Doklady Chemistry最新文献

New polymer composite materials (PCMs) were obtained based on a mixture of phenol–formaldehyde and phthalide-containing phenol–formaldehyde resole-type binders reinforced with polyoxadiazole fiber, and their tribological properties were investigated. A study was made of the effect of the content of the phthalide-containing phenol–formaldehyde polymer in the two-component mixture of binders on the hardness of the surface layer and the tribological and thermofrictional properties of the PCM in various systems of dry friction on steel. It was shown that the resulting PCMs are superior in tribological and thermofrictional properties to PCMs based on phenol–formaldehyde or phthalide-containing phenol–formaldehyde resole-type binders.

Heterogeneous and mechanochemical syntheses of new materials based on titanium, calcium, and magnesium phosphates were developed for the first time. The products demonstrated high efficiency as sorbents for the removal of heavy metal cations and radionuclides from solutions. The joint action of the sorption components ensures high sorption capacity towards various cations over a wide pH range. The optimal conditions providing products with a specified phase composition were identified. The use of a solution of a phosphorus-containing agent and solid precursors taken in a stoichiometric ratio, together with mild hydrothermal conditions make it possible to minimize the amount of liquid waste. In the first step of the synthesis, precipitation of titanium phosphate and formation of the precursor needed for the second step (formation of calcium and magnesium phosphates) take place simultaneously. Thus, the synthesis protocol complies with the green chemistry principles.

A method has been developed for the selective C(2)H alkylation of (benz)oxazoles with tertiary alkyl chlorides and alkyl bromides under visible light-induced (460 nm) catalysis with the Pd(PPh₃)₄/[Bu₄N]I system in N,N-dimethylacetamide. The tetraalkylammonium salt has a significant promoting effect on the reaction, which seems to be based on the stabilization of nanosized palladium species in the catalytic system.

A new method has been proposed for the synthesis of bis(phosphine sulfides) and nickel and platinum chelate complexes of 1,3,6-azadiphosphacycloheptanes. The method is based on the ability of 14-membered 3,6,10,13-diazadiphosphacyclotetradecanes to undergo a reversible transformation in solutions into a mixture of meso- and rac-isomers of seven-membered bis-phosphines. The reaction of 3,6,10,13-diazadiphosphacyclotetradecanes with elementary sulfur results in 14-membered tetrakis(phosphine sulfides) or seven-membered bis(phosphine sulfides), depending on the reaction conditions. The reaction of 1,3,6-azadiphosphacycloheptanes, resulting from the reversible dissociation of 14-membered tetraphosphines in chloroform, with Ni(CH₃CN)₆(BF₄)₂ and Pt(COD)Cl₂ gives the corresponding chelate complexes. The structures of the meso-isomer of 1-cyclohexyl-3,6-diphenyl-1-aza-3,6-diphosphacycloheptane-3,6-disulfide, bis-(κ²-1-isopropyl-3,6-diphenyl-1-aza-3,6-diphosphacycloheptane)nickel bis(tetrafluoroborate), bis-(κ²-1-cyclohexyl-3,6-diphenyl-1-aza-3,6-diphosphacycloheptane)chloronickel tetrafluoroborate, and cis-dichloro-(κ²-1-cyclohexyl-3,6-diphenyl-1-aza-3,6-diphosphacycloheptane)platinum(II), isolated in crystalline form, have been confirmed by single crystal X-ray diffraction.

The first example of intramolecular diastereoselective domino reaction of ferrocene 1,1'-bis-enone to [5]ferrocenophane initiated with sodium ethoxide was found. The product is [5]ferrocenophane with two pyridyl and one ethoxy substituents arranged asymmetrically in a five-carbon bridge. Diffraction studies showed that ferrocene is in almost ideal eclipsed conformation. The fan conformation found in the crystal is also preserved in solution, which was determined by NMR spectroscopy.

Reducing carbon dioxide emissions during production is one of the main trends in modern oil and gas chemistry. One of the most realistic possibilities for achieving this is to involve carbon dioxide generated in technological processes as a feedstock for producing gas chemical products. The maximum effect can be achieved in the production of large-scale chemicals, such as syngas, hydrogen, and methanol. We consider such possibilities and present a new combined autothermal process for the joint production of hydrogen and methanol based on non-catalytic matrix conversion of natural gas into syngas, which allows one to almost avoid CO₂ emissions.

A first-generation triazole-containing dendron with hydroxypropyltriazole groups and a tetraethylene glycol linker was synthesized for the first time by stepwise modification of gallic acid by the azide–alkyne cycloaddition reaction. The structures of all intermediate compounds have been proven by advanced physical methods. It has been found that, due to the high mobility of the bromine atom in the benzylic position, the use of bromomethylene gallic acid derivatives in the synthesis of triazole-containing dendrons gives by-products resulting from alkylation of the bases used in the reaction (triethylamine and diisopropylethylamine).

An efficient synthesis of optically pure macrocyclic mono- and binuclear polylactones has been proposed. The synthesis is based on the condensation of natural triol, castor oil, with sebacoyl dichloride in 1 : 1 or 1 : 2 ratios in boiling carbon tetrachloride in the presence of triethylamine and N,N-dimethylaminopyridine as a catalyst.

Previously unknown phenyl-substituted iodo-δ-lactone derived from 11‑phenylundeca-5Z,9Z-dienoic acid was synthesized in 94% yield using the Ti-catalyzed intermolecular cross-cyclomagnesiation of aromatic 1,2-diene with O‑containing allene at the key stage. The in vitro cytotoxic activity of synthesized alkyl- and phenyl-substituted iodo-δ-lactones of 5Z,9Z-dienoic acids against the Jurkat, K562, U937, HL60, and Hek293 cell lines was studied, and their effect on the cell cycle and the ability to induce apoptosis were investigated using flow cytometry.

Methods have been proposed for the preparation of new polyfunctional heterocyclic compounds based on the addition of dichlorocarbene and ethanol to the terminal double bond of 2,2-disubstituted 4-methylene-1,3-dioxolanes, as well as on hydrogenation and ozonolysis of this bond.