New pure component parameters are presented for the MOSCED limiting activity coefficient model for 133 solvents with an absolute average deviation of 10.6% to experimental literature data. The MOSCED model has been applied to solid-liquid equilibria correlation and compared with the experimental data available in the literature. The correlation of solubility of 26 solids in organic solvents has an average absolute deviation of 25%. This compares favorably to the prediction of the modified UNIFAC model.

There are now available a variety of tunable solvents; these have been used extensively for extractions and in a variety of materials applications. Our focus has been to apply these techniques to chemical reactions to take advantage of the special properties available, primarily for sustainable technology, to create processes that are potentially more benign and more advantageous. We report here our work in using supercritical fluids, near-critical fluids, and gas-expanded liquids to couple organic reactions with separations. In this paper, we review applications involving improved transport, catalyst recycling, and product separation as well as the in situ generation of catalysts. Although such tunable solvents are in no way a panacea, they do offer the chemical community alternatives that can often be applied creatively to many reaction opportunities.

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The phase equilibria of dilute aqueous solutions are treated separately from those of dilute organic systems due to water's unique structure and hydrogen-bonding characteristics. As a result, traditional predictive methods (UNIFAC, ASOG, etc.) tend to be only moderately successful. In addition to inverse solubility measurements, we describe new direct and indirect techniques for precisely measuring these values which are more accurate. A database is compiled from data measured by using these techniques. The data were evaluated and suspect points removed. The data were correlated linearly with the solute solvatochromic R, , and π*, solute and solvent molar volume, solute vapor pressure, and the solute gas-liquid partition coefficient between hexadecane and an inert gas phase, log L 16 . The correlation fits the data to within an average absolute deviation of 0.294 ln units. The correlation provides a direct and relatively accurate method for estimating Henry's constants and thus limiting activity coefficients of nonelectrolytes in water.

The mutual solubility of carbon dioxide and alcohols over a wide range of temperature and pressure provides a useful and tunable medium for reactions and separations. For many years, researchers have used alcohols as cosolvents in supercritical CO2, and recently CO2-swollen alcohols have been used for antisolvent crystallization and as mobile phases for chromatography. However, little consideration has been given to chemical interaction between the alcohols and CO2. We have confirmed that such an interaction does exist and can create an acidic environment. By isolating reaction products we have demonstrated that alcohol−CO2 complexes react similarly to carboxylic acids with diazodiphenylmethane, a compound typically used to evaluate acid strengths. Our evidence indicates that the behavior of CO2−alcohol systems is comparable to that of CO2−water systems, where carbonic acid is formed.

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The key to sustainable technology is achieving an economic benefit for environmental improvements. The tunability of benign compounds such as CO2 and water as supercritical and near-critical fluids offers improved performance and greater flexibility for separation and reaction processes, leading to economic advantages. Examples of such behavior are supercritical CO2 extractions and separations, CO2-expanded polar liquids for separations, and reactions in near-critical water. In each case the tunability is achieved through density changes or cosolvents and may augment product yield, quality, or rates.

Vapor−liquid equilibria, molar volumes, and volume expansion for several binary mixtures of organic solvents with carbon dioxide have been determined using a visual synthetic technique at temperatures from (298 to 333) K. The binary vapor−liquid equilibrium and saturated liquid molar volume of CO2 + acetone, + acetonitrile, + dichloromethane, + nitromethane, + N-methyl-2-pyrrolidone, + perfluorohexane, + 2-propanol, + tetrahydrofuran, + toluene, and + 2,2,2-trifluoroethanol were measured at temperatures from (298.2 to 333.2) K. The VLE correlated well using the Patel−Teja equation of state with Mathias−Klotz−Prausnitz mixing rules. The solubility of CO2 in the various solvents is explained by considering the intermolecular interactions of CO2 in solution.