Picric acid

[ALENGOSVIG1]

Usually i wouldnt post something like this, but the forum is looking a little empty so i figured i'd post it.

Last night a made some picric acid using 250 aspirin tablets. each tablet contained 325mg of A.S.A.
Here's a picture of the yeild: http://www.angelfire.com/linux/aleng/pa.jpg

you may have to paste it in your browser. In the pic is 2 paper towels and 1 coffee filter full of picric acid on an old kitchen plate. Sorry about the shitty quality of the picture.

when it dries i'll weight it and try to make some DDNP with it. I'll post my results for that too.

[ 03 March 2002: Message edited by: ALENGOSVIG1 ]

[DBSP]

Glad you posted that I'm trying PA next wekend. Did you use the normal H2SO4 KNO3 method? 250 tablets, that's about 81g ASA it would be good to get a feeling about the yield based on the ASA. Nice pic I'd love to see more of those on the forum!!

I wouldn't normaly post something like that either but as you say, the forum is kinda empty right now so a few posts like this really doesn't mind me at all. ;)

[ALENGOSVIG1]

Yep i just did the normal sulphuric acid/kno3 method. Below is the method i wrote up

Picric acid 1

Materials:

250 aspirin tablets each containing 325 mg acetylsalicylic acid
440 ml 98% sulphuric acid
153g potassium nitrate
1L isopropyl alcohol

Procedure:


1) Powder 250 aspiring tablets and place the powder in a beaker.
2) In another beaker, gently warm 1L of isopropyl alcohol and add it to the beaker containing the powdered aspirin.
3) Stir for 10 minutes then filter out and discard any solids collected.
4) Pour the filtrate into a shallow ceramic dish and heat in a simmering water bath until all of the isopropyl alcohol has evaporated and only acetylsalicylic acid remains.
5) Place the ceramic dish containing the acetylsalicylic acid in an oven set at 65 degrees Celsius for about 45 minutes to dry off any remaining moisture.
6) In another beaker, add the acetylsalicylic acid to 440 ml of 98% sulphuric acid stir for 5 minutes.
7) Heat the beaker to 70 degrees Celsius and hold it there while stirring until all of the acetylsalicylic acid has dissolved.
8) While vigorously stirring, slowly add 153g of potassium nitrate to the sulphuric acid/acetylsalicylic acid solution. The addition should take about 1 hour and 20 minutes.
9) Let the solution cool to room temperature then cool it to 5 degrees Celsius in an ice bath.
10) In another beaker, add 1kg of crushed ice to 400 ml cold water,
11) While stirring the ice/water, slowly add the contents of the beaker. This should precipitate out the picric acid.
12) Stir for 5 minutes and then let it sit for 15 minutes to let the precipitate settle at the bottom of the beaker.
13) Carefully pour off about 1L of the liquid and add 500 ml of cold water.
14) Filter out the picric acid and discard the filtrate.
15) In a beaker add the picric acid to 300ml of boiling water and stir. Add more water if all of the picric acid doesn’t dissolve.
16) Let the beaker cool to room temperature then cool it to 5 degrees Celsius in an ice bath.
17) Filter out the precipitate and discard the filtrate.

[DBSP]

Just run into problems the KNO3 was out of stock when I was about to buy it at the store. Is it possible to use NH4NO3 instead?
There is one thing wich is called "saltpeter salt" it's KNO3, NaCl and something more, every store has this one but they've run out of KNO3 could you use this in an emergency. I dont know about how much of what it is in the stuff. I once tried KNO3-sugar using this, It worked if you ignited it with some "real" stuff first so the conc of KNO3 must still be quite high.

[DBSP]

Ah finally found it in a small store out the contry.. I'll be doingsome picric this wekend and I'll post the results. How was your yield ALEN?

[Yi]

Get some pictures if you can :) I'll be doing the same experiment sometime soon and I just want to know how much nitrous vapours to expect.

[Mr Cool]

You'll hardly get any NO2 if you add the KNO3 slowly, and don't let it get too hot. Just a bit of NO2 (just visible), HNO3 vapours and CO2 from the ASA decarboxylating.

[DBSP]

I'm afraid I don't have a digital camera the normal one worked fine but then you have to wait a month to get the film developed. So no pics, sorry. :( However I'll tell you how it goes.

[DBSP]

Ok I just tried PA, however as usual there are some complications.

I dissolved 13g ASA in 90ml of conc H2SO4 and started to add KNO3 very slowly, I added A total of 16g over an hour. The mixture started foaming as soon as I started adding the KNO3 and continued throughout the whole reaction. When It stopped the mix was dark red. Allmost no NO2 was formed, but I perhaps didn't see it before it was sucked away in the fan. I then slowly poured the acid mix into a liter if cold water and crushed ice. ?? no picric, no picric fell out of the solution but the ice/water went dark red.

What went wrong?? :confused: I still have the liquid left from the reaction in case it's of any use.

It in the middel of the night here so I'm going to bed I'll check the thread in about 5h after some sleep. :(

[Madog555]

you want to let the asprin "cook" with the H2SO4 for like 15 minutes to convert it to phenol. then you should nitrate it.

[ALENGOSVIG1]

You attempted to precipitate it with too much water. alot of the picric acid probally dissolved in the water.

[ 07 March 2002: Message edited by: ALENGOSVIG1 ]

[DBSP]

So evapourating should get it out of the solution then. I might give it a try again in the weekend, and I'll try reacting the ASA and sufuric about an hour and only having about twice the original volume of ice/water.

[Alchemist]

Hello all,

Well since it is slow, I also have some questions on making Picric Acid!

1. Exactly how long is the best time for the Asprin plus Conc. Sulfuric Acid mix and what is the best temp.? After reading many recipes
I have found times from just mix at 50 degree's C to 100 degree's C and then start adding KNO3 right away. Then also waiting as long as an hour before adding the NO3!

2. Also just wondering does anyone know what the Asprin plus H2SO4 makes. Is it a Phenolsulfonic Acid or ? I would like to know exactly what we would have if this was dissolved in a suitable solvent, then re-crystallized (For possible other experiments).

More later I am working on a few things!

[ 08 March 2002: Message edited by: Alchemist ]

[Madog555]

1. i dn't know, in the black book it says 15 minutes.

2. im pretty sure that it is just H2SO4 with some phenol in it. i read(in merck i think) that when asprin is heated with H2SO4 it make phenol.

[DBSP]

I've evapourised some of it now the crystals came out but they were very poluted. Could it be H2SO4 left with the crystals. What's the best way to seperate them. Is there any common solvent that doesn't dissolve the PA, water, ether, ethanol, chloroform, benzene, acetone, they all dissole it.

I've added som water to the soulution, it's cooling down right now.

[Yikes]

What about recrystallisation from acetone or ether? That woud get you nice, clean crystals of PA.

[Madog555]

here is the properties of PA from Merck

Properties: Pale yellow, odorless, intensely bitter crystals. d 1.763 . mp 122-123degrees . Explodes above 300degrees. One gram dissolves in 78 ml water, 15 ml boiling water, 12 ml alc, 10 ml benzene, 35 ml chloroform, 65 ml ether. Incompat: All oxidizable substances, albumin, gelatin, alkaloids. Keep in a cool place and remote from fire. Explodes when rapidly heated or by percussion! Note: For safety in transportation, 10-20% water is usual ly added.

[DBSP]

I've checked merck, that's were I got it from. I suppose the only way is to dissolve it in acetone, filter and and evapourate. What do you think about the H2SO4?

[Madog555]

megas site sugesed boiling water, then spoon off any dirty oil shit that comes to the top , then re-crystalize it. i bet acetone would be easier though.

[VX]

I swear, this stuff is jinxed.

I've just finnished wasting my afternoon.
I followed Alens methos to the word, however my reactant vessel was a milk bottle. Its all i could find :rolleyes: .
Anyway, as soon as I started to add the KNO3 it started to foam a lot, and produce various gases... By the way is this normal?
Oh, and to be clear, should the nitrate be added while the acid mix is still at 70 degrees in the water bath.

I had added about half of the KNO3 when it started to foam a bit more, so I stired more vigorously and.....broke the bottle!!!

Honestly the bottle just broke at the bottom, forming a nice hole for all of the reactents to escape. :mad: . I could not beleive it. I'll try again soon, after i have aquired a large (100ml) beaker) beaker.

Come to think of it the acid mix nearly filled the bottle, so it didnt take much of the froth to make the bottle nearly overflow. As the level of the liquid was at the point whare the bottle starts to form into the narrow neck. I'll try again soon.

VX

[DBSP]

The foaming is normal and gases will be produced (NO2). If you add the KNO3 slow with much stirring ypu wont get very much NO2. You schould probably let it cool a bit before you add the KNO3. Best would be if you would let the ASA sit in the H2SO4 for at least 1/2 hour before you add the KNO3 so that the ASA gets some time to sulphonate.

I didn't sucsed the first time I tried PA either so don't give up, give it another shot. And you could use a normal jar or a big glass as a reacting vessel.

Good luck <img border="0" title="" alt="[Wink]" src="wink.gif" />

[VX]

Oh theirs no chance of me giving up, and sooner or later, as God is my witness it will work! :)

This is probably me being slow but when you say let it cool a bit, should it be taken out of the water bath completely and then left out for the duration of the addition, or just allow the water bath to cool to a lower temp befor continuing with the addition of the KNO3? If so what temp?

I did let it sit for about 10 mins before adding the bottle to the water bath, and a further few mins when all of the ASA had dissolved.

I will get this to work and i may be able to get pics of both the synth, and of its 'use' <img border="0" title="" alt="[Wink]" src="wink.gif" />

<small>[ March 14, 2002, 04:54 PM: Message edited by: VX ]</small>

[Mr Cool]

When using phenol, no gas should be prodcued, although some NO2 probably will be. When using aspirin, you will get lots of gas due to the aspirin decarboxylating, releasing CO2. So yes, gas is normal if using aspirin.

[VX]

Ive just re read the thread below. Should the acid mix go black before the addition of the KNO3, it might have been very dark red, but anyway is this what's supposed to happen?

And the froth formed when the KNO3 was added was red, (I think that it was a least partly NO2). I was ading the KNO3 VERY slowley, I was adding it from the tip of a cocktail stick!

<small>[ March 15, 2002, 04:06 AM: Message edited by: VX ]</small>

[DBSP]

I don't know if it's supposed to go black before you add the KNO3 but mine did so it might be normal. After the addition of KNO3 my liquid was very red, that's supposed to happen I think.

[Mr Cool]

The H2SO4 I use for this is 91% drain cleaner, which is bright purple so I'll obviously get some funny colours during the reaction, but it does go dark and then red/orange when I do it.

[vonK]

When I make Picric acid the solution stays colourless untill the addition of the nitrate, when it instantly changes to light orange and begins to foam then slowly darkens with more nitrate.

Today I extracted the ASA from 50 asprin tablets, the ASA crystals are now dry and stained purple from the methylated spirits but they also smell very fruity. I'm wondering if the ASA could possibly have esterified with the meths (95% ethanol).
Do you think this will cause any problems when I try to make Picric acid.
Thanks
Kurt

[stanfield]

I have an important question : is acetylsalicylic acid a synonym for benzoic acid ? if yes, I could produce picric acid in very impotant quantity since I can buy benzoic acid and it's really cheap !

thanx !

[VasiaPupkin]

Acetylsalicylic acid is a (CH3COO)C6H4(COOH) Benzoic acid is a C6H5(COOH). You could not make TNP from benzoic acid so easily.

[stanfield]

is there a way from benzoic ?

[vulture]

First you would have to make salicylic acid C6H4(OH)(COOH) from benzoic acid.
Maybe this can be done by boiling with NaOH.
Now we would want the COOH group substituted by a NO2 group.
However, I think the nitro groups will take the open positions or replace the OH group, but i'm not sure.

[Mr Cool]

No, there's no easy way (that I know of) to make TNP from benzoic acid. B acid can be nitrated to DNB acid, which might decarboxylate in hot acid, forming DNB, which could be nitrated to TNB. I can't remember who I was asking about this, but someone here said they thought it might work.

[a_bab]

Stanfield, what other chemicals are available in France ? Some usefull I found are acetone, ammonia solution and alcohol. Where can I find benzoic acid ?

I have a method for making TNP from salicilic acid only, but it involves large quantities of HNO₃ :( ...

[stanfield]

no, allright ! I found Acetylsalicylic acid in the acros organics catalog, 500 g for 13€ !!
How many grams of TNP could I obtain with 500 of Acetylsalicylic acid ?

thanx !

[Mr Cool]

In theory, 636g. With a 70% yield, 445g.

[Marbles]

I've just prepared some picric acid from aspirin and its drying now.I just want to get some idea of the power this has in comparison with AP for example.What expieriences do you guys have with it?I plan on making some good strong detonaters with it and Ag2C2.

[andreas]

Yesterday I dreamt of making PA. So here's what I did.
24g acethylsilicilicacid
100ml sulphuric acid
50gram KNO3

After warming the sulphuric acid to around 60 degree celcius
I added the acid slowly. When it al dissolved I let it cool to 40 C
It was a dark red collor. Then I started adding the nitrate it took me 1hour and 20 minutes for the lot.
During the addition little NO2 was formed but it was throthig and it turned extremely dark red during the addition. During the hole addition the temp didn't exceed 70 degrees C After all whas added I let the mix cool to room tmp. After cooling there was a thick cake like layer on the botom and I added 300ml of water ice mix I thought a white powder like substance formed on the vessel but I'm not shure.
I didn't see real cristals so I filtered it. One big filter whit drab.
then I washed the filter whit alcohol. I still have this filtrate, it's dark red but I don't know if it contains any PA. does any of you knows what happened becouse this is my third attempt and it's beginning to nag me.

[mongo blongo]

vonK- I use methylated spirits and have had no problems. As long as the acetylsalicylic acid looks like fluffy shiny crystals then it's ok.
They will be died purple because the methylated spirits contains pyridine hence the purple colour.

[DBSP]

I had the same problems as you have. The red shit is the red foam and unreacted ASA I think. This is just a suggestion, I boiled down the liquid left as much as I could then I dissolved as much as I could in acetone then filtered again, then evapourate the acetone to get the crystals. PA is supposed to be yellow.

[Marbles]

I've just failed in detonating Picric acid[at least thats what I think it was] with Ag2C2.I made the PA by dissolving 16[500mg] unpurified aspirin tablets in 40ml of 97% H2SO4,leaving it for 1 hour and then slowly adding 8 grams of NH4NO3.I allowed this to cool to room temperature,poured it into crushed ice and filtered.I then purified by boiling.
But I just cannot get the fucker to detonate.This really pisses me off because I've tried 3 times before to make PA but everytime it failed to detonate.I press it into a 1/4 inch plastic drinking straw and then on top of this I've put Ag2C2 or AP,just pressed enough to hold the primary in place.How sensitive do you guys find your PA to primaries?I've also tried AP putty.I honestly can't see where I'm going wrong.Please help me or I'll fucking burst with anger.

[ALENGOSVIG1]

I've never had a problem detonating it. Just make sure its completely dry. I usually press it into 1/4" aluminum tubes. Be sure to press the primary very well.

[vulture]

Stanfield, what's the name of the company that resells acros products, maybe they have a bussiness in Belgium too?

[NG]

I was completing some PA using alens instructions exactly but scaled down by 80%. (32 asprin, 56ml 98% sulphuric acid and 19g potassium nitrate). As I was going onto stage 13 & 14, there was a strange layer floating on the top (This looked like algi floating on a pond). Does anyone know what this is or what might of caused it??? could I have done the stages to fast, or is it just impurities???

Thanks in advance
NG

<small>[ March 19, 2002, 10:13 AM: Message edited by: NG ]</small>

[Zambosan]

Impurities, maybe?

<small>[ July 18, 2002, 12:39 AM: Message edited by: Zambosan ]</small>

[Anthony]

Watch out for pressing peroxide primaries straight onto TNP, it is acidic and cause the peroxide to decompose explosively. You need a thing barrier, even if it is just a piece of plastic film.

[NG]

When I had finnished adding the KNO3 it looked like froth in the beaker, I left it for a few mins and it turned back into a red liquid. When I stired it againg the solution once again turned to froth.

Were the bubbles formed by the HNO3 decomposing, or by the acetylsalicyclic (sp) acid decarboxylating. And so should I have continued stiring until no more bubbles were formed, or simply ignore this and follow the procedure as normal? :confused:

Edit: this froth is different from the froth in my previous post. This froth was present while the reaction was occuring, where as the other was only noticed when I was trying to recrystalise the PA from water, as it would not disolve at all.

<small>[ March 20, 2002, 05:46 AM: Message edited by: NG ]</small>

[vulture]

Stanfield, why don't you just buy phenol, nitrophenol or dinitrophenol from acros?

[vonK]

How do you guys dry you picric acid.
My last two batches have refused to dry.
I've got 50 asprins worth of picric acid sitting outside in the blazing sun right now, it's already been there for three hours and is no drier than when I first put it out there.
Also the paper towel I filtered it through has turned brown and feels slimey.
Anyone know whats going on.

Kurt

PS. I haven't tried to purify it, do you think I should try that?

[DBSP]

I dry my PA on a radiator. It's quite effective, and it dryes quickly.

[Dhzugasvili]

The last time i made some PA, it was unusually hard to detonate. Putting it through a drop test i found that it took a 1kg weight through 50cm to detonate the PA. It usually will take less than this to detonate. Also, i used the same procedure (direct phenol route) and amazingly enough there was no crystalization in the nitrating "syrup" after two hours and a half of heating as stated in procedure, crystalization occurred after nitrating mix was taken off from heat and cooled...but it was very "bubbly/puffy" crystalization of Picric....hmmm...i wonder what caused this...i suspect it could be the nitric i used which had some impurities.

[CyclonitePyro]

I bought 4, almost 1000mL bottles of 70% isopropyl alcohol because it was on sale and I need it to purify the ASA, how can I make the alcohol close to 100%, distillation, boiling, or does it form an azeotrope with water? Or should I just but some ethyl alcohol(denatured)? (I have very little of it)

[Polverone]

The first time I tried to purify aspirin of binders I used denatured alcohol. I got impatient waiting for the alcohol to evaporate so I set the alcohol/acid mixture on a hotplate on low heat. When it got mostly evaporated I was left with a horrendous sticky mass of methyl salicylate and acetylsalicylic acid. Whoops. Mr. Methanol and Miss Acetylsalicylic Acid got to know each other rather intimately in that evaporating dish. It was taking forever to clean the mess out with water or alcohol, but acetone worked like a charm. So the next time I tried to purify aspirin I just used acetone and all was good. There was really fast evaporation, no reaction, and nice crystals left at the end. Plus the binders (outside tablet coating, actually) were completely left behind with the acetone, whereas they kind of softened and clumped with the alcohol.

[DBSP]

You could probably distill the isopropyl. Boiling point is 82,4 degrees C.
check this: <a href="http://chemfinder.cambridgesoft.com/result.asp" target="_blank">http://chemfinder.cambridgesoft.com/result.asp</a>

[nbk2000]

I think the foam is caused by rapidly released NOx bubbles. When you add nitrate to the acid, it reacts, forming sulphate along with free NO radicals. The nitrate gets a coating of sulphate that protects it to some degree from the acid. But when you stir it, it breaks this coating, exposing it to the acid which then causes the vigourous foaming.

That's my theory anyways. :D

I believe isopropanol forms an azeotrope in the high 80's-low 90's percentage. Distill it as much as possible, and remove the rest of the water with quicklime. You could also try microwaved epsom salt. But I think that makes some kind of solid addition complex.

The blackbooks say use alcohol, probably because it's easier to get in the third world than acetone.

Avoid using boiled down battery acid if you got it from a used battery. There's going to be some traces of lead in it, and that will form lead picrate in your TNP. This could cause an accident when making your det.

A drop of wax on top of your pressed TNP should form an adequate barrier for using AP if you've pressed the TNP well enough to prevent breaking the wax crust when pressing the AP.

You can recrystallize it by dissolving in the minimum of hot acetone or alcohol, then pouring into ice cold water. Since picric is much less soluable in water than the solvent, and being diluted by the water, it will precipitate out, leaving impurities still dissolved in the water. Filter, rinse, dry.

My mix was black before adding the KNO3, then turning to very dark orange/red with some NOx fumes and frothing. But nothing too bad. You should use a jar or beaker at least five times larger than volume of your ASA/acid mix to contain the foaming if it happens. Otherwise you'll lose product.

I saw a bottle of phenol for sale at an electronics store. Not the rat-shack kind, but the kind that engineers go to for their parts. It was used for circuit boards. Either cleaning or etching, I don't remember which.

[CyclonitePyro]

Thanks for the suggestions. I only paid about $0.70 for each bottle, and I have plenty of acetone, so that's what I'll use. I usually assume that the best method is given, but that's not the case.

I just looked an msds for ASA and under solubility it said ACETONE : >=100 mg/mL @ 23 C (RAD) so for 500 325mg tablets I'll need 1625mL of acetone to dissolve all the ASA. Right? How much if I heat it up?

<small>[ March 25, 2002, 12:19 PM: Message edited by: CyclonitePyro ]</small>

[Polverone]

I do remember needing a fair amount of acetone (relative to my tablets) to dissolve everything. But it was manageable because I wasn't trying to process 500 tablets at once! Ah, well, dollar store aspirin and paint store acetone are cheap. You could try heating the acetone, but I'd A) not heat it very strongly and B) do it in a sealed container.

When I want to heat acetone and something else (not something explosive!) I pour the acetone and material into an empty red wine vinegar bottle and screw on the plastic cap. It keeps the acetone from evaporating but if the pressure builds up too much it starts gradually venting from the cap, so I don't have to worry about explosions. I don't heat it with an open flame, of course! Now that I think about it I believe I gently heated my aspirin and acetone, using hot water from the tap. It didn't make a dramatic difference, but when I filtered the stuff the filter paper almost immediately afterward went stiff/crusty from all the crystals suddenly forming in it.

[nbk2000]

Sounds like it's time for you to discover the joys of a soxhlet extractor. This is a filter basket that hangs underneath a condenser inside of a flask of boiling solvent.

<img src="http://www.chemglass.com/images_product_1/1368.gif" alt="" />

The solvent fumes go up into the condenser where they cool and reliquify, thence to flow down over the (in this case) aspirin powder, extracting out the ASA. The solvent is constantly boiling, and there's a constant flow of pure solvent over the aspirin.

A cup or two of acetone could extract unlimited amounts of ASA, up till the point where the boiling acetone is a slurry of ASA crystals.

:D

[vonK]

Has anyone else ever had problems with picric acid being hygroscopic?
My last two batches have refused to dry.
I threw out the last batch. The one I've got now I purified by dissolving in boiling water, cooling to 5C and filtering the crystals. They've been sitting in the open for 4 hours and still show no sign of drying.
This is really starting to piss me off.
Does anyone have any idea what is going on?

[andreas]

I think I found the problem. For my procedure I use paracetamol, witch contains N-acetyl-paraaminophenol (C8H9NO2)
I did a surch on asprin witch is acetylsalicylic acid as we al know by now.
I think I failed becouse the paracetamol contains a different phenol deriffative that could react in a different way as aprin will.
Your thoughts or suggestions are welcome. I used the procedure that is on the flash bang boom page <a href="http://flashbangboom.homestead.com/home_page.html" target="_blank">http://flashbangboom.homestead.com/home_page.html</a>

[mongo blongo]

Your tabs should be the cheap ones which only ASA and binders!
I.E. no paracetamol.

[nbk2000]

Here's the results of a quick and dirty test I tried with acetone and 70% isopropyl alcohol.

I crushed 20 generic aspirin tablets and heated it in a water bath with about 90ml of CP acetone. Once it was boiling, I filtered it hot and evaporate the solute to dryness.

It came out as a very fine, snow white, powder. There was a few percent (by volume) of insolubles left in the filter and boiling flask. The powder had almost no smell.

Next, I took the same powder, and followed the same procedure with the 70% isopropanol.

This took significantly longer evaporate to dryness. It came out a kinda clumpy mass of flaky plates with an off-white (yellowish) tint. It was difficult to powder because it had a lot of residual water and smelled funky.

There was practically no residue from the filtration of the isopropanol.

My conclusion:
Acetone has it all over rubbing alcohol for purifying aspirin for PA (TNP) synthesis. It removes as much filler as isopropanol, dries very quickly, leaving a much finer and cleaner product for subsequent use with no funky colors or smell like Iso-p leaves.

Naturally, I expect others to do a more detailed analysis.

[S. Toppholzer]

I have searched the Forum and unfortunately, I didn't dig up the information needed.

I bought quite some amount of pure (Merck) acetyl salicylic acid (sp?) and a bottle of pure (98%) H2SO4, also some saltpeter, technical grade. I've got all the glassware for preparing PA right away and that's what I did.

I have been trying mostly a method I found somewhere in the Forum Archives of a ratio like 10 mg Ac.acid, 37,5 ml H2SO4 and 19 g Saltpeter. Everytime I tried that recipie, I felt that this suggests far too much Saltpeter. It always seemed the nitration is finished with, say approx. 10 grams. The more I added Saltpeter the more imurities (aka "the red stuff") I got in my PA.

I tried a ratio of 20:50:15 (see above) and the result seemed much better. After nitration I poured the liquid into twice the amount of water which wasn't cooled. I instantly got a thermic reaction (didn't measure temp, though) so I decided to let the stuff sit a bit further away from me (as far as I know PA is safe up to about 120°C).

After some 30 minutes, a huge amount of impurities has settled at the top of the beaker and became crusty. Below the yellow crystals of PA.
Maybe this would be a method of a one-step purification?

I tried to purify PA with mega's method by using boiling water. The impurities settled not at the top as described by mega but at the bottom of the beaker. This method leaves me still with a considerable amount of impurities. I tried using the hot alcohol method, but that was a complete loss.

I dissolved the PA crystals in as much of hot alcohol as needed. But every time I try to re-crystallize the PA out of the alcohol solution I get more or less a zero return. No matter if I use hot or cold water, no matter if I use just a bit of water or more than the double amount - nada.

Anyone got an idea what I am doing wrong??

[S. Toppholzer]

Just another basic question about TNP - I found contradictory comments about TNP reacting with metals. Most state that TNP should NOT - IN NO CASE - come in touch with ANY metal at all.
Other sorces though state that aluminium would be ok - no danger of formation of dangerous salts.
Since aluminium tubes are commonly used for detonators a correct information might be valuable.

[kingspaz]

not sure about aluminium, to be safe i wouldn't mix it with any metals. i can't see why aluminium picrate wouldn't form though...could be something to do with Al^3+ but still i can't see why it wouldn't form....

[vonK]

I once left some picric acid to dry on an aluminium pizza tray.
After one week all the picric acid had turned a light brown colour that sparkled in the light. I scraped it off with a teaspoon and then washed the tray under hot water. The brown crap just seemed to dissappear and left an incredibly clean tray.
If it's any consolation I couldn't get the brown crystals (aluminium picrate?) to detonate.

[Zambosan]

Wouldn't picric acid decompose in UV light?

<small>[ July 18, 2002, 12:44 AM: Message edited by: Zambosan ]</small>

[kingspaz]

i believe if the picric acid is slightly damp then the less sensitive hydrated picrates will form.

[nbk2000]

Here's a patent for purifying aspirin using acetone.

<a href="http://164.195.100.11/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=/netahtml/search-bool.html&r=1&f=G&l=50&co1=AND&d=pall&s1='2890240'.WKU.&OS=PN/2890240&RS=PN/2890240" target="_blank">US Patent #2,890,240</a>.

Lists solubility in acetone at various temperatures too.

[S. Toppholzer]

NBK:
Thanks for that link. Unfortunately, it says
"Full text is not available for this patent. Click on "Images" button above to view full patent."
But clicking that link doesn't do any good - the screen stays blank.
Could you please tell me one of the acetone purification methods you tried and that worked?

[wantsomfet]

S.Toppholzer - you'll need the AlternaTIFF plugin to view TIFF images in your browser...
<a href="http://www.alternatiff.com/" target="_blank">http://www.alternatiff.com/</a>

<small>[ April 11, 2002, 03:15 PM: Message edited by: wantsomfet ]</small>

[S. Toppholzer]

Thanks wantsomfet! Works perfect now :)
Can I assume that this process of crystallizing Aspirin from hot acetone also applies on TNP? Do you have a good method?
You know I tried so many times with soi much loss of product - I'd really like making it right this time (not quite cheap, that stuff)

[Mr Cool]

Yes, of course you can. That sort of thing has been discussed countless times, in countless different topics. Just adjust the mass used to account for their different molar masses.
But at least you didn't start a new topic...

[nbk2000]

TNP and aspirin are entirely different chemicals. So it won't apply directly across.

But the principle of using a small amount of strong solvent, and drowning in a large amount in weak solvent could be used.

[vonK]

Today I made TNP from methylsalicylate (oil of wintergreen).
I'm not sure if other people use this method. I chose to use methylsalicylate instead of acetylsalicylic acid from asprin because it is cheaper for me.
I followed Alen's method but substituted the ASA for an equimolar amount of methylsalicylate and scaled it down 2.5 times.

100 aspirns(325mg) = 32.5g = 0.18mol
0.18mol methylsalicylate = 27.5g = 23ml

I noticed a few differences between this reaction and the one with ASA.
During the addition of the methylsalicylate there was no gas released, the colour became a very light golden brown and the temperature rose by 8C.
After heating the solution at 70C for 15mins I added 61g of KNO3.
At first I tried to add it while the solution was at 65C, instant NO2 fumes and the solution turned a dark brown with possibly a green tint.
I let the solution cool to 40C before I added more KNO3, there was absolutely no gas released this time but the solution slowly turned a dark orange and every time I added some KNO3 the temp shot up 10C so I let it cool again before adding more.
As I added KNO3 I noticed what looked like tiny gas bubbles suspended in the soloution, it was thick with them but none broke the surface.
When I was about half way through the KNO3 the gas final started to fizz out of the solution, slowly at first but as I progressed through the KNO3 the fizzing became more vigorous. The gas seemed to lag behind the addition of the KNO3. When I stirred in the KNO3 the solution became thick with suspended gas bubbles and about 10 seconds later it would all fizz up leaving behind a now, very deep red coloured solution.
The precipitation of the TNP in crushed ice and filtering was identical to the ASA reaction.
The yield seems quite good, my paper towel filter is filled to the brim, when it is dry I will weigh it.
Overall I'm quite happy with the reaction , it's cheaper for me to use methylsalicylate and less effort since there is no need to extract ASA or any need to dissolve it in the acid.

[S. Toppholzer]

vonK:
Can you tell me any common source for methylsalicylate? Where could I get it from? Are there any products "out there" wheer it is contained relatively pure?

[nbk2000]

From what I've seen, it's usually kept with the ipecac syrup, glycerin, and other liniments at the pharmacy.

But, in the US, it's much cheaper to buy aspirin then the green oil.

Can get 162 grams of ASA from 500 tablets for just $1.

[S. Toppholzer]

you mean that green stuff - the ipecac syrup - is methylsalicylate?

[nbk2000]

No. Ipecac is NOT methyl saliyicate. It's called "oil of wintergreen" (I believe) and is usually kept along with ipecac.

[S. Toppholzer]

yup. Thought that :p
NBK: this "oil of wintergreen" - what is it used for? You see, if I'd go to the shop asking for methyl saliyicate I'd just get a blank stare from friendly but rather stupid maids. If I could tell them: That's the stuff used for blah,blah... ya know? If they hand me the stuff I could check the contents on the carton to see if it's the right stuff.

vonK:
"Overall I'm quite happy with the reaction , it's cheaper for me to use methylsalicylate and less effort since there is no need to extract ASA or any need to dissolve it in the acid. "
Maybe I didn't understand chemistry 101 but isn't the sulfuric acid necessary for the nitration process? Do you add the KnO3 DIRECTLY into that "oil of wintergreen" an it reacts on itself?

<small>[ April 16, 2002, 01:45 PM: Message edited by: S. Toppholzer ]</small>

[nbk2000]

Here's the Merck listing:

Methyl Salicylate . CAS Registry number: [119-36-8] CAS name(s): 2-Hydroxybenzoic acid methyl ester Additional name(s): wintergreen oil; betula oil; sweet birch oil; tea berry Molecular formula: C 8 H 8 O 3 Molecular weight: Percent Composition: C 63.15%, H 5.30%, O Literature references: Present in leaves of Gaultheria procumbens L., Eri ca ceae, in the bark of Betula lenta L., Betulaceae; prepd by esterification of salicylic acid with methanol. Toxicity data: P. M. Jen ner et al., Food Cosmet. Toxicol. 2, 327 (1964). Properties: Colorless, yellowish or reddish, oily liq; odor and taste of gaultheria. mp minus8.6degrees . bp 220-224degrees . d 25 25 1.184 . d of the natural ester is approximately1.180 . n D 20 1.535-1.538 . Flash pt, closed cup: 210degreesF (99degreesC). Slightly sol in water: one gram in about 1500 ml; sol in chloroform, ether. Misc with alcohol, gla cial acetic acid. LD 50 orally in rats: 887 mg/kg (Jen ner) . Density: d 25 25 1.184; d of the natural ester is approximately Boiling point: bp 220-224 Melting Point: minus8.6 Refraction index: n D 20 1.535- Note: Caution: Potential symptoms of overexposure are hyper pnea, apathy, lassitude; anorexia, nausea, vomiting, thirst; headache, dizziness, tinitis, difficulty with hearing and vision; confusion, irritability, mania, generalized convulsions; deep coma, death due to respiratory failure or cardiovas cular collapse. Direct contact may cause irritation of skin and mucous membranes. See Clinical Toxicology of Commercial Products, R. E. Gosselin et al., Eds. (Williams and Wilkins, Baltimore, 5th ed., 1984) Section II, p 205; Section III, pp 368-375. USE: In perfumery; for flavoring candies, etc. THERAP CAT: Counterirritant. THERAP CAT (VET): Counterirritant.

I believe it's used in the US as a toothache remedy or astringent (skin drying).

The sulfuric is still needed, whether you're using Aspirin or MeSA.

[vonK]

Methylsalicylate is used as a "rub in" pain killer and to warm up stiff muscles, sports people use it a lot.
I find it on the same shelf as the iodine tincture, peroxide, precipitated sulfer etc.
Ever heard of Deep Heat or Linament, they are both preperations that contain methylsalicylate as the main ingreadient.
When I said there is no need to dissolve the ASA I meant, you don't have to spend a long time dissolving the methylsalicylate because it is a liquid, where as it can take quite a while to dissolve the ASA. You still need the H2SO4.
By the way, I am now convinced my TNP is hygroscopic.
I fan baked it in the oven at 75C for two hours, it came out quite dry, I think it was still a little wet but it appeared dry. Now two days later it is swimming in water, it has just been sitting on my shelf on a sheet of plastic.
Can anyone help me?
If I can't get it completely dry I'll just dry it as best I can and then turn it in to something else, probably DDNP.

Thanks
Kurt.

<small>[ April 18, 2002, 05:18 AM: Message edited by: vonK ]</small>

[kingspaz]

vonK, could it be residual H2SO4 in the TNP absorbing moisture from the air?

[Rhadon]

If the HCl should substitute your H2SO4 you're wrong - this won't work.

[kingspaz]

ok, the reaon it wouldn;t work is because H2SO4 (when pure) is a dehydrating agent. the nitric acid that forms from the
2KNO3 + H2SO4 ----> K2SO4 + 2HNO3
the nitric has the structure HONO2, the nitrogen being in oxydation state of 5.
when next to a hydrogen atom on a molecule, eg cellulose, you have this (imagine it in a picture and 3d, the first H being on another molecule and not bonded to the nitric at all)
-H H-O-N=O2
the H2SO4 can then remove the water from this, the hydrogen on the cellulose and H-O on the nitric making H-O-H (water!) this leaves the NO2 radical to join up with where the hydrogen was.
i've never seen this anywhere i don't think, so the chances are its wrong since its my explanation. i think the actual mechanism is different than this for TNP, but the H2SO4 still serves to 'soak' up the water keeping the dissolved nitric concentration high.
can somebody explain the mistakes i;ve made here....would help me greatly...

[Rhadon]

Kingspaz, your mechanism is alright for the reactions in which an ether is formed.
In the case of TNP (when making it with phenol), the H2SO4 reacts with the phenol and forms phenol-2,4-disulfonic acid. Later on, the HNO3 replaces the HSO3 groups with NO2. I think it works that way, but I'm not 100% sure

[kingspaz]

yer thats the way i thought it worked but didn't know what the intermediates where called. i've just read chemistry of powder and explosives and that is what happens, well more or less. i scanned the page for people to look at if they wish. the link must be copied and pasted into your browser.
<a href="http://www.angelfire.com/mo3/kingspaz/tnp.JPG" target="_blank">http://www.angelfire.com/mo3/kingspaz/tnp.JPG</a>

[vonK]

Thanks Kingspaz, that seems to have been the problem.
I washed my TNP again in 700ml of iced water a couple of days ago and now it is completely dry, well I can't be totally sure but I can find no sign of moisture.
It now weighs 38g (roughly). I lost several grams during filtering and such but this yeild still seems quite good.
Does anyone know how this yeild compares with yeilds when using 32.5g ASA?
BTW I have stained the bathroom bench with TNP and my Mum is really pissed. I think the bench is made of formica. does anyone have any idea how I could clean it? If I can't get it off I'll be in real shit :( .

Thanks
Kurt.

[CyclonitePyro]

Alen, I know it's been awhile, but how much TNP did you end up with dry? Also, did you go on and try DDNP?

[ALENGOSVIG1]

CyclonitePyro: Now that i think about i dont believe i ever weighed it. :(

Ill make more soon and i'll be sure to weigh it.

And yes, I did make the DDNP.

<small>[ May 20, 2002, 05:58 PM: Message edited by: ALENGOSVIG1 ]</small>

[andreas]

Extremely hot water would work or acethone but that would be a wast of acethone. Wear gloves when handeling it it can couse liver problems i've heard an overdose can cause you're blood to look like molten chocolate

[vonK]

Thanks andreas, but I got it off a long time ago.
I used a detergent called "Jif", a heavy scouring pad and a lot of scrubbing.

I have a question.
When you guys make TNP, do you leave it as that incredibly fine powder that it is when you dump the acid mix into cold water, or do you dissolve your TNP in hot water and let it cool slowly to give larger crystals?

Thanks
Kurt.

[andreas]

I leave it as fine cristals but I already had some precipitate in the acid mix which looked like yellow froth on top of the acid.I've redone the experiment in my dream and found pictures somewhere <img border="0" title="" alt="[Wink]" src="wink.gif" />
startingmaterials
<a href="http://www.angelfire.com/mac/detonation/tnp1.JPG" target="_blank">web page</a>

startingmaterials after purification:
<a href="http://www.angelfire.com/mac/detonation/tnp2.JPG" target="_blank">web page</a>

after the asa has dissolved in the sulphuric acid:
<a href="http://www.angelfire.com/mac/detonation/tnp3.JPG" target="_blank">web page</a>

Half way through the nitrate addition:
<a href="http://www.angelfire.com/mac/detonation/tnp4.JPG" target="_blank">web page</a>

3/4 through nitration you'll see the mix clearing up and getting more yellowy:
<a href="http://www.angelfire.com/mac/detonation/tnp7.JPG" target="_blank">web page</a>

After all the nitrate has been added and the mix is starting to cool: <a href="http://www.angelfire.com/mac/detonation/tnp9.JPG" target="_blank">web page</a>

after teh mix has reached roomtemp.:
<a href="http://www.angelfire.com/mac/detonation/tnp10.JPG" target="_blank">web page</a>

after ice water has been added:
<a href="http://www.angelfire.com/mac/detonation/tnp11.JPG" target="_blank">web page</a>

yeild from 40 grams of asa
[URL=http://www.angelfire.com/mac/detonation/tnp12.JPG]
you will need the right click the links and kopy and paste the url in a new window

<small>[ May 27, 2002, 06:48 AM: Message edited by: andreas ]</small>

[andreas]

it's drying now you'll al hear of the actual yeild lost something in purification :p

[DarkAngel]

None of the pictures work.

[mongo blongo]

Not working for me too.

[andreas]

well the last link you'll see the adress just copy paste the link and then substitute the 12 for 1 to 12
or look at properties and the adres shows up there.
sorry for the inconvinience

[CyclonitePyro]

I tried picric twice and failed, both times I adjusted the size of the reaction but forget to adjust how much water I pour the whole beaker into and end up drowning the picric acid in water and then just throw it all a away.
I'll remember next time though :rolleyes:
When I add the mix to the water at the end, red nitrogen dioxide started coming out of the water, nearly none came off during the KNO3 addition, maybe it is because the nitric acid that is created contains alot of NO2 and when it gets cold it can't hold all of it and it gives it off?
Also, I get this goo, as described by someone else, probably because of the drain cleaner's additional ingrediants, it would take too long to spoon it out, how else could I get this floating layer of gobs of goo off, I can't let it get in with the picric acid when I filter it.
And, I know I would be getting a decent yield because after an hour or 2, when I let it cool, the mix get thick with crystals, and a hard layer of crystals forms on top.

[cutefix]

For people who are Picric Acid Fanatics ……Have you seen these site?
<a href="http://www.powerlabs.org/chemlabs/picric.htm" target="_blank">http://www.powerlabs.org/chemlabs/picric.htm</a>

[CyclonitePyro]

I don't think I was clear in the post above.
Can anyone think of a way to remove the upper layer of goo in a beaker full of picric acid synthesis solution, containing H2SO4, HNO3 and Picric acid on the bottom?

[megalomania]

You may try a low power suction device by connecting an aspirator to a bottle and another line from the bottle as your suction tube. The crap gets sucked into the bottle. In a pinch (for those w/o aspiration) try a nice big turkey baster. I think you can get one for $1 US.

[kingspaz]

couldn't you pass the mix through a filter? the goo would be too thick to pass through the filter so would be removed.

[CyclonitePyro]

I can't pass the mix through the filter because the picric acid is precipitated on the bottom of the beaker, I can't let the crystals get in with the goo, they will stick.
I have a vacuum pump, I could try that idea, the only thing I can think of is the goo clogging the tube like someones arteries. That could be solved with large diameter tubing.
I'm not going to try any more reactions until I get some proper lab filtering devices either.

Thanks for the ideas.

[Microtek]

If the goo is floating at the top and the PA is sitting on the bottom, can't you just decant it? Or skim it off with a spoon?

[mr.evil]

in a dream i tried to make TNP again, really funky this time;

50ml 98% H2SO4
25gr. KNO3
10gr. ASA

After i added the ASA to the H2SO4 it became dark brown, after this hotted the mix to 65C. Then i added the KNO3, it didn't became red.. so i warmed up the mix a little bit (to 75C.) NOX came off, so i stopped heating and cooled the mix to 50C. Still no deep red color like the other times i made TNP. I got a little irritated so i putted the mix in 2C. water, it became nice red, but again with lots of NOX(a thick orange layer of bubbles at the top), i filtered the mix and let it stand for about 20minutes. Then, when i looked again there were some (red?) crystalls in it, so i filtered it again; yeild:
7grams of RED(?!)TNP...i had Yellow, green and pink crystalls, but never red!! anyway, my fingers are bright yellow now :rolleyes: and also the bathroom :p so i will get a fight with my mom this afternoon..

no, but has anyone got the same problem? (NOX, Red crystalls, Yellow fingers? (joke)... in some ways i think TNP is a bitch of an explosive when preparing it, i've made it 8times now, and only 4times it worked.. hmpf!

[VX]

Does anyone know what this yellow frothy goo that form actualy is? I have made picric a few times now and each time I get this froth, However I uses lab grade KNO3 and Sulphuric acid and purifies ASA (from asprin).

So I dont beleive that they are due to impurities in anything.

Perhaps they are mononitro phenol, or dinitro phenol?? They look like frothy TNP, in my case at least.

Any ideas??

[kingspaz]

when KNO3 is added the COOH group on the benzene ring is attacked by HNO3 resulting in attachment of a nitro group to the ring and the formation of HOCO2 whihc decomposed to H2O and CO2. the CO2 will cause bubbles which will foam the solution. so the foam is just TNP/acid solution with CO2 in it. i think <img border="0" title="" alt="[Wink]" src="wink.gif" />

[Madog555]

mr evil, i recently tried a big batch of TNP and it was red too! i think it was mononitro/dinitrophenol. i used mr cool method. TNP is a pain in thje ass, but it is a must for the lab. im gona try it again soon.

[mr.evil]

Madog; hmmm.. a while ago, when i made TNP for first my batch was Pink(!) after boiling it it became yellow so it must have been some pulution or something(acid i think).

i've just e-mailed a chemshop in my country, they sell Phenol so hopefully they will sell it to me(ASA is expensive)

anyway, about the red TNP, i've saved some solution(with some crystalls) but on the sides of the beaker there is some red mas(with air i think, you can see some bubbles..) when i light it it burns with a fizzling sound and a small flame...

BUT:
If it is Dinitrophenol, could you make DDNP of it then? (as DDNP is DiazoDINITROphenol)

<small>[ June 11, 2002, 01:57 AM: Message edited by: mr.evil ]</small>

[Madog555]

damn, i boiled my red TNP(well DNP) and it didnt do jack. i also tried to renitrate it more. im gona do another batch soon

<small>[ June 11, 2002, 08:42 AM: Message edited by: Madog555 ]</small>

[Mr Cool]

I think MNP, DNP and TNP are all varying shades of yellow. Not red. If it's still red after recrystalising it, then it might have been oxidised or something?
When I make TNP it normally pptes yellow, but it has been pink before for me too. This always goes yellow after recrystalisation (the pink crystals dissolve to form a yellow solution, which crystalises to give yellow TNP). I think it's just due to a different crystal form or something. It's definitely TNP, and quite pure too.

[S. Toppholzer]

I made PA several times and the only problems I ran into was the re-crystallisation process after purification. I use chem grade 98% H2S04, pure KNO3 and pure ASA (Merck). However, my PA crytals always had some shade of yellow except of once when I sort of overnitrated it and I was left with some brownish gum-like substance.
As I write thes lines I recall some red stuff that sometimes showed at the bottom. It appears way before the actual PA crystallizes out and looks like droplets at the bottom of the glass. My method of getting rid of this sort of impurity (where the hell does it come from when using chem grade material??? :confused: ) was to let the whole stuff cool down to room temp. and then decant as much as possible before purifying the PA.
nb: I guess this red substance forms up especially when rushing the nitration. The smaller amounts of KNO3 added, the more patience the less of this substance shows up it seems.

<small>[ June 11, 2002, 04:32 PM: Message edited by: S. Toppholzer ]</small>

[Zambosan]

Hazardous decomposition products: Carbon monoxide, oxides of nitrogen, carbon dioxide

Out of the above, I think the NOx is certainly the worst to worry about.

<small>[ July 18, 2002, 12:46 AM: Message edited by: Zambosan ]</small>

[cutefix]

Picric Acid has an oxygen balance of about -45%.Therefore it will form carbon residue just like TNT(has OB of -74%).
If they are detonated the smoke will appear blackish.due to formation of finely divided carbon.
Many burnt organic matter including explosives display these sweet smell. It includes TNT and DNT...
Being a nitrocompound,its normal to exude NOx fumes on decomposition.But as Nitrogen oxide exhibit reddish color on evolutions,it not much to worry about and easy to avoid.Rather its the carbon monoxide because its odorless...And the combination of these oxides makes it toxic....

[Helos]

I thought about an blasting cap of aluminium with TNP.
Why can it (al+TnP) selfignite(?) in the precense of water?
The oxide will protect the TNP from the altube but is it safe to store?
And what is the metalsalt that TNP can form with Al, because if it isn´t dangerous or sensitive it will be nothing to worry about..

[cutefix]

I would not recommend to expose Picric Acid with metals as its risky due to the formation of sensitive picrates.
If you want to use aluminum tubing then its better to coat it with wax (or similar stable coating)before you place your booster(TNP)in the bottom ,while your primary is on top of it.

[kingspaz]

Helos, ALL picrate salts (TNP is the same as picric acid) are explosive. the Al2O3 layer will not protect the Al at all since it will react with the H+ ion provided by the picric acid:
6R-OH + Al2O3 --&gt; 2Al(R-O)3 + 3H2O
R-OH representing picric acid.

[frostfire]

ALENGOSVIG1, with the H2SO4/KNO3 method, you only performed a single nitration right? So how does the TNP formed? or if it is, then it must be partial and very impure.
In TNT nitration which I'm more familiar the tri-nitro configuration is formed with at least 2 nitration....any theory/reasoning??? :confused:

[Rat Bastard]

I saw in the "Forum vid and pic" post, that andreas made TNP with AN instead of using KN03.

I searched and came up with no recipie for the AN method.

Does anyone know what recipie/procedure he used?

<small>[ July 06, 2002, 11:30 PM: Message edited by: Rat Bastard ]</small>

[kingspaz]

frostfire, the reason for only one nitration step being required is because the phenol group weakens the ring to substitution more than the methyl group on toluene. i think <img border="0" title="" alt="[Wink]" src="wink.gif" />

[da man]

I remember someone asking what is formed when you react the acetylsalicylic acid with sulfuric acid.
I just read the reactions that proceed with acetylsalicylic acid and sulfuric acid in chem labs.
The sulphuric acid catalyses the breakdown of acetylsalicylic acid to acetic acid, and salicylic acid:
. H2SO4
C9H8O4 -------&gt; C2H4O2 + C7H4O2
The salicylic acid produced then reacts with water to form phenol and carbon dioxide:
C7H4O2 + H2O ---&gt; C6H6O + CO2
Question is, where does the water come from?
The phenol then reacts with the sulfuric acid to form phenolsulfonic acid! Which is then nitrated.
But where does the water come from in the second reaction?

<small>[ July 07, 2002, 07:12 AM: Message edited by: da man ]</small>

[da man]

Also, i am planning to make picric acid from aspirin soon, and i have dissolved 150, 300mg aspirin tablets in 500ml of acetone. I want to know if i can boil off the acetone, because it takes a bloody long time to evaporate it at room temperature. I just checked chem finder, and it says it melts at 135*C, and boils at 145*C, so i imagine i can boil the acetone off (acetone boils at 56*C) without decomposing the acetylsalicylic acid?
Thanks!

[kingspaz]

yes you can boil the acetone off. just make sure you've filtered it first to remove the fillers <img border="0" title="" alt="[Wink]" src="wink.gif" />
now about the TNP from aspirin. i beleive what happens is that the traces of water in the H2SO4 (there is allways some water in it!) hydrolise the ester bond forming salicylic acid and ethanoic acid (acetic acid). the salicylic acid is then sulfonated when heated to about 60*C turning the mixture blackish. upon addition of KNO3 the COOH group is removed by the nitric acid as are the two SOOOH groups. this results in carbonic acid (H2CO3 which decomposes to H2O and CO2 and the two SOOOH groups are converted back into H2SO4. where these groups have been removed the nitro group take their place.
hope thats helped.

edit: i'm pretty certain this is how it happens because i've been researching and working this out for the past month and a bit!

<small>[ July 07, 2002, 11:05 AM: Message edited by: kingspaz ]</small>

[mongo blongo]

Da man- If you don't want to take ages evaporate the acetone then simply dump the acetone/ASA into some cold water to precipitate the ASA and filter.
Rat Bastard- The method using AN is exactly the same except you will have to work out the new weight of AN with the same amount NO3 ions.

[ALENGOSVIG1]

Yeah precipitating the ASA in water would work. A mass of water soaked crystals would probally take longer to fully dry then 500 ml of acetone being gently heated would take to evapourate.

I'd just heat off the acetone.

[mongo blongo]

Yes you are right there. I use an improvesed Buchner suction filter so it's quicker for me. :)

[kingspaz]

dumping it in water may screw up calculations somewhat though.
ASA is hydrolised by water to form C2H3COOH (ethanoic acid) and SA.
ASA has molar mass of 166 ans SA of 138. this means when you come to weigh out the extract for nitration you end up wasting some since you need more moles of SA than ASA for a given mass. eg, 1g of SA will contain more moles than 1g of ASA. anyways, to cut a long short story short, this results in wastage of ASA and apirins. for people in the US this is ok but its not so good for people in the UK who can only buy 32 aspirins at a time <img border="0" title="" alt="[Frown]" src="frown.gif" />

[mongo blongo]

Are you sure because We used this method in chem class in college to purify ASA once we made it.

[kingspaz]

hehe, i am sure because we hydrolised ASA with water in my chem class <img border="0" title="" alt="[Wink]" src="wink.gif" /> .....it smelt of vinegar afterwards. in you chemistry class did you use the ASA in a reaction after purifying?

[mongo blongo]

We made ASA and then we dissolved it in methylated spirits and dumped it into water to crystallize pure ASA. I'm sure we were marked on the purity and yield. I will try and dig out my old college work and have another look.
I just remembered that you can buy aspirin that can be dissolved in water. I remember trying this and it didn't crystallize when dumped into water. I looked at the packet and it said "dispersible" and realized that I bought the wrong one (from ASDA). I think they were buffered or something.

[Microtek]

When making TNP from aspirin, I've found that the yield is better and the nitration smoother if nitric acid is used instead of KNO3. I am aware that nitric acid is produced from KNO3+H2SO4, but the KHSO4 produced in this reaction tends to increase the viscousity of the soln. This means that the CO2 released from de-carboxylation forms a resilient foam ( in my experience at least ) which makes further addition of KNO3 difficult and also insulates the container.
If ordinary 60-70 % HNO3 is used instead, possibly with a little H2SO4, a more mobile liquid is obtained which also facilitates mixing.
Of course, this is only really an attractive alternate if HNO3 is readily obtainable ( as it is here ).

[Helos]

ok, did you add as many moles HN03 as you added KNO3(or NaN03)?

Another thing, what do you use your TNP for. It is not a wery cheap explosive to use, so I will use it mostly to blasting caps.
I think that I will use plastic pipe instead of aluminiumtubes, even if they are coated with wax it seems unsafe and I am not shure were to find wax. I also had another thought, if I only can get aluminiumtubes I can use DDNP only(?) because it doesn´t matter wery mutch if I use 0,5gDDNP +1gTNP or 1,5g DDNP /cap. A single loaded cap with DDNP will be as strog as the other, or am I wrong?
I haven´t been able to get any information on what DDNP can react with (for example al) , but I would have guessed that it is not acidic and therefore not dangerous with metals

[Anthony]

Candles are made from parrafin wax, or less comonly, bee's wax. Both will work for coating Al tubes.

[S. Toppholzer]

Microtek:
</font><blockquote><font size="1" face="Verdana, Arial, Helvetica">quote:</font><hr /><font size="2" face="Verdana, Arial, Helvetica"> If ordinary 60-70 % HNO3 is used instead, possibly with a little H2SO4, a more mobile liquid is obtained which also facilitates mixing </font><hr /></blockquote><font size="2" face="Verdana, Arial, Helvetica">I'm a definitive nutcase when it comes to Picric acid - I simply love that stuff and thus I am always searching for ways of improving its production.
Could you please kindly provide me with a recipie using 60-70% HNO3? (I happen to have a liter of this acid and would like to put it to good use)

[Microtek]

The alternate method is actually very similar to the usual one ( I use the recipe on Mr Cool's site ); once the ASA has been dissolved in the H2SO4 you would usually add dry KNO3. Instead of this, add an equimolar amount of nitric acid. In other words, for every gram of KNO3 add 1 gram nitric acid of density 1.38 ( about 62 % ).
So, if you normally need 20 grams of KNO3, you instead add 15 mL 62 % HNO3 and maybe 5 mL H2SO4. I don't know if the extra sulfuric acid is neccessary; afterall there is already a lot of it in the beaker that would normally be reacted with the KNO3.

As to what I'm doing with the TNP, well I'm trying to make some DDNP. In fact I have a batch brewing as I write this, made using Mr Cool's pointers in the "DDNP troubles" topic.

[bonnsgeo]

hi,

does somebody have the dissolution table of picric acid in water please ?

thx

[lucifer]

I tried to make TNP with phenol, H2SO4(98%) and HNO3 (65%).
But failed and made a mess of my lab.

I added 25gr phenol to 46 ml H2SO4 and heated this solution for 30 minutes at 100 deg C
After this i cooled it down to 5 deg C
I also cooled 175 ml HNO3 to 5 deg C.

The solution of the phenol / H2SO4 was dark red.
There where also some large solids in the cooled solution (clumps in the solution).

I added while stirring slowly the HNO3 to the phenol / H2SO4 solution and the temperature rise to 20 degrees, no problem.

After a few minutes i picked up the glass which contained the solution.
Without any warning the acid solution jumped out of the glass and was dripping from the ceiling.
I guess I have to repaint the ceiling of my lab. It’s now yellow.

I assume the reason for this fountain reaction are hotspots created around or in the large solids of the phenol / H2SO4 solution.

Can any one confirm this?

I will retry to make TNP again, but I don’t want any acid solution spraying around me no more.
So I would like to find out went wrong.

[mr.evil]

i guess the temperature was a little to high? or the Acids have been added to quickly(NOX/NO2 was formed and the bubbles with the mix came out of the beaker?)

anyway, i see you are from holland to. Do you have MSN messenger? Can you e-mail me please, i've tried to e-mail you but i didn't got an answer, thanks :)

edit: some spelling mistakes

[bonnsgeo]

hmm ... lucifer .. 100 degres for dissolve the phenol is really too high !! i did without any problems at 55 degres. (you certainly destroyed the phenol ,it is a fragile molecule.)

i see you had clumps in solution ...its normal !! u used 46 ml of h2so4 for 25 g of phenol , it didnt all dissolve!!! ... me, i used 100 ml of h2so4 for 15 g of aspirin !!!!!! i think you must use more h2so4 (100 ml minimum for 25 gr of phenol) if u want all dissolve.

and if u used hno3 ... its not really a good thing.it works but the better thing to do is to use kno3 , because the nitration of phenol must be slow for not destroy the molecule (if u put directly phenol in 99 % nitric u wont have a lot of picric ...maybe nothing)

so use kno3... its better and safer (i m not sure of this word: safer) than hno3.

bye
<img border="0" title="" alt="[Wink]" src="wink.gif" />

[Kalium]

Excuse me if my english is so ugly.
I'm always prepareing picric acid from salycilic acid.
To prepare salicylic acid i put 25 tablets of aspirin(every contains 0,5g of ASA)and 200ml of cold water with some ml of H2SO4 into 500ml beaker, then heat it about 20-30 min. Then cool and filter salicylic acid(it looks like a cotton wool).
Put 10g of SA into 20ml pure HNO3. Stir about 20 min - it should become light-yellow(nitrosalicylic acid). Then slowly heat to 60-70°C for 15min while very intensive stirring(try NO2 not to become! only CO2). Then add 15ml HNO3 and 5 ml pure sulfuric acid and heat at 100°C for 15min. Then flow it in 100ml of water.Cool it and filter. If you made all right , yeild will be more than 80%.

[a_bab]

Yeah, I also used this method and it works. I used only HNO3 though. But it seems that it eats LOTS of HNO3; I'll try with H2SO4 as it seems to be better.

About the TNP color: I read somewhere that the pure picric acid recrystalized from HCl is colorless (transparent crystals) but because of the air humidity it'll turn into yellow. Also some picrates are coloured in red; such a impurity could be an explanation. In a small quantity it'll give pink, maybe.
Actually, the picric acid was the first chemical used to explain the colour given by the organic radicals and such.

[andreas]

Rat basterd use the method on mR. Cool's site (prety popular as it seems:-) ) and just substitute the moles of KNO3 for an equal amount of moles of NH4NO3 and this works just fine for me.

[lucifer]

Last week I made picric acid and I tried to detonate it,
but it failed. (I did try it twice)

I made sure that the picric acid was really dry.
I used 4gr PA and 1.5 gr HMTD in a straw to detonate the PA.
Both the PA and the HMTD where a little bit compressed.

The PA was in a piece of plastic tube with a diameter of about 3/4-inch

The PA i made also doesn’t really burn very good.
It more or less just glows and gets carbonated when you light it (very small amounts of course)
Is this normal?

Further the “PA” I made is yellow, not very soluble in cold water, but is soluble in hot water, soluble in ethanol and in a solution of water the yellow color disappears when a little H2SO4 is added.
So I assume it is PA.

Can anyone tell me what went wrong.

[shooter3]

I got rid of some old PA by burning. It was easy to light and burned with a yellow smokey flame. (It was from a batch that went off just fine). After it burned there was no residue.

It sounds like there is some contaminent in your Pa.

[mr.evil]

Maybe it was MNP...

[Helos]

Today I tried Picric acid, and I have many questions and things to share. I did two batches:

Nr.1: 160ml of sulfuric acid+ 30gKN03 +20g salicylic acid.
I heated the solution of sulfuric acid+ SA for twenty minutes at 70 degrees, let it cold then I added the KNO3 in portions. When I added the KNO3 I had an temperature between 20-50degrees.
After that I mixed in 500ml icewater and filtered.

Everything went fine and now I have the PA dissolved in acetone that is evapourating. One thing was strange through, at first I used NaNo3 instead of KN03. but it didnt react at all but the KNO3 reacted well.
Why didnt the NaN03 react, and can it be used?

I am also wondering if you think the proportions of the ingredients in this formula is good? cause I have seen a lot of differnet proportions.

Nr2. I had read the above replies about using HN03 instead of KNO3.
I did everything exactly the same as in my first batch, I think.
BUT, Instead of KNo3 I used an equimolar mass of HNO3 (30g)
I also added 6ml of sulfuric acid (98%) to suck up excess water.
i added the acid in portions under 15minutes and I also under some minutes put a platic cover over the reaction vessel to force the NO2 to dissolve in the mix.

The reaction seemed to be smother and better(but similar) to my first batch. However when I had diluted my batch with ice water and it had a temperature of 10 celsius, still no TNP crystalls had been visible (in nr1 it was a lot of them) The liquid changed color from orange to yellow during cooling. :cool:
I cant understand what went wrong
:o Is there anyone who can think of what went wrong, and how I can improve this method?

I have the liquid left if there are any posible way to use it, it apperantly is some TNP in it because it is yellow, but I am afraid that it is wery thiny ammount. <img border="0" title="" alt="[Frown]" src="frown.gif" />

[kingspaz]

evapourate the water off so you only have 1/3 of the solution left. then allow to cool and filter the TNP.
500ml ice water?...that seems alot for about 30g TNP...
1.2g/100ml....so thats 5*1.2 = 6g in solution. plus the solution will the nitrating acid present increasing solubility.

<small>[ September 15, 2002, 07:50 AM: Message edited by: kingspaz ]</small>

[Helos]

Today I tried to follow this formula (above)
---------------------------------------------------------
Put 10g of SA into 20ml pure HNO3. Stir about 20 min - it should become light-yellow(nitrosalicylic acid). Then slowly heat to 60-70°C for 15min while very intensive stirring(try NO2 not to become! only CO2). Then add 15ml HNO3 and 5 ml pure sulfuric acid and heat at 100°C for 15min. Then flow it in 100ml of water.Cool it and filter. If you made all right , yeild will be more than 80%.
------------------------------------------------------------------

But I used 65% HNO3 (pure may be 100%) I stirred and I dont think so much happened. I then heated it. At 40 C degrees a red growing spot formed in the white crystale mass of SA. It was a runaway reaction that produced a lot of No2 (I could smell it, but never saw it)
Luckili I fast dumed the whole shit in icewater (that becamed yellow of No2)

I also checked the failed solution (my post above) two days later.
Then an okay ammount of TNP crystals had formed, I was wey surprised that the reaction could have continued even as I had added a lot of extra water. I didnt boil it down, just cooled it more and filtered out the TNP althought it wasnt wery much.

[Helos]

I have an important question.

Can you use salicylic acid in a method that is for "TNP from phenol"

I figure out that salicylic acid readily conwerts to phenol when there are H2SO4, so just use an equimolar ammount of SA.

Or have i missed something? T

han correct me!

[kingspaz]

helos, that is correct! although the salicylic acid doesn not turn to phenol. it is first sulphonated during the heating stage and then upon addition of KNO3/HNO3 the COOH group is lost from the ring in the form of H2O and CO2 after attack by NO2+. you will notice gas production when the KNO3 is added.

[Helos]

Today I actually tested to do a TNP synth. with saliylic acid instead of phenol.
I used a process that are similar to these:

<a href="http://www.powerlabs.org/chemlabs/picric.htm" target="_blank">http://www.powerlabs.org/chemlabs/picric.htm</a>
<a href="http://www.flashbangboom.homestead.com/procedures.html" target="_blank">http://www.flashbangboom.homestead.com/procedures.html</a>

It is intressting to see the differences between these (and a third, also similar) methods, the ammounts of chemicals are very different, for example mr.cools method has more than 200% more than the teoretical nitric acid needed!

I also used more than teoretical of acids however.

My calculation resulted in this:

TNP
----------------------------------------------------------------------
1. Put 30 gram phenol (or 44g Salicylicsacid) in a 1000ml bottle and add carefully add

45ml (80g)
konc. H2SO4 and stirr. Continue stirring fo a while.

2. Warm the solution i a hot water bath at 90-100C in two hours.


3. Create an icebath. Place the bottle there.
Add 120ml (+70ml H2S04) HN03 slowly and stirr alot.

4. Warm the solution at 90- 100C.
fo 90-120m.

5. Add 300 ml dest. water and cool it i a fridge.

6. Filter, wash, and purify.

Instead of 30g g phenol I added 44g salicylic acid.

When I heated it everything dissolved fine but at ca. 80 C something bad happened <img border="0" title="" alt="[Eek!]" src="eek.gif" />

Everything got solid and hard and wery hot, shit what happened?

Next time I used 90 ml of H2SO4. This time the almost clear liquid(H2S04 + SA) becamed muddy and like sirup. White crystals were visible (is this phenol?)
After 2 hours it was a white and red cream.

I added the HNO3 wery slowly and now it becamed a yellow syrup, very thick.

I also did an other batch but in this I added 70ml H2SO4 with the nitric acid.

When I heated the solutions everything dissolved and the color becamed redorange.
But then something happened that was not supposed to happen, at 80C the solution began bubbling (cooking?)a lot of red fumes (aka NO2) became visible, a really mess. I just heated the solutions at 50C (2hours) after that incident.

The result was that I got a good deal of TNP from the batch with an extra 70ml H2SO4 but almost nothing (only a white powder!) from the other batch.

Does this mean that Phenol cant be substitued with salicylic acid?
Anyone that has done a similar procedure but with pehol? Then what is different.
Any suggestions of a better method with salicyllic acid, this was damn hard and dangerous.

This is really frustrating shit! :mad:

[a_bab]

If you want a safer and easier method, use corn starch (flour works also) and gasoline. It packs the power of a stick of dynamite in about 200 grams.

Now seriously speaking, WTF do you expect ? To put two solutions togheder and presto---&gt;pure TNP ?!
Of course is not that simple. But neither dangerous if you are paying attention. If you want danger, stick to hidrazine distillation. Or to tetranitrometan. Methyl nitrate could be another option.
Is simple and safe IF you follow EXACTLY the CORRECT procedure. Now how can I get the correct procedure, I hear you. Well, by reading as much as possible and you'll end up by realising how incomplete are the recipes which are floating around.
If you'll read about the industrial manufacturation of TNP, you'll find out that the nitric acid is added gradually (and I mean GRADUALLY) to the phenol/H2SO4 mix. It takes several hours ! This simply means that you need to add the nitric acid not as slowly as glycerine in sulphonitric mix, but even slower. Otherwise you'll end up with lots of NO2 in your lungs and a black slurry instead of the TNP.
I don't know why, but for me the aspirin method works perfectly. With phenol I wasn't able to get more TNP than to stain my hands (not a single visible crystal :mad: ). I may try it again, though now that I know the correct procedure.

[kingspaz]

or invent your own procedure :) .....if it doesn't work then work out why using the tool of chemistry and try again!

[AfroFukinPyro]

Who uses a respirator or fume hood while making Picric acid? I'm not sure how neccisary it is, but I use a respirator for most things in my lab just in case.

[kingspaz]

i use a respirator when making TNP. its better to have one and not need one other than need one and not have one. its best to be prepared for an accident.

[Helos]

Now what the fuck do YOU want? a-bab You have an really bad and agressive attidude, I say: Put that away!

Did i sound like a kewl? Actually I worked this methode out myself used myself using the tools of chemistry.
I calcualted how much of different chemicals to use, and I also wrote critical about another report that I think used way to much nitric acid.
I also have read many different methods (as you had seen if

you had been more concentrated while reading my post, a-baba)

I ALSO actually added the nitric acid WERY slowly.

That was not my problem, my problems was that when I heated the solution AFTER adding

the nitric acid (read again) I had a run awayreaction with red posiounous gases.

This is not supposed to happen. My problem was that I used salicylic acid instead of phenol, and even thought I still cant understand why it certainly dont work just as fine as phenol should do!?

[a_bab]

Really agressive atitude ? Hm, this isn't going to be a flaming, BUT:
"Did i sound like a kewl ?"
Well, did I ever said that ?

I made TNP from salycilic acid and it works. I posted a method if I remember. Shortly, you only use salicilic acid and HNO3, in two phases: in the first one you'll get a yellow compound of I-don't-know-what, with evolution of CO2, compound which is tranformed in TNP with a second addition of HNO3. I have to search for the book where I got the method from. DON'T use sulphuric acid with saicilic acid; it won't work. All I got was a thick slurry of crystals, lot's of acids spent but no TNP.
And please spell my name corectly. Actually *try* to spell everything better <img border="0" title="" alt="[Wink]" src="wink.gif" />

[Helos]

As I have written before I tried that method (Pure HNO3 + SA)
It was a mess (aka bad RED reaction), I used 65% nitric acid, maybee pure means 100%HNO3? Can you explain this process more exactly?
What chemicals did you use a-bab?

As you mention it seems hard to use sulfuric and salicylic acid, but the methode I used (I wrote about this in a long message above)in fact gave me picric acid in the end, but the yeild was as low as 50% I think (havent calculated it exactly yet)
And as i have written before, I got a lot of problem even thought I did everything perfectly(?)

[Boob Raider]

Hey Vonk .... if I just go to the pharmacy and get a bottle of "oil of wintergreen" and on the ingredients it oil of wintergreen .... 99.9% is this the natural one ? would the synthetic methyl salicylate one say Methyl salicylate or Oil of wintergreen.
Oh and your PA is not drying and turning paper brown and slimy ... I think there can be 2 reasons. 1). your PA is not properly washed and still contains nitrating acid mix. 2). your product is not completely tri nitrated and probably contaminated with mono/di nitro phenols.

[nbk2000]

I was just reading the last page in PMJB5 (before the index) where it was described how oil of wintergreen can be made by adding sulphuric acid to a aspirin powder in methyl alcohol.

Seperation may be a bitch, or it may simply distill out, I don't know. Though this may make for an interesting purificating process as a prelude to making TNP.

[VX]

I just had a pretty pleasant surprise.

Yesterday I was in the lab all day at Uni synthesising random inorganic iron compounds. Whilst searching shelves trying to find the Chemicals needed my eye caught two big jars full of yellow powder, and yes.. They were labeled "Picric Acid"!!

Both jars were about 10cm in diameter and about 4 inches full with picric acid, (and about an inch of water on top of the crystals, I assume that they don't want it blowing up):D

I’m going to have to get a camera from somewhere and take some pictures of the labs and chemicals available.

Sorry for the randomness of this post, I just thought it was kinda cool to stumble across some of this stuff.

[Al Koholic]

I know that feeling...only I've found a jar of ACS reagent grade that was 3/4 full (about a 1/2 litre jar) and was merely covered by a loose piece of cellophane. There was also no water in it but that really isn't a problem as it won't just spontaneously detonate...

[webbsmurfen]

Originally posted by Marbles
I've just prepared some picric acid from aspirin and its drying now.I just want to get some idea of the power this has in comparison with AP for example.What expieriences do you guys have wi
th it?I plan on making some good strong detonaters with it and Ag2C2.

Marbeles: Instead of using AP when you detonate TNP, use sodium picrate instead. (You dont need a barrier between the explosives if you use SP)

Sodium picrate is quite simple to make...

sodium hydroxide + C6H2(NO2)3OH ---> C6H2(NO2)3ONa + H2O
Filter out the crystals... and let them dry

*Sorry but my english sux*

[Trinitrotoluene]

Does anyone know how to chemically destory picric acid?
Or to clean up the yellow stains created by picric acid that had stained wood and plastic?

[kingspaz]

webbsmurfen, from my experience sodium picrate does not detonate reliably.

i don't know anyway to chemically destroy it. i was under the impression that when it stains things that it is chemically bonded to whatever it stains. it may just be hydrogen bonded but i forget. if this was the case however then a wash with somthing that would form stronger hydrogen bonds with the stained material would likely remove the TNP.

or am i just talking shit :confused:

[yt2095]

only a hunch, but UV light may reduce it somewhat, i`ve used it with limited success on other organic dyes, if your in no rush, bright sunlight may fade it over time, or maybe faster if you have a UV EPROM erasure?

good luck :)

[ossassin]

When making picric acid, would it be possible to use methanol instead of ethanol? I have a huge bottle of the stuff.

[Dave Angel]

ossassin: do you mean for dissolving the ASA to separate it from the filler material? If yes then I think methanol should work but I haven't tried it as acetone does the job fine for me.

[Mumble]

Ossassin might be refering to the purification step. Thats the only place I've seen ethanol used before. A 2:1 Water to Ethanol ratio for recrystalising from. I suppose it could be used to dissolve the ASA, there are many other cheaper more efficient solvents. The ethanol water mix is referenced at Powerlabs. I guess it has a higher high temp solubility or a lower low temp solubility. Perhaps both.

[Dave Angel]

Oh I see, I tend to just use water and recrystallise another crop of crystals from the filtrate by boiling it down and cooling, and maybe some more after that. I'll have to try that solvent mix and see if I can improve my yields.

[ossassin]

This procedure uses aspirin tablets instead of phenol. Crush 100 aspirin tablets to a fine powder. Put 500 mL of 95% ethyl alcohol in a 1000-mL beaker then add the aspirin powder. Gently heat the alcohol while stirring to dissolve the acetylsalicylic acid within the tablets for 15 minutes. Acetylsalicylic acid is the active ingredient in aspirin and a phenol derivative. Filter the still hot alcohol to remove any excess tablet filler. Now heat the solution to evaporate off all of the alcohol, leaving behind crystals of acetylsalicylic acid. When the crystals have dried, add them to a 1000-mL beaker with 700 mL of 95-100% sulfuric acid. Heat the acid and stir to dissolve the acetylsalicylic crystals.

That's from Megalomania's site. It's the third method that uses the aspirin.

[Dave Angel]

Well in that case, acetone certainly works and methanol will probably do instead, as all you are doing is extracting the ASA from the filler materials. Just make sure you remove all the solvent afterwards and you'll have nice crystals of ASA to do the synthesis with.

I'd probably stick with water for the recrystallization though, if you haven't got much in the way of solvents to spare.

[atlas#11]

I am out of H2SO4 now but I plan to try picric some time this weekend and I got to thinking, would it be possible to add the xNO3 in a saturated water solution from a burret? The water may cause a problem when trying to crystalize out the tnp but I would think it would make the reaction a little less violent. But then their's the water + H2SO4 heat thing that may cause problems. But I am just a lazy guy who dosen't want to sit their for over an hour stiring a solution that is ozzing poisionus gasses. Just a thought. Has any one tried tnp shaped charges? Cast charges?

[Mumble]

A water solution will not work. In addition to heat generated by the Sulfuric, it will also lower the acid concentration. More than likely, lower it beyond an acceptable value. If you add the nitrate slow enough there is little if any NOx given off.

[atlas#11]

O.K. just wondering. How many people used boiled down batery reffil solution for this? That's all i can get so I need to know if there are any important impurities in it. Any ways I will try this on thursday and report the yeild to any one who cares. Last time I tried this with that shity black drain opener and it was going well untill I dumped it into the ice/water mix and it foamed up to make a huge(1 litre) mass of grey shit that I couldn't filter or any thing and I know there was some picric in it because my fingers turned bright yellow and there were brown crystals in it but I couldn't get at them. Oh well, live and learn.

[Dave Angel]

If it's refill solution then I shouldn't worry about it too much, unless it's made from recycled battery acid. If you use acid from an old battery you will likely have lead impurities which will form lead picrate.

I've used the drain cleaner acid before with no problems, I boil the acid before hand to concentrate it and destroy all that colouring, although mine is purple so may have different impurities.

How much of your mix is ice and how much is water? I usually use plenty of cracked ice and only a little water, and the volume of this mix is approximately double that of the reaction mix. It does foam a bit but I wait for the ice to melt, stirring in the foam and the TNP is there for filtering. It looks orange/pink for me before recrystallisation.

Remember that less substituted nitrophenol derivatives will also turn your flesh yellow. I considered working out a titration to determine the degree of nitration but any left over nitration acids would interfere in such an analysis unless you recrystallised a very pure sample.

[Skean Dhu]

I just made a small batch(~5g ASA) of TNP over the long weekend. I didn't heat up the ASA/H2SO4 mix while adding KNO3 and it didn't all dissolve, so now I am faced with the task of separating the TNP yeild from the undissolved KNO3.
Would (m)ethanol be able to dissolve the TNP while leaving the KNO3 as a solid( KNO3 being insoluable in alcohol) or would the TNP not dissolve in it either?
Also since not all of the KNO3 dissolved how likely is it that what ever TNP I did make was then converted into potassium picrate while I let it cool and then filtered it?
I'm not entirely sure how much this will affect your responses but I used
4.6g of ASA, ~100mL 93-98% H2SO4, ~15-20g KNO3,, yea I know it was kinda wasteful but after adding it to the correct acid ratio it didn't look like enough so I added some more,

::Edit:: spelling/ minor question.

how do you guys ignite/detonate your TNP, would it react with the K in Black powder. I don't plan on storing it but just cramming it into the straw of a X-mas light ignitor

[Dave Angel]

Skean, have you tried recrytallisation?

One way to do this is to dissolve your mix of TNP / KNO3 in a small amount of hot water and boil the solution down somewhat. When it cools, some TNP will crystallise out of solution and the KNO3 will mostly remain in solution, being more souble than the TNP in cold water. Filter to isolate your TNP crystals and wash them in the funnel with a little ice cold water.

Like I said before, I like to boil down the filtrate a little more and get a second crop of crystals. Cool fairly rapidly so that you don't let the crystals get too big, large crytals of explosives are more sensitive than small ones AFAIK.

Recrystallisation is a standard lab practice and it shouldn't be too difficult for you to find many references to it if this is of no help.

[Blackhawk]

It would be more interesting to see if any of the TNP comes out as Potassium Picrate. I'm not sure what TNP looks like but KPicrate looks like a lot of yellow needle crystals.

[Skean Dhu]

No, I haven't tried recrystalization yet, thats kinda what my post was about. I'm kinda nervous about heating a primary(it is a primary isn't it?) that I have to experince with no matter how small an amount it is.
I haven't really looked at it much, it was still filtering really slowly when i left it sunday afternoon. When i mixed it I took 25-30 min to add all of the KNO3, I didnt get any NOx just the usual whisps of HNO3 you get from fuming stuff(whew they clear your sinuses if you catch a whiff) the solution was a nice rust red color but then as I filtered it it changed to a nice yellow, the powder itself(as I left it) was a shade brighter than the sulfur I have. If any K picrate is formed I'll be sure to post about it .

well as my plan stands tonite, I'm gonna buy some ethanol tomorrow and see if that works the way I hope it does. Otherwise I'll have to depend on the solubility differences. Would cooling(freezer or just leave it outside for a few hours ) work rather than heating it?

[Blackhawk]

Yes I think the cooling should work, although KNO3 will also precipitate out as the temperature gets lower. The idea about recrystalisation is that seeing as TNP is less soluble than KNO3 if you bring the ammount of water down to just the ammount needed to disolve all the KNO3 then the TNP will crystalise out leaving very little behind as all the water is used by the KNO3. I don't think heating the water soloution of TNP could be a problem, although it would be better to get the opinion of someone that has done it before ;)

[grendel23]

Skean Dhu,
I have recrystallized TNP, Blackhawk is correct that the idea is to dissolve the TNP in the minimum amount of water that will hold it at boiling, then cool it to just above freezing and filter out the precipitate. You will find that there is also some crud that will not dissolve at all in the boiling water. Any KNO₃ should remain in solution as it is much more soluble in cold water.
Use 1000ml boiling water per 15g of crude TNP, stir to dissolve all that will, filter while hot, place container in freezer until contents reach almost freezing, then filter out the pure TNP. You could boil down the liquid and get another small amount when cooled, but it wouldn't be very much.
TNP is a secondary explosive, you need a primary to reliably detonate it.
Be careful with your TNP, it is quite toxic, can be absorbed through the skin, and is incompatible with metals.

[atlas#11]

Dave, I didn't think about boiling it but I don't think it would remove the coloring. The Ice water mix had less than 200ml of water and was in a 1 litre beaker(about half full), the ice was ground up to about 1/2" chuncks. I believe their is something else in that drain opener, a thickner or something cause it pours like warm maple syrup. That may make it foam up like that. Any way I will get some refill acid tomarrow if I can find any. But it will take a long debate to convince my parents to let me buy it.

[Dave Angel]

Well if you aren't sure then don't do it. Personally I would think that a primary salt dissolved in solution would be relatively less dangerous to heat, but the decision to do so is up to the individual experimenter to make based on what reliable informatation they can find.

Does anyone know if TNP reacts with KNO3 at all? I was under the impression that it must be reacted with the hydroxide of potassium (ie a base) to make potassium picrate. KNO3 is the salt of a strong acid and a stong base and as such is not likely to react with picric acid as much as table salt doesn't form sodium acetate when you add vinegar, AFAIK.

This is not to say 'yeah go ahead, there's no picrate salt in there', if in doubt, throw it out. You'll live, and you can make TNP again and convert it to potassium picrate if and when you want to, not when it decides to.

Hope you get hold of that acid and carry out a safe, successful synthesis.

[Bert]

Potassium picrate may be produced by reacting picric acid and Potassium carbonate in a hot aqueous solution and chilling to precipitate the product. It was used for old fashioned pyrotechnic whistles, mixed with Potassium nitrate in the ratios 63% picrate : 37% nitrate. If you try to use it straight, it blows up instead of whistling... It's not as nasty to handle as Lead or Copper picrates.

[Dr_Pind]

This might not fit under the TNP thread.
It was said earlier that benzoic acid couldn't be used to form TNP. I was wondering if it would be possible to nitrate it in a similar fashion like the TNP, to form Trinitro benzoic acid. I found several sources on the net, stating that it can be made by catalysed oxydation of TNT. This of course wouldn't be a good way since it uses TNT in it's manufacture. Would it be possible to sulphonate benzoic acid and nitrate it. Also Trinitro Benzoic acid is used in the manufacture of TNB(Tri Nitro Benzene) and in the manufacture of Lead Trinitro benzoate which is a promising primary explosive. Any ideas?

[Ollie Snowie]

Dr_Pind:-
I'm sure you mean toluene instead of TNT :).
I've heard that benzioc acid can be made by oxidising toluene with KMnO4.
The benzene ring in benzioc acid should be nitratable - I can't see why not.
In most nitrations a sulphonation takes place - e.g nitroclygerine. That's why many nitrations need sulphuric acid as opposed to any strong acid.
I don't quite get you on the rest of that post. You are asking if it would be possible and later saying that it is possible and that it is already used to make a promising primary explosive :confused: Or was that just speculation?

[Dr_Pind]

What i meant was that Trinitro-Benzoic Acid could be made by oxidation of TNT. Sorry for the misunderstanding. Obout the manufacture of Trinitro-Benzoic Acid. It IS possible to make it from TNT, but since it uses a good HE in it's manufacture, I don't see why anyone in this forum would find any interest in this synthesis. I don't know if it can be made by nitrating Bensoic Acid directly,havent been able to find any info on it anywhere on the net, but if it is possible to make it by nitration, i dont see why the TNT synthesis is used in the first place. The primary made from the Trinitro-Benzoic Acid and lead is described on Mega's homepage(it states that benzoic acid is used. This is not correct. It is Trinitro-Benzoic Acid).
About the sulfonating process. Does the compound being nitrated have sulfonate groups attached to all the places where the NO2 group are supposed to be? Also, when nitrated, the reaction produces H2SO4. Will this work as a water absorbant?

[kingspaz]

yes, sulphonation occurs first then electrophilic substitution of the sulphonate groups by NO2+ ions generated by H2SO4 and HNO3 mixed acid.

[atlas#11]

Tried it, with a small batch (18g nitrate,140ml SA, 20 asprin tab.) and I got this strange red/orange powder out of it after it was cooled to about 5-10*. I tried every methode of purification I could think of! When the addition of the nitrate started it went blood red and released HNO3 gass,(seemed normal), then when I dumped it in the ice it released a small puff of NOx and then shut up and for some reason it melted all the ice and was still about 40*(not enough ice?). After it cooled in a snow bank for about 30min. It formed some yellow brown crystals and so I filtered them through a coffe filter and brought them in and tried washing them with about 50ml of water and looked for color changes, nothing just deminished ammount. After attempted recrystilization and rinsing with various solvents I was left with this strange powder time and again. Could it have been oxidation? I have heard that oxidation is the culprit of many failed attempts at PA, and has similar results as what I got so I think it caused it. Any way i dumped it and will try again with a diffrent methode when ever it warms up outside enough for me to boil down some more of my Sa. bought like a gallon of it and I think it is over 40%! for 3 USD per quart I can get tons so it's no big deal if I fail time and again.

[Dave Angel]

You did add the nitrate in small amounts over a long period of time with plenty of stirring didn't you? Neglecting this is a possible cause of oxidation. The red/orange powder you recovered sounds a lot like what I get before recrystallisation.

There's always plenty of ice left after I have dumped my reaction mix into the slush which I leave to melt, and that gets it quite cool, plus I put it in the freezer for a while if the container will fit. 40C sounds quite high, it's possible you ought to have used more ice, but that's something you just have to learn to judge and comes with experience. Keep at it, it's a great synthesis once you have your method sorted.

[atlas#11]

hmm, I may have had some picric in their but even if I did it woulden't be more than a gram. Yes of course I added the nitrate slowly, took me about 45 min to add the 18g(not long enough?). At the moment my acid is boiling down so I will try another batch and tweak it a little. More ice and more reaction time and maby lower reaction temp? It hoovered around 75 when the nitrate was added but when I heated it to sulfate the asa I only allowed it to reach 65 for about 10-15 min. In your experience what is the best time and temp to allow for the sulfuric + asprin to react? I've heard it's as long as possible but would like to be sure. And the coloration I saw, was that normal?

[Dave Angel]

18g over 45 mins sounds fine, I was just checking, you'd be surprised what some people do.

To sulphonate the ASA, heat the mix to 80C and keep it there for good half hour or so. Addition of the nitrate does usually turn it a blood red colour so you're ok there. I'd maintain the temperature at 75-80C during the addition of the nitrate so long as it is well stirred, and maintain the temp for another 15-30 mins when the addition is finished before allowing it to cool and dumping into your ice/water.

Works for SWIM.

[atlas#11]

Alright! I will try that when ever this acid cools. Where do you get your acid? If it is nessicary to boil down your acid how exactly do you know when it is concentrated? when I boiled mine down it took about 3 hrs. and stoped boiling but kept relasing steam (at least that's what I thought it was). Last time when it stoped boiling I collected it and cooled it and it became about like cooking oil in viscosity. It was tinted slightly brown but I think that was because of some small shred of paper towl that had fallen in while it was hot. Yoi say your crude picric is about that color? I may have thrown out some picric acid! I did try to purify it without luck I'll try harder nextime and do a bigger batch(megas recipie?). BTW have you tried megas method? What is the yeild like?

[Dave Angel]

I either get my acid as 91% concentration drain cleaner or buy it through lab supplies when it's worth putting an order in. In a recent thread on nitrocellulose, Mr. Cool mentioned that an effective way to check if your H2SO4 is concentrated enough is to dip a little paper towel into it whilst it is at room temperature, and if it turns black in a second or so then it is.

I believe the method I came up with is a mix of procedures gathered from mega's site, Mr Cool's and Forum posts. You should probably stick to small batches until you sort your method out, as that way you can make them quickly. Believe me 3 hours of nitrate addition is really not that thrilling, despite how much I enjoy my chemistry.

Here's the method:

For every 1 gram of ASA, use 1.8g of KNO3, and 14mL of conc H2SO4. I usually use a bit more than what is calculated, probably 4-5% of the quantities depending on how it looks to me. This is a handy rough guide and can be used with 10g to 100g of ASA successfully, without having to bother with molar calculations.

Heat the H2SO4 to 80C and stir in the ASA, ensuring each scoop gets mixed in thorougly before adding the next to avoid caking. Maintain stirring and temperature for at least 30 mins. Solution goes a yellow/brown colour.

Maintaining the temperature at 80C, add the KNO3 gradually, in small amounts, allowing the reaction to subside before adding the next little bit [this is where you might wish you'd made a smaller batch]. Addition causes colour change to blood red.

After addition is complete, maintain heat and stirring for 15-30 mins and then allow to cool down to room temperature, preferably lower. Pour over your estimated amount of crushed ice / water slurry and crude TNP precipitates. For, example I used something like 4-5kg of slush for the 750mL of H2SO4 used once, but it's very much down to experience.

Allow the ice to melt and the mix to cool, and filter the product, [vacuum filtration is also a must for larger batches]. Wash the filtrate with a little ice cold water.

Recrystallise from boiling water, you may be able to get 2 or 3 crops as mentioned above.

[atlas#11]

I tried it again and this time when I heated the SA and ASA together I let it reach 80 and let it sit for 30 min and when I came back it was about 40 degrees and was a black solution with a little bit of ASA still floating around in it. Why doesen't it desolve? Any ways I now have a bunch of grey crystals that I will try to recrystalize and see what happens. BTW, what's up with the forum? There is this error message on the top of the screen about headers. I used your method with 10g ASA, 140 ml SA, and 18g nitrate.

[static_firefly]

Maybe its just me, but is anyone's nitration mix blood red before the addition of KNO3, and when you add the KNO3 the solution turns yellow? I have pics of before and after the KNO3 is added, and my TNP yeilds seem quite good (however i wasnt able to way the yeild because i had the batch drying in a coffee filter, and the residue H2SO4 ate through and my TNP fell on the ground).

[Bert]

I am wondering about the suitability of Sodium salycilate as a starting material in place of ASA. Any thoughts?

[atlas#11]

O.K. I recrystalized that stuff I got out of the black solution, it is a creamy yellow/grey crystaline mass that resembles wet fiber glass. It doesn't look like the picric I have seen in other pictures but I am going to hold on to it anyways and find out what it is. If it is picric then the yeild sucks only 2 grams from 10 asa. It doesn't burn and it smells like asa when melted(without the acetic acid fumes). I tried recrystalizing it a second time and filtered off a small ammount of brown crud and got the same mass of crystals but with a lighter color. I have heard that picric has needle like crystals but never like fiberglass, what is this stuff?

Bert, sodium salicilate sounds ok to me, when sulfating wouldn't it make NaSO4? If so then I don't think the picric acid would be strong enough to remove the sulfate ion so you shouldn't have to wory about sodium picrate forming to my knowledge. Don't hold me to it though, I'm not an all knowing chemist.

[Dave Angel]

atlas: Do you know if are there soluble impurities in your aspirin tablets that came through when you dissolved and filtered them to get your ASA? It sounds like something might be getting carbonized, just like the paper towel does in the test. Besides ASA, the tablets I use contain potato starch, lactose and talc.

I think I'll dream a synthesis soon so that I have some recent data to compare, and I'll take particular note of my colour changes.

Bert: I suspect the sodium salt of SA could be used but you would have to use a large excess of acid to acidify it to SA. If this wasn't done, one might end up with impurities like sodium picrate or more likely low yields as the acid one did use would be partially consumed in the acidification, as in atlas' reasoning. It might be possible to acidify it separately with, for example, HCl and isolate the SA from this, but I haven't looked into such a process in detail yet.

[atlas#11]

I didn't think of that, I did use acetone to purify it(it's cheaper and more abundant) that may be why. I'm going shopping today so next time i'll use ethanol and see if it makes a diffrence. The inactive ingredients are hypromellose, starch, and titanium dioxide. I'm guessing the hypromellose was dissolved in with it but i'd be willing to bet it won't disolve in ethanol. I don't remember if starch was soluble in acetone or not but it could be in their too. sounds reasonable but I will have to wait untill I get more ethanol before I can try it.

[Dave Angel]

Ah, hypromellose, also known as hydroxypropyl methylcellulose found in some contact lens cleaning solutions, maybe in (on) the tablets to give them a shiny, easy to swallow coating? I just so happen to have a large amount of old lens solution which I could evaporate down and then treat the residue with some conc H2SO4 to see if dehydration ---> carbonisation occurs, which I'm guessing will occur, as it is so similar to cellulose.

Being so soluble though, you might want switch to non-coated aspirin if indeed this is coating material. You should probably switch brands to one that does not contain the compound anyway as it may be rather difficult to remove no matter where in the tablet it is. The cheapest brands you can lay your hands on tend to contain fewer inert ingredients which is no bad thing.

[atlas#11]

Well that would be the easy way but as I like to kill all of my opponents in grand theft auto I will remove the impurities from my chemicals in any way possible. What color is your asa when purified? A long time ago I purified some asa from bayer or something and it came out slightly purple, so i'm guessing thats what it should look like. Any ways, if hypermellose is soluble in something that asa isnot then it would make things easier so I will search. BTW, when trying another batch I got completely diffrent results, instead of fiberglass I got orange crystals, I think i'll wait till I get pure asa before I try this again. Next time may bring wierder(or more dangerouse) results.

[Mumble]

100% pure ASA is pure white, to a slight tan. Because it's so white, the slightest impurity can really cause a noticeable difference.

[atlas#11]

That gets me to wondering what made that crap purple. Any ways it has been a blizzard all day here so I wasn't going to risk going to get more asa maby tomarow(I HATE WINTER), weather permiting, (When you live in the mountians it's not leaving thats a bitch, it's geting home that kills ya). In the future, coated = bad for picric, also, for the nitration of 10g asa is 12g NH4NO3 enough (Still working on my stoich, I know, I know.)?

Update: Got some uncoated asprin and purified, like an itiot I used 75% isopropanol and am still waiting for it to dry. I have concluded that the purple imputities in my asa are due to oxidation as heat was the only variable in both purification attempts. On a lighter note, I got some glycerine so i can now make some NG. For some reason NG and picric go toghether, maby because picric's precursor is a purified headache medication and NG causes tremendous headaches. I won't be making that until i've got a fume hood or noish approved self contained breathing apparatus, (not a big fan of headaches.)

[Skean Dhu]

Has anyone here experimented with APPA(acetone peroxide/picric acid) I was roaming around megas chem lab site and in the AP synth page it said adding AP to some TNP would increase the stability of the AP.

Swim had planned to do some test to find a mix that was Fuse sensative but when he went to take the PA out of the filter papers it had been sitting in for a couple weeks he discovered the paper had all but disintegrated. So right now Swims TNP is drying out and has 6 or so slightly nitrated/picrated coffee filters worth of paper sitting in it. Swim being too lazy to filter out the paper, besides it'll probably just act like microbeads.

anywho, Swim and I were wondering if anyone had already done this or experiments similar.

[Dave Angel]

I've just dreamt of a TNP synthesis.

20g of cheap aspirin ASA was used along with 300mL 97% technical H2SO4 and 40g garden supply KNO3.

Acid heated to 80C and stirred, ASA added and the solution gradually became a bright yellow colour. It was left for 30 mins and the yellow became a little richer. Addition of KNO3 commenced which took in total 90 mins.

The KNO3 could be added relatively rapidly at first but as the nitrate concentration increased and the reaction became more vigorous (ongoing foaming) rate of addition was slowed down.

Addition of a little nitrate deepens the yellow greatly which, with a little more, changes to a golden syrup like colour. As addition continues the colour becomes warm orange and then red. After an hour the mixture is foaming and by the time addition is complete there's quite a bit of foam in the stirring vortex. After addition, I increased the rate of stirring and maintained this for 30 mins.

Cooled to 25C whilst stirring, then poured over 700 - 800g of minced ice (no water used this time). Allowed ice to melt and put in freezer to take temp down to -10C. Filtered by suction to obtain the crude TNP which was a pink/orange colour. Recrystallised from boiling water to give the bright yellow TNP crystals. Worthy of note is that the initial recrystallisation gave a rather murky green solution, which was boiled down after it's crystals had been isolated, at which point it became the more familiar rich yellow colour. This has occured before and the product has turned out just fine. I wonder, have other members made similar observations?

Yield unknown as some saturated TNP solution from a previous synthesis was added to the filtrates and multiple crops of crystals produced by boiling the mix down and recrystallising.

atlas,

80g of NH4NO3 will provide the same amount of nitrate ions as 101g of KNO3 so just multiply however much KNO3 you would use by 0.8 and that should be fine.

With all this TNP lying around SWIM might investigate some mixtures involving it such as those in the Lyddite thread.

[Edit] I've just done a little search and Rosco Bodine has used ammonium nitrate to make TNP before and found the yield to be poor. I'd use the sodium/potassium nitrates instead unless ammonium nitrate is all you can lay your hands on.

[atlas#11]

I ran out of KNO3 so I was using ammonium nitrate but I will order some more, I haven't really looked but it may be avalible in some home improvement stores or something but I'd wrather not use it for nitrations(I would wrather use lab grade). Any ways, It seems I am also out of sulphuric, Damn! I do have one quart of un concentrated stuff but it will only do two batches so I will be buying more of that as well. Don't you just love shopping when it comes to chems?

My last batch came out same as before only slightly reder and I used a diffrent asprin and everything. Jeez, I'm out of ethanol too! And I can't even go shopping till next week, this sucks! I guess I'll just wait till then any way. I think I will look for a beter source of sulphuric as this one is kind of pricy, but it is easy to get and the guy who sells it has shit for brains so I can walk in and get gallons of it without anybody the wiser. I love this town.

[Roy Paci]

I have few simple questions:

-What is the amount of NOx I shall expect from the nitration o ASA via AN? Can I carry this with no vented hood or a poor one? :confused:

-Is the intermediate solution obtained adding AN likely to esplode suddelny? :(

Thanks

[atlas#11]

If you go slow their should be very little if any. Mine never produced any, except when it was poured in the ice and that was probably from the hydration of the SA. Ofcourse I have not successfully made any yet so I don't know how relyable this is. Today is my offical sulfuric acid boiling down time so I may try again tomarrow. I don't suggest doing this without a good fume hood or outside. It may not make NOx but it does make HNO3 fumes which are just as bad in high concentrations. You can heat the sulfonation mix indoors as long as you don't over heat it. Good luck.

[pdb]

I am trying to make detonators that wouldn't need compression of the HE load by choosing cast picric acid associated with another layer of slightly compressed PETN (plus a primary as third layer).

Cast picric acid being quite insensitive, does anyone have an idea of the amount of PETN required to initiate it ? If it is over 0.5g, there will not be enough space in the detonator case...

[Boomer]

I would not put a nitro-ester in direct contact with picric ACID (for that very reason). Why not use only PETN plus a primary? It can be safely pressed.

[pdb]

I am aware that a better choice would be TNT iso PA, since it has no acidity and a lower melting temperature. But I don't think it's a problem to keep dry PETN & PA in contact for a period of one year or so (I destroy my detonators beyond this limit).

So far, I have most of the time used PETN as main load, but compression has always been a problem because of lack of appropriate equipment to get a reliable and reproductible result. This is why I would like to explore another way.

[kingspaz]

pdb, i am interested as to why you think it is safe to store an explosive which undergoes spontaneous decomposition under acidic conditions with picric acid. could you please explain your thinking?

[pdb]

The world of chemical incompatibilities is not binary, and there are degrees between the do's and don'ts. I mean I will never for example use a mercury salt primary in an aluminium case, or a picrate in a copper one, or mix a chlorate with a sulfate etc... On the other hand, I don't think that dry PETN powder slightly pressed against a surface of cast picric acid will be such a hazard in the conditions of storage I mentionned previously, and it could even become worthwhile if it prevents me from the necessity of pressing hard some PETN in conventional detonators with a bad equipment, which I think is definitively a hazard. If you wish, it's an assessement of which of the two solutions is the least bad... Is it more clear ?

[Blackhawk]

But surely a paper cap pressed between the cast TNP and the PETN would stop them touching and reduce the chances of problems without badly effecting the detonation of the cap?

[pdb]

Yes, of a layer of appropriate varnish on the PA surface... But I fear this discussion is useless, as further information (melinite use during WWI)makes me think that much more than 0,2g PETN would be required to initiate cast PA.

[Bert]

I have looked at a number of purification methods for Picric acid both here and on other sites, as well as in COPAE.

Could someone with practical experience suggest their favorite regime for purification, and give solvent per gram ratios, temperatures, etc. I am particularly interested in methods OTHER than re-crystallization from boiling water... The amounts of water required (15g/liter) and boiling time seem prohibitive for more than a few grams.

Any and all suggestions are welcome, I'd particularly like to here purification methods compared by those who have tried multiple methods.

[Mendeleev]

I was curious, just how toxic is nirogen dioxide gas? The MSDS says its lethal, my chemistry teacher says its only lethal in very large doses, megalomania's site says it lethal in small doses, and members on this forum have claimed to have smelled it; so I was confused as to how I should treat it. I almost never get any, because I do the nitrations outside and sit with the fumes blowing downwind, but I was still wondering how toxic the gas is.

[Boomer]

I would say it is so irritating that you will have to leave the room before it does much harm. I got several good whiffs as I do most nitrations inside (=hidden from view), but never suffered any damage. :)

Someone said you get used to the smell at low concs and that makes you inhale too much, but that is hard to believe: It should form acid in your throat and lungs, how can that go unnoticed until too late? :confused:

[Sonny Jim]

It can induce a condition called pulmanory oedemia, which can cause death in a couple of days. Apparently, for a while after exposure, you can seem fine then become ill all of a sudden.

I would imagine the delayed effect could be due to:

NO2 (the gas) + H2O (in your lungs) --> HNO3 :(

Nitric acid on the chest isn't too appealing a prospect.

[Bert]

I was curious, just how toxic is nirogen dioxide gas?

Odour Threshold:
0.75 to 2.5 mg/m3 (detection) (2)



Warning Properties:
NOT RELIABLE - odor threshold about the same magnitude as TLV. Irritation reported at 155 mg/m3 (30 times greater than TLV).(2)

If you can smell it, you likely are over the threshold. If you can FEEL the effects, you are probably screwed allready.

I "smelled" some once. I had removed something from the hood, thinking it was done off gassing. It wasn't. I bent over it, and got a good whiff. My nose and airway burned, I jerked back and left quickly. About a day and a half later, I developed slight wheezing and fluid in the lungs. I didn't need medical O2, diuretics, hospitalization & etc., but it sure got my attention.
Nitrogen Oxide Toxicity (http://www.emedicine.com/emerg/byname/toxicity-nitrous-dioxide.htm)

[Mendeleev]

Thanks for all the info guys, I dreamt I made some more picric acid today, I sat up wind and so did not breath in any NO2, but this time after filtering it is a bit more of a powder than a larger crystalline form, although it is still drying off. Also, after I dumped it in water it looked like a really concentrated solution of yellow piss, which it normally is not. It also smelled very strongly of vinegar, which it normally does not. I used Aleng Gosvig's procedure with 250 tablets, 325 mg asa each, 440-450 mL of sulfuric acid, it was liquid fire brand drain cleaner, and 155 grams of green light stump remover, which is 98% KNO3. Perhaps it was the drain cleaner, which is black and thus has impurities in it. I haven't purified it yet in boiling water yet, but I'm pretty sure this nitration was as successful as the previous ones as it stains my hands yellow, but I am curious about the discrepancies from previous syntheses.

[Xioa]

Mendeleev, I think that maybe part of your picric acid is still aspirin, since the 500g of ASA I purified months ago smells strongly of vinegar. The picric acid I just made, does not. However, I just made it yesterday, and it's still wet, so I could be wrong, but I'm pretty sure that picric acid smells bitter. I believe this incomplete nitration could come from your H2SO4. In the past, I've had some really bad results from that stuff :( Try concentrating it next time...

[Mendeleev]

I'm pretty sure the nitration was fine, as I did boil down the drain cleaner until massive white plumes of SO3 were emmitted, I also purified the asa in denatured ethanol. The stuff is almost dry now, and I think I just have some impurities in it, which I will get rid of today by dissolving it in boiling water.

[lysias1]

A.VOGEL, in his book "practical organ[c chemistry"describes it.

[2,4,6-TNP]

Hello all,

Here is how I have always made my picric acid:

Materials:

50 grams of aspirin
350 milliliters of 99% isopropyl or Denatured Alcohol
350 grams of 92% sulfuric acid drain cleaner
115 grams of potassium nitrate or 95 grams of sodium nitrate

Procedure:

Place 50 grams acetasalicylic acid equivalent of aspirin into a blender,turn it on and blend the aspirin to powder and then add 350 milliliters of hot alcohol and blend for 2 minutes.
Now filter the solution and heat the alcohol in a sauce pan until there is no more alcohol left.
Scrape up the acetasalicylic acid and weigh it( should have 50 grams).
Now into a clean flask place 350 grams of sulfuric acid.
Useing an ice/salt bath, cool the acid to 0 Celsius.
Then slowly add 115 grams of potassium nitrate or 95 grams of sodium nitrate over a period of about 1 hour, while rapidly stirring and maintaining its temperature below 5 Celsius.
After the addition of the sodium or potassium nitrate, slowly add the dry recrystalized acetasalicylic acid over a period of about 1 hour while rapidly stirring and keeping the temperature below 5 Celsius.
After adding the aspirin, heat this mixture in an oil bath at 60 Celsius for 2 hours while rapidly stirring.
After 2 hours, remove heat source, and allow the reaction mixture to cool to room temperature.
Then gradually add the mixture to to 1500 milliliters of ice water, and allow the entire mixture to stand for 3 hours.
Now filter off the precipitated Picric Acid, and wash with 10, 250-milliliter portions of ice cold water.
Then vacuum dry or air dry the product.

Note: Do not wash with a base as the corresponding picrate will form.

The yield for this procedure is 60 grams of relatively pure Picric Acid.
it can be purified further by recrystalization from distilled water.

This is the only procedure I have ever used to make 2,4,6-trinitrophenol. The amount of NO3 gas given off during this procedure is entirely based on the reaction mixtures temperature; if you keep it hovering at 60 celsius and no more during the entire reaction you will not get any that is visible. If it is overheated large volumes of red gas will be released and you will get a poor yield.

I have enjoyed this procedure and have found that it can be done in the kitchen with the windows open and you'll need a gas mask during the first 20 minutes of heating the mixture. I always scrape the picric acid off the coffee filters and let it dry on plastic trays. If it is left on the filters, the filters will be charred black and contaminate the picric acid.

I have found if I add the picric acid to a pyrex bowl and put it in the oven at 123 Celsius and let it melt then take it out and allow it to cool, then crush it up again the crystals will be much larger and as rosco bodine would say "gritty".

Note: just like the other synthesis' of PA using aspirin, this mixture will bubble up and threaten to overflow if the reaction beaker is too small. For this procedure the reaction container should be at least 2000 mL capacity to avoid overflow. I use a plastic spoon to stir the mixture.

[Rosco Bodine]

It would probably be more accurate for the first sentence to read :

This is how someone who has never made picric acid may speculate
it should be made , before actually trying it and discovering that
in reality it doesn't quite work that way .

[2,4,6-TNP]

Rosco,

What on earth do you mean? I don't understand your last post!

What doesn't work?

I may not know shit about your lead azide and clathrates, but I have been making picric acid by this method for years now. I have detonated it with acetone peroxide and mercury fulminate.

I think you should try this procedure and then you can critisize me only afterwords.

The only thing that doesn't make since to me hear, is why anyone would want to add a nitrate to a already hot sulfuric acid solution anyway!

Just try it, I dare you! I have always had to do it on a weekend, cause as you can see it is pretty much a 7 1/2 hour deal.

[Rosco Bodine]

Where to begin ?

The proportions you have described are almost identical to what
I already posted in the archive thread , which I have never seen
posted anywhere before , and were from my own experiments
determined over years of experiments and reported from old
notes kept in my lab notebook . It seemed hugely coincidental
that you would independently arrive at almost the exact same
proportions as optimal . I suppose imitation is the sincerest form
of flattery .

Anyway , there are differences otherwise in the two methods .
Sulfonation is a step you either omit all together or you failed
to describe it . Directly nitrating an unsulfonated phenolic
material will lead to oxidation losses and unwanted by products
and also to the production of excess nitric oxides . I never got
as good a yield working at the lower temperatures you describe ,
even when sulfonating before the nitration . Yet you report
a yield identical to what I reported , even using much greater
amounts of water during your product isolation . This does not
square at all with results from my own experiments . Neither
does your identification of the time during which the fumes
appear to increase square with my observation and I do make
careful notes . Always , without exception it has been towards
the end of my nitrations when fumes appear , not during the
first two hours . Maybe because your order of addition is reversed
then the appearance of fumes is also reversed , I don't know .
Perhaps there is a simultaneous sulfonation / nitration occurring
for you . Are you sure you have transcribed your notes accurately ?

[Mr Cool]

I've never tried nitrating ASA unsulphonated, but remember it does have that carboxylic acid group which I would imagine will make it less prone to oxidation than other phenols... IIRC it's more deactivating than a nitro.

[Rosco Bodine]

From every literature source I have read , and in agreement
with my own experience , the best yields of picric acid are
obtained by a very gradual nitration where the first nitro
group is introduced , and then the second , and finally the
third , in a very deliberate process where the temperature
is increasing for each stage of the nitration .

It would seem that having the precursors for all of the nitric
acid to be required for the nitration , present all at once from
the beginning , would result in a more dangerous nitration mixture
where excess oxidizer is present in the early stages of the
nitration process , which would be producing picric acid directly
from the start due to the large excess of the nitration mixture .
And due to the fact the phenolic material is not sulfonated ,
there is a propensity for runaway at any time , which would
necessarily make such an alternate route undesirable from
a safety standpoint .

[2,4,6-TNP]

You think I have just read some posts and came up with this procedure?

Well you're way wrong.

I got this procedure EXACTLY as it is from The prepratory Manual of Explosives, written by Jared Ledgard, an organic chemist. One chapter and the table of contents can be previewed and the book can be purchased at this site: www.uvkchem.com Along with a manual on preparing chemical warefare agents and narcotics. The chemical ratio's seem so optimum, because they are! In the manual it also gives a procedure for preparing Picric Acid from 94 grams of Phenol, 42 grams of sodium hydroxide, 86 grams of sodium nitrite, 800 milliliters of 26% nitric acid, and 250 milliliters of 90% fuming nitric acid. The only variations I have listed in the above procedure is using Isopropyl alcohol instead of 350 milliliters of 95% ethyl alcohol. I also listed the use of Drain cleaner instead of 98% sulfuric acid, and in the books procedure the author say to use a clean flask, equipted with thermometor, motorized stirrer, and powder funnel. Also during the heating process the powder funnel is to be replaced with a condensor and refluxed for 2 hours at 60 Celsius. The only reason I have altered the procedure is cause I don't have all the chemical specifications and equiptment listed. The Picric acid is a very fluffy crystal heap in the filter after washing. I hope you will look at the preview on the site of the table of contents so you can get a grasp for the broadness of the preparation manual. It's unfortunate that he doesn't give a preview for the chapter that the picric acid synthesis is in, but the chapter you can preview is chapter 11, the chapter on preparing nitrobenzenes, including TNT, 1,3,5-triflouro-2,4,6-trinitrobenzene, trichlorotrinitrobenzene, picryl chloride, and trinitro benzylchloride.

I don't want you to think that I make up anything I say, and I don't try to steal other people's work and say it is mine. I have not made up any of the synthesis I have ever given in my post's, but they are all from various accurate preparation manuals. This chemist that wrote the manual obviously knows allot more about preparing explosives than about their practicle use.

Note: You can view the table of contents on the site by clicking on the buy/get more info link.

I would also like to note that when I followed the procedure as is from the book I had no problem and everything went as described. However I once tried to scale everything up, using two pounds of aspirin and the coresponding amount of acid and nitrate. It was done out in the woods and I didn't use a thermometor and I used a wooden spoon to stir(bad mistake). It went well until I added the aspirin, whereupon like you say there was a violent runaway reaction, but no detonation. The whole contents smoked, burst into flames and deflagerated. I think that any attemp to use the above procedure to scale things up should be done very slowly over a period of several hours or even days and an acetone/dry ice bath would be required to control the temperature. I have found the most I can scale up this procedure and still maintain good results is using no more than 95 grams of aspirin. I have been satisfied with these smaller scale preparations. I will also look into other possible procedures in the future, but like I said this is the only one I have used to prepare the picric acid.

[Rosco Bodine]

Now that you have told me from what source that "recipe" came ,
it helps to explain a whole lot of things . That is the same book
which recommended using dextrose with lead azide , and that
was about as good a quality of information . The author must
have gotten his chemistry degree from a cracker jack box , or
as a reward for giving blow jobs to his college professor . He
sure as hell didn't learn anything in a lab .

You really should be careful about the information supplied by
that "manual" , be very cautious , because the author evidently
doesn't know shit about his subject .

Buying such a "manual" isn't on my list of potential purchases ,
that much I can assure you .

And really , you would do better to study chemistry yourself
and come up with your own carefully thought out methods ,
than to trust information from sources like the one you have
been entrusting with your safety . That manual sounds like
another one of the classical "crap books" .

[2,4,6-TNP]

Dear Rosco,

It has been my desire to find an Explosives preparation manual that is completly accurate in as far as every synthesis works as written. I have a desire to own such a book, full of every explosive synthesis you can think of and all from extremely reliable, perhaps military based sources. That is why I purchased this book, and I am not saying that it is all that. Purhaps you can give me the titles of a few books that contain such information as I seek. I want a book that gives me accurate and in depth knowledge about each explosive, their preparations and applications; So I don't have to float around on the internet wondering if the "recipes" I see are just going to get me killed. Do you know of such an anthology that could be bought?

With respect,
The Bottle Breaker

P.S. This picric acid procedure worked for me!
P.P.S. What I'm saying is if you're going to tell me that the book I have spent my time and money on is dangerous and bunk at best, you should at least have the curtousy to recommend an alternative title.

[Rosco Bodine]

PATR , Federoff , 10 volumes .
The entries provide references to journals and patents .

Urbanski

COPAE , Chemistry of Powder and Explosives

Really I don't know of any one single "manual" .

Explosives technology is an engineering field covering
vast amounts of information . I understand what it is
you are requesting in the way of a basic manual ,
but so far as I know it doesn't exist , and its absence
is one of the reasons for this forum .

[Mendeleev]

In my opinion, learned journals are the best source of explosives syntheses, but these are usually a bit more advanced, requiring good equipment and chemicals, which would require either a well equiped lab or a solid investment into your home lab of at least 2 grand. Some of the journals I'd recommend would be, the Journal of Organic Chemistry (one of the few which allows free article downloads, just search for it on google); Propellants, Explovies, and Pyrotechnics; the Journal of Heterocyclic Chemistry; Mendeleev Communications (The recent articles are free, within about 4-5 years but the older ones require a subscription), and patents. Here is a link http://www.organicworldwide.net/journals.html . For cheap easy explosives like nitroglycerine, TNT, etc. which are basically sulfuric + nitric + hydrocarbon= explosive, I would recommend mega's site, and also NBK's pdf file, which is quite mind-altering. Back on topic, I recently synthesized another batch of picric acid, it is more brown this time because I used a different drain cleaner, but usually the impurities come out during recrystallization.

[Mr Cool]

I'm part way through a batch myself, using a method slightly modified from Vogel 3rd edition. The difference being that it's scaled up to 25g of phenol, and I'm therefore adding the nitric acid in three stages (30mL, 30mL, 40mL) because last time I used the exact procedure but scaled up proportions and it got quite vigorous... I'll do a write up when it's done. So far I've added 30mL of nitric and am waiting for it to cool...

This is how it's gone so far:

25g of phenol was sulphonated with 35mL of sulphuric acid (91%) in a 1L RBF in a boiling water bath for 30 minutes, while 100mL of nitric acid (69%) was cooled to -10*C. The phenolsulphonic acid was removed and cooled in the freezer to the same temperature. 30mL of nitric acid was poured onto the phenolsulphonic acid, and it was swirled for 2 minutes to partially mix the solutions. Approx. 3 minutes later, a very vigorous reaction took place, lasting around 10 seconds, perhaps a little less.
The reaction was then cooled to room temperature, and then to -5*C in the freezer, and another 30mL of cold nitric acid was added, and mixed in thoroughly by swirling. After 15 minutes, no visible reaction had taken place and the mixture was approaching room temperature. A warm water bath was used to initiate the reaction, but was removed once it had started. This time it was less vigorous, and lasted around 45 seconds.

I am going to let the mixture cool to room temperature, and then add the remaining 40mL of nitric acid...

[Rosco Bodine]

When you are introducing the third nitro group , it can help to let
the temperature rise steadily into the range of 120-125 Centigrade
at the end of the nitration , with good stirring provided
and carefully controlled heating if needed . You can do this using
a stirrer hotplate . It is somewhat nerve wracking to
bring the temperature up like that and hold it there for
three or four minutes , but the quality of the product and
the yield will be improved by a few per cent . The
temperature is high enough that the impure picric acid
which has precipitated during the final nitration will melt
and exclude the impurities as it recrystallizes almost
immediately in the spent nitration mixture . There is a
patent mentioned in the other archive thread where I
found the method first described . *If* you have the equipment
to maintain the stirring and temperature control required ,
it is a good way of finishing a batch to provide an improved
purity of product directly from the nitration .

Edit : I grabbed the patent list from the other thread and am
pasting a copy here for reference .

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 .

[Mr Cool]

The concept of melting an explosive in concentrated acid doesn't fill me with enthusiasm. Anyway, I lack a thermometer (temps were guessed based on the temp of my freezer!), never mind a stirrer hotplate, so I don't think it would be wise for me to do so :D.
I'll just recrystalise, I think ;).

Incidentally, I looked at that patent you mentioned in the TATNB thread, about DNDCB, and it seems like a good addition for TNP. You can get mp's down to ~50*C, at approx. 50/50 w/w. Would be great for AN mixes too... I'll have to make myself a batch!

[Rosco Bodine]

Not for the fainthearted ,
those fanny puckering manipulations having potential ! :D

Hey , I'll lose a few per cent and recrystallize from water ! ;)

I mean who needs perfection , anyway ? :cool:

Think TNT ......plus about 40 degrees more , of course .

I have done it one time , and I considered using binoculars
to read the thermometer , and using a long extension cord
for extending the circuit loop to the heating element in
the stirrer hotplate , which I could use to "unplug" the heating
element when the target temperature was reached :D

But then I thought , hey I'm an old man and I have good
accidental death coverage .....so what the hell , I'll go for it :D

It worked fine . I do have a solid state thermistor controlled
stirrer hotplate , which makes the heat closely controllable ,
and braces my courage for such a process .

[Mr Cool]

And was the emotional trauma worth it for those few per cent? :p

Anyway, I added the last of the acid, all at room temperature, no initial reaction, after a minute or two on a boiling water bath it once again emitted quite a lot of that red gas we all love to hate, and so I took it off the water bath and out of my kitchen, back into the lab to let it calm down. When I went back it had set solid, although it was broken up into a mush with a bit of swirling.
It's now back on the water bath, behaving nicely. 25 more minutes to go...

And because I was bored and have a new digi cam, I took a pic :). Now if only I can get it from my camera onto the computer...

Edit: Here (http://www.boomspeed.com/mrcool/Picric.jpg) it is!

[Mendeleev]

As I predicted, recrystallizing got the impurities out, and I now have beautiful fluffy yellow crystals. Mr. Cool, is there a way to attach images without having your own website, because I have so far not been able to.

[Mr Cool]

Yes there is. Beneath the reply box there is a button to let you do it - "Manage Attachments."
There are, however, file size and type restrictions; you may not be able to attach your picture if it does not fit within these.
I'm not sure if you can do it in "Quick Reply," I never use that.

Just waiting for my first crop to dry...

[Mr Cool]

The yield of the first crop from recrystalisation from water was 47g, 77%, 1.88g of TNP per 1g of phenol.
The yield of the original method in Vogel was 16g of TNP from 10g of phenol, or 66%.
But perhaps I got a better result because any loses on filter papers etc represent a smaller percentage when working with a larger batch size.
Still, not too bad.
COPAE has a method in which phenol is sulphonated, then diluted with 75% sulphuric (IIRC), and then nitric is dripped into this, followed by heating on a water bath.
I intend to try a sort of hybrid of the two methods - sulphonate phenol, chill it, and then add a 70% nitric acid/75% sulphuric acid mixture, followed by heating on a water bath. This should hopefully reduce oxidation and NOx production, while still avoiding the necessity of me standing there dripping in nitric acid while it's billowing NOx all over the place... that's the reason I like the Vogel method - you can just add the acid and forget about it until the reaction is over!
Something I have noticed is that the Vogel method uses a 92% excess of nitric acid, while one patent I have read states that only a 3-7% excess is required...

[Rosco Bodine]

Twenty per cent excess of theory for the nitric should be plenty .

The optimum excess will depend upon the amount of sulfuric acid
and water present in the spent acid , and the temperature and
holding time which was used in the introduction of the third nitro
group .

[al93535]

This was my third try at Picric acid, my first two failures were attributed to not heating during nitrate addition. Here is what I did:
10 Grams acetylsalicylic acid 7.5 grams unpurified, 2.5 grams purified
18 grams KNO3
150 ml H2SO4
heat H2SO4 to 80 degrees
Add ASA and let it dissolve, wait 30 min while at 80 degrees
Add 10 ml of 70% Nitric acid, reaction begins
maintaining 80 degrees I added 18 grams KNO3 slowly (over 20 minutes)
Maintain stirring for 30 minutes and a temp of about 90
Let cool to room temperature (mixture was very fluid)
add to 300 ml ice water with instant precipitation
filter, and wash with 100 ml ice cold water
add crystals to boiling water, and filter
recrystalize from boiling water yielded nice lovely yellow crystals
Final dry yield is 8.7471 grams
I did get a nasty scum floating on top of the water, which I attribute to the filler in the asprin, which was filtered off. I used all but 2.5 grams of my purified ASA in previous attempts, so just added asprin this time. Next time I will purify my ASA, and make a 30-40 gram batch. I just love it when a synthesis finally works!
EDIT: After my picric dried completely, it seemed to lose its yellow tint, and turned more white. Anyone else have that happen?

[Mendeleev]

Yeah, mine also turns slightly white. It is more of a pale yellow, but I can see tinges of white here and there, only noticable up close. Your temperature seemed a little high, I usually keep mine between 55 and 70, usually aroung 65, however looks like your synthesis worked so no problems. What exactly are those picture requirements attachment requirements, the size and memory?

[Bert]

What exactly are those picture requirements attachment requirements, the size and memory?
Keep them under 500X500 pixels, total size below 78.1 KB

[Mr Cool]

Apparently the trinitrophenol structure is colourless. The colour comes from two resonance forms which are present in minute quantities in equilibrium. These resonance forms are more dominant in picrate salts, hence these tend to be yellower, and more sensitive. The same is true for NM - colourless normally, but in basic solution it is converted to its "enol" form (not actually an enol...), which is generally yellow, and more sensitive.
Water (or other polar solvents, I suppose), helps to stabilise the resonance forms, so they are present in greater quantities in wet TNP, so wet TNP is bright yellow.
TNP dissolved in a non-polar solvent is colourless, and almost colourless if recrystalised from dil. HCl - just as bases produce more of the resonance forms, acids produce less (after it has dried out)...

[Bert]

TNP dissolved in a non-polar solvent is colourless, and almost colourless if recrystalised from dil. HCl - just as bases produce more of the resonance forms, acids produce less (after it has dried out)...

What was your procedure for recrystalizing from HCl?