TNP (Picric Acid)

kbk · #1 (**permalink**) 07-13-2005, 07:56 PM

Picric acid is prepared in a 2 steps..The first step is purification of aspirin to aquire ASA (acetyl salicylic acid), this is done by dissolving crushed asirin tablets into warm acetone and evaporating the liquid off. The second step is the real making of the TNP(Tri-Nitro-Phenol) this is done by dissolving 20g ASA into warm (70-80 degrees C) H2SO4(100mL), and letting it sit for 20-30 minutes, this produces phenol sulphate. Nowr remove the acid from the heat and allow to cool and you are ready to add 50g of KNO3, do this slowly as it will fizz and fume if it is done too fast and this can cause a runaway reaction which you do not want. Now after the KNO3 (or other nitrate salt) is added you have to put it into an ice/salt bath and cool it down to 0-5 degrees C, it will become a thick sludge at this point. Now place 200g of ice and 100mL of water into a larger container and scrape in the TNP mixture...After awhile you will see yellow TNP chrystals in the bottom of the container, filter these out. After you filter out the TNP you will need to purify it, to do this dissolve the TNP into 50mL of boiling H2O and then place it into an ice batch to re-chrystalize it.

Kaos-theory · #2 (**permalink**) 07-13-2005, 09:57 PM

the tnp mix you refer to being the "will become a thick sludge at this point"? if so i understand.

whats the out come of a runaway reaction?
this seems so simple any problems incountered?

Douchermann · #3 (**permalink**) 07-13-2005, 10:51 PM

I don't think a runaway is possible with this, or atleast while adding the xNO3, because mine wasn't dissolve all the way, so i actually turned the heat back on for a couple minutes and shot that stuff up to about 90deg C. And yes, when you get done adding all the nitrate it is a thick sludge, but its soo cool when you pour it into the ice beaker, it goes from black ugly sludge to bright yellow liquid right before your eyeballs.

kbk · #4 (**permalink**) 07-13-2005, 11:24 PM

I don't know about runaway I seem to remember someone mentioning that it could happen..I ran into no problems making it, it took me a long time to mix in the KNO3 because of fizzing but that was it. And yes I do mean the TNP mix turns thick.

kbk · #5 (**permalink**) 07-22-2005, 05:07 PM

I have a tutorial posted on my site for this, it's not quite complete yet because I didn't cover purification or re-use of the liquid, but I don't have time for that stuff today...Anyway, here's the link, http://kbkforum.com/cgi-bin/ikonboar...=ST;f=22;t=109

Douchermann · #6 (**permalink**) 07-23-2005, 02:00 AM

Nice, how much asa are you using?
Did you use that ice bath thing the first time you made that stuff?

Douchermann · #7 (**permalink**) 07-23-2005, 02:04 AM

I would also like to point out that TNP is not toxic (thought it can irritate eyes, but can't anything irrate eyes these days?)
http://ptcl.chem.ox.ac.uk/MSDS/PI/picric_acid.html
One sentence i would like to point out is "Explosive when dry", well heres my two cents:
NO SHIT

kbk · #8 (**permalink**) 07-23-2005, 02:15 AM

TNP is carcinogenic, I don't know if that classifies as toxic, but it does for me. I use 30g of ASA, 75g of KNO3, and 150mL of H2SO4. And yes I used an ice bath the first time I made TNP.

Mumbles · #9 (**permalink**) 07-24-2005, 11:38 PM

It most certainly is toxic. It is a scheduled poison in Australia(class S6) and in the US. I suggest you find a more complete MSDS. Those oxford ones are decent for quick facts and solubilities, but I always try to find a Fisher, J.T. Baker, or Sigma-Aldrich MSDS as they are all very complete. It is toxic by inhalation, consumption, and skin contact. Gloves do more than just keep your skin not yellow.

http://www.chemsupply.com.au/files/catalog/1CHHT.pdf
http://www2.itap.purdue.edu/MSDS/docs/1219.pdf <-- Note section 11

kbk · #10 (**permalink**) 07-25-2005, 03:37 AM

Hm that's a little scary...O well though.

Douchermann · #11 (**permalink**) 07-25-2005, 05:30 PM

I stand corrected.