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L. V. Klyba N. A. Nedolya N. I. Shlyakhtina E. R. Zhanchipova 《Russian Journal of Organic Chemistry》2005,41(10):1544-1550
Previously unknown 5-(1-ethoxyethoxy)-2-methoxy-6-methylsulfanyl-2,3-dihydropyridine, 3-(1-ethoxyethoxy)-2-methylsulfanylpyridine, and 2-methylsulfanylpyridin-3-ol were synthesized from α-lithiated 1-(1-ethoxyethoxy)allene, methoxymethyl isothiocyanate, and methyl iodide, and their fragmentation under electron impact was studied. At ionizing electron energies of 12 and 60 eV in the temperature range from 50 to 250°C, the molecular ions derived from 5-(1-ethoxyethoxy)-2-methoxy-6-methylsulfanyl-2,3-dihydropyridine and 3-(1-ethoxyethoxy)-2-methylsulfanylpyridine decompose along two main pathways: rupture of the C-O bond in the acetal moiety to give oxonium ions with m/z 73 (in the two cases) and 168 (pyridine derivative) and unexpectedly facile McLafferty rearrangement with elimination of ethoxyethene molecule to produce fragment ions with m/z 173 and 141, respectively. The latter pathway was not observed previously for dihydropyridines and acetals, and it predominates in the fragmentation of 3-(1-ethoxyethoxy)-2-methylsulfanylpyridine. Expulsion of methanol molecule from the molecular ion of 5-(1-ethoxyethoxy)-2-methoxy-6- methylsulfanyl-2,3-dihydropyridine occurred only above 170°C. 相似文献
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Nedolya N. A. Shlyakhtina N. I. Zinov'eva V. P. Dmitrieva L. L. Sarapulova G. I. 《Russian Journal of General Chemistry》2002,72(5):760-766
Polyfluoroalkyl vinyl ethers take up aliphatic and aromatic carboxylic acids in the presence of 0.2-5 wt% of trifluoroacetic acid at 55-105°C to give fluorine-containing hemiacetals in 60-100% yields. 相似文献
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A. V. Shlyakhtina D. A. Belov S. Yu. Stefanovich L. G. Shcherbakova 《Russian Journal of Electrochemistry》2011,47(5):620-627
In complex oxides of REE (Ln4M3O12 (Ln = Tm, Lu; M = Zr, Hf), Ln2TiO5 (Ln = Er-Yb)) and Ho2TiO5, the following phase transitions of the order-disorder type are studied for different cooling rates: rhombohedral δ-phase-defective
fluorite in Ln4M3O12 (Ln = Tm, Lu; M = Zr, Hf), pyrochlor-like phasedefective fluoride in Ln2TiO5 (Ln = Er-Yb), and hexagonal β-phase-pyrochlor in Ho2TiO5. The presence of nanostructuring phenomena typical of fluorite-like polymorphous modifications of complex oxides in the Ln2O3-MO2 (Ln = Ho-Lu; M = Ti, Zr, Hf) systems is confirmed. The conductivity of polymorphous modifications of Ln4Zr3O12 (Ln = Tm, Lu;) and Ln2TiO5 (Ln = Ho-Yb) with different thermal prehistory is studied. The comparative studies of the oxygen-ionic conductivity of fluorite-
and pyrochlor-like Ln2TiO5 (Ln = Ho-Yb), pyrochlor Ho2TiO5, and β-Ho2TiO5 and also of the conductivity of fluorite-like compounds and δ-Ln4Zr3O12 (Ln = Tm, Lu) are carried out. The oxygen-ionic conductivity of complex oxides in the Ln2O3-MO2 (Ln = Er-Lu; M = Ti, Zr, Hf) system is shown to decrease in the following series: defective pyrochlor-defective fluorite-rhombohedral
δ-phase ∼ hexagonal β-phase. 相似文献
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D.A. BelovA.V. Shlyakhtina S.Yu. StefanovichA.N. Shchegolikhin A.V. KnotkoO.K. Karyagina L.G. Shcherbakova 《Solid State Ionics》2011,192(1):188-194
Low-temperature ordering transitions in polycrystalline high temperature conductors (Dy1 − xCax)2Ti2O7 − δ (x = 0, 0.1) prepared using co-precipitation, mechanical activation and solid-state reactions at 1400 or 1600 °C have been studied by impedance spectroscopy at low frequencies and thermal mechanical analysis (TMA). The dielectric permittivity and loss tangent of the ceramics obtained have been measured as a function of temperature at low frequencies (0.5−500 Hz). The results provide evidence for the relaxation of point defects, most likely oxygen vacancies, at 500−600 °C and an antiferroelectric low-temperature phase transition of the second order, associated with re-arrangement process in the oxygen sublattice of pyrochlore structure. The temperature of the antiferroelectric transition is 700 to 800 °C, depending on the synthesis procedure and ceramic composition. Calcium doping of Dy2Ti2O7 leads to the formation of additional oxygen vacancies and, in the case of the samples prepared via co-precipitation, increases the peaks in permittivity due to the relaxation process and ordering transition by three or six times, respectively. 相似文献
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Matus E. V. Shlyakhtina A. S. Sukhova O. B. Ismagilov I. Z. Ushakov V. A. Yashnik S. A. Nikitin A. P. Bharali P. Kerzhentsev M. A. Ismagilov Z. R. 《Kinetics and Catalysis》2019,60(2):221-230
Kinetics and Catalysis - The effect of preparation procedures (a polymer ester precursor method and incipient wetness impregnation) on the physicochemical and functional properties of Ni/CeO2... 相似文献
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A. V. Shlyakhtina A. E. Sokolov V. A. Ul’yanov V. A. Trunov M. V. Boguslavski? A. V. Levchenko L. G. Shcherbakova 《Crystallography Reports》2009,54(1):25-30
The crystal structure of pyrochlore-like solid solutions (Yb1 − x
Ca
x
)2Ti2O7 (x = 0, 0.05, 0.10) synthesized by high-temperature annealing of mechanically activated initial oxides at temperatures of 1300–1500°C
is studied using neutron diffraction. It is found that the Ca2+ cations are located in the ytterbium sublattice, which apparently favors the splitting of one of the oxygen sublattices [O(2)
(48f)] of the pyrochlore structure: the decrease in the occupancy of this sublattice is accompanied by the formation of a new
sublattice O(3) (8b), whereas the other oxygen sublattice O(1) (8a) remains unchanged. This rearrangement of the anions in the oxygen subsystem due to the incorporation of an alkaline-earth
cation explains the high ionic conductance (∼0.2 S/cm at 1000°C) for (Yb0.9Ca0.1)2Ti2O7 ∼ 0.2, which is the maximum value observed to date for pyrochlores of the A
2
B
2O7 type, where A = Ln and B is a Subgroup IVA element of the periodic system. The bulk and grain-boundary components of the conductivity of (Yb0.95Ca0.05)2Ti2O7 synthesized at temperatures of 1300, 1400, and 1500°C are studied using impedance spectroscopy. It is found that the (Yb0.95Ca0.05)2Ti2O7 sample synthesized at 1500°C has the highest total conductivity due to the increased grain-boundary component. The bulk component
of the ionic conductivity of (Yb0.95Ca0.05)2Ti2O7 is hardly affected by the synthesis temperature and depends mainly on the degree of heterovalent substitution.
Original Russian Text ? A.V. Shlyakhtina, A.E. Sokolov, V.A. Ul’yanov, V.A. Trunov, M.V. Boguslavskiĭ, A.V. Levchenko, L.G.
Shcherbakova, 2009, published in Kristallografiya, 2009, Vol. 54, No. 1, pp. 31–36. 相似文献