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Author: Subject: Separation (rdx, keto-rdx)??
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[*] posted on 18-12-2012 at 11:00
Separation (rdx, keto-rdx)??


i know that keto-rdx can recrystallized from ethyl acetate.

Is the rdx Soluble in ethyl acetate?

Because the method of preparation keto-rdx containing about 20% of rdx..
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[*] posted on 22-12-2012 at 22:48



This is my understanding of the methods used is acetone, I do not know the effect of the ethyl acetate.

In acetone at room temperature under 662 smaller solubility than RDX, so in this method of using acetone soaked separation 662 of RDX. Air temperature of 26 ° C to 30 ° C (air temperature should be based on different temperature solubility of RDX in acetone to determine the amount to take the amount of acetone), take 42 ~ 43ml acetone, placed in a 200ml beaker , 662 with the mixture of RDX adding acetone, stir a moment, standing on the step to dry one day. One day later, the majority of RDX dissolved portion 662 less dissolving, filtration, and the resulting filtrate was dripping dilution, precipitation of RDX. Dry the insolubles were obtained after the separation 662. Note 662 still contain a small amount of RDX, wherein part of a suction filtration 662 surface after evaporation of acetone, precipitation of RDX; another part of RDX was dissolved in acetone. But the amount of RDX has been greatly reduced, and has little effect on the purity or stability.
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AndersHoveland
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[*] posted on 23-12-2012 at 00:09


I think keto-rdx is much more soluble in water than rdx.

"keto" is not really the best term here, since it is technically an amide not a ketone.

[Edited on 23-12-2012 by AndersHoveland]
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[*] posted on 24-12-2012 at 12:45


One simple question: why do you want to separate these compounds? I think, they can be used together. To Anders: I've read that article, which you recommended on preparation of keto-RDX. It looks rather promising. It would be interesting to check if mixed acid (HNO3+H2SO4) can be replaced with sulfur acid + some salt of nitric acid. And may be replacement of urea by nitrourea will increase total yield of keto-RDX and RDX.



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[*] posted on 1-1-2013 at 21:29


I originally posted this in the thread "Why sulfuric acid can't be used to make RDX"

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

This paper talks about using HNO3/H2SO4 nitrating mix to first make Dinitrourea and then add Hexamine or HDN to the mix..
This affords a mix of RDX and Keto-RDX (K-6).
Can anyone verify this ?
I definitely would like to try the nitrate salt/sulfuric acid mix.




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[*] posted on 1-1-2013 at 23:07


Quote: Originally posted by Motherload  
This paper talks about using HNO3/H2SO4 nitrating mix to first make Dinitrourea and then add Hexamine or HDN to the mix..
This affords a mix of RDX and Keto-RDX (K-6).
Can anyone verify this ?

I have little doubt that this would indeed work, though I cannot verify it. Dinitrourea gradually hydrolyses in water, and between the hexamine and free nitramine floating around, there would be plenty of equilibrium.

However, the acids have to be very concentrated to get dinitrourea, even more than usual. Without going into the details, it can just be said that it is not as simple as some may think. The dinitrourea route may likely not be so practical.

Quote: Originally posted by caterpillar  

And may be replacement of urea by nitrourea will increase total yield of keto-RDX and RDX.

I think the nitrourea route has several advantages, and is probably the best in terms of highest yields.

Quote: Originally posted by caterpillar  

It would be interesting to check if mixed acid (HNO3+H2SO4) can be replaced with sulfur acid + some salt of nitric acid.

There are no chemical reasons why this will not work, but there are physical solubility reasons that tend to make such nitrations more problematic.

The different routes each have different advantages and disadvantages, in terms of product yields relative to each reactant. The details of most of this are already discussed elsewhere in this forum.
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[*] posted on 2-1-2013 at 14:20


Look, there was only one word in original Chinese paper about concentration of mixed acid. They used concentrated mix and I take it as if they used usual H2SO4, but no oleum. Well, nitration produces some water It means, that if they started with 98% H2SO4 (or 100%, but 98% is the usual concentration of so-called concentrated sulfur acid) same result can be obtained with mix of smaller concentration if one will use nitrourea instead of urea. This is important because usual concentration of sulfur acid, available in market is 92-94%. Mix 50:50 can be obtained without distillation. Ca(NO3)2 + H2SO4, for example. Or one may take mixture of H2SO4 + KNO3 (or NaNO3), to heat it and then to cool. Or dissolve NH4NO3 in H2SO4. In any event, if the method, described in aforementioned Chinese paper works, it gives us the way how one may prepare RDX using mixed acid.



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[*] posted on 4-1-2013 at 09:46


Theoretically, when a specific nitration reaction requires more concentrated nitric acid, 70% nitric acid can still be used, with a much greater ammount of concentrated sulfuric acid added to compensate. In reality, this requires increasing the proportion of sulfuric acid by several fold, and often just is not practical. At best it is very wasteful, at worst the high proportion of sulfuric acid can cause destructive dehydration in some reactions, leading to decreased yields. I think I remember someone in this forum trying to prepare dinitrourea with normal mixed acids, he failed. The salts of dinitrourea are very powerful themselves, it seems rather wasteful to be using dinitrourea to make keto-RDX. The first nitro group is much easier to add to the urea molecule than the second nitro group. It would be quite challenging to do this with normal mixed acids, but theoretically not impossible. As you mentioned, another strategy is to use add solid nitrate salt (NaNO3,KNO3, Ca(NO3)2, etc.) instead of the nitric acid, to minimise water, but it can be problematic to get these solid nitrate salts to dissolve in the sulfuric acid (these specific issues, and methods of dealing with the solubility problems, are discussed elsewhere in this forum).



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[*] posted on 4-1-2013 at 16:10


As I wrote, reaction with Ca(NO3)2 + H2SO4 DOES GO without problem as it goes between Ca3(PO4)2 (which is absolutely insoluble) and H2SO4. Moreover, I think (it is only my proposition, of course) that CaSO4 which precipitates during this reaction extracts some water and increases resulting concentration of mixed acid. The only one problem is to separate liquid and mess of tiny crystals of CaSO4, floating there (and this is why I used not thin powder of Ca(NO3)2 but small pieces 1-3 mm in diameter). Chinese boys wrote that they used concentrated mixed acid. If there was no oleum, described process probably can be realized with slightly lower concentration of mix too if one uses nitrourea instead of urea. I'd like to make this experiment, but it would be difficult now- all my reagents with lab equipment was leaved in my past live. Now I have only few gr of KMnO4 and large amount of NaCl. What a pity.



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