Wittig Reaction

[@cognitivedissonance7422]

you are my hero. Forget Batman, you are the hero we deserve.

[@Pad2Paper]

Not all heroes wear capes.

[@chander.261]

@@Pad2Paper cracked at Fortnite my guy

[@Marcofernandez12]

Real

[@hsabulkhair]

Thanks Dave, I think it will be more accurate if you reversed the directions of curve arrows at 4:52 to make electron in C-O bond going to Oxygen and those in C-P bond toward the Carbon. Thanks again

[@jaejeong4271]

Thanks!

[@noneofyourbusiness3288]

Well done. I have one minor thing to note though: I personally would draw the arrows in hte last step the other way round. It basicly doesnt matter, but "giving" the electrons in an O-C bond to the carbon and not the oxigen seems odd; much more likely the P-C bond breaks in direction of the C. Aside from that, again a nice and understandibly video, well done ^^

[@imranshakeel7874]

agree.

[@miska8035]

I know its a 6 year old comment, but what I've seen in literature, the arrows are always drawn the same way Dave is drawing them. Cannot explain why it is like this, or not sure if it does even matter. [Clayden, Greeves & Warren: Organic Chemistry, 2. p, Oxford, 2012, chapter 27.]

[@mathr4306]

Thank you so much for your explanation, I have an exam tomorrow and I didn't understand Wittig reaction, but now I do!! From a french chemistry student :)

[@Nexus2Eden]

Excellent, truly. We just covered this, and even though my Prof. is fairly good at explaining RXNs - I feel I have a much better understanding and your presentation was very easy to follow. I feel much more confident about this RXN now. Thanks!

[@markushinterthan7960]

Man, if my prof explained this as good as you do... I already thought I'm too stupid for organic chemestry.

[@keersy7]

Goddamn. You are the man. Precise and to the point. You’re saving my grade, can’t thank you enough!

[@benscrafield9575]

Sadly this video propagates an outdated model of the Wittig mechanism - please see the Gilheany Chem Soc Rev review to understand that the modern interpretation of the reaction is that it occurs via an asynchronous [2+2]. Betaines should not be invoked. The twisted TS you get in the [2+2] is necessary to understand how stereoselectivity depends on ylide type (stabilised => E; unstabilised => Z). Incidentally, I would also advise against showing π bonds between P and C/N/O - exactly what orbitals are overlapping there? An ylide-type structure represents all of these structures adequately (including phosphine oxides), in my opinion.

[@ProfessorDaveExplains]

I thank you for your very appropriate comment, and my answer is similar to the one I gave you for the Beckmann rearrangement. My lecture was based on the mechanisms given in most textbooks, which are now superseded by more recent studies on the oxaphosphetane mechanism. As you know, textbooks take forever to react to new developments in the literature, which leads to the diffusion of “older” mechanistic ideas. This video is also slated for replacement, and your insightful comment prompts me to do it as soon as I can. I am less in agreement about the representation of ylides and phosphine oxide exclusively as zwitterions, but I think this is a minor point. I am also in disagreement about betaines. They are not involved in lithium-free Wittig chemistry, but most likely play a major role in Wittig reaction in the presence of Li salts. I will also distinguish between stabilized and non-stabilized ylides, although my script is rather long and I am still debating whether to skip some stuff, especially since, as you know, this reaction is now avoided in industry, and is destined to become a reaction of mere historical significance, or at best a tool for the less elegant academic total syntheses. It does get asked a lot in college examinations though.

[@uuuuu1781]

​@@ProfessorDaveExplainswould love a new vid on the wittig reaction including its stereochemistry :)

[@Smaileymaile]

Thank you so much for your videos and help through email! I managed an A in ochem 2 and now just have to tackle environmental o chem

[@divyadyutiukil3232]

I never understood this so well till today.. Thank you sir

[@soladotunsalawu9002]

Wittig reaction has never been easier!! THANK YOU!!

[@mirianehujuo5884]

After 9 years I still found these videos very useful… thank you Professor Dave … you’re a hero

[@marianacorrea3387]

im a brazilian student and im so glad that i found your channel, u explain this so well, i saw this wittig reaction in klein but its not good explained, so im thankful for u teacher

[@HaleyGirl923]

I LOVE your videos. You helped me 4.0 orgo 1 and I'm watching you again to try and 4.0 orgo 2. Explained it so much better than my TA when I went in for help.

[@DeNoobdi]

I am highly grateful that you exist!

[@mariamalaa4463]

That's life saving I swear .

[@robdelman3487]

you make the absolute best videos

[@philsaspiezone]

The reaction which converts a carbonyl group to a C=C double bond using an organosphosphorus zwitterion called an ylide. The triphenylphosphine oxyde and an alkene are products.

[@limmuquan4796]

An alternative mechanism involves a irreversible concerted [2+2] cycloaddition of the ylide and the carbonyl compound going straight to the oxaphosphetane. The consensus now seems to be that that, and not the one shown which involves the betaine, is the actual mechanism(at least in the absence of lithium salts). The cycloaddition mechanism better accounts for some of the details in the stereoselectivity, among other things. See for example a paper titled "The modern interpretation of the Wittig reaction mechanism". But this minor detail aside, a very helpful video, thanks

[@SyenPie]

LMAOOO I was reading about the Wittig reaction in my Kaplan book and initially I thought "ok this mechanism I'm gonna skip for now..." but I figured I'd still just skim your video for good measure. But WOW you ACTUALLY made me understand this reaction crystal clear... there are so few people who can SIMPLIFY the way you do without leaving any key details out! 💯

[@nadinadi6869]

sir upload videos about preparation of ketones and aldehyde

[@moshaheedshaikh7865]

Professor no1 can make this reaction as simple as you did...thumbs up..;)

[@mirandantui8536]

This is so much better than my lecturer's

[@informationguru8299]

Your explanation is good, THANKYOU FOR THIS.I am a IIT JEE aspirant from India,i had a bucket of doubt on this mechanism but n😊w i am Clear about all the steps ❤

[@djennings-DDS]

Thanks Dave! At 5:05, the arrows should be pushing the other way due to electronegativity, correct? The product would be the same but the electrons between the C-O would be attracted to the Oxygen, whereas the electrons between the C-P would be attracted to the Carbon.

[@ProfessorDaveExplains]

Hmm, I had always operated under the assumption that the direction of those two arrows was arbitrary, but I suppose if we consider the polarization of the bonds what you are suggesting might make sense. I wonder how that might be tested!

[@SameerSk]

Professor sir "This is Awesome" .🙏🙏🙏🙏. Your explanation is supercalifragilisticexpialidocious!!!!!!!!!!!

[@hashirgill2922]

Give this man a medal

[@michealwaldrup4357]

Dear Lord.

[@ProfessorDaveExplains]

i encourage schools to use my stuff in class! but failing that, just tell your friends to subscribe :)

[@miklosdeak8000]

Bro im studying Pharma and ur videos are so helpful ure King🙌

[@MaybeMaxwell]

This was unbelievably helpful.

[@ganeshgs2241]

professor forget to discuss about the stereochemistry of wittig, story like stabilized and unstabilized and E, Z...

[@XxToXicVaGxX]

What about the stereochemistry for these reactions? The Z or E stuff for these reactions in particular are rough for me for some reason. I just don’t know how that is determined as the same or opposite sides in this reaction

[@ekantoro9013]

Thank professor, you came to earth to teach us

[@matroxman11]

Bless you professor dave you're doing the lords work

[@shanemichael9011]

That was an outstanding explanation Prof. Dave. Once again, Thanks again ! I am always left however with wanting to know just a little more. Call it meaningless curiosity. Like, why not a compound like a Phosphorus attatched to 3 ethyl groups instead of 3 benzene rings. Perhaps because the benzene rings will stay inert during the reaction whereas the ethyl groups will inadvertently participate. Who knows ? But anyway, that was a great video !

[@shaikhfirdousmuskanR]

ur videos have always been helping me tysm sir i just love ur teaching short videos and more understanding. ..hooo

[@suramyashrivastava9761]

Brilliant video . Always got a clear explanation and yes , the starting music for the video is awesome.😂💓❤️💞

[@songohan393]

just making sure I liked every single video

[@Piyush-i4t]

smoothly u all the things defined....u r awesome sir

[@nagasudharanisuraboina9781]

I'm very dumb at this reaction but you made it so simple Thank you sir

[@sulaimanaloraini4212]

Good explanation Dave

[@robertjennifer3784]

I really appreciate this video.thumbs up Mr prof

[@SarthakAggarwalme]

Beautifully explained. Thank you so much :)

[@mariamziad9379]

This was very helpful, thank you!

[@arexqui625]

Best Professor ever!

[@wsdfewefsvdsfasg1212]

wheres the part where you explain the differences in stereoselectivity between stabilized and non stabilized ylide? DAMN SON

[@Mistgabel]

very helpful thank you. Would be nice if you could say something about the stereoselectivity aswell. I know that the thermodynamic product is E and the kinetic is Z and that you can use stabilised Ylids to form the E double bond or unstabilised Ylids to form the Z double bond, but i dont understand the mechanism behind it! Still super understandable video

[@ProfessorDaveExplains]

i will try to make a practice problem including this! thanks for watching!

[@johnmao1248]

Professor Dave: thanks. good share, good lesson.

[@jasminferreira3544]

More specifically, the pronunciation of Wittig is Vit-tig. Also, the way you say ylide is strange, you say it as il-id (don't pronounce the 'y'). Just for further info: The resonance form of the ylide (containing a double bond between the 'R' group and the P atom) is referred to as a phosphorane. Overall the Wittig reaction is a great reaction to use on paper but it does unfortunately produce the unwanted triphenylphosphine oxide by-product. A reaction using a stabilised ylide leads to the preferred formation of an E-alkene whereas a reaction using an unstabilised ylide results in Z-alkene formation. :)

[@ProfessorDaveExplains]

Thanks for the additional info!

[@Nexus2Eden]

+Jasmin Ferreira Hey some else has had OChem II lab!

[@maxfuchs2524]

+Jasmin Ferreira Can you tell me why a stabilised ylide leads to a E product an a unstabilised ylide leads to a Z product? I know that it has something to do with the mechanism, but I don't get it, even after drawing them.

[@courtneyriley185]

....this binge watch is gonna be hard but least Ill learn ?

[@LOLWAAHH]

Nice! We were taught to use n-BuLi as the base to abstract the proton from the attached R, but I’m assuming, as the video explains, that any base would do?

[@ProfessorDaveExplains]

sure you can use a variety of bases, RLi is very common. has to be very strong though i believe!

[@ucci4pie600]

Nice video, helpful indeed!!! Parsec! nice tattoo bro...I just finished cosmology class.

[@eleazarvillaflor5747]

Thank you Orgo Chem Jesus

[@Huzabul]

fantastic video! thank you!

[@abhilashsahu452]

What is the steriochemical consequence of the stable and unstable Ylide ?? Sir

[@mamtaghosh3255]

sir you are awesome .

[@djchemtalk2946]

Super explanation

[@charlesedwards12346]

YOU'RE THE BEST!!!!!

[@ranganatha.b.r6854]

Can you make clear of the stereochemistry of this reaction as I have read that both Z and E forms are possible if there are hetero R groups on each of the reacting carbon atoms? Well done by the way. Keep going...

[@ProfessorDaveExplains]

yes both isomers are possible! in terms of getting selectivity for one isomer over the other i don't really recall, i think there is something regarding the stabilization on the ylide, unstabilized favors Z and stabilized favors E, but i don't remember why.

[@saidfsr91]

thaaank you for this video.

[@PG-qn8od]

oh mi god, i love wittig reaction, you explained it very well 💅🏻👍🏻

[@HangingQueen]

I like your hair style

[@BaMagraM666]

thanks prof. dave !! :)

[@ranjanpaudel698]

thank u aagain ser....sweet explaination aagain....you deserve the noble prize....after ser wittig for this chem reaction....hahhaha...

[@qwekuyeboah200]

Crystal clear

[@EricRomeoCalderon]

Can Ylides be used in protic solvents?

[@neerajtiwari6600]

Sir whether reaction initiates spontaneously or some heating is required

[@Error-yh3xr]

Maybe you should say nucleophile attacks electrophile.

[@AddisonPhilips]

what happens to the bromine after the SN2 (SET?)attack by the phosphorus on to the carbon atom in the alkyl bromide?

[@ProfessorDaveExplains]

AddisonPhilips nothing special, just sits in solution.

[@kirubabowneeth3928]

thank you sir.

[@abilashsr9674]

kiruba bowneeth 😳🤪🙄🤣

[@karthikmangathaya9529]

Sir how does the tri phenyl phosphine attack the alkyl bromide via SN2 even though it's steric hindrance is huge?

[@ProfessorDaveExplains]

yeah it's a little tricky to imagine but don't forget the trigonal pyramidal shape and also that phenyl rings are completely flat

[@karthikmangathaya9529]

@@ProfessorDaveExplains thanks. You the man!

[@VikasM258]

Me at viva = 5:20

[@abhishekchunduri8285]

Sir, why does the spontaneous flipping of bonds occur all of a sudden in the four membered intermediate???

[@abhishekchunduri8285]

Is there any specific reason!

[@ProfessorDaveExplains]

i think it's thermodynamically driven! we can compare bond enthalpies to see if that is the case.

[@bw6329]

u r amazing sir

[@Sakshi-vj5km]

his face looks like ranbir kapoor of bollywood.

[@AbdulRehman-il9bn]

I understand 😊

[@AbdulRehman-il9bn]

I understand first time Thank you sir

[@bic1349]

Amazing!

[@biotechchem9778]

Excellent

[@primordial7305]

I wish you are my lecturer

[@neerajtiwari6600]

Is it a chelation process of forming ring???

[@ProfessorDaveExplains]

+Neeraj Tiwari kind of, chelation is when some kind of ligand makes more than one coordination with some central atom, like a transition metal. it results in something sort of cyclic, but not in the same sense as say, cyclohexane.

[@cassc5330]

Can the carbonyl be an aldehyde?

[@ProfessorDaveExplains]

+Cassy Cunning yes indeed!

[@eastofthegreenline3324]

Nice explanation. And neat tattoo! Parallax...?

[@ProfessorDaveExplains]

yep! check it out in "ask professor dave #3"

[@ScottNguyenRCAC]

eelid, eulid or ehlid? idk 😂😂🤦🏻‍♂️

[@ankushmadival9278]

Anyone in 2024...

[@Amy-se5ld]

I love you

[@mwalia9582]

plz do haloform rxn

[@rassimsimou1594]

Good

[@thechemistlife]

awesome

[@mr.murica9571]

watching this cause my prof is too lazy to teach

[@anubhavranjan1145]

Chemistry Jesus

[@henylor2813]

is this english?

[@W1TT1G]

What is wittig, other than my last name

[@gamingnoobie1700]

this comment section is OOOO PPPPP

[@conceptuallearningforiitje9738]

Sir is it all fine now In italy Here in india we are heading towards a big trouble May china end soon

[@homemobile8362]

❤

[@kchorman]

You say ylide wrong...