Химия

The introduction of the (trifluoro)acetyl moiety into different heterocycles allows one to vary their physicochemical properties, change the nature and magnitude of biological activity, and also to carry out further chemical transformations. At the same time, modern methods of organic chemistry are aimed, inter alia, at increasing the efficiency of known and widely used chemical reactions and the possibility of directing along other paths when conducting syntheses under conditions, which are different from the classical ones.

The application of the Vierordt’s and the first derivative at the “zero crossing” methods was evaluated for the simultaneous determination of synthetic food dyes Yellow “sunset” (E110) and Ponso 4R (E124) in model solutions. The concentrations interval of components is established at which the principle of optical densities additivity is observed. For the implementation of the Vierordt’s method, wavelengths with the maximum difference in the absorption coefficients of the individual components (470.2 and 536.7 nm) were chosen.

The conditions of synthesis of ion associates of phosphorus-molybdenum ions with protonated form of lysine hydrochloride have been considered. It has been shown that the phosphoric molybdenum acid undergoes hydrolysis with the formation of the following products: НРО42– + Мо12О42– + 11Н2О. At pH 2 in aqueous solutions, the PhMA is stable, exists as anion [РМо12О42]3– and interacts with protonated form of lysine with the formation of associates 3[НLys]+[FMC]3–.

Показано, что 4H-хроменоны, функционализированные альдегидной группой в положении С3, способны образовывать гибридные системы, имеющие в своей структуре помимо хроменонового пиридиновый, пиримидиновый циклы. Кислая среда способствует раскрытию ?-лактонного фрагмента. Показана возможность дезактивации альдегидной группы с последующим деформилированием. 

A brief review of computational methods for the liquid-liquid equilibrium has been carried out, and their capabilities and limitations have been shown. Complications of such computational models for the liquid–liquid–solid equilibrium lead to a decreased accuracy of calculations. In this case, it is advisable for researchers to make use of the approximation of experimental data on the liquid – liquid and liquid – liquid – solid equilibria.

The effect of complexation with yttrium ions and micellar media of surfactants on the fluorescent properties of levofloxacin was studied. The luminescence of levofloxacin depends on the acidity of the medium Т. Г. Данилина и др. Влияние мицелл поверхностно-активных веществ 378 Научный отдел Изв. Сарат. ун-та. Нов. сер. Сер. Химия. Биология. Экология. 2019. Т. 19, вып. 4 and is maximum in an acidic medium. It was shown that complexation with yttrium ions promotes the growth of the intrinsic fluorescence of levofloxacin by a factor of 2.

The possibility of using hydroxythiophenols (HTP) for the photometric determination of cobalt (II) has been studied. Aminophenols (AP) were used as hydrophobic amine: 2- (N,N-methylamino methyl)-phenol (AP1) and 2- (N, N-methylaminomethyl) -4-methylphenol (AP2). Dichloroethane, chloroform and carbon tetrachloride turned out to be the best extractants. With a single extraction with chloroform, 97.5–99.5% of cobalt is recovered as a complex. The cobalt (II) complex is extracted into chloroform in the pH range of 3.6–6.3.

The acute problem in the analysis of dairy products is the potentiometric determination of the active and total titrated acidity of pasteurized milk from different manufacturers and their comparison with those for raw cow milk. In addition, for various expert purposes, fast definition of the manufacturer of this product is necessary. The conditions of potentiometric titration of pasteurized milk are specified. It is shown that the total acidity of pasteurized milk produced by different manufacturers differs insignificantly.

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.