Effect of aqueous solvation on the structures of pyruvic acid isomers and their reactions in solution: a computational study

The pyruvic acid molecule and its various isomers have been studied in aqueous solution in order to understand the mechanism of decarboxylation. The tautomeric equilibrium remains in favor of the keto form in aqueous solution, but the energy difference between the two tautomers decreases. The anion also exists in the keto form in aqueous solution. Good agreement between the calculated and observed gas phase protonation and basicity values is obtained, and the calculated pK_a value is also in reasonable agreement with the literature value. The importance of the catalytic mechanism may be gauged from the fact that, in the absence of an enzymatic pathway, the reaction has high activation barrier and may not occur at all. Copyright © 2007 John Wiley & Sons, Ltd.