Log in

View Full Version : Picric Acid - Archive File


megalomania
June 17th, 2003, 08:02 PM
CragHack
Frequent Poster
Posts: 618
From:
Registered: DEC 2000
posted 05-26-2001 03:59 PM
--------------------------------------------------------------------------------
i read on megalomania's site that you must dissolve crushed up aspring tablets in 95% ethyl alcohol. The highest i can find is like 151 prrof (yes bacardi 151) and this is WAY to expensive. Does anyone have another liqued that i can dissolve the asprin in, so as to precipitate out the A. Acid later on? thank you.
------------------
"If you must, do it with intelligent people, at least they know how to talk to the cops."



gcic
Frequent Poster
Posts: 80
From: Germany
Registered: OCT 2000
posted 05-26-2001 04:21 PM
--------------------------------------------------------------------------------
Can`t you just use the ethanol, which is used for barbecue? I think, it is about 99%ethanol and 1% methanol, but I guess the methanol is no problem for your purpose.



CragHack
Frequent Poster
Posts: 618
From:
Registered: DEC 2000
posted 05-26-2001 04:27 PM
--------------------------------------------------------------------------------
ethonal is ethyl alcohol. unless i am grossly mistaken.
can you use something like rubbing alcohol. (mainly what i am getting at is can you use isopropyl?)

------------------
"If you must, do it with intelligent people, at least they know how to talk to the cops."



Anthony
Moderator
Posts: 2306
From: England
Registered: SEP 2000
posted 05-26-2001 07:40 PM
--------------------------------------------------------------------------------
Yeah, ethanol is ethyl alcohol.
I'm guessing any alcohol will work, all it has to do is dissolve the A acid.

Do you really need to bother with this step though?



CragHack
Frequent Poster
Posts: 618
From:
Registered: DEC 2000
posted 05-26-2001 07:47 PM
--------------------------------------------------------------------------------
if i were to try and make TNP, yes i would have to bother with it because i need to use the Asprin method. Thus i need the pure
A. acid to add to the Sulphuric acid. and (once again assuming i was to do this) i would be using NaNO3. but that isn't a problem.
so any alcohol huh? thanks for the info. I was thinking that just about any alcohol would work, but i wanted to make sure. thanks.

------------------
"If you must, do it with intelligent people, at least they know how to talk to the cops."

[This message has been edited by CragHack (edited May 26, 2001).]



Detonator
Frequent Poster
Posts: 133
From:
Registered: NOV 2000
posted 05-27-2001 01:55 AM
--------------------------------------------------------------------------------
Guys, Lets say you have Acetilsylisalec Acid
How many grams you would use with the 700m Sulfric Acid.?



Anthony
Moderator
Posts: 2306
From: England
Registered: SEP 2000
posted 05-27-2001 10:23 AM
--------------------------------------------------------------------------------
I don't bother with the purification step but I suppose it depends how much crap is in your aspirin tablets.


CragHack
Frequent Poster
Posts: 618
From:
Registered: DEC 2000
posted 05-27-2001 11:10 AM
--------------------------------------------------------------------------------
well it is better to be safe than sorry. If i am going to do it, i mine as well do it right. Does anyone have any actual info on yields and shit when using the proportions on megas page? hell can anyone tell me any type of info on the yields? i would like to know. I kinda get the sense they are REALLY small. I don't really want to get my hopes up, then have them dashed.
------------------
"If you must, do it with intelligent people, at least they know how to talk to the cops."



Actu
New Member
Posts: 5
From:
Registered: APR 2001
posted 05-30-2001 01:50 PM
--------------------------------------------------------------------------------
For 10(+-1)g pure acetylsalicylic acid (M=180g/mol) I got 5(+-1)g of recristallized,
dried product (M=229g/mol)
The theoretical yield is 229*10/180=12.7g so r=40% but there was a lot of loss
during filtration that you may minimize by using larger quantities of reagents (I mean, if the product lost during filtration is constant the relative lost would be minimized with larger quantities).

Is there a minimal quantity required for picric acid to detonate ? How much acetone peroxyde should one use to set it off ?



Mr Cool
Frequent Poster
Posts: 991
From: None of your bloody business!
Registered: DEC 2000
posted 06-02-2001 07:16 AM
--------------------------------------------------------------------------------
You don't need much AP. 0.5 grams if the TNP is a base charge in a cap, 2 grams if the detonator is seperate and contains only AP. This should be plenty.


YTS
Frequent Poster
Posts: 61
From:
Registered: MAR 2001
posted 06-02-2001 11:46 AM
--------------------------------------------------------------------------------
Why dont you buy some methalated spirit which is 90% ethanol & 10% methanol if you want you could boil off the methanol im not exactly sure the ethanols strength but its 90% plus


Mr Cool
Frequent Poster
Posts: 991
From: None of your bloody business!
Registered: DEC 2000
posted 06-02-2001 12:48 PM
--------------------------------------------------------------------------------
Methylated spirit (the purple crap) works fine as it is, without boiling or anything.


FadeToBlackened
Frequent Poster
Posts: 201
From: Hell
Registered: MAR 2001
posted 06-02-2001 07:47 PM
--------------------------------------------------------------------------------
Megalomania's site shows using 700mL of sulfuric acid for 100 aspirin tablets. Does anyone here besides me think that is maybe a little excessive?


Actu
New Member
Posts: 5
From:
Registered: APR 2001
posted 06-03-2001 04:56 AM
--------------------------------------------------------------------------------
The "aspirin tablet" is not really a known SI unit so you can't tell wether 700mL are enough :-)
But if you use pills containing a standard 500mg dose you'll eventually get 50g of acetylsalicylic acid and you'll need about 200mL of 95% H2SO4 to dissolve it (just speaking from my personal experience).


Mr Cool
Frequent Poster
Posts: 991
From: None of your bloody business!
Registered: DEC 2000
posted 06-03-2001 05:24 AM
--------------------------------------------------------------------------------
Well for me the aspirin is the most expensive reactant by far, so I like to make sure that none of it is wasted. Therefore I use the equivalent of 700 mL per 100 aspirins (each of my aspirins is 750mg of A. acid, with chalk and lactose which I remove).


wantsomfet
Frequent Poster
Posts: 236
From: EU
Registered: JAN 2001
posted 06-03-2001 06:16 AM
--------------------------------------------------------------------------------
I use a ratio 1 : 3,75 : 1,9 (acetylsalicyilic acid : H2SO4(ml) : KNO3)
http://odin.prohosting.com/~ratfuck/pa-imp.zip

Nihilist
June 19th, 2003, 02:31 AM
SWIM told me that he actually got a very good yield using cheap bayer aspirin pills, without purification. He said that he scaled mega's method down by 10 times so 10 pills and 70 ml h2so4(and he forgets how many grams of KNO3), but he got a yield of 13(wet) grams of TNP.

Sonny Jim
June 19th, 2003, 02:15 PM
I suppose the need for purification depends on how large a percentage of the tablet is ASA. You can work it out by looking at the number of mg of the tablet, then weighing the tablet and calculating the percentage ASA from there.

I am interested in making TNP, and am wondering if NH4NO3 can be used instead of KNO3.

Thanks.

IPN
June 19th, 2003, 02:47 PM
I tried to make some TNP a little while ago with NH4NO3 using MrCool's method, I didn't get any product:(
Though I added the nitrate pretty fast and if I remember correctly I had quite a bit of red NOx fumes..

Here the aspirin comes in 20 or 100 packs and contain 500mg ASA per tab, they certainly need to be purified.

Btw. Would this work NH4NO3 + KOH --> KNO3 + NH3OH

vulture
June 19th, 2003, 03:43 PM
IIRC, phenol is pretty sensitive to oxidation by NOx. Maybe that's why you didn't get any yield.

IPN
June 19th, 2003, 06:07 PM
Yes, that must be it. Next time I will add the NH4NO3 slowly, something like 1g per 15sec. (am I being too slow?)

In fact I did get a product, it was black brown goo witch didn’t dissolve in water and gave no precipitate from ammonia.. Certainly it wasn't TNP.

vulture
June 19th, 2003, 06:14 PM
Sounds like the typical symptoms of oxidation.

ALENGOSVIG1
June 19th, 2003, 07:05 PM
he scaled mega's method down by 10 times so 10 pills and 70 ml h2so4(and he forgets how many grams of KNO3), but he got a yield of 13(wet) grams of TNP

That doesnt sound right at all. 13g (yes, wet and unpurified but still) from 10 aspirin tablets! I get about 32-35g of purified TNP from 125 aspirin tablets each containing 325 mg of ASA. And thats not that bad of a yeild.

Me thinks theres alot of other crap in your TNP.

Arthis
July 20th, 2003, 05:48 PM
Standard aspirin is often dosed with 250-300 mg acetylsalicylic acid. (just to point out). If it's more concentrated it's written because some people can't stand it much. (hemophily problems)

Back to my problem. this afternoon I was trying to make PA. I used 10g salicylic acid, 250 mL H2SO4, 92+ %, and 30 gm KNO3.
The mix of both acids was easy, np. The KNO3 addition didn't make a lot of red fumes, rather some NA fumes.
The temperature was about 65-70°C I guess, I didn't measure, but I couldn't handle the jam pot.
I let the whole mix cool down to 25°C (less than room temp., see Mega's recipe ;)), then I poured it in 1.5 L of water. It was yellow, coloured my skin (a little on a finger). I thought it was due to the NA, which does the same, but it seems to be a particularity of PA, I don't know exactly.
But there was no cristallisation, no decantation. I guess I used too much water, and that the PA dissolved in it. But I don't know.
Any explanation ?

kingspaz
July 20th, 2003, 05:58 PM
too much water by far IMO. i would have dumped it onto 300g of ice water. and yes TNP does stain the skin yellow. i hope you are aware it is toxic (although a little on the skin isn;t going to kill you). just try to avoid contact. gloves come in very handy when making this explosive.

Arthis
July 21st, 2003, 06:07 AM
Cristallisation has occured, there are some in the water floating like glass fibers. I need to filter them out. To wash them, I will use more water, again, so what is the problem with water ? Do I need to use a little, for cristallization, then use some more to wash the cristals ? Mega's recipe, which happens to be KIBC's one, tells to use (keeping proportions) 300mL first, then 500 mL to wash cristals. I shouldn't have drown my mix.

I have some more salicylic acid, so I'm going to test again.

kingspaz
July 21st, 2003, 05:32 PM
assuming a 100% yield you would get 16.6g of TNP from 10g of SA.

solubility is 1.4g/100ml in water.
since TNP is soluble in the nitrating acid mixture then i'd say its going to be more soluble than 1.4g/100ml in the diluted acid mixture. but we'll assume it remains at 1.4.

now, you used 1500ml water. 1.4/100*1500 = 21g TNP will dissolve in 1500ml water.
thus, you have dissolved all the product. assuming you get a 60% yield then you would need only 711ml. so based on a 60% yield if you wanted to extract half of it you'd need about 350ml of water.

Arthis
July 22nd, 2003, 06:17 AM
Yeah, that's bad, I see I've lost a lot of PA... I collected the cristals, washed them a little. (don't use bicarbonate to neutralize acidity ! ;)) While drying in the sun, the cristals yellow color fades away.
Well, not uner direct sun, as here it's 35°C all day long, and even more if exposed to the sun, it's covered by a paper.

kingspaz
July 22nd, 2003, 09:40 AM
it should turn out to be a creamy yellow colour when first filtered out. when recrystalised from boiling water the TNP tends to form as a bright yellow.

Arthis
July 22nd, 2003, 11:00 AM
I think that my first picric acid batch gave me some cristallized K2SO4, or KNO3. I'm not sure, but it took ages to fully cristallize (one night I had to wait !), and it doesn't burn, so even if not pure, that's pretty weird for picric acid.

I've just made another batch a few hours ago, without cooling anything. I let the stuff react half an hour, let it cool down to about 30°C, then I added 150 mL of cold water. The temperature of the mix rose to 90°C, it's now cooling down. This is due to conc. H2SO4/HNO3 mix in which you add water. Still no trace of picric acid, I'll let it alone for a day as I leave for a party, then I tell you.

The procedure seems so easy, I cannot understand why it doesn't work.

Though my KNO3 should be quite pure, I suspect some additives to make it unusable for nitrating mixes... But that may be a little paranoïa, "they" don't take so many precautions.

kingspaz
July 23rd, 2003, 09:31 AM
right, i'm in a hurry so i only scanned in the procedure i used. you must recalculate the mass of SA to use since i used acetyl salicylic acid but the procedure is the same. also, use ice water of the mass we discussed above and it should work.

Arthis
July 23rd, 2003, 12:15 PM
You wrote it yourself ! Imagine what a scriptanalyst can reveal about you with that !

Yesterday I tried to make some PA again.
I used 3g salicylic acid, 9g KNO3, 70mL H2SO4, 92%
Today there's some cristals, yellow, looking like snow. Pretty beautiful. But there isn't much PA.
I roughly guess, since it's not dry yet, that there's something like between 0.5gm and 1gm, I'll weight it when dry.

I should try to use more concentrated sulfuric acid. Anyway I've got no more so I need to buy a gallon.

What is the purpose of heating the acids mix for half an hour ? Better dissolution ?

IPN
July 23rd, 2003, 12:37 PM
What is the purpose of heating the acids mix for half an hour ? Better dissolution ?

I think it's because then the ASA (or SA) has enough time to convert to phenol witch then turns into sulfonic acid.
But i'm certainly not sure about this..

knowledgehungry
July 23rd, 2003, 05:01 PM
Today SWIM attempted to make PA. However instead of adding the NaNO3 while the mix was warm, the NaNO3 was added after the mixture had cooled to room temperature. Will this make any difference? Should the mix be reheated? Or is it fine the way it is?

EDIT:
The NaNO3 is still undissolved, SWIM will reheat but is waiting for replies before he does, doesnt want runaway on his hands.


SWIM is still waiting for someones opinions before attempting to reheat mixture, any thoughts are appreciated.

Arthis
July 24th, 2003, 02:04 PM
I don't know about the particular reactions that may happen from the sulfonic acid presence.
Anyway, adding NaNO3 when the mix is hot is not really a problem, you add less each time. Heating the mix after all has been added gives you many more chances that you get an important formation of NOx fumes.
It may work if you heat very slowly.
This is only my mind, I cannot guarantee any problem.

blazter
July 24th, 2003, 05:27 PM
SWIM tells me that he just cooked up a batch of TNP via the aspirin/mixed acids method. He says that the KNO3 addition went slow, and cool in an ice bath. However, the KNO3 did not dissolve, and there was no foaming which would indicate the reaction had started. He heated the beaker carefully in an oil bath to a bit over 50C until foaming was noticed. Stirring was continued for about an hour until the foaming was no longer noticed. He also tells me that 10g ASA, 40ml H2SO4, and 20g KNO3 was used. He hasn't weighed the yeild yet, but he says it looks decent.

knowledgehungry
July 24th, 2003, 08:10 PM
SWIM may do what Blazters friend did. But he is still going to wait until tomorrow so if anyone whose opinion he respects more(sorry blazter your new) tells him not to try it he will be able to save himself from harm..

anthracis
July 25th, 2003, 05:49 AM
<<<Of all the nitrophenols,picric acid has been known the longest.The first mention of it can be found in alchemical writings of 1742,in which(cant read it)experiments are described.He acted with nitric acid on wool or horn and isolated picric acid in the form of its lead or potassium salt.A more detailed description was given by Woulfe in 1771,who prepared picric acid from indigo by treating it with nitric acid and found that the new substance had dyeing properties("indigo yellow")while Haussmann,in 1788,proved that it behaved like an acid.Later,many workers obtained the same product by acting with nitric acid on various organic substances,such as silk,natural resins ect.>>>

I've took this from another thread regarding nitroderivates of phenol.

As you can see, picric acid can also be prepared by nitrating other substrates. I've nitrated coniferous resin (with HNO3/H2SO4 mixture) and I've got an orange-yellowish stuff which burned very well, similarly to picric acid. At that time I had no primaries to try a detonation test, and I didn't even bothered to purify it in order to get superior nitroderivates, but this could be done, if someone has chemicals to waste. I guess that this stuff may prove useful at least for sensitising AN mixtures.

Arthis
July 25th, 2003, 07:27 AM
Very interesting quote indeed...

I think that my poor yield concerning PA is due to 2 reasons.
First, I didn't let the mix of SA/H2SO4 sit for a while, I soon added the KNO3 pretty fast; then I didn't let the mix cool down slowly, I forced the temp. to rise down with an ice bath.
That's why I get such a bad yield.

anthracis
July 25th, 2003, 04:51 PM
LOL something distracted my attention and I didn't noticed that the quote was blank...

I can't copy/paste the quote, but it's from the thread "Nitro derivatives of phenol"...

spelunker
July 31st, 2003, 05:14 PM
What is the biggest difference that anyone had between the hot water bath temperature and the reacting mix temperature (referring specifically to making picric from asa)? When SWIM tried it, the reaction temperature jumped up to 78 C, when the water bath was only at 60C. The spike in temperature was short in duration. This happened as the whole mix thickened to a thick gel. After filtering and recrystallizing it SWIM got a yellow powder, and the solution of it stains everything yellow, so he believes it is picric.
He did not write down the amounts used, but it was reacted in a large glass jar. The reaction was made utilizing asa, H2SO4, NaNO3, gallon glass container, thermometer. The NaNO3 was first powdered and then added in batches with stirring.
Afterwards, he reacted it with NaOH, since he did not have anything else (like KOH, PbO). Then it was recrystallized from that solution by lowering the temperature to about 0 C.
This made orange brownish crystals and only flamed up when heated over a flame, emitting smoke, which smelled similar to that from firing smokeless powder firearm.

Arthis
August 4th, 2003, 05:55 PM
Still, I'm wondering, after over one week drying, why the cristals refuse to dry ? There's a *lot* of water still. It may be due to the fact that the cristals are in a beaker, but it's pretty hot here (30°C in the shadow), you can see it should dry anyway while standing at the sun...

I haven't tried yet to use a dessicating agent, but I don't remember anyone having such problem with drying. A radiator was always enough...

0EZ0
August 4th, 2003, 09:01 PM
Make sure the PA is fully washed of sulfuric acid. It is quite possible that it was not satisfactorily removed after production. As you would know, sulfuric does trap alot of water. If thats not the problem, then it may be the high humidity in the air that is prolonging the drying. Try putting it in a dessicator or vaccum dessicator. You really should remove the PA from the beaker and spread it out over some paper towel or similiar. Doing this increases the surface area in contact with the air, carrying away more of the water.

grendel23
August 6th, 2003, 06:43 AM
I also had some trouble getting my TNP to dry very well. I decided to recrystalize it from water and had a fair amount of insoluble crap left in the beaker. After I precipitated and filtered the TNP, it dried very nicely and gave a bright yellow product.
I used pure USP grade ASA, H<sub>2</sub>SO<sub>4</sub> and KNO<sub>3</sub>, so the residue I had was not the result of aspirin tablet impurities.
I didn't weigh the crud, but it was a substantial percentage of the weight of the crude TNP.

Some Guy
August 24th, 2003, 07:11 PM
Many plants naturally produce salicylic acid, willow being one of them. Being an inexperienced organic chemist, I was wondering if anyone has tried extrating salicylic acid from say willow bark? Once extracted, one could easily make their own ASA with acetic anhydride and H2so4. I have read about using ethanol to absorb the acid, but no volume or weight was givin. This may not be the most efficient way of obtaining ASA but it would be neat to try.

Arthis
August 24th, 2003, 07:24 PM
The route would be interesting to be checked. I know some animals use to eat some willow leaves to cure themselves.

But I doubt that the concentration will be high enough to use commonly the route to produce your own expensive ASA.

Moreover, any of us that would get enough acetic anhydride to produce ASA for himself, without even thinking of using it for PA (as you can anyway make PA from salicylic acid), would prefer using it for more interesting purposes: RDX, or drug :) ...

Hubert
September 21st, 2003, 02:00 PM
Hej :)
Oh, in poland 250g of TriNitroPhenol TNF (Kwas pikrynowy) cost 10pln = 2,5$
1kg of tnf cost 40PLN or 10 dolars :), this explosives is very chep :D.

Bert
September 21st, 2003, 02:59 PM
Picric acid was sold in drug stores in the US up untill the
early 60's or so. Interesting to hear that former
Warsaw pact countries now are less regulated than
the USA...

bobo
November 21st, 2003, 09:31 PM
I was wondering: is it a good idea to neutralize the nitrating fluid with KOH? I have a red solution which stains everything quite yellow, alas no sign of any crystals. But, the stuff looks like old tomato sauce in a dirty pizzeria. If I get rid of most but not all of the acid, will the PA be less soluble?

edit: after one night I get a visually good yield of ochre metter which I assume to be PA. Now I think about it, contaminations present have to be inorganic salts mostly and since PA is organic, could it be better to purify PA by dissolving it in toluene or something like that?

Bert
December 8th, 2003, 03:01 PM
Pyrotechnists uses Sodium Salicylate to manufacture whistles, whistling rockets & etc. Would this be a suitable material in place of aspirin? Would any modifications in the procedure, be necessary beyond that required by the different mol weights of the two starting materials?

Mendeleev
December 8th, 2003, 10:29 PM
Walking through a CVS today I happened upon a container of Clearasil Pore Cleansing pads, and upon the label I read "Active Ingredient: 2% Salicylic acid." It also contains alcohal. I am not very familliar with the boiling point or vapor pressure of salisilic acid, so I'm not sure how to extract it, but extracting it would be expensive anyway, as it is only 2% and those things cost a lot :mad:.

Bert
December 9th, 2003, 02:15 AM
I do not mean that someone would need to extract the Sodium salycilate from a manufactured article- We have a license to manufacture, I have a drum of the pure chemical in my store (technical grade). I have also in the past had benzoic and salycilic acids for use in manufacturing Copper benzoate and Copper salycilate by reacting the acids with Copper carbonate. I was just curious as to the substitutability of Sodium or potassium salycilate for acetyl salycilic acid in the picric acid synthesis as it IS a chemical that many pyros would allready have on hand-

Rosco Bodine
December 9th, 2003, 01:01 PM
The method using purified aspirin / drain cleaner sulfuric / sodium nitrate
has always worked very well for me and uses cheap OTC precursors .
Two bottles of 500 aspirin tablets costs about five dollars , and the thousand
325 milligram tablets contain 325 grams of acetylsalicylic acid plus about
53 grams of alcohol insoluble binders and buffers . About 800ml of denatured
alcohol can extract the 325 grams of pure aspirin , if the solvent is hot , and
the extraction and recrystalization is extremely efficient , giving nearly
100 per cent recovery of the pure aspirin from the tablets . Alternately ,
it is convenient to obtain unadulterated aspirin by the pound , cheaply
available from veterinary suppliers . But in any case the use of impure
aspirin for the synthesis of picric acid produces a poor yield of impure
picric acid and also makes the synthesis more dangerous due to
decomposition byproducts . So it is always better to use only purified
acetylsalicylic acid for making picric acid .

A glass whistling tea kettle of about one and one half liters capacity is
what I use for producing 120 gram yields of exceptionally pure picric acid .
A magnetic stirrer hotplate , a large heavy stirbar , and a lab thermometer
are required for the process on this scale . I have managed half scale batches
less efficiently using manual swirling of the mixture , kept more fluid by
using a larger proportion of sulfuric acid , about twenty per cent more sulfuric IIRC .

Recrystallized sodium nitrate from fertilizer , is used for the nitration .
For each 1 gram of purified acetylsalicylic acid ,4 ml of the sulfuric acid is used ,
and 1.8 grams ( one and eight tenths gram ) of sodium nitrate .
My experience using the ratio of 1 gram / 4 ml / 1.8 grams
( aspirin / drain opener / sodium nitrate ) is that the ratio consistently gives
good results . The yield of extremely pure , pale yellow , recrystallized ,
purified picric acid should be 1.1 grams ( one and one tenth grams )
dry weight of Picric Acid from each 1 gram of purifed aspirin , about
80 per cent yield based on aspirin , from the first recrystallization . An
additional eight per cent yield is obtained in the second crop of crystals
for a final yield of 88 per cent , or about 1.2 grams of dry weight of very
pure picric acid from each 1 gram of aspirin . The crude picric acid is
precipitated by dumping the spent nitration mixture onto about twice
its volume of ice cubes , allowing to stand for a couple of hours and
filtering . The crude still damp picric acid is purified by redissolving in
boiling water and the solution allowed to cool slowly for several hours
while being continuously stirred . Well formed "gritty crystals" of picric
acid suitable for use in detonators or for any other use are precipitated
by this method . Rapid cooling produces a much lower density and less
desirable crystal form of picric acid as fluffy flakes and powder instead
of gritty crstals . For a batch size that starts with 100 grams of aspirin ,
about two and three quarters liters of boiling water is used to dissolve
the crude picric acid which has been filtered from the nitration reaction mixture .
The residual liquid from this crystallization contains an additional ten to
fifteen grams of picric acid and impurites . If the solution is boiled down
to about 700 ml volume , the impurities will precipitate as a molten
undissolved reddish brown blob in the boiling picric acid solution .
The hot picric acid solution is decanted from the residue of impurity ,
and on cooling the second crop of picric acid crystals is obtained .
Pure picric acid is absolutely NOT hygroscopic and when completely
dry is very pale yellow in color , a pastel yellow , very lightly tinted
material . Any moisture darkens the color significantly . But there
is not even a hint of red or orange coloration to pure picric acid , so
a pale yellow color is a good index of purity . There is no "neutralization"
of the nitration mixture done as is done for nitrations producing nitroesters .
Any base will immediately combine with the picric acid to form a picrate salt
of that base and picric acid .

The nitration process evolves extremely dangerous nitrous fumes and some
provision for powered ventilation and remote discharge of the fumes is
essential . This danger cannot be emphasized enough , the lethality
of even low concentrations of fumes near these sorts of reactions is
well established . The synthesis of picric acid is NOT a "kitchen recipe" .
This is one of those nitration procedures where air intake and discharge
ductwork is good sense .

The intitial step of sulfonation is done by dissolving the purified aspirin
added in portions to the well stirred sulfuric acid over thirty minutes as
the mixture is gradually heated to 115 degrees Centigrade . Acetic acid is
split off and the disulfonate of salicylic acid is produced in solution with sulfuric
acid along with some water as a byproduct . Heating is reduced and when
the stirred mixture has cooled to 85 degrees Centigrade , the portionwise
additions of sodium nitrate are begun . The temperature rises and the
rate of additions of sodium nitrate are done at a pace to maintain the
temperature of the mixture in the smooth nitration range of 95 to 100
degrees Centigrade . If the temperature rises higher , at 103 degrees
red fumes will be produced , indicating a loss of nitrogen due to an
excessive reaction rate and decomposition by oxidation , so it is best
to regulate the rate of addition of sodium nitrate to control the reaction .
When about two thirds of the sodium nitrate has been added , the reaction
product is largely dinitrosalicylic acid , which will acquire a third nitro group
while evolving carbon dioxide and thereby be converted to picric acid
as the reaction proceeds . This is the stage of the reaction where the
danger resides , due to the active effervescence of carbon dioxide at
the same time the third nitro group is being introduced in the hot nitration
mixture . Higher temperatures are required for good completion of the
nitration and best yields of purest product are obtained with supplemental
heating of the mixture during the final third of the nitration . Desirably ,
the temperature is allowed to peak at about 120 degrees centigrade after
the final addition of the sodium nitrate . At this high temperature the
picric acid is molten in the reaction mixture and a good yield of substantially
pure picric acid is obtained after three or four minutes reaction
at the elevated 120 degree temperature . The picric acid precipitates
rapidly in the hot reaction mixture and the mixture becomes a thick slurry
of picric acid crystals as it is allowed to cool just below the melting point
of the picric acid . Heating is discontinued and stirring is maintained to
avoid hotspots . After the stirred mixture cools for a few minutes ,
a fine stream of water from a wash bottle is directed upon the inside neck
of the vessel so that it forms a flowing sheet on the inner wall of the glass ,
and gradually mixes in a slow controlled dilution of the stirred mixture .
When sufficently diluted for pouring , the reaction mixture is dumped
onto twice its volume of ice cubes and the residue rinsed from the vessel
added to the mixture . The precipitation of crude picric acid proceeds
and the mixture is filtered after standing for two hours . The crude
picric acid is then recrystallized from boiling water .

From 100 grams of aspirin , 112 grams dry weight of pure picric acid is
obtained from the first boiling water recrystalization . An additional
10 to 15 grams is obtained after concentration of the filtrant to 700ml ,
decanting from residual impurity , and cooling , filtering the second crop
of crystals of pure picric acid .

Patents which provide references pertinent to this method are :

GB370436 describes reason for heating of nitration mixtures to
above the melting point of the picric acid

US1349802 describes boiling water recrystallization of picric acid

US1396001 describes a related similar nitration process for phenol which
uses sodium nitrate and sulfuric acid .

Microtek
December 9th, 2003, 03:37 PM
If you have easy access to 50-70% HNO3 you may want to try using instead of the NaNO3, an equivalent amount of HNO3. In my experience the CO2 produced during the de-carboxylation tends to form a quite resilient foam if the reaction mixture is too viscous ( which it easily gets if KNO3 is used; I haven't tried NaNO3 ). Using HNO3 gives a very fluid system that is easily stirred, and the heating due to dehydration of the dilute HNO3 can be minimized by mixing it with some of the sulfuric acid before addition.
This may not be helpful if HNO3 is not cheap and accessible where you are, but here where nitrates are sold only to farmers and 62 % HNO3 is OTC, my method is quite an improvement.

Rosco Bodine
December 9th, 2003, 04:59 PM
Microtek ,

Your suggestion has merit and I will try the use of azeotropic nitric ,
at least for the introduction of the first two nitro groups . The
presence of water should be no problem . You and I have both
observed that the use of aspirin as the precursor is complicated
by the decarboxylation , due to the temperature and foaming .
The effect is predictable and annoying , even though it is not
an unmanageable issue , so long as good stirring and temperature
control is used to keep the frothing mixture from overflowing ,
which it predictably threatens to do with little provocation at certain
stages nearing the completion of the nitration . If the mixture
was less viscous at the point where dinitration was complete ,
the third nitro group and decarboxylation would proceed more
smoothly . Champagne effervesces in a better behaved manner
than does oatmeal :) , that's for sure . But because of the elevated
temperature for the decarboxylation efficiency , I will still probably
use the solid sodium nitrate for introducing the third nitro group .
The nascent nitric acid forming in the depth of the mixture will
likely be more effective at nitration since it will have more time
of contact with the thing being nitrated , and not escape as quickly
as would liquid nitric acid dropped onto the hot mixture . Much
of the liquid nitric acid would volatilize or decompose on contact
with the hot mixture , and this would probably offset any advantage
for its use in the introduction of the third nitro group , when aspirin
is the starting material . Using phenol itself as the starting material ,
this limitation would not apply . But using aspirin does produce this
reaction stage where things get complicated ( a little ) by the
decarboxylation process .

I haved tried other nitrates , both potassium and ammonium , and
sodium nitrate gives the best result , a thinner mixture than potassium
nitrate . Ammonium nitrate gives a thin mixture but poor yields .

tom haggen
March 26th, 2004, 06:58 PM
Rosco Bodine, I searched the U.S. patent office for patent number US1349802 with no results. Mabey you could post a link to this information.

Rosco Bodine
March 26th, 2004, 09:03 PM
Try here , highlight and copy the term US1349802 and then paste it into
the second search box and follow the links .

http://ie.espacenet.com/espacenet/ie/en/e_net.htm

or a direct link if it will hyperlink

http://l2.espacenet.com/espacenet/bnsviewer?CY=ie&LG=en&DB=EPD&PN=US1349802&ID=US+++1349802A1+I+

Anyway there is just a sentence or two in the patent regarding
crystallization while stirring hot water that is slowly cooling ,
which is a pretty standard method of getting a good crystalline
product of any material .

tom haggen
March 26th, 2004, 11:44 PM
I tried putting US1349802 in the second search box and I didn't get very good results. Also that hyperlink didn't hyperlink. Basically I'm just having a hell of a time trying to purify my picric acid. I have recrystallized XNO3, Chlorates, and other things. But when I try to recrystallize picric acid I'm not getting crystalline formations. I know It's because I have not removed the impurities, but i'm having a hard time isolating the impurities to be able to remove them.

Rosco Bodine
March 27th, 2004, 05:55 AM
The recrystallization of picric acid from near saturated solutions
of boiling water is so straightforward that anyone having trouble
recrystallizing picric acid doesn't have picric acid .

The links work fine on my machine . You either have a faulty browser
or your access is being blocked through some means .

knoddas
March 27th, 2004, 07:19 AM
Try this link instead: Click Me! (http://patimg1.uspto.gov/.piw?Docid=01349802&homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fn ph-Parser%3FSect1%3DPTO1%2526Sect2%3DHITOFF%2526d%3DP ALL%2526p%3D1%2526u%3D%2Fnetahtml%2Fsrchnum.htm%25 26r%3D1%2526f%3DG%2526l%3D50%2526s1%3D1349802.WKU. %2526OS%3DPN%2F1349802%2526RS%3DPN%2F1349802&PageNum=&Rtype=&SectionNum=&idkey=A378C6192BD6)

Searched at: http://patft.uspto.gov/netahtml/srchnum.htm
Searched for: 1349802

(If You can't see the picture, You have to download AlternaTIFF)

tom haggen
March 27th, 2004, 11:13 AM
knoaddas i searched on the site you posted and was able to view the patent, thanks. Rosco, I think my picric acid is heavily poluted with compounds that were oxidised during the nitration. I think it would be possible to recrystallize my picric acid accept i'm finding it quite impossible to extract the contaminents, and I haven't found any procedure that is efficient at doing so.

Rosco Bodine
March 27th, 2004, 11:52 AM
Tom ,

The picric acid is only slightly soluble in cool water compared to near boiling
water , the ratio is more than ten to one . So if you spoon your crude
picric acid into boiling water until no more will dissolve and then add a
little water to complete the solution and take it a little below saturation
so that it doesn't crystallize while you are pouring or transferring it ,
you are going to get ninety per cent of that picric acid crystallizing
as the solution cools .

The partially nitrated phenols and phenolsulfonic acids are also yellow
but those impurities will remain in solution , and when the residual
solution from the first crystallization is concentrated to about one fifth its volume ,
those impurites will form a molten insoluble blob on the bottom .
At that point you can decant the hot solution of picric acid away from
the impurities and upon cooling you get your second crop of crystals
of picric acid .

If it doesn't go that way , then you have not made picric acid but
have an incompletely nitrated assortment of phenolic substances
instead .

To get good detonator grade crystals you cannot rush the crystallization
or use supplemental cooling . You need to have about a gallon of the
boiling hot nearly saturated solution cool slowly at its own rate to room
temperature while being stirred continuously . The surface of the solution
is not exposed to the air so there is no speeding of cooling by evaporation ,
and you may even wrap a dry towel or insulation around the container to
insure slow cooling .

The tailings of powder like picric acid which you get from chilling the solution
should be set aside for use in syntheses where the crystalline form is not important .

Pure , dry picric acid is a very bright but light pale yellow color sort of like
scrambled eggs .

tom haggen
March 27th, 2004, 07:23 PM
Ok so the trick is to cool slowly that way I can extract the picric acid before any contaminants precipitate. I'm still a little in the dark by what you mean when you said "The tailings of powder like picric acid which you get from chilling the solution."
Someone
This is what i'm am getting from you. Disolve everything in to a solution. Then slowy cool and the crystalline picric acid will precipitate out of the solution first. again i'm not sure when the powder like picric acid will precipitate.
forgot
Anyway, thanks for the advice I will try this slow cooling method. by the way I was just disolving my product in boiling water and then sticking it in the freezer so i'm sure this method will help.
to
Next time I make this I will have it down. My method will be as followed. React everything as mentioned elsewhere on this site. After the addition of XNO3 or nitric acid your supposed to cool it to 5C before you add water.
add
Well heres what i'm going to do. After the addition i'm going to add water to the reactants while they are still at like 40-50C, this will cause some NO2 to form and some product will oxidise.
paragraph
However, if you let this reaction subside and come back when the runaway reaction is complete, there will be very pure picric acid crystals formed on the bottom and all the impurities will be floating on the top so you can just decant off the impurities with out having to go through the hassle of recrystallization.
breaks. ;) NBK
I used this method when I first made picric acid, unfortuneatly I didn't decant off the impurities and instead filtered all the precipitates at once.

Rosco Bodine
March 27th, 2004, 08:38 PM
Tom ,

The term is recrystallize , you don't "extract" anything . Extraction
is a different process , usually where two imiscible solvents are used
to separate a mixture of things into different layers .

Anyway , don't speculate upon improvements or variations upon
the described process until you have more experience with what
does work , and has already been described in detail by experts .
People who have already done the syntheses many times have
likely tried many variations and can save you a lot of work at
the details of optimizing something already optimized :)

You will get the powder form from rapid or supplemental cooling ,
or from the more rapid cooling which occurs naturally with small
batches . Probably it would be better to only stir occasionally
a small batch as it is cooling , and definitely cover and insulate
the container . Let it slowly cool all day , or better still overnight ,
before filtering . The latent heat in the solution is the engine which
drives the crystallization process . The longer it takes for that heat
to dissipate , the larger grow the crystals .

tom haggen
March 28th, 2004, 12:38 PM
Rosco your the man! I tried that insulating trick that you told me about and presto. The next morning I woke up to some orchid like crystal formations. See for yourself.http://www.geocities.com/grandpa_jacob/picric_acid.html?1080491729951

EDIT: I must say that i'm a little suspicious that these crystals are just potassium nitrate stained yellow, They don't really seem to burn.

Rosco Bodine
March 29th, 2004, 12:37 AM
The melting point for the dried crystals should be 122 C ,
and it should be very soluble in alcohol .
A few crystals of the material when dissolved should
give a distinct yellow tint even to a relatively large
volume of water , as picric acid is a strong yellow dye .
A solution of the material should give a precipitate
when mixed with a solution of copper or lead salts .
A small amount of the dry material mixed with bicarbonate
of soda and wetted should effervesce carbon dioxide
and turn orange . These are a few tests that can
help you identify the material .