Primary Explosives Research Articles

Benzofuroxan‐Based Energetic Materials with Alternating Nitro and Hydroxyl Groups: Synthesis, Characterization, and Energetic Properties

AbstractDue to its good stability, density and oxygen balance, the benzofuroxan fused ring framework has attracted particular attention in the field of high energy density materials. The planar structure of the benzofuroxan facilitates the straightforward derivatization with explosophores and contributes to molecular stability. In this work, a benzofuroxan scaffold was utilized to develop a highly dense energetic material, namely 5,7‐dihydroxy‐4,6‐dinitrobenzo[c][1,2,5]oxadiazole 1‐oxide (DHDNBF). The successive inclusion of explosophores like nitro (−NO2) and oxidative functionality like hydroxyl (−OH) on benzofuroxan resulted in an impressive density (ρ=1.91 g cm−3) and a positive oxygen balance (6.20 %) in DHDNBF (2). Furthermore, the hydroxy groups on DHDNBF enable the formation of dicationic energetic salts 3–7, contributing to additional modifications in the overall performance. Energetic salts 3, 4, and 5 exhibit significantly higher densities ranging from 1.84 (5) to 1.87 (3) g cm−3 and possess a favorable oxygen balance approaching zero or equal to zero. A marked improvement in thermal stabilities was observed in all the energetic salts (3–7) compared to their neutral counterparts, DHDNBF. Energetic salts 4 (Dv=8459 m s−1, P=32.10 GPa) and 5 (Dv=8539 m s−1, P=30.37 GPa) possess good energetic performance, comparable to that of well‐known explosives such as LLM‐105 (Dv=8560 m s−1, P=33.4 GPa). Overall, the favorable characteristics of energetic salts 4 and 5 make them potential candidates for use as benzofuroxan‐based secondary and primary explosives, respectively, in various military and civilian applications.

A modified phosphorus-based inhibitor for dry water inhibitor and its chemical mechanisms in preventing benzoyl peroxide explosion

Dust explosions caused by benzoyl peroxide (BPO) pose a significant risk to the chemical industry, making the development of high-performance inhibitors essential. The effect of a novel inhibitor on the explosion behavior of BPO dust was studied through experiments and simulations. The chemical mechanism behind the suppressed BPO dust explosion was clarified. The primary explosion hazard of BPO stems from the instability of the oxygen–oxygen bond. To address this, a novel phosphorus-based dry water powder inhibitor, MAP-DW, was prepared which effectively captures key reactive radicals involved in the chain reaction. At the optimal explosion concentration of BPO, a concentration of 400 g/m3 of MAP-DW reduced the maximum explosion pressure and the maximum explosion pressure rise rate by 96.48 % and 99.58 %, respectively. The suppression effects of MAP-DW on the explosion of BPO dust include heat absorption, oxygen dilution, thermal insulation, and capture of key free radicals. The kinetic simulation results showed that the suppression cycle between phosphorus-containing substances captured key chain reaction radicals, and the coupled suppression among NH3, H2O, and phosphorus-containing substances dominated the suppression mechanism of MAP-DW on BPO dust explosion. This study provides new insights into the characterization and suppression of BPO dust explosion, while also supplying crucial data for the safe utilization of peroxides.

Trace detection of styphnate from pre- and post-blast samples by hydrophilic interaction chromatography with tandem mass spectrometry.

Although ubiquitous in explosives and ammunition, few trace methods for detection of heavy metal-containing primary explosives from forensic samples are currently in practice. Extracts of cotton swabs or direct sampling of items were cleaned up using solid-phase extraction to remove heavy metal contaminants (i.e., lead) while retaining the organic styphnate component. The styphnate was chromatographically separated using hydrophilic interaction chromatography (HILIC) and detected via high-resolution tandem mass spectrometry (MS/MS) using a sensitive, targeted approach in five minutes or less. A mass spectrometric method for the detection of styphnate, including limit of detection (LOD), sample stability, and interferences was developed. We present a validated method for the extraction, separation, and detection of styphnate from lead(II) styphnate with an estimated LOD of 257 ppt (pg/mL). We detail an improved LOD relative to previous reports for trace detection of styphnate and, for the first time to our knowledge, the post-blast analysis of styphnate.

Synthesis and Performance Evaluation of Zwitterionic C-N Bonded Triazole-Tetrazole-Based Primary Explosives.

Developing advanced metal-free nitrogen-enriched primary explosives is challenging due to the inherent risks associated with their synthesis and handling. However, there is an urgent need to develop novel lead-free, nitrogen-rich primary explosives that offer balanced energetic properties. C-N bonded bicyclic compound 3-azido-1-(1H-tetrazol-5-yl)-1H-1,2,4-triazol-5-amine (4), its salts, and 3,5-diazido-1H-1,2,4-triazole (8) were synthesized from inexpensive starting materials resulting in a fine blend of sensitivity and stability. These compounds exhibit high nitrogen content (79.78 to 83.43%), good thermal stability (129-210 °C), excellent detonation performance (VOD: 8592-9361 ms-1, DP: 27.1-33.8 GPa), and acceptable sensitivity (IS: 2.5-30 J, FS: 72-288 N). The hot needle tests of compounds 4 and 8 exhibit excellent ignition performance. All of the newly synthesized compounds were fully characterized using infrared spectroscopy (IR), high-resolution mass spectroscopy (HRMS), multinuclear magnetic spectroscopy (NMR), elemental analysis (EA), thermogravimetric analysis-differential scanning calorimetry (TGA-DSC), and 2, 4, and 8 were confirmed by single-crystal X-ray crystallographic studies. The molecular electrostatic potential (ESP), noncovalent interactions reduced density gradient (NCI-RDG) method, and QTAIM analysis were performed to investigate the intermolecular interactions. Together with promising performance properties, ease of synthesis, and ignitability, they are highly suitable candidates to pave new avenues for future applications.

Taming of Triazole, Tetrazole, and Azido Groups: Nitrogen-Rich Energetic Materials with High Thermal Stabilities.

Nitrogen-rich energetic materials are of interest due to their potential use as high-energy-density materials in various applications. However, most compounds with a high nitrogen content show poor thermal stabilities, which may limit their use in certain applications. In pursuit of nitrogen-rich energetic materials, this study presents the synthesis and characterization of two nitrogen rich energetic compounds, namely 3-azido-1-(1H-tetrazol-5-yl)-1H-1,2,4-triazol-5-amine (3, C3H3N11, N%: 79.78) and (E)-1,2-bis(3-azido-1-(1H-tetrazol-5-yl)-1H-1,2,4-triazol-5-yl) diazene (7, C6H2N22, N%: 80.62). Compounds 3 and 7 have high thermal stabilities of 216 and 221 °C, respectively, making them the most thermally stable among metal-free primary explosives. Additionally, they show good energetic performance (vD: 8345 m s-1; P: 25.17 GPa; vD: 8275 m s-1; P: 25.57 GPa), making them potential candidates for metal-free high energy primary explosive. The energetic salts of 3 and 7 were also investigated. Among them, hydrazinium salt 11 displays better energetic performance (vD: 9089 m s-1; P: 30.55 GPa), which was on par with those of cyclotetramethylene tetranitramine (HMX). This research contributes to the exploration of nitrogen-rich energetic materials with potential applications in various fields.

Investigation and CFD simulation of coal dust explosion accident in confined space: A case study of Gaohe Coal Mine Ventilation Air Methane oxidation power plant

The study investigates a coal dust explosion accident within a confined space in Shanxi. The accident was caused by coal dust coming into contact with a high-temperature heat source under the influence of the stack effect. Based on the investigation of the coal dust explosion accident, the study uses computational fluid dynamics (CFD) simulation to reconstruct the accident scenario. The simulation results provide a detailed depiction of coal dust movement within subsurface semi-enclosed confined spaces during the ventilation diffusion stage, influenced by the stack effect, and confirm the formation of a coal dust layer at the heat source due to coal dust deposition. The simulation results of the two explosion processes indicate that excessively high coal dust concentrations within confined spaces have a negative correlation with the development of explosion flames and the peak overpressure. It resulted in a secondary explosion with a relatively low concentration of coal dust, where the peak overpressure was five times that of the primary explosion. Comparative analysis between simulation results and actual investigations the accuracy of the CFD simulation in capturing the accident process and its characteristics, providing valuable insights for preventing and controlling coal dust explosion accidents.

Zwitterionic Energetic Materials: Synthesis, Structural Diversity and Energetic Properties.

Zwitterionic compounds are an emergent class of energetic materials and have gained synthetic interest of many in the recent years. Due to their better packing efficiencies and strong inter/intramolecular electrostatic interactions, they often ensue superior energetic properties than their salt analogues. A systematic review from the perspective of design, synthesis, and physicochemical properties evaluation of the zwitterionic energetic materials is presented. Depending on the parent ring(s) used for the synthesis and the type of moieties bearing positive and negative charges, different classes of energetic materials, such as primary explosives, secondary explosives, heat resistant explosives, oxidizers, etc., may result. The properties of some of the energetic zwitterionic compounds are also compared with analogous energetic salts. This review will encourage readers to explore the possibility of designing new zwitterionic energetic materials.

Analysis of the building on the air shock wave by direct dy-namic method (with LIRA-FEM soft-ware)

Calculation of the impact of air shock waves on buildings is extremely important for our country, which is in a state of war. Studying the structural safety and survivability of load-bearing reinforced concrete structures under influence is an important task, especially for critical infrastructure facilities. A blast scenario can be carried out directly in an FEA program as a time history analysis evaluate varying levels of structural damage and to minimize loss of life.The article is devoted to the features of the calcula-tion of buildings under the influence of air shock waves using the finite element method using the LIRA-FEM software complex. The features of ex-plosive loads, typical shock wave parameters, and the order of analysis for explosive loads are taken into consideration. The primary distinctions be-tween shock or explosion impacts and regular loads are explained. In-depth consideration is given to the problems of determining shock wave parameters and how they affect structures. Also included are the techniques for evaluating structures for explosive impacts.Using LIRA-FEM software, a preliminary analysis of the explosion resistance of a one-story building with a metal frame and sheet metal wall infill is carried out. It is demonstrated how to define impulse loads from a shock wave to the side walls, roofs, rear walls, and walls facing the explosion. The article describes the peculiarities of the "Time History Analysis" system in the LIRA-FEM program for ex-plosion dynamics problems.This analysis helps in the assessment of risks in the design of protective structures, development of pro-ject solutions and conducting research in the field of explosion safety.

Self-Assembly Method for Synthesizing High-Dimensional EMOFs with High Stability and Laser Response.

Dimension and solvent molecules affect the performance of energetic metal-organic frameworks (EMOFs). High-dimensional EMOFs are usually characterized by high stability and low sensitivity due to their complex network structure. However, solvent molecules affect the detonation performance of EMOFs, and these molecules may be removed at low temperatures, resulting in structural collapse and affecting the stability of EMOFs. In this work, zero-dimensional (0D) Co(AFTO)2·(H2O)2 (EMOF 1) and Ni(AFTO)2·(H2O)2 (EMOF 2) with coordinated water molecules and [Co(AFTO)2]n·EtOH (EMOF 3) and [Ni(AFTO)2]n (EMOF 4) (AFTO = 5-(4-amino-furazan-3-yl)-1-hydroxytetrazole) with high-dimensional structure were synthesized using hydrothermal and self-assembly methods in ethanol, respectively. Structural and performance tests show that EMOF 3 and 4 exhibit remarkable thermal stability and low mechanical sensitivity. This method is a simple, effective, and green technique for synthesizing high-dimensional EMOFs with high stability through self-assembly in ethanol solution. In addition, EMOF 3 and 4 can be used as primary green laser explosives.

1- and 2-Tetrazolylacetonitrile as Versatile Ligands for Laser Ignitable Energetic Coordination Compounds.

1- and 2-Tetrazolylacetonitrile (1- and 2-TAN) have been synthesized by the reaction of chloroacetonitrile with 1H-tetrazole under basic conditions. They further were reacted with sodium azide in the presence of zinc(II) chloride to form 5-((1H-tetrazol-1-yl)methyl)-1H-tetrazole (1-HTMT) and 5-((2H-tetrazol-2-yl)methyl)-1H-tetrazole (2-HTMT). The nitrogen-rich compounds have been applied as ligands for Energetic Coordination Compounds (ECCs) and show interesting coordinative behavior due to different bridging modes. The structural variability of the compounds has been proved by low-temperature X-ray analysis. The ECCs were analyzed for their sensitivities to provide information about the safety of handling and their capability to serve as primary explosives in detonator setups to replace the commonly used lead styphnate and azide. All colored ECCs were evaluated for their ignitability by laser initiation in translucent polycarbonate primer caps. In addition, the spin-crossover characteristics of [Fe(1-TAN)6](ClO4)2 were highlighted by the measurement of the temperature-dependent susceptibility curve.

N‐Azidoethyl azoles through N‐alkylation under highly harmonized reaction conditions: Synthesis, characterization, and complexation as energetic coordination compounds

AbstractOrganic azides are universally important in many areas of chemistry, particularly in organic synthesis. The availability of these azides often depends on specific transfer reagents and reaction conditions, or only work with certain substrates. Customizable transfer reagents offer a safe and direct pathway to desired compounds, thereby increasing the availability of N‐alkyl‐azides. In an effort to streamline the synthesis and broaden the scope of N‐azidoethyl‐containing molecules, three different versatile azidoethyl transfer reagents were synthesized and a uniform reaction protocol with azoles as substrates, including imidazole, pyrazole, 1,2,3‐triazole, 1,2,4‐triazole, and tetrazole was established. The resulting azidoethyl‐azoles were further used as ligands for energetic coordination compounds in an effort to create new lead‐free primary explosives. A comprehensive characterization of the transfer reagents, the azidoethyl‐containing products, and energetic coordination compounds was conducted using multinuclear nuclear magnetic resonance (NMR), elemental analysis, mass spectrometry, and infrared spectroscopy (IR). Furthermore, their thermal stability and sensitivity toward friction and impact were determined as well as the detonation properties were calculated by using the EXPLO5 code.

Sensitizing Explosives Through Molecular Doping.

Cocrystallization assembles multicomponent crystals in defined ratios that are held together by intermolecular interactions. While cocrystals have seen extensive use in the pharmaceutical industry for solving issues with stability and solubility, extension to the field of energetic materials for improved properties has proven difficult. Predicting successful coformers remains a challenge for systems lacking well-understood synthons that promote reliable intermolecular assembly. Herein, an alternative method is investigated for altering energetic properties that operates in the absence of well-defined interactions by molecular doping. An impact sensitive primary explosive, cyanuric triazide (CTA), was selected as the dopant to test if less impact sensitive secondary explosives could gain increased sensitization to impact when CTA is inserted into their crystal lattices. Molecular doping was successful in sensitizing three melt-castable energetics: 2,4,6-trinitrotoluene (TNT), 2,4-dinitroanisole (DNAN), and 1,3,3-trinitroazetidine (TNAZ). CTA could also be incorporated as a stabilized inclusion to sensitize DNAN further. These results demonstrate how the judicious choice of dopant can lead to specific property improvements, providing a method for creating energetic materials with new properties to access metal-free primary explosives and physical hot spot models for explosive ignition.

Effects of composition on the explosive properties of potassium chlorate and oils

Abstract Potassium chlorate has long been utilized as an excellent oxidizing agent in pyrotechnics and explosives. As mixtures of potassium chlorate and any type of combustible material can be explosive, there is a potential risk of misuse in homemade explosives. Unlike commercial explosives, homemade chlorate and oil mixtures do not have a constant composition, which limits their understanding. This study reports the effects of two types of oil (motor oil and cooking oil) and their ratios (ranging from 2.5% to 40.0% (w/w)) on the explosive properties of such mixtures. The impact sensitivity was highest at a motor oil ratio of 5%. The friction sensitivity increased with an increasing oil ratio, reaching a maximum at an oil ratio of around 22.5%, and was close to those of primary explosives. The motor oil mixtures exhibited higher sensitivity than the cooking oil mixtures at oil ratios of 25% or less. A 10% oil mixture, which was close to the ratio of oxygen balance equal to zero, detonated in weak confinement, such as a paper cylinder. The highest detonation velocities in a polypropylene tube were around 2300 and 2550 m/s at a 10% ratio of motor oil and cooking oil, respectively. The velocities of the metal case wall, measured by photonic Doppler velocimetry, reached about 1100 m/s near the end of acceleration. These results show that homemade chlorate and oil mixtures are capable of detonation and quite sensitive over a wide range of oil ratios, with sufficient power to cause damage in the vicinity.

Coordination nanosheets based molecular computing for detection and differentiation of high-energy explosives TATB and FOX-7

Detection and differentiation of explosives is an issue of immediacy for security and environmental monitoring. At present, the most operated explosive system combines primary and secondary explosives. Although various advances are presently equipped for identifying primary explosives, the insensitive nature of secondary explosives makes their detection and differentiation challenging. Here, we report three coordination nanosheets (CNs) AM-8-Eu, AM-8-Tb, and AM-8-Zn containing three-way terpyridine ligands (AM-8) and Eu(III), Tb(III), and Zn(II) ions. These CNs act as a highly selective platform for detecting unexplored high-energy explosive 1,1-Diamino-2,2-dinitro ethylene (FOX-7) in solid and solution phases. For AM-8-Zn, calculated molecular electrostatic surface potential revealed two modes of interactions for triaminotrinitrobenzene (TATB) and FOX-7, producing two distinct spectral responses. Digital analysis of these responses revealed a complimentary implication (IMP)/not implication (NIMP) logic function. Finally, the unique feature of IMP gate is used to define all possible sixteen distinct binary Boolean operations on two logic values for “functional completeness”. The detection and differentiation of such insensitive high-energy explosives TATB and FOX-7, where Boolean logic can process information through distinct binary responses in solid and solution phases, have not been witnessed hitherto in a single chemical platform.

Pushing the Limit of Oxygen Balance on a Benzofuroxan Framework: K2DNDP as an Extremely Dense and Thermally Stable Material as a Substitute for Lead Azide.

Because of environmental and health impacts, there is an ongoing necessity to develop sustainable primary explosives to replace existing lead-based analogues. Now we describe a potential primary explosive, dipotassium 4,6-dinitro-5,7-dioxidobenzo[c][1,2,5]oxadiazole 1-oxide (K2DNDP), which exhibits an excellent thermal stability (Tdec = 281 °C), positive oxygen balance (+4.79%), and a calculated crystal density of ρ = 2.274 g cm-3 at 100 K. Its physicochemical properties concomitantly with its straightforward synthesis make it a potential replacement for lead-based initiators.

Metal-Determined Explosive Characteristics of M(NO3)2(1-AT)x of Thermal and Laser Ignition (M2+ = Cr2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, and Zn2+; x = 2 or 3).

Optical and thermal ignition are two common pathways to initiate the explosion of primary explosives, where laser ignition is a more reliable and safer initiation method. Caused by the current-applied laser igniter with the wavelength of 1064 or 915 nm, the energetic complexes with strong absorption in the near-infrared (NIR) region are possibly applied as laser-ignited explosives. Recently, [Cu(NO3)2(1-AT)3] complex has been synthesized with excellent NIR absorption properties, where 1-amino-5H-tetrazole (1-AT) has been proved to be a promising laser-ignited energetic ligand. To confirm the structure-thermal/optical explosive characteristics, based on the structure of synthesized [Cu(NO3)2(1-AT)3], the commonly used transition-metal cations (M2+ = Cr2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, and Zn2+) have been selected to construct the series of complexes of M(NO3)2(1-AT)x (x = 2 or 3) theoretically. Car-Parrinello molecular dynamics (CPMD) method has been applied to unveil the role of center metals in the initiation and growth pathways. Time-dependent density functional theory (TD-DFT) method is used to explore their charge-transfer (CT) characteristics. The optical characteristic of the metal complex is mainly determined by the behaviors of the 3d electrons of center metals in excitation, where the activity of β-d electrons is an important factor to affect the NIR characteristic of complexes.

Exploring a Fused Triazole-Tetrazine Binary CN Material for a Promising Initiating Substance.

The pursuit of binary carbon-nitrogen (CN) materials with high density and good thermal stability presents a significant challenge due to the inherent trade-off between high-energy storage and low bond dissociation energy. In this study, we designed and synthesized (S)-1,2-bis(3-azido-1H-1,2,4-triazol-1-yl)diazene (BAzTD) and 2,9-diazidobis([1,2,4]-triazolo)[1,5-d:5',1'-f][1,2,3,4]tetrazine (DAzTT) through a straightforward reaction. Remarkably, DAzTT demonstrated a high density of 1.816 g·cm-3 (at 298 K) and a considerable thermal decomposition temperature of 216.86 °C. These properties outperform those of previously reported binary heterocyclic CN compounds and polyazido heterocyclic compounds. The quantum-chemical methods further substantiated the integral role of aromaticity as the driving force behind this difference. Additionally, the initiation capability of DAzTT was evaluated by a notably low minimum primary charge (MPC = 40 mg), surpassing conventional organic primary explosives, such as commercial 2-diazo-4,6-dinitrophenol (DDNP, MPC = 70 mg). The exceptional priming ability highlights the potential as an environmentally friendly replacement for toxic lead azide. DAzTT sets a new standard for binary CN compounds and provides a valuable precursor for high-nitrogen carbon nitride materials.

One step synthesis of nitrogen-rich green primary explosives from secondary explosives: synthesis, characterization, and performance study

Mono and di-azido group substituted TNBI-based metal free green primary explosives were synthesised. Newly made molecules show better detonation performance (7593–8494 m s−1; 21.3–30.0 GPa) than commonly used primary explosives – DDNP and Pb(N3)2.

N-Methylene-C bridged tetrazole and 1,2,4-triazole energetic salts as promising primary explosives

New energetic salts based on N-methylene-C bridged tetrazole and triazole were developed as safe primary explosives, which are free from heavy metal ions and azide groups and show high energy property, good stability, and reliable ignition ability.

Synthesis and protection: a controllable electrochemical approach to polypyrrole-coated copper azide with superior safety for MEMS.

Traditional lead-based primary explosives present challenges in application to micro-energetics-on-a-chip. It is highly desired but still remains challenging to design a primary explosive for the development of powerful yet safe energetic films. Copper-based azides (Cu(N3)2 or CuN3, CA) are expected to be ideal alternatives owing to their properties such as excellent device compatibility, excellent detonation performance, and low environmental pollution. However, the significantly high electrostatic sensitivity of CA limits its use in micro-electro-mechanical systems (MEMS). This study presents an in situ electrochemical approach to preparing and modifying a CA film with excellent electrostatic safety using a Cu chip. Herein, a CA film is prepared by employing Cu nanorod arrays as precursors. Next, polypyrrole (PPy) is directly coated on the surface of the CA materials to produce a CA@PPy composite energetic film using the electrochemical process. The results show that CuN3 is first generated and gradually oxidized to Cu(N3)2, essentially forming enclosed nest-like structures during electrochemical azidation. The microstructure and composition of the product can be regulated by varying the current density and reaction time, which leads to controllable heat output of the CA from 521 to 1948 J g-1. Notably, the composite energetic film exhibits excellent electrostatic sensitivity (2.69 mJ) owing to the excellent conductivity of PPy. Thus, this study offers novel ideas for the further advances of composite energetic materials and applications in MEMS explosive systems.