Simple crystallisation - Purification of organic compounds

This is the most general technique used to purify organic solids. It is associated with the concept that whenever a crystal is made, it leads to leave out the impurities. For crystallisation, a appropriate solvent is one (a) that dissolves more of the substance at higher temperature as compared to at room temperature (b) where impurities are either insoluble or that to an extent that they stay in solution (in the mother liquor) upon crystallisation, (c) that is not highly inflammable and (d) which does not react chemically along with the compound to be crystallized. The most generally used solvents for crystallisation are: ether, water, chloroform, carbon- tetrachloride, petroleum ether acetone, benzene etc.