Doklady Chemistry最新文献

This paper presents the scientific and technological principles of electrochemical removal of diffusible hydrogen by reactions of hydroxyl and hydrogen in molten aluminum fluoride slag and in the gas phase. A model was proposed for the electrochemical processes in the weld pool with the formation of aluminum fluoride polymer clusters in TiO₂–CaF₂–Na₃AlF₆ slag to reduce the content of diffusible hydrogen, decrease the volume of slag inclusions, and improve the mechanical properties of bainitic steel welded joints.

A study was made of glass samples obtained from highly purified natural quartz, synthetic silica, and glass grit made of synthetic quartz crystals smelted according to a technology that included elements of the KS-4V technology. It was determined that the transmission spectra of the glasses smelted from various materials have differences in the UV and IR regions.

The Bu₄NI/t-BuOOH oxidative system is widely used in organic synthesis, but mechanistic principles underlying its reactivity are only partially explored. In this work, drawing on the example of the oxidative C–O coupling reaction between compounds with a carbonyl group and (or) a benzyl moiety with N-hydroxyphthalimide, it has been discovered that the coupling with the CH-acidic fragment of the carbonyl group proceeds via ionic mechanism, and the coupling with the benzyl fragment proceeds via radical mechanism. When dimethylacetamide is used as a solvent, the ionic process with the participation of the carbonyl group prevails, while in MeCN the radical process involving the benzyl moiety is realized along with the ionic process. For the oxidative C–O coupling with participation of the benzyl moiety without affecting the α-CH fragment of the carbonyl group, it is advisable to use PhI(OAc)₂, Ce(NH₄)₂(NO₂)₆, or t‑BuOOt-Bu as oxidants for which only radical pathway is characteristic.

A possibility of preparation of 1,2,4-triazines with a residue of 2-amino-1,3,4-thiadiazoles at the C5 position by the solvent-free reaction of ipso-amination of 3,6-di(het)aryl-1,2,4-triazine-5-carbonitriles has been studied. It has been found that the reaction also leads to the corresponding 5-amino-1,2,4-triazines as minor products.

Transformation of H₂PtCl₆ over time under the action of 2-octanol has been studied by NMR, IR spectroscopy, GLC, and GC/MS. It has been found for the first time that the alcohol in a H₂PtCl₆ ⋅ 6H₂O–2-octanol solution is hydrochlorinated to give 2-chlorooctane. Dehydrated platinum chlorides catalyze the elimination of methyl groups in trimethylchlorosilane and hexamethyldisiloxane, which leads to the formation of polydimethylsiloxanes. It has been assumed that the resulting π-complex of H₂PtCl₄ with octene-1 is not stable in a hydrochloric medium and rapidly decomposes to release chloroalkyl.

The condensation of arylpropargyl aldehydes with malonic acid in AcOH has led to the formation of 2-(3-arylprop-2-yn-1-ylidene)malonic acids in 68–85% yields. A similar reaction with 4-fluorophenylpropargyl aldehyde in ethanol in the presence of 2-aminopyridine has resulted in intramolecular cyclization to give previously unknown 5-(4-fluorobenzylidene)-2-oxo-2,5-dihydrofuran-3-carboxylate. The structure of this compound has been studied in detail by X-ray diffraction.

The paper proposes a new one-pot ozonolytic synthesis of acylhydrazones from phenylacrolein acetals, which includes ozonolytic cleavage of the substrate in methanol and treatment of the intermediate peroxides with hydrazides of capric, nicotinic, isonicotinic, benzoic, and para-hydroxybenzoic acids taken in excess.

The radical polymerization of 2-(perfluorohexyl)ethyl methacrylate (FHEMA) initiated by azobis(isobutyronitrile) in the presence of a commercially available chain transfer agent, 2-cyano-2-propyl dithiobenzoate, carried out in trifluorotoluene (TFT) or in supercritical carbon dioxide (scCO₂) was studied for the first time. The conditions were found under which the FHEMA polymerization in TFT or in scCO₂ proceeds under homogeneous conditions with reversible chain transfer via the addition–fragmentation mechanism.

Water-soluble copolymers of sodium styrene sulfonate and 4-methacrylamidosalicylic acid of 93.7 mol % composition have been synthesized, and their interaction with terbium and gadolinium ions has been investigated to fabricate luminescent probes promising for their visualization in biomedical research. It has been shown that, in aqueous solutions in the copolymer concentration range 0.15–1.7 mg mL^–1 and at the ratio [Tb³⁺]/[COO^–] = 1, water-soluble luminescent metal polymer complexes with a luminescence lifetime of 823 µs are formed. When Tb³⁺ ions are partially replaced in the complex by Gd³⁺ ions, bimetallic complexes with intense luminescence are formed.