Holec's Rule

Holec's Rule is a guideline used by chemists to predict whether a compound can be purified using recrystallization. It states that compounds with a high difference (usually over 1.3) between their solubility in hot and cold solvents are good candidates for recrystallization. Essentially, if a substance dissolves easily when hot but barely dissolves when cold, it can be recrystallized effectively to obtain pure crystals. This rule helps chemists choose suitable solvents and conditions for purification without extensive trial and error.