PHASE EQUILIBRIUM RELATIONSHIPS IN THE BINARY SYSTEM METHYL ETHYL KETONE–WATER

A complete investigation of the phase equilibrium relationships in the binary system of the partially miscible liquid pair methyl ethyl ketone–water is presented. The system shows a minimum azeotrope at 73.35 ± 0.05 °C with a composition of 88.45 ± 0.15 wt.% ketone. The azeotrope falls outside of the miscibility gap for this system. The liquid–vapor curves intersect the miscibility gap at the temperature of 73.60 ± 0.05 °C at which two conjugate solutions of compositions 18.10 ± 0.10 and 87.78 ± 0.15 wt.% ketone, respectively, are in equilibrium with a vapor phase of composition 88.00 ± 0.15 wt.% ketone. The partially miscible liquid pair shows an upper consolute temperature of 139 ± 0.5 °C at a composition of 44.9 ± 0.2 wt.% ketone. The liquid–liquid curves intersect the solid–liquid curves at a temperature of −6.0 ± 0.5° C at which two conjugate solutions of composition 40.0 ± 0.2 and 78.0 ± 0.2 wt.% ketone, respectively, are in equilibrium with ice. A binary eutectic exists at a temperature of −89.0 ± 0.5 °C with composition of the eutectic solid equal to 99.4 ± 0.4 wt.% ketone. The freezing point of pure, dry methyl ethyl ketone is determined to be −83.5 ± 0.5 °C.