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991.
The condensation of -substituted acetophenones with benzylidenebisurea in an acid medium has given 5-R-2-oxo-4,6-diphenyl-1,2,3,4-tetrahydropyrimidones. The analogous condensation of propiophenone forms 5-methyl-2-hydroxy-4,6-diphenylpyrimidine. The tetrahydro derivatives obtained are readily dehydrogenated to 5-R-2-hydroxy-4,6-diphenylpyrimidines.For part XX, see [1]. 相似文献
992.
A. A. Pud G. S. Shapoval V. K. Skubin N. V. Kondrashova Yu. V. Kontsur G. M. Tel'biz 《Theoretical and Experimental Chemistry》1989,25(6):653-658
A study has been made of the electrochemical reductive breakdown (ECRB) of solid-phase chlorinated butyl rubber (CBR). It has been established that CBR does not accept electrons under conditions of fast sweep of electrode potential; however, with prolonged cathodic polarization of the substrate at the polymer/cathode/solution three-phase boundary, it undergoes reduction and subsequent chemical conversion, including intermolecular cross-linking and breakdown of the macromolecules. The rate of ECRB of the CBR depends on the potential and materials of the cathode, and also on the nature of the solvent. In a aprotic medium, the process of CBR breakdown leads to the formation of long polyconjugated structures that color its surface black in the vicinity of the three-phase boundary. In an aqueous medium, no such color is observed, but the products of ECRB are found to contain conjugated double bonds with a shorter conjugation chain than in the case of the aprotic medium. It has been established that he starting reaction in ECRB of CBR is reduction of the C-Cl bond and subsequent elimination of Cl–.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 6, pp. 710–715, November–December, 1989. 相似文献
993.
Electroreduction of benzo-1,2,3-dithiazolium salts and their selenium analogs in nonaqueous solution
V. Sh. Tsveniashvili M. V. Malashkhiya V. N. Gaprindashvili B. Kh. Strelets M. M. Gel'mont Yu. I. Akulin 《Chemistry of Heterocyclic Compounds》1985,21(2):181-184
The electroreduction of benzo-1,2,3-dithiazolium cations and their selenium analogs in aprotic solvents takes place in two steps. The first step is a reversible, one-electron transfer leading to the formation of stable radicals detected by EPR. As a result of further electroreduction, the radicals obtained combine with six electrons to form the corresponding o-aminothio(seleno)phenols. Analysis of the reduction potentials of the compounds studied shows that the substitution of a selenium atom for a sulfur in these cations, especially in the 2 position of the heterocycle, facilitates their electrochemical reduction. The electrochemical activity and the kinetics of nulceophilic substitution in the cations studied are compared.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 219–222, February, 1985. 相似文献
994.
Yu. D. Kholodova 《Chemistry of Natural Compounds》1977,13(2):194-196
Summary The spectrophotometric characteristics of the products of the Chugaev reaction with ecdysones have been studied. Methods have been proposed for determination of ecdysterone and viticosterone E in an artificial mixture and of ecdysterone in extracts of plant raw material by thin-layer chromatography followed by the Chugaev reaction.A. V. Palladin Institute of Biochemistry, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 227–230, March–April, 1977. 相似文献
995.
Perminov V. P. Modyanova A. G. Ryabkov Yu. I. Sevbo O. A. Gailyunas I. A. Kuchin A. V. 《Russian Journal of Applied Chemistry》2002,75(4):636-640
The thermal stability and mechanical strength of composites based on ED-20 epoxy oligomer cured with isomethyltetrahydrophthalic and methylendic anhydrides was studied as influenced by the nature and properties of finely dispersed inorganic fillers, such as carbon black, aluminum oxide, and silica nanoparticles. 相似文献
996.
997.
M. N. Sultankhodzhaev B. Tashkhodzhaev B. B. Averkiev M. Yu. Antipin 《Chemistry of Natural Compounds》2002,38(1):78-82
The known diterpenoid alkaloids karacoline, karakanine, songorine, napelline, 12-acetylnapelline, cammaconine, and a new 7,17-secoalkaloid of the lycoctonine type, secokaraconitine, were isolated from tubers of Aconitum karacolicum. An x-ray structure analysis of the new alkaloid was performed. 相似文献
998.
N. O. Saldabol L. L. Zeligman Yu. Yu. Popelis S. A. Giller 《Chemistry of Heterocyclic Compounds》1975,11(1):45-50
The action of 1 mole of bromine on 6-(2′-furyl)imidazo[2,1-b]thiazole, its 2-methyl-, 3-methyl-, and 2,3-dimethyl-substituted derivatives, and their hydrobromides in chloroform and glacial acetic acid was studied. The bromination of bases containing a methyl group in the 3 position leads primarily to the 5′-derivatives with respect to the furan ring in chloroform, whereas in the remaining cases 5-bromo derivatives with respect to the imidazothiazole system are formed. Compounds of the latter type are formed by the action of bromine in glacial acetic acid or of sodium hypobromite in alkaline media on the bases. The hydrobromides are brominated in both acetic acid and chloroform, regardless of the substituents in the thiazole ring, primarily in the 5′ position of the furan ring. The structures of the bromination products were proved by means of alternative syntheses, thin-layer chromatography, and the PMR spectra. 相似文献
999.
K. Yu. Novitskii Kh. Gresl O. V. Lyubinskaya T. A. Pershina 《Chemistry of Heterocyclic Compounds》1969,5(3):303-307
A study was made of certain transformations of the bicyclic compounds of the fur an series synthesized from 3,4-bis(chloromethyl)furan, N-butyl-4H, 6H-furo [3,4-c]pyrrole and 4H,6H-thieno[3,4-c]furan. On the basis of the same dichloride, 3,4-dimethyl furan and furan-3,4-dialdehyde were synthesized.For part XLVI, see [10]. 相似文献
1000.
V. M. Lembrikov V. V. Volkova L. V. Konyakhina Z. N. Korneva O. V. Pokidova 《Russian Journal of Applied Chemistry》2005,78(8):1209-1212
Data on the kinematic viscosity of phosphoric acid solutions in technical-grade tributyl phosphate and in an industrial extract from a technological purification system based on tributyl phosphate, which contain 0–18% phosphoric acid in terms of P2O5, at 10–70°C are presented. 相似文献