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Previous fundamental work on the solvent properties of carbon dioxide by the research groups of McHugh, DeSimone, Johnston, and Eckert has been used as a road map for the design of materials that will be miscible with CO2 at relatively moderate pressures. In this initial work, judicious side chain functionalization of an oligomeric silicone has been shown to produce a material whose phase behavior in CO2 resembles that of a fluorinated polyether. The phase behavior results are quite dramatic in that addition of only five ester-functional side chains to the silicone polymer lowers the cloud point curve at 22 °C by 2500 psi. It was also observed that addition of simple alkyl side chains raises the cloud point pressures of the silicone in CO2. This latter observation is consistent with results on the phase behavior of poly(n-alkyl acrylates) in CO2 that showed that increasing alkyl content (i.e., increasing alkyl chain length) also raises cloud point pressures.

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Hydrogen peroxide is a "green" oxidant whose relatively high cost has prevented it from being generally applied to commodity chemical processing. In large part, the attributes of the current H 2 O 2 process (the anthraquinone, or AQ, route) that contribute to its high cost also contribute to its nonsustainable features: byproduct streams, high energy input and solvent usage, and multiple required unit operations. We have explored the generation of hydrogen peroxide directly from hydrogen and oxygen using liquid CO 2 as the solvent. Producing H 2 O 2 directly from H 2 and O 2 in the presence of a CO 2 -soluble Pd catalyst could potentially eliminate entire unit operations and reduce raw material costs significantly. Further, homogeneous reaction in liquid CO 2 allows for contact between significant concentrations of O 2 and H 2 , high rates of reaction, and ready recovery of the product via stripping into water. Both Pd(+2) and Pd(0) catalysts were explored for the reaction; our results suggest that future work should focus on the optimization of a CO 2 -soluble or -dispersible Pd(0) catalyst. Finally, we have found that CO 2 / H 2 O 2 /H 2 O mixtures are, themselves, useful reagent systems. A biphasic aqueous H 2 O 2 /CO 2 mixture is an efficient epoxidizing system, where HCO 4is formed through various reactions of water, CO 2 , and H 2 O 2 and transfers of oxygen to alkenes. From our results, it appears that H 2 O 2 can react directly with CO 2 , producing more percarbonate ion than in situations that employ only bicarbonate as the precursor.