Sublimation

Principle: Direct transition of a solid into its gaseous state upon heating without passing through the liquid state.

$$\text{Solid} \underset{\text{Cool}}{\overset{\text{Heat}}{\rightleftharpoons}} \text{Vapor}$$

Condition: Applicable when the organic compound is sublime, and the impurities are non-sublime (or vice-versa).

Common Examples: Naphthalene, Anthracene, Camphor, Benzoic Acid, Salicylic Acid, Iodine, and Ammonium Chloride ($$\text{NH}_4\text{Cl}$$).