Synthesis and Characterization of New Energetic Nitroformate Salts

Straightforward Synthesis of Insensitive 2-(1-Hydroxy-2,2-dinitrovinyl)guanidine and Its Guanidinium Dinitromethanide Salt as a High Energy Density Material

High energetic 2-(1-hydroxy-2,2-dinitrovinyl)guanidine and guanidinium dinitromethanide (GDNM) salt were synthesized in one and two steps using a simple and cost-effective methodology from commercially available inexpensive starting materials with a high yield. NMR, IR spectroscopy, elemental analysis, and differential scanning calorimetry studies were used to characterize compound 2a and GDNM salt. Single-crystal XRD, Hirshfeld surface analysis, and SEM analysis were used to study the crystal structure, hydrogen-bonding/noncovalent interactions, and morphology of the GDNM salt, respectively. The physicochemical and energetic properties of compound 2a and GDNM salt reveal their good energetic performance, specific impulse, and high mechanical insensitivity, which are better than that of propellants such as ADN and AP and close to that of the benchmark explosives such as RDX and FOX-7.

Taming nitroformate through encapsulation with nitrogen-rich hydrogen-bonded organic frameworks

Owing to its simple preparation and high oxygen content, nitroformate [^-C(NO₂)₃, NF] is an extremely attractive oxidant component for propellants and explosives. However, the poor thermostability of NF-based derivatives has been an unconquerable barrier for more than 150 years, thus hindering its application. In this study, the first example of a nitrogen-rich hydrogen-bonded organic framework (HOF-NF) is designed and constructed through self-assembly in energetic materials, in which NF anions are trapped in pores of the resulting framework via the dual force of ionic and hydrogen bonds from the strengthened framework. These factors lead to the decomposition temperature of the resulting HOF-NF moiety being 200 °C, which exceeds the challenge of thermal stability over 180 °C for the first time among NF-based compounds. A large number of NF-based compounds with high stabilities and excellent properties can be designed and synthesized on the basis of this work.

A general method for the synthesis of covalent and ionic amine borane complexes containing trinitromethyl fragments

A general approach for the synthesis of covalent and ionic amine borane complexes containing trinitromethyl fragments has been developed through metathesis reactions between amine chloroborane complexes and potassium salt of trinitromethyl (K[C(NO₂)₃]). Five covalent and ionic trinitromethyl amine borane complexes have been synthesized in good yields with high purity and it is found that the ionic complex, [H₂B(NH₃)₂][C(NO₂)₃], might be a promising energetic material on the basis of the investigation of its thermal decomposition behaviour.

A general approach has been developed through which five covalent and ionic amine borane complexes containing trinitromethyl fragments were synthesized.

The strategy for improving the stability of nitroform derivatives-high-energetic oxidant based on hexanitroethane

To develop high-energetic stability nitroform compounds, three types of nitroform derivatives based on hexanitroethane structure are designed. The guidelines for selecting these compounds are based on (1) constructing a flexible molecule and weakening the external force by elastic deformation and (2) forming negative ion or introducing electron-rich group to eliminate the electron-deficient situation. The conformations and some important properties of them are calculated at B3LYP/6-311 + G(d) level. Based on the bond order and bond dissociation enthalpy analysis, C-NO₂ bond is considered to be the most unstable position, and both of the methods can improve the stability of designed compounds. Based on molecular energy gap (HOMO-LUMO) and density of state (DOS) analysis, it is found that introducing of bridge atoms is helpful to lower the sensitivity, while the construction of anions changes both HOMO-LUMO and DOS which shows obvious ionic properties. A further study on the electrical potential surface shows that the probability for extreme values of designed compounds decreases which is beneficial for high stability. Finally, the explosive properties and impact sensitivity of them are calculated. Results show that their explosive performances are obviously better than current energetic oxidants and some of them maintain low sensitivity.

Experimental and theoretical approving of anomeric based oxidation in the preparation of 2-sbstituted benz-(imida, oxa and othia)-zoles using [2,6-DMPy-NO2]C(NO2)3 as a novel nano molten salt catalyst

The synthesis of [2,6-DMPy-NO₂]C(NO₂)₃ as a novel NMS and its application in the synthesis of 2-sbstituted benz-(imida, oxa and othia)-zoles via a new mechanistic approach was supported by theoretical studies.

Energetic salts from nitroformate ion

Development of new energetic salts is the key factor in replacing low performance compounds in conventional formulations of high explosives as well as propellants. Ten salts based on the nitroformate anion and various nitrogen-rich cations were designed and their geometric optimizations carried out using the density functional method. With reasonable oxygen balance (from -36% to 0%), heats of formation (47-624 kJ mol(-1)) and high densities (1.81-1.89 g cm(-3)), the detonation velocity (D) and pressure (P) values of salts were calculated as 8.62-9.36 km s(-1) and 33.10-40.01 GPa, respectively. Lastly, the nitroformate salts studied in this work are of prospective interest as high performance explosives.

Energetic N-trinitroethyl-substituted mono-, di-, and triaminotetrazoles

A series of dense energetic N-trinitroethyl-substituted mono-, bis-, and tri-5-aminotetrazoles were obtained by reacting primary amines with in situ generated cyanogen azide, followed by the trinitroethyl functionalization that involves a condensation of a hydroxymethyl intermediate (prepared by a reaction with formaldehyde) with trinitromethane. These compounds were fully characterized by using multinuclear NMR spectroscopy, IR, elemental analysis, differential scanning calorimetry (DSC), and, in one case with 9, with single-crystal XRD analysis. The heats of formation for all compounds were calculated with Gaussian 03 and then combined with experimental densities to determine the detonation pressures (P) and velocities (D(v)) of the energetic materials. Interestingly, most of them exhibited high density, good thermal stability, acceptable oxygen balance, positive heat of formation, low impact sensitivity, and excellent detonation properties, which highlighted their practical application potentials as a fascinating class of highly energetic materials.

Energetic N,N,N',N'-tetraaminopiperazinium salts

The formation of terraminopiperazinium salts using water as solvent provides a green, straightforward approach to highly energetic salts that exhibit good thermal stabilities and moderate densities. The N,N,N',N'-tetraaminopiperazinium cation was selected for this study because of its high nitrogen-nitrogen bond content and its hign positive near or formation. Theoretical and empirical calculations on energetic salts based on this nitrogen-rich cation reveal them to have high positive molar enthalpies of formation, as high as 1034.0 kJ mol(-1), supporting the application of these new salts as potential energetic materials.