Abstracts(No.4.August 1999)

A STUDY OF DYNAMIC BEHAVIOR AND PHASE SEPARATION OF POLYACRYLIC GELS Ju Zuo , Fa-jun Zhang, Ying-li An, Ai-zhen Niu, Zhi-guang Zhang, Fang-xing Li, Chang-ying Zhu and Bing-lin HeThe State Key Laboratory of Functional Polymeric Materials for Adsorption and Separation, Department of Chemistry, Nankai University, Tianjin 300071Dynamic behavior and phase separation sensitive to temperature of a series of polyacrylic gels was studied by dynamic light scattering. The dynamic behavior of the gels is characterized in terms of the correlation lengthξand diffusion coefficient D. The rules of the influence of cross-linking degree, concentration of polymer and amount of initiator on ξand D were obtained. When cross-linking degree increases, ξdecreases and D     

N. K. Kochetkov (18.05.1915–21.12.2005)

In Memoriam

N. K. Kochetkov (18.05.1915–21.12.2005)     

STUDIES ON TRANSITION-METAL PERHALOPHENYL COMPOUNDS.VI.CRYSTAL STRUCTURE OF TRANS-BROMO-BIS(METHYLDIPHENYLPHOSPHINE) (σ-PENTABROMOPHENYL)NICKEL(II)

<正> M= 1010.62, D24-P212121, a=11.654(3), b=15.812(9), c=18.556(8) A, V=3419.5A3, Z=4, Dc=1.963 g·cm-3. Final R=0.066 for 2187 reflections. The central nickel(II) atom of the title compound is in slightly distorted square-planar coordination.     

H. C. Brown Centennial (1912–2004)

Herbert Brown discovered the reaction of hydroboration and the most successful compound he made was sodium borohydride. His life and research activities took interesting turns and seemed often governed by serendipity. He was consistent in his hard work and dedication to chemistry. He was both an inorganic and an organic chemist and his research often presented challenges to the structural chemists.     

Photochemical Symthesisof Aporphines: (±)-Thaliporphime. (±)-N-Nethyllaurotetanineand(±)-Isoboldime

Aporphines, (±)-thaliporphine (1). (±)-N-methyllaurotetatine (2), and (±)-isoboldine (3) were synthesised using photochemical cyclization as the key step.     

Oberflächenspannungsmessungen. IX (1)

Ohne Zusammenfassung Mit 3 Tabellen     

Professor Eduardo F. A. Neves (1933–2006)

Abstract

The present note deals with the optimization of the combustion of organic materials to CO₂ in Pyrex and quartz tubes. The influence of temperature and oxidant on the combustion yield was investigated. Different physical forms of CuO and a CuO/MnO₂-mixture were used as oxidants. Possible isotopic effects during combustion were tested by gas isotope ratio mass spectrometry (GIRMS) of the CO₂. Excellent results were obtained for combustion in Pyrex at 530 °C using CuO rods mixed with 20% MnO₂ as oxidant. The stable isotope results for CO₂ prepared with this method were accurate and showed a very good precision of 0.030 %. Applications for which quantitative combustion is a necessity, we suggest the use of CuO powder (< 100 μm) as oxidant and a combustion temperature of 850 °C.     

Chelatometrie. II. Äthylendiamintetraessigsäure (EDTA) und das Kupfer(II)/Kupfer(I)-Redoxsystem

Zusammenfassung In Gegenwart von reichlichen Mengen Ammoniumrhodanid sind Kupfer(II)-Ionen mit 0,01-m Äthylendiamintetraessigsäure gegen Variaminblau B-Base als Redoxindikator in schwach salzsaurer Lösung titrierbar. Auch die inverse Titration ist möglich. Der Bestimmungsbereich liegt unterhalb etwa 3 mg Kupfer bzw. 18 mg Äthylendiamintetraessigsäure.

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Summary Cooper(II) ions can be titrated with 0.01M ethylenediaminetetraacetic acid in the presence of much ammonium thiocyanate and in weakly hydrochlorid acid solution. Variamin blue B base serves as redox indicator. The reverse titration is likewise possible. The determination range lies below about 3 mg copper and 18 mg ethylenediaminetetraacetic acid, respectively.

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Résumé Il est possible de titrer les ions Cu(II) par l'acide éthylènediaminetétracétique 0,01 M en présence de quantités importantes de sulfocyanure d'ammonium et de l'indicateur d'oxydoréduction «Variaminblau B-Base» en solution faiblement chlorhydrique. Le titrage inverse est également possible.L'échelle analytique correspond à des quantités de substance à doser inférieures à environ 3 mg pour le cuivre et 18 mg pour l'acide éthylènediaminetétracétique.

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Mitteilung I dieser Reihe: Mikrochim. Acta [Wien]1955, 812.     

STUDIES ON POLY(ETHYLENE TEREPHTHA LATE)-POLY(TETRAMETHYLENE ETHER) MULTIBLOCK COPOLYMER.Ⅰ.COMPOSITIONAL HOMOGENEITY

The compositional homogeneity of a poly (ethylene terephthalate)-poly (tetramethylene ether) multiblock copolymer sample with low content of hard segment was examined by GPC, TLC, and solubility method. The copolymer sample was found to have a uniform composition as a function of elution volume over the major portion of sample from GPC method. However within one elution fraction, the copolymer chains, although having the same hydrodynamic volume, may have some difference in composition. Two fractions with different composition were obtained by precipitation in ethanol. Some low molar mass copolymers were also separated by a TLC technique from the copolymer sample.     

Front Cover: Safe Entry to Ag(I)/Ag(III) Mixed Valence Salts Containing the Homoleptic Ag(III) Anion [Ag(CF3)4]− (Eur. J. Inorg. Chem. 19/2023)

The synthesis of Naumann's Ag^I/Ag^III mixed valence salt [Ag^I]⁺[Ag^III(CF₃)₄]⁻ ( Ag-1 ) is revisited. Ag-1 is now safely available in half gram scale upon 2e⁻ oxidation of AgF in presence of CF₃SiMe₃ and ambient air. In addition to its unprecedented crystallographic characterization, the use of Ag-1 to build the novel Ag^I/Ag^III salts [ Ag (bpy)₂] -1 , [ Ag (18-crown-6)₂] -1 , [ Ag -crypt-222] -1 and [ Ag (PCy₃)₂] -1 is herein reported, alongside their characterization by NMR, single crystal X-ray diffraction (Sc-XRD) and elemental analysis (EA). The utility of the currently affordable Ag-1 in gold(I) catalysis was demonstrated by the excellent catalytic activity displayed by [{ Au (PPh₃)}₂(μ-Cl)] -1 and [ Au (PPh₃)] -1 in the 5-exo-dig cyclization of N-propargylbenzamide ( 2 ). These cationic Au^I catalysts are accessible from (PPh₃)AuCl and Ag-1 , and outperform the activity of the well-known benchmark catalyst (PPh₃)AuNTf₂.     

Protoberberine ausReissert-Verbindungen, 4. Mitt. Eine neue Synthese des (±)-Alamaridins und des (±)-epi-Alamaridins

Summary A novel synthesis of 8-methylisoquino[2,1-b][2,7]naphthyridinium salts7 is reported using the intramolecular cyclization of the 1-substituted isoquinolines5 as the key step, which in turn are obtained by alkylation of theReissert compounds1. The salts7 can be reduced by NaBH₄ yielding the 8- and 8-methylstereomers (±)-alamaridine and (±)-epi-alamaridine9c and11c, respectively.

     

Condensed aromatics—XXIII. Cyclo[d.e.d.e.d.e.d.e.d.e.d.e]dodecakisbenzene (kekulene)

Some topological properties of coronoids are given. These systems have chemical counterparts in cycloarenes. For one of these molecules, viz. C₄₈H₂₄ kekulene, the simple Hückel molecular orbital analysis has been performed and employed in the construction of a harmonic force field. Finally the set of calculated vibrational frequencies is reported.