title: Computational study on the relative acidity of acetic acid by the QM/MM method combined with the theory of energy representation.
abstract: We have applied the quantum mechanical/molecular mechanical (QM/MM) method combined with the theory of energy representation (ER) to study the acidity of acetic acid in aqueous solution. We have focused our attention on the relative acidity DeltapK(a) of the molecule with respect to water solvent to circumvent the ambiguity of the solvation free energies of the molecular species referred to as proton. The value of DeltapK(a) for the acetic acid has been computed as -11.5 when we adopt the free energy change in the gas phase obtained by the B3LYP functional, which is in excellent agreement with the experimental value of -11.0. It has been demonstrated that the QM/MM-ER approach recently developed gives an adequate description for the solvation free energies related to the acidity/basicity calculations of organic molecules.
authors.affiliation: Division of Chemical Engineering, Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Machikaneyama-cho 1-3, Toyonaka, Osaka 560-8531, Japan.
authors.forename: Takumi
authors.initials: T
authors.lastname: Hori
authors.forename: Hideaki
authors.initials: H
authors.lastname: Takahashi
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Furukawa
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Nakano
authors.forename: Weitao
authors.initials: W
authors.lastname: Yang
mesh_terms: D019342:Acetic Acid / Q000737:chemistry*; D000465:Algorithms; D003198:Computer Simulation; D004735:Energy Transfer; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008958:Models, Molecular; D011522:Protons; D012996:Solutions; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
chemical_list: D011522:Protons; D012996:Solutions; D014867:Water; D019342:Acetic Acid