ABSTRACT Variable temperature stopped-flow investigations of the reversible hydration of pyruvic acid were carried out and reveal that for the spontaneous reaction ∆H‡ = 36 ± 7 kJmol-1 and ∆S‡ = -171 ± 25 Jmol-1K-1 and for the hydronium ion-catalyzed reaction ∆H‡ = 33 ± 2 kJmol-1 with ∆S‡ = -121 ± 7 Jmol-1K-1. These values at 298 K correspond to a ∆G‡ = 87 ± 10 kJmol-1 for the spontaneous reaction and a ∆G‡ = 69 ± 3 kJmol-1 for the hydronium ion-catalyzed hydration. These kinetic results are interpreted in terms of the mechanisms of the spontaneous and hydronium ion-catalyzed hydration of pyruvic acid.
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