Alcohol to Aldehyde by PCC oxidation- Mechanism and reaction setup with work up

[@waltersobchak7275]

Nice I’ll thumbs up now and come back and watch. I’m on letterbox duty this morning 😺😺😳

[@Dr.Mosharraf]

Thank you dear.

[@prakashkelgandre8788]

Please upload video on Buchwald hartwig coupling reaction

[@Dr.Mosharraf]

I will do that. Thank you for your request.

[@Dr.Mosharraf]

Hi Prakash, Please see my latest video on Buchwald-Hartwig coupling reaction. I hope you will like it. Thank you for asking me to make the video on it.

[@jeeva.b6321]

hi sir I do some project work like this so I need this proper procedure documents and also need your contact number sir please

[@gigiadd2816]

PCC form carboxyl acid too. Tempo + NaClO is Better ti oxydate benzyl alcohol.

[@Dr.Mosharraf]

I never tried that way

[@gigiadd2816]

@@Dr.Mosharraf It's a specific way to stop oxydation to aldehyde. Strong oxidation as PCC produce carboxylic acid too, and Need a further separation as fractionacted distillation, or other mode to separate aldehyde by acid.

[@Dr.Mosharraf]

In my case I didn’t face any problem. And specifically during work up I did extraction with NaHCO3 solution which took away produced carboxylic acid.

[@gigiadd2816]

@@Dr.Mosharraf NaHCO3 to extract carboxylic acid, and separate aldehyde by acid. The separation is good ? Any further purification ?

[@Dr.Mosharraf]

No I didn’t need to any further purification for this reaction. And the NMR was very clean.

[@crabcrab2024]

Is it really required to have such strictly anhydrous conditions?

[@Dr.Mosharraf]

All reactions specially for SN2, reduction, oxidation or any other reaction unless it says otherwise, should be done under argon or nitrogen and if you have pure and anhydrous solvent, then you should use it. For example, Suzuki coupling require water for the base. But still we use anhydrous DME, Toluene, or dioxane etc. it is better practice to get more yield and not to messed up the reaction with poor yield and mixtures. So to be safe side, you can setup reaction always under inert gas and use pure and if possible anhydrous solvent.

[@crabcrab2024]

@@Dr.Mosharraf OK. I understand. Thank you.

[@Christopher.Marshall]

@@Dr.Mosharraf why is it especially important for sn2 chemistry? Water is not a very good nucleophile.

[@Dr.Mosharraf]

But water can destroy your base or produced nucleophile to react. Also it can disturb the transition state. In presence of water, sometimes elimination can occur. I wanted to say here, keep the reaction moisture and air free. If you have seen my full video, you might have seen I have talked about alkylation of fluorine molecule, which was done with KOBu-t. That reaction was also such sensitive, even if potassium tert butoxide somehow get water, the alkylation wasn’t happening. I also have mentioned, in some cases people also use aqueous base in presence of phase transfer catalyst. Compound to compound varied. But SN2 reaction is more favorable in aprotic polar solvent like THF, Acetone, ether etc.

[@meenudevi8282]

why are you choose diethyl ether for reaction quench process instead other solvent and water? can you explain me?

[@Dr.Mosharraf]

Hi Meenu Devi, thank you for your question. It is a very good question. Why quenching with diethyl ether? Because by adding diethyl ether, you are quenching excess PCC and also by adding ether you are changing reaction environment not to give additional oxidation. Because if you add water, that water molecule will be added with your produced aldehyde to create hydrate, which could be further oxidized by a second equivalent of PCC if it is present. Although this is not a concern with ketones because there is no H directly bonded to carbonyl carbon for ketone. I hope I could answer your question. Please let me know if you have further question.

[@meenudevi8282]

@@Dr.Mosharraf thank you sir

[@VijayYadav-cq9os]

What will happen if I concentrate the product and then do work up with ethyl acetate and water

[@chitrarajavel7701]

For 1 equivalence of alcohol, how many equivalence of PCC and DCM should I add sir?

[@Dr.Mosharraf]

I used 1.2 equivalent of PCC and total 22 mL of DCM for 1.5 g of alcohol.

[@chitrarajavel7701]

@@Dr.Mosharraf thank you sir

[@han-rw1bg]

For work up you used hexane and DCM mixture but both these solvents are immiscible. Why didn't you use Ethyl acetate and hexane.... or simply just diethyl ether

[@Dr.Mosharraf]

There must be a reason. Most probably to remove one impurity. I forgot now. I will check.

[@han-rw1bg]

@@Dr.Mosharraf thanks for your fast reply.... please let me know about solvent if possible