The keto/enol equilibrium of phenol. An ab initio investigation

Gadosy, Timothy A.; McClelland, Robert A.

doi:10.1016/s0166-1280(96)04694-5

Cited by 25 publications

(31 citation statements)

References 13 publications

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“…The results were compared to the phenol geometry obtained using the restricted Hartree-Fock level of theory and the second order Møller Plesset (MP2) formalism. We found an average C-C bond length of 1.395 Å, to be compared to 1.384 Å obtained by Gadosy and McClelland [20].…”

Section: Methodssupporting

confidence: 75%

Coverage effects on phenol adsorption on Si(100)2×1 as: A first principle calculation

2009

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Section: Methodssupporting

confidence: 75%

Coverage effects on phenol adsorption on Si(100)2×1 as: A first principle calculation

2009

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“…The results were compared to the phenol geometry obtained using the restricted Hartree-Fock level of theory and the second-order Møller-Plesset formalism. 35 We found an average C-C bond length of 1.395 Å, to be compared to 1.384 Å obtained by Gadosy and McClelland. 32 We optimized the geometry of the Si surface starting from symmetric dimers and allowing the first two layers to fully relax.…”

Section: Methodssupporting

confidence: 71%

Dissociative versus molecular adsorption of phenol onSi(100)2×1: A first-principles calculation

2007

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We investigated the competitive adsorption of a bifunctional molecule, phenol, on Si͑100͒2 ϫ 1 by ab initio calculations. We performed geometry optimizations of phenol adsorbed either molecularly or dissociatively, on five possible sites ͑top, bridge, valley bridge, cave, and pedestal͒, in the low coverage regime. We found that the dissociative adsorption of phenol on top of a silicon dimer is the most favorable adsorption configuration. In the group of dissociative adsorption the phenol initially placed on the bridge or the valley-bridge sites ends up as a toplike local minima. The pedestal and cave sites remain as low-adsorption energy "open" sites. In the group of molecular adsorption, a higher adsorption energy is associated to the adsorption through an addition reaction and loss of the aromatic character ͑bridge, valley-bridge, and pedestal sites͒. Standard butterfly or diagonal butterfly are the corresponding optimized geometries. Retention of aromatic character and lower adsorption energy are associated to the adsorption on the top and cave sites. The ordering of adsorption sites according to the adsorption energy shows a mixture of the dissociative and the molecular sites. In the case of adsorption on the top site, the adsorption energies after a rotation of the phenoxy fragment along the bonding axis and hydrogen migration on the surface are very similar. The bend of the phenoxy fragment on the surface, instead, is not favored ͑the adsorption energy is 1.004 eV lower compared to the vertical position͒. Different electron density maps were calculated for different adsorption sites and modes. Finally, we investigated the possibility that molecularly adsorbed phenol behaves as a precursor for the dissociative one by nudged elastic band calculations. We found a barrier of the same order of magnitude of the thermodynamic energy at room temperature for the conversion of the valley-bridge molecular into the top dissociative site.

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“…Both cyclohexa-2,4-dien-1-one 27 and cyclohexa-2,5-dien-1-one 28 Let us remember that the energy difference between phenol 26 and both keto isomers 27 and 28 amount to 73 and 69 kJ mol −1 , respectively ( Figure 31). The contribution of entropy is small, amounting to S = −9 and −1 J mol −1 K −1 , for both ketonization reactions, respectively, and this also leads to an estimate for the equilibrium constant of the enolization, pK E , ranging from −12 to −13, of the same order of magnitude as the experimental results in aqueous solution 186,187,469 . It should be stressed that such similarity of values in both gaseous and condensed phases should not be considered as an 'agreement' and need to be treated with much caution, due to the fact that the solvent effect on the equilibrium has not been taken into account.…”

Section: Keto-enol Interconversionsupporting

confidence: 60%

General and Theoretical Aspects of Phenols

Nguyen

Kryachko

Vanquickenborne

2009

Patai's Chemistry of Functional Groups

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Introduction Molecular Structure and Bonding of Phenol Structures and Properties of Substituted Phenols Energetics of some Fundamental Processes Hydrogen Bonding Abilities of Phenols Open Theoretical Problems Acknowledgements

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The keto/enol equilibrium of phenol. An ab initio investigation

Cited by 25 publications

References 13 publications

Coverage effects on phenol adsorption on Si(100)2×1 as: A first principle calculation

Coverage effects on phenol adsorption on Si(100)2×1 as: A first principle calculation

Dissociative versus molecular adsorption of phenol onSi(100)2×1: A first-principles calculation

General and Theoretical Aspects of Phenols

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