mick
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Advice on the sensitivity of dry picric acid
I was asked to look a an old store of chemicals at work today, people are panicing about an almost certain H & S inspection due the miss-recording
of high powered radiation sources. The most worrying thing I found was a 500ml jar containing about 100g picric acid under water but there is dried
picric acid on the outside of the jar (looks like someone has poured some out and left it to dry) and there could be dry acid around the top. Instinct
says to put in a bucket of water to soak and loosen the top under water. Is it very fiction sensitive. This might sound over the top but it is work.
Any advice would be appreciated.
PS The acids cupboard would have been a gold mine a few years ago when you could give stuff away. Fuming nitric and fuming sulphuric acid. perchloric
acid, chlorosulphonic acid, acetyl chloride, benzoyl chloride, phosphorous trichloride, phosphorous oxychloride etc all sitting in a cupboard with
half a gallon of conc ammonia. The tops and labels are just about falling to bits.
Mick
It was a metal cabinet as well
[Edited on 20-8-2004 by mick]
[Edited on 20-8-2004 by mick]
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JohnWW
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It sounds as if you are onto some good stuff there! If your firm is getting rid of the stuff, ask to take it home. If necessary, get new tops for the
bottles.
John W.
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markgollum
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I really wouldnt worry about the picric acid, as its not sensitive to reasonable amounts of friction or impact. Picric acid, also known as
trinitrophenol (TNP) and lyddite, was at one time an important millitary HE used as a secondary for filling various munitions, including artillary
shells. It is slightly more powerful than TNT.
However, TNP can react with metals to form picrates, some of whitch are very sensitive explosives, eg lead picrate, but not all picrates are
sensitive, some are, in fact, actually less sensitive to impact than TNP itself. Aluminium picrate is, if I remember correctly, one of these.
What was the lid of the container storing the TNP made of?
If it was made of metal and is coroded then you may have the coresponding metal picrate present.
What color is the dried TNP on the container? many picrates are a different color than TNP (yellow, or if re cryst from HCl, white).
If I were you, I would scrape a little bit of picric acid off the container and see how it burns, if it burns with a flash than picrates are very
likly present, pure picric acid burns calmly and not too fast.
Again, you are not going to have an accident if there are no picrates present, pure picric acid is not sensitive to anything near the stresses applied
during normal handling.
And if you find that there are picrates present If they are from the lid(Al, Cu ,Fe)
then be careful, but if I remember correctly those picrates arent too too bad(look them up in the Enclyclopedia of explosives and related Items to
confirm, I dont have time to do that my self right now).
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BromicAcid
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I have no experience in the matter but I have heard about the bomb squad being called out several times to deal with exactly what you're talking
about. It actually happened at my school, an errant bottle of picric acid had managed to escape detection and crystals of it had formed around the
inside bottom of the stopper. That wing of my school was evacuated. But, then again people overreact about many things regarding chemicals.
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mick
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Thanks
It is a plastic top, no metal, it should be OK to give a good wash and open it slowly. javascript :icon(' '
I can not work out these icons.
Mick
[Edited on 21-8-2004 by mick]
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JohnWW
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Some plastic tops are liable to deterioration, from either volatile organic substances given off by the slow auto-decomposition of the organic
compounds contained in the bottles, or through exposure to sunlight. Tops made of aluminium or tin-plated or painted steel would be corroded by any
strongly acid or alkaline vapors given off by the contents.
John W.
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Marvin
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I would agree mick, douse completely with water (distilled), rubber gloves and open under water. When the water has entered the container leave it
for a while. There is essentially no risk if there has been no contact with metals or metal salts. Picric acid has toxicity problems but thats about
it.
I think the salt markgollum was thinking of was ammonium picrate, aka explosive D, aka about as easy to detonate as granite aka "why the hell did
I make a high explosive and then turn it into this virtually inert salt".
From memory aluminium and tin would be fine anyway. Tin particulally is safe because at one time picric acid in tin tubes was used as a form of det
cord.
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mick
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Thanks
I have not found any info on someone being hurt by opening an old bottle of picric acid with a plastic top . I will give it a clean, was thinking of
wrapping some PTFE tape round the top which is good for friction but I have just thought it is also good for static so forget that one.
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