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1.
    
In this paper, results of the research on the application of thin layer chromatography (TLC) for the determination of 1,1‐diamino‐2,2‐dinitroethene (FOX‐7, DADNE) and its precursors produced in the synthetic path starting from 2‐methylpyrimidine‐4,6(1H,5H)‐dione are presented. Analytical parameters of the substances and methodology of their quantitative analysis were determined, and the results obtained were used for monitoring the FOX‐7 synthesis process.  相似文献   

2.
    
2‐(dinitroethylene)‐4,5‐imidazolidinedione, which is the intermediate in preparing FOX‐7, was synthesized by acetamidine hydrochloride and diethyl oxalate. Ring cleavage reaction could be carried out more quickly, when methanol, water, and formic acid were used as ring cleavage reagents; the disadvantages from using ammonia as ring cleavage reagent could be overcome with yields of up to 65.5%. When water is used as ring cleavage reagent, the reaction rate will be high and the reaction conditions will be milder. So this method is more suitable for further up‐scaling research.  相似文献   

3.
    
1,4‐Dimethyl‐5‐aminotetrazolium 5‐nitrotetrazolate ( 2 ) was synthesized in high yield from 1,4‐dimethyl‐5‐aminotetrazolium iodide ( 1 ) and silver 5‐nitrotetrazolate. Both new compounds ( 1, 2 ) were characterized using vibrational (IR and Raman) and multinuclear NMR spectroscopy (1H, 13C, 14N, 15N), elemental analysis and single crystal X‐ray diffraction. 1,4‐Dimethyl‐5‐aminotetrazolium 5‐nitrotetrazolate ( 2 ) represents the first example of an energetic material which contains both a tetrazole based cation and anion. Compound 2 is hydrolytically stable with a high melting point of 190 °C (decomposition). The impact sensitivity of compound 2 is very low (30 J), it is not sensitive towards friction (>360 N). The molecular structure of 1,4‐dimethyl‐5‐aminotetrazolium iodide ( 1 ) in the crystalline state was determined by X‐ray crystallography: orthorhombic, Fddd, a=1.3718(1) nm, b=1.4486(1) nm, c=1.6281(1) nm, V=3.2354(5) nm3, Z=16, ρ=1.979 g cm−1, R1=0.0169 (F>4σ(F)), wR2 (all data)=0.0352.  相似文献   

4.
    
Self‐sensitized FOX‐7 (1,1‐diamino‐2,2‐dinitroethylene) was prepared by a facile heat treatment process near the decomposition temperature. Field emission scanning electron microscopy (FE‐SEM) shows the self‐sensitized FOX‐7 becomes multiple layers and porous after heat treatment. N2 adsorbance measurements revealed that its specific surface area (6.754 m2 g−1) is 20 times of the area of expanded ammonium nitrate. The SAXS tests further indicate the existence of a large amount of voids in self‐sensitized FOX‐7 and the pore size is about 30 nm, belonging to mesopore (2.0–50 nm). Based on the analysis of X‐ray powder diffraction (XRD), the self‐sensitized porous FOX‐7 consists of α‐phase and a spot of γ‐phase. The TG‐DSC results show that the self‐sensitized FOX‐7 exhibits excellent thermal stability. The impact, frication and electrostatic spark sensitivities of self‐sensitized FOX‐7 also have considerable enhancement. This new method provides a promising route for exploring new green primary explosive replacements.  相似文献   

5.
    
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.  相似文献   

6.
    
The stability of Ni‐YSZ anodes as part of solid oxide fuel cells (SOFCs) towards redox cycling is an important issue for successfully introducing the technology. Detailed knowledge of the NiO‐Ni transitions and their impact on the mechanical integrity of the whole system is necessary to improve the overall stability. In the present paper, a unique in‐situ X‐ray diffraction setup is presented which allows monitoring of the local structural changes during processing of SOFCs. With this setup technological SOFCs – a half cell and a full cell – were studied with respect to NiO‐Ni transitions in repeated reduction‐oxidation cycles, under conditions relevant for SOFC application. It was found that the redox kinetics is a function of the sample depth. Ni particles further away from the surface were reduced/oxidized at a slower rate than particles close to the surface.  相似文献   

7.
    
Ongoing research into new insensitive energetic materials with low sensitivity toward accidental stimuli, high thermal stability and high performance characteristics is undertaken in many research groups worldwide. In order to obtain promising compounds, which fulfil the sensitivity, stability, and performance requirements, researchers use many different strategies. One of the most promising approaches is the synthesis of novel explosives with tailored physico‐chemical properties. In this review the synthesis and properties of some both covalent (NTO, TEX, FOX‐7, ADNP, DNPPs) and ionic (salts of ANDP and DNPP) insensitive explosives are presented, which are of high interest to this field of research.  相似文献   

8.
    
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.  相似文献   

9.
    
Dinitromethyltetrazole is an easily accessible and highly energetic compound which – due to its acidity – gives rise to a wide range of energetic salts. The present study investigates dinitromethyltetrazole and several of its salts. The compounds were characterized using multinuclear NMR as well as vibrational spectroscopy and X‐ray diffraction. The energetic properties were estimated using the EXPLO5 code and the sensitivities of the compounds were measured.  相似文献   

10.
    
1,3‐Diazido‐2‐nitro‐2‐azapropane (DANP) and 1,7‐diazido‐2,4,6‐trinitro‐2,4,6‐triazaheptane (DATH) were synthesized, thoroughly analyzed, and their explosive properties and sensitivities toward friction and impact were measured. The precursors 1,3‐diacetoxy‐2‐nitro‐2‐azapropane ( 1 ), 1,3‐dichloro‐2‐nitro‐2‐azapropane ( 3 ), and 1,7‐dichloro‐2,4,6‐trinitro‐2,4,6‐triazaheptane ( 4 ) – as well as DATH – were furthermore characterized by X‐ray diffraction.  相似文献   

11.
    
We have performed a series of highly‐instrumented experiments examining corner‐turning of detonation. A TATB booster is inset 15 mm into LX‐17 (92.5% TATB, 7.5% kel‐F) so that the detonation must turn a right angle around an air well. An optical pin located at the edge of the TATB gives the start time of the corner‐turn. The breakout time on the side and back edges is measured with streak cameras. Three high‐resolution X‐ray images were taken on each experiment to examine the details of the detonation. We have concluded that the detonation cannot turn the corner and subsequently fails, but the shock wave continues to propagate in the unreacted explosive, leaving behind a dead zone. The detonation front farther out from the corner slowly turns and eventually reaches the air well edge 180° from its original direction. The dead zone is stable and persists 7.7 μs after the corner‐turn, although it has drifted into the original air well area. Our regular reactive flow computer models sometimes show temporary failure but they recover quickly and are unable to model the dead zones. We present a failure model that cuts off the reaction rate below certain detonation velocities and reproduces the qualitative features of the corner‐turning failure.  相似文献   

12.
    
A complex from copper(II) perchlorate with 4‐amino‐1,2,4‐triazole (4‐AT, C2H4N4) was synthesized, and elemental composition, molecular structure, and explosive properties were determined. To this end, elemental and X‐ray analyses were carried out, sensitivity to mechanical and thermal stimuli was measured, mechanism of thermal decomposition was investigated, and kinetic parameters of decomposition were determined. In the next step measurements of heat of combustion and detonation velocity were performed. Detonation parameters were also calculated. It was stated that the complex has slightly distorted square bipyramidal (4+2) coordination. The four basal bonds are formed by nitrogen atoms of four 4‐AT molecules. The coordination of the metal is completed by two axial oxygen atoms, one of the perchlorate ion, and one of the water molecule. With respect to explosive properties, tetrakis(4‐AT)copper(II) perchlorate monohydrate belongs to the group of sensitive secondary explosives.  相似文献   

13.
    
1,1‐Diamino‐2,2‐dinitroethylene (FOX‐7) is a novel high‐energy insensitive material with good thermal stability and low sensitivity, and exhibits excellent application performance in the field of insensitive ammunitions and solid propellant. Although FOX‐7 is simple in molecular composition and structure, its chemical reactivity is abundant and surprising, including salification reaction, coordination reaction, nucleophilic substitution reaction, acetylate reaction, oxidizing reaction, reduction reaction, electrophilic addition reaction, among other reactions. These reactions are systemically summarized and some reaction mechanisms are analyzed in this review.  相似文献   

14.
    
Pin and X‐ray corner turning data have been taken on ambient LX‐17 and PBX 9052, and the results are listed in tables as an aid to future modeling. The results have been modeled at 4 zones/mm with a reactive flow approach that varies the burn rate as a function of pressure. A single rate format is used to simulate failure and detonation in different pressure regimes. A pressure cut‐off must also be reached to initiate the burn. Corner turning and failure are modeled using an intermediate pressure rate region, and detonation occurs at high pressure. The TATB booster is also modeled using reactive flow, and X‐ray tomography is used to partition the ram‐pressed hemisphere into five different density regions. The model reasonably fits the bare corner turning experiment but predicts a smaller dead zone with steel confinement, in contradiction with experiment. The same model also calculates the confined and unconfined cylinder detonation velocities and predicts the failure of the unconfined cylinder at 3.75 mm radius. The PBX 9502 shows a smaller dead zone than LX‐17. An old experiment that showed a large apparent dead zone in Composition B was repeated with X‐ray transmission and no dead zone was seen. This confirms the idea that a variable burn rate is the key to modeling. The model also produces initiation delays, which are shorter than those found in time‐to‐detonation.  相似文献   

15.
    
This study reports the preparation of 1‐amino‐1,2,3‐triazole‐3‐oxide (DPX2) and its transformation to 1,2,3,4‐tetrazine‐1‐oxide. DPX‐2 provides insight into a novel N‐oxide/N‐amino high‐nitrogen system, being the first energetic material in this class. The ability of this material to undergo a nitrene insertion forming 1,2,3,4‐tetrazine‐1‐oxide was also studied, and evidence for this material, the first non‐benzoannulated 1,2,3,4‐tetrazine‐1‐oxide, is presented. The existence of both of these materials opens new strategies in energetic materials design. DPX2 was characterized chemically (Infrared, Raman, NMR, X‐ray) and as a high explosive in terms of energetic performances (detonation velocity, pressure, etc.) and sensitivities (impact, friction, electrostatic). DPX‐2 was found to possess good thermal stability and moderate sensitivities, indicating the viability of N‐amino N‐oxides as a strategy for the preparation of new energetic materials.  相似文献   

16.
    
We report on a first principles analysis of chemical decomposition reaction in a crystalline FOX‐7 (1,1‐diamino‐2,2‐dinitroethylene) molecule, which is a good candidate for insensitive energetic materials. Our calculations are based on variable‐cell shape methods under pressure, density functional theory with localized numerical orbital and pseudopotential, together with ab initio biasing molecular dynamics. The calculated crystal structure and equation of state (pressure vs. volume) up to 8 GPa agrees well with the corresponding experimental data. A chemical decomposition by intermolecular hydrogen transfer is found at higher pressure. This decomposition appears to be driven by a weakening in the chemical hardness. This suggests that the molecular HOMO and LUMO orbital energy difference is decreased when intermolecular hydrogen transfers occur, and for the FOX‐7 crystal the band gap is narrowed with increasing external pressure.  相似文献   

17.
    
Phase behavior of octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX) is investigated by X‐ray powder diffraction (XRD). The XRD patterns at elevated temperature show that there is a co‐existing temperature range of β‐ and δ‐phase during the phase transition process. Additionally, mechanical forces can catalyze the conversion from δ‐ back to β‐phase. Based on the diffraction patterns of β‐ and δ‐phase at different temperatures, we calculate the coefficients of thermal expansion by Rietveld refinement. For β‐HMX, the linear coefficients of thermal expansion of a‐axis and b‐axis are about 1.37×10−5 and 1.25×10−4 °C−1. A slight decrease in c‐axis with temperature is also observed, and the value is about −0.63×10−5 °C−1. The volume coefficient of thermal expansion is about 1.60×10−4 °C−1, with a 2.2% change from 30 to 170 °C. For δ‐HMX, the linear coefficients of thermal expansion of a‐axis and c‐axis are found to be 5.39×10−5 and 2.38×10−5 °C−1, respectively. The volume coefficient of thermal expansion is about 1.33×10−4 °C−1, with a 2.6% change from 30 to 230 °C. The results indicate that β‐HMX has a similar volume coefficient of thermal expansion compared with δ‐HMX, and there is about 10.5% expansion from β‐HMX at 30 °C to δ‐HMX at 230 °C, of which about 7% may be attributed to the reconstructive transition.  相似文献   

18.
    
Structural investigation of the crystallized 2‐nitropropane compound (C3H7NO2) was performed by X‐ray powder diffraction at low temperature. A first crystalline phase, called phase α, is observed below 172 K. This form exhibits a triclinic symmetry with P‐1 space group (a=1.0313(3) nm, b=0.5873(2) nm, c=1.6146(4) nm, α=90.17(2)°, β=92.17(2)° and γ=90.09(2)°), and Z=8). At Tt=172 K, a structural transition is observed which brings to another phase, called phase β (above Tt). This one contains four molecules per unit cell and shows a Pc21n symmetry (a=1.0141(3) nm, b=0.5855(2) nm, and c=0.8319(4) nm). In addition to the doubling of the c‐axis, structural networks differ by the different conformations of NO2 nitro groups and by the orientation of the propyl group in the unit cell. Both crystal structures can be described using infinite zigzag chains of C3H7NO2 molecules showing a regular alternation along the c‐axis. Two orientations of these ribbons, called A and B, are observed. The crystal structures are then built with different distribution of these ribbons within the crystalline network.  相似文献   

19.
    
An X‐ray diffraction method was applied for the quantitative determination of the ε‐Hexanitrohexaazaisowurtzitane (HNIW) in polymorphs of HNIW. The XRD patterns of four polymorphs illustrate the unique nonoverlapping peak at 19.9° which belongs to ε‐HNIW. The intensity ratio of the peak at 19.9° of ε‐HNIW to the peak at 79.6° of α‐Al2O3 is proportional to the weight ratio of standard ε‐HNIW to the internal standard of α‐Al2O3, which enables the internal standard method. When the particle size of the sample is less than 10 μm, the content of ε‐HNIW ranging from 70 to 100 wt.‐% can be determined with an absolute error below 2.0%.  相似文献   

20.
    
The title compound {[Ca(CHZ)2(H2O)](NTO)2⋅3.5H2O}n was synthesized by using an aqueous solution of calcium 3‐nitro‐1,2,4‐triazol‐5‐onate and carbohydrazide (CHZ, NH2NHCONHNH2). Its molecular structure was determined by X‐ray diffraction and its crystals have monoclinic form, with space group C2/c, where a=2.4483(4) nm, b=1.2581(2) nm, c =1.6269(3) nm, β=121.168(12)°, V=4.2879(13) nm3, Z=8, dc=1.727 g⋅cm−3, μ (Mo Kα)=3.9 cm−1, M=557.47, F(000)=2312. The coordination polyhedron is a tricapped trigonal prism in a tetradecahedron with a coordination number of nine. The whole molecule has many long chains formed through the carbohydrazide bridges, and every long chain is unlimited along the c axis. The long chains are linked by hydrogen bonds to form the crystal structure.  相似文献   

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