I read the Rhodium 'Vanillin Demethylation with Pyridine and AlCl3 synthesis" and see no reason why the same reaction couldn't be done
with4-Allyl-2-methoxyphenol.
From what I read about this reaction, the by-product of this reaction is chloromethane, and that chlorine comes from the AlCl3. Furthermore this
reaction is finished by protonation by HCl.
That being said, does that mean there's no way to recover the AlCl3 catalyst then? If I used aqueous HCl, the water will hydrate the salt and make it
useless. I then had the bright idea that they could use HCl gas instead, but does that solve the issue of the missing Cl stolen by the methyl leaving
group? Should I be worried about adding HCl across the alkene double bond?
If anyone has any insight or suggestions on how one could recover AlCl3 in this reaction to use again later it would be greatly appreciated!
[Edited on 24-5-2022 by MrShackleford]
[Edited on 25-5-2022 by MrShackleford]
I've got a theory
draculic acid69 - 24-5-2022 at 03:00
I have a theory about this rxn that the hydrobromide would work better as a demethylating agent than the hydrochloride. Just a guess but I think it's
a good betTexium - 24-5-2022 at 06:50
SWIM read the Rhodium 'Vanillin Demethylation with Pyridine and AlCl3 synthesis" and sees no reason why the same reaction couldn't be done
with4-Allyl-2-methoxyphenol.
No SWIMming on this forum. All it does is make you sound like an idiot. Please
refrain from it in the future, and re-write your post if you can. It is truly painful to read.
[Edited on 5-24-2022 by Texium]clearly_not_atara - 24-5-2022 at 12:38
AlCl3 is used stoichiometrically in the reaction (equimolar amounts of AlCl3 and vanillin). This is a clue that it is consumed, rather than acting as
a catalyst.
Quote:
sees no reason why the same reaction couldn't be done with4-Allyl-2-methoxyphenol.
I will make extensive use of that in the near future.Mateo_swe - 28-5-2022 at 01:28
Why not use Aluminum Triiodide, AlI3?
In the "Protocatechuic aldehyde from ethylvanillin" thread i attached a document that is about demethylenation of vanillin, Eugenol and similar,
"Cleavage of Catechol Monoalkyl Ethers by Aluminum Triiodide–Dimethyl Sulfoxide".
It also covers the demethylenation of Eugenol aka "4-Allyl-2-methoxyphenol" to Hydroxychavicol (4-Allylcatechol) with yields stated at 94% on
gramscale demethylenations.
It uses iodine and aluminum powder to make the AlI3 in situ.
Only drawback is that is uses rather much iodine that is a bit expensive and also it uses Acetonitrile, MeCN, as a solvent, something maybe not
everyone have.
Maybe most of the iodine can be recovered, i would guess so.
But other than that it seem very good, check out the paper.
