In this respect, extraction is like distillation and recrystallization. However, extraction, unlike recrystallization or distillation, rarely gives a pure product. Recrystallization or distillation may be needed to purify a crude product extracted from a mixture. The solute divides itself between the two immiscible phases in a ratio determined by the relative solubility of the solute in each phase. See Figure 4.
Immiscible liquids form layers with a definite boundary between the layers.
Naturally, the liquid which is most dense will be the bottom layer. One phase could be a gas and the other could be a liquid, for example. Extraction One important application of the process is its use to remove an organic compound from a solution when distillation is not feasible, perhaps because the desired compound is unstable toward heat. In either event, extraction is accomplished by shaking a solution in a separatory funnel with a solvent that is immiscible with the one in which the desired substance is dissolved and in which the desired substance is more soluble. Two liquid layers are formed which can be separated from each other by draining the lower layer through the stopcock of the separatory funnel.