New ion exchangers based on polyacrylonitrile fiber were obtained by catalytic amination of nitrile groups with tetraethylenepentaamine and pentaethylenehexaamine. Chelating ion exchangers with aminodiacetic functional groups were obtained on the base of these materials. The acid-base parameters of the functional groups of obtained ion exchangers were determined by potentiometric titration: initial polyampholytes have a high anion exchange capacity (E_b = 4.5–5.5 m-eq/g) distributed between three types of groups with pK_a equal to 3.3, 6.2 and 9.2, and a cation exchange capacity with E_a ≈ 1 m-eq/g and pK_a ≈ 10.7; chelating ion exchangers on their base contain three types of acid groups with pK_a approximately equal to 3.5, 6.0, 10.5 and two types of anion-exchange groups with pK_a equal to 2.0 and 6.0. Initial polyampholytes have a high efficiency in the processes of air purification from acidic impurities (experimental data for sulfur dioxide), chelating ion exchangers – in the processes of water purification from heavy metal ions.

The process of thermal activation of a carbon fiber supported with palladium-copper-iron-containing catalysts has been studied by means of DSC and TGA in air and in nitrogen. The presence of the exoeffect during calcination due to the interaction of the copper (II) nitrate decomposition products with the carbon carrier was detected. Aforementioned exoeffect leads to spontaneous heating and combustion of the sample in air. The XPS and catalytic experiments showed that calcination of the catalyst in nitrogen leads to the formation of low-activity reaction centers. Oxygen plays an important role in the formation of the active phase, so the thermal activation of catalyst should be carried out in the air.

Besides the theoretical value, the study of radiation-chemical carboxylation of the indole-alanine system is caused by the possibility of its use for obtaining an essential amino acid – tryptophan. In the previous paper an impact of the acceptors of charge − diphenyl and hydrogen peroxide – on the kinetics of radiolysis of the system: water, alcohol, indole, serine was studied. [1]. It was determined, that the solvated electron plays a decisive role in a mechanism of tryptophan formation. The purpose of this paper is to formulate a quantitative model of tryptophan radiation synthesis by the example of water-alcohol solution of the indole and alanine. The radiolysis was performed by γ–rays of the radioactive isotope 60-Сo at the UGU-420A facility under static conditions at the dose rate 1.2 Gy/s. The system in question, which consists of 0.1M of the alcoholic solution of indole and 0,1M of aqueous solution of alanine at the ratio 1:1, saturated with carbon and exposed to radiation treatment, was investigated by means of thin-layer chromatography for amino acids determining.

The error of determination was ± 5 %. By the method of ascending paper chromatography with subsequent quantitative determination, tryptophan was detected in the irradiated solution. The dependence of tryptophan concentration on a dose during radiation-chemical carboxylation in the indole-alanine system was demonstrated. Based on the obtained experimental and calculated values of radiation-chemical output of β-indolylmaleimide acid (tryptophan), theoretical model that satisfactorily describes the experimental data was established.

The possibility to determine iodide ions by stripping voltammetry has been demonstrated in multivitamin preparations against the background of redox active components with a concentration exceeding the iodide content of 600–1000 (ascorbic acid), 8–20 (thiamine, riboflavin), 20–40 (iron ions), 10–12 (manganese ions), 4–6 (copper ions) times. The method is based on the anodic concentration of iodide in the form of mercury iodide Hg₂I₂ on an amalgamated silver indicator electrode at a potential of 0.0 V (vs. Ag/AgCl reference electrode), followed by recording the cathode current peak in a potentiodynamic voltammogram in 0.4 mol/dm³ formic acid aqueous solution in the range of electrode potential from +0.1 to–0.7 V. The method is applicable for the determination of iodide ions in a solution with 0.5–100 μg/dm³ concentration; the relative standard deviation decreases from 6.1 to 3.2 % with an increase in the concentration of iodide from 0.5 to 5.0 μg/dm³, and in the range of 10–100 μg/dm3 is 2.4–3 %.

Extraction of polycyclic aromatic hydrocarbons (PAHs) containing from two till six cycles in the molecule, both sequestered and isolated, with previously unexplored n-hexane – polar organic solvent systems: propylene glycol, triethylene glycol, tetraethylene glycol, sulfolane and mixtures of dimethylformamide with water has been studied. Extraction of some previously unexplored aromatic hydrocarbons often presented in pyrolysis mixtures (indene, 2-methylnaphthalene, biphenyl, 2-ethylnaphthalene, 2-ethenylnaphthalene, biphenylene, diphenylmethane) in n-hexane-polar organic solvent systems has been studied as well. The dependences of the distribution constants on the structure of PAH molecules and the nature of the polar solvent were found to complement the previously established patterns. The most effective and selective solvents for PAHs extraction from pyrolysis mixtures have been suggested.

A procedure of extraction purification of picric acid from impurities of dinitrophenols with diethyl ether at pH = 3 has been developed. Purified picric acid was used to determine the creatinine by the Jaffe reaction on model systems and the extraction-photometric determination of the basic substance in higher quaternary ammonium (QAS) and amine impurities in them. It was shown that both the purity and the concentration of picric acid affect the sensitivity of the creatinine quantification. It was found that to determine creatinine, a solution of HPic with a concentration of 0,035 mol/l should be used. The determination of amines in the QAS and basic substance is also necessary to be carried out only with purified picric acid to avoid distortion of the results.

The synthesis of new chalcones with potential biological activity, including the reactions of chloromethylation, N-alkylation, Claisen-Schmidt condensation, was carried out. The compounds obtained contain an isoxazole moiety in their structure.

Compounds that contain an indole cycle in their structure have biological activity and are a source for the development of new medicinal products. N-acetyl-3-indolinones are actively used as incoming substance for their organic synthesis. Preparative methods for the obtaining of N-acetyl-3-indolinones, used as incoming substances for the synthesis of condensed indole derivatives with high therapeutic activity, have been developed. Synthesis of N-acetyl-3-indolinone was performed by deacetylation and cyclization of N-(2-carboxyphenyl) glycine and its 4-bromo-derivative to form N,O-diacetylindoxyls followed by hydrolysis of the obtained compounds to target indolinones. It was established that brominated derivatives have increased stability as compared with the analogues which do not contain bromine on the benzene ring of the indole nucleus, resulting in the increase in the yield of desired products in the reaction.

3-Isobutylhexahydropyrrolo[1,2-a]pyrazine-1,4-dione, [cyclo(prolyl-leucyl)], which has a wide range of biological effects, was obtained by thermolysis both the L-prolyl-L-leucine methyl ester and the methyl ester L-leucyl-L-proline, for the synthesis of which the removal of tert-butyloxycarbonyl amino protecting groups in tert-butyloxycarbonylprolyl-leucine methyl ester and tert-butyloxycarbonylleucyl-proline methyl ester under the action of a methanolic solution of hydrogen chloride and the treatment of the resulting of methyl esters hydrochlorides L-prolyl-L-leucine and L-leucyl-L-proline with an equimolar amount of triethylamine were used. The starting tert-butyloxycarbonylleucyl-proline methyl ester was prepared like the previously synthesized tert-butyloxycarbonylprolyl-leucine methyl ester by the carbodiimide method. It was found that the cyclization of the methyl ester of L-leucyl-L-proline into the desired diketopiperazine proceeds at a lower temperature than the cyclization of the methyl ester of L-prolyl-L-leucine.

A reagent kit EIA-OCHRATOXIN A for the determination of mycotoxin ochratoxin A in feeds and foods by a  direct  competitive  enzyme  immunoassay  using  microtitration  plate  has  been  developed  and  tested.  The  conjugate of ochratoxin A with horseradish peroxidase was synthesized using the mycotoxin aminoderivative joined to the carbohydrate chain of the enzyme. A monoclonal antibody to the mycotoxin was immobilized on the surface of plate wells through sheep anti-mouse antibodies. The evaluated parameters of the kit and metrological characteristics of the technique of measurements correspond to the modern level of immunoassay development and provide the determination of ochratoxin A content of agricultural products in a range of 5 to 375 mg/kg with proper accuracy and precision. The limit of quantitative determination of ochratoxin A in grain and cereal foods does not exceed 5 mg/kg.

The process of lignin phosphorylation in a medium of phosphoric acid and urea has been studied. The product prepared contains 1.3– 6.8 % phosphorus, 0.3–2.3 % nitrogen and has an ion exchange capacity of 0.7 to 2.8 mg-ekv•g^–1 of Na⁺, to 1.8–2.3 mg-ekv•g^–1 with respect to Ni²⁺ and 2.6 –2.8 mg-ekv•g^–1 to UО₂²⁺. The product of thermal decomposition of lignin phosphate at 500 °C actively absorbs benzene vapor (sorption value of 0.42–0.52 sm³•g^–1) and has a Na⁺ ion exchange capacity of 2.8 mg-ekv•g^–1.

Influence of cooling and mixing rate on the process of schoenite crystallization from saturated salt solutions was investigated in laboratory conditions. It was established that as the system’s cooling rate and mixing speed increase, a significant decrease of the induction period of schoenite crystallization is observed. Fivefold increase of the cooling rate increases sizes of schoenite crystals by an average of 2.5–3.0. Mixing rate increase leads to the formation of a fine crystalline precipitate (crystal size 10−20 μm).

A study of treatment of polyhalite ore was conducted by the method of washing halite using water as a washing liquid. The optimal conditions for washing halite from polyhalite ore (water consumption and temperature, contact time of the solid and liquid phases, ore grinding degree) were determined, providing the production of pure polyhalite and filtrate close to saturation with sodium chloride at low polyhalite losses.

A new nitrogen-containing product based on tall oil rosin, adipic acid and diethylenetriamine is capable of simultaneously exerting a strengthening and hydrophobizing effect on paper and cardboard made both from primary (cellulose) and secondary (waste paper) fibers. The strengthening effect is due to the presence in its structure of nitrogen-containing groups –NH₂ and –NH– capable of forming additional interfiber bonds with negatively charged hydroxyl groups of cellulose macromolecules. Hydrophobizing effect is provided by resin acids included in the product. Preparation of the product with preset physicochemical properties (acid number not more than 40 mg KOH/g, solubility in water, cationic character and thermal stability at a temperature of at least 135 °C) was carried out in three stages. The first stage is the tall oil resin acids modification with diethylenetriamine; the second stage is the polycondensation of the resin acid amides obtained in the first stage with adipic acid and diethylenetriamine; the final stage is water dilution of the product formed in the second stage, to a solids content of 10–12 %. In paper masses containing primary and secondary fibers glued with alkylketene dimers (Fennosize KD 225 YP), the replacement of the import strengthening agent (cationic starch Hi-Cat) with a new nitrogen-containing product allows us, first, to increase the dry strength of paper and cardboard and improve hydrophobicity and, secondly, to prevent undesirable process of “sticking” when storing paper samples (elementary layers of cardboard).

The development of organometallic chemistry of metallocenes, in particular, the chemistry of organic derivatives of iron, manganese, titanium and niobium, is explained by their diverse catalytic activity with respect to polymerization reactions, isomerization and hydrogenation of olefins, cyclotrimerization of acetylene hydrocarbons, fixation of molecular nitrogen under mild conditions and many other processes, using these compounds as additives to fuels and high-temperature lubrication oils, vulcanization accelerators of rubbers constituting lacos and water-repellent impregnation, anti-knock agents, driers, fungicides, etc. Of particular interest are the synthetic methods and chemical transformations of titanocene and niobocene derivatives containing the metal-carbon σ-bond. Most of the titanium-c-derivatives have low thermal stability, and the niobocene derivatives are extremely sensitive to the action of air oxygen, which makes it difficult to study their chemical transformations. Carborane derivatives are used for the preparation of various types of polymers used in solid rocket fuels and as heat-resistant coatings. They are also used as agents in boroneutron capture therapy of oncological diseases. This review presents a brief historical flashback, the current state and further development of the work carried out in the laboratory of organoelement compounds, which began and was supervised by Yu. A. Ol’dekop, covering the period from 1971 to 2018. References include 80 references.