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Author: Subject: Separating Benzoquinone from Hydroquinone
anotheronebitesthedust
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[*] posted on 25-9-2010 at 09:35
Separating Benzoquinone from Hydroquinone


Recently I Recrystallized 50 grams of benzoquinone from a mixture of green benzoquinone (quinhydrone???) and to say the least it was messy and a pain in the arse.

Are there any solvents that dissolve hydroquinone and not benzoquinone? Or vice versa?

Here's what I found so far, mostly from Wiki:

Hydroquinone:
6g/100ml H2O
Sparingly soluble in DCE
From what I can interpret it is also sparingly soluble in DCM and Toluene

Benzoquinone:
Sparingly soluble in H2O
Slightly soluble in Petroleum Ether
7g/100ml Toluene
3.6g/100ml DCM
5g/100ml DCE
Soluble in Acetone
Very soluble in Ethanol, Benzene and Diethyl Ether

http://www.freepatentsonline.com/4963234.html
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not_important
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[*] posted on 25-9-2010 at 10:33


You'll want to read the article here http://preview.tinyurl.com/2wfxapd

Solutions of hydroquinone and benzoquinone form the bi-molecular complex quinhydrone, a dark green low solubility material. Not real easy to separate, the best way is to drive the complex to full reduction (for hydroquinone) or oxidation (for benzoquinone) to get just one or the other, then recrystallise.
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kclo4
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[*] posted on 26-9-2010 at 10:13


Quote:
the best way is to drive the complex to full reduction (for hydroquinone) or oxidation (for benzoquinone) to get just one or the other, then recrystallise.


I am having the same problem as the OP.
I want only/primarly the hydroquinone. What would an effective method in reducing the benzoquinone be? I'd imagine mixing it will fine Fe and dripping HCl on it would be one method, however I strongly dislike doing that reaction.

it seem like the product Iron Out, which releases SO2 and contains various bisulfites and dithionite salts of sodium might work?
This, http://www.chemie.uni-regensburg.de/Organische_Chemie/Didakt... shows that sulfurous acid turns benzoquinone to quinhydrone. Would it continue to turn it into hydroquinone?




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Boffis
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[*] posted on 21-1-2021 at 08:32


I acquired some very old benzoquinone a few years ago and recently I have been purifying it by steam distillation. This works well but I only get about 50% recovery and the residue in the flask is the gloop from hell. It is removeable but what a job! I wonder what it can be. Assuming the dark green colour of the crude benzoquinone is due to quinhydrone what happens when it is steam distilled? Does quinhydone survive steam distillation? Would be better to reduce or oxidize the crude material first and then process the result. Oxidation would probably be preferable sinc steam distillation is very simple and efficient.
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pip
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[*] posted on 31-1-2021 at 17:22


Vanadium pentoxide and hydrogen peroxide methods work well. If it stalls gently heat and it’ll finish sometimes from green to yellow instantly. Your biggest problem will be the watering eyes that stuff is irritating.

[Edited on 1-2-2021 by pip]
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