Doklady Chemistry最新文献

A new method has been developed for the synthesis of 5,5-disubstituted N-methyl-1,3-oxazinanes as a mixture of diastereomers at the 5-position containing monoterpene and branched alkyl substituents in the 5-position. 1,3-Oxazinanes were obtained for the first time by reacting 2,2-substituted 3-aminopropan-1-ols with formaldehyde and sodium borohydride in one stage.

The effect of carbon supports and preparation methods of Pd/C catalysts on leaching of palladium-containing species to the solution upon interaction of a catalyst with a solvent was considered. The leaching of palladium from the support surface into pure solvents was studied by high resolution mass spectrometry. It has been shown that the type of leached palladium species formed in the solution depends not only on the solvent, but also on the method of catalyst deposition on the support and the support nature. It has been found that the use of phosphorus-doped carbon (PC) as a support also results in palladium leaching into solution. In addition, the activity of the catalysts supported on graphite and PC decreased to the same degree both in the Suzuki–Miyaura and Mizoroki–Heck reactions.

An analysis of literature data on the set of reactions for the production of macromolecules with a high content of phosphorus and sulfur has been carried out, and basic approaches that allow the introduction of these elements into the composition of polymers and polymeric materials have been considered in compliance with the fundamental principles of green chemistry. Methods for synthesis of functional polymers under mild conditions that require minimal energy input from external sources, which can become new growth points for green industrial technologies, are considered. Particular attention focuses on the synthesis of polyphosphazenes and polyphosphoesters for biomedical purposes, as well as on the inverse vulcanization reaction to give polymers used in sorption wastewater treatment, the creation of current sources, and IR optics.

New dialkyldithio derivatives of 2,6-dimethylphenol have been synthesized and characterized. The multifunctional properties have been studied for the first time for these compounds as additives to lubricating oils in friction and wear processes under boundary friction conditions, as inhibitors of high-temperature oxidation of hydrocarbons, and as protectors of metal surfaces. It was determined that even a 0.5 wt % concentration of the synthesized additives in lubricating oils contain more than doubles anti-wear properties. It was shown that the additives exhibit a complex antioxidant effect and high efficiency at all stages of the oxidation process, and even at ultralow concentrations (0.005 wt %), their ability to resist oxidation exceeds widely used analogues. The new additives are of significant interest to modern lubricant science and can be used in motor oil formulations and other lubricants.

Controlled radical polymerization of lauryl methacrylate in polyalphaolefin base oil has been performed for the first time in the presence of 2-cyano-2-propyl dodecyl trithiocarbonate. It has been shown that polymerization proceeds to high monomer conversions and leads to the formation of a polymer with a narrow molecular weight distribution. At the same time, the reaction mixtures retain their transparency after polymerization is completed. The synthesized polymers have a thickening ability, which naturally increases with an increase in their number-average molecular weight.

An approach to designing the structure of Eu²⁺-containing silicate glass-crystalline materials was implemented for the first time, using which a rare-earth activator is introduced into Ba-containing silicates formed during glass crystallization. Eu²⁺-activated fluorine-containing glasses and glass-ceramics in the MgO–BaO–ZrO₂–SiO₂ system were synthesized, and their crystal structure and luminescence properties were studied. It was shown that the simultaneous incorporation of Eu into several different silicate crystals formed during the crystallization of glasses yields a material with a broad luminescence band in the visible part of the spectrum. A study of the luminescence excitation and emission spectra of glass demonstrated the possibility of excitation energy transfer from Eu²⁺ ions to Eu³⁺ ions. The approach proposed for the first time to designing the structure of glass-crystalline materials is quite promising for the further creation of new optical media used in high-power light-emitting diodes.

Mg_3 – nNi_nBPO₇ samples (n = 0–3) were synthesized by gel combustion followed by annealing at 980°C, cooled under inertial-thermal conditions, and then studied by X-ray powder diffraction analysis, IR spectroscopy, and X-ray fluorescence spectrometry. A crystalline phase of Ni₃BPO₇ with the β-Zn₃BPO₇ structure was experimentally obtained for the first time. When varying the composition of the samples from Mg₃BPO₇ to Ni₃BPO₇, in borophosphate, a region of coexistence of α‑Mg₃BPO₇ and β-Ni₃BPO₇ was discovered. Analysis of diffuse reflectance spectra of Mg_1.5Ni_1.5BPO₇ showed the presence of Ni²⁺ cations in an environment different from the symmetrical octahedral or tetrahedral environment.

An efficient approach to the synthesis of (+)-camphor and (–)-fenchone anils has been developed, which involves the reaction of the corresponding bicyclic monoterpenoid ketones with substituted anilines in the presence of in situ prepared (i-PrO)₂Ti(OTf)₂·(i-PrOH)₂ complex, as a homogeneous catalyst, and (i-PrO)₄Ti, as a dehydrating agent. The advantage of the suggested method lies not only in obtaining target products in good yield and high purity, but also in a simplified procedure for their isolation. These products are of interest as potential pharmacologically active compounds, antioxidants for rubber mixtures, and components of 3D-printing formulations.

Here, we report the synthesis of a single-atom alloy Pd₁Ag₆/Al₂O₃ catalyst with an egg-shell distribution of the active component over the catalyst granules for the selective hydrogenation of acetylene traces in ethylene. The formation of an egg-shell structure has been confirmed by electron probe microanalysis, which demonstrates that metals are predominantly localized at a depth of 130–160 µm from the granule surface. Transmission electron microscopy and X-ray photoelectron spectroscopy have provided evidence of the formation of a PdAg substitutional solid solution with electron density transfer from Ag to Pd. The formation of Pd₁ single sites has been confirmed by IR spectra of adsorbed CO. In the selective hydrogenation of acetylene, the synthesized single-atom alloy Pd₁Ag₆/Al₂O₃ with an egg-shell distribution shows high selectivity, which radically exceeds the selectivity of the palladium counterpart.

A number of new derivatives of octahydro-2H-chromene based on monoterpenoid (–)-isopulegol has been synthesized. The composition and structure of the products have been established using NMR spectroscopy, high-resolution mass spectrometry, and X-ray diffraction analysis. It has been shown that the majority of obtained compounds show high analgesic activity in vivo. (4S)‑Diastereomers of morpholinoacetamide derivatives of octahydro-2H-chromene showed the highest efficiency in both tests (acetic acid-induced writhing test and hot plate test).