Objectives. The work set out to synthesize tertiary amines comprising derivatives of morpholine and piperidine containing a 1,3-dioxolane or gem-dichlorocyclopropane fragment, as well as quaternary ammonium salts based on them. In order to determine the process conditions (duration and temperature of the reaction) under which the maximum possible yield of the target quaternary ammonium salts is achieved, the effect of the halide structure on the yield of tert-amines and their subsequent salts was evaluated. The study also aimed to establish the structural and spatial structure of the obtained carbo- and heterocyclic amines and salts based on them, as well as to evaluate the anticorrosive properties of the obtained products in a hydrogen sulfide medium.

   Methods. The target compounds, such as tertiary amines and quaternary ammonium salts (QAS), were obtained by classical methods of organic synthesis consisting of alkylation and condensation of the corresponding amines of various structures. Preparation of QAS was carried out using a microwave system for organic synthesis via microwave activation on a Sineo device (China). The qualitative and quantitative composition of the reaction masses was determined using gas–liquid chromatography (Crystal 2000 hardware and software complex), while mass spectroscopy was carried out on a Chromatec-Crystal 5000M device with a NIST 2012 database). A Bruker AM-500 device having operating frequencies of 500 and 125 MHz was used to perform nuclear magnetic resonance spectroscopy.

   Results. Tertiary amines containing a cycloacetal or gem-dichlorocyclopropane fragment were obtained under thermal heating conditions. By carrying out their condensation in excess halides using microwave radiation, new quaternary ammonium salts were synthesized with a yield close to quantitative. Anticorrosive activity was estimated for the obtained cyclic compounds. 4-Allyl-4-[2-(1,3-dioxolan-2-yl)-ethyl]morpholinium chloride was determined to have the maximum protective effect in a hydrogen sulfide medium with a protection level of 91 %.

   Conclusions. Tertiary amines containing a cycloacetal or gem-dichlorocyclopropane fragment were obtained under the proposed conditions. Such substances are in demand as intermediates in the synthesis of quaternary ammonium salts having anticorrosive activity.

   Objectives. The work set out to prepare and chromatographically analyze pentaerythritol esters, use gas chromatography to determine the Kováts logarithmic retention indices and enthalpies of sorption, and evaluate the enthalpy of evaporation of pentaerythritol tetraesters based on linear correlations with enthalpies of sorption and logarithmic retention indices.

   Methods. The synthesis was carried out in an isothermal stirred reactor at T = 393.2 K at a molar ratio of pentaerythritol to carboxy lic acid of 1 : 4 in self-catalysis mode to avoid side reactions that occur during aggressive acid catalysis. The obtained samples were analyzed using Chromatec Analytic hardware and software complex based on a Kristall-2000M chromatograph equipped with a capillary column (60 m × 0.32 mm × 0.5 μm) having BP-1 grafted stationary phase (100 % dimethylpolysiloxane). The analysis conditions were as follows: isothermal mode; column temperature, 433.2–603.2 K; evaporator and detector temperatures, 623.2 K; gas flow split, 1 : 50; carrier gas, helium; volume of injected sample, 0.15 µL; diluent of reaction samples, methanol.

   Results. For the first time, the values of the Kováts retention indices and enthalpies of sorption were found for 31 pentaerythritol esters of various structures (mono-, di-, tri-, and tetramethanoates; 2-methylpentanoates; 4-methylpentanoates; 2,2-dimethylbutanoates; 2-ethylbutanoates; octanoates; nanoates; and decanoates). The obtained correlation equations were used to estimate the enthalpy of evaporation of pentaerythritol tetraesters (for 7 compounds, data were obtained for the first time).

   Conclusions. The retention parameters were found as linear dependencies with a high degree of correlation (R² > 0.99) in the studied temperature range (433.2–603.2 K). The enthalpies of evaporation calculated based on the enthalpies of sorption and logarithmic retention indices within the limits of error of the correlation dependencies coincide with the literature data and the values predicted by the quantitative structure–property relationship method. The obtained data can be used to design units for separating multicomponent mixtures and identify these compounds.

   Objectives. 2-Chloroethyl phenylsulfide (2-CEPS) is a relevant simulant of chemical warfare sulfur mustard gas (yperit) as part of an environmentally-friendly decontamination processes. This study presents the initial results of research the catalytic ability of tungstate in the conversion process of 2-CEPS.

   Methods. The decontamination system employed in this study comprised hydrogen peroxide (H₂O₂), potassium tungstate acting as a metal transition salt catalyst, a surfactant, and organic solvents. The research investigated the impact of K₂WO₄ concentration on the conversion efficiency and rate of the target compound. As well as additionally exploring the influence of the substrate-to-catalyst ratio on the reaction pathway, the study evaluated the stability of the detoxifying mixture.

   Results. Increasing the concentration of K2WO4 is shown to lead to an increase in the efficiency and conversion rate of 2-CEPS. As well as demonstrating stability and durability, the catalyst did not cause unwanted H₂O₂ breakdown. After 18 h of mixing, the conversion retained efficiency above 95 % within 15 min of the reaction. The degradation kinetics follow a pseudo-first-order model, indicating that the reaction rate is directly influenced by the K₂WO₄ concentration. In addition to enhancing the oxidative capacity of the solution, increased tungstate concentration promotes the formation of undesirable sulfone byproducts.

   Conclusions. The study investigated the catalytic activity of tungstate within an eco-friendly solution formulated to degrade 2-CEPS. Our findings demonstrate a strong correlation between the concentration of potassium tungstate (K₂WO₄) and the rate of 2-CEPS degradation. A key advantage of tungstate is its exceptional stability and durability as a catalyst. Efficient decontamination is ensured thanks to its minimal interference with the stability of hydrogen peroxide (H₂O₂).

   Objectives. The work set out to describe conditions for the purification of a model fermentation broth for cultivating the lactic acid-containing micromycete Rhizopus oryzae from impurities of inorganic salts using ion-exchange resins under dynamic conditions.

   Methods. The solutions collected for analysis were examined using precipitation titration to determine the concentration of chlorides along with a qualitative reaction with Nessler’s reagent to ascertain the presence of ammonium ions. The concentration of lactic acid was evaluated spectrophotometrically using iron(III) chloride. The total nitrogen content was determined by high-temperature catalytic combustion on a Formacs HT TOC/TN Analyzer (Netherlands). The content of trace elements and macroelements in the samples was determined using an iCAP 6300 Duo inductively coupled plasma emission spectrometer (United Kingdom).

   Results. Purification of the model broth under the described conditions was carried out by successive filtration through the cation exchanger KU-2-8 in the H-form and subsequently through a mixture of weakly basic A847 and strongly basic AV-17-8 anion exchangers in the OH-form taken in a one-to-one ratio. The breakthrough of impurity ions into the solution was shown to occur after passing 30-fold and 10-fold volumes of the model broth relative to the volume of the cation-exchange and anion-exchange resins, respectively. The dynamic exchange capacity prior to breakthrough was determined as follows: 0.35 mmol-eq/cm³ for the anion-exchange column and 1.61 mmol-eq/cm³ for the cation-exchange column. The following parameters were defined as column regeneration modes: 3-fold excess of 2 M H₂SO₄, 10-fold excess of distilled H₂O for cation exchange; for anion exchange, 3-fold excess of 2 M NaOH and 20-fold excess of H₂O.

   Conclusions. The conducted studies showed that purification of the model fermentation broth of Rhizopus oryzae can be successfully implemented using ion-exchange resins. The model fermentation broth passing successively through cation-exchange and anion-exchange columns was shown to be purified from impurities of mineral salts while maintaining the concentration of lactic acid.

   Objectives. The study set out to investigate the effect of ureas and their sulfur- and selenium-containing analogs on the vulcanization of elastomeric materials based on nitrile butadiene rubber and their resistance to thermo-oxidative aging.

   Methods. The properties of the molecules of ureas under study were calculated by the MM+ quantum chemical method of molecular mechanics and PM3 semiempirical method using the HyperChem 8.0 software. Vulcanization of rubbers and total crosslink density were studied using the rotorless vulcanization method with a MonTech MDR 3000 Professional rheometer. The dynamic characteristics of vulcanized rubbers were investigated in accordance with ASTM D6601-02 and D5992-96 standards. The efficiency of the studied antioxidants against thermo-oxidative aging was evaluated in accordance with GOST 9.024-74. Infrared (IR) spectra of samples were recorded with an FT-801 Fourier-transform IR spectrometer (Russia) according to the attenuated total reflection method.

   Results. For the first time, a study was conducted on the efficiency of 1-(3-chlorophenyl)-3-phenylurea, 1-(3-chlorophenyl)-3-phenylthiourea, and 1-(3-fluorophenyl)-3-phenylselenourea as antioxidants for elastomers under conditions of thermo-oxidative aging. The effect of these substances on the vulcanization characteristics and total crosslink density of materials based on nitrile butadiene rubber was investigated.

   Conclusions. The values of electron affinity energy and its sign were shown to accurately predict the possibility of using individual molecules as accelerators of the vulcanization process or antioxidants. With a change in the electron affinity energy from 0.051 (urea) to −1.115 (thiourea) and −1.365 eV (selenourea), the time to the start of vulcanization was shown to change from 15 to 3 and 2 min, respectively. As a result of thermo-oxidative aging of rubbers based on BNKS-28 AN rubber without a stabilizer and with 1-(3-chlorophenyl)-3-phenylurea, 1-(3-chlorophenyl)-3-phenylthiourea, and 1-(3-fluorophenyl)-3-phenylselenourea, the total crosslink density changes by 33 %, 23 %, 25 %, and 29 %, respectively. In this connection, the use of 1-(3-chlorophenyl)-3-phenylurea somewhat improves the stability of rubbers to thermo-oxidative aging, whereas 1-(3-chlorophenyl)-3-phenylthiourea and 1-(3-fluorophenyl)-3-phenylselenourea do not worsen this property when introduced into the rubber compound.

   Objectives. The authors synthesize complex oxide phases of the composition Eu_2−xGdxZr₂O₇ and Eu_2−xGd_xHf₂O₇ at x = 0.5, 1.0, 1.5 under microwave heating conditions and investigate their phase composition, particle size distribution, and specific surface with the purpose of obtaining bulk ceramic materials on their basis and study their behavior when heated to 1473 K.

   Methods. Using X-ray phase analysis, the phase composition of samples subjected to heat treatment at temperatures of 1473 and 1773 K was studied, and the cell parameters were calculated. The particle size of the obtained powders was analyzed by laser diffraction on a Fritsch Analysette 22 device. The specific surface area was studied by the Brunauer–Emmett–Teller method on a TriStar 3000 analyzer. Bulk ceramic materials were obtained by cold pressing with subsequent sintering at 1773 K. The coefficient of thermal expansion (CTE) of ceramic samples was studied on a Netzsch DIL 402C dilatometer in a temperature range of 300–1473 K.

   Results. At a temperature of 1473 K, all synthesized samples were observed to form a fluorite structure; at a temperature of 1773 K, samples with the composition Eu_2−xGd_xHf₂O₇ had an ordered pyrochlore structure. With an increase in the gadolinium content in the samples, a decrease in both the unit cell parameter and the CTE was observed. The particle size of almost all samples did not exceed 100 μm; the specific surface area did not exceed 1 m²/g.

   Conclusions. For the first time, compounds with the composition Eu_2−xGdxZr₂O₇ and Eu_2−xGd_xHf₂O₇ were obtained using microwave processing at x = 0.5, 1.0, 1.5. As well as determining the dependence of the phase composition on the heat treatment temperature after microwave exposure, the dependence of the change in the unit cell parameters on the gadolinium content in the sample was studied, the particle size distribution was investigated. The CTEs of bulk ceramic samples obtained by cold pressing were additionally studied. The obtained data can be used in the development of thermal barrier coatings and technical ceramics used at high temperatures (up to 1473 K).

   Objectives. The study set out to investigate the possibility of production strontium hexaferrite permanent magnets using powder injection molding (PIM) technology, which involves casting granules highly filled with ceramic powder. After obtaining the initial granulate based on organic binders and strontium hexaferrite powder, the material was cast in an injection molding machine to create the first intermediate (green) parts, followed by removal of the primary binder to obtain brown parts and final sintering.

   Methods. Strontium hexaferrite powder was obtained by the ceramic method. The material underwent grinding in a planetary ball mill to obtain a powder having an average particle size of 13.4 μm, which is considered optimal for the applied PIM technology. Granulate materials, consisting of the obtained strontium hexaferrite powder combined with primary paraffin and secondary polyamide binders, were prepared by manual mixing of the components and used for creation of green parts in injection molding machine. Brown parts obtained following removal of binder from the obtained green parts were characterized by their higher brittleness and open pore structure. Permanent magnets with dimensions of 10 × 10 × 5 mm were obtained following sintering of brown parts in an oxidizing atmosphere.

   Results. The more than 70% higher strength of the magnetic properties of the obtained strontium hexaferrite samples compared to isotropic barium hexaferrite-based magnets manufactured in accordance with GOST 24063-80 is due to the presence of pores after sintering.

   Conclusions. The possibility of using the ceramic method for producing strontium hexaferrite powder for use in granulate manufacturing was demonstrated. This raw material can then be used to obtain strontium hexaferrite permanent magnets via PIM technology having 80 % density.

   Objectives. To develop and validate a method for the quantitative determination of 8-methoxypsoralen in a soft dosage form in accordance with the requirements of the State Pharmacopoeia of the Russian Federation, 15^th edition, and the Pharmacopoeia of the Eurasian Economic Union.

   Methods. Quantitative determination of 8-methoxypsoralen was performed by high-performance liquid chromatography on a Chromaster 5000 (Hitachi, Japan) with a diode array detector. Chromatography was performed on a Kromasil EternityXT-5-C18, 5 μm, 250 × 4.6 mm column in isocratic mode with a mobile phase of acetonitrile/water in a ratio of 50 : 50 % (v/v). The flow rate was 1.0 mL/min, while the detection wavelength was 250 nm.

   Results. The optimal condition for the extraction of 8-methoxypsoralen was found to be ultrasonic gel extraction at 40 °C for 15 min using acetonitrile. The best peak resolution of 8-methoxypsoralen was achieved during gel analysis at 250 nm using a reversed-phase sorbent with an octadecyl phase (C₁₈) grafted onto silica gel. The acetonitrile/water mixture was used as a mobile phase in a volume ratio of 50 : 50 % to minimize chromatography time while maintaining optimal resolution. From the validation procedures, it was confirmed that the method is specific, linear (R² > 0.997) and reproducible (relative standard deviation was ≤ 3.0 %). The accuracy of the analytical method was from 98.26 % to 101.02%, while the values of the detection and quantitative determination limits were 0.006 and 0.020 μg/mL, respectively. The developed quantitative determination method demonstrated its stability when varying as the column temperature and flow rate by ±5 %.

   Conclusions. As effectively implemented using the high-performance liquid chromatography method, the method for quantitative determination of 8-methoxypsoralen has a number of advantages over the previously described methods, including reduced analysis time, as well as increased sensitivity and effectiveness, which makes it possible to apply the developed method in assessing the quantitative content of 8-methoxypsoralen in a soft dosage form—gel for the treatment of psoriasis.