Too fast and too furious: thermoanalytical and quantum chemical study of the thermal stability of 4,4'-dinitro-3,3'-diazenofuroxan.

Novel energetic materials (EM) often combine two intrinsically counter trends, , a high energy density and mediocre safety parameters, like thermal stability and sensitivity toward mechanical stimuli. A rational design of promising EMs requires a proper understanding of their thermal stability at both macroscopic and molecular levels. In the present contribution, we studied in detail the thermal stability of 4,4'-dinitro-3,3'-diazenofuroxan (DDF), an ultrahigh-performance energetic material with a reliable experimental detonation velocity being very close to 10 km s.

First Alliance of Pyrazole and Furoxan Leading to High-Performance Energetic Materials.

Nitrogen heterocyclic scaffolds retain their leading position as valuable building blocks in material science, particularly for the design of small-molecule energetic materials. However, the search for more balanced combinations of directly linked heterocyclic cores is far from being exhausted and aims to reach ideally balanced high-energy substances. Herein, we present the synthetic route to novel pyrazole-furoxan framework enriched with nitro groups and demonstrate a promising set of properties, viz.

Energetic Methylene-Bridged Furoxan-Triazole/Tetrazole Hybrids.

Design and synthesis of new energetic materials retains its urgency in chemistry and materials science. Herein, rational construction and regioselective synthesis of a series of energetic compounds comprising of a methylene-bridged combination of 1,2,5-oxadiazole and nitrogen-rich azoles (1,2,4-triazole and tetrazole) enriched with additional explosophoric functionalities (nitro and azo moieties) is presented. All target materials were thoroughly characterized using IR and multinuclear NMR (H, C, N, N) NMR spectroscopy, high-resolution mass spectrometry, X-ray diffraction, and differential scanning calorimetry.

Highly energetic -cyano-substituted CL-20 analogues: challenging the stability limits of polynitro hexaazaisowurtzitanes.

To design high-energy-density materials of a new level, it is necessary to develop methods for the functionalization of energetic scaffolds, which will make it possible to tune their physicochemical and energetic properties. For this reason, we have elaborated an approach for synthesizing a new series of energetic cage compounds with advanced properties by introducing the -cyano group into the polynitro hexaazaisowurtzitane framework. The structures of the obtained substances were fully characterized with a combination of methods, including multinuclear (H, C{H}, N, and N{H}) NMR and IR spectroscopy, high-resolution mass spectrometry, X-ray diffraction analysis, electron microscopy and quantum chemical calculations.

New Mechanistic Insights into the Primary Thermolysis Reactions of 1,3,4,6-Tetranitrooctahydroimidazo-[4,5-]imidazole (BCHMX) from Predictive Local Coupled Cluster Calculations.

Theoretical studies of the decomposition mechanism of energetic materials quite often scrutinize only the primary thermolysis reactions. However, the secondary reactions are crucial, inter alia, for proper building of the combustion models and understanding the autocatalytic processes. In the present study, we applied predictive DLPNO-CCSD(T) calculations to elucidate the kinetics and decomposition mechanism of a novel promising energetic material, 1,3,4,6-tetranitrooctahydroimidazo [4,5-] imidazole (BCHMX).

Can the Sublimation Enthalpy Be Obtained Using Atomic Force Microscopy with Heating? A PETN Nanofilm Case.

Vaporization is an important aspect of the performance and detection of energetic materials. While the traditional techniques concentrate on bulk property changes during sublimation, atomic force microscopy (AFM) offers the possibility to track particle volume changes under heating. Ideally, this will enable the investigation of chemicals that are challenging to study using conventional vaporization analysis methods, i.

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.

First Example of 1,2,5-Oxadiazole-Based Hypergolic Ionic Liquids: A New Class of Potential Energetic Fuels.

The development of liquid energetic fuels with improved properties is an important topic in space propulsion technologies. In this manuscript, a series of energetic ionic liquids incorporating a 1,2,5-oxadiazole ring and nitrate, dicyanamide or dinitramide anion was synthesized and their physicochemical properties were evaluated. The synthesized compounds were fully characterized and were found to have good thermal stabilities (up to 219 °C) and experimental densities (1.

Anions Containing Tripoid Conjugated N System: Salts of 5-(Substituted Amino)-[1,2,3]triazolo[4,5-][1,2,5]oxadiazol-5-ium-4-ides, as well as Their Synthesis, Structure, and Thermal Stability.

A strategy for the synthesis of 5-((2-cyanoethyl)-X-amino)-[1,2,3]triazolo[4,5-][1,2,5]oxadiazol-5-ium-4-ides (X = H; CHCHCN; NO (); CN (); COEt ()) starting from 3-amino-4-azido-1,2,5-oxadiazole was developed. The key step in this strategy is the intramolecular thermolytic cyclization of the azido group and the bis(2-cyanoethyl)triazene group. Removal of the 2-cyanoethyl protecting group from amides - gave potassium salt of the corresponding nitramide and sodium salts of cyano- and ethoxycarbonylamide.

Novel family of nitrogen-rich energetic (1,2,4-triazolyl) furoxan salts with balanced performance.

Nitrogen-rich energetic materials comprised of a combination of several heterocyclic subunits retain their leading position in the field of materials science. In this regard, a preparation of novel high-energy materials with balanced set of physicochemical properties is highly desired. Herein, we report the synthesis of a new series of energetic salts incorporating a (1,2,4-triazolyl) furoxan core and complete evaluation of their energetic properties.

An Alliance of Polynitrogen Heterocycles: Novel Energetic Tetrazinedioxide-Hydroxytetrazole-Based Materials.

Energetic materials constitute one of the most important subtypes of functional materials used for various applications. A promising approach for the construction of novel thermally stable high-energy materials is based on an assembly of polynitrogen biheterocyclic scaffolds. Herein, we report on the design and synthesis of a new series of high-nitrogen energetic salts comprising the C-C linked 6-aminotetrazinedioxide and hydroxytetrazole frameworks.

Renaissance of dinitroazetidine: novel hybrid energetic boosters and oxidizers.

Nitrogen-oxygen organic materials constitute an important family of multipurpose high-energy materials. However, the preparation of energetic boosters and oxidizers for various civil and space technologies remains a challenging task and such materials usually require special precautions and fine tunability of their functional properties. To find a balance between energy and safety while retaining the oxidizing ability of target energetic materials, novel hybrid organic compounds comprising furoxan and 3,3-dinitroazetidine scaffolds enriched with additional nitro groups were synthesized.

Autocatalytic decomposition of energetic materials: interplay of theory and thermal analysis in the study of 5-amino-3,4-dinitropyrazole thermolysis.

A reliable kinetic description of the thermal stability of energetic materials (EM) is very important for safety and storage-related problems. Among other pertinent issues, autocatalysis very often complicates the decomposition kinetics of EM. In the present study, the kinetics and decomposition mechanism of a promising energetic compound, 5-amino-3,4-dinitro-1-pyrazole (5-ADP) were studied using a set of complementary experimental (, differential scanning calorimetry in the solid state, melt, and solution along with advanced thermokinetic models, accelerating rate calorimetry, and evolved gas analysis) and theoretical techniques (CCSD(T)-F12 and DLPNO-CCSD(T) predictive quantum chemical calculations).

Nitrogen-rich metal-free salts: a new look at the 5-(trinitromethyl)tetrazolate anion as an energetic moiety.

A series of energetic nitrogen-rich salts comprised of a 5-(trinitromethyl)tetrazolate anion and high-nitrogen cations was synthesized by simple and efficient chemical routes from readily available commercial reagents. These energetic materials were fully characterized by IR and multinuclear NMR (H, C, N) spectroscopy, elemental analysis, and differential scanning calorimetry (DSC). Additionally, the structure of an energetic salt containing the 3,6,7-triamino-7-[1,2,4]triazolo[4,3-][1,2,4]triazolium cation was confirmed by single-crystal X-ray diffraction.

Design and Synthesis of Nitrogen-Rich Azo-Bridged Furoxanylazoles as High-Performance Energetic Materials.

A series of novel energetic materials comprising of azo-bridged furoxanylazoles enriched with energetic functionalities was designed and synthesized. These high-energy materials were thoroughly characterized by IR and multinuclear NMR ( H, C, N) spectroscopy, high-resolution mass spectrometry, elemental analysis, and differential scanning calorimetry (DSC). The molecular structures of representative amino and azo oxadiazole assemblies were additionally confirmed by single-crystal X-ray diffraction and X-ray powder diffraction.

Learning to fly: thermochemistry of energetic materials by modified thermogravimetric analysis and highly accurate quantum chemical calculations.

The standard state enthalpy of formation and the enthalpy of sublimation are essential thermochemical parameters determining the performance and application prospects of energetic materials (EM). Direct experimental measurements of these properties are complicated by low volatility and high heat release in bomb calorimetry experiments. As a result, the uncertainties in the reported enthalpies of formation for a number of even well-known CHNO-containing compounds might amount up to tens kJ mol-1, while for some novel high-nitrogen molecules they reach even hundreds of kJ mol-1.

Apparent autocatalysis due to liquefaction: thermal decomposition of ammonium 3,4,5-trinitropyrazolate.

Thermal decomposition of solids is often accompanied by autocatalysis, one of the possible causes of which is the formation of a liquid phase. The kinetic model considering the liquefaction of solid reactants under isothermal conditions was proposed by Bawn in the 1950s. The present study reports the application of the Bawn model to the thermolysis of 3,4,5-trinitropyrazole ammonium salt (ATNP) under nonisothermal conditions.

Nitro-, Cyano-, and Methylfuroxans, and Their Bis-Derivatives: From Green Primary to Melt-Cast Explosives.

In the present work, we studied in detail the thermochemistry, thermal stability, mechanical sensitivity, and detonation performance for 20 nitro-, cyano-, and methyl derivatives of 1,2,5-oxadiazole-2-oxide (furoxan), along with their bis-derivatives. For all species studied, we also determined the reliable values of the gas-phase formation enthalpies using highly accurate multilevel procedures W2-F12 and/or W1-F12 in conjunction with the atomization energy approach and isodesmic reactions with the domain-based local pair natural orbital (DLPNO) modifications of the coupled-cluster techniques. Apart from this, we proposed reliable benchmark values of the formation enthalpies of furoxan and a number of its (azo)bis-derivatives.

Supercritical Antisolvent Processing of Nitrocellulose: Downscaling to Nanosize, Reducing Friction Sensitivity and Introducing Burning Rate Catalyst.

A supercritical antisolvent process has been applied to obtain the nitrocellulose nanoparticles with an average size of 190 nm from the nitrocellulose fibers of 20 μm in diameter. Compared to the micron-sized powder, nano-nitrocellulose is characterized with a slightly lower decomposition onset, however, the friction sensitivity has been improved substantially along with the burning rate increasing from 3.8 to 4.

Critical Appraisal of Kinetic Calculation Methods Applied to Overlapping Multistep Reactions.

Thermal decomposition of solids often includes simultaneous occurrence of the overlapping processes with unequal contributions in a specific physical quantity variation during the overall reaction (e.g., the opposite effects of decomposition and evaporation on the caloric signal).

Assembly of Tetrazolylfuroxan Organic Salts: Multipurpose Green Energetic Materials with High Enthalpies of Formation and Excellent Detonation Performance.

A series of highly energetic organic salts comprising a tetrazolylfuroxan anion, explosophoric azido or azo functionalities, and nitrogen-rich cations were synthesized by simple, efficient, and scalable chemical routes. These energetic materials were fully characterized by IR and multinuclear NMR ( H, C, N, N) spectroscopy, elemental analysis, and differential scanning calorimetry (DSC). Additionally, the structure of an energetic salt consisting of an azidotetrazolylfuroxan anion and a 3,6,7-triamino-7H-[1,2,4]triazolo[4,3-b][1,2,4]triazolium cation was confirmed by single-crystal X-ray diffraction.

Toward reliable characterization of energetic materials: interplay of theory and thermal analysis in the study of the thermal stability of tetranitroacetimidic acid (TNAA).

The thermal stability of energetic materials, being of the utmost importance for safety issues, is often considered in terms of kinetics, e.g., the Arrhenius parameters of the decomposition rate constant.

Kinetic analysis of overlapping multistep thermal decomposition comprising exothermic and endothermic processes: thermolysis of ammonium dinitramide.

This study focused on kinetic modeling of a specific type of multistep heterogeneous reaction comprising exothermic and endothermic reaction steps, as exemplified by the practical kinetic analysis of the experimental kinetic curves for the thermal decomposition of molten ammonium dinitramide (ADN). It is known that the thermal decomposition of ADN occurs as a consecutive two step mass-loss process comprising the decomposition of ADN and subsequent evaporation/decomposition of in situ generated ammonium nitrate. These reaction steps provide exothermic and endothermic contributions, respectively, to the overall thermal effect.