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211.
Ohne ZusammenfassungHerrn Prof. Dr.A. Franke in aufrichtiger Verehrung zum 80. Geburtstag gewidmet. 相似文献
212.
213.
214.
O. V. Drygina G. N. Dorofeenko O. Yu. Okhlobystin 《Chemistry of Heterocyclic Compounds》1981,17(4):320-324
Nitrogen heterocycles, viz., pyridines, pyridinium salts, diazepine, and pyrazoles, with an o-carboranyl substituent were obtained by reaction of 4-(o-carboranyl)-pyrylium perchlorates with nitrogen-containig nucleophilic agents, viz., ammonia, primary amines, hydrazine, and phenylhydrazine. Opening of the pyrylium ring without involvement of the carborane ring occurs under the influence of bases.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 454–458, April, 1981. 相似文献
215.
Magnetic susceptibility of Cs3Cr2Cl9 as a single crystal is studied in the temperature range 4.2–77 K. A maximum is obtained at 25 ± 1 K. These experimental data are interpreted by considering the isotropic exchange interaction between two spin quadruplets. The exchange constant J is found to be equal to - 13 cm?1. 相似文献
216.
217.
O. V. Ignatenko A. S. Arkhangel'skaya É. I. Chupka 《Chemistry of Natural Compounds》1992,28(3-4):361-364
The results are given of a determination of the steady-state concentrations of peroxide compounds on the oxidation of lignin by oxygen in dioxane. An iodometric method of determining peroxides was used, with spectrophotometric control of the amount of iodine formed. It was established that the achievable steady-state concentration of peroxide compounds on the oxidation of lignin is 0.28–0.44 wt. % of Oact (oxygen pressure 1 atm, temperature 50–80°C). With a rise in the temperature, the steady-state concentration of peroxide compounds decreased. The addition of water (30 vol. %) to the organic solvent led to an increase in the rate of accumulation of peroxide compounds. It has been shown that the presence of alkaline and acidic catalysts exerts no appreciable influence on the achievable steady-state concentration and the rate of accumulation of peroxide compounds during the oxidation of lignin.Bratsk Industrial Institute. All-Union Scientific Production Combine of the Pulp and Paper Industry, Leningrad. Translated from Khimiya Prirodnykh Soedinenii, Nos. 3,4, pp. 413–417, May–August, 1992. 相似文献
218.
V. N. Charushin G. M. Petrova G. G. Aleksandrov L. G. Egorova A. I. Chernishev E. O. Sidorov N. A. Klyuev O. N. Chupakhin 《Chemistry of Heterocyclic Compounds》1987,23(4):426-435
Dibenzo[d,k]-1,3,6,10-tetraazatetracyclo[7.3.1.02,7.06,13]trideca-4,11-dienes undergo addition reactions at the C(2) carbon atom with alcohols and thiols, accompanied by cleavage of the C-N bond of the imidazoline ring, to generate diquinoxalino[1,2-a2,3-d]pyrrole derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 513–522, April, 1987. 相似文献
219.
O. L. Shaffer V. L. Dimonie M. S. El-Aasser J. W. Vanderhoff 《Journal of polymer science. Part A, Polymer chemistry》1987,25(9):2595-2603
A series of poly(styrene)/poly(styrene-co-acrylonitrile) core-shell latexes were synthesized by seeded emulsion polymerization. The dried latex was dissolved in toluene and then cast on the surface of water to form a very thin film (60–90 nm). Phase separation in the thin film was studied by transmission electron microscopy (TEM). Electron micrographs of these thin films yielded fine structure and interesting morphology that was unattainable by ultramicrotoming of the corresponding compression-molded specimens. Glass transition temperatures and percent grafted polystyrene were correlated with the TEM results. As grafting increases, mixing of the two phases improves, with the resulting Tg value being between the two Tg's of poly(styrene) and poly(styrene-co-acrylonitrile). 相似文献
220.
The chemical shifts of the protons in the even positions of the pyrimidine ring in 2- and 4-substituted pyrimidines in dimethyl sulfoxide solutions were determined. The correlation equations that link the relative chemical shifts (with allowance for corrections for the magnetic anisotropy of the substituents and the ring) with the F and R substituent constants were calculated. The ratios obtained were analyzed by comparison with the corresponding correlation equations for monosubstituted benzenes. The reasons for the significant increase in the transmission of the conjugation effects of the substituents to the even positions of the pyrimidine ring as compared with the meta positions of the benzene ring and the appreciable weakening of the conductivity of their inductive effects when the heteroring nitrogen atom is situated between a resonating proton and the substituent are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 673–677, May, 1978. 相似文献