Hexamethylene triperoxide diamine (HMTD) is a high explosive organic compound. HMTD is an organic peroxide, a heterocyclic compound with a cage-like structure. It is a primary explosive. It has been considered as an initiating explosive for blasting caps in the early part of 20th century, mostly because of its high initiating power (higher than that of mercury fulminate) and its inexpensive production. As such, it was quickly taken up as a primary explosive in mining applications. However, it has since been superseded by more (chemically) stable compounds such as dextrinated lead azide and DDNP (which contains no lead or mercury). HMTD is widely used in amateur-made blasting caps. Preparation and structure First synthesised in 1885 by the German chemist Ludwig Legler, HMTD may be prepared by the reaction of an aqueous solution of hydrogen peroxide and hexamine in the presence of an acid catalyst, such as citric acid, acetic acid or dilute sulfuric acid. The hydrogen peroxide needs to be at least 12% w/w concentration, as lower concentrations lead to poor yields. Citric acid is overall superior to other acids, providing a yield of up to about 50%. The molecule adopts a cage-like structure with the nitrogen atoms having an unusual trigonal planar geometry. Properties as an explosive Like other organic peroxides, such as acetone peroxide (TATP), HMTD is unstable and detonates upon shock, friction, static electricity discharges, concentrated sulfuric acid, strong UV radiation and heat. Cases of detonation caused by the simple act of screwing a lid on a jar containing HMTD have been reported. Common static electricity discharges have been reported to cause detonation. It is, however, less unstable than many other peroxides under normal conditions; exposure to ultraviolet light increases its sensitivity. It also reacts with most common metals, which can lead to detonation. HMTD is chemically very stable when pure (free of acids, bases, and metal ions) and does not quickly sublime like its acetone counterparts. HMTD is a more powerful initiating explosive than mercury fulminate, but its poor thermal and chemical stability prevents its use in detonators. Nevertheless, HMTD is one of the three most widely used primary explosives in improvised, amateur made blasting caps. The other being TATP and silver acetylide. HMTD is a common source of injury among amateur chemists, particularly finger amputations. Most of these injuries are caused by small amounts of HMTD that inadvertently detonate in close proximity of fingers, since