hahs4]

@abclol3kid this is beyond the A-level curriculum

your teacher mainly said that position, branched, and functional are structural isomerism

and the other is stereoismerism

for the purpose of the a-level thats enough, what sal is saying is some more details

I did alevels btw

[xsiierra]

my professor at uconn owes you her whole life savings! thanks!!

[TheTiitch]

Prof. Sal <3



[ravishlystunning]

wow ! :)

[30reesespieces]

Thanks for these videos, I started watching them a couple of years ago to help complete my HSC I am now 38 in university working on my undergraduate for Medicine. I would hope that the students would also appreciate their own teachers. It is not an easy task these days. I have seen what they have to put up with. This is a great tool to complement your studies. Bless you Sal

[JesusTheGardener]

I'm in high school AP chem and you teach wayyy clearer than the teacher thank you

[kingmedabe]

Makes so much more sense than my professor. We call is diasterioisomers instead of diasteriomer though.

[TheWoWRevelation]

@Notheus Story of our lives.

[Faiangel]

@gngrbdk actually it is superimposable ^.^ perhaps he shouldn't have explained it as flipping the benzene ring. if you were to turn the 1first benzene ring 180 degrees, you would see that they are indeed the same compound

[gngrbdk]

@Faiangel ah, i watched it again and saw you're right. i remembered another one and replied like that. they are the same molecule.

[PoisenIvy69]

Khana! Getting me through Chemistry since 2009!

[efosmen]

can i take ur class next semester pls, pls

[TheNightFusion]

The last part is not a mirror image...Since its cyclohexane, one of the groups coming out towards us will be axial and the other must be equatorial.

[maznasty10]

Sal, how come the molecule at 12:10 is superimposable? It seems like if I put them on top of each other, they won't superimpose. I thought they would be enantiomers because they're mirror images of each other.

[TheBigtiff]

@maznasty10 If you rotate one of them 180 degrees in the plane of the page they will be super imposable

[Kakarot21591]

To Abdullah et. al., the molecule is non-superimpose-able because the fluorine on the left side is UP, but when you flip it over and try to superimpose it, it ends up pointing DOWN. The fluorine on the right is already pointing UP, so they will not sync up.

[killergiant34]

I agree with Abdullah, at 13:12 why cant you superimpose the molecules that have the fluorine? The wedges remain the same with respect to both fluorines and bromines, and if you flip them 180 degrees, you get the same molecule. Am i missing something?

[Abdullah19910]

At : 13:26, Could you explain why they can't be superimposed, because If you rotate the molecule 180 it would be the same molecule.

[kayaktenable]

You are the shit dude...I finally understand this stuff ...never did really understand it in general chemistry....I have a test tomorrow and I think you just sealed me a decent grade....I was afraid, very afraid of the" mirror mirror on the wall, what chemistry student is going to take a fall"....HA..Thanks man...

[PainCakesxX]

@kayaktenable

Stereochemistry in Gen Chem? Damn, that's one crazy school you go to...

[orangejuiceangelaa]

why the mirror in the back? wouldnt it be the same if you just flipped it?

[2glam4aUsername]

How come at 11:00 he didn't simply say that the H and Cl bonds were already the same???

[iniloy1993]

im kinda confused on couple things..

1) why do you switch the wedges and dashes when the mirror is behind but not switch it if the mirror is to the side??

2) for the last one, if you flip it, then shouldnt the bromines go to dashes rather than wedges?

[filipinatrina2006]

@iniloy1993 for your first question, when u put the mirror in the back, the atoms in the back of the actual molecule will appear in the front of the mirror image. and the atoms in the front of the actual molecule will appear father away and towards the back of the mirror image. so that affects whether there is dashes or wedges. If the mirror is to the side.. the atoms in the front will still be in the front in the mirror image and same with the back ones.. i hope that helped.

[TheVelocirapp3r]

can we do it? yes we khan!

[seniorgomez6689]

Khan, you're in everything! Keep it up!!!

[chemmalakuzhyj]

The dude up top probably had yamamamoto for o chem haha

[chemmalakuzhyj]

The dude up top probably had yamamamoto for ochem haha

[H3BLTM]

saved me learning 4 weeks worth of lectures!! xD ta! ty! LOVE IT!

[Yoganut319]

Your videos are AMAZING! Not only are you saving my keister in organic chem, but you're helping me in molecular bio too! I wish I could send you an edible arrangement!!!

[georgyorgy2]

12:13 You spelled superimposable wrong

[kazmanX]

My chem prof went to stanford and mit, but he's got nothing on you... oh yeah, he is not a BOSS like you!

[Lov3lyx]

Thank you for all your amazing videos - they are so informative and useful! Just wondering:

Are all enantiomers chiral?

Thanks :)

[knighthandsome]

you are awesome, if you become an instructor in the future, i'll take your class for sure

[arshass]

I think I love you...

[Ace220X]

Thanks a lot! I've finished OChem 1 and 2, and never had a teacher that could explain stereochemistry well enough for me to fully understand it. I could usually get the problems right without knowing what I was doing, but that sucks. I get it now!

[fatkidinaspeedo]

KHAAAAAAAAAAAAAAAAAAAAAAAAAAAA­AAAAAN!!!

[iPaiRx]

Thanks you help me more ^^

[BaseAndAcid]

@Notheus @mandi8452 Now I start to think that all chemistry teachers are women..

[nitrorev386]

Next semester, I will watch all of your videos before the lecture so I know what the hell the teacher is talking about.

[moka22051]

@nitrorev386 GOOD IDEA

[salmanmsaeed]

Thank you Mr. Khan, you will be a great part of the of my life in this coming month. Your videos are amazing and you explain in 13 minutes what my lecturers can't explain in 50 minute lectures and that is perfect for exam study.

[007abhinavagarwal]

thanks

[aznjerk123]

ha ha im the only one who disliked

[007abhinavagarwal]

@aznjerk123

u r only fool

[Standardguttene]

if people started watching this guy instead of going to school everybody would be disburbingly intelligent

[dudekyle13x]

An easier way to do this (for me) is to look at the R and S configurations around each stereocenter. If you have two compounds and if one compound is (2R,3R) and the other molecule is (2S,3S) you know they are enantiomers because both R's and S's change. Now if the second molecule had (2R,3S), only one letter changes (the S) so they are diastereomers. When they have a change at one or more stereocenters (but not all) they are diastereomers. Meso compounds have a plane of symmetry.

[dudekyle13x]

@dudekyle13x

If you know your R and S configurations this way is faster because you don't have to draw out the molecules and flip them etc. Plus in Organic Chemistry you will most likely have compound naming questions on your exams that require R and S designations in the name, so it's extra practice for that too.

[junior1984able]

so the wedges are the atoms coming out of the paper pointing toward you and the dotted is going away right, what about the normal wedges

[SanniYork]

@junior1984able

As you said, the wedges and the dots/lines represent the plane going in/out of the image, towards/away from you.

The lines (for example between carbons) represent the plane following the image, simply going from left to right, like the horizon.

[junior1984able]

i am confused

[junior1984able]

maybe you could use real life molecule  diagrams to explain the fliping

[dudekyle13x]

@junior1984able

Junior, if you are still confused an easier way for you to see if they are enantiomers, or diastereomers, compounds is to use R and S configurations around stereocenters. (See my recent comment to this video). Hopefully it helps and if you have any questions you can always shoot me a message here on Youtube :)

[junior1984able]

@dudekyle13x thanksx

[wendy321]

omg i screamed out in joy when i saw that you actually did a video on enantiomers!! that other video on youtube about enantiomers with hands and pens was confusing. and incorrect.

[WauLYaYo]

ur the best mayn!!

[kermitcintronsucks]

Uh, is khan academy gonna create an organic chemistry module/exercises?

[Link64]

What subject do you NOT know?!?!?!?! :O

[love43283]

I signed on just for you. You are the Prize!!!!!!!!!! Thank you.

[fugert]

enanchiomers?

[riks1991]

Thank you!!

[NKindianhobo]

LOVE this guy

[iStudy101]

Hello,

Great explaining!

But, i have a question for the last example of the 1,2- dibromocyclohexane...when you flip them dont the wedge bonds become dash bonds and vice versa? So the pair are not superimposable...

please reply asap. I'm desperate! I'm a nerd. :D

[abeautyqueenofonly18]

hey man THNQ> u made my ideas and doubts . clear and all.

Hope u lead a happy teacher life.

[daddylira]

great work you make the information so easy ....keep up the good work :)

[RifaiM]

so how do you know when to do the mirror on this side

or the mirror behind the molecule?

[mandi8452]

my teacher at ODU owes you her paycheck. great job!!!

[poopdude]

Awesome, I was getting so confused with all these vocab and its nice to see it be organized by these examples.

I'll still need to spend more time on it, but this helped a ton. Thanks!

[karatefox]

Excellent video, thank you very much for sharing :)

[markgia]

In my book, it says that a diastereomer is a compound with multiple chiral centres and therefore cannot have an enantiomer. Do you agree with this definition Sal?

[FirelionGuate]

@markgia I think Sal will be taking a good ole long break and someone else(if it ever gets answered) will answer this question you just made. Stupid google. Hope Sal comes back and everything becomes simple and normal like before...

[dalcde]

Could you make a video on adenosine triphosphate? You mentioned it in the biology playlist, and I am interested in understanding more about it.

[rbazlami]

@dalcde He already made it

[ingnir]

Sal eres un chingon. I went through the whole organic chemistry series and never really new what a diastereomer or meso cpd was until now.

[MarvelsofaLifetime]

Sal really does just win at life. How else can it be put? The man knows everything and is soon to be a multi-millionaire.

[hobomnky]

at 13:30 wouldn't it still work if the mirror was inbetween the two

[Lern2Read]

superimposable* at 12:30

[Rayman304]

cool... first view

im amazed that i am interested in this level of chemistry and im not in any chemistry courses yet...awesome Sal!