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991.
A series of N-substituted hydroxylamine derivatives was synthesized as a potential substitute for calcium hypochlorite. Like calcium hypochlorite, these compounds are highly P(V)-nucleophilic with respect to toxic phosphorus esters.Incorporating surface-active structural elements into the compounds can enhance their reactivity to phosphorus esters on the one hand (micelle catalysis); on the other hand aqueous solutions of these compounds wet polymer surfaces easily, thus ensuring that they can be well applied. The effectiveness of the compounds in the detoxification of phosphorus esters was examined using diisopropyl fluorophosphate (DFP) as a model substance. 相似文献
992.
Thomas Novinson Roland K. Robins Darrell E. O'Brien 《Journal of heterocyclic chemistry》1973,10(5):835-837
Nucleophilic displacement reactions under acidic and basic conditions have been studied with 4,6-dinitro-3-methoxypyridazine 1-oxide ( 1 ) and with 6-chloro-3-methoxy-4-nitropyridazine 1-oxide ( 2 ). Depending on the nature of the nucleophilic reagent and the conditions of the reaction we have found that the chloro group, the nitro group, as well as the methoxy group of 1 and 2 may be displaced by the nucleophile. This type of compound possesses significant in vitro antifungal activity. 相似文献
993.
Naeem B. Hanna Slobodan D. Dimitrijevich Steven B. Larson Roland K. Robins Ganapathi R. Revankar 《Journal of heterocyclic chemistry》1988,25(6):1857-1868
1-β-D-Ribofuranosyl- 21 , 1-(2-deoxy-β-D-erytftro-pento fur anosyl)- 27 and 1-β-D-arabinofuranosyl- 29 derivatives of 1,2,4-triazole-3-sulfonamide ( 19 ) have been prepared. Glycosylation of the silylated 19 with 1,2,3,5-tetra-0-acetyl-β-D-ribofuranose ( 5 ) in the presence of trimethylsilyl triflate gave the corresponding blocked nucleoside ( 20 ), which on ammonolysis afforded 1-β-D-ribofuranosyl-1,2,4-triazole-3-sulfonamide ( 21 ). Stereospecific glycosylation of the sodium salt of 19 with either 1-chloro-2-deoxy-3,5-di-O-p-toluoyl-α-D-erythro-pentofuranose ( 22 ) or 1-chloro-2,3,5-tri-0-benzyl-α-D-arabinofuranose ( 23 ) provided the corresponding protected nucleosides 26 and 28. Deprotection of 26 and 28 furnished 1-(2-deoxy-β-D-erythro-pentofuranosyl)-1,2,4-triazole-3-sulfonamide ( 27 ) and 1-β-D-arabinofuranosyl-1,2,4-triazole-3-sulfonamide ( 29 ), respectively. 2-0-D-Ribofuranosyl-1,2,4-triazole-3(4H)-thione ( 7 ) and 4-β-D-ribofuranosyl-1,2,4-triazole-3(2H)-thione ( 9 ) were also prepared utilizing either an acid catalyzed fusion of 1,2,4-triazole-3(1H,2H)-thione ( 4 ) with 5 , the reaction of 5 with silylated 4 in the presence of trimethylsilyl triflate, or by ring closure of 4-(2,3,5-tri-0-benzoyl-β-D-ribofuranosyl)thiosemicarbazide ( 10 ) with mixed anhydride and subsequent deacylation. The synthesis of 1-β-D-ribofuranosyl-3-benzylthio-1,2,4-triazole ( 15 ) has also been accomplished by the silylation procedure employing 3-benzylthio-1,2,4-triazole ( 13 ) and 5 to give 1-(2,3,5-tri-0-acetyl-β-D-ribofuranosyl)-3-benzylthio-1,2,4-triazole ( 14 ). Deacetylation of 14 furnished 15 . The structural assignments of 7, 14 and 21 were made by single-crystal X-ray diffraction analysis and their hydrogen bonding characteristics have been studied. The sulfonamido-1,2,4-triazole nucleosides are devoid of any significant antiviral or antitumor activity in cell culture. 相似文献
994.
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998.
Seeded beam expansions of high-temperature sodium vapour in helium, neon, argon, krypton and nitrogen carrier gases are examined. Photoionization coupled with mass spectroscopic detection is used to determine beam constituents. Contrary to non-seeded supersonic expansions, in which the abundance of sodium clusters observed decreases exponentially with increasing cluster size, large abundances of higher clusters (Nax, x ?65) are observed. Maxima centered at m/z = 161, m/z = 437 and m/z = 874 occur under certain conditions. 相似文献
999.
A new approach for the determination of elemental uranium in uranium bearing ore, using high resolution -ray spectrometry, was applied. Using a variant of the enrichment technique an agreement of better than 1% has been obtained between -ray measurement results and a certified value obtained by other analytical methods. For the calibration of the -ray spectrometer uranium reference samples have been used which are made available jointly in Europe and the USA as Certified Reference Materials for Gamma-Ray Spectrometry (EC NRM 171 and NBS SRM 969, respectively). The measured ore has been put in a special designed container which ensured in all directions seen from the radiation window an uniform degree of infinite thickness of about 95%. The results can be taken as an example for the applicability of -ray spectrometry when high accuracy is required and under conditions were homogeneously distributed elemental uranium is embedded in larger amount of matrix material. 相似文献
1000.
Brigitte Gutsche und Roland Herrmann 《Fresenius' Journal of Analytical Chemistry》1971,253(4):257-262
Zusammenfassung Der von früheren Untersuchungen her bekannte In-Brenner für den spezifischen Chlor(359,9 nm) und Brom-(327,7 nm)Nachweis wird in dieser Arbeit für den spezifischen Jod-Nachweis bei 409,9 nm benützt. Es wird gezeigt, daß man mit einem solchen Detektor in günstigen Fällen das Auflösungsvermögen eines GC verbessern kann. Nach vorangegangener Eichung sind Aussagen darüber möglich, wieviel Jod in den einzelnen GC-Fraktionen enthalten ist. Die Nachweisgrenzen des Verfahrens liegen zwischen 0,01–1,4 g Jod.
Unterstützt mit Mitteln der Deutschen Forschungsgemeinschaft. 相似文献
Iodine-specific detector for a gas chromatograph
The In-flame detector earlier applied to the specific chlorine (359.9 nm) and bromine (372.7 nm) analysis has now been employed for the iodine determination at 409.9 nm. It is shown that the resolution power of a GC column can be improved by such a specific detector. After calibration quantitative measurements of the iodine contents of the GC fractions are possible. The detection limits are 0.01–1.4 g of iodine.
Unterstützt mit Mitteln der Deutschen Forschungsgemeinschaft. 相似文献