Liquid-liquid equilibrium data of the solubility (binodal) curves and tie-line end compositions are presented for mixtures of [water (1) + formic acid or propanoic acid or 4-oxopentanoic acid or pentanoic acid (2) + 1-octanol/Alamine 336 (3)] at 293.15 K and (101.3 +/- 0.7) kPa. A solvation energy relation (SERLAS) has been utilized to estimate the properties and liquid-liquid equilibria (LLE) of associated systems containing protic and nonprotic components capable of a physical interaction through hydrogen bonding. The tie lines were also correlated using the UNIFAC-original model. The reliability of the models has been analyzed against the experimental data with respect to the distribution ratio and separation factor. The proposed model appears to be an improvement in data fit for the LLE systems, yielding a mean deviation of 12% for all of the systems considered.