5-ATZ(5-Aminotetrazole), the nitrotetrazolate ion and friends

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Azole-Based Energetic Salts, Chemical Reviews, Gao and Shreeve

Attachment: Azole-Based Energetic Salts, Chemical Reviews.pdf (1.6MB)
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@ Rosco I posted this reference a year ago and picked out a few do-able syntheses in it but it didn't stir up any meaningful response. Its a great reference, full of data and interesting ideas but some of the statements about methods of synthesis are wrong and you need to refer to the original papers (many of which I have requested through the references section).

Hope you get a better response!


@Boffis, are you talking about your post in another thread?
http://www.sciencemadness.org/talk/viewthread.php?tid=&...
I missed it but above is the article, since the reference was posted,
Dany sent me a link for the article, and then I reduced the file size enough for it to attach.

You were experimenting with the dicyandiamide, aka cyanoguanidine, so I thought the summary of interesting copper compounds I posted last week
http://www.sciencemadness.org/talk/viewthread.php?tid=&a...
may rouse your curiosity, with regards to the guanazole synthesis involving cyanoguanidine being boiled with hydrazine dihydrochloride. Given that in my improved hydrazine sulfate synthesis using pool hypochlorite and urea, there are modifications possible where the end product desired is not hydrazine sulfate, it had occurred to me that a modification might be chosen such as formation of methyl ethyl ketone azine, separating and hydrolyzing the azine with hydrochloric acid, and distilling off the MEK, leaving hydrazine dihydrochloride for use as a precursor for boiling with cyanoguanidine where the ultimate end product would be guanazole. It could of course also be possible to first obtain the hydrazine sulfate in the usual way and convert it to the hydrazine dihydrochloride using calcium chloride, filtering out the sulfate value and concentrating the filtrate in preparation for reaction with the cyanoguanidine.

Thereafter, the guanazole would be nitrosated by one method to the dinitrotriazole, or the nitrosation under Sandmeyer condition would provide the mixed result where half the product is dinitrotriazole and half the product is nitrotetrazole.

Cyanoguanidine is actually a slow time release nitrogen fertilizer which is sold as 66-0-0 and is stocked in 25kg bags but it is an obscure product probably not widely used or commonly found stocked because it is an expensive specialty product and special order ag product for professionals. One brand name is Guardian-DF for the cyanoguanidine crystals.
A bag of the stuff could set a golf course landscaper back a couple of hundred bucks easily, but hey golf is important

[Edited on 10-10- by Rosco Bodine]

http://www.youtube.com/watch?v=wu9Y1OCXXO0

Here's a vid of some of the NaCuNTZ i made. I think its behaviour in a detonator is the same as lead-azide. Difficult to detonate from a single spark. Since I have no visco at the moment I cant test a det with visco; only with a straw filled with blackpowder (but i cant get detonation, only some crackling.

Here are a couple of additional articles. These look familiar so they may have been posted before, but I haven't found where so here they are.



Attachment: Insensitive high-performance replacements for RDX, Klapotke ADA[1].pdf (926kB)
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Attachment: Green Pyrotechnics, A Chemists Challenge, Klapotke.pdf (842kB)
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[Edited on 17-10- by Rosco Bodine]

Just curious, what is the toxicity or LD50 of tetrazole compounds ?

5 aminotetrazole for example ?

If you want to learn more, please visit our website.

Quote: Originally posted by Axt  Nitrosation of diaminotetrazole. There was only five (prepared and isolated) structures in the scifinder database that had a string of 7 nitrogens, at least that I could see. Of which only two looked notably energetic, this being one and <a href="http://www.sciencemadness.org/talk/viewthread.php?tid=">this</a> the other.

Personally I wouldn't have a problem heating a small amout of Pb azide dispersed in a solvent to 100°C, unless it wanted to bump and splutter but that shouldn't be a problem with DMF. Patent SE precipitates Pb(N3)2 from Pb(NO3)2 + NaN3 at 90°C, a more extreme example is US which precipitates it from molten KNO3/NaNO3 at 225°C!! (Pb(N3)2's decomposition temp is >300°C).

[Edited on 13-6- by Axt]

It is possible to hang a nitro group there ?

We all know that a very important substance is Sodiumnitrotetrazole or NaNTZ! We can all make this easily from the acid salt of cuppernitrotetrazole. Just neutralize it with NaOH and distinguish the CuO leaves u a yellow solution of NaNTZ! Put a CuNO3 solution in it to get the NaCuNTZ....

But this is not the case. The obtained product (see my video http://www.youtube.com/watch?v=wu9Y1OCXXO0 ) is NOT suitable for using in detonators! It wont detonate simply by fuse! After reading a lot, I discoverd that this so called 'raw solution' of NaNTZ must be purificied. This can be done by evaporating the raw NanTZ solution and then extract the pure NaNTZ. BUT this proces is dangerous. After NaNTZ recrystalize from aceton it easily forms anhydrous NaNTZ wich is very very dangerous. There are some case where the stuff exploded without reason....

So, my idea: Slowly evaporate your raw NaNTZ solution, wich will give you the monohydrate of NaNTZ and some contamination. Then extract the NaNTZ with an excess of hot aceton. Instead of evaporating the stuf just pour it in distilled water. Then boil the water until the aceton is removed. Now you have the pure solution

Quote: Originally posted by snooby  

After NaNTZ recrystalize from aceton it easily forms anhydrous NaNTZ wich is very very dangerous. There are some case where the stuff exploded without reason....



Do you have a reference for this? I have never seen or heard of the the anhydrous coming out of acetone...


Quote: Originally posted by Davin   Quote: Originally posted by snooby  

After NaNTZ recrystalize from aceton it easily forms anhydrous NaNTZ wich is very very dangerous. There are some case where the stuff exploded without reason....



Do you have a reference for this? I have never seen or heard of the the anhydrous coming out of acetone...


Best reference until now

http://onlinelibrary.wiley.com/doi/10./zaac./ab...

Dany.

Thanks for the compliment Dany, I do believe that method of NaNT dihydrate synthesis to be the best one out there, with the addition rate and temperature control tuned perfectly to avoid microdetonations prior to the isolation in high yield of perfect crystals of the dihydrate.

But what I was wondering about was if there was a NaNT reference somewhere indicating the loss of hydration waters of NaNT during recrystallization from acetone as snooby has mentioned. I have never came across any mention of this, and certainly have not had it occur myself.


snooby: If your NaNT solution is coming out yellow you have a temperature control or pH control issue.

[Edited on 1-11- by Davin]

Davin, i want to take advantage of your presence to see what are the progress in TKX-50? does the team plan to perform in depth studies on this important HEDM like cylinder expansion test? i would like to know how it will perform in metal acceleration ability and if the Dcj prdicted by EXPLO5.05 is realistic. I also would like to know the value of the constant (alpha, beta, kappa and tetha) used in the BKW EOS in EXPLO.05 for performing detonation performance calculation in your articles.

Dany.

[Edited on 1-11- by Dany]

And what about my idea of putting the aceton/NaNTZ mix into water and let evaporate the aceton?? Then you avoid the step with working with the pure NaNTZ..?


Engager said......
And one more thing, BE AWARE that separation of NaNT from solution in acetone IS very dangerous, and i know people from sciencemadness forum who taken serious wounds and injuries during this process, when product spontaneously exploded during crystallization. This could be attributed to formation of very hazardous anhydrous salt, but that is not quite clear in conditions then that happened. So you must consider this proces as very dangerous and take appropriate safety measures/precautions. I'm persistently encourage you to leave separation of pure solid compound and use it only in form of pure AQUEOUS solulitons, prepared by separation of Cu salt and reaction with corresponding ammount of sodium hydroxide (and heat/filtering as written). Remember, clever people learn from mistakes of others, stupid learn on their own. Be smart and cautious, and you will be alive long enough and still be in good health to tell about your beautiful chemical adventures



Btw: a solution of NaNTZ SHOULD be yellowish.. right

Okay today i did it again! I made a solution of (so called RAW) NaNTZ out of acid CuNTZ. You can use this solution to make AgNTZ yes, but no, it will not be pure. You can also make NaCuNTZ (the famous primer) from it, just by puting an solution of CuNO3 in some raw NaNTZ solution, boil it, cool it, filter it, done. See the youtube link for the raw NaCuNTZ! It is not suitable for detonators! In the video it looks like it is! But I need to put a flame against it for like 1 second, and that is just too long. In a det, it wont work, all because of the NaNTZ solution whas RAW.

://www.youtube.com/watch?v=wu9Y1OCXXO0

Today I boiled the raw NaNTZ solution on a waterbath, until cristals apeared. This is your NaNTZ, but with a lot of junk in it. I trew hot aceton over it and decanted the aceton, which turned yellowish. Evaporating the aceton can be dangerous because of anhydrous NaNTZ can form (I red this and also Enger confirmed it.) And btw,,, I had an accident with 200 mg, blowing my eardrums.

So after the aceton dissolved the NaNTZ, there still was a lot of undisolved stuff in my glass. This shows that the NaNTZ solution whas deffinitly not pure! All the stuff that doesnt dissolve is not NaNTZ, and this stuff makes the NaCUNTZ not suitable for detonators of course.

So then I putted the aceton into water, and let the aceton evaporate. After there were no signs of aceton I got a yellowish solution of Pure NaNTZ! I tested this and made some NaCUNTZ and AgNTZ with, wich shows clear colores. Its drying right now, and I will post the results of it! I think this is an safe method of making pure NaNTZ solution, amen

Quote: Originally posted by Dany  I also would like to know the value of the constant (alpha, beta, kappa and tetha) used in the BKW EOS in EXPLO.05 for performing detonation performance calculation in your articles.



version: alpha: beta: kappa:theta
5.03: 0.5:0.176:14.71:
5.04: 0.5:0.96:17.56:
At home right now and cannot find 5.05 or 6.01 yet. Will let you know.

Davin, i'm very grateful to you for providing me this informations.

So the version 5.03 (i think this is the first version) of EXPLO5 uses the sets of constant of the well known BKWN which is published by M.Suceska. In his paper [1] M.Suceska compared the BKWN output to other well known BKW EOS variant (BKWR, BKWS and BKW TNT/RDX). Suceska found that BKWN give the best overall agreement between the calculated and experimental values of detonation parameters.

[1]M.Suceska, EXPLO5-Computer program for calculation of detonation parameters (in International Conference of ICT Held in Karlsruhe, Federal Republic of Germany on July 3-6, . Energetic Materials: Ignition, Combustion and Detonation)

http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefi...

Dany.




[Edited on 3-11- by Dany]

I only have experience with NH4NTZ, but my experience is similar to snoobys.

I made NH4CuNTZ, als well as NH4NiNTZ.

Both perform nicely, stunning - once you get em going

They are both very stubborn to ignite via flame, almost impossible. The only viable setup for me was putting a thermite layer upon the copper salt - the nickel salt failed even with that.


Am I the only guy experiencing this problem?
Does somebody have an opinion on that?

@ Gargamel: The NaCUNTZ is very powerfull but not easy to use in detonators indeed! Not flamesensitive enough! Can you please explain which kind of thermite you are using!? And how you use it in a det? Must be a metal cap right?

The silversalt I made with my pure NaNTZ is very flamesensitive but also very impact-sensitive, so I dont want to use the silversalt! Also sent you a PM!

Gargamel: for the best peforming/most flamesensitive NaCUNTZ:

- Reflux the NaNTZ and CuNO3-solution! Or at least boil it. The liquid must get colorless, if not, you added to much CuNO3 for the amount of NANTZ. So dont put to much CuNO3 (its difficult to calculate the amount of NaNTZ in your solution right). Afterwards, cool it and filter it. Then washing with ethanol and water of course.

- Raw NaNTZ solution is not enough, make it pure by evaporate the solution (not to fast).Do this in different steps! So for example portions of 30 ml NaNTZ solution. Then youre sure you dont have to work with more then 1 gram at most. When Crystals appears, put boiling aceton in it. The decant the hot aceton and put it in distilled water. Do this with al your portions. Then boil the solution to evaporate the aceton. Then let the NaNTZ further evaporate leaving you a really pure solution of NaNTZ.

- use distilled water and in the last step, make sure your NaNTZ solution is PH 4

[Edited on 4-11- by snooby]

Quote:
Can you please explain which kind of thermite you are using!? And how you use it in a det? Must be a metal cap right?

Simple iron oxide stuff. Only with pyro aluminium to make it sensitive. Maybe CuO or Bismuth based stuff would be better, but I don't like it anyway.
BP never worked.

I did not use it in any det, I find it useless. A primary should be fuse sensitive. The green primaries I tested aren't.


This whole thing was interesting for me because I wanted a primary insensitive to friction and ESD. And as far as I read myself through this whole thing, that applies only to the NH4 salts.





edit:
No metal cap, it was just a parallel wound paper tube, 6mm inner diameter, 1mm walls.
Confinement is not the issue here, like with mercury fulminate, HMTD and so on. If it ignites, DDT comes extremely fast, practically immediate. A small crumb maybe a millimeter long made a little crater in my working plate. Superb!
But before it went, I could push it around over the table with the flame of my little torch...

[Edited on 4-11- by Gargamel]

Witch synthesis did you use for your NH4NT? I'm interested in NH4CuNT as well, but I stumble upon the invest of bariumhydroxyde and such for the synth mentioned bij Engager, did you use the direct method with ammonia soln?
I've experience with AgNT, but I find it rather too sensitive to my tasting, its initiating propperties however are unbeatable IMO.

Quote:
Am I the only guy experiencing this problem?


Could it be something with purity of your reagents or purification steps in between synthesis?
I tried NaCuNT a long time ago and it was just like crackling when lit in a pile, in a cap it just didn&#;t do anything.
I always blamed myself for bad, or no purification of the 5-ATZ, CuNT, and NaNT between synthesis, after that I abandoned further research into it because reliability was a main factor.

Other thing that came to mind was too much energy dissipating thorough the mass before going high order.
I can&#;t remember if I tried loosely packed NaCuNT but it would need bigger confinement if it didn&#;t work I thought, raising scrapnell levels.
There is always a grey area around people going public with practical experience with this kind of stuff, even with lots of easy to prepare primairy&#;s and its synthesis to be found everywhere.

If thermite is a key factor to get it to work I would be very satisfied, giving up AgNT for thermite => NH4CuNT.

Hi,

Today I did some tests on the sensivity of NaCUNTZ. Blows with a hammer were positive, about 25% less sensitive in comparisson with dextrinated lead-azide but friction-tests almost were al negative. This NaCUNTZ is relatively flame-sensitive but not reliable in a detonator.. So, with the positive hammertests, I am sure my NaCUNTZ is the right stuff, however it is yet not suitable in a det.. I think this was the last time I've made NaCUNTZ.. (btw also made the purple Nickel-salt with it, was even worse!).

The AgNTZ however (yellowish Crystals) are interesting for in detonators, but they are quite sensitive. So, then I would rather stay with the Azo-Clathrate from Mr. anonymious then with the AgNTZ.



Well tickle me tweeters and bump my subwoofers
http://www.youtube.com/watch?v=O6kSEqnDoLE

<iframe sandbox width="640" height="480" src="//www.youtube.com/embed/O6kSEqnDoLE?rel=0" frameborder="0" allowfullscreen></iframe>

Quote: Originally posted by AndersHoveland  I think the most promisting energetic compound may be dinitromethyl tetrazole.
&#;Syntheis of 5-Dinitromethyltetrazole&#;, A. V. Shastin, B. L. Korsunskii, T. I. Godovikova, V. P. Lodygina. () Russia

The structure of this compound has resemblance to another well-described insensitive energetic compound, diaminodinitroethylene (Fox-7).

Dinitromethyl tetrazole is somewhat acidic and can form salts.

Measurements of the explosive properties of dinitromethyl tetrazole have not been reported, but I think it would have an excellent combination of explosive performance and stability.

The aromatic nature of the ring would stabilize the nitrogen atoms, while the two NH groups be electron-donating toward the geminal nitro groups, stabilizing them. Many energetic tetrazole compounds have lower sensitivities than RDX, and Fox-7, which also contains the gem-dinitro functional group, is roughly twice as resistant to impact as HMX.


[img]http://www.sciencemadness.org/talk/files.php?pid=&aid=[/img]


This thing is actually interesting. I got the papers down there.

Quote: Originally posted by The_Davster  http://onlinelibrary.wiley.com/doi/10./prep./ab...

"Dinitromethyltetrazole and its salts: A comprehensive study"

Paper in the uploads

And in the paper, the Di-ammonium cation of the Dinitromethyltetrazole, is it possible to use the nitronium cation ?

http://onlinelibrary.wiley.com/doi/10./poc./abstract





Attachment: Synthesis of 5-Dinitromethyltetrazole.pdf (235kB)
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[Edited on 7-11- by DubaiAmateurRocketry]

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As was pointed out earlier in the thread there has already been worked out at LANL a method for isolation of 5-nitrotetrazole that is analytically pure

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

The method of Gilligan and Kamlet was patented in US
http://www.sciencemadness.org/talk/viewthread.php?tid=&a...

quote: Ammonium nitrotetrazolate was prepared by diazotization of 5-aminotetrazole in the presence of excess nitrite followed by extraction as the tri-laurylamine salt and displacement by ammonia. Upon addition of stoichiometric amount of ammonium hydroxide, sodium nitrotetrazolate forms quantitatively and is analytically pure.

See US page 4 column 3 line 53 Attached

An idea was described previously for what may be an alternative method for conditions for the Sandmeyer reaction or for adjusting the reaction system thereafter to obtain a more easily filterable crystalline material, which in retrospect
may also be a useful intermediate for DBX-1.
http://www.sciencemadness.org/talk/viewthread.php?tid=&a...

It is possible that other low solubility salts of 5-nitrotetrazole may facilitate purification of the nitrotetrazole needed in pure form for successful preparation of cuprous nitrotetrazolate in the desired crystalline form. Or it may be found schemes for precipitating or decomposing the impurities and leaving the purified nitrotetrazole value in solution. Unreacted aminotetrazole impurity may be reduced by improvement of the nitrosation method.

Attachment: US Primary Explosives of Tetrazole Moiety.pdf (58kB)
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A spontaneous explosion of sodium nitrotetrazole dihydrate during drying has been reported. See page 8 of the attached document.

Attachment: ADA.pdf (1.1MB)
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To revisit the earlier aspect of an alternative route for isolation of the nitrotetrazole as a variation on the method of Gilligan and Kamlet see US attached

Attachment: US Ethylenediamine salt of 5-nitrotetrazole and preparation.pdf (767kB)
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Further refinement of the process for DBX-1 has been reported by Klapotke and others having parallel research.

Edit: Per request of the inventor presently involved in business negotiations related to the technology, a delay of discussion of some proprietary details of this technology is being effected. Respect for the inventors explains the edits and missing posts in this thread about process details for which discussion can wait awhile yet until the corporate attorneys are satisfied the art originators interests are secured. Putting a lid on this discussion for awhile until given the "all clear" to proceed with further discussion.

Sufficient to say the technology is in part originating from this forum. No more speculation about coincidental discussions and professional publications need be indulged about where the overlap occurs for amateur experimentalism and the formal literature and ongoing current research. For this forum we are already there and have been there awhile.

[Edited on 16-11- by Rosco Bodine]  Pages:  1  ..  12  13  14  15  16  ..  25

3.1. Synthesis and Chemical Structure Analysis

For the synthesis of energetic polymers functionalized by tetrazole heterocycles and/or azido groups, we used poly-(epichlorohydrin)-diol (p-ECH-BD) as the starting polymeric matrix representing an epichlorohydrin polymer with central butanediol units and terminal OH groups and structurally containing reactive functional chlorine atoms capable of being substituted. The p-ECH-BD polymer was prepared by the cation polymerization technique through the epoxy ring-opening of epichlorohydrin (ECH) by an initiating system based on boron trifluoride etherate and 1,4-butanediol (BDO). The polymerization process of ECH was effected under conditions of the activated monomer mechanism [23] that precludes side reactions of the formation of low-molecular cyclic products and provides the best control of molecular weight and polydispersity.

The common method for functionalization of polymer precursors by explosophoric groups is the reaction of nucleophilic substitution of reactive groups (chlorine, bromine, mesylate group) of the polymeric matrix [56,57,58,59]. Here, p-ECH-BD was chemically modified through the nucleophilic substitution by heating the mixed reactants at 130 °C in aprotic high-boiling solvent DMF, which dissolves quite well the starting polymer precursor&#;the sodium salt of 5-aminotetrazole and sodium azide. The concentration of the chlorine polymer in the chosen solvent, which makes sure that the reaction mixture is homogeneous and the polymer is not deposited by the reaction, was 20 wt.%. To enhance the nucleophilicity, 5-AT was employed in the salt form with Na+ cations (sodium 5-aminotetrazolate, Na5-AT). The substitution of chlorine atoms in p-ECH-BD by tetrazole heterocycles and/or the azido group was performed with a 50% excess of the corresponding reactant or their mixture. The degree of substitution reaction was maintained until the high-sensitive Beilstein test [60] showed no organic chlorine in the reaction mixture and until the characteristic signals of the chloromethyl moieties of the starting polymer were absent according to the 13C NMR and IR spectroscopic data.

Under the aforesaid conditions, the reaction of sodium 5-aminotetrazole and/or the azide ion with the starting polymer precursor took place towards the substitution of chlorine atoms, with an insertion of the respective energy-rich substituents into the macromolecule structure ( ).

Upon completion of the reaction between sodium 5-AT and p-ECH-BD (12 h at 130 °C), a p-GAT homopolymer containing 5-aminotetrazole heterocycles was obtained, with the degree of substitution of the halogen by aminotetrazole being 99.3%. The degree of substitution was measured from the residual chlorine content of the product by using an analyzer for total chlorine. The chlorine content of the target homopolymer was 0.17%. The polymer yield was about 52% of the theoretical possible. Proceeding from quite a high substitution of the halogen by the tetrazole heterocycles, the temperature&#;time nucleophilic substitution parameters employed in the synthesis of p-GAT were used for the preparation of the p-(GAT-co-GA) azide copolymers.

The 5-Aminoterazole compound and derivatives thereof are known to be capable of reacting with nitric acid to produce energetic salts in which the aminotetrazole heterocycle acts as a cation, while NO3&#; serves as an anion [61,62,63,64,65]. Such high-energy ionic salts offer advantages over non-ionic molecules because of a lower vapor pressure and a higher density [61,62,63,64,65]. Given this, for the structure to be additionally enriched with functional nitrogen&#;oxygen-bearing groups, the p-GAT homopolymer was subjected to nitration with excess concentrated HNO3 (65%). When reacted with the nitrating agent, a polymeric salt structure began to be formed in which the cation was the macromolecule bearing aminotetrazole moieties, while the anion was the nitrate anion (p-GAT-N). Moreover, the terminal OH groups of the precursor transformed into energy-rich ONO2 groups. The high-temperature synthesis promotes the progress of a side process associated with thermolysis of the aminotetrazole ring, leading to the ring-opening and formation of the azido form that occurs when 5-AT and its derivatives are exposed to high temperatures [66,67]. The partial thermolysis progress was evidenced by the presence of an exoeffect during the nitration, the appearance of IR signals in the region typical of azido groups and the small yield of the p-GAT-N product.

The p-(GAT-co-GA) copolymers of N-glycidyl-5-aminotetrazole and glycidyl azide were synthesized by simultaneously reacting the starting p-ECH-BD polymeric matrix with both 5-AT heterocycles as the sodium salt and sodium azide. The reactivity of the azide ion increased significantly when the azidation reaction was carried out in the presence of compounds that, when reacted with NaN3, generate hydrazoic acid salts that are much more soluble in DMF [68]. Concurrently with an improvement in solubility, such salts increase the reactivity of the azide ion [68]. In the synthesis of p-(GAT-co-GA) copolymers, we used mixed NaN3/NH4Cl as the azidizing system, which were taken in an equimolar ratio. A variation in the ratio of Na5&#;AT and the azidizing system allowed the copolymers to be prepared with a varied ratio of energetic moieties in the macromolecule structure, with a high halogen degree of conversion and a yield above 56% ( ).

Table 1

PolymerReactant Ratio, a
mmolElement Ratio, b
% molRatio of Isomeric Moieties, c
% mol.Mw dMw/Mn dYield, %Na5-ATNaN3GATGAN-1N-2 p-GAT (homopolymer).957..p-(GAT-co-GA)-.113.943.856..p-(GAT-co-GA)-.722.345.754..p-(GAT-co-GA)-.155.948.951..p-(GAT-co-GA)-.474.650.849..GAP (homopolymer) e&#;&#;.Open in a separate window

The high organophilic behavior of the synthesized polymers promoted a decline in their yield when they were treated with organic solvents during their isolation from the reaction system.

To evaluate the structural characteristics, thermal stability and density, we prepared azide homopolymer GAP as a reference sample via the nucleophilic substitution of the p-ECH-BD halogen by the NaN3&#;NH4Cl azidizing system under conditions reported in [23].

The structural characteristics of the resultant 5-AT-based polymers were characterized by a set of spectral techniques (NMR and IR spectroscopies) and gel-permeation chromatography.

depicts IR spectra of the starting Na5-AT and p-ECH-BD and of the synthesized polymers. Irrespective of the type of the energy-rich moiety (aminotetrazole heterocycles and/or N3 group, nitrate anion) that was incorporated into the starting p-ECH-BD macromolecule or underwent a chemical modification by nitration, the shape and frequency of symmetric vibrations of the ether link (C&#;O&#;C) of the polymeric backbone retained within the range of &#; cm&#;1. The characteristic bands of stretching vibrations of the CH- and CH2 groups of the glycidyl chain retained as well for all the synthesized polymers in the range of &#; cm&#;1. The presence of the said characteristic vibrational bands of the major bonds and groups of the polymeric chain evidences absent destructive processes of the macromolecule during the reactions of nucleophilic substitution and nitration. The absorption bands of stretching vibrations of the CH2-Cl bonds of the starting p-ECH-BD at 748 cm&#;1 show up only for the intermediates at shorter substitution reaction times. The IR spectra of the target polymers have no absorption band of chloromethyl groups, suggesting quite a high degree of substitution of the halogen by the corresponding energy-rich moiety.

For compounds p-GAT, p-GAT-N and p-(GAT-co-GA), the aminotetrazole heterocycles found in the structure corroborate the IR spectrum to have the most frequency-characteristic intense absorption bands of skeletal vibrations of the ring and the ring-related exocyclic NH2 group.

You will get efficient and thoughtful service from Boraychem.

The stretching and stretching&#;bending skeletal vibrations of the tetrazole heterocycles (NCN, NN, CN) appear near &#; cm&#;1, intermix with each other and exhibit several intense absorption bands in the ranges of &#; cm&#;1, &#; cm&#;1, &#; cm&#;1, &#; cm&#;1 and &#; cm&#;1 [29,44,47,53]. The most intense band among the listed ones is the absorption band near &#; cm&#;1, which is related to the C=N vibrations of the tetrazole ring [44,53]. The symmetric and asymmetric stretching vibrations of the amino group appear as intense and broadened absorption bands because of hydrogen bonding in the high-frequency region of &#; cm&#;1 and &#; cm&#;1, respectively [53]. The present signals of the NH2 group indicate that the nucleophilic substitution proceeded to incorporate aminotetrazole heterocycles into the polymeric chain over the endocyclic nitrogen atoms of the ring, not affecting the exocyclic amino group.

For the nitrated derivative (p-GAT-N), in addition to the skeletal vibrations of the tetrazole heterocycles, the IR spectra show characteristic intense absorption bands of the NO3&#; anion at cm&#;1, cm&#;1 and cm&#;1 [62,64,65], and characteristic vibrations of the ONO2 groups resulted from the nitration of the terminal OH groups of the starting p-GAT homopolymer: bands at cm&#;1, cm&#;1 and cm&#;1 [29,69,70].

The azido moieties in the structures of azide homopolymer GAP and p-(GTO-co-GA) copolymers are identifiable from the present characteristic stretching vibrations of the N3 groups appearing at &#; cm&#;1 [27].

The 13C NMR spectra of the resultant polymers ( ) show a resonance of carbon atoms of the glycidyl backbone and butanediol units: carbon atoms of the ester bond at 66.6&#;71.9 ppm (&#;CH2&#;O; 3, 4) and 76.2&#;79.3 ppm (&#;CH&#;O; 5), and central carbon atoms of the diol moiety at 25.9&#;26.6 ppm (&#;CH2&#;; 1, 2). The carbon signals of the chloromethyl groups (6) of the starting polymeric matrix (p-ECH-BD) near 44.7&#;47.6 ppm disappear completely following the nucleophilic substitution by the corresponding energy-rich moiety. The resonance signals of the carbon atoms located in the side chain and related to 5-aminotetrazole heterocycles (6&#;) appear in the spectra at 53.3&#;53.7 ppm (for p-GAT, p-GAT-N and p-(GAT-co-GA)).

The alkylation of 5-aminotetrazole in basic media is known to take place to furnish isomeric derivatives substituted on the heterocyclic N-1 and N-2 atoms [44,71,72,73]. The two characteristic carbon signals present in the 13C NMR spectra of the resultant p-GAT and p-(GAT-co-GA) polymers indicate two 5-AT isomers present in the macromolecule at 156.5 ppm (C&#;NH2; N-1 isomer 7) and 167.5 ppm (C&#;NH2; N-2 isomer 8) [74].

In the spectra of the nitrated p-GAT-based derivative, the carbon signals of the isomers are shifted upfield at 152.5 ppm (C&#;NH2; N-1 isomer 7) and 153.6 ppm (C&#;NH2; N-2 isomer 8) because of the ionic nature.

For the azide polymers (GAP and p-(GAT-co-GA)), the resonance carbon atom signals of the &#;CH2&#;N3 groups (6&#;) show up at 51.4&#;51.5 ppm in the 13C NMR spectra. The ratio of glycidyl triazolone and glycidyl azide units in the p-(GAT-co-GA) copolymers was estimated from the 13C NMR spectra of the corresponding samples. The results are summarized in .

Due to the polymeric nature of the target compounds, the proton signals of the polymeric chain units have a characteristic broadened appearance in the 1H NMR spectra ( ). The spectra of all the polymers retain proton signals of the glycidyl diol backbone and overlap over each other and are at between 3.30 ppm and 3.95 ppm (&#;O&#;CH2; 3, 4 and &#;O&#;CH; 5). The resonance proton signals of the central units of butanediol were documented separately at 1.52&#;1.55 ppm (&#;CH2; 1, 2). The proton signals of the &#;CH2&#; groups (6&#;) associated with the endocyclic N-1 and N-2 atoms of the aminotetrazole heterocycle, as well as with the N3 groups, show up in the range of 4.08&#;4.80 ppm (6&#;). Broadened by the hydrogen bonding, the proton singlets of the exocyclic NH2 group of the isomeric tetrazole moieties were resonating separately in the downfield for the p-GAT and p-(GAT-co-GA) polymers.

In that case, the proton signals of the amino group typical of the N-1 substituted isomeric tetrazole moieties are shifted downfield at 0.61&#;0.64 ppm relative to the respective proton signals of the NH2 group of the N-2 isomeric moieties: 5.99&#;6.01 ppm (NH2; N-2 isomer 8) and 6.61&#;6.64 ppm (NH2; N-1 isomer 7) [71,72,73].

The analysis data of the 1H NMR spectra of the nitrated p-GAT-N polymer are on par with the known results of the spectral analysis of the low-molecular counterparts, such as 1-methyl- and 2-methyl-5-aminotetrazol-4-ium nitrates [62,65], that have characteristic proton signals of the amino groups near 8.5&#;9.1 ppm. Because of the polymeric nature and the presence of hydrogen bonds, the proton signals of the NH2 groups (7, 8) and the protons of (7&#;, 8&#;) isomeric units of the p-GAT-N polymer were recorded as a single broadened signal at 8.9 ppm.

The ratio of the N-1 and N-2 isomeric moieties contained in the polymeric chain structure was determined from the ratio of the integral intensities of the proton signals of the corresponding amino groups in the 1H NMR spectra ( ). The isomeric composition of the corresponding polymer depends on nucleophilic substitution reaction conditions. Under conditions of no azidizing system (NaN3&#;NH4Cl) in the reaction mixture, the halogen was substituted in the polymeric matrix simultaneously on N1 and N-2 of the aminotetrazole heterocycle, whose proportion attained 57% (p-GAT), with the chain containing chiefly N-2 isomeric moieties. The insertion of the azidizing system into the reaction mixture and its successive increase during the synthesis of the corresponding p-(GAT-co-GA) copolymer were likely to promote an increase in the reaction medium basicity, thereby increasing the accessibility of the most basic reactive site in the 5-AT molecule, i.e., the nitrogen atom at the N-1 position of the heterocycle. That said, the portion of N-1 substituted moieties increased from 44% (p-(GAT-co-GA)-14) to 51% (p-(GAT-co-GA)-75) relative to the N-2 isomers.

The molecular-weight characteristics of the synthesized polymers were evaluated by GPC using an HPLC chromatograph equipped with a refractive index detector. Polyethylene glycol samples with the known molecular weights and a low polydispersity were utilized as the calibration standards. It is seen from the findings listed in that the molecular weight (Mw) of the polymers varied in a range of &#; g/mol and depended considerably on the 5-AT unit content in the structure. The p-(GAT) aminotetrazole-bearing homopolymer had the highest Mw. A decrease in the portion of aminotetrazole moieties from 86 to 25 mol% in the macromolecule structure resulted in a decline in the molecular weights of the p-(GAT-co-GA) copolymers from g/mol to g/mol. The GAP azide polymer containing no 5-AT units has a Mw of about g/mol. That said, all the polymers exhibit quite a moderate level of polydispersity (Mw/Mn): 1.19&#;1.45. The tendency towards an increase in the content of aminotetrazole moieties in the polymer structure (transition from GAP to p-(GAT-co-GA) and p-(GAT)) can be caused by increased intra- and intermolecular hydrogen bonding, typical of tetrazole polymers, and by enhanced self-association of molecular chains, while the amino group present in the tetrazole heterocycle only amplified these effects [75,76]. This is reflected in the GPC chromatograms: the chromatograms have a broadened appearance for the samples with a high content of aminotetrazole moieties.

It has been established from the results of spectral studies and GPC analysis that the reaction between the starting chlorine polymeric matrix p-ECH-BD and Na-5-AT and/or NaN3 under the used nucleophilic substitution conditions provides an insertion of aminotetrazole heterocycles and/or N3 groups into the polymeric chain in place of the halogen. The substitution of aminotetrazole for chlorine atoms proceeded at the N-1 and N-2 positions of the heterocycle, and the ratio of the isomeric moieties was dependent on the reaction conditions. The ratio of the structural elements in the single molecule and the level of molecular-weight characteristics of the polymers are controlled by varying the ratio of the starting reactants. A p-GAT-N polymer structurally bearing additional energy-rich moieties (ONO2 groups, NO3&#; anion) was prepared by nitration of the p-GAT sample. No variations in the polymeric backbone were observed during the chemical modification (nucleophilic substitution, nitration).

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