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 Zr^IV 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 Zr^IV, 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