Question

What are the criteria for the selection of solvent for the process of crystallization?​

Answer 1

Answer:

The solvent to be used for crystallization must have the following properties:

• The solubility of the compound to be crystallized should be more at higher temperature and least at room temperature in a given solvent.
• The impurities should be either insoluble or sparingly soluble in a given solvent at room temperature.
• The solvent should not react chemically with the compound to be purified.
• If the solvent is a low boiling liquid, its removal becomes easy.
• The solvent should have low viscosity.

Note: The commonly used solvents are water, ethyl alcohol, methyl alcohol, acetone, ether or their combinations.

Answer 2

Answer:

The criteria used to choose an appropriate recrystallization solvent includes: a.) finding a solvent with a high temperature coefficient. The solvent must not dissolve the compound at low temperatures (that includes room temperature), but must dissolve the compound at high temperatures.