Results of my NTO synth.

[Mr Cool]

The method I used was taken from US patent number 4,733,610.
I used 98% pure semicarbazide hydrochloride, 68% HNO3, and formic acid produced by distilling oxalic acid (dihydrate) with anhydrous glycerol.
I scaled down the ratios to use 15g of semicarbazide hydrochloride.

However, I messed it up. Since the oxalic acid used was a dihydrate, the crude formic acid produced was only around 60% pure, but I didn't think about this so I didn't concentrate it!!
This resulted in a low yield of triazolone.
When the HNO3 was added, the temp. shot up to around 65*C before I had a chance to put the flask into cold water (ambient temp was around 23*C), the reaction temp rose to 72*C, and lots of NO2 was produced. After about 10 seconds of sitting in the cold water bath the reaction died down to a slight fizzing, and the temp had dropped to around 45*C. I heated it to 60*C (+/- c.5*C) for 1.5 hours, under reflux. Small amounts of NO2 were given off, and I think a colourless gas was also given off in small quantities. This I assume to have been CO2, and I also assume it to have been a bad sign.
After this time, I placed it in the freezer and cooled it to -5*C. The product was filtered, washed with 15mL of water at 0-1*C, and air dried. The yield was only 3.2g (yet to be detonated).

Yields of up to around 90% are claimed in the patents. I can think of three things that may have gone wrong in my attempt:
1) The low concentration of formic acid produced a low yield of triazolone, and left unreacted semicarbazide hydrochloride.
2) The reaction got very hot (due to unreacted semicarbazide hydrochloride?), which may have caused oxidation of the triazolone.
3) The reaction may have been over more quickly due to the initial high temp., and the heating for 1.5 hours may have caused decomposition.

This explosive is about equal in performance to RDX, but substantially more thermally stable. It is less sensitive than TNT, but more so than TATB.
It does not require 99% HNO3, or any other exotic chemicals. The main problem is obviously the need for semicarbazide hydrochloride, although this can be made from urea in what appears to be an easy synth (look in the "Patents" thread in "Links and Literature").

I used up all my oxalic acid in that initial experiment. In probably about two weeks I will be getting some 98% formic acid, so I will continue my experiments then...

If anyone tries making semicarbazide hydrochloride from urea, or has anything else related to the manufacture of this explosive, please post.

[ALENGOSVIG1]

Too bad it didnt work out too well.

Ive read that a small amount of formic acid can be obtained by distilling red ants! :p
It can also be made by oxidizing methanol with potassium permanganate.
Did you make your semicarbazide hydrochloride or did you purchase it? Becuase everywhere i ask, its quite expensive.

[edit: realized the method i posted was the same one you used :) ]

<small>[ August 05, 2002, 04:47 PM: Message edited by: ALENGOSVIG1 ]</small>

[Mr Cool]

Yeah, it's a pitty that the yield sucked :(
I'll get it right when I get my formic acid. I can buy this easily at the moment, but if I'm ever short of cash... well, I never did like ants! <img border="0" title="" alt="[Wink]" src="wink.gif" />
I didn't make my semicarbazide hydrochloride this time, although I intend to do so soon. The synth looks very easy, with urea, bleach and ammonia (look in the "Patents" thread in "Links and Literature"). Nor did I buy it. It was a free sample <img border="0" title="" alt="[Wink]" src="wink.gif" /> My chem supplier sells it, £60/kg!!
If you make freebase semicarbazide, it can also be used to make azides, with NaNO2, which would be useful.
That synth is essentially the same as the one in the patent I followed. What concerned me was that a lot of NO2 was produced in the first few seconds, in the little runaway I had, but then very little was produced during the rest of the reaction.

[nbk2000]

On making formic acid:

Take what you get from the oxalic acid/glycerol distillation and react it with a carbonate. Crystallize and dry (at low heat) the crystals. Then distill these from concentrated H2SO4 to get the anhydrous formic.

I'm also curious where you got the semi from. Did you make it? You certainly have enough patents referrenced for all the precursors to it. That'd be cool if you did a total synthesis.

[Mr Cool]

A total synth from start to finish is my ultimate goal. I'm concentrating some 5% NaOCl bleach now, so that there isn't so much water in it since I'm going to have to use aqueous ammonia (or maybe a constant stream of ammonia gas, but that'd be smellier) to make the semicarbazide. The trouble is you can't boil off the water because you end up disproportionating the NaOCl (unless you're trying to make chlorates, of course <img border="0" title="" alt="[Wink]" src="wink.gif" /> ), so it's a slow process. I've even started assembling stuff for my electric HNO3 making device. It'll be amazing if that works, HNO3 at the flick of a switch!! It's based on one of those patents someone posted, although it'll probably be a batch process. Start an arc in air at increased pressure, with the (sealed) reaction vessel cooled to -15*C in the freezer, hopefully to produce liquefied N2O4, which will poured into another container with ice at -15*C. This'll be sealed off and allowed to warm up, and the N2O4/NO2 should dissolve in the water to form HNO2 and HNO3, then it'll be exposed to the air to convert the HNO2 into HNO3. I'll post progress in the appropriate section once work has started.

My initial experiments with NaOCl and urea are not encouraging though. Even with 5% NaOCl (bleach, I think that's the only active ingredient) at 3*C, adding solid urea produces a lot of bubbling. I'm sure this is CO2, although I haven't tested it, which would mean that it's making hydrazine instead. But I didn't manage to get any hydrazine out either!

[Pu239 Stuchtiger]

It's quite questionable how well the method of distilling formic acid with H2SO4 would work. I have tried mixing NaCH3COO with concentrated H2SO4 and then distilling, results were surprising... Immediately upon mixing it fizzled, and I smelled a peculiar, sweetish odor. Once I got a faint whiff of it - I choked, and coughed a lot for several minutes. The distilled product didn't freeze even at 0C. I think that the H2SO4 was dehydrating the formed CH3COOH to CH2CO (ketene gas), which was reacting with remaining CH3COOH to form acetic anhydride. The product probably was a mix of CH3COOH and (CH3CO)2O, but there certainly was some acetic anhydride present. So, formic acid may be dehydrated by heating it with H2SO4, which would result in complete destruction of the formyl group:

HCOOH + H2SO4 ----&gt; CO + H2SO4*H2O

<small>[ August 05, 2002, 07:53 PM: Message edited by: Pu239 Stuchtiger ]</small>

[Mr Cool]

Yes, I believe you are right. I think I've heard that formic and oxalic acids decompose in H2SO4 to give CO and H2O (and CO2 with oxalic).
Maybe a vac. distillation is possible?
If not, just distil it from anhydrous Ca(NO3)2 or CaSO4 a few times.

[PrimoPyro]

Urea + hypochlorites --&gt; hydrazine. Be careful, hydrazine is highly toxic. It's a mutagen and a lachrymator.

You might want to check the practicality of the air/electricity N2O4 generating system. Calculate how long it will take to produce only one mole of N2O4 at a given rate of operation. You'll likely find that it will take approximately 5 hours per mole or so. Sucks, don't it?

It's not exactly the type of device I'd leave running without supervision if you know what I mean. Fun 5 hours you're gonna have there. :D

[Mr Cool]

"Urea + hypochlorites --&gt; hydrazine. Be careful, hydrazine is highly toxic. It's a mutagen and a lachrymator."

I know, I am trying to avoid any free hydrazine. That is why I am using this method for the production of the semi., since with other methods you react hydrazine with urea. And I don't want to use nitrourea (reduction either with Zn/acid or electrolytic) because conversion of UN to NU is only around 60% most of the time, and it means you need a lot more chems.

Even if the HNO3 machine made one mole every 10 hours, that's 100mL/day! Enough for me! I wasn't expecting anything like 0.2 mol/h! I don't see why I'd need to sit there and watch it, the pressure used wouldn't be very high, and I'd build in some sort of pressure release system just in case the pressure did get very high due to heating from the arc. This will be a slow, low power device so I don't think heating will be much of a problem. A fire is very unlikely, since I'm toying with the idea of using CO2 to pressurise it, and the whole thing will be sitting in a freezer. Nothing to burn but ice at -15*C! The worst thing that could happen really is the N2O4 could spill into the freezer, which isn't used for food anyway, or I could get an electrical fault. If this happened in the transformer outside the freezer it could be a problem I suppose, but it wouldn't be able to set fire to anything except the transformer itself because it'll be on a concrete floor, with no combustibles around.
Well, we'll see. To be honest I don't expect it to work, but it might!

[Alchemist]

Hello all,

Mr. Cool and anyone else interested. If you read Vogels "Practical Organic Chemisrty"
Page 954, section VII,2 , it's on how to make SEMICARBZIDE HCL. It uses Hydrazine
Sulfate, Sodium Cyanate, and Sodium Carbonate. I believe this may be easier than the Pat. you found, as it uses Hydrazine Sulfate rather than Hydrazine itself!

Also I remember reading an article somewhere (I am still looking for it again), that Calcium Hypochlorite (higher
chlorine content) in the place of Sodium Hypochlorite for making Hydrazine/SO4 can increase the yield as much as 17%!

More later!

[Mr Cool]

I have a copy of Vogel's POC, I'll take a look.
Also I have 1kg of calcium hypochlorite, it says 35% available chlorine which means it's quite impure. It's from a chem. supplier, I think the impurity is just Ca(OH)2. I'll try it...
Thanks!

[Microtek]

I'm experimenting with NTO synthesis using exclusively OTC chems.
For preparing semicarbazide*HCl I am using patent number 5241117 according to which urea is reacted with NaOCl in solution. Note that NaOCl is added to a soln of urea in water not the other way round. Note also that it is important to use an excess of urea. This implies that if urea is added to NaOCl, hydrazine is produced due to the excess hypochlorite. Anyway, following the patent seems to work fine;
50 mL 15% NaOCl was added slowly to 9 g urea in 20 mL water while temp was kept at 7-9 C. No visible reaction took place at first but about halfway through the NaOCl addition, a slight cloudiness appeared. When addition was complete, the mix was allowed to sit for 30 min and 3 g ZnCl2 in 20 mL water was added to 50 mL 20% ammonia water. At this point an autoclave is preferred but not neccessary, so I just placed some kitchen film over the beaker and heated it to about 70 C. At this point the mix started bubbling quite a bit but very quietly. The temperature was kept at 70-80 C for 40 min, and then the film was removed and the volume was reduced by boiling. Then another 50 mL ammonia water was added to compensate for the missing autoclave and the procedure was repeated. At this point, I left the mix un-attended for too long and it was evaporated to dryness. It wasn't burnt however, so I just added some water and then acidified with HCl. After evaporating I am left with a mass of white crystals of unknown composition.
Now the question is, how do I purify the supposed semicarbazide*HCl?
For starters, it would help if someone could tell me the solubility of this compound in water, as all I have been able to find in various MSDSs on the web has been "solubility: appreciable" or " Freely " and frankly that isn't enough.
Some of the patents mention dissolving the free base in alcohol and then precipitating the HCl salt by adding anhydrous HCl, so I was wondering if I could react the semicarbazide*HCl with NaOH evaporate to dryness and extract the free base with isopropanol or ethanol.

[Mr Cool]

Good work, I always tried adding urea to NaOCl...
To purify the semicarbazide*HCl, you could try getting the freebase with NaOH, then forming a semicarbazone with acetone, filtering this off, and then hydrolysing back to semicarbazide, and adding HCl to precipitate it.
Maybe.

[Microtek]

Searching the chemical abstracts I found one that mentioned the solubility of semicarbazide*HCl in hydrochloric acid. The numbers were as follows:

5% HCl soln 531 g/L at 70 C and 322 g/L at 30 C
20% HCl soln 113 g/L at 70 C and 46 g/L at 30 C

This could be used by dissolving semicarb*HCl in hot water and then cool down and bubble HCl into the soln. This would precipitate the product while hopefully leaving most impurities in solution.

[Microtek]

I tested this hypothesis by treating a sample of the crude product with warm water, making sure that there was much more crystalline matter than could be dissolved, even at elevated temperatures. I then allowed the soln to cool to room temp and decanted the clear liquid phase into a fresh beaker.
I then bubbled HCl from a CaCl2+HNO3 generator into the soln. At first I had problems with the precipitated crystals clogging up the bubbler, but this was solved by using a bigger nozzle. After dinner, the soln was saturated and a great mass of white crystals had precipitated. Bubbling was stopped, the liquid was decanted and the crystals were drowned in isopropanol. After reducing the crystal size, the product was washed again with IPA.

[vir sapit qui pauca loquitur]

Just interested in how you were going to pressurise the vessel with CO2 ? I'm currently working on a working version that would automatically dump the HNO3 into a collection systm, i was going to have the acid dissolved into water/KOH solution but after reading the references i think the liquification process offers a better yield without fussing about. I have pressurised my reaction vessel to 2300 psi and had it running for a few hours (about 10) and after i calculated what amount of NO2 (hence HN03) was produced i thought i was wrong, but it seems like i wasn't after all !!

hopefully when i get enough time i'll be setting up the full system and pre-testing it, i advise that you flush the tubes etc with an inert gas before using electric spark as it wont be very nice if you're electric pressure pipe-bomb goes kablooie (i take as many precautions as i can b/c my next mistake will probably be my last if my next door asswipes hear anything, they take a dim view of anything too lively, maybe it'll give them a heart attack one day)

sounds promising though... if it goes well then i know what my next project is :D so best of luck!

[da man]

Microtek, this procedure looks very promising! Good work!
What was the yeild of semicarbazide hydrochloride?
Does the concentration of the sodium hypochlorite matter in the reaction with urea (would 5% ordinary bleach work)?
This could also be a safer and more economical route to sodium azide!

[Mr Cool]

It sounds like you got a good yield, although I think urea*HCl would also ppte with your semicarbazide*HCl, since an excess of urea is used...
What shape are your crystals? I could grow a larger crystal of the pure semicarbazide*HCl that I have, it might be useful in identifying the product.
I'm racking my brains trying to think of a way to purify it, but the only way I can think of is semicarbazone production followed by hydrolysis. I think you'll have to do this if you're making lead azide, to remove Cl-... I doubt it'd be worth it when making NTO if you only have a little bit of urea in there. Maybe it'd be better (easier) to purify it of urea after the formation of triazolone.
I'm going to go and buy some bleach now, to find out how well it works with 5% NaOCl...

[Microtek]

This sample was only a fraction of the batch, but 3.10 g was obtained from the HCl precipitation. The washed and dried product was introduced into 7 mL formic acid. This acid was produced by the reaction of oxalic acid dihydrate with glycerol. As the glycerol acts as a catalyst and CO2 is formed in the process, the product should contain 2 mol H2O to 1 mol formic acid. This would give 56 % acid soln, and as the patent called for about 1 mL 85% formic acid per gram of semicarbazide*HCl, I used about twice the amount.
The mix was heated to 60-70 C with stirring and more formic acid was added until all had dissolved. Then temp was raised to a gentle boil until crystallization began, and a little more formic acid was added to ensure excess. When cystals began to appear again, 10 mL water was added and the mix was concentrated until near dryness. At this point I had a little accident; the beaker fell over while I was concentrating it and some of the mother liquor was lost.
The crystals were washed in IPA and dried the rest of the way.
2.81 g of supposed TO was obtained. My calculations indicate that theoretical yield is about 2.4 grams so something isn't right.
15.3 mL 62% HNO3 was heated to 65 C and the crystals were added at such a rate as to keep the temp between 60 and 70 C. The mix foamed some when the crystals were added and the colour became darker, but essentially no NO2 left the liquid.
Temp was kept in the above interval for 60 min during which I observed a decrease in the bubbling, and beginning crystallization towards the end of the period.
The beaker was removed from the heater, and cooled to 0 C to complete crystallization.
The liquid was decanted and the product washed in IPA and a sample was dissolved in a little water and a few drops of AgNO3 soln was added, but no precipitate was formed. The same test was done with Pb(NO3)2 but again no precipitate.

[Mr Cool]

No ppte could be, in a way, a good thing. It shows that no chloride is present, which means that the chloride has gone from the semicarbazide HCl (obviously...).
I suppose it could have happened when you heated it with HNO3, but HCl should have been evolved when making triazolone from the semicarbazide*HCl. So it might mean that that step was successful...

[Microtek]

My thoughts exactly, but reading up on a few patents, I have found that the semicarbazide salt or free base is generally refluxed with formic acid for several hours to complete conversion. Due to the small amounts that I am working with, concentration only took about 15 min, so I'll probably need to employ a condenser.

PS. Mr Cool, I'm quite interested in that method you are referring to concerning lead azide from semicarbazide. Could you elaborate please?

<small>[ September 29, 2002, 06:06 AM: Message edited by: Microtek ]</small>

[Mr Cool]

Hmmm... yeah, try with a big excess of formic acid, and a reflux condenser, so that we can see if the product was in fact semicarbazide.
This has reminded me to buy some formic acid, I've placed an order so it should be here in a week or so.
The method for making azides is exactly the same as when using hydrazine; replace each mole of hydrazine with a mole of freebase semicarbazide.
NaNO2 + N2H4 --&gt; NaN3 + 2 H2O
NaNO2 + H2NCONHNH2 --&gt; NaN3 + CO2 + NH3 + H2O
If you ppted the semicarbazide as the nitrate, then you could dissolve it in dH2O, then add conc NaOH (aq) until it was just slightly alkaline, then add the conc NaNO2 (aq) until no more CO2 was given off, then a bit of dextrin, stir it all up to dissolve the dextrin, then add slightly basified conc Pb(NO3)2 (aq) until it stopped ppting Pb(N3)2.
Lead azide, via the "quick 'n' dirty" method <img border="0" title="" alt="[Wink]" src="wink.gif" />

[Mr Cool]

I've been trying this again, encouraged by finding OTC formic acid (limescale remover) which means it can be made totally OTC in theory which is what I want, and have been getting much better yields. There is still room for improvement, but recently I've been getting 2.5-3g of NTO per 5g of SCA*HCl (using only 13mL of 70% HNO₃ per 5g of SCA*HCl).
I have yet to determine the exact concentration of the formic acid I'm using, but it is strong enough to hurt your nose if you smell it. I'll do a quick neutralisation, to find how many moles of NaOH is required to neutralise Xg of the acid, this should give an accurate enough figure.
I've been taking more time over the first step than with my first attempt. I'm using 2mL of formic acid per 1g of SCA*HCl, distilling until the first signs of crystalisation appear, then adding 1.5mL of dH₂O per gram of SCA*HCl, again distilling until small crystals start to form, then pouring the mixture into an evapourating basin and heating it on a steam bath until just moist, then turning off the heat and letting it dry fully.
During the reaction large amounts of HCl are given off, an open bottle of ammonium carbonate near the flask collecting the distillate fumed strongly.
I editted the way I was doing the nitration after reading a different patent, H861, so now I preheat 70% HNO₃ to 60*C and add the dry product from the first step, keeping the temperature between 60*C and 70*C using a cold water bath when necessary. There is still quite a bit of bubbling and NO₂ given off, I think by-products/unreacted reactants are being oxidised, but the first patent I used said this was normal.
After chilling to 0*C, the mixture (which is yellow, but not quite right for the colour to be caused by NO₂ alone) must be left for a few hours to fully ppte the NTO, which appears as clusters of very small off-white crystals. It's appearance is unchanged after recrystalisation from water.
I'll take a few pictures next time.

So now I'm going to start work on SCA*HCl again. I'll be using the urea/hydrazine, or maybe NaOCN/hydrazine, method since I don't have a good source for strong ammonia solution and working with ammonia gas is a pain in the arse, having to dispose of the excess and not letting your reaction get sucked to where you don't want it as the ammonia dissolves in the liquid...

Edit: the formic acid is 55%, give or take a bit. The patent calls for 85%, but I used twice as much by volume so it's OK.

<small>[ March 01, 2003, 08:59 AM: Message edited by: Mr Cool ]</small>

[Mr Cool]

A sample of the dried product was pressed into a plastic drinking straw, roughly 6mm in diameter, to a depth of 25mm. On top of this were pressed 4mm of PETN and 1mm of AgN₃.
The witness plate clearly indicates a complete detonation (<a href="http://www.boomspeed.com/mrcool/NTOWitness.jpg" target="_blank">1</a>,<a href="http://www.boomspeed.com/mrcool/NTOWitness2.jpg" target="_blank">2</a>).

The product, when touched with a red-hot wire or a glowing splint, will rapidly and exothermically decompose, releasing a large amount of gas and white fumes, and ignites in larger quantities (or when ignited with a flame) to burn similarly to RDX, although it does have a habit of blowing itself out and continuing to decompose without flame when the source of ignition is removed.

If I can now make SCA*HCl in large quantities I think this will become my prefered explosive, because it is as powerful as PETN and RDX, it is safer than both of them, and requires less HNO₃ than both of them!

I'll have to get some hypochlorite pool stuff so I don't have to mess around with household bleach for making SCA*HCl...

Edit: link messed up, it should work now.

<small>[ March 02, 2003, 01:52 PM: Message edited by: Mr Cool ]</small>