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V. N. Yuskovets A. V. Moskvin L. E. Mikhailov B. A. Ivin 《Russian Journal of General Chemistry》2005,75(1):134-146
Readily available 5-acyl-4-hydroxy-3,6-dihydro-2H-1,3-thiazine-2,6-diones with primary alkyl- and arylamines in mild conditions (boiling in propan-2-ol) to give Schiff bases. In more rigid conditions (boiling in DMF), the reaction is accompanied by COS liberation and provides 1-substituted 6-alkyluracils. This previously unknown reaction possesses a considerable synthetic potential and can be considered as a new, general, and regioselective synthetic approach to 1-substituted 6-alkyluracils.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 1, 2005, pp. 146–158.Original Russian Text Copyright © 2005 by Yuskovets, Moskvin, Mikhailov, Ivin.For communication CXXI, see [1]. 相似文献
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The possibilities of the new chromatomembrane method in the removal of oxygen dissolved in water are studied. The scheme of the water deoxygenation process is determined. The new reagent-free method allows production of water with oxygen content at the level of a few ppb. 相似文献
5.
L. N. Moskvin V. N. Yepimakhov O. A. Amosova 《Journal of Radioanalytical and Nuclear Chemistry》1993,175(6):455-466
A rapid method has been developed for the determination of polonium in water. The samples with a volume of 0.25 to 4.0 1 were filtered at a flow rate of 2 to 3 1 h–1 on a membrane filter impregnated with silver. Optimum conditions are 0.1M hydrochloric acid in the presence of 0.01M ascorbic acid. After the filtration the membranes are flushed, dried and measured for -activity. The detection limit for a 41 sample with a membrane diameter of 35 mm is lower corresponding to 1.5×10–3 Bq.1–1. The method permits activity measurement with an -radiometer or -spectrometer with an error less than 30% at a confidence level of 0.95. 相似文献
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We report a new algorithm for constructing pathways between local minima that involve a large number of intervening transition states on the potential energy surface. A significant improvement in efficiency has been achieved by changing the strategy for choosing successive pairs of local minima that serve as endpoints for the next search. We employ Dijkstra's algorithm [E. W. Dijkstra, Numer. Math. 1, 269 (1959)] to identify the "shortest" path corresponding to missing connections within an evolving database of local minima and the transition states that connect them. The metric employed to determine the shortest missing connection is a function of the minimized Euclidean distance. We present applications to the formation of buckminsterfullerene and to the folding of various biomolecules: the B1 domain of protein G, tryptophan zippers, and the villin headpiece subdomain. The corresponding pathways contain up to 163 transition states and will be used in future discrete path sampling calculations. 相似文献
8.
The important mechanisms of supertransferred hyperfine (STHF) interactions in N–O–M chains are briefly discussed: (i) spin polarization ofns states in the N-ion due to the s-d exchange interaction,H
STHF
sd
; (ii) contributions of spin-polarized states of the intervening O-ion,H
STHF
II
; (iii) transfer of d-electrons of the M-ion to emptyns states in the N-ion,H
STHF
III
. The dependence ofH
STHF upon the N–O–M bond configuration, electronic structure, and orbital state of the M-ion is presented in a convenient form. The STHF interactions in the chains Sn4+–O2––Fe3+, Cr3+ in compounds with slightly distorted Perovskite structure are considered. The STHF field in the chain Sn4+–O2––Cr3+ is shown to change the sign within the range of angles near 170°. This conclusion is in line with published data on the isoelectronic chain Sn4+–O2–Mn4+ in the compounds Ca1–x
Sr
x
MnO3. The results obtained for the N–O–Fe3+ chain are rationalized by the predicted angular dependence ofH
STHF=+ cos + cos2. Features of the STHF interactions in N–O–M chains with an M-ion in an orbital degenerate state are examplified by a preliminary analysis of N–O2––V3+ chains in orthovanadites. 相似文献
9.
A. N. Ponomarev Yu. L. Moskvin S. D. Babenko 《Russian Journal of Electrochemistry》2007,43(3):273-278
The transport properties of separating membranes MF-4SK are studied during electrolysis of H2O in solutions of KOH. The effective diffusion coefficients of molecules of KOH and H2O and the transfer coefficients of ions K+ and OH? and molecules of H2O are measured at KOH concentrations reaching 11 M, currents reaching 0.31 A cm?2, at ambient temperature and at 80°C. In contact with a KOH solution in the concentration interval 0.1 to 11 M, the membranes that initially swelled in H2O lose a considerable fraction of water that was present in them and the overall volume of clusters and solution-filled channels in them noticeably decreases. The coefficients of transfer by current of ions K+ out of anodic compartment into cathodic and the OH? ions in the reverse direction, respectively, happen to be equal to about 0.6 and 0.4 at ambient temperature and 0.8 and 0.2 at 80°C. The coefficients of transfer of water molecules out of the anodic volume into the cathodic volume in the process of electrolysis happen to be in the limits 1.6–1.9 at ambient temperature and in the limits 2.2–2.8 at 80°C. The effective diffusion coefficients of molecules of KOH and H2O at moderate concentrations of KOH (5.6 M) amount to ~2.6 × 10?7 and 30 × 10?7 cm2s?1 at ambient temperature and ~4 × 10?7 and 61 × 10?7 cm2s?1 at 80°C, respectively. At a high concentration of KOH (~10 M) these quantities substantially diminish. 相似文献
10.
A review of the membrane methods of substance separation used in analytical chemistry is presented. Membrane methods based on gas-diffusion separation and dialysis extraction, membrane filtration, membrane extraction, and chromatomembrane separation are considered. The possibility of combining membrane methods with modern methods of substance determination, such as flow-injection analysis, gas and liquid chromatography, capillary electrophoresis, mass spectrometry, and so on is discussed. The list of references consists of 200 items. 相似文献