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991.
The use of the complex acid HAlCl4 (HCl+AlCl3) permits the detemrination of the standard potential of the hydrogen electrode in nitromethane. The result (E0(Hs+/H2)=0.5 V vs. Fc/Fc+, Fc=ferrocene) shows that nitromethane is very weakly basic. This measurement is confirmed by showing that the standard potential of the hydrogen electrode in various solvents is linked to Gutmann's donor numbers of these solvents. The E0(Hs+/H2) value obtained in nitromethane belongs to the correlation line. 相似文献
992.
N. F. Pedchenko N. D. Trusevich V. F. Lavrushin 《Chemistry of Heterocyclic Compounds》1974,10(4):418-420
The shifts of the stretching vibrations of the hydroxyl groups of phenol and pentachlorophenol during the formation of intermolecular hydrogen bonds with 2-thienyl phenyl ketones containing substituents in the benzene ring were measured. A correlation dependence between theD
OH values and + substituent constants was established.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 482–485, April, 1974. 相似文献
993.
A method was developed for the preparation of 2-methyl-N-(2-thiazolyl)-, 2-methyl-N-(2-pyridyl)-, and 2-methyl-N-(2-benzothiazolyl)thiazolium salts. Cyanine dyes were synthesized from these salts. A comparison of the absorption spectra of dyes with various substituents (ethyl, phenyl, and 2-hetaryl) attached to the nitrogen atoms of the thiazole rings of the dyes demonstrated that the color deepens as the electronegativity of these substituents increases.See [1] for communication XIV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 933–936, July, 1972. 相似文献
994.
995.
B. D. Berezin 《Chemistry of Heterocyclic Compounds》1966,1(6):641-643
A qualitative analysis of certain peculiarities of the porphine molecule and its complexes compared with the phthalocyanine molecule is made by evaluating the -electron charges of bonds in these compounds by means of G. V. Bykov's semi -empirical linear equation. Acid-base, oxidation-reduction, and coordination properties of porphine are examined. It is shown that differences in chemical properties of porphines and tetraporphines can be explained by differences in -electron charges of bonds. 相似文献
996.
997.
Phosphorescence and excitation spectra have been measured of Fe3+-doped LiAl5O8, β-NaAlO2, Na-silicate glass and crystalline alumino-silicates. All excitation spectra fit quite well the Tanabe-Sugano diagram for a high spin d5 configuration. The expected tetrahedral site symmetry of Fe3+ in the host lattices and the value of the crystalline field parameter are strong evidence for phosphorescence of Fe3+ ions in tetrahedral oxygen coordination. 相似文献
998.
J. Reid Shelton D. E. Agostini J. B. Lando 《Journal of polymer science. Part A, Polymer chemistry》1971,9(10):2789-2799
Synthesis of the naturally occurring polyester, D -poly-β-hydroxybutyrate (PHB) was accomplished by using an optically active monomer. Polymerization of D -(+)-β-butyrolactone (β-BL) of 73% optical purity with a catalyst system of Et3Al–H2O produced a polymer with a similar optical activity and essentially identical to the natural polymer as isolated from bacterial cells. This paper describes the synthesis and characterization of this optically active polyester along with a suggested mechanism to account for the observed stereospecific polymerization of β-BL with this catalyst system. 相似文献
999.
E. N. Fedoseeva A. V. Budruev L. A. Smirnova Yu. D. Semchikov V. B. Fedoseev 《Polymer Science Series A》2007,49(8):868-875
It has been shown that the interaction of chitosan and oligochitosan with unsaturated acrylic esters via the nucleophilic addition mechanism and their condensation with heptadecyl isocyanate yield hydrophobic alkyl-containing derivatives of the above polymers. The method of modification of oligochitosan in reactions via end functional groups is developed. 相似文献
1000.
(13)C spin-lattice relaxation studies on bis(2-ethylhexyl) adipate (DOA) plasticized poly(vinylchloride) (PVC) membranes are reported for plasticization levels ranging from 25 to 100 wt% plasticizer. The interaction between DOA and PVC molecules in these membranes appears to involve an entrapment of the plasticizer molecule within the polymer matrix. This is based on the constancy of the characteristic segmental motions of the plasticizer chains throughout the concentration range studied. The segmental mobility of the plasticizer component is modified by water absorption in the membrane. The pattern of characteristic segmental motions of the plasticizer is altered, the effect depending on the amount of added salt in the membrane. The results show water has a weak influence on the microviscosity of the membrane matrix. 相似文献