Том 67, № 10 (2018)

The literature data concerning features of the kinetics and mechanisms of elementary steps of liquid-phase oxidation of cyclohexane and its oxygen derivatives are considered and analyzed. A comparison of rates of intermolecular and intramolecular reactions of cyclohexylperoxyl radicals under the industrial conditions indicated a necessity to take into account intramolecular interactions. The occurrence of cross recombination of hydroperoxyl and α-hydroxyperoxyl radicals without chain termination in the course of cyclohexanol and 2-hydroxycyclohexanol oxidation was proved. A significance of degenerate branching reactions involving cyclohexyl hydroperoxide in the industrial process of cyclohexane oxidation at 423 K was evaluated. The influence of the electron-withdrawing functional groups on the reactivity of carbon–hydrogen bonds of organic compounds in the reactions with electrophilic peroxyl radicals was studied. The low conversion of a substrate in the industrial process are mainly caused by the radicalchain oxidation of cyclohexanone leading only to by-products. The catalysts of cyclohexane oxidation, viz., compounds of variable valence metals, affect the reaction rate and ratio of the yields of the target products (cyclohexyl hydroperoxide, cyclohexanol, and cyclohexanone) but exert no effect on their relative reactivity. The use of the catalytic additives increasing the yield of cyclohexanone in the step of cyclohexane oxidation in the production of caprolactam is revealed to be inexpedient.

Methods for the preparation of multifunctional dispersions of polymer particles (DPP) in the course of free radical heterophase polymerization, which provides careful control of both macromolecular and colloidal properties, are considered. Approaches that, according to the polymerization technique, make it possible to control the particle diameter and shape, particle size distribution, colloidal stability, morphology, surface chemistry and functionality, as well as the formation of organo-inorganic hybrid particles, are demonstrated. The possibilities of DPP application in homogeneous and heterogeneous assays and cell labelling are reviewed. The use of DPP leads to decrease the reaction scales and costs and to increase the speed, sensitivity, selectivity, and reproducibility of assays.

The results of a study on the photocatalytic activity of aqueous dispersions of Ni-doped CdS nanocrystals (NCs) covered with an amphiphilic polyelectrolyte (PE) shell, i.e., a polycation (NC-PC) or polyanion (NC-PA), are presented for the first time. The H₂ evolution rate measured under identical conditions served as a measure of activity. The NC-PC and NC-PA samples were characterized by similar PE content (~40%) and monomodal size distribution. According to our calculations based on the NC dimensions and lattice parameters, about one macromolecule of the PE is required to stabilize one NC. The average hydrodynamic diameter of the NC-PC was found to be 1.5 times larger than that of the NC-PA due to the difference between their chemical structures and different abilities of ionogenic groups to dissociate. The photocatal ytic activity of the PE-stabilized CdS nanocrystals was significantly influenced by the type of the PE, while the H₂ evolution rate depended on the reducing medium used during the process. When the medium contained Na₂S or when the PE-stabilized NCs were pretreated with Na₂S, the effect of the shell type was more pronounced and the activity of NC-PA was 2 to 14 times higher than that of NC-PC.

Using numerical and analytical methods, a model for microporous carbon adsorbents with slit-shaped pores of different widths was developed. Such pores are formed during activation procedure by the removal of the hexagonal carbon layers burnt out in a graphite-like crystallites. Dubinin’s theory of volume filling of micropores was used to calculate methane adsorption equilibria on these model adsorbents. Isobaric dependences of methane adsorption on pore width, specific micropore volumes, and the specific surface were plotted in the range of pressures from 1 to 10 MPa. It was found that the isobaric adsorption curves had a maximum the position of which depends on both the structural-energy characteristics of the adsorbent and thermodynamic conditions chosen to operate the adsorption system. As pressure increased, the maximum of adsorption shifts to the porous systems with wider pores and larger micropore volume.

Phase behavior and structure formation was studied using optical interferometry, nephelometry, and refractometry in the polymer–solvent–nonsolvent system for DMF solutions of two poly(amic acids): based on 3,3′,4,4′-benzophenonetetracarboxylic acid dianhydride and meta-phenylenediamine (PAA-1) and pyromellitic acid dianhydride and 4,4′-oxydianiline (PAA-2). Distilled water and its mixtures with DMF were used as a nonsolvent. According to the results of the study, isothermal cross sections of the phase state diagram in the threecomponent system were plotted, the position of the critical point, the spinodal, and the conodes were determined, the movement of the figurative points in the system was traced depending on the nonsolvent composition.

This study aims to investigate the role of complexation between reagents and the role of solvation of reagents by solvents in the kinetics of chain reactions of quinone imines with thiols. The thermodynamic characteristics of the complexation of quinone imines with thiophenol in CCl₄, chlorobenzene, and ethanol, as well as of the complexation of quinone imines and thiophenol with these solvents were calculated by quantum chemical methods (DFT calculations at the PBE/cc-pVDZ level of theory) and in terms of the additive-multiplicative model. Both approaches give consistent results. The formation of molecular complexes in quinone imine–thiphenol systems is accompanied by a 10–30 kJ mol^–1 decrease in enthalpy and has only a slight effect on the reaction mechanism.

A series of merocyanine dyes were synthesized by two-component condensation of N-aryl-4-picolinium salts and cyanoacetic acid derivatives. Physicochemical properties of the synthesized dyes were studied.

A series of novel benzo[f]quinolino[3,4-b][1,7]naphthyridine-6,8(5H,9H)-diones, which are promising ligands for the extractive separation of actinides and lanthanides, and also their complexes with lanthanum and europium were synthesized. The molecular and crystal structures of one among the ligands were determined by single crystal X-ray diffraction. The protonation of compounds was investigated by IR and NMR spectroscopy. The electronic structure of starting substances and protonated forms was estimated by DFT calculations.

Fluorinated esters of 2,5-furandicarboxylic acid have been synthesized starting from 2,5-furan dicarboxylic acid dichloride and fluorine-containing diols. The reaction control was performed by means of ¹H, ¹⁹F NMR, and IR-spectroscopy. Thermal stability, as well as glass transition temperature, and intrinsic viscosity parameters of the obtained oligomers have been determined.

Polydimethyl-co-methyl(3-aminopropyl)siloxanes differing in the content of amino groups and molecular weight were synthesized by two pathways, namely, by hydrosilylation of oligodimethyl-co-methylhydrоsiloxane with N-(trimethylsilyl)allylamine (TMSAA) and by copolymerization of octamethylcyclotetrasiloxane with methyl(3-aminopropyl)cyclosiloxanes. The colloid-chemical properties of the synthesized oligomers were studied. The oligosiloxanes possess high surface activity and can reduce the interfacial tension in the interface surfactant solution in toluene–water to 6.7–4.2 mJ m². Aggregatively stable polystyrene suspensions with particle of 0.5 and 0.8 μm in diameter were obtained in the presence of the synthesized oligomers.

Chemoselective methods for O- and N-nitration of steroids fused to the pyrazole ring were developed. The nitrating agents were acetyl, propionyl, and trifluoroacetyl nitrates generated from carboxylic acid anhydrides and either copper nitrate or nitric acid. Depending on the reaction conditions, the developed methods allow both selective nitration at the pyrazole nitrogen atom leaving intact the hydroxy group of steroid framework and dinitration giving rise to the corresponding nitrates of steroidal nitropyrazoles.

The pathways of H–D exchange between quercetin and solvent taking into account the effects of the medium are considered using quantum chemical calculations and the mechanism of selective H–D exchange reaction at the C(2′) position observed only in the presence of Au complexes is identified. It is shown that only the exchange processes in the A-ring have suffi- ciently low activation barriers. In the acidic and alkaline media, these processes occur at lower energies as compared with the reaction in the neutral system, which qualitatively agrees with the published experimental data. It was shown that the Au^I chloride complex with DMSO is able to react with the C–H bond at the C(2′) position by the mechanism of electrophilic substitution under mild conditions.

The rate of sorption and desorption of cinchomeronic and dipicolinic acids on the AB-17-8 strongly basic anion exchanger is limited by slow diffusion of components in the polymer phase. The diffusion coefficient of the organic anion in the phase of the AB-17-8 anion exchanger is equal to (3.7±0.5)•10^–12 m² s^–1. Taking into account high rates of desorption of anions of cinchomeronic and dipicolinic acids from anionite (the half-transformation time is 6 min), the AB-17-8 strongly basic anion exchanger can be recommended for use as a container for development of prolonged drugs based on pyridinedicarboxylic acids.

The bibliometric analysis of scientific works on medicinal chemistry published over the last ten years is performed. The data obtained from the Web of Science Core Collection citation database suggest a decrease in the number of studies in the European developed countries and the United States, while this number increased in China, India, and the Latin American countries. There is a growing number of open-access articles on medicinal chemistry among which the portion of review papers increases. In Russia, this field is extensively progressing: the publication activity from 2008 to 2017 increased 2.5-fold.