Vol 67, No 8 (2018)

Literary data on kinetics, catalysis and inhibition of the oxidation reaction of carbonyl compounds with peroxy acids according to the Baeyer—Villiger reaction under aerobic liquidphase oxidation conditions have been considered and discussed. The main reaction channel involves a reversible formation of α-hydroxyperoxy ester and its rearrangement to an ester or a lactone. In the case of homolytic decomposition of α-hydroxyperoxy ester no esters are formed. At all steps the formation and transformation of α-hydroxyperoxy ester are catalyzed by carboxylic acids. The possibility of formation of the second intermediate, presumably dioxirane, is shown. Catalysts of the oxidation processes such as variable-valency metal salts influence the kinetics at all steps in the Baeyer—Villiger reaction. Inhibition of ester formation in the presence of cobalt and manganese salts is associated with catalysis of homolytic decomposition of peroxy acid and α-hydroxyperoxy ester.

Possible reactions of Roussin’s red esters [Fe₂(μ-SC₆H₄R)₂(NO)₄], where R = H, o-NH₂, m-NO₂, m-OH, or m-NH₂, in DMSO solution were investigated by quantum chemical modeling. It was shown that in these systems, numerous reactions can occur, including NO donation, ligand substitution, and decomposition into mononuclear iron nitrosyl complexes. The resulting compounds are also NO donors.

A comprehensive theoretical and experimental research of the diene synthesis involving norbornene (1) and 1,3-cyclopentadiene (2) was carried out. The thermodynamic and kinetic parameters were evaluated by quantum chemical methods, and the structures of stereoisomeric products and the quantitative estimation of their ratio were predicted. The results of quantum chemical analysis were experimentally confirmed. The structures of codimers of 1 with 2 and their ratio were determined by a number of physicochemical methods. A strategy combining the theoretical and experimental studies and enabling to optimize the search for objects for the synthesis and reaction conditions was proposed.

Nanosized low-temperature modifications of titanium(iv) oxide with the anatase and η-phase (TiO_2–x•mH₂O) structures were prepared by the sulfate method (pH <3) and for the first time characterized by a complex of methods (X-ray diffractometry, scanning electron microscopy, IR spectroscopy, Raman spectroscopy, differential scanning calorimetry, low-temperature sorption capacity of samples to nitrogen, and differentiating dissolution). The physicochemical properties of the modifications were compared. Differences in compositions of the surface and volumes of the samples, compositions and structures of the phases (structure of η-phase is superstructure to anatase), and microstructure elements (sizes of crystallites, nanoparticles, and specific surface area; volume of nano- and ultrananopores) were revealed. The region of η-phase stability was found in the coordinates of temperature (T = 50–95 °C) and hydrolysis duration (τ = 10–80 min) and temperature (T≤200 °C) and annealing duration (τ <6 h). The distinctions in the thermal behavior of the nanosized anatase and η-phase were studied. The photocatalytic activity (PCA) is determined by the physicochemical characteristics of the samples and phases and also by the composition and structure of the decomposed substrate. In the case of difenoxazole, the PCA is affected by the compositions of the samples, phases, and surface (the presence of OH groups) and specific surface area, whereas the composition of the samples and specific surface area affect the PCA in the case of thiamethoxam.

Systems based on 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), iron(iii)—HEDP and manganese(ii)—iron(iii)—HEDP, were studied by pH-potentiometry combined with mathematical modeling and NMR. Diverse and highly stable heteronuclear iron manganese complexes were found to exist in the heteronuclear system. The formation of the MnH₃L₂^3–, FeMnH₃L₂⁰, Fe₂MnHL₃^3–, and MnL^2– complexes was established. The relaxation efficiency coefficient REC₂ (relaxivity) of these complexes was evaluated at ~2000 mol^–1 s^–1 L. Therefore, these systems hold promise as MRI contrast agents.

The effect of the inert component nature (argon, helium) in a gas mixture on the morphology and the amount of carbon deposits formed upon methane pyrolysis on a resistive fechral wire catalyst heated by direct current was studied. The carbon deposits had a similar morphology with fibrous texture in all cases. By varying the gas medium composition, one can obtain either fibers with up to 150 μm length and 2–3 μm diameter or short fibers of 8–10 μm length formed from a dense surface carbon layer. In the presence of helium, the amount of carbon deposited on the surface was virtually proportional to the methane content in the gas mixture, while in argon medium, the carbon formation was markedly retarded.

An efficient catalytic method for the synthesis of benzyl- and dibenzylamines by hydrogenating oximes and Schiffbases was developed on palladium supported high-porosity foamed ceramic block catalyst. The multiple regeneration ability of the foamed ceramic block catalyst can significantly decrease the Pd consumption as compared to the use of the conventional 10%Pd/C catalyst. Owing to a high hardness of the foamed ceramic catalyst, the reaction mixture can rapidly be removed from the reactor without using filtering devices. The structures produced by the reaction are fragments of biologically active and natural molecules. Antiproliferative properties of dibenzylamines revealed on the sea urchin embryo model suggest that these compounds can be considered as promising agents for the design of new anticancer drugs.

Hydrogenation of naphthalene and anthracene deposited on Sibunit and active carbon was studied. The reactions were carried out at a temperature of 280 °C and a pressure of 90 atm. The directions for the complete hydrogenation of the investigated substrates were studied. Correlations between the structures of naphthalene and anthracene and their activity in hydrogen absorption are presented. The hydrogenation rates decrease as the substrate is saturated with hydrogen.

Cationic polymerization of butadiene using a titanium tetrachloride—tert-butyl chloride catalytic system allows one to synthesize with high rates and yield fully soluble polybutadiene with controlled molecular characteristics. It was shown that the obtained cationic polybuta diene is characterized by predominantly 1,4-trans-structure and reduced unsaturation. The macromolecules of the cationic polybutadiene contain the initial tert-butyl and end chlorine-containing units.

A series of branched oligophenylenes containing the dioctylfluorene and octylphenothiazine moieties was synthesized using the Suzuki reaction applied within the framework of the A₂ + B₂ + B₃ approach. 1,3,5-tris(7-Bromo-9,9-di-n-octylfluoren-2-yl)benzene and 1,3,5-tris- (4-bromophenyl)benzene were used as the branching co-monomers. It was shown that the fluorescence spectra of co-oligomers containing phenothiazine moieties are shifted to the longwavelength region as compared to the spectra of that without such moieties.

Synthetic procedures towards new N-β-hydroxyethyl- and N-β-bromoethylated 1,1’-[methyl enebis(oxy)]bis(triaz-1-ene 2-oxides) were developed. N-β-Nitroxyethyl[methylenebis(oxy)]- bis(triaz-1-ene 2-oxides) were first synthesized by nitration of N-β-hydroxyethyl derivatives and nucleophilic substitution of the bromine atom of N-β-bromoethyl derivatives. The first representative of a new class of energetic compounds, namely, (1-nitroxymethoxy)triaz-1-ene 2-oxide, was synthesized.

New CF₃-containing derivatives of (5-aminoindol-3-yl)acetic acid were synthesized from 5-nitroindole and trifluoropyruvate or 2-diazotrifluoropropionate. Their reactions with isocyanates allowed us to obtain the series of new ureas, including sulfonylureas, containing a pharmacophore moiety of α-(trifluoromethyl)indolylacetic acid.

New benzoxazolyl-substituted spiroindoline-benzopyrans with electron-withdrawing groups in the indoline fragment were obtained. These compounds exhibit positive P- and T-type photochromism. Structural correlations of the spectrokinetic properties depending on the variation of substituents in the indoline part of the spiropyran molecules were established. Electronwithdrawing groups were found to cause a bathochromic shift of the long-wavelength absorption maxima of the merocyanine isomers as compared to the unsubstituted spiropyran and decrease their lifetime. Conversely, an introduction of electron-donating groups results in a hypso chromic shift of the absorption maxima and an increase in the lifetime of the colored isomers of spiropyrans. Electron-withdrawing substituents at the position 5 of the indoline fragment cause the increase of the colorability of the spiropyrans.

Alkylation of 7-amino-3-tert-butyl-4-oxo-4,6-dihydropyrazolo[5,1-c][1,2,4]triazine-8-carbonitrile led to N¹-substituted derivative, which upon treatment with NaH and MeI in DMF was converted to 1-benzyl-3-tert-butyl-7-dimethylamino-4-oxo-1,4-dihydropyrazolo-[5,1-c][1,2,4]triazine-8-carbonitrile. The latter reacted with Grignard reagents to give high yields of new 3-tert-butyl-3-R-4-oxo-1,2,3,4-tetrahydropyrazolo[5,1-c][1,2,4]triazines (R = Alk, Ph). The reaction course and conditions were studied, and spectral characteristics of the products are discussed.

Binuclear molybdenum(0) carbonyl complexes were synthesized based on naphthophosphacyclophanes containing a 1,6-dihydroxynaphthalene fragment and diethylamide linkers. The physicochemical and spectral characteristics of the synthesized coordination systems were studied.

Encapsulation of biologically active β-oxalylamino substituted O-ethylcarbamate in micelles of non-hydrolyzed and hydrolyzed casein is performed. The AFM studies show that the controlled hydrolysis of casein by trypsine allows preparation of monodisperse nanoparticles with a mean size of 22 nm and with a dispersion of 5 nm. The high-precision coulometric method for the chlorine detection shows that, as compared with initial casein micelles, the formed nanoparticles involve appreciable amounts of chlorine-containing alkylcarbamate. Micellar solubilization allows the preparation of the colloidal form of alkylcarbamate form, which is suitable for its practical application.

A series of mono-, bis-, and tris-substituted lactamomethyl derivatives of diphenols were synthesized. The solution and solid-state structures of these compounds were confirmed by IR and NMR spectroscopy and X-ray diffraction. The in silico evaluation indicated a high probability that these compounds have various biological activities.

O-Polysaccharides (O-antigens) of a number of genetically related Escherichia coli O-serogroups (O17, O44, O73, O77, and O106) and Salmonella enterica O:6,14 possess an identical main chain composed of d-GlcNAc and d-Man residues and differ from each other by the absence or presence of glucose side chains at various positions. Using two-dimensional NMR spectroscopy, we established the structure of the O-polysaccharide of E. coli O106 having two glucose side chains in a hexasaccharide repeating unit.

The TiO₂ and TiO₂—SiO₂ xerogels were prepared by hydrolyzing tetrabutoxytitanium or its mixture with tetraethoxysilane. The synthesis was conducted in an acetic acid—water atmosphere under stationary conditions followed by calcinations. The final TiO₂ and TiO₂—SiO₂ xerogels represented 3D globular pore structure with a narrow globule size distribution. At hydrolysis of terabutoxytitanium, acetic acid vapors favored formation of TiO₂ xerogel with a higher surface area compared to the material produced without acidic catalyst.