LINEAR SOLVATION ENERGY RELATIONSHIP OF THE SOLUBILITY OF VERY POLAR GASES - SULFUR-DIOXIDE, HYDROGEN-CHLORIDE, HYDROGEN BROMIDE, AND AMMONIA

A linear free energy relationship was found for the log (mole fraction ) of solutes in a wide variety of organic solvents with the solvatochr omic parameters and the Hildebrand solubility parameter. The solutes w ere the highly dipolar gases sulfur dioxide, hydrogen chloride, hydrog en bromide, and ammonia at 25-degrees-C and 1 atm. partial pressure of the solute. It was found that correlations were greatly improved if s olvatochromic parameters for the solvent as a monomer were used rather than the values for the bulk solvent. In solutions with these very di polar gases, the mole ratio of solute to solvents approaches unity in many of the solutions, so a molecule of solute is interacting primaril y with a particular molecule of the solvent. Therefore, the use of the solvatochromic parameters for the solvent as monomer is physically re asonable.