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Author: Subject: demethylation arylalkenes
Mn2Dc
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[*] posted on 20-11-2017 at 16:18
demethylation arylalkenes


cann anhydrous AlCl3 be succesfully used for the demethylation of anisole to phenol ? I've read that pyridine HCl is one way for ringmethoxylated aromatics ? But what about AlCl3, maybee some info found on it, but I like some details, I know that AlCl3 cann diffuse(?) the methyl group of toluene to one identical molucule forming one xylene and one benzene. I dont know if you call this a chemical reaction actually and I know this has nothing to do with my main question about demethylating, but found intresting that AlCl3 cann remove methylgroups, so what about ring methoxylated species such as anisole or better eugenol ? I know that AlI3 is used. But will Aluminium(III)Chloride will act the same way like Alluminium(III)Iodide or does the type of halogen really matter in this application ?

sorry for my awfull way of writing :-)


:o Text




Ive never did any school in chemistry lessons but learned it all by my self and the internet to expand my knowledge on chemical mechanics of atoms and organic chemistry.




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Dr.Bob
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[*] posted on 20-11-2017 at 17:55


I'm not familiar with AlCl3 demethylating aryl methoxy groups. I agree that pyridine/HCl can work, but I would go with lithium iodide/pyridine (or another higher boiling solvent), BBr3, thiols, and I think even excess MeMgBr refluxed can also demethylate anisoles. Many of these are essentially an SN2 reaction on the methyl group, where the halogen or other nucleophile attacks/displaces the phenol leaving group to form bromomethane or such.

But a simple search for "aluminum chloride demethylation" in Googles does find some results, many in less academic sources, that might help. Most appear to use AlCl3 along with ethanethiol, a sure way to get your neighbors to hate you and the fire Dept/gas company to your house.

One good result is below

http://lego.chemistry.tripod.com/various/demethylation.html
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Mn2Dc
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[*] posted on 20-11-2017 at 19:02


Ok , So Lithiumchloride in dimethylformamide is also the option for demethylation of eugenol, that is exactly a good experiment for my research since eugenol is available for me as cloves oil ! and DMF as the solvent is not available to me, Can a organic mixture of cyclic-hydrocarbons like white spirit or maybe ethylacetate be used as substitution for DMF,, I like OTC experiments. And dissolving lithium metal from old batterys in Hydrochloric acid result for some LithiumChloride ? Should the solvent have to have a high boiling point, and is this the reason the use pyridine and AlCl3 for demethylation of ring substituted aromatics ? Thankyou !:D
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clearly_not_atara
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[*] posted on 20-11-2017 at 21:35


Propylene carbonate would be the closest thing I can think of to a DMF replacement and it's mostly OTC. Propylene glycol and urea are refluxed over zinc oxide for a few hours and the propylene carbonate is distilled coming over at about 240 C.

However, I'm not sure we should be discussing eugenol demethylation...




[Edited on 04-20-1969 by clearly_not_atara]
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wg48
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[*] posted on 21-11-2017 at 02:05


Perhaps this patent on demethylation of vanillin may help you.

It uses mild conditions with any number of aromatic compounds and alluminium bromide made insitu from alluminium and bromine.

https://www.google.com/patents/US2975214

Do report back if you get it to work as I was thinking about using it.
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