Water in nonaqueous solvents*

The possibility and usefulness of sinple liquid models is reported. The importance of van der Waals forces for liquid water and aqueous solutions is discussed and compared with the solubility of water in nonpolar solvents and as well as of nonpolar solvents in water. Both systems could be understood as equilibrium of few water monomers. The network of H-bonded water molecules seems to be less important for both effects. This conclusion would disagree with the cluster model of liquid water. The polarization of OH groups by unpolar solvents is demonstrated. The carrier effect of polar molecules for the solubility of water in nonpolar solvents is studied with the polyethylenoxides. The change of water solubility in organic phases by changes of the water activity by other solutes is reported. As example for the cooperativity effect of water H-bonds the influence of different cations on the interaction between water and aprotic solvents is studied. This gives a view on the role of water and its cooperativity on biochemical structures.