Methods of purifications

Purification in a chemical context is the physical separation of a chemical substance of interest from foreign or contaminating substances. Pure results of a successful purification process are termed isolate. The following list of chemical purification methods should not be considered exhaustive.


This method can be applied to only those compounds that change their state directly from solid to vapour on heating .


The difference in the solubilities of an organiccompound and that of the impurities present in it, in a suitable solvent is the basis for this method of separation. A concentrated solution is prepared by dissolving the compound in a suitable solvent; the pure compound crystallizes out on cooling. The dissolved impurities are removed through filtration.


This method is mainly used for separating liquids with sufficient difference in their boiling points. It can also be used for separating volatile liquids from non volatile impurities.

Differential Extraction

It is used for the separation of organic compound present in an aqueous solution. The compound is removed from the aqueous solution by dissolving the compound into a highly soluble solvent forming a layer with the aqueous solution. The aqueous solution and the organic solvent should be immiscible and are separated using a separatory funnel.