Determination of mercury in sludge and materials used for HG-eliminations from industrial waste waters by zeeman atomic absorption spectrometry after matrix modification with potassium bromide and bromine

Summary Mercury was determined by Zeeman Atomic Absorption Spectrometry after matrix modification of urine and waste water by addition of 0.1M HNO₃, 0.05M KBr, and 5l Br₂/ml, and after its extraction from sludge, iron sludge and ion exchanger by a mixture containing the same additives. The same samples were also analysed by the cold vapour method after wet oxidation of the samples in closed teflon bombs. The ratio of the corresponding concentrations was 1.21±0.39 (SD) and the concentration range covered 0.1–50000 mg Hg/kg. The analytical powers of both procedures are compared.

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Bestimmung von Quecksilber in Schlamm und in für die Reinigung industrieller Abwässer verwendeten Materialien mit der Zeeman-Atomab-sorptions-Spektrometrie nach Matrixmodifizierung durch Kaliumbromid und Brom

Zusammenfassung Quecksilber wurde mit der Zeeman-Atomabsorptions-Spektroskopie in Urin und Abwässern nach einer Matrixmodifizierung durch Zugabe von 0,1M HNO₃, 0,05M KBr und 5 l Br₂/ml sowie nach seiner Extraktion aus Schlamm, Eisenschlamm und Ionenaustauschern mit einer Mischung der gleichen Zusatzstoffe bestimmt. Die gleichen Proben wurden auch nach der Kalt-Dampf-Methode nach dem Naßaufschluß in geschlossenen Teflonbomben analysiert. Das Verhältnis der betreffenden Konzentrationen betrug 1,21±0,39 (Standardabweichung), wobei der Konzentrationsbereich 0,1–50000 mg Hg/kg umfaßte. Die analytischen Leistungsfähigkeiten der beiden Verfahren wurden verglichen.

     

Synthesis and conversions of metallocycles. 7. A novel approach to the synthesis of 3,4-dialkyl-substituted aluminacyclopentanes in the presence of Cp2ZrCl2

A novel approach was developed for the stereoselective synthesis of trans-3,4-dialkyl-substituted aluminacyclopentanes from -olefins, metallic magnesium, and EtAlCl₂ in the presence of catalytic amounts of Cp₂ZrCl₂. The hydrolysis and deuterolysis products of the 3,4-dialkyl-substituted aluminacyclopentanes obtained are only in the trans configuration.For previous communication, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1607–1609, July, 1991.     

Application of a nickel hexacyanoferrate(II) composite ion exchanger to fast separation of Ra from Fr and Ba from Cs

Sorption studies of Ra, Ba, Fr and Cs on nickel hexacyanoferrate(II) composite ion exchanger from hydrochloric acid and EDTA solutions are presented.     

Liquid-phase oxidation of bromovinyl compounds with molecular oxygen

Liquid-phase oxidation of bromovinyl compounds with the aim to obtain the corresponding α-bromo acids was studied. Original Russian Text R.B. Bayatyan, B.E. Bayatyan, L.A. Saakyan, 2006, published in Zhurnal Prikladnoi Khimii, 2006, Vol. 79, No. 11, pp. 1870–1873.     

S=N versus S+-N-: an experimental and theoretical charge density study

To elucidate the bonding situation in the widely discussed hypervalent sulfur nitrogen species, the charge density distributions rho(r) and related properties of four representative compounds, methyl(diimido)sulfinic acid H(NtBu)(2)SMe (1), methylene-bis(triimido)sulfonic acid H(2)C[S(NtBu)(2) (NHtBu)](2) (2), sulfurdiimide S(NtBu)(2) (3), and sulfurtriimide S(NtBu)(3) (4), were determined experimentally by high-resolution low-temperature X-ray diffraction experiments (T = 100 K). This set of molecules represents an ideal frame of reference for the comparison of SN bonding modes, because they contain short formal S=N double bonds as well as long S-N single bonds, some of them influenced by inter- or intramolecular hydrogen bonds. For comparison, the gas-phase ab initio calculations of the four model compounds, H(NMe)(2)SMe, H(2)C[S(NMe)(2)(NHMe)](2), S(NMe)(2), and S(NMe)(3), were performed. The topological features were found to be not particularly sensitive with respect to different substituents R (R = H, Me, tBu). In this paper, it is documented that theory and experiment differ in the eigenvalues of the Hessian matrix because of systematically differing positions of the bond critical points but agree very well concerning the spatial Laplacian distribution and the distinct polarization of all investigated sulfur-nitrogen bonds. Both recommend the S(+)-N(-) formulation of sulfur nitrogen bonds in 1 and 2 since all nitrogen atoms are found to be sp(3) hybridized. The planar SNx (x = 2, 3) units in the diimide 3 and the triimide 4 reveal characteristics of m-center-n-electron systems. For none of the investigated S-N bonds, a classical double bond formulation can be supported. This is further substantiated by the NBO/NRT approach. Valence expansion to more than eight electrons at the sulfur atom can definitely be excluded to explain the bonding.