O-H Bond Dissociation Energies of Phenolic Compounds are Determined by Field/Inductive Effect or Resonance Effect?A DFT Study and Its Implication
✍ Scribed by Zhang, Hong-Yu ;Sun, You-Min ;Chen, De-Zhan
- Publisher
- John Wiley and Sons
- Year
- 2001
- Tongue
- English
- Weight
- 289 KB
- Volume
- 20
- Category
- Article
- ISSN
- 1611-020X
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✦ Synopsis
The electronic effects on O-H bond dissociation energy (BDE) of phenolic compounds have been investigated by a density functional theory (DFT) calculation on 6-31G(d, p) basis set. For para substituted phenols, the stability of phenoxy radical (SPR), the stability of parent molecule (SPM) and the relative O-H BDE correlate well with Hammett-type parameter s þ p and resonance parameter R þ .
Therefore, the O-H BDE is mainly governed by the resonance effect. But, only the resonance effect of electron-donating group reduces the O-H BDE, and on the contrary, the resonance effect of electron-withdrawing group increases the O-H BDE. Accordingly, the existing structure-activity relationship (SAR) for flavonoids to scavenge free radicals were questioned.