Transformations of Cyclohexane under the Action of in situ Generated Aluminum Halides

Transformations of inert cyclohexane into dimethyldecalins under mild conditions in the presence of a simple catalytic system consisting of aluminum metal and halomethanes were studied.     

Characterisation of fatty acids in biological oil samples using comprehensive multidimensional gas chromatography

Comprehensive multidimensional gas chromatography can adequately resolve very complex mixtures of analytes such as the fatty acid mixtures which are contained in, e.g., fish and vegetable oils. Well-ordered patterns are obtained in the two-dimensional separation plane which can be used to tentatively identify peaks when no standard is available. The technique which can also be used for quantification, i.e., quantitative ratio analysis, should be especially useful for fingerprinting purposes. Unravelling the composition of complex mixtures such as fish oils appears to be highly rewarding.     

Multivariate data analysis of trace element content in animal organs measured by simultaneous atomic absorption spectrometry

The simultaneous determination of trace elements in animal organs offers improved possibilities to characterize the geographical origin of the animal by analyzing its pollution characteristics. Pb, Cd, Ni (GF-AAS) and Cu, Zn, Fe, Mn (F-AAS) in kidneys and livers of cows from different sites have been measured using simultaneous AAS. The correct allocation of cows to specific regions shows that multivariate data analysis provides efficient tools for the geographical classification. The consideration of absorbance rather than concentration as the data input simplified the analytical procedures by omitting the calibration step.     

Anomalies in the temperature dependence of the 1.2-μ absorption of liquid water

The weakly absorbed 1.2-μ combination band of water was accurately studied as a function of temperature, in both its profile and first derivative, to obtain information on the bulk properties of liquid water. Arrhenius plots of integrated component intensity ratios showed well aligned experimental points, except for a neatly defined break occurring in the 30 to 40°C temperature interval for pure water A similar break, shifted by some 18°C towards lower temperature, was found in the case of 1M NaClO₄ aqueous solutions. The breaks are tentatively assumed to result from abrupt though subtle changes involving low-frequency modes. This tentative, assumption appears independent of specific models and assignments and, although in agreement with available neutron-scattering and NMR data, needs more direct verification.     

FTIR-screening of carbonyl compounds in metal working fluid aerosols

Due to the complex composition of metal working fluids (MWF) the determination of all individual compounds is sometimes difficult and very expensive. Today the widely used method for the quantification of airborne MWFs consists of a non specific IR analysis of their C-H valence bands. With a new design of sample cell this inexpensive technique was extended to a more detailed screening of the MWF composition, especially the detection of carbonyl compounds in MWFs and their aerosols and vapors. The screening method was evaluated for the determination of concentrations of the aldehyde nonanal and the ketone diacetone alcohol in air in laboratory experiments. In preliminary workplace studies the applicability of this method to the (semi-)quantitative determination of carbonyl compounds in airborne MWFs is shown. The screening method was found to be very useful, specially to detect alterations in the composition of the MWF due to industrial use. Received: 16 January 1997 / Revised: 9 April 1998 / Accepted: 14 April 1998     

Ultratrace analysis of uranium and thorium in glass

Three methods of determination for uranium and thorium traces and ultratraces in glass were developed: a simple and powerful ICP-MS method exhibiting limits of determination in the one ng/g-range; a complex method with end-determination by classical photometry and a limit of determination for U and Th of 20 ng/g; and a method with chelate-complex formation for U and Th and subsequent GC-detection with a ⁶³Ni-ECD with limits of determination in the g/g-range. These methods are critically compared and tested for real type samples of special glasses.Abbreviations used AAS Atomic absorption spectrophotometry - ECD Electron capture detector - FOD 1,1,1,2,2,3,3-Heptafluoro-7,7-dimethyl-4,6-octanedion - GC Gas chromatography - HFA 1,1,1,5,5,5-Hexafluoro-2,4-pentanedione - ICP-AES, -MS Inductively coupled plasma-atomic emission spectrometry, metry, -mass spectrometry - LAS Liquid absorption spectrophotometry = classical photometry - NAA Neutron activation analysis - NIST National Institute of Standardization and Technology (Gaithersburg, U.S.A.) - TBP Tri-(n-butyl)-phosphate - TFA 1,1,1-Trifluoro-2,4-pentanedione - TTFA 1-(2-Thenoyl)-3,3,3-trifluoroacetone - XRS X-ray (fluorescence) spectrometry     

Beiträge zur Komplexchemie der Phosphine und Phosphinoxide. XXIII. Schwermetallkomplexe des Tetramethyl-biphosphins

On the coordination chemistry of phosphines and phosphinoxides. XXIII. Heavy metal complexes of tetramethyl-biphosphine The reactions of tetramethyl-biphosphine with salts of 3d elements including Cd and Hg, too, in THF, benzene, acetonitrile and alcohols, respectively, results in forming complexes of differing compositions: (MⁿX_n)₂{(CH₃)₂P? P(CH₃}₂)₃? Mⁿ = Ti^III, V^III, Cr^III, Fe^II, Ni^II, Cu^I; MX₂{(CH₃)₂P? P(CH₃)₂}₂? M = Co^II, Ni^II, Hg^II; MX₂ · (CH₃)₂P? P(CH₃)₂? M = Fe^II, Ni^II, Zn, Cd, Hg^II; X = Cl, Br, J. The partly intensively coloured complexes have low solubilities; this item complicates the performing of structure determining methods. Partial informations about the structures of the complexes are to be gained by magnetic and spectrophotometric measurements and X-ray investigations. The tendency of (CH₃)₂P? P(CH₃)₂ to form complexes with transition metals differs from that of other biphosphines. Splitting of the P? P bond due to metal salts does not occur. (CH₃)₂P? P(CH₃)₂ acts as a monodentate or bidentate ligand, like other members of the R₂P? PR₂ series do too. The forming of ligand bridges seems to be favoured in comparison to the chelate function.     

Linear codimerization of 2-cyclopropyl-1,3-butadiene with methyl acrylate catalyzed by iron and cobalt complexes

Conclusions The linear codimerization of 2-cyclopropyl-1,3-butadiene with methyl acrylate gave a mixture of methyl esters of 5-cyclopropyl-2Z,5Z- and 2E,5Z-heptadienoic acids.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2364–2366, October, 1984.     

High-speed liquid chromatography of polychlorinated biphenyls and related compounds.

High-speed liquid chromatography in the system silica gel-dry n-hexane has been used to characterize the behaviour of a series of commercially available mixtures of chlorinated biphenyls, viz., Aroclor 1221-1268. An attempt has been made to assign a large number of peaks in the chromatograms of the Aroclors to the individual constituents. To this end, retention times and UV spectra were recorded for 47 polychlorinated biphenyls. The dependence of retention and spectral characteristics on the chlorine content of the substituted biphenyls is discussed