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  • Articles: DFG German National Licenses  (18)
  • 1975-1979  (7)
  • 1960-1964  (11)
  • 1920-1924
  • Dyes/Pigments
  • Heterocycles
  • 1
    ISSN: 1434-4475
    Keywords: Enamines, synthesis ; Heterocycles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Condensation of alkyl γ-haloacetoacetates (or γ-chloroacetoacetanilide) with triethoxymethane and primary (hetero)aromatic amines gives in a one step synthesis under mild conditions new β,β-diacyl-enamines (2 a-m, 3 a-d). In contrast, the N-alkylsubstituted derivatives could be synthesized only in a two step procedurevia the enolethers6 a, b. According to their ir-specra, most of the aminomethylene-γ-haloacetoacetic acid derivatives are stereochemically fixed either in theE- orZ-form. The pmr-spectra, however, show that they exist as mixtures of at least two isomers in solution. With KOH or sodium acetate, a ring closure to 3-hydroxy-pyrroles (8, 9) could be achieved whereas with pyridine only quarternary pyridinium salts (11) are formed. Acidic (orLewis acidic) condensing agents leave the chloroacetyl group unaffected and give either free carboxylic acids (2 p-r) pyrido-[1,2-a]pyrimidones (12) or 4-quinolones (13), depending on the type of the molecule and the reaction temperatures employed.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 18 (1979), S. 1-19 
    ISSN: 0570-0833
    Keywords: Areno-analogy ; Heterocyclopolyaromatic compounds ; Heterocycles ; Heteroaromatic compounds ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organometallic linkage of heteroaromatic compounds provided a means of synthesizing complicated combinations of heteroaromatic compounds; not only nucleophilic aromatic substitution, but also “Ar—Cu/Ar—Hal linkage”, “organometallic oxidative linkage”, and “metal amide linkage” have been employed. The heterocyclopolyaromatic compounds are made of one, two, or three kinds of heteroaromatic species as ring members. These syntheses illustrate the construction of heterocycles from large, performed structural units. Competition experiments showed that the reactivity typical of the individual species is enhanced in open-chain combinations (ArNu)n and (ArE)n (ArNu, ArE: nucleo- and electrophilic heteroaromatic systems, respectively); the opposite situation is mostly encountered in the case of ArNu—AE combinations. - Cycloocta[1,2-b:4,3-b′5,6-b″:8,7-b‴]tetrathiophene, the only heterocyclopolyaromatic system yet to have been studied in detail, proved surprisingly inclined to undergo monosubstitution reactions.
    Additional Material: 3 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 16 (1977), S. 835-851 
    ISSN: 0570-0833
    Keywords: Cycloelimination ; Nitrogen cycloelimination ; Carbenes ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclic azo compounds including heteroaromatics with a N=N bond of strong double-bond character can eliminate molecular nitrogen on addition of sufficient thermal energy or on electronic excitation. Some substrates decompose spontaneously, others are moderately or even extremely resistant to N2-elimination. From a preparative point of view this type of reaction opens a variety of interesting possibilities, e.g. the synthesis of small carbocycles or heterocycles, strained bi- and polycycles, as well as cage compounds. From a theoretical mechanistic viewpoint, current importance attaches to the primary fragments such as carbenes, diradicals, trimethylene, trimethylenemethane, dipoles, ylides, antiaromatic 4π-systems, unstable cycloalkynes, and arynes.
    Additional Material: 5 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 14 (1975), S. 688-698 
    ISSN: 0570-0833
    Keywords: Dyes/Pigments ; Colorimetry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Although man has used pigments to impart color to his surroundings since prehistoric times, it is only in the 20th century that methods for objective testing and evaluation of their optical properties have become available. Colorimetry and color-order systems based on principles of color perception, in particular the Adams-Nickerson system, which form the basis of these methods are described, and are followed by a discussion of the theories of light absorption and light scattering, in particular of the Kubelka-Munk theory. Of the important optical pigment properties chromaticity and color difference, tinting strength and lightening power (of white pigments), and the hiding power of colored and uncolored coatings are discussed on the basis of the testing methods. Sweeping developments in computer technology during recent years have contributed significantly to the present advanced status of testing practice; further progress in testing methods may be expected in the future as our understanding of the visual process improves.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0570-0833
    Keywords: Heterocycles ; Aromaticity ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The terms “aromatic” and “antiaromatic” have attracted widespread interest in recent years. After all the discussion about the meaning of words, one fact remains: the energy content of planar systems displaying cyclic electron delocalization depends upon the number of, and the orbital interactions between, the participating electrons. The concept underlying this progress report is that the electronic destabilization of systems having eight π-electrons should be especially pronounced in the case of six-membered rings for steric and electronic reasons. Such systems are found primarily in anionic, but also in neutral, heterocycles containing hetero ring members which possess electron pairs capable of delocalizing into the π-system. The production and reactivity of such systems are investigated and their biological significance discussed.
    Additional Material: 4 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 14 (1975), S. 665-679 
    ISSN: 0570-0833
    Keywords: Heterocycles ; Optical brighteners ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Optical brighteners are used in detergents, textiles, paper, plastics, and paints. Most optical brighteners contain heterocycles such as coumarins, 2-pyrazolines, naphthalimides, pyrazoles, triazoles, oxadiazoles, and triazines. In this article the syntheses, properties, and applications of new optical brighteners are described with references to patent literature.
    Additional Material: 7 Tab.
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  • 7
    ISSN: 0570-0833
    Keywords: Phosphinidenes ; Phosphanediyl compounds ; Heterocycles ; Cyclophosphanes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Formation and detection of phosphinidenes (R—P̈:) in the decomposition of cyclophosphanes and in the reaction of dichlorophosphanes with metals are considered critically. Only in the thermolysis of pentaphenylcyclopentaphosphane can phenylphosphinidene be detected with certainty by pyrolysis-mass spectroscopy. “Trapping reactions” such as “insertion” into S—S or As—As bonds, and addition reactions with 1,2-diketones, 1,3-dienes, or alkynes can also be interpreted without the assumption of free phosphinidenes. The pyrolysis products of cyclophosphanes add to 1,3-dienes and alkynes, yielding five- and six-membered heterocycles that contain one to three phosphorus atoms.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 408-416 
    ISSN: 0570-0833
    Keywords: Reactive dyes ; Dyes/Pigments ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two new groups of reactive dyestuffs have been developed. One group (Levafix® dyes) comprises compounds which contain —SO2NH—CH2—CH2—OSO3H or —CH2—N(alkyl)-CH2—CH2—OSO3H as reactive groups. The dyes of this group react with cellulose fibers to form cellulose ethers, e.g. R—SO2NH—CH2—CH2—O—cellulose. The substances in the second group (Levafix-E® dyes) consist of the amides formed from 2,3-dichloroquinoxaline-6-carboxylic acid and dyestuffs containing primary or secondary amino groups.
    Additional Material: 3 Ill.
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  • 9
    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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  • 10
    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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  • 11
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 20-23 
    ISSN: 0570-0833
    Keywords: Reactive dyes ; Dyes/Pigments ; Reactive dyes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Compounds and dyes containing vinylsulfonyl groups or groupings which readily yield vinylsulfonyl groups possess a marked ability to add onto many compounds containing active hydrogen under alkaline conditions. They also react with natural substances of high molecular weight, e.g. wool and cellulose, which contain amino- or hydroxyl groups. These reactions lead to the formation of strong covalent bonds between the reactants. As a result of this finding, reactive dyes for nitrogenous and cellulose fibers have been developed.
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  • 12
    ISSN: 0570-0833
    Keywords: Polycondensation ; Dyes/Pigments ; Bunte salts ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dyes which contain only thiosulfate residues as water-solubilizing groups are readily polycondensed on cellulose under mild conditions in the presence of condensing agents such as sodium sulfide to give insoluble, high molecular-weight dyes. This type of fixation leads to wash-fast dyeings and, in contrast to reactive dyes, involves no reaction with the fiber. The preparation and application of the dyes are described.
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  • 13
    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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  • 14
    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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  • 15
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 41-45 
    ISSN: 0570-0833
    Keywords: Dyes/Pigments ; Rutile structure ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Until the present time, new color pigments have been developed by isotypic and homotypic mixed-phase formation. This paper deals primarily with heterotypic mixed-phase formation for the preparation of new colored and white pigments with the rutile structure. Dioxides and difluorides crystallizing in the rutile lattice-form were chosen as host-lattices for the mixed-phase formation. Hosts of the general formula AB2 can accommodate, as guests, in the form of solid solutions, oxides and/or fluorides with different structures. Characteristically, the mean statistical cation-radius lies between 0.55 and 0.98 Å, with single radii between 0.46 and 0.98 Å. Relative quantities are so chosen that the cation to anion ratio of 1:2 prescribed by the host lattice, as well as electroneutrality, is maintained.
    Additional Material: 6 Ill.
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  • 16
    ISSN: 0570-0833
    Keywords: Azo dyes ; Dyes/Pigments ; Oxidative coupling ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New findings in the field of oxidative coupling reactions are reported. These involve: extension of this type of reaction to amidrazone system displaying (vinylogous) tautomerism and to unsymmetrical diarylhydrazines; elucidation of the coupling mechanism for these arylhydrazines and for the amidrazone systems previously described; the properties of some dyes, complexed with heavy metals, and the synthesis of tetraazapentamethine and penta-azapentamethine dyes.
    Additional Material: 1 Tab.
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  • 17
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 532-537 
    ISSN: 0570-0833
    Keywords: Polyacrylonitrile ; Fibers ; Azatrimethinecyanines ; Dyes/Pigments ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Like all basic dyes, azatrimethinecyanines possess a good dyeing affinity for acrylic fibers. Compounds with isolated nitrogen atoms in the trimethine chain show insufficient light fastness, whereas good to excellent fastness to light is displayed by compounds having neighboring nitrogen atoms in the chain. Thus, a working hypothesis stating that the light fastness of trimethinecyanines on acrylic fibers is improved by progressive replacement of methine groups by nitrogen atoms has been partially confirmed.
    Additional Material: 3 Tab.
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  • 18
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 568-572 
    ISSN: 0570-0833
    Keywords: Trichloropyrimidyl dyes ; Dyes/Pigments ; Dichloropyrimidyl dyes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several examples are used to show that the reactivity of dichloro- and trichloropyrimidyl dyes and the sensitivity of their dyeings to hydrolysis are determined by the nature of the bridge unit between the chromophore and the reactive system. The tendency of the dyeings to hydrolyze in acid and, more particularly, in alkaline media increases with increasing reactivity of the dyes. In alkaline media, dyeings made with dyes containing oxygen bridges are cleaved mainly between the reactive system and the chromophore, while in dyeings made with dyes containing imino or methylimino bridges, the linkage between the reactive system and the cellulose is hydrolyzed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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