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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 67 (1995), S. 1472-1476 
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 2
    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 kinetics of the autoxidation of 2,3-dimethylbutadiene (1,3) yielding polymeric peroxides have been investigated and compared with the spontaneous autoxidation of the Me-ester of 10,12-octadecadienoic acid. Both reactions are shown to be of autocatalytical character: the rate of autoxidation is proportional to the square root of mole O2/mole diene. The peroxides split into radicals starting autoxidation chains in a monomolecular manner. The energies activation have been determined.The influences of azoisobutyronitrile, ascaridole, di-tert. -butylperoxide and copper salt of α-ethylcaproic acid on the autoxidation of the Me-ester of 10,12-octadecadienoic acid have been investigated. The result of all is that polymeric peroxides are formed.
    Notes: Die spontane Autoxydation des Dimethylbutadiens, die zu polymeren Peroxyden führt, wird kinetische verfolgt und mit der Autoxydation des konjugierten 10, 12-Octadecadiensäuremethylesters verglichen. Beide Reaktionen verlaufen autokatalytisch. Die Reaktionsgeschwindigkeit ist zu Beginn der Wurzel aus dem Autoxydationsgrad (Mol O2/Mol Substrat) proportional. Die gebildeten Peroxyde zerfallen monomolekular in kettenstartende Radikale. Die Brutto-aktivierungsenergieen werden angegeben.Die Einwirkung von Azodiisobuttersäurenitril, Ascaridol, Di-tert.-Butylperoxyd und Cu++ -oktoat auf die Autoxydation des 10,12-Octadecadiensäuremethylesters wird untersucht. Es ergibt sich, daß auch die Autoxydation des konjugiert-ungesättigten Fettsäure-esters zu polymeren Peroxyden führt.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 3
    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 polymeric peroxides of dimethylbutadiene, isoprene and cyclopentadiene are thermally decomposed and the fragments analyzed. The content of 1,2-structure of the polymeric peroxide of dimethyl-butadiene is about 40-50%, of the polymeric peroxides of isoprene nearly 25%. The polymeric peroxide of cyclopentadiene has only 1,4-structure.The reaction of the polymeric peroxides with perbenzoic acid had been investigated. The presence of peroxy groups in α-position to an ethylenic bond changes their reactivity with perbenzoic acid, decreasing the reactivity of internal double bonds.
    Notes: Die polymeren Peroxyde von Dimethylbutadien, Isopren und Cyclopentadien werden thermisch zersetzt und die erhaltenen Bruchstücke untersucht. Quantitative Bestimmungen von Formaldehyde ergeben, daß das polymere Dimethylbutadienperoxyd zu 40 bis 50%, das polymere Isopreperoxyd zu etwa 25% aus 1,2-Copolymerisaten der Diene mit molekularem Sauerstoff bestehen. Das polymere Cyclopentadienperoxyd entsteht dagegen anscheinend nur durch 1,4-Addition, da der Nachweis des für ein 1,2-Copolymerisat als Zersetzungsprodukt zu erwartenden Glutaconsäuredialdehyds nicht gelang.Es wird außerdem versucht, mit Perbenzoesäure die bei 1,4-Autoxydation zu erwar-tenden kettenständigen Doppelbindungen neben den bei 1,2-Autoxydation zu erwarten-den Vinylseitenketten zu bestimmen. Die Anwesenheit einer peroxydischen Gruppe in α-Stellung zu einer Doppelbindung ändert deren Reaktionsfähigkeit mit der Persäure; sie ist bei kettenständigen Doppelbindungen vermindert.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 18 (1956), S. 406-413 
    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 Me-ester of 9,11-octadecadienoic acid reacts in 1.2 and 1.4-position with moleculare oxygen to give relatively low molecular oxygen-copolymers. These polymeric peroxides produce autocatalyzing effects in the authoxidation reaction. They are rather resistent and can be stored without showing formation of aldehydes. The reaction of perbenzoic acid with external and internal double bounde standing in α-position to peroxy groups was studied at the examples of allyl-tert.-butyl peroxide and cyclohexenylmethyl peroxide.
    Notes: 9,11-Octadecadiensäuremethylester reagiert mit molekularem Sauerstoff in 1,2- und 1,4-Stellung unter Bildung von relative niedermolekularen Sauerstoff-Copolymerisation. Diese polymeren Peroxyde sind bei der Authoxydation autokatalytisch wirksam. Sie sind recht beständig; die buldung von Aldehyden wurde dei der Aufbewahrung nicht beobachtet. Die Reaktion von end- und von kettenständigen Doppelbindungen, die in Nachbarschaft zu Peroxygruppen stechen, mit Perbenzoesäure wird am Beispiel des Allyl-tert.-Butyl- und des Cyclohexenylmethylperoxyds untersucht.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1434-193X
    Keywords: 1,4-Benzoquinones ; [2.2]Paracyclophanes ; 1,4,8,11-Pentacenetetrones ; Cyclic voltammetry ; Radical anions ; ESR/ENDOR spectroscopy ; Intramolecular electron transfer ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three types of tetrone radical anions in which two 1,4-benzoquinone units are connected by ethano (1·-, 2·-), [2.2]paracyclophane (3·-, 4·-), and anthracene bridges (5·-, 6·-) have been studied by ESR and ENDOR spectroscopy. The displacement of the unpaired electron over the two π moieties in the [2.2]cyclophane radical anions 1·--4·- and the marked difference between the first and second reduction potentials, ΔE = |E20 - E10| ≥ 0.20 V, are evidence for a substantial intramolecular electronic interaction between the two electrophores. Similar ΔE data for the syn- (3) and anti-naphthalenophanes (4) indicate that most of the intramolecular electronic interaction takes place through the [2.2]paracyclophane bridge. When ion pairing is inhibited by complexation of the cation, the unpaired electron in 5·- and 6·- is also delocalized over the whole pentacenetetrone system at temperatures as low as 160 K.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1434-193X
    Keywords: Paracyclophanes ; Cyclic voltammetry ; Radical cations ; ESR/ENDOR spectroscopy ; Intramolecular electron transfer ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A range of [n.n]paracyclophane radical cations (4·+-12·+), in which two 2,5-dimethoxy-1,4-phenylene units are connected by alkano bridges of varying length, have been studied by ESR and ENDOR spectroscopy. In the [2.2]- and [3.3]paracyclophane radical cations 4·+-6·+, 10·+ and 11·+ the delocalization of the unpaired electron over both π-moieties and the distinct difference between the first and second oxidation potentials, ΔE = E20 - E10, are evidence for a strong intramolecular electronic interaction between the two electrophores. The [5.5] and [7.7] species (8·+ and 9·+) are localized radical cations at low temperature (ca. 220 K). At room temperature, the higher molecular flexibility leads to a significant increase in the number of internal collisions between the electrophores, resulting in a fast (ESR time scale) intramolecular electron transfer. The intermediate [4.4]paracyclophane radical cations 7·+ and 12·+ are apparently also localized radical cations. The close interplanar distance between the two π-moieties, however, facilitates their mutual contacts. In 7·+, the intramolecular electron transfer becomes fast on the ESR time scale at room temperature; in 12·+ the transfer is fast over the temperature range 200-300 K.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1434-193X
    Keywords: [2.2](1,4)Naphthalenophanes ; [2.2](1,4)Anthracenophane ; Pentacene ; Cyclic voltammetry ; Radical cations ; ESR/ENDOR spectroscopy ; Intramolecular electron transfer ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various radical cations, in which two terminal 1,4-dimethoxybenzene units are anellated to [2.2]paracyclophane (2b•+, 3b•+), [2.2](1,4)naphthalenophane (4d•+), and anthracene bridges (5•+), have been studied by ESR and ENDOR spectroscopy. In the syn- and anti-naphthalenophane radical cations 2b•+ and 3b•+ the delocalization of the unpaired electron over both π-moieties and the distinct difference between the first and second oxidation potentials, ΔE = E20 - E10, are evidence for a substantial intramolecular electronic interaction between the two electrophores. Extension of the bridge in 4d•+ and 5 by benzo anellation results in a localized radical cation. Strong intramolecular electronic interaction between the two electrophores is found in the 1,4,8,11-tetramethoxy-pentacene radical cation (5•+). The syntheses of 4d are described.
    Type of Medium: Electronic Resource
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