Ammonium Picramate for DDNP

[Microtek]

Well here I go again, another attempt at the elusive DDNP synthesis. But this time I have a few promising possibilities to explore; the first and perhaps least interesting is making nitrite of a better quality using a couple of new methods that I have tried out. I'll elaborate on this later, but at present I'll keep to the second new possibility:
Synthesizing DDNP without nitrite in 90 % yield. The method comes from a patent ( US 1460708 ), and will just outline the procedure here. 100 parts fuming nitric acid is placed in a beaker and covered with 200 parts of a paraffine oil such as kerosine.
40 parts ammonium picramate is mixed with 10 parts of an alcohol to act as a reducer ( to stop the picramate from being oxidized by the HNO3 ) and is added to the acid.
The mix is heated gradually until gas evolution stops, the acid phase is drawn off and is poured slowly into stirred water,which causes the DDNP to precipitate.
I assume ammonium picramate can be made by acidifying the sodium picramate soln from the reduction of picric acid to obtain pure picramic acid and then react the isolated compound with ammonia water. Now, does anyone know anything about ammonium picramate?

[Mr Cool]

This is a good find, since making picramic acid is EASY! I'll have to read the patent...
What exactly do you want to know about ammonium picramate? It can be made as you said, probably weakly explosive, flammable, decomposes in alkalis to release ammonia... but as long as we know how to make it then that's all that matters, right?

[kingspaz]

sorry if this is a dumb question (i'm tired again) but could picramic acid be further nitrated (the NH2)? like methylamine?

[Microtek]

I have made a batch of picramic acid and reacted it with ammonia and obtained a brown, very fine powder that is very insoluble. When I filtered the mix and then acidified some of the filtrate with HCl, no preciptate of picramic acid was formed as there should have been if substantial amounts of ammonium picramate was dissolved in the filtrate.
So, my question is if this low solubility is consistent with the properties of ammonium picramate. I haven't been able to find anything useful on the web ( except for an interesting book which might be worth purchasing - I found it here: <a href="http://www.cannonfuse.com/explosives/" target="_blank">http://www.cannonfuse.com/explosives/</a> ).

Kingspaz: If the NH2 group was substituted with NO2 I think you would just end up with picric acid again. Was this what you meant?

[Mr Cool]

I guess he meant to form -NHNO2. I don't see why it couldn't be done, but maybe someone who puts more thought into it could see a problem...

[Helos]

I use a process for making DDNP that first makes picramicacid(?)
I react a solution of picricacid with NaOH and after that add a solution of Na2S4.
When I do this, do I get Na-picramic acid or pure picramic acid.

If I get the Na-picramicacid, how do I do to get pure picramicacid instead.
BTW my yeilds of this was terrible when i tried it, I enden up with 0,2g (na?)-picramicacid from 6g picricacid.

[kingspaz]

basically do this to get picramic acid:
1. make Na2Sx solution by boiling an excess amount of S with NaOH.
2. to this add TNP.
3. this will make picramic acid. you then filter it and wash and its done.

the procedure i've seen in KIBC carries out the reduction of a nitro group on the sodium salt of picramic acid. the only possible reason i can see for this is that possibly the salt promotes reduction on carbon 2 or 6 some how avoiding rection on 4....maybe i'm talking crap....

also to get from the Na-picramate to picramic acid you simple need to add an acid which is stronger then picramic acid. so you could use HCl or H2SO4. this will result in the sodium salt of the mineral acid and picramic acid precipitation.

[Marvin]

Thats an interesting patent, but it seems to waste a very large amount of anhydrous nitric acid. Enough by my maths, to diazotise the picramic acid. have made the picric acid in the first place, and oxidise everything organic in the aqueos solution to carbon dioxide water and nitrogen. Unfortunatly there is no such thing in patents as quality control. If someone actually tries this, I would be inclined to proceed very carefully, the thought of runaway reactions looms heavily on the horizon but its the sheer waste that bothers me most.

There are aparently a lot of mild oxidising agents that will reduce picric acid, such as glucose. Sodium nitrite is not hard to make, makes me wonder why people are having trouble. Diazotizing is pretty trivial but its this stage you actually find out if any of the previos reactions have gone wrong.

[Microtek]

Marvin: Have you actually tried ( successfully ) to produce DDNP all the way from home made picric acid and home made nitrite ? It would be reassuring to know that somebody has actually done it, as it is indeed causing no end of problems.

PS. Using about 60 mL HNO3 to produce about 40 grams of DDNP may be wasteful, but it takes perhaps 2 hours and 0.05 dollars to produce 60 mL HNO3 and considering that 40 grams of DDNP is enough for 2000 detonators, I think the excess is acceptable.

<small>[ October 13, 2002, 07:56 AM: Message edited by: Microtek ]</small>

[Helos]

You mean that 0,02g is enough for a detonator, it seems way to little.
What are you planning yo use as base charge then??

Myself I was thinking of picricacid, but I dont know if it is sensitive enough. If not, I will use it itself, even if it ofcourse are "a little to valuable" to use by itself. That is ofcourse if I succeeds with making any DDNP at all. I think 1g will do a good singleloaded #8 cap considering the power of DDNP.

[kingspaz]

microtek i believe i got reasonable close using home made nitrite and home made TNP.
i finally, after many attempts (4-5) using varying methods, ended up with some sort of diazo compound. it looks a kind of lemonish brown and darkens in the sunlight. i initially thought it was DDNP but after drying it in a dessicator and then taking a match to some i was very disapointed to have it just bubble a little and burn smokeily.
then i gave up after wasting 45g of TNP and hours and hours of cooking and experimenting to get a successful method to prepare KNO2 in reasonable purity.
i think the problem is the reduction step. it has to be carried out on the nitro group on either carbon 2 or 6 and not 4. also it must only be reduced once on every TNP molecule not 3 times on one TNP molecule or similar reactions. there must be some way to reduce it only on the NO2 on carbon 2 or 6....
if anybody finds anything let me know i have an excess of TNP....around 100g <img border="0" title="" alt="[Eek!]" src="eek.gif" />
thats alot of yellow!

[Marvin]

Microtek, as it happens I havnt tried to make DDNP. At the time I made a fairly small amount of picric acid, now a long time ago, and I was rather unconvinced as to how pure it was. I used an asprin method with additional conc sulphuric. Lacking any suitable method of testing at the time I let it sit on a shelf. I will try it again at somepoint, and this time I will make a stab at DDNP. Ive also found methods of producing as solids a few more common aromatic diazo compounds, most of which are supposed to be explosive themselves. (Diazotize with an alkyl nitrite in alcohol then add ether to ppt).
Doubtless crappy initiators, but its not what I'm after.

Ive made reasonable quantities of nitrite from nitrate before, but again I have no idea how pure it was, just that it worked fairly well for what I was doing at the time. I need to revise some of my old experiments. I'm very interested in primaries as novelties / demonstrations, and secondaries only as far as the chemistry goes. Just a matter of personal preference. Benzene ring chemistry seems to follow much more rational paths than most of the rest of organic chemistry.

I would suggest anyone trying DDNP should test the quality of the nitrite they use first, then increase the amount used accordingly. Even if there is a lot of nitrate in the mixture it shouldnt interfere as long as the right amount of nitrite is also present.

[Microtek]

I've been researching a lot in the university library and found a book on diazotization methods and it seems that there are quite a few to choose from. A number of points were stressed, including:

- Reaction mixture must be acidic ( below about pH 2 ) during the entire process. This means that dripping acid into the Na-picramate/nitrite soln is probably not optimal.
- There must not be an excess of nitrite in the soln due to unspecified secondary reactions.
- HCl is preferred over H2SO4 due to being more effective.
- Temp must be kept at about 0-2 C for many diazotization reactions, though some diazo compounds are stable enough to endure up to room temp.
- At least about 2.5 mol acid should be used for each mol arylamine to ensure sufficient excess.
- Substance to be diazotized should be dissolved in the acid or in another solvent that is inert towards the reactants in order to ensure rapid reaction ( which is important because the products are unstable ).

Marvin: do you have a good way of determining the amount of nitrite in a nitrite/nitrate mix? I have had reasonable success making nitrite by reducing nitrate with lead; you just have to heat it to a much higher temp than is needed to melt the KNO3, and then mix the mass with a metal rod until all lead has been converted.
The nitrate/nitrite is extracted with hot water, the volume is reduced and the soln is cooled to 0 C to precipitate KNO3.

[Microtek]

I looked in Beilstein for a synthesis of picramic acid. Here is what I found:

-20 grams picric acid is dissolved in 300 mL alcohol and 125 mL conc ammonia ( soln in water presumably ).
-H2S is added at such a rate as to keep the temperature below 50-55 C.
-The produced ammonium salt of picramic acid is decomposed with dilute acetic acid to obtain the pure compound. Yield is 80 %.