Synthesis and Properties of Bis(nitrocarbamoylethyl) Nitramine - A New Energetic Open-Chain Nitrocarbamate

The nitrocarbamate derivative of the well-known and intensively investigated nitro ester DINA was prepared and studied. Starting with bis(hydroxyethyl) nitramine obtained from DINA, the corresponding carbamate was obtained by treatment with chlorosulfonyl isocyanate (CSI). Using fuming nitric acid only as nitration reagent, the target compound bis(nitrocarbamoylethyl) nitramine was synthesized. Furthermore, a route to the salt bis(nitrocarbamoylethyl)ammonium nitrate by a simple two step synthesis starting from diethanolamine was revealed. The compounds were fully characterized by NMR spectroscopy, X-ray diffraction, differential thermal analysis, vibrational analysis and elemental analysis. The sensitivities towards impact and friction of the energetic compounds were measured, as well as their energetic properties determined by using the energies of formation, calculated on the CBS4-M level of theory, with the EXPLO5 computer code

Kinetic Predictions Concerning the Long-Term Stability of TKX-50 and Other Common Explosives Using the NETZSCH Kinetics Neo Software

Explosives are used in both military and civilian applications all over the world. Sufficient longevity and good thermal stability are therefore essential for safe handling and safe storage of energetic materials. In this work, five well-known compounds, TKX-50, RDX, HMX, CL-20 and PETN, were investigated by means of different kinetic models, in order to make predictions about their long-term stability. For this purpose, the compounds were synthesized according to literature-known procedures and thermogravimetric (TG) measurements were performed. The TG plots were analyzed using the Ozawa-Flynn-Wall, Friedman and ASTM E698 kinetic models with the NETZSCH Kinetics Neo software and the activation energy and isothermal long-term stability were determined. Moreover, various climatic predictions of different countries were made

OZM Ball Drop Impact Tester (BIT‐132) vs. BAM Standard Method – a Comparative Investigation

Safety, performance, cost efficient synthesis and toxicity are the most important aspects of modern explosives. Sensitivity measurements are performed in accordance with different protocols all around the world. Sometimes the BAM drop hammer does not accurately reflect the sensitivity of an energetic material, in particular the sensitivity of primary explosives. Therefore, we present here preliminary results obtained using the novel ball drop tester (BIT‐132), manufactured by OZM research, following MIL‐STD‐1751 A (method 1016). The ball drop impact sensitivity tester is a device in which a free‐falling steel ball is dropped onto an unconfined sample, and is expected to produce more realistic results than the currently commonly used BAM method. The results obtained using the probit analysis were compared to those from the BAM drop hammer and friction tester. The following sensitive explosives were investigated: HMTD, TATP, TAT, Tetrazene, MTX‐1, KDNBF, KDNP, K2DNABT, Lead Styphnate Monohydrate, DBX‐1, Nickel(II) Hydrazine Nitrate, Silver Acetylide, AgN3, Pb(N3)2 RD‐1333, AgCNO, and Hg(CNO)2

The Lithium Salts of Bis(azolyl)borates as Strontium‐ and Chlorine‐free Red Pyrotechnic Colorants

After concerns regarding the use of chlorinated material for pyrotechnic items had reinforced, the action of the U.S. Environmental Protection Agency on health concerns about strontium ushered in a new era in the production of red light. Lithium was shown to impart red color to a pyrotechnic flame, however only a very narrow selection of such formulations can be found in the literature. Dihydrobis(azolyl)borates are a well investigated, easily accessible class of materials which have been proven to be suitable as pyrotechnic coloring agents. With their high nitrogen contents such moieties should also meet the requirements of a low combustion temperature and a reducing flame atmosphere for a lithium‐based red‐burning composition. This work evaluates the capability of the lithium salts of dihydrobis(pyrazol‐1‐yl)borate, dihydrobis(1,2,4‐triazol‐1‐yl)borate, and dihydrobis(tetrazol‐1‐yl)borate to serve as red color imparters. The latter compounds were characterized by multinuclear NMR experiments, IR spectroscopy, elemental analysis, and single‐crystal X‐ray diffraction and were investigated with respect to their thermal stabilities as well as sensitivities toward various ignition stimuli

Salts of Picramic Acid – Nearly Forgotten Temperature‐Resistant Energetic Materials

Thermally stable explosives are becoming more and more important nowadays due to their important role in the oil and mining industry. The requirements of these explosives are constantly changing. Picramate‐based compounds are poorly investigated towards their energetic properties as well as sensitivities. In this work, 13 different salts of picramic acid were synthesized as potential energetic materials with high thermal stability in a simple one‐step reaction and compared with commercially used lead picramate. The obtained compounds were extensively characterized by e. g. XRD, IR, EA, DTA, and TGA. In addition, the sensitivities towards impact and friction were determined with the BAM drop hammer and the BAM friction tester. Also, the electrostatic discharge sensitivity was explored. Calculations of the energetic performance of selected compounds were carried out with the current version of EXPLO5 code. Therefore, heats of formation were computed and X‐ray densities were converted to room temperature. Some of the synthesized salts show promising characteristics with high exothermic decomposition temperatures. Especially, the water‐free rubidium, cesium, and barium salts 5 , 6 and 10 with decomposition temperatures of almost 300 °C could be promising candidates for future applications

Initial Steps of Thermal Decomposition of Dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate Crystals from Quantum Mechanics

Dihydroxylammonium 5,5?-bistetrazole-1,1?-diolate (TKX-50) is a recently synthesized energetic material (EM) with most promising performance, including high energy content, high density, low sensitivity, and low toxicity. TKX-50 forms an ionic crystal in which the unit cell contains two bistetrazole dianions {c-((NO)N3C)-[c-(CN3(NO)], formal charge of ?2} and four hydroxylammonium (NH3OH)+ cations (formal charge of +1). We report here quantum mechanics (QM)-based reaction studies to determine the atomistic reaction mechanisms for the initial decompositions of this system. First we carried out molecular dynamics simulations on the periodic TKX-50 crystal using forces from density functional based tight binding calculations (DFTB-MD), which finds that the chemistry is initiated by proton transfer from the cation to the dianion. Continuous heating of this periodic system leads eventually to dissociation of the protonated or diprotonated bistetrazole to release N2 and N2O. To refine the mechanisms observed in the periodic DFTB-MD, we carried out finite cluster quantum mechanics studies (B3LYP) for the unimolecular decomposition of the bistetrazole. We find that for the bistetrazole dianion, the reaction barrier for release of N2 is 45.1 kcal/mol, while release of N2O is 72.2 kcal/mol. However, transferring one proton to the bistetrazole dianion decreases the reaction barriers to 37.2 kcal/mol for N2 release and 59.5 kcal/mol for N2O release. Thus, we predict that the initial decompositions in TKX-50 lead to N2 release, which in turn provides the energy to drive further decompositions. On the basis of this mechanism, we suggest changes to make the system less sensitive while retaining the large energy release. This may help improve the synthesis strategy of developing high nitrogen explosives with further improved performance