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Volumn 69, Issue 16, 2004, Pages 5460-5467

Water effect on the O-H dissociation enthalpy of para-substituted phenols: A DFT study

Author keywords

[No Author keywords available]

Indexed keywords

AROMATIC COMPOUNDS; DISSOCIATION; ELECTRONS; ENTHALPY; HYDROGEN BONDS; NUMERICAL METHODS; SUBSTITUTION REACTIONS;

EID: 3543004703     PISSN: 00223263     EISSN: None     Source Type: Journal    
DOI: 10.1021/jo0495236     Document Type: Article
Times cited : (59)

References (38)
  • 19
    • 3543030763 scopus 로고    scopus 로고
    • note
    • The O-H BDE values tabulated in ref 14 were determined by EC cycle using the measured one-electron reduction potential of the phenoxy radicals in water. They have been viewed as upper limits to the gas-phase values since they were obtained by setting to zero the difference between the free energy of solvation of phenols and phenoxyl radicals. On the other hand, these values can be considered as the O-H BDE of phenols in water solution. Indeed, the correct BDE values in water can be obtained by substituting in the EC cycle the small contribution due to the difference in entropy between phenol and phenoxyl radical calculated in the gas phase (-0.43 kcal/mol for phenol) with the corresponding value in water. The effect of solvation on this small contribution due to the entropy difference is expected to be very small.
  • 30
    • 0000630535 scopus 로고
    • Saenger, W. Nature 1979, 279, 343-344.
    • (1979) Nature , vol.279 , pp. 343-344
    • Saenger, W.1
  • 33
    • 3543009287 scopus 로고    scopus 로고
    • A theoretical study on the effect of water on the BDE of para-substituted phenols was published when this paper was under examination by the referee (Fu, Y.; Liu, R.; Liu, L.; Guo, Q.-X. J. Phys. Org. Chem. 2004, 17, 282-288). The effect of water was simulated by placing one water molecule near the phenolic/phenoxyl group. Thus, this model cannot take into account the effect of water on the electronic properties of the para substituents that largely influence the BDE values of phenols. Indeed, this model does not reproduce the large decrease (2.8 kcal/mol) of the O-H BDE observed experimentally in water on going from hydroquinone to p-methoxyphenol. On the contrary, the BDE of hydroquinone has been computed to be 1.3 kcal/ mol higher than that of p-methoxyphenol.
    • (2004) J. Phys. Org. Chem. , vol.17 , pp. 282-288
    • Fu, Y.1    Liu, R.2    Liu, L.3    Guo, Q.-X.4
  • 34
    • 3543037911 scopus 로고    scopus 로고
    • note
    • The one-electron reduction potential of the dimethylaminophenoxyl radical decreases by 28 mV on substituting a methyl group with a hydrogen atom, but against any expectation, it increases by 43 mV on substituting both methyl groups with hydrogens. This apparent discrepancy was judged unclear by the authors.28


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.