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  • 1965-1969  (21)
  • 1960-1964  (9)
  • 1920-1924
  • 1890-1899
  • 1880-1889
  • Alkenes
  • Heterocycles
  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 8 (1969), S. 478-482 
    ISSN: 0570-0833
    Keywords: Sesquifulvalenes ; Fulvalene ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Heterosesquifulvalenes containing sulfur or oxygen as hetero atom may be prepared, e.g., by condensation of cyclopentadienes with thiopyrones or pyrones in acetic anhydride. Heterosesquifulvalenes containing nitrogen can be obtained from the oxygen compounds by O,N-exchange. The ground state of all these compounds is determined mainly by the nonpolar resonance formula.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 8 (1969), S. 556-577 
    ISSN: 0570-0833
    Keywords: Ene reaction ; Addition ; Alkenes ; C-C coupling ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ene reaction is defined as the indirect substituting addition of a compound with a double bond (enophile) to an olefin with an allylic hydrogen (ene). For a long time the reaction has been neglected and has remained overshadowed by the related Diels-Alder addition. It is shown that the ene reaction possesses wide scope and applicability ranging from industrial to biosynthetic processes. Preparative aspects are summarized and current views on the mechanism are discussed.
    Additional Material: 8 Tab.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 8 (1969), S. 962-974 
    ISSN: 0570-0833
    Keywords: Heterocycles ; Aziridinium salts ; Azetidinium salts ; Cycloaddition ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and important reactions of stable aziridinium salts are described in this article. The more stable azetidinium salts, which undergo similar reactions, have also been studied. Polar and dipolar cycloadditions produce heterocycles by ring expansions that can be represented as .
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 7 (1968), S. 247-252 
    ISSN: 0570-0833
    Keywords: Reduction ; Chromium ; Alkyl halides ; Alkenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chromium(II) salts can be used for a variety of reductions in organic chemistry; for example, alkyl halides and suitably substituted olefins may both be reduced to alkanes, and alkynes may be converted into trans-olefins. Several epoxyketones are reduced to α,β-unsaturated ketones or β-hydroxyketones, and a nitro steroid was found to give a hydroxy(hydroxyimino) compound. The reduction of alkyl halides is reported to proceed by a free-radical mechanism; the halogen atom that is set free forms a bridge between two chromium atoms.
    Additional Material: 1 Tab.
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  • 5
    ISSN: 0570-0833
    Keywords: Carbonylation ; Alkenes ; Palladium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: During a search for catalysts that allow carbonylation reactions on olefins to proceed below 100 °C, complex palladium(II) compounds having the formula LmPdXn were found to be catalytically active. L denotes a ligand such as a phosphine, nitrile, amine, or olefin, X is an acid residue, and m+n is 3 or 4. The catalysts permit the carbonylation of heat-sensitive compounds, as well as selective carbonylation of polyunsaturated olefins. The new process can also be carried out on the industrial scale, as is shown by the carbonylation of cyclododecatriene
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 7 (1968), S. 754-765 
    ISSN: 0570-0833
    Keywords: Electron-rich alkenes ; Tetraaminoethylen ; Alkenes ; Tetramethoxyethylene ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Olefins are normally preferentially attacked by electrophiles. This trend is strengthened in enol ethers and enamines, and is particularly pronounced in tetramethoxyethylene and in tetraaminoethylenes. These electron-rich olefins are accordingly also excellent reducing agents. In their reactivity, therefore, they behave as counterparts of tetracyanoethylene. This compound shares with the electron-rich olefins a strong tendency to undergo cycloadditions, the electron-rich olefins adding particularly readily to electrophiles.
    Additional Material: 3 Tab.
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  • 7
    ISSN: 0570-0833
    Keywords: Sulfonyl hydrazones ; Amides ; Azo sulfones ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sulfonyl hydrazones of cyclic amides undergo oxidative coupling with phenols and reactive methylene components. The reaction proceeds via the azo sulfones, which may be used as such, and which, as ambident cations, enter into many reactions with nucleophiles and extend the scope of oxidative coupling. The reaction with phenols is a two-step process, in which the limiting cases k1 ≪ k2, k1 ≈ k2, and k1 ≫ k2 can be realized by slight variation of the reactants.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 7 (1968), S. 903-911 
    ISSN: 0570-0833
    Keywords: Alkylation ; Squalene epoxide ; Polyisoprenoid synthesis ; Biosynthesis ; Alkenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stereochemical studies, made possible by asymmetric labeling with hydrogen isotopes, have led to the hypothesis that enzymic association of C5 units in polysoprenoid synthesis is not a concerted process but proceeds in two steps: a trans 1,2-addition to an olefin followed by a trans 1,2-elimination. It is shown that similar mechanisms can also explain the cyclization of squalene epoxide to tetracyclic and pentacyclic triterpenoids.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 6 (1967), S. 919-928 
    ISSN: 0570-0833
    Keywords: Heteroaromatic compounds ; Hydration ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Many aromatic N-heterocycles add water across the C=N double bond. Methods are described for recognizing this phenomenon and for diagnosis of the site of attack. These methods are extended to the determination of (a) the ionization constants of unstable states (whether hydrated or anhydrous), (b) the ratio of hydrated to anhydrous forms at equilibrium, and (c) the rate constants of hydration. The features that stabilize hydration in a molecule are discussed. The literature through 1965 and 1966 is reviewed with special reference to the emergence of new principles, such as di-hydration and the shifting of hydration within a molecule.
    Additional Material: 5 Ill.
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  • 10
    ISSN: 0570-0833
    Keywords: Ketones ; Sulfur ; Amines ; Heterocycles ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A large number of preparatively interesting compounds have become readily available by the simultaneous action of sulfur and ammonia or amines on ketones. Direct syntheses of Δ3-thiazolines, Δ3-imidazoline-5-thiones, 5,6-dihydro-4H-1,4-thiazines, and the 1,2,3,4,5,6-hexathiocane system from ketones, sulfur, and ammonia or amines, and further possibilities for the synthesis of these heterocyclic systems have been proposed. Other heterocycles containing N or N and S (thiazoles, thiophenes, thiazolidines, tetrahydrothiazolo[2,3-c]-1,4-thiazines, thiomorpholines, 4-amino-2H-imidazoles, etc.) are readily obtainable by further reactions of these compounds. Hydrolysis of the Δ3-thiazolines yields α-mercapto ketones, which are the starting materials for other syntheses. Most of the syntheses described proceed at room temperature and at normal pressure.
    Additional Material: 10 Tab.
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  • 11
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 6 (1967), S. 423-434 
    ISSN: 0570-0833
    Keywords: Addition ; Alkenes ; Alkynes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The possibilities of additions to the activated CC triple bond are discussed with the aid of a number of examples. The additions of donors that contain no active hydrogen are generally initiated via a dipolar primary complex, which can undergo stabilization by rearrangement, cyclization, or addition reactions. Preparative aspects of these reactions are also discussed. They offer routes for the preparation of heterocycles, particularly pyrrole and thiophene derivatives.
    Type of Medium: Electronic Resource
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  • 12
    ISSN: 0570-0833
    Keywords: Allyl transition metal systems ; Bis(allyl)nickel ; Nickel ; Polymerization ; Alkenes ; Allylic ligands ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As a continuation of a report published in 1963, recent results in the field of allyl-transition metal complexes are describedThe term “allyl compounds” in the present paper refers not only to compounds containing the simple allyl group (CH2=CH—CH2—), but also to those that contain substituted allyl groups or allyl groups forming part of a ring system.. Syntheses and reactions of these compounds, as well as the bonding between metal and allyl group, are discussed. Allyl-transition metal complexes form the basis of extremely selective catalysts for homogeneous reactions of 1, 3-diolefins and of olefins; the metal atoms in these “matrix” catalysts are either “bare”The description “bare” is applied to complexed metal atoms from which the ligands can be quantitatively displaced by the substances taking part in catalytic reactions. or are bound to only a few ligands.
    Additional Material: 3 Tab.
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  • 13
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 5 (1966), S. 35-39 
    ISSN: 0570-0833
    Keywords: Heterocycles ; Pyrimidines ; Quinazolines ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Some syntheses of heretofore unknown pyrimidines, tetrahydroquinazolines, and quinazolines are described. These methods are uniquely simple one- or two-step reactions, general and versatile in scope, and give high yields. Some interesting chemistry associated with these heterocyclic systems is discussed.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 5 (1966), S. 760-776 
    ISSN: 0570-0833
    Keywords: Silicon-nitrogen heterocycles ; Heterocycles ; Cyclosilazanes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Great progress has recently been made in the chemistry of the silicon-nitrogen bondC. Eaborn: Organosilicon Compounds. Butterworths, London 1960, p. 339.R. Fessenden and J. S. Fessenden, Chem. Reviews 61, 361 (1961).K. A. Andrianov, I. Haiduc, and L. M. Khananashvili, Uspekhi Khim. 32, 563 (1963); Chem. Abstr. 59, 8782 (1963).U. Wannagat, Advances inorg. Chem. Radiochem. 6, 265 (1964).I. Haiduc: Westep do Chemii Nieorganicznych Zwiazkow Pierscieniowyrh. WPN, Warsaw 1964, Chap. 10 (in Polish).. Whereas attention was formerly concentrated on open-chain silazanes and silylamines, growing interest is now being shown in the cyclic SiN compounds. A major factor which has contributed to the rapid development in this field is the need for better polymers and liquids for use above 350 °CCf. E. G. Rochow, Chim. et Ind. 85, 897 (1961).. The present article deals with monomeric cyclic compounds containing at least one silicon-nitrogen bond in the ring, as well as the polycyclic compounds derived from these.
    Additional Material: 8 Tab.
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  • 15
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 4 (1965), S. 49-68 
    ISSN: 0570-0833
    Keywords: Elimination ; Alkenes ; Alkynes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Eliminations from olefins are very often initiated by bases, and usually lead to formation of acetylene derivatives. In view of the numerous side-reactions and subsequent additions or rearrangments observed, the nature of the base used is of considerable significance. Organometallic bases are very versatile. In addition to dehydrohalogenation, dehalogenation by metals, and also thermolytic and photolytic eliminations. (e.g. the retrodiene reaction with exchange of substituents) are discussed. Elimination from low-membered cyclic olefins yields cycloalkynes having strained ring-systems, and the existence of these can be demonstrated by trapping them. The mechanisms known for β-elimination (E2, E1 and E1cB) occur also in the case of olefins; however - due to the sp2-hybridization of the carbon atoms taking part - they are realized with different rates of reaction relative to saturated compounds. α-Eliminations from olefines having aryl residues in the β-position lead to formation of arylacetylenes by rearrangement of the carbon skeleton. The mechanism of this reaction, which is known as the Fritsch-Buttenberg-Wiechell rearrangement, is discussed in considerable detail, and several variations of the reaction are considered. According to present-day knowledge carbenes are involved in α-eliminations only when both β-positions of the olefin are occupied by aliphatic substituents, or when they are occupied by aromatic residues where rearrangement to acetylenes is impossible for steric reasons (as for example with 9-chloromethylenefluorene). With organolithium compounds a number of dehydrohalogenations, which are formally β-eliminations, actually proceed via deprotonation on the halogenbearing carbon atom (α-metallation). α-Metallations are the rate-determining steps when ether is used as solvent, but proceed quickly in tetrahydrofuran even at low temperatures. Compounds of the type \documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}$\raise1pt\hbox{$〉$}{\rm C}\raise1pt\hbox{=\kern-3.45pt=}{\rm C(Li)Cl}$\end{document} may be prepared by this method and are recognized as intermediates in α-eliminations.
    Additional Material: 2 Tab.
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  • 16
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 4 (1965), S. 583-587 
    ISSN: 0570-0833
    Keywords: Alkylidenephosphoranes ; Phosphonium salts ; Synthetic methods ; Phosphoranes ; Ylides ; Alkenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Phosphonium salts may be regarded as Bronsted acids, and alkylidenephosphoranes as the conjugate bases. Compounds of the two classes exist in equilibrium with each other. Phosphonium salts and alkylidenephosphoranes can be obtained by this “transylidation”. Other methods are also given for the preparation of members of both classes.
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  • 17
    ISSN: 0570-0833
    Keywords: Alkylidenephosphoranes ; Phosphonium salts ; Synthetic methods ; Phosphoranes ; Ylides ; Alkenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of alkylidenephosphoranes with compounds containing halogens can be used to prepare ylides, which can be converted in to useful products, e.g. by hydrolysis, by thermal decomposition, or by other reactions. Examples of such products are ketones including cyclic, unsaturated, and branched-chain ketones (including cyclic, unsaturated, and branched-chain ketones), carboxlic esters (including those of unsaturated, branched- chain, polyenecarboxylic, acetylenecarboxylic, and allenecarboxylic acids), and aldehydes.
    Additional Material: 10 Tab.
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  • 18
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 4 (1965), S. 543-557 
    ISSN: 0570-0833
    Keywords: Hetarynes ; Heterocycles ; Alkynes ; Arynes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Investigations carried out during the last six years have shown that, as in the case of benzene, an extra bond can be introduced into heteroaromatic rings. Since this possibility does not appear to be confined to exceptional cases, the heterocyclic arynes (hetarynes) promise a much wider variety than the carbocyclic arynes. Hetarynes occur mainly as intermediates in nucleophilic substitutions on halogenated heterocyclic compounds. Since the replacement of a CH group in dehydrobenzene by a nitrogen atom and the condensation of benzene rings have stabilizing effects, the stability of hetarynes is expected to increase with the number of N atoms and with the number of condensed aromatic rings.
    Additional Material: 1 Ill.
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  • 19
    ISSN: 0570-0833
    Keywords: Alkylidenephosphoranes ; Phosphonium salts ; Synthetic methods ; Phosphoranes ; Ylides ; Alkenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A few examples of preparatively useful syntheses using alkylidenephosphoranes and substances containing a C—N or C—C double bond are the preparations of olefins, allenes, pyran derivatives, and cyclopropane derivatives. Olefins, ketones, and monocyclic compounds can be obtained by autoxidation of alkylidenephosphoranes; α, β-dioxo compounds (including cyclicones) can be prepared by oxidation with peroxy-acids. Alkylidenephosphoranes can also be used for the synthesis of azines and Schiff bases. Of the many possibilities offered by the Wittig reaction, only the preparation of tritiated aldehydes and olefins will be considered.
    Additional Material: 1 Ill.
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  • 20
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 4 (1965), S. 292-300 
    ISSN: 0570-0833
    Keywords: Pyridazones ; Heterocycles ; Mucochloric acid ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new synthesis of mucochloric acid by chlorination of butynediol has facilitated the preparation of a series of 4,5-dichoropyridazones. The high reactivity of these compounds has been investigated and applied in several ways. New classes of compounds, some with biological activity, were obtained by displacement of the chlorine atoms. New heterocyclic systems were prepared by condensation and rearrangement reactions.
    Additional Material: 2 Tab.
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  • 21
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 4 (1965), S. 1023-1038 
    ISSN: 0570-0833
    Keywords: Heterocycles ; Phosphorus ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation of heterocycles containing phosphorus is described. The chemical behavior of ring systems containing trivalent phosphorus is mainly determined by their phosphine character; heterocyclic behavior in the ordinary sense is shown by rings containing functional groups. Syntheses and reactions of cyclic compounds of pentavalent and hexavalent phosphorus are particularly interesting.
    Additional Material: 3 Tab.
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  • 22
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 245-249 
    ISSN: 0570-0833
    Keywords: Addition ; Alkenes ; Electrophilic reactions ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various structures have been proposed for the intermediates of electrophilic additions onto olefins; these include halonium ions, classical carbonium ions, π-complexes (i.e. nonclassical carbonium ions), and π-complexes with back-coordination. It is shown here that it is impossible to use any one of these entities alone to explain all such electrophilic additions; the electrophile itself determines the nature of the transition state formed. Polar addition of hydrogen halides onto olefins appears to proceed via a classical carbonium ion which does not occur as the free ion but as an undissociated ion pair. Various other mechanisms have been excluded by studies reported here of the stereochemical course of such additions.
    Additional Material: 2 Tab.
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  • 23
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 333-341 
    ISSN: 0570-0833
    Keywords: Strained molecules ; Heterocycles ; Diaziridines ; Diazirines ; Oxaziranes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Since their discovery five years ago, the diaziridines have become an extensive and easily accessible class of compounds. Hydrolysis of these compounds effects a simple synthesis of hydrazine, alkylhydrazines, and N,N′-dialkylhydrazines. They are also powerful oxidizing agents. The rigidity of the three-membered ring gives rise to a few stereoelectronic peculiarities. Investigations on the mechanism of formation of the three-membered rings led to a new synthesis of oxaziranes and to discovery of the isomeric oximes with a three-membered ring structure. The latter decompose readily to form diimide. Diazirines are cyclic isomers of the aliphatic diazo compounds and are surprisingly easy to obtain by dehydrogenation of suitable diaziridines; they are chemically much more stable than the linear isomers. Grignard reagents add onto the N=N double bond without destruction of the three-membered ring. Thermal decomposition yields carbenes.
    Additional Material: 1 Ill.
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  • 24
    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.
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  • 25
    ISSN: 0570-0833
    Keywords: Koch carboxylic acid synthesis ; Carboxylic acids ; Alkenes ; Isomerization ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: When straight-chain mono-olefins, from pentene to decene, are subjected to the Koch carboxylic acid synthesis by the addition of CO and H2O or CH3OH in the presence of strongly acidic catalysts, not only the expected secondary acids, but also mixtures of a specific type of tertiary acids or their methyl esters are formed. When the catalysts contain boron trifluoride, the secondary acids are formed in ratios of isomers which are, within the scope of this investigation, independent of the experimental conditions and which agree well with the values calculated from the isomer equilibria of the corresponding n-olefins. Using concentrated sulfuric acid as catalyst, a larger proportion of tertiary acids is obtained than with BF3-catalysis, and amongst the secondary acids, those isomers predominate in which the COOH group is situated near the centre of the molecule.
    Additional Material: 1 Ill.
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  • 26
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 295-308 
    ISSN: 0570-0833
    Keywords: Emulsion polymerization ; Polymerization ; Polymerization ; Alkenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ionizing radiation induces the polymerization of some vinyl monomers in aqueous emulsion with high radiation yields. With identical emulsion compositions, the kinetics of this reaction and the kinetics of emulsion polymerization induced by water-soluble initiators are very similar. The rate of reaction in emulsion polymerization is about one hundred times greater than in bulk polymerization. The initiation of emulsion polymerization by means of ionizing radiation permits uniform “illumination” of the reacting volume, as well as almost any desired variation in the frequency of initiation during the reaction. The sharp decrease in the overall rate of reaction when initiation is interrupted during emulsion polymerization of styrene induced by γ-rays contradicts the earlier concept of sharply separated reaction zones.
    Additional Material: 11 Ill.
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  • 27
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 459-476 
    ISSN: 0570-0833
    Keywords: Aminoguanidine ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Due to its unique structure, aminoguanidine is capable of reacting as a derivative of hydrazine, guanidine or formamidine. Addition and condensation reactions yield products which can be cyclized to heterocyclic compounds. Frequently, heterocyclics are directly accessible from aminoguanidine in one stage.
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  • 28
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 565-598 
    ISSN: 0570-0833
    Keywords: Dipolar cycloaddition ; Cycloaddition ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In contrast to the very large number of special methods applicable to syntheses in the heterocyclic series, relatively few general methods are available. The 1,3-dipolar addition offers a remarkably wide range of utility in the synthesis of five-membered heterocycles. Here the “1,3-dipole”, which can only be represented by zwitterionic octet resonance structures, combines in a cycloaddition with a multiple bond system - the “dipolarophile” - to form an uncharged five-membered ring. Although numerous individual examples of this reaction were known, some even back in the nineteenth century, fruitful development of this synthetic principle has been achieved only in recent years.
    Additional Material: 4 Tab.
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  • 29
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 704-714 
    ISSN: 0570-0833
    Keywords: Titanium ; Alkenes ; Polymerization ; Titanium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: At low temperatures, ethylene and α-olefins (Δ1-olefins or 1-alkenes) are rapidly converted into oligomrs by the two-component organometallic catalyst CH3TiCl3·CH3AlCl2. To achieve smooth oligomerizations, aromatic or chlorinated hydrocarbons must be used as solvents. Although the activity of the titanium-carbon bond is enhanced by the aluminum component of the catalyst, the aluminum and its methyl group do not participate in the reaction proper; the latter proceeds exclusively at the titanium-carbon bond. The reaction will olefins can be used as an analytical method for the quantitative determination of the titanium-carbon bond in admixture with the organoaluminum component. It is thus possible to follow the reaction leading to formation of the catalyst from titanium tertrachloride, as well as the processes occurring at the titanium-carbon bond during the oligomerization of olefins. All the observations indicate that the catalyst possesses an ionic structure which is determined by the solvent. It is shown that the initial reaction step probably involves formation of a complex between the olefin and the alkyltitanium cation. The reaction scheme proposed is based on organometallic reactions which are characterized by carbanion and hydride transfers within the olefin-cation complex. This mechanism, which is unusual for Ziegler catalysts, is due to the predominance of hydride transfers.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 30
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 80-88 
    ISSN: 0570-0833
    Keywords: Oxidation ; Palladium ; Catalysis ; Alkenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The oxidation of olefins to carbonyl compounds with palladium compounds, especially the oxidation of ethylene to acetaldehyde, is at present carried out on a technical scale. The reaction takes place via a palladium-olefin complex, the formation of which is inhibited by halide ions. Hydrolysis to the carbonyl compound is inhibited by hydrogen ions. The knowledge gained by studying the reaction of olefins with pure solutions of palladium salts allows important conclusions to be drawn concerning the action of technical catalyst solutions containing copper and palladium chloride.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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