T. K. Goncharov

Preparation, structure, and main properties of bimolecular crystals CL-20—DNP and CL-20—DNG

New bimolecular crystals of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) with 2,4-dinitro-2,4-diazapentane (DNP) and 2,4-dinitro-2,4-diazaheptane (DNG) were obtained in a ratio of 2 : 1 and 1 : 1, respectively. Their X-ray diffraction analyses were carried out. The thermal stability, detonation characteristics, and sensitivity to friction of bimolecular crystal of CL-20 with DNP (CLD) were studied. The detonation characteristics of bimolecular crystal CLD are comparable with the properties of the known bimolecular crystal CL-20—HMX (2 : 1).

Crystal structure of cocrystals 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclo [5.5.0.05.9.03.11]dodecane with 7H-tris-1,2,5-oxadiazolo (3,4-b:3′,4′-d:3″,4″-f) azepine

The crystal structure of the bimolecular crystal of CL-20 with new promising highly energetic compound 7H-tris-1,2,5-oxadiazolo[3,4-b:3′,4′-d:3″,4″-f] azepine is obtained and studied.

Structure and properties of cocrystals of trinitrotoluene and 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane

Crystals containing 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane and trinitrotoluene molecules in a 1: 1 ratio were obtained. The crystal structure was determined, and DSC thermograms, thermal stability, and the standard enthalpy of formation were investigated. An analysis of the crystal structure shows that interactions between the oxygen and nitrogen atoms of the nitro groups ON=O…NO2 of adjacent molecules are among the structure-forming intermolecular interactions in the crystals of polynitroamine compounds.

Crystal structure of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane solvate with ɛ-caprolactam

The crystal structure of the CL-20 solvate with ɛ-caprolactam in the 1:6 ratio is obtained and studied.

Crystal structure of 4,4″-dinitro-[3,3′,4′,3″]-tris-[1,2,5]-oxadiazole

The crystal structure of a new energetic compound of 4,4″-dinitro-[3,3′:4,3″]-tris-[1,2,5]-oxadiazole is studied.

Structure of a bimolecular crystal of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane and methoxy-NNO-azoxymethane

The crystal structure of the bimolecular crystal of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and methoxy-NNO-azoxymethane (МАМ) (1:2) is studied. The CL-20 molecules adopt a ζ-conformation. The crystal structure is formed by layers of CL-20 and МАМ molecules, between which there are shortened NOδ–⋯Nδ+O contacts of the neighboring CL-20 and МАМ molecules.

Impact sensitivity of energy systems based on nanoporous silicon and oxidant: influence of the hydrogen content and specific surface

The impact sensitivity of the energy systems based on nanoporous silicon, obtained by electrochemical etching of monocrystalline silicon wafers in an HF-containing electrolyte, and calcium perchlorate was studied using a modified Weller—Ventselberg technique (estimation of the impact sensitivity of initiating explosives). The impact sensitivity of these systems is shown to be determined by both the presence of hydrogen, which is stored on the porous silicon surface during the preparation of the latter, and also the influence of other factors, including the specific surface of porous silicon. The composition, amount of the generated gas, and gas evolution rate during nonisothermal and isothermal calcination of porous silicon in a temperature range of 60—120 °С were determined using methods of thermal gravimetry (TG), measurement of the gas volume, and mass spectrometry. The generated gas almost completely consists of hydrogen, and its content in the studied samples of porous silicon achieved ~3.8 wt.%. The calculated activation energy of the hydrogen evolution process in vacuo was 103.7±3.3 kJ mol–1. The dependences of the impact sensitivity of the energy composition based on porous silicon and heat of combustion of porous silicon on oxygen on the hydrogen content were established. The impact sensitivity of the energy system decreases with a decrease in the hydrogen content in porous silicon and its specific surface.

Energetic potential of solid composite propellants based on CL-20-containing bimolecular crystals

The energetic potential of bimolecular crystals (BMCs) containing CL-20 as components of solid composite propellants (SCPs) was investigated. The experimental and calculated values of the standard enthalpies of formation are reported. The maximum heats of explosion, which correlate with the impact sensitivity, were calculated. The specific impulse values and the densities of SCPs based on an active binder, aluminum, and oxidizer (BMC + a small portion of ammonium dinitramide) were evaluated.

Kinetics and Mechanism of the Thermal Decomposition of the Isoxazoline Compounds

The decomposition of the isoxazole ring at 160–280°C formed by the addition of ethylene to methyland ethyl–substituted benzonitrile oxides is studied. The reaction consists in the cleavage of the isoxazole ring into acetaldehyde and the corresponding aromatic nitrile. Its rate in the melt and in inert solvents, such as chlorobenzene, only weakly depends on the structure of the aromatic substituent, with the kinetic parameters having low values: E = (104 ± 8) kJ/mol and log(A, s–1) = 7.2 ± 0.8. Only if the benzene ring has three ethyl substituents, the decomposition of the compound in the melt proceeds faster than in solution. The rate of the decomposition of the ring decreases with increasing viscosity of the medium, being higher in solvents with a lower strength of the C–H bond. For compounds with the fully deuterated isoxazole ring, the inverse kinetic H/D isotope effect is observed. The results are explained in terms of the biradical mechanism of the opening of the isoxazole ring that involves an effective recombination of the biradical and its loss through a synchronous rearrangement with acetaldehyde release.

Structure and stability of isoxazoline compounds

Structure of isoxazoline compounds formed via the reaction of alkyl-substituted benzonitrile oxides with ethylene was determined by X-ray diffraction method. Isoxazoline ring is flattened, the bond lengths in it depend slightly on the nature of substituents (CH3, C2H5) and their position in the benzene ring and the angle of rotation relative to the isoxazoline ring. The connection N-O has a length 1.422 Å. Thermal decomposition of isoxazolines in a liquid phase (160–280°C) is accompanied by the release of acetaldehyde and aromatic nitrile. Both the structure of the cycle and its stability is practically independent of the structure of an aromatic substituent. The rate constant of the initial stage is characterized by the low significance of kinetic parameters, E = 104°8 kJ mol−1 and log a(A/c) = 7.2±0.8. The results obtained are rationalized in terms of biradical mechanism of isoxazoline ring-opening that includes an efficient recombination of the biradical and its disappearance as a result of synchronous multi-center rearrangement with the release of acetaldehyde.