Determination of metal traces in tantalum by proton activation analysis

Procedures for determining traces of calcium, titanium, vanadium, chromium, iron, copper, niobium, molybdenum and tungsten in tantalum are described utilizing 11 MeV proton activation. The instrumental method of analysis with the use of a Ge(Li) detector and the radiochemical separation of the corresponding fractions are described. The formula for the calculation of the concentration of traces with the use of thick target yields is given. Experimental data on the thick target yields of radioisotopes⁴⁴Sc,⁵²Mn,⁵⁶Co,⁶⁵Zn,^93mMo,⁹⁶Tc are presented. Based on the experimental data, the detection limits are estimated at 1–10 ppb for the above mentioned metal traces in tantalum. The successful solution of the task of the simultaneous determination of nine elements in tantalum confirms the wide applicability of proton activation analysis.     

Untersuchungen in der Thiazolreihe. III—massenspektrometrische Untersuchung von 2-Amino-3-hydroxythiazoliumchloriden

The mass spectrometric decomposition of 2-aminothiazole-3-oxides is characterised by the abstraction of O and OH out of the molecule ion. Distinct differences between 4-alkyl and 4-aryl derivatives as well as defined dependence of the [M – O]⁺·: [M – OH]⁺ ratio on the substituents are interpreted by a stabilisation of the [M – O]⁺·: radical cation through aromatic substitution. The effects of temperature suggest an equilibrum between tautomers in the inlet system.     

Synthesis and properties of polycondensation polymers from compounds with asymmetric functional groups

The effect of conditions of polycondensation on the structure of polymers formed from monomers with symmetric and asymmetric functional groups by nonequilibrium polycondensation has been studied for the system with acceptor-catalytic polyesterification of β-hydroxyethyl ethers of bisphenols and terephthalic acid chloride in the presence of triethylamine. Polymers with statistical or regular arrangement of diol residues in the chain can be produced in such systems, depending on the way in which starting compounds are introduced in the reactor. A difference in the reactivity of functional groups in an asymmetric monomer is not sufficient to produce polycondensation polymers with a regular structure. Gradual introduction of the symmetric monomer is essential to yield polymers with predominant “head-to-head” (“tail-to-tail”) configurations. Some properties of the resulting polymers have been studied. Polymers with ordered residues of the asymmetric monomers in the macromolecules have higher softening temperatures and an increased tendency for crystallization than the statistic polymers.     

Phenolic resins for solid-phase peptide synthesis: Copolymerization of styrene and p-acetoxystyrene

Details are given of the synthesis and purification of p-acetoxystyrene and its solution and suspension copolymerization with styrene. Reactivity ratios, evaluated by the Tidwell-Mortimer method, were r₁ (p-acetoxystyrene) = 1.18, and r₂ (styrene) = 0.88 for (bulk) solution copolymerization. Corresponding values of the reactivity ratios for suspension copolymerization were, within experimental error, indistinguishable from unity. Thus the copolymer composition is governed simply by the monomer feed composition. Use of a specially designed reactor vessel permits convenient suspension copolymerization of styrene, p-acetoxystyrene, and divinylbenzene to give crosslinked resins having comparatively narrow particle size distributions. Acetoxy groups in the crosslinked resin are cleaved by hydrazine hydrate under very mild conditions to give crosslinked polystyrenes having phenolic groups which, in turn, provide a useful alternative to the more usual chloromethylated polystyrene resins for solid-phase peptide synthesis.     

3-Furylchromones

-[2-(5-Methoxycarbonyl)furyl]-2,4-dihydroxy- and 2,4,6-trihydroxyacetophenones were obtained by the condensation of polyphenols with (2-methoxycarbonyl-5-furyl)acetonitrile. 7-Acetoxy- and 5,7-diacetoxy-2-methyl-3-[2-(5-methoxycarbonyl)furyl]chromones were obtained from them by reaction with acetic anhydride in the presence of triethylamine and were subsequently deacylated to 7-hydroxy and 5,7-dihydroxy compounds. 7-Hydroxy- and 5,7-dihydroxy-2-ethoxycarbonyl-3-[2-(5-methoxycarbonyl)furyl]chromones were obtained from the indicated acetophenones by reaction with ethoxalyl chloride.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1317–1320, October, 1972.     

Schiff bases in syntheses of substituted naphthylamines,naphthyridines, azaphenanthrenes,and benzocarbazole

9-Methylnaphtho[2,1-b][1,6]naphthyrldine and 2,3-dimethyl-1-azaphenanthrene were obtained on a K-16 dehydrogenating catalyst from N-(1,2,5-trimethyl-4-piperidylidene)--naphthylamine, while N-cyclohexylidene--naphthylamine yielded N-phenyl--naphthylamine and benzo[a]carbazole.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1400–1403, October, 1972.     

Polymethylene dyes derived from heterocyclic bases containing condensed thiophene rings

Some new polymethine dyes of the cyanine and merocyanine series which are derivatives of 5- and 6- thienopyridines are synthesized. Replacement of a vinyl group at a sulfur atom in the condensed benzene ring of quinoline in dyes which are derivatives of this base, always leads to a bathochromic shift of the absorption maximum of the corresponding dyes.     

Die Koordinationszahl von Lanthaniden: Thermodynamik der LnIIIEDTA-Mischkomplexe mit den Anionen der 8-Hydroxychinolin-5-sulfonsäure,Iminodiessigsäure und Nitrilotriessigsäure

The values of ΔG, ΔH and ΔS for the formation of the mixed 1:1:1 lanthanide EDTA complexes with the anions of 8-hydroxyquinoline-5-sulfonic acid, iminodiacetic acid and nitrilotriacetic acid were determined by pH-titrations and a direct calorimetric method. These thermodynamic data are discussed and compared with those for the formation of the Ln(III)EDTA complexes. Contrary to current opinion it is concluded that all trivalent lanthanide aquoions have the same coordination number in dilute solution. However, in the series of the lanthanide EDTA complexes the coordination number changes between Sm and Tb. In this region, equilibria occur between two types of EDTA complexes with different numbers of coordinated water molecules: The corresponding equilibrium constants could be evaluated. The coordination number changes also in many other Ln complexes along the lanthanide series, and similar equilibria occur.     

The chemistry of indole

The opening of the pyrazolidine ring at the nitrogen-nitrogen bond in 1-arylpyrazolidine under the influence of acidic agents which leads to the formation of N-(3-aminoalkyl)indoles is described. The method enables one to obtain indoles with branched aminoalkyl radicals.For part XIII see [1].     

l-Leucanthemit als Inhaltsstoff von Gymnospermae

Zusammenfassung Die Bildung und das Vorkommen von Cycliten inThuja occidentalis wurden mit Hilfe der Methode der Photoassimilation in einer Atmosphäre von¹⁴CO₂ untersucht. Nebenmyo-Inosit, Sequoyit,d-chiro-Inosit undd-Pinit wurde auchl-Leucanthemit (l-1,2,4/3-Cyclohexentetrol), ein Cyclit, der bisher nur als Inhaltsstoff mehrerer Angiospermae bekannt ist, nachgewiesen. Das Vorkommen vonl-Leucanthemit konnte auch inPinus austriaca sichergestellt werden. Methoden zur Isolierung vonl-Leucanthemit ausThuja occidentalis wurden ausgearbeitet.

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The formation and the occurrence of cyclitols inThuja occidentalis has been studied, using the method of photoassimilation in an atmosphere of¹⁴CO₂. Besidesmyo-inositol, sequoyitol,d-chiro-inositol, andd-pinitol, alsol-leucanthemitol (l-1,2,4/3-cyclohexentetrol), a cyclitol which so far has only been found in Angiospermae, was identified. The occurrence ofl-leucanthemitol could also be established inPinus austriaca. Methods have been elaborated which permit the isolation ofl-leucanthemitol fromThuja occidentalis.