SPACE PREDICTOR FOR INFINITE DILUTION ACTIVITY-COEFFICIENTS

A new formulation (SPACE) is presented for the prediction of infinite dilution activity coefficients in nonionic solutions. Statistical meth ods have been used to develop a critically evaluated gamma(infinity) d atabase at 25-degrees-C and to determine optimum mathematical expressi ons. The predictive method stems from earlier work using additive cont ributions to the cohesive energy density, but all compound-specific ad justable parameters have been avoided by using known molecular propert ies, especially the solvatochromic parameters for dipolarity/polarizab ility and for hydrogen bonding. This method has the advantages of incl uding explicitly ''chemical'' interactions and of being uncoupled from any specific g(E)(x) expression. For the present, it is limited to mo nofunctional molecules at 25-degrees-C, and it has not yet been applie d to water. Although it appears somewhat more accurate for this databa se than the UNIFAC method, it should be viewed as a complementary tech nique-an additional tool for solvent selection by the design engineer.