Nitroisobutylglycerol Trinitrate

<center><b><font size="5">Nitroisobutylglycerol Trinitrate</b></font></center>
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<table width="80%"><tr><td><center><img src="http://www.sciencemadness.org/scipics/axt/nibgtnstruc.jpg"></center></td><td><table border="1"><tr><td width="70"></td><td width="70"><b><center>NIBGTN</center></b></td><td width="70"><center>NG</center></td></tr><tr><td><center>Density</center></td><td><ce nter><b>1.68</center></b></td>
<td><center>1.60</center></td></tr><tr><td><center>VOD</center></td><td><center&g t;<b>7860</center></b></td><td><center>7600</center></td></tr><tr>
<td><center>%OB</center></td><td><center><b>0</center></b></td><td><center>+3. 5</center></td></tr><tr><td><center>Gas (L/Kg)</center></td><td><center><b>769.7</center></b></td><td><center>781.1</center> </td></tr><tr><td><center>Gas (L/L)</center></td><td><center><b>1293.1</center></b></td><td><center>1241.9</center> ;</td></tr><tr><td><center>Lead Block (%TNT)</center></td><td><center><b>180</center></b></td><td><center>173</center>< /td></tr><tr><td><center>Brisance (%TNT)</center></td><td><center><b>195</center></b></td><td><center>170</center>< /td></tr><tr><td><center>Power (%TNT)</center></td><td><center><b>200</center></b></td><td><center>185</center>< /td></tr><tr><td><center>MP (°C)</center></td><td><center><b>-35</center></b></td><td><center>+13</center></ td></tr><tr><td><center>Droptest</center></td><td><center><b>6cm</center></b>< /td><td><center>2cm</center></td></tr></table></td></tr></table></center>

Figures in table were taken from <i>Chemistry of Powder and Explosives</i> (Davis), <i>Encyclopedia of Explosive and Related Items</i> (Fedoroff, Sheffield) and <i>Explosives</i> (Kohler, Meyer), Synthesis was adaptated from a PETN synth in COPAE.

Effectively, NIBGTN is to NG what PETN is to ETN. NIBGTN is a viscous yellow liquid with a structure very simular to PETN and is made much the same way, but by substituting acetaldehyde for nitromethane. While all the values in the table above look good, doesnt freeze easily, less sensitive with higher energy/brisance then NG, effectively its just another explosive oil that leaves you wondering ... if it was only a solid. It provides a greater lead block test expansion of 540cm³ compared to NG's 520cm³ even though the test is biased due to being used on 10g weights, a 10cm³ volume sample would give more accurate comparisons for constant density liquids, in which case NIBGTN would take a greater lead due to its high density.

Like NG, NIBGTN also suffers from low velocity detonation and gives headaches if touched though notas readily as NG. NIBGTN may find uses in compositions as an energetic liquid additive that wont alter the oxygen balance of the mix, NIBGTN is not used commercially due to its chemical instability and subsequent decomposition in storage. With this in mind, storing NIBGTN probably isnt a good idea.

Synthesis is straight forward, nitroisobutylglycerol, C(CH2OH)3NO2, is formed by the reaction between 3 moles of formaldehyde with 1 mole of nitromethane with a potassium carbonate catalyst. Its then a normal H₂SO₄ / xNO₃ nitration of the solid precipitate to form NIBGTN.

<b>Condensation to NIBG</b>

This is a simular process to the creation of pentaerythritol from acetaldehyde for PETN and Hexamine from ammonia for RDX. Here formaldehyde is condensed "joined" with the three active hydrogens within the nitromethane molecule, replacing it with the group -CH₂-OH, thus creating three nitratable hydroxyl groups.

2g potassium carbonate is dissolved into 200g 30% formaldehyde in a 600ml beaker, this is cooled to 10°C, to this is slowly poured 50gm of nitromethane, DO NOT STIR!, the mixture will seem to be doing nothing for about 5 minutes when a vigorous, short (~2 sec.) reaction will froth up in the beaker therefore make sure the beaker can accomodate this! (First time I did this I stired the mixture and it ejected about 30cm into the air!). Allow the solution to heat up to around 75°C where it is held for five hours using a hot water bath. After the five hours the solution will have evaportated to about 100ml, the solution is then cooled to 10°C and a dark orange precipitate of NIBG forms producing a solid gelatinous slurry,Scoop the orange solid out, place in a piece of fabric and squeeze out as much moisture as possible. Place the extract onto a piece of newspaper for drying.

<center><img src="http://www.sciencemadness.org/scipics/axt/nibg.jpg"></center>

Note that I also tried to purify the product by using excess NM and boiling the aqueous solution, the solution turned black and smelt of burnt sugar! dont do that.

Theoretically you would extract 2.48g NIBG for every gram of NM, but that assumes no loss of nitromethane/formaldehyde through evaporation, unless you want to spend a lot of time and effort its easier to extract about 1g for 1g and tip the rest down the sink you will also end up with a more pure product if you do this by leaving the more soluble carbonate catalyst and monomethylol/dimethylol (they may even be liquid?) products in solution. The picture above is the condensation reaction sequence showing liquid mixture after the initial violent reaction, mixture 2 hours into the reaction and drying of the final yield. Once dry the NIBG should be white to light yellow needle shaped crystals.


<b>Nitration to NIBGTN</b>

Nitration bath is created by combining 100ml 70% HNO₃ to 200ml 95% H₂SO₄, 60g NIBG was added slowly to the mix <img src="http://www.sciencemadness.org/scipics/axt/nibgtn.jpg" align="right"> with temperature maintained between 0-10°C by cooling with water / ammonium nitrate. After the last addition the mix is left with frequent stiring for 15 min. The mix is then dumped into water, the NIBGTN will form a amber layer on the bottom of the jar. NIBGTN seemed to seperate easily from the mix but left an unknown milky layer between the NIBGTN and the water.

The acid/water layer on top of the NIBGTN is decanted off and a solution of water/sodium carbonate is poured over the explosive to neutralise any residual acid. This was done twice until it stopped fizzing. I did not stir the mix in case it formed an emulsion but simply left it overnight, extracted it with a syringe and fired it on that day.

Theoretical yeild is 1.89g NIBGTN per 1g of NIBG, I only recieved about 1.2g after washing. The picture to the right shows the yield after two nitrations using the above precedure, about 85ml or 143g.


<b>Detonation</b>

Detonation follows the equation -

<b>C₄H₆N₄O₁₁ ---> 4 CO₂ + 3 H₂O + 2 N₂</b>

Thus, perfect oxygen balance. A detonation results from the use of thin glass containment and #8 strength (0.5g PETN) initiation. Below is the detonation of 25ml NIBGTN carried out on a lead witness plate measuring 25x35x50mm, result was complete plastification of the metal, splat! as if it was plasticine. Even with that result, it is unlikely that the charge performed to the properties in the table above, half a millimetre of glass containment is unlikely to give its highest performance. The grey smoke was somewhat unexpected and may indicate impurities.

Note the cardboard box next to the charge with a circle drawn on it, my intention was to use this as a test of brisance by counting the number of holes produced from fragments of the casing. No holes were it the box at all! only ripped from the blast. It was only 2.5 feet from the charge. The casing would have to be brittle for this test to work so I thought the glass vial would do. Must have been too thin as there wasnt even a speck through the box.

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[Edited on 9-12-2005 by Axt]

[Edited on 9-12-2005 by Axt]

Better than NG but less than PETN.

Assuming it is a polyol...suffering from the same kind of troubles than PETN...I would use HNO3 99-100% and avoid H2SO4. To see if yield is better.

Maybe a recristallisation of the nitropolyol would have helped getting something purer.

The milky layer comes from the fact you have used HNO3 70% and H2SO4...partial presence of uncomplete nitrated compounds (dinitrate and mono nitrate + oxydation products accounts for amphiphilic character and intermediary layer).

No doubt the proces might be improved but it is a nice first try.

Alternative trials are O2N-CH2-CH2-ONO2
O2NO-CH2-CHNO2-CH2-ONO2 wich should have similar properties.

Optimum is:
O2N-CH2-CH2-NO2 --> (HOCH2)2C(NO2)-C(NO2)(CH2OH)2
wich can be tertanitrated, perfect OB.
Since it is a kind of dimeric form of your NIBGTN...it will display a better output since denser.Lower or equal sensitivity.

Reduction of the nitropolyol to amino might be also something interesting to investigate...the result will be cristaline and relatively unhygroscopic.
O2NOH.H2N-C(CH2ONO2)3
Anionic exchange will allow the fromation of the perchlorate salt.
Treatement with HNO2 will lead to deamination and formation of an alcool group.
HO-C(CH2OH)3 wich can be tetranitrated
Power >or= to PETN; OB>0.
Reaction with formol will lead to a triazacyclohexane ring but with 1/2 ratio to
(O2NOCH2)3C-NH-CH2-NH-C(CH2ONO2)3
which can be dinitraminated for a high density cristaline moderately sensitive and powerful explosive...
Of course one step nitration is possible if the aminopolyol is reacted with formol in teh appropriate ratio.

Of course a urea is also possible and then dinitrourea related compound...
(O2NOCH2)3C-NH-CO-NH-C(CH2ONO2)3

Great Stuff!


Anyway, your nitroisobutyleneglycerol is described/shown as a orange precipitate. THis is a tad confusing (unless I misunderstand something) because in your own reference, in the prev. post, it says it's a colourless solid... doesn't sound like a 100% clean product to me
Also, according to your reference, it states a solubility of 220g/ml, and judging by your amount of starting material, plus your final stated volume of 100 ml water, I don't see how you could have purified that much. Am I missing something, once again?

At last...

I´ve tried this synthese more times with very similar results...my product wasn´t fully stable - it usually produced some NO2, but there wasn´t any vigorous decomposition after two months storage.
The yellow layer seems to be the hated emulsion - when the NIBGT was vigorously stirred in the separating funnel with the washing liquid, it turned to the same yellow viscous liquid and I had to extract it with CHCl3...
I´m trying to eliminate these "emulsion problems" by reaction and washing in an inert solvent like CH2Cl2...
Best use of NIBGT is a plasticizer for nitrocelulose in some plastic explosives - for example 31,5% NIBGT + 3,5% NC + 65% RDX gives much deeper hole (>4mm in my test on the steel plate) than inert-plastified RDX (3,2mm). Observed density was 1,67g/cm3 so VoD had to be high (over 8000m/s).

I think orange impurities can destroy stability of final product, it´s better to recrystalise "orange NIBG" from water or ethanol with some decolorizing agent (active carbon).

I tried to prepare NIBG by another way:
reaction of NM with paraformaldehyde in ethylacetate (no exotherm!) and then destile out ethylacetate until NIBG begins to crystalize. Add mixture of ethylacetate/trichlormethane and boil it for 30mins - there will be some brown viscous liquid on the bottom of the flask, so decant hot solution, add some active carbon and filter. Then cool it and the white or pale-yellow NIBG will crystalize out.
Yield was 45g NIBG from 54g paraformaldehyde and 36g nitromethane, but it was only first time - next charge was quite poor...
Now I don´t make this because problems with stability and low final yield, but I can´t find another energetic plasticizer as good as NIBGT