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The mole fraction solubilities of ten copper (II) and five chromium (III)/3-diketonates were measured in supercritical carbon dioxidewith a spectroscopic technique and found to vary over 4 orders of magnitude. Observed trends indicate that the solubility in supercritical carbon dioxide is strongly dictated by the character of the hydrocarbon or fluorocarbon shell surrounding the central metal atom. A group-contribution approach was used to calculate the solubility parameter of the anion of the uncomplexed/3-diketone that was correlated to the experimentally measured solubility. A regular solutionsapproach was used for Cr (acac) 3 to quantitatively attemptto predict the solubility in supercritical carbon dioxide. Solubility data, solubility parameter trends, and limitations of regular solutions theory applied to supercritical fluids are discussed.