TRANSFER OF TRIFLUOROACETYLACETONE ACROSS A WATER-1,2-DICHLOROETHANE INTERFACE

The ion transfer of 1,1,1-trifluoroacetylacetone (HTAA) across a water/1,2-dichloroethane interface has been studied at various pH values, using current-scan polarography at the ascending water electrode, and a cathodic wave caused by the transfer of TAA- from the aqueous to the organic phase has been observed. Experiments have been carried out with two different types of addition of HTAA; one is the addition to the organic phase and the other to the aqueous phase. Although the anodic wave appears with both additions, the limiting current and the half-wave potential depend on the pH differently. Their dependences have been ascribed to the following: (1) the slow keto-enol tautomerization rate of HTAA; (2) the existence of TAA2- hydrate anion; (3) some branch diffusions from the interfacial region to the bulk phase. The pK(a2) value of HTAA has been determined to be 9.2.