Facile CH arylation using catalytically active terminal sulfurs of 2 dimensional molybdenum disulfide

The first methodology of CH arylation of heteroarene via 2D transition metal dichalcogenides that have catalytically active edge functional groups was described. The terminal sulfur groups could effectively catalyze a formation of an azo-linked intermediate with aryl diazonium salts, leading to produce heteroarenes with good yields. This novel methodology using bulk 2D transition metal dichalcogenides that have catalytically active edge functional groups can apply for various reactions to achieve CC bond formation in the fields of heterogeneous catalysis that is easily separable, highly reusable, and inexpensive method.     

Structure,microstructure and physicochemical properties of BaW<Subscript>1−x</Subscript>Nb<Subscript>x</Subscript>O<Subscript>4−δ</Subscript> materials

Nb-doped BaWO₄ with the assumed formula BaW_1?xNb_xO_4?δ (x = 0, 0.005, 0.01, 0.02 and 0.05) were prepared by solid-state reaction method. Crystal structure and phase composition were determined by X-ray diffraction method. Scanning electron microscopy (SEM) coupled with energy-dispersive spectrometry (EDS) was used to describe microstructure and chemical composition of synthesised materials. It was found that solubility limit of niobium in the BaWO₄ structure is the range 0.5–1 mol%, as formation of second phase—Ba₅Nb₄O₁₅—was observed for samples with higher dopant content. For evaluation of the chemical stability of synthesized materials, the comparative CO₂/H₂O exposure test was performed. Samples were exposed to carbon dioxide- and water vapour-rich atmosphere (7% CO₂ in air, 100% RH) at 298 K for 700 h. During this exposition, the chemical reactions between the samples and the surrounding gaseous atmosphere resulting in formation of barium hydroxide and/or barium carbonate can process. Thermogravimetry (TG) method was used for chemical stability evaluation. The comparison of samples before and after the CO₂/H₂O exposure test was performed. To support the interpretation of TG results, the analysis of gaseous products evolved during thermal treatment of the samples was done using mass spectrometer. The effect of dopant on the BaWO₄ chemical stability improvement was observed. In order to determine the electrical properties of obtained materials, the DC resistance measurements in synthetic air atmosphere were taken. It was shown that niobium doping and the presence of second phase—Ba₅Nb₄O₁₅—leads to an increase in the total conductivity of synthesised materials.     

Formation,microwave spectrum and preliminary structure of selenoketene

Hitherto unknown selenoketene, CH₂CSe, has been produced by pyrolysis of 1,2,3-selenodiazole and identified by observation of microwave absorption from CH₂C&.dbnd;⁸⁰Se and CH₂C⁷⁸Se. The CC and CSe bond lengths of selenoketene agree with bond lengths in ketene, CH₂CO, and in carbonyl sulphide, OCS.     

Synthesis and complex-forming properties of crown ethers incorporating glucuronic acid moieties

Crown ethers1 and4 of the 18-crown-6 type containing two glucose units have been oxidised by KMnO₄ into mono- and dicarboxylic acid derivatives (5 and11), and derivatives with different lipophilicities of the above crown ethers, namely the acetyl, benzyl and butyl derivatives (8–10, 13, 14) and methyl esters (6 and12) have been synthesizedThe association constants (K _a) with Li, Na, K and NH₄ cations measured in CHCl₃ indicate that complexing ability increases on introduction of carboxy groups, and selectivity changes in favour of the Na cation. These compounds were able to transport alkyl-ammonium salts through a CHCl₃ liquid membrane, displaying, however, no chiral recognition ability.     

Computations of atom spectra

This is a contribution to the theory of atoms in abelian categories recently developed in a series of papers by Kanda. We present a method that enables one to explicitly compute the atom spectrum of the module category over a wide range of non‐commutative rings. We illustrate our method and results by several examples.