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un0me2
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Mate, I am NOT GOING TO IMPORT ANY CHEMICALS - I have been busted going the import route, I was doing nothing wrong, but it took me months to sort
that shit out. I still don't have any chance of getting my glass/chemicals/laptop/pc back...
Good luck if you import to this Cunt Tree
However, back on subject, from what I can see (There is at least one reference on its use on methoxyanilines) Fremy's Salt will do the job.
There is a great writeup on Orgsyn where it is prepared from sodium nitrite, SO2, sodium carbonate and electrolysis with a Stainless electrode.
That should allow for the preparation of p-methoxyphenol from p-methoxyaniline (2 min MW/HCl will remove the AcOH group from the amine according to at
least one report). Methylation, followed by hydrolysis & oxidation of the p-methoxyaniline to the p-methoxyphenol is the ONLY route I know of that
will give solely the monomethoxyhydroquinone.
[Edited on 5-7-2010 by un0me2]
[Edited on 5-7-2010 by un0me2]
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JohnWW
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What jurisdiction do you live in, Unome2? If I were you, I would be looking at emigrating to a less Fa$cist country or $tate.
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peach
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do you specifically need hydro / benzo unome? how much are you talking about?
are you trying to make a ketone?
[Edited on 8-7-2010 by peach]
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mfilip62
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Hydro/benzo are great as selective oxidants.
I used them a lot in peroxide research, just when I started to do some research on
HMDT analogues they became banned and extremely hard to find.
That is because retarded people used them as "wonder medicine" a lot and irresponsibly for
minor skin imperfections causing cancer, mutilations...
IMHO that is just evolution working, let the bastards die instead of banning something useful!!
Anyway, photographers got pissed and now it is good business selling this stuff!
Ketone is pretty wide deffinition, you mean THE ketone from THE olefin or!?
I am not very familiar with that kind of chemistry but I am sure it could be used for that,
but as long as I remember this procedure uses some
H2O2 and formic/acetic acid, at least procedure I read about...don't take me by the word!
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peach
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I'm reasonably sure benzo / hydro became a problem because drug labs were all using it in their wackers; after reading certain google searches.
The wacker / peracid / oxidizing salt / halide + base method will work for a huge number of ketones. You don't need to use benzo for a wacker to make
a ketone. Some of them use O2. Anything that'll supply an oxidative potential to the CuCl2 / PdCl2 will work. There are a huge number of ways to a
ketone; contrary to your suggestion.
[Edited on 8-7-2010 by peach]
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mfilip62
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As I said I am not very fammiliar with that field of chemistry.
Just read some searches on that synth.,looks interesting and plausible but
salt formation seems to be waste of time and product.
You think that bubbling O2 instead of using p-benzo in this report would
work?(just google it,it is star something synth.)
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un0me2
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I just had a good look around and found some interesting procedures, most of which use only fairly innocuous, easily sourced chemicals, to give us a
possible route at 2-nitro-4-methoxyaniline, which according to the people here is fairly simply made, although their yields are not stated. That set me looking further, which led me to this paper (attached) which states
that extremely good yields can be had by adding H2O2 along with the nitrite/HCl to affect the nitration.
From there, I was looking at a link Nicodem provided for the diazotization of m-Nitroaniline to m-nitrophenol and wondering, could we use that to end up with 2-methoxy-5-hydroxynitrobenzene?
If so, that would open up a whole new route to the 2C series that is so beloved of so many without any majorly difficult-to-acquire chemicals.
Attachment: Matsuno.etal.A.New.Nitration.Product.3NO2.4Acetamidophenol.Obtained.from.Acetamidophen.with.Nitrous.Acid.pdf (143kB)
This file has been downloaded 953 times
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mfilip62
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Back on main subject...
I tried synthesis and it works quite well!
First time I botched it because I accidentally made wrong blend of acids.
(HNO3 3 : 1 HCl)I figured out something is wrong when I got big mushroom cloud of NO2 and
mosquitoes stoped to sting that night... 
Anyway, in next synth. I got cca. 7g of pure dry crystals from 15g of paracetamole.
Is this good!?
I skipped reflux of p-benzo in alchohol and filtering of boiled solution since it completely dissolved in 200ml of denat. ethanol
with light heating without crude crap leftover and it is obvious killer of the yield.
There were far less crystals than in pics of IPN synth. and they were all at the bottom.
First I let them at the room temp. for 24h and then 12h in the freezer(looks like everything
was already there at the room temp.)
I have few questions:
Is the black liquid they recrystallized them from worth effort!?I poured in few ml of CH2Cl2 and it seems to be miscible?! Is this normal?!
Is 200ml of ethanol too much!? On versuchtchemie they use 200ml isopropyl alcohol so is it more soluble in ethanol than in isopropyl !?
On next paracetamole extraction crystals became pink upon drying !
Is this normal!? It was on the direct sunlight for a day on extremely hot day with high UV index.
Thanks
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Alastair
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Quote: Originally posted by Taoiseach  | | Quote: Originally posted by mr.crow |
I love versuchschemie 
They mentioned nitrate salts. That would be easier to get and maybe a less vigorous reaction.
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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. |
as far as i understand german ''aber kein Ammoniumnitrat'' is BUT NOT AMMONIUM NITRATE (ie sodium instead of ammonium).
Also i found that para quinone can be reduced with ascorbic acid in water (vitamin C, another otc). this reaction works better in less acidic
conditions. (yield hydroquinone)
[Edited on 27-10-2011 by Alastair]
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Scr0t
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I've attempted this method of preparing p-Benzoquinone and compared it to Benzoquinone prepared via HQ/H2O2/I2 by using both as reagents to prepare
5-hydroxy-1,3-benzoxathiol-2-one as described under PIHKAL #167.
Results were markedly different.
Benzoquinone prepared by this method produced a compound that was close in mp (depressed by a couple of Kelvin) however other differences were noted
e.g. slightly lower solubility in IPA and it was more difficult to form large crystals from IPA but otherwise closely resembled Benzoquinone.
Apart from a few other differences in observations during the course of the reaction with thiourea the end product did not form large needles of the
Benzoxathiolone but formed an off-white powder and did not have a melting point (~170°C) but simply carbonised >200°C.
This leads me to think that the material so obtained is not primarily Benzoquinone but perhaps predominately chlorinated intermediates to Chloranil.
The reaction is not easily controlled by an ice-salt bath and can briefly peak at a Temp >40°C on the 15g scale used in the versuchschemie
procedure.
Perhaps Aqua-regia is not a good choice of oxidant here.
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Nicodem
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| Quote: Originally posted by Scr0t | I've attempted this method of preparing p-Benzoquinone ...
Perhaps Aqua-regia is not a good choice of oxidant here. |
Just to make things clear, are you referring to the procedure developed by benzylchloride1?
Thanks for sharing your results.
Interesting coincidence that the melting points are so close. Anybody has the time to review the mp of the most likely candidates? It would be
interesting to see what the actual product is. It appears to be a substituted quinone.
…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)
Read the The ScienceMadness Guidelines!
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Scr0t
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Yes.
A similar or the same procedure is also posted on versuchschemie.de.
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Nicodem
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| Quote: Originally posted by benzylchloride1 | | 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 lit. mp of 2,6-dichloro-1,4-benzoquinone is 122-124 °C or less (depends on the source), while that of 1,4-benzoquinone is 113-115 °C. So, the
slightly higher mp might have not been a mistake due to a rapid heating rate. Since benzylchloride1 does not report the melting interval, it is hard
to estimate, if his product was a pure substance or perhaps he obtained a slightly impure 2,6-dichloro-1,4-benzoquinone which would explain the 117
°C mp due to its depression.
Given the nature of the oxidant used, it would be unusual to obtain nonchlorinated 1,4-benzoquione as the main product. Finally, taking into account
the derivatization results reported by Sc0t, I would say that the identification of the product obtained in this procedure requires a revision.
Certain references support the idea of 2,6-dichloro-1,4-benzoquinone as the product of chlorine reagent based oxidations of substrates that could go
through related intermediates:
| Quote: | Chem. Abstr. 69: 58917
The soln. of NaClO2 (0.03 mole in 10 ml. H2O) was added dropwise during 1-2 hrs. into a stirred mixt. of 0.01 mole phenol and 25 ml. 2N H2SO4 or 2N
HCl. The temp. was kept at 0-5° to give 2,6-dichloro-p-benzoquinone (I), m. 119-20°, as a main product, some chloro-p-benzoquinone, and traces of
p-benzoquinone. Similarly, I was obtained from 2,6-dichloro-, 2,4-dichloro-, and 2,4,6-trichlorophenol in the yields 84.9, 32.5, and 59.8% resp.;
2,5-dichlorophenol gave 34.5% 2,5-dichloro-p-benzoquinone, m. 160-1°, and traces of trichloro-p-benzoquinone. The results were independent of the
inorg. acid used. |
Another example: In the chlorination of phenol with NaClO3/HCl, a 1:1 mixture 2,6-dichloro-1,4-benzoquinone and 2,5-dichloro-1,4-benzoquinone was
obtained (Bulletin of the Korean Chemical Society, 32, 472-476; DOI: 10.5012/bkcs.2011.32.2.472). Anisole gave 2,6-dichloro-1,4-benzoquinone
as the second major product, right after 2,4,6-trichloroanisole.
…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)
Read the The ScienceMadness Guidelines!
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JJay
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I was recently looking through papers for a method to convert acetaminophen to hydroquinone and found several possible routes, all of which go through
p-benzoquinone. I like the idea of doing it with hydrogen peroxide in sulfuric acid, but oxidation by aqueous permanganate is well researched and
apparently produces a quality product without the need for much purification.
Attachment: 01932691003656938.pdf (369kB)
This file has been downloaded 795 times
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JJay
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I've been meaning to try this out for a few weeks now, and I'm planning on getting started tonight. I made a few changes from the original procedure
from the PDF above. In particular, the reaction has been scaled up by a factor of 10. Also, instead of using chloroform, I tentatively plan to
substitute ether because it evaporates more readily and I don't have any chloroform prepared. Also, I think ether probably dissolves benzoquinone more
readily. In addition, I hope to use less solvent than in the original procedure to avoid wasting solvent and to minimize the impact on the
environment.
Acetaminophen is not very soluble in water, so reaction conditions are necessarily dilute. I'm quite sure they don't have to be as dilute as in the
original procedure, though, and the stoichiometry looks off, but I'd like to get the synthesis working before doing any further optimization.
---
Proposed Procedure for Preparation of Benzoquinone
Extraction of acetaminophen from OTC pain reliever medication
Crush 10x500 mg acetaminophen pain reliever pills to a fine powder and place in a 250 mL beaker. Add 100 mL of methanol and with strong stirring,
slowly heat to just boiling over 30 minutes. Allow to cool to room temperature and gravity filter. Cool the resulting solution to 0 C and then add 100
mL of cold water in small portions. Vacuum filter the product with a glass sinter and extract most of the water on the pump, then dry the product in a
dessicator over anhydrous calcium chloride before weighing and placing in a suitable storage container.
Oxidation of acetaminophen
Dissolve 1.20g acetaminophen in 500 mL room temperature distilled water with strong stirring in a 1000 mL beaker. Dissolve 4.00g potassium
permanganate in 250 mL distilled water. With strong stirring, add the permanganate solution to the acetaminophen solution and allow to react for
several hours or until complete. Gravity filter, and add to a separatory funnel. Extract with 3x10 mL diethyl ether. Combine the ether extracts and
wash with 3x50 mL distilled water. Dry the ether solution over a few grams of anhydrous magnesium sulfate. Place the ether solution in a dish and
allow it to evaporate at room temperature. Remove and weigh the product, and place in a suitable storage container.
Edit: After reviewing the literature, I tentatively decided to substitute ether instead of DCM for chloroform. I'm still trying to decide exactly what
solvent to use.
[Edited on 13-1-2017 by JJay]
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JnPS
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That's an excellent short write-up JJay, I'll definitely be trying that before this semester starts, what was your yield when using ether? I'll try
using DCM and we could compare the solvent choices. I'm out of ether from chlorophyll extractions 
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JJay
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| Quote: Originally posted by JnPS | | That's an excellent short write-up JJay, I'll definitely be trying that before this semester starts, what was your yield when using ether? I'll try
using DCM and we could compare the solvent choices. I'm out of ether from chlorophyll extractions |
Thanks. I haven't tried it yet, and I'm still trying to decide for sure what solvent to use. Right now, I'm watching acetaminophen pills dissolve in
methanol on a hotplate. They seem to dissolve quite readily (I'm just using the generic Equate brand), so minimal crushing is required.
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JJay
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I have a still slightly-warm solution of acetaminophen sitting in one of my three oldest ground-glass Erlenmeyers. I got impatient and filtered the
solution through a cotton ball twice, and the solution is milky. I'm not 100% sure what the cause of the milkiness is... could be talc, titanium
dioxide, stearic acid, corn starch, or any number of other substances. I'm going to let it cool overnight before proceeding. Hopefully the milkiness
will settle.
Edit: The proposed extraction method didn't work. I think it could work, but the methanol solution should be saturated, and that requires a lot more
than 5g of acetaminophen in 100mL of methanol.
I did some searching around and found a couple of procedures for extracting acetaminophen from pills:
BlackDragon2712 obtained very nice-looking crystals using 95% ethanol: lhttp://www.sciencemadness.org/talk/viewthread.php?tid=65167#pid437040
The RSC wrote a guide for educators on acetaminophen that describes an extraction with acetone: http://www.rsc.org/learn-chemistry/content/filerepository/CM...
The crystals in BlackDragon2712's pictures look awfully nice, so I think I'll adapt his procedure. I suspect I can get away with using slightly less
ethanol, but first I'm going to try replicating his procedure exactly.
[Edited on 14-1-2017 by JJay]
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JnPS
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Yeah I just tried the methanol prep and I got a small amount of precipitate when adding the cold water to the methanol solution but not enough to
bother recovering, I've been saving my 95% EtOH for a rainy day but I don't have much, I'll probably end up following the acetone extraction route
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JJay
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I was thinking about giving the methanol extraction another try but with something more like 20-30g of acetaminophen. I have 4L jugs of ethanol and
acetone but only about a liter and a half of methanol... the crystals from absolute ethanol look so pretty, though, so I think I'll try that next.
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JnPS
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Acetone extraction worked great for me, I'm recrystallizing from water just to be safe, but yeah those crystals from EtOH looked amazing, maybe when
I'm 21 and can get ethanol more readily I'll try and get those cool looking crystals.
Back to benzoquinone though, should I add the permanganate solution slowly or just mix the two and allow to react?
EDIT: Nevermind, I'm reading the PDF JJay linked to and there doesn't appear to be any reason to slowly add the oxidant
[Edited on 15-1-2017 by JnPS]
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JJay
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I have a crop of acetaminophen crystals growing in the freezer. They don't look as nice as BlackDragon2712's, and they are pretty small (around 0.5 mm
long), but they have a similar shape as his, and I think they'll be pure enough for the next step.
Edit: I took the crystals out of the freezer and vacuum filtered them through a glass sinter. Most of the precipitate was a powder, and even the
biggest crystals seemed pretty fragile. I washed them a couple of times with water and dried them on a water aspirator for about 10 minutes, and now
they are sitting in a makeshift desiccator made out of nested Tupperware containers over calcium chloride in the dark.
For some reason, the powder is light pink rather than white as I would expect. I'm not really sure why... this is obviously some sort of impurity, but
the pills started out entirely white, so I suspect it is a decomposition product or a polymer. I started out with 20 grams of acetaminophen, and there
appears to be a pretty good amount of product, which I will weigh when it is fully dry.
There has been some research done on acetaminophen decomposition products that form in solution, but they appear to range from yellow to brown rather
than pink....
[Edited on 16-1-2017 by JJay]
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JnPS
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I ran the oxidation but I the total volume of filtrate (doing the gravity filtration) is ~750mL. This is too large for my biggest sep. funnel (500mL).
Would I be okay boiling off up to half the volume of water so I can do the extraction of the product? Or should I just opt for doing the extraction in
two steps?
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JJay
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I'd say do the extraction in two steps. I'm not really sure what boiling off the water would do.
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Boffis
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@JnPS, I would not try boiling off the water as benzoquinone is steam volatile and you will loose most of it to the distillate. I would do as JJay
suggested and divide the solution into 2 or 3 portions that you can extract and then extract with dichloromethane, dry the extract and then distil of
the chlorinated solvent with reduced pressure distillation to minimise co distillation of the volatile benzoquinone.
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