Sciencemadness Discussion Board - RDX synthesis

It can be done efficiently on industrial plant scale level, but for the amateur experimetalist the synthesis of the highly concentrated nitric acid is the bottleneck for most of the available methods. And the obtaining of acetic anhydride for the remainder of routes.

I agree in principal with your statements. Both of the components you mentioned are difficult to come by; however, it is my experience that NH₄NO₃ and H₂SO₄ are readily obtainable. With a decent sized distillation set and a few hours of time, acceptable HNO₃ is also obtainable. If my calculations of the K-process are correct, one would only need 250ml (371.2g of 95% concentration at 25C) of HNO₃ to produce a 90% yield of 588.8g of RDX. I think that is pretty good. Am I wrong?

markx - 26-5-2014 at 10:34

Quote: Originally posted by ethicalhacker

I think your calculations are a bit off on the bill of materials. I'm referencing to Urbanski regarding the K-method material balance and it figures out roughly as:

50g hexamine
480g AN
860g HNO3

to produce 100g of RDX

Take into account the materials needed to produce that amount of HNO3 by distilling and you will soon realise it is a lost cause in terms of any economy. And this is data for plant level yield....it can be less in an amateur setting. In fact whichever synthesis route you choose, the excpected yield will realistically hover in the 70% range......90% is unfortunately a pipe dream.

ethicalhacker - 26-5-2014 at 11:07

I think your calculations are a bit off on the bill of materials.

Agrawal and Hodgson report the following chemical formula for the K-process. This is the basis for my calculations.

C₆H₁₂N₄ + 2 NH₄NO₃ + 4 HNO₃ -> 2 C₃H₆N₆O₆ + 6 H₂O

Motherload - 26-5-2014 at 18:55

Shouldn't nitraamide condense with straight formaldehyde to produce RDX ?

markx - 26-5-2014 at 22:39

Quote:

Agrawal and Hodgson report the following chemical formula for the K-process. This is the basis for my calculations.

C₆H₁₂N₄ + 2 NH₄NO₃ + 4 HNO₃ -> 2 C₃H₆N₆O₆ + 6 H₂O

This equation reflects the summary ratios of reagents involved in the actual formation of the product...albeit in a rather simplistic manner, but that is not even important at this stage. What is important though, is the fact that one needs to involve a considerable amount of overhead reagents to drive up the yield and bind the formed water. In fact the ratios are 0,5/8,6 of hexamine/HNO3 by mass. This acid is recovered and reused in industrial setups, therefore the losses are negligible, but that will not be the case in amateur synthesis.

[Edited on 27-5-2014 by markx]

markx - 27-5-2014 at 01:25

On the note of E-method....I also performed a run with 4g paraform to 8g of AN to study the effect of a ratio that inclines towards excess paraformaldehyde. First observation seemed promising as the amount of preciptate formed was greatly increased (2g of yield after drying). But the vast majority of this precipitate was unreacted paraform, as it turned out afterwards on recristallisation stage with acetone.
I have to take a closer look on the quality of the anhydride before I continue with further experimentation involving catalysts. Perhaps the cause of all the failures is the degradation of the anhydride.

caterpillar - 27-5-2014 at 04:55

Quote:

Agrawal and Hodgson report the following chemical formula for the K-process. This is the basis for my calculations.

C₆H₁₂N₄ + 2 NH₄NO₃ + 4 HNO₃ -> 2 C₃H₆N₆O₆ + 6 H₂O

Use hexamine dinitrate instead of hexamine. Diluted acid later may be used for preparation of aforementioned hexamine dinitrate or urea nitrate for example.

markx - 29-5-2014 at 13:23

I conducted an E-method run with AlCl3 catalyst:

Half the amounts of chemicals were used in this test compared to the first one.
13,5ml of Ac2O was heated to 88C in the reactor and 100mg of anhydrous AlCl3 was added to it. Vigorous audible fizzing was observed for about 2 seconds. The Ac2O dissolved the catalyst and remained clear and uncolored.
Then 5,0g of previously dried AN was added to the preheated Ac2O. I decided to add all of the AN to the reactor to avoid the manual gradual dosing of both ingredients...turns out I should not have done it. Temperature in the reactor jumped to 100C and a vigorous reaction started with the evolution of NOx and a colourless gas. This was totally different compared to what was observed without the lewis acid catalyst: the temperature fell in the reactor every time upon addition of AN and no visible reaction was observed. The temperature started to fall after a couple of minutes and the evolution of gases seized. A considerable amount of AN had been dissolved/decomposed by visual assessment. After about 10 minutes the reactor temperature had fallen to 90C and the gradual addition of a total of 1,8g of praformaldehyde was begun. Immediately after the first additions of paraform the reaction began with strong evolution of gas bubbles and temperature rose to 92C. The additons of paraform were timed in order to keep the reactor temperature around 90C. Reaction was clearly more vigorous than without the catalyst, judging by the amount of bubbles formed. After approximately 30 minutes the additions were complete and reactor temperature was kept at 88C until the evolution of gas bubbles seized (about 30 min after the last addition of paraform). The fluid in the reactor was loaded with a flocculent precipitate and was milky white, a very slight yellowish coloration was observed. Without the catalyst the fluid in the reactor at the end of previous syntheses was distinctively greenish coloured and basically clear with only a very slight precipitate noted. The reactor contents were allowed to cool down for 15 minutes and thereafter crashed into 300ml of cool water. The precipitate formed was filtered, washed with water and neutralised with sodium bicarbonate solution. The yield is drying and I will report the numbers tomorrow, but it seems that the catalyst addition had a beneficial effect.

[Edited on 29-5-2014 by markx]

markx - 29-5-2014 at 23:09

Weighed the yield....0,5g before recristallisation. Seemed promising, but then I noticed a rather obvious smell of formaldehyde coming from the dried mass, not a good omen. Rather a hint to paraforaldehyde contamination. On top of that I managed to spill about 1/4th of the product onto the floor, damn butterfingers and sleep depravation. So I was left with 0,37g to perform recristallisation from hot acetone. And to my great dissapointment again a very considerable amount of precipitate remained undissolved. After drying I was left with a meager 0,15g of product.
I will try the synthesis with catalyst again, but this time with the gradual addition of both reagents. This may have a profound effect, as it turned out the AN on it's own gives a strong reaction on addition to the Ac2O with catalyst.
Since the E-method was practiced in industrial level at the plant "Fazan" in Bobingen Germany it should be possible to make it work with a reasonable yield. Although I tend to be suspicious about the process description being complete or precise. I think there might be some important details that have been lost in translation or were simply never leaked to the public or have been biased with intention. At the time of war the cyclonite production was a closely guarded secret and it is all too possible that the description of german procedures is somewhat incomplete and erraneous.
But it is a captivating topic with a rather enjoyable learning curve...i will keep working on it and post the updates with the kind permission of all the fellow mad scientists

Manifest - 2-6-2014 at 09:47

Does this reaction have to be absolutely clear of Nitrogen Oxides in the Nitric Acid?
If so, is there any way of removing the impurity after distillation?

caterpillar - 2-6-2014 at 12:19

Quote: Originally posted by Manifest

Does this reaction have to be absolutely clear of Nitrogen Oxides in the Nitric Acid?
If so, is there any way of removing the impurity after distillation?

Which in particular? If you mean direct nitration of hexamine, this process is sensitive to NOx. I failed twice, using freshly distilled nitric acid. But perhaps, I failed because of relatively large pieces of hexamine (tablets from drugstore). Neutralization of a base like hexamine is exothermic reaction. But when I used hexamine dinitrate, I had no problems. My nitric acid was yellow and became at nearly colorless after I had added the first portion of HDN.

Turner - 2-6-2014 at 14:56

More importantly it has to be water free

Manifest - 3-6-2014 at 09:55

This compound is too much of a pain to make.

ETN seems preferable considering they are almost equal in detonation velocities.

markx - 4-6-2014 at 00:22

Quote: Originally posted by Manifest

This compound is too much of a pain to make.

ETN seems preferable considering they are almost equal in detonation velocities.

Sure...if one just needs/wants a quick high yield batch of something to go off in a loud bang then heterocyclic nitramines are not the way to go.
I for a change enjoy a complicated synthesis...it poses a challenge to the intellect and makes the process more captivating.

caterpillar - 4-6-2014 at 01:44

Quote: Originally posted by Manifest

This compound is too much of a pain to make.

ETN seems preferable considering they are almost equal in detonation velocities.

The only problem with the classic route to RDX (or K-process, no matter) is the large amount of nitric acid. Many compounds may be prepared with the aid of salt of nitric acid plus sulfur acid- TNP for example. But if you make pure nitric acid, nitramines are the best way to use it. But there is a route to mix of RDX + keto-RDX, and this process was discussed at this very forum. This process looks rather simple and uses mixed acid- 50% : 50%, hexamine (dinitrate will be better) and urea. I was about to cry, reading description of this process. I had all necessary chemicals, when I was young, but wasted mixed acid for preparation of NC.

markx - 4-6-2014 at 02:21

Quote:

You can wipe away the tears as the 50/50 in keto rdx synthesis description only marks the proportions (by mass or molar ratio...I can't remember at the moment) of anhydrous HNO3 and H2SO4 (or was it even oleum).

As for the E-method I found an old article in polish language from Urbanski dated in 1948 and it states that the E-method had no practical value as there were numerous explosions during the syntheses if temperature was allowed to climb over the limit. Sadly no more information is given on the extent of the temperature limit or on any other parameter for that matter.

Please find the article attached:

Attachment: przemysl_chemiczny_1948_s487.pdf (864kB)
This file has been downloaded 852 times

markx - 12-6-2014 at 00:43

Now there's a new load of information on the inner workings of the E-method!
I'm really thrilled to find this source....seems that the low yields have a rather well established connection to reaction times. I deemed the 6 hour reaction time mentioned in Urbanski to the particulars of production facility, but it seems that there is an incubation time of several hours before any end product is formed.
Please find the articles attached:

Attachment: The reaction to form RDX from AN and praformaldehyde in AcO2.pdf (192kB)
This file has been downloaded 988 times

[Edited on 12-6-2014 by markx]

Attachment: IEC 40 1948.pdf (1.5MB)
This file has been downloaded 1178 times

markx - 13-6-2014 at 05:25

I just performed the final verification test for the recristallised E method product from my previous low yield syntheses.
0,6g of recristallised product was hand compacted into Al foil tube.
Initiated pyrotechically via 40cm visco fuse with 40mg of SADS + 50mg of loose recristallised ETN.
The detonation occurred with exceedingly satisfactory violence and the sound had a characteristic deep note to it. Metal pipe tobacco can that the charge was taped onto was torn and twisted in a rather apocalyptic manner. I think it is pretty safe to say that the product (in large majority) was RDX.

markx - 16-6-2014 at 04:29

Status update....I performed several long runs of the E-method on previous weekend to study the effect of long reaction times with and without AlCl3 catalyst on the yield.
Utter dissapointment to be honest...even with 12h reaction times it was not possible to obtain a pre recristallisation yield of over 15% calculated on paraform. Addition of AlCl3 in a concentration of 0,6% (calculated on Ac2O used) sped up the reaction rate considerably, but yield did not increase remarkably. Furthermore, it seems that prolonging the reaction time has no beneficial effect upon yield once all the reactants are consumed and the reactor liquor turns transparent. The E-method seems a low yield dead end....

On a brighter note I read through the Bachmann patent nr 2798870 and found a promising reference to the possibility of using 70% nitric acid in the synthesis....provided that an excess of Ac2O is present to account for the dehydration of the lower concentration HNO3.
After preliminary calculations on the need of Ac2O for a 10g yield (75%) of RDX via hexamine, I came up to the "not so frightening" amount of roughly 50g of Ac2O. Considering the fact that I have Ac2O available and that I can (theoretically) skip the hassle of distilling HNO3, I find it might not be such a bad combination. Provided that it really works the way it is planned...the patent does not provide an experimental example with lower concentration HNO3, but merely mentions that it is possible. Provided that the extra Ac2O does not have a detrimental effect on the reaction mechanism, it might all go well.
Using hexamine dinitrate the amount of Ac2O can be further reduced since less nitric acid is required in the synthesis. If my calculations hold water, then 32g of Ac2O is required with hexamine dinitrate+70% nitric acid and only 23g of Ac2O with dinitrate + 98% nitric acid for a 10g yield at an optimistic 75%.
But for preliminary testing I shall begin with straight hexamine, as I have that set of reactants available and I can skip any further hassle of making the precursors. If the concept with hexamine and 70% HNO3+excess Ac2O via Bachmann route shows promising results, then I may consider trying the hexamine dinitrate option also.
I'll keep you posted when I have some results...

[Edited on 16-6-2014 by markx]

[Edited on 16-6-2014 by markx]

markx - 16-6-2014 at 22:59

Here goes....Bachmann route with 70% HNO₃ and double amount of Ac₂O through "all liquid feeds":

Reagents:
0,03mol -> 4,2g hexamine
0,09mol -> 7,2g ammonium nitrate
0,16mol -> 14,3g nitric acid (70%)
0,5mol -> 51g acetic anhydride

9,8g glacial acetic acid

Experimental:
The hexamine and ammonium nitrate were dried on hotplate before the synthesis and sealed into airtight containers until used.
Hexamine was dissolved in 6,8g of glacial acetic acid with magnetic stirring, the result was a viscous transparent liquid with the approximate consistancy of syrup.
AN was dissolved in precooled (4C) nitric acid with magnetic stirring, no additional cooling was neccesary.
Acetic anhydride was weighed into a separate flask.

The reactor was heated by PID controlled waterbath and brought up to the reaction temperature of 75C. Magnetic stirring was used to agitate the reaction mixture.

Due to unfavorable weather conditions the experiment had to be conducted inside. For that reason the reactor chamber was sealed with plastic and no opportunity presented to install a thermometer into the reactor. Slow additions through syringes penetrating the plastic were planned to keep the exotherm controlled and inside chamber temperature near the optimum of 75C.

Into the reactor chamber were placed 10ml of Ac₂O, 3g of glacial acetic acid and 1ml of the AN+nitric acid mixture. Upon addition of the nitric acid, the AN pricipitated.
After about 5minutes of equilibriating the inner chamber temperature the gradual, concurrent (as much as it was possible) and slow additions of the three liquid feeds through the plastic wrap via syringe needles were begun.

The dosing was approximately in the order of
1) 0,5ml hexamine in glacial acetic acid
2) 1ml of AN in 70% nitric acid
3) 2,5ml of acetic anhydride

After the first 2 additions the reactor liquor remained transparent with a slight brownish tint, slight evolution of gas was observed upon addition of the liquid feeds. After the third additon of liquid feeds there was a sudden and heavy precipitation of at least several grams of suppposedly RDX. The crystals were coarse and heavy like sand and glistened in the light. If stirring was shut off, the precipitate immediately fell to the bottom of the reactor leaving behind a clear solution on top of it. Visually a rather enjoyable spectacle...

The exotherm was quite violent as the water bath temperature was seen to rise by a few tenths of centigrade following the addition of liquid feeds. The additions were tried to keep slow and cautiously spaced, but the inner chamber temperature most likely fluctuated wildly around the setpoint.
Additions were resumed until all of the feeds were consumed (at around 70minutes into the reaction) and the mixture was let to react for a further 25minutes after that at 75C. Slow gas evolution was observed and the torrent of heavy crystals in the vortex of the stir bar fogged the entire reactor.

To be continued...

[Edited on 17-6-2014 by markx]

markx - 17-6-2014 at 00:22

After letting the reaction continue for the 25minutes, the inner chamber was removed from the water bath and the contents drowned in 400ml of warm water. An instant and heavy precipitation of solid product(s) was observed:

The contents of the beaker were stirred for 5minutes with the magnetic bar and then filtered through 2 regular coffee filters. The filtration proceeded with extraodrinary ease as the precipitate was coarse and did not clog the pores of the paper.

The contents of the filter were neutralised with a solution of NaHCO₃, drained, washed with several portions of warm water and squeezed more or less dry between paper dowels.

The damp weight showed a rather promising 14,75g with the filter paper mass subtracted.

After complete drying the final yield was registered as 8,35g:

The result accounts for a 63% yield....not a miracle synthesis run, but I'm really pleased with it. As a consept verification synthesis it was a magnificent success. If we take into account the extra anhydride, initial diluted medium for the reaction (the 10ml Ac₂O + 3ml glacial acetic acid in the reactor) and the inconsistent temperature control in the inner chamber then I must say that this is far more than I initially expected. I would really love to perform an analysis on the resulting product with regards to the composition. I do fear that we shall see a rather sizeable "contamination" of HMX since the extra anhydride and inital diluted nitration medium are prone to shift the product towards the formation of the eight membered nitramine.

Ah yes....and it leaves a rather deep impression too

[Edited on 18-6-2014 by markx]

plante1999 - 17-6-2014 at 03:36

Very interesting work markx, looking forward new experiments

roXefeller - 1-8-2014 at 14:48

Quote: Originally posted by VladimirLem

yepp...its pretty hard to get it these days cause you can make diacetylmorphine with it....and many many interesting explosives too IF you had it...

I have to pull the thread on this one. What other EM come from Ac2O?

markx - 3-8-2014 at 22:32

Quote: Originally posted by roXefeller

Quote: Originally posted by VladimirLem

yepp...its pretty hard to get it these days cause you can make diacetylmorphine with it....and many many interesting explosives too IF you had it...

I have to pull the thread on this one. What other EM come from Ac2O?

Well...HMX via modification of the Bachmann process is one of the most rewarding options. But only imagination is the limit, since nitric acid + Ac2O form a powerful nitrating agent with catalytic properties in some instance.

Dornier 335A - 4-8-2014 at 06:31

Hardly of any practical interest, but nitric acid + Ac2O can nitrate cellulose to more than 13.5% N, something that nitric acid + sulfuric acid fails to do. Other than that, I agree with markx.

Motherload - 7-8-2014 at 08:57

Markx.
Great work.
Since Glacial Acetic Acid is a lot easier to come by and probably cheaper.
Have you tried using GAA to "concentrate" the HNO3 ?
One would think it would have a tendency to "hold" water like many other concentrated acids do, thereby letting you get away with less AcAn.
I couldn't find a chart on affinity of liquids towards water.
I wanted to try similar method, but using conc. H3PO4 to "hold" water in the reaction.
I can buy AcAn for the chem supply guy ... As long as I only buy a litre every few months. "It's to remove lead out of barrels for customers that shoot cast bullets."
So I like to conserv it and it is like $60 a litre.

markx - 7-8-2014 at 12:34

Quote: Originally posted by Motherload

Markx.
Great work.
Since Glacial Acetic Acid is a lot easier to come by and probably cheaper.
Have you tried using GAA to "concentrate" the HNO3 ?
One would think it would have a tendency to "hold" water like many other concentrated acids do, thereby letting you get away with less AcAn.
I couldn't find a chart on affinity of liquids towards water.
I wanted to try similar method, but using conc. H3PO4 to "hold" water in the reaction.
I can buy AcAn for the chem supply guy ... As long as I only buy a litre every few months. "It's to remove lead out of barrels for customers that shoot cast bullets."
So I like to conserv it and it is like $60 a litre.

I doubt very much that glacial acetic acid has the needed affinity towards water to overcome the affinity of nitric acid. Basic reasoning in terms of similar to similar center interactions tends to suggest against it. Besides, dilution of the reaction media with acetic acid will tend to push the reaction mechanism towards the formation of HMX:
http://www.sciencemadness.org/talk/viewthread.php?tid=32296#...
Basivcally it is the same Bachmann system, but diluted with glacial acetic acid.

What I have considered though is the MAGNAC process for concentrating of nitric acid above the azeotropic point:

Attachment: US2860035.pdf (445kB)
This file has been downloaded 745 times

In theory it looks quite excellent....the dessicant Mg(NO₃)₂*2H₂O is regenerable under vaccuum, dirt cheaply available as the heptahydrate and no fear of sulfate contamination in the end product. In fact I have already constructed a pump operated closed loop aspirator station for the purpose. I also managed to aquire a lovely brand new czhechoslovakian belt driven 2 stage vacuum pump for free (built in 1982), but after realizing the beauty of the thing I found no heart to use it for the acid process. I know for sure that it will be a short death sentence for the pump, no matter what kind of scrubbers are used. Therefore I opted for the aspirator station which can handle all kinds of corrosive crap and still be virtually indestructible.
If that fails, then there is always the possibility to use the vacuum station to dehydrate the Mg nitrate heptahydrate to the dihydrate state and use sulfuric acid to perform the classic nitric acid distillation from the nitrate salt of magnesium. The appeal of using Mg nitrate is in the fact that MgSO4 is formed instead of the bisulfates (hydrogen sulfates HSO4- ), hence double the yield is possible with the same amount of H2SO4 as compared to Na or K nitrate. Even if we consider the 2 moles of remaining water in the dihydrate (which is presumably the limit for dehyrating Mg nitrate befor decomposition occurs even under vacuum), the yield is still better than using Na or K nitrate.

markx - 2-9-2014 at 00:44

I did regenerate an old batch of RFNA by redistillation and addition of urea yielding about 50ml of near anhydrous HNO3 (measured density of 1,5g/ml). The resulting acid was ever so slightly yellow colored and I decided to try it in the Bachmann synthesis without further purification. The resulting outcome was observed:

Raw materials:
Feed I- 3,36h hexamine + 5g glacial acetic acid
Feed II- 5,5g AN + 5ml WFNA (slight contamination of NO2)
Feed III- 15g Ac2O

As the AN and HNO3 were combined in flask, a rather noticeable amount of NO2 was released and the mixture remained slightly yellow. An indication of persistant NO2 contamination and a clear sign of the need to further purify the acid before synthesis.

Heel in reactor:

3g glacial acetic acid
3g Ac2O
0,6ml Feed II

Synthesis temperature 75C (PID controlled), magnetic stirring was applied to the reactor chamber.

The heel was let equlibriate to 65C and additions of liquid feeds proceeded during 20minutes in 7,5 parts as follows:

1ml Feed I
1ml Feed II
2ml Feed III

Immediately after the first addition of feeds a heavy precipitate of RDX started to form. But the shape of crystals was different this time. Not a dense granular form, but a more flocculent voluminous sedimentation was observed. The exotherm was very violent and after the second feed the temperature spiked upwards of 82C for a short period of time. PID control was shut off at that point and addition of ice to the waterbath was used to keep the temperature in the range of 75C optimum. In retrospective the feeds should have been divided into more portions to avoid the spiking of temperature and a more consistant reaction. In spite of that, the precipitate gathered at amounts that turned the reactor contents into a thick sludge and made stirring very inefficient. Before the last portion of feeds was introduced, the reactor contents were resembling more a solid phase than a liquid. An amazing difference compared to the synthesis with 70% HNO3.
After the completion of liquid feeds the reaction was run for an additonal 15min at 75C. The cristals were filling the liquid phase to the full amount and no separation of phases occurred. The cristals were all in the flocculent voluminous form. A suspicion of side reactions having taken place and low melting contaminants in the product arised.
After the 15 minutes the temperature of water bath was raised to 97C and 50ml of warm water was added to the reactor chamber. There was no phase separation even as the volume of the reactants was more than doubled by the addition of water. The flocculent mass filled the liquid to full extent and energetic evolution of gas was observed in the cristalline mass. A clear sign of side products decomposing in the acidic media. A decicion was made to digest the products in the reactor at 97C for an extended time until no more signs of decomposition are seen.
After 3 hours of digestion at 97C the cristalline mass had decreased in volume by four times and acquired a more dense and slightly granular appearance. Still the precipitate looked nothing like the product formed in pervious synthesis. No more evolution of gas was observed and the heating was shut off. Product was crashed into 400ml of cold water, filtered, washed with water, neutralised by sodium bicarbonate and washed with water again to remove the salts.

Dried yield was registered as 7,1g (67% of theoretical)

Melting point could not be measured at the moment as the heating element only reached a temperature of 175C...no signs of softening were observed at that point though.
I must reconstruct the MP apparatus on a smaller base to allow for higher temperatures...the rectifier diode heat sink that I use as the substrate is clearly too much for the 100W heating elemant and does not allow for higher melting substances to be analysed correctly at the moment.

Product is clear white and of a very fine cristalline appearance. I sucpect the slight NO2 contamination in the acid is responsible for the side products and the alteration of the cristalline structure of the resulting RDX. Also the fluctuations in temperature due to high feeding rate might be the cause of inconsistency. Further investigations will follow....

roXefeller - 2-9-2014 at 02:48

That is an interesting theory for contamination. It seems hard to separate the effect of the inconsistent temperatures. Will you be able to test it by fully cleaning the acid first?

markx - 2-9-2014 at 03:59

Quote: Originally posted by roXefeller

That is an interesting theory for contamination. It seems hard to separate the effect of the inconsistent temperatures. Will you be able to test it by fully cleaning the acid first?

The reaction system is rather complicated, that much is true, but by doing a minimum of two dedicated synthesis runs I believe that some light can be shed upon the cause of the observed effects.

1) Synthesis with same conditions and feed rates with similar temperature fluctuations, but a highly purified acid being used.

2) Synthesis with the contaminated acid, but with smaller and more frequent additions of the feeds, allowing for a better temperature control.

I tend to lean towards the NOx contamination being the main cause for changing the synthesis course and structure of the product (and the side products). The reason being that I also attemtpted the synhtesis with true RFNA and this run produced only 20% of impure yield with the same flocculent appearance. As the synthesis failed I did not report it, but in light of recent observations I think it can serve as a guide to the cause....

roXefeller - 2-9-2014 at 13:55

The Bachmann synthesis is also focused on dilution of the nitric acid with acetic acid. Your first run was effectively dilute nitric/acetic acid after the acetic anhydride dried out the 70% nitric acid. The second run wasn't nearly so. That could also be an effect that might confound the result.

markx - 5-9-2014 at 12:55

Right...I conducted the synthesis 2 (same contaminated acid, but better temp control and smaller more frequent additions of feeds). To achive better temperature control I added the feeds in 20 portions timed according to the internal temperature of the reaction mixture. That meant a reaction time of approximately double the duration (30min). Hence I also lowered the reactor temperature to 65C. The Bachmann patent specifically mentions the lowering of reaction temperature if a longer addition time of feeds is expected. Lo and behold....heavy, sandy, glistening crop of cristals started to form immediately after the first addition of feeds and continued to grow in bulk to the completion of the feeds. A sight almost identical to the one observed in my very first synthesis with the 70% acid and double anhydride amount. The temperature hovered between 63-70C during the reaction....as more portions of feeds were added, the amount of thermal mass in the reactor grew and fluctuations decreased accordingly.
After the additions were complete, the layer of heavy coarse cristals occupied about a third of the volume of liquid phase...a profound difference compared to previous run where the contents of reactor resembled cottage cheese at the end of reaction and liquid phase was almost nonexistent.
The reaction was let run at 65C for an additional 10minutes and then removed from the hot water bath and placed into a cool one to bring the temperature down to 30C. A profound amount of crystals precipitated during the cooling phase up to the extent of almost filling 3/4 of the liquid phase. The crystals that formed during the cooling phase were not as coarse and resembled the product of previous run after digestion phase at 97C.
The contents of reactor were crashed into 400ml of warm water, filtered, washed with water, neutralised with sodium bicarbonate and washed again with water to remove any remaining salts. The yield was squeezed more or less dry between filter papers and the wet mass was registered as 21,7g.
The synthesis was conducted with 4,5g of hexamine and the respective amounts of reagents....comparing to the result of first synthesis which had a wet product mass of 14,75g registered under similar conditons (and using 4,2g hexamine). Should not be too shabby at all. The expected dry yield could be up to 12g (84% theoretical)......but tomorrow will tell

I guess my suspicions about the slight NOx contamination being the cause of altered state in previous run were unfounded....seems that slow and continuous additions of feeds are the key to a successful reaction.

[Edited on 5-9-2014 by markx]

roXefeller - 5-9-2014 at 15:53

The reason being that I also attemtpted the synhtesis with true RFNA and this run produced only 20% of impure yield with the same flocculent appearance.

That is a good thing to report. I can't seem to find the solubility of NOx in nitric acid, but I suspect it can be very high for degraded acid.

Hoping for good news on the dried product.

NeonPulse - 5-9-2014 at 15:54

Great work! it looks like you are getting closer to the ideal conditions for this type of RDX synthesis. i 'm interested to see how your yield looks when dried properly. are you going to replicate this procedure to be sure of the same yield or tweak it a little more? 84% of theroretical is nothing to be sneezed at and seems pretty optimal already.

markx - 6-9-2014 at 00:55

I just weighed the product and the dry mass registered as 10,47g (73%).....not the 12g that I was hoping, but still a very noticeable improvement.

The product is of nice granular appearance with very little fine fraction. Looks like very fine white sand,,,,would almost be a shame to recristallise it

Actually the yield is exactly on par with the one reported in Bacmann patent 2798870: 74%
I guess the seventies will be a realistic expectation for overall yield with the Bachmann process, although the maximum is stated as up to 90%. Still I believe that this will be more an exception that enforced the rule.
If I take into account that I just managed to conjure 10,5g of nitramine by using 6,7ml of HNO3 and 24ml of Ac2O then I find this is really excellent.

I shall reconstruct my melting point apparatus this weekend and then hopefully we can have a preliminary peek at the purity of the product.

[Edited on 6-9-2014 by markx]

markx - 7-9-2014 at 11:38

I reconstructed my melting point apparatus and got it to a state where it can reach upper limit of 290C.....should be appropriate for most energetics now

As for the RDX, the melting points were as following:

1) Flocculent product from the "strange" synthesis - 195C with previous softening at 185C

2) Granular product from last synthesis - 195C with previous softening at 180C

It actually seemed that the flocculent product had less impurities (makes sense as it was simmered in acid for 3 hours), but the difference was quite small and again corellated very well with the values from the patent (196C-197C ). Not a absolutely pure product, but very well within limits of acceptance.
Meanwhile I have also aquired a set of TLC plates and further analysis can be performed...

markx - 4-1-2015 at 10:35

I had remnants (15ml) of last years WFNA in my cold depository that had really degraded to the point of questionable functionality. Still I decided to throw it all in the pot and cook up a last batch Bachmann style with the "not so white" NA. To my amazement it worked beautifully:

http://www.youtube.com/watch?v=slH2iGKyv3w

The video is from the purification stage of the process. The percipitate is the crude rdx formed in the synthesis stage (about 20g worth). The reactor contents are diluted with water and simmered for several hours at 95-97C to decompose unstable impurities. The heavy evolution of gas that can be seen in the flask will continue for at least 2 hours and is a clear sign of the side products decomposing. Sometimes it can become so intense that the contents overflow an spew out of flask. All the flocculent fraction disappears during the simmering and the precipitate becomes uniformly granular and very heavy in texture. This is also accompanied by a quite sizeable decrease in the volume of precipitate, but the mass loss is reasonably negligible.

[Edited on 5-1-2015 by markx]

ScubaDiver - 8-2-2015 at 13:40

Call me frugal but is not 50 cents per gram a bit pricey?

Hennig Brand - 8-2-2015 at 16:22

Quote: Originally posted by ScubaDiver

Call me frugal but is not 50 cents per gram a bit pricey?

That is because he is working at lab scale, once the process is finalized and he increases production to pilot scale and then to plant scale prices will significantly drop.

Found a good journal article on HDN production a while back which I thought others might find useful.

Attachment: Hexamethylenetetramine Dinitrate (HDN) - The Precursor for RDX Production by Bachmann Process.pdf (976kB)
This file has been downloaded 1610 times

Hawkguy - 8-2-2015 at 19:52

What are the pros to making RDX through a separate HDN synth? I just go straight from Hexamine, and so far the only hangup is the waste of the excess Nitric Acid....

Hennig Brand - 8-2-2015 at 19:59

That is the big advantage, much less highly concentrated, high purity, nitric acid is required.

Hawkguy - 8-2-2015 at 20:09

True, I see where you're coming from. But still.... The time and effort of doing two separate Nitrations would be a pain in the ass.

Hennig Brand - 8-2-2015 at 20:24

The laborious and technically demanding part for most people is getting the nitric acid as concentrated as possible and at the same time as free of nitrogen oxides as possible. When distilling nitric acid from a mixture of it and sulfuric acid a fraction can be collected first which is suitable for the last stage (HDN to RDX) and once the distillate concentration starts to drop below what is acceptable the next fraction collected can be used to produce the HDN feed from hexamine.

markx - 9-2-2015 at 03:30

I've actually found that the nitric acid distillation is very much like the distillation of fermented alcohol fractions...at first a highly concentrated fraction that is heavily contaminated with nitric oxides comes over (like the "heads" or aldehyde ester fraction-EAF of alcohol) and can be separately collected. Then the "heart" starts to distill over, this being a pure, almost white, highly concentrated fraction that is most suitable for the nitration of heterocyclics. After that a gradually less concentrated "tail" distills over. The "heads" and "tails" can be used for less demanding nitrations.

Preparation of HDN is very straight forward and quick from the point of conducting the actual reaction....the more tricky part is dealing with the hygroscopic, poisonous and water soluble nature of the stuff and yet getting it completely dry before further nitration to heterocyclics. Vacuum drying and storage under desiccant is the way to go for an anhydrous HDN precursor. If that is not done, the benefits of getting by with less acid go out the window very quickly. But really, apart from scientific curiosity and having a personal inclination towards performing extra work I see no point in using the HDN route in amateur practice. Just way too much complications for a rather questionable end gain. It might hold the promise of cost saving in commercial scale enterprises where waste nitric acid from e.g. PETN nitration is used to form the HDN. But I guess such things are not in our league of operations

Hennig Brand - 9-2-2015 at 05:51

Yes, I failed to mention that the "heads" (the tiny fraction which comes over at the start of the distillation with high nitrogen oxide(s) content) should be collected separately from the first main fraction to be collected. The size of the fractions collected does depend on the proportions and concentrations of nitric and sulfuric acid in the boiler as well as how it is run. From what I have read, most of the problems with HDN occur because of contact with water and using heat in attempts to dry it. If the wet HDN is quickly washed with a suitable volatile solvent to remove water and then the solvent is quickly removed (ideally with vacuum) before placing the HDN in airtight storage (ideally with a desiccant) the problem should be solved for the most part. I think that waste acids can sometimes be very effectively used, even in an amateur setting.

I made an Excel spreadsheet a while ago, to help determine the quantities of nitric and sulfuric acids of various strengths to use and when and what to collect when conducting a distillation. Here is a link to where the spreadsheet is attached:

http://www.sciencemadness.org/talk/viewthread.php?tid=15676&...

They are only small files so I might as well attach them here since they could be useful to others.

Attachment: Concentrating HNO3 - Overcoming the HNO3_H2O Azeotrope Using H2SO4.xlsx (79kB)
This file has been downloaded 715 times

Attachment: Concentrating HNO3 - Overcoming the HNO3_H2O Azeotrope Using H2SO4 (compatibility mode).xls (97kB)
This file has been downloaded 649 times

[Edited on 9-2-2015 by Hennig Brand]

Rosco Bodine - 27-3-2015 at 11:14

Quote: Originally posted by roXefeller

Quote: Originally posted by Dornier 335A

A quick search revealed this patent: Method for synthetizing cyclotrimethylenetrinitramine employing magnesium-nitrate-assisted direct nitration process
They used 12 times as much 95% HNO₃ by mass as hexamine, and the molar ratio of Mg(NO₃)₂*6H₂O to hexamine was 1 to 2. They ran the nitration at 30°C for an hour and reported slightly better yield than for the traditional procedure.

That same thread where underground got the Mg(NO3)2 concept from also has relevant discussion from Rosco (http://www.sciencemadness.org/talk/viewthread.php?tid=4701&a...). Using 12:1 by mass HNO3 to hexamine is wasteful of acid (Rosco thinks it can be done with 100ml HNO3: 40 g HDN, or ~8.3:1 acid:hexamine by mass). It was discussed that the yield was dependent on final reaction temperature. So it seems the patent authors increased the HNO3 to compensate for the 30C reaction. BTW that patent just seems odd. Why are they using a hexahydrate to dehydrate? And why are they writing new patents on a 70 year old process (direct nitration of hexamine from HNO3)? As far as trying Mg(NO3)2 to dehydrate, go ahead, someone has to put patents to practice. You should probably dehydrate the salt first. But you should keep in mind other concepts that reduce the acid use, detailed in that RDX thread, such as urea nitrate stabilized decomposition at high temps, and ammonium nitrate supplementation. And you should read Bachmann's work. He suggests varying cleaving mechanisms of hexamine depending on temperatures and dilutions, which result in different paths to the nitramine.

With regards to the possible usefulness of Mg(NO3)2 as a reagent in nitrolysis and nitrations where its dehydration property towards nitric acid may have favorable effect by tying up any water that is known to reduce the yield, I have continued to look at the literature and learn more, posted in another thread where several mixed nitrate systems have been identified which have potential usefulness.

http://www.sciencemadness.org/talk/viewthread.php?tid=4457&a...

The journal article and patent of Griffith relates to the binary system of NH4NO3 and Mg(NO3)2 and of particular interest is the composition based on weights that would be 65% Mg(NO3)2 and 35% NH4NO3 expressed as percentage for the anhydrous materials.

There are conflicting articles about the dehydration of Mg(NO3)2 alone being possible to achieve at atmospheric pressure using heat alone to drive off the water, without some decomposition leading to impurity of the basic salt.

I believe that the acidic nature of NH4NO3 in a combined melt with Mg(NO3)2 tends to oppose decomposition that would occur for Mg(NO3)2 heated alone, and that using vacuum to aid the final dehydration of a 65/35 mixture of Mg(NO3)2 + NH4NO3 would produce a mixture which could be useful in nitrolysis and nitration reactions for sequestration of water.

The journal article by Griffith describes that the 65% Mg(NO3)2 mixture with NH4NO3 is an anhydrous melt which is prone to form a monolith of a supercooled glass upon cooling, which is a definite complication to simple manipulation and is undesirable.

However, Griffith also describes that if the solidified glass is reheated to 110C, the metastable glass suddenly crystallizes with a large exotherm. Whether this results in a spontaneous crumbling and disintegration of the material I do not know for certain, but that would be likely to be the effect. If true, the reagent would be self milling and when cooled would be ready for the uses it is anticipated it would be valuable.

There are lower percentage mixtures where the content of Mg(NO3)2 on the anhydrous basis is below 38% of the combined mixture with NH4NO3 which are not prone to glass formation as the potential issue that would require breaking up a monolith of a solidified melt, since those lower percentage Mg(NO3)2 mixtures with NH4NO3 do crystallize on cooling. And those lower Mg(NO3)2 content mixtures could likewise still be useful even with their lower content of the material that would have the desired ability to tie up water, there would still be present only to a lessened extent the dehydrating property adjusted downward for the lower Mg(NO3)2 content.

An advantage for the lower Mg(NO3)2 content mixtures would be a lower melting point and easier dehydration during preparation of the anhydrous reagent, and elimination of the issue of glass formation which would require reheating to 110C to cause crystallization for the 38% to 65% or greater Mg(NO3)2 mixtures.

[Edited on 27-3-2015 by Rosco Bodine]

softbeard - 25-9-2015 at 15:14

Yet another RDX synthesis paper, but specifically dealing with radioisotope-labelled RDX & HMX synthesis. Contains a good list of references.

Attachment: p512589.pdf (1.2MB)
This file has been downloaded 993 times

kecskesajt - 27-9-2015 at 01:05

Hi,It was discribed a lot of time but what abou mixing an excess Ca(NO3)2 with H2SO4,filtering and then nitrating the hexamie in it? I don't want to make it, Ag2C2-DS and ETN is fine for me.
Will it be unstirrable and unfilterable?[SFMBE]

roXefeller - 27-9-2015 at 16:18

My first thought without looking it up would be to ask if CaSO4 has any equilibrium products like Na2SO4.

PHILOU Zrealone - 28-9-2015 at 01:57

Quote: Originally posted by kecskesajt

Hi,It was discribed a lot of time but what abou mixing an excess Ca(NO3)2 with H2SO4,filtering and then nitrating the hexamie in it?
Will it be unstirrable and unfilterable?[SFMBE]

Ca(NO3)2 is hygroscopic.
CaSO4 forms gyspum with water... = plaster of Paris

So unless you start from conc H2SO4 and dry Ca(NO3)2...stirrable at first, but not for long, difficult to filter without vaccuum.

Maybe good to try vaccuum distilation of the CaSO4 cake to get the conc HNO3 out of it in the cold to avoid its decomposition.

Fulmen - 28-9-2015 at 02:50

Pretty much. I tried it once, and you end up with a CaSO4/HNO3-paste that is pretty much unworkable. You could perhaps add the Ca(NO3)2 in portions, filtering in between, although I suspect the losses will be high. Vacuum distillation should work, but then you could use any nitrate salt and avoid the mess of the insoluble CaSO4.

I think this method would be best for producing mixed acids, that way you can wash out the HNO3 with conc. H2SO4.

kecskesajt - 28-9-2015 at 06:11

Ahh.Alright,I saving for a laptop so I dont have acces to a distillation kit in the near future.
Anyway,thanks for the anwsers.

hyfalcon - 28-9-2015 at 13:34

Has this already been uploaded or do I need to make a request?

Methylene-nitramines. Part I. The reaction of hexamine dinitrate with nitric acid at low temperatures

K. W. Dunning and W. J. Dunning
J. Chem. Soc., 1950, 2920-2924

DOI: 10.1039/JR9500002920

Joeychemist - 28-9-2015 at 14:59

I don't beleive it has and if you are going to go through the trouble of getting the first one you might as well get parts two and three.

Methylene-nitramines. Part II. An investigation of some properties of 1-alkoxymethyl-3 : 5-dinitro-1 : 3 : 5-triazacyclohexane and of related compounds
K. W. Dunning and W. J. Dunning
J. Chem. Soc., 1950, 2925-2928
DOI: 10.1039/JR9500002925

Methylene-nitramines. Part III
K. W. Dunning and W. J. Dunning
J. Chem. Soc., 1950, 2928-2932
DOI: 10.1039/JR9500002928

markx - 16-11-2015 at 23:32

Rigged up my melting point apparatus to record video of the process and overlay the temp controller reading simultaneously....turned out pretty cool

https://youtu.be/WMJDcE7wS_8

Just need to make the sample well bottom less reflective, otherwise the camera will compensate for the bright surrounding areas and turn the center sample too dark.

[Edited on 17-11-2015 by markx]

PHILOU Zrealone - 17-11-2015 at 07:58

Rigged up my melting point apparatus to record video of the process and overlay the temp controller reading simultaneously....turned out pretty cool

Thumbs up and hat down!
Beautifull!
Stil I have a question for you:
Is there no risk for your camera lens to be in the axis, in the bad event of a detonation?
Usually melting point apparatus allows one to see perpendicular to the axis...the full melting point is easier to see.

markx - 17-11-2015 at 11:55

Thanks for the kind words Philou!

This is not a very conventional desing indeed....the means available forced my hand, so to speak. Hence the head on collision course with the sample. But really, the amount measured is so small, on the order of one mg, that even in the unlikely event of a detonation the camera will most likely stay in tact as it sits a good 5cm above the sample well. Even so it is a cheap chinese usb microscope, the loss of which I shall hardly mourn.

Thraxx - 30-10-2016 at 09:20

I would like to tell ,that I am now ended the China synthesis of RDX-keto RDX mix,preparation vers. B. with HDN.
I take 14 g urea to 65 ml acid 50:50 HNO3 +H2SO4,cooled to 0-5C,past them I gave there 10 g of HDN at minus 5 C.It was white like milk and if I put it to water,then was there nothing,absolut nothing,clear water.
With the same acid and with the same HDN I synthetised RDX without problems.Therefore it was lie.

[Edited on 15-10-2016 by Thraxx]

kratomiter - 30-10-2016 at 12:37

I would like to tell ,that I am now ended the China synthesis of RDX-keto RDX mix,preparation vers. B. with HDN.
I take 14 g urea to 65 ml acid 50:50 HNO3 +H2SO4,cooled to 0-5C,past them I gave there 10 g of HDN at minus 5 C.It was white like milk and if I put it to water,then was there nothing,absolut nothing,clear water.
With the same acid and with the same HDN I synthetised RDX without problems.Therefore it was lie.

[Edited on 15-10-2016 by Thraxx]

Me too, same problem with the China synthesis. But in my case I were unable to keep the temperature below 5 ºC, which is critical for this synthesis.

Thraxx - 30-10-2016 at 22:38

I had a cooling with ice and 450g of NH4NO3.
In the first step by adding urea I did a mistake -temperature rose to +15 for 5 min.In the second step by adding HDN I was between 0 and +5C.
If I added the HDN into the mixed acid ,it wasnt like if I give the HDN to fuming nitric acid,it was too mild,it was like without reaction.It diluted only.
Fedoroff under Hexamethylene dinitrate described similar reaction with histamine giving to mixed HNO3 and sulfuric
acid for to prepare HDN.
May be ,that this China reaction should be done in two steps after longer time,because the first undercooled step could be Dinitrourea and it could be reaction between Hexamine and this stuff in the fuming nitric acid.(?)

[Edited on 15-10-2016 by Thraxx]

[Edited on 15-10-2016 by Thraxx]

cryomancer - 4-11-2016 at 11:54

So in the effort of figuring out ways to produce RDX at a decent cost and with relative ease i at one point stumbled upon a synthesis using Acetic Anhydride, but through looking into it futher I discovered that Ac₂O is very hard to purchase because of its linkage to illegal drugs.

I went stumbling around tring to find a decent synth for Ac2O but even its precursors were not that easy. But today i found this patent:Patent US1425500-Manufacture of Acetic anhydride
From what it says there is a possible route to Ac2O using high purity Acetic acid and acetylene gas. From what i can tell in the procedure this method is much easier.

Thoughts?

kratomiter - 5-11-2016 at 11:49

Quote: Originally posted by cryomancer

So in the effort of figuring out ways to produce RDX at a decent cost and with relative ease i at one point stumbled upon a synthesis using Acetic Anhydride, but through looking into it futher I discovered that Ac₂O is very hard to purchase because of its linkage to illegal drugs.

I went stumbling around tring to find a decent synth for Ac2O but even its precursors were not that easy. But today i found this patent:Patent US1425500-Manufacture of Acetic anhydride
From what it says there is a possible route to Ac2O using high purity Acetic acid and acetylene gas. From what i can tell in the procedure this method is much easier.

Thoughts?

Interesting, but you'll dealing with acetic acid vapours and a mercury salt, so be careful. Also keep in mind that acetylene from calcium carbide is contaminate with other compounds, so your AA won't be pure.

cryomancer - 5-11-2016 at 13:05

^

Right, the dangers of mercury salts, if you are using good lab practice, can be avoided. I would say it would be easier (maybe more expensive) to go and buy a tank of commercial acetylene gas from a welding company (I think tractor supply sells the tanks and gas) That way you would reduce contamination to near negligible amounts. It would be very simple to just pump the gas straight from the tank into the acid while outdoors or in a very well ventilated room in case the gas escapes.

PHILOU Zrealone - 6-11-2016 at 07:14

Quote: Originally posted by cryomancer

^

Right, the dangers of mercury salts, if you are using good lab practice, can be avoided. I would say it would be easier (maybe more expensive) to go and buy a tank of commercial acetylene gas from a welding company (I think tractor supply sells the tanks and gas) That way you would reduce contamination to near negligible amounts. It would be very simple to just pump the gas straight from the tank into the acid while outdoors or in a very well ventilated room in case the gas escapes.

Or Calcium carbide direct into the acetic acid....although the acid must be in 3X excès to take care for the CaC2, CaO and CaCO3 neutralisation into Ca(acetate)2...

Thraxx - 7-11-2016 at 01:07

For to make the nitrolysis of hexamine more economic ,I tryied use the spent acid for pentaerythritole esterification in situ.
After the nitrolysis which should be in ratio 1:8 and by 20 C I gave there into the reaction pentaerythritol by the 20-30 C in ratio 1:5 .
75 ml (112g)Nitric acid + 14 g Hexamin (1:8)... + 22 g pentaerythritol (1:5).After reaction stand it half of hour and I throw it into 400 ml of water.Result was 15 g of product.
May be this is not the right way.

PHILOU Zrealone - 7-11-2016 at 10:06

For to make the nitrolysis of hexamine more economic ,I tryied use the spent acid for pentaerythritole esterification in situ.
After the nitrolysis which should be in ratio 1:8 and by 20 C I gave there into the reaction pentaerythritol by the 20-30 C in ratio 1:5 .
75 ml (112g)Nitric acid + 14 g Hexamin (1:8)... + 22 g pentaerythritol (1:5).After reaction stand it half of hour and I throw it into 400 ml of water.Result was 15 g of product.
May be this is not the right way.

Sorry but I don't understand what you are trying to do.

-Your 75 ml HNO3 are at wat %?
-What are Hexamin (1:8) and PE (1:5)?
-15g of what product?

1°) PE should lead to PETeN, but into this case, you may have also PETriN, PEDN, PEMN...
2°) the Hexamin may lead to hexamine dinitrate or to cyclo-N,N'-dinitro-triazahexane nitrate...and of course HMX and precursors...
3°) Not counting with the oxydation products from PE and the possible hemi-acetal and acetal formation between alcohol (HO) groups from PE (or intermediary nitrated PE) and formaldehyde resulting from Hexamine breakdown.

--> An horrible mix...probably hard to purify, crystallize and most likely unstable for storage.

Better synthetise appart and mix afterwards to avoid complexification/multiplication of the side products.

[Edited on 7-11-2016 by PHILOU Zrealone]

PHILOU Zrealone - 7-11-2016 at 10:10

Quote: Originally posted by cryomancer

Not to neglect:
1°) the use of acetylen at about 2.5 atm/bars...
Over 2 bars acetylen becomes quite explosive on its own or to shock/surface catalyst ... owing to its endothermic nature
H-C#C-H --> 2 C + H2 + heat

2°) some acetylenic compounds of Hg are explosive

3°) Commercial tanks of acetylen usually contains aceton in which C2H2 is quite soluble and it reduces the risk of spontaneous explosion/shock explosion while pressurized.
--> Maybe is aceton detrimental to the proces?

[Edited on 7-11-2016 by PHILOU Zrealone]

Thraxx - 8-11-2016 at 00:34

-Your 75 ml HNO3 are at wat %?
-What are Hexamin (1:8) and PE (1:5)?
-15g of what product?

[Edited on 7-11-2016 by PHILOU Zrealone]

-I used freshly distilled fuming nitric stabilised whith urea.
-According to Orlova,which citate from work of Di Cerrione L.A.-Am, Chim.appl.38,5,(1948),-„ is the RDX by the nitrolysis constitute in the range between (H:Acid) 1:3 to 1:500,where optimum is between 1:8-1:30 with best yield by 1:26.“
Because the acid must be in excess for to equalize diluting during the reaction(3 mol watter from each mol of hexamine).This problem is by the nitrolysis of hexamine not possible to solve through sulfuric acid as usually. And therefore is in the spent acid too much nitric acid in too high concentration for to throw it .
Because the Pentaerythritol could be esterificate with nitric acid without sulfuric acid like in WWII. production methodes in Germany, Japan and Soviets and each of these methods used ratio 1:5 by the temperature abbout 20 C ,I thought,that the spent acid after the nitrolysis of Hexamin,could be used and exploatate for esterification of Petn.
-15g of what product?-I dont know what it is,it should be 11g of RDX and over 20 g of Petn.Perhaps is there the RDX and some lower nitrates of PE.

[Edited on 15-10-2016 by Thraxx]

PHILOU Zrealone - 8-11-2016 at 12:08

Maybe recover the "diluted" HNO3 from reaction by using it with hexamine to make hexamine dinitrate...and allow to dry
Or from urea to make urea nitrate and recover crystals for keto-RDX.

Thraxx - 9-11-2016 at 09:16

RDX from sulfamic acid like GB pat.899692:

Aminosulphamic acid (ASA) H3NSO3 mol= 97,10
NH4OH 24% mol =35,05
Formaldehyd 40 % mol= 30,03
HNO3 =63,01

I.Step :
10g ASA diluted in 30 ml watter neutralised with 14 ml aquous Ammonia .Evaporated .Yield 15g crystals looking like mica.
This step is not necessary,because the Ammonium ASA is possible to buy by Aldrich.
II. Step:
Into 10 ml of formaldehyd giving 15 g crystals of ammonium ASA .Reaction mild but exothermic.
After adding ethanol for to precipitate the product ,there extruded white liquid on the bottom looking like NG.
Other clear dilution should crystalised , and after two days there was nice crystals,but still wet.Added Ethanol,filtered,dryied.Complicate to dry it.After drying there was 15 g of ammonium methylene amino sulphonate
III.Step:
15 g of ammonium methylene amino sulphonate added into 30 ml of cold fuming acid (vacuum made).Mild reaction,throwed into 150 ml of ice watter =yield poor-2g RDX

[Edited on 15-10-2016 by Thraxx]

[Edited on 15-10-2016 by Thraxx]

PHILOU Zrealone - 10-11-2016 at 08:15

RDX from sulfamic acid like GB pat.899692:

Aminosulphamic acid (ASA) H3NSO3 mol= 97,10
NH4OH 24% mol =35,05
Formaldehyd 40 % mol= 30,03
HNO3 =63,01

I.Step :
10g ASA diluted in 30 ml watter neutralised with 14 ml aquous Ammonia .Evaporated .Yield 15g crystals looking like mica.
This step is not necessary,because the Ammonium ASA is possible to buy by Aldrich.
II. Step:
Into 10 ml of formaldehyd giving 15 g crystals of ammonium ASA .Reaction mild but exothermic.
After adding ethanol for to precipitate the product ,there extruded white liquid on the bottom looking like NG.
Other clear dilution should crystalised , and after two days there was nice crystals,but still wet.Added Ethanol,filtered,dryied.Complicate to dry it.After drying there was 15 g of ammonium methylene amino sulphonate
III.Step:
15 g of ammonium methylene amino sulphonate added into 30 ml of cold fuming acid (vacuum made).Mild reaction,throwed into 150 ml of ice watter =yield poor-2g RDX

[Edited on 15-10-2016 by Thraxx]

[Edited on 15-10-2016 by Thraxx]

Maybe use the Na or K salt instead of the NH4 salt?
Anyway, it is not the favoured synthesis pathway for a reason...probably the low yield.

Thraxx - 10-11-2016 at 23:25

[/rquote]
Maybe use the Na or K salt instead of the NH4 salt?
Anyway, it is not the favoured synthesis pathway for a reason...probably the low yield.[/rquote]

-I am looking for some RDX method with better yields in comparisson to fuming nitric acid,not to precursor like in industry.
Problem is,that this method has poor yields of both views.

The patent is talking about ammonium salt.The K salt was described in this thread like W method and the last step needs SO3 or P2O5.
Described method with ammonium salt like patent need either
SO3 or 100% acid.These conditions are very simmilar.It seems me,that the precursor is hygroscopic and is very complicate to dry it and the acid is not 100%.Lower concentration of reaction mix lead to inconspicious oxidation with bubbles.(no Nox,simply bubbles).

Attachment: RDX from sulphamic acid.pdf (203kB)
This file has been downloaded 638 times

Bert - 11-11-2016 at 04:05

Thrax?

Please, could you add time and temperature range information to your lab notes?

The claimed 75% yield method with straight nitric acid in the patent description mentions a desirable range of temperatures, and a specific reaction time before drowning the mixture in cold water.

The claimed "quantitive yield" method with SO3 does not provide an actual description of weight achieved, or sufficient information for me to derive that for myself? Or do I need more coffee....

I did not yet see the method with P205/nitric acid mentioned, is this elsewhere in thread? Could you add a link, if so-

Going back to looking for Bambi now. Too cold to type without gloves.

Thraxx - 11-11-2016 at 09:01

Quote: Originally posted by Bert

Thrax?
... time and temperature range information to your lab notes?
... range of temperatures, and a specific reaction time before drowning the mixture in cold water.
...I did not yet see the method with P205/nitric acid mentioned, is this elsewhere in thread? Could you add a link, if so-

Method with P2O5 you will find in this thread,page 2,author: Polverone.(I saw simmilar description on the EWF forum and elsewhere I archived it.)
To my experiments.I did Step 2 (precursor) two times and Step 3 three times .In each step I did mistakes.
My mistakes :
Mistake in Step 1-first experiment-precursor was prepared in described temperatures.For to keep it between 30-40 C I musted cool and heat.But I did it exactly.It was very long reaction-5 hours. In this case I didnt mistake and the product was clear solution.After one day by 20 C on the glas plate I saw there
small crystals,after two days there was very long and nice crystals .
- second experiment- I prepared 50 g of ammonium ASA with 74,5ml formaldehyd ,all was right at the time of adding,but I must go to another room and as I returned,there was 90 C and in the beaker was something like white gelatine.I cooled it and dryied it .I saw there no crystals and the drying was not easy,twice I gave there ethanol,but I thought,that if it was on the 90C,then I can it heat on this grades.And after it seems me dry,I did Step 3.
Mistakes in Step 3.
- in the first experiment I used the first (good)precursor and 30 ml acid.It was more,there should be 30 g acid (about 20 ml).During reaction rose temperature for one moment over 30 C.It was in half time of addition.Followed addition was in the range 5-10 C.I drowned it short time after last addition.I should wait 30 min.
- in the second experiment I did no mistakes,it was with 20 ml acid,then added between 5-10 C and waited for 30 minutes.This time I saw,like the clouded acid is more clear and clear and some bubbles are there.And after drawing it to ice there was shit.Clear watter.
- in the third experiment I prepared into the beaker 10 ml of liquid Mg(NO3)2 melted at 170C,because I told me,that there was a watter because not good dryied precursor.Well. Then was the same like before-holy shit and clear watter.
Result-the second precursor, either wet or dry, was bad.May be,if the first experiment with good precursor would done without thermical excess (30C)and waited for 30 min., it could be more succesfull.
((SO3 method--if I remember ,SO3 is available from thermical decomposition of FeSO4,but there is an philosophical question,if the RDX is good enough for such smell and wasting of acid and time.))

[Edited on 15-10-2016 by Thraxx]

[Edited on 15-10-2016 by Thraxx]

Thraxx - 20-11-2016 at 03:11

Nitrolysis under pressure
I had a rest of abbout 30 ml nitric acid (vac. fum.)and I gave there 10 g of hexamin.Unfortunatelly it slumped me there big amount of hex and temperature was rose now at 60 C,big flame and smell (gray smoke and brown nox).Acid was clear like watter.I cooled it and at 20-30 C added the rest of hex.And after addition I put the beaker under pressure 120psi of compressed air for one hour without cooling.After I opened the pressure bottle,there was on the bottom of the beaker a small amount of white crystals and after diluting in 150 ml watter there was a very good yield.Try it too.

[Edited on 15-10-2016 by Thraxx]

Bert - 20-11-2016 at 11:43

Could you define "a very good yield", give dry product weight?

And is there any litterature or other particular information that led you to try pressurizing the reaction?

Thraxx - 20-11-2016 at 22:21

Pressurizing is my own idea and the "very good yield" is drying now,but it must be repeated,because there was the accident which I described.
the "very good yield" is 10 g.

[Edited on 15-10-2016 by Thraxx]

PHILOU Zrealone - 21-11-2016 at 15:28

You may reduce the heat by using Hexamine dinitrate instead of Hexamine...

Since neutralization generates heat (use frozen cold saturated solution of hexamine then add frozen cold 69% HNO3)...
Final salt must be dried and can then be used for your experiment --> reducing a lot the heat of reaction.

Thraxx - 21-11-2016 at 23:35

You may reduce the heat by using Hexamine dinitrate instead of Hexamine...

Since neutralization generates heat (use frozen cold saturated solution of hexamine then add frozen cold 69% HNO3)...
Final salt must be dried and can then be used for your experiment --> reducing a lot the heat of reaction.

To work with HDN is to tolerate this hygroscopic, corrosive and stinking stuff and need to have a good dessicator/dryer,where isnt gauge for to know if it is already dry.
Reasons for to use the HDN are two-as you told,the mild reaction and second-utilisation of spent acid from Petn.
If somebody think,that save some acid with use of HDN if he use the for acid advantageous ratio,then he use the disadvanategeous ratio for RDX and his product contain other stuffs.(((may be if such product would be renitrated,there could be a lot of HMX )))
The first industrial method used in Italy for production of T4(which now we told RDX)used HDN:acid 1:8 and 6 h.after addition it was cooled and vacuum destilled (after filtration?without diluting?) at 40C for to have acid or formaldehyde back.
One of author (Kraus)told,that production of Petn and RDX are simmilar-if the Petn has good nitration yields and problematic precursor,then the RDX has good precursor and problematic nitration yields.
Therefore if we use the HDN instead of Hexamine,then we lose the advantage of RDX production.

[Edited on 15-10-2016 by Thraxx]

[Edited on 15-10-2016 by Thraxx]

markx - 11-12-2016 at 04:36

Some very energetic "diamonds" I grew in a soxlet extractor type of recristallisator....a thing of beauty

PHILOU Zrealone - 11-12-2016 at 16:27

Some very energetic "diamonds" I grew in a soxlet extractor type of recristallisator....a thing of beauty

Nice.
RDX, HMX or keto-RDX?

What a mysterious way of recristallisation...never heard of it; could you explain a bit more...the procedure or scheme.

Microtek - 12-12-2016 at 02:40

Quote:

Therefore if we use the HDN instead of Hexamine,then we lose the advantage of RDX production.

I don't quite get your point. HDN is not difficult to produce, nor excessively hygroscopic. As Philou said, just add cold dilute (ca. 60%) HNO3 to a saturated (or nearly so) hexamine solution. HDN precipitates immediately and can be filtered off. Then wash the crystals with alcohol and dry. In my experience, air drying is not problematic, but you could use a CaCl2 drying tube to blow dry air over the product if you live a very humid place.

markx - 12-12-2016 at 04:58

Some very energetic "diamonds" I grew in a soxlet extractor type of recristallisator....a thing of beauty

Nice.
RDX, HMX or keto-RDX?

What a mysterious way of recristallisation...never heard of it; could you explain a bit more...the procedure or scheme.

Garden variety rdx....but the original aim of the recristallisation device was towards alpha hmx conversion to beta cristal modification. Basically it is an improvised soxhlet extractor and the idea is to use refluxed solvent to dissolve the sample in the smaller hanging glass vessel and then carry it to the reboiler where it slowly settles out under gentle mixing (don't let the pic fool you, the device is heated via a pid water bath, not directly on hot plate):

What this contraption allows is the use of a limited amount of solvent that is recycled to carry over a rather sizeable sample. Not really essential for rdx, but for hmx the conventional means of recristallisation is a lost cause. Solubility is minimal in all conventional solvents and furthermore it displays basically zero solubility temperature dependance. Hence heating the solvent will accomplish nothing with the eight membered heterocycle. Thus the contraption at hand will allow to use a reasonable amount of solvent to get the conversion done. Due to the less than optimized geometry of the vessel containing the sample the whole process currently takes too long and crystals tend to grow too large, but visually a very enjoyable sight.

[Edited on 12-12-2016 by markx]

PHILOU Zrealone - 12-12-2016 at 11:29

If I understand correctly because it seems that there is solid in both récipients (inner and outsider):
1°)The initial cristals are inside the hanging inner vessel.
2°)The outside vessel contains the solvent that evaporates because warm
3°)The condenser condense the warm volatilized solvent into the inside tinier vessel which dissolve a portion of the initial cristals.
4°)The solvent level into the inner vessel goes up while cristals remains at the bottom of it; at a certain point (level) it goes out via tiny holes and fall into the larger outer vessel with the initial solvent; doing so the dissolved compound passes into the larger recipient with the larger amount of solvent.
5°)The outside recipient enrich itself slowly with the dissolved compound while the solvent continues its cylcus (evaporation, condensation into inner recipient, dissolution of initial cristals and fall of solution into larger outside recipient).
6°)The outside recipient reaches the saturation level where it deposits first cristals at the desired temperature of cristallization.

Nice set-up and process. --> Bravo/Applause/Hat down.

markx - 12-12-2016 at 12:56

If I understand correctly because it seems that there is solid in both récipients (inner and outsider):
1°)The initial cristals are inside the hanging inner vessel.
2°)The outside vessel contains the solvent that evaporates because warm
3°)The condenser condense the warm volatilized solvent into the inside tinier vessel which dissolve a portion of the initial cristals.
4°)The solvent level into the inner vessel goes up while cristals remains at the bottom of it; at a certain point (level) it goes out via tiny holes and fall into the larger outer vessel with the initial solvent; doing so the dissolved compound passes into the larger recipient with the larger amount of solvent.
5°)The outside recipient enrich itself slowly with the dissolved compound while the solvent continues its cylcus (evaporation, condensation into inner recipient, dissolution of initial cristals and fall of solution into larger outside recipient).
6°)The outside recipient reaches the saturation level where it deposits first cristals at the desired temperature of cristallization.

Nice set-up and process. --> Bravo/Applause/Hat down.

Well played, sir!

Indeed that is the absolutely correct description of the course of events that through inevitable completion led to the cristalline result that can be seen in the previous posting

NeonPulse - 12-12-2016 at 17:16

Some very energetic "diamonds" I grew in a soxlet extractor type of recristallisator....a thing of beauty

Nice job! Quite an interesting method you have there.
I have a similar diamond like crystals pic on page 2 of this thread but I made mine via slow evaporating a solution of acetone however I had already gotten the main crop of crystals and the acetone was decanted with the crystals growing over a coupe of days.

Thraxx - 14-12-2016 at 09:41

Quote: Originally posted by Microtek

Quote:

Therefore if we use the HDN instead of Hexamine,then we lose the advantage of RDX production.

I did a lot of HDN in the past and I dont like it.May be I am lazy. Hexamine is easy and cheap to buy.

PHILOU Zrealone - 14-12-2016 at 12:34