Partitioning of ethyl acetate, maltol, glucose, and fructose to liquid phases of the carbon dioxide plus water plus 1-propanol system

This investigation reports on a thermodynamic phenomenon that can be observ ed in aqueous solutions of hydrophilic organic solvents: A completely misci ble binary liquid mixture of water and an organic solvent, e.g., 1-propanol , can reveal a liquid-phase split, when it is pressurized with a "near-crit ical" gas, i.e., a gas near its critical temperature. This phase split phen omenon is briefly explained and new experimental data are presented for the partitioning of some natural products (ethyl acetate, D-fructose, D-glucos e, and maltol) on, at near-critical pressures, coexisting liquid phases of a three-phase vapor-liquid-liquid equilibrium in the ternary system carbon dioxide + water + 1-propanol. In addition to the experimental data, a semie mpirical approach for the correlation of the partition coefficients is shor tly outlined. As the partition coefficients significantly deviate from unit y, this phase equilibrium phenomenon can be applied for a new mild high-pre ssure liquid-liquid extraction process for natural products.