Search

Cocrystallization is a promising method for generating new energetic materials with improved performances. Herein, a novel energetic cocrystal composed of 1H-tetrazole/sodium perchlorate was prepared using the solvent evaporation method. This cocrystal is characterized as containing organic azole derivatives and an ionic perchlorate salt, which is used as an oxidizer in pyrotechnics. The crystal structure was determined via single-crystal X-ray diffraction. The as-prepared crystal exhibited a lamellar structure consisting of 1H-tetrazole and sodium perchlorate layers. A molecular structure comparison between the cocrystal and pristine ingredients revealed variations in the bond lengths and angles owing to the cocrystallization. The hydrogen bond formed by adjacent tetrazole rings was strengthened. The 1H-tetrazole/sodium perchlorate cocrystal was structurally compared with crystals previously reported to the Cambridge Structural Database including sodium perchlorate in lamellar structures. The lamellar structure of the cocrystal exhibited weak layer-to-layer interactions compared with those of the other crystals. Fourier transform infrared and Raman spectroscopy analyses were conducted, and the relationship between the spectroscopy results and the crystal/molecular structure are discussed. The results of the spectroscopic analyses exhibited peak shifts that indicate structural changes in bond lengths and angles owing to the cocrystallization.

The molecular and crystal structure of 1H-1,2,4-triazolium perchlorate, C2H4N3 +·ClO4 −, was determined as detailed crystallographic data had not been available previously. The structure has monoclinic (P21/m) symmetry. It is of interest in the field of energetic compounds because nitrogen-rich azoles are the backbone of high-density energetic compounds, and salt-based energetic materials can exhibit preferential energy-release behaviour. The bond angles of the 1,2,4-triazolium cation in this study were similar to those of a cationic triazole ring reported previously and were different from those of the neutral triazole ring. This study contributes to the available data that can be used to analyse the relationship between the structures and properties of energetic materials.

In this work, we investigated the thermal oxidation of methyl tert-butyl ether (MTBE) using a customer-designed mini-closed-pressure vessel test and quantitatively analyzed the hydroperoxides produ...

Pyrotechnic compositions containing magnesium (Mg) powder face the problem of degradation by moisture. Although potassium dichromate is an effective stabilizer that avoids Mg degradation, it is detrimental for human health and environment. This study is aimed at developing a harmless stabilizer for Mg in pyrotechnics. We investigated the effect of magnesium stearate (MgSt) coating on stabilization and combustion properties of the coated Mg. The stabilization effect of MgSt coating was measured by aging test of ammonium perchlorate (AP) and Mg mixture (AP/Mg). The aging test revealed that MgSt coating reduced the generation of degradation product, Mg(OH)2. Results of burning test showed that MgSt has little effect on flame color, while it considerably decreased the burning rate. The influence of MgSt coating was lower than that of MgSt that was simply mixed with AP/Mg., This is the pre-peer reviewed version of the following article: Y. Nishiwaki, T. Matsunaga, M. Kumasaki, Prop., Explos., Pyrotech. 2019, 44, 1028., which has been published in final form at [https://doi.org/10.1002/prep.201800372]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.

Magnesium powder is a common fuel in the field of pyrotechnics. The metal corrodes easily under wet conditions. This can lead to problems such as spontaneous ignition and deterioration of combustion performance when the powder is used in humid areas. For pyrotechnic compositions containing magnesium, harmful stabilizers are often used. In this study, we researched a less harmful replacement for the stabilizer and selected linseed oil, which is used as cooking oil. Experiments were conducted to examine linseed oil’s stabilization effects against magnesium corrosion when it is in contact with an oxidizer under humid conditions by coating magnesium powder and soaking it in aqueous oxidizer solutions. The oxidation of linseed oil led to its polymerization, because of which the stabilizing effect of linseed oil was lost. Stearic acid, which is a saturated fatty acid, was also examined for its stabilizing effects. Melted stearic acid was mixed with magnesium, and coating of stearic acid on magnesium particles was confirmed. The effect of stearic acid coating is more prominent than that of simple mixing of stearic acid with Mg. The stabilization effect of linseed oil and stearic acid coating shows that unharmful organic stabilizers can also be used in pyrotechnic compositions containing Mg., This is a post-peer-review, pre-copyedit version of an article published in "Journal of Thermal Analysis and Calorimetry". The final authenticated version is available online at: http://dx.doi.org/10.1007/s10973-019-08069-z

Due to recent climate change, highly-connected society, and the centralization of hazardous materials, Natech is a matter of the growing concern. As Natech disasters occur with low frequency, those in charge of facilities should learn lessons from past cases to prepare for situations in the future in which they may have to respond to a potentially catastrophic event for the first time. This paper describes three Natech cases triggered by the heavy rainfall in Japan in 2018. One resulted in violent explosions, one showed consequences half a year later, and the other managed to avoid a catastrophic situation by preparation based on prior analysis of possible damage. The lessons which can be learnt are as follows: Undertake measures based on the hazardous conditions of materials and possible reactions; Avoid normalcy bias for improved decision-making; Identify slow developing and lagging Natech consequences; Prepare and intensify safeguards to avoid possible damage based on risk analysis; Consider employees’ safety in returning to their homes; Collect micro information and aggregate it; Provide current information about the situation to stakeholders; Plan resources required for recovery activities.

Manga are graphic novels that are considered to have the potential to effectively convey concepts and engage readers. The efficacy of manga has been validated for chemical safety education to students in three universities in Japan, Taiwan, and Thailand. Students were asked to examine a photo to identify hazards and hazardous behaviors that can potentially lead to accidents before and after reading a manga that explains the risk of fires and explosions. The identified hazards/hazardous behaviors were classified into seven categories, and the average number of hazards/hazardous behaviors was determined in each category. The differences before and after the lesson were analyzed to evaluate the effectiveness of manga as an educational tool. In the students’ answers, in all three of the universities, some common features were observed: Subjects easily identified certain hazardous conditions in the photo, particularly noting deficient or unsuitable personal protective equipment. The hazards/hazardous behaviors...

The potentially explosive reaction of hydrogen peroxide (H2O2) and copper chloride (CuCl2) was investigated. Pressure tests revealed that the reaction was strongly temperature - dependent and can easily undergo runaway reaction. Nevertheless, there was only a slight pressure increase at the low temperatures studied or when using low concentrations of CuCl2. Under the conditions generating the slight pressure increase, hypochlorite anions (ClO−) are generated and the acidity increases. As the reaction reaches completion, ClO− disappears, and the acidity decreases. Interestingly, the addition of phosphate buffer to maintain the weakly acid conditions led to a runaway reaction, and the use of basic ClO− promoted the exothermic reaction. Based on the results, acidity has a strong impact on the reaction behaviour.

There has been considerable evidence that natural disasters can be threats to technological systems and when these threats are concomitant, they pose tremendous risks to countries and communities. Such risk (termed Natech risk) should be incorporated early in the design process, particularly in land-use planning of sites. In this study, a descriptive classification of Natech risk sources was developed, mainly from analysis of a Japanese database, to contribute to preliminary analysis of Natech risk. Analysis of the information gathered, resulted in a classification including fifteen physical effects and six physical impacts that cause technical disorder. Here, the pertinent aspects of natural hazards were termed physical effects, and the phenomena caused by physical effects were termed physical impacts: the primary observable consequences and influences on the functions of technological systems. The classification is expected to be helpful for Natech risk identification, by providing guidewords useful for risk assessment and management.

1-pentyne and 2-hexyne were assessed as replacements for sulphur-bearing odorants in fuel gases, particularly in the view of thermal risks associated with the storage of sulphur-bearing odorants. Both the alkynes were inactive when heated under pressurised nitrogen, but their exothermic behaviour and pressure profiles were found to change when heated in contact with pressurised air. The pressure profiles were considered based on the consumption of oxygen. The exothermic behaviours of 1-pentyne and 2-hexyne were compared both before and after the storage process using differential scanning calorimetry. While both species showed two exothermic peaks before storage, the thermal and pressure load applied during the storage process increased the heat released at low temperatures. Storage under pressurised air influenced the stability of the both the species as well as their exothermic behaviour. The results will help in the use of these odorants and safe handling of fuels containing them.

Energetic material mixtures can be considered as the blends of fuel and oxidizing agents that release energy during redox reactions; therefore, the relationship between their thermal sensitivity and the electrostatic interactions between the electron donor (reductant) and electron acceptor (oxidant) in such mixtures was investigated as an indicator to enable prediction of the thermal sensitivity. The donor–acceptor interactions were evaluated for the mixtures of triazole derivatives and dinitrobenzene by assessing the differences between the ionization energy of the donor and the electron affinity of the acceptor to quantify the magnitudes of the interactions. The ionization energy was experimentally determined by using photoemission yield spectroscopy in air, which determines the photoemission yield as a function of the energy of the ultraviolet irradiation, and theoretically determined using molecular orbital calculations. The thermal sensitivities of the mixtures were evaluated using differential scanning calorimetry. The thermal sensitivities of the mixtures increased as the difference between the ionization energy of the donor and electron affinity of the acceptor increased. A good correlation between the thermal sensitivity and this difference was observed, particularly in the experimental data. The magnitude of the donor–acceptor interactions may thus serve as a potential indicator of the thermal sensitivities of energetic material mixtures.

In order to contribute to the development of risk assessment, cascading natural disasters which are sequences of natural hazards was studied, and the patterns of the interactions between natural disasters were investigated. The data were collected from the database of Japanese newspaper. The relationships between each natural hazard were emerged and divided into four modes: striking, undermining, compounding, and blocking modes. Striking mode means a primary disaster provides sufficient energy to move a significant mass or to propagate the energy through media. In undermining mode, a primary disaster lowers the resistance or weakens a system maintaining mass and causes to collapse. Compounding mode of the linkage shows that a primary disaster reduces the strength of a system. Its difference from undermining mode is that this mode adds to the amount of mass affected. Blocking mode is found in an event blocking steady flows. The results are important for understanding of the impact of these types of cascading natural disaster and so are valuable as a basis for the identification, description, and development of countermeasures.

The influence of a degraded solvent on Grignard reagent formation was investigated in terms of heat release behaviour. Since degraded solvent is supposed to contain peroxide by oxidation with air as well as water from atmosphere, peroxide in this study was intentionally produced by the storage of tetrahydrofuran in a pressurized oxygen atmosphere and the induction periods were measured. The induction period which appears prior to the main exothermic reaction increased with increasing amounts of peroxide and water content, respectively. However, there was a difference in heat release behaviour; the reaction including peroxide showed a delay in the heat release and two exothermic peaks, while the solvent that included water simply showed a delay in the start of the reaction. γ-Butyrolactone was found to be a product derived from peroxide, by component analysis of the oxidized solvent. γ-Butyrolactone caused an induction period when it was added to the solvent. This work suggests a deteriorated solvent can lead to inappropriate handling which cause a runaway reaction and gives insight to the chemical industry that manages the risk of potentially hazardous chemical reactions.

The electrostatic interactions between gas generating agent and organic electron withdrawing additives were studied to understand how the interaction affects the reactions of their thermal behavior. To explore the electronic interaction and its effect, the thermal behavior of a mixture of dinitrobenzene isomers [p-dinitrobenzene (pDNB) and m-dinitrobenzene (mDNB)] and 1, 2,4-triazole (TA) was analyzed. Density functional calculations and electron density analysis proved that both pDNB and mDNB in a 1:1 ratio withdraw electrons from TA. The analysis of pyrolysis behavior showed that TA and dinitrobenzene mixtures (TA/pDNB or TA/mDNB) react at lower temperatures than each precursor. Gas chromatography mass analysis and UV/Vis spectroscopy showed reasonable results that suggested that pDNB and TA make condensed products in the initial stage of the reaction according to the differential scanning calorimetry measurement. When the mixtures were ignited under pressurized conditions, TA/pDNB burned easily while TA/mDNB burned only partially. These results suggested that the interaction between triazole and dinitrobenzene affects the pyrolysis and combustion behavior of a TA/dinitrobenzene mixture.

Factors that affect the induction period of Grignard reagent formation, which involves heterogeneous reaction between magnesium metal (Mg) and an alkyl halide in ether solvent, has been clarified to achieve safer and more efficient operation in chemical processes. The influence of the Mg surface, especially the effects of carbonate, hydroxide, and oxide layers on the induction period were investigated by measuring the exothermic behavior of Grignard reagent formation by a differential reaction calorimeter. Mg powder was kept in water bubbled with CO2 or N2 gas to form a coating on the Mg surface. The calorimetry results for the reaction indicated that both treatments increased the induction period. Thermogravimetric analysis-mass spectrometry was conducted to identify the chemical species and quantify the amount of surface material on the Mg particles. It was found that basic magnesium carbonate and magnesium hydroxide were formed on Mg exposed to CO2 and N2, respectively. Subsequent heating the carbonate- or hydroxide-coated Mg at 500 °C caused a MgO layer to form on the surface, which was found to dramatically reduce the induction period.

The objective of this study is to obtain information about the thermal decomposition behaviors of hydrazine (N 2 H 4 ) caused by metals, using differential scanning calorimeter (DSC) and SuperCRC. The DSC measurements revealed that the exothermic reactions of N 2 H 4 were caused by the reaction conditions such as the type of cells; the T DSC with a gold pan is 485.2 K and that with a glass capillary is 620.5 K. Besides, the activation energy of the thermal decomposition of N 2 H 4 , calculated from the Kissinger and Ozawa methods, were found to be about 38±2 kJ mol −1 in the gold pan and 141±8 kJ mol −1 in the glass capillary. Moreover, a heat flow profile was observed with SuperCRC during the mixing of N 2 H 4 and the metal ion solution at 298 K. The maximum heat flow was related to the metal ion oxidative characters. The higher oxidative characters would provide a faster acceleration for the exothermic behavior than the lower oxidative ions. Based on this study, Mn(VII) and Cr(VI) were considered to exhibit strongly oxidative characteristics during mixing with N 2 H 4 .

On the Metropolitan Expressway in Tokyo, a tank car exploded because it was carrying hydrogen peroxide (H2O2) in a compartment in which copper chloride (CuCl2) remained. Although the main cause of the accident was trivial, the background on the accident suggested that an induction period in the reaction led to a mistake. This report describes the experimental investigation of the catalytic ability of CuCl2, and comparing it with two other copper(II) compounds (nitrate: Cu(NO3)2; and copper sulfate: CuSO4) and three iron(III) compounds (chloride: FeCl3; nitrate: Fe(NO3)3; and sulfate: Fe2(SO4)3). The experiments were performed using a reaction calorimeter. During the experiments at 35 °C, 2×10−5 mol of copper compounds slowly reacted with H2O2 and generated a precipitate. The iron compounds allowed the hydrogen peroxide to violently decompose. A 1×10−4 mol solution of CuCl2, however, produced a violent decomposition at 35 °C. At 15 °C, a moderate heat release occurred. Based on these results, the concentration and temperature dependence of the catalytic ability of CuCl2 were postulated to contribute to the induction period observed in the accident.

The spontaneous ignition mechanism of three types of smokeless powders such as cellulose nitrate/potassium sulfate (SB), cellulose nitrate/glycerin trinitrate/potassium sulfate (DB), and cellulose nitrate/glycerin trinitrate/nitroguanidine/potassium sulfate (TB) were analyzed in terms of the thermal behavior and the pressure change during the isothermal storage at 393 K in various gases. The heat release of SB and DB was suppressed in the atmosphere without O 2 and even in 4.5 vol.% NO 2 /N 2 . However, in 4.7 vol.% NO 2 /air, the exothermic reaction was accelerated compared to that in dry air. In addition, the total pressure decreased during the storage in the presence of O 2 . This nature of the behavior of SB and DB indicated that autoxidation, which was propagation with O 2 and radical species derived from NC, was involved in the exothermic reaction. And, NO 2 contributed not to the autoxidation but to the initiation process before the autoxidation occurred. On the other hand, the exothermic reaction of TB might be different from that of SB and DB because TB released the reaction heat in no O 2 atmosphere such as 4.5 vol.% NO 2 /N 2 . TB would react with NO 2 without O 2 and release the reaction heat when NO 2 was excessively present in the system. This specific nature would be due to the presence of 50 wt.% of nitroguanidine which was not nitric ester.

The objective of this study is to obtain information on the calorimetric behaviors of aqueous solutions of hydroxylamine (HA), hydroxylamine chloride (HACl), and hydroxylamine nitrate(HAN) caused by different Fe(III) states (free Fe(III) from Fe(NH 4 )(SO 4 ) 2 , Fe(CN) 6 3− , and Fe(EDTA) − ). The calorimetric data were obtained with a small-scaled reaction calorimeter, Super-CRC. In the mixing with Fe(III), HA showed the highest reactivity among three substrates. Free Fe(III) and Fe(EDTA) − showed catalytic effects in the reactions. In the overall heat of reactions, Fe(EDTA) − exceeded free Fe(III), which precipitated as Fe(OH) 3 and decreased the chances of interactions with HA. It was suggested that the generation of NH 3 had taken place in the process of reducing HA along with Fe(II) oxidation. Fe(CN) 6 3− was less reactive than free Fe(III) and Fe(EDTA) − . The ability of masking Fe(III) was estimated for CyDTA. The HA including CyDTA had no exothermic peak; however, there was an endothermic peak of the heat flow at Fe(III) injection. CyDTA was found to have the ability to inhibit a violent exothermic reaction of HA.

Novel monoanionic nickel and dianionic copper complexes with the extended TTF dithiolato ligand, propylenedithiotetrathiafulvalenedithiolate [ptdt2–=(S8C9H6)2– ], have been synthesized. Characterization of monoanionic tetraphenylphosphonium and tetramethylammonium salts of Ni(ptdt)2– and the dianionic tetraphenylphosphonium salt of Cu(ptdt)22– have been performed, using cyclic voltammetry, electrical resistivity measurements, magnetic susceptibility measurements and X-ray crystal structure determination. The geometries around the Ni atoms are almost square planar. In both Ni complexes, one of the extended ligands of Ni(ptdt)2– is overlapping with that of the adjacent anion separated by about half of the unit of the molecule, forming a one-dimensional chain. The adjacent chains are connected by transverse short S‥S contacts. Cu(ptdt)22– has a distorted tetrahedral geometry around the Cu atom and the dihedral angle between the planes of the dithiolato ligand is 54.2 °. The crystal structures of Ni(ptdt)2– and Cu(ptdt)22– complexes show the possibility of novel 2D or 3D intermolecular contacts through ptdt ligands. The complex [Me4N][Ni(ptdt)2 ]·Me2CO is a semiconductor with a room temperature conductivity of 1.4×10–3 S cm–1 and activation energy of 9.9×10–2 eV.

The structure of the title compound, C2H4N4O, was determined and found to be almost planar, excluding H atoms. The N—N bond lengths of 1.130 (2) and 1.231 (2) Å in the azide group exhibited a resonance effect and the characteristic organic azide structure.

Hydroxylamine (HA), hydroxylamine chloride (HACl), and hydroxylamine nitrate (HAN) were each mixed with aqueous solutions of Cr 3+ , Cr 6+ , Mn 7+ , Co 2+ , Co 3+ , and Cu 2+ , and their heat flow profiles were monitored by a small-scaled reaction calorimeter, SuperCRC. These mixing tests demonstrated that HA was less reactive than HACl and HAN with Mn 7+ and Cr 6+ . Their UV-vis spectra confirmed that the substrates reacted when Mn 7+ and Cr 6+ were reduced. HA was more reactive with Cu 2+ than HACl and HAN and exhibited the highest reactivity among the three substrates with regard to metals in the intermediate oxidation states: Cr 3+ , Co 3+ , and Co 2+ . During the reaction of HA and Co 3+ , an induction period was observed. All exothermic reactions were accompanied by precipitation or a change in the UV-vis spectra.

Novel monoanionic, dianionic and neutral nickel, copper and palladium complexes with the extended TTF dithiolato ligand, propylenedithiotetrathiafulvalenedithiolate[ptdt 2− =(S 8 C 9 H 6 ) 2− ], have been synthesized. The crystal structures of these complexes show the possibility of the electronic band formation by novel 2D or 3D intermolecular contacts through ptdt ligands. The single crystal of Ni(ptdt) 2 revealed an extremely high electrical conductivity(7 S cm −1 ) at room temperature as a neutral molecular crystal.