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Your search keyword '"Rakitin, O. A."' showing total 341 results
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341 results on '"Rakitin, O. A."'

111. Synthesis of 5-(1,2,5-oxadiazol-3-yl)-1 H-etrazoles from 3-cyano-1,2,5-oxadiazoles.

Author

Godovikova, T., Vorontsova, S., Konyushkin, L., Firgang, S., and Rakitin, O.

Subjects
ORGANIC synthesis, AZOLES, CHEMICAL reactions, CHEMICAL reagents, AZIDES, RING formation (Chemistry), NITROSATION, FURAZANS
Abstract

number of 5-(1,2,5-oxadiazol-3-yl)-1 H-tetrazoles were obtained in high yields by reactions of 3-cyano-1,2,5-oxadiazoles with sodium azide or by nitrosation of furazan-based amidrazones, which are easily prepared from the same starting reagents. [ABSTRACT FROM AUTHOR]

Published
2009
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118. N NMR spectroscopy of nitrofuroxans-qualitative and quantitative method for their determination.

Author

Rakitin, O., Ogurtsov, V., Strelenko, Yu., Godovikova, T., and Khmel'nitskii, L.

Abstract

For the first time, theN NMR spectra of nitrofuroxans were investigated, and it was shown that theN signals are narrow; this allows this method to be utilized analytically. Taking the example of nitrochlorofuroxan, the unusual rearrangement of the 4-nitro isomer to the 3-nitro isomer was found. [ABSTRACT FROM AUTHOR]

Published
1990
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119. Synthesis of Thienothiopyranthiones by a New Molecular Rearrangement

Author

Ogurtsov, V. A., Rakitin, O. A., Rees, C. W., Smolentsev, A. A., Belyakov, P. A., Golovanov, D. G., and Lyssenko, K. A.

Abstract

On heating with alkynes, the readily prepared 1,3-dithioles 3 undergo a new cycloaddition reaction and an unprecedented molecular rearrangement with loss of chlorine to give the first 7H-thieno[2,3-c]thiopyran-7-thiones 4 and 4H-thieno[3,2-c]thiopyran-4-thiones 5 whose structures were confirmed by X-ray diffraction. Unexpectedly, the different alkynes used to form 3 and to convert it into 4 and 5 were incorporated regiospecifically into the thiophene and thiopyran rings, respectively.

Published
2005

121. Synthesis of 3-methyl-4-(5-R-1 H-1,2,4-triazol-3-yl)-1,2,5-oxadiazoles.

Author

Godovikova, T., Vorontsova, S., Konyushkin, L., Firgang, S., and Rakitin, O.

Subjects
AZO compounds, HYDRAZONES, AZOLES, CARBON compounds, AMIDES
Abstract

A number of 3-methyl-4-(5-R-1 H-1,2,4-triazol-3-yl)-1,2,5-oxadiazoles were obtained in high yields by thermal dehydration of acylated 4-methyl-1,2,5-oxadiazole-3-carboxamide hydrazones. [ABSTRACT FROM AUTHOR]

Published
2010
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122. 14N NMR spectroscopy of nitrofuroxans-qualitative and quantitative method for their determination

Author

Rakitin, O. A., Ogurtsov, V. A., Strelenko, Yu. A., Godovikova, T. I., and Khmel'nitskii, L. I.

Abstract

For the first time, the14N NMR spectra of nitrofuroxans were investigated, and it was shown that the14N signals are narrow; this allows this method to be utilized analytically. Taking the example of nitrochlorofuroxan, the unusual rearrangement of the 4-nitro isomer to the 3-nitro isomer was found.

Published
1990
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123. Abnormally Mild Synthesis of Bis(dithiolo)pyrroles from 2,5-Dimethylpyrroles

Author

Amelichev, S. A., Aysin, R. R., Konstantinova, L. S., Obruchnikova, N. V., Rakitin, O. A., and Rees, C. W.

Abstract

Treatment of N-substituted 2,5-dimethylpyrroles 2 with an equilibrated mixture of disulfur dichloride and DABCO in chloroform at 0 °C gives pentathiepinopyrroles 3 in moderate yields; further reaction of 3 with the same mixture at room temperature leads, in an extensive reaction cascade, to bis(dithiolo)pyrroles 4 in high yield; 2 can be converted into 4 in a one-pot operation under unusually mild conditions.

Published
2005

129. [1,2,5]Thia(selena)diazolo[3,4-c]pyridine-4,7-dicarbonitriles: synthesis and electrochemical reduction to radical anions.

Author

Chmovzh, T. N., Kudryashev, T. A., Mikhalchenko, L. V., and Rakitin, O. A.

Subjects
*RADICAL anions, *THIONYL chloride, *ELECTROLYTIC reduction, *SELENIUM dioxide
Abstract

Cyclization of 3,4-diaminopyridine-2,5-dicarbonitrile with thionyl chloride and selenium dioxide afforded [1,2,5]thia- and [1,2,5]selenadiazolo[3,4-c]pyridine-4,7-dicarbonitrile, respectively. Both compounds were electrochemically reduced to the corresponding radical anions. [ABSTRACT FROM AUTHOR]

Published
2024
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130. Synthesis of 4,8-dihydro-7 H-[1,2]dithiolo[3,4- b][1,2,5]oxadiazolo-[3,4- e]pyrazine-7-thione as a new heterocyclic system.

Author

Konstantinova, L., Knyazeva, E., Bagryanskaya, I., Obruchnikova, N., and Rakitin, O.

Subjects
CHEMICAL reactions, OXADIAZOLES, SULFUR monochloride, HETEROCYCLIC compounds, NUCLEAR magnetic resonance spectroscopy, MASS spectrometry
Abstract

The article discusses a study regarding the reactions of 1,2,5-oxadiazoles synthesized with sulfur monochloride as a heterocyclic material. The study uses various methods which include nuclear magnetic resonance (NMR) spectroscopy, elemental analysis, and mass spectroscopy. Result shows that N-ethyl and N-isopropyl groups can interact with sulfur monochloride.

Published
2014
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132. Simple dyes for sensitized solar cells based on hexahydrocyclopentaindole: influence of structure on the photophysical properties of cells.

Author

Mikhailov, M. S., Ustimenko, O. O., Gudim, N. S., Mikhalchenko, L. V., Knyazeva, E. A., Kan, B., Duan, T., Chen, Y., and Rakitin, O. A.

Subjects
*PHOTOVOLTAIC power systems, *DYE-sensitized solar cells, *DYES & dyeing
Abstract

Dyes of various structural complexity, based on the fragments of 4-(2-ethylhexyl)-1,2,3,3a,4,8b-hexahydrocyclopenta[b]indole and cyanoacrylic acid, were obtained. Solar cells sensitized with these dyes were developed, and their key photophysical characteristics were determined. The power conversion efficiency reached 4.64% for the most optimal devices based on a dye with an average structural complexity containing donor and acceptor fragments linked via a thiophene bridge. This value is comparable to the values obtained in the case of solar cells based on dyes of more complex structural types. [ABSTRACT FROM AUTHOR]

Published
2024
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135. Design and Theoretical Study of D–A–π–A Organic Sensitizers with [1,2,5]Thiadiazolo[3,4-c]pyridine, [1,2,5]Selenadiazolo[3,4-c]pyridine, and [1,2,5]Oxadiazolo[3,4-c]pyridine π Component

Author

I. Bolshakov, O., A. Grishina, M., Galushko, A., A. Potemkin, V., and A. Rakitin, O.

Abstract

The study concerns molecular design and theoretical study of novel prospective organic sensitizers based on D–A–π–A concept. A modification of the concept (DA–π–A) and new ways for design of organic sensitizers are proposed. The study shows that π-block plays a key role for the wavelength shift in UV-Vis spectra. An existence of element of higher periods in the π-block provides a noticeable bathochromic shift. The thienyl bridge in A-block provides a red shift with respect to phenyl bridge for [1,2,5]oxadiazolo[3,4-c]pyridines while the phenyl bridge provides a red shift with respect to thienyl bridge for [1,2,5]selenadiazolo[3,4-c]pyridines. The maximal wavelengths are observed for DA-blocks with aliphatic/alicyclic fragments we proposed. An influence of enthalpy of formation and polarity of DA-blocks on bathochromic shift is shown. The quantitative dependencies of wavelengths on the enthalpies and dipole moments are determined. The maximal oscillator strengths are observed for the planar DA-block. Therefore, the conditions for design of compounds possessing the maximal wavelengths and oscillator strengths are different: the latter presupposes the planar structure of DA-block while the first presupposes an existence of nonplanar aliphatic/alicyclic fragments. Thus, the further design of organic sensitizers should include some combination of these concepts.

Published
2015
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