Über die Reproduzierbarkeit der turbidimetrischen Bestimmung von Phosphorspuren mit Strychninmolybdostickstoff(V)säure

Microchimica Acta - Mit der turbidimetrischen Strychninnitrat-Methode für Phosphorspurenbestimmung nach der Version von Hegedüs und Dvorszky kann man nur dann ausgezeichnete...     

Thermoanalytische untersuchung von sekundärem calciumphosphatdihydrat

The thermal excitation of artificial brushite in dried air and normal atmosphere generates the following reactions:

We could not register the monotropic γ→β and β→χ transformations by DTA. At low p_H2O values unstable inordinate intermediates are formed until the exothermic transformation, at high p_H2O value and in water a stable, secondary hydrogen phosphate of ordinate crystal lattice and γ-pyrophosphate originate. The amorphous intermediate compounds are pseudomorphous with the initial brushite. The lack of H₂O hinders, whereas the excess of H₂O promotes the formation of nuclei and crystallization of monetite and as a result of this its thermal existence region is expanded. Accordingly, during the dehydratation process in dry air the decrease of the     

Mass spectrometric studies on azidomorphine derivatives

The mass spectrometric behaviour of nine azidomorphine derivatives have been studied. These compounds proved to have surprisingly specific and selective fragmentation under electron-impact. For 6-deoxy-6-azido-dihydro-isomorphine derivatives (I to V) the main decomposition pathway involves the loss of an N₂ molecule followed by a very rapid and selective fragmentation process. On the other hand, the molecular ions of 6-deoxy-8-azido-pseudomorphine derivatives (VI to VIII) and 6-deoxy-6-azido-14-hydroxy-isocodein (IX) primarily decompose by loss of the N₃ radical. This is due to the allylic effect of the double bond in ring C, corresponding to the chemical behaviour of these compounds.     

Gel permeation chromatography with mixed eluents: Polymer solution as mobile phase

The GPC elution behaviour of a polymer was studied when a solution of another polymer in a liquid was used as an eluent. In ternary systems containing two polymers, GPC results are influenced by the thermodynamics of polymer incompatibility. The incompatibility manifests itself both in the slope of the dependence of elution volume upon the concentration of injected polymer and in the shift of elution volumes extrapolated to zero concentration. Experimental data for systems containing poly(styrene) and poly(methyl methacrylate) have been accounted for qualitatively by theoretical views on coil shrinkage resulting from polymer incompatibility. The concentration effects of the injected polymer and the polymer in the mobile phase on elution volume are compared; further parameters affecting the separation in the systems with polymer solution as eluent are discussed.     

Thermometric determination and analytical application of the landolt effect

The thermometric determination of the Landolt effect applied to the hydrogen peroxide—iodide—ascorbic acid reaction is described. The appropriate kinetic equations are used to interpret the thermometric curve and the calibration curve of the indicator reaction catalysed by molybdenum. The effects of the iodide, hydrogen peroxide, and hydrogen ion concentrations on the shape of the thermometric curves are discussed. This thermometric method can be used to determine micro amounts of iron, zirconium, thorium, vanadium, molybdenum and tungsten, with satisfactory accuracy and precision.     

Magnesium-butadiene addition compounds: Isolation,structural analysis and chemical reactivity

The magnesium-butadiene 1 : 1 (1), 1 : 2 (II) and 1 : 3 addition compounds obtained by the direct metalation of butadiene with metallic magnesium were isolated. These compounds have a polymeric structure. Structural analysis of these compounds by NMR and IR methods was carried out. The process for the formation of II via I and III via II was investigated. The results of protolysis and alkylation of the above magnesium compounds corresponded well to those of crotylmagnesium compounds.     

Some properties of poly-α-piperidone

The high molecular weight polymer of α-piperidone, which had been unobtainable with the use of alkali metal, trialkyl aluminum, or Grignard reagent as catalyst, was prepared with M–AlEt₃, (where M is alkali metal), MAlEt₄ or KAlEt₃ (piperidone) as catalyst and N-acyl-α-piperidone as initiator. From the determination of the behavior of the solution viscosity of poly-α-piperidone in m-cresol at 30°C. the value of 0.27 for the Huggins constant was obtained. Examination of the correlation between the number-average molecular weight, determined by endgroup titration, and the intrinsic viscosity gave a somewhat small value for the endgroup COOH. This may be considered due to the consumption of N-acyl-α-piperidone by a propagating polymer in the course of polymerization. The thermal stabilities of the polyamides, nylons 4, 5, and 6, was in the order nylons 6 > 5 > 4 according to differential thermal and thermogravimetric analyses, Poly-α-piperidone, which has a reduced viscosity of 0.7, shows a melting point of 270°C.. which was expected from the zigzag pattern of the correlation between melting points and numbers of CH₂ groups for polyamino-acid polymers.     

Reconocimiento de nicotina en una hebrita de tabaco

Summary Adaption of theLuís method for the detection of nicotine to microscale, usingEmich's capillary technic proved successful, attaining identification limit of 0,03g.Applying a sub-micro steam distillation effect, the nicotine in a speck of tobacco (1 mm² and less) could still be detected by using the above reaction.Extension of the above procedure to mixtures of nicotine with substances not volatile with steam, inorganic (halides) as well as organic compounds (other alkaloids, acids, etc.) proved to be successful, even when the nicotine is present in proportions of only 1 part in 1000.

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Zusammenfassung Die Anwendung der Kapillartechnik vonEmich zum Nachweis von Nikotin nachLuís war erfolgreich und zeigte eine Erfassungsgrenze von 0,03g.Bei Anwendung einer Ultramikrodampfdestillation kann das Nikotin nach obiger Methode noch in Spuren von Tabak (1 mm² und weniger) nachgewiesen werden.Die Reaktion ist auch positiv bei Gemischen von Nikotin mit anderen, mit Wasserdampf nicht flüchtigen sowohl anorganischen (Halogenide) als auch organischen Substanzen (andere Alkaloide, Säuren etc.), selbst dann noch, wenn das Nikotin bloß im Verhältnis von 11000 vorhanden ist.

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Résumé La technique capillaire d'Emich a été utilisée avec succès pour identifier la nicotine suivant le procédé deLuís; la limite de sensibilité est alors de 0,03g. La mise en oeuvre d'un ultramicroentraînement à la vapeur permet en outre, par application de la précédente méthode, d'identifier la nicotine dans des traces de tabac (moins de 1 mm²). La réaction est également positive en présence d'autres substances non entraînables par la vapeur d'eau, qu'elles soient minérales (halogénures) ou organiques (autres alcaloïdes, acides, etc. ...) même si la proportion de nicotine n'est que de l'ordre de grandeur de 1/1000.

     

Al(Cap)3 as initiator in the anionic polymerization of ε-caprolactam at high temperature

Mechanism for polymerization of ε-caprolactam in the presence of both sodium and aluminum caprolactamate was investigated at 171°C. The role of Al(Cap)₃ as an initiator was revealed. The apparent rate constant of propagation reaction decreased with the increase in the concentration of Al(Cap)₃, as the two different metal salts interact even at 171°C. The activation energy of the overall polymerization reaction with this catalyst system was estimated to be 41.18 kcal/mole.