Nitrotriazolone Research Articles

Participation of Strong H-Bonding to Acidic Groups Contributes to the Intense Sorption of the Anionic Munition, Nitrotriazolone (NTO) to the Carbon, Filtrasorb 400

Participation of Strong H-Bonding to Acidic Groups Contributes to the Intense Sorption of the Anionic Munition, Nitrotriazolone (NTO) to the Carbon, Filtrasorb 400

Electrochemical determination of insensitive munition constituents 3‐nitro‐1,2,4‐triazol‐5‐one (NTO) using gold nanoparticle/carbon nanotube‐modified pencil graphite electrode in groundwater sample

AbstractFor the electrochemical detection of nitrotriazolone (NTO), multiwalled carbon nanotubes (MWCNT) and gold nanoparticles have been combined to generate nanocomposites. Electrochemical analysis and surface characterisation using scanning electron microscopy (SEM) and energy dispersive X‐ray (EDX) spectroscopy techniques were used to confirm the presence of gold nanoparticles on MWCNT. The electrochemical behavior of NTO at the modified pencil graphite electrode in the pH range of 2.0–10.0 (0.04 M Britton‐Robinson buffer solution) was evaluated using cyclic (CV) and differential pulse voltammetry (DPV).The suggested electrochemical sensor displayed a quick reaction to NTO with an optimal set of experimental parameters, a linear calibration curve spanning 30 to 1500 nM, and a detection limit of 22.6 nM. Using the differential pulse voltammetry technique, the usefulness of the MWCNT/AuNPs, and PGE for the determination of NTO in groundwater was evaluated.

Unraveling the Effect of MgAl/CuO Nanothermite on the Characteristics and Thermo-Catalytic Decomposition of Nanoenergetic Formulation Based on Nanostructured Nitrocellulose and Hydrazinium Nitro-Triazolone

The present study aims to develop new energetic composites containing nanostructured nitrocellulose (NNC) or nitrated cellulose (NC), hydrazinium nitro triazolone (HNTO), and MgAl-CuO nanothermite. The prepared energetic formulations (NC/HNTO/MgAl-CuO and NNC/HNTO/MgAl-CuO) were analyzed using various analytical techniques, such as Fourier-transform infrared (FTIR), scanning electron microscopy (SEM), thermogravimetry (TGA), and differential scanning calorimetry (DSC). The outstanding catalytic impact of MgAl-CuO on the thermal behavior of the developed energetic composites was elucidated by kinetic modeling, applied to the DSC data using isoconversional kinetic methods, for which a considerable drop in the activation energy was acquired for the prepared formulations, highlighting the catalytic influence of the introduced MgAl-CuO nanothermite. Overall, the obtained findings demonstrated that the newly elaborated NC/HNTO/MgAl-CuO and NNC/HNTO/MgAl-CuO composites could serve as promising candidates for application in the next generation of composite explosives and high-performance propellants.

Preparation and characterization of nano-CoNiCu ferrite for thermolysis of modified insensitive energetic material nitrotriazolone (NTO)

The present research aims to prepare transition metallic ferrite CoNiCuFe2O4 (CNCF) nanoparticles and its catalytic effects on thermal decomposition of 3-nitro-1,2,4-triazol-5-one or Nitrotriazolone (NTO) and nano-NTO studied by various physico-chemical characterization tools such as powder X-ray diffraction (PXRD), Raman spectroscopy (RS), UV–visible spectroscopy (UV–vis), and thermogravimetric analysis-differential scanning calorimetry-differential thermal analysis (TG-DSC-DTA). For a comparison purpose, the catalytic activity of NTO + CNCF and nNTO + CNCF mixtures was evaluated using thermal analysis with different heating rates and their kinetics were studied. The obtained results indicated that nNTO + CNCF exhibited lower decomposition temperature than the pure NTO, nNTO, and NTO + CNCF. Moreover, kinetic results show that the activation energy and the pre-exponential factor were considerably lowered in the presence of catalyst. Thus, the synthesized energetic compound and catalyst could be applied for the development of chemical propulsion formulations and their co-crystals.

Comparing the shock sensitivity of insensitive energetic materials

We present a tabletop method to study the shock sensitivity of plastic-bonded explosives that are considered shock insensitive using high dynamic range optical emission spectroscopy with laser-launched km/s flyer plate impacts (2, 3, and 4 km/s), which measures the spectral radiance (the emission spectrum vs a calibrated intensity standard) every 0.8 ns in the nanosecond and microsecond regimes. The explosives were TATB (1,3,5 trinitro, 2,4,6 triamino benzene), FOX-7 (1,1-diamino-2,2-dinitroethylene), LLM-105 (2,6-diamino-3,5-dinitropyrazine-1-oxide), and NTO (nitrotriazolone), all with 20% Sylgard 182 binder. Time resolving emission from shocked explosives produces a unique fingerprint at each shock pressure, and the emission temporal profile can be used to understand each material's shock response and the underlying mechanisms within the framework of the well-known shock ignition and growth models. Ignition was characterized by the emission intensity during nanosecond hot spot ignition. The growth process, which occurs after the shock has unloaded, was characterized by the time derivative of microsecond emission intensity. Singular-value decomposition was used to determine a characteristic spectral radiance over the entire time range, and this radiance was fit to a graybody model to determine a characteristic temperature Tc. Even though these insensitive explosives have similar shock sensitivities, our method can clearly distinguish their shock response. FOX-7 and NTO were the most sensitive, with FOX-7 having the greatest shock ignition sensitivity, growth rate, and Tc. LLM-105 was much less sensitive than FOX-7 and NTO, and TATB consistently showed the lowest sensitivity by any measure.

Effect of copper ferrite (CuFe2O4) in the thermal decomposition of modified nitrotriazolone

The reusable and easily separable nano-copper ferrite has been used to study its excellent catalytic behavior for thermolysis of modified nitrotriazolone (NTO), an insensitive energetic material act as an oxidizer for chemical propulsion systems.

Water molecules can significantly increase the explosive sensitivity of Nitrotriazolone (NTO) in storage and transport

Density functional theory studies are performed to take into account theeffecton thestabilities of the molecular structures and mechanisms of intermolecular proton transfer in isolated, mono- and dehydrate nitrotriazolone complexes. The geometries of the local minima and transition states were optimized without imposing symmetry restrictions by the gradient procedure at the DFT levels of theoreticalparameters and then were verified by natural bond orbital calculations. All values of total energies have been corrected for zero point energy contributions. The density functional theory predicts the height of the proton transfer barrier for mono- dehydrated nitrotriazolone complex to be approximately three and four times lower for the dehydrated nitrotriazolone and the keto-enol tautomer’s reactions respectively, compared with non-water assisted processes.

NTO Sensing by Fluorescence Quenching of a Pyoverdine Siderophore-A Mechanistic Approach.

In this study, a siderophore, pyoverdine (PVD), has been isolated from Pseudomonas sp. and used to develop a fluorescence quenching-based sensor for efficient detection of nitrotriazolone (NTO) in aqueous media, in contrast to other explosives such as research department explosive (RDX), picric acid, and trinitrotoulene (TNT). The siderophore PVD exhibited enhanced fluorescence quenching above 50% at 470 nm for a minimal concentration (38 nM) of NTO. The limit of detection estimated from interpolating the graph of fluorescence intensity (at 470 nm) versus NTO concentration is found to be 12 nM corresponding to 18% quenching. The time delay fluorescence spectroscopy of the PVD–NTO solution showed a negligible change of 0.09 ns between the minimum and maximum NTO concentrations. The in silico absorption at the emission peak of static fluorescence remains invariant upon the addition of NTO. The computational studies revealed the formation of inter- and intramolecular hydrogen-bonding interactions between the energetically stable complexes of PVD and NTO. Although the analysis of Stern–Volmer plots and computational studies imply that the quenching mechanism is a combination of both dynamic and static quenching, the latter is dominant over the earlier. The static quenching is attributed to ground-state complex formation, as supported by the computational analysis.

Photo degradation kinetics of insensitive munitions constituents nitroguanidine, nitrotriazolone, and dinitroanisole in natural waters

Herein the matrix effects on the kinetics of aqueous photolysis for the individual munitions constituents of IMX-101: nitroguanidine (NQ), dinitroanisole (DNAN), and nitrotriazolone (NTO) are reported along with the environmentally relevant kinetics and quantum yields. Photolysis potentially represents a major degradation pathway for these munitions in the environment and further understanding the complex matrices effects on photolytic kinetics was needed. Aqueous systems are of particular interest due to the high solubility of NQ (3,800 ppm) and NTO (16,642 ppm) compared to the traditional munitions trinitrotoluene (TNT, 100.5 ppm) and 1,3,5-trinitro-1,3,5-triazine (RDX, 59.9 ppm). Environmental half-lives (and quantum yields) were found to be 0.44 days (1.0×10-2), 0.83 days (3.2×10-4), and 4.4 days (5.9×10-5) for NQ, DNAN, and NTO, respectively, under natural sunlight. In laboratory experiments using nominally 300 nm bulbs in a merry-go-round style reactor in DI water the relative rate of photolysis for the three munitions constituents followed the same order NQ > DNAN > NTO, where DNAN and NTO reacted 57 and 115 times more slowly, respectively, than NQ. In the various environmentally relevant matrices tested in the laboratory experiments NQ was not significantly affected, DNAN showed a faster degradation with increasing ionic strength, and NTO showed a modest salinity and pH dependence on its rate of photolysis.

Comparative toxicogenomics of three insensitive munitions constituents 2,4-dinitroanisole, nitroguanidine and nitrotriazolone in the soil nematode Caenorhabditis elegans

BackgroundEcotoxicological studies on the insensitive munitions formulation IMX-101 and its components 2,4-dinitroanisole (DNAN), nitroguanidine (NQ) and nitrotriazolone (NTO) in various organisms showed that DNAN was the main contributor to the overall toxicity of IMX-101 and suggested that the three compounds acted independently. These results motivated this toxicogenomics study to discern toxicological mechanisms for these compounds at the molecular level.MethodsHere we used the soil nematode Caenorhabditis elegans, a well-characterized genomics model, as the test organism and a species-specific, transcriptome-wide 44 K-oligo probe microarray for gene expression analysis. In addition to the control treatment, C. elegans were exposed for 24 h to 6 concentrations of DNAN (1.95–62.5 ppm) or NQ (83–2667 ppm) or 5 concentrations of NTO (187–3000 ppm) with ten replicates per treatment. The nematodes were transferred to a clean environment after exposure. Reproduction endpoints (egg and larvae counts) were measured at three time points (i.e., 24-, 48- and 72-h). Gene expression profiling was performed immediately after 24-h exposure to each chemical at the lowest, medium and highest concentrations plus the control with four replicates per treatment.ResultsStatistical analyses indicated that chemical treatment did not significantly affect nematode reproduction but did induce 2175, 378, and 118 differentially expressed genes (DEGs) in NQ-, DNAN-, and NTO-treated nematodes, respectively. Bioinformatic analysis indicated that the three compounds shared both DEGs and DEG-mapped Reactome pathways. Gene set enrichment analysis further demonstrated that DNAN and NTO significantly altered 12 and 6 KEGG pathways, separately, with three pathways in common. NTO mainly affected carbohydrate, amino acid and xenobiotics metabolism while DNAN disrupted protein processing, ABC transporters and several signal transduction pathways. NQ-induced DEGs were mapped to a wide variety of metabolism, cell cycle, immune system and extracellular matrix organization pathways.ConclusionDespite the absence of significant effects on apical reproduction endpoints, DNAN, NTO and NQ caused significant alterations in gene expression and pathways at 1.95 ppm, 187 ppm and 83 ppm, respectively. This study provided supporting evidence that the three chemicals may exert independent toxicity by acting on distinct molecular targets and pathways.

Investigation into the environmental fate of the combined Insensitive High Explosive constituents 2,4-dinitroanisole (DNAN), 1-nitroguanidine (NQ) and nitrotriazolone (NTO) in soil

Contamination of military ranges by the use of explosives can lead to irreversible environmental damage, specifically to soil and groundwater. The fate and effects of traditional explosive residues are well understood, while less is known about the impact of Insensitive High Explosives (IHEs) that are currently being brought into military service. Current research has focussed on the investigation of individual constituents of IHE formulations, which may not be representative of real-world scenarios when explosive residues will be deposited together. Therefore, this study investigated the fate and transport of the combined IHE constituents 2,4-dinitroanisole (DNAN), 1-nitroguanidine (NQ) and 3-nitro-1,2,4-triazol-5-one (NTO) in two UK soil types.Static experiments ran for 9weeks to determine the fate of the combined explosive constituents in soil by monitoring the rate of degradation. Transport was examined by running soil column experiments for 5weeks, with a watering regime equivalent to the average yearly UK rainfall. Both static and soil column experiments confirmed that DNAN and NTO started to degrade within twenty-four hours in soil with high organic content, and were both completely degraded within sixty days. NQ was more stable, with 80% of the original material recovered after sixty days. The major degradation product of DNAN in the test soils was 2-amino-4-nitroanisole (2-ANAN), with trace amounts of 4-amino-2-nitroanisole. NTO was rapidly degraded in soil with high organic content, although no degradation products were identified. Results supported work from literature on the individual constituents DNAN, NQ and NTO suggesting that the three explosives in combination did not interact with each other when in soil. This study should provide a useful insight into the behaviour of three combined Insensitive High Explosive constituents for the predication of soil and water contamination during military training.

A two-stage extraction procedure for insensitive munition (IM) explosive compounds in soils

The Department of Defense (DoD) is developing a new category of insensitive munitions (IMs) that are more resistant to detonation or promulgation from external stimuli than traditional munition formulations. The new explosive constituent compounds are 2,4-dinitroanisole (DNAN), nitroguanidine (NQ), and nitrotriazolone (NTO). The production and use of IM formulations may result in interaction of IM component compounds with soil. The chemical properties of these IM compounds present unique challenges for extraction from environmental matrices such as soil. A two-stage extraction procedure was developed and tested using several soil types amended with known concentrations of IM compounds. This procedure incorporates both an acidified phase and an organic phase to account for the chemical properties of the IM compounds. The method detection limits (MDLs) for all IM compounds in all soil types were <5 mg/kg and met non-regulatory risk-based Regional Screening Level (RSL) criteria for soil proposed by the U.S. Army Public Health Center. At defined environmentally relevant concentrations, the average recovery of each IM compound in each soil type was consistent and greater than 85%. The two-stage extraction method decreased the influence of soil composition on IM compound recovery. UV analysis of NTO established an isosbestic point based on varied pH at a detection wavelength of 341 nm. The two-stage soil extraction method is equally effective for traditional munition compounds, a potentially important point when examining soils exposed to both traditional and insensitive munitions.

Fabrication of a nanostructured TiO2/carbon nanotube composite electrode for voltammetric and impedimetric determination of NTO explosive in the water and soil samples

ABSTRACTAn electrochemical oxidation route was developed for sensitive and selective assay of nitrotriazolone (NTO) explosive in some environmental samples on a multi-walled carbon nanotube (MWCNTs)/TiO2 nanocomposite paste electrode, for prevention of the analytical interference of conventional reducible energetic compounds. Detailed evaluations were made for the electrochemical behaviour of NTO on the modified electrode by adsorptive stripping voltammetry, electrochemical impedance spectroscopy (EIS) and chronoamperometry techniques in the pH range of 2.0–10.0. Parameters such as diffusion coefficient constant of NTO were calculated, and various experimental conditions were also optimised. Under optimal conditions the calibration curve had two linear dynamic ranges of 130.0–3251.5 μg L−1 and 6.5–26.0 mg L−1 with a detection limit of 26.0 μg L−1 (0.2 μmol L−1) and precision of <3%. This electrochemical sensor was further applied to determine NTO in real soil and water samples with satisfactory results.

Biotransformation of Explosives by Reticulitermes flavipes-Associated Termite Endosymbionts

Background/Aims: Termites have an important role in the carbon and nitrogen cycles despite their reputation as destructive pests. With the assistance of microbial endosymbionts, termites are responsible for the conversion of complex biopolymers into simple carbon substrates. Termites also rely on endosymbionts for fixing and recycling nitrogen. As a result, we hypothesize that termite bacterial endosymbionts are a novel source of metabolic pathways for the transformation of nitrogen-rich compounds like explosives. Methods: Explosives transformation capability of termite (Reticulitermes flavipes)-derived endosymbionts was determined in media containing the chemical constituents nitrotriazolone (NTO) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) that comprise new insensitive explosive formulations. Media dosed with 40 µg/ml of explosive was inoculated with surface-sterilized, macerated termites. Bacterial isolates capable of explosives transformation were characterized by 16S rRNA sequencing. Results: Termite-derived enrichment cultures demonstrated degradation activity towards the explosives NTO, RDX, as well as the legacy explosive 2,4,6-trinitrotoluene (TNT). Three isolates with high similarity to the Enterobacteriaceae(Enterobacter, Klebsiella) were able to transform TNT and NTO within 2 days, while isolates with high similarity to Serratia marcescens and Lactococcus lactis were able to transform RDX. Conclusion: Termite endosymbionts harbor a range of metabolic activities and possess unique abilities to transform nitrogen-rich explosives.

Estimations of Vapor Pressures by Thermogravimetric Analysis of the Insensitive Munitions IMX‐101, IMX‐104, and Individual Components

AbstractWe have calculated the vapor pressures of the new explosives ordnances IMX‐101 and IMX‐104 and their respective components, 2,4‐dinitroanisole (DNAN), nitroguanidine (NQ), nitrotriazolone (NTO), and hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX) by the method of rising temperature thermogravimetric analysis. Clausius‐Clapeyron relationships were assumed for each case and the vapor pressures were estimated from the Langmuir equation over an appropriate temperature range just below substance melting/decomposition points. For vapor pressures extrapolated to room temperature, the rank with respect to decreasing volatility was found to be: DNAN&gt;IMX‐104&gt;IMX‐101&gt;NQ&gt;RDX&gt;NTO. Interestingly, vapor pressure depression is observed in IMX formulations, where the formulation has a lower vapor pressure than its most volatile component, DNAN. The enthalpy of sublimation was determined for each substance and formulation from Clausius‐Clapeyron equations generated by analysis of the thermogravimetric data. The general trends in vapor pressures and sublimation enthalpies associated with the component materials were in good agreement with previous experimental and computational results. The results obtained by this study have importance for future investigations of IMX, specifically for chemical detection and assessment of environmental fate.

Electrochemical reduction of nitrotriazoles in aqueous media as an approach to the synthesis of new green energetic materials

The synthesis of new azo and azoxy compoundsvia electrochemical reduction of nitrotriazoles has been investigated in aqueous media, using nitrotriazolone (NTO) and nitrotriazole (NTr) as representative substrates. Reduction of NTO produces mainly solid azoxytriazolone (AZTO), with azotriazolone (azoTO) and aminotriazolone (ATO) as minor products, while 3-hydroxylaminotriazole is the major product formed from NTr. AZTO and azoTO are of interest as new green high-nitrogen compounds for use as insensitive high explosives (IHE). The effect of varying reaction conditions such as pH and substrate concentration has been evaluated, and a mechanism is proposed accounting for the experimental observations. In particular, the ratio of azoxy to azo in the solid product is influenced by pH and temperature, and the minor product ATO is formed not via direct reduction of NTO but via a novel thermal disproportionation reaction of the hydrazotriazolone intermediate. Conditions of high substrate concentration and low cell temperature maximise the azoxy yield and minimise the formation of minor products. Results indicate that this green electrosynthetic approach may be generally useful for the synthesis of new azoxy and azo triazoles from suitable substrates.

Electrochemical Method Applicable to Treatment of Wastewater from Nitrotriazolone Production

Laboratory studies show that electrochemical oxidation of acidic nitrotriazolone (NTO) solutions results in complete mineralization, with ammonium nitrate as the only solution product Other products (carbon dioxide, carbon monoxide, and nitrous oxide) are eliminated as gases from the working electrode. No additional chemical loading is required for the process, and electricity isthe only input The process maytherefore represent a cost-effective and environmentally friendly method of remediation for wastewater from NTO manufacture. Electrolyses were carried out at different applied voltages and at NTO concentrations of 0.01 and 0.05 mol/L, and the results indicate that a higher oxidation rate results in a greater charge passed per mole of NTO oxidized and increased production of nitrous oxide. Mechanisms are proposed on the basis of competing oxidative pathways that account for all products formed and the total charge passed during the reaction.

Electrochemical remediation produces a new high-nitrogen compound from NTO wastewaters

A new high-nitrogen molecule, identified as azoxytriazolone (AZTO), has been generated in high yield by electroreduction of acidic aqueous solutions of nitrotriazolone (NTO). The near-quantitative conversion appears to be driven by the low solubility of the product. AZTO precipitates readily, leaving the solution virtually free of organic material, and the process may therefore present an efficient and productive remediation method for wastewater from NTO manufacture. The chemical formula and molecular structure of AZTO indicate that it may be effective as an insensitive explosive.

A high-speed photographic study of the impact initiation of hexanitro-hexaaza-isowurtzitane and nitrotriazolone

A high-speed photographic study has been performed of the initiation mechanisms of hexanitro-hexaaza-isowurtzitane (CL-20) and nitrotriazolone (NTO) by drop-weight impact. CL-20 was found to be slightly more sensitive and NTO less sensitive than cyclotetramethylene tetranitramine (β-HMX) in our drop-weight apparatus. NTO was found to be sensitised by both hard-high-melting point grits (60 μm borosilicate or pyrex glass) and brittle polymers. Heat-sensitive film was used to confirm that the events seen using high-speed photography were indeed deflagration.

Low‐Sensitivity Explosive Compounds for Low Vulnerability Warheads

AbstractLooking for explosives for Low Vulnerability Ammunitions leads to an interest in explosive molecules less sensitive than the usual nitramines (RDX, HMX). If TATB is quite convenient in terms of sensitivity, its performance is too low.The researches described here are related to synthesis and use of NTO (nitrotriazolone), another insensitive molecule. The synthesis by nitration of TO (triazolone) is easy and the two steps from available starting materials have been optimized.A comparison of desensitivation of PBX either by TATB or by NTO have been made. The sensitivity levels were found equivalent while the detonation velocity of the NTO based PBX was slightly higher. Unfortunately in this case, the failure diameter would be larger.The last part relates to an extensive characterization in terms of performance and vulnerability to fast cook off, slow cook off, bullet impact, shock sensitivity and sympathetic detonation of a NTO and HMX based PBX. This PBX, B 2214, was one of the first examples of explosive composition showing no sympathetic detonation, even in 248 mm large diameter.