Visible light induced reversible extrusion of nitric oxide from a ruthenium(II) nitrosyl complex: a facile delivery of nitric oxide

The new ruthenium compound [Ru(NO)(pysiS4)]Br (3) (pysiS4 = 2,6-bis(3-triphenylsilyl-2-sulfanylphenylthiomethyl)pyridine), containing sterically bulky SiPh3 groups ortho to the thiolate donors, has been synthesized. In solution, 3 releases NO efficiently on exposure to visible light (lambda >/= 455 nm) at room temperature to afford [Ru(Br)(pysiS4)] (4). Treatment of 4 with NO yielded exclusively 3 without any metal-bound side reaction.     

Polarographische Untersuchung der Nickel- und der Zinkkomplexe der Adipinsäure

Zusammenfassung Die Nickel- und Zinkkomplexe der Adipinsäure werden polarographisch untersucht. Es zeigt sich, daß Zink reversibel reduziert wird, wogegen Nickel eine irreversible Stufe ergibt. Die Stabilitätskonstanten des Zink—Adipinsäurekomplexes werden nachDeFord undHume berechnet. Der Einfluß des pH-Wertes auf die Zink- und die Nickelstufe wird untersucht. Zink und Nickel werden in Gegenwart vieler störender Kationen halbquantitativ bestimmt.

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The said complexes have been studied by polarography. Zn is found to be reversibly reduced while Ni gives an irreversible wave. Stability constants of the Zn complex are calculated byDeFord andHume method. Effect of pH on Zn and Ni wave are reported. Estimations of Zn or Ni are carried out separately or in presence of interfering cations.

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Mit 7 Abbildungen     

Mechanism of ruthenium tetroxide-catalysed oxidation of aldoses by alkalineN-bromoacetamide

The kinetics of oxidation of three aldoses (glucose, mannose and galactose) byN-bromoacetamide (NBA) in the presence of an alkaline solution of RuO₄ as catalyst and Hg(OAc)₂ as co-catalyst and as a scavenger for bromide have been investigated. The main products of the oxidation are the corresponding aldonic acids. The reaction is zero order with respect to aldose and OH⁻. First order dependence of the reaction on both NBA and RuO₄ at low concentrations shifts to zero order at higher concentrations. Addition of acetamide decreases the reaction rate, while addition of Hg(OAc)₂ has the opposite effect. No significant effect of ionic strength was observed. OBr⁻ is postulated as the reactive oxidising species and a mechanism involving co-catalysis by RuO₄ and Hg^II is proposed. TMC 2588     

Relevance of chemistry to white biotechnology

White biotechnology is a fast emerging area that concerns itself with the use of biotechnological approaches in the production of bulk and fine chemicals, biofuels, and agricultural products. It is a truly multidisciplinary area and further progress depends critically on the role of chemists. This article outlines the emerging contours of white biotechnology and encourages chemists to take up some of the challenges that this area has thrown up.     

Determination of 3-sulfolene in sulfolane by reaction gas chromatography

Summary A simple gas-liquid chromatographic method has been developed for determining 3-sulfolene in sulfolane. The method involves thermal decomposition of sulfolene and determination of the 1.3-butadiene evolved, by GLC. Influence of the operating parameters on quantitative decomposition of sulfolene has been studied. The accuracy of the method as studied in the concentration range from 0.05 to 4.0 % (w/v) of 3-sulfolene in sulfolane is found to be within ±3.0%. It is rapid and sensitive down to 10 ppm and has potentialities for on-line applications also.

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Bestimmung von 3-Sulfolen in Sulfolan durch Reaktions-Gas-Chromatographie

Zusammenfassung Eine einfache gas-chromatographische Methode wurde entwickelt, die auf der thermischen Zersetzung der Probe und der Bestimmung des dabei aus 3-Sulfolen gebildeten 1,3-Butadiens beruht. Der Einfluß der einzelnen Parameter wurde untersucht. Innerhalb eines Konzentrationsbereichs von 0,05–4,0% 3-Sulfolen ergaben sich Fehler von ±3%. Das Verfahren ermöglicht bis herab zu 10 ppm eine schnelle und empfindliche Bestimmung und eignet sich auch zum on-line Betrieb.

     

Reactions of C(6)F(5)Li with tetracyclone and 3-ferrocenyl-2,4, 5-triphenylcyclopentadienone: An (19)F NMR and X-ray crystallographic study of hindered pentafluorophenyl rotations

Tetracyclone, 2a, reacts with C(6)F(5)Li to yield 2-pentafluorophenyl-2,3,4,5-tetraphenylcyclopent-3-en-1-one, 7, and 5-hydroxy-5-pentafluorophenyl-1,2,3,4-tetraphenylcyclopentadiene, 8, as the result of 1,6 and 1,2 additions, respectively. In contrast, treatment of 3-ferrocenyl-2,4,5-triphenylcyclopentadienone, 2b, with lithiopentafluorobenzene leads to 4-ferrocenyl-4-pentafluorophenyl-2, 3,5-triphenylcyclopent-2-en-1-one, 9, and 5-hydroxy-5-pentafluorophenyl-2-ferrocenyl-1,3, 4-triphenylcyclopentadiene, 10, the products of 1,4 and 1,2 addition, respectively. The structures of 7-9 have been established by X-ray crystallography, and the barriers to rotation (19-21 kcal mol(-)(1)) of the pentafluorophenyl groups in 8-10 have been studied by variable-temperature (19)F NMR. Nucleophilic attack at the ferrocenyl-bearing carbon in 2b is rationalized in terms of a zwitterionic structure in which the positive charge of the "cyclopentadienyl cation" is delocalized onto the iron atom in the organometallic substituent.     

Synthesis of some new 4-imino-3,5,7-trisubstituted-pyrido[2,3-d]pyrimidine-2(1H)-thiones

The synthesis of 4-imino-3,5,7-trisubstituted-pyrido[2,3-d]pyrimidine-2(1H)-thiones is described. The elemental analysis, ir and nmr spectral data confirm the structure of the products.     

Gravimetric determination of thorium and zirconium

Summary Thorium and zirconium can be quantitatively precipitated by quinaldinic acid atph 2.7 and 3, respectively. As the precipitates are of nonstoichiometric composition they are to be ignited to oxides. By this reagent thorium can be quantitatively separated from arsenic (As³⁺), mercury (Hg²⁺), rare earths, manganese, magnesium and alkaline earths and zirconium from all the aforesaid ions excepting rare earths which contaminate to a slight extent.     

Direct determination of traces of Ag, Cd, Pb, Bi, Cr, Mn, Co, Ni, Li, Be, Cu and Sb in environmental waters and geological materials by simultaneous multi-element graphite furnace atomic absorption spectrometry with Zeeman-effect background correction

A method was developed for direct determination of minor and trace amounts of Cr, Mn, Cu, Ni, Co, Li, Pb, Cd, Bi, Sb, Be and Ag in silicate rock, lake and stream sediments using a microwave oven dissolution method and a multi-element graphite furnace atomic absorption spectrometer equipped with a Zeeman-effect background correction device. The measurement technique was also suitable for direct determination of trace and ultra-trace amounts of these elements in drinking and seawater samples. A rock or sediment sample was brought into solution in a Teflon vessel by heating in a microwave oven with a mixture of hydrofluoric acid and aqua regia, followed by a further heating with a mixture of boric acid and ethylenediaminetetraacetic acid. The specified elements were directly determined in a group of four elements in one firing and eight elements in two firings from this solution or from a diluted solution using the optimum operating parameters developed in this work. The method, tested with 23 international reference rocks and sediments and seven international quality control and reference water samples, showed good to excellent agreement with the recommended values.