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Motherload
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If you start adding PE at a temp that's too low .... The PE builds up and not nitrated to PETN. So when the temp rises to the nitration temp .... All
the surplus PE wants to get nitrated at the same time causing hot spots and spikes which is probably what results in runaway signs.
"Chance favours the prepared mind"
"Fuck It !! We'll do it live !!"
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ONLIASHISH
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PETN Synth
Hi Motherload, Thank you for your help,I guessed the same reason as you have mentioned. I did lot of search found I should have done nitration at 15C
to 20C very slowly. I have recrystallize impure PETN with acetone at 50C and then filtered after adding water yield is 12g(instead of 22.1g). Learnt
something from mistake 
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ONLIASHISH
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PETN Synth
Hi 10digit,Thank you for your help. I had pure acids without any other impurities other than water. I had done other synthesis(Nitroglycerine,nitro
urea, GC etc) with same acids . The reason given by Mother load is more accurate for my case.
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Hellbat
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Question about PETN synthesis
Hi, I have found a synthesis description for PETN that uses 65% nitric acid instead of fuming nitric acid: http://www.powerlabs.org/chemlabs/petn.htm
But on many other pages I've read that nitrating PE with the mixed acid method mostly yields Pentaerythritoltrinitrate (PETRIN). It
seems to be soluble in acetone just as well, so the purification by recrystalization would not remove it. Maybe, this guy actually made the trinitrate
without knowing? It's a strong explosive as well.
I've actually found a german synthesis description for PETRIN which was nearly the same procedure as on the website I linked.
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hissingnoise
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| Quote: | | Maybe, this guy actually made the trinitrate without knowing? |
I have the feeling that when Sam Barros 'makes something' he knows exactly what it is he's made!
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Hellbat
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But does anyone have accurate information about that? According to german wikipedia, if PE is nitrated with mixed acid, mostly the trinitrate is
formed...
So, either wikipedia or Sam Barros must be wrong.
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Bert
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Why don't you do an experiment and verify if Wikipedia is wrong, and report back.
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The method and ratios work. I have tried the version of this originally posted by "Boomer" that Sam apparently either directly copied or used the same
information (from Thadeus Urbanski Vol. IV) to derive. Should give 90% + yields with care and the correct grade of pentaerythritol.
| Quote: |
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
------------------------
Nitration:
1. Cool nitration mixture during mixing of acids, thus minimalize even minimal decomposition of HNO3. Nitration mixture must be cooled before
nitration process to temperature of 10°C.
2. While stiring, add pentaerythritee in small portions (1-2g) to nitration mixture, always after previous batch is dissolved. Nitration mixture
gradually thicken as PETN forming in solution.
3. Constantly monitor reaction temperature and maintain it in 10-15°C range. Interval of adding pentaerytritol conform to reaction temperature, must
not rise over 15°C, leave beaker in cold water.
4. Stir with mixture for next 5 minutes after all pentaerythrite is added and dissolved. Mixture is now thick, but stirring is going well. During
nitration process must not be developed any brown fumes of NOx!
5. Now put beaker with mixture into water bath and maintain temperature at 50°C, continuously stir with mixture. During 20 minutes at this
temperature, all of possible sulfoesters come into PETN for maximal yield of nitration.
6. While maintaining mixture at higher temperature, mixture must be monitored for developing of NOx fumes. Only light brown colour can be in shrouded
beaker. Raised development of NOx pointing to higher temperatures used (even during previous nitration) or insufficient chmemicals purity and further
heating may end up in uncontrolled reaction and oxidation of formed PETN. In this case it is better to do not heat at all and end just after nitration
(if brown fumes apperas during nitration), the yield will be lower. In case of accidentally runaway reaction during heating, immedialtely pour mixture
into cold water, don't try stop reaction by cooling beaker, it will not help.
7. When heating after 20 minutes pass off, pour reaction mixture into cold water and follow standart procedure of filtration, neutralization and
purifying of PETN.
Yield was 22,1g of PETN from 10g of pentaerythrite, ~95% of theoretical yield (with 65% HNO3 used).
This procedure is result of my research of most effective method preparing PETN from diluted HNO3. Acid ratios are precisely calculated on data from
PETN nitration graph published by T. Urbanski in his book vol. IV. Generaly said, PETN is forming to maximum 30% of water portion in nitration
mixture. But, when also H2SO4 is contained in nitration mixture, minimum ammount of water must be keep, or oxidation with small yields occur. With
this acid ratios 20% of H2O is minimum. So, this nitration mixture has 20% of water on nitration start and 30% at the end, area for most effective
nitration, but again only with this ratios. For other acid ratios must be all recalculated. Excess of HNO3 is used to controll ammount of reaction
water. Only ammount of nitration mixture can be extended for lower mixture thickness, but it lower utilization of acids and overall efficiency. But it
isn't necessary.
I hope there is no major mistakes in my translation to english ;-)
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I am going to merge your thread with an existing PETN thread-
http://www.sciencemadness.org/talk/viewthread.php?tid=10413&...
And you might want to look at the alternative method posted by Rosco Bodine:
http://www.sciencemadness.org/talk/viewthread.php?tid=6151#p...
[Edited on 11-1-2016 by Bert]
Rapopart’s Rules for critical commentary:
1. Attempt to re-express your target’s position so clearly, vividly and fairly that your target says: “Thanks, I wish I’d thought of putting it
that way.”
2. List any points of agreement (especially if they are not matters of general or widespread agreement).
3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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Bert
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Threads Merged
11-1-2016 at 07:23 |
NeonPulse
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I'll too vouch for roscoes method. It is the best synthesis I've tried. No problem in producing high yielding high quality PETN that is easily
neutralised and Recrystallized. No heating needed and no Dangerous fuming. You do need High strength clear fuming nitric though. But the trouble is
worth it. The end product does seem superior to mixed acid PETN
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gnitseretni
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I don't think the trouble is worth it. Only if you're specifically after PETN for some reason. Otherwise, just go the mixed acids route (assuming
that's the easier route for you). You won't notice the difference between a 7k or 7.5k velocity explosive.
I precool my acids and I add my PE while the acids are still below freezin, and I add it pretty fast. It does tend to heat up pretty fast after a
certain point but as long as you are prepared and have plenty of ice available you'll be fine.
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Microtek
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The superiority of the product has more to do with stability than with performance, I think. It is very difficult to remove the last traces of
sulfuric acid from the product, and this makes it unstable, particularly at elevated temperatures.
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