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Author: Subject: Benzoquinone from Paracetamol
tupence_hapeny
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Benzoquinone from Paracetamol

I have recently searched for both hydroquinone and benzoquinone in this country and the OTC sources of these interesting compounds have basically died. Then, when I typed paracetamol and benzoquinone into google I noticed that the toxicity of paracetamol is caused by the conversion of acetaminophen into N-acetyl-p-benzoquinone imine via oxidation.

Therefore my question is, whether it is possible to further oxidise (and cleave) the n-acetyl-imine from the benzoquinone, leaving the benzoquinone to be used (or reduced to the hydroquinone) as and when required?

I have no idea as to whether or not this is possible, I am basically well behind the chemists on this board. My only interest is basically whether it is or is not possible to transform easily available OTC chemicals to their overly restricted kissing cousins, thereby providing an OTC route for the chemically challenged amongst us.

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YT2095
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I dont know about the extraction, but find it hard to believe you cant get Hydroquinone???

have you searched Photography shops and Skin Whiteners for black people?

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not_important
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And how are you proposing to obtain N-acetyl-p-benzoquinone? Popping pain meds isn't useful, 2/3 to 90% is pissed out as glucurosulfates, N-acetyl-p-benzoquinone is a minor metabolite, and if your liver is working is quickly further metabolised.

Extract acetaminophen/paracetamol with boiling water, filtering out the trash. Cool and filter to collect the product. Hydrolyse with 10% H2SO4, 5 minutes in the microwave under an inert atmosphere. Cool, neutralise excess H2SO4, oxidise using a modified version of the sodium chlorate + V2O5 catalyst method, dichromate oxidation, or other method.

[Edited on 4-4-2007 by not_important]
Nicodem
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 Quote: Originally posted by tupence_hapeny My only interest is basically whether it is or is not possible to transform easily available OTC chemicals to their overly restricted kissing cousins, thereby providing an OTC route for the chemically challenged amongst us.

Hydroquinone and p-benzoquinone are both way simpler to just buy given that they are completely OTC. Extracting acetaminophen from pills to get enough for an oxidation where the reagents required would be much less OTC, seems to miss your main idea, doesn't it? Perhaps making something that is not OTC form acetaminophen would make sense, but making two widely available chemicals from another available chemical is a bit irrational.

But essentially, yes, you can oxidize acetaminophen to p-benzoquinone.

…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)

tupence_hapeny
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Ummm, I didn't say I couldn't get hydro/benzoquinone, it's just that what I can get is way overpriced, seriously impure and a minor constituent part of the products I can get. As I am not a great fan of extraction from expensive substances where it is possible to synthesise the same compound from purely otc products - in what hopefully would be a decent yield - I would prefer to go that way. I have been unable to find a single source in Australia that is willing to provide even a miniscule quantity of pure hydro/benzoquinone, whereas I have access to some basic oxidants and shitloads of paracetamol (which is a major part of the tablets - 500mg).

So, taking it as accepted fact, I am actually irrational, how should one proceed if one wished to do so?

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not_important
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2.5 cents - already gave a thumbnail outline.
tupence_hapeny
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oops, half asleep

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PlatinumCal99
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Here in the US it is possible to get hydroquinone but not para-benzoquinone.
One synthesis I was reading involved oxidizing the hydroquinone to para-benzoquinone with chromium trioxide in acetic acid.
Does anyone know what the mechanism of this reaction is? Does the chromium trioxide just form chromic acid and decompose back to chromium trioxide and H2?
If someone with a greater understanding can post back that would be great.
PainKilla
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http://www.erowid.org/archive/rhodium/chemistry/benzoquinone...

I2/H2O2 in water works wonders.

not_important
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 Quote: Originally posted by PlatinumCal99... One synthesis I was reading involved oxidizing the hydroquinone to para-benzoquinone with chromium trioxide in acetic acid. Does anyone know what the mechanism of this reaction is? Does the chromium trioxide just form chromic acid and decompose back to chromium trioxide and H2? If someone with a greater understanding can post back that would be great.

Uh - a strong oxidiser forming H2 and not being consumed? I'd sue my inorganic chem teacher if I were you.

The Cr(VI) gets reduced to Cr(III), just like in dichromate reactions.
benzylchloride1
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In an attempt to alter the synthesis of p-chloranil from p-acetamidophenol, I ended up producing p-benzoquinone in a yield of 80%. I was trying to conserve nitric acid and see what effect low reaction temperatures has on this oxidation reaction. I started with p-acetamidophenol recrystallized from tylenol tablets, dissolved 15g of the recrystallized material in 100 mL of concentrated hydrochloric acid and then I added 33 mL of concentrated nitric acid. The foam produced by the reaction filled a 1000 mL beaker. The mixture was stirred with a glass rod and allowed to sit in a snow drift for 3 hours. Yellow crystals of the crude quinone formed. 300 mL of cold water was added with stirring and the mixture was filtered. The filter cake was pressed to remove excess water and the benzoquinone was dissolved in about 200 mL of 91% 2-propanol. The solution was heated to boiling and allowed to cool. Yellow, needle shaped crystals of p-benzoquinone filled the liquid upon cooling. The crystals were filtered off, pressed and allowed to dry for one day. The final percentage yield was 80% of theoretical. The melting point was taken with a Haake-Buchler melting point apparatus, the product melted at 117 celsius one degree above the value in the CRC Handbook of Organic Compound Identification, due to a fairly rapid heating rate. The benzoquinone was instantly decolorized by bisulfite solution, and when added to a solution of hydroquinone, peacock green crystals of quinhydrone formed. I plan on making some chloranil in the near future for dehydrogenation reactions. The oxidation of aromatic compounds with aqua regia could be a very useful method for the synthetic amateur chemist.

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IPN
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I gave the aqua regia oxidation a go after the results from a dichromate/sulfuric acid oxidation of paracetamol to quinone weren't very satisfying.

Using pretty much the same amounts of reagents as benzylchloride1 I added 15g of pure paracetamol to 100ml of concentrated hydrochloric acid (new bottle so should be close to 37%). This was stirred overnight (accidentally, I kind of forgot about it while doing other stuff..) and formed a slurry of white fine precipitate. The slurry was cooled outside for approximately 1h (-5C outside) and poured into a 2l beaker. 40ml of 13.5M nitric acid was added in one go with some swirling. This caused the slurry to turn yellow. The color quickly deepened and turned more orange and suddenly the slurry changed to a paste and a vigorous reaction ensued which filled the beaker half full with foam and released a cloud of nitrogen oxides. The beaker was then left in the snow outside for a few hours.
The foam was diluted with around 1/4l of water and stirred for a few minutes while setting up the vacuum filtration equipment. The product was filtered and washed with a few ml of water on a glass frit funnel. It looked almost like picric acid, maybe a little lighter yellow. After being sucked dry for 5min or so it was dissolved in 200ml boiling isopropyl alcohol with 10% water (that is 180ml dry IPA + 20ml H2O) and left to crystallize after full dissolution.
The recrystallized product was filtered with suction and washed with 20ml cold 50/50 IPA/water.

Few pictures of the product can be found here.

So this certainly seems like a good method to make some quinone if you don't need much of it and can't find hydroquinone anywhere. Just be wary of the toxic nitrogen oxides!
un0me2
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Hypochlorite with acetaminophen/tylenol/paracetamol/etc. gives a combination of the hydroquinoe the the related imine, which would probably give good yields of the sought after hydroquinone on acid hydrolysis.

[Edited on 4-2-2010 by un0me2]

Attachment: Bedner.MacCrehan.Transformation.Acetaminophen.Hypochlorite.pdf (135kB)

UnintentionalChaos
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 Quote: Originally posted by IPN I gave the aqua regia oxidation a go after the results from a dichromate/sulfuric acid oxidation of paracetamol to quinone weren't very satisfying. Using pretty much the same amounts of reagents as benzylchloride1 I added 15g of pure paracetamol to 100ml of concentrated hydrochloric acid (new bottle so should be close to 37%). This was stirred overnight (accidentally, I kind of forgot about it while doing other stuff..) and formed a slurry of white fine precipitate. The slurry was cooled outside for approximately 1h (-5C outside) and poured into a 2l beaker. 40ml of 13.5M nitric acid was added in one go with some swirling. This caused the slurry to turn yellow. The color quickly deepened and turned more orange and suddenly the slurry changed to a paste and a vigorous reaction ensued which filled the beaker half full with foam and released a cloud of nitrogen oxides. The beaker was then left in the snow outside for a few hours. The foam was diluted with around 1/4l of water and stirred for a few minutes while setting up the vacuum filtration equipment. The product was filtered and washed with a few ml of water on a glass frit funnel. It looked almost like picric acid, maybe a little lighter yellow. After being sucked dry for 5min or so it was dissolved in 200ml boiling isopropyl alcohol with 10% water (that is 180ml dry IPA + 20ml H2O) and left to crystallize after full dissolution. The recrystallized product was filtered with suction and washed with 20ml cold 50/50 IPA/water. Few pictures of the product can be found here. So this certainly seems like a good method to make some quinone if you don't need much of it and can't find hydroquinone anywhere. Just be wary of the toxic nitrogen oxides!

Get a melting point on your material. I tried this and found that overheating did manage to contaminate the p-benzoquinone with chloranil, even after recrystallization. My melting point was 10 degrees too low.

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Taoiseach
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http://www.versuchschemie.de/topic,13634,-Synthese+von+p-Ben...

User
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For the people that have a hard time reading german.

Nice write up, i like the use of otc sources.
I feel some resistance here and there but it is no better or worse than TNP from asprin

What a fine day for chemistry this is.
mr.crow
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 Quote: Originally posted by Taoiseach http://www.versuchschemie.de/topic,13634,-Synthese+von+p-Ben...

I love versuchschemie

They mentioned nitrate salts. That would be easier to get and maybe a less vigorous reaction.

No one has addressed the catalytic I2 route yet. Its probably not a powerful enough oxidizer for the nitrogen.

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xwinorb
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potassium dichromate

I have before made p-benzoquinone using the SpiceBoy recipe, see reference given by Painkilla in this same thread.

You need hydroquinone, sulfuric acid and potassium dichromate, all very easy to get and unexpensive. The reaction is easy and fast, done in 2 h or so. Sodium dichromate can be used also. Don't need to dissolve all the potassium dichromate, it will not. Just drip it in anyway.

Workup, cool it to 5 deg C or close. Filter, if too wet use Saran Wrap when filtering, or squeeze filter cake with a spoon. You will get a dark green solid paste. Filter it as dry as you can.

Can use as it is, just dry it a few days in a closed container or vacuum dessicator with drierite or any other dessicant. It has a substantial ammount of water and other impurities, but for most purposes it works fine. Yield is tipically 60 % or close to that. I mean here, pure p-benzoquinone yield. Just by weight you might have close to 100 % or even higher, but remember it is not pure p-benzoquinone. Also, the impure p-benzo is water soluble.

Assume your yield to be 60 %, calculate how much p-benzoquinone is in and scale accordingly.

If you want purer p-benzoquinone, dissolve it in the minimum ammount of DCM, filter.

You will get a thin layer of green-black solid in the filter cake, and the filtrate has two layers. The bottom layer is DCM + p-benzo ( orange color ), and the top layer is watery, almost black. Separate, keep the bottom layer.

Place in a large boiling flask, boil out the DCM first at RT then with aspirator vacuum.

Evaporate the DCM. It wil start to boil at a higher temperature than the DCM boiling point, you will need aspirator vacuum or similar.

Apply vacuum gently first, then increase. When it becomes a orange paste, bubbling, stop, pour out of boiling flask into a pyrex dish or other shallow container.

Mix with a spoon till most of the DCM evaporates. Better if you have a fume hood, but can be done without it.
It will look orange first, but will become yellow as soon as the DCM evaporates out.

You will haver nice, yellow p-benzoquinone xtals, with just a hint of green color.

The work up is from the Organic Synthesis. They use benzene. I have tried it also, but DCM is much better. Slightly modified.

If you want really pure p-benzoquinone, then from here sublimate or steam distill. I have never done it though.

The non-purified, dark green stuff works fine for most purposes. Dry it well before using.

Suggested to use gloves, handle and pour it carefully, avoid spilling.
Taoiseach
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Quote: Originally posted by mr.crow
 Quote: Originally posted by Taoiseach http://www.versuchschemie.de/topic,13634,-Synthese+von+p-Ben...

I love versuchschemie

They mentioned nitrate salts. That would be easier to get and maybe a less vigorous reaction.

No it is very vigorous. I tried it with ammonium nitrate instead of HNO3. Its an amazing reaction - at first the mixture doesn't do anything but all of a sudden it foams up like crazy and gives off thick fumes of nitric oxides. Cooling is crucial to avoid chlorination, which leads to a product contaminated with chloranil.
jwarr
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I don't understand why anyone fools around with this junk when you can easily prepare p-Benzoquinone from hydroquinone in quantitative yields via catalytic reduction w/ NO2. Hell, if you don't like using gases just use sodium nitrite w/ a drop of HCl.
IPN
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Well if you would have read the thread you would know that for some, hydroquinone is not that easily available so other ways of synthesis are needed.
And also if only small amounts are needed, what is the problem with this synthesis?
jwarr
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"Unique Photo" sells 500g of hydroquinone for 15.62 USD, they ship internationally. What is the problem?
mfilip62
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Yes in USA,and shipping is ten times the price + no way it can be imported for hobby chemist.
Even Kodak branch here doesn't sell it!
watson.fawkes
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 Quote: Originally posted by mfilip62 Yes in USA,and shipping is ten times the price + no way it can be imported for hobby chemist. Even Kodak branch here doesn't sell it!
"No way" is a relative term, given the plentiful existence of black markets and smuggling. Assuming you want a rather more legitimate route, you'll have to state what jurisdiction you're in so that somebody with experience can help you.
mfilip62
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HNO3/HCl method seem to be good and working,but only issued being contamination with chloranil...

IS there way to completely remove chloranil,convert it to p-beznoquinone or is there some similar reaction
(HNO3/any other acid for instance) that can produce p-benzoquinone from paracetamol without chloranil contamination
which is too similar in properties and apperance thus making it hard to get rid of and keep the yield!?
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 Sciencemadness Discussion Board » Fundamentals » Organic Chemistry » Benzoquinone from Paracetamol Select A Forum Fundamentals   » Chemistry in General   » Organic Chemistry   » Reagents and Apparatus Acquisition   » Beginnings   » Miscellaneous   » The Wiki Special topics   » Technochemistry   » Energetic Materials   » Biochemistry   » Radiochemistry   » Computational Models and Techniques   » Prepublication Non-chemistry   » Forum Matters   » Legal and Societal Issues   » Detritus   » Test Forum