Sciencemadness Discussion Board - HMX via nitrolysis of DPT

HMX via nitrolysis of DPT

greenlight - 4-9-2020 at 06:04

1,3,5,7-tetranitro-1,3,5,7-tetrazoctane (HMX)

Formula: C4H8N8O8
Molar mass: 296.15g/mol
Density: 1.91 g/cm3
Melting point: 276-285C
VOD: 9100 m/s @ max density
OB%: -21.61
Gas volume products: 0.907 L/gram

I am attempting the synthetic pathway pictured below to synthesize HMX.
Even though some of the reagents are slightly hard to acquire (formaldehyde, nitric acid) it is more attractive as there is no need for acetic anhydride like other methods. Being a precursor for heroin manufacture makes acetic anhydride harder to obtain than the reagents used here.
The first two steps are done and outlined in the following post.

[Edited on 4-9-2020 by greenlight]

njl - 4-9-2020 at 06:15

So you have nitrourea? Would you mind doing a little bit of testing with it vs urea nitrate? I can't find very much info on their properties and how they compare.

greenlight - 4-9-2020 at 06:39

Yes I have nitrourea but I did the steps on a small scale and only have 8 grams of it. I also suffered yield loss cause I ran out of time and couldn't leave the reaction to stir for the required time after addition.
I do have about 500 grams of 5 year old urea nitrate though which I could turn into more nitrourea for testing. I made fresh stuff for this to eliminate variables. In the meantime I will hunt for some properties and values for the two.
I remember testing 500g charges of urea nitrate when I was 17 using large caps and the results weren't that impressive. Similar to ANFO. Have never used nitrourea before though.

Urea nitrate

greenlight - 4-9-2020 at 06:45

Not much to see here really. 22 grams of hardware store urea was dissolved in 55ml of distilled water and 30ml of 70% nitric acid added with stirring and cooling. Filtered and dried in a dessicator. Final yield 19 grams due to not hunting for a second crop of crystals with freezer cooling.

[Edited on 4-9-2020 by greenlight]

[Edited on 4-9-2020 by greenlight]

Nitrourea

greenlight - 4-9-2020 at 06:57

reagents:

* 19g urea nitrate
* 70ml 98% sulfuric acid

method

70 ml of 98% sulfuric acid was placed into a 250ml beaker in an ice bath with stirring. When the temperature reached 0C, urea nitrate (19g) was added in small portions while keeping the temperature low and watching for evolution of gas.

Stirring was continued for 5 minutes after last addition and then the mix poured onto ice which instantly precipitated the nitrourea as a fine white suspension of powder.

The nitrourea was filtered, washed with ice cold water and dried in a desiccator. Yields are usually around 60-70% but my lack of continued stirring resulted in only 8 grams which is much less at around 41%.

[Edited on 4-9-2020 by greenlight]

underground - 4-9-2020 at 08:37

Do you have any paper for synthesis of DPT from nitrourea ?

greenlight - 4-9-2020 at 10:40

Yes, I'm using this one that's actually quite old:
https://www.google.com/url?sa=t&source=web&rct=j&...

underground - 5-9-2020 at 07:18

Quote: Originally posted by greenlight

Yes, I'm using this one that's actually quite old:
https://www.google.com/url?sa=t&source=web&rct=j&...

Thanks, looking forward for your DPT synthesis. DPT itself is energetic too but never seen any test with it.

[Edited on 5-9-2020 by underground]

Dinitro pentamethylene tetramine

greenlight - 6-9-2020 at 22:35

Well here it is:

Materials:

* Nitrourea (7.25 grams)
* Formaldehyde solution 37% (45ml)
* Sodium hydroxide aq. (5%)
* Ammonium hydroxide (30%)

Method:

7.25 grams of nitrourea was mixed with 45ml of 37% formaldehyde solution which resulted in a white suspension. The mixture was heated to 45 C while stirring which resulted in complete dissolution of the nitrourea.
The acidic solution was cooled to room temperature (25C) and adjusted to pH 3 via addition of 5% sodium hydroxide solution.
A small amount of carbon dioxide gas was liberated during this process.

The solution was then heated to 65C for an hour and 15 minutes. During this time, more evolution of carbon dioxide was noticed but it never got out of control.

The solution was then cooled back to room temperature and 30% ammonia solution was added dropwise while periodically checking pH until 7 was reached. As soon as it neared 6-7 a white precipitate started rapidly forming in the solution. At pH 7, the mixture was filtered through a Buchner funnel and the filtrate returned to the fume hood where additional ammonia solution was added resulting in a second crop of DPT.
Filtering and further addition of ammonia was repeated but resulted in only a miniscule further amount of DPT.

Final dried weight of DPT is 3.80 grams. This corresponds with the paper used where 52% yield was noted.

Right after the nitrourea addition, my favourite (only green) spirit thermometer rolled off the bench that I have used in energetics for 10 years+ now

After all the work it has done with temp control over the years I felt like it needed a mention.

[Edited on 7-9-2020 by greenlight]

[Edited on 7-9-2020 by greenlight]

[Edited on 7-9-2020 by greenlight]

[Edited on 7-9-2020 by greenlight]

underground - 7-9-2020 at 07:22

Respect. Could you actually try to detonate some of this stuff? Looking forward to your HMX synthesis

greenlight - 7-9-2020 at 09:33

Thanks

Yes, I might run another batch as I was thinking it would be interesting to detonate some to see the results.
I only have 70% nitric acid at the moment so I will have to distill it atmospherically with sulphuric acid and then with vacuum to get the high strength acid for the nitrolysis.

[Edited on 7-9-2020 by greenlight]

greenlight - 23-9-2020 at 09:40

Atmospheric distillation of 70% nitric acid complete resulting in yellow fuming nitric acid.
Vacuum pump is playing up at the moment resulting in yellow acid even under vacuum distillation.
Opted to try the dry air pumping method to clean it up instead.

Brought an aquarium air pump from a pond supply store and found that my (chinese made) gas washing bottle stem has broke overnight for no apparent reason whatsoever which I have noticed is a reoccurring trend with this cheap glassware. Placed the pump in an empty desiccator and covered it with anhydrous calcium chloride without using a drying bottle as an alternative method to pump dry air.

1 hour later and I now have 60 ml (volume has reduced) of clear high purity fuming nitric acid with no apparent nitrogen oxide(s) contamination.
Should be sufficient for the final nitrolysis of DPT.

[Edited on 23-9-2020 by greenlight]

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underground - 24-9-2020 at 12:03

Nice job Greenlignt. I am waiting for your proress, really interesting stuff.

Microtek - 25-9-2020 at 09:32

I find that 5-10 minutes is plenty for purging the NOx from the nitric. As you have noted, you do lose some nitric doing this, so excessively long purging should be avoided.

greenlight - 25-9-2020 at 10:27

Thanks underground

@Microtek, only 5 or 10 minutes? Wow, at what temperature was this done at and did you include any other factors differing from my setup?

Microtek - 28-9-2020 at 07:19

50C, just like the urea method. I think this is a temperature sweetspot that is high enough that the NOx becomes quite labile, but low enough that not much HNO3 is lost. In my experience, it is vey important that the air stream is as dry as possible, otherwise the NOx is not purged as efficiently (I don't know why this should be the case).

greenlight - 2-10-2020 at 10:44

I thought that 50C would start to decompose the acid as well as purge the nitrogen dioxide but 10 minutes is much more efficient considering I lost almost 10ml of nitric acid.

I will be completing the last step today doing a test run with 1.5g of DPT using excess acid and ammonium nitrate to aid nitrolysis and hopefully result in a good yield.

1,3,5,7-tetranitro-1,3,5,7-tetrazoctane

greenlight - 3-10-2020 at 09:45

For the final nitrolysis of DPT, this paper was used: http://www.energetic-materials.org.cn/publish_article/2015/1...
The paper found that the NH4+ ion (not just the NO3-) has a positive effect on the nitrolysis step yield-wise when compared to other nitrate salts such as copper and potassium nitrate. It also states a large molar excess (10:1 AN-DPT) results in high 60% yields of final product.
One thing I changed was the amount of 99% nitric acid using more than the authors of the paper did.

Materials:

* 1.5g DPT
* 20 ml 99% nitric acid
* 6.44g ammonium nitrate (10x molar amount of DPT)

Method:

6.44g of desiccator dried ammonium nitrate was mixed into 15ml of white fuming 99% nitric acid in a 100ml round bottom flask with magnetic stirring in a salt-ice bath. The resulting pale yellow solution was cooled to about 5C which resulted inthe ammonium nitrate recrystallizing out making further stirring impossible. Another 5 ml of 99% nitric acid was added in an effort to re-dissolve the ammonium nitrate before the DPT was added in small portions with a spatula. White fumes appeared on each addition and the final temperature was 8.5C.

After DPT addition, the solution was left stirring in the ice bath for 30 minutes in which time the temperature dropped to 4C resulting in a semi solid mixture of ammonium nitrate appearing again. After 30 minutes, the ice bath was replaced with a warm water bath and the mixture held at 25C for 40 minutes before being crashed into ice water to precipitate the final HMX which was filtered and washed 4 times with ice cold distilled water.

Final yield after drying is 0.9 grams from 1.5 g DPT. If working on purely weight this is a 60% yield but the molecular weight of the HMX (296.15 g/mol) is much more than the DPT (186.17 g/mol). So theoretically, the final yield should be about 2.3 grams but then you have another paper stating 1.23g from 2g of DPT is a 45% yield which would make mine a 45-50% yield but I am not sure.

I still have 2 grams of DPT left and can think of a few factors that can be played with for the last run:

1. The ammonium nitrate was ice-pack grade and probably impure which I am quite sure was responsible for the yellow discolouration. I will synthesize my own from nitric acid and ammonia solution next time.

2. Slightly less ammonium nitrate to allow for better stirring with no solid phase at low temperature.

3. Longer mixing at room temperature before crashing into ice.

[Edited on 3-10-2020 by greenlight]

[Edited on 3-10-2020 by greenlight]

[Edited on 3-10-2020 by greenlight]

underground - 3-10-2020 at 12:53

You have done a great job, keep up the good work man, really informative thanks for sharing

B(a)P - 3-10-2020 at 13:31

Plus one to that. Thanks very much for such a great site up. Really interesting stuff.

Nitrosio - 25-11-2020 at 16:51

2C6H12N4 + CO(NH2)2 + 10HNO3 + 2NH4NO3 = 3C4H8N8O8 + CO2 + 11H2O

[Edited on 26-11-2020 by Nitrosio]

B(a)P - 25-11-2020 at 20:51

Quote: Originally posted by Nitrosio

2C6H12N4 + CO(NH2)2 + 10HNO3 + 2NH4NO3 = 3C4H8N8O8 + CO2 + 11H2O

That would be an interesting route to HMX. Do you have any more detail or a reference where it came from?
Thanks

Nitrosio - 26-11-2020 at 10:07

DPT from Urea

CO(NH2)2 +2HNO3 = CO(NH-NO2)2 + 2H2O
CO(NH-NO2)2 + 3CH2O + H2O = CH2OH-NH-NO2 + (CH2OH)2-(N-NO2) + CO2
CH2OH-NH-NO2 + (CH2OH)2-(N-NO2) + 2CH2O + 2NH3 = C5H10N6O4 + 5H2O

CO(NH2)2 + 2NH4NO3 + 5CH2O = C5H10N6O4 + CO2 + 6H2O

DPT from Hexamine

(CH2)6-(N)4 + 2HNO3 = CH2(4)-(N-NO2)2-(N-CH2-N) + CH2O + H2O

HMX from DPT

CH2(4)-(N-NO2)2-(N-CH2-N) + 2HNO3 = (CH2)4-(N-NO2)4 + CH2O + H2O

Nitrosio - 30-11-2020 at 01:03

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Nitrosio - 5-12-2020 at 03:44

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[Edited on 5-12-2020 by Nitrosio]

Nitrosio - 6-12-2020 at 00:31

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HMX second run

greenlight - 20-1-2021 at 11:24

Another nitrolysis run was attempted of the DPT.
This time recrystallized pure ammonium nitrate was used and the amount reduced and stirring time was longer.

12 grams of ammonium nitrate was added to 35 ml of white fuming nitric acid with very slight NO2 contamination. The mixture was stirred in an ice-bath whereupon the ammonium nitrate dissolved giving a clear solution.

Once the temperature reached 5 degrees, slow addition of 4.40g of solid DPT was begun. Each addition caused the mixture to turn cloudy light yellow before slowly clearing up again. Complete addition took around 20 mins as the temperature was monitored and kept between 6-8°C.

Once complete, the nitrolysis mixture was removed from the ice bath and brought up to room temperature (25-26°C) with a warm water bath. It was held here with stirring for 40 minutes and an light amber brown solution resulted.

This was then poured into 200ml of crushed ice/distilled water mixture whereupon the desired HMX precipitated out as a fine white powder. It was then washed with 100ml ice cold water and placed in a desiccator to dry overnight. Will update with yield when dry.

[Edited on 20-1-2021 by greenlight]

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[Edited on 20-1-2021 by greenlight]

underground - 20-1-2021 at 12:12

Nice. How much HMX did you recover ? (yields)

[Edited on 20-1-2021 by underground]

greenlight - 21-1-2021 at 10:16

Final dried yield is 2.87g which corresponds to a 65% yield which is not too bad. If worked out with the molecular weights in mind, final yield should be over 6 grams, which means it is within the 45-50% area again.

[Edited on 21-1-2021 by greenlight]

[Edited on 21-1-2021 by greenlight]

underground - 21-1-2021 at 11:09

Nice greenlight. You have done a great job so far.

Petn1933 - 22-1-2021 at 05:26

Your work was excellent and exemplary. thank you

greenlight - 22-1-2021 at 10:03

Thanks guys.

I'm quite happy there is a method to obtain HMX without trying to find restricted precursors like acetic anhydride. Still want to do a melting point and plate test though.

Petn1933 - 22-1-2021 at 12:26

Can we use fuming nitric acid instead of white fuming nitric?

greenlight - 27-1-2021 at 23:42

Using red fuming nitric acid during RDX nitrolysis is a no no because of thermal runaway. Off the top of my head I'm not sure about HMX but to be on the safe side I would just use white fuming nitric.

By the time I got around to the second nitrolysis run, the clear acid had turned light yellow despite being stored in a fridge but i used it and had no issues.

[Edited on 28-1-2021 by greenlight]

AndraDoria 13 - 13-5-2021 at 08:19

You did a great job, thank you.
But are we sure the product is pure hmx? I suspected it to be MNX

caterpillar - 15-5-2021 at 12:17

Quote: Originally posted by greenlight

Using red fuming nitric acid during RDX nitrolysis is a no no because of thermal runaway. Off the top of my head I'm not sure about HMX but to be on the safe side I would just use white fuming nitric.

By the time I got around to the second nitrolysis run, the clear acid had turned light yellow despite being stored in a fridge but i used it and had no issues.

[Edited on 28-1-2021 by greenlight]

I made RDX, using RFNA (it was yellow, as a matter of fact). But I used hexamine dinitrate, not hexamine.

greenlight - 15-5-2021 at 12:33

Quote: Originally posted by AndraDoria 13

You did a great job, thank you.
But are we sure the product is pure hmx? I suspected it to be MNX

Looks like a melting point test is in order then considering I don't have any super advanced equipment like an FTIR or NMR.

greenlight - 15-5-2021 at 12:35

Quote: Originally posted by caterpillar

Quote: Originally posted by greenlight

I made RDX, using RFNA (it was yellow, as a matter of fact). But I used hexamine dinitrate, not hexamine.

That is very interesting, I have always heard that white acid must be used, maybe it is a myth after all.

caterpillar - 15-5-2021 at 23:41

Quote: Originally posted by greenlight

Quote: Originally posted by caterpillar

Quote: Originally posted by greenlight

I made RDX, using RFNA (it was yellow, as a matter of fact). But I used hexamine dinitrate, not hexamine.

That is very interesting, I have always heard that white acid must be used, maybe it is a myth after all.

Try this: 5.15.1.3 Nitrolysis of hexamine with ammonium nitrate – nitric acid (CH2)6N4 + 2 NH4NO3 + 4 HNO3 2 RDX + 6 H2O (Eq. 5.24)
This method is known as the K-process after its discoverer K¨offler.201 Like method 5.15.1.2 it uses ammonium nitrate to compensate for the nitrogen deficiency in hexamine and works to Equation (5.24) where two moles of RDX are produced per mole of hexamine. As observed
with method 5.15.1.2, the addition of ammonium nitrate to nitric acid appears to prevent dangerous oxidation reactions from occurring. In fact, this nitrolysis reaction only occurs at elevated temperature and so a constant temperature of 80 ◦C is usually maintained throughout the reaction. Yields of approximately 90 % are attainable based on one mole of hexamine producing two moles of RDX. And hexamine dinitrate is always better than hexamine.

greenlight - 4-8-2024 at 06:34

Hello fellow EM chemists,

I am revisiting this method of HMX synthesis for two reasons:

1. To see if the entire process is scaleable x 6.

2. To get a purer recrystallised sample of HMX to obtain a better melting point to assess purity. I have purchased a melting point apparatus.

I have a 150g urea nitrate batch just dry and ready to be reacted with sulfuric acid to nitrourea.

DennyDevHE77 - 4-8-2024 at 21:45

About a year ago I posted an article where DPT for HMX was synthesized through descaler rather than nitrourea, but for some reason everyone is chasing nitrourea....

There she is https://www.sciencemadness.org/whisper/viewthread.php?tid=15...

[Edited on 5-8-2024 by DennyDevHE77]

greenlight - 5-8-2024 at 10:41

That is a very interesting read with some thorough experimentation included.

At the time this thread was made I had no idea there was another method out there. This procedure was very attractive at the time due to acetic anhydride not being required which is a win considering the high level of restriction applied to it in the majority of countries.

I believe this route is popular due to the fact that high strength nitric acid is only required once for the last step. Nitric acid is difficult to acquire in quantity for a lot of home chemists.

There are disadvantages in this method though as stated in the link. The large quantity of formaldehyde required versus DPT yield. Secondly, a large quantity of sulfuric acid is required for the nitrourea synthesis.

I am interested to see how this method goes when scaled up and the purity of the final HMX after recrystallisation though as I never got that melting point

[Edited on 5-8-2024 by greenlight]

[Edited on 5-8-2024 by greenlight]

ManyInterests - 6-8-2024 at 15:27

This thread is interesting because I also have an interest in synthesizing RDX and possibly HMX (they are related compounds if I am not mistaken). The main issue I have with RDX is that for some reason or another, I am having a hard time making WFNA (1.50 SG), Maybe it's because my sulfuric acid was diluted from storage, I am not sure. I did not redistill my nitric acid with sulfuric acid yet, but that would probably fix my issue.

Quote:

That is very interesting, I have always heard that white acid must be used, maybe it is a myth after all.

Quote:

I made RDX, using RFNA (it was yellow, as a matter of fact). But I used hexamine dinitrate, not hexamine.

Isn't RFNA around 85% to 95% concentration? And since I never used hexamine to make the little RDX that I did make, maybe HDN with that concentration + some freshly dried ammonium nitrate added to it (which I have plenty of now) maybe that would work? I was able to make that concentration well enough.

greenlight - 7-8-2024 at 08:42

Quote: Originally posted by ManyInterests

This thread is interesting because I also have an interest in synthesizing RDX and possibly HMX (they are related compounds if I am not mistaken). The main issue I have with RDX is that for some reason or another, I am having a hard time making WFNA (1.50 SG), Maybe it's because my sulfuric acid was diluted from storage, I am not sure. I did not redistill my nitric acid with sulfuric acid yet, but that would probably fix my issue.

Quote:

That is very interesting, I have always heard that white acid must be used, maybe it is a myth after all.

Quote:

I made RDX, using RFNA (it was yellow, as a matter of fact). But I used hexamine dinitrate, not hexamine.

Yes the two are related and similar in structure, they are also often present in small percentage as by-products of each other's synthesis.

Definitely redistill if you think your acid isn't concentrated enough with an excess of fresh sulfuric to eliminate any variables on that side of things. I believe the distilled nitric is above 90% when done properly and yellow in colour with a lot of fuming when in an open vessel.
Bubble some dry air through it and the resulting acid will be crystal clear.

Have you tested the density of your acid? A few drops of high concentration nitric in contact with nitrile gloves will cause them to self ignite.

The addition of ammonium nitrate during nitrolysis is a very interesting mechanism. It definitely works well for HMX and it is the ammonium cation in solution which is thought to enhance the yield although the cation makes a difference too with the nitrate salt responsible for the best results. There is a paper I have read that investigates this mechanism and lead to those conclusions running side by side tests.

ManyInterests - 7-8-2024 at 18:41

Quote:

Definitely redistill if you think your acid isn't concentrated enough with an excess of fresh sulfuric to eliminate any variables on that side of things. I believe the distilled nitric is above 90% when done properly and yellow in colour with a lot of fuming when in an open vessel.
Bubble some dry air through it and the resulting acid will be crystal clear.

Have you tested the density of your acid? A few drops of high concentration nitric in contact with nitrile gloves will cause them to self ignite.

So in the last few times I made nitric acid, when it had a specific gravity indicating above 75% it was red due to NO2 contamination (hence why a redistillation is required). I made methyl nitrate recently with some HNO3 that I measured at with a specific gravity of 1.493, but it was red in color (and all NO2 was purged fully when I added the sulfuric acid).

I rarely tried to react my HNO3 with nitrile gloves. For a bit I didn't trust even vinyl gloves, but an incident were one little drop landing on my hand that left me with a noticeable scar really made me want to wear gloves. I tested that batch (which was around 87% according to the specific gravity) on a nitrile glove and I put a minute bit (barely a visible drop) and it burned a sizzling hole in nitrile glove (did not ignite that time, but I think if I used a bit more it would have ignited). A larger drop on PVC kitchen gloves, however, only left a purple stain. So I wear double layers of PVC gloves ever since when handling nitric acid or a strong nitrating mixture.

For bubbling dry air, I did do that once and I did make my nitric acid crystal clear, but its specific gravity dropped. This is despite using a wash bottle with calcium chloride and a makeshift attachment to my air pump (I used one of those air mattress pumps, but I put an attachment also filled with dry calcium chloride on the air intake).

So basically if it burns nitrile gloves when purged of NO2, it is good enough for RDX?

greenlight - 8-8-2024 at 09:11

I have never measured the specific gravity of the distilled and purged acids. I have just trusted them by the appearance and properties.

That's interesting about the PVC gloves, I have always chosen to not wear gloves when handling high strength nitric due to the fact I would rather wash it straight off with water if any contacted my skin instead of remove melted burned gloves from my hands.

Was you nitric acid still highly fuming after you had bubbled dry air through it?
I just put my air pump (aquarium pump) into a dessicator bowl and covered it in calcium chloride when performing the NOx removal.

I don't think it's that rudimentary, but if it burns nitrile gloves when distill it's a good sign the concentration is high. Below I have attached two photos of about 0.3 ml of red fuming distilled nitric acid pipetted onto a nitrile gloves. The first photo is approximately 2 seconds after contact and the second photo a second later when ignition took place.

[Edited on 8-8-2024 by greenlight]

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ManyInterests - 8-8-2024 at 17:33

Nurdrage and Nile Red on youtube have shown that disposable vinyl gloves will stand up to WFNA. I tested kitchen PVC gloves (since they are much thicker and also grip better) and the acid also did not penetrate the outer layer.

When I got the acid on my hand, I plunged my hand into a bicarbonate bath and got a bottle of bicarbonate solution and it did nothing. I still ended up with a scar on my hand.

But getting past that, so you are more concerned with the reactivity of the acid than the weight/volume? I will try that, it could make my life easier if it'll still make RDX and PETN with the nitric acid acid alone. I haven't bubbled air through acid in a while. I still have some fuming acid, but I won't be using it for a while. I might test it on that. I got a little bit of yellow stains on my fingers (didn't even notice) when I realize the fumes had escaped from the bottle and apparently coated the sides and bottom. Good thing I kept it on sheets of aluminum foil otherwise it would have burned my floor!

DennyDevHE77 - 9-8-2024 at 00:25

I don't really understand why everyone is paying attention to this. I've had fuming nitric acid on my skin many times. The result was always in the form of yellowed skin or small ulcers later, also yellow. But it never caused any painful feelings. The most inconvenient thing was that, for example, a nail dyed yellow would have to grow back before it returned to its color.

Microtek - 9-8-2024 at 11:10

Measuring specific gravity of red nitric acid is not a reliable way to assessing the concentration. The dissolved NOx alters the density. So the reason the density of your acid dropped when you bubbled dried air through it was that you had less concentrated nitric acid with dissolved NOx and when the NOx was purged, the true density could be measured.

In many reactions you can use less concentrated acid with only a minor drop in yield, but I would recommend getting rid of the NOx contaminant in most cases.

greenlight - 12-8-2024 at 10:38

@Denny, I agree, the worst you get is a yellow stain on your skin that peels off a few days later as dead skin. There are much worse solution one could spill on themselves.

@Microtek, agreed, I always get rid of any NOx in the acid before using it in nitrolysis, I feel like it lessens the chance of temperature spikes and runaways.

An update:
Just reacted 150g of urea nitrate with 550ml of 98% sulfuric acid over the course of a few hours. Hate this dehydration reaction as its so hard to keep the temperature around zero even with metric tons of ice.
The filtered nitrourea product is drying now.

ManyInterests - 14-8-2024 at 15:20

Quote: Originally posted by DennyDevHE77

I don't really understand why everyone is paying attention to this. I've had fuming nitric acid on my skin many times. The result was always in the form of yellowed skin or small ulcers later, also yellow. But it never caused any painful feelings. The most inconvenient thing was that, for example, a nail dyed yellow would have to grow back before it returned to its color.

I have a scar on my left hand that is a reminder of the dangers of that. I am not sure if it was something else in the acid that caused it to burn through my skin, and this was even after I had immediately plunged my hand in a bicarbonate solution and started to pray it relentless with bicarbonate spray (before running to the faucet and letting cool water run on my hand for a minute or so.

So I must beg your pardon, but I will need to take caution with all material.

greenlight - 19-11-2024 at 09:22

Just finished the step from nitrourea to DPT on larger scale.

This time, 40 grams of nitrourea was dissolved in 500ml of 37% formaldehyde and heated until dissolution occurred.
Sodium hydroxide solution (5%) was added to the straw yellow clear solution until pH 3 was achieved.
The solution was heated to 65°C and held for just over an hour before cooling in a water bath.
Aqueous ammonia (25%) was added dropwise with stirring until DPT crop precipitated and was vacuum filtered before repeating this base addition two more times.

The DPT product was very light tan in colour this time which indicates some impurity that may have been formed when the temperature reached 68°C at one point or the high acid content of the nitrourea used could have caused this.
A recrystallisation is probably the way to go before proceeding further.