Ammonium permanganate

Ammonium permanganate is the chemical compound NH₄MnO₄, or NH₃·HMnO₄. It is a water soluble, violet-brown or dark purple salt.

Preparation

Ammonium permanganate was first prepared by Eilhard Mitscherlich in 1824 by reaction of silver permanganate with equal molar amount of ammonium chloride, filtering the silver chloride and evaporating the water.
It can also be prepared in a similar way from potassium permanganate and ammonium chloride.

Properties

Ammonium permanganate is a strong oxidizer, owing to its permanganate anion, and it is a moderately strong explosive, owing to the combination of the oxidizing permanganate anion and the reducing ammonium cation. Dry ammonium permanganate can be detonated by heat, shock, or friction, and it may explode at temperatures above 140 °F.
Ammonium permanganate decomposes explosively to manganese dioxide, nitrogen, and water:
Ammonium permanganate decomposes slowly in storage even at normal temperatures. A sample stored for 3 months was only 96% pure, after 6 months it assumed color of iodine and had strong smell of nitrogen oxides. It emits toxic fumes when decomposed by heat.
Quaternary ammonium permanganate compounds can be prepared, such as tetrabutylammonium permanganate and benzyltriethylammonium permanganate.