Sciencemadness Discussion Board - Picric acid: different instructions

Thanks guys, found Ledgard - should I trust someone who presents oxidation state and vallence as they were the same thing? I trust more "official" literature like Urbanski, etc (also some russian authors). Anyway one more question - Rosco describes synthesis that took him 5 hours, is this really the case for small batches (like 5g) or after one gradually adds nitrate and foaming is over + some 30 minutes at 110 °C is enough ? And pls, don't call this "spoonfeeding" I really checked literature before asking, here in forum one expects to hear real experience, a "recipe" is easy to find. I will see when (if) I try this.

I described here my own experience. I'd made some mistakes before I found right "recipe", but I think this sort of experience has no interest. Yeah, temperature regime is just that thing which you have to keep under control, otherwise runaway is possible.

Bot0nist - 3-12-2013 at 06:22

Not just cascading runaway. but also undesirable oxidation products, resinous gunk, and low yields if the temperature is controled. poorly throughout the reaction.

papaya - 3-12-2013 at 09:10

Thanks a lot, temperature is important, though what if one conducts synthesis on the boiling water bath (a little lower temperature than needed), and only heat higher at the very end? Also, any notes on salicylic acid usage instead of ASA, how to adjust quantities then, just on 1 to 1 molar basis ? Hope not bored everybody yet.

Bot0nist - 3-12-2013 at 09:22

The ASA sulfanation will break the ester anyway. I used a simmering brine bath to heat the sulfuric acid during ASA additions, and again to keep the.nitration heat up durring the first small additions. Then it may have to be removed from the bath as the exotherm from nitrate salt.additions picks up. Good mag stirring is vital. Think vortex...

papaya - 3-12-2013 at 12:27

Thing is I found rather pure salicylic acid (reagent), so don't want to bother with tablets, etc...

Bot0nist - 3-12-2013 at 13:19

Just run it as if it were ASA. Sulfanate and nitrate, and record your results for possible improvments.

caterpillar - 3-12-2013 at 13:57

Go ahead. Your own experience is the most valuable. And learn chemistry- pure theory is useful thing too.

roXefeller - 9-12-2013 at 15:35

I found to avoid a great deal of the NOx emissions was to split the sulfuric acid in two, the first part reacts with the ASA, while the second part, roughly in excess of stoichiometric amounts, was mixed with the nitrate salt. Then this is added the same way as the nitrate salt originally. There was a sweet spot for the addition rate that could be dialed in with the sep funnel. Beyond this spot would bring about the fumes again, but still not as bad as before.

barley81 - 14-12-2013 at 08:38

If it helps, I typeset/edited Rosco's original procedure (Dec 9, 2003, E&W forum). Note that this is <b>not the same</b> as the original. Any corrections or improvements would be appreciated. LaTeX and PDF files are both attached.

Has this been done already? If so, then *oops.*

Attachment: roscopicric.pdf (89kB)
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Attachment: roscopicric.tex (7kB)
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[Edited on 14-12-2013 by barley81]

Hennig Brand - 17-4-2014 at 10:34

For a long time I was off and on questioning the purity of the picric acid I was producing from ASA. Here is a couple of articles I found a while back which helped convince me that picric acid is the usual and only product from the direct sulfonation and nitration of ASA or salicylic acid.

Attachment: 4-Sulfo Salicylic Acid Nitration.pdf (1.1MB)
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Attachment: 4-Sulfo Salicylic Acid Synthesis.pdf (424kB)
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Rosco Bodine - 8-11-2014 at 08:52

Quote: Originally posted by ordenblitz

Working from Roscoe's good old country recipe as was posted in another thread, I made some TNP this weekend.

The materials…
http://img58.imageshack.us/img58/9658/asacrystals7bj.jpg
http://img58.imageshack.us/img58/4581/h2so48hp.jpg

93.75 grams of ASA were sulfonated in 375ml 80º, ~96.5% H2SO4
http://img58.imageshack.us/img58/8198/hotsulfasa8lv.jpg

Strangely enough, upon cooling overnight the solution remained clear with no sulfonated material precipitating.
http://img58.imageshack.us/img58/6996/coldsulfasa4gw.jpg

The mixture was placed in a 1000ml flask and the temperature raised to 95º. The additions of granular sodium nitrate commenced. The NaNO3 was obtained from a commercial fireworks chemical supplier and is of high quality but the actual purity is unknown.
http://img58.imageshack.us/img58/1463/beginnitra0wo.jpg
http://img58.imageshack.us/img58/9098/1stadd6oj.jpg

The solution began to slightly darken with each subsequent addition.
http://img58.imageshack.us/img58/627/3rdadd3sl.jpg
http://img58.imageshack.us/img58/9339/7thadd2jo.jpg
http://img58.imageshack.us/img58/2308/10thadd1uv.jpg

As the crystals of TNP formed the mix began to thicken and lighten again.
http://img58.imageshack.us/img58/5044/14thadd6gb.jpg

At this point there was considerable foaming upon the addition of the solid nitrate and the timing between same had to be greatly increased as was suggested.
http://img58.imageshack.us/img58/6453/22ndadd9zj.jpg

Stirring was very difficult and the viscous mix moved but slowly with my poor 2" stir bar. Roscoe mentioned a big 3"oval stir bar and It's surely needed! Next time I will use more sulfuric to lower the viscosity. No sense being stingy.
http://img58.imageshack.us/img58/6875/26thadd8se.jpg

Although it looks like foam, it’s a viscous crust of TNP sitting on the top of the acid. It was making the additions of the nitrate almost impossible to work into solution. This was the final addition of the nitrate.
http://img58.imageshack.us/img58/5117/28thfinal9bd.jpg

An evil looking brew as 500ml of water was being added from a wash bottle as the dilution began.
http://img58.imageshack.us/img58/7987/startdilution9mq.jpg

Some ice and some time and viola'
http://img58.imageshack.us/img58/634/dilutedandcooling4nd.jp...

Filtering out the raw TNP crystals. I cooled quickly, so the result is a voluminous fine crystal.
http://img58.imageshack.us/img58/8335/filteringtnp2kq.jpg

The raw material was suctioned well and dissolved in 2200 ml of boiling water and then allowed to cool again.
http://img58.imageshack.us/img58/7097/recrycooling2uk.jpg

The first crop was dried and weighed in at 84.2 grams or 70.5% of theoretical.
http://img58.imageshack.us/img58/2767/firstcrop6ff.jpg

The mother liquor was boiled down to ~500ml and a second crop was obtained. After filtering and drying a further 24.16 grams was obtained.
http://img58.imageshack.us/img58/9192/secondcropcooling9df.j...

The remaining TNP in solution was neutralized with K2CO3 then chilled and the crystals of potassium picrate were collected. They were then re-crystallized from acetone which yielded 3.56 grams, corresponding to 3.053 grams of picric acid in the final liquor.
http://img58.imageshack.us/img58/6001/ktnp7um.jpg

Final tally was 111.41 grams of C6H3N3O7, 93.38% based on ASA.
It was a good day. Thanks Roscoe.

Kinda perty aint she?

For those who may be looking for the other thread referenced for this synthesis

picric acid from ASA , NaNO3 and 92% H2SO4

http://www.sciencemadness.org/talk/viewthread.php?tid=4457&a...

Also attached are the ordenblitz images which have dead links

Attachment: ordenblitz pictures picric acid synthesis.pdf (663kB)
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Hawkguy - 26-1-2015 at 19:48

2, 4, 6 – Trinitrophenol [Picric Acid]

Picric Acid is a light yellow solid of bitter taste, hence its name. It was discovered in 1742 (earliest documentation), although it could have potentially been synthesised earlier by the nitration of organic materials. Picric Acid’s applications remained solely to use as a chemistry reagent and as a dye until 1830, when its properties as a secondary explosive were realized. The First World War saw extensive use of Trinitrophenol. Explosive action ceased however, because of its reactivity towards metals, forming unstable or hygroscopic salts. By the time World War Two came around, Picric Acid was only used as a Picratol precursor. Today the explosive is obsolete as to military application, but is sometimes used in fireworks for whistle mixes.
Preparation
Although 2, 4, 6 – Trinitrophenol was most often synthesized from Phenol, it is much easier to do so from Acetylsalicylic Acid. This is also a lot safer, as free Phenol, a potent carcinogen, is not handled directly through the ASA route.

- 6 grams of pure Acetylsalicylic Acid are dissolved in 60ml of 18M Sulphuric Acid at 20°C. The solution is heated over the course of 3 minutes to 110°C, and the Acetylsalicylic Acid will hydrolyse to Acetic and Salicylic Acid. The colour of the solution will change from clear, to yellow, to black. The Salicylic Acid will decarboxylate to Phenol and Carbon Dioxide, and Phenylsulphonic Acid will be formed.
- Potassium Nitrate is added in small portions over the course of the next 10 minutes. With every addition, the temperature will rise to 120°C. It is important to keep the temperature below 130°C, so a thermometer must be carefully monitored at all times. At this point the Phenylsulphonic Acid is undergoing a triple nitration to produce water, Sulphuric Acid, and 2, 4, 6 – Trinitrophenol. The temperature is dropped, and the colour will become an orange – red.
- After 5 minutes since the solution was removed from heating, it can be added to 300ml crushed ice, and a yellow precipitate will immediately form. This is the product, and it can be collected.
- [Purification] The product must undergo two water washes, rinses with water to remove acid and other residual contaminants. As well, a recrystallization from Ethyl Alcohol helps remove insoluble contaminants.

Bert - 26-1-2015 at 21:00

Quote:

By the time World War Two came around, Picric Acid was only used as a Picratol precursor. Today the explosive is obsolete as to military application,

I beg to differ.

During WWII, the Japanese used picric acid in shell fillers extensively, and the Germans used picric acid as a booster charge for some rather large TNT charged ordnance (500kg TNT parachute deployed naval mines with 1kg pelletized picric acid as a booster?!).

So... What do you have to contribute from personal experience.

caterpillar - 27-1-2015 at 02:47

Shellite, what was used during WWII in large caliber shells by Britons, was as a matter of fact picric acid with few percents of something like nitrophenole. Ammonium picrate ("dunnite" or compound "D") was used in anti-tank shells due to its low sensibility (lower than of the TNT).

Hawkguy - 27-1-2015 at 08:30

Sorry about that... Yeah you're right then.. I totally though that Picric was starting to be replaced by more modern nitrated explosives by then...

Rosco Bodine - 29-3-2015 at 16:26

Quote: Originally posted by Hennig Brand

For a long time I was off and on questioning the purity of the picric acid I was producing from ASA. Here is a couple of articles I found a while back which helped convince me that picric acid is the usual and only product from the direct sulfonation and nitration of ASA or salicylic acid.

This is the article I think will be most helpful. See first sentence at top of second page of article journal page 2040. This applies to the case involving 5-sulfosalicylic acid

Datta and Varma, J. Amer. Chem. Soc., 1919, 41, 2039

(article attached)

Attachment: JACS Vol 41 pg2039.pdf (414kB)
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[Edited on 30-3-2015 by Rosco Bodine]

Hennig Brand - 29-3-2015 at 17:11

Thanks for locating that. We have a nice collection of old articles now (pieces of the puzzle).

It is the first paragraph from the first article of the two that I posted above, where your article is referenced, which immediately got me very interested at the time.

"It has been found by the previous workers that the sulphonic acid group
in either 3-sulpho- or 5-sulpho-salicylic acid can easily be substituted by
the nitro group, and if the reaction is carried further, the -COOH group is
removed and picric acid is the usual and the only product. Thus Datta
and Varma obtained picric acid by the action of nitrous gases on 5-sulphosalicylic
acid. Meldrum and Hirwe obtained 3 : 5-dinitrosalicylic acid by
controlled nitration of 5-sulphosalicylic acid."

3 : 5-dinitrosalicylic acid is the intermediate just before decarboxylation and addition of the last nitro group forming picric acid.

Rosco Bodine - 29-3-2015 at 17:47

The sulfonate group is more stable than the carboxyl so the "steering effect" on substitution by the first entering nitro will I believe cause the decarboxylation and substitution of the nitro to occur for the first entering nitro group.

Hennig Brand - 29-3-2015 at 18:49

I am just an amateur experimenter, not a professional chemist, but I did asked Philou to explain this to me well over a year ago now and this is what I was told:

"Salicylic acid is very closely related to phenol and the hydroxy group is a very strong activator in ortho and para while the carboxy is an activator in meta... both effects are thus additive and favoring ortho and para position to the OH.
Once those two places are nitrated, the nitro groups are dropping the CO2 away from the aromatic ring and the rest of the reaction follows the course of normal nitration of 2,4-dinitrophenol"

5-Sulphosalicylic acid structure taken from Wiki.

5-Sulfosalicylic acid.png - 4kB

I think you must be forgetting, or just recently saw something that made you re-question some of this. The following was taken from "Rosco's Good Old Country Recipe for TNP":

"When about 2/3 of the sodium nitrate has been added, the reaction product is largely dinitrosalicylic acid, which will acquire a third nitro group while evolving carbon dioxide and thereby be converted to picric acid as the reaction proceeds."

[Edited on 30-3-2015 by Hennig Brand]

Rosco Bodine - 29-3-2015 at 19:36

It isn't really a substantive issue what is the mechanism, or if different paths are occurring simultaneously when all reactions in sum lead to the same 2,4,6-trinitrophenol as the end result in the same reaction mixture. All roads lead to Rome there.

For the case of phenol the hydroxyl on the ring strongly promotes ring substitution, much more than a ring hydrogen on ordinary benzene, but an added sulfonate group hinders further substitution relative to a ring hydrogen. For salicylic acid the carboxyl further hinders substitution even more than a sulfonate. In the case of 5-sulfosalicylic acid there is the promoting hydroxyl of phenol and BOTH the inhibiting sulfonate and further there is the even more inhibiting carboxyl.

My interpretation is the inhibiting groups would themselves be subject to substitution preferentially to the unsubstituted #6 position ring hydrogen which would be nitro substituted dead last if the nitration was steered according to my guess what happens. My understanding may be wrong but I would have supposed the carboxyl would be first to nitrate, the sulfonate would be second, agreeing with the intensity which they hinder substitution relative to a ordinary ring hydrogen, making the plain ring hydrogen at 6 the last to nitrate.

That is my guess how the reaction may proceed. Whether the guess is correct or not I don't know. I would trust what Nicodem may say about this more than Philou

BTW I do not even like the naming convention for 5-sulfosalicylic acid

When I look at the molecule I think of this name:

2-carboxyl-para phenolsulfonic acid

[Edited on 30-3-2015 by Rosco Bodine]

Hennig Brand - 29-3-2015 at 19:45

As long as all roads do in fact lead to Rome I am satisfied, which was my main interest before when I decided to do a little investigating. I found the naming of 5-sulfosalicylic acid a bit confusing myself.

Rosco Bodine - 29-3-2015 at 20:41

Quote: Originally posted by Hennig Brand

Yes I am questioning what I said earlier after thinking about how freely the decarboxylation foaming was occurring during the first third of the nitrate additions. I think I also made that observation. Reflecting on what I had observed has caused me to reevaluate that conclusion about what I observed, since most of the carboxyl group would have been decomposed early in the reaction.

Subsequent experiments will be done at a slightly different reaction condition and a thinner mixture or different temperature ramping. I think the conditions can also change what reaction course is the one which predominates during different times of the course of the reaction, and I think in different proportions all three possible nitro substitution reactions are occurring simultaneously. It could result in an improved synthesis to test variations and compare results.

additonal references

Rosco Bodine - 30-3-2015 at 21:56

Attached are some additional references related to sulfonation and nitration of salicylic acid. I think the only relevant mention about the sulfonation is on the first page of the article. Also attached is some general information about salicylic acid from Von Richter which pointed to those articles, which are in German.

Off topic but worth mentioning ....
I found it interesting also that methyl salicylate reacts readily with aqueous hydrazine to form a hydrazide of salicylic acid identified by Von Richter which may further be reacted with nitrous acid to form an azide. This could have interest as an obscure possibly useful route to azide.

Attachment: Nitro-sulfo-salicylic Acid.pdf (438kB)
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Attachment: Sulfonation of Salicylic Acid.pdf (606kB)
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Attachment: Salicylic Acid Pages from Von Richter.pdf (212kB)
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Attachment: Salicylic Acid Hydrazide.pdf (239kB)
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papaya - 31-3-2015 at 10:01

I found it interesting also that methyl salicylate reacts readily with aqueous hydrazine to form a hydrazide of salicylic acid identified by Von Richter which may further be reacted with nitrous acid to form an azide. This could have interest as an obscure possibly useful route to azide.

Very interesting, could this be done also with benzoate instead of salicylate ? Also, is it at all necessary to have methyl ester or plain acid can substitute it?

PHILOU Zrealone - 31-3-2015 at 10:41

Very interesting, could this be done also with benzoate instead of salicylate ? Also, is it at all necessary to have methyl ester or plain acid can substitute it?

This is an old known reaction initially found with hippuric acid hydrazide...an old way to make HN3
Ar-CO-OAlk + H2N-NH2 --> Ar-CO-NH-NH2 + Alk-OH
Ar-CO-NH-NH2 + HONO --> Ar-CO-NH-NH-N=O + H2O
Ar-CO-NH-NH-N=O <--> Ar-CO-NH-N=N-OH --> Ar-CO-N3 + H2O
Upon basic hydrolysis the aryl azide will generate an arylate and azide salt.

Yes it will work with benzoic acid. The ester is a convenient way to get the hydrazide easily (just like amide from NH3 and esters); this will not work directly from benzoic acid.
Methyl or ethyl esters are easier to get and the resulting methanol/ethanol easy to evaporate/separate.
The hydrazide is crystalline compound while the ester is usually liquid, just like hydrazine...so synthesis is pretty straightforward...

The aryl azide will degrade upon thermolysis via Curtius' degradation into isocyanate and after hydrolysis a convenient way to amines, it works also with the alkylic familly!

[Edited on 31-3-2015 by PHILOU Zrealone]

Rosco Bodine - 31-3-2015 at 10:54

This scheme is something that may fit my idea about synthesis of azide in decent yield being possible using aqueous solutions. Digesting the aryl azide with lime water should precipitate a low solubility calcium salt of the carboxylic acid and leave highly soluble calcium azide in the filtered solution. Reaction with sodium carbonate would precipitate calcium carbonate and leave highly soluble sodium azide in solution, evaporated to obtain crystallized sodium azide.

Could simply reacting the hydrazine product with MEK, or acetone azine, mixed with methyl salicylate, then produce the same salicylic acid hydrazide as the product?

[Edited on 31-3-2015 by Rosco Bodine]

Rosco Bodine - 31-3-2015 at 20:56

Very interesting, could this be done also with benzoate instead of salicylate ? Also, is it at all necessary to have methyl ester or plain acid can substitute it?

Yes it is necessary to have the ethyl or methyl ester of the carboxylic acid to form the hydrazide which is different from the simple acid salt of hydrazine. Hydrazine Salicylate mp 106C
is a different compound from Salicylic Acid Hydrazide mp 147C (corr. 150-151C) The salicylate of hydrazine is simply hydrazine coupled with salicylic acid. This salt has 2 more hydrogen atoms than the different molecule which is the hydrazide of salicylic acid.

https://books.google.com/books?id=JGJFAQAAIAAJ&pg=PA831&...

It is interesting that a mixture of methyl salicylate and hydrazine hydrate microwaved gently 450W for two minutes gives a 90% yield of the hydrazide compared with a 65% yield gotten by refluxing the reaction mixture for 1 hour.

See attached article

Attachment: Rapid Solvent-free Synthesis of Aromatic Hydrazides under Microwave Radiation.pdf (247kB)
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[Edited on 1-4-2015 by Rosco Bodine]

papaya - 1-4-2015 at 04:24

I was thinking of synthesizing ethyl benzoate and then reacting it with hydrazine to get desired hydrazide, since I can get sodium benzoate easily (but unfortunately not methyl salicylate), but after seeing how much work is the synthesis of methyl benzoate (look UC235 video at youtube http://www.youtube.com/watch?v=XCVx759TtNQ) I'm now off.
Interesting if this will work also with ethyl acetate (very OTC!) + hydrazine to give acetic acid hydrazide and then turning it into azide with HNO2, but the latter may be too dangerously explosive to deal with, what do you think?

[Edited on 1-4-2015 by papaya]

PHILOU Zrealone - 1-4-2015 at 04:37

This scheme is something that may fit my idea about synthesis of azide in decent yield being possible using aqueous solutions. Digesting the aryl azide with lime water should precipitate a low solubility calcium salt of the carboxylic acid and leave highly soluble calcium azide in the filtered solution. Reaction with sodium carbonate would precipitate calcium carbonate and leave highly soluble sodium azide in solution, evaporated to obtain crystallized sodium azide.

Could simply reacting the hydrazine product with MEK, or acetone azine, mixed with methyl salicylate, then produce the same salicylic acid hydrazide as the product?

[Edited on 31-3-2015 by Rosco Bodine]

Very good synthetic pathway to NaN3.

MEK azine or Propanone azine may be used as a discrete source of hydrazine (see USP 6002015 : Method of producing 1,2,4-TRIAZOLE) with water at high temperature (170°C listed in the patent).

But there is a chance the keton may react with the phenol compound to generate para-bonded alcool and finally alkene...and further polymeric material...
Usually it works with aldehyds like formol/ethanal (see phenol-formol thermoplastic); methylol enters easily in all ortho and para position.
HO-C6H4(CO2H) + (CH3)2C=O -??-> HO-C6H3(CO2H)-C(OH)(CH3)2 --> HO-C6H3(CO2H)-C(CH3)=CH2 + H2O
So it is maybe better to do without the hydroxy/phenol --> benzoates.

Also the presence of the phenol may be a problem at high temperature involved for the hydrolysis of the azine because as explained elsewhere phenol is in equilibrium with a keto form what will for sure take some hydrazine. The -OH is substituable by -NH2, by -NH-NH2 and maybe -NHOH (and reversely).
See conversion of TATNB into TNPhloroglucidol by diluted NaOH and NH3 evolution....or the conversion of TNP into TNA upon heating and saturated NH3.
HO-C6H5 + NH2-NH2 --> NH2-NH-C6H5 + H2O
HO-C6H5 <--> O=C6H6
O=C6H6 + NH2-NH2 --> NH2-N=C6H6 + H2O
NH2-N=C6H6 <--> NH2-NH-C6H5
Also possible in the final product C6H5-NH-NH-C6H5 and C6H5-N=N-C6H5.

Last but not least phenol is reactive towards the acyl azide leading to an urethane:
Ar-CO-N3 + HO-Ar --> Ar-NH-CO-O-Ar + N2

[Edited on 1-4-2015 by PHILOU Zrealone]

Rosco Bodine - 1-4-2015 at 09:45

If the Azines could be problematic because of unwanted reaction of the ketone fragment, perhaps better to just avoid them and work with an aqueous solution of the free hydrazine, but I don't know how good would be the reaction seeking formation of the hydrazide using a much more dilute aqueous hydrazine. The literature describes use of hydrazine hydrate but mentions no concentration requirements other than showing a much lower yield for the ethanol diluted mixture reacted under reflux.

The idea of microwaving hydrazine doesn't exactly fill me with enthusiasm

Working from methyl or ethyl benzoate would avoid those complications noted for the hydroxy benzoic esters. Formation of the hydrazide reminds me of transesterfication.

Deja Vu is strong for me about this idea and I think I may have already looked at this same idea or very similar alternative idea as a potential route to azides some years ago in the azide thread and looking at very old literature there.

papaya - 1-4-2015 at 10:53

Is there any good source of methyl or ethyl benzoates, or easier synthetic route to them? What about using ethylacetate ?

PHILOU Zrealone - 2-4-2015 at 04:54

Interesting if this will work also with ethyl acetate (very OTC!) + hydrazine to give acetic acid hydrazide and then turning it into azide with HNO2, but the latter may be too dangerously explosive to deal with, what do you think?

True that low molecular weight acyl azide are explosive.
CH3-CO-N3 is a liquid very prone to explosion in the concentrated state. The Curtius rearrangement must be done in an inert solvant that serves as manyfold diluant.
Even if there is no explosion the liberation of a good volume of N2 and volatile, flamable, toxic and carcinogenic methyl isocyanate (CH3-N=C=O) is not to neglect!

Other poly-acyl-azide are very dangerous explosive in the crystalline form: Fumaryl diazide, Malonyl diazide, Ethane-tetracarbonyl tetraazide.
As a rule the more carbon per azido group the best. High explosivity for 1/1, 2/1, 3/1.

PHILOU Zrealone - 2-4-2015 at 05:40

If the Azines could be problematic because of unwanted reaction of the ketone fragment, perhaps better to just avoid them and work with an aqueous solution of the free hydrazine, but I don't know how good would be the reaction seeking formation of the hydrazide using a much more dilute aqueous hydrazine. The literature describes use of hydrazine hydrate but mentions no concentration requirements other than showing a much lower yield for the ethanol diluted mixture reacted under reflux.

The idea of microwaving hydrazine doesn't exactly fill me with enthusiasm

There is always the possibility to increase hydrazine concentration by making the hydrochloride...isolate it by evaporation and allow it to react with solid Ca(OH)2 or NaOH in ethanol.

Won't you give a microwave for the science?
Microwave to Houston, do you copy, we have reached geostationnary orbit

Yes hydrazide formation is linked to transesterification and to transamidation...
R-CO-O-R' + R"OH <--> R-CO-O-R" + R'OH
R-CO-O-R' + R"-CO-O-R"' <--> R-CO-O-R"' + R"-CO-O-R'
R-CO-NH-R' + R"-NH2 <--> R-CO-NH-R" + R'-NH2
R-CO-NH2 + NH2-NH2(l) <-=> R-CO-NH-NH2 + NH3(g)
R-CO-NH2 + H2N-OH(l) <-=> R-CO-NHOH + NH3(g)
2 R-CO-OH + NH2-CO-NH2 <-heat=> 2 R-CO-NH2 + CO2(g) + H2O

And a last but not least reaction

especially for Rosco

!
Ar-CO-N3 + 2 NH3 --> Ar-CO-NH2 + NH4N3

The NH4N3 is said to be scarcely soluble in water (how much?), while the Ar-CO-NH2 (benzamide) is soluble to the extend of 1,35%.
But NH4N3 is quite stable, unsensitive and volatile (high vapor pressure)...what might be valuable for isolation from the mix (Under vaccuum --> sublimation on a cold surface).

The resulting benzamide may then be reacted with hydrazine and recycled into benzoyl hydrazide, it is much less, time and energy consuming than working via benzoic ester again

:
R-CO-NH2 + NH2-NH2(l) <-=> R-CO-NH-NH2 + NH3(g)
The resulting benzoyl hydrazide is also not very soluble in water (how much?).

A final idea based on the above to spare one more step:
Ar-CO-N3 + 2 NH2-NH2 --> Ar-CO-NH-NH2 + NH2-NH3N3
If hydrazinium azide is more soluble than benzoyl hydrazide --> isolation via solubility.
Otherwise there is a chance hydrazinium azide is like ammonium azide, also volatile --> sublimation in the cold vaccuum.

Does someone have references for hydroxylamine azide?
HONH3N3

PHILOU Zrealone - 2-4-2015 at 06:16

Is there any good source of methyl or ethyl benzoates, or easier synthetic route to them? What about using ethylacetate ?

That is maybe a good idea!
Ar-CO2H + CH3-CO2Me -heat-> Ar-CO2Me + CH3-CO2H
Ar-CO2H + CH3-CO2Et -heat-> Ar-CO2Et + CH3-CO2H

Maybe to be in a more practical T° range butyl acetate or ethyl formate.

Rosco Bodine - 2-4-2015 at 06:20

Is there any good source of methyl or ethyl benzoates, or easier synthetic route to them? What about using ethylacetate ?

About sourcing those esters or their synthesis, I have not done a thorough research but the esters appear to be easily synthesized.

Another example of the potentially useful esters would be methyl oxalate which would lead to a dihydrazide and ultimately to oxalyl diazide which could have interest itself. I don't think that oxalyl diazide has been discussed here before and I can't find many references about it other than it does exist. Maybe oxalyl diazide is another obscure item of interest identified for Klapotke and his group

http://www.sigmaaldrich.com/catalog/product/aldrich/131296?l...

Oxalic Dihydrazide

oxalic dihydrazide.png - 20kB

converted by reaction with nitrous acid to

Oxalic Diazide C2O2N6

oxalic diazide.png - 1kB

Update: The oxalic acid diazide reportedly explodes upon attempts at isolation. I knew it had to be energetic and only marginally stable. But evidently it is only barely stable at all.

http://onlinelibrary.wiley.com/doi/10.1002/cber.19640970630/...

https://books.google.com/books?id=i0AEIrEUfg0C&pg=PA151&...

Yes there can be used ethyl acetate which leads easily to a 98% conversion to Acetic Acid Hydrazide. I am attaching a couple of ancient articles by Curtius also which have identified this specific precursor being converted to acetyl azide, See page 10 of the pdf, journal page 463 chart last item in article
Curtius - Hydrazine und Azide Organicher Sauren (attached)

Also see page 13 of the pdf for a second Curtius article (attached). Evidently the type reaction scheme is general.

Attached also is an article showing synthesis of the hydrazides, following a scheme that is also general.

As a matter of simplicity I think it is probably an easier more practical route to sodium azide to work from semicarbazide or another hydrazide which can be made directly from the chlorourea process, which eliminates having to first make hydrazine and then convert an organic acid ester to a hydrazide.

The simplest ever reported synthesis of an azide by Angeli and developed later by Hodgkinson for silver azide is sort of the "holy grail" of a simple aqueous reaction system synthesis. However, it is a deviously fickle reaction requiring very exacting pH control, requiring a methodology never fully disclosed. Engager said that the Russians had worked out the details of that process, and evidently the British war college has also long ago done that same work. But there is no comprehensive reference cited or available published anywhere that I have found. Possibly the exact details about that process for silver azide are something of a secret, for which we are missing the file. The information may reside in some memoirs as hard copy in a reading room never digitized or published, or has been classified secret and remained classified (not for publication).

It is long overdue that some detailed description of that Hodgkinson / Angeli route to silver azide be published with full disclosure of the particulars. Bromothymol Blue and Bromocresol Purple and Alizarin and Methyl Red indicators along with a digital pH meter with some graphing and video coverage would be good. So long as we are wishing, why cut corners

Now there's an experiment!

An oldie but a goodie revisited, remastered.

https://www.youtube.com/watch?v=NowbmnpXYvU

<iframe sandbox width="640" height="480" src="https://www.youtube.com/embed/NowbmnpXYvU?rel=0" frameborder="0" allowfullscreen></iframe>

This thread from the discussion shift to azides should probably be split and merged with the sticky azides thread.

Attachment: Curtius - Hydrazine und Azide Organicher Sauren.pdf (381kB)
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Attachment: Curtius Journal_of_the_Switchmen_s_Union.pdf (691kB)
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Attachment: optimized production of acetylhydrazine.pdf (132kB)
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Attachment: Benzoic Acid Hydrazide.pdf (435kB)
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Attachment: benzoic acid hydrazide from methyl benzoate and alcohol containing hydrazine.pdf (119kB)
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Curtius related clip.bmp - 714kB

[Edited on 2-4-2015 by Rosco Bodine]

papaya - 2-4-2015 at 14:13

Wow, Roscoe that iranian paper on acetyl-hydrazine synthesis from ethylacetate with 98% yield is fantastic, actually this is kind of pour together and heat reaction type, interesting how to isolate the product after synthesis. Then it can be carefully converted into acetyl azide (in a very dilute form) and then for example to ammonium azide reacting with ammonia. In azide thread I found an attached paper where it's written ammonium azide can be "distilled" with water steam, another route for isolation.

Hennig Brand - 5-4-2015 at 08:42

Quote: Originally posted by Hennig Brand

Thanks for locating that. We have a nice collection of old articles now (pieces of the puzzle).

It is the first paragraph from the first article of the two that I posted above, where your article is referenced, which immediately got me very interested at the time.

"It has been found by the previous workers that the sulphonic acid group
in either 3-sulpho- or 5-sulpho-salicylic acid can easily be substituted by
the nitro group, and if the reaction is carried further, the -COOH group is
removed and picric acid is the usual and the only product. Thus Datta
and Varma obtained picric acid by the action of nitrous gases on 5-sulphosalicylic
acid. Meldrum and Hirwe obtained 3 : 5-dinitrosalicylic acid by
controlled nitration of 5-sulphosalicylic acid."

3 : 5-dinitrosalicylic acid is the intermediate just before decarboxylation and addition of the last nitro group forming picric acid.

Found another one of the old articles on my other computer.

Attachment: 3-Sulfo Salicylic Acid, etc - Meldrum and Hirwe.pdf (7.8MB)
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Rosco Bodine - 6-4-2015 at 09:41

The article described use of cool temperatures could have effect on the order of nitration substitution for the carboxyl so it could be different for the example given as compared with a higher temperature and use of a solid nitrate for the nitration, under conditions where also nitrosyl sulfuric acid is present. I think the conditions of nitration could have bearing on when the decarboxylation takes place.

Rosco Bodine - 6-4-2015 at 09:56

Wow, Roscoe that iranian paper on acetyl-hydrazine synthesis from ethylacetate with 98% yield is fantastic, actually this is kind of pour together and heat reaction type, interesting how to isolate the product after synthesis. Then it can be carefully converted into acetyl azide (in a very dilute form) and then for example to ammonium azide reacting with ammonia. In azide thread I found an attached paper where it's written ammonium azide can be "distilled" with water steam, another route for isolation.

Yeah it seems pretty straightforward. I am still intrigued by the methyl oxalate to oxalic hydrazide to oxalic azide route because there are other things like oxalic azide which can't be safely isolated that are still very useful intermediates in synthesis where they are immediately converted to something else and never isolated. I was thinking if the oxalic azide is produced in good yield then hydrolysis by calcium hydroxide would precipitate low soluble calcium oxalate and leave highly soluble calcium azide in solution, which could be easily converted to calcium carbonate also precipitated by sodium carbonate, leaving a sodium azide solution. It might even be possible as a one pot reaction.

PHILOU Zrealone - 7-4-2015 at 11:04

@Rosco,
Very nice idea fro Ca(N3)2 and Ca oxalate...
If oxalyl diazide is too critical for practical use...maybe tartric acid diazide is an alternative.
N3-CO-CHOH-CHOH-CO-N3 --> Ca(N3)2 and Ca tartrate

Rosco Bodine - 7-4-2015 at 12:02

Another thought I had is that by modifying the diazotization of the oxalic dihydrazide perhaps using calcium nitrite directly or maybe with pH adjusted by acetic acid or some other acid, that formation of oxalic diazide may be avoided and calcium azide hopefully would form directly, which would remain in solution with the byproduct calcium oxalate precipitated.

An unknown exists that the same sensitivity to pH and solubility factors as is seen for the Angeli / Hodgkinson reaction for producing silver azide may likewise occur for these similar reactions. It may be found that these reactions are technically possible but are are sensitive about reaction pH conditions to the point that practicality suffers.

A diazotization by an organic nitrite might work better also, and will proceed at a basic pH which may even be required to prevent the escape of volatile HN3.

Further treatment with sodium carbonate or ammonium carbonate or potassium carbonate would then precipitate the soluble calcium value of the calcium azide as calcium carbonate, and the filtered solution evaporated to obtain the desired azide.

This same general scheme might work for some other cases, like tartaric acid hydrazide or other hydrazides.

[Edited on 8-4-2015 by Rosco Bodine]

some old references and a new article

Rosco Bodine - 15-3-2018 at 09:43

Attached are some old references about picric acid and picrates

Attachment: Pages from The_Chemical_Gazette 1859 pg 1 to 8.pdf (506kB)
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Attachment: Pages from The_American_Journal_of_Science pg 379 to 385 M. Carey Lea picric acid and picrates.pdf (671kB)
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Attachment: Pages from The_American_Journal_of_Science pg 78 to 86 M. Carey Lea ammonium metallic picrates.pdf (829kB)
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Additionally is a recent and new article about a one step nitration of phenol in DMSO using HNO3, which may be more general and possibly applicable to nitration of other substances than phenol.

Attachment: Picric Acid via nitration of phenol in DMSO.pdf (398kB)
This file has been downloaded 1479 times

The Metallic Picrates

Rosco Bodine - 16-3-2018 at 14:45

Here attached is a more legible scan of an article posted earlier.

Attachment: The Metallic Picrates - Silberrad and Phillips.pdf (682kB)
This file has been downloaded 436 times

joseph6355 - 18-4-2018 at 00:20

Is recrystallizing picric acid from filtered tap water too stupid?
I mean, I'm aware that picrates will be formed, but will them be in considerable amounts enough to make the final material dangerous?
I will be casting it, btw.

Distilling water has become tedious, and buying it is a pain in the ***, because its heavy.
My reagents are technical grade, and my ASA is ACS grade. Is recrystallization a must considering that I will cast it?

[Edited on 18/4/18 by joseph6355]

XeonTheMGPony - 18-4-2018 at 04:12

what do you consider acceptable purity?

Clean pure product behaves reliable in predictable manner! why I distill store bought acetone and other reagents.

PhenethylamineMachine - 18-4-2018 at 05:06

I have been invested in a related project. This post is marking the topic so I can monitor it.

joseph6355 - 18-4-2018 at 17:38

Quote: Originally posted by XeonTheMGPony

what do you consider acceptable purity?

Clean pure product behaves reliable in predictable manner! why I distill store bought acetone and other reagents.

Pure enough so it won't spontaneously deflagrate when I'm casting it, neither it will increase its sensitivity to the point that it becomes friction or impact sensitive like a primary.

[Edited on 19/4/18 by joseph6355]

[Edited on 19/4/18 by joseph6355]

roXefeller - 18-4-2018 at 18:03

Quote:

Distilling water has become tedious, and buying it is a pain in the ***, because its heavy.

How much picric acid are you purifying if you are complaining about its weight?

joseph6355 - 18-4-2018 at 18:10

Quote: Originally posted by roXefeller

Quote:

Distilling water has become tedious, and buying it is a pain in the ***, because its heavy.

How much picric acid are you purifying if you are complaining about its weight?

A series of 100g charges.
I cast them into cylindrical shape with a hole in the center for the detonator.
I use it for breaking down concrete into small bits by making a 10-15 cm deep hole in it and placing the charge in there.

My father's property is full of concrete structures for some reason. He bought it as is and the previous owner couldn't tell him what they were.
I could take some pictures next time I go there.
Picric Acid isn't very soluble. I need about 1 liter of boiling water to recrystallize 70g of it.

greenlight - 18-4-2018 at 18:39

You could try this if you have enough ethanol:

"Making use of Phenol's high water solubility, and the higher solubility of dinitro and mononitroPhenol, the Picric Acid can be purified to near analytical grade by re-crystallization from a solvent mixture of 1 volume ethanol and 2 volumes water, roughly 9ml of solvent being required per gram of Picric Acid."

Instead of 1 litre per 70g, it would be about 600ml but it would cost more to recrystallize.

joseph6355 - 18-4-2018 at 23:41

Quote: Originally posted by greenlight

You could try this if you have enough ethanol:

"Making use of Phenol's high water solubility, and the higher solubility of dinitro and mononitroPhenol, the Picric Acid can be purified to near analytical grade by re-crystallization from a solvent mixture of 1 volume ethanol and 2 volumes water, roughly 9ml of solvent being required per gram of Picric Acid."

Instead of 1 litre per 70g, it would be about 600ml but it would cost more to recrystallize.

What is instead of distilling water using my hotplate, I used a stove? It would be much quicker.

Does water vapor catches metal particulates when passing through a copper or aluminum tube or is it safe to assume that it will not contain metal in it?

greenlight - 19-4-2018 at 03:25

If its just water your distilling then that would be fine.
Im not sure about the metal contamination. Surely it would be mininal.

I just buy 4 litre bottles of distilled water from the shop for a few bucks for materials synthesis and its saves me having to distill it myself.

If your worried about contamination that could lead to unstable salts, I would just buy the distilled water and its one less thing to worry about.

joseph6355 - 19-4-2018 at 03:38

Quote: Originally posted by greenlight

If its just water your distilling then that would be fine.
Im not sure about the metal contamination. Surely it would be mininal.

I just buy 4 litre bottles of distilled water from the shop for a few bucks for materials synthesis and its saves me having to distill it myself.

If your worried about contamination that could lead to unstable salts, I would just buy the distilled water and its one less thing to worry about.

I don't have a car, I work at mc donalds.
Its pretty common for people to cycle where I live, and the super markets aren't that far from home, but its still annoying having to cycle for 8 km with 20kg of water on my back

. And people keep looking at me because I'm wearing a huge backpack stuffed with things LOL.

Anyway. Is there a straightforward way to test a sample for metal picrates?
I heard aluminum doesn't form picrates with TNP. Is that correct? If thats the case, I could use an aluminum pressure cooker and aluminum tubing to transport the vapors into the glass container.
If there would be any aluminum traces in the water, it shouldn't react with TNP.
This should be right.

greenlight - 19-4-2018 at 21:54

I have not heard of a test for picrate. If picrate salt contamination is suspected, the bottle is not moved and the bomb squad is usually called. It is too unsafe to open to obtain a sample and this is probably why I havent heard of a test for it.

I think you will be okay with aluminium. Tin is safe too I have read but thats it.

joseph6355 - 20-4-2018 at 23:32

Quote: Originally posted by greenlight

I have not heard of a test for picrate. If picrate salt contamination is suspected, the bottle is not moved and the bomb squad is usually called. It is too unsafe to open to obtain a sample and this is probably why I havent heard of a test for it.

I think you will be okay with aluminium. Tin is safe too I have read but thats it.

Aluminum picrate does exist.
The book "SILBERRAD AND PHILLIPS: THE METALLIC PICRATES" says that Aluminum picrate exists and can be obtained.
I suppose it isn't readily formed and need some sort of catalyst to form and crystallize out. I'll have to dig out more to find a synthesis for this picrate and evaluate the possibility of it forming in a solution of water.

[Edited on 21/4/18 by joseph6355]

ManyInterests - 14-11-2022 at 08:01

Since I've completed my first successful picric acid synthesis recently I decided to resurrect this thread to ask some questions about my result.

Some notes. I will have to leave what I have here for a while. Like another week or so before decanting it and boiling the liquid down some more to extract the remaining picric acid that is in the water. I will be making another picric acid today (I hope).

I followed Roscoe's PDF instructions and a YouTube video that did the same. The only issue I have is the crystal shape. As you see they're fluffy and flat, and not the nice needle like structure that you see in some other places. Does this mean that the picric acid isn't good? Or is the crystal shape not as important and this is still useful for detonators and other stuff?

IMG_20221114_094706406 - Copy.jpg - 2.1MB

IMG_20221114_094711561 - Copy.jpg - 2.2MB

B(a)P - 14-11-2022 at 11:30

Since I've completed my first successful picric acid synthesis recently I decided to resurrect this thread to ask some questions about my result.

Some notes. I will have to leave what I have here for a while. Like another week or so before decanting it and boiling the liquid down some more to extract the remaining picric acid that is in the water. I will be making another picric acid today (I hope).

I followed Roscoe's PDF instructions and a YouTube video that did the same. The only issue I have is the crystal shape. As you see they're fluffy and flat, and not the nice needle like structure that you see in some other places. Does this mean that the picric acid isn't good? Or is the crystal shape not as important and this is still useful for detonators and other stuff?

Have you done a recrystallisation? Your crude product will likely look vastly different to what you get after a recrystallisation. If you want some interesting crystals to form during your recrystallisation then insulate your vessel to allow it to cool as slowly as possible. To help determine if you have picric acid and not the mono or di-nitrates a bit more information is required. If you followed Roscoe's PDF closely you likely have pircic acid. I have found good temperature control and slow additions the best way to maximise your yield for this procedure, also there are a couple of colour changes to look out for to help you know when you have reached your end points. Lower nitrated phenols have lower melting points, but the difference is only around 15C so it may be hard to determine the melting point accurately enough with the equipment that you have.

ManyInterests - 14-11-2022 at 17:57

I am confident that it is very pure picric acid (TNP) but I think it was cooled too quickly.

I made a 2nd batch today and I didn't dilute the main nitration mixture (after everything was complete) since it was already extremely liquid. I dumped directly into a lot of ice. I did squirt 250ml of ice cold water onto it anyway. I am going to keep it in the ice for 2 hours before filtering it.

What happened last time is that I made 50 grams of ASA starting in 225ml H2SO4 and and I used 95g of sodium nitrate. Everything went well and when I filtered it, I recrystalized everything in 1400ml of distilled water boiled down to 400ml and I decanted the liquid while leaving the MNP and DNP at the bottom that percipitated first as Rosco said. I did let it cool too fast. But I assume it is still good picric acid, no?

I notied that my thermometer's readings were way, way off. Good thing I have a separate thermometer to get a more accurate reading. I need to fix that.

B(a)P - 14-11-2022 at 18:22

I did let it cool too fast. But I assume it is still good picric acid, no?

You are correct. Depending on your intended use, smaller crystals may be more beneficial anyway.

ManyInterests - 14-11-2022 at 19:56

Well my 2nd doesn't appear to have as much yield as my first, but it could be because I used three different filter papers at first while the 1st time I used mostly 2. I will boil down the filter water as there is more than a liter of water in there. There will be lots of stuff I could use from them.

Quote:

You are correct. Depending on your intended use, smaller crystals may be more beneficial anyway.

I do want to (possibly) make a detonator with picric acid as a booster, but also to make a small charge of ammonium picrate.

In order news, my thermometer seems to peak at 92C. I don't know why it won't register higher temps, this isn't good for future picric acid synths.

Edit: Wow! I used too much water to crash the picric acid. I have 1600ml of liquid and I see LOTS of picric acid crystals shimmering within. I must boil it down to a third ( 500ml or less) and get my crystals...

edit2: I decided to do the recrystalization as well, I added more water and I put in the wet picric acid sludge into the liquor and I am boiling it down. I will boil it down to 400ml like last time. It'll be fine.

edit3: I realized that sometimes adding water to the nitrating mixture before crashing it might be essential. It's fine. It will only take a little longer than normal to get the good stuff.

Also I just got Ledgard's book that people mentioned earlier. I will look through it with a grain of salt. But I did see some interesting things on propellants in it that I might be looking into.

[Edited on 15-11-2022 by ManyInterests]

[Edited on 15-11-2022 by ManyInterests]

[Edited on 15-11-2022 by ManyInterests]

ManyInterests - 15-11-2022 at 15:24

After spending a lot of time boiling down the mother liquor, and then I left it to cool overnight outside (it was 0C last night) I was left with this crude product. (pictured below).

I spent some time boiling down the remaining mother liquor to see if I can squeeze out more crude picric acid. I am not sure if my yield is more or less than last time, but I will need to recrystalize this stuff regardless. It might not be as much as my first time (which is still not weighed and will remain wet for a while).

I made this batch with potassium nitrate (if I didn't mention it already) and I think it would be better if I stuck with sodium nitrate for future synths.

Edit: I think I got almost all the remaining picric acid. There is 200ml of liquid left, and I do believe it is the left over sulfuric acid and nitrate salt. I tried to bring it to a boil, but there was no more water left. I am chilling it in my fridge to see if I can pull out any more picric acid. I will crash it in ice cold water after cooling it in the fridge.

Edit2: Crashed more stuff out from the acid after putting it in the fridge for more than hour (acid sure takes a long time to cool!) and I poured around 600ml of ice cold distilled water in it. I've put it in the freezer. Going to set a timer to check on it every 30 minutes.

Edit3: Managed to get a good amount of picric acid from all this! It's good. I am doing a recrystalization. dissolved everything in 1600ml of water and I am going to boil it down to 350ml or so before stopping the boil. All in all I am pretty proud of myself and what I've done so far!

IMG_20221115_164452204_-_Copy.jpg - 2.3MB

[Edited on 16-11-2022 by ManyInterests]

[Edited on 16-11-2022 by ManyInterests]

[Edited on 16-11-2022 by ManyInterests]

ManyInterests - 18-11-2022 at 21:31

Might as well drop an update. My picric is stored wet currently. My 2nd batch's recrystalization was not done ideally, as I boiled the water too much and I did not decant the acid to pour out the TNP while leaving behind the impurities. I will need a re-recrystalization.

XeonTheMGPony - 20-11-2022 at 06:09

Slowness is the secret. All so it really doesn't like water, boiling it down super amounts really won't get you any more material, non that you'll want anyways, all ways better to keep starting volumes as small as practical to start.

use slightly less water then called for, bring to full boil add aliquat of Piciric, some should remain, add just enough water till the remains dissolve, it should be an active boil at this determining point

Now take container and wrap in several towels (After covering the top) better insulated the better!

Leave undisturbed till at room temp, I usually leave it a full day and night, then whilst wrapped in towel place in fridge for a day or so.

Enjoy your nice TNP crystals.

Now if adventurous, filter out and crush up crystals while damp, add in ammonia to convert to Dunnite! and from there you can make Piciramic acid, and eventually DDNP

ManyInterests - 22-11-2022 at 17:58

I left it undisturbed for a week, my 2nd batch definitely needs a re-recrystalization since I see a lot of red bits in the picric acid. I do believe this is the stuff I don't want. It'll still have to wait before I repurify it again.

And yes I do want to make Dunnite. I did have a question for it. Would dissolving everything in 6% ammonia solution be good for making dunnite? The ammonia is there and it is mostly water so...

B(a)P - 22-11-2022 at 19:20

I left it undisturbed for a week, my 2nd batch definitely needs a re-recrystalization since I see a lot of red bits in the picric acid. I do believe this is the stuff I don't want. It'll still have to wait before I repurify it again.

And yes I do want to make Dunnite. I did have a question for it. Would dissolving everything in 6% ammonia solution be good for making dunnite? The ammonia is there and it is mostly water so...

You would be best to heat your picric acid before adding the ammonia solution. Make sure to add an excess of ammonia. Also note that it is somewhat soluble in water, similar to picric acid.

XeonTheMGPony - 22-11-2022 at 19:27

You aut to get some conversion, not sure if the heating would drive the ammonia out though, I dissolved in water then gassed in the ammonia till the colour changed and I smelt free ammonia, then stopped the gassing and allowed to slowly cool

[Edited on 23-11-2022 by XeonTheMGPony]

[Edited on 23-11-2022 by XeonTheMGPony]

[Edited on 23-11-2022 by XeonTheMGPony]

ManyInterests - 22-11-2022 at 22:54

I can cover the beaker with the ammonia water in it in order to stop the gas from volatilizing. Also I want to make the red version of ammonium picrate, not the yellow. The reason being is that when I want to make my detonator I want to see if it can detonate something as insensitive as TNT. If it can, then I know I have a quality detonator! That's my benchmark.

Yellow Ammonium picrate is simply too insensitive and requires a compound detonator to work. I want to set something off that a detonator made to the Improvised Munitions Guide. By that I mean (at least) 1 gram of secondary such as RDX, picric acid, or PETN (and ETN I guess) with the primary following. For NHN I am thinking I will need at least 0.4g from here on out.

the only thing that is missing is me having a way to mechanically press my detonators, since handpressing will not achieve the proper densities required.

I am still confused if melt-casting ETN in a cap and leaving it as is will be sufficient or if I HAVE to breakup the melt-cast ETN and grind it to dust before filling the cap with the ETN and pressing it again. ETN should be the superior booster to either PETN or RDX due to its O-positive balance.

XeonTheMGPony - 24-11-2022 at 04:03

I have never heard of "red" Picric acid, what you see there is Dunnit, and it goes pop fairly well with proper initiation.

Keep practising.

When I started I made Mercury fulminate caps, then I learned compounding and studied, then it was MF 80% / Potassium Chlorate 20%.

Then as skill in chem improved I moved to 2 Stage caps, HMTD was used at 300mg (All ways better to have more of stage 1 than needed than a fissled cap that may or may not go off seconds later!) and ETN as final stage, and even to this day it is my preferred one, once I remake my primer stocks, I will try ETN/PTEN compounded, and may do RDX/ETN test again.

Then after many many many tests I found the smallest amount I could use based on my process for making them.

Now I make basic commercial style spec caps scaled down, then the boosters can be various types and sizes.

Focus on your detonators, once you get a good reliable system going with what you have, then move on to the next step, but IMO with out a safe reliable firing system no point trying to make hard to fire stuff

and as you see the steel plates, that is your test, if it cuts a clean hole with minimal spalling on the bottom you got a solid system.

Herr Haber - 27-11-2022 at 05:06

With 1 gram of RDX or ETN you will basically have a number 10 detonator which will be able to set off anything you insert it in no matter how insensitive it is.
Ammonium picrate is *less* sensitive than TNT which in turn is less sensitive than picric acid. It was the explosive of choice for very large AP shells. The 406mm AP shells of the Iowa class weighted 1.3 tons of which only 20 kg were Dunnite.

You dont have to break up the melt cast ETN if it's already in it's final casing of course. By the way, you mention the intention of using picric acid as a secondary in your detonators. That is a very bad idea mostly as it will prevent you from using a metal casing and I'm pretty sure you would only get a partial detonation from NHN / Picric acid in a plastic body.
I'm also pretty sure picric acid is a worst initiator than ETN / PETN / RDX.

When making ammonium picrate you want to be certain you are using picric acid free from impurities (leftover acids from nitration). Since you will be boiling ammonia water, covering the beaker will simply not be enough. Best do it outside or next to a window. Prepare airtight goggles or a gas mask to work around boiling ammonia. Really, I mean it !!! You cant just hold your breath: you need to see.
You're better off using large excess of ammonia otherwise you will end up with a mix of ammonium picrate and picric acid which depending on the planned use might be a very bad thing. The excess gas will boil off before water so excess is not a problem.
Normal ammonium picrate looks orange just like on Xeon's picture.

I totally agree with Xeon's recommendation of making small detonators that you can insert in a booster to set off your main charge. Safety first.

ManyInterests - 30-11-2022 at 21:28

Yeah, commercial type detonators are interesting. they do have the primaries in one container and the booster in the 2nd. The only guide I have in making detonators is the improvised munitions guide, which involves 1 gram of RDX or picric acid (their recommendations as there is no mention of PETN or ETN in the book) + some amount of primary (they list many). Their way is to put the secondary, tamp it, then add the primary and tamp gently before using a press (which is very large and almost 1.5 meters long) to mechanically press the cap to a fairly high density. I have no such press and I don't intend to make one, hence just melt-casting the ETN and giving a good strong press by hand to the NHN (Which I've done almost 2 dozen times without incident) should be sufficient.

I'm not likely to actually use picric acid as a booster since I have no aluminum cases to put them in, only brass (spent firearm shell cases) and steel.

My only wish is that I had a place nearby where I can make tests for caps without noise concerns, since I do live in a densely populated area and lots of loud bangs will attract unwanted attention.

I think when I said 'red' ammonium picrate it might have been more orange in color. I will definitely look it up once I have all the picric acid that I want made. failed to fully purify one batch so I have a lot of work to do to make it clean and pure before I turn it into picrate.

Edit: some things I will need for the future is a good gas mask in addition to a whole lot of other equipment. I will need to wait a bit to save up the cash for it.

One other thing for the ammonium picrate is that I do have 2 liters of 6% ammonia solution (only ammonia and water) and around 200 to 250ml of 28% lab grade ammonia. I don't have the equipment to concentrate them to something stronger.

[Edited on 1-12-2022 by ManyInterests]

XeonTheMGPony - 1-12-2022 at 04:19

Yeah, commercial type detonators are interesting. they do have the primaries in one container and the booster in the 2nd. The only guide I have in making detonators is the improvised munitions guide, which involves 1 gram of RDX or picric acid (their recommendations as there is no mention of PETN or ETN in the book) + some amount of primary (they list many). Their way is to put the secondary, tamp it, then add the primary and tamp gently before using a press (which is very large and almost 1.5 meters long) to mechanically press the cap to a fairly high density. I have no such press and I don't intend to make one, hence just melt-casting the ETN and giving a good strong press by hand to the NHN (Which I've done almost 2 dozen times without incident) should be sufficient.

I'm not likely to actually use picric acid as a booster since I have no aluminum cases to put them in, only brass (spent firearm shell cases) and steel.

My only wish is that I had a place nearby where I can make tests for caps without noise concerns, since I do live in a densely populated area and lots of loud bangs will attract unwanted attention.

I think when I said 'red' ammonium picrate it might have been more orange in color. I will definitely look it up once I have all the picric acid that I want made. failed to fully purify one batch so I have a lot of work to do to make it clean and pure before I turn it into picrate.

Edit: some things I will need for the future is a good gas mask in addition to a whole lot of other equipment. I will need to wait a bit to save up the cash for it.

One other thing for the ammonium picrate is that I do have 2 liters of 6% ammonia solution (only ammonia and water) and around 200 to 250ml of 28% lab grade ammonia. I don't have the equipment to concentrate them to something stronger.

[Edited on 1-12-2022 by ManyInterests]

you generate ammonia gas directly, by ammonium sulphate being acted upon by sodium hydroxide, then heat once gas production drops.

An effective generator can be made more crudely if required but this is what I use:

If EM is going to be your Hobby then the first thing you absolutely must have with no exception is a good distillation apparatus.

Next will be a good stirring system, makes worlds of difference

Then means of generating gasses simple enough, a non equalizing dropper funnel then the same gear above

Herr Haber - 1-12-2022 at 07:43

Good idea on the gas mask. A couple of different filters will also come in handy. They are expensive though depending on what they are for (NOx, organic vapors, dust, etc.)
Keep in mind that you can overpower the filter of any gas mask. I can assure you that standing over a beaker full of boiling ammonia will make you cry even if you're outside with the best mask in existance.

Check out Ordnance labs videos on Gas mask + tear gas on Youtube. The lesson from these videos is that you only lessen the risk but never negate it. Pretty important to think about when you're exposed to NOx.

You can either set up an ammonia generator like Xeon suggests (though I'd keep that for times when I need anhydrous conditions) or use the 6% solution you have. It should be easier on your eyes than 30+ % as it wont outgas as fast when you heat it. You'll just have more water to boil but that shouldnt be a problem.

ManyInterests - 1-12-2022 at 09:50

I have a good distillation setup. I don't have that specific column that you have. I have a heating mantle with magnetic stirrer, an alihn condenser, and a whole ton of good glass ware that has never failed me.

i have also ordered a simple magnetic stirrer (no heating) as sometimes I just need a good stirring system outside my mantle (and my mantle isn't that good in stirring in beakers. I believe having a stirrer that I can stir things in when I have a beaker in an ice bath (which is impossible with the mantle) will be very useful.

Can you list the glass ware you have there specifically? With the attachments and such. I am probably going to be in the market for those. I did find them previously, but they were pricey.

So until I get those I will need to use my ammonia solution. I will have to rely mostly on the 6% solution (mostly with some 28% added in).

Does the picric acid need to be fully dissolved in liquid for it to turn to ammonium picrate, or is some saturated solution sufficient? I will not add any picric until the solution is bubbling hot for obvious resaons.

[Edited on 1-12-2022 by ManyInterests]

Herr Haber - 1-12-2022 at 11:15

For a simple gas generator you need:
1 dropping funnel with a glass stopper
1 flask (round with 2 necks, erlenmeyer with a side arm, etc).
Some tubing
If necessary a bubler or a pipette attached at the end of your tubing.

The flask can be the same one you use for vacuum filtration if the joint size is adequate.

I would recommend you put your picric acid in a suspension of ammonia water before turning the heat on, then proceed with small additions of ammonia. If you do the way you suggest a lot of the gas will be lost before having any chance to react with the acid and it'll just be unpleasant longer.
You can add more ammonia until everything dissolves while heating to be 100% sure you converted everything. It's better to use an excess of ammonia; you will get rid of it when heating to reduce the volume and get your product when it cools.

XeonTheMGPony - 1-12-2022 at 13:56

My method was fully dissolve the picric in distilled water under stirring, once a clear yellow solution was present, I started the ammonia generator directly bubbling in the stirred solution, the ammonia generator was all ready at a simmer to ensure the ammonia was fully expelled.

this was run till a slight excess of ammonia was present determined by free ammonia smell

ManyInterests - 2-12-2022 at 09:21

Thanks for the advice. Seems like picric acid is a journey in and of itself.

But I am having this issue. Last night I decided to filter out the picric acid from the beakers and do a re-recrystalization of the older batch and concentrate the liquid of the other batch. But I have this issue.

I placed the picric acid on a sheet of aluminum foil to let it dry off, but I am seeing some discoloration. What is happening here? I hope it isn't degrading my picric. It shouldn't form any other explosive salts. I transferred them to styrofoam plate covered with many layers of paper towel.

IMG_20221202_121652949_HDR - Copy.jpg - 2.4MB

[Edited on 2-12-2022 by ManyInterests]

[Edited on 2-12-2022 by ManyInterests]

Herr Haber - 2-12-2022 at 14:05

I dont know about aluminium picrate but I would never put picric acid in contact with a metal.
Besides, if you need something dry you're better off leaving it in it's filter paper and putting this filter paper on top of a few layers of paper towel and a plate.
If wind / dust is going to be an issue put another plate face down to cover your product. It wont dry perfectly if you leave the plate over it though. I recommend you move the product around with a plastic spoon to expose more moisture. You can also use wood (those disposable chop sticks are good for everything!) but it will turn black.
Good towel paper should wick away moisture away from between the two plates in a couple of days in the worst conditions. Next to a heater during winter can be very fast.

ManyInterests - 2-12-2022 at 16:12

I thought that picric acid didn't react with aluminum! now I know. So I'm not going to ever do that again. I even checked out the post made just before I ressurected this thread... aluminum picrate exists! I have no idea how sensitive it is, but I hope it isn't dangerous. I'm going to use all of what I made here in order to make the ammonium picrate.

https://chempedia.info/info/aluminum_picrate/

[Edited on 3-12-2022 by ManyInterests]

ManyInterests - 2-12-2022 at 19:53

So I have a photo of my first two picric acid batches now drying. I have more that I am going to boil out of the remaining liquid (I have 800ml to boil down to 300ml or so, collect what I can, and call it good for this round).

the colors are different. Is something up with it? Or is it OK? I know some of the discoloration on the plate on the left is due to the aluminum, but the one on the right is one that I reboiled down (at 80C). The one on the left is boiled at a higher temperature before I realized that this is not a good temperature to do it. Did I degrade that picric acid or what?

IMG_20221202_224734195 - Copy.jpg - 2.6MB

B(a)P - 3-12-2022 at 00:26

Looks like a different crystal size/shape? That would likely account for the difference in appearance.

ManyInterests - 3-12-2022 at 00:34

Quote: Originally posted by B(a)P

Looks like a different crystal size/shape? That would likely account for the difference in appearance.

OK good, as long as the purity of my product isn't compromised... except for the silly aluminium mistake, but I don't think that'll affect it that much when turning all this to ammonium picrate.

It'll be a couple of days before they fully dry. I got time. I want to see my overall yield from these before continuing with anything else.

Herr Haber - 4-12-2022 at 05:15

Like B(a)P says.
If you want to be sure dont combine the batches just in case you have some Al picrate in there. I really dont know the compound either.
There's litterally zero chance you degraded your product by heating it when recrystallizing it. It's melting point is far above the temperature you can reach with water and it's decomposition even higher.

ManyInterests - 5-12-2022 at 17:19

Well it's kinda too late when it comes to combining batches since I put them both together (albeit I will keep this one separate from the next two batches I intend to make). I don't think aluminium picrate is that dangerous, but then again it might... at any rate, I will turn all of this into ammonium picrate once everything is 100% dry (there is still some moisture and I just started drying the last bit of picric acid that I squeezed out of these).

Thanks for telling me about the temperature thing. I just need to make sure that my thermometer is working, I have a replacement, butI want to see if I can squeeze one last bit of life from my old one for these picric acid synths and call it a day. The thermometer seems to peak at 80-something C and doesn't want to go higher, it nearly wrecked my last picric acid synth since the temperature of the sulfonated ASA reached 150C when it was not supposed to be beyond 120. Thankfully I have a back up and I waited for it to cool down and added the sodium nitrate and everything went well.

The next two (and possibly final) picric acid synths should go without a hitch, since I've been getting some good experience with everything.

I feel like it's too windy outside my apartment for me to want to go out and make another synth. I also do want to burn the papers I used to dry everything in instead of throwing them in the trash.

Edit: I've also been neutralizing whatever is left by heavily diluting it in water and adding large amounts of baking soda to it. It produces no toxic gasses and I can do it in my kitchen sink! I give it all the time it needs to fully react as I don't want any amount of picric acid going into the sewer. I am not sure if the pipes in my area are fully PVC or not, but a good deal are.

[Edited on 6-12-2022 by ManyInterests]

Herr Haber - 6-12-2022 at 03:29

I worry a bit about the Al because even Ca in the factory floors was an issue.
If my memory serves, sulphonation at 120c for 2 hours is recommended either by a forum member or Urbanski (again).
About thermometers: a good thermometer that goes from -10c to 250c doesnt exist. It'll be cheaper and you'll have better readings with several thermometers with shorter ranges.
A good thermometer isnt cheap and breaking one was was the best way to stop me from using them as stir rods !
See them as an investment since they will help you avoid screwing up a synth because of temperatures therefore saving money and time.

ManyInterests - 6-12-2022 at 11:10

Quote: Originally posted by Herr Haber

I worry a bit about the Al because even Ca in the factory floors was an issue.
If my memory serves, sulphonation at 120c for 2 hours is recommended either by a forum member or Urbanski (again).
About thermometers: a good thermometer that goes from -10c to 250c doesnt exist. It'll be cheaper and you'll have better readings with several thermometers with shorter ranges.
A good thermometer isnt cheap and breaking one was was the best way to stop me from using them as stir rods !
See them as an investment since they will help you avoid screwing up a synth because of temperatures therefore saving money and time.

I wasn't able to do the 2 hour sulfonation last time due to the thermometer issue. I think that should be a sign that I should replace the thermometer. I still think it went OK.

Edit: What should I do about the possible aluminum picrate? I have no experience with it and I am not sure if yet another recrystalization will do anything to get rid of it since it might precipitate out.

[Edited on 6-12-2022 by ManyInterests]

Alkoholvergiftung - 6-12-2022 at 20:03

Aluminiumpicrate is the only none explosvie picrate salt. So its save. Source (Escales Nitroexplosives).
really sensitive are only Lead , iron and Copper picrate. and in contact with leadoxide it does detonate from alone(the picrid acid).

[Edited on 7-12-2022 by Alkoholvergiftung]

ManyInterests - 7-12-2022 at 11:53

Good so I am safe. Thank you for that.

ManyInterests - 8-12-2022 at 14:27

So I finally was able to dry the picric of my first two synths. I got a total yield of 103 grams and of varying crystals and colors. But I am sure they are fairly pure.

It took a long for them to dry, that's for sure!

IMG_20221208_164121370 - Copy.jpg - 1.5MB

XeonTheMGPony - 9-12-2022 at 03:42

best investment ever was a good vacuum filtering rig! I strongly recommend it, Second option is a thermal static warming pan and a few layers of paper towel.

ManyInterests - 11-12-2022 at 15:13

So my third batch is basically done, just some cooling time and then evaporating the rest still in order to squeeze out as much picric acid as possible from this (and of course, the drying time!).

I found something rather interesting in this batch. I added too much water (as usual!) when crashing out the picric after the synthesis. I decided that I could evaporate everything off AND basically do a recrystalization in one step. During my 2nd batch (this is my 3rd) I didn't add water to the picric acid solution before crashing it in the ice. I didn't think it was necessary, but I realized I had made an error at that time.

I actually used 1600ml of water to crash it! I had too much picric still dissolved. when I boiled that water down I got to around 200ml with no crystals until I left it to cool down and it became a solid chunk of picric acid. I then added all the crude picric acid I filtered out the first time and 2000ml of distilled water for a recrystalization. It took a long time (excess of 24 hours) to evaporate down to 800ml before I saw plenty of the red blob of impurities at the bottom and I decided it was a good time to decant it and get rid of the impurities.

It's being a fun experience making picric acid!

The pic shows the hot picric acid solution and the other shows the soldifying impurities (which are being neturalized with water and sodium bicarbonate). Some tiny bit of the red blob came in, but I am confident that it is 99% pure.

My first two batches need to be ground up to get some consistent crystal size.

IMG_20221211_173311765 - Copy.jpg - 1.1MB

IMG_20221211_173321602 - Copy.jpg - 1011kB

ManyInterests - 12-12-2022 at 09:37

So after filtering I did boil down the remaining liquid by half or so, then I decided to let it cool down at room temp. Nothing crystalized, so I decided to put it in the fridge (not the freezer) and most of what I assume is the picric solidified. I put them all in coffee filters and will wait for them to fully filter out. The crystal sizes might be off, but once ground up, they'll be good for anything. In several hours I will squeeze out what I got from them.

I cleaned up as much of the impurities as possible via Rosco's boiling method. This should be good.

I wasn't able to post the photos for some reason...

Herr Haber - 12-12-2022 at 10:35

Adding water at the end of nitration dilutes the sulphuric acid in which PA is very soluble especially at high temperatures.
The only "annoying" part in this synthesis is knowing that you are going to lose a bit of product while getting rid of H2SO4 / water. It's otherwise quite instructing.

I'm curious, how did you proceed from the mono to dinitration. Did you cool then heat again or did you "surf the exotherm" ?

Also, it seems you have discovered molten picric acid. Good thing there's a huge margin between melting and decomposition point

ManyInterests - 12-12-2022 at 11:02

Quote: Originally posted by Herr Haber

Adding water at the end of nitration dilutes the sulphuric acid in which PA is very soluble especially at high temperatures.
The only "annoying" part in this synthesis is knowing that you are going to lose a bit of product while getting rid of H2SO4 / water. It's otherwise quite instructing.

I'm curious, how did you proceed from the mono to dinitration. Did you cool then heat again or did you "surf the exotherm" ?

Also, it seems you have discovered molten picric acid. Good thing there's a huge margin between melting and decomposition point

How I went from the mono/dinitration to the trinitration is following Rosco's instructions. After adding all the nitrate salt (sodium in my case) I kept stirring while heating it up to 120C and letting stay that way for around 5 minutes before letting the temperature go down (slowly) on the mantle until it hit 100 or so before putting in the water to crash it, then crashing it out in distilled ice cubes.

right now most of the water seems to have dropped, which means I hope that I have a good crop of picric acid this time around! My fourth synth will involve 75 grams of ASA to start. I will need to make sure I don't get a lot of foaming when I add the salt. But I think my beaker can handle it. The foaming went up to the 800ml mark (and it is a 1000ml beaker).

I will still need to squeeze out the water tonight. I've been cooking so my apartment heated up, if it was doing to drop more water, the picric would have done so now.

edit: I found Urbanski's Vol 2. Lemme look through it!

[Edited on 13-12-2022 by ManyInterests]

ManyInterests - 14-12-2022 at 19:40

OK this is not good. I think I am doing something REALLY wrong with all my picric acid synthesis. I think the problem is that when I was trying to boil down the mother liquor for more picric I realize that the stuff I was pulling out is really not something that should have been in contact with my picric acid. I think I have been working at this VERY, VERY wrong, and the entire month of work has been for nothing!

This is the third batch I made. It turned all of the paper it was on to a very dark color, almost black. This is consistent with acid and it was still very wet. I am confident it is wet with acid, not water.

My fourth batch's crude looked good, but I boiled down the remaining 1200 water (I am getting better at it, but that is still a little too much) and I got almost white crystals that I thought might have been picric, but it was REALLy acid and was eating through the paper. This is not good since I added it with the other crude picric (that did NOT burn through the paper filter) when adding it to the recrystalization. I hope it works out OK, I won't be boiling down any more liquid. This is not terrible. I really don't want to have wasted all this time and effort for another crummy batch of fake or super poor quality picric acid.

Edit: At least I am learning. Even if it means a lot of time and resources spent on this. Making good picric acid is difficult. No wonder it replaced by so many other stuff.

IMG_20221214_222832655 - Copy.jpg - 1.1MB

[Edited on 15-12-2022 by ManyInterests]

B(a)P - 14-12-2022 at 20:29