Kinetics of the thermal decomposition of dinitramide

The kinetic regularities of the heat release during the thermal decomposition of liquid NH₄N(NO₂)₂ at 102.4–138.9 °C were studied. Kinetic data for decomposition of different forms of dinitramide and the influence of water on the rate of decomposition of NH₄N(NO₂)₂ show that the contributions of the decomposition of N(NO₂)₂ ⁻ and HN(NO₂)₂ to the initial decomposition rate of the reaction at temperatures about 100 °C are approximately equal. The decomposition has an autocatalytic character. The analysis of the effect of additives of HNO₃ solutions and the dependence of the autocatalytic reaction rate constant on the gas volume in the system shows that the self-acceleration is due to an increase in the acidity of the NH₄N(NO₂)₂ melt owing to the accumulation of HNO₃ and the corresponding increase in the contribution of the HN(NO₂)₂ decomposition to the overall rate. The self-acceleration ceases due to the accumulation of NO₃ ⁻ ions decreasing the equilibrium concentration of HN(NO₂)₂ in the melt. For Part 2, see Ref. 1. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 395–401 March 1998.     

A Smart Access to the Dinitramide Anion – The Use of Dinitraminic Acid for the Preparation of Nitrogen-Rich Energetic Copper(II) Complexes

Dinitraminic acid (HN(NO₂)₂, HDN) was prepared by ion exchange chromatography and acid-base reaction with basic copper(II) carbonate allowed the in situ preparation of copper(II) dinitramide, which was reacted with twelve nitrogen-rich ligands, for example, 4-amino-1,2,4-triazole, 1-methyl-5H-tetrazole, di(5H-tetrazolyl)-methane/-ethane/-propane/-butane. Nine of the complexes were investigated by low-temperature X-ray diffraction. In addition, all compounds were investigated by infrared spectroscopy (IR), differential thermal analysis (DTA), elemental analysis (EA) and thermogravimetric analysis (TGA) for selected compounds. Furthermore, investigations of the materials were carried out regarding their sensitivity toward impact (IS), friction (FS), ball drop impact (BDIS) and electrostatic discharge (ESD). In addition, hot plate and hot needle tests were performed. Complex [Cu(AMT)₄(H₂O)](DN)₂, based on 1-amino-5-methyltetrazole (AMT), is most outstanding for its detonative behavior and thus also capable of initiating PETN in classical initiation experiments. Laser ignition experiments at a wavelength of 915 nm were performed for all substances and solid-state UV-Vis spectra were recorded to apprehend the ignition mechanism.     

A new class of flexible energetic salts, part 6: the structures of the hydrazinium and hydroxylammonium salts of dinitramide

The crystal structures of two amine base salts, the hydrazinium, 1, and the hydroxylammonium, 2, of dinitramide have been determined. 1 crystallizes in the monoclinic space group P 2₁/c with cell dimensions a = 8.312(3), b = 5.654(1), c = 10.659(3) Å, = 93.73(3)°, while 2 crystallizes in the orthorhombic space group Pcab (nonstandard setting of Pbca) with cell dimensions a = 6.439(2), b = 12.470(4), c = 30.816(14) Å. The structures of 1 and 2 contain protonated amine cations and dinitramide anions linked by hydrogen bonding. In addition, in 2 there are both neutral and zwitterionic hydroxylamine moieties involved in the hydrogen bonding scheme. Thus in 2 the complete formula unit is (NH₃ ⁺OH)₂[N₃O₄ ^–]₂ · (NH₂OH) middot; (NH₃ ⁺O^–), and in this structure the hydroxylamine exists in its three possible forms: protonated, neutral, and zwitterionic. In both structures the conformations adopted by the dinitramine anions can be related to the types of hydrogen bonds it forms with the surrounding amine cations.     

Kinetics of the thermal decomposition of dinitramide

The kinetic regularities of the thermal decomposition of dinitramide in aqueous solutions of HNO₃, in anhydrous acetic acid, and in several other organic solvents were studied. The rate of the decomposition of dinitramide in aqueous HNO₃ is determined by the decomposition of mixed anhydride of dinitramide and nitric acid (N₄O₆) formed in the solution in the reversible reaction. The decomposition of the anhydride is a reason for an increase in the decomposition rates of dinitramide in solutions of HNO₃ as compared to those in solutions in H₂SO₄ and the self-acceleration of the process in concentrated aqueous solutions of dinitramide. The increase in the decomposition rate of nondissociated dinitramide compared to the decomposition rate of the N(NO₂)₂ ⁻ anion is explained by a decrease in the order of the N−NO₂ bond. The increase in the rate constant of the decomposition of the protonated form of dinitramide compared to the corresponding value for neutral molecules is due to the dehydration mechanism of the reaction. For Part 1, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 41–47, January, 1998.     

Energetic materials: The preparation and structural characterization of melaminium dinitramide and melaminium nitrate

Two energetic salts of the melaminium cation have been prepared and structurally characterized from room temperature X-ray single crystal diffraction data. Melaminium dinitramide (I), triclinic, P1¯, a = 6.6861(11), b = 6.9638(16), c = 10.447(2) Å , = 99.07(3), = 98.30(3), = 108.50(3)°, V = 445.6(2) ų, and Z = 2. Melaminium nitrate (II), monoclinic, P2₁/c, a = 3.5789(7), b = 20.466(4), c = 10.060(2) Å, = 94.01(2)°, V = 735.0(3) ų, and Z = 4. The crystal structures of both salts show distinct monoprotonated melaminium cations and dinitramide- or nitrate anions, respectively. Efficient packing in the solid state is achieved by extensive hydrogen bonding between two-dimensional zigzag ribbons of the melaminium cations and the respective anions resulting in high densities of the solid state structures of 1.74 (I) and 1.71 g/cm³ (II).     

A new class of flexible energetic salts, part 5: The structures of two hexammonium polymorphs and the ethane-1,2-diammonium salts of dinitramide

The crystal structures of two hexammonium polymorphs, 1 and 2, and the ethane-1,2-diammonium, 3, salts of dinitramide have been determined. 1 crystallizes in the triclinic space group with cell dimensions a = 6.391(2), b = 7.5826(9), c = 10.828(1) Å, a = 77.58(1), = 88.18 (2), = 87.54(2)°, 2 crystallizes in the monoclinic space group P2₁/c with cell dimensions a = 6.4893(3), b = 14.5149(8), c = 10.6557(4) Å, = 94.300(4)°, and 3 crystallizes in the triclinic space group with cell dimensions a = 5.614(1), b = 6.867(2), c = 7.371(2) Å, = 68.89(2), = 89.00(2), = 78.90(2)°. The three structures all contain protonated amine cations which are involved in hydrogen bonding interactions with dinitramide anions.     

A new class of flexible energetic salts, part 2: The crystal structures of the cubane-1,4-diammonium dinitramide and cubane-1,2,4,7-tetraammonium dinitramide salts

The crystal structures of cubane-1,4-diammonium dinitramide, 1, and cubane-1,2,4,7-tetraammonium dinitramide, 2, have been determined. 1 crystallizes in the space group P2₁/c with cell dimensions a = 6.018(2), b = 11.642(3), c = 9.754(3) Å, = 107.24(2), while 2 crystallizes in the space group P2₁/c with cell dimensions a = 9.401(4), b = 9.603(3), c = 12.603(4) Å, 111.08(3). In these structures the ammonium substituents are symmetrically attached with respect to the cubane skeleton and have neither low lying empty orbitals nor available lone pairs of electrons thus they have a minimal effect on the metrical parameters of the cubane skeleton. All C–C bond lengths are close to the overall average C–C bond length for all reported cubanes of 1.559 Å. The conformations adopted by the dinitramide ions in both structures are quite different, with the bend, twist, and torsion angles for the dinitramide ion in 1 being significantly larger than those found for the dinitramide ions in 2, due to the different types of hydrogen bonding found in the two structures. In 2, the conformation adopted by the adjacent ammonium ions allows two of the three protons from each ammonium cation to form hydrogen bonds in such a manner that they span either the syn or the anti oxygen atoms of a single dinitramide anion. The dinitramide anion is thus constrained by these interactions and is less free to twist and bend. These results provide further confirmation that the metrical parameters of both the cubane and dinitramide moieties are flexible and reflect their local environment.     

A new class of flexible energetic salts, part 4: The crystal structures of hexaaquomagnesium(II), hexaaquomanganese(II), and hexaaquozinc(II) dihydrate salts of dinitramide

The crystal structures of the hexaaquomagnesium (1), hexaaquomanganese (2), and hexaaquozinc (3) dihydrate salts of dinitramide have been determined. 1 crystallizes in the monoclinic space group P2₁/n with cell dimensions a = 9.589(2), b = 7.420(1), c = 11.116(2) Å, = 108.25(3)°, 2 crystallizes in the monoclinic space group P2₁/n with cell dimensions a = 9.623(4), b = 7.477(2), c = 11.274(3) Å, = 108.38(3)°, and 3 crystallizes in the monoclinic space group P2₁/n with cell dimensions a = 9.513(1), b = 7.4270(8), c = 11.164(1) Å, = 108.806(6)°. The three structures are isostructural, consisting of hexaaquo cations, dinitramide anions and water molecules interlinked by an extensive three dimensional hydrogen bonding interactions. All oxygen atoms as well as the central nitrogen atom of the dinitramide anion are involved in acceptor hydrogen bonds with neighboring water protons. As a consequence of the constraints imposed by these hydrogen bonds the dinitramide ions are almost planar with average deviations of 0.01 Å for 1, 0.03 Å for 2 and 0.03 Å for 3.     

Kinetics of thermal decomposition of dinitramide

Kinetic regularities of thermal decomposition of dinitramide in aqueous and sulfuric acid solutions were studied in a wide temperature range. The rate of the thermal decomposition of dinitramide was established to be determined by the rates of decomposition of different forms of dinitramide as the acidity of the medium increases: first, N(NO₂)⁻ anions, then HN(NO₂)₂ molecules, and finally, protonated H₂N(NO₂)₂ ⁺ cations. The temperature dependences of the rate constants of the decomposition of N(NO₂)⁻ (k _an) and HN(NO₂)₂ (k′_ac) and the equilibrium constant of dissociation of HN(NO₂)₂ (K _a) were determined:k _an=1.7·10¹⁷ exp(−20.5·10³/T), s⁻¹,k′_ac=7.9·10¹⁶ exp(−16.1·10³/T), s⁻¹, andK _a=1.4·10 exp(−2.6·10³/T). The temperature dependences of the decomposition rate constant of H₂N(NO₂)₂ ⁺ (k _d) and the equilibrium constant of the dissociation of H₂N(NO₂)₂ ⁺ (K _d) were estimated:k _d=10¹² exp(−7.9·10³/T), s⁻¹ andK _d=1.1 exp(6.4·10³/T). The kinetic and thermodynamic constants obtained make it possible to calculate the decomposition rate of dinitramide solutions in a wide range of temperatures and acidities of the medium. In this series of articles, we report the results of studies of the thermal decomposition of dinitramide performed in 1974–1978 and not published previously. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2129–2133, December, 1997.     

Dinitramide and its salts

The dinitramide anion shows ambident properties. Its reactions with alkylating reagents give rise toN- orO-alkylated products or their mixtures. The reactions of alkylated products with bases were studied.For the previous communication, see V. A. Shlyapochnikov, G. I. Oleneva, N. O. Cherskaya, O. A. Luk'yanov, V. P. Gorelik, O. V. Anikin, and V. A. Tartakovsky,Izv. Akad. Nauk, Ser. Khim., 1994, 1610 [Russ. Chem. Bull., 1994,43, No. 11 (Engl. Transl.)].Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1775–1778, October, 1994.