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sylla
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sad.gif posted on 2-8-2003 at 06:01
potassium/sodium picrate


Hi all, as it is my first post I hope to be not too stupid and I apologize for my poor english :) I'm reading this forum for a few months and I think my question should have a place here.

Today I made some potassium picrate using powerlabs method (from picric acid using the i-ve-no-phenol-so-i-use-ASA way). I filtered some crystrals which (when dry) looks yellow (darker than picric acid). I took the solution and make it evaporate by sunlight (I'm not crazy since I used only 1g of trinitrophenol and had filtered most of the potassium picrate in step #1). When they were dry they looked dark orange (maybe red but you know colours...)

So I tried burning a few micrograms of picric acid, Kpicrate #1 and Kpicrate #2.

I'm now sure that #1 and #2 are NOT picric acid. both burned the same way but the #2 (dark orange) burned slower with more black carbon cloud.

So, do you have any idea ? Thx for your replies !

EbC Title.

[Edited on 16-12-2005 by chemoleo]
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[*] posted on 2-8-2003 at 17:47


Hi sylla,

Way back when it was ok to make home made fireworks. My father made them. He used black powder for some and a bright yellow powder for some small but powerful crackers. He always refused to tell me what it was. I now think it was a picrate.

The fact that may be helpful to you is when it was ignited it left a whitish powder mark not a black black one.

Have fun but be carefull Bob :)
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[*] posted on 5-8-2003 at 19:53


hey... ive made potassium picrate and i found it not really useful for anything oother than playing with, or perhaps as a sensitizer for something if you must. i heard its mixed with PETN to make nice powerful and sensitive mix for explodeing bridge wire detonators.

alwy, i think the powder you speak of is lead picrate. fits the description, except, in my expperiance lead picrate kinda sucks.

i think the reason k picrate #2 burned slower with more black is because it had TNP in there.
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sylla
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[*] posted on 9-8-2003 at 11:11


how do you explain the different color state ?

would #2 be anhydrous version of #1 which would have a different color ?
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[*] posted on 15-12-2005 at 16:29
Sodium Picrate


Hey,

I am wondering if anyone has any experience with sodium picrate. I haven't been able to find very much information out there, so I wish to resort to this board.

From what I can tell, it is a weak primary explosive, and is made by dissolving NaOH in a trinitrophenol solution, and then precipitating.

Does anyone have any knowledge has to how weak this substance is, and of its worth as apposed to say lead picrate?
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[*] posted on 16-12-2005 at 02:23
Pictrates!


Sylla,

Thanks for your questions!

1. If you reacted potassium hydroxide with picric acid in a sufficeint amount of water, you have potassium picrate.

2. As far as usefulness goes, usefullness is a function dependent on your intentions!

3. Basic lead picrate is the most violent and expediant of the metallic picrates! See US2175249, example 2, for the best of the best metallic picrates, which are best useful as flash igniter, never as primary explosive for practical purposes.

4. Picric acid is capable of reacting with a host of bases, metallic and non-metallic, including ammonia, amines, and amides, the most often desribed is ammonium picrate in literature. If you want to impress me, learn about reacting picric acid with complex amines to form stable explosives which are more powerful than picric acid alone.
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[*] posted on 16-12-2005 at 12:05


Sodium picrate is useless, save for purification of picric acid (add HCl to precipate the picric acid) or for picramic acid preperation. I guess it is somewhat aesthetically pleasing, being dark red and all. Next to lead picrate when comparing explosive properties, it is useless.

You neutralise a hot concentrated picric acid solution with NaOH, boil it down some (only if you are using large batches or extremely fussy about perfect yeilds) and cool. Precipation will ensue.




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[*] posted on 16-12-2005 at 16:36


Sylla, I have already aswered this question by mail to you but it was in french...so I can't simply copy paste it :(

More than certainly the first compound you get is the normal picrate salt...yellower than picric acid...important point but we get to this later.

You evaporated your remaining solution under the heat of the Belgian sun ;) ...note that the place shoudn't influence the result :D...the result is dus a mix of the same picrate but with an increasing concentration of the exces base...pH gets higher and higher....

Now let's get to a little theory for all those really interested in chemistry....
I will consider only the tiny portion of the aromatic ring placed just between the C holing the HO of picric acid and the C holding the ortho NO2 group...for convenience purpose, I will draw everything on a sheet of paper, scan it and this wil be joined as attachement.
The effect is thus true for any ortho nitrophenol...via an intra molecular mechanism. (I have taken the + and- sign of the nitro group away to simplify the drawing)

Note the formation of a ceton and of a nitronic acid patern!

As a parallel I have put also the equation for nitromethane...eveyone who has played with this and with a base has noticed the colour that appears...yellow...if yellow is concentrated it is orange, if more red...then brown and finally black...

Note that the aci form in the alcanic familly is more sensitive than the nitro form...this is the reason why bases are sometimes used to sensitise nitromethane...

This fact is true for the aromatic familly...especially if an exchangeable hydrogen is in the direct vicinity of a nitro group...

TNT is relatively unsensitive and yellow...by heating with NaOH...one could get an orange-red form of TNT that is more shock sensitive...
Here the proton transfer is harder than in TNP and so warming and conc NaOH is needed.

With picric acid the proton transfer is achieved in water at a feeble %...this explain why picric is nearly white yellow when dry, yellow when dilluted, makes very yellow picrates and forms orange/red colors in exces base...

Quote:
Originally posted by Sickman
If you want to impress me, learn about reacting picric acid with complex amines to form stable explosives which are more powerful than picric acid alone.


No will to impress you at all! :P

I have made a mix of Ni(NH2-NH2)3(NO3)2 (usually pale lilas-pink) coprecipitate with NH2-NH3O-C6H2(NO2)3 (hydrazine picrate-pale yellow).....the original pink complex had turned that way pale brown.
In the mix probably Ni picrate, Hydrazine picrate and nickel trihydrazine dinitrate complex...properties not very wel studied owing to the lack of made material (a few mg)...burns fiercely but difference with the original nickel nitrate hydrazinate not noticeable at that quantity...
I'll certainly come back on that study since I have plenty of Ni(NO3)2 at home, about 300g TNP, and about a kilogram of hydrazine sulfate...
And then I'll try to set a testing up to compare:
1)Ni(NH2-NH2)3(NO3)2 (pink)
2)Ni(OC6H2(NO2)3)2 (?colour?)
3)(Ni(NH2-NH2)3(NO2)3)x.(NH2-NH2-O-C6H2(NO2)3)y.(Ni(OC6H2(NO2)3)2)z (pale brown)

:cool::cool::cool:

[Edited on 17-12-2005 by PHILOU Zrealone]

[Edited on 17-12-2005 by PHILOU Zrealone]

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PH Z (PHILOU Zrealone)

"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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lacrima97
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[*] posted on 16-12-2005 at 16:46


Thank you Swany.

PHILOU: I do appreciate your in depth post, and i'm sure many others do as well.
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sylla
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[*] posted on 11-1-2006 at 13:21


Philou, thx for your reply but if you look at the post it has been done 2years ago so it's a different question actually :) Note that your mail did actually reply to the problem too...

I recently had another trouble (that I had discussed with philou by email) with picric acid salts. To resume the experiment I have tried a new approach on ammonium picrate because the current way of doing it is dangerous (consist of evaporating ammonium picrate solution that is very soluble). Unfortunately my picric acid was still moist (because of remaining H2SO4 of the synth) so I did a easy purification consisting of reacting it with KOH to produce potassium picrate and then reacting it with conc HCl to precipitate "pure" picric acid (as it as already been mentioned by someone above). The resulting picric acid was droped into acetone and shacked. The first amazing thing is that my moist picric acid dissolves very well in acetone as it should but purificated picric acid doesn't (even 1g in 100ml acetone yield nothing!). Then I filtered the so called picric acid and let it dry. This was very quick and gave me beautifull yellow crystals (much more yellow than the moist one). Then, I placed a coffee filter on a beaker containing conc ammonia (btw horizontal the filter, just to use some "porous paper") and the crystals on the top of the paper. After about 5minutes they turned orange but (not red as my potassium picrate tends to be). Another interresting thing is that it does detonate from flame! it is not as loud as silver carbide but quite surprising since picric acid nor potassium picrate does that.

Note that you pointed an error of massic ratio in my calculus leading to a large excess of HCl so if someone try to reproduce the experiment he should use 1ml HCl 30% per g K2CO3 used to neutralize picric acid.

You also suggested to prepare a solution of picric acid in ethanol and add drop by drop a amoniac/ethanol solution. The resulting ammonium picrate would then precipitate. (But then why just don't doing it in solid/vapor phase as I tried ? :D)

I need to point out that the so called ammonium picrate describe above has been tested "neutral" with K2CO3 (no CO2 evolutions) while it shows acidic before beeing exposed to the ammoniac. This could prove it worked.

You ended your email with several quotes to explain the detonation. I'll translate and resume them so everybody can work on the topic too.

1/ DNP or TNP way be present.
2/ The CompD might detonate that way.
3/ (the following part was painfull to understand for a undergraduate student like me so tell me if I killed the spirit of it) There is a enol-cetone-nitronic equilibrium with TNP that makes the darker form which is more sensitive (nb: indeed this would explain my very first post here). The same way, TNB and TNT have a red form in strong alkaly conditions that makes them more sensitive. This is because of a deprotonation that shifts the nitronic equilibrium (like it occurs in nitromethane). This is known for Comp D where a red form, more energetic, has been identified but it goes back to its normal form over time. -CO-C(=NO-ONH4)- <--> -C(-ONH4)=C(-NO2)-

If anybody have a little time to investigate on these energetic forms it would be great because picric acid is a so common synthesis for a lab amateur... At the end, I remember that styphnic acid has the same color problem and one could make a yellow form or a, more sensitive and more energetic red form. The difference here is that it doesn't flip back to its yellow form... Anyway, it's kinda normal to have these similitudes sinces styphnic acid shares a lot of structural properties with picric acid !

Good night everyone :)

[Edited on 11-1-2006 by sylla]
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[*] posted on 1-8-2006 at 22:21


Quote:
Originally posted by Joeychemist
I need the following refs please

J. Chem. Soc., 93, pg. 474 (1908) “Picrate Salts” by Silberrad & Phillips.


After finding a somewhat relevant thread amongst the very disorganised picric/ate posts!, heres pages 1-8.

Attachment: the metallic picrates 1-8.pdf (586kB)
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Axt
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[*] posted on 1-8-2006 at 22:22


And pages 9-16.

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sylla
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[*] posted on 6-1-2007 at 08:09


Seems I have troubles again with my picric acid :p

I left some PA in a dessicator for about one month with piperic acid made from piperine close to it and... on the surface the picric acid changed to very dark purple color :-/

Could some kind of piperidinium picrate have formed ? What could explain such a color ? :-/ And well, most of all, could it be dangerous (sensitive or else) ... ?

Sorry for the troubles of such silly questions :)
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[*] posted on 6-1-2007 at 22:32


Sylla,

That's an interesting observation.

Perhaps a deliberate experiment could be conducted by gently heating an alcoholic solution of piperic acid and adding the picric acid to this in portions with stirring (methanol or ethanol should work fine), to see if the addition compound forms.

Picric acid forms addition compounds with a great host of organic compounds, cinnamic acid is an example of this; the addition compound in the case of cinnamic acid has a melting point of 106.5 *C.

The general trend with nonmetallic, organic picrates is that they are more insensitive to impact than picric acid itself is, ammonium and gaunidine picrate for example. Even the majority of the metallic picrates are less sensitive to impact than picric acid itself is. For example, in a test reported by Davis, a 2 kilogram weight being used to test the samples, sodium picrate ignited by a drop of 17 inches, aluminum picrate 16 inches, picric acid a drop of 14 inches and these are all the minimum hieghts at which ignition or detonation occurs. All the hydrated picrates reported in the table have a minumum drop height greater than that of picric acid!

The key to these tests is that the picrate is crushed between two hard surfaces. Not to mention that 2 kilograms is alot of weight to be dropping on a picrate, prepared in the lab, on accident. My point being that in practice, handling picrates and indeed picric acid itself is not a major safety concern unless you plan on hitting it with a hammer!:D You probably wouldn't want to eat the stuff, or breathe it in, either.

However, another safety concern that should not be overlooked in handling any energetic material is static electricity. The experimenter should always have himself grounded at all times to avoid static discharges into the energetic material from the human body. Many accidental explosions have occured because of this very problem. A copper wire (exposed) and wrapped around the experimenter's wrist or ankle and grounded in the proper manner should illiminate this problem.

In the case of the addition compound (if any) formed by reaction of PA with piperic acid, a good test for it's energetic properties is the hammer test, in very small amounts mind you! This gives a sense of sensitivity and power of the material being tested.

By the way, Sylla, do you know which isomer of piperic acid you have or is it a mixture of isomers?
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[*] posted on 5-6-2013 at 19:09


Is sodium picrate more sensitive leads picrate? And can sodium or potassium picrate be used to detonate RDX or TNT?
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[*] posted on 5-6-2013 at 20:50


I kinda see these picrates more like sensitive base charges then actual primaries. I suppose they can be used to make det. cord?
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[*] posted on 6-6-2013 at 08:17


Metal picrates doesn't detonate at a high velocity so you can never use them as base charge but they can be used to make base charge more sensitive. They are more preferably used as primary explosives .



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[*] posted on 6-6-2013 at 09:44


What's the problem with the low velocity. Azide has 5100, that doesn't stop it to be No1 primary. Picrates have more energy density then organic peroxides and are more storage stable.
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[*] posted on 6-6-2013 at 13:50


Is sodium or potassium picrate soluble in water?
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[*] posted on 9-5-2014 at 22:27


I just made some sodium and potassium picrates. Potassium picrate has a very low solubility in water and ignites easily but does not detonate unless it is confined. It could be used as a propellant but its useless for detonators. Sodium picrate has a higher solubility and is much weaker than potassium picrate.
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[*] posted on 10-5-2014 at 03:06


The easiest way to make picrates is to mix slurry of wet picric acid with corresponding carbonate. I'm not sure about lead picrate, but Na, K and ammonium salts can be prepared in this way. I do not see, why people try to dissolve picric acid and then neutralize it with some base. Strange idea, because solubility of aforementioned acid is relatively low. Small excess of carbonates is useful too- result will not content free acid. Kalium picrate is something intermediate between primaries and explosives with low sensitivity. it does not require detonator- it explodes, been ignited in confinement.



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[*] posted on 10-5-2014 at 03:11


The easiest way to make picrates is to mix slurry of wet picric acid with corresponding carbonate. I'm not sure about lead picrate, but Na, K and ammonium salts can be prepared in this way. I do not see, why people try to dissolve picric acid and then neutralize it with some base. Strange idea, because solubility of aforementioned acid is relatively low. Small excess of carbonates is useful too- result will not content free acid. Kalium picrate is something intermediate between primaries and explosives with low sensitivity. it does not require detonator- it explodes, been ignited in confinement.



Women are more perilous sometimes, than any hi explosive.
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[*] posted on 10-5-2014 at 03:12


The easiest way to make picrates is to mix slurry of wet picric acid with corresponding carbonate. I'm not sure about lead picrate, but Na, K and ammonium salts can be prepared in this way. I do not see, why people try to dissolve picric acid and then neutralize it with some base. Strange idea, because solubility of aforementioned acid is relatively low. Small excess of carbonates is useful too- result will not content free acid. Kalium picrate is something intermediate between primaries and explosives with low sensitivity. it does not require detonator- it explodes, been ignited in confinement.



Women are more perilous sometimes, than any hi explosive.
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[*] posted on 30-7-2014 at 10:10


Another example of the immense versatility of picric acid/picrates for the amateur experimenter:

--> http://www.cecd.umd.edu/documents/presentations/Hong-Kong/Yi...

In the presentation a composition named k1k is listed as being a rougly 60/40 mix of potassium picrate and potassium perchlorate. When used in a dual reinforced 6mm cap design this composition is able to initiate PETN in less than 100 mg amounts, according to the table listed in chapter 5.

The composition is very flame sensitive and fast burning when unconfined, has low impact and friction sensitivity and is chemically very stable. Hard to say precisely without actual measurements, but when I made this composition, 1 mg confined in aluminium foil makes a really loud bang and displays about the same brisance as DDNP or NHN in the same quantitiy. Azides are much more brisant with these small amounts, though I have no doubt that with good cap design this composition would be able to initiate MHN or ETN. :-)

EDIT: I don't recommend using chlorates instead of perchlorates for this composition, any residual traces of picric acid will make the resulting composition very unstable andf possibly prone to autoignition!

[Edited on 30-7-2014 by nitro-genes]
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[*] posted on 30-7-2014 at 11:48


I have done testing with the chlorate version. Even when the powders are mixed on a sub-micron level, the detonation is weak or incomplete. It does dent steel though, so something is happening. Using sodium picrate instead of potassium picrate causes small amounts (a few mg) to melt before ignition. The liquid can sometimes explode with extraordinary brisance but usually just makes a sharp bang and rips the aluminium foil a little.
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