Hydration and hydrolysis of alpha-oxo carboxylic acid derivatives and conjugate addition to alpha,beta-unsaturated carbonyl compounds: A density functional study

Hydration of the keto group as well as hydrolysis (ester and amide) of alph a-oxo carboxylic acid derivatives has been studied by density functional th eory (B3LYP/6-31G* and B3LYP/6-311G**). Both uncatalyzed as well as water-a ssisted processes have been considered. Solvent effects were approximated b y the self-consistent isodensity surface polarized continuum (SCIPCM) model . For hydrolysis reactions a concerted as well as a stepwise mechanism was calculated. In the latter one, addition of the nucleophile to a tetrahedral intermediate was found to be rate determining. In uncatalyzed processes bo th concerted and stepwise mechanisms are calculated to have comparable acti vation energies and free enthalpies. In catalyzed reactions the stepwise me chanism is predicted to be considerably more favorable. Hydration of the al pha-ore group should be much more feasible than either ester or amide hydro lysis.