Solubilities of Palladium(II) <i>β</i>-Diketonates (<i>β</i>-Diketonate = Acetylacetonate, Trifluoroacetylacetonate, Thenoyltrifluoroacetonate) in Supercritical Carbon Dioxide

Abstract

The solubilities of palladium(II) -diketonates (PdL 2 , L = acetylacetonate (acac), trifluoroacetylacetonate (tfa), and thenoyltrifluoroacetonate (tta)) in supercritical carbon dioxide (SC-CO 2 ) from 318 -338 K and 8 -25 MPa were investigated by UV-vis spectrophotometer equipped with a high-pressure optical cell. The molar absorptivities for Pd(acac) 2 , Pd(tfa) 2 , and Pd(tta) 2 in SC-CO 2 were estimated as 1.14  10 4 M -1 cm -1 at 324 nm, 8.16  10 3 M -1 cm -1 at 336.5 nm, and 2.70  10 4 M -1 cm -1 at 322.5 nm, respectively. Solubilities in SC-CO 2 increase in order of Pd(tta) 2 < Pd(acac) 2 < Pd(tfa) 2 , i.e., 6.5  10 -6 < 5.2  10 -5 < 1.3  10 -4 M at 318 K and 11.5 MPa. The experimental solubilities were correlated using the equation proposed by Chrastil and the thermodynamic parameters for each PdL 2 were estimated.