Abnormal Picric Acid

[bonusiletisim]

I've just made my first attemp to make PA. I dissolved 10gr aspirin in 150ml H2SO4 at 80 degree celcius. I maintained the temperature 30minutes. Then I slowly added 35ml of 65% nitric acid. The result was a light red solution, a lot of NO2 and burnt lungs:eek: (still hard to breathe). When I poured the solution into cold water, yellow crystals precipitated. What is strange is a foam like layer on top of the solution.

Here is a picture of it. http://www.megaupload.com/?d=FVGXBNY8

What do you think this can be? Should I discard or keep it? Moreover, the solution tears the coffee filter. I cant filter it. İf I could, I want to recrsytallise PA with boiling water.

[NainKaigo]

I thought it appropriate to revive this thread since its the only one I can find in the Water Cooler in regard to synthesizing picric acid. I dont think im quite ready to run with the big dogs yet, so I mingle here.

I've also had trouble producing quality picric acid. I've made three attempts to date, all of which gave very poor yeilds/results. I have learned a few things as a result of these failures (better than nothing at all), but not enough to produce a quality product.

My first attempt started with a very deep green solution after adding the ASA to the H2SO4 (this also happened in my second attempt). I later found out my ASA was impure. I decided to go along with the nitration anyway, despite my dark green solution. Upon adding the KNO3 (very slowly) the solution started to turn a deep orange.

After nitration, the solution was a brighter shade of orange. However, during this process there was no foam (or NOx for that matter... thankfully) it seemed to go pretty smoothly.

I think this might have to do with the scale of my experiment and the speed at which I added the KNO3. It was 10% of Mr.Cool's method and the KNO3 was added painfully slow. I poured the solution into cold water and crystals percipitated. Everything seemed normal to me, though that isnt saying much.

I ran into a bit of a puzzling situation which I attribute to my lack of knowledge in the overall process. After filtering and drying the crystals I thought it best to test them. I tried to burn what I thought was picric acid. All it did was melt down into a pool, turned brown, then bubbled away, hardly what I was expecting.

My third attempt ended in much the same way (used 2g ASA, 30mL H2SO4, and 4g KNO3). The crystals appeared to be a faint yellow. Upon burning these crystals, I noticed relatively the same thing as last time. These crystals melted down, turned brown, bubbled up, then finally evaporated away.

I've searched the forum endlessly for answers and so far all I can come up with is it might look like picric acid but might be something else. Any guidance as to what might have went wrong, how I might be able to improve my methods, or even how to test my product to see if it is picric acid would be much appreciated.

I can't seem to find anything on The Forum in regard to determaining if what I have is indeed picric acid. Maybe I have missed a thread.

[Chopper]

@ bonusiletisim: Have just checked your photo, but MegaUpload says that the link will re-appear when somebody re-uploads it. So I guess it's broken.

I too have experienced a foaming upon crashing of the solution into ice-water. In my case I believe it was a result of too much water, not-finely-enough divided ice, which was further exacerbated by my enthusiasm to pour the reaction mixture all in at once.

I tried recovered the foamy layer seperate from the crystals at the bottom. I unfortunately have no notes, but from memory both portions were able to synthesise PbPicrate.

Lastly, are you melting the acid close to the edge? (and hence the flame) Picric acid does indeed melt before bubbling and dissapearing. I've not found it to be particularly combustible even in this molten phase. Try using a sheet of Al-foil. Place the sample under investigation close to one corner before heating with a match or lighter. Upon melting, you should be able to get it to start burning if you can play the flame across the top of the molten, fuming sample.

In my experience, it's about as easy to light as cooking oil.

Tip: try folding the coffee filter so that there's no strain on the join before placing inside a kitchen funnel.

Even if it doesn't burn you can still smell the distinct smell of picric. Kinda like coal smoke mixed with something more chemical in nature.

But most simple of all - look at anything that the horrible stuff has come in contact with. i.e your hands, clothes, and ther filter paper. If any or all of these are bright yellow and won't come clean....

[51cent]

NainKaigo and Chopper, did you use the same synthese instructions at all your attempts ? When searching for sythese instructions I collect as many as possbile and select the most agreeing to natural human sense. Mr. Cool's collection(I apologize to you if those instructions are based on experience and research) should not be carried out one by one as listed.

I made 1,5 g PA from 2g of ASA using synthese 88-89-1-B: http://www.sciencemadness.org/lambdasyn/synfiles/pikrinsaeure.htm
I'll use 'em tuesday night to initiate the composition discribed in KIFE (AN+P+Soy+instant coffee). We'll see whether "One #6 cap will reliably instigate detonation[...]"

(the rest is in solution and will probably used to sythesise potassium picrate)

Unfortunatly, it is written in German but you should be able to read out the main instructions.

I think you both made the mistake of thinking that this is a 1+1 chemistry reaction.
PA is a explosive which reacts exothermic (you might say "of course
it does you foul", but check out the properties of AP) ! This means that it's synthese has to be endothermic beacause its detonation/pyrolysis releases energy !
You both didn't mention supplying heat to your reaction vessels, so I'm considering you didn't. ASA needs energy to form "Phenolsulfonsäure" AND the final treatment with HNO3 to form TNP. So try the method
above-mentioned.

bonusiletisim, where is more water inside ? in 65% HNO3 or in the vessel containing "Phenolsulfonsäure" and +95% sulfuric acid.
You misguided a basic rule of chemistry: water into acid and not the other way round. You have to pour your "Phenolsulfonsäure" into your vessel containing the HNO3. Although he properbly won't response due to the fact that he rests in peace, I wanted to mention this.:rolleyes:

I hope that I was able to help you with the link. :o

And NBK, yes your right I'm a member of the minority who have methane bacteria in their colon. And I make use of 'em!
The ability to profile a person by just one post is...interesting:D

[lucas]

The foamy yellow stuff floating on the surface is likely picri acid foam with ubles of gas holding it up.

As for testing if a product is picric acid. After isolating it, dissolve it in minimum water and then try staining a piece of fabric or paper. Try also adding some soda to the solution to test acidity.

If either fails, so did synthesis.

[Chopper]

@ 51Cent: Nope. For about the first 4 attempts I made a very deliberate decision to utilize methods described in different sources. I am no longer able to locate the notes, but from memory, the foaming was observed on runs that contained more h2so4 than others.

Going on what lucas has said, I propose that it was the excess of acid that caused localized heating to the point of gassification. This phenomenon was not observed when using (a) lesser quanties of h2so4, nor (b) when the reaction mixture was poured very slowly onto the ice cubes themselves as compared to simply dumping into the cooled water (with ice blocks in it).

Also, you are right to a degree with your thoughts on my assumption of a 1:1 reaction mix. It wasn't until further study that I discovered that this was producing (pH)basic PbPicrate. To produce (pH)normal PbPicrate, one must use a 2:1 molar ratio of PbO and Picric.

Not quite sure where you're going with the endo/exothermic bit however. NG, NC, HMTD, Picric, AcetonPeroxide, SilverAcetylide/Double Salts all release heat upon formation, and with the exception of the Acetone peroxide, all release copious quantities of it upon detonation. Although requiring strong heating during the synth, Picric Acid is here too, since it is the formation of Phenol-4-Sulphonic acid that is endothermic, not the nitration (into Picric) of said sulphonic acid.

Enjoy your yellow fingers :D

EDIT: I got down to using about 8gm purified ASA in 80gms h2so4. Using 80ml (147.2gm) provided no benefit and excacerbated the foaming problem.