PHASE DIAGRAMS OF LAURIC ACID, HEXANE AND THE IONIC LIQUID TRIHEXYL(TETRADECYL)PHOSPHONIUM CHLORIDE

Abstract

Mass and molar phase diagrams of lauric acid (LA), hexane and the ionic liquid (IL) trihexyl(tetradecyl)phosphonium chloride were developed at room temperature. The diagrams and experimental tie-lines were obtained for the water saturated IL. The biphasic system of IL and hexane was observed for LA mole fractions less than 0.015 in IL and 0.005 in hexane. The gradual addition of LA caused the biphasic system to become monophasic at a molar fraction just below 0.01 for LA and 0.03 for IL. Composition of mixtures that phase separated were determined by weight and gas chromatography. LA showed a solubilizing effect on the IL, since increased concentrations of the fatty acid caused an increase in the miscibility of IL with hexane. It was hypothesized that this happened due to a polar association of LA with IL at the positively charged phosphonium site. Using hexane to extract products of hydrolysis from the IL was deemed unsuitable due to the preferential distribution of LA in the IL, rather than the hexane. Phase diagrams of triglycerides in a similar system were suggested to investigate the suitability of the IL as a medium for acidolysis reactions.