Correlation of the boiling points of mixtures

A modified Swietoslawski equation has been developed to correlate the boiling points of mixtures. Vapor—liquid equilibrium data have been determined at 760 mm for the binary systems normal butanol-tertiary butanol and normal butanol-secondary butanol. Both systems present slight negative deviations from ideal solution behavior. The boiling points of the two binaries and of several other non-ideal systems were satisfactorily correlated by means of the above equation. Prediction of ternary boiling points from binary data and simplifications in the correlation which are useful for practical applications are also discussed.