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791.
A. V. Fokin Yu. A. Borisov A. F. Kolomiets N. I. Raevskii V. G. Enchev E. B. Bogachuk 《Russian Chemical Bulletin》1992,41(2):266-271
The heats of formation of polychloroarynes (PCA's) from polychlorobenzenes (PCB's) have been calculated by the AMI method as a function of the composition and structure of the PCB's according to a two-step scheme including deprotonation with the formation of carbanions (PCCA's, H1) and dechlorination to PCA's (H2). The influence of the solvent on H1 and H2 has been evaluated in the framework of the solvaton model. It has been shown that the value of H1 decreases as the number of C1 atoms in the PCB is increased, while H2 increases along the same series due to the increase in the relative stability of the PCCA as the number of C1 atoms is increased. Although the dimerization of PCA's with the formation of polychlorobiphenylenes (PCBP's) is forbidden by orbital symmetry rules, calculations of fragments of the potential-energy surface have shown that this reaction takes place with an energy barrier amounting to about 1 kcal/mole.A. N. Nesmeyanov Institute of Organometallic Compounds, Russian Academy of Sciences, 117813 Moscow. Institute of Organic Chemistry, Bulgarian Academy of Sciences, 1113 Sofia. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 2, pp. 350–355, February, 1992. 相似文献
792.
Yu. K. Tovbin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2006,80(6):995-1001
Expressions for calculating the thermal velocities of the motion of rodlike molecules in slitlike pores were obtained within the framework of a lattice gas model valid over a wide range of fluid densities (from rarefied gases to liquids) and temperatures, including the critical region. The translational and rotational motion of molecules was described using the transition-state theory for nonideal reaction systems, which takes into account the effect of the neighboring molecules on the activation barrier height. The local distributions of the components of the mixture under equilibrium conditions were calculated by describing lateral interactions in the approximation of isolated contacts. The equations of the model reflect the fact that the distributions of the components in the direction perpendicular to the pore walls (due to the effect of adsorption forces) and along the pore axis (if capillary condensation occurs) exhibit a strong anisotropy. 相似文献
793.
Sheinin V. B. Ivanova Yu. B. Berezin B. D. 《Russian Journal of General Chemistry》2002,72(7):1128-1131
The association equilibrium of porphyrinium ions of mesoporphyrin IX dimethyl ester (H2MP) with iodide ions in acetonitrile was studied by spectropotentiometric titration. Two associates were revealed: (H4MP2
+)(I-) and (H4MP2
+)(I-)2; the electronic absorption spectra of these species were measured, and their formation constants were determined. 相似文献
794.
1. | Two types of intermediate complexes are formed in the reaction of benzoyl peroxide with thioketals: because of the reaction of S and O atoms and, in the second case, with the additional reaction of hydrogen atoms of the -CH2 group of the alkyl group of the thioketal with the oxygen of the peroxide. |
2. | The structure of the substituents at the geminal carbon atom does not affect the complexation process. |
795.
V. P. Markhaeva M. V. Rudomino Yu. M. Polikarpov T. Ya. Medved' N. M. Dyatlova M. I. Kabachnik 《Russian Chemical Bulletin》1976,25(5):998-1002
1. | A new organophosphorus complexing agent, N,N-di-(2-hydroxyethyl)ethylenediaminodimethylphosphonic acid was synthesized, which contains additional functional hydroxyl groups in the alkyl radicals on the nitrogen atoms. |
2. | The acid and complex-forming properties for this complexing agent were studied. The composition was studied for the complexes using the methods of spectrophotometry, and high-frequency titration. |
796.
The effect of the nature of the extracted complex and of the organic solvent on the sensitivity of the extraction/atomic absorption determination of tin in a graphite-furnace atomizer is investigated. It is recommended that extracts of tin as its chloride complex, or chelates with N-benzoyl-N-phenylhydroxylamine or 8-quinolinol, in organic solvents which do not contain chlorine should be used. The depressive effect of the organic matrix can be significantly decreased by using ascorbic acid as matrix modifier, by atomization from a graphite platform, and by using an atomizer coated with tungsten carbide. The procedure developed is applied to the determination of tin in rocks. For tin concentrations of 0.1–10 μg g?1, the relative standard deviation does not exceed 10%. 相似文献
797.
798.
Yu. M. Chunaev I. Yu. Grishin N. M. Przhiyalgovskaya 《Chemistry of Heterocyclic Compounds》1992,28(6):618-625
The syntheses and photochemical properties of fulgides derived from indole and indoline are reviewed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 744–753, June, 1992. 相似文献
799.
V. E. Shklover Yu. T. Struchkov T. V. Medvedeva Yu. V. Korshak A. M. Shapiro 《Russian Chemical Bulletin》1990,39(3):508-510
An x-ray structural study has shown that 6-(3-oxo-5,5-dimethyl-1-pyrrolin-3-yl)methylidene-2,2,7, 7-tetramethyl-4-hydroxybicyclo[2.2.2]azaoctane is formed as a low-molecular-weight byproduct of the solid-phase polymerization of 1,4-bis(2,2,6,6-tetramethyl-4-hydroxy-4-piperidyl)butadiyne.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 585–587, March, 1990. 相似文献
800.
Yu. A. Davidovich V. I. Butaeva O. M. Galkin T. N. Sentsova S. V. Rogozhin 《Russian Chemical Bulletin》1977,26(7):1554-1556
Conclusions A convenient method was proposed for obtaining the esters of N-carbonyl--amino acids, which is based on the reaction of the esters of N-trimethylsilyl--amino acids with phosgene in the presence of a tertiary amine.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1682–1684, July, 1977. 相似文献