Infinite dilution liquid—gas partition coefficients of some volatile solutes with binary solvents exhibiting upper consolute temperatures

Abstract

Measurements of liquid—gas infinite dilution partition coefficients (K_R) for furan, methyl formate and diethyl ether, as a function of volume fraction, in each of the mixtures (i) ethyl benzoate + propylene glycol and (ii) tributyl phosphate + ethylene glycol, are reported. Both solvent mixtures exhibit consolute behaviour, with upper consolute temperatures in the range 40–55 °C. It is shown that K_R, for all six ternary systems, varies according to the equation K_R=ΣK^° _Rϕ where K^° _R is the partition coefficient for a pure liquid and ϕ is its volume fraction in the mixture. The continuity of behaviour observed on passing through the sequence single-phase—two-phase—single-phase is shown to be consistent with behaviour previously reported upon for many single-phase g.l.c. solvent mixtures and with a solution model based on microscopic immiscibility of these solvents. The generality of the foregoing equation is thus considerably extended.