PROPELLANS – PERSPECTIVE FRAME COMPOUNDS FOR THE CREATION OF HIGH-ENERGY SUBSTANCES

Гетероциклические соединения вызывают большой интерес у исследователей как потенциальные соединения в создании биологически активный веществ или веществ с высокой энергией. 3,7,10-Триоксо-2,4,6,8,9,11-гексааза[3.3.3]пропеллан (ТНАР) состоит из трех конденсированных колец, соединенных одинарной связью C1-C5 является новым, малоизученным веществом, синтезированным во втором десятилетии XXI века. Теоретические расчеты энергий нитропроизводных пропелланов с пятью или шестью атомами азота показали перспективность использования в качестве высокоэнергетических веществ. Целью работы было проведение квантово-химических расчетов теплоты образования и сгорания, а также длины пропеллановой связи нитро- и ацетилпроизводных 3,7,10-триоксо-2,4,6,8,9,11-гексааза[3.3.3]пропеллана и его восстановленного аналога 2,4,6,8,9,11-гексааза[3.3.3]пропеллана (НАР) с различным количеством заместителей. В результате исследовательской работы была выявлена следующая закономерность: последовательное введение нитрогрупп в изучаемую структуру увеличивает теплоты образования получаемых производных, тогда как для ацетильных групп тенденция противоположная. Оказалось, что гексанитропроизводное ТНАР по термодинамической стабильности сравнимо с гексанитробензолом, а восстановленный пропеллан НАР с шестью нитрогруппами сравним с CL-20. Поведение длины пропеллановой связи C1-C5 при последовательном замещении соединения ТНАР нитро- и ацетильными группами. Накопление ацетильных групп вызывает монотонное укорочение этой связи, вплоть до обычной длины C(sp3)-C(sp3). В случае нитрогрупп тенденция более сложная: сначала укорочение, а затем значительное удлинение, до 1.67 Å для шести нитрогрупп в 3,7,10-триоксо-2,4,6,8,9,11-гексанитро-2,4,6,8,9,11-гексааза[3.3.3]пропеллане. Гексаазапропеллан (НАР), несмотря на нежесткую структуру, имеет 22 стабильных конформера, тогда как у ТНАР их 2, и более короткие связи, что вероятно в дальнейшем позволит синтезировать его гексанитро производное. Heterocyclic compounds are of great interest to researchers as potential compounds in the creation of biologically active substances or substances with high energy. 3,7,10-Trioxo-2,4,6,8,9,11-hexaaza[3.3.3]propellane (THAP) consists of three condensed rings connected by a single C1-C5 bond, is a new, poorly studied substance synthesized in the second decade of the 21st century. Theoretical calculations of the energies of nitro-derivatives of propellanes with five or six nitrogen atoms have shown that they are promising for use as high-energy substances. The aim of the work was to carry out quantum-chemical calculations of the heats of formation and combustion, as well as the length of the propellane bond of nitro- and acetyl derivatives of 3,7,10-trioxo-2,4,6,8,9,11-hexaaza[3.3.3]propellane, as well as its reduced analogue 2,4,6,8,9,11-hexaaza[3.3.3]propellane (HAP) with a different number of substitutes. As a result of the research work, the following regularity was revealed: the successive introduction of nitro groups into the structure under study increases the heats of formation of the resulting derivatives, while the trend is opposite for acetyl groups. It turned out that the hexanitro derivative of THAP is comparable in thermodynamic stability to hexanitrobenzene, and the reduced propellane (HAP) with six nitro groups is comparable to CL-20. Behavior of the C1-C5 propellane bond length upon successive substitution of THAP compound with nitro- and acetyl groups. The accumulation of acetyl groups causes a monotonic shortening of this bond, up to the usual length of C(sp3)-C(sp3). In the case of nitro groups, the trend is more complex: first, shortening and then significant lengthening, up to 1.67 Å for six nitro groups in 3,7,10-trioxo-2,4,6,8,9,11-hexanitro-2,4,6, 8,9,11-hexaaza[3.3.3]propellane. Hexaazapropellane (HAP), despite its non-rigid structure, has 22 stable conformers, whereas THAP has two, and shorter bonds, which is likely to make it possible to synthesize its hexanitro derivative in the future.

Solid-Phase “Self-Hydrolysis” of [Zn(NH3)4MoO4@2H2O] Involving Enclathrated Water—An Easy Route to a Layered Basic Ammonium Zinc Molybdate Coordination Polymer

An aerial humidity-induced solid-phase hydrolytic transformation of the [Zn(NH3)4]MoO4@2H2O (compound 1@2H2O) with the formation of [(NH4)xH(1−x)Zn(OH)(MoO4)]n (x = 0.92–0.94) coordination polymer (formally NH4Zn(OH)MoO4, compound 2) is described. Based on the isostructural relationship, the powder XRD indicates that the crystal lattice of compound 1@2H2O contains a hydrogen-bonded network of tetraamminezinc (2+) and molybdate (2−) ions, and there are cavities (O4N4(μ-H12) cube) occupied by the two water molecules, which stabilize the crystal structure. Several observations indicate that the water molecules have no fixed positions in the lattice voids; instead, the cavity provides a neighborhood similar to those in clathrates. The @ symbol in the notation is intended to emphasize that the H2O in this compound is enclathrated rather than being water of crystallization. Yet, signs of temperature-dependent dynamic interactions with the wall of the cages can be detected, and 1@2H2O easily releases its water content even on standing and yields compound 2. Surprisingly, hydrolysis products of 1 were observed even in the absence of aerial humidity, which suggests a unique solid-phase quasi-intramolecular hydrolysis. A mechanism involving successive substitution of the ammonia ligands by water molecules and ammonia release is proposed. An ESR study of the Cu-doped compound 2 (2#dotCu) showed that this complex consists of two different Cu2+(Zn2+) environments in the polymeric structure. Thermal decomposition of compounds 1 and 2 results in ZnMoO4 with similar specific surface area and morphology. The ZnMoO4 samples prepared from compounds 1 and 2 and compound 2 in itself are active photocatalysts in the degradation of Congo Red dye. IR, Raman, and UV studies on compounds 1@2H2O and 2 are discussed in detail.

The Reaction of Hydrogen Halides with Tetrahydroborate Anion and Hexahydro-Closo-Hexaborate Dianion

The mechanism of the consecutive halogenation of the tetrahydroborate anion [BH4]− by hydrogen halides (HX, X = F, Cl, Br) and hexahydro-closo-hexaborate dianion [B6H6]2− by HCl via electrophile-induced nucleophilic substitution (EINS) was established by ab initio DFT calculations [M06/6-311++G(d,p) and wB97XD/6-311++G(d,p)] in acetonitrile (MeCN), taking into account non-specific solvent effects (SMD model). Successive substitution of H− by X− resulted in increased electron deficiency of borohydrides and changes in the character of boron atoms from nucleophilic to highly electrophilic. This, in turn, increased the tendency of the B–H bond to transfer a proton rather than a hydride ion. Thus, the regularities established suggested that it should be possible to carry out halogenation more selectively with the targeted synthesis of halogen derivatives with a low degree of substitution, by stabilization of H2 complex, or by carrying out a nucleophilic substitution of B–H bonds activated by interaction with Lewis acids (BL3).

Flash Calculation Using Successive Substitution Accelerated by the General Dominant Eigenvalue Method in Reduced-Variable Space: Comparison and New Insights

Summary On the basis of a previously published reduced-variables method, we demonstrate that using these reduced variables can substantially accelerate the conventional successive-substitution iterations in solving two-phase flash (TPF) problems. By applying the general dominant eigenvalue method (GDEM) to the successive-substitution iterations in terms of the reduced variables, we obtained a highly efficient solution for the TPF problem. We refer to this solution as Reduced-GDEM. The Reduced-GDEM algorithm is then extensively compared with more than 10 linear-acceleration and Newton-Raphson (NR)-type algorithms. The initial equilibrium ratio for flash calculation is generated from reliable phase-stability analysis (PSA). We propose a series of indicators to interpret the PSA results. Two new insights were obtained from the speed comparison among various algorithms and the PSA. First, the speed and robustness of the Reduced-GDEM algorithm are of the same level as that of the reduced-variables NR flash algorithm, which has previously been proved to be the fastest flash algorithm. Second, two-side phase-stability-analysis results indicate that the conventional successive-substitution phase-stability algorithm is time consuming (but robust) at pressures and temperatures near the stability-test limit locus in the single-phase region and near the spinodal in the two-phase region.

Improved Multiple-Mixing-Cell Method for Accelerating Minimum Miscibility Pressure Calculations

Summary An improved algorithm for accelerating minimum miscibility pressure (MMP) computation using the multiple-mixing-cell (MMC) methods is presented. The MMC method is widely used to accurately calculate the MMP. In this study, we proposed an acceleration algorithm toward original MMC method to directly locate the shortest key tie-line (TL) after a certain amount of contacts through the adjustment of the gas/oil mixing ratio during the calculation process. The algorithm contains the following key components: (1) mixing cell cutoff strategy to avoid unnecessary flash calculations; (2) gas/oil mixing ratio adjustment to prevent lost information on the shortest key TL during the cell cutoff process; (3) a search algorithm for pressure to improve the next step pressure estimate; (4) the fast and reliable two-phase flash implementation by combining full Newton method with recently proposed iteration variables and conventional successive substitution method. The improved MMC model is shown to be faster than the original MMC method in computing MMP.

SOLUTIONS IN EXPLICIT FORM FOR DETERMINING THE HYDRAULIC RESISTANCE COEFFICIENT FOR TURBULENT FLOW

A comparative analysis of explicit solutions of the Colebrook-White equation is carried out. The median values of relative deviations, coefficients of determination and computational complexities for each approximation were obtained. The results of the iterative solution of the Colebrook-White equation by successive substitution method were used as the intrinsic solution. Approximations by B. Eck and A.R. Vatankhah were identified as the most effective in terms of computational complexity. It was shown that widely used approximations by P.R.H. Blasius, A.D. Altshul and J. Nikuradze although simple, provide acceptable accuracy only within restricted ranges of Reynolds and relative roughness.

Numerical Modeling of CO2, Water, Sodium Chloride, and Magnesium Carbonates Equilibrium to High Temperature and Pressure

In this work, a thermodynamic model of CO2-H2O-NaCl-MgCO3 systems is developed. The new model is applicable for 0–200 °C, 1–1000 bar and halite concentration up to saturation. The Pitzer model is used to calculate aqueous species activity coefficients and the Peng–Robinson model is used to calculate fugacity coefficients of gaseous phase species. Non-linear equations of chemical potentials, mass conservation, and charge conservation are solved by successive substitution method to achieve phase existence, species molality, pH of water, etc., at equilibrium conditions. From the calculated results of CO2-H2O-NaCl-MgCO3 systems with the new model, it can be concluded that (1) temperature effects are different for different MgCO3 minerals; landfordite solubility increases with temperature; with temperature increasing, nesquehonite solubility decreases first and then increases at given pressure; (2) CO2 dissolution in water can significantly enhance the dissolution of MgCO3 minerals, while MgCO3 influences on CO2 solubility can be ignored; (3) MgCO3 dissolution in water will buffer the pH reduction due to CO2 dissolution.

СИСТЕМА ЗАЩИЩЕННОГО ГОЛОСОВОГО УПРАВЛЕНИЯ БЕСПИЛОТНЫМ ЛЕТАТЕЛЬНЫМ АППАРАТОМ

The article proposes and investigates the system of protected voice radio control by the functions of an unmanned aerial vehicle, which is based on the first developed method of secure transmission of voice commands of radio control and the idea of voice authentication of legal subjects of management, where only the voice radio channel is used to transmit control information, thereby allowing the system to be implemented in existing voice radio systems, where on the betraying side is the subject of control, and as a receiver an unmanned aerial vehicle that performs the spoken voice commands. The proposed idea makes it possible to significantly complicate the struggle of malefactors with this kind of systems, since the frequencies at which the voice mobile radio is operating are in common use, and means fighting with this kind of systems will result in the failure of public voice mobile communications. The system of protected voice control of an unmanned aerial vehicle makes it possible to ensure sufficient confidentiality of the transmitted voice commands from the interception of information with the purpose of illegally capturing or destroying an unmanned aerial vehicle throughout the flight. For the first time, the method of voice authentication of legal subjects of management based on the idea of successive substitution of the authentication parameters of the control subject for each subsequent voice command on the authentication parameters from the database, the sequence of which was performed before the flight in a pseudorandom manner and synchronized. The expediency of using the presented system of protected voice radio control functions of an unmanned aerial vehicle is substantiated and experimentally proved. The results of automatic recognition of voice control commands are evaluated using a classifier constructed using the minimum distance criterion, where the decision on the positive identification of voice commands is made by the criterion of a minimum variance in a given threshold of acceptable recognition. The obtained results of experimental research allow to draw a conclusion about the expediency of further practical application of the presented system of protected voice radio control by the functions of an unmanned aerial vehicle