Experimental tie-line data for three quaternary systems of (water + 2-propanol + dimethyl carbonate + isooctane), (water + 2-propanol + dimethyl carbonate + toluene), and (water + 2-propanol + dimethyl carbonate + heptane) and one ternary system of (water + 2-propanol + dimethyl carbonate) were measured at a temperature of 298.15 K and ambient pressure. The experimental quaternary and its constituent ternary results were compared with those correlated using the modified and extended UNIQUAC models that include multibody interaction parameters in addition to binary ones.