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bonnsgeo
August 4th, 2001, 11:00 PM
sorry , its maybe stupid but: i see everywhere that we cant make RDX with a nitric acid under 95 / 99 % (approximatively) ... WHY ? can you give me an answer ?? i did not found any explanation on the forums !
i have 58 % nitric acid is it really impossible to make RDX ??

bye
please give me an explanation !

mongo blongo
August 4th, 2001, 11:19 PM
I was thinking of asking that very question!
From what i can gather it is the water that must cause the reaction to fuck up. There must be no nitrogen oxides because when distilling nitric acid ,the presence of nitrogen oxides means that the HNO3 has decomposed into nitrogen oxides and water. So after all it is the presence of H2O from what i can see is the problem!
I don't know why but i can guess.
Maybe that one of the intermediate products is insoluble in water? so it makes it harder to react?
Maybe the water "water ligans" are being more attracted than the HNO3?
I dont know.

cutefix
August 5th, 2001, 02:18 AM
Preparing nitramine explosives require concentrated acids,preferably above 98%.Less concentrated acids are inefficient and promote undesirable side reactions .One of the prerequisites of this nitration is the removal of water from the reaction for better performance of the nitronium ion.As you will see majority of nitration of explosives require mixed acids for the same reasons(absorb water formed as nitration by product which will affect the nitration efficiency).Sulfuric Acids,Acetic anhydride,phosporus pentoxide have dehydrating ability.Nitroglycerin,nitrocellulose,picric acid,TNT used a blend of H2SO4/HNO3.RDX and HMX use acetic anhydride and nitric acid . There is even the use enriched nitric acid containing 5-20% nitrogen pentoxide,which is superior to pure nitric acid in nitrating capability.These method is currently being applied in the manufacture of higher yield of RDX and HMX(approaching 99% of theoretical)..Therefore if you only have lower acid concentration you should try to purify it,or make explosives that doesn’t need strength such as Urea nitrate and monomethylamine nitrate.

Lagen
August 5th, 2001, 07:34 AM
If nitric acid is the only acid in the solution, it exists in the form NO3(-)H+ and N(O3)(-)H(+). Concentrated HNO3 has the structure NO2.OH and NOH.O2. This is called pseudo-acid and is capable of nitration and esterification, while the dissociated acid is chiefly an oxidizer. Addition of water increases concentration of dissociated acid (NO3(-)H+). The mixed acids: Of course the aditional H2SO4 will "absorb water", so will anhydrides (acetic, nitric etc.). But, in mixed acids, this is further protonated to the nitracidium or hydronitracidium form: NO2.OH + H2SO4 -> NO(OH)2(+) + HSO4(-), or NO2.OH + 2 H2SO4 -> N(OH)3(2+) + 2 HSO4(-). Therefore I must disagree that nitronium ion plays any significant role here. Nitronium ion occurs only in solutions where HNO3 is far outpowered by another acid (like the sulfuric acid/nitrate mix) KNO3 + 2 H2SO4 -> NO2(+) + 2 HSO4(-) + K+ + H2O.

The nitrolysis of hexamine is a complex process. Look into an explosives technology book, the formulas will take up at least two pages. But the basic idea is very simple: as cutefix said, it's the "side reactions". In this case, it's basically oxidation, or burning. Manufacture of urea nitrate is a neutralisation reaction, so any concentration HNO3 will do, as long as you can separate the product. For making fulminates, 65% or even 60% HNO3 will suffice.

Bitter
August 5th, 2001, 07:49 AM
Not to mention the fact that the reduced nitric concentration slows the reaction down to a point where next to nothing is produced.

Don't try to use sulphuric acid to dehydrate the nitric whatever you do- it won't work with RDX.

Lagen
August 5th, 2001, 10:14 AM
The point where next to none RDX is produced (only byproducts) in the N-nitration process is 80%. A concentration lower than 70% will always result in complete oxidation of the hexamine. In this case, when I add hexamine to the nitric acid, white smoke is given off and the mixture turns yellow. I call this a "burnout".

bonnsgeo
August 5th, 2001, 01:06 PM
thank you for your answers !

Tony Montana
August 5th, 2001, 08:34 PM
Take this advice from a hard-headed bastard, that did not listen:
Despite all the warnings, I decided to make RDX with 70%HNO3+C6H12N4. My 70% nitric acid was clear and red fumes would come off it, when it was exposed to air. I thought maybe it would take longer and may have reduced yields.Heres what happened:
A 100ml beaker was washed and I poured in the 70% nitric acid, and added 30% more. Then started to add very finely crushed hexamine, to add 55 grams of hexamine to the solution normally it takes around 10-15 minutes. It took over 3 hours for it to dissolve completely in 70% HNO3, as the hexamine would cake and float to the top, where I would crush it against the side of the beaker with my thermometer. The real trouble started when I heated the solution to 55*C, it resembled a train as the temperature was sluggish at the start but once I got it rising steadily it took over. The temperature hit 55*C and I removed from the heat, but the temperature continued rising, I quickly put it in an ice-bath, it continued rising. By this stage the temp was about 75*C and rising, producing a tremendous amount of red fumes, I dumped it! which stopped the reaction in its tracks. What little solution that was left in the beaker, fumed and bubbled fiercly. If I had of waited much longer a hot acid solution would have sprayed everywhere. Including on me.
Outcome: You must use ahydrous HNO3
Preparation of anhydrous nitric acid Patent Number:3,981,975
http://www.rhodium.ws/chemistry/index.html

ALENGOSVIG1
August 5th, 2001, 09:09 PM
i have made RDX with 95% red nitric before. When the hexamine was added it bubbled and fumes were given off. Upon heating it got a little too hot and so i took it off the heat. temperature kept rising. I wanted to see what would happen so i placed the beaker on the picknic bench outside and got way back. It slowly settled down again and the rdx precipitated as usual. I got less final product than usual though.

bonnsgeo
August 6th, 2001, 07:37 AM
ok Tony montana !
thank you !
now i just have to find 95 % or more nitric acid because i have not a lot of material to concentrate it.

bye

Tony Montana
August 6th, 2001, 08:07 PM
If by material you mean lab equipment you should be right, with this one. You just have to purchase three chemicals, and it sounds like you already have HNO3. Now HNO3 forms an azeotrope with water at concentrations under 68%HNO3, so if you have 58% your going to have to concentrate it to 68% in a well ventilated area. By boiling 10% of the water off, the HNO3 will start fuming red vapors. At this stage you now need two chemicals, H2SO4 (Sulfuric acid) car battery's contain 25%H2SO4, and CH2CL2 methylene chloride, now this proves a bit harder to get and is a carcinogen so be careful(it is used as an industrial solvent with urethane, and some paint strippers). H2SO4 can be concentrated by boiling it, until white fumes start leaving it. HNO3 is poured into a long narrow glass jar, H2SO4 is then poured in and it is stirred. CH2CL2(methylene chloride) is then poured in and it is shaken, and left to seperate (the mixture seperates into CH2CL2/HNO3+H2SO4/H2O.
Take an eyedropper and remove the top layer and put it in a seperate container, the actual recipe is in the patent above.
The CH2CL2 lets the HNO3 freely bond to it reducing the HNO3's tendenacy to take any water with it. CH2CL2 is extremely volatile also, so if left outside without a lid it will evaporate in minutes. Leaving anhydrous HNO3,lab grade is 70% so you would have a real hard time actually purchasing anhydrous nitric acid. If you do make this nasty shit be CAREFULL!!! Its best to make it and go straight onto nitration, make sure you have enough safety equipment to handle anhydrous acid's.

10fingers
August 7th, 2001, 12:15 AM
*

[This message has been edited by 10fingers (edited October 25, 2001).]

mongo blongo
August 7th, 2001, 12:45 AM
This is a question that i don't really expect to get a solution to.But what the hell.
Is there any chemical that acts like H2SO4
for it's H2O absorbing capabilities which is easier to obtain/make than Acetic anhydride which do not destroy any RDX products or intermediates discluding the dinitrate of hexamine (coz it's easy to make with less concentrated HNO3).
In other words Dinitrate to RDX, need a H2O absorber!

Or

What about adding shit loads of AN to the HNO3 like the K process?
I don't fully understand the K process, I know the addition of AN is like making the HNO3 more concentrated but will this work
for more dilute concentrations of HNO3?

zaibatsu
August 7th, 2001, 01:41 AM
Calcium Chloride?

cutefix
August 7th, 2001, 03:40 AM
Why not try phosphorus pentoxide.It can convert even nitric acid to nitrogen pentoxide(nitric anhydride).It is not a restricted material I think.

[This message has been edited by cutefix (edited August 07, 2001).]

Tony Montana
August 7th, 2001, 07:38 AM
10FINGERS: I dreamed of using this method to produce 200ml, about 2 hours ago. I make sure it is done in a tall thin recepticle, so visibility of the two layers is better, and it is easier to collect. I do it outside so when the HNO3/CH2CL2 is collected I put it aside without a lid, the temperature would be about 22*C and 30 minutes later put the lid on and take anhydrous HNO3 in to my makeshift lab.
You raise an excellent point, maybe a more skilled chemist could answer as I have put a lot of thought into that question:In theory
HNO3+ CH2CL2+ C6H12N4= C3H6N6O6
will that work or will the CH2CL2 hinder the process in anyway, as 10fingers says the patent states nitrating, I think some aromatic compounds with HNO3/CH2CL2.

Demolition
August 7th, 2001, 08:06 AM
I am able to get 80% Methylene Chloride in paint stripper.Would this be a higher enough % to use in the procedure?
TONY:Have you tried to manufacture RDX yet using your Nitric Acid.If so how did it go?


------------------
Yeah,what up Detroit
Demolition

Tony Montana
August 7th, 2001, 08:26 AM
I got the H2SO4 last night, and concentrated HNO3 this evening. So I will be dreaming of about 1 1/2 ounces of RDX tommorow (if everthing proceeds smoothly http://theforum.virtualave.net/ubb/smilies/smile.gif)
Demolition, did you find out what the other 20% consisted of? Chances are I catch up with you tommorow anyways.

Hex
August 7th, 2001, 08:27 AM
Don't forget that sulphuric acid, acetic anhydride and P2O5 are not solely acting as dehydrating reagents in nitration, and are acting to produce, respectively nitronium ions, acetyl nitrate (controversial!) and N2O5 in situ. A good dehydrating reagent isn't necessarily going to do the business in a nitration.

bonnsgeo
August 5th, 2002, 06:55 AM
hi.

i d like to know: if i use EXACTLY the amount of h2so4 to deshydrate my nitric acid the mix wont be a real "sulphonitric" (with h2so4 in excess) mix so it could be used for RDX synthesis ... no ? :confused:
maybe the presence of so4(2-) will intervene in the reaction ? :confused:

thx
:)

<small>[ August 05, 2002, 05:56 AM: Message edited by: bonnsgeo ]</small>

Mr Cool
August 5th, 2002, 08:44 AM
No H2SO4 is acceptable in an RDX synth.

bonnsgeo
August 5th, 2002, 09:32 AM
mr cool , are u sure ? in my book, sulphonitric mixture are not good for rdx syhtnesis ... but the author dont say anything more ( the author is a great explosive french engineer so ... i believe what he write ! )

did you already successfully make rdx with sulphuric ??

bye

ALENGOSVIG1
August 5th, 2002, 02:33 PM
Anhydrous calcium nitrate can be used to absorb water during some nitrations. Ive used calcium nitrate with 95% nitric acid when i was out of sulphuric acid to make NG and i got good yeilds.

I wonder if calcium nitrate can be used in RDX synthesis?

Mr Cool
August 5th, 2002, 02:48 PM
Maybe Ca(NO3)2 or another solid dessicant could be used if you have 90% HNO3 for example, but with 70% HNO3 you would need so much to absorb the water that I think it would be impractical.

bonnsgeo: yes, I am sure (by "No H2SO4 is acceptable in an RDX synth." I meant "H2SO4 isn't acceptable in an RDX synth.", not "No, H2SO4 is acceptable in an RDX synth."!).

bonnsgeo
August 7th, 2002, 01:31 PM
I always see on this forum: "no h2so4 for rdx because it will detroy rdx" ..ok

..but could you explain me in detail the action of h2so4 on the rdx ?
(is it the ion so4(2-) wich destoy the rdx ?)
(i did a search, i didnt found anyhting precise)

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

pettingell
September 20th, 2006, 10:29 PM
Nitric acid (100%) that is free of nitrogen oxides can be made in the following manner: potassium nitrate (100g, 0.99mol) is added to a round-bottomed flask equipped with a distillation apparatus connected to open air via a calcium chloride filter. Sulfuric acid (98%, 53mL, 0.994mol) is added to the potassium nitrate and the mixture heated to nitric acid's boiling point of 83 degrees celsius. Allow the reaction to proceed until only a white cake of potassium hydrogen sulfate is left in the reaction vessel and the temperature has risen above 90 degrees celsius. the nitric acid product will be collected as a yellow liquid. Don't think that because its yellow its not concentrated enough. its that colour because it is highly photochromic and reacts with the light, however it will still perform the nitrolysis of hexamine very well. the nitrolysis of hexamine will proceed best at temperatures between 30 and 60 degrees celsius, provided that an ice bath is close by. if the temperature rises too quickly, the reaction becomes self-sustaining and can get out of control.

I don't know why sulfuric acid is bad for RDX, I've never actually used it in the RDX synthesis so I don't know what happens.

If the nitric acid is made in the above manner, no dessicant is needed. The reason why even a small amount of water fucks up this reaction is because hexamine is highly hygroscopic, meaning it dissolves in and absorbs water very easily. If the nitric acid isn't completely dry, then the hexamine will be dissociated by the water and the nitration won't work because the dissociation with water proceeds at a faster rate than does the nitration. the nitration of hexamine is actually quite a slow process, the initial fizz that happens when you first add the hexamine to the acid is the formation of an amine/polyalcohol by-product. the rate of reaction for the nitration is much slower and the heating step helps in completing the nitration step, given that nitric acid is in excess.

Best yields of RDX are obtained when the hexamine used is completely anhydrous. Hexamine can be synthesised by the surprisingly simple method of reacting formaldehyde with ammonia. simply use equal quantities of 20% formaldehyde solution and 10% ammonia and add the ammonia to the formaldehyde slowly, because the reaction is exothermic. after the complete addition, allow the mixture to sit covered at room temperature for 3 hours. after this, boil to dryness to isolate the COMPLETELY DRY hexamine.

The K-Process is one of those things where the guys who figured it out were fucking around with all sorts of stuff but had no idea what they were doing. the precise reaction mechanism for this synthesis is so far unknown. it is known that the ammonium nitrate and paraformaldehyde are undergoing some sort of reaction, since formaldehyde and ammonia, both present in the two reactants, are precursors to hexamine. the nitrate ions presumably come from the ammonium nitrate, however the role of acetic anhydride in this reaction is unknown, since both compounds are almost completely insoluble in acetic anhydride. I've found the best method for making RDX this way is this:

A mixture of 16g of ammonium nitrate and 3g of paraformaldehyde are slowly added to 27mL of acetic anhydride that has been heated to between 60 and 85 degrees celsius. the reaction vessel (a beaker) should be equipped with a magnetic or mechanical stirrer because this reaction needs constant consistent stirring. after the addition of the ammonium nitrate/paraformaldehyde mixture, keep heating the reaction mixture at the same temperature for 40 minutes and add more acetic anhydride a little at a time if its starting to dry up, but add too much and it scews everything up.
After 40 minutes of heating, ad 30mL of distilled water and this will form a precipitate. heat the reaction mixture until the precipitate dissolves and then allow to cool to room temperature and leave covered overnight. small needle like crystals should have formed, filter these off and wash with distilled water.
the yield of this reaction is considerably less than the direct nitration method in my experience.

In the nitrolysis/direct nitration of hexamine, only half of the hexamine molecule is used in the synthesis, while the other half is lost as a by product. I've been experimenting with ways of increasing the yield of RDX by adding different compounds. I've found that it is possible to obtain 2 moles of RDX product from 1 mole of hexamine reactant by the addition of methylene dinitramine. this compound isn't exactly available off the shelf, I was doing this under laboratory conditions, however there is a paper written by these guys back in 1949. here's the reference: W.E Bachmann and J.C Sheehan (1949) “A New Method of Preparing the High Explosive RDX.” Journal of the American Chemical Society 71: 1842-1845. 71 is the volume number while 1842-1845 are the page numbers.

I hope this helps all of you aspiring and promising organic chemists out there.

simply RED
October 8th, 2006, 11:13 AM
the nitrolysis of hexamine will proceed best at temperatures between 30 and 60 degrees celsius.

Rise slowly to 50-60 only after 5-10 minutes have passed at 20!
(highers the yield if NH4NO3 is used - use minute ammount of NH4NO3 only)

Pettingell, what method did you use to make methylene dinitramine?

pettingell
October 18th, 2006, 03:39 AM
simply RED, I've been doing more experiments and found that hexamine works just as well as methylene dinitramine but if you look up a Merck index the synthesis method for methylene dinitramine is in there. I was stuffing around with different synthesis methods because I'm doing my honours thesis in science on RDX.

cutefix
October 18th, 2006, 10:04 PM
Is there anything new to learn about RDX?:confused:
Your interest in using Medina as an alternative pathway remains an academic curiosity but have never been tried in practical synthesis.
The works of Hale, Wright,Bachmann and Sheehan, Lukasavage etc along these lines emphasizes a different approach in its synthesis although there was a brief mention of using methylened dinitramine.. as an intermediate....
This RDX is already a well studied material.....spanning a whole century...what else could you think, that you can contribute to the massive body of knowledge regardling RDX and its cousins?

nbk2000
October 19th, 2006, 04:45 AM
This is where the study of minutea comes into play.

A century ago you could have discovered an element.

Now all that's left is the discovery of the NMR resonance spectra of the fifth oxidation state of Dimethyl Mercury (or some other inconsequential BS).

Mega has ranted on this before.

cutefix
October 19th, 2006, 10:31 PM
:o I just remembered.....
Just a few years ago one energetic research laboratory in USA was reviewing the synthesis of TNT.... for the right environmental reason ...how to synthesize this already considered obsolete explosive in a much cleaner way...

A fresh insight about a material that is gradually decommissioned as an explosive filler/binder in military munition ....:cool:

gnitseretni
January 5th, 2007, 03:29 PM
I was thinking of asking that very question!
From what i can gather it is the water that must cause the reaction to fuck up. There must be no nitrogen oxides because when distilling nitric acid ,the presence of nitrogen oxides means that the HNO3 has decomposed into nitrogen oxides and water. So after all it is the presence of H2O from what i can see is the problem!
I don't know why but i can guess.
Maybe that one of the intermediate products is insoluble in water? so it makes it harder to react?
Maybe the water "water ligans" are being more attracted than the HNO3?
I dont know.

Wouldn't distilling at a lower temperature fix the problem? Say 50 C. The process will take longer that way, but it would keep the HNO3 from decomposing.