Which step of crystallization is most affected if ice-cold solvent is not used?

Using an ice-cold solvent is particularly crucial during the cooling step of the crystallization process. This step is designed to promote the formation of pure crystals by reducing the solubility of the compound in the solvent, thus encouraging it to crystallize out of solution as the temperature decreases.

If ice-cold solvent is not used during this cooling procedure, the solute may remain too soluble, leading to inadequate supersaturation. As a result, the intended crystallization may be compromised — either yielding fewer crystals or resulting in crystals that are less pure due to the presence of impurities that are still in solution. Additionally, higher temperatures can lead to the formation of smaller and more poorly defined crystals, which are less effective for purification.

In summary, the cooling procedure is significantly affected if ice-cold solvent is not used, as this temperature control is critical for successful crystallization and obtaining high-quality crystalline products.