Kinetics and mechanism of reaction between zirconium-lactate and pentane-2,4-dione in excess lactate

The kinetics of the reaction of pentane-2,4-dione (HA) with ZrIV has been studied at 25.0°C in an excess lactate (L−) media. The equilibrium reaction was found to be: Zr2L6+HA⇌HL+Zr2AL5. The equilibrium was approached from either direction and a plausible mechanism has been proposed with kinetic constants, but individual reactivities of the keto and the enol tautomers of pentane-2,4-dione could not be apportioned. However, it was found that both the uncatalyzed and acid-catalyzed paths contribute to the reverse reaction. But 2-thenoyltrifluoroacetone (HT) forms a stronger chelate with ZrIV, so its reaction with less reactive Zr2L5(OH2) could not be detected; reactivity of the more reactive Zr2L5(OH2)(OH) could be found. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 725–729, 2011