| Preferred IUPAC name |
3D model (JSmol)
|UN number||0072, 0391, 0483|
CompTox Dashboard (EPA)
|Molar mass||222.117 g·mol−1|
|Appearance||Colorless or yellowish crystals|
|Melting point||205.5 °C (401.9 °F; 478.6 K)|
|Boiling point||234 °C (453 °F; 507 K)|
|Detonation velocity||8750 m/s|
|Main hazards||Explosive, detonates on contact with mercury fulminate, highly toxic|
|GHS Signal word||Danger|
|H201, H301, H370, H373|
|P210, P250, P280, P370, P372, P373, P501|
|NFPA 704 (fire diamond)|
|Lethal dose or concentration (LD, LC):|
LD50 (median dose)
|NIOSH (US health exposure limits):|
|TWA 1.5 mg/m3 ST 3 mg/m3 [skin]|
IDLH (Immediate danger)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|(what is ?)|
RDX (abbreviation of "Research Department eXplosive" or "Royal Demolition eXplosive"),among other names (see the section Name), is an organic compound with the formula (O2N2CH2)3. It is a white solid without smell or taste, widely used as an explosive. Chemically, it is classified as a nitroamine alongside HMX, which is a more energetic explosive than TNT. It was used widely in World War II and remains common in military applications.
RDX is often used in mixtures with other explosives and plasticizers or phlegmatizers (desensitizers); it is the explosive agent in C-4 plastic explosive. It is stable in storage and is considered one of the most energetic and brisant of the military high explosives,with a relative effectiveness factor of 1.60.
RDX is also known, but less commonly, as cyclonite, hexogen (particularly in Russian, French, German and German-influenced languages), T4, and, chemically, as cyclotrimethylenetrinitramine.In the 1930s, the Royal Arsenal, Woolwich, started investigating cyclonite to use against German U-boats that were being built with thicker hulls. The goal was to develop an explosive more energetic than TNT. For security reasons, Britain termed cyclonite "Research Department Explosive" (R.D.X.). The term RDX appeared in the United States in 1946. The first public reference in the United Kingdom to the name RDX, or R.D.X., to use the official title, appeared in 1948; its authors were the managing chemist, ROF Bridgwater, the chemical research and development department, Woolwich, and the director of Royal Ordnance Factories, Explosives; again, it was referred to as simply RDX.
This section needs additional citations for verification .(January 2021)
RDX was widely used during World War II, often in explosive mixtures with TNT such as Torpex, Composition B, Cyclotols, and H6. RDX was used in one of the first plastic explosives. The bouncing bomb depth charges used in the "Dambusters Raid" each contained 6,600 pounds (3,000 kg) of Torpex; The Tallboy and Grand Slam bombs designed by Wallis also used Torpex.
RDX is believed to have been used in many bomb plots, including terrorist plots.
RDX is the base for a number of common military explosives:
Outside military applications, RDX is also used in controlled demolition to raze structures.The demolition of the Jamestown Bridge in the U.S. state of Rhode Island was one instance where RDX shaped charges were used to remove the span.
RDX is classified by chemists as a hexahydro-1,3,5-triazine derivative. It is obtained by treating hexamine with white fuming nitric acid.
This nitrolysis reaction also produces methylene dinitrate, ammonium nitrate, and water as byproducts. The overall reaction is:
Modern syntheses employ hexahydro triacyl triazine as it avoids formation of HMX.
RDX was used by both sides in World War II. The U.S. produced about 15,000 long tons (15,000 t) per month during WWII and Germany about 7,100 tonnes (7,000 long tons) per month. RDX had the major advantages of possessing greater explosive force than TNT, used in World War I, and requiring no additional raw materials for its manufacture.
RDX was reported in 1898 by Georg Friedrich Henning, who obtained a German patent (patent No. 104280) for its manufacture by nitrolysis of hexamine (hexamethylenetetramine) with concentrated nitric acid.In this patent, the medical properties of RDX were mentioned; however, three further German patents obtained by Henning in 1916 proposed its use in smokeless propellants. The German military started investigating its use in 1920, referring to it as hexogen. Research and development findings were not published further until Edmund von Herz, described as an Austrian and later a German citizen, obtained a British patent in 1921 and a United States patent in 1922. Both patent claims were initiated in Austria; and described the manufacture of RDX by nitrating hexamethylenetetramine. The British patent claims included the manufacture of RDX by nitration, its use with or without other explosives, its use as a bursting charge and as an initiator. The U.S. patent claim was for the use of a hollow explosive device containing RDX and a detonator cap containing RDX. In the 1930s, Germany developed improved production methods.
During World War II, Germany used the code names W Salt, SH Salt, K-method, the E-method, and the KA-method. These names represented the identities of the developers of the various chemical routes to RDX. The W-method was developed by Wolfram in 1934 and gave RDX the code name "W-Salz". It used sulfamic acid, formaldehyde, and nitric acid.SH-Salz (SH salt) was from Schnurr, who developed a batch-process in 1937–38 based on nitrolysis of hexamine. The K-method, from Knöffler, involved addition of ammonium nitrate to the hexamine/nitric acid process. The E-method, developed by Ebele, proved to be identical to the Ross and Schiessler process described below. The KA-method, also developed by Knöffler, turned out to be identical to the Bachmann process described below.
The explosive shells fired by the MK 108 cannon and the warhead of the R4M rocket, both used in Luftwaffe fighter aircraft as offensive armament, both used hexogen as their explosive base.
In the United Kingdom (UK), RDX was manufactured from 1933 by the research department in a pilot plant at the Royal Arsenal in Woolwich, London, a larger pilot plant being built at the RGPF Waltham Abbey just outside London in 1939. 700-acre (280 ha) site, ROF Bridgwater, away from London and production of RDX started at Bridgwater on one unit in August 1941. The ROF Bridgwater plant brought in ammonia and methanol as raw materials: the methanol was converted to formaldehyde and some of the ammonia converted to nitric acid, which was concentrated for RDX production. The rest of the ammonia was reacted with formaldehyde to produce hexamine. The hexamine plant was supplied by Imperial Chemical Industries. It incorporated some features based on data obtained from the United States (U.S.). RDX was produced by continually adding hexamine and concentrated nitric acid to a cooled mixture of hexamine and nitric acid in the nitrator. The RDX was purified and processed for its intended use; recovery and reuse of some methanol and nitric acid also was carried out. The hexamine-nitration and RDX purification plants were duplicated (i.e. twin-unit) to provide some insurance against loss of production due to fire, explosion, or air attack.In 1939 a twin-unit industrial-scale plant was designed to be installed at a new
The United Kingdom and British Empire were fighting without allies against Nazi Germany until the middle of 1941 and had to be self-sufficient. At that time (1941), the UK had the capacity to produce 70 long tons (71 t)(160,000 lb) of RDX per week; both Canada, an allied country and self-governing dominion within the British Empire, and the U.S. were looked upon to supply ammunition and explosives, including RDX. By 1942 the Royal Air Force's annual requirement was forecast to be 52,000 long tons (53,000 t) of RDX, much of which came from North America (Canada and the U.S.).
A different method of production to the Woolwich process was found and used in Canada, possibly at the McGill University department of chemistry. This was based on reacting paraformaldehyde and ammonium nitrate in acetic anhydride.A UK patent application was made by Robert Walter Schiessler (Pennsylvania State University) and James Hamilton Ross (McGill, Canada) in May 1942; the UK patent was issued in December 1947. Gilman states that the same method of production had been independently discovered by Ebele in Germany prior to Schiessler and Ross, but that this was not known by the Allies. Urbański provides details of five methods of production, and he refers to this method as the (German) E-method.
At the beginning of the 1940s, the major U.S. explosive manufacturers, E. I. du Pont de Nemours & Company and Hercules, had several decades of experience of manufacturing trinitrotoluene (TNT) and had no wish to experiment with new explosives. U.S. Army Ordnance held the same viewpoint and wanted to continue using TNT.RDX had been tested by Picatinny Arsenal in 1929, and it was regarded as too expensive and too sensitive. The Navy proposed to continue using ammonium picrate. In contrast, the National Defense Research Committee (NDRC), who had visited The Royal Arsenal, Woolwich, thought new explosives were necessary. James B. Conant, chairman of Division B, wished to involve academic research into this area. Conant therefore set up an experimental explosives research laboratory at the Bureau of Mines, Bruceton, Pennsylvania, using Office of Scientific Research and Development (OSRD) funding.
In 1941, the UK's Tizard Mission visited the U.S. Army and Navy departments and part of the information handed over included details of the "Woolwich" method of manufacture of RDX and its stabilisation by mixing it with beeswax. 220 short tons (200 t) (440,000 lb) of RDX per day. A decision was taken by William H. P. Blandy, chief of the Bureau of Ordnance, to adopt RDX for use in mines and torpedoes. Given the immediate need for RDX, the U.S. Army Ordnance, at Blandy's request, built a plant that copied the equipment and process used at Woolwich. The result was the Wabash River Ordnance Works run by E. I. du Pont de Nemours & Company. At that time, this works had the largest nitric acid plant in the world. The Woolwich process was expensive: it needed 11 pounds (5.0 kg) of strong nitric acid for every pound of RDX.The UK was asking that the U.S. and Canada, combined, supply
By early 1941, the NDRC was researching new processes.The Woolwich or direct nitration process has at least two serious disadvantages: (1) it used large amounts of nitric acid and (2) at least one-half of the formaldehyde is lost. One mole of hexamethylenetetramine could produce at most one mole of RDX. At least three laboratories with no previous explosive experience were instructed to develop better production methods for RDX; they were based at Cornell, Michigan, and Pennsylvania State universities. Werner Emmanuel Bachmann, from Michigan, successfully developed the "combination process" by combining the Canadian process with direct nitration. The combination process required large quantities of acetic anhydride instead of nitric acid in the old British "Woolwich process". Ideally, the combination process could produce two moles of RDX from each mole of hexamethylenetetramine.
The vast production of RDX could not continue to rely on the use of natural beeswax to desensitize the RDX. A substitute stabilizer based on petroleum was developed at the Bruceton Explosives Research Laboratory.
The NDRC instructed three companies to develop pilot plants. They were the Western Cartridge Company, E. I. du Pont de Nemours & Company, and Tennessee Eastman Company, part of Eastman Kodak. 25,000 short tons (23,000 t) (50 million pounds) of Composition B per month.At the Eastman Chemical Company (TEC), a leading manufacturer of acetic anhydride, Werner Emmanuel Bachmann developed a continuous-flow process for RDX. RDX was crucial to the war effort and the current batch-production process was too slow. In February 1942, TEC began producing small amounts of RDX at its Wexler Bend pilot plant, which led to the U.S. government authorizing TEC to design and build Holston Ordnance Works (H.O.W.) in June 1942. By April 1943, RDX was being manufactured there. At the end of 1944, the Holston plant and the Wabash River Ordnance Works, which used the Woolwich process, were producing
The U.S. Bachmann process for RDX was found to be richer in HMX than the United Kingdom's RDX.[ citation needed ] This later led to a RDX plant using the Bachmann process being set up at ROF Bridgwater in 1955 to produce both RDX and HMX.[ citation needed ]
The United Kingdom's intention in World War II was to use "desensitised" RDX. In the original Woolwich process, RDX was phlegmatized with beeswax, but later paraffin wax was used, based on the work carried out at Bruceton. In the event the UK was unable to obtain sufficient RDX to meet its needs, some of the shortfall was met by substituting amatol, a mixture of ammonium nitrate and TNT.
Karl Dönitz was reputed to have claimed that "an aircraft can no more kill a U-boat than a crow can kill a mole".Nonetheless, by May 1942 Wellington bombers began to deploy depth charges containing Torpex, a mixture of RDX, TNT, and aluminium, which had up to 50 percent more destructive power than TNT-filled depth charges. Considerable quantities of the RDX–TNT mixture were produced at the Holston Ordnance Works, with Tennessee Eastman developing an automated mixing and cooling process based around the use of stainless steel conveyor belts.
A Semtex bomb was used in the Pan Am Flight 103 (known also as the Lockerbie) bombing in 1988. 700 g (1.5 lb) of RDX explosives tucked under the dress of the assassin was used in the assassination of former Indian prime minister Rajiv Gandhi in 1991. The 1993 Bombay bombings used RDX placed into several vehicles as bombs. RDX was the main component used for the 2006 Mumbai train bombings and the Jaipur bombings in 2008. It also is believed to be the explosive used in the 2010 Moscow Metro bombings.A belt laden with
Traces of RDX were found on pieces of wreckage from 1999 Russian apartment bombingsand 2004 Russian aircraft bombings. Further reports on the bombs used in the 1999 apartment bombings indicated that while RDX was not a part of the main charge, each bomb contained plastic explosive used as a booster charge.
Ahmed Ressam, the al-Qaeda Millennium Bomber, used a small quantity of RDX as one of the components in the bomb that he prepared to detonate in Los Angeles International Airport on New Year's Eve 1999-2000; the bomb could have produced a blast forty times greater than that of a devastating car bomb.
In July 2012, the Kenyan government arrested two Iranian nationals and charged them with illegal possession of 15 kilograms (33 pounds) of RDX. According to the Kenyan Police, the Iranians planned to use the RDX for "attacks on Israeli, US, UK and Saudi Arabian targets".
RDX was used in the assassination of Lebanese Prime Minister Rafic Hariri on February 14, 2005.
In the 2019 Pulwama attack in India, 250 kg of high-grade RDX was used by Jaish-e-Mohammed. The attack resulted in the deaths of 44 Central Reserve Police Force (CRPF) personnel as well as the attacker.
RDX has a high nitrogen content and a high O:C ratio, both of which indicate its explosive potential for formation of N2 and CO2.[ citation needed ]
RDX undergoes a deflagration to detonation transition (DDT) in confinement and certain circumstances.
The velocity of detonation of RDX at a density of 1.76 g/cm3 is 8750 m/s.[ citation needed ]
It starts to decompose at approximately 170 °C and melts at 204 °C. At room temperature, it is very stable. It burns rather than explodes. It detonates only with a detonator, being unaffected even by small arms fire. This property makes it a useful military explosive. It is less sensitive than pentaerythritol tetranitrate (PETN). Under normal conditions, RDX has a Figure of Insensitivity of exactly 80 (RDX defines the reference point).[ citation needed ]
RDX sublimes in vacuum, which restricts or prevents its use in some applications.[ citation needed ]
RDX, when exploded in air, has about 1.5 times the explosive energy of TNT per unit weight and about 2.0 times per unit volume.
RDX is insoluble in water, with solubility 0.05975 g/L at temperature of 25 °C.
The substance's toxicity has been studied for many years.RDX has caused convulsions (seizures) in military field personnel ingesting it, and in munition workers inhaling its dust during manufacture. At least one fatality was attributed to RDX toxicity in a European munitions manufacturing plant.
During the Vietnam War, at least 40 American soldiers were hospitalized with composition C-4 (which is 91% RDX) intoxication from December 1968 to December 1969. C-4 was frequently used by soldiers as a fuel to heat food, and the food was generally mixed by the same knife that was used to cut C-4 into small pieces prior to burning. Soldiers were exposed to C-4 either due to inhaling the fumes, or due to ingestion, made possible by many small particles adhering to the knife having been deposited into the cooked food. The symptom complex involved nausea, vomiting, generalized seizures, and prolonged postictal confusion and amnesia; which indicated toxic encephalopathy.
Oral toxicity of RDX depends on its physical form; in rats, the LD50 was found to be 100 mg/kg for finely powdered RDX, and 300 mg/kg for coarse, granular RDX. A case has been reported of a human child hospitalized in status epilepticus following the ingestion of 84.82 mg/kg dose of RDX (or 1.23 g for the patient's body weight of 14.5 kg) in the "plastic explosive" form.
The substance has low to moderate toxicity with a possible human carcinogen classification.Further research is ongoing, however, and this classification may be revised by the United States Environmental Protection Agency (EPA). Remediating RDX-contaminated water supplies has proven to be successful. It is known to be a kidney toxin in humans and highly toxic to earthworms and plants, thus army testing ranges where RDX was used heavily may need to undergo environmental remediation. Concerns have been raised by research published in late 2017 indicating that the issue has not been addressed correctly by U.S. officials.
RDX has limited civilian use as a rat poison.
RDX is degraded by the organisms in sewage sludge as well as the fungus Phanaerocheate chrysosporium .Both wild and transgenic plants can phytoremediate explosives from soil and water.
FOX-7 is considered to be approximately a 1-to-1 replacement for RDX in almost all applications.
An explosive 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 explosive charge is a measured quantity of explosive material, which may either be composed solely of one ingredient or be a mixture containing at least two substances.
Nitroglycerin (NG), also known as nitroglycerine, trinitroglycerin (TNG), nitro, glyceryl trinitrate (GTN), or 1,2,3-trinitroxypropane, is a dense, colorless, oily, explosive liquid most commonly produced by nitrating glycerol with white fuming nitric acid under conditions appropriate to the formation of the nitric acid ester. Chemically, the substance is an organic nitrate compound rather than a nitro compound, but the traditional name is retained. Invented in 1847 by Ascanio Sobrero, nitroglycerin has been used ever since as an active ingredient in the manufacture of explosives, namely dynamite, and as such it is employed in the construction, demolition, and mining industries. Since the 1880s, it has been used by the military as an active ingredient and gelatinizer for nitrocellulose in some solid propellants such as cordite and ballistite. It is a major component in double-based smokeless propellants used by reloaders. Combined with nitrocellulose, hundreds of powder combinations are used by rifle, pistol, and shotgun reloaders.
Nitric acid (HNO3), also known as aqua fortis (Latin for "strong water") and spirit of niter, is a highly corrosive mineral acid.
Trinitrotoluene more commonly known as TNT, or more specifically 2,4,6-trinitrotoluene, is a chemical compound with the formula C6H2(NO2)3CH3. This yellow solid is occasionally used as a reagent in chemical synthesis, but it is best known as an explosive material with convenient handling properties. The explosive yield of TNT is considered to be the standard comparative convention of bombs and asteroid impacts. In chemistry, TNT is used to generate charge transfer salts.
Pentaerythritol tetranitrate (PETN), also known as PENT, PENTA, TEN, corpent, or penthrite, is an explosive material. It is the nitrate ester of pentaerythritol, and is structurally very similar to nitroglycerin. Penta refers to the five carbon atoms of the neopentane skeleton. PETN is a powerful explosive material with a relative effectiveness factor of 1.66. When mixed with a plasticizer, PETN forms a plastic explosive. Along with RDX it is the main ingredient of Semtex.
HMX, also called octogen, is a powerful and relatively insensitive nitroamine high explosive, chemically related to RDX. Like RDX, the compound's name is the subject of much speculation, having been variously listed as High Melting Explosive, Her Majesty's Explosive, High-velocity Military Explosive, or High-Molecular-weight RDX.
Ammonium nitrate is a chemical compound with the chemical formula NH4NO3. It is a white crystalline solid consisting of ions of ammonium and nitrate. It is highly soluble in water and hygroscopic as a solid, although it does not form hydrates. It is predominantly used in agriculture as a high-nitrogen fertilizer. Global production was estimated at 21.6 million tonnes in 2017.
C-4 or Composition C-4 is a common variety of the plastic explosive family known as Composition C, which uses RDX as its explosive agent. C-4 is composed of explosives, plastic binder, plasticizer to make it malleable, and usually a marker or odorizing taggant chemical. C-4 has a texture similar to modelling clay and can be molded into any desired shape. C-4 is metastable and can be exploded only by the shock wave from a detonator or blasting cap.
Oleum, or fuming sulfuric acid, is a term referring to solutions of various compositions of sulfur trioxide in sulfuric acid, or sometimes more specifically to disulfuric acid. Oleum is identified by the CAS number 8014-95-7.
Royal Ordnance Factory (ROF) Bridgwater was a factory between the villages of Puriton and Woolavington in the Sedgemoor district of Somerset, UK that produced high explosives for munitions. It was slightly above sea level, between the 5 and 10 metre contour lines on Ordnance Survey maps. BAE Systems closed it when decommissioning was completed in July 2008.
Amatol is a highly explosive material made from a mixture of TNT and ammonium nitrate. The British name originates from the words ammonium and toluene. Similar mixtures were known as Schneiderite in France. Amatol was used extensively during World War I and World War II, typically as an explosive in military weapons such as aircraft bombs, shells, depth charges, and naval mines. It was eventually replaced with alternative explosives such as Composition B, Torpex, and tritonal.
The Composition C family is a family of related US-specified plastic explosives consisting primarily of RDX. All can be moulded by hand for use in demolition work and packed by hand into shaped charge devices. Variants have different proportions and plasticisers and include composition C-2, composition C-3, and composition C-4.
Torpex is a secondary explosive, 50% more powerful than TNT by mass. Torpex comprises 42% RDX, 40% TNT and 18% powdered aluminium. It was used in the Second World War from late 1942, at which time some used the names Torpex and RDX interchangeably, much to the confusion of today's historical researchers. The name is short for torpedo explosive. Torpex proved to be particularly useful in underwater munitions because the aluminium component had the effect of making the explosive pulse last longer, which increased the destructive power. Besides torpedoes and depth charges, Torpex was only used in the Upkeep, Tallboy and Grand Slam bombs as well as the drones employed in Operation Aphrodite. Torpex has long been superseded by H6 and Polymer-bonded explosive (PBX) compositions. It is therefore regarded as obsolete and Torpex is unlikely to be encountered except in old munitions or unexploded ordnance, although a notable exception to this is the Sting Ray lightweight torpedo, which as of October 2020 remains in service with the Royal Navy and several foreign militaries. The German equivalent of Torpex was Trialen.
TATB, triaminotrinitrobenzene or 2,4,6-triamino-1,3,5-trinitrobenzene is an aromatic explosive, based on the basic six-carbon benzene ring structure with three nitro functional groups (NO2) and three amine (NH2) groups attached, alternating around the ring.
Ethylene glycol dinitrate, abbreviated EGDN and NGc, also known as nitroglycol, is a chemical compound a colorless, oily explosive liquid obtained by nitrating ethylene glycol. It is similar to nitroglycerin in both manufacture and properties, though it is more volatile and less viscous. Unlike nitroglycerine, the chemical has a perfect (0) oxygen balance, meaning that its ideal exothermic decomposition would completely convert it to low energy CO2, H2O, and N2, with no excess unreacted O2, H2, C, or other high-energy substances, without needing to react with anything else.
Minol is a military explosive developed by the British Admiralty early in the Second World War to augment supplies of trinitrotoluene (TNT) and RDX, which were then in short supply. The aluminium component in Minol significantly prolongs the explosive pulse, making it ideal for use in underwater naval weapons where munitions with a longer explosive pulse are more destructive than those with high brisance.
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.
Explosive materials are produced in numerous physical forms for their use in mining, engineering, or military applications. The different physical forms and fabrication methods are grouped together in several use forms of explosives.
A water-gel explosive is a fuel sensitized explosive mixture consisting of an aqueous ammonium nitrate solution that acts as the oxidizer. Water gels that are cap-insensitive are referred to under United States safety regulations as blasting agents. Water gel explosives have a jelly-like consistency and come in sausage-like packing stapled shut on both sides.
Nitrolysis is a chemical reaction involving cleavage ("lysis") of a chemical bond concomitant with installation of a nitro group (NO2). Typical reagents for effecting this conversion are nitric acid and acetyl nitrate. A commercially important nitrolysis reaction is the conversion of hexamine to nitramide. Nitrolysis of hexamine is also used to produce RDX, (O2NNCH2)3, a trinitramide widely used as an explosive.
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