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Author: Subject: Demethylation of Vanillin and Eugenol
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[*] posted on 3-11-2019 at 14:08

One of the diol side products I've been preparing, when methylenated yields an oil with an unusually high density. A pleasant fragrant oil, an aroma similar to sassafras but different. I had initially assumed it to be dihydrosafrole owing to its similarity. It doesn't absorb Br2 as quickly or as much as eugenol does. It will absorb Br2, but only slowly. Suggesting ring bromination rather than allyl.

It has a density of about 1.29 g/cc. I have about 8 ml of it left, the diol compound wasn't prepared from bromoeugenol, but from eugenol.
I suspect it's 3,4 methyledioxy indane, and the diol compound being 4,5-indanediol (predicted density of 1.3 g/cc).
Its only generated when the reaction (demethylation) conditions are hot, iirc about >90 C.
I can't find any data on the methylenated indanediol.
Assuming this is what it is, is there likely a practical way to revert the indane back to the allyl form?
I'm assuming not, so will be aiming to avoid its synth in the first place.
Next demethylation experiment will be with isoeugenol in place of bromoeugenol/eugenol, will be interesting to see the difference.

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[*] posted on 7-11-2019 at 18:07

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[*] posted on 29-3-2020 at 12:25

Quote: Originally posted by CycloKnight

Could use a little help. I'm looking for information on this dibenzoyl derivative, its probable structure, etc, and if it can be easily reverted to the 4-allylcatechol. Any feedback appreciated, thanks.

(ii) Benzoyl derivatives (benzamides)
Suspend 1 g of the amine in 20 mL of 5% aqueous sodium hydroxide in a well-corked flask, and add 2 mL benzoyl chloride (fume hood!), about 0.5 mL at a time, with constant shaking. Shake vigorously for 5 - 10 min until the odour of the benzoyl chloride has disappeared. Ensure that the mixture remains alkaline. Filter off the solid derivative, wash with a little cold water and recrystallise from ethanol.

Experiment 10 Preparation of the benzoate of phenol.


Many phenols yield crystalline benzoyl derivatives with benzoyl chloride in the presence of sodium hydroxide (Schötten-Baumann method).


To the phenol (0.5 g) is added 5% sodium hydroxide (10 mL) in a well-corked boiling tube or a small conical flask.Benzoyl chloride (2 mL, density 1.21 g cm-3) is added in small quantities at a time, and the mixture shaken vigorously with occasional cooling under the tap or in ice water.
After 15 minutes the solid benzoate separates out: the solution should be alkaline at the end of the reaction; if not alkaline, or if oily, add a solid pellet of sodium hydroxide and shake again.Collect the benzoate, wash thoroughly with cold water, and recrystallise from ethanol (NO FLAMES!). Carry out the tests for phenols and esters (p 57).

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