2-Benzopyrylium salts. 34. Reactions of 3-carboxy-2-benzopyrylium salts with amines. Synthesis of cyclic ketols

3-Carboxy-2-benzopyrylium salts form 3-carboxyisoquinolinium salts, their decarboxylated analogs, or products of contraction of the heterocycle, namely, cyclic ketols, depending on the nature of the amine and solvent. Upon treatment with acids, these ketols are demethylated through the intermediate formation of -acylcarbenium ions and are converted to quinonemethides.For communication 33, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 454–459, April, 1989.     

Cyclization of N-alkylazinium cations with bisnucleophiles. 3. endo adducts in the reaction of quinoxalium salts with β-diketones and their x-ray diffraction analysis

The cyclization of N-alkylquinoxalinium salts with the anions of -dicarbonyl compounds proceeds regioselectively and stereoselectively and leads to endo-3a, 4,9,9a-tetrahydrofuro[2,3-b]quinoxalines. The structure of the cycloadducts was established on the basis of the ¹H and ¹³C NMR spectra and the results of x-ray diffraction analysis.See [1] for Communication 2.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1392–1398, October, 1981.     

Benzoxazines and related compounds

A simple method has been elaborated for synthesizing 2-substituted 4,4-dialkyl-4H-1, 3-benzoxazines by the interaction between nitriles and o-oxyphenyldialkylcarbinols under the influence of acids.For part I, [1].     

Benzoxazole in the hetarylation reaction

N-Acylbenzoxazolium salts formed in situ in the reaction of benzoxazole with acylating agents react with indoles with opening of the oxazole ring to give tri(3-indolyl)methanes. Hetarylation products are formed in the reaction of N-acylbenzoxazolium salts in situ with oxindole and pyrazolone.See [1] for our preliminary communication.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 904–908, July, 1978.     

Enhanced Electrochemical Response of Isoniazid Electrocatalytic Oxidation on RGO-PPD-SiW Modified Electrode

The electroactive composites based on reduced graphene oxide (RGO), poly-o-phenylenediamine (PPD) and heteropolyacids – H₄SiW₁₂O₄₀nH₂O (SiW) and H₃[PW₁₂O₄₀] ⋅ nH₂O (PW) was applied to a screen-printed carbon electrode (SPCE) as a planar three-electrode cell as the first step to creating various devices, in particular, sensors and catalysts. We studied potential use of the modified and unmodified SPCE planar electrode in determining the concentration of antitubercular antibiotic isoniazid (isonicotinic acid hydrazide C₆H₇N₃O or INH). The best result was observed for SPCE+RGO-PPD-SiW. CV of normal saline with various concentrations of C₆H₇N₃O demonstrated linear dependence of the relevant anodic peak current either in the bulk solution upon immersion of the modified electrode or in a droplet on the electrode surface.     

Crystalline and optical properties of Cd<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Zn<Subscript>1–<Emphasis Type="Italic">x</Emphasis></Subscript>S (0.5 ≤ <Emphasis Type="Italic">x</Emphasis> ≤ 1) films doped with silver

The results from studying Cd _x Zn_1–x S (0.5 ≤ x ≤ 1) films fabricated via pyrolysis from thiourea coordination compounds of cadmium and zinc bromides doped with silver ions having impurity concentrations of 10^–7, 10^–6, 10^–5, 10^–4, and 10^–3 mol L^–1 in sputtered solutions are presented. Films prepared at 400°С have the wurtzite lattice. The bandgap of pure and doped films, determined from absorption spectra near the edge of fundamental absorption, varies linearly from 2.5 to 3.11 eV. An order of magnitude increase in the intensity of luminescence is observed after doping with silver.     

Electrodynamic analysis of reflector antennas using a self-consistent method

The electrodynamic analysis of reflector antennas (RAs) is performed with the aid of a self-consistent method. The mathematical model of such antennas is reduced to a system of 2D hypersingular integral equations. By way of example, an RA with a reflector that represents a parabolic cylinder is analyzed. The directional pattern of the antenna and the current-density distributions on the surfaces of the reflector and feed are presented.