Kinetics of oxidative ammonolysis of 4-bromo-<Emphasis Type="Italic">o</Emphasis>-xylene: II. Formation of by-products

Kinetic laws of formation and expenditure of by-products in the oxidative ammonolysis of 4-bromo-o-xylene in the temperature range 633–693 K were studied. It was shown that 4-bromophthalimide formation at high concentration of ammonia occurs through hydrolysis of 4-bromophthalonitrile; carbon dioxide forms by oxidation of 4-bromo-o-xylene and decarboxylation of 4-bromophthalimide; 4-bromobenzonitrile originates from 4-bromo-o-tolunitrile and 4-bromophthalimide. At low concentration of ammonia additional formation routes of 4-bromophthalimide and CO₂ from 4-bromo-o-xylene are realized.     

Exciton and impurity electroabsorption in GaSexTe1-x〈Sn〉 single crystals

The exciton and impurity electroabsorption has been studied in GaSe_xTe_1-x〈Sn〉 (0.7 ?χ?1) exhibiting the properties of residual conductivity (RC). It has been shown that the broadening of the negative exciton peak, the nature of the field dependence of the electroabsorption signal, and its anisotropy in the exciton and impurity region are associated with the presence of internal chaotic fields E_int ≈ 10³ ? 10⁴ V cm^?1 coming into play because of the fluctuating distribution of the tin impurity and the defects inherent in layer crystals. Based on investigations of the impurity electroabsorption (IEA), the depth of occurence (hv = 1.18 eV) and the concentration (N = 10¹⁶cm³) of impurity centres have been determined.     

Kinetics of oxidative ammonolysis of 4-bromo-o-xylene: V. Synthesis of 4-bromophthalonitrile

Oxidative ammonolysis of 4-bromo-o-xylene on a V-Sb-Bi-Zr/γ-Al₂O₃ catalyst gives 74.82 mol % of 4-bromophthalonitrile at a high conversion of the starting xylene in a one-cycle process. The process with recirculation results in decreased number of by-products and contribution of deep oxidation and increased selectivity in 4-bromophthalonitrile up to 95.42–96.58%.     

Kinetics of oxidative ammonolysis of 4-bromo-o-xylene: III. Conversion of 4-bromo-o-tolunitrile as a substrate

Kinetics of oxidative ammonolysis of 4-bromo-o-tolunitrile on V-Sb-Bi-Zr/γ-Al₂O₃-oxide catalyst in the temperature range 633–673 K were studied. We found that the rate of conversion of 4-bromo-o-tolunitrile to the target 4-bromphthalonitrile and CO₂ was described by the half-order equation with respect to the substrate concentration and was independent of the partial pressures of oxygen and ammonia. The byproducts are 4-bromophthalimide formed through the hydrolysis of 4-bromophthalonitrile, CO₂ produced by oxidation of 4-bromo-o-tolunitrile and decarboxylation of 4-bromophthalimide, and 4-brombenzonitrile produced from 4-bromo-o-tolunitrile and 4-bromophthalimide.     

Centred TVD schemes for hyperbolic conservation laws

New first- and high-order centred methods for conservation lawsare presented. Convenient TVD conditions for constructing centredTVD schemes are then formulated and some useful results areproved. Two families of centred TVD schemes are constructedand extended to nonlinear systems. Some numerical results arealso presented.     

Kinetics of oxidative ammonolysis of 4-bromo-o-xylene: IV. Mechanism of formation of the reaction products

Generalized kinetic data were used to analyze the mechanism of formation of the oxidative oxidative ammonolysis products 4-bromo-o-xylene and 4-bromo-o-tolunitrile.     

Kinetics of oxidative ammonolysis of 4-bromo-<Emphasis Type="Italic">o</Emphasis>-xylene: I. Transformations of 4-bromo-<Emphasis Type="Italic">o</Emphasis>-xylene and 4-bromo-<Emphasis Type="Italic">o</Emphasis>-tolunitrile

Kinetic laws of 4-bromo-phthalonitrile synthesis by vapor-phase oxidative ammonolisis of 4-bromo-o-xylene in the range of 633–69 K were studied. It was shown that formation of 4-bromophthalonitrile proceeds successively through 4-bromo-o-tolunitrile. Conversion rates of 4-bromo-o-xylene and 4-bromo-o-toluinitrile were found to be described by half-order equations on the corresponding components and not to depend on the oxygen and ammonia concentrations.     

Photoelectric properties of GaSexTe1−x : Sn single crystals

The paper deals with the results of investigations of the photoelectric properties of GaSe_xTe_1?x : Sn single crystals in a strong electric field.The maximum influence of light on the current-voltage characteristics is observed to beat wavelength between 400 and 800 nm.The sensitivity of the phototrigger effect is about 10⁷$\text{Vcm}{}^2\text{W}$ in these crystals.