The mole fraction solubilities of ten copper(II) and five chromium(III) P-diketonates were measured in supercritical carbon dioxide with 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 P-diketone that was correlated to the experimentally measured solubility. A regular solutions approach was used for Cr(acac)3 to quantitatively attempt to predict the solubility in supercritical carbon dioxide. Solubility data, solubility parameter trends, and limitations of regular solutions theory applied to supercritical fluids are discussed.1992, 64, 2875.

The solubilities of β-carotene and capsaicin have been measured in supercritical carbon dioxide and in difluoromethane (R-32) and 1,1,1,2-tetrafluoroethane (R-134a) in the liquid phase at temperatures near and somewhat below their critical points. The solubility of β-carotene was also measured in 1,1,1-trifluoroethane (R-143a). The temperatures of the measurements ranged from 35 °C to 55 °C for capsaicin (up to 85 °C in R-32) and from 40 °C to 70 °C for β-carotene. The solubilities were determined using an HPLC system for capsaicin and a static high-pressure cell for β-carotene, and the amounts of products extracted were measured spectroscopically. At similar temperatures and densities, the solubility of capsaicin in the halocarbons was higher than that in carbon dioxide; there was not such a clear trend for β-carotene. Where the data covered a sufficient density range, they (along with literature data for the solutes in carbon dioxide) were analyzed with the semiempirical density-based model of Méndez-Santiago and Teja.

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successfully modeled isotropically as a 1:1 disorder of a CO ligand and an H 2O ligand.After the Rh and P peaks, the next largest peak was located 5.5 Å from the Rh atom. This peak was situated in the center of three smaller peaks that formed a ca. 3-fold symmetric trigonal pyramid. Application of the crystal symmetry operations generated four symmetry-related peaks that, overall, formed a staggered ethane-like fragment that was assigned as an end-to-end disordered SO 3CF3 -moiety. Upon assigning the large peak as a S atom with a site-occupation factor ) 0.5, the largest peak in the subsequent difference map was located 0.96 Å from the S position and just off the vector between S and the position of its symmetry equivalent S(a). Overall, the pattern appeared to be the partially resolved superposition of the C atom (from the CF 3 group) and the S atom (of the SO 3 group). Therefore, the best approximation of the disordered SO 3CF3 -resulted from a model where both the S and C(2) atoms where given site-occupation factors of 0.5 and the F(1), F(2), and F(3) atoms were assigned site-occupation factors of 1.0 each in order to approximately account for both the superposition of the F and O atoms.Despite the disorder in the CO, H 2O, and SO3CF3 -positions, refinement of the structure to 10.57% was possible. The density of the crystals was determined to be 1.57(2) g/cm 3 by flotation in a CCl4/ hexane mixture. The calculated density for 4 molecules of trans-[Rh-(CO)(PPh 3)2(OH2)] [OTf] per unit cell is 1.57 g/cm 3 .

The aim of this work was to identify the key mechanisms governing transport of organic chemical substances from consumer articles to cotton wipes. The results were used to establish a mechanistic model to improve assessment of dermal contact exposure. Four types of PVC flooring, 10 types of textiles and one type of inkjet printed paper were used to establish the mechanisms and model. Kinetic extraction studies in methanol demonstrated existence of matrix diffusion and indicated the presence of a substance surface layer on some articles. Consequently, the proposed substance transfer model considers mechanical transport from a surface film and matrix diffusion in an article with a known initial total substance concentration. The estimated chemical substance transfer values to cotton wipes were comparable to the literature data (relative transfer ∼ 2%), whereas relative transfer efficiencies from spiked substrates were high (∼ 50%). For consumer articles, high correlation (r(2)=0.92) was observed between predicted and measured transfer efficiencies, but concentrations were overpredicted by a factor of 10. Adjusting the relative transfer from about 50% used in the model to about 2.5% removed overprediction. Further studies are required to confirm the model for generic use.