Fast formation of aromatic cations in cyclohexane observed by pulse radiolysis

The fast formation of cations of benzophenone, biphenyl, naphthalene, anthracene and phenanthrene in liquid cyclohexane was studied by nanosecond pulse radiolysis. Rate constants between 2.3 × 10¹⁰ M^?1 s^?1 (for naphthalene) and not below 2.5 × 10¹² M^?1 s^?1 (for benzophenone) were derived and compared with the corresponding rate constants for anion formation.     

Influence of cyclodextrins on nitrosation of drugs

The World Health Organization issued a nitrosation procedure (NAP Test) which allows to carry out nitrosation under standard conditions. It has proved that the in vitro reaction rates of the fast nitrosatable drugs piperazine, cimetidine and ethambutol are not influenced by -, - and -cyclodextrin. On the contrary, -, -cyclodextrin and heptakis-2,6-di-O-methyl--cyclodextrin enhance the nitrosation of the slower nitrosatable 1-ephedrine and fencamfamine significantly. This possible reaction must be considered if nitrosatable drugs are formulated with cyclodextrins to be administered to human beings.     

In vitro nitrosation of ephedrine in the presence of cyclodextrins

-, and -cyclodextrin and heptakis-2,6-di-O-methyl--cyclodextrin enhance the nitrosation rate of l-ephedrine if the nitrosation assay procedure (NAP test) is applied. During this reaction with -cyclodextrin a solid inclusion compound of -cyclodextrin andN-nitrosoephedrine precipitates. Solubilities and stabilities of inclusion compounds of the cyclodextrins with ephedrine and nitrosoephedrine, respectively, explain especially the catalytic effects of some cyclodextrins on ephedrine.Part of the PhD thesis of V. Wedelich, Freie Universität Berlin, 1985.     

Preparation, characterization and thermolysis of metal nitrate complexes with 4,4’-bipyridine

Two bis(bipyridine) polymeric metal nitrate complexes with 4,4’-bipyridine of simple formula like [M(bipy)₂](NO₃)2⋅xH₂O (where M=Co, Ni and Cu; x=4, 2 and 0, respectively) have been prepared and characterized. Their thermal decomposition has been undertaken using simultaneous TG-DTG-DTA and DSC in nitrogen atmosphere and non-isothermal TG in air atmosphere. Isothermal TG has been performed at decomposition temperature range of the complexes to evaluate the kinetics of decomposition by applying model-fitting as well as isoconversional method. Possible mechanistic pathways have also been proposed for the thermolysis. Ignition delay measurements have been carried out to investigate the response of these complexes under the condition of rapid heating.     

Supported ionic liquid catalysis investigated for hydrogenation reactions

The concept of supported ionic liquid catalysis (silc) has successfully been applied to hydrogenation reactions, which significantly reduced the required amounts of ionic liquid phase and enabled the usage of fixed-bed technology; the resulting catalysts exhibited high activity and outstanding stability.     

Verzweigungsreaktionen bei der Vinylacetat-Polymerisation

Zusammenfassung Bei der Untersuchung der Langketten-Verzweigungsreaktionen wurde für die photosensibilisierte Substanzpolymerisation von Vinylacetat festgestellt, da? mit abnehmendem Polymerisationsgrad zunehmend C-C-Hauptketten-Verzweigungen gebildet werden. Es wird gezeigt, da? diese nicht durch Verseilung abbaubaren Verzweigungen in einer Reaktionsfolge entstehen, die mit Disproportionierungsabbruch beginnt und sich in einer Wachstumsreaktion zwischen zwei Polymerpartikeln fortsetzt. Auf die allgemeine Bedeutung dieser Hauptketten-Verzweigung wird hingewiesen.

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Summary In this paper long chain branching reactions occurring in the photosensitized bulk polymerization of vinyl acetate have been examined. The number of C-C branching points is increased by decreasing the degree of polymerization. These branching points-which cannot be hydrolized-were formed in reactions between growing polymer radicals and polymer molecules showing a terminal double bond resulting from a termination reaction by disproportionation.

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Meinem hochverehrten Lehrer, Herrn Prof. Dr. Dr. h. c.Franz Patat, danke ich für stets f?rdernde Unterstützung.     

A Raman technique applicable for the analysis of the working principle of promoters and inhibitors of gas hydrate formation

We report a Raman technique applicable for the in situ analysis of the development of hydrogen bonds in the liquid water‐rich phase just before the onset of gas hydrate formation. Herewith, the phase transition as well as the working principle of hydrate formation inhibitors and promoters can be analyzed. © 2015 The Authors. Journal of Raman Spectroscopy published by John Wiley & Sons Ltd.     

Nachweis verschiedener Strukturen bei Poly-Butenon-Leiterpolymeren

Ohne ZusammenfassungUnserem hochverehrten Lehrer, Herrn Prof. Dr. Dr. h. c.Franz Patat, zum 65. Geburtstag gewidmet.     

Untersuchungen zur Kationenbindung an hydrolytisch abgebauten Cellulosepulvern

Ohne Zusammenfassung