Chemical Journal of Kazakhstan

REGULATION OF THE COMPOSITION AND PROPERTIES OF HUMIC SUBSTANCES DURING ACID TREATMENT

Mon, 30 Mar 2026 00:00:00 +0500

Introduction. Humic substances (HS) are promising natural sorbents that contain carboxyl, phenolic, hydroxyl and other functional groups, which ensures their high reactivity and tendency to complex with heavy and transition metals, influencing their migration, bioavailability and toxicity.The aim of the work is to investigate the influence of various factors on the production of humic acids from the domestic natural raw materials. Methods: standardized methods, elemental and functional analysis, IR spectroscopy, and thermogravimetry. Results and discussion. Research has been conducted on the production of humic acids (HA) by reacting sodium humate with hydrochloric acid. It has been shown that the regulation of the HCl concentration, liquid phase ratio, reaction time and temperature allows one to control the yield of HAdaf (up to 78.31%), the content of COOH and OHphen. groups (up to 1.20 and 1.62 mmol/g), the total pore volume (up to 0.58 cm3/g) and static exchange capacity (up to 21.10 mg-eq/g). The determined optimal synthesis parameters (sodium humate concentration of 3.0%, liquid phase ratio 1:1, treatment for 15 min at 20°C) ensure reproducible properties of the HA and their high efficiency in the sorption of metal ions. The elemental analysis and the calculation of the H/C and O/C atomic ratios have shown that the structure of the synthesized the HA is heterogeneous, including aromatic and aliphatic fragments. It has been found that an increase in the HCl concentration initiates an oxidative-hydrolytic destruction of the peripheral structures with a simultaneous increase in the oxygen-containing functional groups, which determine the sorption activity of the HAs. The data of the thermal analysis and IR spectroscopy confirm the preservation of the functional groups up to 350°C and are consistent with the degradation processes at higher temperatures. Conclusion. A process flow diagram for producing humic acids under the “mild” conditions has been developed. It is characterized by flexibility, low waste generation, and the ability to produce humic sorbents with a specified composition. The synthesized HA have sorption, ion exchange and other properties and are promising for practical application.

LEAD-LIKE PROPERTIES OF A NOVEL PYRIDINE AMINOPHOSPHONATE: SYNTHESIS, PREDICTIVE EVALUATION AND BIOLOGICAL TESTING

Mon, 30 Mar 2026 00:00:00 +0500

Abstract. Introduction. Aminophosphonate derivatives attract considerable interest as a class of low-molecular-weight compounds capable of exerting regulatory effects in biological systems of different origin. The combination of predictive and experimental approaches enables comprehensive characterization of their biological potential at early stages of investigation. The aim of this study was the synthesis of a novel aminophosphonate derivative, the preparation of its water-soluble form, and a comprehensive predictive–experimental evaluation of its biological activity. Dimethyl ((3-phenoxyphenyl)((pyridin-2-ylmethyl)amino)methyl)phosphonate (PMAAPh) was synthesized via the Kabachnik–Fields reaction, and its succinate salt (PMAAPh-Suc) was obtained to improve aqueous solubility. The structures of the compounds were confirmed by NMR and IR spectroscopy. In silico analysis included the assessment of predicted biological activity, pharmacokinetic properties, and toxicity. Experimental studies were performed using plant models and an in vivo model of experimental pancytopenia. It was established that PMAAPh meets the main drug-likeness criteria and belongs to toxicity class III. PMAAPh-Suc exhibited regulatory effects on plant growth and hematopoietic parameters. The obtained results indicate that the studied compound is a promising candidate for further investigation of biologically active compounds.

STUDY OF THE ISOLATION OF ZINC COMPOUNDS FROM BRONZE PRODUCTION WASTE

Mon, 30 Mar 2026 00:00:00 +0500

This article is devoted to the study of the technology of selective separation of zinc and copper compounds from metallurgical wastes formed during the production of bronze and brass by hydrometallurgical method. The relevance of the study is associated with the depletion of mineral raw materials and the increasing environmental load of metallurgical wastes on the environment. The purpose of the work is to determine the possibility of obtaining copper and zinc in an efficient and environmentally friendly way during the processing of bronze and brass slags. During the study, nitric acid, ammonia solutions and sulfuric acid were used, and their leaching efficiency was comparatively evaluated. The chemical and phase composition of the slags was determined by inductively coupled plasma optical emission spectrometry, infrared spectroscopy and X-ray phase analysis. As a new methodological approach, the “hot leaching” method using 25% sulfuric acid at a temperature of 80 °C was used. The results of the study showed that sulfuric acid is more economically and environmentally effective in the separation of copper and zinc. The process resulted in the formation of tin precipitate, chemically and electrochemically extracted high-purity metallic copper, and solid waste rich in zinc. The proposed technological scheme reduces metal consumption, increases the possibility of waste recycling, and is of practical importance for the development of low-waste, resource-saving metallurgical technologies.

NEW N-BENZYLPIPERIDONE DERIVATIVES: SYNTHESIS AND PLANT GROWTH-STIMULATING ACTIVITY

Aigul Malmakova, Kamila Otegulova , Tulegen Seilkhanov — Mon, 30 Mar 2026 00:00:00 +0500

Introduction. Nitrogen-containing heterocycles are of significant importance due to their prevalence in nature and their role as scaffolds for numerous pharmacologically active compounds. Piperidine derivatives, especially N-benzylpiperidones, exhibit broad pharmacological potential and represent promising candidates for further chemical modification. The appeal of these compounds stems from the availability of starting materials and straightforward synthetic procedures, which facilitate the development of novel compounds with specific physicochemical and biological properties. The objective of this study is to synthesize a new series of benzylpiperidone derivatives, generate more complex nitrogen-containing heterocycles through structural modification, and evaluate their plant growth-stimulating activity. Results and discussion. N-benzylpiperidin-4-one was reacted with 1-(3-methoxypropyl)amine and paraformaldehyde to yield 3-benzyl-7-(3-methoxypropyl)-3,7-diazabicyclo[3.3.1]nonan-9-one. The resulting ketone was converted to the corresponding oxime with a 76% yield under oximation conditions. Subsequent acylation of the oxime with benzoyl chloride produced O-benzoyloxime in 65% yield. The resulting complex (KhZR-107) was assessed for its effects on the germination, growth, and development of wheat (variety Kazakhstan-10) and soybean (variety Zhansaya) seedlings at a concentration of 0.001%. Conclusion. The complex KhZR-107 exhibited a positive influence on wheat seed germination and seedling development. Further investigation under controlled and field conditions is warranted to assess its efficacy and microbiological stability.

STRUCTURAL PARAMETERS OF SPATIALLY CROSS-LINKED COPOLYMERS OF POLYETHYLENE GLYCOL MALEATE AND ACRYLIC ACID

Mon, 30 Mar 2026 00:00:00 +0500

Abstract. Introduction. The development of polymer binders for construction and composite materials requires purposeful control over the structure of spatially cross-linked polymer networks, since the internal structural parameters largely determine the mechanical, sorption, and performance characteristics of materials. In this context, the quantitative evaluation of crosslink density and the number of junctions in polymer networks as a function of system composition represents an important scientific task. Methodology. In this study, spatially cross-linked copolymers based on polyethylene glycol maleate modified with acrylic acid were synthesized by a “cold” radical curing method at various mass ratios of the components. The structure of the obtained materials was confirmed by Fourier transform infrared (FTIR) spectroscopy. Quantitative assessment of the structural parameters of the polymer network was performed using equilibrium swelling data of the copolymers in water. The crosslink density, number of network junctions, and average molecular weight between junctions were calculated using the Flory–Rehner equation. Results of the study. It was established that an increase in the polyester component content in the investigated systems leads to a decrease in the swelling degree and to the formation of a denser spatially cross-linked structure, characterized by an increase in crosslink density and a reduction in the molecular weight between network junctions. The obtained results demonstrate the possibility of purposeful control over the structural parameters and properties of polyester binders by varying the system composition, thereby opening prospects for their application in construction and composite materials.

FEATURES OF THE INTERACTION OF INTERGEL SYSTEMS BASED ON POLYACRYLIC ACID AND POLY-2-METHYL-5-VINYLPYRIDINE WITH GOLD IONS

Mon, 30 Mar 2026 00:00:00 +0500

Introduction. In the interpolymer system of polyacrylic acid and poly-2-methyl-5-vinylpyridine, the change in the mutual activation of polymer hydrogels with different degrees of crosslinking as a result of remote interaction of the two hydrogels was determined, and their effect on the process of gold ion sorption was studied [1,2]. The purpose aim of the work is to study the sorption capacity of intergel systems based on poly-2-methyl-5-vinylpyridine and polyacrylic acid in relation to gold ions [3,4]. The obtained results The maximum degree of sorption of the gPAA:gP2M5VP interpolymer systems increased to 0.645 mol/L at a polymer molar ratio of 5:1 within 48 hours of interaction, and then gradually decreased to 0.575 mol/L. The maximum pH values of the intergel system gPAA:gP2M5VP are observed at a ratio of 3:3, corresponding to a pH of 2.99. The minimum pH value is 2.96 at a ratio of 2:4. The overall swelling ratio (Ksw) increases from 0.8 to 3 during the conformational rotation of the interstitial unit. Conclusion. According to the results, the electrochemical properties of hydrogels of polyacrylic acid and poly-2-methyl-5-vinylpyridine in the interpolymer system were studied and the optimal molar ratios were determined. Thus, as a result of these studies: the obtained experimental data on specific electrical conductivity of the solution, pH of the medium and swelling coefficient of hydrogels showed that the presence of remote interaction between acrylic acid and 2-methyl-5-vinylpyridine hydrogels has a significant effect on the initial polymer network and physicochemical properties of the solution.

STUDY OF THE SURFACE–BULK PROPERTIES OF AN ACRYLIC DISPERSION IN THE PRESENCE OF AN AMINE-CONTAINING SURFACTANT

Antonina Dyuryagina, Yuliya Byzova, Darya Ostrovnaya , Aida Lutsenko — Mon, 30 Mar 2026 00:00:00 +0500

Introduction. Waterborne coating materials based on polymer dispersions are regarded as a priority direction in coating technology due to reduced environmental impact and increasingly stringent requirements for production and application safety. However, aqueous acrylic dispersions retain technological limitations associated with film formation, interfacial interactions, and resistance to moisture exposure. One promising approach to improving performance is the incorporation of amine-containing surfactants capable of regulating charge–associative processes and the structure of the interfacial layer. The aim of this study was to determine the effect of an amine-containing additive on the surface–bulk properties of an aqueous acrylic dispersion and to identify the factors governing changes in interfacial activity and structural organization within the bulk phase. The research objectives included a comparative analysis of the “water–additive” system and the “acrylic dispersion–water–additive” system, as well as an examination of the mechanisms responsible for the redistribution of protonated and less ionized forms of the additive between the bulk phase and the phase boundary. Methods. Interfacial characteristics were evaluated using an ACAM series instrument equipped with video recording of the droplet profile and calculation of interfacial parameters by drop shape analysis based on the Young–Laplace equation. Bulk properties were monitored by conductometry (specific electrical conductivity) and potentiometry with pH measurements while varying the content of the amine-containing additive polyethylene polyamine. Results and discussion. It was shown that in an aqueous medium the additive exhibits limited interfacial activity. In the presence of an acrylic dispersion, the interfacial effect is enhanced, indicating the involvement of the additive in specific interactions with functional groups of the film-forming polymer and a change in its distribution between the surface and the bulk phase. Conclusion. The results obtained substantiate the use of polyethylene polyamine as a tool for controlling interfacial and bulk processes in aqueous acrylic dispersions and may be applied in the development of waterborne coating systems.

EXTRACTION OF BIODEGRADABLE SURGICAL THREADS BASED ON POLYLACTIDE

Mon, 30 Mar 2026 00:00:00 +0500

Conventional surgical sutures should be removed after wound healing, because they cause additional pain and discomfort for the patients. Polylactide (PLA) is an aliphatic polyester derived from the renewable resources, which is biocompatible and biodegradable; however, its relatively high stiffness can limit its surgical applications. This study has the purpose to develop biodegradable surgical sutures based, on PLA and poly(vinyl alcohol) (PVA), and to investigate their physicochemical, mechanical, and biodegradation properties. To reduce PLA stiffness, PLA has been blended with PVA to form composite fibers. The fibers have been prepared from the polymer blends, using ultrasonic treatment to improve mixing. The blend homogeneity has been assessed, using UV–Vis spectroscopy, chemical structure has been characterized by the IR spectroscopy, and surface morphology has been investigated by scanning electron microscopy (SEM). The SEM has revealed changes in the surface morphology and gradual degradation of the fibers over a 16- week period, which has also been supported by the mass-loss measurements in soil. The mechanical properties have been determined according to ASTM D2256. AN incorporation of PVA has increased fiber extensibility and elasticity, and the PLA–PVA composition (20:80 wt.%) has shown the most favorable mechanical performance among the tested formulations. Overall, the results suggest that the PLA–PVA composite fibers are promising candidates for absorbable surgical suture materials.

ASSESSMENT OF THE BIOLOGICAL EFFECT OF 2,2-PROPAGYLOXY BENZOIC ACID ON GRAINS OF SINGLE AND DICOTYLEDONOUS PLANTS

Mon, 30 Mar 2026 00:00:00 +0500

Introduction. Oxygen heterocyclic compounds occupy an important place in modern organic and medical chemistry. Tetrahydropyran derivatives in particular are widely studied due to their structural diversity and biological activity. In this regard, the problem of agribilogy and phytochemistry is to determine the biological activity of propargyloxybenzoic acid, an oxygenated derivative of 2,2-dimethyltetrahydropyran-4 — on and propargylated salicylic acid in the grains of single and dicotyledonous plants by the reaction of Favorsky. The purpose and objectives of the work is to study the biological activity of seeds of single and dicotyledonous plants with the synthesis of a new oxygenated heterocyclic compound based on 2,2-dimethyltetrahydropyran-4-on and propargylated salicylic acid. Tasks obtaining the original compound by The Prince reaction, synthesizing a new derivative using the Favorsky reaction, and studying its biological activity. Conclusion (conclusions). The oxygen heterocycle 2,2-dimethyltetrahydropyran-4-on was obtained with dimethylvinyl-ethinylcarbinol in a sulfuric acid medium and using mercury sulfate as a catalyst, with a yield of 70% through the Prince reaction mechanism. By reacting the resulting 2,2-dimethyltetrahydropyran-4-on with the acetylene derivative of salicylic acid by the Favorsky reaction, the acetylene derivative of 2,2-dimethyltetrahydropyran-4-on was synthesized with a 57% yield of 2,2-propagyloxy benzoic acid. The physicochemical properties of the obtained oxygen heterocycle compounds were determined and studied by IR spectroscopy. According to the results of a study of the biological activity of 2,2-propagyloxy benzoic acid on single and dicotyledonous plant grains, it was found that it significantly inhibited the growth of dicotyledonous plants in high concentrations, and was effective as a growth stimulant for single dicotyledonous plants.