On NMR prediction of the effectiveness of p-phenylenediamine antioxidants

Puškárová, Ingrid; Šoral, Michal; Breza, Martin

doi:10.1016/j.cplett.2015.09.013

Cited by 11 publications

(12 citation statements)

References 28 publications

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“…NMR data for N-(1,3-dimethyl-butyl)-N'-phenylbenzene-1,4-diamine (6PPD) were taken from [20]. The NMR spectral assignment of the remaining compounds was straightforward.…”

Section: Nmr Analysismentioning

confidence: 99%

“…For their most stable conformations we have calculated absolute shielding values, σ(X), for all atoms X. Analogously to [20] we have performed the least- Table S11.…”

Section: Calculationsmentioning

confidence: 99%

“…In our laboratory we have investigated p-phenylenediamine antioxidants by Density Functional Theory (DFT) model studies as well [9, 10, 12, 16 -20] our previous study on a series of four p-phenylene diamine antioxidants [20] we have found a linear dependence of AEM values measured at 180 ºC on NMR shifts of nitrogen atoms, hydrogen atoms bonded to them and probably also tertiary aliphatic carbon atoms bonded to nitrogens. The conformation dependence of these NMR shifts obtained by quantum-chemical B3LYP calculations is vanishing and so it is sufficient to evaluate them for the most stable conformations of the studied molecules in vacuum only.…”

Section: Introductionmentioning

confidence: 97%

“…Unfortunately, the above mentioned compound series [20] is too small and the conclusions must be verified on a larger number of antioxidants. The aim of this manuscript is to correlate the AEM values of a series of p-substituted diphenyl amines, which were studied as antioxidants [13] at 25 ºC and 130 ºC (see Table 1), with NMR data obtained experimentally as well as calculated by DFT method.…”

Section: Introductionmentioning

confidence: 98%

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On NMR prediction of the antioxidant effectiveness of p-substituted diphenyl amines

Puškárová

Šoral

Breza

2016

Polymer Degradation and Stability

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“…NMR data for N-(1,3-dimethyl-butyl)-N'-phenylbenzene-1,4-diamine (6PPD) were taken from [20]. The NMR spectral assignment of the remaining compounds was straightforward.…”

Section: Nmr Analysismentioning

confidence: 99%

“…For their most stable conformations we have calculated absolute shielding values, σ(X), for all atoms X. Analogously to [20] we have performed the least- Table S11.…”

Section: Calculationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 98%

See 2 more Smart Citations

On NMR prediction of the antioxidant effectiveness of p-substituted diphenyl amines

Puškárová

Šoral

Breza

2016

Polymer Degradation and Stability

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“…Real PPD structures in the protected materials significantly depend on solid state effects and so it is very problematic to find suitable characteristics of the PPD molecules which not much depend on their conformations. In our previous study (Puškárová, 2015) we have investigated experimentally and evaluated by B3LYP calculations the NMR shifts of several PPD antioxidants in DMSO. We have found that their AEM increases with NMR shifts of both amine hydrogens, of the nitrogen between aromatic rings and probably of the tertiary carbon atom neighboring to the nitrogen between aromatic ring and the side aliphatic chain in agreement with the above mentioned theory of Simon et al (Cibulková, 2005a;Cibulková, 2005b;Polovková, 2006;Gatial, 2007;Cibulková, 2009;Rapta, 2009;Cibulková, 2010;.…”

Section: Introductionmentioning

confidence: 99%

Antioxidant effectiveness of dehydrogenated p-phenylene diamines through NMR calculations

Puškárová

Breza

2016

Acta Chimica Slovaca

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NMR shifts of N-phenyl-N'-alkyl-p-phenylenediamines (PPD) in vacuum were evaluated by B3LYP calculations using GIAO method. According to our previous studies, the Molar Antioxidant Effectiveness (AEM) of PPD antioxidants correlates with NMR chemical shifts of the amine nitrogen between aromatic rings (N A ), the side aliphatic chain nitrogen (N B ) and its neighboring tertiary carbon atom (C T ) as well as of the hydrogens bonded to them. Our results indicate that the above mentioned chemical shifts correlate with increasing reactivity of dehydrogenated PPD antioxidants at these sites as well.

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Quantum‐chemical studies of the antioxidant effectiveness of para‐phenylene diamines

Breza

Jelemenská

2022

Vinyl Additive Technology

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The purpose of this review is to highlight how the antioxidant effectiveness (AE) of rubber additives can be quantitatively interpreted using results from quantum‐chemical calculations. The relationships between the AE of para‐phenylene diamines (PPD), evaluated through non‐isothermal differential scanning calorimetry measurements in styrene‐butadiene and polyisoprene rubber matrices, and various parameters obtained by quantum‐chemical calculations are reviewed. The N atom between both phenyl rings (A site) is more significant than the N atom between the phenyl ring and the alkyl chain (B site). The preferred formation of ketimine structures (instead of the quinonediimine ones) during dehydrogenation despite the higher stability of the NA‐centered radicals indicates a kinetic control of the antioxidant action. In most cases, the AE decreases with the strength of the NA–HA bond and increases with the chemical shifts of NA and HA. In hypothetical Cu(II) complexes, the AE rises with the affinity of NA to Cu, and the extent of electron density transfer from NA to Cu. Most deviations from linearity might be explained by steric hindrances. Reverse trends for the NA and NB chemical shifts are observed, despite the fact that similar reactions are supposed at both sites.

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On NMR prediction of the effectiveness of p-phenylenediamine antioxidants

Cited by 11 publications

References 28 publications

On NMR prediction of the antioxidant effectiveness of p-substituted diphenyl amines

On NMR prediction of the antioxidant effectiveness of p-substituted diphenyl amines

Antioxidant effectiveness of dehydrogenated p-phenylene diamines through NMR calculations

Quantum‐chemical studies of the antioxidant effectiveness of para‐phenylene diamines

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