Liquid-liquid equilibria of the ternary systems toluene-heptane-tetraethylene glycol, toluene-heptane-N-formylmorpholine, toluene-heptane-(tetraethylene glycol + N-formylmorpholine), and toluene-heptane-(tetraethylene glycol + N-methylpyrrolidone) have been determined at 40 degrees C. The capacity and selectivity data of the solvent systems were obtained and compared. The data were correlated using Bachman, Othmer-Tobias, and Hand models.