flopfish
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Demethylation of Eugenol
Well,
This is my first proper attempt at this. And my first post.
I have attached some images for which I have questions:
In the big flask, is 200ml xylene, 25g Eugenol, and 26g AlCl3.
As soon as the AlCl3 touches the eugenol it gets angry and red/brown. Is this normal? I molecular drives the shit out of my xylene so I know it was
dry.
When I add the pyridine (60g), it looks like it’s about to explode. And creates quite a bit of smoke.
I did a second attempt with 5g Eugenol in 20ml toluene, which I dried to kingdom come, added 5g AlCl3, and 5ml pyridine.
Again, the reaction was slower to start but after a few mins the AlCl3 seemed to react with the eugenol and turn everything red brown.
I added the pyridine a bit too fast and it created a hell of a lot of smoke.
Anyway, I just wanted to document my progress and compare this to anyone else’s experience.
[Edited on 20-8-2024 by flopfish]
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clearly_not_atara
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You basically need an inert atmosphere to do this rxn.
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Mateo_swe
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Have you tried the procedure with AlI3?
Gram-Scale Synthesis of 4-Allylcatechol (4)
To a mixture of AlI3 (38.5 mmol, 1.1 equiv) prepared in situ from Al
powder (2.721 g) and I2 (14.657 g, 57.75 mmol) in MeCN (250 mL)
was added DMSO (6.836 g, 87.5 mmol, 2.5 equiv). The mixture was
stirred for 0.5 h at 80 °C, before a solution of eugenol (3; 5.746 g, 35
mmol) in MeCN (20 mL) was added dropwise over 1 h. After stirring
for 18 h at 80 °C, the reaction mixture was quenched with aq 2 M HCl
(50 mL), and extracted with EtOAc (3 × 100 mL). The organic phases
were combined, washed with sat. aq Na2S2O3 and brine, and dried
(anhyd MgSO4). After filtration, the organic solvents were removed on
a rotary evaporator, and the residue was purified through flash column
chromatography (eluent PE/EtOAc 4:1) to give 4; yield: 4.968 g
(94%).
I add the paper.
[Edited on 2024-8-29 by Mateo_swe]
Rename to xxx.pdf
[Edited on 2024-8-29 by Mateo_swe]
Attachment: phpRxKTAw (430kB)
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clearly_not_atara
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^well that's certainly something.
So many failures doing this rxn without nitrogen I have to wonder why this version was different. A couple hypotheses:
- heating the MeCN to 80 C (bp 82 C) for 30 minutes before adding eugenol generates a "vapor blanket" that reduces oxygen intrusion into the rxn
mixture
- oxygen is generally less soluble in polar solvents like MeCN vs nonpolar solvents like toluene
- iodide is a pretty good antioxidant and radical scavenger
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