Химия

Phase equilibria in the ternary system sodium nitrate – water – dipropylamine where the constituent binary liquid system is characterized by a trend to form a lower critical solution temperature (LCST) were studied using the visual-polythermal method in the range ?10.0–90.0° C. It was found that the introduction of sodium nitrate into the water – dipropylamine system led to a significant decrease in the mutual solubility of the components.

The effect of different concentrations of nickel (II) ions on the oxidation rate of mixed wastewater pollutants with ozone-air mixture for 30 minutes with an ozone concentration of 3 mg/l was studied. It was shown that adding nickel (II) ions at a concentration of 300 mg/l reaches the maximum degree purification of wastewater as a result of oxidative processes on the COD value, equal to 40.4%, which is 10.1% more compared to the catalytic oxidation of the investigated wastewater pollutants with the air oxygen participation.

The synthesis of novel organoselenium heterocyclic compounds is of great theoretical and practical interest because of high biological activity. The known methods of synthesis of hexatomic selenium containing heterocyclic compounds allow us to obtain only monoaryl-substituted tetrahydroselenochromilium salts. In this study, the reactions of 2-(3-oxo-1-aryl-3-phenylpropyl) cyclohexanones were carried out with hydrogen selenide in situ under conditions of acid catalysis in diethyl ether.

The research of behavior of cefixime in biological media was conducted by spectrophotometric method. It was shown that the maximum of light absorption of cefixime against the background of oral fluid is observed at ? = 292 nm and for blood serum at ? = 289 nm. The interval of linear dependence optical density – concentration of cefixime is 3–50 mkg/ml. The optimal conditions of precipitation of proteins in the studied biological media were revealed.

Cefuroxime is a cephalosporin antibiotic with a wide spectrum of antibacterial activity for gram-positive and gram-negative microorganisms. It is in the list of vital and essential drugs for medical use. Currently, spectroscopic, chromatographic, electrochemical methods are used to determine cefuroxime. In current study we developed test agents in the form of indicator papers and powders with an immobilized Fehling reagent for the rapid determination of cefuroxime. Cellulose paper and silica gel were used as a solid matrix to create testing means.

Kinetic regularities of the alkaline hydrolysis of copolymers of methyl acrylate, butyl acrylate, vinyl acetate and acrylic acid of several chemical compositions under various conditions were studied by IR spectrometry. The initial rate of alkaline hydrolysis and the limiting conversion degree were shown to increase with increasing concentrations of the components of the reaction mass and temperature.

Obtaining stable polymer-colloidal dispersions based on watersoluble polymers and inorganic colloidal particles, such as silver iodide sol, followed by removal of the dispersion medium is one of the ways to create hybrid biomedical materials (e.g. films, threedimensional matrices). The current work is devoted to studying the possibility of increasing the stability of polymer-colloidal systems based on silver iodide sols, succinyl chitosan and chitosan polysaccharides by reducing the total charge of macromolecules.

The search and analysis of English-language 2004–2019 scientific literature devoted to the graft polymerization of acrylic monomers (acrylic acid and acrylamide being examples) onto chitosan to obtain novel materials with valuable properties was made. It was revealed that radical copolymerization, with potassium or ammonium persulfate, cerium-ammonium nitrate being initiators was used for grafting. Microwave, UV radiation and gamma rays were also used. To obtain gel, a cross-linking agent (N,N’- methylenebisacrylamide) was introduced.

Silver thiostannates and chalcostannates are widely used as promising functional materials which have semiconductor, thermoelectric, and photoelectric properties. The goal of this research is to study the Ag2SnS3-Sb2S3 phase diagram and determine the boundaries of solid solutions based on both components. Alloys were investigated using methods of physicochemical analysis. Based on the results of the study, a condition diagram of the Ag2SnS3-Sb2S3 system was constructed.

The reactions of 4-phenyl and 4-(p-tolyl)-4-oxobutanoic acids with 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane by heating in an aprotic non-polar solvent initially proceed through a nucleophilic attack of the amino group on the carbon atom of the oxoacid carbonyl group to form the corresponding amide.