Spektroskopische Untersuchungen an 4-Nitrophenylhydrazonen sekundärer und tertiärer α-Ketocarbonsäureamide

Spectroscopic Studies on 4-Nitrophenylhydrazones of Secondary and Tertiary α-Ketoamides 4-Nitrophenylhydrazones of secondary and tertiary α-ketoamides both exist in two stable isomeric forms (E/Z) with respect to the position of the substituents at the CN-Bond. But whereas the Z-form of the secondary amides can be easily assigned by means of intramolecular hydrogen bond, this criterion in case of most the derivatives of tertiary amides fails. As shown by derivatives of glyoxylic acid this deviation is evidently caused by steric facts due to the double substituted amide group and the alkyl residue on the α-C-atom.     

Darstellung,Struktur und Reaktivität quartärer Ammoniumcellulosate

Tetraalkylammonium cellulosates were prepared by means of an exchange reaction between cellulose and tetraalkylammonium methoxides in anhydrous methanol and dimethylsulfoxide up to a degree of substitution of about 0,7 without chain degradation. The course of this reaction and the structure of the cellulosates in comparison to lithium and sodium cellulosate has been studied. The reaction rate and the equilibrium substitution decreased with increasing size of the cation in the methoxide. The distribution of the alcoholate groups in equilibrium at C-2, C-3 and C-6 of the glucopyranosyl unit in the cellulosates, which was investigated by methylation, hydrolysis of the methylcelluloses, and analysis of the methylglucoses by gas chromatography, was independent of the nature of the cation. Under the given reaction conditions the hydroxyl group at C-2 was more acidic than those at C-3 and C-6, while for the latter practically no difference was found. The tetraalkylammonium cellulosates are highly reactive intermediates for the preparation of cellulose derivatives. The reactivity of the cellulosates increased with increasing size of the cation, Li^⊕ < Na^⊕ < N(CH₃)₄^⊕ <[(CH₃)₃N? CH₂? C₆H₅]^⊕.     

Konfigurationsbestimmung von Steroiden mit Primärer und sekundärer Aminogruppe durch Messung des Circulardichroismus der Kupfer-Succinimidat-Komplexe

Configurational Assignment of Steroids with Primary and Secondary Amino Groups by CD Measurements of the Copper Succinimidate complexes The CD spectra of the copper succinimidate complexes of 9 different steroids with a primary and 3 steroids with a secondary amino group were investigated. A good correlation between the sign of the Cotton effects in visible range and the chirality of the immediate neighbourhood of the nitrogen atom was observed. The results obey the earlier established octant rule for this chromophor.     

Zur antibakteriellen und antimykotischen Wirkung quaternärer Ammoniumverbindungen

Antibacterial and Antimycotic Action of Quaternary Ammonium Compounds The minimum inhibiting concentration of various quaternary ammonium compounds on dermatologically relevant microbes is reported. The surfactants tested are especially suited against S. aureus, S. pyogenes, and, to a lesser extent against C. albicans. They are less active against P. aeruginosa and dermatophytes. These studies are complemented by examination of the liberation of an active quaternary ammonium compound from two different donor phases in various acceptor phases. Since in pyoderma and C. albicans infections the aqueous acceptor phase predominates, differentiated statements can be made on the usefulness of various externa bases.     

Modell zur beschreibung der glasübergangstemperaturen binärer und ternärer mischungen von poly(styrol-co-n-butylmethacrylat)en

Glass transition temperatures of binary and ternary blends of chemically uniform poly(styrene-co-n-butyl methacrylate)s with a mean content of 30.8 wt.-% of n-butyl methacrylate and number-average molar masses in the range of 4900 and 67000 g/mol have been investigated in relation to their composition. The blends showed significant deviations from an ideal behaviour with reference to a linearity between glass transition temperature and composition. This phenomenon is described by a mathematical model where polynoms are particularly well suited to represent the glass transition temperatures of the blends, partly exceeding those of the pure components. Finally, various reasons of these deviations were discussed. Here, energetical interactions seem to be of considerable importance combined with a nonadditivity of volumes.     

Teilkondensation und nichtadiabate Rektifikation binärer Gemische in Füllkörperrohren

Partial condensation and non-adiabatic rectification of binary mixtures in packed columns. Vertical tube assemblies are preferred for partial condensation of vapour mixtures. The mixture of vapours is fed through the tubes in countercurrent flow to the falling condensate, while coolant flows through the jacket. Only with very large ratios of length L to diameter d of the tubes, i.e. L/d 200, does the separatory effect of partial condensation, owing to rectification mass transfer between the phases, exceed the enrichment effect of partial condensation. Use of ring-shaped packings drastically reduces the characteristic diameter, so that the additional separatory effect occurs at relatively short tube lengths. In the present paper, experimental results concerning the separation efficiency of tubes packed with Raschig rings for non-adiabatic rectification and partial condensation of the “negative” binary mixture n-heptane/benzene are reported and evaluated with the aid of the extended two-film theory. It is found that the resistance to mass transfer averaged over the length of the tube lies entirely on the liquid side on non-adiabatic rectification. Correlation of the Sherwood number of the condensate taken over the length of the tube and the condensate loading clearly shows that the usual calculation of partial condensation with average total mass transfer coefficients does not give physically meaningful results in the case of liquid-side resistance to transport. Calculating procedures which account for the variation of the partial mass transfer coefficients along the tube should lead to improved evaluation or prediction of separation efficiency.     

Phasengleichgewichte binärer Kohlenwasserstoff-Gemische

Phase equilibria of binary mixtures of hydrocarbons . Seven methods for the calculation of phase equilibria of binary mixtures from vapour pressure data have been programmed. Results of computations for hydrocarbon mixtures are discussed, using just one regression method and six iteration procedures based on the Gibbs-Duhem equation. The iteration methods use the approximation of experimental vapour pressure data, e. g. by means of cubic splines or orthogonal polynomials. The practical application of the results, e.g. for the simulation of separation columns, requires the regression of the vapour mole fractions following the iterative solution of the Gibbs-Duhem equation.