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I. A. Ronova L. V. Dubrovina A. Yu. Kovalevskii C. Hamciuc M. Bruma 《Russian Chemical Bulletin》1998,47(7):1248-1256
Hindered rotation was considered in calculations of the conformational parameters of a series of polyheteroarylenes with bulky
side substituents by the Monte-Carlo method. Within the range of experimental errors, the results of calculations for several
polyarylates coincide with the values of conformational rigidity, determined from hydrodynamic experimental data. The proposed
procedure was used to estimate the rigidities of a number of polymers with bulky side substuents for which experimental determination
is difficult.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1287–1296, July, 1998. 相似文献
954.
L. A. Oliferova M. A. Statkus G. I. Tsisin J. Wang Yu. A. Zolotov 《Journal of Analytical Chemistry》2006,61(5):416-441
Methods of analysis combining the on-line sorption preconcentration of analytes with their subsequent separation and determination by high-performance liquid chromatography are considered. Approaches to the selection of sorbents, the sizes of preconcentration columns, and the sorption and desorption conditions are discussed along with the corresponding instrumentation. Many examples of the determination of organic compounds of different polarity and organic and inorganic ions are presented. 相似文献
955.
V. N. Voshula Yu. B. Vysotskii V. I. Seraya N. T. Novikova R. Ya. Mushii V. I. Dulenko 《Chemistry of Heterocyclic Compounds》1990,26(12):1349-1357
The interaction of 1-methallylpyrazoles with acetic or propionic anhydride in the presence of perchloric acid forms products of acylation at the double bond and subsequent heterocyclization — pyrazolo[1,2-a]pyridazinium salts — that are representatives of a new heteroaromatic system. Analogous cyclization is observed in the acylation of 3-(2-hydroxy-2-methylpropyl-pyrazole.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1623–1631, December, 1990. 相似文献
956.
N. I. Mikerova L. M. Alekseeva E. K. Panisheva Yu. N. Sheinker V. G. Granik 《Chemistry of Heterocyclic Compounds》1990,26(3):274-278
The reaction of 2-chloro-5-methylbenzoquinone with -aminocrotonic ester derivatives was studied by PMR spectroscopy in CD3COOD. The spectra indicate the formation of intermediate hydroquinone and quinone derivatives, which subsequently transform into the corresponding indoles. It was shown that the indolization proceeds unequivocally at the 3-position of the initial benzoquinone, and the rate of formation of the indole derivatives decreases with increase in the size of the substituent at the nitrogen atom of the -aminocrotonic ester. The starting, intermediate compounds and the end products observed in the PMR spectra were identified by comparison with specially synthesized compounds.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 324–328, March, 1990. 相似文献
957.
A. S. Balueva Yu. Ya. Efremov V. M. Nekhoroshkov O. A. Erastov 《Russian Chemical Bulletin》1989,38(12):2557-2560
1-Butyl-1-dibutylboryl-2-diphenylphosphino-2-phenylethene, which exists in the form 1,1,2-tributyl-3,4,4-triphenyT-1-borata-4-phosphoniacyclobut-2-ene, reacts with sulfur, selenium, methyl iodide, and pyridine under mild conditions with ring cleavage. In (2-butyl-2-dibutylboryl-1-phenylethenyl) diphenylphosphine sulfide and selenide, there is a coordinate bond between the thio-or selenophosphoryl group and the boron atom.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2793–2796, December, 1989. 相似文献
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