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991.
D. T. Clark B. J. Cromarty A. Dilks 《Journal of polymer science. Part A, Polymer chemistry》1978,16(12):3173-3184
Nonempirical LCAO MO SCF computations (in the ΔSCF formalism) have been carried out of binding energies and relaxation energies for an extensive series of oxygen-containing organic systems encompassing most of the common functionalities. The molecules for which experimental data are available for comparison demonstrate the adequacy of the treatment for describing the relative binding energies for both the Cls and Ols core levels. A sound basis is therefore provided for the discussion of relative core binding energies (Cls and Ols) for functionalities for which experimental data are not available, that is, hydroperoxides, peroxides, peroxyacids, and peroxyesters, a knowledge of which is essential for investigations of the surface oxidation of polymers by means of ESCA. Cls shifts are discussed in terms of primary and secondary substituent effects of oxygen, which greatly simplify the analysis of complex unresolved spectra, whereas for the Ols levels a similar but less straightforward situation exists. The relaxation energies associated with both Cls and Ols core ionization follow a dependence on the binding energy for a given structural type. 相似文献
992.
993.
Summary Copper phthalocyanine tetrasulphonic acid has been found to work satisfactorily as an inside indicator in the cerimetric titration of hydro-quinone and metol. It has the advantage that the indicator correction in titrations with 0.01 N solutions of ceric sulphate is much less than with the ferroin indicator, amounting to only 0.02 ml for two drops of the indicator solution.Part II: See Z. analyt. Chem. 163, 1 (1958). 相似文献
994.
New combining rules are proposed for the well depth, ?, and interaction distance, σ, describing nonbonded interatomic forces for rare gas pair interactions. Concepts underlying current combining rules applied in simulations of macromolecular and polymer systems are shown to be incompatible with experimental data on the rare gases. The current combining rules are compared with the new results using the experimental data. Mathematical properties of combining rules are considered, and it is shown how to reduce combining rule formulas from a two-parameter to a single-parameter problem. It is also shown how to graphically analyze combining rules against experimental data. We demonstrate using this analysis technique that the rare gas potentials do not obey a single combining rule for the ? parameter but do follow a single combining rule for the σ parameter. Finally, we demonstrate that a combining rule using both ? and ω can be used to predict the ? parameters for the mixed rare gas pairs. © John Wiley & Sons, Inc. 相似文献
995.
S. M. Adekenov K. A. Aituganov K. M. Turdybekov S. V. Lindeman Yu. T. Struchkov 《Chemistry of Natural Compounds》1991,27(5):575-579
The new germacranolide argolide has been isolated from the epigeal part ofArtemisia glabella, and its structure has been shown by its conversion into oxopelenolide B. From the results of an x-ray investigation it is
suggested that argolide has the spatial structure of 3-oxo-4α,7α,6β(H)-germacra-1(10),11(13)-dien-6,12-olide.
Institute of Organic Synthesis and Coal Chemistry, Kazakh Academy of Sciences, Karaganda. A. N. Nesmeyanov Institute of Organometallic
Chemistry, Russian Academy of Sciences, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 653–657, September–October,
1991. 相似文献
996.
K. M. Turdybekov T. T. Edil'baeva V. A. Raldugin M. M. Shakirov A. T. Kulyyasov S. M. Adekenov 《Chemistry of Natural Compounds》1998,34(2):141-144
A new sesquiterpene lactone having the structure 3-acetoxy-1-hydroxy-6, 7(H)-germacra-4,10(14), 11(13)-trien-6, 12-olide has been isolated fromArtemisia subchrysolepis Filat. and has been called subchrysin. Its stereochemistry has been established by x-ray structural analysis.Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 176–180, March–April, 1998. 相似文献
997.
998.
999.
1000.
Denifl S Ptasińska S Sonnweber B Scheier P Liu D Hagelberg F Mack J Scott LT Märk TD 《The Journal of chemical physics》2005,123(10):104308
Electron attachment to the polyaromatic hydrocarbons coronene and corannulene is studied in the electron energy range of about 0-14 eV using a high-resolution crossed electron-neutral beam setup. The major anions observed are the parent anions peaking at about 0 eV with cross sections of 3.8 x 10(-20) and 1 x 10(-19) m(2), respectively. The only fragment anions formed in coronene and corannulene are the dehydrogenated coronene and corannulene anions. Other anions observed in the negative mass spectra at about 0 eV can be ascribed to impurities of the sample. High-level quantum-mechanical studies are carried out for the determination of electron affinities, hydrogen binding energies, and structures of both molecules. The behavior of coronene and corannulene upon electron attachment is compared with that of other polyaromatic hydrocarbons studied previously. 相似文献