PETN – Nitropenta: by Marcel Alcaraz Janßen, Mark-Oliver Baum, Simon Bechtel and Julian Baranyai

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PETN – Nitropenta: By Marcel Alcaraz Janßen, Mark-Oliver Baum, Simon Bechtel and Julian Baranyai.

1 PHYSICAL PROTPERTIES

 Molar mass: 316.15 g/mol  Appearance at room temperature: solid, transparent crystals  Density: α-PETN = 1.778 g/cm³ β-PETN = 1.716 g/cm³ [1]  Melting Point: 141-142.9°C [1]  Boiling Point: decomposes above 150°C [1]  Steam Pressure: 67 mbar (at 95.3°C)[2]  Solvation: insoluble in water, weak soluble in ethanol, benzene, well soluble in acetone and dimethylformamide[2]

2 STRUCTURE[1]

α-PETN or also called PETN-I is the thermodynamic stable formation and has got a tetragonal polymorph conformation. β-PETN (PETN-II) has got an orthorhombic polymorph conformation and transforms at 130°C into α-PETN. Because of its symmetric structure it is quite resistant to hydrolysis in water at room temperature. At 100°C it hydrolysis into pentaerythritol dinitrate. PETN forms eutectic mixtures with liq- uid or molten aromatic nitro compounds e.g. trinitrotoluene. Within these mixtures the symmetry and therefore the thermic stability is reduced.

3 CHEMICAL PROPERTIES

The hydrolysis of PETN can be accelerated with 0.1% nitric acid. As well as other nitrate esters, PETN [3] [5] degrades by losing NO2 autocatalyticly. It can also be degraded by iron metal to pentaerythritol. PETN shows in the environment a biodegradation. Bacteria use PETN to gain energy by denitrating into trinitrate and dinitrate. But because of the insolubility in water PETN is not available for organisms. It is also not very toxic (LD 50 rat oral: >6 g/kg). PETN poses a threat for aquatic organisms. [4]

4 SYNTHESIS:

In the first step the starting material pentaerythritol is produced by the reaction of formaldehyde and acetaldehyde. There are three aldol reactions which form three new carbon-carbon bonds. After these reactions a Canizzaro reaction leads to the intermediate pentaerythritol. Here is the aldehyde reduced to an alcohol and formaldehyde is oxidized to formic acid. Now pentaerythritol tetranitrate is formed by the reaction of pentaerythritol with concentrated nitric acid. This step is an esterification of an alcohol (pentaerythritol) and an acid (nitric acid), four hydroxyl groups are transformed into four nitrate ester groups. [6] O OH O O O 3 aldol - reactions - + 3 + + HO H H H H acetaldehyde formaldehyde OH OH 3-hydroxy-2,2-bis(hydroxymethyl)propanal -HCOO-

O2N NO2 O O - reactionCannizzaro OH OH - esterification O + 4 N OH -4 H O + 2 O O O O2N NO2 OH OH nitric acid pentaerythritol pentaerythritol tetranitrate

Fig. 1: Synthesis of PETN.

5 PETN AS AN EXPLOSIVE [7]

PETN is a strong but chemical insensible Explosive. Compared to TNT it has 70% more power considering the explosionheat or the leadblockexpansion.

Use: As Explosive:

The PETN is used as Explosive in combination with TNT or Hexogen for Grenades or for detonating cords to start bigger Explosion from the distance. But it´s also used in combination with plasticizers like wax for plastic explosives. The most popular explosive in this class is Semtex. Like every explosive according to the law it has to be marked with other chemical substances to make it possible to find it with dogs or detectors.

Physical data of the standard explosive TNT compared to PETN [2]: PETN TNT Ap. multiplier Explosionheat 6311KJ/kg 3725kJ/Kg 1.69 Detonationspeed 8400m/s 6900m/s 1.21 Specific Energy 1327 MPa l/Kg 821 MPa l/Kg 1.61 Deflagration Point 202-205°C 300°C - Lead block expansion 52,3cm³ 30cm³ 1.74 Strike sensibility 3J 15J 0.2 Grinding sensibility 60N 353N no Reaction 0.17

The Explosionheat gives you the amount of energy which is set free during the detonation. The detonationspeed gives you the speed in which time the shockwave of the gas reaches you. The deflagration Point is the Point where the substance start to burn it´s self without exploding. The leadblockexpansion shows the increase of the volume of a leadblock by detonating inside of it. The strike sensibility gives you the amount of energy per Strike which is necessary to start the explosive reaction with a metal pen. The grinding sensibility shows the amount of energy which is necessary by grinding to start an explosive reaction. 6 HISTORY OF PETN

The alcohol which is necesarry to create PETN was first invented 1891 from Berhard Tollens and Peter Wigand throught basic condensation. With this alcohol the Sprengstoff AG Köln invited 1894 the PETN explosive with the already shown reaction between salpetric Acid and the alcohol pentaerythrit. Since 1912 the substace was used to boost explosives and in the same year it was patented by Claessen for this work.

7 MEDICAL ASPECTS OF PETN

PETN, a nitro preparation, is applicated in case of Coronary artery disease to relieve the symptoms. CAD is caused by deposits accumulating in the inner walls of the arteries of the heart. [8] This leads to constriction of the heart arteries, so the heart muscles are undersupplied with blood, which causes an oxygen deficiency in the hart muscles. Heretofore there is no cure for this disease leading to deadly heart attacks. However there are several Medicaments to reduce the symptoms of CAD or to stop it from declining. One of these Symptoms is chest pain, the Angina Pectoris. It can be treated with Nitropreparations such as Nitroglycerine or PETN. They reduce the preload and the afterload of the heart muscles. In the course of this the preload is the force inducing the stretch of the muscle during relaxation while the afterload is the tension of the muscle necessary to start the expulsion of the blood into the body. [9] This reduction leads to a lower oxygen demand of the heart muscle and therefore counteracts the oxygen deficiency in the heart for a short time. Furthermore the organic Nitrocompounds are intracellularly converted into NO which has a vasodilating impact. NO induces the Guanylatcyclase which is responsible for producing cyclic Guanosinmonophos- phate (cGMP). cGMP relaxes the smooth muscles of the blood vessels. Therefore Organic nitrates not only reduce the oxygen demand of the heart muscles, they also increase the Oxygen supply by extending the vessels. [10] Nevertheless organic Nitrate compounds may be a treatment for the mentioned symptoms but they are not able to heal the actual disease cad. [11] A substantial disadvantage of nitropreparations is the tolerance of the human body evolving against the Nitropreparations. Nitroglycerine for example loses his effect after 2 days of application. [10] The tolerance is explained by the incurrence of oxygen radicals due to the exposition of nitrates such as nitroglycerin. These radicals inhibit the enzyme Aldehyddehydrogenase which is responsible for the bio- logical activation of nitrates. Put simply: the Nitrate preparations deactivate themselves if used for a longer period. [12] This is where PETN comes in play. The manufacturers of PETN preparations claim that PETN causes no or at least less tolerances than other Nitrates. Studies with dogs indeed showed, that PETN doesn’t cause any tolerance development. 300.000 Patients in Germany are treated with a PETN preparation, PENTA- LONG. However PENTALONG must not be prescribed by physicians anymore. This is due to the fact, that it hasn’t been officially sanctioned by the ‘ Bundesinstitut fürArzneimittel und Medizinprodukte’ due to the lack of an scientifically solid study of the efficiency of the medicament. [13][14] Therefore PENTALONG is until now a fictively approved medicament, which means the health insurance funds are not obliged to pay for a PETN therapy. The approval Process is still not finished yet. [15] Side effects of a Nitrate therapy are significant headaches, patients and physicians claim that PETN preparations induce less headaches than classic Nitro medicine. [16]

8 ATTACHMENT

Fig. 2: C13 NMR of PETN in acetone at 20 MHz and 31°C. [A]

Fig. 3: IR spetrum of PETN. [B]

Fig. 4: H NMR of PETN in acetonitrile at 400 MHz and 25°C. [C]

Fig. 5: MS spectrum of PETN. [C]

9 REFERENCES

[1]: Thieme Chemistry (Hrsg.): RÖMPP Online – Version 3.11. Georg Thieme Verlag KG, Stuttgart 2011.

[2]: J. Köhler, R. Meyer, A. Homburg: Explosivstoffe, zehnte, vollständig überarbeitete Auflage, Wiley-VCH, Weinheim 2008, ISBN 978-3-527-32009-7.

[3]: Thermal decomposition of PENT and HMX over a wide temperature range by V.N. German et al.

[4]: Wildlife Toxicity Assessment for pentaerythritol tetranitrate. U.S. Army Center for Health Promotion and Preventive Medicine. November 2001

[5]: Li Zhuang, Lai Gui and Robert W. Gillham (2008). "Degradation of Pentaerythritol Tetranitrate (PETN) by Granular Iron". Environ. Sci. Technol. 42: 4534.

[6]: J. Clayden, N. Greeves, S. Warren, Organic chemistry, second edition, New York, 2012; M. Wismer, Zur Darstellung von Pentaerythrit, Eidengenössische Technische Hochschule in Zürich, 1949; K. Lange et al, Bioorg. Med. Chem. Lett. 19, 2009, 3141-3144.

[7]: T.Urbanski : Chemistry and technology of Explosives 1961; Dr.R Haas, Dipl. Ing. J. Thieme: Synonyms of Explosives; J.Gartz: cultural history of Explosives; E.S. Mittler & son Hamburg Hommel: Handbook of dangerous goods.

[8]: https://www.unimedizin-mainz.de/htg/patienten/erkrankungen-des-herzens/koronare-herzkrank- heit.html, Stand: 04.02.2014.

[9]: http://flexikon.doccheck.com/de/Vorlast, http://flexikon.doccheck.com/de/Nachlast, Stand: 04.02.2014.

[10]: K.O. Haustein, Pentaerithrityltetranitrat, Pharmakologische Besonderheiten für Praxis und Klinik, Steinkopf Verlag Darmstadt.

[11]: http://www.versorgungsleitlinien.de/themen/khk/nvl_khk/nvl_khk_download/pdf/down- load_nvlkhk_gesamt.pdf, Stand: 04.02.2014.

[12]: www.cardio-symposium.de/index.php?menu=view&id=221, Stand: 04.02.2014.

[13]: http://www.kvwl.de/arzt/verordnung/arzneimittel/info/agavm/fiktiv_zugelassene_am_agamv.pdf, Status 28.12.13.

[14]: http://www.spiegel.de/gesundheit/diagnose/pentalong-streit-um-zulassung-fuer-50-jahre-altes- herzmittel-a-915457.html, Status: 28.12.13.

[15]: http://www.deutschesapothekenportal.de/fileadmin/bestellungen/dap_pentalong_patien- teninfo.pdf, Stand: 04.02.2014.

[16]: „Inzidenz von Kopfschmerzen als Nebenwirkung bei der Behandlung mit Nitraten: Ein doppelblinder Vergleich zwischen PETN, ISUN und Placebo“, V. Paffenrath, S. de la Motte, F. Harisson, C. Rüthening

[A]: ACD: Spectral data were obtained from Advanced Chemistry Development, Inc. [B]: BIORAD: Infrared spectral data from the Bio-Rad/Sadtler IR Data Collection was obtained from Bio- Rad Laboratories, Philadelphia, PA (US). Copyright © Bio-Rad Laboratories. All Rights Reserved.

[C]: WSS: Spectral data were obtained from Wiley Subscription Services, Inc. (US)