Effect of the nature of the active component and support on the activity of catalysts for the hydrolysis of sodium borohydride

The effect of the nature of an active component and a support on the rate of hydrolysis of aqueous sodium borohydride solutions was studied. It was found that the activity of supported catalysts, which were reduced in a reaction medium of sodium borohydride, decreased in the order Rh > Pt ≈ Ru ? Pd regardless of the nature of the support (γ-Al₂O₃, a Sibunit carbon material, or TiO₂). The catalysts based on TiO₂ exhibited the highest activity. As found by UV-vis diffuse reflectance spectroscopy, the composition and structure of the supported precursor of an active component depend on the nature of the support. It is likely that rhodium clusters with different reaction properties were formed on various supports under the action of a reaction medium.     

“Direct” synthesis of unsolvated aluminum hydride involving Lewis and Bronsted acids

Unsolvated aluminum hydride has been synthesized by the “direct” reaction of aluminum bromide or sulfuric acid with an alkali metal tetrahydroaluminate at 90–102°C in pure toluene or in toluene containing 5–10 wt % diethyl ether. The reaction involving aluminum bromide yields a mixture of unsolvated aluminum hydride phases of poor quality. The reaction with sulfuric acid affords a single-phase product as α-AlH₃ at ≤90°C.     

Carbonyl materials: Preparation,properties, and application

The synthesis of powders, films, and coatings obtained by CVD during thermal decomposition of metal carbonyl vapors is considered. The conditions for obtaining them, as well as their main properties and fields of application, are shown.     

Perturbation of magnetization of a magnetic fluid by ultralow thermal fluctuations accompanying a sound wave

The paper presents the results of theoretical and experimental research of the the effect of perturbation of the magnetization of a magnetic fluid caused by thermal fluctuations in an adiabatic sound wave in the initial area of the magnetization curve. Measurements are conducted on samples of a magnetic colloid with various viscosity of the dispersion medium in the frequency range of 20–60 kHz. In this frequency range, the studied samples are characterized by the absence of thermal relaxation of magnetization. Comparison of the conclusions of the thermal magnetization relaxation model with the results of experiment make it possible to obtain information on the rheological features of the neareast molecular environment of a particle, i.e., nanorheology.     

Application of organotin compounds for protecting wood and other materials and in nonfouling paints

The present review is the third part of a review series dedicated to application of organotin compounds. This part discusses the application of organotin compounds for protection of wood and other natural and synthetic materials from biological damage, as well as biocidal additives to nonfouling paints. The prospects are discussed of using organotin compounds in these areas.     

Promising energetic materials composed of nanosilicon and solid oxidizers

A method for production of mechanically activated energetic compositions consisting of nanosilicon and solid inorganic oxidizers is developed. For the compositions prepared, both high-speed burning and detonation are observed. The propagation of the reaction is accompanied by a high energy release, comparable to the heat of explosion of aluminized high explosives. The compositions are highly sensitive to thermal stimuli and capable of rapid deflagration-to-detonation transition. The results obtained in the work suggest that nanosilicon-based formulations as promising energetic materials for a wide range of applications, from initiating compositions in blasting caps to compositions for small charges in microsystem devices.     

Molecular and crystal structure of tris-(2-hydroxyethyl)ammonium 4-chlorophenoxy acetate

Tris-(2-hydroxyethyl)ammonium 4-chlorophenoxy acetate has been synthesized and characterized by ¹H NMR spectra. The molecular structure of this compound has been established by single-crystal X-ray diffractometry (a = 7.5298(23) ?, b = 22.8112(46) ?, c = 10.0921(16) ?, ?? = 111.42(2)°, V = 1613.7(7) ?³, sp. gr. P2₁/c, d _calcd = 1.382 g/cm³). In a cation, the hydrogen atom, in the presence of a nitrogen atom, forms three intramolecular hydrogen bonds with the O atoms of hydroxyl groups [2.29(3)?C2.31(3) ?]. At the same time, all three cation hydroxyl groups are involved in the formation of three intermolecular H bonds with oxygen atoms of the carboxyl anion group [H-O = 1.81(5)?2.06(4) ?].     

Study of the addition of diazoles to vinylsilanes

The reaction of trimethoxy(vinyl)silane with diazoles in the presence of metal lithium was studied. The structure of the reaction products was assigned by NMR spectroscopy (¹H, ¹³C, ²⁹Si, COSY, NOESY, HMBC, and HSQC). An explanation for the different reactivities of reagents (aliphatic amines, diazoles, allylalkylsilanes, vinylalkylsilanes, and vinylalkoxysilanes) was provided.