Sciencemadness Discussion Board

Stability of picric Acid (Trinitrophenol)

TheGarageChemist - 30-5-2020 at 12:00

On the internet there are many conflicting arguments about the stability of picric acid, this can make it hard for people like me who want to know more about various compounds. So, how sensitive is picric acid? Is it truly the lab destroyer some say it is?

mackolol - 30-5-2020 at 12:11

It's not bad until it reacts with heavy metals forming very fragile and explosive salts.

greenlight - 30-5-2020 at 12:47

It is definitely not as dangerous as it is made out to be.
If it is washed and in powder form it is quite stable.
I have heard that large crystals are unstable but neonpulse on this forum has grown some quite large crystals and there was no accidents.

As said above, contact with metals can make sensitive picrates that can detonate for example if they form on the threads of a container it is stored in.


Microtek - 30-5-2020 at 14:16

Be sure to distinguish between (chemical) stability and sensitivity to external stimuli. Picric acid is decent in both respects. As was said above it may react with some metal, if a small amount of moisture is present.

Belowzero - 30-5-2020 at 14:58

I was under the impression that it's often stored wet on purpose as to reduce its explosive properties.

Quote:

As was said above it may react with some metal, if a small amount of moisture is present.


This would suggest dry storage is 'better' ?

BromicAcid - 30-5-2020 at 19:06

Back when I used to do hazardous waste disposal I was told that the issue with old units of picric acid was that they had metal lids. The picric acid would end up in the threads, react with the metal and form picrates which were notably shock/friction sensitive. The vast majority of the units that we were given for disposal however were in poly bottles with water added. Our usual procedure was to pin the bottle under water overnight then open the next day and pour out. This was to get water into the threads and make sure all the picric was wet. It was my understanding that this was a holdover from metal lids and that it was not entirely necessary any longer.

Amusingly enough, just before I left that job I was down in Texas and we were gifted with a 2.5 kg unit of picric acid in a clear glass jar with a metal lid for disposal ;)

Herr Haber - 31-5-2020 at 07:31

Quote: Originally posted by greenlight  

I have heard that large crystals are unstable but neonpulse on this forum has grown some quite large crystals and there was no accidents.


Naaaah. Well, unless 8-10 cm needles is not big enough :)

caterpillar - 6-6-2020 at 16:38

Avoid contact with metals, their salts and AN and sleep well.