Gas-phase thermochemical properties of some tri-substituted phenols: A density functional theory study

作者：Miranda Margarida S^*; Esteves da Silva Joaquim C G; Liebman Joel F

来源：Journal of Chemical Thermodynamics, 2015, 80: 65-72.

DOI：10.1016/j.jct.2014.08.025

• Tri-substituted phenols
• Molecular structure
• Enthalpy of formation
• O-H homolytic bond dissociation enthalpy
• Acidity
• Adiabatic ionization enthalpy

The study of the energetics of phenolic compounds has a considerable practical interest since this family of compounds includes numerous synthetic and naturally occurring antioxidants. In this work, density functional theory (DFT) has been used to investigate gas-phase thermochemical properties of the following tri-substituted phenols: 2,4,6-trimethylphenol, 2,6-dimethyl-4-tert-butylphenol, 2, 6-dimethyl-4-methoxyphenol, 2,4,6-tri-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tertbutyl-4-methoxyphenol, 2,4,6-trimethoxyphenol, 2,6-dimethoxy-4-methylphenol and 2,6-dimethoxy-4-tert-butylphenol. Molecular structures were computed with the B3LYP and the omega B97X-D functionals and the 6-31G(d) basis set. More accurate energies were obtained from single-point energy calculations with both functionals and the 6-311++G(2df,2pd) basis set. Standard enthalpies of formation of the phenolic molecules and phenoxyl radicals were derived using an appropriate homodesmotic reaction. The O-H homolytic bond dissociation enthalpies, gas-phase acidities and adiabatic ionization enthalpies were also calculated. The general good agreement found between the calculated and the few existent experimental gas-phase thermochemical parameters gives confidence to the estimates concerning the phenolic compounds which were not yet experimentally studied.

• 出版日期2015-1