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The architecture of transparent contacts is of utmost importance for creation of efficient flexible light-emitting devices (LEDs) and other deformable electronic devices. We successfully combined the newly synthesized transparent and durable silicone rubbers and the semiconductor materials with original fabrication methods to design LEDs and demonstrate their significant flexibility. We developed electrodes based on a composite GaP nanowire-phenylethyl-functionalized silicone rubber membrane, improved with single-walled carbon nanotube films for a hybrid poly(ethylene oxide)-metal-halide perovskite (CsPbBr3) flexible green LED. The proposed approach provides a novel platform for fabrication of flexible hybrid optoelectronic devices.

We present our studies on the evolution of the normal and superconducting properties with thickness of thin Nb films with a low level of non-magnetic disorder ( $k_Fl\approx 150$ for the thickest film in the set). The analysis of the superconducting behavior points to the presence of magnetic moments, hidden in the native oxide on the surface of Nb films. Using the Abrikosov-Gorkov theory, we obtain the density of surface magnetic moments of $10^{13}$ cm $^{-2}$ , which is in agreement with the previously reported data for Nb films.

3-[(Alkylsulfanyl)methyl]pentane-2,4-diones reacted with phenylhydrazine in the presence of zinc chloride to give the expected products, 4-[(alkylsulfanyl)methyl]-3,5-dimethyl-1-phenyl-1H-pyrazoles, together with 1-(3-methyl-1-phenyl-1H-pyrazol-4-yl)ethanone. The reaction of 3-[(alkylsulfanyl)methyl]-4-(alkylsulfanyl)butan-2-ones with phenylhydrazine under similar conditions afforded 3,4-dimethyl-1-phenyl-1H-pyrazole as the major product.

A novel approach to the synthesis of 3-(alkylsulfanylmethyl)-substituted 1H-indoles was developed based on the Fischer indole synthesis involving accessible β-mercapto ketones. Heterocyclization of 3-[(alkylsulfanyl)methyl]alkan-2-ones and phenylhydrazine by the action of ZnCl2 in MeOH or EtOH gave previously unknown 3-alkyl-3-[(alkylsulfanyl)methyl]-2-methyl-3H-indoles.

The effect of three types of emulsifiers (polyglycerol monostearate ester – E475, sucrose stearate ester – E473 and modified inulin palmitate ester – HP-25) on the starch retrogradation in sponge cake (SC) during storage was investigated. The method of differential scanning calorimetry (DSC) was applied to determine the changes in the starch retrogradation during the staling process. The retrogradation temperature and the enthalpy of the endothermic transition decreased when emulsifiers were added. The lowest values of the enthalpy for the whole storage period were found for SC with 1% HP-25. The methods of differential thermal analysis (DTA) and thermogravimetry analysis (TGA) showed significantly bigger (1.43 times) amount of strongly bound water in the crumb of the SC with E475 and HP-25 in comparison to the control sample on the sixth day of storage. Based on our results, emulsifiers possessed retarding effect on the starch retrogradation and extend the shelf-life of the SC.

5-Methyl-4-[(propylsulfanyl)methyl]-2,4-dihydro-3H-pyrazol-3-one was shown to inhibit the radical-chain peroxidation of 1,4-dioxane, ethylbenzene, and methyl oleate. One peroxyl radical is trapped by each (propylsulfanylmethyl)-substituted 2,4-dihydro-3H-pyrazol-3-one molecule. The reaction rate constant of the compound with a peroxyl radical depends on the structure of the latter and decreases in the series: peroxyl radical of 1,4-dioxane, ethylbenzene, and methyl oleate (k7 × 104, L mol –1 s–1, 333 K: 5.7, 4.1, 1.1). The reason for the observed dependence was discussed.

The properties of the FeBeta zeolite catalyst, MnCe/FeBeta composite catalyst, and FeBeta∥MnCe/FeBeta dual-zone catalytic system were studied in the selective catalytic reduction of nitrogen oxides with ammonia. The combination of the low-temperature (MnCe/FeBeta) and high-temperature (FeBeta) catalysts makes it possible to significantly improve the efficiency of NOx removal in a wide temperature range (200–500 °C) in the presence of the FeBeta∥MnCe/FeBeta system. It was found that this system also demonstrates high activity in the catalytic oxidation of residual ammonia retaining high selectivity in molecular nitrogen formation even under ammonia excess conditions (NH3: NO > 1).

Accumulation of heavy metals (Fe, Cu, Zn, Cd, Pb) and arsenic in water and bottom sediments of the Srepok River in rainy and dry seasons has been assessed. Significant seasonal variations in the concentration of elements in water have been found. The Fe, Cu, Zn, As, and Pb content of sediments did not depend on the season, and the concentration of Cd was higher in the rainy season. At certain periods of time, the concentrations of these elements in river water exceeded those recommended by the national technical regulations of Vietnam: Fe, 2.3–9.5 times; Cu, 1.2–2.8 times; Zn, 1.2–4.5 times; Cd, 1.7–6.8 times; Pb, 1.1–17 times; and As, 1.1–3.7 times. The concentrations of all heavy metals and arsenic in the river water and bottom sediments of industrial zones tended to increase. The results showed, the examined elements can be divided into groups where their concentrations are closely interrelated. These groups are composed of Fe, Cu, Zn, and Pb in the river water, and of Cu, Zn, As, and Pb in sediments. The obtained data prove the necessity of monitoring the levels of heavy metals and arsenic in river water and bottom sediments of industrial zones.

The structure of Pd–Ag/Al2O3 samples with different Ag/Pd ratios has been studied by a complex of physicochemical methods (H2-TPR, XRD, H2-TPD, TEM). Catalysts have been synthesized by supporting an active component on α-Al2O3 and γ-Al2O3. X-ray diffraction analysis has revealed the formation of a Pd–Ag substitutional solid solution with a face-centered cubic crystal lattice owing to alloying of the Pd and Ag components. An increase in the Ag content in the composition of bimetallic nanoparticles hinders the formation of palladium hydride (PdHx), which is completely suppressed at a ratio of Ag/Pd > 0.5. Infrared spectroscopy of adsorbed CO has revealed the formation of single-atom Pd1 sites on the surface of supported Pd–Ag bimetallic nanoparticles isolated from each other by silver atoms. Analysis of the structural stability of isolated Pd1 sites has shown that, under conditions of CO adsorption at 150°C, the stability of the sites can be provided by an increase in the Ag/Pd ratio to ≥2.

Endomorphins endogenous tetrapeptides with the highest affinity for the -opioid receptor. Currently, two tetrapeptides that differ in one amino acid residue have been isolated and characterized. The structure of endomorphins differs from the structure of members of three main families of opioid peptides: endorphins, enkephalins, and dynorphins, which contain the same N-terminal sequence. In the central nervous system, endomorphins are distributed everywhere, where they are primarily responsible for antinociception. Distribution of endomorphins in the immune system, similar to that of other opioid peptides, has allowed to suggest their active participation in the processes of immune regulation. This review summarizes modern views on the structure of endomorphins, their localization, possible intracellular mechanisms of signal transmission and their effects on the processes of activation, proliferation and differentiation of cells of innate and adaptive immunity. Endomorphins actively modulate the functions of the cells of the immune system. Peptides predominantly suppress adaptive immunity reactions. There effects on the functions of innate immunity cells (granulocytes, macrophages, monocytes, dendritic cells) depending on the conditions and can have either an inhibitory or stimulating orientation. Thus, endomorphins can be promising compounds that can effectively regulate both nociceptive signals and processes in the immune system.

Novel one-pot synthesis of trans-stilbene comprises hydrogenation of diphenylacetylene into cis-stilbene followed by its hydroisomerization, over the catalyst being intermetallic PdxIny/Al2O3 system with isolated single-atom Pd1 sites. The hydroisomerization rate in the process is comparable or exceeds the over-hydrogenation into 1,2-diphenylethane thus providing 76% yield of trans-stilbene in the case of Pd2In3/Al2O3 catalyst. This result presumably stems from the formation of ordered single-atom Pd1 sites with favorable hydroisomerization ability on the surface of PdxIny catalysts.

The reaction of 3-[(alkylsulfanyl)methyl]pentane-2,4-diones with nicotinic hydrazide in ethanol as solvent produces 4-[(alkylsulfanyl)- methyl]-substituted 1-(pyridin-3-yl)carbonyl-1H-pyrazoles, whereas 1-acyl-1H-pyrazoles are formed in acetic, propanoic, or pentanoic acid solution. The reaction in methanol in the presence of ZnCl2 is accompanied by elimination of nicotinic acid and the formation of (alkylsulfanyl)methyl-substituted 1H-pyrazoles.

Three-component condensation of propan-2-one with formaldehyde and propane-2-thiol in the presence of sodium hydroxide afforded 3-{[(propan-2-yl)sulfanyl)]methyl}but-3-en-2-one or 4-[(propan-2-yl)sulfanyl]-3-{[(propan-2-yl)sulfanyl]methyl}butan-2-one, depending on the amount of the base. The formation of 4-[(propan-2-yl)sulfanyl]-3-{[(propan-2-yl)sulfanyl]methyl}butan-2-one from 4-[(propan-2-yl)sulfanyl]butan-2-one involved aldol condensation of the latter with formaldehyde and subsequent nucleophilic addition of propane-2-thiol to the C=C double bond of intermediate 3-{[(propan-2-yl)sulfanyl]methyl}but-3-en-2-one in the presence of sodium hydroxide.

The infusion from the aerial part of common lady’s mantle Alchemilla vulgaris L. injected preliminarily for 5 d exhibited neuroprotective properties by normalizing conditioned reflexes and orientational-exploratory behavior indicators of animals after hypoxic exposure. Infusion at a dose of 5 mL/kg was the most active. A. vulgaris infusion at a dose of 5 mL/kg with activation of lipid peroxidation after hypoxic action normalized the content of thiobarbiturate-reactive products in brain homogenate and reduced the concentration of antiradical antioxidants in the lipid extract.

Palladium(II) extraction from hydrochloric acid solutions by 4-[(hexylsulfanyl)methyl]-3,5-dimethyl-1-phenyl-1Н-pyrazole, a new complexing reagent dissolved in toluene or chloroform, was studied. The reagent showed high efficiency in palladium(II) recovery from 0.1–(5–6) М HCl. Palladium(II) is recovered from 1 М HCl by the nonprotonated reagent species according to the coordination mechanism to form the extracted compound [PdCl2μ-L]n (n > 2). The reagent is coordinated to metal ions via the nitrogen atom and the thioether sulfur atom as shown by 1H and 13С NMR spectroscopy. In the temperature range 10–40°С, palladium(II) extraction from 1 M HCl is an endothermic process. The palladium(II) can be quantitatively stripped by a hydrochloric acid solution of thiourea. The reagent (with toluene as diluent) may be recommended for use in palladium(II) concentration from hydrochloric acid solutions and for palladium(II) selective separation from platinum(IV), copper(II), nickel(II), iron(III), and aluminum(III).

Local structure of Pd1 single sites on the surface of Pd1In1 intermetallic nanoparticles supported on α-Al2O3 was investigated by the combination of CO-DRIFTS spectroscopy and DFT. CO-DRIFTS spectra of PdIn/Al2O3 catalyst exhibit only one asymmetric absorption band of linearly adsorbed CO comprising two peaks at 2065 and 2055 cm−1 attributable to CO molecules coordinated to Pd1 sites located at (110) and (111) facets of PdIn nanoparticles. The absence of bridged or hollow-bonded CO bands indicates that multipoint adsorption on PdIn nanoparticles is significantly hindered or impossible. DFT results show that on (110) facet multipoint CO adsorption is hindered due to large distance between neighboring Pd atoms (3.35 Å). On (111) facet multipoint CO adsorption on surface palladium atoms is impossible, since adjacent Pd atoms are located below the surface plane.

A series of oxidative treatments of PdIn-supported intermetallic nanoparticles at different temperatures were performed. The bulk and surface structure of catalyst during phase transformation was investigated by bulk- and surface-sensitive techniques (in situ XAFS, DRIFTS of adsorbed CO). It was found that comparison of palladium and indium fractions in bulk and on the surface suggests the formation of a «core-shell» structure. According to obtained results, the core consists of In-depleted intermetallic compound or inhomogeneous bimetallic phase with the inner core of metallic Pd, when a mixture of indium oxide, metallic palladium and small part of PdIn is present on the surface.

The structure and catalytic characteristics of a bimetallic catalyst containing Pd1In1 nanoparticles deposited on the surface of γ-Al2O3 were studied. The formation of intermetallic nanoparticles was determined by X-ray diffraction analysis and confirmed by X-ray photoelectron spectroscopy and IR spectroscopy of adsorbed CO. In the hydrogenation of acetylene in excess ethylene, PdIn/Al2O3 had significantly higher selectivity of ethylene formation (~86%) than monometallic Pd/Al2O3 (~35%). The high selectivity of PdIn/Al2O3 is explained by two factors: (1) the formation of monatomic Pd1 sites isolated from one another by In atoms and (2) the change in the electronic state of Pd atoms in the intermetallic nanoparticles.

The structure and catalytic properties of a bimetallic Pd–Ag/α-Al2O3 catalyst are studied in the liquid-phase hydrogenation of substituted internal and terminal alkynes using diphenylacetylene, phenylacetylene, 1-phenyl-1-propyne, and 1-phenyl-1-butyne as sample alkynes. IR spectroscopy of adsorbed CO, X‑ray diffraction (XRD), and electron microscopy were used to show that the active sites on the Pd–Ag nanoparticle surface are Pd1 sites. The synthesized Pd–Ag/α-Al2O3 catalyst shows a much higher selectivity in the hydrogenation of internal symmetric and asymmetric alkynes compared to the monometallic Pd/α‑Al2O3 sample. Also, it was found in the hydrogenation of diphenylacetylene and 1-phenyl-1-propyne on Pd–Ag/α-Al2O3 that the rate of the stage of desired olefin hydrogenation substantially decreases, which favors the kinetic control of the process.

In this work an arc model is employed along with electric and spectroscopic measurements to study DC electric arcs in Ar and CO2. The model is aimed at describing the arc and the electrodes. Simulation and experimental results are shown for currents between 150 A and 210 A.

In this paper, we present results obtained by a non-equilibrium modelling and experiments on low-intensity short-length arcs in argon at atmospheric pressure. Two modelling approaches are applied. The first one implies a non-equilibrium description of the quasi-neutral arc column combined with boundary conditions on the electrodes, which are derived from the balance of the electron and the total energy in the space-charge sheaths adjacent to the electrodes. The second approach applies a unified description of the entire inter-electrode region and avoids the assumption of quasi-neutrality. Instead, the Poisson's equation is solved for the self-consistent electric field. The experiments provide data about the arc voltage, which are computed with the model's predictions.

Condensation of pentan-3-one, hexan-2-one, 4-methylpentan-2-one, 5-methylhexan-3-one, or 2,6-dimethylheptan-4-one with formaldehyde and sodium methanethiolate, which is present in sulfidic spent caustic from the Orenburg gas processing plant, yields the corresponding mono- and bis[(methylsulfanyl)methyl]-substituted ketones or their mixtures depending on the reactant ketone structure. Alkylthiomethylation of butan-2-one with equimolar amounts of formaldehyde and sodium methanethiolate results in 3-methyl-5-thiahexan-2-one or, in the case of a twofold excess of the reagents, in 2-methyl-1,5-bis(methylsulfanyl)-4-[(methylsulfanyl)methyl]pentan-3-one. On the basis of 3-methyl-5-thiahexan-2-one, new polyfunctional [(methylsulfanyl)methyl]-substituted alcohol, α-hydroxymethylketone, 1,3-diol, and 1,3-dioxane have been obtained.

The paper gives an overview of the influence of the description of the electron transport properties on the characteristics of a DC microplasma in argon at atmospheric pressure. A spatially one-dimensional model is presented which solves the equations for continuity and conservation of energy of electrons and heavy particles in the entire inter-electrode region, the Poisson equation for the self-consistent electric field coupled with the heat transfer in the cathode and an external electrical circuit for the regulation of the current density. The model is applied to a single setup with an inter-electrode gap of 400 µm for three cases that differ in particular in the drift–diffusion formulation of the transport of electron particles and energy. The results obtained cover discharge regimes from normal glow through abnormal glow to arc discharge. They show that even at similar discharge voltage the plasma properties (particle densities, temperatures of electrons and heavy particles) can differ in the plasma depending on the description of the electron transport.

Three-component condensation of ethyl acetoacetate with formaldehyde and alkanethiols in the presence of 0.1 equiv of sodium hydroxide afforded ethyl 2-[(alkylsulfanyl)methyl]-3-oxobutanoates, and analogous reaction with phenylmethanethiol led to the formation of ethyl 2-[(benzylsulfanyl)methyl]-2-(hydroxymethyl)-3-oxobutanoate. The condensation products reacted with hydrazine hydrate in ethanol at room temperature to give 4-{[alkyl(or benzyl)sulfanyl]methyl}-5-methyl-2,4-dihydro-3H-pyrazol-3-ones which were shown to exist in DMSO-d6 mainly as 1H-pyrazol-5(3)-ol tautomers.

A dual-bed catalytic system has been developed for the complex after treatment of diesel engine exhaust gases comprising nitrogen oxides, CO, hydrocarbons, and residual NH3 (NH3-slip) within wide temperature range. The system demonstrates effective NOx abatement at 200–500 °C. The upstream bed (FeBeta) is responsible for the selective catalytic reduction of NOx by ammonia (NH3-SCR) above ~ 300 °C, while the downstream bed ([Mn–Ce/CeO2–ZrO2 + FeBeta] combined catalyst) provides effective NOx abatement below 300 °C and total oxidation of CO, hydrocarbons, and NH3-slip.

An efficient one-pot procedure has been proposed for the synthesis of 8-methyl-5-[(methylsulfanyl) methyl]-3-thiabicyclo[3.3.1]non-7-en-6-one from accessible natural raw materials. A stable complex of the title compound with gold(III) has been obtained by the extraction method, and the mode of its coordination to the metal ion has been determined by IR and NMR spectroscopy.

Herein we have assessed the state of soil bacterial communities at different levels of pollution with oil. The dependences of the change in the total abundance of non-spore-forming bacteria and bacilli in sodpodzolic soil and typical chernozem have been obtained. The species composition of microorganisms in polluted soils has been assessed. The dynamics of the changes in the structure of bacterial communities with time after single oil pollution has been traced. Several microbiological parameters which can be used as diagnostic tools in case of oil pollution of soil have been found.

The state of soil microbiocenoses at different levels of oil pollution was assessed. The microbiological activity of two types of soils (sod-podzolic and typical black earth) under the conditions of stress caused by oil pollution was determined. The regularities in variation of the ratio and total number of the main groups of microorganisms in different soil types were reveled. The compositions of microorganism species in polluted soils were determined. The dynamics of changes in microbiocenoses after one-time oil spiking was traced. A number of microbiological parameters, which can serve as markers of oil pollution in soil, were proposed.

Volatile organic compounds (VOCs) have a negative effect on both humans and the environment, therefore, it is crucial to minimize their emission. The conventional solution is the catalytic oxidation of VOCs by air, however, in some cases this method requires relatively high temperatures. Thus, the oxidation of short-chain alkanes, which demonstrate the lowest reactivity among VOCs, starts at 250–350 °C. This research deals with the ozone catalytic oxidation (OZCO) of alkanes at temperatures as low as 25–200 °C using an alumina-supported manganese oxide catalyst. Our data demonstrate that oxidation can be significantly accelerated in the presence of a small amount of O3. In particular, it was found that n-C4H10 can be readily oxidized by an air/O3 mixture over the Mn/Al2O3 catalyst at temperatures as low as 25 °C. According to the characterization data (SEM-EDX, XRD, H2-TPR, and XPS) the superior catalytic performance of the Mn/Al2O3 catalyst in OZCO stems from a high concentration of Mn2O3 species and oxygen vacancies.

The paper presents the results of a comparative assessment of the degree of pollution of subtropical brown soils with a number of heavy metals (V, Mo, Co) and arsenic in the zone of influence of solid municipal waste landfill “Sharra”. The landfill is located about 7 km southwest of the center of Tirana. Until the early 1990s it was used mainly for the disposal of industrial waste, subsequently it became an uncontrolled open dump and is now the dumping area for all waste of the capital city of the Republic of Albania. Total metal and As contents were determined by inductively coupled plasma atomic emission spectrometry in samples from 14 sites at different distances from the landfill body. Concentrations of V - in 1.2-1.3 times, Mo - more than in 2.2-4.4 times, Co - in 1.2-1.5 times and As - more than in 3.4 times were exceeded background concentration. It was also revealed 1.7 times higher than the established normative value for As in soils. The obtained results confirm the hypothesis about the negative impact of the Sharra landfill on the adjacent territories.

Fruiting bodies (basidiocarps) of the cultivated mushroom Pleurotus ostreatus (16 strains) were characterized by vibration spectroscopy and chemometrics. According to organic elemental analysis and Megazyme assay, the basidiocarps contained ~6.2&ndash, 17.5% protein and ~18.8&ndash, 58.2% total glucans. The neutral sugar analysis confirmed that glucose predominated in all the samples (~71.3&ndash, 94.4 mol%). Fourier-transformed (FT) mid- and near-infrared (FT MIR, FT NIR) and FT Raman spectra of the basidiocarps were recorded, and the characteristic bands of proteins, glucans and chitin were assigned. The samples were discriminated based on principal component analysis (PCA) of the spectroscopic data in terms of biopolymeric composition. The partial least squares regression (PLSR) models based on first derivatives of the vibration spectra were obtained for the prediction of the macromolecular components, and the regression coefficients R2 and root mean square errors (RMSE) were calculated for the calibration (cal) of proteins (R2cal 0.981&ndash, 0.994, RMSEcal ~0.3&ndash, 0.5) and total glucans (R2cal 0.908&ndash, 0.996, RMSEcal ~0.6&ndash, 3.0). According to cross-validation (CV) diagnosis, the protein models were more precise and accurate (R2cv 0.901&ndash, 0.970, RMSEcv ~0.6&ndash, 1.1) than the corresponding total glucan models (R2cv 0.370&ndash, 0.804, RMSEcv ~4.7&ndash, 8.5) because of the wide structural diversity of these polysaccharides. Otherwise, the Raman band of phenylalanine ring breathing vibration at 1004 cm&minus, 1 was used for direct quantification of proteins in P. ostreatus basidiocarps (R ~0.953). This study showed that the combination of vibration spectroscopy with chemometrics is a powerful tool for the evaluation of culinary and medicinal mushrooms, and this approach can be proposed as an alternative to common analytical methods.

Solid-state ion exchange in mixtures of copper oxides and zeolites can occur at temperatures as low as 200–250 °C in the presence of ammonia (NH3-SSIE), thus providing a low-temperature method to activate zeolites for selective catalytic reduction nitrogen oxide (NH3-SCR). The ammonia induced solid-state ion exchange process is studied in more detail, by monitoring the development of NH3-SCR activity with duration of NH3-SSIE, formation of a mobile linear [Cu(NH3)2]+ complex with X-ray spectroscopy, and the transfer of Cu to the zeolite by XRD, and evaporation of copper(I)-oxide by TGA. We find that the linear [Cu(NH3)2]+ complex is formed in mixtures of copper-oxide and *BEA and CHA zeolites upon exposure to ammonia. Increasing the temperature for NH3-SSIE to well above 300 °C leads to a less efficient Cu-transfer. This indicates that the [Cu(NH3)2]+ complex is crucial for the NH3-SSIE process. The non-monotonous development of NOx conversion and N2O yield with duration of NH3-SSIE is probably due to an initial enrichment of Cu in the outer shell of the zeolite crystals. We also show that the presence of H+ or NH4+-ions in the zeolite are necessary for the NH3-SSIE, and that the transfer of Cu from the Cu-oxides to the zeolites most likely occurs via a surface diffusion process.

The structure and catalytic characteristics of a series of Pd–Cu/α-Al2O3 catalysts with Pd: Cu ratio varied from Pd1–Cu0.5 to Pd1–Cu4 were studied. The use of α-Al2O3 with a small surface area (Ssp = 8 m2/g) as a support made it possible to minimize the effect of diffusion on the catalytic characteristics and to study the structure of Pd–Cu nanoparticles by X-ray diffraction (XRD) analysis. The XRD analysis and transmission electron microscopy (TEM) data indicated the formation of uniform bimetallic Pd–Cu nanoparticles (d = 20–60 nm), whose composition corresponded to a ratio between the metals in the catalyst, and also the absence of monometallic Pd0 and Cu0 nanoparticles. The study of catalytic properties in the liquid-phase hydrogenation of diphenylacetylene (DPA) showed that the activity of the catalysts rapidly decreased with the Cu content increase; however, in this case, the yield of a desired alkene compound significantly increased. The selectivity of alkene formation on the catalysts with the ratios Pd: Cu = 1: 3 and 1: 4 was superior to the commercial Lindlar catalyst.

The effect of palladium segregation was studied which resulted from the effect of CO and O2 on the surface structure and catalytic characteristics of the Pd–Ag2/Al2O3 catalyst. The IR-spectroscopic study of adsorbed CO showed that Pd1 centers isolated from each other by silver atoms predominated on the surface of reduced Pd–Ag2/Al2O3, as evidenced by the almost complete absence of absorption bands typical for the multicentred CO adsorption. In the course of catalyst treatment with CO and O2, the intensity of absorption bands characteristic of the multicenter CO adsorption considerably increased due to the transformation of a portion of monatomic Pd1 centers into multiatomic Pdn ones as a result of the surface segregation of Pd. In this case, a substantial increase in the catalyst activity in the liquid-phase hydrogenation of diphenylacetylene was observed. It was established that, after treatment with CO, the catalyst selectivity for the formation of a target olefin (stilbene) remained almost constant, whereas the treatment with O2 led to a decrease in the selectivity because of more considerable surface modification.

Palladium(II) extraction from hydrochloric acid solutions with a novel weakly basic complexing reagent, 4-[(hexylsulfanyl)methyl]-3,5-dimethyl-1H-pyrazole, dissolved in chloroform was studied. Palladium(II) was found to be highly efficiently extracted from 0.1–3 mol/L HCl solutions. A coordination mechanism of palladium(II) extraction with a protonated form of the reagent via fast interphase transfer of ion associates was proposed. The composition of the extracted compound, [PdCl2μ-L]n (n > 2), was found, and the way of coordination of the reagent to metal ions through N(2) nitrogen atom and thioether sulfur atom was determined. The reagent can be recommended for concentrating palladium(II) and selectively separating it from platinum(IV), copper(II), nickel(II), and iron(III).

New 4-[(alkylsulfanyl)methyl]- and 4-[(alkanesulfonyl)methyl]isoxazoles and -1H-pyrazoles were synthesized by reactions of 3-[(alkylsulfanyl)methyl]- and 3-[(alkanesulfonyl)methyl]pentane-2,4-diones with hydroxylamine and hydrazine, phenylhydrazine, semicarbazide, or thiosemicarbazide, respectively. The heterocyclization of 3-[(alkylsulfanyl)methyl]pentane-2,4-diones with thiosemicarbazide and semicarbazide hydrochloride was accompanied by elimination of amide or thioamide group. 3-[(Alkanesulfonyl)methyl]pentane- 2,4-diones were found to exist in solution as enol tautomers; they were prepared by oxidation of the corresponding 3-[(alkylsulfanyl)methyl]pentane-2,4-diones with hydrogen peroxide in acetic acid in the presence of a catalytic amount of sulfuric acid.

A treatment of PdAg3/Al2O3 catalyst with CO at 250 °C enhanced its activity towards the selective C2H2 hydrogenation without any noticeable losses of C2H4 selectivity. The CO-DRIFTS and XPS data acquired in situ have indicated that the observed effect arises from Pd surface segregation induced by the CO adsorption and partial transformation of isolated surface Pd1 active sites into Pd2 dimers. The catalytic performance of PdAg3/Al2O3 was found to be similar or even better as compared to the best reported catalysts.

In this microreview, we consider the methods used for the synthesis of tetrahydro-4H-thiopyran-4-ones over the last 7 years.