Vol 86, No 6 (2016)

The structural parameters of the (²Σ⁺//C_∞v)-YbF, (¹A₁//C_2v)-YbF2, (²A₂^′//D_3h)-YbF₃, (¹Ag//D_2h)-YbF₂Yb, (¹Ag//C_2h)-FYbF₂YbF, (¹A₁//C_2v)-FYbF₂YbF, (¹A₁//C_2v)-YbF₂YbF₂, (³B_3u//D_2h)-F₂YbF₂YbF₂, (²A′//C_s)-FYbF₂YbF₂, and (³B₂//С_2v)-F₂YbF₂CeF₂ molecules have been determined. Disproportionation of ytterbium monofluoride (2YbF → YbF₂ + Yb + 0.46 eV) is less exothermic than dimerization (2YbF → YbF₂Yb + 2.10 eV). The bond energy of the ytterbium difluoride molecules in the trans dimer (2.93 eV) exceeds those in the cis dimer (2.86 eV) and the coaxial dimer (1.66 eV). Ytterbium trifluoride dimerizes exothermically (2.95 eV) without spin pairing. The dipole and quadrupole moments of the molecules as well as the charges and spin populations of the atoms and the valence electron configurations of the lanthanides have been calculated.

Mechanism of metals alkylation with an organic halide in the presence of binary systems has been defined in more detail. It has been shown that the passivating film on the surface of zinc and cadmium is partially preserved in the course of the process, and the reaction in diethyl ether is decelerated due to the competitive adsorption of the organyl halide and diethyl ether on the surface of the reacting metal. The ratelimiting stages of the studied alkylation process have been elucidated basing on the experimental data on the effect of the reagents (organyl halide and alkylated metal) nature on the rate of the steady-state reaction and modeling of the suggested catalytic cycle.

Side reactions in the course of esterification of methacrylic acid with triethyleneglycol methyl ether in the presence of homogeneous acid catalyst have been studied. Chromato-mass spectrometry and authentic synthesis have revealed the chemical structure of the products; pathways of their formation have been suggested.

Mono and diesters of 2-vinyloxyethylcarbamodithioic acid were synthesized by the reaction of (1-p-nitrophenyl)-2-vinyloxyethylaminoethanol with carbon disulfide. 3-[2-(Vinyloxyethyl)]-5-(4-nitrophenyl)-1,3-thiazolidine-2-thione was prepared and its structure was proved by X-ray diffraction analysis.

2-Amino-4-[(2-aryloxyethyl)sulfanyl]-6-methylpyrimidines were obtained by S-alkylation of 2-amino-6-methylpyrimidin-4(3H)-thione with 2-aryloxyethyl chlorides. Since 2-amino-4-[(2-chloroethyl)sulfanyl]-6-methylpyrimidine is prone to in situ intramolecular cyclization it cannot be used in Claisen reaction. The bromination of the target compounds provided 5-bromo derivatives; some of their hydrochlorides exhibited fungicidal activity.

Hydrobromic acid reacts with 2-methallylthio- and 2-prenylthio-4(3Н)-pyrimidinones with participation of the double bond to give the products of heterocyclization, and with 2-allylthio- and 2-propargylthio-6-methyl-4(3Н)-pyrimidinones, with the retention of the double bond and the formation of hydrobromides.

Using the hybrid DFT method PBE/3ζ conformational transformations of 1,3-dioxa-2-silacyclohexane in the model one-layer carbon nanotubes were investigated. It was found that the effect of the nanotube force field results in shortening of the Si–O bond distances, decrease in the OSiO bond angle and increase in the interconversion barrier between the chair or semi-chair forms, as well as in appearing of the negative charge on the encapsulated molecule.

New ionic liquids, tetrachloroferrates(III) of quaternary ammonium salts [(CH₃)₂NR₁R₂]FeCl₄ [R₁ = CH₃; C₄H₉; (CH₂)₃CN. R₂ = C₁₀H₂₁; C₁₆H₃₃; CH₂CH₂OH; CH₂C₆H₅], were synthesized and their thermal stability was investigated in air in the range 25–600°С. The mechanism of thermal decomposition of the investigated ionic liquids is suggested in agreement with Hofmann’s rule as β-E2-elimination.

The redox properties of vanadium 5,15-bis(о-methoxyphenyl)-3,7,13,17-tetrabutyl-2,8,12,18-tetramethyl-5,10,15,20-tetraphenylporphyrinates in the reaction with an organic peroxide, specifically dicumyl peroxide, were studied. The kinetic parameters of the reaction were determined and its possible mechanism was suggested. The coordinating capacity of vanadium porphyrinates with respect to dicumyl peroxide and imidazole and the stability of the resulting molecular complexes were estimated. It was shown that the nature of the macrocyclic ligand and the surrounding of the coordination center affect the rate of redox transformations. The isolated structures of the reagents and oxidation intermediates were optimized and their geometric parameters were obtained by the quantum-chemical РМ3 method. The calculation results revealed a high degree of deformation of the intermediate molecule, leading to macrocycle destruction.

Phthalocyanines containing gallic acid moieties were synthesized and investigated by the method of electron absorption spectroscopy. It was shown that in organic solvents the prepared phthalocyanines exist predominantly in associated form.

Intrinsic binding constants of the TMPyP4 porphyrin with G-quadruplex of DNA (ckit2) have been calculated; they can be applied as reference for quantitative evaluation of the possibility of such structures participation in biochemical processes. The conclusion about existence of two different sites of the TMPyP4 binding to ckit2 binding made earlier on the basis of the stepwise complex formation model has been revised using the model of mutual influence (cooperativity) of the ligands bound to the oligonucleotide. The model has been verified using principal component analysis and factor analysis methods. The ckit2 biomolecule can be considered as an oligonucleotide with equivalent mutually affecting binding sites.

New bis-phthalimides were synthesized by 2: 1 condensation of phthalic anhydride and tetrachlorophthalic anhydride with 1,2,4-triazole-3,5-diamine, pyridine-2,6-diamine, and 4-hydroxypyrimidine- 2,6-diamine. The synthesized compounds were characterized by elemental analyses and IR, ¹H NMR, and mass spectra. Their interaction with calf thymus DNA (ct-DNA) was studied by UV-Vis spectrophotometry, cyclic voltammetry, and viscosity measurements, which revealed intercalative mode of binding to ct-DNA. Antibacterial activity of the synthesized compounds against Escherichia coli and Streptococcus mutans was assessed in vitro by the agar well diffusion method. The antioxidant activity of these compounds was estimated by DPPH assay.

Tie line data of {methanol + methyl tert-butyl ether + isooctane} ternary systems were obtained at T = 303.15 K, while data for {methanol + ethylbenzene + isooctane} were taken from literature. The ternary system {methanol + methyl tert-butyl ether + ethylbenzene} and {methyl tert-butyl ether + ethylbenzene + isooctane} were completely miscible. A quaternary system {methanol + ethylbenzene + isooctane + methyl tert-butyl ether} was also studied at the same temperature. In order to obtain equilibium data of the quaternary system, four quaternary sectional planes with several methyl tert-butyl ether/methanol ratios were studied. The effect of the addition of methyl tert-butyl ether on the liquid-liquid equilibrium data of {methanol + ethylbenzene + isooctane} ternary system has been investigate at the same temperature. The distribution curves for ternary and quaternary system was analysed. For the quaternary system {methanol + ethylbenzene + isooctane + methyl tert-butyl ether}, experimental data demonstrated that the distribution coefficient of ethylbenzene between the hydrocarbon and methanol phase on a methyl tert-butyl ether–free basis slightly increases with the increase of methyl tert-butyl ether/methanol ratio. Ternary experimental results were correlated with the UNIQUAC and NRTL equation. The NRTL equation is more accurate than the UNIQUAC equation for the ternary systems studied here. The equilibrium data of three ternary systems were used for determining interactions parameters for the UNIQUAC equation. The UNIQUAC equation fitted to the experimental data appeared to be more accurate than the UNIFAC method for the same quaternary system.

The new chalcone derivatives containing the 1,2,3-triazole ring system, namely, (E)-1-(aryl)-3-{3,5-dimethoxy-4-[(1-(aryl)-1H-1,2,3-triazol-4-yl)methoxy]phenyl}prop-2-en-1-ones, were synthesized in 65–88% yield by the “click chemistry” reactions of substituted acetophenones, 4-hydroxy-3,5-dimethoxy-benzaldehyde, and different substituted azides. The structure of the compounds was determined by the FT-IR, ¹H NMR, ¹³C NMR, and mass spectroscopic analyses. Compounds 6a–6l were screened for in vitro antimicrobial activity by the agar disc diffusion method.

A new series of 1-aryl-3-(1-aryl-1H-[1,2,3]triazol-4-yl)propenones (6a–6j) was synthesized by condensation of substituted acetophenones (5a–5c) with substituted 1-aryl-1H-[1,2,3]triazole-4-carbaldehydes (4a–4d) in the presence of potassium hydroxide under conditions of grinding and microwave irradiation. All the newly synthesized compounds were characterized by the IR, NMR, and mass spectroscopic analyses and their antibacterial activity against gram-positive and gram-negative bacterial strains was evaluated. Among the compounds synthesized, better activity was exhibited by 6a, 6c, 6f, 6g, and 6i.

Four novel tetrahydroisoquinoline derivatives 1–4 were synthesized and characterized by IR, ¹H NMR, HRMS, and single crystal X-ray crystallography. Anticancer effect of the products were studied on five human breast cancer cell lines including MDA-MB-231, MDA-MB-468, SK-BR-3, MCF7, HCC70 T4-2. Compounds 3 and 4 demonstrated higher activity than 1 and 2.

Generalization of experimental results and mathematical models of the effect of ultra-high-frequency (UHF) electromagnetic radiation on details fabricated from energetic polymer materials are presented. Different types of phenomena in irradiated details are dependent on the size of the detail, free path radiation length in the material, absorbed energy, and rate of input of the radiant energy to the material.

Statistical polymers and copolymers were firstly synthesized by polymerization of 3,3-bis(azidomethyl) oxetane (BAMO) and 3-azidomethyl-3-methyloxetane (AMMO) in a triisobutylaluminum–water catalytic system, and their physicochemical, physicomechanical, and themochemical properties were studied. It was found that with increasing fraction of poly-AMMO in the BAMO/AMMO copolymers the strength properties of the copolymers enhance and the degree of crystallinity decreases.

A new technology of manufacturing γ-polyoxymethylene (γ-POM) by the polymerization 1,3,5-trioxane in the presence of a boron trifluoride etherate aprotic catalytic agent and a methylal telogen in the medium of the non-ozone-depleting solvent toluene, with an yield exceeding the yield of γ-POM manufactured by the existing industrial technology by 30% is developed. Regression equations for the yield and weight-average particle size of γ-POM synthesized in the toluene medium were derived by means of the optimal experimental design technique. The equations were used to optimize parameters of the synthesis and obtain γ-POM with the weight-average particle size of 15 μm and the highest possible yield.

The method for determination of phthalate–and acetate ions content in return water of lead II–nickel–phthalate synthesis (LNP product) was developed. It was used the capillary electrophoresis method based on migration and separation of the mixture components in a quartz capillary subjected to electric field due to their different electrophoretic activity. This method allows to determine phthalate–and acetate ions content in the range from 20 to 200 mg/dm³. Developed method is recommended for analytic control of phthalate–and acetate ions content in return water of of LNP product to adjust it and return to the technological cycle.

Methods for the determination of the gel time, one of the most important technological parameters of polymer resins and prepregs, useful in development of curing processes and quality control, have been discussed. The capabilities and limitations, as well as the accuracy and convenience of use of these methods have been considered.

The structuring of the liquid titansiloxan oligomer at higher temperatures is studied. The properties of cover materials were investigated. It is shown that the materials have a high fire resistance and physical and mechanical properties compared to materials with vulcanized cover on the base of liquid siloxane rubbers.

A comparative study of radical polymerization of styrene under thermal and microwave heating conditions has been carried out. The polymerization reaction orders with respect to the monomer and initiator concentrations and the polymerization rate constants have been determined. It has been found that non-thermal microwave effects are not manifested during styrene polymerization, because styrene is a weakly polar substance.

Regularities of liquid-phase oxidation the alkyl aromatic hydrocarbons and their cyclohexyl derivatives to hydroperoxides at presence of phthalimide catalysts are studied. It is established that N-hydroxylphthalimide increases the speed of oxidation of these hydrocarbons and provides high selectivity of formation of their hydroperoxides.