Extraction

In simple extraction method, the compound is dissolved in one of the two immiscible or slightly immiscible solvents and then shaken with the other. The solvents separate into two layers with the lighter liquid on top. The immiscible liquids are separated with the aid of a separatory funnel.

C6H5COOH – benzoic acid, substance to be purified

H2O and CHCl3 - two immiscible liquids

NaCl - electrolyte which decreases the solubility of the organic compound in water (since water prefers NaCl than benzoic acid) to facilitate extraction process

salting-out effect - the reduced solubility of organic compound in water in the presence of electrolytes

Distribution Law - concerns the quantitative partitioning of the substance between two immiscible solvents at a given temperature

Characteristics of a Suitable Extraction Solvent

1. It must dissolve the solute more freely than does the other solvent.

2. It must be immiscible with the other solvent.

3. It must be of low boiling point so that it can be readily evaporated from the solute.

4. It must not react chemically with any component of the mixture.

3