Die Darstellung von Gelen als stationäre Phase für die Gelchromatographie

The influence of the mode of synthesis on the characteristics of crosslinked polymers is examined for crosslinked copolymers of ethylvinylbenzol/divinylbenzol and vinylacetate/divinyladipate. Homogeneously crosslinked gels are mostly suited for separation of oligomers; polymers are able to be separated by use of heterogeneously crosslinked gels. It is demonstrated that in case of a heterogeneously crosslinking polymerization the heterogenity of the copolymers with decreasing solvatizing ability of the inert component is increasing; this leads simultaneously to an increase of the excluded molecular weight.     

α-Ketoimidgruppierungen als eine der ursachen für die lumineszenz thermooxidativ geschädigten polycaprolactams

The present paper is concerned with the origin of luminescence in thermo-oxidativ damaged polycaprolactame. It is demonstrated that the luminescence of a substance isolated from the damaged polycaprolactame is caused by an α-ketoimid-structure element linked as a lumophoric group to the backbone of the polymer. A mechanism for the oxidation leading to this structure element is discussed on basis of the caprolactame oxidation.     

Stationäre Chemische Energieumwandlung als Herausforderungen für den Verfahrensingenieur

Meeting future energy demands with more efficient, lower emission, and safe energy technologies has top priority in the medium term. Consumer-friendly energy concepts, integrated into regional and supraregional energy supply structures, represent further elements. These will make important contributions to resource-conserving and environmentally compatible power supplies utilizing local energy sources including renewable resources. Supplying energy to large areas involves additional tasks, from compensation of large amounts of fluctuating energy to the transport of fluctuating energy to the transport of renewable energy over long distances. Solar dish, parabolic section, and tower power generating plant have considerable economic and CO₂-reduction potential in sunny countries, such as in the Mediterranean region, However, the costs of solar-thermal electricity generation have to be reduced by a factor of 1.5 to 2. Fuel cell systems can attain particular significance as efficient low-emission energy conversion systems in power plant and automative engineering once their technical and economic potential can be realized.     

Photochemische Untersuchungen von Vitamin B12-Modellverbindungen mit Azid bzw. Thiolat als Axialliganden – Precursorverbindungen für koordinativ ungesättigte Cobalt(II)-Komplexe

Photochemistry of Azido and Thiolato Vitamin-B₁₂ Model Complexes as Precursor Compounds for Coordinatively Unsaturated Cobalt(II) Complexes The photolysis of [LCo(chelat)B] complexes ( 1–3 ) (L = azide, N; thiolate, RS⁻; chelat = dimethylglyoxime, dmg; N,N′-o-phenylene-bis(salicylidenimine), salphen; N,N′-ethylene-bis(salicylidenimine), salen; B = pyridine, imidazole, triphenylphosphine) leads upon the homolytic cleavage of the Co L bond to both coordinatively unsaturated reactive cobalt(II) chelates [Co(chelat)B] and ligand radicals L^•. The efficiency of these photochemical redox reactions is described in relation to the structure of the cobalt(III) chelates, the wavelength of irradiation, the light-intensity as well as the solvents and substrates used during the photochemical experiments. Further, sensitization experiments using [Ru(bipy)₃]Cl₂ as sensitizer are described and the redox potentials of the investigated complexes are discussed.     

Eine η-c-M-beziehung für polymerlösungen

A simple equation is developed for the dependence of the viscosity upon molecular weight and concentration of polymer solutions. The validity of such a simple equation is given if the plot of log η_sp = f (log (c · [η])) is a straight curve for all viscosity values. This is demonstrated for aqueous polyacrylamide solutions. The covered region is M = 12300-6900 000 (g/mol) and concentrations c = 0,1?5 (g/100cm³). The established η-M-c-relationship is:      

Fettalkoholethersulfonate für die tertiäre Erdölförderung

Ether Sulfonates in Enhanced Oil Recovery Synthesis and application possibilities of ether sulfonates in enhanced oil recovery are described. The products investigated showed high stability in weakly acidic solutions at 180°C with half lives of 400–600 days. Higher ethoxylated products are soluble even in higher concentrated brines. Foaming ability is similar to that of the analogous ether sulfates. For some special types, interesting phase behaviour with a wide micro-emulsion range was found.     

Verfahrensingenieure für das 21. Jahrhundert – Herausforderungen für die Hochschulausbildung

Chemical Engineers for the 21st Century – A Challenge to University Education The education of chemical engineers at the dawn of the 21st Century faces enormous challenges. The number of new students has dropped significantly since early 1990s. Globalisation is having an effect on the working environment of the engineering profession and changing the job market for process engineers whose activities now extend far beyond the chemical industry. As a result, universities and engineering schools now face increasing competition for students and scientific staff and for retention of degree programs and departments. This article throws light on the current situation of the universities, changes in working environment and conditions, and the demands placed on future chemical engineers and their education. Whatever changes may occur, e.g. through the introduction of Bachelor and Master degrees, the characteristic and proven profiles of engineering school and university training must be maintained while enhancing the conditions for good graduates.     

Nucleophile Substitutionen an Bischlornitrosoverbindungen. IV. Sulfonylaminooxime als Extraktionsmittel für Kupfer(II)

Nucleophilic Substitutions with Bischloronitroso Compounds. IV. Sulfonylaminooximes as Extracting Agents for Copper(II) New vicinal sulfonylaminooximes 5a–5v are synthesized from bischloronitroso compounds 1 or 2-chlorooximes 2 and sulfonamides 4 under alkaline conditions. In several cases oligomeric products 6 result instead of 5 . 2-Sulfonylaminobenzophenoneoximes 8a–g are also prepared from 2-aminobenzophenones and sulfonyl chlorides and subsequent reaction with hydroxylamine. The pH_0,5 values for the extraction of copper-(II)-ions into a chloroformic solution are between 2,8 and 4. Compounds 8 are comparably weaker extragents then oximes 5 .     

Chloro-nitrosyl-molybdän-Komplexe als Epoxidationskatalysatoren. II. Epoxidringöffnungs-inaktive Katalysatoren

Chloro-nitrosyl Molybdenum Complexes as Epoxidation Catalysts. II. Catalysts Inactive in Epoxide Ring-opening Reaction Chloro-nitrosyl molybdenum complexes which are active in the epoxidation reaction do not catalyze the consecutive epoxide ring-opening reaction if the coordinated ligand can form a strong transition metal-ligand bond. The temperature of the cleavage of the ligand from the central atom obtained by derivatographic measurements characterizes the strength of this bond. The epoxide ring-opening activity can be demonstrated by the initial reaction rate, by the conversion of the initial epoxide and by the yield of the ring-opening products 1 and 2 obtained in the reaction of 1, 2-epoxyoctane with ethanol in chlorobenzene at 100°C. High temperatures of ligand cleavage correspond with low conversions of the initial epoxide, low initial reaction rate and a low ratio of the isomers 2/1 .     

Quaternäre Metall/Metalloxid‐Katalysatoren als Wandkatalysatoren in Mikroreaktoren für Power‐to‐Gas‐Applikationen mittels kombinatorischer Hochdurchsatzmethoden

Catalysts of quaternary composition have been prepared and tested for the Sabatier process. For catalyst syntheses the following techniques have been used: sol‐gel methods, wet impregnation and incipient wetness impregnation. The Sabatier reaction was carried out at temperatures between 520 K and 670 K, pressures of 15 bar and 30 bar using a mixture H₂:CO₂ of 4:1. Activity screening of the microscale wall catalysts was performed by a custom‐built 10‐fold parallel gas‐flow microreactor setup in sequential operating mode. To analyze the gas phase compositions GC‐FID was used.     

Wege zum Informationsmanagement für interdisziplinäre Forschungsprojekte und die Entwicklung eines prototypischen Systems

New Ways to Information Management for Interdisciplinary Research Projects and the Development of Prototypic Systems Many interdisciplinary research projects lie at the basis of valuable information resources in the form of measured and calculated data, reports, publication, etc. These resources, however, can usually not be used over extended periods of time as they are bound to specific software, or because specific information, such as data sources or calculation principles, is missing. A partial solution to this problem could come in the form of a platform‐independent archiving of scientific information. The XML format, which was originally developed for internet data, including the extensions for the scientific area, could be useful here. The second part of the problem can be solved by the integration and networking of information resources. This can be achieved in various ways, some of which are described here to provide a framework for the documentation of interdisciplinary research projects.     

Der „Nornialisierungsfaktor”︁ für die Toinatenmutante chloronerva. XV. Peptidanaloga des Phytosiderophors Nicotianamin

The “Normalizing Factor” for the Tomato Mutant chloronerva. XV. Peptide Analogues of the Phytosiderophore Nicotianamine Some peptide analogues of the phytosiderophore nicotianamine, (2 S , 3′ S , 3″ S )- N -[3-(3-amino-3-carboxypropylamino)-3-carboxypropyl]-azetidine-2-carboxylic acid, have been synthesized from protected amino acids by the EEDQ or the DCC method. They exhibited no biological effect with regard to the phenotypical normalization of the tomato mutant chloronerva.     

Physikalische Methoden als Hilfe für die Herstellung und Entwicklung von Tensiden II: Mikroskopische Untersuchungen

The Use of Physical Methods in the Manufacture and Development of Surfactants II: Microscope Examinations When surfactants are used, high surfactant concentrations, which often have liquid crystal properties, can easily form on the active surfaces. Knowledge of the range of existence and the structure of such anisotropic surfactant solutions or gels may be of vital importance for the manufacture and development of new surfactants. With the aid of polarization microscopy it is possible to make these liquid crystal structures visible. Pentadecyl and dodecyl benzene sulphonic acids are mixed with water and photomicrographs are made of the structures which form. A melting-point diagram is drawn up to determine the composition of the hydrate complexes which form between the surfactant and the water. The interference figures of the occurring phases are determined as far as possible and this in turn provides information on the structure of the liquid crystals. The structure of the occurring phases is discussed on the basis of the R-theory.