Carbonyl and Oxalyl Bridged Bis(1,5‐Diaminotetrazole)‐Based Energetic Salts

High density energetic salts containing nitrogen rich cations and carbonyl‐ or oxalylbis(diamino‐tetrazole) anions, which were obtained from cyanogen azide and hydrazine, were readily synthesized. In every case, a new family of energetic salts 3 – 14 were characterized by vibrational spectroscopy, multinuclear (¹H, ¹³C, ¹⁵N) NMR, elemental analyses, density, differential scanning calorimetry and impact sensitivity. Compound 12 was structured by single crystal X‐ray diffraction. The densities of 3 ‐ 14 , determined by gas pycnometer, range between 1.500 and 1.676 g cm^?3. The heats of formation and detonation properties for these stable salts were calculated by using Gaussian 03 and Cheetah 5.0, respectively.     

4‐Nitro‐3‐(5‐tetrazole)furoxan and Its Salts: Synthesis,Characterization, and Energetic Properties

A series of new energetic salts based on 4‐nitro‐3‐(5‐tetrazole)furoxan (HTNF) has been synthesized. All of the salts have been fully characterized by nuclear magnetic resonance (¹H and ¹³C), infrared (IR) spectroscopy, elemental analysis, and differential scanning calorimetry (DSC). The crystal structures of neutral HTNF ( 3 ) and its ammonium ( 4 ) and N‐carbamoylguanidinium salts ( 9 ) have been determined by single‐crystal X‐ray diffraction analysis. The densities of 3 and its nine salts were found to range from 1.63 to 1.84 g cm^?3. Impact sensitivities have been determined by hammer tests, and the results ranged from 2 J (very sensitive) to >40 J (insensitive). Theoretical performance calculations (Gaussian 03 and EXPLO 5.05) provided detonation pressures and velocities for the ionic compounds 4 – 12 in the ranges 25.5–36.2 GPa and 7934–8919 m s^?1, respectively, which make them competitive energetic materials.     

Nitrogen‐Rich Energetic Dianionic Salts of 3, 4‐Bis(1H‐5‐­tetrazolyl)furoxan with Excellent Thermal Stability

Nitrogen‐rich 3, 4‐bis(1H‐tetrazol‐5‐yl)furoxan (H₂BTF, 2 ) and its energetic salts with excellent thermal stability were successfully synthesized and fully characterized by ¹H, and ¹³C NMR, and IR spectroscopy, differential scanning calorimetry (DSC), and elemental analyses. Additionally, the structures of barium ( 3 ) and 1‐methyl‐3, 4, 5‐triamino‐triazolium ( 10 ) salts were confirmed by single‐crystal X‐ray diffraction. The densities of the energetic salts paired with organic cations range between 1.56 and 1.85 g · cm^–3 as measured by a gas pycnometer. Based on the measured densities and calculated heats of formation, the detonation pressures and velocities are calculated to be in the range 23.4–32.0 GPa and 7939–8915 m · s^–1, which make them competitive energetic materials.     

2‐(Dinitromethylene)‐1‐nitro‐1, 3‐diazacyclopentane‐Based Energetic Salts

Energetic salts that contain nitrogen‐rich cations and the 2‐(dinitromethyl)‐3‐nitro‐1, 3‐diazacyclopent‐1‐ene anion were synthesized in high yield by direct neutralization reactions. The resulting salts were fully characterized by multinuclear NMR spectroscopy (¹H and ¹³C), vibrational spectroscopy (IR), elemental analysis, density and differential scanning calorimetry (DSC), and elemental analysis. Additionally, the structures of the ammonium ( 1 ) and isopropylideneaminoguanidinium ( 9 ) 2‐(dinitromethyl)‐3‐nitro‐1, 3‐diazacyclopent‐l‐ene salts were confirmed by single‐crystal X‐ray diffraction. Solid‐state ¹⁵N NMR spectroscopy was used as an effective technique to further determine the structure of some of the products. The densities of the energetic salts paired with organic cations fell between 1.50 and 1.79 g · cm^–3 as measured by a gas pycnometer. Based on the measured densities and calculated heats of formation, detonation pressures and velocities were calculated using Explo 5.05 and found to to be 25.2–35.5 GPa and 7949–9004 m · s^–1, respectively, which make them competitive energetic materials.     

Energetic Salts Based on Monoanions of N,N‐Bis(1H‐tetrazol‐5‐yl)amine and 5,5′‐Bis(tetrazole)

High‐density energetic salts that contain nitrogen‐rich cations and the 5‐(tetrazol‐5‐ylamino)tetrazolate (HBTA^?) or the 5‐(tetrazol‐5‐yl)tetrazolate (HBT^?) anion were readily synthesized by the metathesis reactions of sulfate salts with barium compounds, such as bis[5‐(tetrazol‐5‐ylamino)tetrazolate] (Ba(HBTA)₂), barium iminobis(5‐tetrazolate) (BaBTA), or barium 5,5′‐bis(tetrazolate) (BaBT) in aqueous solution. All salts were fully characterized by IR spectroscopy, multinuclear (¹H, ¹³C, ¹⁵N) NMR spectroscopy, elemental analyses, density, differential scanning calorimetry (DSC), and impact sensitivity. Ba(HBTA)₂ ? 4 H₂O crystallizes in the triclinic space group P$\bar 1$ , as determined by single‐crystal X‐ray diffraction, with a density of 2.177 g cm^?3. The densities of the other organic energetic salts range between 1.55 and 1.75 g cm^?3 as measured by a gas pycnometer. The detonation pressure (P) values calculated for these salts range from 19.4 to 33.6 GPa, and the detonation velocities (ν_D) range from 7677 to 9487 m s^?1, which make them competitive energetic materials. Solid‐state ¹³C NMR spectroscopy was used as an effective technique to determine the structure of the products that were obtained from the metathesis reactions of biguanidinium sulfate with barium iminobis(5‐tetrazolate) (BaBTA). Thus, the structure was determined as an HBTA salt by the comparison of its solid‐state ¹³C NMR spectroscopy with those of ammonium 5‐(tetrazol‐5‐ylamino)tetrazolate (AHBTA) and diammonium iminobis(5‐tetrazolate) (A₂BTA).     

Maximum Compaction of Ionic Organic Explosives: Bis(hydroxylammonium) 5,5′‐Dinitromethyl‐3,3′‐bis(1,2,4‐oxadiazolate) and its Derivatives

Within this contribution on bis(oxadiazoles) we report on bis‐hydroxylammonium 5,5′‐dinitro‐methyl‐3,3′‐bis(1,2,4‐oxadiazolate), which (to the best of our knowledge) shows the highest density (2.00 g cm^?3 at 92 K, 1.95 g cm^?3 at RT) ever reported for an ionic CHNO explosive. Also the corresponding bis(ammonium) salt shows an outstanding density of 1.95 g cm^?3 (173 K). The reaction of the 3,3′‐bis(1,2,4‐oxadiazolyl)‐5,5′‐bis(2,2′‐dinitro)‐diacetic acid diethyl ester with different nitrogen‐rich bases, such as ammonia, hydrazine, hydroxylamine, and triaminoguanidine causes decarboxylation followed by the formation of the corresponding salts (cation/anion stoichiometry 2:1). The reactions are performed at ambient temperature in H₂O/MeOH mixtures and furnish qualitatively pure products showing characteristics of typical secondary explosives. The obtained compounds were characterized by multinuclear NMR spectroscopy, IR and Raman spectroscopy, as well as mass spectrometry. Single‐crystal X‐ray diffraction studies were performed and the structures of all compounds were determined at low temperatures. The thermal stability was measured by differential scanning calorimetry (DSC). The sensitivities were explored by using the BAM drophammer and friction test. The heats of formation were calculated by the atomization method based on CBS‐4M enthalpies. With these values and the X‐ray densities, several detonation parameters such as the detonation pressure, velocity, energy, and temperature were computed using the EXPLO5 code.     

Synthesis and Characteristics of Bis(2, 2‐dinitroethyl‐N‐nitro)ethylenediamine‐Based Energetic Salts

New energetic bis(2, 2‐dinitroethyl‐N‐nitro)ethylenediamine‐based salts exhibiting moderate physical properties, good detonation properties, and relatively low impact sensitivities were synthesized in high yield by direct reactions of bis(2, 2‐dinitroethyl‐N‐nitro)ethylenediamine with organic bases. The resulting salts were fully characterized by multinuclear NMR spectroscopy (¹H and ¹³C), vibrational spectroscopy (IR), differential scanning calorimetry (DSC), and elemental analysis. Solid‐state ¹⁵N NMR spectroscopy was used as an effective technique to further determine the structure of some products. Thermal decomposition kinetics and several thermodynamic parameters of some salts were obtained under non‐isothermal conditions by DSC. The densities of the energetic salts paired with organic cations were in the range 1.60–1.89 g · cm^–3 as measured with a gas pycnometer. Based on the measured densities and calculated heats of formation, detonation pressures and velocities were calculated using Explo 5.05 and found to be 23.6–44.8 GPa and 7790–9583 m · s^–1, respectively, which make them potentially useful as energetic materials.     

Nitrogen‐rich Salts based on 3‐Dinitromethyl‐[1,2,4]triazine: Synthesis,Characterization, and Performance

1,1‐Diamino‐2,2‐dinitroethylene (FOX‐7), one of the most well‐known energetic materials, has attracted broad attention around the world. To extend the chemistry of FOX‐7, we present here a series of energetic salts based on 3‐dinitromethyl‐[1,2,4]triazine, which is prepared from FOX‐7. All these salts were fully characterized using ¹H NMR, ¹³C NMR, IR, and elemental analysis. In addition, the potassium salt ( 2 ), ammonium salt ( 5 ), and guanidinium salt ( 7 ) were further confirmed by single‐crystal X‐ray diffraction. Extensive hydrogen bonds were observed in these salts. The salts exhibit moderate densities varying from 1.63 to 1.76 g · cm^–3. All the compounds possess good thermal stability with decomposition temperatures from 118 to 267 °C. The detonation performance for salts were calculated by using EXPLO 5, their detonation velocities are in the range from 6807 to 8614 m · s^–1 and detonation pressures fall between 18.8 to 31.6 GPa. All the salts exhibit very low mechanical sensitivity, which indicates their potential application as insensitive energetic materials.     

1,2,3‐Triazolo[4,5,‐e]furazano[3,4,‐b]pyrazine 6‐Oxide—A Fused Heterocycle with a Roving Hydrogen Forms a New Class of Insensitive Energetic Materials

The straightforward synthesis and energetic properties of a new class of energetic materials, 1,2,3‐triazolo‐ [4,5‐e]furazano[3,4‐b]pyrazine 6‐oxide and its energetic salts are described. They were characterized by IR and multinuclear NMR spectroscopy, elemental analysis, differential scanning calorimetry, and single‐crystal X‐ray diffraction are given. The X‐ray structures show that in the title compound, the hydrogen atom is bonded to the nitrogen in the pyrazine ring; however, in the salts, the negative charge is associated with the triazole nitrogen. Heats of formation for all compounds were calculated with the G2 method and then combined with experimentally determined densities to obtain detonation pressures (P) and velocities (D) by using EXPLO5 program. These new materials exhibit good densities and thermal stabilities, high heats of formation, acceptable detonation properties, and are insensitive to impact.     

Energetic N,N′‐Ethylene‐Bridged Bis(nitropyrazoles): Diversified Functionalities and Properties

A new class of N,N′‐ethylene‐bridged bis(nitropyrazoles) was synthesized and fully characterized. The highly efficient formation of the N,N′‐ethylene bridge was accomplished using dibromoethane and ammonium or potassium pyrazolate. Further functional‐group transformations of diaminobis(pyrazole) and dichlorobis(pyrazole) gave rise to diversified derivatives, including dinitramino‐, diazido‐ and hexanitrobis(pyrazole). Single‐crystal X‐ray diffractions were obtained for hexanitro and diazido derivatives to illustrate the structural characteristics. Heats of formation and detonation performance were calculated by using Gaussian 03 and EXPLO5 v6.01 programs, respectively. Because of the different functionalized groups, the impact and friction sensitivities of these new compounds range from insensitive to sensitive. Among them, the hexanitro derivative displays the most promising overall energetic properties (density (ρ)=1.84 g cm^?3; decomposition temperature (T_d)=250 °C; detonation pressure (P)=34.1 GPa; detonation velocity (v_D)=8759 m s^?1; impact sensitivity (IS)=25 J; friction sensitivity (FS)=160 N), which is competitive with those of 1,3,5‐trinitrotriazacyclohexane (ρ=1.80 g cm^?3; T_d=205 °C; P=35.0 GPa; v_D=8762 m s^?1; IS=7 J; FS=120 N).     

Energetic Salts Based on an Oxygen‐Containing Cation: 2,4‐Diamino‐1,3,5‐triazine‐6‐one

A family of energetic salts with high thermal stability and low impact sensitivity based on an oxygen‐containing cation, 2,4‐diamino‐1,3,5‐triazine‐6‐one, were synthesized and fully characterized by IR and multinuclear (¹H, ¹³C) NMR spectroscopy, elemental analysis, and differential scanning calorimetry. Insights into their sensitivities towards impact, friction, and electrostatics were gained by submitting the materials to standard tests. The structures of 2,4‐diamino‐1,3,5‐triazine‐6‐one nitrate, 2,4‐diamino‐1,3,5‐triazine‐6‐one sulfate, 2,4‐diamino‐1,3,5‐triazine‐6‐one perchlorate, 2,4‐diamino‐1,3,5‐triazine‐6‐one 5‐nitrotetrazolate were determined by single‐crystal X‐ray diffraction; their densities are 1.691, 1.776, 1.854, and 1.636 g cm^?3, respectively. Most of the salts decompose at temperatures over 180 °C; in particular, the salts 2,4‐diamino‐1,3,5‐triazine‐6‐one nitrate and 2,4‐diamino‐1,3,5‐triazine‐6‐one perchlorate, which decompose at 303.3 and 336.4 °C, respectively, are fairly stable. Furthermore, most of the salts exhibit excellent impact sensitivities (>40 J), friction sensitivities (>360 N), and are insensitive to electrostatics. The measured densities of these energetic salts range from 1.64 to 2.01 g cm^?3. The detonation pressure values calculated for these salts range from 14.6 to 29.2 GPa, and the detonation velocities range from 6536 to 8275 m s^?1; these values make the salts potential candidates for thermally stable and insensitive energetic materials.     

Synthesis,Crystal Structure,and Thermal Behavior of a Novel Insensitive Energetic Cocrystal Composed of 3,3′‐Bis(1,2,4‐oxadiazole)‐5,5′‐dione and 4‐Amino‐1,2,4‐triazole

A novel insensitive energetic cocrystal consisting of 3,3′‐bis(1,2,4‐oxadiazole)‐5,5′‐dione and 4‐amino‐1,2,4‐triazole in a 1:2 molar ratio was prepared and characterized. The structure of this cocrystal was characterized by single‐crystal X‐ray diffraction. The crystal structure of the cocrystal is a monoclinic system with P1 space group. Properties of the cocrystal studied included thermal decomposition and detonation performance. This cocrystal has a crystal density of 1.689 g · cm^–3 at 173 K and good detonation performance (D = 6940 m · s^–1, P = 20.9 GPa). Moreover, measured impact and friction sensitivities (IS > 40 J, FS > 360 N) show that it can be classified as an insensitive energetic material. Its thermodynamic properties indicate that it has moderate thermal stability with a sharp exothermic peak (244 °C, 5 K · min^–1) and a high critical temperature of thermal explosion (523 K). In view of the observations above, it may serve as a promising alternative to known explosives such as TNT.     

Synthesis and Characterization of 3,3′‐Bis(Dinitromethyl)‐5,5′‐Azo‐1H‐1,2,4‐Triazole

The synthesis of 3,3′‐bis(dinitromethyl)‐5,5′‐azo‐1H‐1,2,4‐triazole ( 5 ) using the readily available starting material 2‐(5‐amino‐1H‐1,2,4‐triazol‐3‐yl)acetic acid ( 1 ) is described. All compounds were characterized by means of NMR, IR, and Raman spectroscopy. The energetic compound 5 was additionally characterized by single‐crystal X‐ray diffraction and DSC measurements. The sensitivities towards impact, friction and electrical discharge were determined. In addition, detonation parameters (e.g. heat of explosion, detonation velocity) of the target compound were computed using the EXPLO5 code based on the calculated (CBS‐4M) heat of formation and X‐ray density.     

Preparation,Crystal Structure,and Thermal Analysis of Two Energetic Salts Based on Nitro Phenolic Compounds with Diamino‐glyoxine

As a key research objective for environmentally friendly energetic materials, energetic salts without heavy metal have received wide attention. The energetic salts DAG · PA · H₂O ( 1 ) and DAG · TNR · H₂O ( 2 ) were synthesized by using diamino‐glyoxine (DAG) and picric acid (PA) or 2, 4,6‐trinitro‐resorcinol (TNR) as raw materials, and their structures were characterized by elemental analysis, FT‐IR, ¹H NMR, and ¹³C NMR spectroscopy. Single crystals of the title salts were cultured and their structures were determined by X‐ray single‐crystal diffraction. Both salts belong to the triclinic space group P1 with density values of 1.764 and 1.751 g · cm^–3, respectively. The thermal decomposition behaviors of both salts were investigated by differential scanning calorimetry (DSC), the non‐isothermal kinetic parameters and the critical temperature of thermal explosion were calculated. The heats of formation for the salts were also determined through the combustion heats date measured by using the oxygen bomb calorimetry. In addition, the detonation pressure (P) and detonation velocities (D) of the salts were predicted by using the K‐J equations, and their sensitivities towards impact and friction were tested. The results indicated that the title salts have potential applications in the field of energetic materials.     

Synthesis of 3‐(3,5‐dinitropyrazol‐4‐yl)‐4‐nitrofurazan and its salts

The annulation reaction of vinamidinium salt containing nitrofurazanyl moiety at the β‐position gives access to the corresponding pyrazole. At nitration, two nitro groups were installed to the pyrazole ring. The synthesized 3‐(3,5‐dinitropyrazol‐4‐yl)‐4‐nitrofurazan 13 is strong NH acid and a new family energetic salts was prepared by direct neutralization with high nitrogen bases. Compound 13 crystallizes in the monoclinic space group P2₁/c, and charaterized by high density of 1.979 g/cm³ (at 100 K). J. Heterocyclic Chem., (2012).     

Synthesis,Characterization, and Energetic Properties of Alkaline and Alkaline Earth Salts of 5,5′‐bistetrazole‐1,1′‐diolate

5,5′‐Bistetrazole‐1,1′‐diolate‐based energetic salts from alkaline (Li⁺, K⁺, and Na⁺) and alkaline earth metal salts (Mg²⁺, Ca²⁺, and Ba²⁺) were synthesized in a simple, straightforward manner and were characterized by IR and NMR spectroscopy, and elemental analysis. Single‐crystal X‐ray diffraction of 4 salts (Li⁺, Na⁺, K⁺, and Mg²⁺) is given. The X‐ray structures show that in the title compounds, the metal atoms are bonded to the nitrogen and oxygen in the bistetrazole ring to form the sandwich structure. In addition, thermal stabilities of all title compounds were determined with differential thermal analysis‐thermal gravity analysis. All these new materials exhibit excellent thermal stabilities, high density, and excellent insensitivity to impact (h ₅₀ > 60 cm). Especially, the potassium salt is of interest as potential “green heat‐resistance explosive” with high density and high thermal stability as well as low sensitivity.     

Two Energetic Salts based on 5,5′‐Bitetrazole‐1,1′‐diolate: Syntheses,Characterization, and Properties

Two salts based on 1H,1′H‐5,5′‐bitetrazole‐1,1′‐diolate (BTO) anion with pyrazole ( 1 ) and imidazole ( 2 ) cations were synthesized with metathesis reactions. Structural characterization was accomplished for them by using the element analysis, Fourier transform infrared spectroscopy (FT‐IR), NMR and mass spectrum, and X‐ray single crystal diffraction. Thermal analysis for the title salts were determined by means of differential scanning calorimetry (DSC) and thermogravimetry‐derivative thermogravimetry (TG‐DTG) as well as the calculation of non‐isothermal kinetic parameters. Consequently, both salts shown acceptable thermal stabilities as the decomposition temperatures were over 200 °C. The enthalpies of formation were calculated for these salts using the measured combustion energies with a result of 70.6 kJ · mol^–1 for 1 and –47.8 kJ · mol^–1 for 2 , respectively. Impact and friction sensitivities were also tested and the results indicated that these salts both have low sensitivities (>40 J, 120 N). The title energetic salts possess acceptable performance, they can therefore be applied in the field of energetic materials.     

The Environmentally Friendly Energetic Salt (ATZ)(TNPG) Based on 4‐Amino‐1, 2, 4‐triazole (ATZ) and Trinitrophloroglucinol (TNPG)

The environmentally friendly energetic salt (ATZ)(TNPG) (ATZ = 4‐amino‐1, 2, 4‐triazole, TNPG = trinitrophloroglucinol) was synthesized and characterized by elemental analysis and FT‐IR spectroscopy. The crystal structure was determined by X‐ray single crystal diffraction. It crystallizes in monoclinic space group P2₁/c and its crystal density is 1.832 g · cm^–3. Thermal decomposition mechanisms were investigated through differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). In addition, the experimental data showed that the energy of combustion was approximately equal to the energies of combustion of RDX (1, 3, 5‐trinitro‐1, 3, 5‐triazacyclohexane) and HMX (1, 3, 5, 7‐tetranitro‐1, 3, 5, 7‐tetraazocane). The non‐isothermal kinetics parameters were also studied by applying Kissinger's, Ozawa's, and Starink's methods. Determination of the sensitivities revealed higher sensitivities of (ATZ)(TNPG) as compared to (ATZ)(PA) (PA = picrate).     

原位水热合成的二(2,4-二(对硝基苯)-1,3,5-环戊二烯铜配合物的实验和理论研究

以4-硝基对苯腈,氨水和铜盐反应于在原位水热条件下合成了二（2,4-二（对硝基苯）-1,3,5-环戊二烯铜配合物,通过单晶X射线衍射,元素分析,红外,核磁光谱和热重分析等手段对其进行了表征。结构分析表明,铜与四个源自原位合成的配体上的氮原子配位形成平面四边形构型。基于密度泛函的理论计算对配合物的热力学稳定性进行了阐释。     

Energetic Derivatives of 4, 4′,5, 5′‐Tetranitro‐2, 2′‐bisimidazole (TNBI)

4, 4′,5, 5′‐Tetranitro‐2, 2′‐bisimidazole (TNBI) was synthesized by nitration of bisimidazole (BI) and recrystallized from acetone to form a crystalline acetone adduct. Its ammonium salt ( 1 ) was obtained by the reaction with gaseous ammonia. In order to explore new explosives or propellants several energetic nitrogen‐rich 2:1 salts such as the hydroxylammonium ( 3 ), guanidinium ( 4 ), aminoguanidinium ( 5 ), diaminoguanidinium ( 6 ) and triaminoguanidinium 7 4, 4′,5, 5′‐tetranitro‐2, 2′‐bisimidazolate were prepared by facile metathesis reactions. In addition, methylated 1, 1′‐dimethyl‐4, 4′,5, 5′‐tetranitro‐2, 2′‐bisimidazole (Me₂TNBI, 8 ) was synthesized by the reaction of 2 and dimethyl sulfate. Metal salts of TNBI can also be easily synthesized by using the corresponding metal bases. This was proven by the synthesis of pyrotechnically relevant dipotassium 4, 4′,5, 5′‐tetranitro‐2, 2′‐bisimidazolate ( 2 ), which is a brilliant burning component e.g. in near‐infrared flares. All compounds were characterized by single crystal X‐ray diffraction, NMR and vibrational spectroscopy, elemental analysis and DSC. The sensitivities were determined by BAM methods (drophammer and friction tester). The heats of formation were calculated using CBS‐4M electronic enthalpies and the atomization method. With these values and mostly the X‐ray densities different detonation parameters were computed by the EXPLO5 computer code. Due to the great thermal stability and calculated energetic properties, especially guanidinium salt 4 could be served as a HNS replacement.