Publisher Summary Computer-aided product design requires the generation of feasible compounds and the prediction of solution and pure component properties by group contribution methods. The application of group contribution methods, for prediction of pure component and mixture properties, opens the way for efficient computer-aided evaluation of chemical compounds. The stability of the generated chemical structures is based on the electronegativity of the group attachments. A new characterization of group combination properties and the corresponding feasibility criteria for computer-aided generation of branched structures are presented. This chapter describes a synthesis procedure and a strategy for reducing the size of the combinatorial synthesis problem and group contribution methods for the property predictions of aqueous systems in environmental problems. Three basic types of group valences, with increasing degree of electronegativity, were identified in aliphatic compounds: J, L, and K. The analysis of solvents and products from an environmental point of view requires the knowledge or prediction of solution properties, such as solubility in water, Henry constants in aqueous solutions, octanol/water partition coefficients.