Tetranitromethane

Tetranitromethane or TNM is an organic oxidizer with chemical formula C(NO2)4. Its chemical structure consists of four nitro groups attached to one carbon atom. In 1857 it was first synthesised by the reaction of sodium cyanoacetamide with nitric acid.

Uses
It has been investigated for use as an oxidizer in bipropellant rockets, however its extreme explosive sensitivity makes it effectively unusable. In the laboratory it is used a reagent for the detection of double bonds in organic compounds and as a nitrating reagent. It has also found use as an additive to fuel to increase the cetane number.

Preparation
TNM is a pale yellow liquid that can be prepared by the nitration of acetic anhydride with anhydrous nitric acid.

The first industrial scale production was started in Germany during World War II in an effort to improve the cetane number of diesel fuel. This process improved the original method, which started with acetic acid and nitric acid. . Without regard to yield or cost, approximately 10 tons of TNM were produced in a few weeks. However, this production process has not been used again industrially after the end of the war, because of high associated costs.

For commercial use a cheaper method starting from acetylene has been used. First, acetylene is reacted with nitric acid containing mercury nitrate, resulting in nitroform (trinitromethane) and a mixture of carbon dioxide and nitrogen oxide as waste gas. The resulting nitroform is converted to TNM by adding sulfuric acid at higher temperatures. With this method a yield of 90% before purification can be reached. 

Safety
TNM is an explosive that is sensitive to heat, friction and shock. It is reasonably expected to be a human carcinogen.