HMX

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HMX, also called octogen or cyclotetramethylene-tetranitramine, is a powerful and relatively insensitive nitroamine high explosive, chemically related to RDX.

History

First made in 1930, it is used almost exclusively in military applications, including use as the detonators in nuclear weapons, in the form of polymer-bonded explosive, and as a solid rocket propellant.

Its molecule is an eight-membered ring of alternating carbon and nitrogen atoms, with a nitro group attached to each nitrogen atom. Because of its high molecular weight, it is one of the most powerful chemical explosives manufactured, although a number of newer ones, including HNIW and octanitrocubane, are more powerful and/or less sensitive. It is more complicated to manufacture than most explosives and this confines it to specialist applications.

Other names sometimes used for it include octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocane, tetrahexamine tetranitramine, or cyclotetramethylene tetranitramine. It may be produced by nitration of hexamine in the presence of acetic anhydride, paraformaldehyde and ammonium nitrate. RDX produced using the Bachmann Process usually contains 8-10% HMX.

Like RDX, it has various mistranslations of its acronym including High Melting eXplosive, Her Majesty's eXplosive or even High-velocity Military eXplosive, but in fact the acronym simply means "High-Molecular-weight rdX".

Properties

The velocity of detonation of HMX at a density of 1.90 g/cm³ is 9,100 meters per second.

Its CAS Number is 2691-41-0. The chemical formula is C₄H₈N₈O₈. It is a colorless solid with a melting point of 276 to 286 °C, although it usually decomposes at 280 °C. Its molecular weight is 296.20 and its practical maximum density is 1.91 g/cm³, with a theoretical maximum crystal density of 1.96. It is slightly soluble in water.

HMX is used in melt-castable explosives when mixed with TNT, which as a class are referred to as "octols."

References

• Cooper, Paul W., Explosives Engineering, New York: Wiley-VCH, 1996. ISBN 0-471-18636-8
• Urbanski, Tadeusz. Chemistry and Technology of Explosives. Vol. III., Warszawa: Polish Scientific Publishers, 1967

Manufacturers

• Prva Iskra Namenska AD (Serbia)