Nonlinear dependence of the solubility of water in hydrocarbons on the molar volume of the hydrocarbon

The solubility of water in fifty hydrocarbon solvents at 20°C is estimated by means of the solubility equation derived from the thermodynamics of mobile order in H-bonded liquids. Neglecting the change in nonspecific cohesion forces, and assuming that water is primarily monomeric in solution, the prediction accounts for two main effects: the breaking of the H-bond network linking the water solute molecules together, and the entropy of exchange between water and solvent molecules in solution. The formation of a weak O–H ... hydrogen bond interaction is moreover taken into account according to whether the hydrocarbon is saturated or not. The overall predictive equation foresees a non-linear dependence of the water solubility on the molar volume of the hydrocarbon. Several rules are presented regarding the water solubility-hydrocarbon structure relationship.