bluuebunny/crossref_metadata_2025_split huggingface dataset:
Die Isolierung des Fluors vor 100 Jahrenendlich erreichtes Ziel und neuer Anfang
Authors: Links Dietmar 
Published: September 2010

AbstractAfter a brief mention of the early attempts to isolate fluorine the present paper in predominantly concerned with the description of the successful Moissan experiments. Some illustrations showing the historical equipment developed by Moissan are indicative of the high accuracy characteristic for his preparation technique.To afford an example for the international appreciation of the work done by Moissan: He was awarded the first Hofmann Prize in 1903 by the German Chemical Society. In a table are summarized also some other important data of his course of life.
Modelle molekularer Kraftfelder und ihre Anwendung in der Schwingungsspektroskopie
Authors: Böhlig Heinz , Geidel Ekkehard , Geiseler Gerhard 
Published: September 2010

AbstractThe concepts hitherto existing on the nature of intramolecular force fields and their physical background are presented. A short characterization of the individual force fields is followed by the description of possibilities for their application in vibrational spectroscopy. In addition to some traditional applications particularly new areas of application are outlined resulting from our present knowledge with regard to transferable force fields on the one hand and from the increasing combination of conventional and quantum chemical methods on the other. From the authors' point of view possible developments of the subject are mentioned.
Chemie der 3‐Amino‐thioacrylsäureamide; Synthesen und Eigenschaften
Authors: Liebscher Jürgen , Knoll Alexander , Abegaz Berhanu 
Published: September 2010

AbstractCompounds possessing 3‐aminothioacrylamide structures have gained great interest in synthetic organic chemistry. In the present report the methods employed to synthesize 3‐aminothioacrylamides are reviewed. The classification is in accordance with the bond which is formed in the final step of the reaction sequence. A short summary of typical physical and spectroscopic properties of 3‐aminothioacrylamides is included. The wide application of 3‐aminothioacrylamides as building blocks in the synthesis of openchained and especially heterocyclic compounds will be reviewed in a separate publication.
Methanol als Substrat für biotechnische Prozesse
Authors: Babel Wolfgang 
Published: September 2010

AbstractMethanol is one of the most attractive feedstocks for chemical industry. Since methanol is completely miscible with water, is easy to store, to transport and to handle, and a wide variety of microorganisms is capable of growing on methanol as the sole or major source of carbon and energy in an inexpensive synthetic medium methanol has also become attractive for the synthesis of single cell protein (SCP) and commercially useful products.In many countries methanol assimilating microorganisms are being studied and their potential utility in biotechnological processes is explored. At present, commercial processes involving methylotrophs are limited to the production of SCP and coenzyme Q. In this review it is demonstrated that methylotrophs are suitable for syntheses of amino acids, poly‐β‐hydroxy butyric acid, enzymes and vitamins, on the one hand, and that we are far from knowing all possible applications, on the other. It gives an outline of the fundamental problems in both the SCP and overflow productions and the prospects for improving existing processes and developing novel products by means of already known organisms and new strains.
Atmosphärische Chemie — Aufgaben, Methoden und Ergebnisse
Authors: Möller Detlev , Rolle Wolfgang 
Published: September 2010

AbstractThe aim of atmospheric chemistry is to describe the chemical structure of the atmosphere and its dynamical behaviour. Atmospheric fluxes are the most important link within the biogeochemical cycles. The estimation of natural and man‐made related contributions to the atmospheric budget is of special interest. Owing to the biological, chemical and physical characteristics of different processes of emission reaction and distribution it is necessary to evaluate an interdisciplinary approach.In this paper is given a short overview on different experimental and theoretical studies of chemical processes in the atmosphere. The present knowledge of the atmospheric chemistry of radicals, sulphur and nitrogen compounds as well as some selected hydrocarbon is shown.
Modelle zur quantitativen Beschreibung der Inhibition einfacher Elektrodenreaktionen durch Tensidadsorptionsschichten
Authors: Dörfler Hans‐Dieter , Emons Hendrik 
Published: September 2010

AbstractBased on the theory of the absolute reaction rates and surface thermodynamics, various models describing the inhibition phenomena of simple electrode reactions by neutral surfactants at the mercury/solution interface have been discussed. These models are valid for high surface coverage (0 ≈︁ 1) and were derived under the assumption that the activated complex has the same structure at the solvent covered and at the inhibitior covered interface. The results of these models are not in agreement with experimental observations by do polarography and adsorption studies. For that reason a new model was proposed under the assumption that the activated complex is created by a surface reaction between reactant and surfactant. The comparison of the results obtained by calculations using this model with our experimental investigations shows that the different log kapp/log cA‐plots or log kapp/π‐plots (kapp: rate constant; cA: concentration of surfactant in bulk; π: surface pressure) are in a good agreement with calculations using our inhibition model. This refers to the conclusion that the models, which have been proposed in the literature are only special cases of our generalized model.
Die infrarotspektroskopische Charakterisierung von Braunsteinen
Authors: Steger Walter Eberhard , Zichner Kerstin , Lunkwitz Renate 
Published: September 2010

AbstractThe modifications and less defined types of manganese dioxide are considered in progressing form simple to more complex infrared spectra. The i.r. characteristic of ϵ‐MnO2 is a broad absorption from 900 to 360 cm−1. Recrystallization produces the double maximum band of tetragonal β‐MnO2 (polianit). The i.r. spectra from this modification are clearly different from those of orthorhombic β‐MnO2. Formation from and decomposition to Mn2O3 of β‐MnO2 are also studied by i.r. spectroscopy. For the recognition of γ‐MnO2 it will often be necessary to take spectra also after recrystallization of the sample by heat‐treatment.
Elektromigration von γ‐Radionukliden in homogenen wäßrigen Elektrolyten ohne Zusatz stabilisierender Träger
Authors: Rösch Frank , Chalkin Vladimir Alekseevič , Milanov Milko , Hung Tran Kim , Dreyer Rolf 
Published: September 2010

AbstractThe present paper give the results of tests of a special electromigration technique for the analysis of equilibrium reactions in aqueous solutions. By use the electromigration behaviour of ß‐radionuclids at ultramicroconcentrations (205,206Bi, 169Yb, 140La) can be determine hydrolysis constants and complex‐formation constants. The results are compared with results of other analytic methods. The application of this special method for electromigration measurements is discussed.
Elektronentransfer‐Kettenreaktionen in der Chemie; Organische Radikale mit Elektronendonoreigenschaften als Kettenträger: SRH1 (AH·)‐, SRH1 (A−·)‐ und SRZ1‐Kettenreaktionen
Authors: Eggert Lutz , Kuz'min Michail Georgievič , Ivanov Vladimir Leonidovič 
Published: September 2010

AbstractIn this paper a novel classification of chain reactions, in which participate radicals, having properties of electron donors and playing the role of chain carriers by electron transfer is offered. The reactions discussed are distinguished from classical, that means radical, chain reactions, since electron transfer processes play a decisive role in their mechanism. Three groups of chain reactions, including various types of electrondonor radicals, are turned out on the basis of a number of literature examples. In case of SRH1 (AH·)‐reactions AH· radicals, generated from a hydrogen‐atomdonor AH2, act as an electrondonor. More powerful electron‐donors than AH· are A· anion radicals in SRH1(A·)‐reactions. In SRZ1‐reactions arise radical adducts, bearing electron donor properties. In this review are also discussed some proposals for the further development of the studied chain reactions.
Biomesogene
Authors: Hoffmann Siegfried 
Published: September 2010

AbstractBiomesogens evolved as an early amphiphilic pattern from the interface dialectics between order and disorder on the primordial earth. Their molecular designs provided decisive prerequisites for the projection of individual molecular facilities into the structural and functional amplifications of cooperative and dynamic mesogen domain ensembles. By directional nonlinear dynamizations, they arrived at a state of recognition and responsiveness. Competing individualizations forwarded autocatalytic propagations and information processings.The mesogenic order‐disorder patterns gained consciousness by reality adaptation. Experiencing optimization strategies, they developed creativity. They will succeed, however, only in living responsibility.
Zum isolobalen Modell in der elementorganischen Chemie
Authors: Krause Hans‐Joachim 
Published: September 2010

AbstractThe present paper tries to give a survey of the isolobal model in the elementorganic chemistry. The term “isolobal” was introduced by R. Hoffmann in 1976, but the concept of the electronic relationships or electronic resemblance is older. To reconstruct the elementorganic compounds one need to know the electronic structure of the organic and inorganic fragments. For the bonding in these compounds it will suffice that we know the frontier orbitals of the fragments — in other words the valence active orbitals of each fragment. Two fragments are isolobal if number, symmetry properties, approximate energy and shape of the frontier orbitals and the number of electrons in them are similar — not identical, but similar. Hoffmann introduced a symbol for the isolobal relationship: a “two‐headed” arrow with half an orbital below. One use of the isolobal model is in the structural sense. The model allows us to see the, simple essence of seemingly complex structures. This model is also very useful in synthesis of the elementorganic compounds. In this review are discussed the fundamentals and the applications of the isolobal model.
Korrelationen beim Hydrocracken von n‐Alkanen
Authors: Hoffmann Joachim , Petzold Erich 
Published: September 2010

AbstractThe quantitative analysis of the product distribution in hydrocracking of n‐alkanes necessitates the consideration of a large number of reactions for which the kinetic parameters must be known. It is possible to reduce considerably the number of kinetic parameters with the help of lumping analysis. For that one can use the dependencies of the activation energy on the number of carbon atoms and the correlations of the compensation effect. The cracked product distribution can be well described by a Gaussian normal distribution. Than the splitting probability of the individual C—C‐bonds was calculated with quantumchemical methods. The experimentally obtained cracked products correspond with the charge distribution in a carbenium ion.
Struktur‐Wirkungs‐Beziehungen von Auxinen aus theoretischen Konformationsuntersuchungen und molekularen elektrostatischen Potentialen
Authors: Brandt Wolfgang , Gründler Wolfgang 
Published: September 2010

AbstractNew aspects of structure‐activity relationships of auxins were found by theoretical investigations of conformations and molecular electrostatic potentials. The conformation of an active compound is characterized by the formation of an intramolecular hydrogen bond between the side‐chain and the π‐electronic system of the ring part. The molecular electrostatic potentials of active molecules possess a characteristic structure different from that of inactive compounds. Even the explanation of the different behaviour in auxin action of optically active compounds is possible.
Elektrochemische Detektion in Fließsystemen
Authors: Ernons Hendrik , Jokuszies Gabriele 
Published: September 2010

AbstractIn the review principles and analytical applications of conductometric, potentiometric, voltammetric and coulometric detection in streaming solutions are described, with the emphasis on dynamic interfacial techniques. Sensitivity, detection limit, linear dynamic range, response time, selectivity and stability are discussed. Favourable detector cell designs are described focussing on hydrodynamic, electrochemical and stability characteristics. Practical applications of amperometric detectors are summarized. Finally most recent developments and further trends in detector research are outlined.
Ordnungsfaktoren in der organischen Synthese Kooperativität von Ordnungsfaktoren in Organischen Synthesen: eine Generalisierung der Symmetrieregeln
Authors: Heimbach Paul , Bartik Tamás , Preis Heinz‐Günther , Szczendzina Georg , Zeppenfeld Eva 
Published: September 2010

AbstractQualitative models of selforganisation of matter postulate the formation of any order out of alternatives. The important order factors in chemistry are ODD/EVEN (number), P = +1/‐1 (parity), C = +/‐ (charge) and S/AS (phase relation), from which all empirical alternative order factors like e.g. CYCLIC/OPEN, CIS/TRANS, DO/ACC and so on are derived. The importance of especially those small order factors, which are often neglected, is demonstrated by examples with an absolute effect on alternative order in structure and/or process. The cooperativity of “pairs” of — also small — order factors in the subsystems with relative inhibition/activation and compensations instead of only absolute forbidden/allowed leads to a generalisation of symmetry control in chemistry.
Zum Stand der molekültheoretischen Behandlung von organischen Laserfarbstoffen
Authors: Gustav Klaus , Colditz Roland 
Published: September 2010

AbstractThe calculation of molecular geometries in different electronic states, and the determination of the radiative and nonradiative behaviour of molecules are a decisive prerequisite treating organic fluorescence and laser dyes by means of molecular theory. In this paper the present possibilities of the molecular theory are discussed with regard to those properties being essential for a potential laser ability. On this basis it was attempted to propose an unified molecular theoretical model taking into account the present level of knowledge.
Enaminothioketone — Synthesen und Eigenschaften
Authors: Pulst Manfred , Greif Dieter , Kleinpeter Erich 
Published: September 2010

AbstractMost important methods for the synthesis of enaminothioketones — A) sulfurization of enaminoketones; B) from β‐halogeno‐as well as β‐alkoxyvinylmethin‐immonium salts and alkali sulfides or ‐thiosulfates; C) from 1,2‐dithiolium and isothiazolium salts; D) from β‐thioxoaldehydes and amines — are described. The π‐electronic structure of the studied enaminothioketones has been investigated by means of different modes of spectroscopy (UV, IR, NMR) and characterized as polymethine‐like unsaturated organic compounds. This is proved with the obtained reactivity behaviour of the enaminothioketones as heteroanalogous 1,3‐diketones vs. eleclrophilic as well as nucleophilic attacks.
Halogenierung von Phosphorigsäurederivaten
Authors: Gloede Jöurg 
Published: September 2010

AbstractDerivatives of phosphorous acids react very quickly with chlorine. The stability of adducts is depend on the groups which are bound on the phosphorus atom. Accordingly a different behaviour was observed by the halogenation of alkyl and aryl phosphites or acyclic and cyclic phosphites or saturated and unsaturated heterocyclic phosphorus compounds.
Redoxstabilität in der σ‐Organoübergangsmetallchemie
Authors: Taube Rudolf , Steinborn Dirk , Drevs Helmuth , Chuong Pham Nguyen , Stransky Norbert , Langlotz Jochen 
Published: September 2010

AbstractStarting from usual principles of redox stability in coordination chemistry and from the donor‐acceptor characteristic of organyl ligands the review covers the redox behaviour of transition metals in the coordination with simple carbanions. The main topics are the stabilization of high oxidation states and the electron variability in s̀‐organyl transition metal complexes as well as the stabilization of low oxidation states, especially in electron rich phenyl complexes by coordination of lithium ions to the transition metal.
Zur Reaktion der Alkalimetalle mit Pyridin und seinen Substitutionsprodukten
Authors: Lühder Konrad , Füllbier Harry 
Published: September 2010

AbstractIn the present paper the reaction of alkali metals with pyridine and its substitution products is reviewed. Starting with the brutto reaction under anaerobic conditions, which yields the formation of radical anions of 4, 4′‐bipyridyl as a main product, the single steps such as formation of pyridine radical anions, dimerization of these radical anions, and, finally, the aromatization of the coupling product to the bipyridyl structure are discussed in detail.
Trennmaterialien auf der Basis von Kieselgel für die Hochleistungs‐Flüssigchromatographie
Authors: Dietrich Peter , Kunath Annamarie , Hoffmann Brigitte , Aßmann Eckhardt 
Published: September 2010

AbstractAt the present time amorphous porous silica is the mostly used adsorbent in the high performance liquid chromatography. This survey report about efforts in the GDR for investigations, developments and manufacturings of chemically bonded stationary phases especially of reversed phases. The quality of the stationary phases is depending on the mode of producing silica and its efficiency is a function of particle size characteristics as well as of chemical modification art.
Vinylisothiocyanate ‐ eine interessante Substanzklasse konjugierter Heterokumulene
Authors: Schulze Klaus , Schulze Bärbel , Richter Christian 
Published: September 2010

AbstractIsothiocyanates having the NCS‐group bound directly to the CC‐bond — the vinyl isothiocyanates — are of high synthetic interest because this type of heterodienes is a suitable precursor for heterocyclic compounds and derivatives of thiocarbamic acid. They cannot be prepared by standard methods.In this review we report 1) the synthesis of vinyl isothiocyanates by the reaction of nitrogen compounds with thiophosgene and other sulphur compounds, SNV‐reactions, elimination of HX, addition of HSCN to alkynes, cleavage of heterocycles and by miscellaneous methods 2) structure and reactivity of the vinyl isothiocyanates and 3) the reactions of these conjugated mustard oils with numerous nucleophiles and their behaviour as heterocumulenes in cycloaddition reactions.
Zur adsorptiven Zerlegung der Luft mit synthetischen Zeolithen
Authors: Siegel Hans , Schöllner Rolf , Hoffmann Jochen , Oehme Wolfgang 
Published: September 2010

AbstractPressure swing adsorption (PSA) processes are used to an increasing extent for gas separation. Especially the air separation for the production of low and moderate amounts of oxygen and nitrogen is more economic by PSA than by other separation processes. This paper deals with physical and chemical fundamentals of the air separation by PSA.After introducing remarks on the increasing application of the air components for several technical purposes the adsorption properties of synthetic zeolites like sieving action, adsorption energy, kinetics, ‐equilibrium and the state of the adsorbed molecules are reported. Furthermore, technical important aspects of the influence of water preadsorption, thermal treatment of the initial zeolites and the determination of separation factors are discussed.
Oxygenierung von Kohlenwasserstoffen mit Porphyrinkomplexen
Authors: Weber Lutz , Haufe Günter 
Published: September 2010

AbstractDuring the past ten years metalloporphyrin catalyzed oxygenations of hydrocarbons were developed by chemists, shifting from earlier normally unselective autoxidative processes to chemo‐, regio‐ and stereoselective reactions, which are oriented on enzymatic catalysis by metalloproteins. Hydroxylations of saturated as well as unsaturated hydrocarbons and epoxidations of olefins are the main topics of catalytic oxygenations using metalloporphyrins.
Metallclusterverbindungen  Chemie und Bedeutung; Homogene und heterogene Katalyse
Authors: Walther Bernhard 
Published: September 2010

AbstractThe interest in transition metal cluster catalysis has developed tremendously over the past decade because of the potential benefits metal cluster compounds may provide over traditional catalysts. Although these expectations have not been met yet transition metal cluster catalysis has offered many insights into the phenomenon of catalysis and still remains the most important driving force of the metal cluster chemistry. This part of the review on transition metal cluster compounds deals with the homogeneous and heterogeneous catalysis by such compounds.
Stand und Trends der Quecksilberspurenanalytik
Authors: Nitschke Lutz , Scholz Fritz , Henrion Günter 
Published: September 2010

AbstractThe main developments in the field of mercury analysis are traced back for the last decade. A short account of the history is given. New analytical methods and preconcentration techniques are regarded with special reference to spectrophotometry, atomic absorption spectroscopy, neutron activation analysis, voltammetry, chromatography, and catalytic analysis. Problems of sampling and applications to environmental analysis are included.
Zeugnisse aus der Gründungszeit des ersten Chemischen Laboratoriums der Berliner Universität  gefunden am 13 September 1988
Authors: Hass Dieter , Kreysig Dieter , Donke‐Müller Monika 
Published: September 2010

AbstractDuring building and reconstruction activities in the center of Berlin was found a casket made of sheet zinc which was deposited in the foundation wall of the former Irst Chemical Laboratory of the University of Berlin in the Georgen‐Street. This casket and its content documents the laying of the foundation stone of the building by A. W.Hofmann in 1865. In the casket were found the charter of the Irst Chemical Laboratory, photos showing A. W. Hofmann, C. A. Martins and E. Sell, the register of the staff and samples of synthesized dyes. This find is very important with respect to the history of chemistry at the University of Berlin and with view on the 100th anniversary of A. W. Hofmann's death 1992 which will be celebrated by an international conference in Berlin at Humboldt‐University common with the Academy of Science and the Chemical Society of G.D.R.
Nutzungsmöglichkeiten und Grenzen von Labor‐Mikroökosystemen
Authors: Martinetz Dieter , Wenzel Klaus‐Dieter , Weißflog Ludwig 
Published: September 2010

AbstractThe world‐wide increase of production and application of chemicals and the question, connected with it, of protection of the environment in case of damages, disposal of wastes and sewages without any harm as well as of the minimization of the risk make necessary to find out ecochemical and ecotoxicological datas which allow a corresponding evaluation of the environment behaviour.Possibilities are offered by terrestrial and aquatic model micro‐ecosystems which render possible to simulate chemical, physical, and biological processes of the natural environment with satisfactory reproducibility. A review is given on possibilities and limits.