decomposes >265 °C
|ammonium picrate||molecular mass
Ammonium picrate, also called 2,4,6-trinitrophenol ammonium salt, ammonium trinitrophenolate, Dunnite, or Explosive D, is prepared in much the same way as nitrogen triiodide. Ammonium picrate was first prepared in 1841 by a scientist named Marchand. It was not used until 1869 when it was mixed with potassium nitrate as a propellent for rifles. Alfred Nobel patented it in 1888 for Dynamites. The US Army picked it up in 1901, and the Navy floated it in 1907. It saw peak production during WWII but has since fallen victim to progress in chemistry. This explosive is relatively stable, therefore safer to prepare and handle. The only real problem is getting ahold of picric acid which is a regulated explosive chemical. Very few laboratories still use life threatening carcinogens like benzene or explosives like picric acid. That means even if you have the authorization to purchase chemicals you will have a hard time getting any. Not to worry, I have included the preparation of picric acid. Benzene is another matter unfortunately.
|ammonium hydroxide||250-mL beaker|
|picric acid||graduated cylinder|
2,4,6-Trinitrophenol ammonium salt is formed when the ammonium ion, NH4+, attaches itself to the phenol group, OH, of picric acid. I suppose the H from OH is stripped away making O- that balances the positive ammonium ion. To make, dissolve picric acid in excess ammonium hydroxide. Add 1 g of picric acid to a 250-mL beaker then add 100 mL of hot concentrated ammonium hydroxide. Once the picric acid has dissolved, some will precipitate out of solution upon cooling. The liquid must be evaporated to fully precipitate the crystals. Evaporation can be accelerated by heating the solution on a hotplate or in a heated pan of water. More ammonium picrate can be prepared at once by using the same 1:100 ratio of grams picric acid to milliliters ammonium hydroxide. You will need a graduated cylinder to measure the liquid.
The pure substance occurs in two forms, a stable form which is bright yellow and a less stable form which is bright red. The crystals which separate here are the red form. The yellow form can be procured by recrystallizing the red several times from water. The red form will eventually change into the yellow form if stored as a concentrated solution. Keep this material as dry as possible.
Lab Skills|Lab Equipment|Safety|Rogue Science|Links|What’s New|Contact Me|Disclaimer