What is the primary purpose of recrystallization in organic chemistry?

The primary purpose of recrystallization in organic chemistry is to purify solid compounds by exploiting differences in solubility. In this technique, a solid mixture is dissolved in a suitable solvent at high temperatures, where the solubility of the desired compound is generally higher. As the solution cools, the solubility of the compound decreases, leading to the formation of pure crystals. Impurities that are more soluble or have different solubility characteristics remain in the solution and can be separated from the desired product upon crystallization.

This method effectively separates the desired compound from contaminants by utilizing specific solubility properties, leading to a refined product with improved purity. The choice of solvent is crucial, as it must be able to dissolve the target compound when hot while allowing it to crystallize out upon cooling.

While other choices may relate to aspects of organic chemistry, they do not accurately capture the primary focus of recrystallization. For instance, dissolving all compounds thoroughly does not align with the selective purification goal. Identifying unknown substances typically requires different techniques such as spectroscopy or chromatography, while increasing yield can be a consideration in synthesis, but is not the main intent of recrystallization, which is primarily about purity.