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CHEMISTRY

ISSN 2227-6017 (ONLINE), ISSN 2303-9868 (PRINT), DOI: 10.18454/IRJ.2227-6017
ЭЛ № ФС 77 - 80772, 16+

PREPARATION OF AMORPHOUS OXIDES AL2O3 AND FE2O3 BY A MODIFIED SOL-GEL METHOD

Posted in 2022, CHEMISTRY, Issue № 5 (119) May 2022 | 0 comments

A new approach to obtain amorphous oxides was investigated both theoretically and experimentally using X-ray diffraction (XRD), electron probe microanalysis (EPMA) techniques. In this work, the conventional sol-gel method was modified by the addition of malic acid as an oxidizing agent and successfully applied to obtain two oxides Al2O3& Fe2O3 with the amorphous structure. Thermal stability and the enthalpy of fusion of the obtained amorphous oxides were examined by the differential scanning calorimetry (DSC). It was found that amorphous Al2O3 was stable up to 790 – 810 °C, while amorphous Fe2O3 recrystallized at about 160 – 180 °C, depending on the heating rate. The heat capacity using the DSC method has been measured. The results were observed depending on the heating temperature.

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DEVELOPMENT OF AN OXIDIZER AND REACTION CONDITIONS FOR A STABLE AND REPRODUCIBLE DETERMINATION OF CAFFEINE VIA THE MUREXIDE TEST

Posted in 2022, CHEMISTRY, Issue № 04 (118) April 2022 | 0 comments

Control of the content of N-methyl derivatives of uric acid as active substances or concomitant substances is necessary for more than 150 drugs included in the State Register of Medicines. The murexide test is a reliable way to identify caffeine and other purine derivatives, it is used as a basis in a number of physico-chemical instrumental methods. The study develops the optimal composition of the oxidizer and the conditions for conducting a murexide test for a simple, two-stage method for the qualitative determination of caffeine and other purine derivatives both in pure form and in medicinal preparations. This makes it possible to achieve reproducibility and reliability of the reaction results. The experimental studies show that the discrepancy in the color of the reaction products with the claimed methods is associated with the formation of tetramethylalloxanthine. The authors analyze the advantages of the developed methodology in comparison with the literature data.

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ASPEN WOOD LIGNIN: FEATURES OF COMPOSITION, STRUCTURE, FRACTIONATION AND CONVERSION

Posted in 2022, CHEMISTRY, Issue № 04 (118) April 2022 | 0 comments

The study is aimed at identifying the characteristics of aspen wood lignin as an alternative source of aromatic hydrocarbons, which determines the suitability of a particular method of its processing. The author describves the composition and structure of lignin, changes in the chemical composition with various methods of its isolation (fractionation): organic solvent extraction, explosive autohydrolysis, integrated processes. The study presents the results of research of scientists on the isolation of various types of organosolv lignins of aspen wood; practical approaches to conversion into liquid phenolic and aromatic hydrocarbons. The article also draws attention to the search for selective depolymerization processes and preservation of the native structure of aspen wood lignin.

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QSAR Modeling of Inhibitory Activity of γ-Carboline and Phenothiazine Conjugates towards Butyrylcholinesterase

Posted in 2022, CHEMISTRY, Issue № 03(117) March 2022 | 0 comments

The purpose of this study was to create a QSAR (Quantitative Structure-Activity Relationship) models of the inhibitory activity of γ-carboline and phenothiazine conjugates towards butyrylcholinesterase (BChE). These compounds act as selective BChE inhibitors and NMDA receptor blockers at the same time. The search and design of multi-target compounds acting simultaneously on several molecular targets is a new trajectory in the development of drugs for the treatment of neurodegenerative diseases (Alzheimer’s disease, Parkinson’s disease, etc.). A complete conformational analysis was performed for all molecules in Cache Worksystem Pro. Integrals of the spectra of interatomic intramolecular interactions were used as descriptors of the spatial structure of molecules, which were calculated using MOLTRA. For QSAR modeling, the method of multiple linear regression was used. The obtained regression equations have satisfactory statistical characteristics and comply with the OECD principles. In the future, they can be used as filters to optimize the properties of compounds and find application in molecular virtual screening.

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THE EFFECT OF THE ADDITION OF HIGH-RESIN OIL ON THE PROPERTIES OF HIGH-PARAFFIN OIL

Posted in 2022, CHEMISTRY, Issue № 01(115) January 2022 | 0 comments

The current study discusses the effect of the additive of high-resinous oil (3-50% by weight). the structural and mechanical parameters of oil with a high content of paraffin. The degree of exposure is determined by the concentration of highly resinous oil in the mixture. Introduction of 5-10% high-resinous oil into high-paraffin oil by weight contributes to a decrease in viscosity-temperature characteristics, the activation energy of the viscous flow, the specific energy of destruction of the dispersed system, the amount of paraffin deposits, changes in the shape and structure of paraffin crystals. Significant inhibition of the sedimentation process and improvement of viscosity-temperature properties is observed after the introduction of 10% high-resinous oil into high-paraffin oil by weight.

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SEARCH FOR CROSSLINKING AGENTS FOR HIGH-ENERGY INDUSTRIAL COMPOUNDS

Posted in 2022, CHEMISTRY, Issue № 01(115) January 2022 | 0 comments

To increase the waterproof qualities of water-gel high-energy industrial compositions based on guar gum, the current study selects and studies new organic high-energy types of crosslinkers capable of increasing the stability of the charge column when in flooded wells with flowing and standing water.

The authors carry out an analysis of the influence of organic staplers on the physicochemical properties of industrial compounds. Preparation and introduction of active organic groupings to increase the reactivity of guar gum and crosslinking agents, reduce the time of spatial crosslinking of guar gum macromolecules, increase the water resistance of the charge column without reducing the detonation properties of the initial industrial composition.

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A COMPARATIVE ANALYSIS OF DRINKING WATER IN THE CITY OF KOKSHETAU, AKMOLA REGION

Posted in 2021, CHEMISTRY, Issue № 12 (114) December 2021 | 0 comments

Mineral waters are natural groundwater formed in the thickness of the Earth’s crust with certain geological, structural, geothermal, hydrogeological and geochemical conditions that determine the patterns of their spatial localization, gas, ion-salt and trace element composition, temperature and other indicators. In the course of the study, the authors examine the issues of studying the chemical composition of waters from water sources located on the territory of Kokshetau and used in the production of mineral waters such as “Kulager-Arasan”, “Svezhest”, “Turan”. The study determines the content of chloride ions, sulfate ions, magnesium cations, calcium, sodium, and bicarbonates and conducts a comparative analysis of the content of chemicals and organoleptic characteristics.

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SYNTHESIS OF N – HETEROCYCLIC PROLIGANDS AS PROMISING NEW GENERATION OF STABILIZING LIGANDS

Posted in 2021, CHEMISTRY, Issue № 12 (114) December 2021 | 0 comments

The paper analyzes the use of organometallic catalysts, namely the complexes with N-heterocyclic carbenes. The substrates under study can be used as stabilizing ligands for the synthesis of stable complexes. In turn, the complexes can be used as effective catalysts of a new generation of carbon-carbon, carbon-heteroatom bond formation. In most cases, the activity of catalysts directly depends on the structure of N-heterocyclic carbenes in terms of steric and electronic properties, which is of the greatest interest as objects for research. The methods presented in this study allow for obtaining both symmetric and asymmetric benzimidazole, imidazole, and triazole carbenes.

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SYNTHESIS, INVESTIGATION OF THE STRUCTURE AND PROPERTIES OF COMPLEX COMPOUNDS OF HYDROXYL AMINO ACIDS WITH COPPER IONS

Posted in 2021, CHEMISTRY, Issue № 12 (114) December 2021 | 0 comments

The research synthesizes new complex compounds based on copper ions and proteinogenic amino acids L-serine and L-threonine. The reactions were carried out by heating in solutions followed by washing and drying of the precipitated salts. The composition and structure of the obtained compounds were studied by IR spectroscopy, pH potentiometry, titrimetry, and spectrophotometry. The study shows that complexes are formed in a molar metal-ligand ratio of 1 : 2. The authors confirm bidentate coordination of copper by amino acids and N,O-chelation due to donor-acceptor bonds of the carboxyl and amino groups. The absorption bands characteristic of Cu-N, Cu-O bonds, and the displacement of the maxima of functional groups of amino acids are recorded in the IR spectra. The instability constants of threoninate and copper serinate are calculated.

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EFFECT OF AgNO 3 CONCENTRATION ON THE FORMATION OF SILVER NANOPARTICLES BY A STRAIN OF THE YEAST FUNGUS SACCHAROMYCES ELLIPSOIDEUS BDU – XR1

Posted in 2021, CHEMISTRY, Issue № 12 (114) December 2021 | 0 comments

The aim of this article was to study the effect of the concentration of silver nitrate salt (AgNO3) on the formation of silver nanoparticles by a strain of the yeast fungus Saccharomyces ellipsoideus BDU – XR1. The author determine that the ability of the yeast fungus strain under study to form silver nanoparticles was the most optimal in the reaction mixture at concentrations of 0.5 and 1.0 mM AgNO3. On the 7th day of incubation, both a change (darkening) in the color of the reaction mixture and an absorption peak at wavelengths of 405 and 408 nm, respectively, at concentrations of 0.5 and 1.0 mM AgNO3 were observed. At concentrations of 3.0, 5.0 and 10.0 mM of silver nitrate salt, the process of nanoparticle biosynthesis was not observed.

Under a scanning electron microscope, the silver nanoparticles formed in both samples had a rounded shape, and their size was 22.4 and 34.2-37.5 nm, respectively with a silver nitrate salt concentration of 0.5 and 1.0 mM. X-ray spectral analysis of the samples showed the presence of an adsorption peak (Ag Lal) characteristic of silver nanoparticles.

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FEATURES OF SOLVATION IN CONTACT SYSTEMS

Posted in 2021, CHEMISTRY, Issue № 11 (113) November 2021 | 0 comments

The article presents research in the field of solvation in contact systems. The variety of phenomena that can be observed in contact systems, including sorption-active materials and electrolyte solutions, indicates the possibility of a wide range of directional changes in the properties of such systems. This forms the basis for increasing the efficiency of their practical use and can also serve the purposes of developing new, unconventional technological processes and new methods for the study of substances.

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STUDY OF GOLD-CONTAINING CONCENTRATE PROCESSING TECHNOLOGY

Posted in 2021, CHEMISTRY, Issue № 11 (113) November 2021 | 0 comments

The article deals with the processing technology of gold-containing concentrates in the gold extraction plant of the Vysochaishy deposit in the Bodaibo district of the Irkutsk region. The research of mineral samples of gold-containing concentrates was carried out. Recommendations for improving the efficiency of extraction of gold from the gold-containing concentrates at the gold-processing plant at the deposit «Vysochaishy» in the Irkutsk region are reviewed.

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USING OF GAZ CHROMATOGRAPHY FOR DETERMINATION OF URINARY STONES NON-PROTEIN ORGANIC COMPONENTS AND THEIR DISTRIBUTION IN THEIR VOLUME

Posted in 2013, CHEMISTRY, Issue №6 (13) June 2013 | 0 comments

This paper shows the possibility of qualitative and quantitative (for a number of components) of the definition of non-protein organic component of urinary stones using in first time gas chromatography with flame ionization detector. The distribution of non-protein organic
component by stones volume has been submitted and their relationship with forms of urinary stones has been revealed.

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INTEGRATION IN EXCEL WITHOUT MACROS ON THE EXAMPLE OF ARRHENIUS INTEGRAL

Posted in 2021, CHEMISTRY, Issue №10 (112) October 2021 | 0 comments

The article proposes an efficient (accurate, simple and intuitively clear, fast executable and having a short program code) algorithm based on the broad computing capabilities of Excel without using VBA macros. As an example, the implementation of the calculation of the Arrhenius integral in one Excel cell is given. The accuracy of the calculations is analyzed by comparison with the often-used approximations in chemical kinetics for calculating the integral for the range of values that occur during gas and solid-phase reactions. This algorithm can be used for the numerical integration of other nonelementary integrals encountered in solving practical problems and data processing. Illustrative examples (screenshots of a spreadsheet) contain comments and can be quickly reproduced and checked.

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DETERMINING DIMETHYLAMINE IN WATER SOURCES OF VARIOUS GENESIS VIA HPLC

Posted in 2021, CHEMISTRY, Issue №10 (112) October 2021 | 0 comments

Based on the authors’ own previously published information, the article introduces a highly effective method for determining the concentration of secondary aliphatic amine – dimethylamine in water of various genesis. The method of liquid chromatography with a fluorometric detector, with preliminary derivatization of water samples, allows for determining dimethylamine in water with high selectivity, which was confirmed on model systems with the introduction of various concentrations of dimethylamine in the range from 0.005 to 0.1 mg/l. This fully meets the requirements imposed by the current regulatory documents of the Russian Federation. The method demonstrated high efficiency of ~ 97 %, with a total error of the method for measuring dimethylamine concentrations in water by high-performance liquid chromatography with FLD of no more than 25 %.

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ADSORPTION OF DIMETHYLFORMAMIDE AND CAPROLACTAM BY ACTIVE CARBONS IN THEIR JOINT PRESENCE

Posted in 2021, CHEMISTRY, Issue №10 (112) October 2021 | 0 comments

The current article examines the adsorption process of dimethylformamide and caprolactam in their combined presence. As adsorbents, industrial activated carbons of the AG-OV-1, SKD-515 and AG-5 types (JSC “Sorbent”, Perm) were used, which differ in raw materials, the method of production, and adsorption properties. The main changes in the surface of activated carbons caused by the adsorption of dimethylformamide and caprolactam were determined via porometry and X-ray spectroscopy. The study establishes the features, regularities and mechanism of adsorption of dimethylformamide and caprolactam in their joint presence from aqueous solutions with industrial activated carbons. The presence of caprolactam in the dimethylformamide solution leads to a significant disturbance of the structure of the aqueous medium and significant changes in the adsorption isotherms. The AG-OV-1 sample demonstrates the highest adsorption activity in relation to dimethylformamide in the presence of caprolactam in the concentration range under study.

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RELATIONSHIP OF PHYSICAL PROPERTIES WITH THE CRYSTALLOGRAPHIC PARAMETERS OF IONIC CRYSTALS

Posted in 2013, CHEMISTRY, Issue № 9(16) September 2013 | 0 comments

Obtained functional dependence of the Debye temperature for a number of spinels. The dependence of the relative molecular mass of the lattice parameter is satisfactorily described by a linear equation. Revealed a complex effect of crystallographic parameters of the density of a number of spinels.

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CARBOXYLIC ACIDS AS COSOLVENTS FOR OIL- ETHANOL MIXTURE

Posted in 2013, CHEMISTRY, Issue № 9(16) September 2013 | 0 comments

To create the conditions for the intensification of biodiesel production from waste oil and ethanol, the possibility of homogenization of oil +ethanol mixtures is considered. The problem of determination of the phase composition of three- components systems TAG –CarbA -EtOH is solved, where TAG is triglycerides (sunflower oil), CarbA -carboxylic acid (butyric acid, stearic acid, oleic acid), EtOH -ethanol at temperatures ranging from 30 to 70oC. The ability of CarbA to act as a cosolvent for stratified phases such as TAG and EtOH is demonstrated. The efficiency action of CarbA as a cosolvents depending on their functiomal- grouping composition and molecular weight of hydrocarbon radicals is analyzed. A recommendations for choosing CarbA as a cosolvent for homogenization of the TAG +EtOH mixtures are formulated.

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MASS SPECTROSCOPY OF ADDUCTS OF FREE RADICALS AND IMINOXYL RADICALS OF 6-HYDROXYPYRIMIDINE-4(3H)-ONES

Posted in 2021, CHEMISTRY, Issue №9 (111) September 2021 | 0 comments

The current article examines mass spectroscopy of electrospray ionization (ESI) and collision-induced dissociation (CID) of adducts formed by the interaction of free radicals of 2-substituted 6-hydroxypyrimidine-4(3H)-ones and iminoxyl radicals of 6-hydroxypyrimidine-4(3H)-ones. It is shown that they are characterized by the formation of single-charged mono -, di-and trimeric protonated and deprotonated ions of the form [n·M+H]+ and [n·M-H] -, where n=1-3. With negative ionization, the cleavage of the OH ·- radical is observed with the formation of [n·M-OH]- (n=1-3) ions. In the positive mode, hydration occurs with the formation of [n·M+H 3 O]+ ions (n=1-3). Fragmentation of adducts occurs by a single mechanism, the first stage of which is the cleavage of N-oxide oxygen in the form of hydroxyl radical followed by fragmentation of the dioxopyrimidine cycle, eventually leading to a bicyclic structure.

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TECHNOLOGY FOR THE REGENERATION OF ACTIVE COALS AFTER THE ADSORPTION OF ORGANIC CONTAMINANTS

Posted in 2021, CHEMISTRY, Issue №9 (111) September 2021 | 0 comments

The problem of wastewater treatment of the coal industry has not been fundamentally solved in any country, since there is no opportunity to offer and work out a single and universal scheme for wastewater treatment, even for those enterprises that work with similar types of extracted coal and use similar technologies. It is advisable to use adsorption methods to purify quarry waters from organic compounds. During operation, the efficiency of filters with sorbing materials decreases, therefore their periodic regeneration is necessary to restore the adsorption capacity of active coals. Based on experimental studies, the article introduces a technology for restoring the sorption capacity of sorbents SKD-515, AG-3, KAU, AG-OV-1 after adsorption of trilene by heating for 2 hours with airflow at a temperature of 150 °C. Regeneration using this method restores the sorption capacity of active coals by 92-96 %.

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