Katie
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Question about lead azide synthesis
In my dex. Lead azide synthesis, I follow a procedure which states “NaOH is added to lower the pH to 5”. I assumed they meant “raise the ph to
5” so that is what I do, although I use potassium hydroxide instead.
Then recently I read a scientific paper that said the reaction should be carried out in basic conditions, but 5 is acidic!
What is the correct ph to synthesize dextrinated lead azide? And can I rinse the LA I already made with a pH of 5 in a hydroxide or bicarb solution to
emulate having synthesized it in a basic solution?
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Etanol
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You noticed correctly. pH of unclean Pb(NO3)2 is 2...4, clean nitrate have pH about 4,6..5.
Recommended value pH to dextrinated lead azide from lead nitrate is 4,3..4,6. The correct synthesis is described in the patent US3173818 "Manufacture
of dextrinated Lead Azide" and " Bagal. Chemistry and technology of initiating explosives." p230-234 - "Method for the continuous production of lead
azide". Solutions of NaN3 and Pb(NO3)2 should be simultaneously added to the dextrin solution within 30-60 minutes
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Rhodanide
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When I speak of my experiences with any sort of Azides salt in acidic medium, none of the stories turn out good. HN3 will find any way of escaping
even under the mildest of acidic conditions. The Pb azide syntheses I've seen try to keep the ph at the very least neutral or very slightly basic
using dilute aq NaOH. Any sort of azide synthesis in the presence of acid is, in my opinion, ludicrous. HN3 is no joke.
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Katie
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Quote: Originally posted by Etanol  | You noticed correctly. pH of unclean Pb(NO3)2 is 2...4, clean nitrate have pH about 4,6..5.
Recommended value pH to dextrinated lead azide from lead nitrate is 4,3..4,6. The correct synthesis is described in the patent US3173818 "Manufacture
of dextrinated Lead Azide" and " Bagal. Chemistry and technology of initiating explosives." p230-234 - "Method for the continuous production of lead
azide". Solutions of NaN3 and Pb(NO3)2 should be simultaneously added to the dextrin solution within 30-60 minutes |
Thank you for that patent, I noticed several things I’d like to do differently in my next synth.
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Etanol
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| Quote: Originally posted by Rhodanide | | When I speak of my experiences with any sort of Azides salt in acidic medium, none of the stories turn out good. HN3 will find any way of escaping
even under the mildest of acidic conditions. The Pb azide syntheses I've seen try to keep the ph at the very least neutral or very slightly basic
using dilute aq NaOH. Any sort of azide synthesis in the presence of acid is, in my opinion, ludicrous. HN3 is no joke. |
I understand your perplexity. But the "neutral" Pb(NO3)2 solution does not exist. Measure the acidity of your nitrate. At pH7 only Pb(OH)NO3 and
Pb(OH)2 are exists. Nice article in Russian: "The influence of some factors of product synthesis on the formation of crystal grains (for example, the
production of dextrinated lead azide ) Part 1,2,3"
https://cyberleninka.ru/article/n/vliyanie-nekotoryh-faktoro...
Authors show grains of lead azide at pH 3,7...4,6 in Part 3.
[Edited on 22-4-2020 by Etanol]
[Edited on 22-4-2020 by Etanol]
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