Hexogen
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| Surname | Hexogen | |||||||||||||||
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| Molecular formula | C 3 H 6 N 6 O 6 | |||||||||||||||
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| properties | ||||||||||||||||
| Molar mass | 222.12 g mol −1 | |||||||||||||||
| Physical state |
firmly |
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| density |
1.82 g cm −3 (20 ° C) |
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| Melting point |
204–206 ° C (decomposition) |
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| solubility |
bad in water |
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| MAK |
Switzerland: 1.5 mg m −3 (measured as inhalable dust ) |
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| As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . | ||||||||||||||||
Hexogen , also known as cyclotrimethylene trinitramine , cyclonite , T4 and RDX (Research Department Explosive / Royal Demolition Explosive), is a highly explosive , toxic explosive from the nitramine group that was produced in large quantities during the Second World War and is still used. The systematic name of Hexogen is 1,3,5-trinitro-1,3,5-triazinan.
history
Hexogen was first manufactured in 1898 by the Berlin chemist and pharmaceutical entrepreneur Georg Friedrich Henning as an explosive for technical utilization and as a starting material for pharmaceutical preparations and described in the German Imperial Patent under the number 104280 of July 15, 1898. In 1920 the military research office in Berlin researched the substance more closely and called it hexogen.
The manufacturing processes were initially uneconomical. It was not until the 1930s that four new processes were developed in Germany and Hexogen was used under various code names such as K, SH, E or W salt in World War II. Analogous procedures have also been developed on the Allied side, e.g. B. the Bachmann process in the USA . Hexogen was also a component of one of the first plastic explosives that was used by Germany under this name during World War II and consisted of 88% hexogen and 12% petrolatum .
Different combinations are used today, e.g. B. Torpex, consisting of 40% hexogen, 42% TNT and 18% aluminum .
Hexogen is chemically and thermally very stable and is still one of the most explosive explosives with high work performance. The substance is the most important highly explosive military explosive in practical use.
Extraction and presentation
In the SH process, hexogen is obtained by nitrolysis from hexamethylenetetramine ( urotropine , hexamine) and highly concentrated nitric acid (98–99%). Due to the high risk of explosion, the production is bound to compliance with precise synthesis instructions. Technical processes operate modified using additives that bind water ( acetic anhydride in the Ka- or Bachmann method), and additionally ammonium ions provide ( ammonium nitrate in the K-method). Hexamethylenetetramine (urotropine) is a condensation product of ammonia and formaldehyde , which is formed when the aqueous, slightly alkaline solutions are evaporated together. As a by-product of this synthesis, a few percent of octogen is always formed, which can be preferentially formed by adding boron trifluoride . In the E process, paraformaldehyde and ammonium nitrate are converted into acetic anhydride.
The production and handling of Hexogen has already led to environmental and drinking water poisoning in the past.
properties
The hexogen molecule has a ring-shaped structure with three nitrogen atoms ( triazinane ring ), it is a saturated heterocycle .
The nitro groups (-NO 2 ) present in hexogen occur in many explosives, for example also in TNT or - as a nitric acid ester group ( -O-NO 2 ) - in gun cotton . Since the nitro group is bound to an amine nitrogen (this contains a free electron pair), the structure is stabilized (capto-dative structural element). In the case of nitrates, on the other hand, the nitro group is bound to an oxygen atom which, although it has two free electron pairs, is significantly more electronegative than nitrogen. Accordingly, the temperature stability of nitramines is significantly greater than that of comparable nitrates.
Physical Properties
Hexogen is a colorless, crystalline solid that melts at 204 ° C with a heat of fusion of 37.66 kJmol −1 . With a positive enthalpy of formation of 299.7 kJ kg −1 or 66.5 kJ mol −1 , it is an endothermic compound. The crystal structure of hexogen is orthorhombic, space group Pbca; a = 13.22 Å ; b = 11.61 Å; c = 10.75 Å; Z = 8.
The Mohs von Hexogen hardness is 2.5.
Explosion parameters
Due to its high density and high detonation speed, Hexogen shows a high balance performance and is one of the powerful, highly explosive and also relatively insensitive and chemically very stable explosives. Important explosion indicators are:
- Heat of explosion : 5625 kJ kg −1 (H 2 O (l)) , 5277 kJ kg −1 (H 2 O (g)) .
- Detonation velocity : 8750 m · s −1 at the maximum density
- Normal gas volume : 927 l kg −1 .
- Specific energy : 1370 kJ kg −1
- Deflagration point : 230 ° C
- Lead block expansion : 480 cm 3 / 10g
- Impact sensitivity : 7.4 Nm
- Friction sensitivity : 120 N pin load
- Steel sleeve test : limit diameter 8 mm
use
Hexogen is considered to be a particularly strong and highly explosive explosive and is a component of many common types of explosives, for example C4 and Torpex.
Hexogen is highly explosive in its pure state. So that it can be used militarily as an explosive, it is mixed with plasticizers such as polyethylene , wax , modeling clay , Vaseline , polyisobutylene or similar to form the plastic explosives A2, A3, B2, B3, B4, C2, C3 and the most widely used C4 . In addition, the explosives Hexogen and PETN together with a plasticizer form the well-known plastic explosive Semtex . Like almost all explosives used in the military, all these plastic explosives are no longer sensitive to impact, flame and friction. In order to detonate these plastic explosives, an initial ignition with a detonator must take place. With certain other chemical compounds, however, hexogen can also explode directly (see safety instructions ).
Hexogen is found in cutting charges such as linear cutters. Here, the partial focusing of the explosion energy enables steel up to 75 mm thick to be cut.
In the past, hexogen was kneaded into bread dough and used as a rodenticide . This use is no longer common today due to the stricter explosives laws.
safety instructions
Hexogen is a highly explosive substance. Above its melting point of 200 ° C it decomposes with the formation of nitrogen oxides .
Hazard assessment
In 2019, Hexogen was included in the EU's ongoing action plan ( CoRAP ) in accordance with Regulation (EC) No. 1907/2006 (REACH) as part of substance evaluation . The effects of the substance on human health and the environment are re-evaluated and, if necessary, follow-up measures are initiated. The causes for the uptake of Hexogen were concerns about environmental exposure, exposure of workers and widespread use as well as the possible dangers of carcinogenic and reproductive properties. The re-evaluation should be carried out by Hungary from 2020 .
literature
- J. Gartz: From Greek Fire to Dynamite: A Cultural History of Explosives. ESMittler & Sohn, Hamburg 2007, ISBN 978-3-8132-0867-2 .
Web links
- Toxicological assessment of groundwater contaminated with typical explosive compounds (STV) Research report 1998 of the Saxon State Office for Environment and Geology, tabular data (PDF file; 313 kB)
Individual evidence
- ↑ a b Entry on perhydro-1,3,5-trinitro-1,3,5-triazine in the GESTIS substance database of the IFA , accessed on February 28, 2017(JavaScript required) .
- ↑ Entry on Hexogen. In: Römpp Online . Georg Thieme Verlag, accessed on May 30, 2014.
- ↑ There is not yet a harmonized classification for this substance . A labeling of perhydro-1,3,5-trinitro-1,3,5-triazine in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 27, 2018, is reproduced from a self-classification by the distributor .
- ↑ Swiss Accident Insurance Fund (Suva): Limit values - current MAK and BAT values (search for 121-82-4 or Hexogen ), accessed on November 2, 2015.
- ↑ a b c d e f g h i j k l J. Köhler, R. Meyer, A. Homburg: Explosivstoffe. 10th, completely revised edition. Wiley-VCH, Weinheim 2008, ISBN 978-3-527-32009-7 .
- ↑ ES Domalski, ED Hearing: Heat Capacities and Entropies of Organic Compounds in the Condensed phase. Volume III. in: J. Phys. Chem. Ref. Data 25, 1996, pp. 1-525; doi: 10.1063 / 1.555985 .
- ↑ M. Delepine, M. Badoche: Thermochimie de l'aldehyde formique, de l'hexamethylene-tetramine et de ses derive. In: CR Acad. Sci. Paris. 214, 1942, pp. 777-780.
- ↑ Detonation of the opencast mine "747". September 17, 2018, accessed July 31, 2020 .
- ↑ Community rolling action plan ( CoRAP ) of the European Chemicals Agency (ECHA): Perhydro-1,3,5-trinitro-1,3,5-triazine , accessed on March 26, 2019.