BlackDragon2712 - 28-1-2016 at 20:25
Hello guys. So first of all I apologize if I commit some mistake in my writing or something makes absolutely no sense, English is not my native
language but I'll do my best.
Sadly I could not complete the isolation process today but tomorrow I'll be posting my final results.
1-) Chemicals used
a-) Paracetamol tablets (500mg)
b-) Ethanol (95%)
c-) Ethyl acetate
d-) Glacial acetic acid
e-) Sodium nitrite
f-) Sodium Bicarbonate
2-) Extraction of acetaminophen
So I measured 6.5g of paracetamol tablets and ground them into a fine powder. Then I dissolved them into aprox. 100ml of 95% ethanol and filtered the
undisolved particles. Finally I evaporated the ethanol down to 30ml aprox. After about an hour or so the acetaminophen began to crystallize. I put the
solution on the fridge at -7 °C and let it repose for about 30 minutes.
My yield was 5.8g of acetaminophen (89%)
3-) Reaction
I measured 5g of the extracted acetaminophen and mixed it with 11.4g of sodium nitrite under an ice bath and added 20ml of distilled water.
Making sure the mixture is at 0°C I added 2ml of glacial acetic acid. The ph of the solution should always maintain between 4 - 7.
No gases were detected (Though I would imagine some NO2 should be produce due to decomposition of HNO2)
I let the solution react for 2 hours and it went from a yellowish colour all into a deep red one.
I washed the solution with 10 ml of saturated HCO3 and then with 2 batches of 10ml and a final batch of 15 ml of ethyl acetate.
Then I added some magnesium sulphate anhydride to remove water and here I stopped the procedure because it was getting late here.
I'll try to crystallize my final product and get a melting point.
3-) Sources
1- Takanobu MATSUNO, Tomoko MATSUKAWA, Yoshiharu SAKUMA, Takehisa KUNIEDA. A NEW NITRATION PRODUCT, 3-NITRO-4-ACETAMIDOPHENOL, OBTAINED FROM
ACETAMINOPHEN WITH NITROUS ACID. Chem. Pharm. Bull; 37(5) 1422-1423 (1989)
Link: https://www.jstage.jst.go.jp/article/cpb1958/37/5/37_5_1422/...
2- USBiological life sciences. 3-Nitro-4-Acetamidophenol.
Link: http://www.usbio.net/item/N2580
3- Nitro-genes and Rosco Bodine. Synthesis of 4-amino-2,6-dinitrophenol (isopicramic acid) and p-DDNP from acetaminophen.
Link: http://www.sciencemadness.org/talk/viewthread.php?tid=63405
Boffis - 31-1-2016 at 14:23
@Blackdragon; interesting write up, I tried this reaction better (Under this thread) but I dissolve my paracetamol in glacial acetic acid first which
made the whole solution rather too acid and I got an intense yellow brown from which I recovered two products, one bright yellow and one orange brown
but I have had time to do any follow up or repeat experiments with a more carefully buffered reaction medium.
I would be very interested to see what your product is like and whether it is crystalline. Does the paracetamol dissolve or do you work with a
suspension?
BlackDragon2712 - 31-1-2016 at 16:16
To be honest I haven't had time to continue this procedure. after allowing the mixture to repose for a day or so a black precipitate was noticed...
I'm not sure what it is, under the light it seems to be some kind of crystalline substance but it surely looks absolutely evil haha... any ideas on
what could this be?
Looking on the internet I think it could be some kind of hydrolysis product. Sigma Aldrich says that 4-amino-3-nitrophenol has a deep violet color...
I will do some tests when I have time to determine what this may be.
Also, yes. I was working with a suspension... later in the reaction most of the aminophenol did dissolve but just a little bit remained in suspension,
like a gram or so.
Boffis - 19-2-2016 at 16:56
Hi Blackdragon, have you got any further yet? Did you get anything crystalline?
Skilving - 25-2-2016 at 17:07
How do you know that you aren't making a nitroso product? The reaction procedure and red solution remind me a lot of the nitrosylation step of a
Traube synthesis.
Boffis - 26-2-2016 at 14:22
@Skilving, That's the major question but until we can isolate something that looks like an individual crystalline compound rather than gunk it's hard
to say whats going on. I have decided to tackle the problem from the alternative route via direct nitration of 4-acetamidophenyl acetate. I have
prepared a reasonable quantity of this compound from 4-acetamidophenol and acetyl chloride but I haven't had time in the lab recently to attept the
nitration and hydrolysis. I am following two published procedures for this reaction so I hope to end up with a sample for comparison.
Rosco Bodine - 21-3-2016 at 09:03
@BlackDragon2712
There is some information of interest in a related thread
http://www.sciencemadness.org/talk/viewthread.php?tid=9722&a...
Rosco Bodine - 26-2-2017 at 23:10
It is probably the 3-nitroso-4-acetaminophen that is being obtained from the reaction with nitrite in mildly acid reaction system. That nitroso may
be be possible to convert to a nitro by subsequent use of HNO3.