Tie-line data were experimentally determined at 298.15 K and ambient pressure for him ternary systems of water + 1,1'-oxybis(butane) (DBE) + methylbenzene or heptane and two quaternary systems of water + ethanol + DBE + methylbenzene or heptane. The modified and extended universal quasichemical (UNIQUAC) activity coefficient models were used to correlate the experimental tie-line data. The experimental and the correlated results obtained using the modified UNIQUAC model were comparably presented in the phase diagrams for the ternary and quaternary systems measured in this work. Distribution coefficients of components were calculated to evaluate their solubility in aqueous and organic phases.