Hexamethylene triperoxide diamine (HMTD) is a

high explosive An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An ...

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. Th ...

. HMTD is an

organic peroxide In organic chemistry, organic peroxides are organic compounds containing the peroxide functional group (). If the R′ is hydrogen, the compounds are called hydroperoxides, which are discussed in that article. The O−O bond of peroxides easily b ...

, a

heterocyclic compound A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring(s). Heterocyclic chemistry is the branch of organic chemistry dealing with the synthesis, properties, an ...

with a cage-like structure. It is a

primary explosive An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An ...

. It has been considered as an initiating explosive for

blasting caps A detonator, frequently a blasting cap, is a device used to trigger an explosive device. Detonators can be chemically, mechanically, or electrically initiated, the last two being the most common. The commercial use of explosives uses electri ...

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 However, it has since been superseded by more (chemically) stable compounds such as dextrinated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 Lead(II) azide is an inorganic compound. More so than other azides, is explosive. It is used in detonators to initiate secondary explosives. In a commercially usable form, it is a white to buff powder. Preparation and handling Lead(II) azide i ...

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 Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3 ...

and

hexamine Hexamethylenetetramine, also known as methenamine, hexamine, or urotropin, is a heterocyclic organic compound with the formula (CH2)6N4. This white crystalline compound is highly soluble in water and polar organic solvents. It has a cage-like s ...

in the presence of an acid

catalyst Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

, such as

citric acid Citric acid is an organic compound with the chemical formula HOC(CO2H)(CH2CO2H)2. It is a colorless weak organic acid. It occurs naturally in citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, which occurs in ...

, acetic acid or dilute

sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular fo ...

. 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 In chemistry, trigonal planar is a molecular geometry model with one atom at the center and three atoms at the corners of an equilateral triangle, called peripheral atoms, all in one plane. In an ideal trigonal planar species, all three ligands ...

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 Detonation () is a type of combustion involving a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations propagate supersonically through shock waves with s ...

. 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

detonator A detonator, frequently a blasting cap, is a device used to trigger an explosive device. Detonators can be chemically, mechanically, or electrically initiated, the last two being the most common. The commercial use of explosives uses electr ...

s. 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 small amounts (grams) are generally not powerful enough to amputate fingers from distances larger than 5 – 10 cm. Experienced amateurs handle HMTD in such a manner as to avoid any close contact between fingers and the explosive itself, from synthesis to final detonation. Such measures, for example, include using multiple filter papers during the filtration step that are exchanged as not to have more than 0.2 g of HMTD on a single filter paper, pre-bent papers with cotton wrapped wooden rods for manipulation and blast mitigation devices for final filling. Calculated (Explo5) detonation pressure P_cj at crystal density 1.597 g/cm³ is 218 kbar with velocity of detonation VoD = 7777 m/s. Explosion temperature is 3141 K, energy of explosion is 5612 kJ/kg (or 3400 - 4000 kJ/kg per various sources) and volume of explosion gases at STP is calculated to be 826 L/kg. Loose powder has density close to 0.4 g/cm³, hence the common detonation velocities are closer to 3000 m/s and P_cj is closer to 15 kbar.

Sensitivity

HMTD is overall slightly more sensitive than fresh TATP and can be considered to be slightly more dangerous than an average primary explosive. The variance of friction force between different surfaces (e.g. different kinds of paper) is often greater than the variance between the friction sensitivity of a given pair of primary explosives. This leads to different values for friction sensitivity measured at different laboratories.

Terrorism

Despite no longer being used in any military application, and despite its shock sensitivity, HMTD remains a common home-made explosive and has been used in a large number of

suicide bombing A suicide attack is any violent attack, usually entailing the attacker detonating an explosive, where the attacker has accepted their own death as a direct result of the attacking method used. Suicide attacks have occurred throughout histor ...

s and other attacks throughout the world. For example, it was one of the components in the explosives intended to bomb Los Angeles International Airport in the 2000 millennium attack plots and the

2016 New York and New Jersey bombings On September 17–19, 2016, three bombs exploded and several unexploded ones were found in the New York metropolitan area. The bombings left 31 people wounded, but no fatalities or life-threatening injuries were reported. On the morning of Sept ...

, as well as one of the components of the explosives attempted to be made by the

neo-Nazi Neo-Nazism comprises the post–World War II militant, social, and political movements that seek to revive and reinstate Nazi ideology. Neo-Nazis employ their ideology to promote hatred and racial supremacy (often white supremacy), attack ...

terrorist organization

Atomwaffen Division The Atomwaffen Division (''Atomwaffen'' meaning " nuclear weapons" in German), also known as the National Socialist Resistance Front, is an international far right-wing extremist and neo-Nazi terrorist network. Formed in 2013 and based in t ...

in the United States.

References

{{DEFAULTSORT:Hexamethylene Triperoxide Diamine Organic peroxides Explosive chemicals Diamines Organic peroxide explosives