Multicomponent assembling of salicylaldehydes,kojic acid and malonic acid derivatives

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Multicomponent Synthesis of 2-(2,4-Diamino-3-cyano-5H-chromeno[2,3-b]pyridin-5-yl)malonic Acids in DMSO

Dimethyl sulfoxide is a widely used solvent in organic synthesis and in the pharmaceutical industry because of its low cost, stability, and low toxicity. Multicomponent reactions are an advanced approach that has become an efficient, economical, and eco-friendly substitute for the conventional sequential multi-step synthesis of various biologically active compounds. This approach was adopted for the synthesis of previously unknown 2-(2,4-diamino-3-cyano-5H-chromeno[2,3-b]pyridin-5-yl)malonic acids via transformation of salicylaldehydes, malononitrile dimer, and malonic acid. It was shown that the use of DMSO at room temperature makes it possible to synthesize previously unavailable compounds. The investigation of the reaction mechanism using ¹H-NMR monitoring made it possible to confirm the proposed mechanism of the transformation. The structure of synthesized 5H-chromeno[2,3-b]pyridines was confirmed by 2D-NMR spectroscopy.     

Synthesis of a new monomer for sulfonated poly(arylene ether sulfones)

Russian Chemical Bulletin - 4-({2,4-Bis[(4-chlorophenyl)sulfonyl]phenyl}thio)benzenesulfonic acid was synthesized based on the scheme suggested from the results of retrosynthetic analysis. This...     

Diastereoselective multicomponent synthesis of (4<Emphasis Type="Italic">RS</Emphasis>,6<Emphasis Type="Italic">SR</Emphasis>)-4,6-diaryl-5,5-dicyano-2-methyl-1,4,5,6-tetrahydropyridine-3-carboxylates

Multicomponent reaction of benzylidenemalononitrile, 2-acetyl-3-arylacrylates, and aqueous ammonia in alcohols at room temperature proceeds stereoselectively to give (4RS,6SR)-4,6-diaryl-5,5-dicyano-2-methyl-1,4,5,6-tetrahydropyridine-3-carboxylates in 55–87% yields. In this reaction, ammonia acts as both the catalyst and the source of nitrogen for constructing tetrahydropyridine cycle.     

Co-synthesis of 1-(3-aminopyridin-2-yl)-1H-benzimidazole and 3-(2-aminophenyl)-3H-imidazo[4,5-b]pyridine

Russian Chemical Bulletin - A new method for the synthesis of N-substituted 3H-imidazo[4,5-b]pyridine via chemical reduction of 1-(3-nitropyridin-2-yl)-1H-benzimidazole in an acidic media was...     

Identification of the mechanical characteristics of composite materials from experimental data of shells of revolution

A method is developed for determining the mechanical characteristics of the layer of a shell of revolution made by winding along the geodesic lines. The functions describing the nonlinear elastic behavior of the material are found by analyzing the data obtained from experiments. The equations for unknown parameters and conditions of their solvability in a particular case are obtained.Kazan State Architecture and Civil Engineering Academy, Tatarstan, Russian. Translated from Mekhanika Kompozitnykh Materialov, Vol. 34, No. 6, pp. 771–776, November–December, 1998.     

Pentaerythritol-based demulsifying agents and their surfactant properties

Pentaerythritol-based block copolymers of ethylene and propylene oxides were synthesized and characterized as surfactants and demulsifiers.     

Synthesis of new 2-(4-vinyl-2H-chromen-2-ylidene)malononitrile-based chromophores

Russian Chemical Bulletin - An approach towards new 2-(4-vinyl-2H-chromen-2-ylidene)malononitriles-derived chromophores was developed. The optical, solvatochromic, and electrochemical properties of...     

Unexpected photochemical transformation of imidazole derivatives containing the 5-hydroxy-2-methyl-4H-pyran-4-one moiety. Environmentally friendly method for the synthesis of substituted imidazo[1,5-a]pyridine-5,8-diones

An unexpected photochemical transformation of imidazole derivatives containing the 5-hydroxy-2-methyl-4H-pyran-4-one moiety was discovered, which led to the synthesis of previously unknown imidazo[1,5-a]pyridine-5,8-dione derivatives. The structures of imidazole and imidazo[1,5-a]pyridine-5,8-dione derivatives were unambiguously determined by X-ray diffraction analysis.     

Fluctuation processes in paraelectric phase of chromium ammonium alum

The electron spin-lattice relaxation times T ₁, linewidths, and the hyperfine structure parameters of the ESR spectra have been measured for chromium ammonium alum and aluminum-chromium ammonium alum at temperatures above the phase transition point. The correlation times characterizing the fast fluctuation processes in the temperature range 84–360 K are determined. It is demonstrated that the correlation times are described by two exponents with different activation energies. It is established that the fluctuations are most probably brought about by vibrations of water molecules with anomalously large amplitudes in the environment of NH ₄ ⁺ ions at high temperatures and also by the reorientations of the SO ₄ ^2? groups at low temperatures. The dehydrated alum samples with partly removed crystallization water have been studied. It is shown that neither fast fluctuation processes nor phase transition are observed in these compounds.