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  • 1980-1984  (4)
  • 1960-1964  (3)
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  • 1980  (4)
  • 1964  (3)
  • 1948
  • Catalysis
  • 1
    Electronic Resource
    Electronic Resource
    Kinetics of alkaline chloramine-T oxidation of arginine monohydrochloride with and without catalytic action of Cu(II) ion (1980)
    Springer
    Monatshefte für Chemie 111 (1980), S. 649-656 
    Details
    ISSN: 1434-4475
    Keywords: Arginine ; Catalysis ; Kinetics ; Mechanism ; Oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Oxidation erfolgt sowohl mit als auch ohne Cu(II)-Katalysator in erster Ordnung bezüglich des Oxidationsmittels und des Substrats; inverse Ordnung wird bezüglich der Alkalikonzentration beobachtet. Bis zu einer Cu(II)-Konzentration von≤2×10−5 M ist die Geschwindigkeitskonstante der Katalysatorkonzentration proportional; darüber wird eine konstantbleibende Geschwindigkeit beobachtet, die nun von der Cu(II)-Konzentration unabhängig ist. Neutralsalze haben keinen Effekt auf die Geschwindigkeitskonstante. Es wird für den katalysierten und unkatalysierten Reaktionsablauf ein Mechanismus vorgeschlagen und ein mathematischer Ansatz präsentiert.
    Notes: Abstract The kinetics of uncatalysed and Cu(II) catalysed oxidation of arginine monohydrochloride was investigated. Both reactions follow a singular order dependence each in oxidant and substrate. An inverse order dependence is reported with the alkali concentration. A plot of observed rate constant versus Cu(II) concentrations Cu(II)≤2.0×10−5 M is linear; from the intercept the rate constant for the uncatalysed pathway was calculated. However, at high copper ion concentrations i.e. Cu(II)〉2.0×10−5 M a fixed value of rate constant was found for all catalyst concentrations. Added neutral salts show an insignificant effect on the reaction rate. Mechanisms were proposed for both cases and rate expressions were derived by applying steady state assumptions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00903319
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Catalysis of peptide bond formation by histidyl-histidine in a fluctuating clay environment (1980)
    Springer
    Journal of molecular evolution 16 (1980), S. 279-290 
    Details
    ISSN: 1432-1432
    Keywords: Catalysis ; Clay ; Histidyl-histidine ; Oligopeptide ; Protoenzyme ; Autocatalysis ; Prebiotic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The condensation of glycine to form oligoglycines during wet-dry fluctuations on clay surfaces was enhanced up to threefold or greater by small amounts of histidyl-histidine. In addition, higher relative yields of the longer oligomers were produced. Other specific dipeptides tested gave no enhancement, and imidazole, histidine, and N-acetylhistidine gave only slight enhancements. Histidyl-histidine apparently acts as a true catalyst (in the sense of repeatedly catalyzing the reaction), since up to 52 nmol of additional glycine were incorporated into oligoglycine for each nmol of catalyst added. This is the first known instance of a peptide or similar molecule demonstrating a catalytic turnover number greater than unity in a prebiotic oligomer synthesis reaction, and suggests that histidyl-histidine is a model for a primitive prebiotic protoenzyme. Catalysis of peptide bond synthesis by a molecule which is itself a peptide implies that related systems may be capable of exhibiting autocatalytic growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01804979
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesis of Intermediates by Rhodium-Catalyzed HydroformylationDedicated to Professor Matthias Seefelder on the occasion of his 60th birthday (1980)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 19 (1980), S. 178-183 
    Details
    ISSN: 0570-0833
    Keywords: Intermediates ; Hydroformylation ; Rhodium catalysts ; Catalysis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of olefins with carbon monoxide and hydrogen to give aldehydes is referred to as hydroformylation (oxo reaction). As catalyst for this reaction rhodium is about three to four orders of magnitude more active than the more commonly employed cobalt. With special rhodium compounds, e.g. di-ν-chlorobis(ν-1,5-cyclooctadiene)dirhodium [RhCl(C8H12)]2, in the presence of chiral phosphanes, even asymmetric hydroformylations can be achieved; however, the enantiomeric purity of the products (20-30%) is not high enough for industrial-scale syntheses.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.198001781
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Trimethylphosphane Complexes of Nickel, Cobalt, and Iron - Model Compounds for Homogeneous Catalysis (1980)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 19 (1980), S. 362-375 
    Details
    ISSN: 0570-0833
    Keywords: Trimethylphosphane complexes ; Phosphane ligands ; Homogeneous catalysis ; Catalysis ; Cobalt ; Nickel ; Iron ; P ligands ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: One of the greatest achievements of organometallic chemistry in the last ten years has been the experimental proof that transition metal-to-carbon bonds are thermodynamically about as stable as those between main group elements and carbon. The present contribution demonstrates how simply constituted alkylnickel, -cobalt, and -iron complexes are obtained by means of a kinetic stabilization using suitable neutral ligands and what information these model compounds can provide with respect to the course of processes in homogeneous catalyses.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.198003621
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  • 5
    Electronic Resource
    Electronic Resource
    Proton Transfer, Acid-Base Catalysis, and Enzymatic Hydrolysis. Part I: ELEMENTARY PROCESSESPart II (Catalytic Mechanisms) will appear shortly in this journal.Dedicated to Dr. W. Foerst on the occasion of his 65th birthday (1964)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 1-19 
    Details
    ISSN: 0570-0833
    Keywords: Proton transfer ; Catalysis ; Enzyme catalysis ; Hydrolysis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The proton occupies a special position as a promoter and mediator in chemical reactions occurring in solution. Many reactions in organic chemistry are catalysed by acids or bases; likewise, most enzymes contain active groups which promote acid-base catalysis. To understand the reaction mechanisms involved, it is necessary to identify the elementary steps as well as their course in time. Systematic investigation of these elementary steps as well as their course in time. Systematic investigation of these elementary steps has become possible only with the development of new methods for studying very fast reactions. The present paper reviews the information obtained in this type of investigation. The result is a relatively complete picture of the elementary proton transfer mechanisms and a comprehensive description of the modes and laws of acid-base and enzymatic catalysis.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196400011
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  • 6
    Electronic Resource
    Electronic Resource
    The Mechanism of the Action of Organometallic CatalystsDedicated to Prof. Dr. Karl Winnacker on the occasion of his 60th birthday. (1964)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 93-101 
    Details
    ISSN: 0570-0833
    Keywords: Organometallic catalysts ; Catalysis ; Reaction mechanisms ; Lithium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Kinetic investigations of the polyreaction of isoprene with organolithium compounds as initiators in n-heptane as solvent indicate the following sequence of reactions: 1. formation of an adduct between a monomeric form of the organolithium compound and the isoprene and 2. reaction of this adduct with an associated form of the organolithium compound with insertion of the isoprene. The adduct formation is considered to be due to chemisorption, and proof of such chemisorption of a monomer (ethylene) is also demonstrated for a homogeneous Ziegler-type catalyst. All the reactions can be formulated in the form of cyclic structures with electron-deficient character. Postulation of such ring structures explains the surprising values obtained for the frequency factors and equilibrium constants.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196400931
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  • 7
    Electronic Resource
    Electronic Resource
    Coordination Chemistry and Catalysis. Investigations on the Synthesis of Cyclooctatetraene by the Method of W. Reppe (1964)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 185-191 
    Details
    ISSN: 0570-0833
    Keywords: Coordination modes ; Catalysis ; Cyclooctatetraenes ; Reppe chemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The relationship between the structure and the catalytic activity of nickel(II) complexes in the synthesis of cyclooctatetraene by the method of W. Reppe is discussed. The cyclotetramerization of acetylene takes place within labile Ni(II)-acetylene π-complexes. Inhibition tests have made it probable that four molecules of acetylene are grouped around the nickel ion in the transition state, in a configuration which favors the formation of the eight-membered ring.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196401851
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