Sciencemadness Discussion Board

Super explosives based on high nitrogen content salts

Dany - 15-8-2013 at 15:46

In recent years, high nitrogen content energetic materials (EM) have become popular among synthetic EM chemist for obvious reasons: high nitrogen content molecules have high heat of formation (very endothermic compound), very good detonation properties and their combustion/detonation yield primarily N2 gas which is harmless to environment. Also, energetic materials salts have much lower vapour pressure, higher density and better thermal/shock sensitivity than their molecular counterparts. Under the title "super high energy materials based on bis(2,2-dinitroethyl)nitramine" chinese investigators synthesize many high nitrogen content salts based on bis(2,2-dinitroethyl)nitramine (BDNENA). a very similar molecule to BDNENA is bis(2,2,2-trinitroethyl)nitramine (BTNENA). Although, BTNENA is a powerfull explosive (Dcj=8661 m/s, d=1.97 g/cm3) it turn out that this molecule is sensitive and possess poor thermal stability. The solution found by the authors is to replace one nitro group (in the trinitro moiety) of BTNENA, by hydrogen (forming dinitromethyl group). The hydrogen in the dinitromethyl group is highly acidic which mean that the new molecule (BDNENA) can react with high nitrogen content bases to form salts. The cations used by the investigators range from simple ammonium cation to 3,4,5-triamino-1,2,4-triazolium moiety. The most dense (molecule 4, in the article) and energetic (molecule 7) salt is obtained when the cation is an aminoguanidinium derivative. Calculation using EXPLO 5 thermochemical code predict (based on measured density and calculated heat of formation) a Dcj=10004 m/s and Pcj= 462 Kbar. With this detonation properties molecule 7 (see article) is superior to HMX and CL-20. also, drop weight impact test reveal that most synthesized energetic salts are less sensitive than well known HMX, RDX and CL-20. What is annoying about the new energetic salts is their poor thermal stability (decomposition temperature ˂142°C). What is more disturbing is why the authors didn't make the detonation performance test (e.g., cylinder expansion test) instead of predicting them? The molecules in the article are facile to synthesize with very good yield. I think experimental detonation performance should be done on molecule 7 to reveal more of it's outstanding performance.

Dany.

Attachment: super high energy materials based on bis(2,2-dinitroethyl)nitramine.pdf (763kB)
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Microtek - 16-8-2013 at 00:48

Good find Dany.

I think that the authors probably didn't have access to a facility where they could do experimental detonics tests. Considering the reported amounts that they synthesize, they are likely only authorized to produce very small amounts (I know that that was the case when I did my thesis on energetics).

Dany - 16-8-2013 at 00:58

Hello Microtek,

i know that it is difficult to test all new synthesized energetic material, but as molecule 7 in the article possess very high detonation (exceed 10 km/s) i think that a cooperation between lab should be done. Unfortunately, until now (2 year after the publication) nothing appear in the literature dealing with experimental detonation performance of molecule 7, which keep me skeptical about the results cited in the article.

Dany.

Microtek - 16-8-2013 at 02:49

Maybe we could test it. As far as I can see, the most problematic thing would be the triaminoguanidine. IIRC, someone on SM used an oscilloscope to measure VOD some years ago and got fairly plausible results....

Dany - 16-8-2013 at 03:23

As you know Microtek, detonation velocity is only a small part of the whole story on energetic material potential. The most important thing, is to crystallize these explosive so it can be possible to make x-ray diffraction to calculate density. the authors in the article measured density in a gas pycnometer. The density measured by gas pycnometer may differ from the result of x-ray diffraction. one example is the explosive NEST-1 synthesized by Chavez et al. Chavez (Angew. Chem.2008,120, 8431 –8433) reported a crystal density of 1.917 g/cm3 (x-ray diffraction) while the reported density by Oxely et al. (Propellants Explos. Pyrotech. 2012, 37, 24–39) is 1.82 g/cm3 (gas pycnometer). I don't think that measuring detonation velocity will be a big challenge if one could synthesis a new energetic material, the Daurtiche methode give reliable results.

The cylinder expansion test will show all the potential of a new EM. In this test detonation velocity can be measured along with metal pushing ability of the explosive. also, the coefficient of the JWL equation of state can be deduced so as to explore the isentrope along which the detonation products are expanding.

Dany.

Praxichys - 16-8-2013 at 07:04

Triaminoguanidine nitrate can be synthesized from guanidine nitrate in a straightforward reaction with aqueous hydrazine. Engager, among others, has synthesized guanidine nitrate in decent yield. The addition of hydrazine with time and heating (IIRC ~90C) yields mono-, di-, and triaminoguanidine nitrate based on the molar ratio of hydrazine to guanidine nitrate. Triaminoguanidine is insoluble in simple alcohols, so if the reaction is carried out in EtOH, it will precip. as TAG-HNO3. (See this patent for more inforomation. I will dig for more literature after work.)

Dany: would you happen to have access to the "literature procedures" they refer to in this paper regarding the specifics of the synthesis of BDNENA? Should be refs 19-21 at the end of the paper.

I have already done much work on aminonitroguanidine nitrate as an "upper class" energetic (Dcj of 9750 ms-1, Pcj 419 Kbar, d=1.905 g/cm3, Klapötke, EXPLO5) and that has brought me through a great deal of amino- and nitro- guanidine-based compounds. I therefore have great interest in this new compound based on its apparent ease of synthesis with regard to materials I already have. I can definitely help with the scaling-up of this synthesis as well as some performance measurement.

In the spirit of ridiculous acronyms, we could call this "Bis(triaminoguanidinium) Bis(2,2-dinitroethyl) nitramine" BTAG-BDNENA... hilariously enough, an anagram of "Bad Bang Ten" which refers to its (theoretical) 10km/s VoD... BB10 for short. :cool:

[Edited on 16-8-2013 by Praxichys]

AndersHoveland - 20-8-2013 at 11:39

The chemistry of the dinitromethyl moiety in BDNENA forming salts is no doubt analogous to trintromethane and its nitroformate salts. There are of course several other potential ways of stabilizing geminal dinitro groups besides forming a salt, but I will not go into that here. The structure of BDNENA is quite similar to another (toxic/corrosive) energetic compound, bis(2-fluoro-2,2-dinitroethyl)nitramine.

I would imagine that 5-aminotetrazole nitroformate would be more energetic and much simpler to prepare, and probably be a bit more chemically stable too. The advantage of these BDNENA salts may be somewhat higher density since +2 cations and -2 anions tend to pack closer together in the crystal lattice.

I would also like to point out that 1,5-diaminotetrazole does exist, and a BDNENA salt of this would probably be very powerful. Unlike hydrazine, diaminotetrazole is not a reactive reducing agent, so that would also help reduce sensitivity too (compensating for all those less stable nitrogen-nitrogen bonds).

5-aminotetrazole nitroformate would, however become much more dangerously sensitive in the presence of contaminating acid or alkali. Lower pH could free the stabilized nitroformate anion as trinitromethane, whereas high pH could hydrolyze the stable tetrazole ring into an unstable azide group.

[Edited on 20-8-2013 by AndersHoveland]

Dany - 20-8-2013 at 15:13

Reply to AndersHoveland,

5-aminotetrazolium nitroformate is an interesting EM molecule. In fact, this salt has been the subject of a chinese theoretical study last year. Unfortunately, the paper is published in chinese language but the abstract is in english and is enough to understand the important findings. Here's the abstract : "The structure and properties of 5-aminotetrazolium nitroformate were studied using quantum chemistry method. The density, heat of formation, detonation velocity and pressure were calculated. The calculated density was 1.93 g/cm3, and the detonation velocity and pressure were 9.47 km·s-1 and 38.82 GPa, respectively. The detonation properties were better than those of TNT, RDX, HMX". So according to this study, 5-aminotetrazolium nitroformate is inferior in term of detonation performance and density to the proposed salts of BDNENA. The first thing that popped in my head is to use dinitramide anion instead of nitroformate owing to it's lower carbon/higher nitrogen content. 5-aminotetrazolium dinitramide has been synthesized by Klapotke et al. The reported crystal density of 5-aminotetrazolium dinitramide is 1.856 g/cm3. The calculated detonation performance using EXPLO5 thermochemical code is Dcj=9429 m/s and Pcj= 384 kbar. so the nitroformate and nitramide are equal in detonation performance. 5-aminotetrazolium dinitramide is 3.5 time more sensitive than RDX towards impact stimulus and decompose at 117°C, making him basically a primary explosive. I performed a theoretical calculation to obtain the crystal density of both compound cited above using the group additivity group method of Kotomin et al. For the 5-aminotetrazolium nitroformate dadditivity group= 1.880 g/cm3 versus dDFT= 1.930 g/cm3 (so deviation=2.6%), for the 5-aminotetrazolium dinitramide dadditivity group= 1.850 g/cm3 versus dmeasured= 1.856 g/cm3 (deviation=0.32%). I have the feeling that the DFT method overestimate the density of 5-aminotetrazolium nitroformate. Although the DFT computational method is in general more reliable than the group additivity group (or other purely empirical method) for estimating density, i've seen example from the literature where the DFT method deviate significantly (as much as 0.1 g/cm3) from measured crystal density while the empirical method give more reliable results.

Just a few remark on a topic you make earlier under the name "Strategies in Designing Ideal Explosives". when you say :"Amino groups can often act as electron donating groups, making explosives less sensitive. The hydrogen bonding in amino groups also greatly increases intermolecular attraction, leading to higher densities." i found this idea vague. what must be said is" amino group increase stability by their delocalized lone pair when they are present in aromatic or conjugated systems. In TATB for example there are extensive inter- and intramolecular hydrogen bondings leading to the formation of a 2-dimensional graphite-like crystal structure which enhance density and increase stability. TATB is known to possess high thermal conductivity which help the system to dissipate heat from a thermal or impact stimulus and to decrease the chance of increasing the local temperature and formation of hot spot that will lead to ignition and growth to detonation".

also when you say:"Another strategy that has been employed is designing molecules with strained bonds. Octonitrocubane is an extreme example of this. Strained bonds require less energy to break. There has been some experimentation with triangular rings, but such compounds are generally much less stable" i will tell you that the presence of strained bond lead to a positive heat of formation but not necessarily to sensitive compounds. I'll say that strain energy and sensitivity are correlated but not always related . Octanitrocubane has a high positive heat of formation (DH0= +670-724 kJ/mol, calculated by DFT) but according to Eaton who synthesize ONC the latter is not shock sensitive. On the other hand nitroglycerine a molecule without strained energy and a strong negative heat of formation (DH0=-370 kJ/mol, from NIST webbook) is highly sensitive. The reason is that sensitivity of an energetic materials depend on many factor not only one (e.g., physical state, particle dimension, trigger linkage etc...)

below i'll upload the paper of KLAPOTKE et al. for the the synthesis of 5-aminotetrazolium dinitramide along with other interesting salts and the paper that i used to calculate the theoretical density via group additivity method and the link for the chinese paper on 5-aminotetrazolium nitroformate.

http://www.energetic-materials.org.cn/hnclen/ch/reader/view_...

Dany.



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[Edited on 20-8-2013 by Dany]

Praxichys - 22-8-2013 at 05:53

I found an article which might detail an alternate synthetic method to BDNENA. This paper should explain in detail the synthesis of the dipotassium salt of BDNENA from "the condensation of the ammonium salt of dinitromethane with formaldehyde in potassium chloride."

http://link.springer.com/article/10.1007%2FBF00853379#

Bulletin of the Academy of Sciences of the USSR, Division of chemical science
February 1970, Volume 19, Issue 2, pp 329-332

Following chlorination to the dichloride, I wonder if this could undergo a Ter Meer reaction with KOH and KNO2 to yield bis(2,2,2-trinitroethyl)nitramine (BTNENA) or, further, tris(2,2,2-trinitroethyl)amine (TTNEA), which (if I get my chemistry straight) should condense with 3 equivelants of TAG-HNO3 to yield something potentially dense and energetic, and with a perfect oxygen balance.

EDIT: My mistake. TTNEA would be C6H6N10O18(CH9N6)3.

C9H33N28O18 in total for an OB of -4%. Still not that bad.

[Edited on 22-8-2013 by Praxichys]

Dany - 22-8-2013 at 06:00

for Praxichys,


Dany.

Attachment: Synthesis of bis-(2-fluoro-2, 2-dinitroethyl) nitramine and tris-(2-fluoro-2,2-dinitroethyl) amine.pdf (335kB)
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AndersHoveland - 22-8-2013 at 09:39

Quote: Originally posted by Praxichys  
I wonder if this could yield bis(2,2,2-trinitroethyl)nitramine (BTNENA) or, further, tris(2,2,2-trinitroethyl)amine (TTNEA)

powerful, yes, but trinitromethyl groups are not very thermally stable (unless it is in anionic form, nitroformate), incorporation of this group also tends to result in fairly high sensitivities.

Microtek - 15-10-2013 at 04:32

I have been working on these compounds for the past month or so. I synthesize ADIOL (2,2-dinitro-1,3-propanediol) via tris(hydroxymethyl)nitromethane --> 5-hydroxymethyl-2,2-dimethyl-5-nitro-1,3-dioxane by ketal formation with 2,2-dimethoxypropane, then to 2,2-dimethyl-5,5-dinitro-dioxane by oxidative nitration with NaNO2, Na-persulfate and catalytic potassium hexacyano ferrate. Finally I de-protect with cat. HCl in ethanol solution.

I'm confident in the pathway, at least up to 5-hydroxymethyl-2,2-dimethyl-5-nitro-1,3-dioxane since I have used that to produce NEST-1 and have verified the spectrum of that substance. The subsequent oxidative nitration proceeds as described in the ADIOL article.

However, when I then deprotect and subsequently deformylate to produce potassium 2,2-dinitroethanol I end up with a product that doesn't condense with ammonia as it is supposed to, according to the article.

So, my question is this: Does someone have specific reaction conditions for the deformylation step (from ADIOL to K-2,2-dinitroethanol)?
Alternatively, some other references to K-2,2-dinitroethanol production?



Attachment: Improved method for 2,2-Dinitro-1,3-propanediol.pdf (137kB)
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Dany - 15-10-2013 at 09:20

@Microteck

Well first you must be sure that you produced the potassium 2,2-dinitroethanol before saying that the Mannich reaction with MH3 didn't work. As i can see you have access to some sort of spectroscopic technique (NMR?) to verifie your synthesized product so it will be much better if you can characterize your potassium 2,2-dinitroethanol first. Now if you go back to reference [20] (KLAGER, 1958) in the article you will find in the introduction that the Mannich condensation of NH3 and 2,2-dinitroalkanol also yield the corresponding bis-substituted amine (it is cited as reference [1] in KLAGER, 1958). Unfortunately, i cannot get the full article right now. If you want to try the Mannich condensation between NH3 and 2,2-dinitroethanol try first to neutralize the potassium 2,2-dinitroethanol with H2SO4 according to [2]. Another way to get 2,2-dinitroethanol is directly from potassium dinitromethanide and formaldehyde according to [3]. For The deformylation of 2,2-dinitro-1,3-propanediol to 2,2-dinitroethanol see [4].

References

[2] Synthesis, 2007 , 13, 2009 - 2013.
[3] Journal of Organic Chemistry, 1963 , 28, 339 - 344.
[4] Journal of the American Chemical Society, 1954 , 76, 5124.

Dany.

DubaiAmateurRocketry - 15-10-2013 at 09:46

Quote: Originally posted by Microtek  
I have been working on these compounds for the past month or so. I synthesize ADIOL (2,2-dinitro-1,3-propanediol) via tris(hydroxymethyl)nitromethane --> 5-hydroxymethyl-2,2-dimethyl-5-nitro-1,3-dioxane by ketal formation with 2,2-dimethoxypropane, then to 2,2-dimethyl-5,5-dinitro-dioxane by oxidative nitration with NaNO2, Na-persulfate and catalytic potassium hexacyano ferrate. Finally I de-protect with cat. HCl in ethanol solution.

I'm confident in the pathway, at least up to 5-hydroxymethyl-2,2-dimethyl-5-nitro-1,3-dioxane since I have used that to produce NEST-1 and have verified the spectrum of that substance. The subsequent oxidative nitration proceeds as described in the ADIOL article.

However, when I then deprotect and subsequently deformylate to produce potassium 2,2-dinitroethanol I end up with a product that doesn't condense with ammonia as it is supposed to, according to the article.

So, my question is this: Does someone have specific reaction conditions for the deformylation step (from ADIOL to K-2,2-dinitroethanol)?
Alternatively, some other references to K-2,2-dinitroethanol production?



Im extremely interested in Nitrated Diol or polyol compounds, do you have more papers about them ?

Dany - 15-10-2013 at 10:05

@DubaiAmateurRocketry

Check this one:

http://www.sciencemadness.org/talk/viewthread.php?tid=25480&...

Dany.

Microtek - 15-10-2013 at 12:50
Quote:

Well first you must be sure that you produced the potassium 2,2-dinitroethanol


That is precisely my problem. I did have access to Raman spectroscopy when I was at university, but do not at present. For this reason, I am not at all certain that I have, in fact, synthesized K-dinitroethanol, especially since I haven't been able to find any solubilities or other useful data (except a melting point, which is not my first choice) that I could use in identifying the product.

I still have access to the university library, so I have acquired a lot of relevant references, some of which are included here. It just seems from the way the authors of these articles describe the synthesis, that it should be quite straight forward, but it doesn't seem that way to me.

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DubaiAmateurRocketry - 11-11-2013 at 10:04

What about the hydroxylammonium cation ?

Also according to the paper, BTNENA, the Bis(2,2-TriNitroEthyl)NitrAmine ? It has a good oxygen balance(+17%), a good density (1.97) might serve a potential oxidizer? However what does the 44% in the H50 mean ?

Praxichys - 13-11-2013 at 07:45

Quote: Originally posted by Dany  
Another way to get 2,2-dinitroethanol is directly from potassium dinitromethanide and formaldehyde according to [3].


Be careful with this one. I read in [11] Organic Chemistry of Explosives (Agrawal, Hodgson)
"The potassium salt of dinitromethane is a dangerous shock sensitive explosive and should not be isolated"

I am also working on this but I have even less access to analytical tests than you do. I think I have designed a good pathway but my gallon of nitromethane doesn't arrive until sometime later today. I hope to get to 2,2-dinitro-1,3-propanediol (ADIOL) tonight in two steps over 4 hours starting with the basic condensation of sodium nitromethanide and formaldehyde. There is a synthesis using an oxidative nitration route on this product in basic conditions involving silver nitrate which I think will work but I have been so far unable to come up with a plausible mechanism. It's like a double aldol condensation and it's confusing the hell out of me.

I will eventually try to isolate 2,2-dinitroethanol for a MP determination. (Provided it doesn't explode when I try!)

Does anyone have access to a literature value for this MP? I will try my CRC handbook when I get home. Google comes up with nothing... the MP of the potassium salt or 2,2-DNE itself would be immensely helpful. As with a lot of enegetic compounds, the MP might not have been published for a good reason...

Some other interesting compounds that might be worthwhile investingating along the way:

The dinitrate ester of ADIOL (2,2-dinitro-1,3-dinitroxypropane)
The nitrate ester of dinitroethanol (2,2-dinitro-1-nitroxyethane)

Here is another synthesis I found of both potassium dinitromethanide and ADIOL, the former in a 25% yield through apparently a Ter Meer reaction of nitromethane using chlorine.
Kdinitromethane.png - 602kB


[Edited on 13-11-2013 by Praxichys]

Dany - 13-11-2013 at 08:09

The melting point of 2,2-dinitroethanol is 2-3°C.

Check the last page of the atteched paper for more informations on 2,2-dinitroethanol and also 2,2-Dinitro-1,3-propanediol (mp= 139-140°C).

Dany.

Attachment: Preparation and Characterization of 2,2-Dinitroethanol.pdf (381kB)
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[Edited on 13-11-2013 by Dany]

Praxichys - 13-11-2013 at 10:29

Thanks, Dany.

I found an article explaining the method Microtek is using. I will be trying the older method using silver nitrate rather than the persulfate/ferricyanide. I do not have the full article, but I think someone here should:

http://pubs.acs.org/doi/abs/10.1021/jo00210a600

My method is from the attached paper (Hamel, Dehn, Love, Scigliano, Swift), SYNTHESIS OF 2,2-DINITROPROPANOL. STUDIES ON CONTINUOUS PREPARATION. Aerojet-General Corporation. 215.
Quote:
OXIDATIVE-NITRATION REACTION
The most convenient method for preparing gem-dinitro compounds involves the reaction discovered by Kaplan and Shechter in which treatment of the nitronate salt of a primary or secondary mononitroparaffin with silver nitrate and an inorganic nitrite in aqueous media gives the corresponding gem-dinitro compound and metallic silver:

RCH=NO2- + 2 Ag+ + NO2- -->RCH(NO2)2 + 2 Ag
R2C=NO2- + 2 Ag+ + NO2- -->R2C(NO2)2 + 2 Ag

The reaction, which has been termed an oxidative-nitration process, has been used to prepare a variety of primary, secondary, and functionally substituted dinitro-paraffins. The silver produced in the reaction may be separated and converted to aqueous silvernitrate by treatment with concentrated nitric acid; after pH adjustment of the resulting solution to pH 5-6, it is ready for re-use.

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This leads me to believe that the major condensation product between sodium nitromethanate and formaldehyde must be something like 2-nitro-1,3-propanediol, which is then given a gem-nitro group by the NaNO2/AgNO3 solution.

EDIT: Reading up on the Nitroaldol Reaction (Also sometimes known as the Henry reaction) on Wikipedia shows that nitromethane condenses with 1 eq. formaldehyde in the presence of an aqueous base to form 2-nitroethanol, which then undergoes the same reaction again with another equivelant of formaldehyde to give the 2-nitro-1,3-propanediol. Mechanism mystery resolved! (Also made some stoicheometric revisions to my synthesis plan!)

Major hindrances include "retro-Henry" reactions because all products are fairly soluble and all steps in the Henry scheme are reversible.

EDIT EDIT: Hot gazoobies, I was right! Straight from a file here on SM:

"The addition of two moles of formaldehyde to nitromethane by the Henry reaction gives di(hydroxymethyl)nitromethane"

Right on page 6! Damn, I love chemistry sometimes. Now I need to figure out solubility so I might be able to isolate that. Yet another interesting derivative could be 2-nitro-1,3-dinitroxypropane, basically the dinitrate ester mentioned in a post of mine above but with a single nitro group instead of the geminal pair... essentially nitroglycerin but with a nitro instead of a nitrate on the middle carbon.

EDIT EDIT EDIT:

Waiiit a minute... if one equiv. of formaldehyde is reacted with nitromethane, one should obtain 2-nitroethanol, per the nitroaldol (Henry) reaction. So why wouldn't one just stop there and proceed with the silver nitrate/sodium nitrite to react straight to 2,2-dinitroethanol? In the BDNENA paper, why did they bother continuing the condensation to ADIOL before hydrolysis with KOH? It appears that formaldehyde is simply lost in that hydrolosis step. Maybe there is an excess of formaldehde throughout the entire reaction to favor the products over the intermediates?

[Edited on 13-11-2013 by Praxichys]

Dany - 18-11-2013 at 02:29

Quote: Originally posted by Praxichys  
I found an article explaining the method Microtek is using. I will be trying the older method using silver nitrate rather than the persulfate/ferricyanide. I do not have the full article, but I think someone here should:

http://pubs.acs.org/doi/abs/10.1021/jo00210a600[Edited on 13-11-2013 by Praxichys]


here's the paper

Dany.

Attachment: Catalyzed Oxidative Nitration of Nitronate Salts.pdf (570kB)
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DubaiAmateurRocketry - 30-7-2018 at 18:39

This compound's data is probably false or faked, and its heat of formation is extremely high for a salt (this compound's heat of formation is higher than the bis-tetrazole based explosive TKX-50). The triaminoguanidine cation is indeed enegetic, okay, but even triaminoguanidinium nitrate have a negative heat of formation, BDNENA have some explaining to do to bring it all the way up to positive 620 kJ/mol.

The density is also highly suspicious. TAG is an extremely density-lowering cation.