Zur Polymerisation der Germaniumsäure, 2. Mitt. Ermittlung der Komplexzusammensetzungen und Berechnung der zugehörigen Stabilitätskonstanten auf Grund graphischer Ausgleichsverfahren

Auf Grund der in der 1. Mitt. erhaltenen Meßdaten werden mit Hilfe graphischer Ausgleichsverfahren Näherungswerte für die Stabilitätskonstanten ermittelt.

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Mit 1 Abbildung

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Herrn Prof. Dr.E. Hayek zum 60. Geburtstag gewidmet.

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Auszugsweise vorgetragen auf dem Chemikertreffen Schweiz-Österreich am 4. Oktober 1963 in Innsbruck. Vgl. Österr. Chemiker-Ztg.64, 294 (1963).

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Siehe auch die vorangehende 1. Mitt. Hinweise auf Gleichungen bzw. Abb. der 1. Mitt. sind hier mit I bezeichnet, solche auf die folgende 3. Mitt. mit III.     

Toward a general route to the eunicellin diterpenes: the asymmetric total synthesis of deacetoxyalcyonin acetate

A novel approach to the hydroisobenzofuran core utilizing a TiCl4-mediated [4+3] annulation is reported. This [4+3] annulation protocol provides a short, general route to the hydroisobenzofuran core present in the eunicellin diterpenes. Using this annulation, a short synthesis (17 steps) of deacetoxyalcyonin acetate, a member of the eunicellin family, has been achieved.     

Michael additions to trifluoromethylvinyl sulfone

Michael addition reactions of trifluoromethyl vinyl sulfone with organic compounds with labile hydrogen atoms are studied. Such additions can be successfully accomplished using potassium fluoride and 18-crown-6-ether or benzyltrimethylammonium hydroxide (Triton B) as catalysts.     

Identification and decay of182Tl

A new activity with a 3s half-life at mass 182 was produced via proton spoliation reaction on thorium carbide target and mass separation. From the observation of known rays observed in¹⁸²Hg, it was assigned to the (⁺+ EC) decay of¹⁸²Tl, the spin and parity of which is very likely 7⁺.     

Collocation Methods for Weakly Singular Second-kind Volterra Integral Equations with Non-smooth Solution

Collocation type methods are studied for the numerical solutionof the weakly singular Volterra integral equation of the secondkind: where the solution (t) is assumedto have the form f(t) = x(t)+r^?(t), x and being sufficientlysmooth. The solution is approximated near zero by a linear combinationof powers of t?, and away from zero by the usual polynomialrepresentation. Convergence is proved and many numerical experimentsare carried out with examples from the literature. A comparisonis made with a method of Brunner & Norsett (1981), originallydeveloped for (1) with a smooth solution. Special attentionis paid to the numerical approximation of the so-called momentintegrals which emerge in the collocation scheme.     

Darstellung und charakterisierung von trifluormethylthio-cyclopropanen

The reactions of dihalogenocarbenes (CX₂, X = F, Cl, Br) with CF₃SCHCH₂ or (CF₃S)₂CCH₂ yield the corresponding substituted cyclopropanes. 1,1-Dibromo-2-trifluoromethylthio- or 1,1-dibromo- 2,2-bis(trifluoromethylthio)cyclopropanes react with (nC₄H₉)₃SnH to form trifluoromethylthio - or 1,1-bis(trifluoromethylthio)cyclopropane in good yields. Physical and spectroscopic data of the new substances are provided.     

Aminoalkoholester von Hydroxyboranen,IX Salicylamid-Bor-Mannichbasen als potentielle Antitumorwirkstoffe

A synthesis of new boron containingMannich bases of salicylamide by reaction of salicylamide, formaldehyde and boron-heterocycles is reported.

VIII. Mitteilung:Stump, R. K., Zimmerman jr., H. K., Schleppnik, A. A., Gutsche, C. D., Liebigs Ann. Chem.667, 18 (1963).     

Ergebnisse aus versuchen zur darstellung von bis(trifluormethylsulphanyl)thioketen (CF3S)2C=C=S

The attempted preparation of bis(trifluoromethylsulphanyl)thioketene is described. Mono-and di-(trifluoromethylsulphanyl)-substituted orthothioesters may be prepared fromCH₃C(SC₂H₅)₃ and CF₃SCl in the presence of anhydrous ZnCl₂. The unstable compoundshave been isolated and characterized. The corresponding CF₃Se and CF₃SO₂ derivativesare only formed as intermediates which decompose to ketene diethylmercaptal. Suchmono- and di-substituted products are obtained in good yield from H₂C=C(SC₂H₅)₂ andCF₃ECl (E=S, Se). The reaction of H₂C=C(SC₂H₅)₂ with CF₃SO₂F gave only poor yieldsof (CF₃SO₂)_nCH_2−n=C(SC₂H₅)₂ (n=1, 2) which were only capable of characterizationin etheral solution by spectral means. Attempts to prepare (CF₃S)₂C=C=S by refluxing(CF₃S)₂CHC(O)Cl, (CF₃S)₂CHC(O)OH or (CF₃S)₂C=C=O with P₄S₁₀ in toluene yieldedonly the cyclic dimer and the corresponding 1,3,4-trithiolan.