Question

Identify with reasons, which is the best recrystallization solvents(acetone, ethanol, ethyl acetate, hexane and water) for each of these solids(benzoic acid, acetanilide, naphthalene and caffeine)

Answer 1

• For Benzoic Acid methanol is the best solvent for recrystallization because

1. Benzoic Acid is only slightly soluble at room temperature in methanol, but is freely soluble at higher temperature.
2. Ethanol does not react with the benzoic acid and is also more volatile than water.

• For naphthalene and caffeine water is the better recrystallization solvent because of its minimum solubility as low temperature as water is a polar solvent where as naphthalene and caffeine are non-polar molecules.
• For Acetanilide toluene is a better solvent because toluene is a non polar solvent and will favour fair solubility at higher temperature and low solubility at room temperature.