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  • 1
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (o-Hydroxyphenyl)methylphosphonic acids are readily obtained from o-(bromomethyl)- or o-(hydroxymethyl)phenols and trialkyl phosphites. Subsequent hydrolysis leads to the corresponding phosphonic acids. For a series of such compounds, the pKa values have been determined by potentiometry. Their dependence on additional substituents in the aromatic ring is discussed in terms of electronic and steric effects.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: UV/VIS Absorption spectra of nitrosubsituted (o-hydroxyphenyl)methylphosphonic acids (o-(phosphonomethyl)phenols) were measured as a function of pH at 25° in 0.1M NaClo4 solutions. Computational treatment of the whole set of optical density data between 200 and 500 nm resulted in the determination of the dissociation constants of these polyacids and also of the individual electronic spectra of all the species involved in the deprotonation sequence. The spectral behavior gives information on the structure of the anions formed and consequently the order of the subsequent deprotonation steps could be deduced. For the (2-hydroxy-3-nitro(or 5-nitro)phenyl)methylphosphonic acid and the 2-hydroxy-5-nitro-1,3-phenylenebis(methylphosphonic acid), the phenolic proton dissociates in the last step, while, in the case of (2-hydroxy-3,5-dinitrophenyl)methylphosphonic acid, the last dissociating proton comes from a P—OH group. An intermediate situation is found for (3-chloro-2-hydroxy-5-nitrophenyl)methylphosphonic acid. Generally, the deprotonation sequence is governed by intramolecular H-bonds involving the phenolic OH group.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0009-2940
    Keywords: Carbene complexes ; Metallacycles ; Claisen rearrangement ; Cascade reaction ; Cyclopentenones ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cationic ferracyclic carbene complexes 1 react with carbon nucleophiles like lithium enolates and organocuprates to give the corresponding 4-substituted 1, (3E)-diene tricarbonyl-iron complexes 6 and 9. The reaction is thought to proceed by initial attack on the allyl terminus and subsequent ferra Claisen-Ireland rearrangement of the intermediate (η2 alkene)carbene complex 4. This rationale is supported by the isolation and characterisation of analogous aminooxocarbene derivatives 8. With sterically demanding enolates products 6 are formed in diastereomeric ratios of up to 90:10, thus demonstrating the inductive power of the chiral metallacycle in 1. Lithium acetylides as carbon nucleophiles react with 1 according to a novel cascade to give regio- and stereospecifically 2,5,5-trisubstituted-cyclopentenones 10 suggesting a concerted formation of four C=C bonds together with a CO insertion and a formal carbene transfer step.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 427-432 
    ISSN: 0009-2940
    Keywords: [1n]Metabiphenylophanes ; Calixarenes ; Spherands ; Diastereoselectivity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Condensation of 5,5′-di-tert-butyl-2,2′-dihydroxybiphenyl (1) with formaldehyde yields a cyclic trimer 2 (and tetramer 3) having three (four) methylene groups less than a calix[6]-arene (calix[8]arene). Alkylation of the (flexible) trimer with ethyl bromoacetate gives exclusively the stereoisomer 4 with C2 symmetry, while the isomer with D3 symmetry is not observed. Two isomers 6a and 6b (C2 and C1 symmetry) are obtained by treatment with tert-butyl bromoacetate which both are converted by transesterification with methanol into the same hexamethyl ester 5 having C2 symmetry. These results are rationalized by restricted rotation around Ar—Ar bonds for larger O-alkyl groups also around Ar—CH2—Ar bonds. The structure of the hexaethyl ester 4 is also confirmed by single crystal X-ray analysis.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 25 (1991), S. 195-207 
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Als Calixarene werden cyclische Kondensationsprodukte aus para-substituierten Phenolen und Formaldehyd bezeichnet. Vor allem wegen ihrer Rezeptoreigenschaften für Ionen und neutrale Moleküle nimmt das Interesse an ihnen immer noch zu. Einsatzmöglichkeiten zeichnen sich in den unterschiedlichsten Bereichen ab: Ob als neuartige Katalysatoren oder als Antioxidantien, ob als stationäre Phasen in der Chromatographie oder als Additive in Klebstoffen, die Palette der Möglichkeiten ist so groß wie die Variationsbreite in der chemischen Struktur von Calixarenen.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 174 (1973), S. 239-242 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 175 (1974), S. 2255-2274 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The Fries rearrangement of the acetates 2a-c, 3b, 4b, and 4d of six hydroxybenzylphenol derivatives was investigated between 40 and 70°C using AlCl3 as catalyst and nitrobenzene as solvent. Besides the expected main products of the Fries rearrangement also intermediates and products formed by side reactions were isolated by column chromatography, showing the partial saponification of ester bonds to be a probable side reaction. The migration of an acetyl group to the neighbouring phenolic unit of the same molecule could not be observed. All the compounds, including the starting substances, were characterized by their IR- and 1H-NMR-spectra.
    Notes: An den Acetaten 2a-c, 3b, 4b und 4d von sechs Hydroxybenzylphenol-Derivaten wurde die Friessche Verschiebung mit AlCl3 als Katalysator in Nitrobenzol bei Temperaturen zwischen 40 und 70°C durchgeführt. Neben den zu erwartenden Hauptprodukten der Friesschen Verschiebung konnte durch Säulenchromatographie eine Reihe von Zwischen- und Nebenprodukten isoliert werden. Daraus ging hervor, daß wahrscheinlich eine teilweise Verseifung der Acetate als Nebenreaktion stattfindet. Eine Wanderung der Acetylgruppe an den benachbarten Phenolbaustein des gleichen Moleküls konnte nicht beobachtet werden. Sämtliche Verbindungen, einschließlich der Ausgangsprodukte, wurden durch ihre IR- und 1H-NMR-Spektren charakterisiert.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Chlormethylated nitrophenols as well as mono- and bischloromethylated bis- and tris[(hydroxy-5-nitro-1,3-phenylene)methylene] compounds were used to synthesize oligo[(hydroxy-5-nitro-1,3-phenylene)methylene]s. Chloromethylation was achieved by reaction with chloromethyl methyl ether in the presence of zinc chloride. The synthesis of the oligomeric compounds was possible with good yields by condensation of the chloromethylated compounds with a large excess of nitrophenol and zinc chloride as catalyst. Reaction conditions and different reactivities are reported. The structures of some compounds were confirmed by independent syntheses. Thus, also the structures of those compounds were ensured which are connected by unequivocal preparations with the independently synthesized compounds. All together 47 new oligo[(hydroxy-5-nitro-1,3-phenylene)methylene]s could be prepared, among them 12 dinuclear, 20 trinuclear, 13 tetranuclear and 2 pentanuclear compounds.
    Notes: Zur Synthese der Oligo[(hydroxy-5-nitro-1,3-phenylen)methylen]e dienten chlormethylierte Nitrophenole sowie mono- und bischlormethylierte Bis- und Tris[(hydroxy-5-nitro-1,3-phenylen)methylen]e. Die Chlormethylierung erfolgte durch Umsetzung mit Chlormethylmethyläther in Gegenwart von Zinkchlorid. Die Synthese der Oligomeren gelang mit guten Ausbeuten, wenn die chlormethylierten Verbindungen mit stark überschüssigem Nitrophenol und Zinkchlorid als Katalysator kondensiert wurden. Reaktionsbedingungen und unterschiedliche Reaktionsfähigkeiten werden mitgeteilt. Einige Verbindungen wurden in ihrer Struktur bestätigt, indem sie auf zwei voneinander unabhängigen Wegen dargestellt wurden. Damit waren auch die Strukturen jener Verbindungen gesichert, die in eindeutig verlaufender Synthese mit den doppelt dargestellten Verbindungen zusammenhängen. Insgesamt konnten 47 neue Oligo[(hydroxy-5-nitro-1,3-phenylen)methylen]e synthetisiert werden, darunter 12 Zweikern-, 20 Dreikern-, 13 Vierkern- und 2 Fünfkernverbindungen.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 2539-2542 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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