Sciencemadness Discussion Board

PETN synth

 Pages:  1  

VTchem - 25-4-2008 at 12:16

A lot of your posts refer to PETN. In my trolling of the web I have come across some information about it but I seem to have missed the memo on how to synthesize it.
If this belongs in another thread let me know. I searched PETN and I only found tangential references to it and no threads about making it. If there is a really simple explanation elsewhere just point me in the right direction, if not, then would some one care to post a fairly comprehensive procedure (many of you seem to be very familiar with the stuff). Anyway, thanks to all of you, I have finally found people who think like I do. I was always blowing things up (or attempting to) as a kid, and now I am embarking on a career in chemistry and am glad to find like minded people!

Pulverulescent - 25-4-2008 at 12:47

Have a look in Davis' COPAE in the site-library.
It's the best place to start.
PETN is a very powerful explosive, as you probably already know!
I'm an obsessive blower-things-upper, too!

Oh, and you're welcome aboard!

P

Pulverulescent - 25-4-2008 at 13:17

Actually, I should have described myself as someone with a strong interest in energetic materials!
'Sounds marginally better!

P

VTchem - 25-4-2008 at 13:35

Thanks, I had started reading that but had not gotten through all 490 pages yet. Is there anything that I should note in particular about this process? Has anyone done this (the procedure given by Davis) and is Pentaerythrite readily available to an individual or will I have to make it from formaldehyde and acetaldehyde?
And thanks for the welcome, can't wait to contribute.

In today's world sounding PC is sometimes more important than being PC! And yes, I too am an "unpaid energetic materials researcher" etc.

[Edited on 25-4-2008 by VTchem]

vulture - 25-4-2008 at 13:55

First of all, don't double post but use the edit function.

Secondly, we frown upon recipe exchange here. Get your own creative chemistry going, think of something new, but don't go down the beaten path with how much X with Y to get "insert explosive".

[Edited on 25-4-2008 by vulture]

VTchem - 25-4-2008 at 13:59

OK will do, thanks for being understanding.

-jeffB - 25-4-2008 at 17:14

Welcome aboard, and go Hokie, but not the way I did my freshman year:

If you're going to make flare compositions (much less primaries), don't do it in Lee Hall.

If you do, don't use chlorate and sulfur.

If you do, don't set off a little bit of it, then tuck all the rest away in the back of your dresser.

If you do, don't rearrange your room and move your dresser against the radiator.

If you do, don't expect to get off with probation as I did. Those were gentler times.

octave - 25-4-2008 at 19:22

Dang I didn't know people here lived near me! Pentaerythritol isn't readily available for purchase for any average Joe as it has no other use than for the synthesis of this explosive and for Some type of resin process if i recall correctly.

VTchem - 25-4-2008 at 20:31

Wow how much damage did that inflict JeffB? That sounds like the kind of RA nightmare passed done to scare the incoming freshmen! Thanks for the warning, however I live on upper quad and there have already been explosions here occasionally since the days of prohibition. I was planning on doing some chemical exploration when I got home and I don't think I would ever try to synthesize something so frowned upon here at school unless I had a really good reason.....but I could probably come up with one if I thought hard enough.

Anyway, the only reason I asked about a recipe is because I don't want to lose a hand or worse, you know I have a very limited supply of body parts! I will however try my own synth but just make sure I start small. If this needs to be Detritus-ed, go ahead and do that sorry for the annoying thread. I have been reading on here for sometime now but only recently decided to join the conversation, so please excuse any minor mistakes, this is the first forum that I felt was good enough to join, the rest usually degenerate into mindless banter and mudslinging and I get more that enough of that with the elections the way they are!

Sickman - 25-4-2008 at 21:10

VTchem,

Check out this link for the best step by step synthesis for PETN that I have seen for a lab scale synthesis.:D

Very good PETN synthesis courtesy of Rosco Bodine

Pulverulescent - 26-4-2008 at 03:56

PETN is fairly difficult, all things considered, VTchem!

Have you thought about cyclonite (RDX)!

Its synth is somewhat easier, more forgiving, and raw material (hexamine) easier to get.
It uses the same quality HN03 but yields are smaller (minor detail?).

It's slightly more powerful and somewhat less sensitive than PETN!

P

Pulverulescent - 26-4-2008 at 05:27

http://www.svenskakemi.nu/lagerkemikalier.html

This Swedish pyro-supplier lists pentaerythritol on its chem-page.

'Some other interesting stuff, too; all in Swedish, though!

P

-jeffB - 26-4-2008 at 06:59

Quote:
Originally posted by VTchem
Wow how much damage did that inflict JeffB? That sounds like the kind of RA nightmare passed done to scare the incoming freshmen! Thanks for the warning, however I live on upper quad and there have already been explosions here occasionally since the days of prohibition. I was planning on doing some chemical exploration when I got home and I don't think I would ever try to synthesize something so frowned upon here at school unless I had a really good reason.....but I could probably come up with one if I thought hard enough.


I don't think there's a reason good enough today. You'd make the national news, and you'd probably go away for a very long time. All I had was a fire -- in addition to respecting my body parts, I never liked loud noises -- and I was still really, really lucky not to face charges. That kind of luck is no longer available.

If I hadn't been so busy with computers -- which, unlike chemical reactions, offer "undo" commands and restoration from backups -- I would've pursued an undergrad research opportunity with someone in the chem department. I don't have any specific recommendations; this was all close to thirty years ago, and I don't know if any of the profs I talked to are still there. They actually had a fluorine lab at that time, but it looks like that's gone now. Take a look at the departmental Web site, see what research the different faculty members are doing, and pick a few areas that seem interesting. After you've gotten a year or two of classes under your belt, you should be able to get involved with a project that's doing real research; you might even be able to get a publication or two.

Quote:
Anyway, the only reason I asked about a recipe is because I don't want to lose a hand or worse, you know I have a very limited supply of body parts! I will however try my own synth but just make sure I start small. If this needs to be Detritus-ed, go ahead and do that sorry for the annoying thread. I have been reading on here for sometime now but only recently decided to join the conversation, so please excuse any minor mistakes, this is the first forum that I felt was good enough to join, the rest usually degenerate into mindless banter and mudslinging and I get more that enough of that with the elections the way they are!


The only thing I can say is, DO NOT try ANYTHING like this in a dorm, and be very, very cautious about trying it in an apartment. Others here may have different perspectives, but as far as I'm concerned, group housing is no place for even mildly hazardous materials. (And, let's be honest, are you really interested in materials that AREN'T hazardous? ;))

VTchem - 26-4-2008 at 07:58

I would never do it in the dorms, I agree that group housing + hazardous materials = very bad situation. Thanks for the synths guys, I was trying to decide what I wanted to work up and I came to PETN because so many people compare what they made to it, and it seems to be some kind of standard. RDX also had piqued my interest but I thought that seemed more exotic but if you say its not top bad I might try that too, Pulverulescent. Its only a few days now until I leave campus and all of my equipment/materials are at home so currently I am doing all the research I can into the backgrounds of all of these compounds.

What compound would you guys say is stable, safe and easy to make (yield and power are secondary for now). I need to walk before I run. I have experience with things like LN2 and HCCH + O2 stuff but this will be my first nitration. I was also thinking about peroxidation but that seems so much more dangerous from what I what have read, correct me if I am wrong but organic peroxides tend to be really rich and rather unstable.

-jeffB - 26-4-2008 at 08:17

Quote:
Originally posted by VTchem
What compound would you guys say is stable, safe and easy to make (yield and power are secondary for now). I need to walk before I run. I have experience with things like LN2 and HCCH + O2 stuff but this will be my first nitration.


This isn't my main field of interest, but I'd guess the best starting point (safe/stable/easy) would be nitrocellulose. I managed to get a runaway with even that by nitrating toilet tissue (too porous and absorbent), but the only untoward result was copious NOx and steam. I usually started with cotton cloth or cotton wads, rinsed with water and bicarbonate, and then dissolved in acetone. I never tried to get it to detonate, and doubt that it would, but my better efforts deflagrated quickly and cleanly.

Then again, I blew up my dresser, so I'm not the best source of advice. :P

Pulverulescent - 26-4-2008 at 10:12

Hexamine was the first compound I nitrated, and I did it in the kitchen-sink.
The reaction-vessel was cooled by running water (~20*C) and the acid was yellowish.

It would have been safer to decolourise the acid first, though, by blowing dry air through it.

One compound I'd be very wary of is nitro.

I made it once but never again; I don't quite trust it, anymore!

P

VTchem - 26-4-2008 at 12:51

Thanks guys, NG looked interesting at first despite its obvious hazards and a lot of people here seem to have made it or tried, but then when I read that it is even more sensitive when impure, I decided to look elsewhere...but maybe someday.

[Edited on 26-4-2008 by VTchem]

chemoleo - 26-4-2008 at 19:17

Back on TOPIC please guys.


Quicksilver has made PETN with HNO3 less than 100%, I think he posted it in the trinitrotoluene thread:
Quote:

***********
for PETN synth
***********
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
------------------------

or
34,0 ml of 65% HNO3 (66% excess)
24,8 ml of 96% H2SO4
10,0 g of Pentaerythrite
------------------------

or
34,8 ml of 58% HNO3 (48% excess)
36,3 ml of 96% H2SO4
10,0 g of Pentaerythrite

Let me say this; it does need to be monitored to a get degree. Temp must not exceed 15-20C or else it may run and spew NOx.



There's some question about whether these are full tetranitrates or mixtures, but crystallisation appears to occur well, suggesting the purity of the final product is high.

Microtek - 26-4-2008 at 23:28

I downloaded an excel sheet from roguesci which contained an adaptation of the triangular nitration graphs in Urbanski. You could enter amounts and purity of acids and then it would calculate the change in concentration as the nitration ran. The results was then displayed as an overlay on the triangular graph. This allowed you to see if the process stayed within the PETN production zone or if it strayed into domains where the lower nitrates were produced.

Playing with this tool lets you determine an optimum acid composition depending on your individual supply situation.
I also found that with well purified and highly concentrated nitric (99%) you should get almost quantitative yield with only 2.5 ml acid per gram of PE. I tested it with nitric acid that titrated as 99.5 % concentration and got a 97% yield (assuming only the tetranitrate was produced).

I don't have the document anymore, but I think it was called petn2.xls

Pulverulescent - 27-4-2008 at 05:19

Quote:
Originally posted by Microtek
I tested it with nitric acid that titrated as 99.5 % concentration and got a 97% yield (assuming only the tetranitrate was produced).


I have no experience of PETN yet, but I just assumed lower nitrates would be removed by repeated washings.

And 99.5% HN03 Microtek, that's practically anhydrous---how did you get that high a concentration?

P

hokk - 27-4-2008 at 06:50

Quote:
Originally posted by Pulverulescent
http://www.svenskakemi.nu/lagerkemikalier.html

This Swedish pyro-supplier lists pentaerythritol on its chem-page.

'Some other interesting stuff, too; all in Swedish, though!

P
The downside with that shop is that you have to make a minimum order of 1500SEK (161 Euro, 255$ excluding VAT).
This polish guy also has it tough (among other things), http://www.keten.org.pl/odczynniki.html

Quote:
Originally posted by chemoleo
Quicksilver has made PETN with HNO3 less than 100%, I think he posted it in the trinitrotoluene thread:
....
There's some question about whether these are full tetranitrates or mixtures, but crystallisation appears to occur well, suggesting the purity of the final product is high.
Don't know how pure it is (any tips for testing this?), but the synth in the middle gives a one hell of a energetic compound.

[Edited on 27-4-2008 by hokk]

[Edited on 27-4-2008 by hokk]

Microtek - 27-4-2008 at 09:45

Quote:

And 99.5% HN03 Microtek, that's practically anhydrous---how did you get that high a concentration?


Note that I only said that it titrated as 99.5%....
Anyway I made it as follows:
50 ml HNO3, 62% conc. was added to 50 ml H2SO4, 96% in a distillation setup. The mix was distilled at atmospheric pressure without boiling to reduce decomposition.
The first 30 ml was collected and the remaining acids were heated to 200 C to reconcentrate the sulfuric acid.
Then, after cooling down, the 30 ml distilled nitric (which had been determined to be about 85% conc by gravimetric measurement - this was an estimate since there was some dissolved NOx ) was added.
The mix was distilled as before, but even slower. I collected about 20 ml of very pale yellow acid. This acid was then heated to 50 C and dried air was bubbled through until it was completely colourless. It was stoppered up and cooled to 20 C, at which point a sample was removed for titration.

Pulverulescent - 27-4-2008 at 10:59

Thanks for that, Microtek.
So slow below-boiling distillation does work.
I imagine it's very slow, but if the temp was constant (~90*C?) it could presumably run for many hours unattended, giving higher than usual concentration of acid.
It's quite interesting!

P

Microtek - 27-4-2008 at 13:07

Yes, I let it run in my shed unattended, I just check on it now and again. I think that a batch like that takes maybe three hours. I use a glass kettle placed on a portable electric stove and a water cooled condensor (cooling water recirculated by a small bilge pump). The temperature fluctuates between maybe 90 and 110 C since the thermostat is not so accurate. I wrap the top of the kettle in Al foil to provide a little insulation, so the temp of the acids doesn't have to be higher to compensate for heat loss before the vapour gets to the condensor.

DJF90 - 27-4-2008 at 13:48

3 hours for 20ml of acid :o thats long... its a good job it can be left unattended... but at the end of the day the collected acid is surely worth it. I assume that using a larger RB flask than necessary would aid in the distillation as it would provide the acid with more surface area and hence can evaporate/vaporise more readily? Can I ask what you titrated the acid with? NaOH solution would seem reasonable, but at what concentration? And how large was the sample of acid to be titrated? Your results are truely outstanding though microtek :P

[Edited on 27-4-2008 by DJF90]

Microtek - 27-4-2008 at 23:44

OK, this is the last OT post from me then: I titrated with NaOH soln at about 1 M IIRC. The NaOH concentration had been established precisely by titration against high purity benzoic acid. I calculated the accumulated error based on estimates of the individual errors and got a concentration of 99.5 +- 0.1% IIRC.
I have an old Mettler-Toledo mechanical balance which is very accurate. It measures down to 0.0001 g with excellent repeatability and was mine for the taking, simply because the lab upgraded to digital versions. It enables me to do fairly accurate work at the small scale, where I prefer to be.

Anyway, the product of the PETN synthesis using only 2.5 ml HNO3 for 1 g PE produced 2.250 g product after thorough neutralisation (in solution) and washing.

Boomer - 28-4-2008 at 09:40

Did you get a melting point? This would give pointers to whether it contained lower nitrates. On the other hand, if it contained much trinitrate of lower molecular weight the yield would be over 100%....

97% seems high anyway, I don't have numbers for PETN here, but I remember for NG even industrial 1000kg batches using 99% nitric with oleum get below 97% for NG. IIRC mostly because the spent acid dissolves 3%, though 2/3 of that *could* be recovered by solvent extraction, which is *not* done in normal practice. They want to get rid of the shit ASAP.

You sure the solvent from neutralization was completely gone (i.e. vacuum desiccator)? I remember a batch of MHN containing considerable solvent even though it looked and felt dry. The much lower mp showed it.

Not that I don't want you to hold that yield record - I am content to have beaten you with the RDX yield (additive threat). ;)

[Edited on by Boomer]

Microtek - 29-4-2008 at 00:14

I didn't measure the melting point of the product as I don't have an actual melting point apparatus. So every time I need to do a measurement I have to come up with some improvised contraption. That said, I did place samples of different PETN batches on a thin glass plate which was then placed on a hotplate. The samples all melted practically simultaneously and very sharply. They also crystallized in a manner which suggested a high-purity sample.

Regarding the RDX, my best yield was 74% of theory based on hexamine, but more impotantly (in my opinion) 0.31 g RDX per ml of HNO3. I don't quite recall what your numbers were....

-=HeX=- - 8-5-2008 at 07:51

Back on topic: this friday I will post a synth that I have used for PETN. I got it in a torrent and it is very good and contains good data on PETN. I got my pentaerythritol through good social engineering but the supplier no longer carries it.

PETN Is a very safe and good explosive in my opinion but I prefer ETN for the simplicity of obtaining the precursors and synthesising it in uncontrolled conditions. I hate said a lot on ETN on roguesci but it is down.

Engager - 15-12-2008 at 11:09

Quote:
Originally posted by Microtek
OK, this is the last OT post from me then: I titrated with NaOH soln at about 1 M IIRC. The NaOH concentration had been established precisely by titration against high purity benzoic acid. I calculated the accumulated error based on estimates of the individual errors and got a concentration of 99.5 +- 0.1% IIRC.
I have an old Mettler-Toledo mechanical balance which is very accurate. It measures down to 0.0001 g with excellent repeatability and was mine for the taking, simply because the lab upgraded to digital versions. It enables me to do fairly accurate work at the small scale, where I prefer to be.

Anyway, the product of the PETN synthesis using only 2.5 ml HNO3 for 1 g PE produced 2.250 g product after thorough neutralisation (in solution) and washing.


I've also tried nitration using 99.7% HNO3 (yellowish - some NOx exist), to get rid of nitrogen oxides i've added some small ammount of urea until acid is completely colorless. Temperature was carefully controlled to be below 15C, but at some moment (then about half of penthaerythrytol was added to acid) violent oxidation started and mixture was emidately poured into large ammount of ice cold water - no precipitate was obtained. Next attemt i've made was dilute (70%) nitric acid + conc. H2SO4 using proportions mentioned in this tread somethere above, temperature was controled by stream of cold water, all was fine until moment close to the end of penthaerythrytol addition, a was away for 15 sec to turn off lights in my bedroom (flask was sitting in cooling bath), again violent oxidation took place, many NOx evolved, temperature rised from ~12C then i was away, to 56C+ then i came back after ~15 seconds, reaction mixture turned into black oily liquid, with was emidately poured into ice water and discarded (nitric acid used was just 99.5% HNO3 diluted by water to 70%). Third attempt was made using same method as in second, but temperature control was to below ~10C and virgous stirring without stops, after all penthaerythrytol was added, and mixture is allowed to slowly heat to room temperature at ~20C violent oxidation was started, and mixture is also poured into large ammount of cold water, some NOx evolved and precipitate of PETN is obtained with ~30% yield. I have no idea how you mean to stop this violent oxidation reactions, and how you never encountered them. Somebody have any idea what is the problem here?

Rosco Bodine - 15-12-2008 at 18:18

Yeah I have studied this nitration a bit and worked out
a pretty optimal synthesis which is basically identical to a patented method. I am sure I posted about it, maybe it was on another forum, the E&W forum. I'll have to go back and check this to get the specifics. But as I recall
the nitration is a very high yield reaction with high acid utilization efficiency using ~97% HNO3 alone, but it is also a very very exothermic nitration where excellent cooling and very slow addition of the pentaerythritol is required
while good stirring and a narrow nitration temperature range is closely controlled by rate of addition. It can be nailed and reproduced because I have done it more than once with identical results and no complications. But it does require careful work. It was based on one of the
old patent Nobel or DuPont processes I think. I do remember the nitration proceeds at a mild cool temperature absent any of the warming described with some other methods...which is a really bad idea IMO .

Okay I found it, what you are looking for of course is
Rosco's good old country recipe for PETN :D

http://www.sciencemadness.org/talk/viewthread.php?goto=lastp...

Hmmm I just went back and saw that Sickman posted this same link about eight months ago, so this puzzles me what could be the problem unless there is some variable which was not observed, and this accounts for the problem.
Anyway it worked for me very well as described.

[Edited on 15-12-2008 by Rosco Bodine]

Engager - 16-12-2008 at 12:21

Process with 70%HNO3 + conc. H2SO4 was repeated by another russian chemist using conc. HNO3 diluted to 70%. Same problems vere encountered, it was very surprising, because, man i'm talking about reported several completely successfull runs using this method, he also mentioned that he has no idea about what is the reason of problem. There is something terribly strange here, only difference from my case with ~15 sec away time, he was away for about 40 seconds.

[Edited on 16-12-2008 by Engager]

Rosco Bodine - 17-12-2008 at 02:14

An educated guess is that your problem is related to two factors...reaction temperature too low and addition not gradual enough to be in sync with the reaction rate, causing surging. You need a sufficient reaction temperature and good stirring so that there is a smooth reaction of added material without any delay or induction period, because the reaction is thermally driven but is also extremely exothermic, so a runaway is lurking there for any unreacted material, proceeding to react and cascading past the decomposition temperature. This is classic organic nitration stuff. The first thought is there is insufficient cooling so the reaction temperature is lowered which then makes the reaction sluggish for added material and aggravates the inclination for induction delay followed by runaway. So it may seem conterintuitive, but your baseline nitration temperature needs to be raised a little so that added precursor nitrates smoothly on addition as soon as it is introduced, without any delay which allows unreacting material to accumulate, and to then react in a self-accellerating fashion.

And yeah the problem is aggravated with a more oxidizing nitration mixture using mixed acids. The straight nitric acid
nitration method is really the best method for PETN.

Try that five degree window temperature range I described
for 18-23C using the 97% HNO3. The idea there is to sprinkle
in the PE very slowly at 18C and at a rate to keep the reaction temperature in that range, allowing for a rise to 23C
from the exotherm of each addition, allowing the exotherm to subside and making the next addition at the fall again to18C. If you have a screw feed addition funnel for solids, you can probably fine tune the rate of addition to flatten the oscillation of temperature a bit better than that 5 degrees.

The exact optimum temperature is somewhere in that range,
perhaps 20-22C, I am not certain. But the warmer you run
it , while it goes faster, it is closer to the limit and has less
headroom range for tolerating any surges in temperature.

It has been a few years since I did this nitration, but I tend to make accurate notes, so those numbers are probably correct.


[Edited on 17-12-2008 by Rosco Bodine]

zajcek01 - 17-12-2008 at 08:00

Here is the document Microtek vas talking about :

http://www.2shared.com/file/4476387/87867b1c/petn2.html

Page contains some ads and popups.... just ignore them and click:
"Save file to your PC: click here" on the right bottom corner of the page.

You have to enable macros in M$ Excel in order for this document to work.


how to read results:

Area I - Formation of PETN with yield of 94-98% without formation of sulfoesters.
Area II - Formation of PETN via sulfoesters.
Area III - Area of low yields (10-50%) due to the high NOx
production and oxidation processes
Area IV - PETN not forming"


The only problem with nitration of PE with mixed acid I had, was localized overheating and oxidation because concentration of water rose to 30% at that spots. Nitric acid that contains more than 30% of water is a powerful oxidizer.
The solution of this problem was overcome with finely powdered and dried PE and mixing thoroughly during the process of nitration.

[Edited on 17-12-2008 by zajcek01]

Kontaktverfahren - 31-12-2008 at 17:24

Mhh this does not work for me, no yield is shown, the diagramm does not change whatever I type and the buttons have no use.
(Maybe its because I use Open Office)

PS: Yes I have enabled macro-use

zajcek01 - 1-1-2009 at 15:59

It does not work on OpenOffice.org :(

It only works on Micro$oft office

erik89 - 10-1-2009 at 10:35

Hi!
I´ve had some problems with my PE.
This is what happend:

First, I meassured up X mL of H2SO4 and Y mL of HNO3.
These were pre-chilled and later mixed, and once again chilled to a temperature about -10 C.

Then, I meassured up Z grams of Pentaerythritol.
I started the addition of PE to the nitrating-mix.

I added one gram at a time.
The PE just simply DISSOLVED in the nitrating-mix.
I added another gram. I still just dissolved.

After a while, all of the pentaerythritol were in the mix and "dissolved"
The mixture whas 100% CLEAR, which is shouldn´t bee.
There should have been a white slurry, with some crystalls in it.

The "liquid" was added to water, to precipitate the "PETN".
Nothing precipitated.

There is nothing wrong with the acids.
(96% H2SO4 and 65% HNO3, and they´ve worked just fine with other synthesis)
So, I think there is something wrong with my pentaerythritol.

Is there anyway to test it´s purity?

Have anyone of you guys had a similar problem?
If so, how did you solve it?

Could it have been any water in the PE, since it is hygroscopic?

Thanks in advance!

hissingnoise - 10-1-2009 at 15:00

Dilute HNO3, IMO, is the real problem here.
The amount of water absorbed by pentaerythritol is insignificant, considering your HNO3 contains 35%.
Distill it carefully from twice its volume of H2SO4, reconcentrate the latter to ~98% and try again.
Or better, add predried pentaerythritol to HNO3 of the highest density.
If the substrate *is* pentaerythritol, the tetranitrate will form and will precipitate on drowning.

The HNO3 should have no dissolved NO2.
If it can't be removed by blowing dry air through, treat it with a gram of urea.

[Edited on 10-1-2009 by hissingnoise]

erik89 - 10-1-2009 at 15:16

Quote:
Ursprugligen inlagt av hissingnoise
Dilute HNO3, IMO, is the real problem here.
The amount of water absorbed by pentaerythritol is insignificant, considering your HNO3 contains 35%.
Distill it carefully from twice its volume of H2SO4, reconcentrate the latter to ~98% and try again.
Or better, add predried pentaerythritol to HNO3 of the highest density.
If the substrate *is* pentaerythritol, the tetranitrate will form and will precipitate on drowning.


Hi!
Yes, I am aware of the fact that higher conc. the HNO3 has, the better the yield will be.
But, here´s the prob.
I have two different pentaerythritols, from two different suppliers. One of them, worked just fine, and I got an exellent yield from it. Unfortunatley, I´ve ran out from that one, and I have to use the PE from the other supplier, and his doesn´t work.
My primary question is that if there is anyway to test the PE´s purity?

Thanks for replying!

hissingnoise - 10-1-2009 at 15:27

Near anhydrous nitration is the best test I can think of, right now.
Failure under those conditions will seriously call your pentaerythritol into question.

Microtek - 11-1-2009 at 08:00

Maybe you could do some sort of elemental analysis by quantitatively analysing the products of the complete combustion. So, make an apparatus similar to a nitrometer, make a mix of your mystery PE and excess CuO and put it in there. Heat rapidly to ignition with some non-contaminating heat source in a stream of suitable gas (eg. nitrogen). You could pass the gas stream over an exactly known amount of a suitable dessicant to capture the water and in that way determine the amount of hydrogen in the sample.
You could then bubble the gas stream through a Ca(OH)2 slurry (with an exactly known amount of hydroxide) to absorb CO2. Then weigh the mix of CaCO3 and Ca(OH)2 to establish how much carbon was in the sample.
Using the assumption that your sample contains only carbon, hydrogen and oxygen, you then have the amount of oxygen too.

A bit labor intensive, but if you don't have access to more sophisticated equipment.....

Engager - 1-7-2009 at 10:50

Quote: Originally posted by Engager  
Process with 70%HNO3 + conc. H2SO4 was repeated by another russian chemist using conc. HNO3 diluted to 70%. Same problems vere encountered, it was very surprising, because, man i'm talking about reported several completely successfull runs using this method, he also mentioned that he has no idea about what is the reason of problem. There is something terribly strange here, only difference from my case with ~15 sec away time, he was away for about 40 seconds.

[Edited on 16-12-2008 by Engager]


I'm finaly realized source of my problems with nitration of PE - it is purity of source pentaerythritol. Melting point of PE i was using in all failed nitration experiments is ~220C - that is much too low, indicating a lot of impurities are present. Oxidation problems completely disappeared then i was using pure PE from another chemical supplier. So if someone encounter severe oxidation problems, check out your pentaerythritol!

[Edited on 1-7-2009 by Engager]

User - 2-7-2009 at 04:04

Would it not be quite easy to purify the PE from a solvent?

Btw the best yield i ever had was 89.52% of theoretical.

This was done by using 65% nitric acid.
34.0ml 65% HNO3 (analytical grade)
24.8ml 98% H2SO4 (boiled down battery acid)
10 gr PE (unknown grade)

The acids were mixed and cooled to -5 degrees.
The PE was added in three portion while keeping temp under 0.
The vessel was taken out of the ice and slowly gained temp by the exothermic reaction.
Very careful and slowly the temp was brought up to 30 degrees and maintained for 2 hours.

Then the mixture was crashed into 500ml of almost freezing water.
The next wash consisted out of 200ml 5% bicarbonate, letting it sit for a while.
The PETN was then dried on a radiator on low heat.

When almost dry, the PETN was added to 200ml of hot acetone and 1 gram of bicarbonate was added.
The mixture was then crashed on 500ml of water with chunks of ice.
And sat for a night in the freezer. (before i didn't do this and i noticed that my yield suffered, urbanski has a nice table on acetone/water/petn at different temps)

Filtered and dried in an exicator.
Yield: 89.52 %
Thats as almost 21 grams

Could be better though.



[Edited on 2-7-2009 by User]

edmo - 10-8-2009 at 02:37

of course C4 via hexamine is easy.

PETN is relevant because it's a LOT easier to initiate. So the original posters questions about PE synthesis are totally relevant.

Rich_Insane - 10-8-2009 at 09:11

Wow you guys can get FNA? Very difficult to come buy without vac dist.

Pentaerythritol has nothing to do with erythritol btw. Pentaerythritol can actually be produced by fomraldehyde and acetalhyde if I am correct. I saw it for sale from Sigma for ~$30 a kilogram. You could buy it from a middleman.


hissingnoise - 10-8-2009 at 11:59

If your KNO3 is dry and H2SO4 is ~98%, strong, fuming HNO3 will distill from it without using vacuum. . .
If you're nitrating pentaerythritol the HNO3 should be decolourised first!
Blowing dry air through it usually works; if it doesn't, just add a little urea. . .
Some things need repeating!

[Edited on 10-8-2009 by hissingnoise]

phantasy - 15-10-2009 at 16:00

Quote: Originally posted by User  

Very careful and slowly the temp was brought up to 30 degrees and maintained for 2 hours.
[Edited on 2-7-2009 by User]

peretherification of pentaerytrytol sulphate begin at 40 deg
use 45c and 15-20 minutes to 93-96% yeild

[Edited on 16-10-2009 by phantasy]

chemoleo - 8-1-2010 at 18:23

The derailment of this thread on the matter of PETN that made it into the news can now be found in Whimsy, please continue there (while refraining from turning this into a political discussion).

http://www.sciencemadness.org/talk/viewthread.php?tid=13235

[Edited on 9-1-2010 by chemoleo]

PETN synthesis

NUKE - 30-4-2010 at 01:40

I have employed this procedure with various 50-200g PE batches and I have never had a runaway or any problems with the product.

I'll give example for nitration of 100g PE.

255mL of 96% H2SO4 is measured into a reaction vessel (I have figured out 1L flat bottomed florence flask is optimal for that purpouse since much less NOx is evolved during nitration due to small surface area and shape of flask itself). H2SO4 is equipped with thermomether (-30 to 150°C), covered with thin plastic foil and moved into a salt/ice bath until the temperature of it reaches approximately -10°C. In the mean time 390mL of 65% HNO3 are measured and moved onto a 600mL beaker which is covered with plastic foil afterwards and put into the cold water bath (~10°C). When appropriate temperature of H2SO4 is reached HNO3 is added, thermomether is fixed with the hand to the bottom and swirling is employed so the temperature of acid mixture doesn't exceed 35°C. When all the HNO3 is added mixture is moved into a ice bath and temperature is allowed to drop to 5°C. PE is then added in few 10g portions and violent swirling is used to homogenise the mixture. (I have figured out it doesn't really matter how fast you add PE, the mixture just has to be continuously stirred/swirled so no hot spots form) For instance during 200g PE nitration starting temperature of acids was 10°C and I have added all 200g of PE in mere 10 minutes, no NO2 evolved only the temperature rose to around 35°C. After all the PE has been added mixture is heated up by momentarily immersing florence flask in hot water (70-90°C), moving flask out of the water and violently swirling the mixture for some time until temperature became stable. Process was repeated for as long as the temperature of mixture was lower than 45°C. Mixture was kept at the temperature for around 30 minutes. Heating was stopped after that time and mixture was left to stand until total of 1h after beginning of addition had passed. Mixture was dumped into 5L of cold tap water and whole mixture was stirred a bit.

Crude PETN was filtered using vacuum filtration apparatus and washed few times with distilled water. As much filtrate as possible was sucked out of the crude PETN. Crude PETN was then moved in a vessel and split in half. First half was moved into a clean 1L florence flat bottomed flask and 500mL of acetone was added. Around 20g of NaHCO3 was then added onto the same flask and half of the crude PETN. In the mean time 5L of cold distilled water with small ammount of NaHCO3 dissolved was prepared and kept close. Florence flask with acetone, crude PETN and NaHCO3 was put into the water bath on electrical heater and mixture was stirred until temperature of above 60°C was reached. Majority of PETN dissolves at that temperature only NaHCO3 and salts from neutralisation are left on the bottom. Clear layer is decanted into the NaHCO3 solution which is vigorously stirred during the decantation. Process is repeated with another half of crude PETN.

My most recent attempts yielded 210g of recrystalized dry PETN.

-=HeX=- - 30-4-2010 at 14:09

Nuke has a lot of experience with PETN... I recall seeing (via webcam) a kilo or two of the wonderful stuff in an ice cream tub!

Actually, Nuke, you should post the pics of the funky NG here...

Anyways... I have noted that PETN is rather sensitive to initiation by certain primaries moreso than others. For example, 50mg Pure Lead Azide was the least I could use to get reliable dets from well pressed PETN, wheras a mere 3mg or less of DPNA could be used with excellent results.

However, seeing as they are old tests, I cannot be sure of 'how' well pressed them stuff was...

VladimirLem - 30-5-2010 at 09:57

Is the product really the TETRA-Nitrate ?

I think, that i read in some online book, ist is a TRI-Nitrate when using diluted HNO3



hissingnoise - 30-5-2010 at 10:48

There is no product when dilute HNO3 (<90%) is used with pentaerythritol.
The trinitrate, along with the lesser nitrates containing (OH) is water-soluble and doesn't normally precipitate on drowning. . .




VladimirLem - 30-5-2010 at 11:34

Quote: Originally posted by hissingnoise  
There is no product when dilute HNO3 (<90%) is used with pentaerythritol.



***********
for PETN synth
***********
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
------------------------

or
34,0 ml of 65% HNO3 (66% excess)
24,8 ml of 96% H2SO4
10,0 g of Pentaerythrite
------------------------

or
34,8 ml of 58% HNO3 (48% excess)
36,3 ml of 96% H2SO4
10,0 g of Pentaerythrite

Let me say this; it does need to be monitored to a get degree. Temp must not exceed 15-20C or else it may run and spew NOx.


are you sure ?

Quote: Originally posted by hissingnoise  
The trinitrate, along with the lesser nitrates containing (OH) is water-soluble and doesn't normally precipitate on drowning. . .


that i've got wasen't water-soluble ;)

franklyn - 31-5-2010 at 19:40



Attachment: PETN Synthesis of .rtf (12kB)
This file has been downloaded 1403 times

Microtek - 1-6-2010 at 00:45

@Vlad:
When you use dilute nitric along with concentrated sulfuric you are generating concentrated nitric in situ. So that doesn't really qualify as using dilute nitric acid.

quicksilver - 1-6-2010 at 08:47

Microscopic examination if crystalline structure will reveal quite a bit. Needles form at the level of PETN while lesser nitrated materials will form other shapes. The shearing/shaving of the material will still reveal needle structure at 100x. Tri-nitrated material will often still be energetic. Whether it will wash out or go into solution is dependent upon temp & method of nitration.

Edit:

This is also true of MHN. At the level of true MHN you'll see needles; if it doesn't make it that far, you won't. ETN forms platelets, however (it's only my opinion) that other shapes reveal higher levels of nitration, especially if 1.51 HNO3 is used for initial nitration & H2SO4 is used to precipitate the nitrated product out. Under magnification, platelets are seen along side hexagonal granular shapes - using that form of nitration.

[Edited on 1-6-2010 by quicksilver]

gnitseretni - 3-6-2010 at 12:47

Made some PETN.

12g PE
60g KNO3
150ml H2SO4

I again used a large excess of H2SO4 just like with the ETN synth a few days ago.

I added the PE pretty fast. After the last addition I stirred for 10 minutes in the ice bath, then I took it out and placed it in 45C water and stirred for another 15 minutes and then, after taking a picture of the thick mixture, drowned it in cold water. After washing, neutralizing, recrystallizing, drying.. result is 21g PETN. Not too bad :)

Some pics..






Rain - 3-6-2010 at 13:09

If I may ask...What was the temperature of your ice bath, and what was the concentration of your sulfuric acid?Was it drain cleaner or lab grade?Im so gonna make me some pbx as soon as I get a chance.Jealousy is a great motivator.

[Edited on 3-6-2010 by Rain]

gnitseretni - 3-6-2010 at 13:24

Didn't check the temp on the ice bath, but I started PE addition when the temp of the mix was 5C. The H2SO4 was drain cleaner(Liquid Fire).

VladimirLem - 6-6-2010 at 05:21

Quote: Originally posted by gnitseretni  
Made some PETN.

12g PE
60g KNO3
150ml H2SO4



Wouldn't it be better to take ammoniumnitrate to get a stronger HNO3 ?

quicksilver - 6-6-2010 at 11:39

Doesn't work that way. Solid alkali nitrates have different rates of efficiency but the results are generally similar.

Sephi - 1-9-2010 at 00:12

Hi
I'm new on this forum, I think this is the best place to expose my doubts

This summer I've done about 20g of PETN (I used the synthesis of powerlabs) and I've took some pics of the dry crystals.

60X
150X
150X
600X

anyone have other pics to compare?

There is a system to distinguish PETN from other esters?

Thanks and sorry for my bad english



pdb - 1-9-2010 at 07:45

For those worried about the effectiveness of PETN synthetized from mixed acids, here is a test of a 2.9gr pill on a 5mm thick steel plate :


Pan3.jpg - 118kB

The side in contact with PETN exhibits typical detonation wavelets, when on the other side, the creeks reveal the lamination direction.

[Edited on 1-9-10 by pdb]

VladimirLem - 5-12-2010 at 06:32

Hi


"pdb" is right, it IS a strong explosive. I tested it as a little shaped charge (3cm Copperpipe, tulp-glasliner, 3cm Standoffs at a 5cm thick steelplate. Around 20g of that kind of "PETN" where used and penetrated around 2cm...
:)


------------------------------------------------


Back to Topic ("real" PETN)

In this Thread is a Synth of (real) PETN with high conc. HNO3 (look at the Link)

http://www.sciencemadness.org/talk/viewthread.php?tid=6151&a...

...do i have this right, that only 100ml HNO3 Acid are used at 33g PE, because the themerature of the mixture is such high (18-23C) so that the Acid can better work - (but everything else is like a "normal" PETN synth where only high conc. acid is used)...right?
I ask this, because the most synth of PETN which are on the internet use only 25g PE on 100ml...(1:4 ratio)





quicksilver - 5-12-2010 at 06:53

I know I have mentioned this before but for those who have not read back some time, etc there is the reagent grade (or mil-spec) grade pentaerythritol. that is used in making energetics (in Europe it's often know as pentaerythritol.-M, Penta-M, etc) & there is the material in the 30gal tins used in the vinyl and paint industries that is below common technical grade material (93% +). The "big tin-cans" of pentaerythritol. used to be available frequently and sold off at the pound level. The best you could hope for was getting a very poor yield of PEN for this. In general; it was garbage for making PETN. Reagent pentaerythritol is often note to be extremely light yellow-white; the paint-grade is identified by a beige coloration (very light beige and also "fluffy" not granular). Reagent level pentaerythritol would never be cheap. It's cost would not be low. Paint-grade pentaerythritol is (IMO) a waste of acid.

Since the abuses of energetics the paint-grade material is much more difficult to obtain than it once was. However there may still be some cans of that crap floating around. Don't waste your money as you could make pentaerythritol that would have a higher purity level & would not be adulterated with a fairly large percentile of paint-oriented items.



[Edited on 5-12-2010 by quicksilver]

Rosco Bodine - 5-12-2010 at 07:13

The procedure was accurately described. However you must note the stirring difficulty due to the proportions which involve a high solids content. Excellent stirring is required to achieve that efficiency. If you don't have excellent stirring
then you should adjust your proportions for a thinner mixture.

Reagent grade pentaerythritol was used for the experiment. It is a snow white material and so is the recrystallized nitrated form, which looks and glitters exactly like table sugar.

[Edited on 5-12-2010 by Rosco Bodine]

nitro-genes - 6-12-2010 at 00:57

What is the purity of this reagent grade? My PE is 98% purity, although it has a slight acetic acid/acetaldehyde smell to it. With efficient stirring and cooling I usually got something like 22 grams of PETN from from 10 grams of PE and 30 ml of 97% WFNA. Strange thing is though that the PETN goes from snow-white to a very slightly shade of yellow upon neutralization of the water-washed PETN with a few ml's of 10% ammonia. Never had any runwaways though...

Rosco Bodine - 6-12-2010 at 01:51

It was 98% or better, that has been some years ago and I'm not certain. The yellowing you got may be from overneutralizing.

nitro-genes - 6-12-2010 at 04:45

Not sure about the over neutralizing, the yellow colour became visible with the first addition of ammonia. PETN crystalizes as very pure PETN though, forming 1-2 cm long needles from a slowly cooled 40% PETN/acetone solution. Couldn't find the pictures from these anymore, though here is one after blending with water for a couple of minutes. Estimated size is 20-50 micron. (40 times enlarged) :) Crystals show lots of surface damage as they are not translucent, also experimented with water/solvent treatment afterwards to improve surface imperfections, though it is quit tedious work to do so...


PETN.jpg - 84kB

[Edited on 6-12-2010 by nitro-genes]

quicksilver - 6-12-2010 at 06:54

It sounds appropriate to me. As long as you're getting tiny needles in the end result instead of a poor-yield granular mass; the pentaerythritol is clean enough. An extremely buff white yellow can also be an age issue: however I'm talking about JUST off white; any real yellowing may be also be UV exposure. You really don't what beige or a light brown! As I remember 98% would be acceptable. The commercial vinyl product is really low (such as 89-91%).

iHME - 6-12-2010 at 13:34

My PE appears to be the paint-grade type.
It was reasonably cheap.
It's not granular but instead a freeflowing white powder that feels light.

What kind of yields can be expected from this starting material?
What are the common impurities in the paint-grade stuff?
And are those easy to get rid off? As in a simple recrystallisation or solvent wash?
All in all, what can be done to attempt improving yields from this starting material?

Sorry for multiple questions, but they should be in theme with the topic.

mabuse_ - 6-12-2010 at 14:22


Quote:

a freeflowing white powder that feels light.


Just like mine. The Vendor made no statement about purity.

I got exactly 20g of flawless locking white matter from 10g using 65% HNO3 with H2SO4.
Seems to work fine.

nitro-genes - 6-12-2010 at 15:13

Recrystallization should remove some impurities, which are definitely there when using mixed acids instead of 90+% HNO3 alone to produce PETN. After watering down the mixed acids + PETN I then filter, thoroughly wash, neutralize, and finally a second wash and drying. However, there is always some left over PE or lower nitrate portion that doesn't dissolve when it is subsequently recrystallized from acetone. It stays on the bottom as a flocculent mass which represents about 1-2% of the total amount of PETN added to the acetone. Then I also noticed that upon the addition of water to precipitate the last amount of PETN from the acetone, the filtrate is slightly milky. This impurity won't collect at the bottom, possible also lower nitrates that are still soluble in the acetone/water mix. It appeared to me that these impurities are reduced when longer nitration times/better stirring/final 40 deg. step are used, and are nearly absent when conc. HNO3 is used alone...

Then again... I stored a small amount of PETN/Pib plastique made with mixed acid PETN for over 2 years, still detonated fine.

[Edited on 6-12-2010 by nitro-genes]

hissingnoise - 7-12-2010 at 04:48

Quote: Originally posted by iHME  

What are the common impurities in the paint-grade stuff?

Technical grade PE contains a few per cent of di- and tri-pentaerythritol.
Their presence reduces PETN's stabily and explosive strength!
They could be removed by careful fractional crystallisation, I expect . . .


quicksilver - 7-12-2010 at 06:56

There is a rare book entitled The Pentaerythritols by Berlow, Barth, & Snow that is generally the bible of the industry and of all the idiosyncrasies surrounding it. I read that thing from cover to cover many times as I have made a lab of pentaerythritol itself in an attempt to get the finest product. It's actually not that hard.
So I'm with nitro-genes on this; I think a re-crystallization should be fine if you have any doubt. HOWEVER - if you DO have some doubts don't neglect that step as you'll really only get a 40-60% yield of PEN if you don't.

The paint grade stuff can also have real extraneous garbage in it. This almost sounds ridiculous but it can actually have everything from clear and white enamel. crushed vinyl siding, and white powder-coating all used as both adulterants / recycling, & means to stop it's use as an explosive. Remember this stuff was sold in what looked like a huge coffee can of 30 gal volume for about 60-70 USD. Large scale attention was paid to it starting back in the 1980's but only as a method to recycle. Today.....I'm fairly sure they do not use anything but a lightly adulterated product. The main difference between manufacturing RDX and PETN was always the cost of the precursor in PETN that was responsible for the cost difference.


edit:
If you compare the major precursor of PETN and RDX you'll clearly see that RDX is a cheaply manufactured material. The acid being the real expense; the hexamine being only formaldehyde and ammonia while quality Pentaerythritol has always been fairly expensive - even on a plant level. It's often quoted that the shelf life for both being at the 20yr mark. (Federoff, Urbanski, etc)


[Edited on 7-12-2010 by quicksilver]

Bert - 30-12-2010 at 13:42

119 ml of 40' Baume nitric acid and 105 ml of 1.8 g/ml sulfuric acid were chilled to freezer temperatures, then mixed and chilled to below 10' C. in an ice water bath on a stirring hot plate.

30 g of pentaerythritol was added in small scoops, allowing each addition to dissolve and temperature to fall back down to 5' C. before next addition. Temperature ranged from 5 to 8' C. and total time was 30 minutes.

The mix stirred another 10 minutes while a warm water bath was prepared, then temp was raised to 50' C. over another 10 minutes. Mix held at 50' for 20 minutes and drowned in 1 l of ice water. Total time from start to drowning 65 minutes.

Product filtered, washed with distilled water, bicarbonate solution and then more warm distilled water. Returned damp filtered PETN to beaker with 600 ml distilled water and heated with stirring to 60' C. Ph tested and neutralized with 10% ammonia water. PETN filtered, rinsed and dried on paper, crude PETN was a clumpy and very fine white powder. It resembled the consistency of PETN spilled from cut det cord I have handled.

PETN was dissolved in 270 ml of acetone in covered jar with stiring in hot water bath as temperature was brought to 55' C. 1g each of urea and bicarbonate were then added. NO AMMONIA WATER WAS ADDED AT THIS TIME as solution tested slightly basic.

Heat was turned off, stir continued on high and dropwise addition of 250 ml of warm water with 2.5 g of dissolved urea started along with 200 g of crushed ice in small portions.

About 40 minutes to add all ice and water. Mixture was then filtered and rinsed with warm water, sucked as dry as possible in Buchner funnel and dried on paper.

Some loss past filter occured, and more stuff coming out of solution in the flask of filtrate from recrystalization was noted the next day. The yield before recrystalization was 64 g. After was 53 g. The apparent dry volume went down by perhaps 1/3 from the crude product after recrystalization.

Consistency of product is odd, matted glittering white needle like crystals. It looks kind of like dry fluffed commercial pyrocellulose- Not dusty, but not free flowing either. Definitely not a desirable consistency for loading, it pours about like chopped fiberglass insulation. A 100mg dry sample compressed in Al foil packet and struck briskly between steel surfaces detonates violently, embedding bits of foil into nearby surfaces.

I'd like to get a denser and more pourable product.


[Edited on 31-12-2010 by Bert]

[Edited on 31-12-2010 by Bert]

quicksilver - 31-12-2010 at 08:11

You can. - There are certain issues that if addressed will get you there.....
As long as needles formed you're at least at the nitration stage. The whole purpose of strict attention to QC with the pentaerythritol in industry is that the paint industry pentaerythritol is SO poor it will at best give a lousy yield let alone fully the proper level of PETN. I have seen very elegant needles (3mm+) which shaved beautifully into granules. This was nearly always from reagent-level quality and nearly anhydrous HNO3.
The use of nearly anhydrous acid will get the synthesis to that point. Re-crystallization of solid esters is a must. It may test basic to a surface test but within the crystal you'll have a different story. Mixed acid (from solid alkali metal nitrates) CAN result is fully nitrated end product if precursor is high quality & temp/time issues are covered well.
The reason I have mentioned the quality of the pentaerythritol at various times was not only the yield but the low quality of paint-grade pentaerythritol has shown serious problems during war time emergency production.
No needle product will flow. It must be shaved to the 4 um and smaller level and an anti-caking agent used. The most difficult needle product to work with had always been nitrogunaadine which did not shave what so ever. The most dangerous was MHN which had roughly the same sensitivity as ETN re: friction / impact initiation. Since Urea was used as stabilizer, strict attention should be paid to decomposition from inside crystal. Surface ph can be VERY deceptive. The whole purpose of diphenylamine was the discoloration indicator when used as a stabilizer. This CAN be extracted from smokeless powder with little difficulty.
Industrial acetone will leave some hydrocarbons in finished product. Depending upon levels, shaving may be inhibited by same. Microscopic examination will tell a story if needles are of inconsistent shape, with, density (400x). Anti-caking agent and light manipulation should shave down to that level & maintain longevity of product if previous issues are covered in full. Often two re-crystallization are used to achieve higher level of brittle crystal lattice resulting in excellent shaving through light manipulation. Unless all interior acidic elements removed, shaving process will accelerated decomposition.

[If you can get it, please] See "The Pentaerythritols" by Berlow.

[Edited on 31-12-2010 by quicksilver]

Bert - 1-1-2011 at 07:25

Any small scale "shaving" techniques?

User - 1-1-2011 at 08:34

Another method to obtain a more crystal like structure is recrystallization from toluene.
I get cubic high density crystals this way.

Urbanski wrote some words on this.
Toluene is a very good recrystallization medium for its solubility of petn only at high temps.
If desired you can squeeze out more from the liquid by adding water.



[Edited on 1-1-2011 by User]

Bert - 1-1-2011 at 10:38

I have toluene available, can you point to solubility vs. temperature data?

Downloaded Urbanski years ago, it's on a computer I won't have access to for a couple of weeks though.

Sephi - 1-1-2011 at 12:06

et voilà

PETN_sol.jpg - 59kB

quicksilver - 1-1-2011 at 12:07

Shaving is merely the rubbing, crushing light manipulation of crystalline materials against one another. Often, in certain materials and circumstances, it happens very naturally. It IS something to practice high safety levels with (obviously) however if the needle is structured trim and brittle, it will take place simply buy manipulation of the substance from one container to the next, from simple gentle manipulation (for instance in a static-free bag) can crush to extremely fine powder, most ridged refined crystal forms.

Bert - 1-1-2011 at 20:05

Frankly, the shaveing procedure doesn't sound like it will produce a DENSE product.

What is the recommended mechanism for growing cubic crystals from toluene- Slow cooling with agitation, at a guess?

gnitseretni - 2-1-2011 at 05:14

Shaving won't make the crystals denser, it will reduce their size and you will get less/smaller air pockets when you press it and thus a higher density. At least that's how I understand it.

quicksilver - 2-1-2011 at 11:23

Cubic crystals or crushed needles STILL need to be reduced to 2 um or there-abouts to compress so as to eschew air pockets. The point is to reduce size of particulate (solid).

{see gnitseretni 's comment above.}

Which would be easier to manipulate? There IS a patent to maintain clean cubic crystals in Lead Styphate (Do a search: I posted it several years back) however the thrust of the patent was for manipulation: to make the product pour into tight fitting containers. To increase density the best possible method is to liquefy, eliminate bubbles, solidify, etc.
There ARE "trade secrets" to maintaining very TINY and extremely brittle needles that fragments apart into near dust however. That in so far as I am aware is a temperature re-crystallization scheme.
Keep in mind that solvents in "paint-grade" contain enormous amounts of other materials. Frequently hydrocarbons, that can result in exactly the opposite of the desired result by leaving behind a sludge of oily contaminants.
The idea of using varying solvents to produce variety in crystal design is very workable but not with kitchen chemistry. The materials must be appropriately pure. Distillation apparatus is your friend. One thing that should be done with a degree on consistency is when such glassware is first obtained, is to make several distillations to familiarize oneself with temp control and to have sources of truly pure solvents. Reagent benzene is commonly sold at close to $200 a gallon at true reagent grade.

DNA - 31-1-2011 at 02:21

So just to get this correct, the advantage of having very small particles is that you will be able to get a higher density when loading because there will be less airpockets.
Higher density means higher VoD, but does the density also correlate to sensitivity, will it be harder to detonate or easier etc?

And one comment on the solubility table.
On powerlabs it gives a solubility of PETN of 58g/100mL acetone @ 50*C.

This is confirmed by the following paper:

Quote:
Solubility of Pentaerythritol Tetranitrate
Robert N. Roberts, Robert H. Dinegar
J. Phys. Chem., 1958, 62 (8), pp 1009–1011
DOI: 10.1021/j150566a032




[Edited on 31-1-2011 by DNA]

[Edited on 31-1-2011 by DNA]

Attachment: solubility petn.pdf (344kB)
This file has been downloaded 1194 times


gnitseretni - 7-2-2011 at 11:05

Did another PETN synth to try out my homemade addition funnel. Works like a charm so far ;)

I cast the "hopper" part from aluminum using the lost foam technique. Made a hopper from styrofoam, glued on a sprue and buried it in dry sand and poured aluminum over it and voila. Not as easy as I make it sound though. That was my 4th casting and even IT didn't completely fill out. But it's acceptable. The auger is just a long screw, and the motor and gears came out of a printer.

Some pics of the addition funnel:


Direct link: http://img52.imageshack.us/img52/5131/funnel001.jpg



Direct link: http://img820.imageshack.us/img820/6439/funnel002.jpg


Here's a short video of it in action: http://www.youtube.com/watch?v=BrjFfuxVc90


Some more pics:


Direct link: http://img6.imageshack.us/img6/7548/sl731092.jpg



Direct link: http://img573.imageshack.us/img573/8659/sl731093.jpg



Direct link: http://img195.imageshack.us/img195/9282/sl731095.jpg



Direct link: http://img690.imageshack.us/img690/8678/sl731097.jpg



Direct link: http://img822.imageshack.us/img822/2262/sl731098.jpg

232g uncrystallized PETN from 100g PE.

Direct link: http://img715.imageshack.us/img715/4558/sl731102.jpg

[Edited on 7-2-2011 by gnitseretni]

Bert - 7-2-2011 at 12:19

Interesting little pilot plant you have there.

What is the mixer blade- Stainless steel?

Any feedback control of addition rate? Temperature sensor in the reaction vessel, PID controller... Or is it a pre set constant rate of addition.

mabuse_ - 7-2-2011 at 12:32

That funnel is really cool.

If saved an old mixer for such purposes too. But i wonder how the stirring device will react to HNO3? I would expect it to rust really fast...?

And what's that green stuff? Antifreeze?

gnitseretni - 7-2-2011 at 13:28

Addition rate is constant. (About 4g per minute) I tried making a PWM with a 555, and although it worked for a smaller motor, it didn't work with this one. It does without the gears but not with the gears. Not enough juice I guess.

The mixer blade is some shitty grade of stainless steel, and yes it gets rusty fast. But to clean it just dip it in HCl. I've been wanting to make one out of aluminum but keep putting it off.

Green stuff is antifreeze, yes.

Bert - 14-2-2011 at 08:54

Quote: Originally posted by User  
Another method to obtain a more crystal like structure is recrystallization from toluene.
I get cubic high density crystals this way.

Urbanski wrote some words on this.


User, could you point to which volume/page of Urbanski addresses this? I've had a chance to look at the index of my PDF's but have not located this- Lots of material to sift through there!

[Edited on 14-2-2011 by Bert]

quicksilver - 14-2-2011 at 10:43

Quote: Originally posted by gnitseretni  
Addition rate is constant. (About 4g per minute) I tried making a PWM with a 555, and although it worked for a smaller motor, it didn't work with this one. It does without the gears but not with the gears. Not enough juice I guess.


You may want to consider a CD4536b timer (CMOS type) Fairchild made them. This is an IC and programmable to minutes hours days. A serious little chip, it handles up to (I believe up to 18-20v so it's not a 555 that has to run as a feed circuit alone to power a motor!).
MANY people experiment w/ the 555 & become discouraged due to having to design two separate circuits but IC's are a vast improvement due to many being made to handle higher voltage than older active components. It's a very standard 16 pin IC and actually can be pulled from higher powered timer designs such as a microwave oven timer system. They (CD4536's) and much more modern chips save a great deal of work when designing something of that nature.

There IS a very modern timer CMOS chip that (relativity) high voltage but I forgot it's model. If you Google cd4536 Fairchild, you'll likely get the new ones too that are REALLY nice. The 4536 is like the 555 - it cost less than a dollar & are common but the newer ones (IC's) cost more but you get a great deal more in features.




[Edited on 14-2-2011 by quicksilver]

Rosco Bodine - 15-2-2011 at 00:39

That powered auger drive addition funnel / hopper is a neat improvisation.
A variation on the idea could be made from a woodboring auger bit run inside a tube
with a tee section fed by a hopper. This could have a bit longer reach at the discharge end.
This would be handy also for making nitrate additions. A thermocouple sensor and controller setup
could be used to pace the additions based on temperature, interrupting (Not Enabling) the additions
for a selected interval upon temperature rise above a setpoint and resuming (Enabling) additions
on temperature fall to below the setpoint .....basically providing hardware logic "AND" decision function
True?(Enable) / False?(Not Enable) to your timed cycle drive motor. Your addition funnel would then operate
as a thermostat for the exotherm regulating the reaction temperature by rate of addition. Then you would
have a "Thermally Sentient" intelligent powder addition funnel :D

quicksilver - 15-2-2011 at 07:19

Have you gotten as far as a schematic or a rendering (whole unit) drawing?
I'm getting much more interested in things of that sort. I only wish I had written down ideas I had thought of in the past; as the more I learn about today's engineering, the more many ideas seem to be within reach.



@ Bert: According to table (above) that solvency is seriously low (& require significant heat). If such a re-crystallization mechanism were to produce a cubiod it would entail enormous levels of solvent for this to be effective on anything but a lab level. Utilization at 110 C+ doesn't appear to be an ideal situation.... Common re-crystallization with acetone, when using temperature extremes produce a very fragile crystal. With the widest possible extremes (the water being close to freezing & acetone being boiling) the fragility of the needle is such that it cannot maintain it's form in a dry condition with even gentle flow from pouring bottle to bottle. An experimental model of that with an ounce or so would show this to be a workable method of shaving to an extremely low particulate mass.
Purity of acetone becomes a factor additionally in that often "paint-grade" acetone contains petroleum distillates which would hamper crystal structure and leave impurities. I have in the past used distilled acetone & the results were different enough to be worth the effort (it's actually only a few minutes of work as it boils so easily). Distilled benzene is (approx) $200 a gal from Spectrum. I don't like working w/ benzene too much but found that similar to toluene; it had a high boiling point, thus being more time consuming to get a pure solvent.

Rosco Bodine - 16-2-2011 at 09:48

No I haven't drawn a schematic but it should be simple enough to signal process the output a thermocouple input controller like an Omron programmable PID controller. Basically I was thinking you could output the controller, inverted if necessary, to the reset pin of a 555 timer chip and get the aforedescribed AND logic function to ENABLE the 555 timer to RUN and cycle through as an on/off astable multivibrator having settable duration on and off times. The ON output of the 555 timer would drive an optoisolator input
having a triac output to enable / not enable the AC gearmotor turning the auger. So the auger would be rotated by the AC gearmotor for periods corresponding to the duty cycle settings for the 555 timer. I would have to study the truth table for the 555 because it has been years since I put chips on perfboard to do whatever.

To do this right would really require that the thermocouple input controller have a setpoint / reset differential capability
(Schmitt trigger adjustable hysteresis) so that for example, if the setpoint is 30C for transitioning the controller output signal, that it must drop back to below the setpoint temperature, by a user specified amount before "reset" which transitions the controller output back again. So the "hunting range" for the closed loop can be set at a half degree C or one degree C or one and eight tenths degree C .....whatever differential you specify for the "reset on temperature fall to value".

To match the thermodynamic curve of a nitration reaction,
there would really be needed a kind of "ramp controller"
added to the timer stage so that each ON cycle of the timer is progressively varied by a user specified percentage from the previous completed ON cycle. A digital controller that could decrease the ON period by additive tenth / tenths seconds for each successive ON period would be needed
to rate match the process demand so that the oscillations in temperature are dampened from the reagent supply side and the input controller has less process variation supervision and limiting to do. That ought to be simple enough to implement huh :D

gregxy - 16-2-2011 at 10:35

The easy way to create your own controller of this type
is with a micro controller. For example the PIC16F876
which has a 10 bit A-D converter to read the input and
a pulse with modulator that can control a motor.
The rest is done in software. The chips are kind of fun to program. The chip is about 5$ and a board to program the
chip is about $30 on Ebay.
A standard thermocouple would probably not generate enough voltage but there are probably temperature transducer chips
that could be used.

Bert - 17-2-2011 at 06:20

I am a lazy b*5tard. I just buy a PID controller with appropriate thermocouple, and add a solid state relay if the setup is used for a high current application. For use in an acid bath you'll need to protect the thermocouple. I use a meat probe type protected with an oversize piece of Teflon "spaghetti" tube filled with thermo conductive grease, poke the probe into it and keep the open ends above the surface.

http://www.susanminor.org/forums/showthread.php?315-PID-Cont...

You will learn a lot more making it from scratch though. I have a couple of these rigs, one for my bullet casting smelter (high amp, with SSR) and another for a small heater on my lubricating/sizing press (low amp, no SSR)

http://gunloads.com/castboolits/showthread.php?t=34547&p...

These things learn the response time of your system after a couple of cycles. That could be exciting in a highly exothermic nitration during the first cycle... Best have a slooooow addition rate and watch it closely.

Rosco Bodine - 17-2-2011 at 07:50

Yeah I too am all for using the programmable front end and I think some of them do have the programmable differential for reset. Most of them have some slight
differential anyway simply to prevent rapid oscillation cycling.

Having a timer that will run cycles having a progressively decaying duty cycle
is a cute trick for analog. It would be like a delay windshield wiper that adds a second to the delay time every time it cycles.

quicksilver - 17-2-2011 at 08:50

I know I pulled this a bit off track but I found a great little inverter design with just two power transistors that really could work. There are SO many decent schematics out there - especially from old Popular Mechanics reprints that this whole concept could be pulled forward into a great design as all the tough stuff has been shaken out (the basic mechanical design).

An interesting technical question is whether the addition in a given nitration NEEDS (human)augmented timing or whether it would be ideal to make the timing electro-mechanical?
I know that generally this would depend on some variables (outside temp, etc) & the specific nitration: but from a theoretical ideal: I've thought this was an interesting issue.




[Edited on 19-2-2011 by quicksilver]

Rosco Bodine - 17-2-2011 at 12:13

Do your itty bitty baby molecules need nurturing ???? :D you know ....like people talk to their plants......as the seedlings break through .....come on little fellows, you can do it :D Maybe music is the key .....

http://www.youtube.com/watch?v=Ty7nf1PBkKM

 Pages:  1