Antioxidants and stabilizers. XLIII. Structure of phenolic antioxidants and infrared spectra of the hydroxyl groups

Pivcová, H.; Jiráčková, L.; Pospı́šil, J.

doi:10.1002/polc.5070400132

Cited by 4 publications

(2 citation statements)

References 13 publications

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“…It was suggested that BIS adopted a number of conformations that “may be in equilibrium.” 23 The O−H bands were assigned to “free” OH, to OH hydrogen bonded to the “other” aromatic ring, OH−Ar, and to OH hydrogen bonded to the “other” OH group, OH−OH . The presence of four O−H stretching bands has been confirmed in three later publications, − though their reported frequencies in CCl 4 and the conformers suggested were not always in agreement…”

Section: Discussionmentioning

confidence: 93%

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Abnormal Solvent Effects on Hydrogen Atom Abstraction. 3. Novel Kinetics in Sequential Proton Loss Electron Transfer Chemistry

2005

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Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. Questions? Contact the NRC Publications Archive team atPublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information. NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. NRC Publications Record / Notice d'Archives des publications de CNRC:http://nparc.cisti-icist.nrc-cnrc.gc.ca/eng/view/object/?id=21b8dc7b-d32d-4f84-a5fb-75743ca35d88 http://nparc.cisti-icist.nrc-cnrc.gc.ca/fra/voir/objet/?id=21b8dc7b-d32d-4f84-a5fb-75743ca35d88 A prolonged search involving several dozen phenols, each in numerous solvents, for an ArOH/2,2-diphenyl-1-picrylhydrazyl (dpph • ) reaction that is first-order in ArOH but zero-order in dpph • has reached a successful conclusion. These unusual kinetics are followed by 2,2′-methylene-bis(4-methyl-6-tert-butylphenol), BIS, in five solvents (acetonitrile, benzonitrile, acetone, cyclohexanone, and DMSO). In 15 other solvents the reactions were first-order in both BIS and dpph • (i.e., the reactions followed "normal" kinetics). The zero-order kinetics indicate that in the five named solvents the BIS/dpph • reaction occurs by sequential proton loss electron transfer (SPLET). This mechanism is not uncommon for ArOH/dpph BIS. Some properties specific to BIS that may be relevant to its relatively slow ionization in the five solvents are considered. Abnormal Solvent Effects on Hydrogen Atom Abstraction. 3. Novel Kinetics in Sequential Proton Loss Electron Transfer Chemistry

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Section: Discussionmentioning

confidence: 93%

“…Band maximum frequencies (in cm -1 ): 3639, 3620, 3516, 3450 (ref ); 3648, 3623, 3516, 3444 (ref ); 3627, 3610, 3506, 3436 (ref ); 3651, 3635, 3516, 3454 (ref ). Our work (Figure and Scheme ) yields: 3632, 3610, 3510, 3450.…”

Section: Referencesmentioning

confidence: 99%

Abnormal Solvent Effects on Hydrogen Atom Abstraction. 3. Novel Kinetics in Sequential Proton Loss Electron Transfer Chemistry

2005

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Antioxidants and stabilizers, 116 Influence of the carbon black chezacarb EC on polyolefin thermooxidation: A model study with cyclohexene doped with chain‐breaking antioxidants

Rotschová

Pospı́šil

1992

Angew. Makromol. Chem.

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The ageing of polyolefins is accelerated by carbon black Chezacarb EC used as a filler. Conditions for selection of suitable chain-breaking antioxidants protecting against degradation were simulated using cyclohexene doped with various amounts of carbon black and oxidized at 60°C. The results obtained reveal an acceleration of cyclohexene oxidation in the phase following the induction period (IP). The oxidation acceleration is similar to the effect caused by powdered copper(0) or copper(I1) ions. Polynuclear phenolic antioxidants are able to stabilize cyclohexene for periods longer than 120 h only in the presence of low amounts of Chezacarb (up to 0.5 wt.-"0). At higher Chezacarb concentrations, merely a prolongation of IP may be achieved. Arylene diamines are efficient stabilizers only if combined with a high concentration of Chezacarb (10 wt.4'0). None of the chain-breaking antioxidants used was able to diminish the oxidation rate of cyclohexene in the phase after IP. ZUSAMMENFASSUNG:Die oxidative Alterung von Polyolefinen wird durch RUB, Chezacarb EC, als Fullstoff beschleunigt. Die Bedingungen fur die Auswahl von geeigneten kettenabbrechenden Antioxidantien wurden mittels Cyclohexen, das mit verschiedenen Mengen von RUB versetzt und bei 60°C oxidiert wurde, simuliert. Die Resultate zeigen eine Beschleunigung der Oxidation des Cyclohexens in der Phase nach der Induktionsperiode (IP). Die Oxidationsbeschleunigung ist dem katalytischen Effekt von Kupfer (0)-Pulver oder Kupfer(I1)-Ionen ahnlich. Mehrkernige phenolische Antioxidantien konnen Cyclohexen fur einen langeren Zeitabschnitt als 120 h nur in Anwesenheit von kleinen Mengen Chezacarb (bis 0,5 Gew.-%) stabilisieren. Nur eine Verlangerung der IP wurde bei hoheren Konzentrationen von RUB beobachtet. Arylendiamine stabilisieren wirksam nur in Anwesenheit von einer hoheren Konzentration (10 Gew.-%) von Cheza-* Part 115 cf. ref.lg.

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Eight‐membered organosulfur heterocycles. Synthesis of dibenzo[d,g][1,3,6,2]dioxathiaphosphocin and dibenzo[d,g][1,3,6,2]dioxathiasilocin ring systems

Pastor¹,

Spivack²,

Steinhuebel³

1984

Journal of Heterocyclic Chem

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Antioxidants and stabilizers. XLIII. Structure of phenolic antioxidants and infrared spectra of the hydroxyl groups

Cited by 4 publications

References 13 publications

Abnormal Solvent Effects on Hydrogen Atom Abstraction. 3. Novel Kinetics in Sequential Proton Loss Electron Transfer Chemistry

Abnormal Solvent Effects on Hydrogen Atom Abstraction. 3. Novel Kinetics in Sequential Proton Loss Electron Transfer Chemistry

Antioxidants and stabilizers, 116 Influence of the carbon black chezacarb EC on polyolefin thermooxidation: A model study with cyclohexene doped with chain‐breaking antioxidants

Eight‐membered organosulfur heterocycles. Synthesis of dibenzo[d,g][1,3,6,2]dioxathiaphosphocin and dibenzo[d,g][1,3,6,2]dioxathiasilocin ring systems

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