Synthesis and Electrophilic Cyclization Reactions of Diphenyl 3-Methylpenta-1,2,4-trienyl Phosphine Oxide

Diphenyl 3-methyl-penta-1,2,4-trienyl phosphine oxide can be readily prepared via an atom-economical [2,3]-sigmatropic rearrangement of the mediated alkenynyl phosphinite formed in situ by reaction of 3-methylpent-1-en-4-yn-3-ol with diphenylchlorophosphine. Electrophilic cyclization reactions of the vinylallenyl phosphine oxide prepared were investigated as it was established that the reactions proceeded with formation of various heterocyclic or highly unsaturated compounds with participation of the allenic and/or 1,3-dienic part of the vinylallenic system with neighboring group participation of phosphoryl and/or vinylic group.

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Acid-Base Properties of 6-Methyluracil-5-carbonitrile and Its N-Methyl Derivatives

Russian Journal of General Chemistry - The constants of acid-base equilibrium of 6-methyluracil-5-carbonitrile in water were determined spectrophotometrically. For the first time,...     

Synthesis of 3-tert-Butyl-7,8-nitro(dinitro)pyrazolo-[5,1-c][1,2,4]triazin-4(6H)-ones

Russian Journal of Organic Chemistry - 3-tert-Butyl-8-nitro-7-R-pyrazolo[5,1-c][1,2,4]triazin-4(6H)-ones (R = H, Cl, Br, NO2, N3) were prepared by nitration with HNO3/H2SO4 of the corresponding...     

Parameters of pulse generators based on 4H : SiC sharp-recovery drift diodes: The influence of electron drift velocity saturation

The generation of high-voltage electrical pulses by generators based on 4H : SiC sharp-recovery drift diode is demonstrated. It is shown that the electron drift velocity saturation influences the shape of output pulses.     

Role of neon in a decaying high-purity helium plasma

The evolution of the electron and atomic and molecular metastable densities and the radiation of the decaying plasma of helium with a 10^–5-fraction of neon additive is experimentally studied. A model of elementary processes in He–Ne plasma is constructed, which describes the formation and destruction of HeNe⁺ and Ne₂ ⁺ molecular ions and their contribution to the formation of the afterglow spectrum by the electronion recombination. The various criteria influence of neon on the parameters of the decaying plasma are studied. The possibility of determining the amount of neon in helium by measuring the relative intensities of helium molecular bands and neon spectral lines in the afterglow is considered.     

Effective fields in laser-driven electron recollision and charge localization

We propose a model to describe correlated two-electron dynamics in strong laser fields during laser-induced recollision between an electron and its parent ion. We derive an effective interaction potential which describes the effect of the laser-driven electron collision with an ion while retaining the correlation between the colliding and the bound electron. Using dissociative ionization of molecular hydrogen as an example, we analyze the dynamics of correlation-driven electron localization in a dissociating hydrogen molecular ion.     

Plasma-volume generation of H<Superscript>−</Superscript> ions in a low-voltage xenon-hydrogen discharge. II

A low-voltage xenon-hydrogen discharge is considered theoretically at an interelectrode distance of L = 1 cm and cathode emission current densities of j _s = 2–20 A/cm². Basic parameters of the discharge plasma, in particular, the total hydrogen and xenon densities, are optimized to attain the maximum possible density of negative hydrogen ions \(N_{H^ - } (L)\) at the plasma-anode boundary. The distributions of the plasma parameters over the discharge gap are calculated for optimized regimes. According to calculations, at intermediate cathode emission current densities (j _s ≈ 5–10 A/cm²) in optimized discharge regimes, the density of negative hydrogen ions in the anode region of the plasma is \(N_{H^ - } (L)\) ≈ (1.5–2.5) × 10¹² cm^?3 and the total plasma pressure is p ₀ = 0.5–0.6 Torr.     

Peculiarities of the dielectric,elastic, and anelastic properties of the PbFe<Subscript>1/2</Subscript>Nb<Subscript>1/2</Subscript>O<Subscript>3</Subscript> ferroelectromagnet at the antiferromagnetic phase transition

Peculiarities in the behavior of the dielectric, elastic, and anelastic properties of the PbFe_1/2Nb_1/2O₃ ceramic ferroelectromagnet have been found and investigated near the antiferromagnetic phase transition (Néel temperature T _N = 160 K). It is established that the transition to the antiferromagnetic phase leads to a decrease in the permittivity and elastic compliance. The anomaly of permittivity found near T _N indicates the presence of magnetoelectric interaction in the magnetically ordered phase.     

Reversed steric order of reactivity for tert-butyl and adamantyl-3-cyanomethylene-1,2,4-triazines

Reactions of 2-(6-tert-butyl-5-oxo-4,5-dihydro-1,2,4-triazin-3(2H)-ylidene)-3-oxo-3-R-propanenitriles (R = t-Bu, Ad-1) with tert-butyl bromoacetate gave the corresponding N(2), C(5)O bis-alkylation products. Treatment of the latter with t-BuLi, in the case of R = t-Bu, led to intramolecular condensation at the exocyclic nitrile group. However, in the case of R = Ad-1, the condensation with the sterically more hindered carbonyl group was observed to give diastereomerically pure 8-cyanopyrrolo[1,2-b][1,2,4]triazine-6-carboxylate derivatives. The structures of the isolated products were confirmed by spectral methods and X-ray single-crystal diffraction.     

High-Selective Catalyst Based on Intermetallic Rh1In1 Particles for Nitrobenzene Hydrogenation

Kinetics and Catalysis - The catalytic performance of a bimetallic RhIn/SiO2 catalyst was studied in the liquid-phase hydrogenation of nitrobenzene. The formation of intermetallic Rh1In1...