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ManyInterests
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Quote: Originally posted by axd1995  | I used 20ml of 92% sulfuric acid and 3.6g of salicylic acid. After heating, I added salicylic acid, but it couldn't completely dissolve. I raised the
heating temperature and there was a strong phenol odor, but it still couldn't completely dissolve. Why? |
I would suggest using Rosco's picric acid method. The only thing is that you need more nitrate salt than for using ASA. But since you're using
salicylic acid (which in my own opinion, is superior to ASA in every way, I think my picric acid was ultra pure even without a recrystalization when I
made it with salicylic acid).
I would suggest using more sulfuric acid. I use 95+% sulfuric acid (I clean drain cleaner grade with H2O2 and then boil it for 95 minutes or so). Like
4ml for every gram of salicylic acid. this is a great excess, but I was able to fully dissolve all of my salicylic acid in H2SO4 before I even began
the heating step, so I know it is an excess, but it will guarantee that you will be able to make it work.
Attachment: roscopicric.pdf (89kB)
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ManyInterests
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I made a bit more picric acid, but one thing I did differently is that I used a lot more ice cold (near freezing) water to wash everything out. My
losses weren't as bad as I thought they would be, but when I decided to a burn test, it was different.
How is picric acid supposed to burn? The last batch I did where I used burned like gunpowder in a puff, and it did that even after I recrystalized it
(and I used more than needed water and didn't boil off a significant amount of the water when I suspected there was a lot of sulfuric acid in there)
and after filtering it out (after cooling of course) it still burned really fast.
My current one takes a bit to melt, then it sizzles, and only towards the end it catches fire. with a lot of black smoke and a lot more flame than
anticipated.
I am quite curious as to what is supposed to happen?
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B(a)P
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| Quote: Originally posted by ManyInterests | I made a bit more picric acid, but one thing I did differently is that I used a lot more ice cold (near freezing) water to wash everything out. My
losses weren't as bad as I thought they would be, but when I decided to a burn test, it was different.
How is picric acid supposed to burn? The last batch I did where I used burned like gunpowder in a puff, and it did that even after I recrystalized it
(and I used more than needed water and didn't boil off a significant amount of the water when I suspected there was a lot of sulfuric acid in there)
and after filtering it out (after cooling of course) it still burned really fast.
My current one takes a bit to melt, then it sizzles, and only towards the end it catches fire. with a lot of black smoke and a lot more flame than
anticipated.
I am quite curious as to what is supposed to happen? |
Your second description is closer to how it should behave. First it melts, then burns with a sooty flame.
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ManyInterests
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Ok good. Seems like I am finally making fairly pure stuff. However I am a bit concerned about my old batch. While I did recrystallize that, it still
did burn quite fiercely like gunpowder. I turned some of it into ammonium picrate to try to see if I can make a detonator strong enough to set it off
(I used a 7mm Remington Magnum shell filled with 4 grams of melt-cast ETN and 0.4 grams of NHN/ETN mixed as primary). I tried one of those against a
witness plate and it nearly obliterated the plate.
I am wondering why the other picric burned as it did, especially after recrystallization which should have removed all sulfuric acid residue.
I need to mention that the new batch used an excess of sodium nitrate. Around 2.5 grams of sodium nitrate per gram of salicylic acid instead of 2.1.
Maybe the salicylic acid was fully nitrated in those batches? I am just speculating.
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