The O-H Bond Dissociation Energies of Substituted Phenols and Proton Affinities of Substituted Phenoxide Ions: A DFT Study

Abstract

Abstract:The accurate O-H bond dissociation enthalpies for a series of meta and para substituted phenols (X-C 6 H 4 -OH, X=H, F, Cl, CH 3 , OCH 3 , OH, NH 2 , CF 3 , CN, and NO 2 ) have been calculated by using the (RO)B3LYP procedure with 6-311G(d,p) and 6-311++G(2df,2p) basis sets. The proton affinities of the corresponding phenoxide ions (X-

DFT/B3LYP Study to Investigate the Possible Ways for the Synthesize of Antioxidants with High Efficiency Based on Vitamin E

“…Total enthalpies of the studied species X, H(X), at the temperature T are usually estimated from the expression (4) 8,45 H(X) = E 0 + ZPE + ΔH trans + ΔH rot + ΔH vib + RT (4) where E 0 is the calculated total electronic energy, ZPE stands for zero-point energy, ΔH trans , ΔH rot , and ΔH vib are the translational, rotational, and vibrational contributions to the enthalpy, respectively. Finally, RT represents PV-work term and is added to convert the energy to enthalpy.…”

DFT/B3LYP Study of the Substituent Effects on the Reaction Enthalpies of the Antioxidant Mechanisms of Magnolol Derivatives in the Gas-Phase and Water

“…39,42,83,93 DiLabio et al 16,88,95 found that BDE and ΔBDE values of para-substituted phenols, 6-substituted-3-pyridinols, 2-substituted-5-pyrimidinols, and anilines are linearly dependent on Hammett constants σ p . Klein et al 37,48 found that BDE and ΔBDE values of para-substituted and meta-substituted phenols are linearly dependent on Hammett constants σ p and σ m .…”

“…Substituent effects are among the most important concepts of structural effects influencing the chemical, physicochemical, and biochemical properties of chemical species. 35,36 In recent years many previous experimental [22][23][24][37][38][39][40][41][42] and theoretical 12,22,33,[43][44][45][46][47][48][49][50] investigations have been carried out on phenol and mono-substituted phenols in gas and solvent environment. Theoretical study of substituent effect can be utilized in the synthesis of substances with enhanced antioxidant properties.…”

An Accurate QSPR Study of O−H Bond Dissociation Energy in Substituted Phenols Based on Support Vector Machines

“…In most of the cases the calculated BDE values differ widely from the experimental value. 7 The other methods are more empirically based quantitative structure-activity relationship (QSAR) and quantitative structure-property relationship (QSPR) approaches. In a recent review, 10 quantitative structure-activity relationships have been established for both biological and nonbiological activities and properties of substituted phenols with electronic properties of the substituents.…”

“…The rigorous approaches involve quantum mechanical methods including density functional methods, 7 ab initio, 8 and semiempirical methods. 9 The accurate estimation of BDE from theoretical calculations is a challenging task, since high levels of calculations are necessary for taking into account the effect of both the dynamical and the nondynamical part of electron correlation.…”