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Topic: Picric acid
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ALENGOSVIG1
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posted March 04, 2002 11:57 AM
Yep i just did the normal sulphuric acid/kno3 method. Below is the method i wrote upPicric 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.
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DBSP
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posted March 04, 2002 09:01 PM
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.
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DBSP
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posted March 06, 2002 09:00 AM
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?
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Yi
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posted March 06, 2002 09:04 AM
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.
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Mr Cool
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posted March 06, 2002 09:18 AM
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.
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"Nothing makes a man fear much, more than to know little." - Francis Bacon.
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DBSP
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posted March 06, 2002 09:23 AM
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.
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Madog555
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posted March 07, 2002 02:10 PM
you want to let the asprin "cook" with the H2SO4 for like 15 minutes to convert it to phenol. then you should nitrate it.
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DBSP
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posted March 07, 2002 06:43 PM
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.
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Alchemist
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posted March 08, 2002 11:06 AM
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 ]
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Yikes
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posted March 09, 2002 11:58 PM
What about recrystallisation from acetone or ether? That woud get you nice, clean crystals of PA.
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Madog555
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posted March 10, 2002 01:18 AM
here is the properties of PA from MerckProperties: 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.
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DBSP
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posted March 10, 2002 03:00 AM
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?
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Madog555
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posted March 10, 2002 06:06 AM
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.
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Most people outgrow their pyro tendencies, we are the ones whose tendencies outgrew us.
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VX
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posted March 14, 2002 03:18 PM
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 ![[Roll Eyes]](rolleyes.gif) .
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]](mad.gif) . 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
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DBSP
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posted March 14, 2002 03:32 PM
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 ![[Wink]](wink.gif)
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VX
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posted March 14, 2002 03:41 PM
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'
[ March 14, 2002, 04:54 PM: Message edited by: VX ]
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Mr Cool
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posted March 14, 2002 05:07 PM
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.
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VX
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posted March 15, 2002 04:03 AM
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!
[ March 15, 2002, 04:06 AM: Message edited by: VX ]
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DBSP
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posted March 15, 2002 06:57 AM
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.
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Mr Cool
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posted March 15, 2002 01:58 PM
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.
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"Nothing makes a man fear much, more than to know little." - Francis Bacon.
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vonK
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posted March 17, 2002 03:15 AM
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
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stanfield
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posted March 17, 2002 03:44 AM
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 !
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VasiaPupkin
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posted March 17, 2002 05:37 AM
Acetylsalicylic acid is a (CH3COO)C6H4(COOH) Benzoic acid is a C6H5(COOH). You could not make TNP from benzoic acid so easily.
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stanfield
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posted March 17, 2002 06:01 AM
is there a way from benzoic ?
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vulture
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posted March 17, 2002 06:29 AM
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.
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Mr Cool
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posted March 17, 2002 06:44 AM
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.
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a_bab
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posted March 17, 2002 07:29 AM
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 ...
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stanfield
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posted March 17, 2002 07:51 AM
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 !
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Mr Cool
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posted March 17, 2002 08:47 AM
In theory, 636g. With a 70% yield, 445g.
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Marbles
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posted March 17, 2002 11:02 AM
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.
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andreas
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posted March 17, 2002 11:48 AM
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.
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mongo blongo
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posted March 17, 2002 11:55 AM
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.
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DBSP
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posted March 17, 2002 12:55 PM
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.
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Marbles
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posted March 18, 2002 12:30 PM
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.
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Marbles
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ALENGOSVIG1
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posted March 18, 2002 01:06 PM
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.
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vulture
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posted March 18, 2002 01:24 PM
Stanfield, what's the name of the company that resells acros products, maybe they have a bussiness in Belgium too?
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NG
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posted March 19, 2002 10:06 AM
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
[ March 19, 2002, 10:13 AM: Message edited by: NG ]
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Zambosan
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posted March 19, 2002 01:28 PM
Impurities, maybe?
[ July 18, 2002, 12:39 AM: Message edited by: Zambosan ]
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Anthony
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posted March 19, 2002 01:46 PM
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.
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NG
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posted March 20, 2002 04:18 AM
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]](confused.gif)
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.
[ March 20, 2002, 05:46 AM: Message edited by: NG ]
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vulture
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posted March 20, 2002 07:47 AM
Stanfield, why don't you just buy phenol, nitrophenol or dinitrophenol from acros?
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vonK
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posted March 22, 2002 09:26 PM
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?
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Dhzugasvili
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posted March 22, 2002 10:41 PM
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.
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CyclonitePyro
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posted March 24, 2002 11:50 PM
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)
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Polverone
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posted March 25, 2002 05:42 AM
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.
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nbk2000
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posted March 25, 2002 08:30 AM
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. ![[Big Grin]](biggrin.gif)
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.
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CyclonitePyro
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posted March 25, 2002 11:58 AM
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?
[ March 25, 2002, 12:19 PM: Message edited by: CyclonitePyro ]
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Polverone
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posted March 25, 2002 03:37 PM
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.
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nbk2000
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posted March 26, 2002 12:58 AM
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.
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.
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vonK
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posted March 26, 2002 04:41 AM
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?
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andreas
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posted March 29, 2002 11:44 AM
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 http://flashbangboom.homestead.com/home_page.html
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mongo blongo
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posted March 29, 2002 02:03 PM
Your tabs should be the cheap ones which only ASA and binders!
I.E. no paracetamol.
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nbk2000
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posted March 29, 2002 10:34 PM
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.
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S. Toppholzer
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posted April 03, 2002 04:24 PM
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??
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S. Toppholzer
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posted April 08, 2002 03:42 PM
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.
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kingspaz
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posted April 08, 2002 04:22 PM
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....
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vonK
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posted April 08, 2002 08:07 PM
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.
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Zambosan
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posted April 09, 2002 09:47 AM
Wouldn't picric acid decompose in UV light?
[ July 18, 2002, 12:44 AM: Message edited by: Zambosan ]
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kingspaz
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posted April 09, 2002 04:34 PM
i believe if the picric acid is slightly damp then the less sensitive hydrated picrates will form.
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nbk2000
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posted April 09, 2002 11:06 PM
Here's a patent for purifying aspirin using acetone.
US Patent #2,890,240.
Lists solubility in acetone at various temperatures too.
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S. Toppholzer
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posted April 11, 2002 02:32 PM
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?
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wantsomfet
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posted April 11, 2002 03:14 PM
S.Toppholzer - you'll need the AlternaTIFF plugin to view TIFF images in your browser...
http://www.alternatiff.com/
[ April 11, 2002, 03:15 PM: Message edited by: wantsomfet ]
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S. Toppholzer
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posted April 11, 2002 03:38 PM
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)
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rc
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posted April 11, 2002 04:53 PM
btw. can you use nh4no3 instead of kno3/nano3?
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Mr Cool
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posted April 11, 2002 06:30 PM
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...
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nbk2000
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posted April 12, 2002 12:26 AM
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.
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vonK
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posted April 12, 2002 05:48 AM
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.
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posted March 03, 2002 02:43 PM
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