title: Moderately strong phenols dissociate by forming an ion-pair kinetic intermediate.
abstract: We show computational evidence that ground-state moderately strong hydroxyarenes (Ar-OH, pKa ∼ 0) dissociate by forming an ion-pair intermediate that lives for 3-5 ps. The concentration of this intermediate is approximately 2 times smaller than that of the un-ionized acid at pH ∼ 0.6 and is characterized by average C-O bond lengths (1.30 Å) that are intermediate between those of un-ionized (1.29 Å) and fully dissociated (1.34 Å) species. During the lifetime of the ion-pair intermediate the excess proton fluctuates between the oxygen atom of the phenolic moiety and those of water molecules in the first and second solvation shells on a subpicosecond time scale (∼100-300 fs).
authors.affiliation: Département de Chimie, Université de Montréal , CP 6128, succursale Centre-Ville, Montréal H3C3J7, Canada.
authors.forename: Radu
authors.initials: R
authors.lastname: Iftimie
authors.forename: Marie-Hélène
authors.initials: MH
authors.lastname: Tremblay
authors.forename: Vibin
authors.initials: V
authors.lastname: Thomas
authors.forename: Sebastien
authors.initials: S
authors.lastname: Hétu
authors.forename: Francis
authors.initials: F
authors.lastname: de Lasalle
authors.forename: Ugo
authors.initials: U
authors.lastname: Rivard
mesh_terms: D006863:Hydrogen-Ion Concentration; D007477:Ions; D007700:Kinetics; D056004:Molecular Dynamics Simulation; D010100:Oxygen / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*; D011522:Protons; D013696:Temperature; D014867:Water / Q000737:chemistry*
chemical_list: D007477:Ions; D010636:Phenols; D011522:Protons; D014867:Water; D010100:Oxygen