Theoretical and Experimental Chemistry最新文献

The catalyst for hydrogenation of organic compounds has been prepared by low-temperature decomposition of complex Ni(COD)(DQ) (COD = 1.5-cyclooctadiene, DQ = duroquinone) in a solution in presence of activated carbon Norit. The catalyst is characterized by high dispersion of nickel-containing particles. It is shown that hydrogenation of quinoline to 1,2,3,4-tetrahydroquinoline in presence of the obtained catalyst occurred with 99 % yield in the case if the catalyst formed in the reaction mixture in situ, or ca. 40 %, if the catalyst had prior contact with air. It has been shown that other substituted quinolines could be hydrogenated in presence of the developed nickel-containing system.

The oxidation of cyclohexene and its methyl derivative with hydrogen peroxide in the presence of a catalytic system based on polyoxomolybdate and cobalt(II) bromide has been studied. It is found that epoxidation and oxidative dihydroxylation of cycloolefins without changing the initial structure are the main reaction routes at a temperature of 50-60°C, a duration of 5-7 h, and a substrate:oxidizer molar ratio of 1:2. The process further proceeds by oxidative decyclization of epoxide and diol into aliphatic oxyaldehydes and oxyacids under more harsh conditions (T = 70-80°C, reaction duration of 20-24 h, molar ratio of cycloolefin:oxidizer 1:4).

Hydrogenolysis of 10% aqueous solution of glucose into propylene glycol on supported Cu-containing oxides has been studied according to target reaction C₆H₁₂O₆ + 4H₂ = 2C₃H₈O₂ + 2H₂O in a flow mode. It is shown that the best propylene glycol productivity (0.9 mmol C₃H₈O₂/(g_cat·h)) achieves on 23Cu-1Cr₂O₃/Al₂O₃ catalyst at 180°C, 4.0 MPa H₂ under a catalyst load of 1.6 mmol C₆H₁₂O₆/(g_cat·h). Is is found that ethylene glycol, hydroxyacetone, erythritol, glycerol, 1,2-butanediol, 1,2,4-butanetriol, and sorbitol are side products of the reaction.

Nanosized TiO₂ was prepared by hydrolysis of titanium tetraisopropoxide in the presence of a new bacterial strain Bacillus paralicheniformis. It was shown that the sample predominantly consisted of rutile nanoparticles with an average size of 15.4 nm. The obtained TiO₂ possessed photocatalytic activity in the process of dye decolorization in effluents of a textile manufacturing industry. It was found that treatment of such solutions by the bacteria Bacillus paralicheniformis followed by irradiation in the presence of TiO₂ increased the process efficiency.

Samples of crystalline carbon nitride doped with oxygen were obtained, which exhibit high photocatalytic activity in the oxidation of benzyl alcohol to benzaldehyde under the action of visible light. The quantum yield of benzaldehyde formation with the participation of the optimal photocatalyst can reach Φ ≈ 49% at λ_irr = 405 nm, which is almost twice as high as when using undoped crystalline carbon nitride. This effect can be associated both with more intense absorption of light in the visible range of the spectrum due to the appearance of the n → π* band of the electronic transition, and with a better separation of photogenerated charges and inhibition of their recombination.

The effect of the formation temperature of the composites based on Ni phosphides and N,P-doped carbon (Ni_xP_y/N,P-C) obtained by pyrolysis of a mixture of H₃PO₄-doped polyaniline and Ni(II) salt on their phase composition and electrocatalytic properties in the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) has been established. It is shown that increasing the pyrolysis temperature from 800 to 900 and 1000°C leads to an increasing in the content of the Ni₂P phase in the composites with simultaneously Ni₁₂P₅ decreasing and NiP eliminating. It is found that the highest activity in HER in an acidic electrolyte, as well as in OER, is inherent to Ni_xP_y/N,P-C formed at 900°C (with a close ratio of Ni₂P and Ni₁₂P₅ particles). The best performance in HER in an alkaline electrolyte is revealed by the obtained at 800°C analogue with dominant NiP particles and the highest N,P-doping level of the carbon.

General data on features of obtaining, structure, and optical and electrical properties of chiral perovskites of different dimensional structures (0D-3D) have been analyzed and summarized. The application of chiral perovskites in optoelectronics, spintronics, and nonlinear optics is considered. An analysis of organic molecules, which are perspective for the synthesis of chiral 3D perovskites is performed. The possibility of the use of chiral dyes for improving the optical characteristics of hybrid perovskite materials is considered.

The kinetics of the liquid-phase oxidation of cumene (RH) with molecular oxygen in the presence of KMnO₄ and N-hydroxysuccinimide (NHSI) is studied. An increase in the reaction rate when adding acetic acid is established. An synergistic effect of KMnO₄ and NHSI in aerobic oxidation of RH is found. This can be associated with the formation of C-centered (R^⦁) and O-centered (SINO^⦁) radicals that participate in the chain initiation stage and the catalysis of the chain propagation stage by the SINO^⦁ radical.

Organic electrolytes based on different solvents (propylene carbonate, γ-butyrolactone, sulfolane, and benzonitrile) with high boiling points have been studied in supercapacitors. The cyclic voltammetry data, dependence of capacitance, internal resistance on voltage, and endurance tests indicate that a solution of spiro-(1,1′)-bipyrrolidinium tetrafluoroborate (SBP-BF4) in benzonitrile is one of the most reliable electrolytes in a voltage range of about 2.5 V up to temperature of 100-110°C . The high electrochemical stability of benzonitrile under such harsh conditions can be explained by the absence of an SEI film formation process on the electrode surface that doesn’t cause a noticeable internal resistance increase and capacity decrease when voltage is increased.

The current state of research on spin-orbit interaction in cofactor-free oxidases and dioxygenases during oxygen activation is considered. The spin activation of triplet oxygen during combustion and respiration is analyzed in comparison with the reactions of flavin-containing enzymes, as well as important cofactor-independent dioxygenases. The mechanism of the triplet-singlet transition in glucose oxidase and a number of dioxygenases, including the RuBisCo oxygenase pathway and chirality-induced spin selectivity, is considered.