Methyl ammonium nitrate

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According to Urbanski in, "The Chemistry and Technology of Explosives," vol 2, Methyl ammonium nitrate was first used as an explosive ingredient by the Germans during World War Two. Urbanski, not following standard naming conventions used by chemists, called the substance mono-methylamine nitrate, a name that has largely stuck among chemists who formulate energetic materials. Methly-ammonium nitrate is created when methylamine is mixed with strong nitric acid.

Methyl-ammonium nitrate is somewhat similar in explosive properties to ammonium nitrate (AN) which yields 85% of the power of nitroglycerine when the ammonium nitrate is incorporate into an explosive. The addition of the carbon containing methyl group imparts better explosive properties and helps create a more favorable oxygen balance.

Following World War Two, relative to less costly ammonium nitrate, methyl-ammonium nitrate was largely ignored by explosives manufacturers. Ammonium nitrate fuel-oil mixtures (ANFO) were sufficient for most large-diameter explosives uses.

Methyl-ammonium nitrate saw a resurgence when E. I. du Pont de Nemours and Company, Inc., seeking to lower the cost of its TNT-based "Tovex" water gels, incorporated a mixture of methyl-ammonium nitrate with ammonium nitrate which served as a basis for DuPont's water gels manufactured under the names, "Tovex" "Extra" and "Pourvex" "Extra." Methyl-ammonium nitrate, also known as PR-M (which stands for "Potomac River - Mono-methylamine nitrate") soon was seen as the possible path toward creating a low cost blasting agent (water gel explosives) that might replace the explosives based on nitroglycerin (dynamites).

In late 1973, DuPont started to phase out dynamite and replace it with water gels based on PR-M.

However, PR-M proved to have unusual "mass effects." That is, if there was sufficient mass, under certain conditions, PR-M could explode without warning. On August 6, 1974, a tank car contain PR-M blew up in Wenatchee rail yard, killing two and injuring 66 others. On July 4, 1976, a PR-M storage with thousands of gallons of PR-M detonated at DuPont's Potomac River Works.^[1] Though there was no loss of life, there were many injuries and a substantial loss of property.

Within two years, DuPont moved out of water gel explosives.