[Babcock_Hall]

http://www.orgsyn.org/demo.aspx?prep=CV2P0228
https://pubs.acs.org/doi/abs/10.1021/ed082p1310.2
https://www.compoundchem.com/2016/11/07/24-dnp/

I am recrystallizing about a gram of dinitrophenylhydrazine from n-butanol today (about 30 mL per gram of 2,4-DNPH).  My intended application is a TLC spray or dip for aldehydes and ketones.  The commercial material was very wet, and I thought that it would be easier to weigh accurately if it were in the form of dry crystals.  However, a 2005 J. Chem. Ed. article noted that it must be stored moist.  How should the leftover DNP be stored?  I was thinking of using a brown glass bottle and storing in the refrigerator or freezer, but I am unsure whether or not I should add a small amount of water.  This compound is a shock explosive, and from what I can gather there was some interest in its disposal in Great Britain circa 2016.

[rolnor]

I had a jar of this for many years as a dry powder without any special considerations. It was probably as old as from the -80s.
It was a lided brown glass jar.

[Babcock_Hall]

The water made it difficult to weigh accurately, but my recovery was probably less than 50% when I recrystallized it from n-butanol.  I will try to make a dip or spray today and practice with benzaldehyde.

[rolnor]

I think I used a dilute solution in EtOH with a few drops conc. HCl. I dissolved it first in conc. HCl then add EtOH. Its not very critical with concentration. I should say that it is a good thing to be carefull and keep it moist. I also had a very old 250g jar of mCPBA that was 100% pure, no water or chlorobenzoic acid added. This is dangerous and it was before people realize that it should be kept moist and dilueted.

[wildfyr]

250g jar of mCPBA that was 100% pure

!!!!!