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Synthesis and Heterocyclization of 4-Hydroxy-3 - ((2-hydroxy-4,4-dimethyl-6-oxocyclohex1-en-1-yl) (aryl) methyl) -2H-chromen-2-ones

Authors: Kostritsky A. Y., Nakonechnikova M. G., Fedotova О. V., Pchelintseva N. V.

The possibility of obtaining asymmetric 1,5-diketones based on 4-hydroxy-2H-chromen-2-one and dimedone by three-component condensation in the presence of L-proline as a catalyst is shown. As a result, a series of 4-hydroxy3 - ((2-hydroxy-4,4-dimethyl-6-oxocyclohex1-en-1-yl) (aryl) methyl) -2H-chromen-2-ones was obtained with a yield of 25 up to 73%. The study revealed that the highest yield was observed for compounds containing fragments of ortho-substituted aldehydes capable of forming a hydrogen bond. For meta- and para-substituted – the lowest yield was observed.

Optimization of the Conditions for Determining 2,4-D and Deltamethrin by HPLC

Authors: Melikhova E. V., Farafonova O. V.

The paper presents the results of optimizing the conditions for the chromatographic determination of 2,4-dichlorophenoxyacetic acid and deltamethrin for two capillary columns (Supelcosil LC-18, Kromasil C-18). The modes of individual chromatography of pesticides were selected. The use of the isocratic elution mode in the joint presence of 2,4-dichlorophenoxyacetic acid and deltamethrin was shown and experimentally proved to be invalid. Three options were proposed for the conditions of the gradient mode of the separate detection of analytes in a mixture.

Chromatographical Analysis of Meldonium with Preliminary Concentration by Solid-Phase Extraction on Magnetite Nanoparticles

Authors: Sumina E. G., Reshetnikova I. S., Uglanova V. Z., Yurasov N. A.

A comprehensive method for meldonium analysis, based on a combination of magnetic solid-phase concentration of the analyte on magnetite nanoparticles modified with cetylammonium bromide (CTAB) cations and its subsequent analysis by thin-layer chromatography (TLC) were developed in the process of study. The influence of a number of factors on meldonium sorption was studied, namely: pH, sorbent mass, sorption and mixing times; optimal extraction conditions were determined. It was found that quantitative sorption proceeded in 20 min with a meldonium extraction degree of 88%.

Atomic Force Microscopy Study of the Surface of Films of Chitosan and Its Salts with Organic Acids

Authors: Rudenko D. A., Bratashov D. N., Shipovskaya A. B.

The results of the study of the morphology and surface topography of chitosan films of the salt (S-) and basic (B-) chemical form by atomic force microscopy are presented. The films were cast from polymer solutions in acetic, lactic, citric and succinic acid. NaOH and triethanolamine were used for the salt → chitosan base reaction. Surface tomograms were obtained; the main morphological characteristics and roughness parameters of the film samples were estimated.

“Electronic tongue” multi-systems for the separate determination of cefotaxime and cefazoline

Authors: Kulapina E. G., Dubasova A. Е., Kulapina O. I., Ankina V. D.

. Electroanalytical properties of unmodified and modified by polyaniline and by CuO nanoparticles solid-contact potentiometric sensors which are based on associates of tetradecylammonium with complex compounds of silver (I) with cephuroxime, cephotaxime and cephazoline Ag(β-lac)2TDA in solutions of corresponding antibiotics were studied. It was revealed that Ag(β-lac)2TDA –based sensors had no specificity to the basic ion but showed sensitivity to other cephalosporins.

Branched polymers of N-isopropylacrylamide: A 2005–2020 review of english literature

Authors: Bayburdov T. А., Shmakov S. L.

The search and the analysis of English scientific literature from 2005 to 2020 devoted to the methods of obtaining branched polymers and copolymers of N-isopropylacrylamide were made in order to obtain novel materials with valuable properties. It was found that modern methods of controlled radical polymerization were mainly used for this purpose, namely, atom transfer radical polymerization (ATRP), polymerization with reversible addition-fragmentation chain transfer (RAFT) and group transfer polymerization (GTP). In most cases the original compounds were the chain transfer agents in RAFT.

Adsorption of organic reagents by natural bentonites modified with aluminum and iron (III) polyhydroxocations

Authors: Nikitina N. V., Lamikhova A. P., Nikitina N. V., Kazarinov I. А.

The effective nanostructured sorbents based on natural bentonite modified with aluminum and iron (III) polyhydroxocations were obtained. The elemental composition of the obtained sorbents was studied. The specific surface area was determined for the studied samples. It was shown that modified sorbents based on natural bentonite were nanostructured objects. IR spectroscopy showed that modification of natural bentonite led to the changes in its structural properties.

Investigation of nikel(II) complexing with 2,6-dimerkapto-4-methilphenol and aminophenols

Authors: Kuliev K. А., Mamedova S. A., Efendiyeva N. N.

Complexing of nickel(II) with 2,6-dimercapto-4-methylphenol (DMMP) and hydrophobic amines was studied using physicochemical methods. Hydroxyl-containing amines-aminophenols (AP) were used as a hydrophobic amine. On the part of aminophenols, 2 (N, N-dimethylaminomethyl) -4-methylphenol (AP1 ), 2 (N, N-dimethylaminomethyl)-4-chlorophenol (AP2 ), and 2 (N, N-dimethylaminomethyl) -4-bromophenol (AP3 ) were used. Mixed-ligand complexes were formed in a weakly acidic medium (pHopt 4.6–6.4).

Phase diagram of the β-alanine – water binary system

Authors: Cherkasov D. G., Parfenova V. D.

The phase diagram of the β-alanine–water binary system was studied using the visual polythermal method and the method of time–temperature curves in а temperature range of -20–90°С. There is a eutectic equilibrium at -18.3°С in the system; the solid phases of this equilibrium are ice and individual β-alanine. For the first time, the composition of the liquid phase of the eutectic state was determined.

One-pot synthesis and structure of isomeric aryl-substituted triazolohexahydroquinazolines

Authors: Vasilkova N. O., Demidova D. M., Krivenko A. P.

Aryl-substituted triazolohexahydroquinazolines have been synthesized by means of three-component condensation of pnitro(pbromo) benzaldehydes, cyclohexanone, 1,2,4-triazol-3-amine. A scheme of the reaction mechanism is proposed, which makes it possible to explain the features of the behavior of p-nitro(bromo) benzaldehydes in condensation reactions in comparison with their ortho-substituted analogs.

The influence of nature of active components and modifiers on electroanalytic properties of planar cefalexine-selective sensors

Authors: Kulapina E. G., Kulapina O. I., Ankina V. D.

The 1st generation cefalexine-cephalosporine antibiotic is used in the treatment of various infectious diseases. Spectrophotometry, kinetic spectrophotometry, spectrofluorimetry are proposed to determination of cefalexine in medicine and biological environment. Planar screenprinted sensors allow analyzing the micro-volumes of samples, which is important for the analysis of biological objects without preliminary samplepreparation. Depending on the active material and modifiers, you can create planar sensors for the determination of different organic compounds.

Effect of sulfur solvent on the properties of lead sulfide quantum dots

Authors: Tsvetkova O. Y., Shtykov S. N., Smirnova T. D., Zhukov D. N.

Colloidal quantum dots (QDs) of lead sulfide have been synthesized and investigated using octadecene and white spirit as a solvent for sulfur, varying the concentration of precursors and the temperature of the process. A method has been proposed for the synthesis of these QDs using anhydrous white spirit as a solvent at a temperature of 200° C, which made it possible to obtain polygonal nanoparticles with an average diameter of 2 to 3.2 nm with a minimum spread in size (± 10%).

Glauconite as a sorbent of 4-nitrophenol

Authors: Makhova T. M., Doronin S. Y.

The sorption properties of glauconite from Beloozersk deposits (Saratov region) for 4-nitrophenol (4-NF) have been investigated. The effect of glauconite on pH and 4-nitrophenol structure in solution is estimated. It is shown that glauconite increases pH of aqueous environment to 8 and shifts the equilibrium towards the formation of aci-form 4-NF. The conditions of sorption 4-NF by glauconite are established: the sorption time 20 min, the mass of the sorbent (0.50–1.0) g.

Extractive crystallization of salts in the ternary systems sodium (potassium, cesium) nitrate – water – triethylamine

Authors: Danilina V. V., Chernov D. I., Cherkasov D. G., Il’in K. K.

A comparative analysis of the results of our polythermal study of the ternary systems sodium (potassium, cesium) nitrate – water – triethylamine has been carried out to estimate the efficiency of the use of triethylamine in the extractive crystallization of alkali metal nitrates from water–salt solutions containing 43.0, 44.0, 45.0, 46.0, and 47.0 wt. % sodium nitrate in the range of 10.0–25.0°C, 20.0, 21.0, and 22.0 wt.% potassium nitrate and 18.0, 19.0, 20.0 and 21.0 wt. % cesium nitrate in the range of 20.0–25.0°C.

Phase equilibria and salting out of butyric acid in the ternary system potassium nitrate + water + 2-(2-butoxyethoxy)ethanol

Authors: Smotrov M. P., Godyaeva M. V., Hrykina A. V., Cherkasov D. G.

Visual polythermal method in the bynary system of water-2-(2-butoxyethoxy) ethanol in the range of –25÷0° C the ice melting line is determined and the phase equilibria in the ternary system potassium nitrate–water–2-(2-butoxyethoxy) ethanol are studied in the range of 10.0–90.0° C. The ice melting line in the water–2-(2-butoxyethoxy) ethanol binary system is a flat, smooth line. This form of the melting line shows a hidden separation in liquid mixtures.

Destruction of the active substance of tetracycline under the action of UV irradiation

Authors: Ustinova M. N., Zhunusov N. S.

The growth of the pharmaceutical industry inevitably leads to an increase in the concentration of organic pollutants in environmental objects. The problem of inactivation of such pollutants and water treatment is extremely urgent. The aim of this work was to use combined chemical methods of destruction of tetracycline, as one of the most commonly used antibiotics. The destruction of the active substance of tetracycline under UV irradiation, UV irradiation in the presence of hydrogen peroxide, and UV irradiation in the presence of hydrogen peroxide and ferrous iron ions was studied.

Synthesis of polysubstituted spiropyrrolidines using 2-acetylfuran, 2-acetylthiophene, and 2-acetylpyrrole

Authors: Borisova S. V., Sorokin V. V.

 A series of novel spirooxindoles have been synthesized through three-component 1,3-dipolar cycloaddition of azomethine ylides generated in situ by the decarboxylative condensation of isatin and sarcosine with the dipolarophile 3-phenyl-1-(heteroaryl -2-yl)prop-2-en-1- one, synthesized by the Knoevenagel reaction using 2-acetylfuran, 2-acetylpyrrole, 2-acetylthiophene and substituted benzaldehydes. These compounds are used for the first time as dipolarophiles.

Express determination of cephalexin

Authors: Tumskaia A. V., Kosyreva I. V.

Test means based on immobilized Fehling’s reagent for the determination of cephalexin have been obtained. Methods for visual and colorimetric assessment of antibiotic concentration using a smartphone camera have been developed. The optimal conditions for the indicator reaction have been selected with varying heating time and temperature. For a visual semi-quantitative assessment of the content of cephalexin, a color scale has been obtained.

Determination of thymol with micellar extraction preconcentration

Authors: Tsygulyova E. I., Doronin S. Y.

For the efficient preconcentration of azo compounds – products of the interaction of 4-nitrophenyldiazonium with thymol, a system 4-nitroaniline (4-NA) – NO2 - – Triton X-100 – NaOH – ethanol has been proposed. The optimal conditions for the formation of micellarsaturated phases of the system under study have been established: 3. 10-4 M 4-NA – 3. 10-4 M NO2 - – 5% Triton X-100 – 2.8 M NaOH – 10 vol. % С2Н5ОН. A spectrophotometric study of the above system has been carried out.

ISE on Vitamin B6

Authors: Varygina O. V., Chernova R. K., Сusina E. F.

Sensor obtained by ion associate of vitamin B6 with tetraphenylborate ion and determined its electrochemical characteristics. Method biionnyh potentials determined selectivity coefficients of the electrode. The method of determination of the main substance in the product «Pyridoxine hydrochloride».

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