Alcohol Oxidation Mechanism with H2CrO4, PCC and KMnO4

[@Arikomaro_yt]

I'm preparing for JEE (an Indian entrance examination) & to be very honest, I loved this video. Thank you so much Leah...

[@djchemtalk2946]

Im very much delighted by the way u explain the mechanism. It is very informative over reading volumes of pages of so called organic text books... Once again thanks a lot for valuable teaching...

[@Scavenger_-nj1or]

Sand bob and vagene

[@Leah4sci]

You're very welcome, so happy to help!

[@uchennaofodile8878]

Thank you for showing the mechanism and thank you for not just showing it, but for showing why the steps occur the way they do with the partial charges. You are a great teacher!

[@Leah4sci]

You are very much welcome! Glad to help :)

[@kareemmohammed5658]

@@Leah4sci +

[@beingfor1825]

what a wonderful chemistry teacher you are! when you teach chemistry, it makes sense, it becomes interesting, motivating, and above all fun.

[@Leah4sci]

Wow, thanks so much for your kind words!

[@Petipuf8]

Hi! My professor said that an internal proton transfer between the alcohol and chromate can’t happen in this mechanism because the distance between them is too small-it’s done by the solvent instead. Just what he said when we all used your mechanism on our homework’s and marked us wrong.

[@Leah4sci]

oh wow! I'm sorry to hear that you all got it wrong! definitely double check with your professor because everyone teaches it a bit differently

[@thehottalk7606]

@@Leah4sci he/she might have graduated by now 😂😭

[@Karmic_Retribution]

@@thehottalk7606the 5 year later response is crazy 😭💀

[@vishalgaurav4411]

you are one of the best teachers have seen ever

[@Leah4sci]

Wow, thanks!

[@fernandofischer3725]

Very very good video. I'm amazed with how much I've learned, thank you very much. I have a question. On the PCC reaction, when the alcohol electrons attack the Chromium atom, why do the Pi electrons go back to its Oxygen, instead of the Cl atom being released? At first i thought resonance might be the molecules first choice (because its weaker and it would rather move its electrons around than lose an atom (PS: i don't know if its weaker)) , but later on, those same electrons are able to push the Chloride atom out.

[@Leah4sci]

I'm glad the video helped. As for your question, at which specific point in the video?

[@fernandofischer3725]

Leah4sci At min. 7:43 the attack takes place.

[@Leah4sci]

2 things to keep in mind here. 1- the pi electrons are always resonating 2- the goal is to find the most sensible next step - ie what is natural and stable. a pi bond in resonance will be easily kicked off. It's when the pi bond forces itself to reform as the electrons come back out that we kick out something else. You'll see this a lot in carbonyl reactions. TCAI intermediate and then pi reforms to kick out a leaving group

[@diptilulla2895]

In strong acidic solutions due to ionisation anions and h+ exist so why aren't we allowing a negative charge?

[@Leah4sci]

I'm sorry, but I don't offer tutoring through KZbin comments. For help with this and more, I recommend joining the organic chemistry study hall. Full details: leah4sci.com/join

[@michaelfairchild9561]

at 4:55, did the double bond to oxygen break? I don't see arrows or explaining ?

[@Leah4sci]

Oh wow, I forgot to show the arrow. You are correct though, the pi bond breaks collapsing upwards onto the oxygen

[@shuanlin3763]

Hi, thanks for your teaching! I wonder how you find these mechanisms. Is there any research that can support?

[@Leah4sci]

Of course! Lots of research went into understanding these reaction mechanisms. For help with mechanisms like this and more, I recommend joining the organic chemistry study hall. Details: leah4sci.com/join or contact me through my website leah4sci.com/contact/

[@elocitybeats4308]

11:11 Manganese has 8 valence electrons how is that possible it should have only 7 according to the periodic table

[@Leah4sci]

The periodic table shows you valence electrons native to the atom. However, each atom will attempt to reach a complete octet via donation, accepting, or bonding

[@safiaqureshi3939]

thanks for the video- Isn't the first step reversible (and maybe the proton transfer too, not sure)? Also is the second product H2MnO4?

[@Leah4sci]

I believe any step is reversible, under the right conditions. And yes, manganic acid would be a by-product of this reaction.

[@kouiderbenmoussa4527]

Hi, thanks for the explanation. Does the Mn2+ ion act as an autocatalyst for the reaction between an alcohol and the MnO4 ion? Thanks in advance for your answers. 😊

[@Leah4sci]

This question is outside of what I cover in this video. For help with questions like this and more, I recommend joining the organic chemistry study hall. Details: leah4sci.com/join or contact me through my website leah4sci.com/contact/

[@JKG601]

this video better than other organic chemistry books, thank you so much.

[@Leah4sci]

Wow, thank you!

[@bhavanakalyankasture9159]

Is there any video on swern oxidation?

[@Leah4sci]

Not yet, I'll consider it though

[@01107345]

What if you wanted to get just an aldehyde without it then becoming a carboxylic acid? Would you have to interrupt the reaction somehow? I'm a bit confused because we're doing retrosynthetic analysis in class, and we're being taught that we can use chromic acid to produce an aldehyde, and that that aldehyde can then be used with a grignard reagent to produce an alcohol. But how would you stop the aldehyde from becoming a carboxylic acid?

[@miguelhernandezgonzalez9305]

The only way to not further oxidize and stop at the aldehyde is to use PCC/Ch2Cl2. That's it purpose. The H2CrO4 will always further oxidize the primary alcohol into a carboxylic acid.

[@Leah4sci]

PCC is a milder oxidizing agent that will oxidize a primary alcohol to an aldehyde without going all the way to a carboxylic acid

[@01107345]

@@Leah4sci Thanks for the reply! It was fun figuring out what my old question meant and then figuring out you guys' answers. Oh, and ChatGPT is like "maybe you can use a low temperature with a strong acid also!", for what that's worth.

[@aminebelkacem9661]

there is actually one remark , In PCC mechanism : why Cl- grabe the proton over attacking the carbon as a nucleophilic substitution while the (HCrO4)- would be a good leaving group as you said thank you for your efforts

[@Leah4sci]

That’s a really great question! Having the chloride attack the carbon would cause the electrons in the carbon-oxygen bond to be newly deposited on the oxygen as a lone pair. This forms a negatively charged oxygen that is not likely to exist in the acidic medium of this reaction. Furthermore, chloride is a better base than nucleophile.

[@PoppiD93]

As other people said, mechanism very well explained! So then it's easier to remember rather than a mnemonic sequence of steps.

[@Leah4sci]

So happy to help you not just memorize but truly understand

[@muhammadmasood9767]

Excellent methodology to explain mechanism in detail..,. Thanks a lot for this effort.....

[@Leah4sci]

Glad you enjoyed it! You are very welcome

[@bogkenkawaleboryalism5426]

thankyou so much- im satisfied - you boost me of understanding organic chemistry.

[@Leah4sci]

You're very welcome!

[@jacksonmafuta9102]

you talk chemistry and its exciting.... continue unlocking the hiden concepts

[@Leah4sci]

Thank you! Do subscribe to see more videos.

[@everlyneowiro1723]

Thanks for your help, you're the best

[@Leah4sci]

Thanks! You're very welcome!

[@vaibhavbhardwaj8781]

thank you so much .Was Looking for exactly the same thing

[@Leah4sci]

You're welcome!

[@sidharthapandey4231]

In chromic acid what happend of chromic ester in solution .....pls tell me Sir

[@Leah4sci]

The chromic acid reagent is regenerated by the chromate ester when the Cr-O bond is cleaved. This happens at the same point in time that the alcohol is oxidized. See 3:30 in the video.

[@sidharthapandey4231]

@@Leah4sci ok

[@alondraherrera4170]

leah i hope you have nothing but a good life u taught this very well since my prof is a complete jackass tysm queen

[@Leah4sci]

Hate to hear that you have a horrible professor, but I'm happy to be able to help you understand

[@karanbhanushali6756]

Nice explaination mam

[@Leah4sci]

It's my pleasure!

[@souravkumarroy5912]

Thank you so much .....please more update with new topic...

[@Leah4sci]

You're welcome! Keep checking back for more videos!

[@sharpshootero1459]

Nice videos.Once again thanks for the help.

[@Leah4sci]

You're welcome, happy to help!

[@maggiechen9607]

THANK YOU SO MUCH

[@Leah4sci]

You're very welcome. :)

[@shivakumarnagavimath157]

I am writing what u r telling in videos some words are not have clarity in speaking plz can u slow down ur words with more clarity but ur explanation is amazing

[@Leah4sci]

You can adjust the speed in the video settings to slow it down.

[@shivakumarnagavimath157]

@@Leah4sci i am also telling about ur clariry of speaking some words are not lesionable

[@santhib7761]

happy teachers day mam!!!!!!!!

[@Leah4sci]

Thanks a lot!

[@abdrahmanmappiase8926]

very helpful thanks a lot....

[@Leah4sci]

You're welcome, happy to help!

[@mads-24-s]

Thank you!!!

[@Leah4sci]

You're welcome!

[@The_Broken_Smile]

You are very scientific! Thank you .

[@Leah4sci]

you're welcome

[@abdulawal4660]

Thanks mam for great teaching ❤️🇧🇩

[@Leah4sci]

You're so welcome!

[@jelenazivkovic7423]

Супер објашњаваш.👍

[@Leah4sci]

Thanks so much, so glad you liked it!

[@muhammadarshadmarshad7236]

Explanation is too good. But why oxygen protonated first always?

[@Leah4sci]

Check out my explanation at 1:53. Because this reaction is happening in an acidic solution, we cannot collapse a pi bond onto an oxygen that is deprotonated. This would result in a negatively charged oxygen that cannot exist in an acidic medium.

[@ali_ibn_munshif]

I love you ❤️❤️❤️

[@Leah4sci]

Thanks

[@sidharthapandey4231]

Hii i m from India

[@Leah4sci]

Hi!

[@sidharthapandey4231]

Can u guided me?

[@aishaali1858]

nice

[@Leah4sci]

Glad you like it

[@chemistryeasy2241]

👍👍👍

[@Leah4sci]

:)

[@sarfarazmungloo4481]

Why doesn't lecturers explain in this way? Mine just gave me a pdf and voilà.

[@Leah4sci]

Sadly, some professors don't teach well (not all, but too many). I'm happy you've found my resources to help you!

[@Sky-pg6xy]

So chloride said, if youre gonna ruin my day im gonna ruin your whole career

[@Leah4sci]

lol