A Procedure for the Deposition of Macrocomponents in Determining Selenium and Tellurium in Metallurgical Materials by Inductively Coupled Plasma Atomic Emission Spectrometry

Journal of Analytical Chemistry - Studies on the separation of the Se and Te trace components from Co, Ni, Cu, Fe, Cr, Mo, and W macrocomponents for their determination by inductively coupled...     

Fiber-Optic Backscattering Profile Measurements for Determination of the Optical Coefficients of Turbid Media

The necessity of using anisotropic approximation in techniques for determining optical parameters from the backscattered radiation profile is shown. A fiber-optic technique for simultaneous determination of the anisotropy parameter as well as the scattering and absorption coefficients of turbid media is proposed. It is based on the comparison of the experimental backscattered radiation profiles and those obtained by the numerical Monte Carlo method.     

Hydrogen Oxidation on a Platinum Microelectrode: Effect of Carbon Monoxide Impurities

The kinetics of the hydrogen oxidation and the CO adsorption on a Pt (ultra)microelectrode is studied in a 0.5 M H₂SO₄ solution saturated with a mixture of gaseous H₂ and CO at partial CO pressures p _CO = 10–500 ppm. The balance between rates of diffusion and adsorption of CO at different adsorption times is studied. Studied is the effect of CO impurities in H₂ on steady-state polarization curves for the hydrogen ionization and nonsteady-state curves of the oxidation current decay with time at 0.02–0.05 V. Conditions under which in a certain time interval and at a certain CO concentration the slope of an I vs. t curve is proportional to p _CO are determined. The obtained dependence may be used when designing a technique for monitoring CO impurities in technical hydrogen.     

Synthesis and structure of 5,5-dialkyl-3-arylamino-2-thiohydantoins

The reaction of arylhydrazides of -alkyl--chlorocarboxylic acids with thiocyanate ions gave intermediate thiocyanates which rearranged to isothiocyanates on heating and the latter cyclized to 5,5-dialkyl-3-arylamino-2-thiohydantoins.Institute of Technical Chemistry, Urals Branch, Russian Academy of Sciences, Perm' 614000. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 898–903, July, 1997.     

The synthesis of some (pentafluorophenyl)germanium compounds

Tris(pentafluorophenyl)germanium bromide reacts with lithium aluminium hydride or triethylgermane to give tris(pentafluorophenyl)germane. On reaction with HgR₂ [where R = Et, Et₃Ge and (Me₃Si)₂N] or reaction with diethylcadmium, the latter gave the hitherto unknown [(C₆F₅)₃Ge]₂Hg or [(C₆F₅)₃Ge]₂Cd. The germylmercurial compound could also be prepared by reaction of metallic mercury with [(C₆F₅)₃Ge]₂Cd and by exchange of bis(triethylgermyl)mercury with (C₆F₅)₃GeBr. Some reactions of bis[tris(pentafluorophenyl)germyl]mercury are discussed.     

New routes to pentafluorophenyl derivatives with germanium-chalcogen bonds

Tris(pentafluorophenyl)germanethiol, (C₆F₅)₃GeSH (Ia), was obtained in good yield by heating the tris(pentafluorophenyl)germane with elemental sulphur or by the exchange between Et₃GeSH and (C₆F₅)₃GeBr. The reaction between sulphur and (C₆F₅)₂GeH₂ or C₆F₅GeH₃ gives heterocyclic products with chains of alternating germanium and sulphur atoms in the cycles. The compounds [(C₆F₅)₃Ge]₂X (X = S, Se) were prepared by exchange reaction of (Et₃Ge)₂X with tris(pentafluorophenyl)germanium bromide and by reaction of chalcogens (S₈, Se₈) with hexakis(pentafluorophenyl)digermane. Ia reacts with diethylmercury affording (C₆F₅)₃GeSHgEt. Insertion of elemental sulphur into the GeHg bond of bis[tris(pentafluorophenyl)germyl]mercury led to the thermally stable (C₆F₅)₃GeSHgGe(C₆F₅)₃.     

Gas-Chromatographic Determination of Alkyl Acetates in Aqueous Solutions with Chromatomembrane Gas Extraction

Methods were developed for the gas-chromatographic determination of alkyl acetates in aqueous solutions in the concentration range of 0.01–100 mg/L with the chromatomembrane gas extraction of analytes from a flow of the test liquid. The analytical potentialities of the direct-flow and counterflow techniques of chromatomembrane gas extraction were compared. It was demonstrated that the interfering effect of petroleum products on the results of analysis can be eliminated by using an additional chromatomembrane cell.     

Azo coupling of 5-substituted furan-2(3H)-ones and 1H-pyrrol-2(3H)-ones with arene(hetarene)diazonium salts

5-Substituted furan-2(3H)-ones and 1-phenyl-1H-pyrrol-2(3H)-ones reacted with diazonium salts derived from substituted anilines and 1H-1,2,4-triazol-5-amine to give azo coupling products at the methylene group in the heteroring. The products were found to exist as hydrazone tautomers.