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  • Electronic Resource  (14)
  • 1970-1974  (8)
  • 1960-1964  (6)
  • 1950-1954
  • 1920-1924
  • Reaction mechanisms
  • 1
    Electronic Resource
    Electronic Resource
    The Variety of Thermal Pericyclic Reactions (1974)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 13 (1974), S. 47-76 
    Details
    ISSN: 0570-0833
    Keywords: Pericyclic reactions ; Reaction mechanisms ; Woodward-Hoffmann rules ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The six-electron thermal pericyclic reactions are examined systematically as to the number and kind which are possible by varying both the σ shell and the combinations of different atoms in all orientations, on both a six-atom and a five-atom framework. A simple unifying nomenclature is offered for these reactions, which number in the thousands. Further, in order to comprehend this very large number of possible reactions, they are also organized systematically in terms of their value for basic synthesis operations: construction, elimination, refunctionalization, etc. The methodology is aimed at providing a basis of selection for the invention of useful new reactions. A discussion of reaction energetics leads also to an analysis of molecular features which can facilitate reaction.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.197400471
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  • 2
    Electronic Resource
    Electronic Resource
    The Theory of Pericyclic Reactions (1974)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 13 (1974), S. 751-780 
    Details
    ISSN: 0570-0833
    Keywords: Pericyclic reactions ; Reaction mechanisms ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pericyclic reactions include thermal and photochemical cycloadditions and cycloreversions, electrocyclic reactions and sigmatropic shifts. Configuration interaction analysis can be used for making predictions about preferred reaction pathways, about reaction rates, about the nature of possible intermediate steps, and above all about the stereochemistry of such reactions.
    Additional Material: 26 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.197407511
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  • 3
    Electronic Resource
    Electronic Resource
    Kinetics and Mechanism of Radical Polymerization (1974)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 13 (1974), S. 781-789 
    Details
    ISSN: 0570-0833
    Keywords: Kinetics ; Radical polymerization ; Polymerization ; Reaction mechanisms ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Low molecular reactions are frequently accompanied by side reactions producing a whole spectrum of by-products whose removal in purification operations generally causes little difficulty because the major and side products usually differ sufficiently in their properties. Hence detailed kinetic studies in low molecular chemistry can claim industrial interest only insofar as they aim to reduce the rate of formation of side products. The situation is completely different in polymer chemistry, where the terms major and side product no longer apply. Instead, one obtains mixtures of similar and/or isomeric molecules which differ so little with regard to molecular weight and structure that resolution into pure substances or isolation of pure substances becomes practically impossible. However, since all partial reactions exert a direct influence on the product spread, i.e. the composition and properties of a product mixture are modified by any change in operating conditions, detailed kinetic analyses embracing all relevant partial reactions are an essential prerequisite for the production of defined polymeric products on any scale. This progress report illustrates the importance of kinetics for radical polymerization with the aid of selected examples.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.197407811
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  • 4
    Electronic Resource
    Electronic Resource
    Displacement Reactions of Phosphorus(V) Compounds and Their Pentacoordinate IntermediatesChemistry and Logical Structures, Part 5. - Part 4: see Ref. [2]. (1973)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 12 (1973), S. 91-119 
    Details
    ISSN: 0570-0833
    Keywords: Displacement reactions ; Phosphorus ; Phosphorus ; Reaction mechanisms ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of phosphorus(v) compounds involving the mutual interconversion of tetra- and pentacoordinate species are discussed in a critical review emphasizing stereochemical implications of the reaction mechanism. This discussion includes the formation and decomposition of the stable oxyphosphoranes, the Michaelis-Arbusov, Perkov, and Wittig reactions, interconversions of phosphines and their oxides, and the nucleophilic displacements on phosphonium compounds. Reactions of phosphate esters and related compounds receive particular attention. All chemical arguments are derived by considering the effect of factors determining the relative stabilities of phosphorane derivatives, their rates of formation, decomposition and rearrangement by bond deformation or rupture and recombination processes, considerations which are uniformly applied on the basis of concepts developed in a preceding communication[2]. It is shown that a comprehensive mechanistic interpretation of the foregoing reactions requires substantial addition to available conceptual foundations such that, in many cases, present concepts and mechanisms must be revised.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.197300911
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  • 5
    Electronic Resource
    Electronic Resource
    Mechanistic Analysis of Solution Reactions by Non-Isothermal Calorimetry (1973)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 12 (1973), S. 381-389 
    Details
    ISSN: 0570-0833
    Keywords: Solution reactions ; Calorimetry ; Differential thermal analysis ; Reaction mechanisms ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: For the rapid kinetic and energetic analysis of reactions in solution (τ20°C 〉 10-4s) by differential thermal analysis (DTA), the following thermogram parameters are defined as characterizing the start of the reaction: 1. initial temperature, 2. activation energy of the initiation reaction. In conjunction with the shape index (asymmetry of the DTA curve) and the half width of the DTA curve referred to standard physical conditions (cell constant, heating rate, and temperature difference), these quantities allow a simple distinction between one-step reactions of first and second order and composite reactions. It is possible to recognize whether a process involves parallel, successive, or equilibrium reactions, or combinations of these. The reaction mechanism can be clarified in many cases by measurements at various concentrations and heating rates and by discussion of the enthalpy values. The shortened method described in this report for the evaluation of the thermograms was derived with the aid of an analog computer and checked experimentally.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.197303811
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  • 6
    Electronic Resource
    Electronic Resource
    Mechanisms of Reactions in the Solid State (1972)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 11 (1972), S. 173-179 
    Details
    ISSN: 0570-0833
    Keywords: Solid-state reactions ; Reaction mechanisms ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of two solid phases X and Y to give a solid compound XYv is taken as an example for the discussion of transport mechanisms and reaction steps. The following methods of investigation are discussed: determination of the rate law, marker experiments, and calculation of the reaction rate. It is pointed out that the investigation of powder reactions leads to problematic conclusions.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.197201731
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  • 7
    Electronic Resource
    Electronic Resource
    The Mechanism of Contact Elimination, A Contribution to Understanding the Function of Polar Catalysts (1971)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 10 (1971), S. 172-181 
    Details
    ISSN: 0570-0833
    Keywords: Contact elimination ; Elimination ; Reaction mechanisms ; Catalysis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The current ideas of organic chemists based on the work of Ingold and his school are applied to heterogeneous catalytic eliminations (mostly from haloalkanes and aliphatic alcohols). It is deduced from the activity of the catalysts, the reactivity of the substrates (reactants), and the primary product distribution that these eliminations proceed by a heterolytic mechanism similar to that involved in the liquid phase. The activity of the catalysts (salts and oxides) increases with increasing charge and decreasing radius of the cations and with increasing basicity of the anions. The reactivity of the substrates behaves in much the same manner as in the liquid phase. In contrast with the liquid-phase reaction, the cis-olefins are frequently favored as primary products. The stereospecificity of the reaction is determined from the relative strengths of the interactions between the catalyst cation and the leaving group X-, and between the catalyst anion and the leaving proton. Only trans elimination has so far been found in the concerted mechanism.
    Additional Material: 11 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.197101721
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  • 8
    Electronic Resource
    Electronic Resource
    Kinetic Evidence for Reactive IntermediatesBased on a GDCh training course from October 6-9, 1969 in Munich. (1970)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 9 (1970), S. 751-762 
    Details
    ISSN: 0570-0833
    Keywords: Intermediates ; Kinetics ; Reaction mechanisms ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Spectroscopic methods have recently been developed that allow the direct detection of reactive intermediates under favorable circumstances. The most general and reliable method, however, is still the indirect one, which makes use of the priciple of kinetic competition; this method is based on the freedom of the intermediate to choose between several reaction possibilities. The following discussion is addressed less to the specialist in reaction mechanisms than to the outsider who wishes to obtain some idea of the value and limitations of the kinetic method.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.197007511
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  • 9
    Electronic Resource
    Electronic Resource
    The Course of the Willgerodt-Kindler Reaction of Alkyl Aryl KetonesA review article (a continuation of [1]) is being prepared in which the new compounds discussed in the present paper are treated in greater detail. A paper recently published [2] prompted us to make our concept of the course of the Willgerodt-Kindler reaction known.Respectfully dedicated to Prof. Dr. Karl Ziegler on the occasion of his 65th birthday (1964)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 19-28 
    Details
    ISSN: 0570-0833
    Keywords: Willgerodt-Kindler reaction ; Ketones ; Reaction mechanisms ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ketones react with sulfur and NH3 or amines at room temperature to produce Δ3-thiazolines, 5-alkylidene-Δ3-thiazolines, Δ3-imidazoline-5-thiones, hexathiacycloheptane derivatives, α,α′-dioxodisulfides, bis-(1-aralk-1-yl) disulfides, or thiocarboxamides, depending on the coreactant and on the reaction conditions. It was recognized that the formation of all of these numerous types of compounds can be explained basically by primary thiolations and geminal dithiolations, which in conjunction with their reverse reaction (desulfurization) and the assumption of a thioreductone equilibrium permit a new interpretation of the course of the Willgerodt-Kindler reaction of alkyl aryl ketones.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196400191
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  • 10
    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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  • 11
    Electronic Resource
    Electronic Resource
    Phenol Oxidation ReactionsDedicated to Professor Dr. Hans Brockmann on the occasion of his 60th birthday (1963)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 723-735 
    Details
    ISSN: 0570-0833
    Keywords: Phenol oxidation ; C-C coupling ; Reaction mechanisms ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The use of well-known phenol oxidation reactions for the preparation of compounds arising from C—C and C—O coupling has recently received increased attention. A selection from the large number of products obtainable by oxidation of mono- and polyhydric phenols and a discussion of the reaction mechanisms indicate the scope of this method. The formation of hydroxyphenylquinones and orceine dyes from resorcinol derivatives is explained. The synthesis of natural products by way of phenol oxidations is briefly discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196307231
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  • 12
    Electronic Resource
    Electronic Resource
    Kinetics and Mechanism of 1,3-Dipolr CycloadditionsExtended version of a lecture given at the Annual Meeting of the Dechema in Frankfurt/Main on June 14th, 1962, and of the Max Tishler Lecture at Harvard University on December 10th, 1962. (1963)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 633-645 
    Details
    ISSN: 0570-0833
    Keywords: Kinetics ; Dipolar cycloaddition ; Cycloaddition ; Heterocycles ; Reaction mechanisms ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Criteria for the mechanism of 1,3-dipolar cycloadditions which lead to 5-membered rings are provided by the stereoselectivity observed with cis-trans isomeric dipolarophiles, by the effect of solvent and substituents on the rate constants, by the activation parameters, and by orientation phenomena. A concerted addition, which can also be described in terms of molecular orbitals and in which the two new σ-bonds are formed simultaneously, although not necessarily at equal rates, offers the best explanation of the experimental facts.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196306331
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  • 13
    Electronic Resource
    Electronic Resource
    The Mechanism of Bimolecular β-Elimination ReactionsBased on lectures presented in February-July, 1961, at University College, London, University College, Dublin, the University of Bologna and the University of Munich. (1962)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 225-235 
    Details
    ISSN: 0570-0833
    Keywords: Elimination ; Reaction mechanisms ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In bimolecular β-elimination (E 2 mechanism), several bonds are ruptured or formed in one concerted reaction step. However, the various aspects of bond-making or -breaking need not be completely synchronous. In the E 2 transition state for elimination HX, rupture of the C—X bond may be more advanced than that of the C—H linkage, or vice versa. Factors influencing the relative extents of rupture of these two bonds at the transition state are discussed, and the consequences of non-synchroneity in one sense or the other are developed from theory and illustrated from experiment. This treatment provides an understanding of the Hofmann-vs.-Saytzeff orientation problem.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196202251
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  • 14
    Electronic Resource
    Electronic Resource
    Electrophilic Substitutions at Saturated Carbon Atoms (1962)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 382-393 
    Details
    ISSN: 0570-0833
    Keywords: Electrophilic reactions ; Reaction mechanisms ; Substitution ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The results obtained in recent years from investigations into the mechanisms of electrophilic substitution reaction at sp3-hybridized carbon atoms are reviewed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196203821
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