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Author: Subject: (Somewhat bad) Synthesis of Piperonal
Niklas
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[*] posted on 20-1-2025 at 11:35


So I just rewatched Sam‘s Lugduname video (https://youtu.be/YdGalCuJ96Q?si=G7DkvF4hivI_6Eki), where he made the ortho isomer of piperonal as an intermediate, and to make it he used the rather interesting approach of catalyzing the methylenedioxy-synthesis with copper(II)-oxide, I presume to achieve an Ullmann-condensation kind of mechanism.
Literature claims 90%, and while it is using dibromomethane, I now wonder how well this procedure could be applied to protocatechulic aldehyde using DCM, as it‘s definitely a lot more accessible than any of the quaternary ammonium catalysts I‘m personally trying to employ.
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[*] posted on 20-1-2025 at 13:38


Quote: Originally posted by Niklas  
So I just rewatched Sam‘s Lugduname video (https://youtu.be/YdGalCuJ96Q?si=G7DkvF4hivI_6Eki), where he made the ortho isomer of piperonal as an intermediate, and to make it he used the rather interesting approach of catalyzing the methylenedioxy-synthesis with copper(II)-oxide, I presume to achieve an Ullmann-condensation kind of mechanism.
Literature claims 90%, and while it is using dibromomethane, I now wonder how well this procedure could be applied to protocatechulic aldehyde using DCM, as it‘s definitely a lot more accessible than any of the quaternary ammonium catalysts I‘m personally trying to employ.


What is also interesting is that he is also using Glacial AA and 48% HBr for the cleavage reaction in inert atmosphere with 48% yields. No pyridine, no ALCL3. Just distill some HBr from a Br salt + drain cleaner and you are ready.

[Edited on 20-1-2025 by underground]
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Niklas
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[*] posted on 20-1-2025 at 14:49


Quote: Originally posted by underground  

What is also interesting is that he is also using Glacial AA and 48% HBr for the cleavage reaction in inert atmosphere with 48% yields.


Indeed, definitely wouldn’t have expected much more than maybe 20% with that approach.
I honestly can’t believe it would work this well for normal vanillin as well, like logically it should, but it can’t be that nobody tried that one and we are still rather using stuff like the AlCl3 / Py demethylation..
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[*] posted on 20-1-2025 at 14:51


Quote: Originally posted by Niklas  
Quote: Originally posted by underground  

What is also interesting is that he is also using Glacial AA and 48% HBr for the cleavage reaction in inert atmosphere with 48% yields.


Indeed, definitely wouldn’t have expected much more than maybe 20% with that approach.
I honestly can’t believe it would work this well for normal vanillin as well, like logically it should, but it can’t be that nobody tried that one and we are still rather using stuff like the AlCl3 / Py demethylation..


LoL i was editing but you was faster :P
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