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排序方式: 共有235条查询结果,搜索用时 15 毫秒
1.
Susana Conde Ceide 《Tetrahedron letters》2006,47(26):4415-4418
We herein report that flash heating microwave irradiation is a helpful tool in the formation of arylpyrimidines from the corresponding halopyrimidines. The palladium-catalyzed cross-coupling reactions of 2,4-di- and 2,4,5-trihalopyrimidines with phenylboronic acid under the above conditions are described. By use of the appropriate catalyst and the adequate halopyrimidine, good regioselectivity can be achieved in the 2-, 4-, or 5-positions of the heterocycle. In addition, we show that this methodology is ameneable for the stepwise preparation of mono-, di-, and triphenylpyrimidines. 相似文献
2.
Summary A new technique is described for the identification of the chloride ion through the formation of chromyl chloride, based on the extraction of the latter with carbon tetrachloride. The identification limit is 2g of chloride. It is possible to carry out the test in the presence of many other anions, including fluoride, which cannot be present when the traditional distillation technique is employed.
Zusammenfassung Vorgeschlagen wird eine neue Technik zum Chloridnachweis durch Bildung von Chromylchlorid. Dieser Nachweis beruht auf der Extraktion des Chromylchlorids mit Tetrachlorkohlenstoff. Die Nachweisgrenze liegt bei 2g Chlorid, wobei die Möglichkeit besteht, den Test auch in Gegenwart von Fluorid durchzuführen, das bei Anwendung der üblichen Destillationsmethoden nicht anwesend sein darf.相似文献
3.
Santiago Conde Carlos Corral Jaime Lissavetzky 《Journal of heterocyclic chemistry》1980,17(5):937-940
The synthesis by two alternative routes of 1-(3-benzo[b]thienyloxy)-3-isopropylamino-2-propanol hydrochloride ( 1a HCl), a thiophenic isoster of Propranolol, and related compounds, is reported. The protecting and enolizing properties of the 2-methoxycarbonyl group on benzo[b]thiophene-3-one, along with its facile removal, are utilized in the first route. In the second one, conversion of 3-bromobenzo[b]thiophene in 1-(3-benzo[b]thienyloxy)-2,3-o-isopropylidenepropane is the key step. On the other hand, hydrolysis of 1-(3-benzo[b]furanyloxy)-2,3-o-isopropylidenepropane to the corresponding diol, in order to obtain a furanic isoster of Propranolol (17a ), was unsuccessful. 相似文献
4.
J. Borrs R. Carballo A. Castieiras M. C. Gmez‐Conde M. C. Fernndez‐Vidal J. Nicls 《无机化学与普通化学杂志》2005,631(11):2221-2226
Four new dinuclear copper(II) complexes have been synthesized and have the general formula [Cu2(L)(H2O)2], where L = GLYDTO [N,N′‐bis(carboxymethyl)dithiooxamide], ALADTO [N,N′‐bis(carboxyethyl)dithiooxamide], VALDTO [N,N′‐bis(1‐carboxy‐2‐methylpropyl)dithiooxamide] and LEUDTO [N,N′‐bis(1‐carboxy‐3‐methylbutyl)dithiooxamide]. The complexes were characterized by elemental analysis as well as by IR, electronic and EPR spectroscopy. These techniques provided evidence for the presence of the CuNO2S chromophore. Magnetic susceptibility measurements on all the complexes in the range 4–300 K show the existence of a dominant antiferromagnetic interaction with ?J values greater than 300 cm?1. Thermal decomposition behaviour of the complexes was studied by thermogravimetry. 相似文献
5.
R. D. Sinisterra R. Najjar O. L. Alves P. S. Santos C. A. Alves De Carvalho A. L. Conde Da Silva 《Journal of inclusion phenomena and macrocyclic chemistry》1995,22(2):91-98
The preparation and characterization of the 1:1 inclusion compound of rhodium(II) -methyl cinnamate in -cyclodextrin is reported. Evidence of inclusion was obtained from X-ray powder diffraction results, Raman, IR and UV-Vis spectroscopic studies and thermal analysis. Given the potential antitumor activity of the rhodium(II) carboxylate and its virtual insolubility in water, its inclusion in -cyclodextrin opens the possibility for its transference to the aqueous phase. 相似文献
6.
Santiago Conde Carlos Corral Jaime Lissavetzky 《Journal of heterocyclic chemistry》1985,22(2):301-304
A study on the oximation of a number of 2-acetylthiophenes in order to ascertain the validity of contradictory results previously described is reported. The fact that the steric hindrance is smaller in 2-acetylthiophenes unsubstituted at position-3 than in acetylbenzenes allows in these cases the formation of Z oximes, which even can predominate on the E oximes in the case of a + M substitution at position-5. In the paper is also shown that the E/Z ratio of 2-acetylthiophene oximes can be deduced from the 1H-nmr spectrum of the crude oxime mixture. 相似文献
7.
J. Hernandez Mendez A. Sanchez Perez F. Lucena Conde 《Journal of Electroanalytical Chemistry》1975,66(1):53-65
The anodic oxidation of a dropping copper amalgam electrode in presence of dilute solutions of glycine in 0.50 M NaClO4 has been studied. An anodic wave at ?0.28V (SCE) is observed, yielded by diffusion of glycinate anion in the solution towards the electrode surface. The wave-heights increase with the glycinate concentration (function of glycine concentration and pH value) until the anodic oxidation is controlled by the metal diffusion into mercury. The effect of pH is interpreted by attributing it to the depolarizer effects at glycinate anion even though the zwitterion is present in much larger concentrations. The applicability of anodic oxidation of a dropping copper amalgam electrode in the determination of glycine in the range of concentrations 10?4–10?2M with a rigorous control of pH (8.0<pH<10.5) is shown. The standard deviation of the proposed method is 4.1% and the minimum concentration determinable is in the 1×10?4M range. 相似文献
8.
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10.
Gallardo J. Duran A. Garcia I. Celis J.P. Arenas M.A. Conde A. 《Journal of Sol-Gel Science and Technology》2003,27(2):175-183
Sol-gel hybrid organic-inorganic and inorganic SiO2-based protective coatings with and without added 3 m glass particles were developed and tested for their corrosion and wear behavior of an stainless steel substrate (AISI316L). The corrosion resistance greatly increases by incorporating glass particles in the sols. The incorporation of particles in the coatings allows the synthesis of thicker crack-free coatings. On the other hand, the corrosion resistance increases for coatings with a higher organic content obtained at lower sintering temperature. These coatings are also highly stable in saline aqueous solutions. However, the wear resistance is badly affected by the hybrid character of the SiO2 matrix. The optimum coating process in terms of corrosion and wear resistance, appears to be a hybrid system with a dense SiO2 network achieved at intermediate sintering temperatures. 相似文献