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Raid
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any easy way to destroy peroxides?
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Baiuvarian
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Destruction of peroxides
This paper is all about the destruction of peroxide compounds, specifically HMTD, TATP and DADP:
http://energetics.chm.uri.edu/system/files/Peroxide%20Explos...
For solid peroxide compounds, 5 mol of either (NaBr, KMNO4, CuCl2, ZnCl2, ZnSO4, SnSO4, sulfuric acid only) were put on top of 1 mol of the peroxide
and a few drops of sulfuric acid in different concentrations (37 %, 50 %, 100 %) were added, destroying the peroxide within 14 hours. For faster
destruction, concentrated mineral acids like sulfuric acid (98%), nitric acid (70%), and hydrochloric acid (36%) can be used, but will likely cause
even small samples to detonate.
In my experience, when placing about 1 g of loose HMTD powder on a flat surface it can be lit with a torch and will just burn with a fireball and
won't detonate. There is no excuse for handling larger amounts than 1 - 1.5 grams of peroxides, so in practice, burning the unconfined compound (maybe
in smaller batches, depending on the surroundings) seems to be the best way to effectively destroy peroxides in my opinion.
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Baiuvarian
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HMTD: Synthesis, properties and my thoughts on safety
Factors like the purity and morphology of a substance can have a great influence on its properties. So when discussing the properties, these
parameters should be considered. Since it is pretty hard in a home lab to exactly characterize the material, especially impurities, I suggest at least
describing the synthesis in as much detail as possible. That way, others have the chance to reproduce it. Also, when comparing syntheses and
corresponding material properties, correlations may be found.
Synthesis
This synthesis is based on [1]. The main difference is that I use more hydrogen peroxide but I don't recall where I got that from. Finishing washing
with isopropyl alcohol is done to get rid of contaminants that are not water soluble and to help with drying.
Chemicals:
- 20 ml H2O2 30 % (stabilized, typ. with 1-2 % phosphoric acid)
- 3.5 g Hexamine (ground Esbit tablet)
- 5 g Citric acid (food grade)
- distilled water
- isopropyl alcohol
Materials:
- small beaker (I use 50 ml)
- ice bath
- magnetic stirrer
- filtration setup (I use a coffee filter)
Procedure
- Put the H2O2 in the beaker, set in the ice bath and start stirring.
- With the H2O2 below 0 °C, add the Hexamine while stirring continuously.
- When everything is dissolved as good as possible (the wax binder in the Esbit and I think even some Hexamine won't dissolve, the solution is cloudy)
add the citric acid in small batches, making sure the temperature stays below 0 °C.
- Keep stirring for about 1.5 hours while the ice bath and the solution warm up to about 10 °C.
- Set beaker in a place at room temperature for about 3 hours. Don't set the beaker on anything well insulating like a paper towel to make sure the
solution doesn't get warmer than necessary.
- Filter off the solids and wash thoroughly, first with distilled water (5 times) and then with isopropyl alcohol (3 times). Make sure to start each
individual wash from the very top of the filter. Otherwise, contaminants like acid will stay there and will get into the product later.
- Split filtrate into 2 - 3 portions and let them air dry
For this timing I got a yield of 2.4 g HMTD, with longer times (3 h stirring, 20 h at room temperature) I get 3 - 3.2 g.
Please note that anything I describe below refers to "my" HMTD created this way. Other syntheses (e.g. with different acids, ratios, washing ...) may
lead to a product with very different properties.
Physical appearance
Crystal sizes (longest dimension) vary between about 30 µm and 400 µm. There are some longer linear aggregations of connected crystals up to 1 mm
long. I was worried about those (because TATP tends to form very sensitive needles) but they are very elastic and bend and break up easily without any
reaction.
Recrystallization
Oxley [2] suggests recrystallization with a 70/30 v/v mix of ethyl acetate (EA) / acetonitrile (ACN). However, the solvent can't be fully removed even
under high vacuum. That and the availability of the solvents are the main reasons why I don't recrystallize the HMTD, especially considering I never
noticed any issues with decomposition (see below).
Sensitivity and Stability
I tested the sensitivity with about 20 mg HMTD on a milled steel block and a hammer. No amount of friction on the face, edge and corner of the hammer
could set it off, neither did light taps (light for a hammer, they would still hurt quite badly of it was your head). A slightly harder blow would set
it off. About 1 g of loose powder on a steel plate touched with a flame gives a short yellow "fireball" with a deep "oompf", the entire burn with
visible flame lasting about 0.3 seconds.
I then stored a sample of about 1 g in a flat glass dish covered with cling wrap in a dark place for two months at about 8 - 12 °C and 40 - 70 RH,
repeatedly checking on it. There was no measurable weight loss (considering the measurement uncertainties I can be sure it was less than 3 % over two
months). The appearance, sensitivity and burning characteristics did not change subjectively with the tests described above. I realize those tests are
quite rudimentary and I'm working on that (see "What I plan next").
Storage: Keeping it as a loose powder in well separated portions of 1 g max. contained
- in a way that doesn't cause mechanical stress including potential pressure build-up
- in a way that doesn't constrain it in case it burns
- far away from metals, metal compounds and acids [2]
- in a cool, dry and dark place
seems reasonably safe to me. If it were to burn it's a quick intense flame. No detonation, no shrapnel.
I would still not recommend storing it for longer periods of time since it is known to slowly decompose, depending on the conditions [3,4].
Usage: My main use for HMTD is in detonators. The the same rules as for storage apply to the detonator, except for the constraining part of course, so
appropriate precautions (PPE, shielding, ...) must be taken. Building a detonator with the HMTD contained in a plastic syringe is one simple way to
avoid metals (pressing the HMTD is not recommended). Wrapping the detonator it in something non-transparent like electrical tape blocks light. The use
of detonators containing HMTD is still limited to environments with at most moderate temperatures. All of that is not a problem in my applications.
Toxicity
Hexamine and citric acid are approved as food additives. Hydrogen peroxide will decompose into water and oxygen. The main decomposition products of
HMTD are CO2 and trimethylamine [4], both of which are not very toxic and can just be ventilated away.
Of course "the dose makes the poison". However, many other primaries and required reagents are just highly toxic. The LD50 for lead azide and silver
fulminate is about 30 mg / kg, the same as sodium cyanide [5,6]. Keep in mind that some substances (like lead) even in trace amounts will accumulate
in your body over long periods of time. Also, doses well below the LD50 can cause serious damage like cancer. With a good lab setup and meticulous
operation, contamination can be managed but for many home labs (being part of a home means long exposure to contamination), toxicity is a significant
safety concern that needs to be considered in the selection of projects.
Conclusion
The toxicological aspects of other primaries, along with the availability of reagents, are a big part of why I chose to experiment with HMTD. I chose
HMTD over TATP due to TATPs tendency form large, fragile crystals by sublimation while also being twice as sensitive to impact [7]. TATP does
decompose slower than HMTD [8] but that is in practice mostly relevant at elevated temperatures which are not a concern in my applications.
I don't want to "promote" HMTD here but I do want to share my experiences with what I think is a practical primary for some applications, that can be
handled appropriately in many home labs even on a low budget.
What I plan next
The sensitivity tests described above are quite rudimentary. I have since built a friction testing apparatus very similar to the BAM machine as well
as other testing capabilities, which I will use to further characterize HMTD and other substances.
I will try to desensitize HMTD using graphite, comparing properties quantitatively and sharing the results here.
References
[1] Tenney L. Davis: "The Chemistry of Powder and Explosives"
[2] Jimmie C. Oxley: "Destruction of Peroxide Explosives"
[3] Jimmie C. Oxley: "Synthesis and Degradation of Hexamethylene Triperoxide Diamine (HMTD)"
[4] Jimmie C. Oxley: "Decomposition of multi-peroxidic compounds Part II. Hexamethylene Triperoxide Diamine (HMTD)"
[5] https://en.wikipedia.org/wiki/Azide
[6] https://en.wikipedia.org/wiki/Silver_fulminate
[7] Rudolf Meyer: "Explosives" 6th Edition
[8] Jimmie C. Oxley: "Determining the Vapor Pressures of Diacetone Diperoxide (DADP), and Hexamethylene Triperoxide Diamine (HMTD)"
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