THERMODYNAMIC STUDY OF THE PARTITIONING OF ORGANIC-COMPOUNDS BETWEEN WATER AND OCTAN-1-OL

The effect of water, as cosolvent, in changing the affinity of octan-1-ol towards organic solutes according to their chemical nature, has been examined by determining the thermodynamic functions of solvation, Delta(solv)X degrees(j) (X = G, H, S), in anhydrous (j = oct) and in water-saturated octan-1-ol (j = oct*) of organic compounds of the RY type (R = hydrocarbon frame, Y = H, O, C=O, NH2, NH, N). From these data and the analogous thermodynamic functions of hydration,Delta(solv)X degrees(w), the thermodynamic functions, Delta(tr)X degrees(j --> j*), for the three ideal or practical processes of transfer (namely, w --> oct, w --> oct*, oct --> oct*) have been calculated. The Delta(tr)X degrees(j --> j*) functions have been correlated with the structure of the solutes by using their intrinsic volume as a unique structural parameter. The coefficients of the linear equations obtained give information about the contributions to the envisaged thermodynamic function, connected with the formation of a cavity containing the solute and to the solute-solvent interactions. In the case of the Delta(tr)G degrees(j --> j*) functions, the LSERs (linear solvation energy relationships) have also been used for correlating the thermodynamic functions to the structural features of the solutes.