Effects of structural transformations in magnetic emulsions

Structural transformations and relevant changes in the magnetic and optical properties of magnetosensitive emulsions based on magnetic fluids are experimentally studied. Peculiarities of the changes in the magnetic susceptibility of emulsions associated with the deformation of their microdroplets and the effect of phase inversion (the transformation of dispersions of magnetic droplets in nonmagnetic media into dispersions of nonmagnetic droplets in magnetic fluids) are established. Optical effects occurring in magnetic emulsions under the combined action of a shear flow and a magnetic field are studied. It is concluded that optically active composition media may be developed on the basis of magnetic fluids.     

New approach to synthesis of aromatic N-phenyl-substituted polyamides

It is shown that polyimidates obtained by polycondensation of bisphenols with imidoyl chlorides may be transformed into N-phenylsubstituted aromatic polyamides. The rearrangement occurs as a result of heating at 260–340°C, and, in a diphenyl ether solution, at 240°C. The resulting polymers are soluble in organic solvents and demonstrate high thermooxidative stability.     

Pars-Orbital-Methode (PO-MO), 2. Mitt.: Anwendung der Charakterordnungen aufDiels—Alder-Reaktionen

Zusammenfassung Die p-LokalisierungsenergieL _p nachBrown wird als Maß derDiels—Alder-Reaktivität in Beziehung gesetzt zu den Äthylen-, Butadien- und Benzol-Charakterordnungen . Bei Angriff an peripherencisoiden C₄-Einheiten des Moleküls fälltL _p erwartungsgemäß mit _dienoid und steigt mit den anderen Charakterordnungen. Werden innerhalb eines einzigen Benzolrings nur sekundäre C-Atome angegriffen, so steigtL _p mit allen Charakterordnungen, werden hingegen auch tertiäre C-Atome miterfaßt, fälltL _p mit allen Charakterordnungen. Dieser Hinweis auf wahrscheinliche Reaktionsmechanismen zeigt neuerlich die Signifikanz dieser Reaktionsindices.

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Brown's p-localization energy as a measure for theDiels—Alder-reactivity is correlated to ethylene-, butadiene- and benzene-character orders. If the molecule is attacked at periphericcisoidic C₄-units,L _p decreases with _dienoid and increases with the other 's, as expected. If in the reaction only secondary C-atoms of a single benzene ring are involved,L _p increases with all character orders, but if tertiary C-atoms are also involved,L _p decreases with the character orders. This hint of probable reaction mechanism shows once again the significance of these new indices of reactivity.

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Mit 4 Abbildungen

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Als 1. Mitt. zählen wir die in zitierte Arbeit.     

Synthesis and Heterocyclization of 3-Arylaminothiocrotonanilides

Reactions of acetylthioacetanilide with arylamines in acetic acid in the presence of sodium acetate give 3-arylaminothiocrotonanilides in good yields. When treated with -bromoacetophenone in acetone, these products are converted to substituted 4-hydroxy-²-thiazolinium bromides, one of which was dehydrated to obtain the corresponding thiazolium bromide. The structure of the heterocyclization products was confirmed by single crystal X-ray diffraction and NMR study of 2-acetonylidene-3,4-diphenyl-2,3-dihydrothiazole formed by dehydration of the corresponding ²-thiazolinium salt with simultaneous hydrolysis.     

Discontinuous-flow potentiometric determination of chloride in a large-volume wall-jet cell using an ion-selective electrode based on a silver chloride film chemically deposited on a silver iodide support

A robust and sensitive chloride ion-selective electrode can be prepared by modifying the surface of an iodide-selective electrode using the chemical reaction with mercuric chloride in an oxidizing medium containing excess chloride. A thin film of silver chloride is thus formed ensuring a rapid and reproducible response to chloride. The analytical parameters of this electrode are similar to those of commercial silver chloride ion-selective electrodes, but its electrical impedance and signal noise are substantially lower and the response somewhat faster. Its sensitivity toward surfactants is somewhat suppressed. The electrode was used for discontinuous flow potentiometric (DFP) determinations in a large-volume wall-jet cell in which the electrode surface can be continuously reactivated by a cleaning solution contained in the cell. The method was applied to determination of chloride in ground waters from an industrial waste dumping site. The limit of determination is low 9 mug Cl(-)/l (2.6 x 10(-7)M), the precision good (the relative standard deviation varies from 0.6 to 3.0% for chloride contents from 2.90 to 0.15 mg/l, respectively) and the method correlates satisfactorily with the results of an indirect AAS determination of chloride. The sample throughput is high-90 measurements can be carried out per hour, corresponding to 30-40 determinations per hour.     

Gas chromatographic analysis of bifunctional amines after derivatization with methyldichlorophosphine and sulfur

Summary A derivatization procedure for the gas chromatographic analysis of bifunctional amines likeβ-adrenergic blocking drugs is described. The method consists of a two-step reaction with methyldichlorophosphine and sulfur in presence of triethylamine to form cyclic methylphosphonothioic derivatives. The properties of these compounds are discussed and the application of the method to the quantitation of ephedrine in human body fluids is presented. Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984     

The cyclic fixation and reduction of molecular nitrogen with [WH4(Ph2PCH2CH2PPh2)2] in γ-irradiated solutions

Yields of NH₃ and N₂H₄ in radiation-catalytic reduction of N₂ by means of a hydride complex of W^IV with dppe in thf solution and in mixtures of thf with other solvents have been estimated. A mechanism proposed earlier of reduction of coordinated N₂ has been confirmed and the role of solvent in reduction of N₂ to NH₃ and amines has been explained.     

Beiträge zur Chemie des Hydrazins und seiner Derivate. XXXV. Darstellung und Eigenschaften neuer Stickstoff–Wasserstoff-Verbindungen von Barium und Strontium

On the chemistry of hydrazine and its derivatives. XXXV. Preparation and properties of new nitrogen-hydrogen compounds of barium and strontium By thermal decomposition of barium hydrazide, Ba(N₂H₂), and strontium hydrazide, Sr(N₂H₂), under decaline at about 190°C the compounds BaN_0.5H_0.4 resp. SrN_0.5H_0.4 were obtained. In order to characterize them chemical and spectroscopical investigations were carried out.     

M?glichkeiten und Grenzen der Identifizierung von Stoffen aus ihrem Verhalten bei der isothermen Eluierungsgaschromatographie

Zusammenfassung Es wird vorgeschlagen, für die Identifizierung von Stoffen Verteilungskoeffizienten zu verwenden und diese mit Hilfe der GLC in einem einfachen Verfahren, das auch die Kontrolle der Meßbedingungen erlaubt, zu bestmimen. Dieser Vorschlag kombiniert ein relatives Meßverfahren mit der Bestimmung absoluter Größen. Der Meßgenauigkeit, die für die Identifizierung von entscheidender Bedeutung ist, wurde besondere Aufmerksamkeit gewidmet und dabei herausgestellt, daß sie im allgemeinen durch die Trennleistung der Säule begrenzt wird. Für die Auswertung der Ergebnisse bei der Verwendung von Säulen mit verschiedenen stationären Phasen wurde ein Verfahren erprobt, bei dem die an den verschiedenen Säulen gemessenen Verteilungskoeffizienten miteinander kombiniert werden. Es wurde eine Tabelle der Verteilungskoeffizienten von etwa 80 Kohlenwasserstoffen bei 50,0° C mit Squalan und Dinonylphthalat als stationären Flüssigkeiten angefertigt. An Hand dieser Tabelle wurde die Identifizierung der C₅–C₇-Kohlenwasserstoffe eines Crackproduktes durchgeführt.

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Summary It is recommended to use partition coefficients for the identification of compounds and to determine these by a simple gas-chromatographic procedure, which allows the control of the measuring conditions.This recommendation combines a relative method of measurement with the determination of absolute quantities. The accuracy of the measurement, which is decisive for the identification, was investigated and it was found that the accuracy in most cases will be limited by the resolving power of the column. For the evaluation of the results obtained with columns with different stationary phases a method was tested in which the partition coefficients measured on two different columns were combined. A table of partition coefficients of 80 hydrocarbons at 50,0° C on squalane and dinonylphthalate as stationary phases was compiled. On the basis of this table the identification of the C₅-C₇ hydrocarbons in a crack product was carried out.