Confined Carbon Mediating Dehydroaromatization of Methane over Mo/ZSM‐5

Non‐oxidative dehydroaromatization of methane (MDA) is a promising catalytic process for direct valorization of natural gas to liquid hydrocarbons. The application of this reaction in practical technology is hindered by a lack of understanding about the mechanism and nature of the active sites in benchmark zeolite‐based Mo/ZSM‐5 catalysts, which precludes the solution of problems such as rapid catalyst deactivation. By applying spectroscopy and microscopy, it is shown that the active centers in Mo/ZSM‐5 are partially reduced single‐atom Mo sites stabilized by the zeolite framework. By combining a pulse reaction technique with isotope labeling of methane, MDA is shown to be governed by a hydrocarbon pool mechanism in which benzene is derived from secondary reactions of confined polyaromatic carbon species with the initial products of methane activation.     

Experimental measurements of the compressibility, temperature, and light absorption in dense shock-compressed gaseous deuterium

Experimental data on the shock compression, temperature, and absorptivity of gaseous deuterium with an initial density close to its value in the liquid state were obtained on a spherical explosion shock-wave generator in a pressure range of 80–90 GPa. The obtained results are compared with the existing experimental and theoretical data.     

Experimental study of the density of aqueous solutions of lithium bromide at temperature of up to 250°C in the range of mass concentrations from 30 to 65 %

The density of aqueous solutions of lithium bromide was studied by the monochromatic gamma-ray attenuation method at the saturation line from the liquidus temperature of up to 250 °C for five samples with initial concentration of 30,927, 39.706, 50,936, 59.322, and 65.148 mass % of LiBr. The errors of temperature and density measurements were ±0.02÷0.05 °C and ±0.05%, correspondingly. Approximating equations and tables of reference data were obtained for density dependencies on temperature and concentration. Measurement results were compared with published data. The work was financially supported by the Russian Foundation for Basic Research (Grant No. 04-02-16302).     

Synthesis and mesomorphic properties of iron(II)-containing dendrimeric complexes derivative of 3,4-n-dodecyloxybenzoyl poly(propylene imine)

Synthesis and characterisation of liquid crystalline (LC) Fe(II) complexes with ‘two-chain’-substituted poly(propylene imine) (PPI) dendrimeric ligand of the first to fifth generations are presented. Compounds were synthesised by complex formation between the metal salt and the corresponding dendrimeric ligands. The purity and structure were proved by different methods. The calculated amount of iron in the complexes was confirmed by the experimental data with a great degree of precision. Iron ions are incorporated into the dendrimer at two sites: at the border and inside of the dendrimeric core. A tetragonal coordination of iron was found. Mesomorphic properties of dendrimer iron(II) complexes were studied, a hexagonal columnar mesophase (Col_h) was evaluated by the results of X-ray scattering. Upon excitation at absorption bands, iron dendrimeric complexes exhibit fluorescence properties.     

2-Arylpropionyl chlorides in kinetic resolution of racemic 3-methyl-2,3-dihydro-4H-[1,4]benzoxazines

Kinetic resolution of racemic 3-methyl-2,3-dihydro-4H-[1,4]benzoxazines in the reaction with chiral 2-arylpropionyl chloride predominantly yielded R*,R*-diastereomers. Ibuprofen acyl chloride as acylating agent was found to be more selective and sensitive to the changes in the reaction temperature as compared to naproxen acyl chloride and 2-phenylpropionyl chloride.     

Determination of methyl-substituted phenols in water by gas chromatography with preliminary iodination

A procedure is developed for determining phenol; 2-, 3-, and 4-methylphenols, and 2,4- and 2,6-dimethylphenols in aqueous media, which consists in the synthesis of iodine derivatives, their extraction with toluene, and determination by gas chromatography with electron-capture detection. The optimal conditions for the iodination of phenols in water are found; also the extraction and gas chromatography behavior of methylphenols and their iododerivatives are investigated. To make the identification of iododerivatives of methylphenols more reliable, they are subjected to acylation with acetic anhydride in the extract. The analytical range of phenols in water is 0.01–10 μg/L, the relative standard deviation is 2–6%, and the duration of analysis is up to 40 min.     

Reaction of methylpheophorbides <Emphasis Type="Italic">d</Emphasis> and <Emphasis Type="Italic">b</Emphasis> with amines

A series of formyl analogs of chlorin e₆ 13-amides were synthesized in high yields by reaction under mild conditions of primary and secondary amines with methylpheophorides b and d. In contrast with the secondary 13-amides, tertiary 13-amides were found as two isomers differing in the orientation of the amide plane relative to the plane of the chlorin ring. Methylpheophorbides b and d were more reactive toward the amines than methylpheophorbide a.     

Extraction and Gas-Chromatographic Determination of Phenol and Cresols in Soil

The effects of the acidity of an aqueous solution, the time of moistening a soil sample, and the time of ultrasonic desorption on the extraction of phenols from soils were studied. The optimum conditions were found. A procedure was developed for the gas-chromatographic determination of 0.05–50 mg/kg of phenol and o- and p-cresols in soil with an error of 10–25%. The time of analysis was 40 min.