Sciencemadness Discussion Board - PETN imposter?

PETN imposter?

twelti - 13-5-2019 at 09:39

I made some "PETN" using method outlined by quicksilver, based off of Urbanski nitration tables I think:

***********
for PETN synth
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Verified efficient method of preparing PETN from diluted HNO3

use
32,7 ml of 70% HNO3 (75% excess)
18,9 ml of 96% H2SO4
10,0 g of Pentaerythrite

Finely ground PE. Kept between 10-15 deg during addition of PE (didn't seem to heat up much actually). After 20 min, heated to 50 deg for 20 min, crashed in water and recrystallized using acetone. Looks good and yield around 85%. Just cant get it to do anything! Wrapped in foil, taped to hammer on steel: occasional feeble spark one out of maybe 20 tries. heated in foil: fsssst. dropped on hot foil: deflag and no residue. I tried to measure the temp of the foil using IR thermometer, but i'm not sure it works right. I tried 200 mg of it with 80 mg ETN/SADS in a paper tube with some fiberglass strapping tape for at least a little confinement. Didn't seem to detonate.

I recrystalized it again just in acetone, slowly evaporating to get long crystals. broke those up and retested, thinking it might be more sensitive. Nope. Everything I have read indicates that it should not be lower nitrates, after crashing in water and recrystalizing.

What I have read is that it should "make a crackling sound" in a mortar.
I tried that too, nope, nothing.

What do I have here? Should i give up and make some WFNA? I was hoping to avoid that.

MineMan - 13-5-2019 at 19:35

I just tested my PETN in a motor. No cracking.

twelti - 13-5-2019 at 22:48

Quote: Originally posted by MineMan

I just tested my PETN in a motor. No cracking.

Did you make yours the same, w/o WFNA?

FeedMe94 - 14-5-2019 at 00:17

Quote: Originally posted by MineMan

I just tested my PETN in a motor. No cracking.

Same here

twelti - 14-5-2019 at 07:07

Clearly there is something different bout how they made theirs (I think I read that in Davis, which came from Naoum). I also don't think mine will DDT from 2 kg at 20 cm, or "a Carpenters hammer on s concrete floor" !!
WTF?

hissingnoise - 14-5-2019 at 11:45

Quote: Originally posted by twelti

32,7 ml of 70% HNO3 (75% excess)
18,9 ml of 96% H2SO4
10,0 g of Pentaerythrite

What do I have here? Should i give up and make some WFNA? I was hoping to avoid that.

It's likely that you have a mixture of lower nitrates since that small quantity of MA wouldn't have produced a high enough concentration of NO₂⁺ ion to fully nitrate 10 grams of substrate...

More HNO₃ and lots more H₂SO₄!

underground - 14-5-2019 at 13:00

Cleaning the PETN with plenty of water it will remove any lower nitrates.

twelti - 14-5-2019 at 14:23

I thought those were the verified amounts? I believe others have used it.
...and I thought the lower nitrates were soluble in water. They are for ETN, and as far as i could find, also for PETN. It can't be unreacted PE, since that is not soluble in acetone.

There has been mention of "sulfo-esters" but not sure what they are or if they are soluble.

Will try more NA and lots more SA and see. It will certainly make the mix thinner.

MineMan - 14-5-2019 at 22:43

I think your PETN is fine. Just wash it with water. Let it dry and hit it on sandpaper with a hammer. Taping the PETN with foil to the hammer. Better yet. Mix in some Al. Or just try to detonate it!! If you followed that procedure. You should be good.

Herr Haber - 15-5-2019 at 04:31

Ratios should be closer to 6 (H2SO4) 4 (HNO3) and 1 (PE) with those concentrations you are using.

twelti - 15-5-2019 at 11:33

Quote: Originally posted by MineMan

I think your PETN is fine. Just wash it with water. Let it dry and hit it on sandpaper with a hammer. Taping the PETN with foil to the hammer. Better yet. Mix in some Al. Or just try to detonate it!! If you followed that procedure. You should be good.

Haven't tried the sandpaper or aluminum, will do.

twelti - 15-5-2019 at 11:41

Quote: Originally posted by Herr Haber

Ratios should be closer to 6 (H2SO4) 4 (HNO3) and 1 (PE) with those concentrations you are using.

Is that ml/ml/g ratio, or by weight? Will try.

Regardless, I'm mystified as to what this material IS (?!). Yield and solubility is as expected for PETN. I keep wondering about crystal size. I know that affects sensitivity, but I did reX it to larger crystals and it didn't seem to matter. Maybe there is a small amount of impurity that is reducing sensitivity. For example unreacted PE. If the amount was small enough, it might dissolve in the acetone and get through the purification washing and Rex I did. I maybe should look into a more precise melting point assessment. Maybe I should grind the PE longer too. I did grind it for maybe 10 mins in a mortar before the synth. Do I need a ball mill...?

MineMan - 15-5-2019 at 11:45

No. You don’t need a ball kill. You need 30 seconds of grinding. Twelti I understand your frustration... but are you SURE you don’t have PETN? Mix some with aluminum and PP and try burning it. Hit it harder with a hammer. Put some SADS on it. A lot if you have to!

markx - 15-5-2019 at 15:00

Electrical coffee grinder works wonders on pulverizing raw materials. Beats a mortar and pestle by light years. Just do not use it on something that does not like mechanical manipulation.

Omit the heating step to 50C. It does nothing for your yield and only increases the risk of thermal runaway. The combination with mixed acids is rather prone to that scenario.

twelti - 15-5-2019 at 15:54

Quote: Originally posted by markx

Electrical coffee grinder works wonders on pulverizing raw materials. Beats a mortar and pestle by light years. Just do not use it on something that does not like mechanical manipulation.

Omit the heating step to 50C. It does nothing for your yield and only increases the risk of thermal runaway. The combination with mixed acids is rather prone to that scenario.

That is interesting. I'll try that. One thing I noticed in 2 synths so far is that I never felt that I was very close to thermal runaway. I WAS cautious, and added only a gram or two of PE at a time, but the temp barely budged from 10 deg. Actually, the first time i did it, I didn't realize that the stir bar was no longer moving. So it sat there for a few minutes w no stirring. When I noticed it, there was a hint of orange fumes in the beaker, so maybe I did get close!

Herr Haber - 16-5-2019 at 05:20

Quote: Originally posted by twelti

Is that ml/ml/g ratio, or by weight? Will try.

Use whatever unit is most convenient. In this case let's go for grams.
1 PE, 6 H2SO4, 4 HNO3
68% HNO3 weights 1,41 grams /ml
96% H2SO4 weights 1,84 grams /ml
1 gram of PE weights... well 1 gram

Microtek - 16-5-2019 at 10:54

How certain are you of the concentration of your acids? You could do a titration with something like recrystallized benzoic acid as your primary standard. Or just make a small amount of fuming nitric acid to make a small amount of authentic PETN to compare against your mystery sample.

caterpillar - 16-5-2019 at 16:40

All methods that I read about required concentrated HNO3. It is not a great problem to prepare it, but you may try NH4NO3 dissolved in H2SO4 instead.

twelti - 16-5-2019 at 18:34

I could check the density of the HNO3, right?. I don't have any FNA, though I'm starting to think I should just bite the bullet and make some. I did try the sandpaper and hammer MineMan mentioned. It does seem to at least partially detonate then.

markx - 16-5-2019 at 23:27

Can you conjure up a way to measure the melting point? It should be close to 140C for the desired end product. Heat gun and IR thermometer combination can not be accounted as a viable option for that purpose.
Also it would be a wise approach to construct a simple hammer drop tester. Just a frame to hold the weight and a scale (measure tape .e.g) to note the height. The weight can be dropped via a quick release (just a pin connected through the weight and support frame). That and a reasonable assessment on m.p. would take a lot of "iffiness" out of the discussion.
Hitting a sample manually with a hammer is at best going to reveal if it has any energetic properties at all, but even that not with reasonable repeatability.

OneEyedPyro - 17-5-2019 at 01:37

I had a similar experience with PETN the first time I made it.
I was pretty sure I had lower nitrate contamination or something else going on.

Turns out I did in fact have PETN, I was just expecting much greater sensitivity.
When I actually tried to detonate it with a primary, it fully detonated and when I did a lead block test it left a dent just about identical to the same volume of pressed ETN.

Try taping a small amount to a hammer in a foil pouch as MineMan said, but heat it up a bit and smack it on a hard rounded surface (like a large diameter steel pipe or something similar). It should give a nice pop.

twelti - 17-5-2019 at 08:36

I tried to test MP on foil on a burner, but I don't think the IR thermometer works on it, as i could only seem to get it up to 70 deg. I do have a thermocouple around here somewhere (from another hobby) and might try that. I'm definitely going to make a drop tester, for this and some other primaries I'm interested in (including AG Nickel Perchlorate which I just made).

I had a similar experience with ETN too. I'm starting to thing this IS PETN. i made a foil tube with 600 mg of it, and 200 mg of ETN to kick it. Will find out this weekend.

twelti - 21-5-2019 at 19:34

I got a "smoking gun"! 40 mg of nickel aminoguanidine perchlorate and 500 mg of the PETN in question, lightly pressed. Galvanized steel plate from a conduit box (approx 1.5 mm thick - too thick to bend manually at all) was deformed maybe 9 mm. No way the 40 mg AG complex did that!

So, this stuff really is not that sensitive as I thought.

[Edited on 22-5-2019 by twelti]