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101.
102.
Boris A. Trofimov Lyubov'' N. Sobenina Zinaida V. Stepanova Tamara I. Vakul''skaya Ol''ga N. Kazheva Grigorii G. Aleksandrov Oleg A. Dyachenko Al''bina I. Mikhaleva 《Tetrahedron》2008,64(23):5541-5544
The solvent-free interaction of 2-phenylpyrrole with bromobenzoylacetylene (room temperature) upon their grinding with solid metal oxides (MgO, CaO, ZnO, BaO, Al2O3, TiO2, ZrO2) and salts (CaCO3, ZrSiO4) leads to either the cross-coupling product or the adduct of pyrrole addition to the riple bond of acetylene. The ethynylation is accompanied by the formation of intermediate and side products: E-2-(1-bromo-2-benzoylethenyl)-5-phenylpyrrole and 1,1-di(5-phenylpyrrol-2-yl)-2-benzoylethene. The activity of the metal oxides in the ethynylation reaction falls in the order (in the brackets, the content of 2-benzoylethynyl-5-phenylpyrrole in the reaction mixture is given): ZnO (81%), BaO (73%), Al2O3 (71%), MgO (69%), CaO (50%). The oxides, SiO2, TiO2, ZrO2, and the salts, CaCO3 and ZrSiO4, are inactive in the ethynylation reaction affording only the intermediate adduct, with ZrO2 the isolated yield of the bromoethenylpyrrole reaching 60%. ESR monitoring shows the reaction to start from one electron transfer from pyrrole to acetylene mediated by the oxide surface. The adduct is readily converted on Al2O3 to 2-(benzoylethynyl)-5-phenylpyrrole crystallized mostly as cis-rotamer (X-ray data). 相似文献
103.
F. Macá?ek P. Ková? P. Rajec R. Lepej 《Journal of Radioanalytical and Nuclear Chemistry》2009,280(2):389-400
Except the nuclear fuel reprocessing and nuclear materials safeguards, at present there are two areas of an increased responsibility
of nuclear scientists for their results: radioecology and human medicaments. At both of them, quality and trustfulness of
results is of great importance for their end-users and may have serious economical and legal consequences. The trends of implementation
of good laboratory and manufacturing practices under umbrella of international quality management standards like ISO 17025:2005
and ISO 9001:2000 in radiochemical and radiopharmaceutical laboratories are discussed as expanding to “good scientific practice”.
The case studies of the Comenius University laboratory LARCHA authorized for radiochemical analysis, and the company BIONT
producing medical radionuclides and PET radiopharmaceuticals are used as the examples. 相似文献
104.
105.
106.
Tamara A. Vaganova Vladimir I. Rodionov Georgij E. Sal’nikov Evgenij V. Malykhin 《Journal of fluorine chemistry》2008,129(4):253-260
Monoamination of octafluoronaphthalene by liquid ammonia affords 2-aminoheptafluoronaphthalene mainly (isolated yield 85-90%). Diamination of octafluoronaphthalene or amination of 2-aminoheptafluoronaphthalene affords a mixture of isomeric 1,6-, 1,7-, 2,6-, and 2,7-diaminohexafluoronaphthalenes with considerable prevalence of the 2,7-isomer (∼70%), thus being the first example of the predominant substitution at position 7 in 2-substituted polyfluoronaphthalenes. The 2,7/2,6 ratio of 2-X-heptafluoronaphthalene (X = −NH, NH2 and NHAc) amination diminishes with the decrease of electron-donating effect of the substituent; 2,7-diaminohexafluoronaphthalene forms in the reactions of 2-aminoheptafluoronaphthalene or octafluoronaphthalene with excess of NaNH2 in liquid ammonia and 2,6-diaminohexafluoronaphthalene—in the reaction of 2-acetylamidoheptafluoronaphthalene with liquid ammonia followed by acetylamido group hydrolysis. The method of the selective preparation of these diamines based on the reversible transformation of amino group and a convenient technique of their high purity isolation by complexation with crown ether have been elaborated. 相似文献
107.
The paper demonstrates conceptual parallels and relationships between intellectual capital measurement methods and the evaluation
of quality in clinical laboratories in the Slovak Republic. It explores further the contextual links of those parallels with
the tangibility (or intangibility) of quality indicators of laboratory diagnostics. It also highlights the problems which
laboratory staff in Slovakia are confronted with.
Presented at the conference Quality in the Spotlight, March 2007, Antwerp, Belgium. 相似文献
108.
109.
Isabel C.F. Damin Morgana B. Dessuy Tamara S. Castilhos Márcia M. Silva Maria Goreti R. Vale Bernhard Welz Dmitri A. Katskov 《Spectrochimica Acta Part B: Atomic Spectroscopy》2009
The determination of trace elements in crude oil is difficult due to the complex nature of the sample and the various different chemical forms in which the metals can occur. The advantage of graphite furnace atomic absorption spectrometry is that only a minimum of sample pretreatment is required. In this work two techniques have been compared to establish a fast and reliable method for lead determination in crude oil. In the first one the crude oil samples were weighed directly onto solid sampling (SS) platforms and introduced into the graphite tube for analysis. In the second one the samples were prepared as oil-in-water emulsions and analyzed in a filter furnace (FF). Twenty μL of a mixture of 0.5 mg L− 1 Pd + 0.3 mg L− 1 Mg + Triton X-100 has been used as the modifier, and calibration against aqueous solutions has been used for both methods. The sensitivity obtained with the FF was more than a factor of two better than that with SS; however, as a larger sample mass could be introduced in the latter case, so that the limits of detection for both techniques were 0.004 mg kg− 1. Seven crude oil samples were analyzed using the two procedures, and all results were in agreement at a 95% confidence level using a paired Student's t-test. For validation purposes, three crude oil samples have been mineralized using an open-vessel acid digestion, and the results were in agreement with those found with direct sampling and with emulsion sampling using FF according to ANOVA test. Both methods are simple, fast and reliable, being appropriated for routine analysis; however, the direct method using SS technology should be preferred because of its simplicity, speed and commercial availability. 相似文献
110.
In the present experiments the high temperature successive deposition (HTSD) of Al and Pt and the half shadowing technique
producing wedge shaped area with increasing quantity of deposited Pt are applied for studying the initial stages of solid
phase reaction producing amorphous Al2Pt phase. The nucleation of Al2Pt phase results in a decoration pattern which could be related to the characteristic local oxide coverage of the Al crystal
surface developing by kinetic segregation of oxygen species during the Al film deposition. In the area of larger amount of
deposited Pt, where the Al2Pt phase is continuous Kirkendall voids are present.
The samples were investigated in plane by transmission electron microscopy (TEM) and selected area electron diffraction (SAED)
and analysed by energy dispersive X-ray spectroscopy (EDX). 相似文献