Aminoazoles in the three-component synthesis of 7-substituted 6-ethoxycarbonyl-5-methyl-4,7-dihydroazolo[1,5-a]pyrimidines

The three-component synthesis of 7-substituted 6-ethoxycarbonyl-5-methyl-4,7-dihydroazolo[1,5-a]pyrimidines was carried out for the first time by the reactions of aminoazoles (3-aminopyrazole, 3-amino-1,2,4-triazole, or 5-aminotetrazole) with acetoacetic ester and aliphatic, aromatic, or heteroaromatic aldehyde.     

Use of the plastein reaction for the modification of cotton-plant proteins

Pronase hydrolysates have been obtained from cottonseed meal which were then used as a substrate for the performance of the plastein reaction. The possibility has been shown of introducing deficient amino acids — lysine methionine, threonine, and tryptophan — by means of this reaction.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 92–96, January–February, 1986.     

Composition and Structure of [WCl4{N(Et)C(O)}3Cl]: MALDI-TOF Mass Spectrometric Study

The product of introduction of three ethyl isocyanate molecules at the tungsten-chlorine bond, namely, [WCl₄{N(Et)C(O)}₃Cl], was synthesized via thermolysis of tungsten hexachloride with a threefold excess of ethyl isocyanate in dichloroethane and studied by MALDI-TOF mass spectrometry method. In addition to the peak of the molecular ion WCl₄{N(Et)C(O)}₃Cl]^- at 573.9 m/z, the mass spectrum of the complex exhibited the maxima at 342.0, 231.0, and 801.0 m/z assigned to [WOCl₄]^-, [{N(Et)C(O)}₃ · H₂O]⁺, and [WOCl₄{N(Et)C(O)}₆Cl]^-, respectively. These three ions can only form in the hydrolysis of the complex containing a chain ligand.     

Azacarbazoles

Alkylation of 5H-pyridazino [4, 5-b] indole with halogen compounds or dimethyl sulfate in the presence of alkaline reagents gives 2-alkyl-2H-pyridazino [4, 5-b] indoles. Reduction of the methiodide or chlorobenzylate of 5H-pyridazino [4, 5-b] indole also gives 2-alkyl derivatives. LiAlH₄ reduction of 3-alkyl-3H-pyridazino [4, 5-b] indolones-4 gives 3-alkyl-3H-pyridazino [4, 5-b] indoles.For Part I see [1]. The main results of the research were reported at the Conference on Heterocyclic Rings in Organic Synthesis, Kiev, June 1964.     

New 1,2,4-triazine-containing podands: synthesis and properties

A method of one-step C-C coupling of 1,5-bis(2,6-dimethylphenoxy)-3-oxapentane (1a) and 1,8-bis(2,6-dimethylphenoxy)-3,6-dioxaoctane (1b) with 3-methylthio- (2) and 3-amino-1,2,4-triazine (3) and 3-aryl-1,2,4-triazin-5-one (6-8) has been described. The reaction of compounds 1a,b with compounds 2 and 3 in the presence of trifluoroacetic acid results in the addition of the dimethylphenoxy group to the unsubstituted C(5) carbon atom of the triazine ring. The reactions of triazinones 6-8 with compounds 1a,b in a mixture of trifluoroacetic acid and organic anhydrides are accompanied by the acylation of the nitrogen atom adjacent to the reaction center and affords bis[(3-R-1-acyl-5-oxo-1,4,5,6-tetrahydro-1,2,4-triazin-6-yl)-2,6-dimethylphenoxy]-3-oxapentane or -3,6-dioxaoctane. The obtained adducts can smoothly be oxidized under mild conditions to form more stable products of nucleophilic hydrogen substitution in the triazine ring. The extraction and transport of Ca²⁺ and Mg²⁺ cations through an organic membrane by the compounds synthesized are discussed.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2210–2215, October, 2004.     

Resonance regimes in the neighborhood of bifurcation points of codimension 2 in the Couette-Taylor problem

The bifurcation in a dynamical system with cylindrical symmetry dependent on several parameters is studied with reference to the Couette-Taylor problem. Points at which two neutral curves intersect (bifurcation points of codimension 2) corresponding to several independent neutral modes are found. In the neighborhood of the bifurcation points of codimension 2 the interaction of these modes can be described by a system of amplitude equations on the central manifold. If the neutral modes are nonrotationally symmetrical, there exist seven different resonance states that influence the cubic terms of the amplitude system. For the resonances Res 0 and Res 3 the results of calculating the intersection points are presented and the conditions under which stationary regimes exist and are stable are analyzed.     

On the Calculation of an X-Ray Natural Circular Dichroism Signal

The sequential derivation of an expression that describes an X-ray natural circular dichroism (XNCD) signal in the most general case is performed. The obtained expression is used as a basis to consider XNCD signals and their structural origins in copper metaborate CuB₂O₄ crystals at an incident radiation energy near the K absorption edge of copper and lanthanum–gallium silicate La₃Ga₅SiO₁₄ crystals at an incident radiation energy near the K absorption edge of gallium. It has been demonstrated that the measurements of circularly polarized X-ray absorption spectra in combination with corresponding first-principle calculations provide an efficient method for studying the contributions of crystallographically non-equivalent atoms to the X-ray optical activity of crystals.     

Thermal oscillation convection in a layer of liquid with weightlessness or reduced gravitation

Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 2, pp. 84–90, March–April, 1991.     

Silver Electrodeposition from Cyanide Solutions: Effect of Lead Ions

Effect of lead hydroxy compounds on the process of electrodeposition of silver from cyanide electrolytes is studied on an electrode whose surface is renewed in solution by cutting off a thin layer of metal. This permitted to perform the study on both the freshly renewed electrode and at controlled values of the time of the electrode contact with solution t. Shown is that on the freshly renewed electrode (t<1 s) the presence in the solution of lead ions in concentrations c ₁ on the order of 10^–5 M leads to the process depolarization only in the initial portion of a polarization curve. With c ₁ increased to 10^–4 M the effect of depolarization extends on the entire polarization curve. Keeping the electrode in solution after the renewal of the metal surface magnifies depolarization, and the greater the concentration c ₁, the shorter the time period t required to achieve the same effect. These regularities are attributed to catalytic influence of lead adatoms, whose surface concentration depends on c ₁ and t, as well as on the intensity of their incorporation in the silver deposit.