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1.
Simple catalytic systems for cross-coupling reactions of acyl chlorides with arylboronic acids under microwave conditions were tested. Microwave irradiation facilitated the reaction course. Mild reaction conditions afford the symmetrical and unsymmetrical aryl ketones in reasonable to high yields within a short time. A wide range of substrates bearing an electron-donating or an electron-withdrawing substituent on aryl ring of acid chloride as well as on boronic acid were examined and high yields of ketones were produced. 相似文献
2.
Jan Hlav
Miroslav Soural Pavel Hradil Iveta Fryov Jan Slouka 《Journal of heterocyclic chemistry》2004,41(4):633-636
The reactions of 5‐nitroisatine were studied with nucleophiles like heterocyclic amines and alkaline hydroxide. With the use of alkaline hydroxide it was converted into 2‐amino‐5‐nitrophenylglyoxylic acid 2 , with piperidine, morpholine and carbethoxypiperazine to its amides 4a‐4c or by oxidation to 5‐nitroanthranilic acid 7. This acid was used for synthesis of 3‐hydroxy‐6‐nitro‐2‐phenyl‐1H‐quinolin‐4‐one 10. Semicarbazone of 5‐nitroisatine 11 was converted to 5‐(2‐amino‐5‐nitrophenyl)‐2,3,4,5‐tetrahydro‐1,2,4‐triazine‐3,5‐dione 12. Cyclocondensation of this compound to afford 8‐nitro‐2,3‐dihydro‐5H‐[1,2,4]triazino‐[5,6‐b]indol‐3‐one 13 was unsuccessful. 相似文献
3.
In isotachophoresis (ITP), the sample constituents migrate, depending on their concentrations in the loaded sample, either in fully developed zones or in the boundary layers between the zones of constituents of the corresponding effective mobilities. The latter (spike) migration mode is analytically beneficial in selective detections of trace analytes, especially, when appropriately chosen discrete spacers minimize detection interferences due to matrix constituents. To facilitate a search for suitable mixtures of discrete spacers, a two-step calculation procedure was developed in this work. Using a pool of discrete spacers consisting of 42 anionic and zwitterionic constituents, this procedure was shown effective in the anionic ITP separations performed at pH = 6.5-10.0. Besides the predictions of the migration orders, it was helpful in identifying the spacing constituents that could cause resolution problems due to an uncertainty with which pH of the leading electrolyte solution is known. The ionic mobility and pKa data, taken for the spacing constituents from the literature and the ones obtained from the ITP experiments carried out in this work, were used in the calculations performed in a context with the choice of spacers. Although the data obtained from the ITP experiments provided better results, small uncertainties with which they were acquired (attributable to fluctuations in the experimental conditions) set practical limits in the calculation based choice of multi-component mixtures of the spacing constituents. 相似文献
4.
Jakub Stýskala Jan Slouka Iveta Wiedermannov Petr Bedn 《Journal of heterocyclic chemistry》2003,40(5):805-811
A series of 6‐azacytosines 4a‐4k and 5a‐5c were prepared by nucleophilic cleavage of furan ring of [1]benzofuro[2,3‐e][1,2,4]triazine derivative 1 . Some of them were used for the preparation of derivatives of [1,2,4]triazolo[4,3‐d][1,2,4]triazine ( 6a‐6d ) and tetrazolo[1,5‐d][1,2,4]triazine (7). The reaction of 1 with hydrogen sulfide afforded the corresponding 6‐(2‐hydroxyphenyl)‐2‐phenyl‐5‐thioxo‐4,5‐dihydro‐1,2,4‐tri‐azin‐3(2H)‐one ( 8 ), while with hydrogen selenide 6‐(2‐hydroxyphenyl)‐2‐phenyl‐4,5‐dihydro‐1,2,4‐triazin‐3(2H)‐one ( 9 ) was formed. The prepared compounds were tested for biological activity. 相似文献
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Leite Irena Andrianov Victor Zelencova-Gopejenko Diana Loza Einars Kazhoka-Lapsa Iveta Domracheva Ilona Stojak Marta Chlopicki Stefan Kalvins Ivars 《Chemistry of Heterocyclic Compounds》2021,57(12):1235-1235
Chemistry of Heterocyclic Compounds - 相似文献
9.
ubomír Smr
ok Radovan erný Miroslav Bo
a Iveta Mackov Blanka Kubíkov 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(2):i16-i18
The crystal structure of tripotassium octafluoridotantalate, K3TaF8, determined from laboratory powder diffraction data by the simulated annealing method and refined by total energy minimization in the solid state, is built from discrete potassium cations, fluoride anions and monocapped trigonal–prismatic [TaF7]2− ions. All six atoms in the asymmetric unit are in special positions of the P63mc space group: the Ta and one F atom in the 2b (3m) sites, the K and two F atoms in the 6c (m) sites, and one F atom in the 2a (3m) site. The structure consists of face‐sharing K6 octahedra with a fluoride anion at the center of each octahedron, forming chains of composition [FK3]2+ running along [001] with isolated [TaF7]2− trigonal prisms in between. The structure of the title compound is different from the reported structure of Na3TaF8 and represents a new structure type. 相似文献
10.
Iveta Smetanová Karol Holý Monika Müllerová Anna Polášková 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(1):101-109
Seasonal and short term variations of 222Rn activity concentration in borehole air and water of the borehole drilled in cracked quartzite were studied and possible
response on meteorological parameters was examined. Seasonal change of radon concentration in borehole air due to atmospheric
temperature was confirmed. Short term variation of radon concentration in borehole air coincided with the atmospheric pressure
changes. The strong impact of rainfall on radon concentration values was observed both in air and water environments. The
decrease of radon content in borehole air and water followed radioactive decay law exclusively in spring and summer month.
Contrary to borehole water, rainfall increased radon concentration in borehole air during spring and summer months only. In
this paper the results from two and half years of investigation are presented. 相似文献