Rate and Equilibrium of the Distribution of 2-Thenoyltrifluoroacetone in Carbon Tetrachloride-Aqueous Perchlorate Solution Systems

Abstract

The rate and equilibrium of the liquid-liquid distribution of 2-thenoyltrifluoroacetone (Htta) was studied in carbon tetrachloride-aqueous 0.1mol dm^-3 sodium perchlorate solution systems at 298K. The distribution equilibrium of Htta reached after two-phase agitation for 90min and the distribution constant of the total Htta was 2.2×10; however, that of the enol form of Htta was higher than 2×10² and that of the keto form of Htta was 5.8×10^-1. By a spectrophotometric method and by a liquid-liquid partition method, the rate constant of the enolization and ketonization in the organic phase was measured. The former was 10² times higher than that of the latter; both were several orders lower than those in the aqueous phase. From these results, it was assumed that when Htta was initially added to the organic phase the main route of the two-phase distribution reaction was a transference of the enol form from the organic to the aqueous phase and its change to the keto form. In contrast to the change in the distribution ratio of Htta during two-phase agitation, the solvent extraction of metal ions from the aqueous phase with Htta did not change very much after a transient equilibrium was reached within a short time. This was examined with the extraction of indium(III).