Russian Journal of General Chemistry最新文献

The reactions of 3-aminopyridine with 9,10-phenanthrenequinone and 1,2-naphthoquinone under various conditions was studied. The formation of the monoimine was observed in the presence of an additional aromatic ring in the structure of the starting dione. The product of the nucleophilic attack of the amino group at position C4 of the aromatic ring was obtained in the absence of this additional ring. One of the products obtained is a derivative of lawsone, a natural dye with a wide range of bioactivity, including antitumor one. Its structure was additionally confirmed by single crystal X-ray diffraction analysis.

It is known that cable channels, often consisting of multilayer polymer pipes, are used to protect cable lines. Taking into account the fact that cables are heated during operation, important criteria for the reliability of the cable channel are increased heat resistance and flame resistance - for the inner layer of the pipe. Even the most reliable system cannot completely eliminate the possibility of cable damage up to a short circuit in the line. In case of cable breakage, bare wires will be located on the wall of the polymer pipe. In this case, finding the place of cable breakage through the wall of a pipe traditionally made of HDPE dielectric is extremely difficult. When choosing a cable channel of a special design made of special electrically conductive PCM, even in case of damage to the conductive line, it will be possible not only to avoid further destruction, but also to determine the breakdown location. In the assortment of POLYPLASTIC Group there are fundamentally new technical, technological and constructive solutions of current-seeking pipes for cable channels produced under the trademark ELECTROPIPE OS RS OMP, which allows you to determine the place of cable breakdown with an accuracy of up to 12 m. The paper presents a comparative study of multilayer polymer pipes of the ELECTROPIPE RS series, ELECTROPIPE OS RS with an internal refractory layer and ELECTROPIPE OS RS OMP with an internal electrically conductive layer based on a special refractory composition and carbon nanotube concentrate (CNTC). The content of CNTC is 5–10 wt %. All tests were carried out on real pipe samples. The physicomechanical (tensile strength, modulus of elasticity and elongation) and electrophysical characteristics (insulation resistance), as well as resistance to flame (exposure to hot wire, a test for flammability according to the ROSSETI method) were investigated.

The article presents the results of studies subject to establish the dependencies of thermal, mechanical and technological properties of highly filled polyphenylene sulfides depending on the mineral fillers introduced into the glass-filled polyphenylene sulfide. Mineral fillers differed in chemical and physical structure and nature. It is shown that the filling of glass-filled polyphenylene sulfide with powdered fillers does not affect the level of electrophysical properties, but significantly affects the physical, mechanical and technological characteristics of highly filled materials.

The performic acid–sulfuric acid system in methylene chloride was proposed as a key reagent for the synthesis of a number of A-seco-derivatives of allobetulone. As a result, from the same substrate (allobetulone) and reagent (formic acid in methylene chloride), depending on different amounts and method of adding sulfuric acid, 4 differently functionalized derivatives of allobetulon (unsaturated acid, keto acid, formyloxy acid and diacid) were obtained.

A new series of azabenzimidazole compounds was synthesized and characterized with spectral methods such as IR, ¹H NMR, ¹³C NMR and elemental analysis. The target compounds were screened for urease, and acetylcholinesterase inhibitory activities. The synthesized azabenzimidazole containing thiosemicarbazide and oxadiazole moieties showed antiurease activity. 2,2′-[(6-Bromo-2-oxo-1H-imidazo[4,5-b]pyridine-1,3-diyl)bis(1-oxoethane-2,1-diyl)]bis(N-4-nitrophenylhydrazinecarbothioamide) has the best inhibition result with IC₅₀ = 15.80±0.40 µg/mL (15.75±0.15 µg/mL for thiourea).

The reaction of C⁶-unsubstituted 5-aryl-3-(2-pyridyl)-1,2,4-triazine with generated in situ difluoroaryne intermediate (4,5-difluoro-1,2-dehydrobenzene), previously unused for this aim, was studied. New transformations of the 1,2,4-triazine nucleus were discovered, which lead, along with the domino transformation product (10-(1,2,3-triazole-3-yl)pyrido[1,2-a]indole) natural for this transformation, to the formation of unexpected products, namely 1,3,5-tris-substituted 1,6-dihydro-1,2,4-triazin-6-ol and 1H-1,2,4-triazole. The structure of the products was confirmed by physicochemical methods, including X-ray diffraction analysis.

The reaction of 6-methylpyridin-2-ylphosphine with benzaldehyde and p-toluidine was investigated. This reaction leads to the formation of three isomers of acyclic aminomethylphosphine oxide with a moderate yield. The structures of the compounds were confirmed by NMR and IR spectroscopy data. It was shown that the reaction results in the formation of three isomers of acyclic aminomethylphosphine. One of the isomers was isolated in a crystalline form suitable for the single crystal X-ray diffraction analysis. According to the XRD data, the isomer is crystallized as dimers formed by N–H···O hydrogen bonds.

The strengths of the complex thread and single filaments of the copolymer aramid fiber of the Rusar-S brand produced by JSC Research and Production Enterprise “Termoteks” (Russia, Moscow region) and microplastics based on epoxy resin (KDA brand) and prepared using the aramid fiber were determined. It was found that the treatment of the fiber surface during its formation using a suspension of multilayer carbon nanotubes produced by NanoTechCenter LLC (Russia, Tambov,) leads to an increase in the strength of the thread, determined at a clamping length of 70 mm, by 4.4%. The increase in the strength of microplastics under the same conditions was 8.2%. Estimated on the basis of the analysis of the dependence of a single filament strength on the clamping length, the value of the critical fiber length after treatment with nanotubes decreased from 0.59 to 0.43 mm, and the strength increased by 28%, from 4.98 to 6.38 GPa. This leads to an increase in the tensile strength when the matrix is shifted at the interface with aramid fiber, by 67.7%, from 72.8 to 122 MPa. The results obtained indicate the possibility of a significant increase in the strength of the composite material when using aramid fiber modified with multilayer nanotubes. It is noted that the correct application of the correlations linking the tensile strength limits of a complex thread and a microplastic made therefrom is possible only at the approximation of the experimental data using the Weibull–Gnedenko distribution. The hypothesis of compliance of experimental data for aramid fibers treated with nanotubes with the Weibull–Gnedenko distribution was verified by means of nonparametric statistics methods. Electron microscopy has shown that the fiber surface becomes rougher after treatment with nanotubes, which should lead to enhanced adhesive interaction with the matrix.

A new nanocarrier was developed for the delivery of an antidote for poisoning with organophosphorus compounds. The nanocarrier acts as an artificial esterase, hydrolyzing acetylcholine and releasing the antidote (atropine) when acetylcholine level is high. The nanocarrier was made using histidine-containing resorcinarene as a building block. Histidine-resorcinarene was preorganized in a microemulsion media and then polymerized with phenylboronic acid, which acts as a linker between the resorcinarene molecules. Antidote (atropine) was incorporated into the nanocarrier with an encapsulation efficiency of 52.2%. At a neutral pH of 7.4, the nanocarrier hydrolyzes acetylcholine to choline and acetic acid. The acid triggers dissociation of the boronate bonds to dissociate, resulting in nanocarrier degradation and the release of 64.4% of the antidote. Transmission electron microscopy (TEM), dynamic and static light scattering (DLS and SLS, respectively), and IR spectroscopy were utilized to characterize the structure of the nanocarriers. Cyclic voltammetry and NMR spectroscopy were employed to evaluate its ability to hydrolyze acetylcholine. Through fluorescence and NMR spectroscopy, it was demonstrated that the nanocarrier could release substrates (fluorescein and atropine) in in response to the presence of acetylcholine.

It has been established that the variation in the conductance of insulation made with materials of various chemical nature and physical structure (polyvinyl chloride plastic compound and varnished cambric) with a short-term exposure to a mold fungus has an S-shaped character. The unambiguous correlation of the induction period, the stage of rapid increase and the time to reach the quasi-stationary level of conductance with the induction period, the stage of rapid growth, the time to reach the maximum amount of biomass on the surface of the material is due to the sorption by isolation of the metabolic products of the mold fungus. The variation in conductance at short times of exposure to microorganisms (~ 1 month) is reversible. Removal of microorganisms from the surface leads to a decrease in conductance to its original level. With their longer exposure (~ 1 year), the change in conductance may become irreversible as a result of the biochemical decomposition of insulation components, in particular, dialkyl phthalates - polyvinyl chloride plasticizers. Features of the processes of changes in conductance are due to the duration of the growth of microorganisms, the nature of materials and their components. The growth of microorganisms depends primarily on temperature and humidity conditions. For materials with high water absorption (varnished cambric), the most important external factor is temperature, and for materials with low water absorption (polyvinyl chloride) – relative humidity.