Crystallization is the most common method for purifying solid organic compounds.

• Principle: It is based on the fact that an organic compound is much more soluble in a specific solvent at high temperatures than at low temperatures.
• Procedure: The impure solid is dissolved in a minimum amount of hot solvent to form a saturated solution. Upon cooling, the pure compound, being less soluble at lower temperatures, crystallizes out. The impurities, which are either insoluble or more soluble than the compound, remain in the mother liquor.