Doklady Chemistry最新文献

The crystalline phase of Mg₃BPO₇ was obtained by gel combustion method and solid-phase synthesis with optimization of annealing temperatures. The effect of precursors and synthesis conditions on the formation of Mg₃BPO₇ was analyzed by X-ray powder diffraction and IR spectroscopy. It was shown that the formation of a mixture of kotoite Mg₃B₂O₆ and farringtonite Mg₃P₂O₈ prevents the formation of Mg₃BPO₇, whereas a significant excess of periclase MgO promotes the production of Mg₃BPO₇.

An active and selective catalyst 1%Pt/CeO₂–ZrO₂ for glycerol hydrodeoxygenation to 1,2-propanediol was synthesized. The reaction was carried out in water under relatively mild conditions: a temperature of 170°C and a hydrogen pressure of 10 atm for 6 h. The glycerol conversion reached 82% with a 74% selectivity to 1,2-propanediol. The high activity and selectivity of the catalyst are due to the high degree of dispersion of supported platinum nanoparticles with a size of less than 2 nm, the optimal Ce : Zr ratio in a mixed oxide support, high specific surface area, and the presence of weak Brønsted acid sites. The presence of zirconium in the mixed oxide support not only gives rise to additional defects in the cerium oxide structure, but also stabilizes the deposited platinum nanoparticles.

A stable diradical 2-{N-[(3s,5s,7s)-adamantyl-1]-N-oxylamino}-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl—a heteroatomic analogue of trimethylenemethane—has been synthesized by reacting lithiated 4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl with 1-nitroso-adamantane, followed by oxidation of the intermediate hydroxylamine. According to X-ray diffraction data, the dihedral angle between the planes of paramagnetic moieties in the paramagnet is close to 60°. Magnetochemical measurements have shown that the energy gap between the triplet and singlet states (2J/k_B; H = –2JS_1/2S_1/2) in the diradical is 880 K. The EPR spectrum of the diradical was simulated using the parameters: S = 1, g_xx = 2.007, g_yy = 2.005, g_zz = 2.006, D = 825 MHz, E = 60 MHz. According to the data of cyclic voltammetry in the anodic region, the diradical undergoes electrochemical oxidation at potentials of 0.79, 1.63, 1.89, and 2.25 V, the first process being chemically and electrochemically reversible. In the cathodic region, the diradical is reduced quasi-reversibly at –1.18 and irreversibly at –2.59 V.

Phosphorus-containing compounds have a huge synthetic potential because of their wide application in pharmaceuticals, biology, agrochemistry, organic synthesis, and materials science. The search for new selective reactions for their preparation requires a deeper understanding of the properties and reactivity of key intermediates, which include phosphorus-centered radicals. Of particular interest are the ways to stabilize such radicals, which have unusual physical properties. This review analyzes and summarizes basic achievements and trends in both the generation of highly reactive phosphorus radicals and their involvement in practically significant synthesis reactions, primarily the formation of phosphorus–carbon bonds, and the pathways for the synthesis of stable radicals, their physicochemical properties, and magnetic resonance parameters. Despite the long historical development of research, important achievements in this area have been made over the past decade.

Acridine has been found to undergo readily concurrent N(1)- and С(9)-functionalization under the action of ethyl aryl-2-oxobut-3-ynoates and water to form pharmacologically promising previously unknown N-alkenylacridones in 80–84% yields.

Redox processes in the H₂PtCl₆·6H₂O–1,1,3,3-tetramethyl-1,3-divinyldisiloxane system both in the presence of ethanol and trimethylchlorosilane, and in the absence thereof were studied by ¹Н, ¹³С, and ²⁹Si NMR spectroscopy and gas–liquid chromatography. It was found for the first time that Pt(IV) and Pt(II) chlorides catalyze the reactions of hydrochlorination of vinyl groups with their transformation into β-chloroethyl groups and the elimination of the latter to form ethylene and dimethylchlorosilanes. Based on the results obtained, it was assumed that Pt(0) is coordinated to the siloxane group. A method to produce a high-temperature hydrosilylation catalyst consisting of nanosized Pt(0) and trimethylsilylsilicate was proposed and successfully tested in practice for curing SIEL-type compounds.

The efficient synthetic approaches to new 2,2'-bipyridine ligands functionalized with a 3-thienyl moiety have been developed. These compounds are of interest as monomeric units for electropolymerization. The “1,2,4-triazine” methodology was used for the synthesis.

An approach was developed for the synthesis of multitarget compounds based on a tacrine molecule conjugated with a vanillin moiety using alkylimine or alkylamine linkers with different alkyl chain lengths (C2–C4). The synthesized conjugates effectively inhibit cholinesterases, displace propidium from the peripheral anionic site of acetylcholinesterase, which implies potential antiaggregant properties, and exhibit high antioxidant activity.

A method for preparing 1-tosyl-3H-naphtho[1,2,3-de]quinoline-2,7-diones by the reaction of N-(9,10-anthraquinon-1-yl)chloroacetamide with sodium p-toluenesulfinate has been developed. Nucleophilic substitution of the tosyl group by nitrogen and oxygen nucleophiles has been found to proceed under mild conditions. The corresponding 1-substituted 3H-naphtho[1,2,3-de]quinoline-2,7-diones have been obtained by the reaction of these compounds with amines, phenol, sodium hydroxide, and sodium azide.

A method for the synthesis of betulin vinyl ether using calcium carbide as a source of acetylene has been proposed. Optimal conditions for synthesis of betulin mono- and divinyl ether have been selected. It has been found that the addition of alkali metal fluorides in an excess of calcium carbide promotes the formation of a divinylated product. Two-dimensional NMR spectroscopy proves the formation of monovinyl ether at the primary alcohol group.