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241.
Inductively coupled Argon Plasma Spectrometry is used for the indirect determination of sulphate in iron(III) chloride leach solution of Elliot Lake uranium ores via addition of a known amount of barium ions and analyzing for excess of barium. The ore contains approximately 7 wt% pyrite, FeS(2) as the major mineral which oxidizes to generate sulphate during leaching with fe(III). The effects of pH, the concentrations of Fe(III) and chloride ions and for presence of ethanol in the test samples on the accuracy of analysis are studied. It is found that unlike the Rhodizonate method, removal of iron(III) from or addition of ethanol to the test sample prior to analysis are not required. Linear calibration curves are obtained. 相似文献
242.
Z. Popova C. Dimitrov K. Aristirova R. P. Dimitrova L. Dukova G. Wendt 《Reaction Kinetics and Catalysis Letters》1988,36(1):85-90
Two series of nickel mordenite catalysts have been prepared on the basis of Na-mordenite and H-mordenite. Their catalytic activity in cyclohexane conversion has been studied. It has been found that the properties of the catalysts are strongly dependent on the acidity of mordenite.
NaM HM. .相似文献
243.
L. A. Srybnaya Z. Tulyabaev A. A. Sadykov D. N. Dalimov 《Chemistry of Natural Compounds》1990,26(3):347-348
A. S. Sadykov Institute of Bioorganic Chemistry, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 413–415,
May–June, 1990. 相似文献
244.
The modification of a Ni-Cr oxide catalyst during reduction was studied by IR spectroscopy of adsorbed CO and NH3 probe molecules. It was determined that in the starting oxidized sample the nickel cations were in the form of oxide clusters distributed over the surface of chromium oxide. As a result of reduction, they were depleted in oxygen, and metal clusters were formed and enlarged. Effective oxidation, by water vapor, of part of the surface of the metallic-nickel clusters that formed during reduction was observed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2718–2725, December, 1991. 相似文献
245.
X-ray diffraction and spectral studies of 1-phenyl-3-methyl-4-(2′,4′-Dimethylphenylazo)-pyrazolone-5
L. G. Kuz'mina L. P. Grigor'eva Yu. T. Struchkov Z. I. Ezhkova B. E. Zaitsev V. A. Zaitseva P. P. Pron'kin 《Chemistry of Heterocyclic Compounds》1985,21(6):680-684
The molecular and crystal structures of 1-phenyl-3-methyl-4-(2,4-dimethyl-phenylazo) pyrazolone-5 were determined. In the crystal the molecule exists as the hydrazone tautomer. The pyrazole ring is planar, and the substituents are practically coplanar with it. The molecule contains an intramolecular NH...O hydrogen bond that closes a practically planar six-membered ring (N...O, 2.77 (I), H...O 2.14 Å, angle at H(N(4)) hydrogen 131 °). The x-ray diffraction data agree with the spectral data and with the CNO calculation.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 816–821, June, 1985. 相似文献
246.
A. A. Krauze É. É. Liepin'sh Z. A. Kalme Yu. É. Pelcher G. Ya. Dubur 《Chemistry of Heterocyclic Compounds》1984,20(11):1241-1245
The condensation of benzylideneacetonacetic ester with cyanoacetamide in the presence of triethylamine yielded 3-carbamoyl-3,4-dihydropyridin-2-one, while the condensation of arylidenecyanoacetamides with -aminocrotonic ester in acetic acid yielded 3-cyano-3,4-dihydropyridin-2-ones. It was established by NMR spectroscopy that 3-cyano-4-R-5-ethoxycarbonyl-6-methyl-3,4-dihydropyridin-2-ones exist in solutions in the form of a mixture of cis- and trans-stereoisomers in a 101 ratio.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1504–1508, November, 1984. 相似文献
247.
Intraionic C3 reorientation of the anilinium NH+3 group was evidenced by measurements of the temperature dependence of the proton spin—lattice relaxation time, by rotating frame experiments and cw NMR data. Analysis of the results yielded a rotor hindering potential E = 33.6 kJ/mole and τo = 4 × 10−13 s. 相似文献
248.
General analytic formulas for derivatives of real Slater orbitals with respect to the Cartesian coordinates x and y have been derived. The application of this result to molecular geometry optimization or to the construction of a force constant matrix is briefly discussed. 相似文献
249.
T. A. Vaganova S. Z. Kusov V. I. Rodionov I. K. Shundrina E. V. Malykhin 《Russian Chemical Bulletin》2007,56(11):2239-2246
Amination of pentafluoropyridine, 2,3,5,6-tetrafluoropyridine, 4-chlorotetrafluoropyridine, 3,5-dichlorotrifluoropyridine,
octafluorotoluene, α,α,α,2,3,5,6-heptafluorotoluene, decafluoro-m-xylene, decafluorobiphenyl, hexafluorobenzene, and pentafluorobenzene with liquid ammonia was investigated. Bis-aminodefluorination
temperatures for the majority of substrates were shown to exceed significantly the corresponding temperatures of monoaminodefluorination.
The optimal conditions for selective preparation of mono-and diaminopolyfluoro(het)arenes were elucidated. An efficient method
for isolation of particular polyfluorophenylenediamines from product mixtures formed in nonselective reactions of pentafluorobenzene
and hexafluorobenzene with aqueous ammonia based on complexation with a crown ether is proposed.
Dedicated to the memory of Academician N. N. Vorozhtsov on the occasion of his 100th anniversary.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2163–2170, November, 2007. 相似文献
250.
L. J. Ning Y. P. Wu L. Z. Wang S. B. Fang R. Holze 《Journal of Solid State Electrochemistry》2005,9(7):520-523
Three kinds of silicon-containing disordered carbons have been prepared by pyrolysis of polysiloxanes with different amounts of phenyl side groups. X-ray powder diffraction, X-ray photoelectron spectroscopy and electrochemical capacity measurements were performed to study their behaviors. Graphite crystallites, micropores, and silicon species affect their electrochemical performances. All of them present high reversible capacities, >372 mAh/g. Since the graphite crystallites are very small, they contribute very little to reversible capacity. The number of micropores produced by gas emission during the heat-treatment process decides whether they exhibit reversible capacity. Si mainly exists in the form C–Si–O and influences the irreversible capacity. There is no evident capacity fading in the first ten cycles, indicating promising properties for these disordered carbons. 相似文献