Manganese heptoxide-1-

Freshly prepared manganese heptoxide. Photo by woelen.

Manganese heptoxide, also known as permanganic anhydride, is a dark green, extremely oxidizing manganese compound with the formula Mn2O7. It will set nearly any organic material on fire, and may explode on contact with metals. It tends to decompose to form manganese dioxide, oxygen and ozone. In hot environments, this may also occur explosively. This compound is not recommended for production and use except by chemists who know what they're doing.



Manganese heptoxide is an energetic material, and will ignite pretty much anything it touches, including ethanol, acetone, cotton, styrofoam, aluminium and bread (albeit with GREAT difficulty). It will explode, even without a fuel, on warming to 95 °C. It produces ozone when it decomposes and this can ignite a piece of paper impregnated with alcohol.


The pure compound is a brown liquid with melting point 5.9 °C. It forms violet vapours if warmed to 40-50 °C and explodes at higher temperatures. Solutions in sulfuric acid are dark green, and this is the most commonly prepared form.


Don't even think about it. But if you really must know:

Add a few drops of 98% sulfuric acid to potassium permanganate. The resulting green liquid is manganese heptoxide dissolved in sulfuric acid, with potassium bisulfate impurities. Always have a bucket with water or sand nearby when doing this reaction.



Manganese heptoxide sets ANY reducing agent on fire. It's also an oxidizer, so a manganese heptoxide fire cannot be deprived of oxygen to stop it. It is also known to be able to explode on its own, so larger quantities should never be prepared. The decomposition of manganese heptoxide produces copious amounts of ozone.


Hydrate thoroughly, preferably adding sodium hydroxide afterwards. The water will convert the manganese heptoxide to permanganic acid, which is far less explosive, and the sodium hydroxide will neutralize any remaining sulfuric acid.



Relevant Sciencemadness threadsEdit

Community content is available under CC-BY-SA unless otherwise noted.