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21.
Gas-stirred propylene carbonate (PC) extraction can be performed by bubbling nitrogen without loss of volume. This extraction technique has proved to be highly useful for the separation and subsequent direct polarographic estimation of Tl(III) in the recovered PC phase. Tl(III) can be determined by differential-pulse polarography over the concentration range of 0.4 10 g ml–1 without any interferences due to most metal ions such as Pb(II), Bi(III), Cu(II), Sb(III) and As(III). This proposed technique would be possible to use as a simple extraction step prior to the final estimation by instrumental method of analysis such as atomic absorption spectrometry or spectrophtometry. 相似文献
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The effects of some organic solvents and acids on the atomic fluorescence of tin in air-hydrogen flames have been examined. Ketones and alcohols greatly reduced the florescence sensitivity in fuel rich air-hydrogen flame whereas organic acids generally enhanced the fluorescence signal. The depressive effect of organic solvents was found to be highly dependent on the fuel to oxidant ratio in the flame. An attempt has been made to explain these effects, on the basis of possible reactions occurring in the flame.On leave from Institute of Chemistry, University of the Punjab, Lahore 54590, PakistanOn leave from Department of Analytical Chemistry, University of Zaragoza, Zaragoza, Spain 相似文献
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The results of NMR-spectroscopy studies of the structure, dynamic stereochemistry, and intermolecular interactions in solutions
of organic derivatives of penta-and hexacoordinated silicon, germanium, and tin containing amidomethyl, lactamomethyl, and
related bidentate ligands are surveyed.
For the series of works “Dynamic stereochemistry of hypervalent compounds of silicon, germanium, and tin,” the author was
awarded the Academia Europea Prize for young scientists from CIS in 1996.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1912–1934. November, 1997. 相似文献
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Conductance measurements for fifteen uni-univalent salts in 2-methylpyridine-N-oxide (2-MPO) were made over the concentration range of 2–120×10–4 mol-dm–3 at 55°C. All conductance data were evaluated by the Lee-Wheaton equation. The results indicate that all of the salts studied are slightly associated in 2-MPO, which is, nevertheless, a reasonably good ionizing solvent compared to other solvents having a similar value for the dielectric constant. The tetraalkylammonium halides are weaker electrolytes than the tetraphenylborate salts in 2-MPO. Ionic limiting molar conductances were obtained by using as a reference electrolyte tris(iso-pentyl)butylammonium tetraphenylborate. Anions appear to be poorly solvated in this solvent but certain cations, particularly Na+ and K+, show evidence of specific ion-solvent interaction.This study was presented, in part, at the 6th Central Regional Meeting of the American Chemical Society, Detroit, Michigan, April 1974. 相似文献
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The crystal structure of synthetic carlinite, Tl2S, was re-determined by single crystal and powder X-ray diffraction methods. The cell parameters obtained from Rietveld refinement are a=12.150(2) Å, c=18.190(4) Å, V=2325.5(7) Å3. A single crystal data refinement proved Tl2S crystallizing in the trigonal space group R3 with M=440.8gmol−1, Z=27, R=0.076, and wR=0.145. The atomic arrangement found is that of a strongly deformed anti-CdI2 type, but the deformation is clearly different from that given by previous workers. In the five crystallographically different STl6 octahedra the S-Tl distances vary between 2.82 and 3.09Å, the Tl-Tl edges between 3.52 and 4.58Å. The common features of these octahedra are (i) each one with a definitely smaller vs larger Tl3 face in trans-position, both faces parallel or sub-parallel (00.1), and (ii) each three shorter and longer S-Tl distances to the atoms of the larger and smaller Tl3 faces, respectively. The Tl-Tl contacts between different Tl2S sheets are on the average definitely shorter than the ones within the sheet and they can be smaller than the Tl-Tl contacts in the small Tl3 faces of the STl6 octahedra. The atomic arrangement indicates that the single electron pairs of the monovalent Tl atoms are not arranged all parallel to the z-axis, as one would expect for Tl2S with an ideal anti-CdI2 structure. The surrounding of the S atoms resembles that of one-third of the Cl atoms in yellow InCl. The absorbance of Tl2S is very low at wave numbers approximately <9000 cm−1. 相似文献