Synthesis and Characterization of 3,4-Bis[3(2-azidoethoxy)furazan-4-yl]furoxan (DAeTF): A Novel Low-Melting Insensitive Energetic Material.

The synthesis and characterization of low-melting-point insensitive energetic materials are crucial due to their increasing applications in melt-cast explosives. In this work, a furazan-derived energetic compound, 3,4-bis[3(2-azidoethoxy)furazan-4-yl]furoxan (DAeTF), exhibiting insensitive and high-energy characteristics, is rationally designed and synthesized. The structure of DAeTF is characterized by nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, elemental analysis, mass spectrometry, and single-crystal X-ray diffraction. The thermal properties of DAeTF are investigated using differential scanning calorimetry, in situ FTIR spectroscopy and thermogravimetric-differential scanning calorimetry-Fourier transform infrared-mass spectrometry and thermal decomposition mechanism was elucidated in combination with bond energy calculations. The detonation performance of DAeTF is predicted by the EXPLO5 program. The results indicate that DAeTF has thermal stability (Td = 251.7 °C), high energy level (D = 7270 m/s) and significant insensitivity (IS = 60 J). Additionally, its relatively low melting point (Tm = 60.5 °C) facilitates processing and loading. These characteristics indicate that DAeTF is a promising candidate as an insensitive melt-cast explosive in future applications.

Biochar applications for efficient removal of energetic compound contaminants.

Military activities and the production or disposal of ammunition often lead to soil contamination with energetic compounds (ECs) such as dinitrotoluene, trinitrotoluene, and hexogen, posing significant threats to human health and the ecosystem. Biochar has emerged as a cost-effective and widely available solution for remediating contaminated sites characterized by its capacity for pollutant removal through adsorption and conversion process, along with minimal secondary pollution. This paper provides a comprehensive review of relevant literature on biochar's efficacy in eliminating ECs, including an analysis of the underlying mechanisms. The discussion addresses challenges and opportunities associated with biochar application in ECs remediation, offering insights for future research directions. In summary, the use of biochar for ECs removal presents a promising and eco-friendly approach, facilitating the remediation of contaminated sites while promoting soil function and ecosystem recovery.

How contaminated is flatfish living near World Wars' munition dumping sites with energetic compounds?

Seas worldwide are threatened by an emerging source of pollution as millions of tons of warfare materials were dumped after the World Wars. As their metal shells are progressively corroding, energetic compounds (EC) leak out and distribute in the marine environment. EC are taken up by aquatic organisms and pose a threat to both the marine ecosphere and the human seafood consumer because of their toxicity and potential carcinogenicity. Here, sediment samples and fish from different locations in the German North Sea of Lower Saxony were examined to determine whether EC transfer to fish living close to munition dumping areas. EC were found in sediments with a maximum concentration of 1.5 ng/kg. All analyzed fish muscle tissues/fillets and bile samples were positive for EC detection. In bile, the max. EC concentrations ranged between 0.25 and 1.25 ng/mL. Interestingly, while detected TNT metabolites in the muscle tissues were in concentrations of max. 1 ng/g (dry weight), TNT itself was found in concentrations of up to 4 ng/g (dry weight). As we found considerable higher amounts of non-metabolized TNT in the fish muscle, rather than TNT metabolites, we conclude an additional absorption route of EC into fish other than per diet. This is the first study to detect EC in the edible parts of fish caught randomly in the North Sea.

Intramolecular Hydrogen Bonds Assisted Construction of Planar Tricyclic Structures for Insensitive and Highly Thermostable Energetic Materials.

Safety is fundamental for the practical development and application of energetic materials. Three tricyclic energetic compounds, namely, 1,3-di(1H-tetrazol-5-yl)-1H-1,2,4-triazol-5-amine (ATDT), 5'-nitro-3-(1H-tetrazol-5-yl)-2'H-[1,3'-bi(1,2,4-triazol)]-5-amine (ATNT), and 1-(3,4-dinitro-1H-pyrazol-5-yl)-3-(1H-tetrazol-5-yl)-1H-1,2,4-triazol-5-amine (ATDNP), were effectively synthesized through a simple two-step synthetic route. The introduction of intramolecular hydrogen bonds resulted in excellent molecular planarity for the three new compounds. Additionally, they exhibit regular crystal packing, leading to numerous intermolecular hydrogen bonds and π-π interactions. Benefiting from planar tricyclic structural features, ATDT, ATNT, and ATDNP are insensitive (IS > 60 J, FS = 360 N) when exposed to external stimuli. Furthermore, ATNT (Td = 361.1 °C) and ATDNP (Td = 317.0 °C) exhibit high decomposition temperatures and satisfying detonation performance. The intermolecular hydrogen bonding that produced this planar tricyclic molecular structure serves as a model for the creation of innovative multiple heterocycle energetic materials with excellent stability.

Ecotoxicological Risk of World War Relic Munitions in the Sea after Low- and High-Order Blast-in-Place Operations.

Submerged munitions from World War I and II are threatening human activities in the oceans, including fisheries and shipping or the construction of pipelines and offshore facilities. To avoid unforeseen explosions, remotely controlled "blast-in-place" (BiP) operations are a common practice worldwide. However, after underwater BiP detonations, the toxic and carcinogenic energetic compounds (ECs) will not completely combust but rather distribute within the marine ecosphere. To shed light on this question, two comparable World War II mines in Denmark's Sejerø Bay (Baltic Sea) were blown up by either low-order or high-order BiP operations by the Royal Danish Navy. Water and sediment samples were taken before and immediately after the respective BiP operation and analyzed for the presence of ECs with sensitive GC-MS/MS and LC-MS/MS technology. EC concentrations increased after high-order BiP detonations up to 353 ng/L and 175 µg/kg in water and sediment, respectively, while low-order BiP detonations resulted in EC water and sediment concentrations up to 1,000,000 ng/L (1 mg/L) and >10,000,000 µg/kg (>10 g/kg), respectively. Our studies provide unequivocal evidence that BiP operations in general lead to a significant increase of contamination of the marine environment and ecotoxicological risk with toxic ECs. Moreover, as compared to high-order BiP detonations, low-order BiP detonations resulted in a several 1000-fold higher burden on the marine environment.

Synthesis, Characterization, and Properties of High-Energy Fillers Derived from Nitroisobutylglycerol.

Herein we report a comprehensive laboratory synthesis of a series of energetic azidonitrate derivatives (ANDP, SMX, AMDNNM, NIBTN, NPN, 2-nitro-1,3-dinitro-oxypropane) starting from the readily available nitroisobutylglycerol. This simple protocol allows obtaining the high-energy additives from the available precursor in yields higher than those reported using safe and simple operations not presented in previous works. A detailed characterization of the physical, chemical, and energetic properties including impact sensitivity and thermal behavior of these species was performed for the systematic evaluation and comparison of the corresponding class of energetic compounds.

Enhanced Energetic Performance via the Combination of Furoxan and Oxa-[5,5]bicyclic Structures.

Three new compounds based on the combination of furoxan (1,2,5-oxadiazole N-oxide) and oxa-[5,5]bicyclic ring were synthesized. Among them, the nitro compound showed satisfactory detonation properties (Dv, 8565 m s-1; P, 31.9 GPa), which is comparable to the performance of RDX (a classic high-energy secondary explosive). Additionally, the introduction of the N-oxide moiety and oxidation of the amino group more effectively improved the oxygen balance and density (d, 1.81 g cm-3; OB%, +2.8%) of the compounds compared to furazan analogues. Combined with good density and oxygen balance as well as moderate sensitivity, this type of furoxan and oxa-[5,5]bicyclic structure will open up a platform for the synthesis and design of new high-energy materials.

Long-Term Trends for Blue Mussels from the German Environmental Specimen Bank Show First Evidence of Munition Contaminants Uptake.

Submerged munitions are present in marine waters across the globe. They contain energetic compounds (ECs), such as TNT and metabolites thereof, which are considered carcinogenic, exhibit toxic effects in marine organisms, and may affect human health. The aim of this study was to investigate the occurrence of ECs and their trends in blue mussels from the annual collections of the German Environmental Specimen Bank sampled over the last 30 years at three different locations along the coastline of the Baltic and North Sea. Samples were analyzed by GC-MS/MS for 1,3-dinitrobenzene (1,3-DNB), 2,4-dinitrotoluene (2,4-DNT), 2,4,6-trinitrotoluene (TNT), 2-amino-4,6-dinitrotoluene (2-ADNT), and 4-amino-2,6-dinitrotoluene (4-ADNT). The first signals indicating trace levels of 1,3-DNB were observed in samples from 1999 and 2000. ECs were also found below the limit of detection (LoD) in subsequent years. From 2012 onwards, signals just above the LoD were detected. The highest signal intensities of 2-ADNT and 4-ADNT, just below the LoQ (0.14 ng/g d.w. and 0.17 ng/g d.w., respectively), were measured in 2019 and 2020. This study clearly shows that corroding submerged munitions are gradually releasing ECs into the waters that can be detected in randomly sampled blue mussels, even though the concentrations measured are still in the non-quantifiable trace range.

Theoretical design of new insensitive high energy metal complexes based on the double fused-ring insensitive ligands strategy.

CONTEXT: In this work, 24 new nitrogen-rich fused-ring energetic metal complexes were designed based on the double fused-ring insensitive ligands strategy. First, 7-nitro-3-(1H-tetrazol-5-yl)-[1,2,4]triazolo[5,1-c][1,2,4]triazin-4-amine and 6-amino-3-(4H,8H-bis([1,2,5]oxadiazolo)[3,4-b:3',4'-e]pyrazin-4-yl)-1,2,4,5-tetrazine-1,5-dioxide were linked together by coordinating with metals cobalt and copper. Then, three energetic groups (NH2, NO2, and C(NO2)3) were introduced into the system to modify the structure and adjust the performance. Then, their structures and properties were investigated theoretically; the effects of different metals and small energetic groups were studied also. Finally, 9 compounds which have both higher energy and lower sensitivity than the famous high energy compound compound 1,3,5,7-tetranitro-1,3,5,7-tetrazocine were selected out. In addition, it was found that copper, NO2, and C(NO2)3 could increase the energy while cobalt and NH2 would be helpful for reducing the sensitivity. METHODS: Calculations were performed at the TPSS/6-31G(d) level by using the Gaussian 09 software.

Spatial-vertical variations of energetic compounds and microbial community response in soils from an ammunition demolition site in China.

Ammunition-related activities have caused severe energetic compound (EC) contamination and pose serious risks to ecosystems. However, little is known regarding the spatial-vertical variations of ECs or their migration in soils at ammunition demolition sites. Although the toxic effect of some ECs to microorganisms have been reported through laboratory simulations, the responses of indigenous microbial communities to ammunition demolition activities are unclear. In this study, the spatial-vertical variations of ECs in 117 topsoil samples and three soil profiles from a typical ammunition demolition site in China were studied. Heavy contamination of ECs was concentrated in the top soils of the work platforms, and ECs were also detected in the surrounding area and nearby farmland. ECs showed different migration characteristics in the 0-100 cm soil layer of the different soil profiles. Demolition activities and surface runoff play critical roles in the spatial-vertical variations and migration of ECs. These findings suggest that ECs are able to migrate from the topsoil to the subsoil and from the core demolition area to further ecosystems. The work platforms exhibited lower microbial diversity and different microbiota compositions compared to the surrounding areas and farmlands. Using the random forest analysis, pH and 1,3,5-trinitrobenzene (TNB) were characterized as the most important factors affecting microbial diversity. Network analysis revealed that Desulfosporosinus was highly sensitive to ECs and may be a unique indicator of EC contamination. These findings provide key information in understanding EC migration characteristics in soils and the potential threats to indigenous soil microorganisms in ammunition demolition sites.

Release of Ammunition-Related Compounds from a Dutch Marine Dump Site.

After World War II, large amounts of ammunition were dumped in surface waters worldwide, potentially releasing harmful and toxic compounds to the environment. To study their degradation, ammunition items dumped in the Eastern Scheldt in The Netherlands were surfaced. Severe damage due to corrosion and leak paths through the casings were observed, making the explosives in the ammunition accessible to sea water. Using novel techniques, the concentrations of ammunition-related compounds in the surrounding seabed and in the seawater were analyzed at 15 different locations. In the direct vicinity of ammunition, elevated concentrations of ammunition-related compounds (both metals and organic substances) were found. Concentrations of energetic compounds ranged from below the limit of detection (LoD) up to the low two-digit ng/L range in water samples, and from below the LoD up to the one-digit ng/g dry weight range in sediment samples. Concentrations of metals were found up to the low microgram/L range in water and up the low ng/g dry weight in sediment. However, even though the water and sediment samples were collected as close to the ammunition items as possible, the concentrations of these compounds were low and, as far as available, no quality standards or limits were exceeded. The presence of fouling, the low solubility of the energetic compounds, and dilution by the high local water current were concluded to be the main causes for the absence of high concentrations of ammunition-related compounds. As a conclusion, these new analytical methods should be applied to continuously monitor the Eastern Scheldt munitions dump site.

Variations of microbiota in three types of typical military contaminated sites: Diversities, structures, influence factors, and co-occurrence patterns.

Contamination with energetic compounds (ECs) is common in military sites and poses a great risk to the environment and human health. However, its effects on the soil bacterial communities remain unclear. This study assessed the variations of bacterial communities, co-occurrence patterns, and their influence factors in three types of typical military-contaminated sites (artillery range, military-industrial site, and ammunition destruction site). The results showed that the most polluted sites were ammunition destruction sites, followed by military-industrial sites, whereas pollution in the artillery ranges was minimal. The average concentrations of ECs including 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) in the study sites ranged 120-1.67 × 105, 20-7.20 × 104, and 180-2.38 × 105 µg/kg, respectively. Bacterial diversity and community structure in military-industrial and ammunition destruction sites were significantly changed, but not in artillery ranges. TNT, pH, and soil moisture are the critical factors affecting bacterial communities in contaminated military sites. Co-occurrence network analysis indicated that the pressure of ECs affected bacterial interactions and microbiota function. Our findings provide new insights into the variations in bacterial communities in EC-contaminated military sites and references for the bioremediation of ECs.

Synthetic Strategies Toward Nitrogen-Rich Energetic Compounds Via the Reaction Characteristics of Cyanofurazan/Furoxan.

The structural units of amino-/cyano-substituted furazans and furoxans played significant roles in the synthesis of nitrogen-rich energetic compounds. This account focused on the synthetic strategies toward nitrogen-rich energetic compounds through the transformations based on cyanofurazan/furoxan structures, including 3-amino-4-cyanofurazan, 4-amino-3-cyano furoxan, 3,4-dicyanofurazan, and 3,4-dicyanofuroxan. The synthetic strategies toward seven kinds of nitrogen-rich energetic compounds, such as azo (azoxy)-bridged, ether-bridged, methylene-bridged, hybrid furazan/furoxan-tetrazole-based, tandem furoxan-based, hybrid furazan-isofurazan-based, hybrid furoxan-isoxazole-based and fused framework-based energetic compounds were fully reviewed, with the corresponding reaction mechanisms toward the nitrogen-rich aromatic frameworks and examples of using the frameworks to create high energetic substances highlighted and discussed. The energetic properties of typical nitrogen-rich energetic compounds had also been compared and summarized.

Contamination characteristics of energetic compounds in soils of two different types of military demolition range in China.

The pollution of energetic compounds (ECs) in military ranges has become the focus of worldwide attention. However, few studies on the contamination of ECs at Chinese military ranges have been reported to date. In this study, two different types of military demolition range in China, Dunhua (DH) and Taiyuan (TY), were investigated and the ECs in their soils were determined. 10 ECs were detected at both ranges. While all the contamination characteristics were distinct, 2,4,6-trinitrotoluene (TNT) was the most abundant contamination source in soils at DH range, with an average concentration of 1106 mg kg-1 and a maximum concentration of 34,083 mg kg-1. Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and two mono-amino degradation products of TNT were also found to have high concentrations, with potential ecological and human health risks. In contrast, the concentrations of ECs in soils of TY range were much lower. The content of RDX was most significant, with average and maximum concentrations of 7.8 and 158 mg kg-1, respectively. However, the potential threat to human health of 2,4-dinitrotoluene and 2,6-dinitrotoluene in soils at both ranges should not be ignored. The differences in pollution characteristics of the ECs at DH and TY are closely related to the types and amounts of the munitions destroyed. Moreover, the spatial distribution of ECs at the demolition ranges was extremely heterogeneous, which may be attributed to the use of open burning / open detonation and the non-homogeneous composition of the munitions.

LC-MS analysis data of intermediate products used to construct photodegradation pathways for bis(1H-tetrazol-5-yl)amine (H2BTA).

The photolysis of bis(1H-tetrazol-5-yl)amine (H2BTA) in water was carried out in SolSim and Rayonet photochemical reactors equipped with solar simulating and ultraviolet lamps, respectively. The intermediary degradation products were monitored and tentatively identified by liquid chromatography - mass spectrometry (LC-MS). A quadrupole time-of-flight mass spectrometer (QTOF) was used to measure the mass-to-charge ratio (m/z) of the deprotonated molecular ions ([M - H]-) using electrospray ionization in negative mode (ESI-), thus making it possible to determine the number of C, H, N and O in the molecules. Four major degradation products, namely N-(1H-tetrazol-5-yl)formamide (T(5yl)FA), 1H-tetrazol-5-ylcarbamic acid (T(5yl)CA), N-(1H-tetrazol-5-yl)carbamohydrazonic acid (T(5yl)CHA) and 1H-tetrazol-5-amine (5-AT), have been identified after solar simulated and UV irradiation. This dataset is supplementary to the research paper "Photodegradation of bis(1H-tetrazol-5-yl)amine (H2BTA), a high nitrogen content tetrazole-based energetic compound in water" [1].

Hybrid chemometric approach for estimating the heat of detonation of aromatic energetic compounds.

This work presents an elegant technique for estimating the heat of detonation (HD) of thirty organic energetic compounds by combining support vector regression (SVR) and gravitational search algorithm (GSA). The work shows that numbers of nitrogen and oxygen atoms as well as the compound molar mass are sufficient as descriptors. On the basis of three performance measuring parameters, the hybrid GSA-SVR outperforms Mortimer and Kamlet (1968), Mohammad and Hamid (2004) and Mohammad (2006) models with performance improvement of 93.951%, 86.197%, and 47.104%, respectively. The superior performance demonstrated by the proposed method would be of immense significance in containing the potential damage of the explosives through quick estimation of HD of organic energetic compounds without loss of experimental precision.

Aromatic Nucleophilic Substitution of FOX-7: Synthesis and Properties of 1-Amino-1-Picrylamino-2,2-Dinitroethylene (APDE) and Its Potassium Salt [K(APDE)].

Two energetic compounds, 1-amino-1-picrylamino-2,2-dinitroethylene (APDE) and its potassium salt [K(APDE)] were synthesized through an aromatic nucleophilic substitution reaction between FOX-7 and picryl chloride. APDE and K(APDE) were characterized by elemental analysis, IR, NMR spectroscopy, and X-ray diffraction. APDE has a 3D wavy layered stacking structure similar to FOX-7. K(APDE) (peak temperature (Tip )=185.6 °C and impact sensitivity (IS)=19.6 J) presents better stability than APDE (tap =133.3 °C and IS=15.7 J). The reasons why the stability of APDE is lower than that of FOX-7 and picryl chloride are analyzed. The detonation velocity (D) and detonation pressure (P) of APDE (8.36 km s-1 and 31.3 Gpa) are close to those of FOX-7 and RDX. The thermal decomposition of K(APDE) is very violent, and its detonation performance (D=9.14 km s-1 and P=38.6 Gpa) is comparable to that of HMX, indicating that K(APDE) has good potential to be a high explosive.

Diffusion of energetic compounds through biological membrane: Application of classical MD and COSMOmic approximations.

Computational studies of the potential biological impact of several energetic compounds were performed. The most commonly used explosives were considered in the present studies: trinitrotoluene (TNT), 2,4-dinitrotoluene (2,4-DNT), 2,4-dinitroanisole (DNAN), and 5-Nitro-2,4-dihydro-3H-1,2,4-triazol-3-one (NTO). The effect of such factors as ionic strength and presence of DMSO in the water solution on the structure of the membrane were considered using the POPC lipid bilayer as an example. Molecular dynamics (MD) simulations revealed that, even on a short-time scale, the influence of those additives is noticeable, and therefore those factors should always be taken into account. The MD and the COSMOmic approaches were used to elucidate the ability of the energetic compounds to penetrate the living cell. Calculated free energy profiles and partitioning coefficients revealed distributions of the compounds in the lipid bilayer as well as an overall ability to enter the cell. MD in this case provides a better representation of the free energy profile, while the COSMOmic approach works better to predict log(Klipw) values. The effect of the functional group was observed for the profiles that were obtained using the MD method.

Pyrazole-Tetrazole Hybrid with Trinitromethyl, Fluorodinitromethyl, or (Difluoroamino)dinitromethyl Groups: High-Performance Energetic Materials.

High-nitrogen-content compounds have attracted great scientific interest and technological importance because of their unique energy content, and they find diverse applications in many fields of science and technology. Understanding of structure-property relationship trends and how to modify them is of paramount importance for their further improvement. Herein, the installation of oxygen-rich modules, C(NO2 )3 , C(NO2 )2 F, or C(NO2 )2 NF2 , into an endothermic framework, that is, the combination of a nitropyrazole unit and tetrazole ring, is used as a way to design novel energetic compounds. Density, oxygen balance, and enthalpy of formation are enhanced by the presence of these oxygen-containing units. The structures of all compounds were confirmed by XRD. For crystal packing analysis, it is proposed to use new criterion, ΔOED , that can serve as a measure of the tightness of molecular packing upon crystal formation. Overall, the materials show promising detonation and propulsion parameters.

Study on the computer-aided design of high energetic compounds based on the 1,2,3,4-tetrazine-1,3-dioxide frame.

In order to discover more potential high energy compounds, five computer-aided design methods were founded, and 20 high energetic compounds based on the 1,2,3,4-tetrazine-1,3-dioxide frame were designed. The first step of computer-aided design methods was to design new frame M. Three combination rules were invented, they were simple double-points rule, complicated double-points rule, and complicated multi-points rule. The second step of computer-aided design methods was to design 1,2,3,4-tetrazine 1,3-dioxides derivants by connecting M to 1,2,3,4-tetrazine-1,3-dioxides. Two combination rules were invented, they were simple single-points rule and double-points rule. All the structures are ring-fused or caged compounds including 1,2,3,4-tetrazine-1,3-dioxide. In these compounds, almost half of them have positive or zero oxygen balances, and the nitrogen contents of 17 compounds are over 40%. The densities and detonation velocities of all compounds are over 1.98 g cm-3 and 9500 m s-1 respectively. -N = N- group and -NO2 group have a major contribution to enthalpy of formation, detonation heat, and power index. -O- group and -ONO2 group have the main contribution to density, detonation velocity, and detonation pressure.