Analytical Sciences

Association of Tris(pentane-2,4-dionato)chromium(III) with Modifiers of Hydrogen-bond Donors in Supercritical Carbon Dioxide

Akira OHASHI, Hirobumi HOSHINO, Hisanori IMURA, and Kousaburo OHASHI

Department of Environmental Sciences, Faculty of Science, Ibaraki University, Mito 310-8512, Japan

The solubility of tris(pentane-2,4-dionato)chromium(III) (Cr(acac)₃) in supercritical carbon dioxide (SC-CO₂) containing organic modifiers (1,1,1,3,3,3-hexafluoro-2-propanol (HFP) and 3,5-bis(trifluoromethyl)phenol (BTMP)) of hydrogen-bond donors was investigated by UV/VIS spectrophotometry. A great solubility enhancement of Cr(acac)₃ in SC-CO₂ was accomplished by adding HFP and BTMP. The association constant of Cr(acac)₃ with HFP and BTMP in SC-CO₂ could be determined from the relationship of the solubility enhancement against the concentration of the modifier. The association constant linearly increases with an increase in the acid dissociation constant of the modifiers.

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