Bisnitramide-Bridged -Substituted Tetrazoles with Balanced Sensitivity and High Performance.

In this study, a simple synthetic strategy for bridged bis(nitramide)-based -substituted tetrazoles is described. All new compounds were isolated and fully characterized by sophisticated analytical techniques. The structures of the intermediate derivative and two final compounds were determined by single-crystal X-ray data.

Effects of nitric acid concentration for nitration of fused [1,2,5]oxadiazolo[3,4-]pyrimidine-5,7-diamine.

Nitration reactions are very often used for the selective synthesis of novel, high performing nitramine-based materials. Now nitration reactions of the fused 5,7-diamino pyrimidine derivative 1, under different nitric acid concentrations were examined. Concentrated nitric acid gave selectively -(5-amino-4,5-dihydro-[1,2,5]oxadiazolo[3,4-]pyrimidin-7-yl)nitramide, 2, while the fused ring nitrate salt, 4, and ring open nitrate salt, 3 were obtained using low concentrations of nitric acid (<70%).

Construction of Highly Thermostable and Insensitive Three-Dimensional Energetic Salts Based on [1,2,5]Oxadiazolo[3,4-]pyrimidine.

A novel method for accessing energetic salts of a fused-ring skeleton based on [1,2,5]oxadiazolo[3,4-]pyrimidine and three alkali metals, sodium (Na), potassium (K), and cesium (Cs), was developed. All three compounds were fully characterized, and their structures were confirmed by single-crystal X-ray analysis. They were highly thermally stable (>290 °C) and had high density, good detonation properties, and insensitive properties, which suggested possible heat-resistant explosive applications.

Energetic Salts of Sensitive N,N'-(3,5-Dinitropyrazine-2,6-diyl)dinitramide Stabilized through Three-Dimensional Intermolecular Interactions.

N-nitration of 2,6-diamino-3,5-dinitropyrazine (ANPZ) leads to a sensitive energetic compound N,N'-(3,5-dinitropyrazine-2,6-diyl)dinitramide. This nitro(nitroamino) compound was stabilized by synthesizing energetic salts, dipotassium (3,5-dinitropyrazine-2,6-diyl)bis(nitroamide) () and diammonium (3,5-dinitropyrazine-2,6-diyl)bis(nitroamide) (). Compounds and are fully characterized by single-crystal X-ray diffraction.

Nucleophilic Catalyzed Structural Binary Cleavage of a Fused [5,5]-Bicyclic Compound.

Structural binary cleavage of 3,7-diamino-2,6-dinitro-1,5-pyrazolo-[1,2-]pyrazole-1,5-dione , under nucleophilic conditions, leads to the formation of a monocyclic pyrazole unit of 5-amino-4-nitro-1,2-dihydro-3-pyrazol-3-one, . Additionally, various salts of the pyrazole ring were synthesized and fully characterized. Detonation properties and mechanical sensitivities of and other new compounds are remarkably improved compared to .

1,2-Bis(5-(trinitromethyl)-1,2,4-oxadiazol-3-yl)diazene: a water stable, high-performing green oxidizer.

Trinitromethane moieties are very important for the design and development of high performing dense green oxidizers. The novel oxidizer 1,2-bis(5-(trinitromethyl)-1,2,4-oxadiazol-3-yl)diazene, 14 is stable in water in contrast to 1,2,4-oxadiazoles with other electron withdrawing substituents at the C5-position. Compound 14 is a CNO-based oxidizer with positive oxygen balance (+6.

Energetic Tricyclic Polynitropyrazole and Its Salts: Proton-Locking Effect of Guanidium Cations.

An axisymmetric polynitro-pyrazole molecule, 3,5-di(3,5-dinitropyrazol-4-yl)]-4-nitro-1-pyrazole (), and its salts (-) were prepared and fully characterized. These compounds not only show promising energetic properties but also show a unique tautomeric switch via combining different cations with the axisymmetric compound (). Its salts (-) remain axisymmetric when the cations are potassium, ammonium, or amino-1,2,4-triazolium.

Selective Synthesis of Bis(3-(3-(trifluoromethyl)-1-1,2,4-triazol-5-yl)-4,4'-azo- and -azoxyfurazan Derivatives.

In this paper, we report the synthesis of two new derivatives, bis(3-(3-(trifluoromethyl)-1-1,2,4-triazol-5-yl)-4,4'-azo- and -azoxyfurazans by selective oxidation of 4-(3-(trifluoromethyl)-1-1,2,4-triazol-5-yl)-1,2,5-oxadiazol-3-amine. Ammonium salts of these derivatives were prepared, and all of them were fully characterized by multinuclear NMR, FTIR spectroscopy, elemental analysis, differential scanning calorimetry (DSC), and single-crystal X-ray diffraction. All of the new compounds have high measured crystal densities, and the energetic properties have been investigated.

Response to "What Shall We Do with Computed Detonation Performance? Comment on '1,3,4-Oxadiazole Bridges: A Strategy to Improve Energetics at the Molecular Level'".

The values obtained for detonation performance are a function of the computational methods utilized. Since there are many such methods, the literature may contain a range of values for a single compound.

Mono-N-oxidation of heterocycle-fused pyrimidines.

Three nitrogen-rich heterocyclic compounds containing the diamino-pyrimidine mono-N-oxide moiety were synthesized via mild oxidation reactions. Oxidation of the furazano-pyrimidine compound (1) with a mixture of trifluoroacetic anhydride (TFAA) and hydrogen peroxide (50%) gave the nitrate salt (3). All of the compounds were characterized by NMR spectra, elemental analysis, and single-crystal X-ray diffraction.

HFOX-1-Amino-1-hydrazino-2,2-Dinitroethylene as a Precursor to Trifluoromethyl, Dinitro, or Trinitro-Based Energetic 1,2,4-Triazoles.

The chemical reactivity of 1-amino-1-hydrazino-2,2-dinitroethylene with a carboxylic acid for the construction of structurally interesting energetic triazoles and their energetic salts is reported. All new compounds were fully characterized by elemental analysis, infrared spectroscopy, nuclear magnetic resonance spectroscopy, and differential scanning calorimetry. Crystal analysis, good detonation properties, and low sensitivities of these trifluoromethyl and dinitro- or trinitro-based triazoles suggest their role as potential candidates for insensitive high-energy-density materials.

1,3,4-Oxadiazole Bridges: A Strategy to Improve Energetics at the Molecular Level.

Many energetic materials synthesized to date have limited applications because of low thermal and/or mechanical stability. This limitation can be overcome by introducing structural modifications such as a bridging group. In this study, a series of 1,3,4-oxadiazole-bridged furazans was prepared.

A Duo and a Trio of Triazoles as Very Thermostable and Insensitive Energetic Materials.

The triazole moiety with a high heat of formation and a high nitrogen content has been investigated for decades in combination with other nitrogen-rich heterocyclic rings in the field of energetic materials. A novel strategy for the construction of both thermally stable and mechanically insensitive energetic materials using a multi-aminotriazole system is now described. Using this methodology, two series of energetic materials were created on the basis of a duo of triazoles, 5-amino-3-(3,4-diamino-1,2,4-triazol-5-yl)-1-1,2,4-triazole (), and a trio of triazoles, 4,5-di(3,4-diamino-1,2,4-triazol-5-yl)-2-1,2,3-triazole ().

Azo- and methylene-bridged mixed azoles for stable and insensitive energetic applications.

A simple synthetic strategy for the preparation of high nitrogen content azo- and methylene bridged mixed energetic azoles was used. All new compounds were fully characterized by NMR and infrared spectroscopy, elemental analysis, and differential scanning calorimetry (DSC). In addition, the structures of energetic salts 7 and 10 were confirmed by single-crystal X-ray diffraction analysis.

Energetic Butterfly: Heat-Resistant Diaminodinitro trans-Bimane.

Due to a significant and prolific activity in the field of design and synthesis of new energetic molecules, it becomes increasingly difficult to introduce new explosophore structures with attractive properties. In this work, we synthesized a trans-bimane-based energetic material-3,7-diamino-2,6-dinitro-1,5-pyrazolo-[1,2-a]pyrazole-1,5-dione (4), the structure of which was comprehensively analyzed by a variety of advanced spectroscopic methods and by X-ray crystallo-graphy (with density of 1.845 g·cm at 173 K).

Design and synthesis of hybrid cyclophanes containing thiophene and indole units via Grignard reaction, Fischer indolization and ring-closing metathesis as key steps.

We demonstrate a new synthetic strategy to cyclophanes containing thiophene and indole moieties via Grignard addition, Fischer indolization and ring-closing metathesis as key steps.

Diversity-Oriented Approach to Cyclophanes via Fischer Indolization and Ring-Closing Metathesis: Substrate-Controlled Stereochemical Outcome in RCM.

Here, we report a new and diversity-oriented approach to macrocyclic cyclophanes by a Grignard reaction, followed by Fischer indolization and ring-closing metathesis (RCM) as key steps. The configuration of the double bond formed during the RCM depends upon the order of synthetic sequence used. Fischer indolization followed by RCM delivers the cis isomer, whereas RCM followed by Fischer indolization gives the trans isomer.

Hybrid macrocycle formation and spiro annulation on cis-syn-cis-tricyclo[6.3.0.0(2,6)]undeca-3,11-dione and its congeners via ring-closing metathesis.

We have developed a simple methodology to transform cis-syn-cis-triquinane derivative 2 into the diindole based macrocycle 6 involving Fischer indolization and ring-closing metathesis (RCM). Various spiro-polyquinane derivatives have been assembled via RCM as a key step.

Synthesis of indole-based propellane derivatives via Weiss-Cook condensation, Fischer indole cyclization, and ring-closing metathesis as key steps.

A variety of highly functionalized indole-based [n.3.3]propellane derivatives is described.