Energetic Salts of 5‐(5‐Azido‐1H‐1,2,4‐triazol‐3‐yl)tetrazole

Several metal and nitrogen‐rich salts of the recently presented 5‐(5‐azido‐1H‐1,2,4‐triazol‐3‐yl)tetrazole (AzTT), including silver ( 1 ), copper(I) ( 2 ), potassium ( 3 ), cesium ( 4 ), copper(II) ( 7 ), ammonium ( 8 ), and guanidinium ( 9 ), as well as the respective double‐salts of 3 , 4 , 8 and 9 , were prepared and well characterized by IR and multinuclear (¹H, ¹³C, ¹⁴N) NMR spectroscopy, DSC, mass spectrometry, elemental analysis and one ( 4 ) additionally by single‐crystal X‐ray diffraction. The sensitivities towards impact, friction and electrostatic discharge were determined according to BAM standards, revealing most of the metal salts as highly sensitive and the nitrogen‐rich salts as insensitive. The metal salts were further tested for their ability of being primary explosives.     

Synthesis of 5‐(1H‐Tetrazolyl)‐1‐hydroxy‐tetrazole and Energetically Relevant Nitrogen‐Rich Ionic Derivatives

Sodium 5‐cyanotetrazolate sesquihydrate ( 1 ) was prepared from sodium azide and two equivalents of sodium cyanide under acidic conditions. Sodium 5‐cyanotetrazolate sesquihydrate ( 1 ) reacts with hydroxylammonium chloride to form 5‐aminohydroximoyl tetrazole ( 2 ). 5‐Aminohydroximoyl tetrazole ( 2 ) is treated with sodium nitrite and hydrochloric acid to form 5‐chlorohydroximoyl‐tetrazole ( 3 ). The chloride azide exchange yields 5‐azidohydroximoyl‐tetrazole monohydrate ( 4 ). When compound 4 is treated with hydrochloric acid, 5‐(1H‐tetrazolyl)‐1‐hydroxytetrazole ( 5 ) is obtained in good yield. Compound 5 can be deprotonated twice by various bases. Different ionic derivatives such as bis(hydroxylammonium) ( 6 ), bis(hydrazinium) ( 7 ), bis(guanidinium) ( 8 ), bis(aminoguanidinium) ( 9 ), bis(ammonium) ( 10 ), and diaminouronium ( 11 ) 5‐(1‐oxidotetrazolyl)‐tetrazolate were synthesized and characterized. With respect to energetic use salts 6 and 7 are most relevant. Compounds 3 – 9 and 11 were characterized using low temperature single‐crystal X‐ray diffraction. All compounds were investigated by NMR and vibrational (IR, Raman) spectroscopy, mass spectrometry and elemental analysis. The thermal properties were determined by differential scanning calorimetry (DSC). The sensitivities towards impact ( 4 : 4 J, 5 : 40 J, 6 : 12 J, 7 : 40 J), friction: ( 4 : 60 N, 5 : 240 N, 6 : 216 N, 7 : 240 N), and electrical discharge ( 5 : 0.40 J, 6 : 0.75 J, 7 : 0.75 J), were investigated using BAM standards and a small scale electrostatic discharge tester. The detonation parameters of 5 – 7 were calculated using the EXPLO5.06 code and calculated (CBS‐4 M) enthalpy of formation values.     

Studies on Energetic Salts Based on (2,4,6‐Trinitrophenyl)guanidine

(2,4,6‐Trinitrophenyl)guanidine was synthesized and its thermal and energetic properties were investigated. The reaction of (2,4,6‐trinitrophenyl)guanidine with different acids, such as nitric, picric, perchloric, and hydrochloric acid results in protonation of (2,4,6‐trinitrophenyl)guanidine and the formation of the corresponding salts (cation : anion ratio 1 : 1). The reactions are performed at ambient temperature in H₂O or EtOH and produce qualitatively pure products with energetic properties, which are typical of those of secondary explosives. The compounds were characterized using multinuclear NMR spectroscopy, IR and Raman spectroscopy, as well as mass spectrometry. Single crystal X‐ray diffraction studies were performed and the structures of the four different salts at low temperatures were determined. The thermal stabilities were measured using differential scanning calorimetry (DSC). The sensitivities were determined using the BAM drophammer and friction tests. The heats of formation were calculated by the atomization method based on CBS‐4M enthalpies. Using these values as well as the X‐ray or pycnometric densities, several detonation parameters such as the detonation pressure, velocity, energy, and temperature were computed using the EXPLO5 code.     

Explosives Based on Diaminourea

Diaminourea (DAU, 1 ) is synthesized by the reaction of dimethylcarbonate with hydrazine hydrate. DAU was protonated using nitric as well as perchloric acid yielding diaminouronium nitrate ( 2 ), diaminouronium dinitrate monohydrate ( 3 ) and diaminouronium perchlorate ( 4 ). The bis‐perchlorate salt could not be isolated due to its high hygroscopicity. Explosives 2 – 4 were fully characterized using X‐ray diffraction, NMR and vibrational spectroscopy, mass spectrometry and elemental analysis. The thermal properties were determined by differential scanning calorimetry (DSC). The sensitivities towards impact ( 2 : 9 J, 3 : >40 J, 4 : 2 J), friction ( 2 : 288 N, 3 : >360 N, 4 : 5 N) and electrical discharge ( 2 : 0.60 J, 3 : 0.50 J, 4 : 0.30 J) were investigated using Bundesanstalt für Materialforschung (BAM) methods and a small scale electrostatic discharge device. The detonation parameters of 2 and 3 were computed using the EXPLO5.04 code with the X‐ray densities as well as calculated (CBS‐4 M) energies of formation as input values.     

Synthesis and Characterization of a New Class of Energetic Compounds – Ammonium Nitriminotetrazolates

1‐Methyl‐5‐nitriminotetrazole ( 1 ) and 2‐methyl‐5‐nitraminotetrazole ( 2 ) obtained by nitration of 1‐methyl‐5‐aminotetrazole ( 3 ) and 2‐methyl‐5‐aminotetrazole ( 4 ) were deprotonated using aqueous ammonia solution yielding the energetic compounds, ammonium 1‐methyl‐5‐nitriminotetrazolate ( 5 ) and ammonium 2‐methyl‐5‐nitriminotetrazolate ( 6 ). The nitrogen‐rich salts were tested and characterized comprehensively using vibrational spectroscopy (Infrared (IR) and Raman), multinuclear (¹H, ¹³C, ¹⁴N, and ¹⁵N) NMR spectroscopy, and elemental analysis. The molecular structures in the crystalline state were determined using low temperature single crystal X‐ray diffraction. The thermal behavior and the decompositions were investigated using differential scanning calorimetry (DSC) and gas IR spectroscopy. The heats of formation were calculated using bomb calorimetric measurements. In addition, the relevant detonation parameters, like the detonation pressure and velocity of detonation were calculated using the software EXPLO5 outperforming the values of TNT. Last but not least the sensitivities were determined using BAM methods showing moderate values against impact and friction (drophammer and friction tester) and the long‐term stabilities were tested using Flexy Thermal safety calorimetry (TSC). X‐ray crystallography: 5 : monoclinic, P2₁/c, a=370.06(2) pm, b=2079.06(9) pm, c=859.69(5) pm, β=99.120(5)°, V=65306(6) pm³, Z=4, ρ_calc=1.639 g cm⁻³; 6 : monoclinic, P2₁, a=365.39(2) pm, b= 788.82(5) pm, c=1124.95(7) pm, β=91.818(6), V=32408(3) pm³, Z=2, ρ_calc=1.651 g cm⁻³.     

Energetic Derivatives of 2‐Nitrimino‐5,6‐dinitro‐benzimidazole

2‐Nitrimino‐5,6‐dinitrobenzimidazole ( 1 ) was synthesized by nitration of 2‐aminobenzimidazole at ambient temperature in good yield. In order to explore new insensitive explosives four energetic nitrogen‐rich 1 : 1 salts such as the guanidinium ( 1a ), aminoguanidinium ( 1b ), triaminoguanidinium ( 1c ) and hydroxylammonium ( 1d ) were synthesized either by facile acid/base or in situ metathesis reaction. In addition 2‐nitrobenzimidazole ( 2 ) was synthesized by the reaction of 2‐aminobenzimidazole using potassium hyperoxide in THF. Different nitration methods were tested to obtain a theoretically 2,4,5,6,7‐pentanitrobenzimidazole but only the already known 4,5,6,7‐tetranitrobenzimidazol‐2‐one ( 3 ) could be isolated. All synthesized compounds were characterized especially by low temperature X‐ray diffraction, CHN elemental analysis and ¹H and ¹³C NMR spectroscopy. The heat of formation of all new synthesized compounds was calculated using CBS‐4M electronic enthalpies in combination with the atomization method to calculate their detonation parameters with the EXPLO 5 V5.05 computer code.     

Barium Salts of Tetrazole Derivatives – Synthesis and Characterization

The compounds barium tetrazolate ( 6 ), barium 5‐aminotetrazolate tetrahydrate ( 7 ), barium 5‐nitriminotetrazolate dihydrate ( 8 ), barium bis(1H‐5‐nitriminotetrazolate) tetrahydrate ( 9 ), barium 1‐methyl‐5‐nitriminotetrazolate monohydrate ( 10 ), and barium 2‐methyl‐5‐nitriminotetrazolate dihydrate ( 11 ) were synthesized by the reactions of barium hydroxide octahydrate and 1H‐tetrazole ( 1 ), 5‐aminotetrazole ( 2 ), 1,4H‐5‐nitriminotetrazole ( 3 ), 1‐methyl‐5‐nitriminotetrazole ( 4 ), and 2‐methyl‐5‐nitraminotetrazole ( 5 ), respectively. The compounds were characterized using multi‐nuclear NMR spectroscopy, vibrational (IR and Raman) spectroscopy, elemental analysis, and differential scanning calorimetry. The solid‐state structures of 7 – 11 were determined using low temperature X‐ray diffraction and a comprehensive characterization is given. In addition, the sensitivities (impact, friction, electrical discharge) of 6 – 11 were investigated and bomb calorimetric measurements were carried out.     

A Selection of Alkali and Alkaline Earth Metal Salts of 5,5′‐Bis(1‐hydroxytetrazole) in Pyrotechnic Compositions

The dilithium ( 1 ), disodium ( 2 ), dipotassium ( 3 ) and dicesium ( 4 ) salt as well as the calcium ( 5 ), strontium ( 6 ) and barium ( 7 ) salt of 5,5′‐bis(1‐hydroxytetrazole) were prepared and characterized including NMR‐, IR‐ and Raman spectroscopy, mass spectrometry, elemental analysis and differential scanning calorimetry. The crystal structures of 1 , 2 and 4 – 6 were additionally determined by single‐crystal X‐ray diffraction. The sensitivities of the salts towards impact, friction and electrostatic discharge were determined by means of BAM (Bundesanstalt für Materialforschung‐ und prüfung) methods. The potential use of 1 , 6 and 7 as coloring agents in pyrotechnical mixtures as well as the utilization of 3 and 4 as additives in near infrared (NIR) emitting pyrotechnical formulations was examined.     

Structural and Theoretical Investigations of 3,4,5‐Triamino‐1,2,4‐Triazolium Salts

Reactions using the high nitrogen heterocycle 3,4,5‐triamino‐1,2,4‐triazole (guanazine) with strong acids (HNO₃, HClO₄, and “HN(NO₂)₂”) resulted in a family of highly stable salts. All of the salts were characterized using spectroscopic as well as single crystal X‐ray diffraction studies. The X‐ray structures were compared to that obtained from theoretical calculations (MP2/6‐311+G(d, p) level). Initial safety testing (impact, friction) was carried out on all of the new materials.     

The Synthesis of Energetic Compound on 4,4′‐((2,4,6‐trinitro‐1,3‐phenylene)bis(oxy)) bis(1,3‐dinitrobenzene)(ZXC‐5): Thermally Stable Explosive with Outstanding Properties

The novel, thermally stable explosive 4,4′‐((2,4,6‐trinitro‐1,3‐phenylene)bis(oxy))bis(1,3‐dinitrobenzene) (Be referred to as ZXC‐ 5 in our laboratory) has been reported. ZXC‐5 can be synthesized by a simple synthetic method (The total synthesis of ZXC‐ 5 requires only two steps and the total yield of ZXC‐ 5 is more than 89 %) and shows the superior detonation performances (detonation pressure, detonation velocity, sensitivity toward mechanical stimuli, and temperature of decomposition). The structure of ZXC‐5 was characterized by multinuclear (¹H, ¹³C) NMR and mass spectrometry. The structure in the crystalline state was confirmed by low‐temperature single‐crystal X‐ray diffraction. From the calculated standard molar enthalpy of formation and the measured densities, the detonation properties were predicted by using the EXPLO5 V6.01 thermochemical computer code. The sensitivity of ZXC‐ 5 towards impact, electrostatic discharge, and friction were also measured.     

5-(3-氨基呋咱-4-基)-1-羟基四唑胍盐的合成及性能研究

以丙二腈为原料,高收率合成了5-(3-氨基呋咱-4-基)-1-羟基四唑(1)的胍盐(2)、二氨基胍(3)以及联胍盐(4).采用红外光谱、核磁共振、元素分析、热分析等对其结构进行了表征;培养了2和3的单晶,并采用X射线单晶衍射测试了其晶体结构;通过落锤法和摩擦感度仪测试了3种胍盐的撞击感度和摩擦感度;采用DSC研究了3种胍盐的热分解过程.结果表明,3种胍盐的撞击感度均大于24J,摩擦感度均大于360N,分解点介于266~277℃,显示出良好的热稳定性.     

Structural and Preliminary Explosive Property Characterizations of New 3,4,5‐Triamino‐1,2,4‐triazolium (Guanazinium) Salts

Two new highly stable energetic salts were synthesized in reasonable yield by using the high nitrogen‐content heterocycle 3,4,5‐triamino‐1,2,4‐triazole and resulting in its picrate and azotetrazolate salts. 3,4,5‐Triamino‐1,2,4‐triazolium picrate (1) and bis(3,4,5‐triamino‐1,2,4‐triazolium) 5,5′‐azotetrazolate (2) were characterized analytically and spectroscopically. X‐ray diffraction studies revealed that protonation takes place on the nitrogen N1 (crystallographically labelled as N2). The sensitivity of the compounds to shock and friction was also determined by standard BAM tests revealing a low sensitivity for both. B3LYP/6–31G(d, p) density functional (DFT) calculations were carried out to determine the enthalpy of combustion (Δ_cH (1) =−3737.8 kJ mol⁻¹, Δ_cH (2) =−4577.8 kJ mol⁻¹) and the standard enthalpy of formation (Δ_fH° (1) =−498.3 kJ mol⁻¹, (Δ_fH° (2) =+524.2 kJ mol⁻¹). The detonation pressures (P (1) =189×10⁸ Pa, P (2) =199×10⁸ Pa) and detonation velocities (D (1) =7015 m s⁻¹, D (2) =7683 m s⁻¹) were calculated using the program EXPLO5.     

4H,8H-双呋咱并[3,4-b:3′,4′-e]吡嗪(DFP)有机双胺盐的合成及性能研究

为改善4H,8H-双呋咱并[3,4-b:3′,4′-e]吡嗪(DFP)结构存在的酸性问题,以DFP和有机胺为原料,合成了DFP的氨基胍盐(DAGDFP)、氨基脲盐(DSDFP)、1,3-二氨基胍盐(DBAGDFP)、脒基脲盐(DGUDFP)、胍盐(DGDFP)、缩二胍盐(DBGDFP)、三氨基胍盐(DTAGDFP)等7种有机双胺盐化合物;通过核磁共振谱、红外光谱和元素分析对其结构进行了表征;采用DSC和TG法分析了目标化合物的热性能;采用BAM标准方法测试了机械感度;通过Kamlet-Jacobs方程和最小自由能法分别计算了DFP双胺盐的爆轰参数和单元推进剂的燃烧性能。结果表明,DFP双胺盐热稳定性良好,撞击感度均大于40J,摩擦感度均大于360N,为钝感含能离子盐;DSDFP热分解温度为273.4℃,理论爆速为7891m/s,爆压为27.07GPa,比冲为2352N·s/kg,特征速度为1462.9m/s,爆轰性能优于TNT,比冲和特征速度较偶氮四唑胍盐(GZT)大幅提高,有望应用于气体发生剂和固体推进剂等。     

Tetrazolyl Triazolotriazine: A New Insensitive High Explosive

A triazolotriazine carbonitrile ( 1 ) was formed by diazotization of 3‐amino‐5‐cyano‐1,2,4‐triazole followed by treatment with nitroacetonitrile. Cyclization of the C≡N bond with sodium azide results in a tetrazolyl triazolotriazine ( 2 ). Formation of the sodium salt of 2 , followed by metathesis with [PPN][Cl] resulted in the organic salt 3 . Compounds 1 , 2 , and 3 were characterized by elemental analysis and infrared, ¹H, and ¹³C{¹H} NMR spectroscopy and 1 and 3 were characterized by single‐crystal X‐ray diffraction. Compound 2 has a density of 1.819 g cm⁻¹, is thermally stable up to 305 °C, and is insensitive to impact, friction, and electrical discharge. The detonation pressure and velocity of 2 are calculated to be 27.04 GPa and 8.312 km s⁻¹, respectively, making this a 1,3,5‐triamino‐2,4,6‐trinitrobenzene (TATB) replacement candidate.     

Synthesis and Characterization of a Thermally and Hydrolytically Stable Energetic Material based on N‐Nitrourea

The novel primary explosive tetranitrodiglycoluril (TNDGU) was synthesized from glycoluril dimer. It was fully characterized by using NMR (¹H, ¹³C), IR spectroscopy, and elemental analysis. X‐ray diffraction revealed that the crystals of TNDGU belong to triclinic system with space group P . The thermal behavior of TNDGU was studied using DSC methods. TNDGU exhibited good thermal stability with a decomposition temperature of 284.8 °C. TNDGU was also more resistant to hydrolysis compared to other nitrourea analogues. Additionally, density, enthalpy of formation, detonation velocity (VOD), and detonation pressure of TNDGU were predicted and it was found that TNDGU is a potential powerful explosive with a calculated density of 1.93 g cm⁻³, a detonation velocity of 8305 m s⁻¹ and low sensitivity to electric discharge.     

Combustion Characteristics of Silicon‐Based Nanoenergetic Formulations with Reduced Electrostatic Discharge Sensitivity

This paper details the synthesis and combustion characteristics of silicon‐based nanoenergetic formulations. Silicon nanostructured powder (with a wide variety of morphologies such as nanoparticles, nanowires, and nanotubes) were produced by DC plasma arc discharge route. These nanostructures were passivated with oxygen and hydrogen post‐synthesis. Their structural, morphological, and vibrational properties were investigated using X‐ray diffractometry, transmission electron microscopy (TEM), nitrogen adsorption‐desorption analysis, Fourier transform infrared (FTIR) spectrometry and Raman spectroscopy. The silicon nanostructured powder (fuel) was mixed with varying amounts of sodium perchlorate (NaClO₄) nanoparticles (oxidizer) to form nanoenergetic mixtures. The NaClO₄ nanoparticles with a size distribution in the range of 5–40 nm were prepared using surfactant in a mixed solvent system. The combustion characteristics, namely (i) the combustion wave speed and (ii) the pressure‐time characteristics, were measured. The observed correlation between the basic material properties and the measured combustion characteristics is presented. These silicon‐based nanoenergetic formulations exhibit reduced sensitivity to electrostatic discharge (ESD).     

Energetic,Low‐Melting Salts of Simple Heterocycles

The synthesis of three new families of heterocyclic‐based salts was undertaken and accomplished. Three triazole systems, 1H‐1,2,4‐triazole, 4‐amino‐1,2,4‐triazole, and 1H‐1,2,3‐triazole, were used as proton bases with nitric (HNO₃), perchloric (HClO₄), and dinitramidic (HN(NO₂)₂) acid systems. In all cases, stable salts were recovered and fully characterized by vibrational spectra (IR, Raman), multinuclear NMR spectroscopy, material balance, density measurements, and elemental analyses, as well as DSC, TGA and initial safety testing (impact). Many of these salts have melting points well below 100 °C, yet high decomposition onsets, defining them as new, highly energetic members of the well known class of materials identified as ionic liquids. Additionally, the single crystal X‐ray diffraction study of 1,2,4‐triazolium perchlorate was investigated, revealing the expected structure.     

Synthesis and Characterization of Energetic 1,2‐Bis(Oxyamino)Ethane Salts

The synthesis, characterization, theoretical calculations, and safety studies of energetic salts based on 1,2‐bis(oxyamino)ethane, (H₂N O CH₂ CH₂ O NH₂), were carried out. The salts were characterized by vibrational (infrared, Raman), multinuclear NMR studies (¹H, ¹³C), differential scanning calorimetry (DSC), elemental analysis, and initial safety testing (impact and friction sensitivity). Single crystal X‐ray diffraction studies were carried out on the mono‐perchlorate and the double nitrate salts, revealing the expected structures.     

The Formulation Design and Performance Test of Gas Generators Based on Guanidinium Azotetrazolate

Six types of gas generators based on guanidinium azotetrazolate (GZT) were designed into six formulations having different oxidants: GZT‐LiNO₃ (1), GZT‐NaNO₃ (2), GZT‐KNO₃ (3), GZT‐Mg(NO₃)₂ (4), GZT‐Sr(NO₃)₂ (5) and GZT‐KMnO₄ (6), respectively. The properties of these formulations were investigated in terms from gas production, appropriate combustion temperature and nontoxic gaseous emission. REAL software calculation program [1] was used to calculate the combustion heat at constant pressure, combustion heat at constant volume and specific volume in standard state. It showed that gas generators based on GZT with nitrate salts as oxidant exhibited better performance. Thus its thermal behavior and combustion temperature were studied further and the experimental results were consistent with the theoretical calculation results. Therefore, it can be concluded that formulation 3 has comprehensive optimal performance: low moisture content, insensitivity to friction, heightened vacuum stability, high combustion heat and specific volume. Namely, formulation 3 exhibited the most promising indications of commercial application, such as using in air bags of motor vehicles.     

Synthesis and Characterization of 1‐Nitroguanyl‐3‐nitro‐5‐amino‐1,2,4‐triazole

The synthesis of 1‐nitroguanyl‐3‐nitro‐5‐amino‐1,2,4‐triazole (ANTA‐NQ) ( 1 ) with good yield and high purity is described. DSC analysis showed that the material displays good thermal stability. An X‐ray crystallographic analysis confirms the structure of this material, as well as displays intramolecular hydrogen bonding. A gas pycnometry density for this material was measured to be 1.79 g cm⁻³. The heat of formation of this material was also measured. These data, along with the molecular formula were used as inputs to calculate the detonation velocity and detonation pressure using the Cheetah thermochemical code. The sensitivity of this material towards impact, spark and friction was also measured, as well as its vacuum thermal stability. The 3‐azido derivative 2 was also prepared and its properties are described as well. The above data show that (ANTA‐NQ) may be a high performing material with low sensitivity and good thermal stability.