Campus Units

Chemistry, Ames Laboratory

Document Type

Article

Publication Version

Published Version

Publication Date

11-1996

Journal or Book Title

Journal of the American Chemical Society

Volume

118

Issue

46

First Page

11592

Last Page

11598

DOI

10.1021/ja9538546

Abstract

The abstractions of hydrogen from both carbon and oxygen in acetic acid by hydride, fluoride, and hydroxide anions have been studied using ab initio electronic structure calculations. Molecular structures were optimized at the Hartree−Fock level of theory using the 6-31++G(d,p) basis set. For energetics, the 6-311++G(d,p) basis set was used, with second- and fourth-order perturbation theory corrections, for both minima and transition states. For the hydride and fluoride ion abstractions of hydrogen from carbon, a small activation energy exists at the Hartree−Fock level, but vanishes when correlation energy corrections are introduced. No other barriers are found for the abstraction reactions, but intermediate minima are found on the F- + CH3COOH → FH + -CH2COOH surface and on the analogous OH- + CH3COOH surface. The calculated heats of formation for both acetic acid anions are in good agreement with the experimental values. The fourth-order perturbation theory calculation of the activation energy for the isomerization of acetate to enolate ion is 50.4 kcal/mol. The G2 values for the gas phase acidities of acetic acid at the OH and CH ends of the molecule are 339.3 and 365.8 kcal/mol, respectively. The former result is in good agreement with experiment.

Comments

Reprinted (adapted) with permission from Journal of the American Chemical Society 118 (1996): 11592, doi:10.1021/ja9538546. Copyright 1996 American Chemical Society.

Copyright Owner

American Chemical Society

Language

en

File Format

application/pdf

Included in

Chemistry Commons

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